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1

Fatigue life prediction in composites  

Microsoft Academic Search

Because of the relatively large number of possible failure mechanisms in fibre reinforced composite materials, the prediction of fatigue life in a component is not a simple process. Several mathematical and statistical models have been proposed, but the experimental evidence to support them is limited so far. In this paper, an attempt has been made to fit experimental results to

R. J. Huston

1994-01-01

2

Distribution-Free Life Test Sampling Plans.  

National Technical Information Service (NTIS)

The paper describes life test sampling plans which assume only that the life distribution has increasing or decreasing failure rate. Tables are presented showing the minimum number of items necessary to assure a specified mean life or percentile life when...

S. S. Gupta

1966-01-01

3

Failure Distributions with Decreasing Mean Residual Life.  

National Technical Information Service (NTIS)

It is well known that the class of distributions with decreasing mean residual life (DMR) contains the class of distributions with increasing hazard rate (IHR). The study of DMR distributions has received little attention in the literature. Starting with ...

V. K. Murthy V. R. R. Uppuluri

1967-01-01

4

Characterization of Nonparametric Classes of Life Distributions.  

National Technical Information Service (NTIS)

This paper obtains characterizations of large classes of nonparametric life distributions, such as the increasing (decreasing) failure rate, increasing (decreasing) failure rate average, new better (worse) than used, etc., classes. The methods used differ...

N. A. Langberg R. V. Leon F. Proschan

1978-01-01

5

Families of Life Distributions Characterized by Two Moments.  

National Technical Information Service (NTIS)

The authors consider several classical notions of partial orderings among life distributions which have been used to describe aging properties, tail domination, etc. They show that if a distribution G dominates another distribution F in one of these parti...

J. Sethuraman M. C. Bhattacharjee

1988-01-01

6

Fatigue life prediction and failure mechanisms of composite materials  

Microsoft Academic Search

Fatigue life prediction and failure mechanisms of composite materials are studied based on the fatigue modulus concept and experimental results. Single-stress level fatigue life is predicted using generalized fatigue modulus degradation model and resultant strain failure criterion. Cumulative damage models defined by fatigue modulus and resultant strains are derived as functions of fatigue cycle and applied stress. This approach can

K. S. Han; W. Hwang

1992-01-01

7

Sex differences in body composition early in life  

Microsoft Academic Search

Background: Early development of the percentage of fat and muscle is rarely considered, but is important because excessive fat is related to the development of diabetes and other morbidities later in life. In pediatric medicine, there are few to no data comparing sex differences in body composition in the first months of life despite the fact that males are typically

David A. Fields; Sowmya Krishnan; Amy B. Wisniewski

2009-01-01

8

Life Test Sampling Plans for Normal and Lognormal Distributions  

Microsoft Academic Search

Sampling plans for truncated life tests from the normal and lognormal distributions are obtained. The tables of this paper give the minimum sample size necessary to assure a certain mean or median life when the experiment time is tied in advance. The modification necessary to assure any other quantile (percentile) of the distributions is obtained. Thus, sampling plans for establishing

Shanti S. Gupta

1962-01-01

9

Mean residual life of lifetime distributions  

Microsoft Academic Search

This paper characterizes the general behaviors of the MRL (mean residual lives) for both continuous and discrete lifetime distributions, with respect to their failure rates. For the continuous lifetime distribution with failure rates with only one or two change-points, the characteristic of the MRL depends only on its mean and failure rate at time zero. For failure rates with “roller

L. C. Tang; Y. Lu; E. P. Chew

1999-01-01

10

The Bayesian Predictive Distribution in Life Testing Models.  

National Technical Information Service (NTIS)

Prediction intervals for future observations in life testing situations have been derived. Expected-cover tolerance regions have been obtained. A Bayesian approach was given to such situations and the concept of the Bayesian predictive distribution was us...

I. R. Dunsmore

1973-01-01

11

Predictive Distributions in Life Tests under Competing Causes of Failure.  

National Technical Information Service (NTIS)

In competing risk life testing models, the units under test can fail due to one of several competing risks. The estimation of parameters in such compound models was investigated; predictive distributions and probabilities are derived for such situations, ...

G. A. Bancroft I. R. Dunsmore

1975-01-01

12

Financial evaluation of Participating Life Insurance Policies in distributed environments  

Microsoft Academic Search

In this paper we discuss the development of a parallel software for the numerical simulation of Participating Life Insurance Policies on distributed architectures. The use of stochastic pricing models, together with the request of solutions in a \\

Stefania Corsaro; Pasquale Luigi De Angelis; Zelda Marino; Francesca Perla; Paolo Zanetti

2008-01-01

13

Quality of Life and the Distribution of Wealth and Resources  

Microsoft Academic Search

Enhancing and sustaining the quality of human life is a primary goal of environmental, economic, and social policy. But how do we define and measure quality of life (QOL)? How is QOL distributed among people in the current generation and among the current and future generations? How do we model the dependence of QOL on the full range of environmental,

R. Costanza; J. Farley; P. Templet

14

Gamma Distribution in Acceptance Sampling Based on Life Tests  

Microsoft Academic Search

The gamma distribution is assumed as a model for lifetime. The problem of acceptance sampling when the life test is truncated at a pre- assigned time is discussed. For various acceptance numbers, various confidence levels, and various values of the ratio of the fixed experiment time to the specified mean life, the tables of this paper give the minimum sample

Shanti S. Gupta

1961-01-01

15

Lognormal and Weibull accelerated life test plans under distribution misspecification  

Microsoft Academic Search

In this article, we derive expressions for the asymptotic distribution of maximum likelihood estimators of model parameters in accelerated life tests (ALTs) when the model distribution is misspecified. We investigate results for two popular models, namely, the lognormal and Weibull Arrhenius-type ALT models. We propose test plan criteria based on asymptotic bias (ABias) and asymptotic mean squared error (AMSE) to

Francis G. Pascual; Grace Montepiedra

2005-01-01

16

Probabilistic fatigue life prediction of metallic and composite materials  

NASA Astrophysics Data System (ADS)

Fatigue is one of the most common failure modes for engineering structures, such as aircrafts, rotorcrafts and aviation transports. Both metallic materials and composite materials are widely used and affected by fatigue damage. Huge uncertainties arise from material properties, measurement noise, imperfect models, future anticipated loads and environmental conditions. These uncertainties are critical issues for accurate remaining useful life (RUL) prediction for engineering structures in service. Probabilistic fatigue prognosis considering various uncertainties is of great importance for structural safety. The objective of this study is to develop probabilistic fatigue life prediction models for metallic materials and composite materials. A fatigue model based on crack growth analysis and equivalent initial flaw size concept is proposed for metallic materials. Following this, the developed model is extended to include structural geometry effects (notch effect), environmental effects (corroded specimens) and manufacturing effects (shot peening effects). Due to the inhomogeneity and anisotropy, the fatigue model suitable for metallic materials cannot be directly applied to composite materials. A composite fatigue model life prediction is proposed based on a mixed-mode delamination growth model and a stiffness degradation law. After the development of deterministic fatigue models of metallic and composite materials, a general probabilistic life prediction methodology is developed. The proposed methodology combines an efficient Inverse First-Order Reliability Method (IFORM) for the uncertainty propogation in fatigue life prediction. An equivalent stresstransformation has been developed to enhance the computational efficiency under realistic random amplitude loading. A systematical reliability-based maintenance optimization framework is proposed for fatigue risk management and mitigation of engineering structures.

Xiang, Yibing

17

Development of life-test sampling plans for exponential distributions based on accelerated life testing  

Microsoft Academic Search

This paper presents a procedure for developing life-test sampling plans for exponential distributions based upon accelerated life testing(ALT). Type II censoring is assumed at each overstress level. The derived test statistic is shown to be a quotient of two independent random variables, each of which is a rational power of a Chi-square random variable. The distribution of the test statistic

Bong-Jin Yum; Sun-Ho Kim

1990-01-01

18

Life prediction and life extension of composite specimens using acoustic emission technique  

Microsoft Academic Search

This paper discusses a proof test procedure for estimating and extending the fatigue life of composite coupons. The estimates were based on the acoustic emission data collected during the described proof test procedure. A group of coupon specimens that included both undamaged as well as damaged ones were tested to verify the ability to estimate the fatigue durability. For majority

Francis Nkrumah; Mannur J. Sundaresan; Leonard Uitenham

2005-01-01

19

Life cycle assessment of carbon fiber-reinforced polymer composites  

Microsoft Academic Search

Purpose  The use of carbon fiber-reinforced polymer matrix composites is gaining momentum with the pressure to lightweight vehicles;\\u000a however energy intensity and cost remain major barriers to the wide-scale adoption of this material for automotive applications.\\u000a This study determines the relative life cycle benefits of two precursor types (conventional textile-type acrylic fibers and\\u000a renewable-based lignin), part manufacturing technologies (conventional SMC and

Sujit Das

2011-01-01

20

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

21

Life prediction and life extension of composite specimens using acoustic emission technique  

NASA Astrophysics Data System (ADS)

This paper discusses a proof test procedure for estimating and extending the fatigue life of composite coupons. The estimates were based on the acoustic emission data collected during the described proof test procedure. A group of coupon specimens that included both undamaged as well as damaged ones were tested to verify the ability to estimate the fatigue durability. For majority of the specimens tested the fatigue life of the coupons is inversely proportional to the cumulative AE energy collected during the proof test procedure. Based on the trend that was established, a new group of specimens AE based proof test was performed and using the acoustic emission response, the life was estimated. If one could estimate the fatigue life, it would be possible to identify those specimens, which are likely to fail prematurely. For such specimens it may be possible to extend the fatigue life by appropriate reduction in the cyclic load amplitude. This hypothesis was tested on the last group of specimens. The results obtained during the life extension phase actually show that it is possible to identify the specimens, which are likely to have short life and extend the fatigue life by subjecting them to less demanding load history.

Nkrumah, Francis; Sundaresan, Mannur J.; Uitenham, Leonard

2005-05-01

22

Limited failure-censored life test for the Weibull distribution  

Microsoft Academic Search

When the distribution of lifetimes is 2-parameter exponential, Balasooriya (1995) provided a failure-censored reliability sampling plan to save test time. This paper extends the Balasooriya sampling plan to the Weibull distribution and provides a limited failure-censored reliability sampling plan (LFCR) to do life testing when test facilities are scarce. The s-expected test time of the LFCR is computed, and the

Jong-Wuu Wu; Tzong-Ru Tsai; Liang-Yuh Ouyang

2001-01-01

23

A Class of Distributions Useful in Life Testing and Reliability.  

National Technical Information Service (NTIS)

A new class of distributions having a finite range that are useful in life testing and reliability is proposed. Methods of estimating the unknown parameters are studied. Explicit expressions for lower moments of order statistics in random samples of any s...

Z. Govindarajulu

1975-01-01

24

Stress distribution in antifriction composite materials  

Microsoft Academic Search

The optimum shape of hard inclusions in a composite material, irrespective of the magnitude of load and mode of its application to the surface, is a spheroid or ellipsoid of revolution. The characteristic linear size of a hard inclusion should be greater than the calculated diameter of a single spot of contact. If a composite material is to exhibit high

L. V. Zabolotnyi

1979-01-01

25

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

SciTech Connect

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 does not produce large pieces of heavy material that become dangerous projectiles, but generally produces a large number of pieces varying in size from chunks of delaminated laminates to dust and string- or straw-like matter. Composite flywheels are also thought to be more durable since composite materials generally perform very well under long-term and fatigue loading, frequently better than metals. However, the relatively limited experience that has been gained in using composite materials in high performance structures for long periods of time requires that special care be taken to verify the durability of any such design by experimental programs. An experimental program designed to establish the durability and life of the composite flywheel designs available at this time is presented. The objectives of the test program are as follows: to establish the durability and lifetime of flywheel rotors under conditions which include all of the essential details of the spectrum loading that rotors are likely to sustain as an energy storage device for various applications; to identify critical performance and durability characteristics which potentially limit the long term use of the rotor designs currently under development; and to develop test techniques and philosophies which can be used for fatigue testing of flywheels and to relate specimen data to rotor performance. Part I consists of the development of the test plan methodology.

Kulkarni, S.V.; Reifsnider, K.L.

1982-09-01

26

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

27

Creep-fatigue life prediction of in situ composite solders  

NASA Astrophysics Data System (ADS)

Eutectic tin-lead solder alloys subjected to cyclic loading at room temperature experience creep-fatigue interactions due to high homologous temperature. Intermetallic reinforcements of Ni3Sn4 and Cu6Sn5 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 straincontrolled 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.

1995-12-01

28

Formal Semantics of Composite Events for Distributed Environments  

Microsoft Academic Search

Languages for event specification in centralized systems and their semantics have received considerable attention in the literature. In contrast, very little work exists on extending the semantics of event specification languages to distributed environments. The paper provides a well-defined notion of distributed composite time stamps and their least restricted strict ordering are defined. The ordering is carefully chosen based on

Shuang Yang; Sharma Chakravarthy

1999-01-01

29

Composite fault location for Distribution Management Systems  

Microsoft Academic Search

The problem of fault location is an integral part of Distribution Management System (DMS) solutions. This paper presents a method of locating fault in unsymmetrical networks, including both radial and meshed parts of the network. The real-time information regarding the topological condition of the network and the status updates of the Fault Indicators are used as input to the fault

I. Dzafic; P. Mohapatra; H. T. Neisius

2010-01-01

30

LifeTrak®/ Lab and Distribution, Version 4.6.0  

Center for Biologics Evaluation and Research (CBER)

... LifeTrak®/ Lab and Distribution, Version 4.6.0. Applicant: Mediware Information Systems, Inc. ... Product: LifeTrak®/ Lab and Distribution, Version 4.6.0. ... More results from www.fda.gov/biologicsbloodvaccines/bloodbloodproducts/approvedproducts

31

Composite flywheel durability and life expectancy: test program  

SciTech Connect

The goals of this project are to: determine the durability and life expectancy of flywheel rotors; identify critical performance and durability characteristics that control the long-term service and safety of rotors and rotor containments; and develop test procedures that can be used to economically evaluate the performance of flywheels under cyclic loading in the laboratory and to relate that information to long-term service behavior. Approximately half the project is complete, including the following tasks: a material property data base has been assembled for each major material to be used in the flywheels; material property data has been characterized and modeled; the initial version of a generic test program has been designed; and some NDE characterization of all prototype composite flywheels rotors has been conducted.

Kulkarni, S.V.; Reifsnider, K.L.; Boyd, D.M.

1981-07-14

32

A Framework for Life-Cycle Cost Assessment of Composites in Construction  

Microsoft Academic Search

The slow acceptance of composite materials in construction could be attributed to the high initial cost of composites compared to conventional materials and the limited information on life-cycle cost. This paper presents a unique frame- work for a probable life-cycle cost assessment model for composite materials in construction. The proposed model utilizes the historical life-cycle performance data for conventional materials,

Makarand Hastak; Amir Mirmiran; Deepak Richard

2003-01-01

33

Compositional Distribution and Electronic Structure of Ternary Compound Semiconductor Nanocrystals  

NASA Astrophysics Data System (ADS)

We present a first-principles-based theoretical study of compositional distribution and the resulting electronic structure of ternary quantum dots (TQDs) of compound semiconductor nanocrystals. The analysis is based on first-principles Density Functional Theory (DFT) calculations of atomic and electronic structure and on Monte Carlo (MC) simulations of compositional distribution according to DFT-parameterized valence force field models. We report results for ZnSe1-xSx (type-I), ZnSe1-xTex (type-II), and InxGa1-xAs (Reverse type-I) TQDs with nm-scale diffusion lengths and large surface-to-volume ratios. The equilibrium compositional distribution is predicted as a function of overall composition (x) and TQD diameter and its impact on the electron density distribution, electronic density of states, and band gap of the TQDs is analyzed. We find that thermodynamically stable atomic distributions allow for optimal band-gap tenability and wave function confinement in TQDs. Our findings explain the possibility for compositional redistribution that may cause, over time, favorable or adverse changes of the TQD electronic properties with far reaching implications for the synthesis and applications of such nanostructures in devices.

Pandey, Sumeet; Maroudas, Dimitrios

2012-02-01

34

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 Banks...DEPARTMENT OF THE TREASURY SALES OF CREDIT LIFE INSURANCE § 2.3 Distribution of credit life insurance income. (a) Distribution of...

2013-01-01

35

Classes of Discrete Decreasing and Increasing Mean-Residual-Life Distributions  

Microsoft Academic Search

Discrete failure-time distributions can be appropriate to model lifetimes. This paper represents two well-known non-parametric families of discrete distributions: decreasing and increasing mean-residual-life. It provides two parametric families of discrete distributions which are suitable for fitting decreasing and increasing mean-residual-life models to discrete life-test data.

Nader Ebrahimi

1986-01-01

36

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

2013-05-22

37

A Framework for Event Composition in Distributed Systems  

Microsoft Academic Search

For large-scale distributed applications such as internet-wide or ubiquitous systems, event-based communication is an eectiv e messag- ing mechanism between components. In order to handle the large volume of events in such systems, composite event detection enables application components to express interest in the occurrence of complex patterns of events. In this paper, we introduce a general composite event detection

Peter R. Pietzuch; Brian Shand; Jean Bacon

2003-01-01

38

Distributed Feature Composition: A Virtual Architecture for Telecommunications Services  

Microsoft Academic Search

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

Michael Jackson; Pamela Zave

1998-01-01

39

Distributed Mixers with Composite Right\\/Left-Handed Transmission Lines  

Microsoft Academic Search

The use of composite right\\/left-handed transmission lines (CRLH-TLs) in distributed mixers, instead of the usual right-handed transmission lines (RH-TLs) is explored. The theoretical performance of such mixers is analyzed in two cases: when CRLH-TLs are used in both drain and gate lines, and when a CRLH-TL is introduced only in the gate line. Both cases show that innovative distributed mixer

J. Mata-Contreras; T. M. Martin-Guerrero; C. Camacho-Penalosa

2006-01-01

40

A hybrid model for fatigue life estimation of polymer matrix composites  

NASA Astrophysics Data System (ADS)

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

Uleck, Kevin R.

41

Compositional Distribution of the Near-Earth Object Population  

NASA Astrophysics Data System (ADS)

We will highlight our findings to identify source regions for NEOs and PHAs and the size dependence of their compositional distribution as it pertains to the role of the Yarkovsky effect in delivering bodies from the main-belt to near-Earth space.

Binzel, R. P.; DeMeo, F. E.; Lockhart, M.; Spivakovsky-Gonzalez, P.; Polishook, D.; Tokunaga, A.; Thomas, C. A.; Rivkin, A. S.; Bus, S. J.; Birlan, M.; Vernazza, P.

2012-05-01

42

Life cycle inventory analysis of fresh tomato distribution systems in Japan considering the quality aspect  

Microsoft Academic Search

Life cycle of fresh tomato was evaluated to determine CO2 emissions during its cultivation and distribution. Low temperature (LT) and modified-atmosphere packaging (MAP) were compared for their effect on quality. Road and sea transport were also compared. The method of cultivation and transport and the distribution systems affected the overall life cycle inventory (LCI, CO2 emissions). Life cycle inventory was

Poritosh Roy; Daisuke Nei; Hiroshi Okadome; Nobutaka Nakamura; Takahiro Orikasa; Takeo Shiina

2008-01-01

43

Life-cycle cost assessment model of composite materials in construction  

Microsoft Academic Search

To further enhance the application of fiber reinforced composites in construction, it will be important to assess the life-cycle costs of replacing conventional construction materials with advanced composites. However, the lack of sufficient reference data or maintenance records for advanced-composite applications in construction makes it difficult to make a credible assessment for life-cycle costs. The available reference data are limited

TaeHoon Hong

2005-01-01

44

Size and composition distribution of atmospheric particles in southern California  

SciTech Connect

Continuous measurements of single particle size and chemical composition in the atmosphere are made using aerosol time-of-flight mass spectrometers (ATOFMS) operated alongside more conventional reference air sampling instruments at a network of three urban air monitoring sites in southern California. Electrical aerosol analyzers and optical particle counters are employed to acquire continuous particle size distribution data, and inertial impactor and bulk filter samples with 4-h resolution are taken for determination of particle size and chemical composition. Filter and impactor samples also are taken upwind of the air basin at Santa Catalina Island in order to characterize background air quality. The airborne particle size and composition distribution as measured by the cascade impactors at inland sites differ from that over the ocean principally due to depletion of sea salt particles accompanied by the addition of fine carbon-containing particles and secondary aerosol nitrate. Data from the ATOFMS systems create a continuous time series of sodium-, ammonium-, nitrate-, and carbon-containing particle counts that provide a high-resolution view of differences in particle composition as a function of location in the air basin. Results show that the characteristic peak in the Los Angeles area aerosol mass distribution in the 0.2--0.3-{micro}m size range observed during the 1987 SCAQS experiments has been reduced, consistent with reductions in diesel soot and elemental carbon emissions since that time.

Hughes, L.S.; Allen, J.O.; Kleeman, M.J. [and others

1999-10-15

45

Using pseudo amino acid composition to predict protein subcellular location: approached with amino acid composition distribution  

Microsoft Academic Search

Summary.  In the Post Genome Age, there is an urgent need to develop the reliable and effective computational methods to predict the\\u000a subcellular localization for the explosion of newly found proteins. Here, a novel method of pseudo amino acid (PseAA) composition,\\u000a the so-called “amino acid composition distribution” (AACD), is introduced. First, a protein sequence is divided equally into\\u000a multiple segments. Then,

J.-Y. Shi; S.-W. Zhang; Q. Pan; G.-P. Zhou

2008-01-01

46

Data Acquisition and Control for Multiple Composite Life Tests.  

National Technical Information Service (NTIS)

Strength durability of composite materials has many current Navy applications including rocket motor cases, pressure vessels for submarine flasks, energy storage for space applications and for pilot ejection seats. The primary effect of composite aging ca...

J. W. Emery

1988-01-01

47

Distributed photoacoustic system for cure monitoring of composites  

NASA Astrophysics Data System (ADS)

In this paper we describe a laser ultrasonic system for real-time monitoring of the degree of cure of a graphite-epoxy composite part during manufacturing. The system is integrated with a Resin-Transfer Molding (RTM) machine, and contains (i) a fiberized laser ultrasonic source, and (ii) an embedded ultrasonic sensor based on an intrinsic fiber optic Sagnac interferometer. Bulk ultrasonic waves generated by the laser source are transmitted into the composite structure and are subsequently detected by the embedded ultrasonic sensor. The degree of cure can be obtained from measurements of ultrasonic velocity and attenuation in the composite part. The use of an optical switch in the fiber optic delivery system of the laser ultrasonic source allows ultrasonic generation at several locations of the composite part. In this paper we discuss the design of the laser ultrasonic source and the sensor optimized for cure monitoring applications, and their integration with the RTM mold. The results of ultrasonic measurements during manufacturing of a composite specimen are presented. Our results show that laser ultrasonics offer distinct advantages for manufacturing of modern composite structures including the ability to operate in a high temperature and high pressure environment and provide distributed sensing that can cover critical areas of a component.

Fomitchov, Pavel A.; Kim, Yeong K.; Kromine, Alexei K.; Krishnaswamy, Sridhar; Achenbach, Jan D.; Daniel, Isaac M.

2001-07-01

48

Prey nutrient composition has different effects on Pardosa wolf spiders with dissimilar life histories  

Microsoft Academic Search

The nutritional composition of prey is known to influence predator life histories, but how the life history strategies of\\u000a predators affect their susceptibility to nutrient imbalance is less investigated. We used two wolf spider species with different\\u000a life histories as model predators: Pardosa amentata, which have a fixed annual life cycle, and Pardosa prativaga, which reproduce later and can extend

Kim Jensen; David Mayntz; Søren Toft; David Raubenheimer; Stephen J. Simpson

2011-01-01

49

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

50

Wear and Life Characteristics of Microwave-Sintered Copper-Graphite Composite  

NASA Astrophysics Data System (ADS)

Copper-graphite composite is an important tribological material used in electrical sliding contact applications like electrical brushes in motors and generators. The electrical sliding contact experiences multiple stresses such as mechanical pressure and temperature. Traditional life tests under normal operating condition would be a time-consuming process due to the longer expected life of the composite. Accelerated wear testing was carried out to evaluate the life characteristics of the composite. This work focuses on evaluation of tribological performance of microwave-sintered copper-graphite composite using accelerated wear testing methodology using high temperature pin-on-disc tribometer. Microstructural studies of worn out surfaces were carried out using SEM with EDAX. Reliability and analysis on life characteristics were performed on the time-to-failure data using temperature-nonthermal-accelerated life-stress model. The obtained times-to-failure data from the accelerated wear testing was extrapolated to normal usage condition. Temperature and pressure are significantly affecting the wear performance. Self-lubricating action of graphite and improvement in wear resistance is helpful in extending the life of copper graphite composite. The life of the composite obtained through testing at mean and 99% reliability are 18,725 and 16,950 h, respectively.

Rajkumar, K.; Aravindan, S.; Kulkarni, M. S.

2012-11-01

51

Prey nutrient composition has different effects on Pardosa wolf spiders with dissimilar life histories.  

PubMed

The nutritional composition of prey is known to influence predator life histories, but how the life history strategies of predators affect their susceptibility to nutrient imbalance is less investigated. We used two wolf spider species with different life histories as model predators: Pardosa amentata, which have a fixed annual life cycle, and Pardosa prativaga, which reproduce later and can extend development across 2 years. We fed juvenile spiders of the two species ad libitum diets of one of six Drosophila melanogaster fly types varying in lipid:protein composition during three instars, from the start of the second instar until the fifth instar moult. We then tested for interactions between predator species and prey nutrient composition on several life history parameters. P. amentata completed the three instars faster and grew larger carapaces and heavier body masses than P. prativaga, but the two species responded differently to variation in prey lipid:protein ratio. Duration of the instars increased when feeding on protein-poor prey in P. amentata, but was unaffected by diet in P. prativaga. Likewise, the effect of diet on body composition was more pronounced in P. amentata than in P. prativaga. Prey nutrient composition thus affected the two species differently. During macronutrient imbalance P. amentata appear to prioritize high growth rates while experiencing highly variable body compositions, whereas P. prativaga maintain more constant body compositions and have slower growth. These can be seen as different consequences of a fixed annual and a plastic annual-biennial life cycle. PMID:20976606

Jensen, Kim; Mayntz, David; Toft, Søren; Raubenheimer, David; Simpson, Stephen J

2010-10-26

52

Matrix Properties Controlling Torsional Fatigue Life of Fiber Reinforced Composites.  

National Technical Information Service (NTIS)

The fatigue life of torsionally stressed N.O.L. rings can be correlated with basic properties of the matrix. In a constant maximum deformation mode, fatigue life correlates, in a nonlinear fashion, with the ultimate strain of the matrix. Performance is al...

R. E. Lavengood R. M. Anderson

1969-01-01

53

Composition and Analysis of a Model Waste for a Celss (Controlled Ecological Life Support System).  

National Technical Information Service (NTIS)

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).

T. Wydeven

1983-01-01

54

Bayesian life test planning for the Weibull distribution with given shape parameter  

Microsoft Academic Search

This paper describes Bayesian methods for life test planning with Type II censored data from a Weibull distribution, when the Weibull shape parameter is given. We use conjugate prior distributions and criteria based on estimating a quantile of interest of the lifetime distribution. One criterion is based on a precision factor for a credibility interval for a distribution quantile and

Yao Zhang; William Q. Meeker

2005-01-01

55

New acceptance sampling plans based on life tests for Birnbaum–Saunders distributions  

Microsoft Academic Search

In this paper, we consider the Birnbaum–Saunders distribution as a life model to develop various acceptance sampling schemes based on the truncated life tests. We develop the double sampling plan and determine the design parameters satisfying both the producer's and consumer's risks simultaneously for the specified reliability levels in terms of the mean ratio to the specified life. We also

Muhammad Aslam; Chi-Hyuck Jun; Munir Ahmad

2011-01-01

56

On a Life Distribution Family Based on Total Time on Test on Average: NBUTA  

Microsoft Academic Search

A new class of life distributions, namely new better than used in the total time on test on average transform ordering (TTTA), is introduced. The relationship of this class to other classes of life distributions, and closure properties under some reliability operations, are discussed. We provide a simple argument based on stochastic orders that the class is closed under the

A. N. Ahmed; H. M. Hewedi; E. A. Rakha; E. M. Shokry

57

On changing points of mean residual life and failure rate function for some generalized Weibull distributions  

Microsoft Academic Search

The failure rate function and mean residual life function are two important characteristics in reliability analysis. Although many papers have studied distributions with bathtub-shaped failure rate and their properties, few have focused on the underlying associations between the mean residual life and failure rate function of these distributions, especially with respect to their changing points. It is known that the

M Xie; T. N Goh; Y Tang

2004-01-01

58

MAE: An Integrated Design Tool for Failure and Life Prediction of Composites  

Microsoft Academic Search

An advanced strength and life prediction tool, MAE, was developed for the analysis and design of composite structures and components. The MAE integrates three theories and methods: micromechanics of failure (MMF), an accelerated testing method (ATM), and an evolution of damage (EOD). The MAE can serve as a useful tool to predict damage initiation, progression and life under various durability

Sangwook Sihn; Jin Woo Park

2008-01-01

59

Ceramic Matrix Composites (CMC) Life Prediction Method Development.  

National Technical Information Service (NTIS)

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 co...

S. R. Levine A. M. Calomino J. R. Ellis M. C. Halbig S. K. Mital P. L. Murthy E. J. Opila D. J. Thomas L. U. Thomas-Ogbuji M. J. Verrilli

2000-01-01

60

Future Experimental Methods Needed to Verify Composite Life-cycle Simulations  

Microsoft Academic Search

The future experimental methods needed for composite life-cycle are identified by computationally simulating the fracture\\u000a of an integrally stiffened composite structure. The simulation describes events occurring during the fracture progression\\u000a at all composite structure scales, the fracture modes that contribute to those events and the respective local failure mechanisms.\\u000a The fracture modes in their respective scales provide opportunities to suggest

CHRISTOS C. CHAMIS; Levon Minnetyan

61

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

62

Particle distribution in a polymer nano-composite  

SciTech Connect

We use the hybrid particle-Self Consistent Field calculation (hybrid particle-SCF) to study the distribution of particles in a multi-block copolymer nano-composite. Using the static approach, we first find the effective interaction potential between the nano-particles and the polymer. The interaction has an entropic and an enthalpic component. The dynamical simulation confirms that the distribution of particles has a maximum at the minima of the interaction potential. We also study the situation where the nano-particles are distributed in a blend of AB diblock and A homopolymer. In this case, for large homopolymer concentration (larger than 20%), an interface is created between components that are identical, but they come from different types of polymer chains (i.e. the AB diblock or the A homopolymer). We find that the interaction potential has a minimum in this A/A interface which is of pure entropic origin. Furthermore the dynamical simulation reveals that the distribution of nano-particles has a maximum in the area around this interface.

Maniadis, Panagiotis [Los Alamos National Laboratory; Kober, Edward M [Los Alamos National Laboratory; Lookman, Turab [Los Alamos National Laboratory; Tsimpanogiannis, I [NCSR, GREECE

2009-01-01

63

Gangliosides in rat kidney: composition, distribution, and developmental changes.  

PubMed

Gangliosides in rat kidney were analyzed for their composition, regional distribution, and developmental changes. Renal tissue from 7-week-old rats showed a GM3-dominant pattern with GD3 and several minor ganglioside components including GM4, GM2, GD1a, and an unknown ganglioside (ganglioside X). The tissue also contained c-series gangliosides that included GT3 as the main component with GT2 in a lesser amount. Ganglioside analysis of cortical and medullary regions of renal tissue suggested the restricted localization of some gangliosides. While GM4 and GD3 were enriched in the cortical region, GM2 was distributed mainly in the medullary area. Renal gangliosides showed unique developmental profiles during a period from Embryonic Day 20 (E20) to 7 weeks postnatal. The content of renal gangliosides increased from E20, reached the highest around Postnatal Day 1, and thereafter, decreased rapidly to the adult level. The ratio of N-glycolylneuraminic acid to total sialic acids in gangliosides tended to change in inverse proportion to the amount of total sialic acids. The composition of major gangliosides in renal tissues shifted from GD3-dominant to GM3-dominant patterns with advancing ages. While GM1 was expressed only at early stages of the development, GM4, GM2, and ganglioside X appeared after Postnatal Day 3. The expression of c-series gangliosides was less affected through the period examined. These results suggest that gangliosides may be implicated with development and function of rat kidney. PMID:11360994

Saito, M; Sugiyama, K

2001-02-01

64

Mineral composition in arid soils: A global distribution (Invited)  

NASA Astrophysics Data System (ADS)

Dust storms and subsequent mineral aerosol transport and deposition are mainly driven by meso- and synoptic-scale atmospheric processes. It is therefore essential that dust aerosol process and background atmospheric conditions are observed and modeled spatially and temporally as better as possible. Behavior of dust in its interactions with the environment is to a large extent determined by mineral composition of dust particles. Fractions of various minerals in the aerosol are very much dependent on mineral composition of arid soils, therefore the requirement for high-resolution specification of mineral and physical properties in soil sources holds as well. Dust aerosol is a complex mixture of minerals having high variability of their physical and chemical properties. Current information on geographical distribution of minerals in arid soils is available with unsatisfactorily resolution and this work aims to improve it. In this work we generate a high-resolution global data set of effective mineral contents (GMINER30), as more suitable input for the regional dust/mineral modelling simulations. The mapped minerals considered here are eight minerals (illite, kaolinite, smectite, calcite, quartz, feldspar, hematite and gypsum) distributed over clay and silt populations. GMINER30 could be used as input data in atmospheric dust models to provide emission fluxes for various mineral fractions.

Nickovic, S.; Vukovic, A.; Vujadinovic, M.; Pejanovic, G.; Djurdjevic, V.; Dacic, M.

2010-12-01

65

Determining molecular mass distributions and compositions of functionalized dendrimer nanoparticles  

PubMed Central

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

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

2009-01-01

66

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

Microsoft Academic Search

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 ofNemalion helminthoides is

C. van den Hoek

1982-01-01

67

Accelerated life-tests for intermittent destructive inspection, with logistic failure-distribution  

Microsoft Academic Search

Statistically-optimal accelerated life-test plans are suggested for items whose lifetime follows a logistic distribution. Both the scale and location parameters of the lifetime distribution are functions of the stress level. The test plans accommodate intermittent destructive sampling. The number of sampled items which fail to pass the test at the time of each inspection follows a hypergeometric distribution; the number

So Young Sohn

1997-01-01

68

A Bayesian life test sampling plan for products with Weibull lifetime distribution sold under warranty  

Microsoft Academic Search

A Bayesian life test sampling plan is considered for products with Weibull lifetime distribution which are sold under a warranty policy. It is assumed that the shape parameter of the distribution is a known constant, but the scale parameter is a random variable varying from lot to lot according to a known prior distribution. A cost model is constructed which

Y. I. Kwon

1996-01-01

69

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

Microsoft Academic Search

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

John M. Pandolfi; Peter R. Minchin

1996-01-01

70

The Distribution of Stars Most Likely to Harbor Intelligent Life  

Microsoft Academic Search

Simple heuristic models and recent numerical simulations show that the probability of habitable planet formation increases with stellar mass. We combine those results with the distribution of main-sequence stellar masses to obtain the distribution of stars most likely to possess habitable planets as a function of stellar lifetime. We then impose the self-selection condition that intelligent observers can only find

Daniel P. Whitmire; John J. Matese

2009-01-01

71

Life extension for electrical power distribution systems using vacuum technology  

Microsoft Academic Search

Three alternatives for upgrading old equipment are discussed. Retrofitting with vacuum arc interrupter technology is the most cost effective and offers many advantages over older air-magnetic interrupters. These include simpler design, fewer parts and less maintenance, readily available parts, high reliability, extended insulation life and safety. The authors address modernization options available to industry specifically in the area of electrical

A. D. Storms; D. D. Shipp

1991-01-01

72

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

Code of Federal Regulations, 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

73

Thermal life cycle testing of a titanium matrix composite  

NASA Astrophysics Data System (ADS)

The experimental procedures used at the Wright Labs, Wright-Patterson Air Force Base, to test a titanium-matrix composite (TMC) panel representing a fuselage section of a hypersonic aerospace vehicle are described together with results of these tests. The test objective was to evaluate the TMC panel's durability to thermal fatigue loading and to gain qualitative and quantitative information on its response. Results showed that, except for some slight warpage over the hat sections of the corrugated skin, the test panel successfully sustained 150 thermal cycles without any apparent damage.

Hart, David

74

Estimation for a Family of Life Distributions with Applications to Fatigue.  

National Technical Information Service (NTIS)

The estimation problem is studied for a new two-parameter family of life length distributions which has been previously derived from a model of fatigue crack growth. Maximum likelihood estimates of both parameters are obtained and iterative computing proc...

S. C. Saunders Z. W. Birnbaum

1968-01-01

75

Life cycle assessment of ACQ-treated lumber with comparison to wood plastic composite decking  

Microsoft Academic Search

A cradle-to-grave life cycle assessment was done to identify the environmental impacts related to alkaline copper quaternary (ACQ)-treated lumber used for decking and to determine how the impacts compare to the primary alternative product, wood plastic composite (WPC) decking. A model of ACQ-treated lumber life cycle stages was created and used to calculate inputs and outputs during the lumber production,

Christopher A. Bolin; Stephen Smith

2011-01-01

76

Fatigue-life prediction of SiC aluminum composite using a Weibull model  

Microsoft Academic Search

The feasibility of the acoustic emission technique in predicting the residual fatigue life of 6061-T6 aluminum matrix composite reinforced with 15vol.% SiC particulates (SiCp) is presented. Fatigue damages corresponding to 40, 60 and 80% of total fatigue life were induced at a cyclic stress amplitude. The specimens with and without fatigue damage were subjected to tensile tests. The acoustic emission

D. Shan; H. Nayeb-Hashemi

1999-01-01

77

Performance-based optimal design and rehabilitation of water distribution networks using life cycle costing  

Microsoft Academic Search

A new multiobjective formulation is proposed for the optimal design and rehabilitation of a water distribution network, with minimization of life cycle cost and maximization of performance as objectives. The life cycle cost is considered to comprise the initial cost of pipes, the cost of replacing old pipes with new ones, the cost of cleaning and lining existing pipes, the

Nirmal Jayaram; K. Srinivasan

2008-01-01

78

Acceptance Sampling Plans from Truncated Life Tests Based on the Birnbaum-Saunders Distribution for Percentiles  

Microsoft Academic Search

Time to failure due to fatigue is one of the common quality characteristics in material engineering applications. In this article, acceptance sampling plans are developed for the Birnbaum–Saunders distribution percentiles when the life test is truncated at a pre-specified time. The minimum sample size necessary to ensure the specified life percentile is obtained under a given customer's risk. The operating

Y. L. Lio; Tzong-Ru Tsai; Shuo-Jye Wu

2010-01-01

79

Acceptance Sampling Plans from Truncated Life Tests Based on the Generalized Birnbaum–Saunders Distribution  

Microsoft Academic Search

In this article, we develop acceptance sampling plans when the life test is truncated at a pre-fixed time. The minimum sample size necessary to ensure the specified median life is obtained by assuming that the lifetimes of the test units follow a generalized Birnbaum–Saunders distribution. The operating characteristic values of the sampling plans as well as producer's risk are presented.

N. Balakrishnan; Víctor Leiva; Jorge López

2007-01-01

80

DESIGN OF FAILURE-CENSORED ACCELERATED LIFE-TEST SAMPLING PLANS FOR LOGNORMAL AND WEIBULL DISTRIBUTIONS  

Microsoft Academic Search

This paper considers the design of life-test sampling plans based on failure-censored accelerated life tests for products with lognormal and Weibull lifetime distributions. Two levels of stress higher than the use condition stress, high and low, are used. The sample size, sample proportion allocated to each stress level, and the lot acceptability constant which satisfy the producer's risk and consumer's

D. S. BAI; J. G. KIM; Y. R. CHUN

1993-01-01

81

REPORTS The Galactic Habitable Zone and the Age Distribution of Complex Life in the Milky Way  

Microsoft Academic Search

We modeled the evolution of the Milky Way Galaxy to trace the distribution in space and time of four prerequisites for complex life: the presence of a host star, enough heavy elements to form terrestrial planets, sufficient time for biological evolution, and an environment free of life-extinguishing supernovae. We identified the Galactic habitable zone (GHZ) as an annular region between

C. L. Cepko; C. P. Austin; X. Yang; M. Alexiades; D. Ezzeddine

82

Failure-censored accelerated life test sampling plans for Weibull distribution under expected test time constraint  

Microsoft Academic Search

This paper considers the design of life-test sampling plans based on failure-censored accelerated life tests. The lifetime distribution of products is assumed to be Weibull with a scale parameter that is a log linear function of a (possibly transformed) stress. Two levels of stress higher than the use condition stress, high and low, are used. Sampling plans with equal expected

J. G. Kim

1995-01-01

83

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

84

Bayesian life test sampling plans for the two parameter exponential distribution  

Microsoft Academic Search

In this paper we consider the determination of Bayesian life test acceptance sampling plans for finite lots when the underlying lifetime distribution is the two parameter exponential. It is assumed that the prior distribution is the natural conjugate prior, that the costs associated with the actions accept and reject are known functions of the lifetimes of the items, and that

A. M. Nigm; M. A. Ismail

1985-01-01

85

Magnetostriction in composites of LiFe5O8-BaTiO3  

NASA Astrophysics Data System (ADS)

Polycrystalline lithium ferrite, LiFe5O8 was prepared by adopting two preparation techniques, the solid-state double sintering method and the sol-gel method. This ferrite powder was thoroughly mixed with barium titanate, BaTiO3 for preparation of di-phasic composites of lithium ferrite and barium titanate. X-ray diffraction study of these composites revealed the presence of both the phases. Magnetostriction of these composites was measured in varying magnetic fields. The value of magnetostriction for the composites prepared by the sol-gel method was found to be higher than the values obtained in case of composites prepared by the solid-state method. Magnetostriction was found to decrease with increasing content of barium titanate. The saturation field was found to increase with the introduction of barium titanate.

Sarah, P.; Suryanarayana, S. V.

2003-03-01

86

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

Microsoft Academic Search

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

M. Mirdamadi; W. S. Johnson

1994-01-01

87

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

ERIC Educational Resources Information Center

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

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

2009-01-01

88

Prediction of creep-rupture life of unidirectional titanium matrix composites subjected to transverse loading  

SciTech Connect

Titanium matrix composites (TMCs) incorporating unidirectional fiber reinforcement are considered as enabling materials technology for advanced engines which require high specific strength and elevated temperature capability. The resistance of unidirectional TMCs to deformation under longitudinally applied sustained loading at elevated temperatures has been well documented. Many investigators have shown that the primary weakness of the unidirectional TMC is its susceptibility to failure under very low transverse loads, especially under sustained loading. Hence, a reliable model is required to predict the creep-rupture life of TMCs subjected to different transverse stress levels over a wide range of temperatures. In this article, the authors propose a model to predict the creep-rupture life of unidirectional TMC subjected to transverse loading based on the creep-rupture life of unidirectional TMC subjected to transverse loading based on the creep-rupture behavior of the corresponding fiberless matrix. The model assumes that during transverse loading, the effective load-carrying matrix ligament along a row of fibers controls the creep-rupture strength and the fibers do not contribute to the creep resistance of the composite. The proposed model was verified using data obtained from different TMC fabricated using three matrix compositions, which exhibited distinctly different types of creep behavior. The results show that the creep-rupture life of the transverse TMC decreases linearly with increasing ratio of the fiber diameter to the ply thickness. The creep-rupture life is also predicted to be independent of fiber spacing along the length of the specimen.

John, R.; Khobaib, M. [Univ. of Dayton Research Inst., OH (United States); Smith, P.R. [WL/MLLN, Wright-Patterson AFB, OH (United States). Materials Directorate

1996-10-01

89

Effective nonlinear optical properties of shape distributed composite media  

NASA Astrophysics Data System (ADS)

The effective linear and nonlinear optical properties of metal/dielectric composite media, in which ellipsoidal metal inclusions are distributed in shape, are investigated. The shape distribution function P(L_x,L_y) is assumed to be 2?^{-2}?(L_x-1/3+?/3)?(L_y-1/3+?/3)?(2/3+?/3-L_x-L_y), where ?(\\cdot\\cdot\\cdot) is the Heaviside function, ? is the shape variance and L_i are the depolarization factors of the ellipsoidal inclusions along i-symmetric axes (i=x,y). Within the spectral representation, we adopt Maxwell-Garnett type approximation to study the effect of shape variance ? on the effective nonlinear optical properties. Numerical results show that both the effective linear optical absorption ?sim? Im (sqrt{?_e^{(0)}}) and the modulus of the effective third-order optical nonlinearity enhancement |?_e^{(3)}|/?_1^{(3)} exhibit the nonmonotonic behavior with ?. Moreover, with increasing ?, the optical absorption and the nonlinearity enhancement bands become broad, accompanied with the decrease of their peaks. The adjustment of ? from 0 to 1 allows us to examine the crossover behavior from no separation to large separation between optical absorption and nonlinearity enhancement peaks. As ?rightarrow 0, i.e., the ellipsoidal shape deviates slightly from the spherical one, the dependence of |?_e^{(3)}|/?_1^{(3)} on ? becomes strong first and then weak with increasing the imaginary part of inclusions' dielectric constant. In the dilute limit, the exact formula for the effective optical nonlinearity is derived, and the present approximation characterizes the exact results better than old mean field one does.

Gao, Lei; Huang, Yanyan

2003-05-01

90

Creep rupture life prediction of short fiber-reinforced metal matrix composites  

SciTech Connect

The creep rupture life of an Al/Al{sub 2}O{sub 3} composite and its creep behavior were studied. The metal matrix composite was produced by using a squeeze casting technique. High-temperature tensile tests and creep experiments were conducted on a 15 vol pct alumina fiber-reinforced AC2B Al alloy metal matrix composite (MMC). The high-temperature tensile strength of Al/Al{sub 2}O{sub 3} composite is 14 pct higher than that of an AC2B Al alloy. The steady-state creep rate and the creep life were measured. The stress exponent in Norton`s equation and the activation energy were computed. The stress exponents of the AC2B and Al/Al{sub 2}O{sub 3} composites were found to be 4 and 12.3, respectively. The activation energy of the AC2B and Al/Al{sub 2}O{sub 3} composites were found to be 242.74 and 465.35 kJ/mol, respectively. A new equation for predicting creep life was established, which was based on the conservation of the creep strain energy. The theoretical predictions were compared with those of the experiment results, and a good agreement was obtained. It was found that the creep life is inversely proportional to the (n + 1)th power of the applied stress and strain failure energy of creep is conserved. The creep fracture surface, examined by scanning electron microscopy (SEM), showed that the MMC specimen failed in a brittle manner.

Nam, H.W.; Han, K.S. [Pohang Univ. of Science and Technology (Korea, Republic of). Dept. of Mechanical Engineering

1998-07-01

91

Symptom Control May Improve Food Intake, Body Composition, and Aspects of Quality of Life After Gastrectomy in Cancer Patients  

Microsoft Academic Search

That severe malnutrition affects body function and psychological well-being is well documented. We addressed the question of whether quality of life relates to changes in variables such as food intake, body composition, and gastrointestinal symptomatology after gastrectomy for gastric cancer. Thirty-two patients undergoing gastric resection had their dietary intake, body composition, and specific and general aspects of quality of life

B. Liedman; J. Svedlund; M. Sullivan; L. Larsson; L. Lundell

2001-01-01

92

Describing variability of MSW composition data with the log-logistic distribution.  

PubMed

Variations in solid waste composition data are necessary as inputs to solid waste planning, yet uncertainty exists regarding which probability distributions might be generally valuable to describe the variability. Twenty-two detailed analyses of solid waste from British Columbia, Canada, were fitted to distributions using the BestFit software. Alternative distributions were ranked based on three goodness-of-fit parameters and twelve waste fractions. The log-logistic distribution was found to be the most able to fit over the wide range of composition types considered. The results were demonstrated to be insensitive to the number of waste components or to the choice of a two- or three-parameter distribution. Although other distributions were able to better match the waste composition for individual waste types, the log-logistic distribution was demonstrated to fit, overall, a wide variety of waste composition types. PMID:18727327

Milke, Mark W; Wong, Vincent; McBean, Edward A

2008-08-01

93

The Galactic Habitable Zone and the Age Distribution of Complex Life in the Milky Way  

Microsoft Academic Search

We modeled the evolution of the Milky Way to trace the distribution in space\\u000aand time of four prerequisites for complex life: the presence of a host star,\\u000aenough heavy elements to form terrestrial planets, sufficient time for\\u000abiological evolution and an environment free of life-extinguishing supernovae.\\u000aWe identified the Galactic habitable zone (GHZ) as an annular region between 7

Charles H. Lineweaver; Yeshe Fenner; Brad K. Gibson

2004-01-01

94

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

PubMed Central

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

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

2012-01-01

95

Fatigue Tests Of Cracked Reinforced Concrete Slabs For Estimating The Service Life Of Composite Bridge Decks  

Microsoft Academic Search

A large-scale experimental program was co-sponsored by the main French owners of composite bridges in order to estimate the fatigue service life of cracked decks, as it occurs due to restrained shrinkage of concrete. The fatigue tests were carried out at the Structures Laboratory of LCPC on six transversally cracked reinforced concrete slabs largely equipped with gauges and sensors. 1.4

François Toutlemonde; Guillaume Ranc

2001-01-01

96

Polysaccharide-based composite coating formulations for shelf-life extension of fresh banana and mango  

Microsoft Academic Search

The effects of four different composite coating formulations based on polysaccharides on maintaining quality and an extended shelf-life of banana and mango at 27DŽ °C were investigated and compared with commercial Waxol-coated and uncoated fruits. The formulations consisted of modified starch, cellulose and chitosan, blended with a suitable lipid component and a wetting agent. Quality parameters measured included firmness, total

F. S. Kittur; N. Saroja; Habibunnisa; R. Tharanathan

2001-01-01

97

Modelling low-cycle fatigue life of particulate-reinforced metal-matrix composites  

Microsoft Academic Search

A low-cycle fatigue life prediction model for particulate-reinforced metal-matrix composites (MMCs) is presented. The low-cycle fatigue behaviour of particulate-reinforced MMCs is treated as a localised damage development phenomenon activated by applied cyclic loading. The localised cyclic stress and strain concentration and fatigue damage evolution of microstructural elements within the fatigue damaged zone ahead of the crack tip are considered to

H.-Z Ding; O Hartmann; H Biermann; H Mughrabi

2002-01-01

98

Birth size, adult body composition and muscle strength in later life  

Microsoft Academic Search

Objective:Low birth weight has been linked to lower lean body mass and abdominal obesity later in life, whereas high birth weight has been suggested to predict later obesity as indicated by high body mass index (BMI). We examined how birth weight was related to adult body size, body composition and grip strength.Design\\/subjects:Cross-sectional study on 928 men and 1075 women born

H Ylihärsilä; E Kajantie; C Osmond; T Forsén; D J P Barker; J G Eriksson

2007-01-01

99

Double acceptance sampling plans for Burr type XII distribution percentiles under the truncated life test  

Microsoft Academic Search

Lio et al (2010a,?2010b) introduced two single acceptance sampling plans (SASPs) for the percentiles of Birnbaum-Saunders and Burr type XII distribution with a truncated censoring scheme. They assured that the acceptance sampling plans for percentiles significantly improve the traditional ones for mean life. In this paper, a double-sampling procedure is developed for Burr type XII distribution percentiles to save sample

M Aslam; Y Mahmood; Y L Lio; T-R Tsai; M A Khan

2012-01-01

100

Double acceptance sampling plans for Burr type XII distribution percentiles under the truncated life test  

Microsoft Academic Search

Lio et al (2010a,?2010b) introduced two single acceptance sampling plans (SASPs) for the percentiles of Birnbaum-Saunders and Burr type XII distribution with a truncated censoring scheme. They assured that the acceptance sampling plans for percentiles significantly improve the traditional ones for mean life. In this paper, a double-sampling procedure is developed for Burr type XII distribution percentiles to save sample

M Aslam; Y Mahmood; Y L Lio; T-R Tsai; M A Khan

101

A composite weighted multi-objective optimal approach for emergency logistics distribution  

Microsoft Academic Search

Improving the efficiency of distribution in emergency logistics research, which would decrease disaster damage in the other side. A new composite weighted multi- objective optimal approach for distributing commodities was constructed in this paper, which feature in including penalty function in objective functions, as well as time and cost during the transshipment in urgent relief distribution centers were considered in

Ming Liu; Lindu Zhao

2007-01-01

102

Comparative life-cycle cost analysis of underground heat distribution systems  

Microsoft Academic Search

An analytical model was developed to compare the life-cycle costs of two types of underground heat distributions systems: directly buried conduits and concrete trench installations. The costs of initial construction, routine maintenance, operation, repair, and replacement are represented in the model. Comparisons are made to explore the influence of failure rates, heat loss assumptions, the discount rate, and the policy

James V. Carnahan; Charles Marsh

1998-01-01

103

Selecting the best alternative based on life-cycle cost distributions of alternatives  

Microsoft Academic Search

Life-cycle cost (LCC) analysis can be used to select the best alternative among a set of candidates. The LCC is often treated as a random variable due to uncertainties. As a result, it is often represented by a distribution (or its first four moments) rather than a deterministic value. It is a challenge how to select the best alternative based

R. Jiang; W. J. Zhang; P. Ji

2004-01-01

104

Required characteristics of statistical distribution models for life cycle cost estimation  

Microsoft Academic Search

Life cycle cost (LCC) is used as the decision objective in many engineering problems such as project selection and bidding. An important nature of LCC estimation is uncertainty. Therefore, cost elements and system cost are usually represented by statistical distributions. A number of statistical models have been used for modeling LCC in the literature. It appears to be lack of

R. Jiang; W. J. Zhang; P. Ji

2003-01-01

105

Life history characteristics and distribution of Bythotrephes longimanus Leydig (Crustacea, Onychopoda) in the Biesbosch reservoirs  

Microsoft Academic Search

The diel and horizontal distributions of Bythotrephes longimanus Leydig, Leptodora kindti (Focke) and Anomopoda (cladocerans), as well as several life history parameters of each developmental stage of B. longimanus were studied in the non-stratified Biesbosch reservoirs. Anomopoda avoided the surface layer during the day only in the pelagic zone. In the surface layer near the shore, however, they were very

Henk A. M. Ketelaars; Arco J. Wagenvoort; Reglindis F. Herbst; Patricia A. W. Salm; Ger-An J. Jonge-Pinkster

1995-01-01

106

Families of Distributions with Positive Memory Derived from the Mean Residual Life Function.  

National Technical Information Service (NTIS)

The probability law of a positive random variable with finite mean is uniquely determined by the mean residual life function. This function is useful as an indicator of wearout and similar mechanisms. The amount of memory of a distribution is defined and ...

E. J. Muth

1975-01-01

107

A Comparison of Accelerated Life Test Plans for Weibull and Lognormal Distributions and Type I Censoring  

Microsoft Academic Search

Previous work on planning accelerated life test plans for the Weibull and lognormal distributions has concentrated on optimum test plans that minimize the variance of some specified estimator. However, these test plans use tests at only two levels of stress and, thus, have serious practical limitations. This article compares optimum test plans and some compromise test plans with respect to

William Q. Meeker

1984-01-01

108

Life Cycle Assessment of the District Heat Distribution System - Part 2: Network Construction (11 pp)  

Microsoft Academic Search

Preamble. This series of three papers is based on research performed for the Swedish District Heating Association with the purpose of mapping the environmental life cycle impacts from the different phases involved in district heat distribution. Part 1 concerns production of district heating pipes while Part 2 describes construction of the district heating pipe network. In Part 3, the use

Morgan Fröling; Magdalena Svanström

2005-01-01

109

The galactic habitable zone and the age distribution of complex life in the Milky Way.  

PubMed

We modeled the evolution of the Milky Way Galaxy to trace the distribution in space and time of four prerequisites for complex life: the presence of a host star, enough heavy elements to form terrestrial planets, sufficient time for biological evolution, and an environment free of life-extinguishing supernovae. We identified the Galactic habitable zone (GHZ) as an annular region between 7 and 9 kiloparsecs from the Galactic center that widens with time and is composed of stars that formed between 8 and 4 billion years ago. This GHZ yields an age distribution for the complex life that may inhabit our Galaxy. We found that 75% of the stars in the GHZ are older than the Sun. PMID:14704421

Lineweaver, Charles H; Fenner, Yeshe; Gibson, Brad K

2004-01-01

110

Temperature effects on gametophyte life-history traits and geographic distribution of two cryptic kelp species.  

PubMed

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

2012-06-18

111

Development of a Fatigue-Life Methodology for Composite Structures Subjected to out-of-Plane Load Components.  

National Technical Information Service (NTIS)

The efforts to identify and implement a fatigue life methodology applicable to demonstrate delamination failures for use in certifying composite rotor blades are presented. The RSRA/X-Wing vehicle was a proof-of-concept stopped rotor aircraft configuratio...

M. Sumich K. T. Kedward

1991-01-01

112

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

113

Hierarchical Process Composition: Dynamic Maintenance of Structure in a Distributed Environment.  

National Technical Information Service (NTIS)

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 mu...

S. A. Friedberg

1988-01-01

114

Body composition characteristics and body fat distribution in lean women with polycystic ovary syndrome  

Microsoft Academic Search

Body composition, fat distribution and bone mineral density were examined in lean women suffering from polycystic ovary syndrome (PCOS) and compared with body composition and fat distribution characteristics of weight- matched lean controls. Ten women with PCOS and a body mass index (BMI) below 25.00 (kg\\/m2) and 10 healthy women with a BMI below 25.00 (kg\\/m2) matched for age and

S. Kirchengast; J. Huber

2001-01-01

115

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

116

Effect of CNT distribution on tribological behavior of alumina–CNT composites  

Microsoft Academic Search

Alumina–carbon nanotube (CNT) composites with a different volume fraction of CNTs were fabricated by two different processing methods to investigate the effect of the distribution of CNT in the ceramic matrix on the tribological behavior. Alumina–CNT composites with CNT content up to 12wt.% were fabricated by tape casting, followed by lamination and hot pressing. For the comparison, composites with the

D.-S. Lim; D.-H. You; H.-J. Choi; S.-H. Lim; H. Jang

2005-01-01

117

Distribution and composition of particulate organic matter in the Ross Sea (Antarctica)  

Microsoft Academic Search

The biochemical composition and spatial distribution of particulate organic matter (POM) were studied in the Ross Sea (Antarctica) in summer 1989 to assess the quantitative role of organic carbon fractions in the cycling of organic matter in the water column. Large differences in chemical composition were observed between surface and deep layers. The results indicated that, despite large geographical differences,

Mauro Fabiano; Paolo Povero; Roberto Danovaro

1993-01-01

118

Preparation of C-fibre borosilicate glass composites: Influence of the fibre distribution on mechanical properties  

Microsoft Academic Search

Optimum conditions with respect to preparation-determined fibre distribution in borosilicate glass composites were investigated. Continuous C-fibre bundles were impregnated with glass powder in silicon alkoxide solution and wound in parallel to prepregs which were hot pressed into unidirectional composites. The influence of the glass particle size during the impregnation of fibre bundles and during hot pressing on the homogeneity of

T. Klug; R. Brückner

1994-01-01

119

Distribution of Protein Composition in Bread Wheat Flour Mill Streams and Relationship to Breadmaking Quality  

Microsoft Academic Search

Cereal Chem. 84(3):271-275 Wheat protein quantity and composition are important parameters for wheat baking quality. The objective of this study was to use fractionation techniques to separate the proteins of flour mill streams into various protein fractions, to examine the distribution of these protein fractions, and to establish a relationship between protein composition and bread- making quality. Nine break streams,

Y. G. Wang; K. Khan; G. Hareland; G. Nygard

2007-01-01

120

On the Analysis of Composite Lumped-Distributed Systems.  

National Technical Information Service (NTIS)

Fabrication methods associated with modern microelectronic technology have stimulated detailed investigation of the properties of distributed active and passive transmission systems. As a consequence, there have appeared recently several interesting resul...

J. J. Kelly M. S. Ghausi J. H. Mulligan

1966-01-01

121

Relationship Between Birth Weight and Body Composition, Energy Metabolism, and Sympathetic Nervous System Activity Later in Life  

Microsoft Academic Search

Objective: Epidemiological studies suggest that high birth weight might be associated with an increased risk of obesity later in life. Programming of metabolic, endocrine, and\\/or autonomic pathways during intrauterine development has been proposed to explain this association.Research Methods and Procedures: To determine the relationship between birth weight and body composition and energy metabolism later in life, we measured fat mass

Christian Weyer; Richard E. Pratley; Robert S. Lindsay; P. Antonio Tataranni

2000-01-01

122

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

Microsoft Academic Search

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

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

2008-01-01

123

Study of Rosmarinus officinalis L. Essential Oil Yield and Composition as a Function of the Plant Life Cycle  

Microsoft Academic Search

The yield and composition variation of the Algerian Rosmarinus officinalis as a function of plant life cycle was studied. Best period to collect the plant was found to be at full flowering stage. However, to obtain required oil quality, a compromise between oil yield and composition must be considered.

C. Boutekedjiret; R. Belabbes; F. Bentahar; J. M. Bessiere

1999-01-01

124

Distributed photoacoustic system for cure monitoring of composites  

Microsoft Academic Search

In this paper we describe a laser ultrasonic system for real-time monitoring of the degree of cure of a graphite-epoxy composite part during manufacturing. The system is integrated with a Resin-Transfer Molding (RTM) machine, and contains (i) a fiberized laser ultrasonic source, and (ii) an embedded ultrasonic sensor based on an intrinsic fiber optic Sagnac interferometer. Bulk ultrasonic waves generated

Pavel A. Fomitchov; Yeong K. Kim; Alexei K. Kromine; Sridhar Krishnaswamy; Jan D. Achenbach; Isaac M. Daniel

2001-01-01

125

Application of reliability and fiber probabilistic strength distribution concepts to composite vessel burst strength design  

Microsoft Academic Search

A composite pressure vessel design approach that is based on reliability and probabilistic fiber strength distribution concepts is discussed. The method is based on the fiber strain-strength interference reliability theory. The way in which fiber strength distribution parameters generated by two tensile tests of impregnated carbon fiber strands can be used in pressure vessel strength design is examined. It is

David Cohen

1992-01-01

126

Induction Heating of Carbon-Fiber Composites: Electrical Potential Distribution Model.  

National Technical Information Service (NTIS)

Mechanisms of heat generation and distribution in carbon-fiber-based composites subjected to an alternating magnetic field are considered. A model that predicts the strength and distribution of these heat sources in the plane of the cross-ply laminate con...

B. K. Fink R. L. McCullough J. W. Gillespie

1999-01-01

127

The Bias-corrected Mass Distribution Of Compositional Classes In The Main Asteroid Belt  

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 (Gradie & Tedesco 1982, Science, 216, 1405). In this work, we reexamine the architecture of the asteroid belt by determining the bias-corrected distribution of 99.99% of its mass based on compositional information provided by ground-based and space-based measurements. We report an updated view of the distribution of asteroid compositions. This material is based upon work supported by the National Science Foundation under Grant No. 0907766.

DeMeo, Francesca E.; Carry, B.

2012-10-01

128

Distributed configuration management using composite objects and constraints  

Microsoft Academic Search

Distributed programming techniques have transformed applications into federations of cooperatingsemi-autonomous components. Complex interactions between these componentscreate complex interdependencies which are quickly outstripping the capacity of human systemsmanagers. Adding configuration management features to an application's componentsreduces the flexibility and portability of those components. The Raven Configuration ManagementSystem (RCMS) provides an environment in which...

Terry Coatta; Gerald W. Neufeld

1994-01-01

129

Normal families and value distribution in connection with composite functions  

Microsoft Academic Search

We prove a value distribution result which has several interesting corollaries. Let k 2 N, let 2 C and let f be a transcendental entire function with order less than 1\\/2. Then for every nonconstant entire function g, we have that (f g)(k) has infinitely many zeros. This result also holds when k = 1, for every transcendental entire function

E. F. Cliord

130

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

131

Performance-based optimal design and rehabilitation of water distribution networks using life cycle costing  

NASA Astrophysics Data System (ADS)

A new multiobjective formulation is proposed for the optimal design and rehabilitation of a water distribution network, with minimization of life cycle cost and maximization of performance as objectives. The life cycle cost is considered to comprise the initial cost of pipes, the cost of replacing old pipes with new ones, the cost of cleaning and lining existing pipes, the expected repair cost for pipe breaks, and the salvage value of the pipes that are replaced. The performance measure proposed in this study is a modification to the resilience index to suit application to water distribution networks with multiple sources. A new heuristic method is proposed to obtain the solution for the design and rehabilitation problem. This heuristic method involves selection of various design and rehabilitation alternatives in an iterative manner on the basis of the improvement in the network performance as compared to the change in the life cycle cost on implementation of the alternatives. The solutions obtained from the heuristic method are used as part of the initial population set of the multiobjective, nondominated sorting genetic algorithm (NSGA-II) in order to improve the search process. Using a sample water distribution network, the modified resilience index proposed is shown to be a good indicator of the uncertainty handling ability of the network.

Jayaram, Nirmal; Srinivasan, K.

2008-01-01

132

Normal families and value distribution in connection with composite functions  

Microsoft Academic Search

We prove a value distribution result which has several interesting corollaries. Let k?N, let ??C and let f be a transcendental entire function with order less than 1\\/2. Then for every nonconstant entire function g, we have that (f?g)(k)?? has infinitely many zeros. This result also holds when k=1, for every transcendental entire function g. We also prove the following

E. F. Clifford

2005-01-01

133

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

Microsoft Academic Search

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

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

1985-01-01

134

Quantifying distributed damage in composites via the thermoelastic effect  

SciTech Connect

A new approach toward quantifying transverse matrix cracking in composite laminates using the thermoelastic effect is developed. The thermoelastic effect refers to the small temperature changes that are generated in components under dynamic loading. Two models are derived, and the theoretical predictions are experimentally verified for three types of laminates. Both models include damage-induced changes in the lamina stress state and lamina coefficients of thermal expansion conduction effects, and epoxy thickness. The first model relates changes in the laminate TSA signal to changes in longitudinal laminate stiffness and Poisson's ratio. This model is based on gross simplifying assumptions and can be used on any composite laminate layup undergoing transverse matrix cracking. The second model relates TSA signal changes to longitudinal laminate stiffness, Poisson's ratio, and microcrack density for (0[sub p]90[sub q])[sub s] and (90[sub q]/0[sub p])[sub s] cross-ply laminates. Both models yield virtually identical results for the cross-ply laminates considered. A sensitivity analysis is performed on both models to quantify the effects of reasonable property variations on the normalized stiffness vs. normalized TSA signal results for the three laminates under consideration. The results for the cross-ply laminates are very insensitive, while the (+/- 45)[sub 5s] are particularly sensitive to epoxy thickness and longitudinal lamina coefficient of thermal expansion. Experiments are conducted on (0[sub 3]/90[sub 3])[sub s] and (90[sub 3]/0[sub 3])[sub s] Gl/Ep laminates and (+/- 45)[sub 5s] Gr/Ep laminates to confirm the theoretical developments of the thesis. There is a very good correlation between the theoretical predictions and experimental results for the Gl/Ep laminates.

Mahoney, B.J.

1992-01-01

135

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

136

Spatial Distribution of Total, Ammonia-Oxidizing, and Denitrifying Bacteria in Biological Wastewater Treatment Reactors for Bioregenerative Life Support  

PubMed Central

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.

2002-01-01

137

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

138

Semantic-Based Automated Composition of Distributed Learning Objects for Personalized E-Learning  

Microsoft Academic Search

Recent advances in e-learning techonologies and web services make realistic the idea that courseware for personalized e-learning can be built by dy- namic composition of distributed learning objects, available as web-services. To be assembled in au automated way, learning objects metadata have to be ex- ploited, associating unambiguous, semantically rich, descriptions, to be used for such an automated composition. To

Simona Colucci; Tommaso Di Noia; Eugenio Di Sciascio; Francesco M. Donini; Azzurra Ragone

2005-01-01

139

Space charge distribution in Low-density Polyethylene (LDPE)\\/Pumice composite  

Microsoft Academic Search

Low-density polyethylene (LDPE)\\/pumice composites with different pumice weight percentage (1 wt%, 2 wt% and 5 wt%) were prepared by melt blending process in torque rheometer. Space charge distribution in composites and pure LDPE were investigated with pulsed electro-acoustic method (PEA). The results indicate that most of the space charge in pure LDPE under high electrical field was homo-polarity space charge

Bai Han; Zhi Sun; Yang Chen; Fuqiang Tian; Xuan Wang; Qingquan Lei

2009-01-01

140

Lifetime distributions for unidirectional fibrous composites under creep-rupture loading  

Microsoft Academic Search

Monte-Carlo simulations and theoretical modeling are used to study the statistical failure modes and associated lifetime distribution of unidirectional 2D and 3D fiber-matrix composites under constant load. Within the composite the fibers weaken over time and break randomly, and the matrix undergoes linear viscoelastic creep in shear. The statistics of fiber failure are governed by the breakdown model of Coleman

S. Mahesh; S. L. Phoenix

2004-01-01

141

Isotope distribution in electrochemical ion implantation in metals and composite materials  

Microsoft Academic Search

Experimental data are reported for the isotope distribution in the electrochemical implantation of lithium and hydrogen isotopes\\u000a in metals and composite materials from LiOD and LiOH solutions. General regularities are identified for the changes in isotopic\\u000a composition in the metal-matrix in which ions are implanted, in impurities in the metals, and in the ions responsible for\\u000a electrolyte conductivity. Possible mechanisms

V. V. Larionov; N. N. Nikitenkov; Yu. I. Tyurin

2010-01-01

142

Anthropometric Measures, Body Composition, Body Fat Distribution, and Knee Osteoarthritis in Women  

Microsoft Academic Search

Objective: Increased BMI is a well-recognized risk factor for radiographic knee osteoarthritis (rKOA); however, the contributions of the components of body composition, body fat distribution, and height to this association are not clear.Research Methods and Procedures: We examined 779 women ?45 years of age from the Johnston County Osteoarthritis Project. Body composition was assessed using DXA, and rKOA was defined

Lauren M. Abbate; June Stevens; Todd A. Schwartz; Jordan B. Renner; Charles G. Helmick; Joanne M. Jordan

2006-01-01

143

Determinants of Change in Stroke-Specific Quality of Life After Distributed Constraint-Induced Therapy  

PubMed Central

OBJECTIVE. We identified the predictive factors of change in quality of life (QOL) after a distributed form of constraint-induced therapy (dCIT) among stroke survivors. METHOD. Seventy-four participants were treated with dCIT. We identified eight potential determinants of change: age, gender, side of lesion, time since stroke, cognitive status, motor impairment of the upper extremity, activities of daily living (ADLs), and instrumental ADLs (IADLs). The Stroke-Specific Quality of Life Scale (SS–QOL) was used to assess QOL. RESULTS. Right-sided lesion and onset >17 mo earlier determined greater improvement in the SS–QOL Energy domain. Onset >10 mo earlier, poorer IADL performance, and age >68 yr predicted improvement in the Family Role, Mobility, and Mood domains, respectively. CONCLUSION. Side of lesion, time since stroke, IADL performance, and age were the most important determinants of QOL in patients receiving stroke motor rehabilitation.

Huang, Yan-Hua; Wu, Ching-Yi; Hsieh, Yu-Wei; Snow, Wilaiwan M.; Wang, Tien-Ni

2013-01-01

144

Monomer abundance distribution patterns as a universal biosignature: examples from terrestrial and digital life.  

PubMed

Organisms leave a distinctive chemical signature in their environment because they synthesize those molecules that maximize their fitness. As a result, the relative concentrations of related chemical monomers in life-bearing environmental samples reflect, in part, those compounds' adaptive utility. In contrast, rates of molecular synthesis in a lifeless environment are dictated by reaction kinetics and thermodynamics, so concentrations of related monomers in abiotic samples tend to exhibit specific patterns dominated by small, easily formed, low-formation-energy molecules. We contend that this distinction can serve as a universal biosignature: the measurement of chemical concentration ratios that belie formation kinetics or equilibrium thermodynamics indicates the likely presence of life. We explore the features of this biosignature as observed in amino acids and carboxylic acids, using published data from numerous studies of terrestrial sediments, abiotic (spark, UV, and high-energy proton) synthesis experiments, and meteorite bodies. We then compare these data to the results of experimental studies of an evolving digital life system. We observe the robust and repeatable evolution of an analogous biosignature in a digital lifeform, suggesting that evolutionary selection necessarily constrains organism composition and that the monomer abundance biosignature phenomenon is universal to evolved biosystems. PMID:21253717

Dorn, Evan D; Nealson, Kenneth H; Adami, Christoph

2011-01-21

145

Development of Elderly Quality of Life Index - Eqoli: Item Reduction and Distribution into Dimensions  

PubMed Central

OBJECTIVE To describe item reduction and its distribution into dimensions in the construction process of a quality of life evaluation instrument for the elderly. METHODS The sampling method was chosen by convenience through quotas, with selection of elderly subjects from four programs to achieve heterogeneity in the “health status”, “functional capacity”, “gender”, and “age” variables. The Clinical Impact Method was used, consisting of the spontaneous and elicited selection by the respondents of relevant items to the construct Quality of Life in Old Age from a previously elaborated item pool. The respondents rated each item’s importance using a 5-point Likert scale. The product of the proportion of elderly selecting the item as relevant (frequency) and the mean importance score they attributed to it (importance) represented the overall impact of that item in their quality of life (impact). The items were ordered according to their impact scores and the top 46 scoring items were grouped in dimensions by three experts. A review of the negative items was performed. RESULTS One hundred and ninety three people (122 women and 71 men) were interviewed. Experts distributed the 46 items into eight dimensions. Closely related items were grouped and dimensions not reaching the minimum expected number of items received additional items resulting in eight dimensions and 43 items. DISCUSSION The sample was heterogeneous and similar to what was expected. The dimensions and items demonstrated the multidimensionality of the construct. The Clinical Impact Method was appropriate to construct the instrument, which was named Elderly Quality of Life Index - EQoLI. An accuracy process will be examined in the future.

Paschoal, Sergio Marcio Pacheco; Filho, Wilson Jacob; Litvoc, Julio

2008-01-01

146

Separation and composition distribution determination of triblock copolymers by thermal field-flow fractionation.  

PubMed

Thermal field-flow fractionation (ThFFF) is used to separate a linear triblock copolymer of polystyrene, poly(tert-butyl acrylate), and poly(methyl methacrylate) by composition. Fractions were collected and subjected to off-line NMR analysis. The resultant mole fraction versus retention time plots for each of the three polymer components confirmed the success of the separation and yielded the composition distribution of the copolymer. The composition distribution was also obtained using a second approach that involved solving a series of equations comprised of polymer thermal diffusion coefficients and quasi-elastic light scattering, differential refractometry, and UV detector responses. Both sets of data showed similar trends of composition variations in each polymer component as a function of retention time. However, discrepancies were observed in the mole fraction values. The ability to compositionally separate and to determine composition distribution of copolymers is important as demonstrated by the presence of diblock impurities in the ThFFF with off-line NMR results. PMID:23975085

Ponyik, Charles A; Wu, David T; Williams, S Kim Ratanathanawongs

2013-08-24

147

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

NASA Astrophysics Data System (ADS)

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

Sardet, Laure; Patilea, Valentin

148

Lunar Clinopyroxene and Plagioclase: Surface Distribution and Composition  

NASA Astrophysics Data System (ADS)

The Clementine UVVIS images and the spectral and chemical (mineral) characteristics of lunar soil samples previously measured by the Lunar Samples Characterization Consortium were used to map the plagioclase and clinopyroxene abundance in the lunar surface material. An excess of plagioclase was found in young highland craters (e.g., in the crater Tycho) and in their ray systems. For clinopyroxenes, analogous behavior was observed in mare craters (e.g., in the crater Aristarchus). The maps for the FeO and Al2O3 bulk contents and the contents of these oxides in plagioclase and clinopyroxene were estimated by the same technique. These maps were compared to each other and to the predicted distribution of the lunar regolith maturity. The regolith of highland ray systems (e.g., the Tycho crater system) is characterized not only by low maturity but also by peculiar iron and aluminum contents: the lower the soil maturity degree, the smaller the iron content and the greater the aluminum content. This is confirmed by the data for the lunar soil samples from the Apollo 16 landing site. A cluster analysis of the “clinopyroxene content-maturity” and “plagioclase content-maturity” correlation diagrams allowed the mineral mapping of the lunar surface to be performed.

Shkuratov, Yu. G.; Kaydash, V. G.; Pieters, C. M.

2005-07-01

149

Synthesis of Ni-Cu Nanoparticles by Pulsed Wire Discharge and their Compositional Distribution  

NASA Astrophysics Data System (ADS)

Ni-Cu nanopowders were successfully synthesized from Cu and Ni wires using pulsed wire discharge. The powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). XRD confirmed that the nanopowder produced from Ni and Cu stranded wire was of Ni-Cu alloy. The composition of the nanopowders was controlled by varying the ratio of Ni to Cu wire diameter. TEM showed that the size of the prepared particles was less than 100 nm. EDS results revealed that the compositions of single nanoparticles in the nanopowder were different from each other. The composition distribution indicated that most compositions of nanoparticles agreed with that of the stranded wire. Submicron-sized particles consisting of Ni- or Cu-rich compositions were also found in the sample.

Suwa, Koji; Nakayama, Tadachika; Suzuki, Tsuneo; Suematsu, Hisayuki; Jiang, Weihua; Niihara, Koichi

2008-01-01

150

Sky distribution of artificial sources in the galactic belt of advanced cosmic life.  

PubMed

In line with the concept of the galactic belt of advanced life, we evaluate the sky distribution of detectable artificial sources, using a simple astrophysical model. The best region to search is the median band of the Milky Way in the Vulpecula-Cygnus region, together with a narrower one in Carina. Although this work was done in view of a proposal to send a SETI probe at a gravitational focus of the Sun, we recommend these sky regions particularly for the searches of the sky survey type. PMID:11540597

Heidmann, J

1994-12-01

151

Accepted manuscript Bayes estimators for reliability measures in geometric distribution model using masked system life test data  

Microsoft Academic Search

This paper presents Bayes estimators for the reliability measures of the individual components in a multi-component systems in the presence of masked system life test data. The life time distributions of the system components are assumed to be geometric with different parameters. Two sided Bayesian probability intervals of the parameters are also derived. Numerical simulation study is given in order

Ammar M. Sarhan; Debasis Kundu

152

The Relations among Organizational and Distribution Forms and Capital and Asset Risk Structures in the Life Insurance Industry  

Microsoft Academic Search

This article is the first step toward integrating in a single framework two previously separate lines of research on major structural decisions of life insurers. The literature has previously studied the relation between capital structure and asset risk on the one hand, and the relation between organizational form and distribution system on the other hand, without integrating them. Using life

Etti Baranoff; Thomas Sager

2003-01-01

153

Fatigue-life prediction of SiC particulate reinforced aluminum alloy 6061 matrix composite using AE stress delay concept  

Microsoft Academic Search

A study of the residual fatigue life prediction of 6061-T6 aluminum matrix composite reinforced with 15 vol % SiC particulates (SiCp) by using the acoustic emission technique and the stress delay concept has been carried out. Fatigue damages corresponding to 40, 60 and 80% of total fatigue life were stimulated at a cyclic stress amplitude. The specimens with and without

D. Shan; H. Nayeb-Hashemi

1999-01-01

154

Delay Composition Algebra: A Reduction-Based Schedulability Algebra for Distributed Real-Time Systems  

Microsoft Academic Search

This paper presents the delay composition algebra: a set of simple operators for systematic transformation of distributed real-time task systems into single-resource task systems such that schedulability properties of the original system are preserved. The transformation allows performing schedulability analysis on distributed systems using uniprocessor theory and analysis tools. Reduction-based analyses techniques have been used in other contexts such as

Praveen Jayachandran; Tarek T. Abdelzaher

2008-01-01

155

The generalized-kinetics-based equilibrium distribution function for composite particles  

Microsoft Academic Search

This work is devoted to the equilibrium distribution function for a fluid of mutually non-interacting identical composite point particles in three-dimensional physical space. The distribution function is derived within the generalized-kinetics (GK) vision from the proposed probabilistic model based on quantum-mechanical bosons and fermions. The first GK advantage is that the derivation does not involve any assumption on the interpolation

Nicola Bellomo; Nils Calander; Eugen Mamontov; Magnus Willander

2003-01-01

156

Compositional Distribution of Near-Earth Asteroids: New Results for 80 Objects  

Microsoft Academic Search

We report new spectroscopic observations for about 80 near-Earth asteroids. These observations allow the compositional distribution of near-Earth asteroids to be compared with the distributions measured for main-belt asteroids and meteorites. For all objects in our sample, we obtained visible wavelength spectra, typically covering 0.45- to 0.95-microns, by utilizing the 2.4m Hiltner telescope at Kitt Peak, AZ. For nearly 20

R. P. Binzel; S. J. Bus; T. H. Burbine

1997-01-01

157

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

2012-07-14

158

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

159

DISTRIBUTION OF PROTEIN COMPOSITION IN BREAD WHEAT FLOUR MILL STREAMS AND RELATIONSHIP TO BREADMAKING QUALITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Wheat protein quantity and composition are important parameters for wheat baking quality. The objective of this study was to use fractionation techniques to separate the proteins of flour mill streams into various protein fractions, to examine the distribution of these protein fractions, and to esta...

160

Stress Distribution and Effective Longitudinal Young's Modulus of Unidirectional Discontinuous Fibre Composites  

Microsoft Academic Search

In this article, stress and strain distributions in the elementary cell are studied in the case of unidirectional discontinuous fibre composites as functions of the geometrical arrangement of fibres. This arrangement is characterized by the volume frac tion of fibres, the fibre aspect ratio and the fibre spacing parameter. Thus, two extreme schemes are analyzed by the finite element method:

J.-M. Berthelot; A. Cupcic; K. A. Brou

1993-01-01

161

The effects of chemical composition and distribution on the preservation of phytolith morphology  

NASA Astrophysics Data System (ADS)

Different types of phytolith even when coming from the same plant react to high temperatures in different ways. To understand the behavior of phytoliths upon heating, we examined composition and distribution of some elements within different phytolith types using SEM-EDS and synchrotron radiation ?-X-ray fluorescence. By analyzing phytoliths from rice husk, rice leaf and Than tree leaf, we find that the compositions and distributions of metal oxides within different phytolith types are quite different. It is well known that metal oxides have been used as fluxing agent to reduce the melting temperature of SiO2 in the production of glass, and different metal oxides can be used to produce a variety of glass with diverse features. Similarly, metal elements including potassium, magnesium and calcium in phytoliths should also act as a fluxing agent under high temperature, and the differential compositions and distributions of these metal elements within the phytoliths resulted in the variable reaction to heating. In sum, there is a negative relationship between the flux elements composition in phytoliths, and the temperatures at which phytoliths deform; furthermore, potassium and calcium in the rice leaf phytolith are almost evenly distributed in all parts, which may cause the phytolith's shape to deform evenly. In comparison, Than tree leaf phytolith is found to have a high percentage of potassium and calcium located exclusively on the outside, which may explain why the deformation of Than tree leaf phytolith occurs firstly at the outside.

Wu, Yan; Yang, Yimin; Wang, Hua; Wang, Changsui

2013-02-01

162

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

SciTech Connect

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

Tuncer, Enis [ORNL

2006-01-01

163

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

SciTech Connect

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

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

2006-01-01

164

P2J-3 Axial Power Flow Distribution of Ultrasonic Guided Waves in Composite Pipes  

Microsoft Academic Search

This paper describes a preliminary investigation of the distribution of axial power flow amplitude of longitudinal guided waves in composite pipes. The dispersion characteristics were computed on the assumption that the frequencies are real and the wavenumbers are complex numbers. The optimal location, optimal mode and its frequency-thickness products (fd) of testing were chosen according to the APF. The results

Dean Ta; Weiqi Wang; L. H. Le

2006-01-01

165

The effect of interfacial imperfections on the micromechanical stress and strain distribution in fibre reinforced composites  

Microsoft Academic Search

A mathematical model for the determination of micromechanical stress and strain distribution in a unidirectional fibre reinforced composite is developed. The model consists of three phases represented as concentric cylinders, including the existence of an interphase. Both fibre and matrix have well defined elastic properties, while the interphase properties follow an exponential law of variation. The effect of an abrupt

P. A. Kakavas; N. K. Anifantis; K. Baxevanakis; D. E. Katsareas; G. C. Papanicolaou

1995-01-01

166

Strain Measurement of Carbon/Epoxy Composite with Fibre Optics White Light Quasi Distributed Polarimetric Sensor.  

National Technical Information Service (NTIS)

The results obtained in measuring the static and dynamic strain of carbon/epoxy composites with embedded or bonded fiber optics white light quasi-distributed polarimetric sensor are reported. Linear and accurate measurements were obtained and up to six se...

B. Fornari J. J. Guerin P. Sansonetti M. Lequime G. Romeo

1993-01-01

167

The composition and size distribution of the dust in the coma of Comet Hale–Bopp  

Microsoft Academic Search

We discuss the composition and size distribution of the dust in the coma of Comet Hale–Bopp. We do this using a model fit for the infrared emission measured by the Infrared Space Observatory (ISO) and the measured degree of linear polarization of scattered light at various phase angles and wavelengths. The effects of particle shape on the modeled optical properties

M. Min; J. W. Hovenier; A. de Koter; L. B. F. M. Waters; C. Dominik

2005-01-01

168

The composition and size distribution of the dust in the coma of Comet Hale Bopp  

Microsoft Academic Search

We discuss the composition and size distribution of the dust in the coma of Comet Hale Bopp. We do this using a model fit for the infrared emission measured by the Infrared Space Observatory (ISO) and the measured degree of linear polarization of scattered light at various phase angles and wavelengths. The effects of particle shape on the modeled optical

M. Min; J. W. Hovenier; A. de Koter; L. B. F. M. Waters; C. Dominik

2005-01-01

169

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

170

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 mum) 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; M. Power; A. G. Allen; A. Aiuppa; C. J. Horwell; E. P. W. Ward

2008-01-01

171

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

172

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

2013-05-09

173

Distributed condition monitoring techniques of optical fiber composite power cable in smart grid  

NASA Astrophysics Data System (ADS)

Optical fiber composite power cable such as optical phase conductor (OPPC) is significant for the development of smart grid. This paper discusses the distributed cable condition monitoring techniques of the OPPC, which adopts embedded single-mode fiber as the sensing medium. By applying optical time domain reflection and laser Raman scattering, high-resolution spatial positioning and high-precision distributed temperature measurement is executed. And the OPPC cable condition parameters including temperature and its location, current carrying capacity, and location of fracture and loss can be monitored online. OPPC cable distributed condition monitoring experimental system is set up, and the main parts including pulsed fiber laser, weak Raman signal reception, high speed acquisition and cumulative average processing, temperature demodulation and current carrying capacity analysis are introduced. The distributed cable condition monitoring techniques of the OPPC is significant for power transmission management and security.

Sun, Zhihui; Liu, Yuan; Wang, Chang; Liu, Tongyu

2011-11-01

174

Effect of particle size distribution on particle based composite anode models  

NASA Astrophysics Data System (ADS)

Particle based models of composite anodes are useful tools for exploring the behavior of SOFC systems. As part of our efforts to develop models for understanding fuel cells, we have been building models of Ni-YSZ composite anodes using experimentally measured particle size distributions. The objectives of this study were to characterize the percolation threshold and conductivity of these models in comparison to simpler mono dispersed and biphasic particle size distributions from the literature. We found that the average values for the onset of percolation and the measured conductivity of the models with experimentally measured particle size distributions are similar to those for the simple distributions and the experimentally measured distributions. For all of the configurations evaluated, the onset of percolation in the Nickel phase occurred at a solid fraction of Nickel between 20% and 25%. This corresponded almost exactly to the point at which the coordination number between Nickel phase particles reached 2.2. The significant finding was that the variation in the value for the conductivity, as measured by the standard deviation of the results, was several orders of magnitude higher than for the simpler systems. We explored the validity of our assumptions, specifically the assumption of random particle placement, by building a particle model directly from FIB-SEM data. In this reconstruction, it was clear that the location of particles was not random. Particles of the same type and size had much likelihood of contact higher than would indicated by random location.

Thomas, Vaughan L.

2013-06-01

175

AC losses and current distribution of multi-tape BI-2223 composite conductor  

NASA Astrophysics Data System (ADS)

In the power applications of high temperature superconductor(HTS), it is necessary to stack several HTS tapes together to achieve high current carrying capacity. However, the current would not be well distributed in the multi-tape composites due to the existence of electrical and magnetic interaction inside it. As a result, the AC losses in the composites would be then increased. In order to investigate the detail, the AC losses of multi-tape composites are experimentally studied in this presentation. The average transport AC losses are measured under self and different background AC fields. The results show that the average losses are increased with the external magnetic field and the number of the stacked tapes, and there exists an upper limit of the number of the stacked tapes due to the magnetic coupling effect among the tapes. .

Zhang, G. M.; Lin, L. Z.; Xiao, L. Y.; Qiu, M.; Wang, Y. S.; Yu, Y. J.

2002-05-01

176

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

177

Small Birth Weight and Later Body Composition and Fat Distribution in Adolescents: The AVENA Study  

Microsoft Academic Search

Objective:To assess the association between birth weight and body composition and fat distribution in adolescents, and to test the possible sex-specific effect in these relationships.Methods and Procedures:A total of 1,223 adolescents 13–18.5 years old (553 male adolescents and 670 female adolescents) born at >35 weeks, were selected from a cross-sectional multicenter study conducted in five Spanish cities in 2000–2002. BMI

Idoia Labayen; Luis A. Moreno; Jonatan R. Ruiz; Marcela González-Gross; Julia Wärnberg; Christina Breidenassel; Francisco B. Ortega; Ascensión Marcos; Manuel Bueno; Idoia Labayen Goñi

2008-01-01

178

Distribution of Composite CYP1A1 Genotypes in Africans, African-Americans and Caucasians  

Microsoft Academic Search

We present the genotype distribution of the CYP1 A1 gene in a sample of over 300 subjects of various ethnic origins. Genotypes are presented as composites of eight possible alleles, taking into account the three major polymorphisms, including a recently described African-American-specific MspI RFLP. A new nomenclature system is presented for clarifying the various haplotypes. Interesting interracial differences in allelic

Seymour J. Garte; Julie Trackman; Frances Crofts; Paolo Toniolo; Joel Buxbaum; Sine Bayo; Emanuela Taioli

1996-01-01

179

Research on space charge distribution in composite of Low Density Polyethylene and Nano Silver  

Microsoft Academic Search

Double-solution mixture method was employed in the preparation of the composite of low density polyethylene\\/Nano-silver. Space charge distributions in samples with different nano-silver concentrations were measured using the pulsed electro-acoustic (PEA) method. In the experiment, samples were tested under three different levels of electrical stress, respectively: 10kV\\/mm, 30kV\\/mm and 50kV\\/mm. Discharge characteristics of the samples were examined as well. Test

Chuan Cai; Xuguang Li; Yi Yin; Zhe Li; Pingkai Jiang

2008-01-01

180

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

Microsoft Academic Search

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

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

2006-01-01

181

Perinatal bisphenol A exposure promotes hyperactivity, lean body composition, and hormonal responses across the murine life course.  

PubMed

The development of adult-onset diseases is influenced by perinatal exposure to altered environmental conditions. One such exposure, bisphenol A (BPA), has been associated with obesity and diabetes, and consequently labeled an obesogen. Using an isogenic murine model, we examined the effects of perinatal exposure through maternal diet to 50 ng (n=20), 50 ?g (n=21), or 50 mg (n=18) BPA/kg diet, as well as controls (n=20) on offspring energy expenditure, spontaneous activity, and body composition at 3, 6, and 9 mo of age, and hormone levels at 9 and 10 mo of age. Overall, exposed females and males exhibited increased energy expenditure (P<0.001 and 0.001, respectively) throughout the life course. In females, horizontal and vertical activity increased (P=0.07 and 0.06, respectively) throughout the life course. Generally, body composition measures were not different throughout the life course in exposed females or males (all P>0.44), although body fat and weight decreased in exposed females at particular ages (all P<0.08). Milligram-exposed females had improved glucose, insulin, adiponectin, and leptin profiles (all P<0.10). Thus, life-course analysis illustrates that BPA is associated with hyperactive and lean phenotypes. Variability across studies may be attributable to differential exposure duration and timing, dietary fat and phytoestrogen content, or lack of sophisticated phenotyping across the life course. PMID:23345456

Anderson, Olivia S; Peterson, Karen E; Sanchez, Brisa N; Zhang, Zhenzhen; Mancuso, Peter; Dolinoy, Dana C

2013-01-23

182

What is the difference? Evidence on the distribution of wealth, health, life expectancy, and health insurance coverage.  

PubMed

There is a literature of long standing that considers the relationship between income and differentials in mortality and morbidity, but information on differentials over the distribution of accumulated wealth have been far more scarce and subject to measurement problems. This paper provides evidence from the Survey of Consumer Finances, which is designed as a survey of wealth, on the distribution of wealth and income and how those distributions have shifted in recent years. Particular attention is paid to the distribution of wealth across minority groups and across age groups. The paper also examines the relationship between wealth and health status, life expectancy, and health insurance coverage. PMID:18680166

Kennickell, Arthur B

2008-09-10

183

Distribution of normalized critical current of bent multifilamentary Bi2223 composite tape  

NASA Astrophysics Data System (ADS)

The distribution of the normalized critical transport current (critical current normalized with respect to the original value) of Bi2223/Ag/Ag alloy composite tape under bending strain of 0%-0.833% was studied experimentally and analytically. The experimental results were analyzed by a modeling approach based on the relation of the heterogeneous damage evolution to the distribution of the critical current. The main results are summarized as follows. (1) The measured distribution of the critical current values varying with bending strain was described well by the present approach. (2) When all specimens were damaged at high bending strains (0.338%-0.833% in the present work), the distribution of the critical current of the bent-damaged specimens was expressed by the three-parameter Weibull distribution function, the reason for which was revealed. (3) The distribution of the irreversible strain was estimated, with which the influence of the increase in the fraction of damaged specimens on the variation of critical current distribution in the low bending strain range (0%-0.35%) was elucidated.

Ochiai, S.; Fujimoto, M.; Shin, J. K.; Okuda, H.; Oh, S. S.; Ha, D. W.

2009-11-01

184

Modelling of ceramic matrix composite microstructure using a two-dimensional fractal spatial particle distribution  

NASA Astrophysics Data System (ADS)

Particulate composite reinforcements are good candidates for the fracture toughness of ceramics. In order to predict mechanical response of ceramic matrix composites, an efficient method capable of modelling their complex microstructure is needed. The purpose of this research is the development of such a model using fractal spatial particle distribution. A review of different toughness mechanisms for particulate composites and associated models for deriving their constitutive relationships is presented in chapter 2. These different toughening mechanisms as well constitutive properties depend on particle shape, size and spatial distribution, which lend themselves to a self-similar fractal based modelling approach. A self-similar distribution of particles linked to the fractal geometry is proposed. Fractal geometry provides an ideal tool for describing the randomness and disorder of the system. Its foundations are reviewed in chapter three with emphasis on iterated function systems that are subsequently used to obtain the particle configurations in the proposed model. For the sake of completeness, a review of fractal structure in science is given to illustrate possible applications. Derivation of the volume fraction associated with self similar distributions is provided in chapter 4. This is followed by a description of the numerical model and the boundary conditions. A Finite Element simulation is performed for different volume fractions, generators and number of particles for different displacements (two uniaxial and biaxial cases) and 2-D stress state cases. From these simulations the inverse distribution of the maximum principal stress is computed. Then the self similar models are compared with the model obtained by the Yang Teriari Gokhale (Y.T.G.) method and model obtained by only one iteration. Fractal dimension for real microstructure are computed and microstructure based on the fractal dimension and number of particle is simulated. It can be derived that the fractal dimension can be related to the average radius of circular particle in special cases. General conclusion and recommendation for future work brings this investigation to a close.

Cottet, Arnaud J.

185

Contrasted glass-whole rock compositions and phenocryst re-distribution, IPOD Sites 417 and 418  

NASA Astrophysics Data System (ADS)

Major element composition ranges of closely associated basalt glass-whole rock pairs from individual small cooling units approach the total known range of basalt glass and whole rock compositions at IPOD sites 417 and 418. The whole rock samples fall into two groups: one is depleted in MgO and distinctly enriched in plagioclase but has lost some olivine and/or pyroxene relative to its corresponding glass; and the other is enriched in MgO and in phenocrysts of olivine and pyroxene as well as plagioclase compared to its corresponding glass. By analogy with observed phenocryst distributions in lava pillows, tubes, and dikes, and with some theoretical studies, we infer that bulk rock compositions are strongly affected by phenocryst redistribution due to gravity settling, flotation, and dynamic sorting after eruption, although specific models are not well constrained by the one-dimensional geometry of drill core. Compositional trends or groupings in whole rock data resulting from such late-stage processes should not be confused with more fundamental compositional effects produced in deep chambers or during partial melting.

Staudigel, H.; Bryan, W. B.

1982-01-01

186

Analysis of stress distributions in metal-matrix composites with variations in fiber spacing  

NASA Astrophysics Data System (ADS)

Results of micromechanical and finite element analyses are presented to quantify the effects of fiber spacing in unidirectional metal-matrix composites (MMC's). Computed tomography (CT) data of unidirectional metal-matrix composite samples provide information on fiber locations for the analysis of the fiber distribution within the composite. Image processing methods are developed to extract fiber centers from the CT data. A micromechanical model, based on the Generalized Method of Cells (GMC), is developed to include interface and crack elements and model the stress variations in a representative unit cell containing two half fibers. The minimum, average, and maximum distance between fibers, as measured from the CT data, is used as input to the model. The model results show that the stress between fibers increases as they get closer together. The CT data are also processed to produce a rectangular grid of finite elements which model the composite cross-section and where the stiffness matrix for each element is based on the local fiber volume fraction. The finite element results show that in some cases, stresses in the composite can be as high as 56% greater than the average stress and thereby set up stress concentrations which can initiate yielding and/or damage at loads well below those that would be calculated using average stress considerations only.

Yancey, Robert Neil

1997-09-01

187

Weighting Components of Composite Endpoints in Clinical Trials: An Approach Employing Disability Adjusted Life Years  

PubMed Central

Background and Purpose Conventional analysis of vascular prevention trials assigns equal weight to disparate vascular events of composite endpoint at variance with public’s perception of their differential impact on health outcome. This study was to apply the disability-adjusted life year (DALY) metric for differential weighting of individual vascular endpoints in trial analyses. Methods DALY values for the most common major endpoints in vascular prevention trials, nonfatal myocardial infarction (MI), nonfatal stroke, and vascular death, were derived using World Health Organization Global Burden of Disease Project methodology. The standardized DALYs for each event were applied to recent major primary and secondary vascular prevention trials and to hypothetical model trials. Results Standardized DALYs lost were 7.63 for nonfatal stroke, 5.14 for nonfatal MI, and 11.59 for vascular death. In the published trials analyses, direction of treatment effects was consistent between DALY and standard event analysis, but rank order of treatment effect changed for 10 of 18 trials. The DALY analysis also enabled to provide number-needed-to-treat values to gain one DALY: 2.1 for anticoagulation in atrial fibrillation, 2.7 for carotid endarterectomy in symptomatic stenosis, and 4.7 for clopidogrel added to aspirin in acute coronary syndrome. Hypothetical trial analyses demonstrated that the DALY metric more finely discriminates treatment effects. Conclusions Compared with a nonfatal MI, a nonfatal stroke causes a 1.48-fold greater loss and vascular death a 2.25-fold greater loss of DALY. DALY analysis integrates these valuations in a summary metric reflecting the net impact of therapy on patient and societal health, complementing conventional endpoint analyses.

Hong, Keun-Sik; Ali, Latisha K.; Selco, Scott L.; Fonarow, Gregg C.; Saver, Jeffrey L.

2011-01-01

188

Life cycle strain mapping of composite airframe structures by using FBG sensors  

NASA Astrophysics Data System (ADS)

The objective of this work is to develop a system for monitoring the structural integrity of composite airframe structures by strain mapping over the entire lifecycle of the structure. Specifically, we use fiber Bragg grating sensors to measure strain in a pressure bulkhead made of carbon fiber reinforced plastics (CFRPs) through a sequence of lifecycle stages (molding, machining, assembly, operation and maintenance) and detect the damage, defects, and deformation that occurs at each stage from the obtained strain distributions. In previous work, we have evaluated strain monitoring at each step in the FRP molding and machining stages of the lifecycle. In the work reported here, we evaluate the monitoring of the changes in strain that occur at the time of bolt fastening during assembly. The results show that the FBG sensors can detect the changes in strain that occur when a load is applied to the structure during correction of thermal deformation or when there is an offset in the hole position when structures are bolted together. We also conducted experiments to evaluate the detection of damage and deformation modes that occur in the pressure bulkhead during operation. Those results show that the FBG sensors detect the characteristic changes in strain for each mode.

Sekine, K.; Takahashi, I.; Kume, M.; Takeya, H.; Iwahori, Y.; Minakuchi, S.; Takeda, N.; Koshioka, Y.

2011-03-01

189

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

Microsoft Academic Search

The efforts to identify and implement a fatigue life methodology applicable to demonstrate delamination failures for use in certifying composite rotor blades are presented. The RSRA\\/X-Wing vehicle was a proof-of-concept stopped rotor aircraft configuration which used rotor blades primarily constructed of laminated carbon fiber. Delamination of the main spar during ground testing demonstrated that significant interlaminar stresses were produced. Analysis

M. Sumich; K. T. Kedward

1991-01-01

190

Comparative life cycle studies on poly(3-hydroxybutyrate)-based composites as potential replacement for conventional petrochemical plastics  

Microsoft Academic Search

A cradle-to-grave environmental life cycle assessment (LCA) of a few poly(3-hydroxybutyrate) (PHB) based composites has been performed and was compared to commodity petrochemical polymers. The end products studied are a cathode ray tube (CRT) monitor housing (conventionally produced from high-impact polystyrene, HIPS) and the internal panels of an average car (conventionally produced from glass-fibers-filled polypropylene, PP-GF). The environmental impact is

Matteo Pietrini; A. L. Roes; Martin K. Patel; Emo Chiellini

2007-01-01

191

Software for analysis of chemical mixtures--composition, occurrence, distribution, and possible toxicity  

USGS Publications Warehouse

The composition, occurrence, distribution, and possible toxicity of chemical mixtures in the environment are research concerns of the U.S. Geological Survey and others. The presence of specific chemical mixtures may serve as indicators of natural phenomena or human-caused events. Chemical mixtures may also have ecological, industrial, geochemical, or toxicological effects. Chemical-mixture occurrences vary by analyte composition and concentration. Four related computer programs have been developed by the National Water-Quality Assessment Program of the U.S. Geological Survey for research of chemical-mixture compositions, occurrences, distributions, and possible toxicities. The compositions and occurrences are identified for the user-supplied data, and therefore the resultant counts are constrained by the user’s choices for the selection of chemicals, reporting limits for the analytical methods, spatial coverage, and time span for the data supplied. The distribution of chemical mixtures may be spatial, temporal, and (or) related to some other variable, such as chemical usage. Possible toxicities optionally are estimated from user-supplied benchmark data. The software for the analysis of chemical mixtures described in this report is designed to work with chemical-analysis data files retrieved from the U.S. Geological Survey National Water Information System but can also be used with appropriately formatted data from other sources. Installation and usage of the mixture software are documented. This mixture software was designed to function with minimal changes on a variety of computer-operating systems. To obtain the software described herein and other U.S. Geological Survey software, visit http://water.usgs.gov/software/.

Scott, Jonathon C.; Skach, Kenneth A.; Toccalino, Patricia L.

2013-01-01

192

Evaluation of light transmission and distribution materials for Lunar and Martian bioregenerative life support.  

PubMed

The materials that were selected and evaluated in this study in the context of bioregenerative advanced life support included polymer optical cables, for transmission of photosynthetic photon flux (PPF), and light pipe, woven optical pad and light-emitting fiber (LEF) for PPF distribution. All materials exhibited significant fidelity in transmitting the spectral characteristics of the artificial lluminator's Xenon-Metal Halide lamp. The PPF attenuation values for the polymer cables EL-200, EL-300, EL-400, and EL-500 were not significantly distinguishable from one another nor from that of the fused-silica cable of 0.34 dB/m. With the exception of EL-100 and EL-700, which had significantly lower PPF transmission efficiencies of 54.9%/m and 66.6%/m, respectively, all the other polymer cables had PPF transmission efficiencies of over 85%/m which, except for EL-300, were not significantly different from one another nor from that of the fused-silica cable of 93.2%/m. The highest PPF output efficiency achieved for the 7.1-cm light pipe 14.7%, for its maximum pipe length of 100 cm. At a constant pipe length of 50 cm, the PPF output efficiency of the 10-cm light pipe of 0.71% was significantly lower than that of the 7.1-cm light pipe of 10.54%. The PPF output for the woven optical pad was determined to be 36.3%. The PPF output efficiency for the LEF without the optic fastener was determined to be 27.1%, whereas that for the LEF with the optic fastener was 50.3%, that is, the maximum value of PPF output efficiency in the study. The polymer optical cables, light pipe, woven optical pad, and LEF exhibited significant regularity and symmetry in their PPF output spatial distributions. PMID:11871446

Cuello, J L; Sadler, P; Jack, D; Ono, E; Jordan, K A

1998-01-01

193

Rock size distributions on lava flow surfaces: New results from a range of compositions  

NASA Astrophysics Data System (ADS)

We measured block sizes along 15-25m orthogonal transects on 12 lava flows of compositions ranging from basalt to rhyolite. At each site, we stretched a line across the flow surface then measured the length of each block cut by this line that were greater than 3-12cm (depending on composition). The measurements from each site were reduced to cumulative size frequency distribution plots, with block size (D) plotted against the fraction of the line f(D) composed of blocks greater than or equal to that size, and fitted with an exponential curve of the form f(D) = k exp(-qD) where k is the intercept and q is the decay parameter. Average block size and geometric mean were also determined for each site. Our data show no clear trends linking average or mean block size to composition, although there does seem to be relationship between block size and the decay parameter. Block size corresponds with the decay parameter at each site except for the basaltic andesite flow at Paint Pot Crater (CA). Many sites at this flow were covered with secondary spatter deposits. Largest blocks and smallest decay parameters were found for the andesite flows at Sabancaya (Peru), while the basalt flows at Cima (CA) exhibited the smallest blocks and largest decay parameters. The second largest block sizes occurred at the four Inyo domes composed of both crystal-rich and glassy rhyolite, and these domes also showed the second smallest decay parameters. All four of the Inyo domes were emplaced along the same feeder dike trend, and the average and mean sizes and decay parameters at these domes are nearly identical, suggesting that composition, extrusion rate, or eruption history controls the block size distributions. However, values for the two andesitic flows, Mt. Shasta (CA) and Sabancaya, were very different, suggesting that extrusion rate and/or eruption history exert a stronger control over the block size distributions than does composition. LIDAR data sets are capable of detecting sub-meter variations in topography that can be related to block size. High-resolution topographic characteristics measured from LIDAR data sets can therefore supply us with another avenue to study the emplacement histories of lava flows using block size distributions.

Burke, M. P.; Anderson, S. W.; Bulmer, M. H.

2005-12-01

194

A GROUP ACCEPTANCE SAMPLING PLANS FOR TRUNCATED LIFE TESTS BASED ON THE INVERSE RAYLEIGH AND LOG-LOGISTIC DISTRIBUTIONS  

Microsoft Academic Search

A group acceptance sampling plan from a truncated life test is designed when the lifetime of an item follows either an inverse Rayleigh or a log-logistic distribution, in which a multiple number of items as a group can be tested simultaneously in a tester. The minimum number of groups required for a given group size and the acceptance number is

Muhammad Aslam; Chi-Hyuck Jun

2009-01-01

195

Accelerated life test sampling plans for the Weibull distribution under Type I progressive interval censoring with random removals  

Microsoft Academic Search

This paper considers the design of accelerated life test (ALT) sampling plans under Type I progressive interval censoring with random removals. We assume that the lifetime of products follows a Weibull distribution. Two levels of constant stress higher than the use condition are used. The sample size and the acceptability constant that satisfy given levels of producer's risk and consumer's

Chang Ding; Chunyan Yang; Siu-Keung Tse

2010-01-01

196

Local abundance patterns of noctuid moths in olive orchards: life-history traits, distribution type and habitat interactions.  

PubMed

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

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

2011-01-01

197

Life cycle, weight and possible age distribution in a population of Nereis virens (Sars) from New Brunswick  

Microsoft Academic Search

A population of the marine polychaete Nereis virens at Brandy Cove, New Brunswick has been analysed on the basis of weight distribution in monthly collections made throughout a year. Gametogenesis, spawning and larval life were also studied and information which adds to or differs from earlier accounts is reported. An age structure is postulated, involving a lifespan of up to

Doreen R. Snow; Joan Rattenbury Marsden

1974-01-01

198

Life expectancy (ex) and stable age distribution (Cx) of Plutella xylostella (L.) (Lep.: Yponomeutidae), exposed to sublethal doses of hexaflumuron  

Microsoft Academic Search

The diamondback moth, Plutella xylostella (L.) is a major pest of crucifers in Iran. In this study, the influence of two sublethal concentrations (LC10 and LC25) of an insect growth regulator, hexaflumuron on life expectancy (ex), stable age distribution (Cx), age-specific fertility (mx) and number of fertile eggs per day was investigated. Results showed that the sublethal doses of hexaflumuron

Mohammad Mahmoudvand; Habib Abbasipour; Aziz Sheikhi Garjan; Ali Reza Bandani

2012-01-01

199

Life expectancy (ex) and stable age distribution (Cx) of Plutella xylostella (L.) (Lep.: Yponomeutidae), exposed to sublethal doses of hexaflumuron  

Microsoft Academic Search

The diamondback moth, Plutella xylostella (L.) is a major pest of crucifers in Iran. In this study, the influence of two sublethal concentrations (LC10 and LC25) of an insect growth regulator, hexaflumuron on life expectancy (ex), stable age distribution (Cx), age-specific fertility (mx) and number of fertile eggs per day was investigated. Results showed that the sublethal doses of hexaflumuron

Mohammad Mahmoudvand; Habib Abbasipour; Aziz Sheikhi Garjan; Ali Reza Bandani

2011-01-01

200

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

201

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

ERIC Educational Resources Information Center

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

Scalice, Daniella; Wilmoth, Krisstina

2004-01-01

202

Distributed Brillouin fiber optic strain monitoring applications in advanced composite materials  

NASA Astrophysics Data System (ADS)

Composite materials based on glass, carbon and aramid fibers have many advantages such as fast application, lightweight and corrosion resistance, and are widely diffused for manufacturing of tanks, pipings and for restoration, upgrade and seismic retrofit of structures and historical heritage. As several questions regarding long term durability of composite strengthenings remains still unsolved, monitoring of strain and temperature is strongly recommended, respectively to assess proper load transfer and no glass phase transition of the polymeric matrix. In this research work strain and temperature distributed sensing trough Brillouin scattering in single-mode optical fibers was used in different tests in order to understand the influence of different fiber coatings and embedding techniques. Pressure tests were performed on a GFRP piping with inhomogeneous strengthening layout and Brillouin strain data were compared with conventional strain gages. A smart CFRP material has been also developed and evaluated in a seismic retrofit application on an historical building dated 1500 that was seriously damaged in the earthquake of 1997. The developed embedding technique has been demonstrated successful to obtain fiber-optic smart composites with low optical losses, and the data comparison between Brillouin and resistive strain gauges confirms Brillouin technique is very effective for composite monitoring.

Bastianini, Filippo; Cargnelutti, Mario; Di Tommaso, Angelo; Toffanin, Massimo

2003-08-01

203

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

204

Assessment of a Composite Right\\/Left-Handed Transmission Line-based Distributed Amplifier implemented in microstrip technology  

Microsoft Academic Search

The use of composite right\\/left-handed transmission lines (CRLH TLs) in the design of active distributed circuits such as distributed amplifiers or distributed mixers has led to potential new applications for these kinds of microwave circuits. In particular, CRLH TL-based distributed amplifiers (DAs), which exhibit multiband amplification performance, have recently been proposed by the authors. In this paper a microstrip implementation

J. Mata-Contreras; T. M. Martin-Guerrero; C. Camacho-Penalosa

2006-01-01

205

Characterization of reinforcement distribution in cast Al-alloy/SiC{sub p} composites  

SciTech Connect

The distribution of reinforcement in 10% SiC and 20% SiC{sub p} reinforced A356 alloy processed by gravity casting, squeeze casting, and roll casting is studied by using the mean free path, nearest neighbor distance, radial distribution function, and quadrat methods. The study is performed by using computer image analysis methods in an automated procedure to prevent operator errors, improve sample size, and minimize analysis time. From the methods used to characterize the SiC{sub p} distributions, the quadrat method and radial distribution function are found to be more effective in detecting pronounced changes in the metal-matrix composite (MMC) microstructure through appropriate parameters, whereas the mean free path is characteristic of the particular MMC system rather than process specific. Furthermore, the nearest neighbor distance is of little use in studying cast MMCs, because it is affected by local clusters of a few SiC particles commonly found in cast MMCs, thus failing to characterize the macroscopic arrangement of reinforcement. Quantitative methods present themselves as a useful tool for quality control in MMC fabrication and can be used to correlate particle distribution and properties of MMC systems.

Karnezis, P.A. [British Steel PLC, Rotherham (United Kingdom). Swinden Technology Centre; Durrant, G. [Rolls-Royce Aerospace Group, Derby (United Kingdom); Cantor, B. [Univ. of Oxford (United Kingdom). Dept. of Materials

1998-02-01

206

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

NASA Astrophysics Data System (ADS)

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

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

207

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

208

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

Microsoft Academic Search

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

M. Q. Brewster; J. C. Mullen

2011-01-01

209

Somatic maintenance resources in the honeybee worker fat body are distributed to withstand the most life-threatening challenges at each life stage.  

PubMed

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

2013-08-05

210

Effective medium approximation for weakly nonlinear metal/dielectric composites with shape distribution  

NASA Astrophysics Data System (ADS)

The effective linear and nonlinear optical properties of metal/dielectric composite media in which the components possess certain shape distribution are investigated. Based on a self-consistent condition of zero net dipole moment, we derive Bruggeman-type effective medium approximation with shape distribution, which has been established using the reciprocity theorem [Solid State Commun. 106 (1998) 83]. Spectral density functions are analytically obtained to obey the requirements of Bergman spectral representation. The real part of the effective conductivity, the energy-loss function and the linear optical absorption are calculated accordingly. By invoking the mean-field approximation, we further evaluate the effective optical nonlinearity enhancement. Numerical results show that the nonlinearity enhancement maximum is separated from the optical absorption one especially at large volume fraction. Moreover, the optical nonlinearity enhancement and the figure of merit are found to be greatly enhanced near the bulk plasma frequency.

Gao, Lei

2003-03-01

211

Optimal vibration control of a rotating composite beam with distributed piezoelectric sensing and actuation  

NASA Astrophysics Data System (ADS)

A rotating composite blade, modeled as a box-beam with transverse shear flexibility, shear-tractionless bounding faces and restrained warping, and subjected to a time dependent pressure pulse is considered. It comprises an orthotropic (graphite-epoxy laminate) host structure with surface embedded and spanwise distributed transversely isotropic (PZT-4) sensors and actuators. The total current output from the sensors is distributed to the actuators after suitable weighting. A modified Galerkin method using only admissible functions is considered, and the optimal control problem is studied via the classical and instantaneous LQR methods. Results reveal that structural tailoring can yield a lower steady-state response at the expense of increased settling time. Increasing the patch length beyond a limit proves ineffective. The instantaneous LQR control algorithm provides a reduced response, as does the present model involving through-thickness shear strain variation. Studies regarding the effect of location and weighting of piezopatches on the controlled response are presented.

Chandiramani, N. K.; Librescu, L. I.; Saxena, V.; Kumar, A.

2004-04-01

212

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

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

213

A compact analytic method for stress distribution in composite pinned joints  

NASA Astrophysics Data System (ADS)

An analysis was performed to evaluate the stress distribution in composite pin loaded joints. In this analysis involving a push fit pin, the pin was modeled as rigid and the plate as an infinite orthotropic plate. The analysis involves first the specification of displacement expressions in form of a trigonometric series that satisfy the boundary conditions for the contact region in terms of a set of undetermined coefficients. Based on this assumed distribution, the Lekhnitskii complex variable approach is used to obtain the stress functions needed to evaluate the contact stress within the joint. Unknown coefficients in the displacement expression were obtained by assuming coulomb friction within the contact region and then evaluating the displacement at discrete points within this region. Material properties of carbon fiber reinforced plastic laminates and a graphite-epoxy laminate was used for the study and the stress distribution for various values of coefficient of friction analyzed and the results compared with the previous investigations. This analysis reveals that friction has a pronounced effect on stress distribution around the hole boundary.

Aluko, Olanrewaju

214

Electric field distribution around the chain of composite nanoparticles in ferrofluids  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

215

Composition, diversity and distribution of microbenthos across the intertidal zones of Ryazhkov Island (the White Sea).  

PubMed

The composition and distribution of the main unicellular eukaryotic groups (diatom algae, ciliates, dinoflagellates (DF), other phototrophic (PF) and heterotrophic flagellates (HF)) were investigated in sandy sediments at five stations allocated across the tidal sheltered beach of the White Sea. Overall, 75 diatoms, 98 ciliates, 16 DF, 3 PF and 34 HF species were identified; some are new records for the White Sea. Common species for each group are illustrated. Diatoms and ciliates showed high alpha-diversity (species richness per sample), whereas flagellates were characterized by high beta-diversity (species turnover across the intertidal flat). Each group demonstrated its own spatial pattern that was best matched with its own subset of abiotic variables, reflecting group-specific responses to environmental gradients. Species richness increased from the upper intertidal zone seaward for ciliates but decreased for HF, whereas autotrophs showed a relatively uniform pattern with a slight peak at the mid-intertidal zone. Across the littoral zone, all groups showed distinct compositional changes; however, the position of the boundary between "upper" and "lower" intertidal communities varied among groups. Most of the species found at Ryazhkov Island are known from many other regions worldwide, indicating a wide geographic distribution of microbial eukaryotic species. PMID:23871644

Azovsky, Andrey; Saburova, Maria; Tikhonenkov, Denis; Khazanova, Ksenya; Esaulov, Anton; Mazei, Yuri

2013-07-18

216

Effect of changes in epidemiological factors on the composition and racial distribution of renal calculi.  

PubMed

One thousand and two calculi, which occurred in both black and white patients during a 15-year period, have been analysed by the X-ray diffraction technique. Calcium oxalate calculi were the most common irrespective of race. Whewellite calculi were equally distributed in both race groups, while weddelite stones appeared to be much less common amongst blacks; the opposite applied for struvite and the rare ammonium acid urate stones. The other calculi were approximately equally distributed between the two race groups. A statistically significant rising trend in the prevalence of renal stones in blacks, accompanied by changes in the ratios of the major stone forming constituents, have been a prominent feature of this survey. However, the aforementioned remained unchanged in white patients. Contrary to previous impressions, total urates exceed phosphates in whites as a major stone forming constituent. The composition of upper urinary tract stones in blacks, during the 3-year period 1981 to 1983, was very similar to the composition previously reported for the Sudanese. The profile of renal stones in blacks over the last 3 years, however, is now becoming substantially different from that of the other previously reported surveys and may be approaching that of their white compatriots. A change in the dietary patterns in blacks is occurring which is also reflected in an increasing incidence of ischaemic heart disease and which may also be responsible for the observed changes in renal stones. PMID:3427314

Beukes, G J; de Bruiyn, H; Vermaak, W J

1987-11-01

217

A new decoupling method for accurate quantification of polyethylene copolymer composition and triad sequence distribution with 13C NMR.  

PubMed

(13)C NMR is a powerful analytical tool for characterizing polyethylene copolymer composition and sequence distribution. Accurate characterization of the composition and sequence distribution is critical for researchers in industry and academia. Some common composite pulse decoupling (CPD) sequences used in polyethylene copolymer (13)C NMR can lead to artifacts such as modulations of the decoupled (13)C NMR signals (decoupling sidebands) resulting in systematic errors in quantitative analysis. A new CPD method was developed, which suppresses decoupling sidebands below the limit of detection (less than 1:40,000 compared to the intensity of the decoupled signal). This new CPD sequence consists of an improved Waltz-16 CPD, implemented as a bilevel method. Compared with other conventional CPD programs this new decoupling method produced the cleanest (13)C NMR spectra for polyethylene copolymer composition and triad sequence distribution analyses. PMID:17524686

Zhou, Zhe; Kümmerle, Rainer; Qiu, Xiaohua; Redwine, David; Cong, Rongjuan; Taha, Angela; Baugh, Dan; Winniford, Bill

2007-05-23

218

Fatigue, fracture, and life prediction criteria for composite materials in magnets  

Microsoft Academic Search

An explosively-bonded copper\\/Inconel 718\\/copper laminate conductor was proposed to withstand the severe face compression stresses in the central core of the Alcator C-MOD tokamak toroidal field (TF) magnet. Due to the severe duty of the TF magnet, it is critical that an accurate estimate of useful life be determined. As part of the effort to formulate an appropriate life prediction,

1990-01-01

219

Modeling Research of Short-Life-Cycle Product Supply Chain Based on Composite Model  

Microsoft Academic Search

This paper puts forward the concept of supply chain in short-life-cycle products and analyses the character of this type of supply chain. Then previous researches on short-life-cycle product supply chain are reviewed, and the management problems that exist in supply chain modeling are discussed. According to the character of this supply chain and on the basis of research review on

Changli Feng; Jing Zhao

2007-01-01

220

Modeling and Life Prediction Methodology for Titanium Matrix Composites Subjected to Mission Profiles.  

National Technical Information Service (NTIS)

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...

M. Mirdamadi W. S. Johnson

1994-01-01

221

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

SciTech Connect

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

Sumich, M.; Kedward, K.T.

1991-02-01

222

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

223

Comparative life cycle studies on poly(3-hydroxybutyrate)-based composites as potential replacement for conventional petrochemical plastics.  

PubMed

A cradle-to-grave environmental life cycle assessment (LCA) of a few poly(3-hydroxybutyrate) (PHB) based composites has been performed and was compared to commodity petrochemical polymers. The end products studied are a cathode ray tube (CRT) monitor housing (conventionally produced from high-impact polystyrene, HIPS) and the internal panels of an average car (conventionally produced from glass-fibers-filled polypropylene, PP-GF). The environmental impact is evaluated on the basis of nonrenewable energy use (NREU) and global warming potential over a 100 years time horizon (GWP100). Sugar cane bagasse (SCB) and nanoscaled organophilic montmorillonite (OMMT) are used as PHB fillers. The results obtained show that, despite the unsatisfying mechanical properties of PHB composites, depending on the type of filler and on the product, it is possible to reach lower environmental impacts than by use of conventional petrochemical polymers. These savings are mainly related to the PHB production process, while there are no improvements related to composites preparation. SCB-based composites seem to be environmentally superior to clay-based ones. PMID:17583946

Pietrini, Matteo; Roes, Lex; Patel, Martin K; Chiellini, Emo

2007-06-21

224

[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

225

Distribution of gaseous and particulate organic composition during dark ozonolysis of monoterpenes  

NASA Astrophysics Data System (ADS)

Secondary organic aerosol (SOA) affects atmospheric composition, air quality and radiative transfer. However, major difficulties are encountered in the development of reliable models for SOA formation. Constraints on processes involved in SOA formation can be obtained by interpreting the speciation and evolution of organics in the gaseous and condensed phases simultaneously. In this study we investigate SOA formation from dark ozonolysis of ?-pinene with particular emphasis upon the mass distribution of gaseous and particulate organic species. Experiments were performed in the EUropean PHOtoREactor (EUPHORE) simulation chamber, including on-line gas-phase composition obtained from Chemical-Ionization-Reaction Time-Of-Flight Mass-Spectrometry (CIR-TOF-MS) measurements, and off-line analysis of SOA samples performed by Electrospray Ionisation Ion Trap Mass Spectrometry (ESI-MS). A detailed chamber box model designed to simulate SOA formation was developed for comparison with the experimental results, coupling an equilibrium gas/particle partitioning module to the ?-pinene oxidation scheme extracted from the Master Chemical Mechanism (MCMv3.1). The simulated temporal profile of SOA mass is in reasonable agreement with the observations, both in terms of the shape and magnitude. Sensitivity analysis highlights the importance of the choice of vapour pressure estimation method. Comparisons of the simulated mass spectrum with the CIR-TOF-MS mass spectrum show a similar mass distribution for gaseous organics. The ESI-MS measurements show the presence in the condensed phase of monomer and oligomer type organics. Comparisons of the simulated condensed phase mass spectrum with the ESI-MS mass spectrum show that most of the peaks in the monomer region are in reasonable agreement, i.e. explained in the simulation by the gas/particle partitioning of semi-volatile organic compounds (SVOC) formed during the ?-pinene gas-phase oxidation. The simulated composition is used to (i) propose chemical structures for the principal gaseous SVOC and condensed monomer organic species and (ii) explore the possible contribution of a range of accretion reactions occurring in the condensed phase. We find that oligomer formation through esterification reactions gives the best agreement between the observed and simulated mass spectra. Extending this approach to characterise the gaseous and particulate organic composition from other organic precursors, under various experimental conditions, will help greatly our understanding SOA formation, and therefore assist in the development of reliable SOA schemes for incorporation into 3D chemical transport models.

Camredon, Marie; Hamilton, Jacqui F.; Alam, Mohammed S.; Wyche, Kevin P.; Carr, Timo; White, Iain R.; Monks, Paul S.; Rickard, Andrew R.; Bloss, William J.

2010-05-01

226

Clinical Significance of the Multiple Sclerosis Functional Composite: Relationship to Patient-Reported Quality of Life  

Microsoft Academic Search

Background: The Multiple Sclerosis Functional Com- posite (MSFC) was recommended by a task force of the National Multiple Sclerosis Society as a new clinical out- come measure for clinical trials. The task force recom- mended that the MSFC be validated against other measures of the disease, such as patient-reported quality of life. Methods: Three hundred patients with multiple scle- rosis

Deborah M. Miller; Richard A. Rudick; Gary Cutter; Monika Baier; Jill S. Fischer

2000-01-01

227

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

National Technical Information Service (NTIS)

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...

J. D. Vienna J. S. McCloy

2010-01-01

228

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

229

[Population, distribution and food composition of wolves (Canis lupus) at Saihanwula Nature Reserve, Inner Mongolia].  

PubMed

To provide initial value for population restoration and management of wolves (Canis lupus) in the wild, line transect survey and fecal analysis method were used to study the population ecology of wolf at Saihanwula National Nature Reserve, Inner Mongolia. The results revealed that the population number was at least seven within the reserve and population density was 4.18+/-2.88 individual per 100 km2. The wolf population was mainly distributed in Shengshan and Qinyunshan core areas; active sites appeared mostly along mountain ridges, roads and valleys at Shengshan and mountain ridges at Qinyunshan. Hare (Lepus capensis) and plants occurred frequently in the food composition of wolf scats. Food types varied between years but not seasons (Winter-Spring and Summer-Autumn). PMID:21509971

Chen, Jiu-Yi; Zhang, Li-Jia; Wang, An-Meng; Bater; Nasendelger; Yuan, Li; Bao, Wei-Dong

2011-04-01

230

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

231

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

232

Distribution of gaseous and particulate organic composition during dark ?-pinene ozonolysis  

NASA Astrophysics Data System (ADS)

Secondary Organic Aerosol (SOA) affects atmospheric composition, air quality and radiative transfer, however major difficulties are encountered in the development of reliable models for SOA formation. Constraints on processes involved in SOA formation can be obtained by interpreting the speciation and evolution of organics in the gaseous and condensed phase simultaneously. In this study we investigate SOA formation from dark ?-pinene ozonolysis with particular emphasis upon the mass distribution of gaseous and particulate organic species. A detailed model for SOA formation is compared with the results from experiments performed in the EUropean PHOtoREactor (EUPHORE) simulation chamber, including on-line gas-phase composition obtained from Chemical-Ionization-Reaction Time-Of-Flight Mass-Spectrometry measurements, and off-line analysis of SOA samples performed by Ion Trap Mass Spectrometry and Liquid Chromatography. The temporal profile of SOA mass concentration is relatively well reproduced by the model. Sensitivity analysis highlights the importance of the choice of vapour pressure estimation method, and the potential influence of condensed phase chemistry. Comparisons of the simulated gaseous- and condensed-phase mass distributions with those observed show a generally good agreement. The simulated speciation has been used to (i) propose a chemical structure for the principal gaseous semi-volatile organic compounds and condensed monomer organic species, (ii) provide evidence for the occurrence of recently suggested radical isomerisation channels not included in the basic model, and (iii) explore the possible contribution of a range of accretion reactions occurring in the condensed phase. We find that oligomer formation through esterification reactions gives the best agreement between the observed and simulated mass spectra.

Camredon, M.; Hamilton, J. F.; Alam, M. S.; Wyche, K. P.; Carr, T.; White, I. R.; Monks, P. S.; Rickard, A. R.; Bloss, W. J.

2010-03-01

233

Age-related changes in the metabolism and body composition of three dog breeds and their relationship to life expectancy.  

PubMed

We measured body composition and resting metabolic rates (RMR) of three dog breeds (Papillons, mean body mass 3.0 kg (n = 35), Labrador retrievers, mean body mass 29.8 kg (n = 35) and Great Danes, mean body mass 62.8 kg (n = 35)) that varied between 0.6 and 14.3 years of age. In Papillons, lean body mass (LBM) increased with age but fat mass (FBM) was constant; in Labradors, both LBM and FBM were constant with age, and in Great Danes, FBM increased with age but LBM was constant. FBM averaged 14.8% and 15.7% of body mass in Papillons and Labradors, respectively. Great Danes were leaner and averaged only 10.5% FBM. Pooling the data for all individuals, the RMR was significantly and positively associated with LBM and FBM and negatively associated with age. Once these factors had been taken into account there was still a significant breed effect on RMR, which was significantly lower in Labradors than in the other two breeds. Using the predictive multiple regression equation for RMR and the temporal trends in body composition, we modelled the expenditure of energy (at rest) over the first 8 years of life, and over the entire lifespan for each breed. Over the first 8 years of life the average expenditure of energy per kg LBM were 0.985, 0.675 and 0.662 GJ for Papillons, Labradors and Great Danes, respectively. This energy expenditure was almost 60% greater for the smallest compared with the largest breed. On average, however, the life expectancy for the smallest breed was a further 6 years (i.e. 14 years in total), whereas for the largest breed it was only another 6 months (i.e. 8.5 years in total). Total lifetime expenditure of energy at rest per kg LBM averaged 1.584, 0.918 and 0.691 GJ for Papillons, Labradors and Great Danes, respectively. In Labradors, total daily energy expenditure, measured by the doubly labelled water method in eight animals, was only 16% greater than the observed RMR. High energy expenditure in dogs appears positively linked to increased life expectancy, contrary to the finding across mammal species and within exotherms, yet resembling observations in other intra-specific studies. These contrasting correlations suggest that metabolism is affecting life expectancy in different ways at these different levels of enquiry. PMID:14570234

Speakman, J R; van Acker, A; Harper, E J

2003-10-01

234

The Effect of Early Menarche on Later Body Composition and Fat Distribution in Female Adolescents: Role of Birth Weight  

Microsoft Academic Search

Background: To examine the effect of early menarche (EM) on adolescent body composition and fat distribution, and to explore the possible contribution of birth weight (BW) to this relationship. Methods: From the cross-sectional AVENA study, 788 girls (aged 13–18.5 years) were selected. Post-menarcheal body composition was estimated by anthropometric methods. Results: BW Z-score was associated with age at menarche (?

Idoia Labayen; Francisco B. Ortega; Luis A. Moreno; Carlos Redondo-Figuero; Gloria Bueno; Sonia Gómez-Martínez; Manuel Bueno

2009-01-01

235

A highly efficient user-defined finite element for load distribution analysis of large-scale bolted composite structures  

Microsoft Academic Search

This paper presents the development of a highly efficient user-defined finite element for modelling the bolt–load distribution in large-scale composite structures. The method is a combined analytical\\/numerical approach and is capable of representing the full non-linear load–displacement behaviour of bolted composite joints both up to, and including, joint failure. In the elastic range, the method is generic and is a

P. J. Gray; C. T. McCarthy

2011-01-01

236

Determination of the chemical composition distribution of copolymers of styrene and butadiene by gradient polymer elution chromatography  

Microsoft Academic Search

In order to determine the chemical composition distribution (CCD) of styrene-butadiene copolymers, gradient polymer elution chromatography has been performed. The separation is mainly based on differences in solubility among the copolymer molecules with different chemical composition. The solubility of a copolymer is dependent on the following parameters: temperature, type of solvent\\/non-solvent mixture, molecular mass of the polymer and the chemical

P. J. C. H. Cools; F. Maesen; B. Klumperman; A. M. van Herk; A. L. German

1996-01-01

237

Carbon isotope composition of boreal plants: functional grouping of life forms  

Microsoft Academic Search

We tested the hypothesis that life forms (trees, shrubs, forbs, and mosses; deciduous or evergreen) can be used to group\\u000a plants with similar physiological characteristics. Carbon isotope ratios (?13C) and carbon isotope discrimination (?) were used as functional characteristics because ?13C and ? integrate information about CO2 and water fluxes, and so are useful in global change and scaling studies.

J. R. Brooks; Lawrence B. Flanagan; N. Buchmann; James R. Ehleringer

1997-01-01

238

Does diet breadth control herbivorous insect distribution size? Life history and resource outlets for specialist butterflies  

Microsoft Academic Search

Although butterfly distributions are known to be positively correlated with the number of larval hostplants used it is not known to what extent larval hostplant number uniquely influences butterfly distributions and to what extent effects are indirect through other variables. This issue is central to understanding the part generalism and specialism in host use play in organism persistence and conservation.

Roger L. H. Dennis; Tim G. Shreeve; Henry R. Arnold; David B. Roy

2005-01-01

239

Longitudinal variation of thermospheric neutral winds and composition and their effects on the F region electron density distribution  

NASA Astrophysics Data System (ADS)

Longitudinal variations of thermospheric neutral winds and composition at mid-latitudes and their effects on the F region ionosphere electron density distribution are investigated using the Utah State University Global Assimilation of Ionospheric Measurements (USU-GAIM) model. For this study, seasonally averaged radio occultation data from the six FORMOSAT-3/COSMIC satellites were assimilated by the model. The data assimilation model is based on an Ensemble Kalman filter technique and a physics-based model of the ionosphere/plasmasphere (IPM). The model calculates 3-dimensional plasma density distribution in the ionosphere and estimates the physical drivers, including the magnetic meridional wind and neutral composition. The geographic zonal and meridional winds are then inferred from the magnetic meridional wind based on a decoupling procedure that considers the longitudinal variation of magnetic declination and a wind decomposition into zonal harmonics. In order to stud! y the relative role of zonal variations of neutral wind, neutral composition and the magnetic field direction in the F region electron density distribution, additional simulations with the IPM model were performed considering different harmonic components of the estimated neutral wind and neutral composition. Model calculations were also performed using HWM93 and HWM07 empirical winds and the resulting densities and corresponding winds were compared with the USU-GAIM results. The results indicate that longitudinal changes in the geomagnetic field geometry play a major role in the F region electron density distribution but zonal changes in the neutral wind and composition can also be important.

Lomidze, L.; Scherliess, L.

2012-12-01

240

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

241

Psychological state, quality of life, and body composition in postmenopausal women with osteoporosis in Lithuania  

Microsoft Academic Search

Summary  The objective of this study was to determine body composition, physical activity, and psychological state in postmenopausal\\u000a women with osteoporosis. Fat mass, lean mass, water mass, and basal metabolic rate are lower, self-reported physical activity\\u000a and risk factors of fractures are higher, and cognitive functions were worse in osteoporotic patients than in controls. Significant\\u000a correlations were found between physical activity

Lina Lasaite; Aurelija Krasauskiene

2009-01-01

242

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

243

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

Microsoft Academic Search

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

Huw J. Griffiths; Richard Kazimierz Frank Unsworth

2010-01-01

244

The influence of birthweight and intrauterine environment on adiposity and fat distribution in later life  

Microsoft Academic Search

OBJECTIVE: To review the literature on the association between birthweight and body mass index (BMI) and obesity in later life.METHODS: Included in the review were papers appearing in Medline since 1966 and identified using the search terms obesity, body fat, waist, body constitution, birthweight and birth weight. Further papers were identified by examining bibliographies.RESULTS: There is good evidence that there

I Rogers

2003-01-01

245

Lobar Distribution of Lesion Volumes in Late-Life Depression: The Biomedical Informatics Research Network (BIRN)  

Microsoft Academic Search

White matter hyperintense lesions on T2-weighted images are associated with late-life depression. Little work has been carried out examining differences in lesion location between elderly individuals with and without depression. In contrast to previous studies examining total brain white matter lesion volume, this study examined lobar differences in white matter lesion volumes derived from brain magnetic resonance imaging. This study

James R MacFall; Warren D Taylor; David E Rex; Steve Pieper; Martha E Payne; Douglas R McQuoid; David C Steffens; Ron Kikinis; Arthur W Toga; K Ranga Rama Krishnan; JR MacFall

2006-01-01

246

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

247

Vertical distribution and composition of phytoplankton under the influence of an upper mixed layer.  

PubMed

The vertical distribution of phytoplankton is of fundamental importance for the dynamics and structure of aquatic communities. Here, using an advection-reaction-diffusion model, we investigate the distribution and competition of phytoplankton species in a water column, in which inverse resource gradients of light and a nutrient can limit growth of the biomass. This problem poses a challenge for ecologists, as the location of a production layer is not fixed, but rather depends on many internal parameters and environmental factors. In particular, we study the influence of an upper mixed layer (UML) in this system and show that it leads to a variety of dynamic effects: (i) Our model predicts alternative density profiles with a maximum of biomass either within or below the UML, thereby the system may be bistable or the relaxation from an unstable state may require a long-lasting transition. (ii) Reduced mixing in the deep layer can induce oscillations of the biomass; we show that a UML can sustain these oscillations even if the diffusivity is less than the critical mixing for a sinking phytoplankton population. (iii) A UML can strongly modify the outcome of competition between different phytoplankton species, yielding bistability both in the spatial distribution and in the species composition. (iv) A light limited species can obtain a competitive advantage if the diffusivity in the deep layers is reduced below a critical value. This yields a subtle competitive exclusion effect, where the oscillatory states in the deep layers are displaced by steady solutions in the UML. Finally, we present a novel graphical approach for deducing the competition outcome and for the analysis of the role of a UML in aquatic systems. PMID:19896955

Ryabov, Alexei B; Rudolf, Lars; Blasius, Bernd

2009-11-06

248

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

Microsoft Academic Search

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

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

2006-01-01

249

Composition and size distribution of submicrometer aerosol particles observed on Mt. Fuji in the volcanic plumes from Miyakejima  

Microsoft Academic Search

An aerosol observation campaign was conducted at the summit of Mt. Fuji (at an altitude of 3776m), which is located 170km northwest of Miyakejima. Individual aerosol particles were collected with an electrostatic aerosol sampler and the number–size distribution and composition were examined by electron microscopy. Number–size distributions were measured with the combination of a diffusion battery (DB) and a condensation

Hiroaki Naoe; Jost Heintzenberg; Kikuo Okada; Yuji Zaizen; Kazuhiko Hayashi; Takahiro Tateishi; Yasuhito Igarashi; Yukiko Dokiya; Kisei Kinoshita

2003-01-01

250

Prolongation of ifosfamide elimination half-life in obese patients due to altered drug distribution  

Microsoft Academic Search

The pharmacokinetics of intravenous ifosfamide were determined in 16 patients with carcinoma of the bronchus. In all 25% (4) of these patients were obese (i.e. >20% over their ideal body weight). The terminal elimination half-life (t1\\/2 ß) was found to be higher in the obese group than in the control group (6.36 h, range 5.77–7.45 h) vs 4.95 h, range

M. J. Lind; J. M. Margison; T. Cerny; N. Thatcher; P. M. Wilkinson

1989-01-01

251

The interaction of guarantees, surplus distribution, and asset allocation in with-profit life insurance policies  

Microsoft Academic Search

Traditional life insurance policies in many markets are sold with minimum interest rate guarantees. This paper concentrates on the risk cliquet-style guarantees impose on the insurer, measured by shortfall probabilities under the so-called “real-world probability measure P”. We develop a general model and analyze the impact of interest rate guarantees on the risk of an insurance company. Furthermore the paper

Alexander Kling; Andreas Richter; Jochen Ruß

2007-01-01

252

Monomer Abundance Distribution Patterns as a Universal Biosignature: Examples from Terrestrial and Digital Life  

Microsoft Academic Search

Organisms leave a distinctive chemical signature in their environment because they synthesize those molecules that maximize\\u000a their fitness. As a result, the relative concentrations of related chemical monomers in life-bearing environmental samples\\u000a reflect, in part, those compounds’ adaptive utility. In contrast, rates of molecular synthesis in a lifeless environment are dictated by reaction kinetics and thermodynamics,\\u000a so concentrations of related

Evan D. Dorn; Kenneth H. Nealson; Christoph Adami

2011-01-01

253

Composition and distribution of sublittoral zoobenthos in Kemskaya Bay of the White Sea  

NASA Astrophysics Data System (ADS)

Data on the distribution of the zoobenthos in Kemskaya Bay (the Kem’ River estuary and the White Sea), which is subject to the strong influence of the river discharge, are presented. The number of species at the sampling stations varied from 4 to 65. The density of the communities and the zoobenthos biomass ranged from 342 ± 68 to 4293 ± 96 ind./m2 and from 0.418 ± 0.081 to 1975.22 ± 494.36 g/m2, respectively. The Shannon index values varied between 1.19 to 4.7 bit/ind. At the upper part of the estuary, detritivores dominated, while, in the central part and at outlets, sestonophages prevailed. The changes in the quantitative indices of the zoobenthos along the gradient of the water salinity were traced, and the relations of these indices with seven more environmental factors were revealed. It was found that the species composition, the biodiversity, and the trophic structure of the zoobenthos significantly correlate with some of the above mentioned parameters. Multiple regression analysis was used to assess the combined effect of the factors, and it revealed which of them play a determining role in Kemskaya Bay: for the species composition, these are the depth, the water color, and the content of total suspended matter; for the number, these are the contents of pelite and Corg in the bottom sediments. The biomass depends on the water salinity, the water chromaticity, and the Corg contents in the sediments and suspended matter. The Shannon index value is determined by the water color, the Corg contents in the sediments, and the pelite content. The calculations of the ecological stress values revealed two zones with an unstable state of the zoobenthos.

Denisenko, N. V.

2009-12-01

254

[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

255

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

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

256

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

257

Nutrient composition of banked human milk in brazil and influence of processing on zinc distribution in milk fractions  

Microsoft Academic Search

OBJECTIVE AND METHODS: We measured the contents of fat, protein, lactose, calcium, phosphorus, zinc, iron, copper, and vitamin A in processed mature milk samples (individual, n = 60, and pooled, n = 10) from a reference human milk bank in Brazil and assessed the effect of pasteurization followed by freezing on the nutrient composition and the pattern of zinc distribution

Helo??sa C. A Góes; Alexandre G Torres; Carmen M Donangelo; Nadia M. F Trugo

2002-01-01

258

Studies on the compartmentation of lipid in adipose cells. I: Subcellular distribution, composition, and transport of newly synthesized lipid: liposomes  

Microsoft Academic Search

The subcellular distribution and composition of endogenously synthesized lipid in isolated white adipose cells were studied to determine the nature and extent of lipid compartmentation. After brief incubation of cells with labeled glucose, acetate, or palmitic acid, over 90% of newly syn- thesized triglyceride was localized in the bulk-lipid phase, indicating rapid intracellular transport and storage. From 13 to 20%

AUBIE ANGEL

2010-01-01

259

Initial Trial using Embedded Fibre Bragg Gratings for Distributed Strain Monitoring in a Shape Adaptive Composite Foil.  

National Technical Information Service (NTIS)

This technical note reports on the embedment and testing of a series of distributed optical fibre sensors embedded just beneath the top and bottom surfaces of a shape adapative composite foil. The sensors were monitored during the resin infusion and curin...

C. Davis D. Rowlands J. Kopczyk P. Norman

2012-01-01

260

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

261

Space charge distributions in glass fibre/epoxy resin composites under dc 10 kV mm-1 electric field  

NASA Astrophysics Data System (ADS)

In this paper, the authors discuss one- and three-dimensional space charge distributions in glass fibre/epoxy resin composites. By the conventional pulsed electroacoustic (PEA) method, only a one-dimensional distribution of the average charge over a whole area parallel to the two electrodes can be observed. Therefore, the authors have developed a new PEA system capable of measuring a three-dimensional space charge distribution. Using this system, they measured the charge distribution in glass fibre/epoxy resin composites made of lattice-woven glass fibre and epoxy resin. It has become clear that spatial variation in signal intensity observed depends on the internal structure of the composite. There appear repetitious positions where a high charge density is observed on the same lateral cross section along the vertical direction in the composite. Such positions are consistent with the intersections of the glass fibres. Accumulation of mobile charge carriers or appearance of polarization charge due to mismatch of the ratio of the conductivity and permittivity between the glass fibre and the epoxy resin is thought to be responsible for the PEA signals.

Tanaka, Hidesato; Ohki, Yoshimichi; Fukunaga, Kaori; Maeno, Takashi; Okamoto, Kenji

2007-03-01

262

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

263

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.

Ruf, Thomas

2010-01-01

264

Residual stress distribution in an Al{sub 2}O{sub 3}-Ni joint bonded with a composite layer  

SciTech Connect

Neutron diffraction was used to study the residual stress distribution in an axisymmetric Al{sub 2}O{sub 3}-Ni joint bonded with a 40 vol% Al{sub 2}O{sub 3}-60 vol% Ni composite layer. A series of measurements was taken along the axis of symmetry through the Al{sub 2}O{sub 3} and composite layers. It is shown that after taking into account the finite neutron diffraction sampling volume, both the trends and peak values of the experimental strain distribution were in excellent agreement with calculations of a simple finite element model, where the rule-of-mixtures approach was used to describe the constitutive behavior of the composite interlayer. In particular, the predicted steep strain gradient near the interface was confirmed by the experimental data.

Wang, X.L.; Watkins, T.R. [Oak Ridge National Lab., TN (United States); Rabin, B.H.; Williamson, R.L.; Bruck, H.A. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

1996-07-01

265

The causal differential scattering approach to calculating the effective properties of random composite materials with a particle size distribution  

NASA Astrophysics Data System (ADS)

An implementation of the Causal Differential Method (CDM) for modelling the effective properties of a random two-phase composite material is presented. Such materials are commonly used as ultrasonic transducer matching layers or backing layers. The method is extended to incorporate a particle size distribution in the inclusion phase. Numerical issues regarding the implementation and convergence of the method are discussed. It is found that, for a given frequency of excitation, the calculated velocity for the composite has a distribution whose variance increases as the volume fraction of inclusions increases. The model predictions would suggest that to reliably and repeatedly manufacture these composites, with a desired mechanical impedance, a low volume fraction of inclusions should be used.

Young, A.; Mulholland, A. J.; O'Leary, R. L.

266

DNA search efficiency is modulated by charge composition and distribution in the intrinsically disordered tail.  

PubMed

Intrinsically disordered tails are common in DNA-binding proteins and can affect their search efficiency on nonspecific DNA by promoting the brachiation dynamics of intersegment transfer. During brachiation, the protein jumps between distant DNA regions via an intermediate state in which the tail and globular moieties are bound to different DNA segments. While the disordered tail must be long and positively charged to facilitate DNA search, the effect of its residue sequence on brachiation is unknown. We explored this issue using the NK-2 and Antp homeodomain transcription factors. We designed 566 NK-2 tail-variants and 55 Antp tail-variants having different net charges and positive charge distributions and studied their dynamics and DNA search efficiencies using coarse-grained molecular dynamics simulations. More intersegment transfers occur when the tail is moderately positively charged and the positive charges are clustered together in the middle of the tail or towards its N terminus. The presence of a negatively charged residue does not significantly affect protein brachiation, although it is likely that the presence of many negatively charged residues will complicate the DNA search mechanism. A bioinformatic analysis of 1,384 wild-type homeodomains illustrates that the charge composition and distribution in their N-tail sequences are consistent with an optimal charge pattern to promote intersegment transfer. Our study thus indicates that the residue sequence of the disordered tails of DNA-binding proteins has unique characteristics that were evolutionarily selected to achieve optimized function and suggests that the sequence-structure-function paradigm known for structured proteins is valid for intrinsically disordered proteins as well. PMID:21078959

Vuzman, Dana; Levy, Yaakov

2010-11-15

267

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

...LIFE ESTATES AND FUTURE INTERESTS Life Estates Not Created Under AIPRA...principal and income to the holder of a life estate? (a) This section applies...cases: (1) Where the document creating the life estate does not specify a...

2010-04-01

268

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

...LIFE ESTATES AND FUTURE INTERESTS Life Estates Not Created Under AIPRA...principal and income to the holder of a life estate? (a) This section applies...cases: (1) Where the document creating the life estate does not specify a...

2009-04-01

269

Crustacea in Arctic and Antarctic sea ice: distribution, diet and life history strategies.  

PubMed

This review concerns crustaceans that associate with sea ice. Particular emphasis is placed on comparing and contrasting the Arctic and Antarctic sea ice habitats, and the subsequent influence of these environments on the life history strategies of the crustacean fauna. Sea ice is the dominant feature of both polar marine ecosystems, playing a central role in physical processes and providing an essential habitat for organisms ranging in size from viruses to whales. Similarities between the Arctic and Antarctic marine ecosystems include variable cover of sea ice over an annual cycle, a light regimen that can extend from months of total darkness to months of continuous light and a pronounced seasonality in primary production. Although there are many similarities, there are also major differences between the two regions: The Antarctic experiences greater seasonal change in its sea ice extent, much of the ice is over very deep water and more than 80% breaks out each year. In contrast, Arctic sea ice often covers comparatively shallow water, doubles in its extent on an annual cycle and the ice may persist for several decades. Crustaceans, particularly copepods and amphipods, are abundant in the sea ice zone at both poles, either living within the brine channel system of the ice-crystal matrix or inhabiting the ice-water interface. Many species associate with ice for only a part of their life cycle, while others appear entirely dependent upon it for reproduction and development. Although similarities exist between the two faunas, many differences are emerging. Most notable are the much higher abundance and biomass of Antarctic copepods, the dominance of the Antarctic sea ice copepod fauna by calanoids, the high euphausiid biomass in Southern Ocean waters and the lack of any species that appear fully dependent on the ice. In the Arctic, the ice-associated fauna is dominated by amphipods. Calanoid copepods are not tightly associated with the ice, while harpacticoids and cyclopoids are abundant. Euphausiids are nearly absent from the high Arctic. Life history strategies are variable, although reproductive cycles and life spans are generally longer than those for temperate congeners. Species at both poles tend to be opportunistic feeders and periods of diapause or other reductions in metabolic expenditure are not uncommon. PMID:16905428

Arndt, Carolin E; Swadling, Kerrie M

2006-01-01

270

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

271

Characterization of distributions by relationships between failure rate and mean residual life  

Microsoft Academic Search

The characterizations described use relations between the failure rate function and conditional expectation. The theorems proved here extend the results of some authors and can be used in the context of the renewal process. The utility of these results is demonstrated by using them to characterize some common distributions

J. M. Ruiz; Jorge Navarro

1994-01-01

272

Simple Sequence Repeats in Escherichia coli: Abundance, Distribution, Composition, and Polymorphism  

PubMed Central

Computer-based genome-wide screening of the DNA sequence of Escherichia coli strain K12 revealed tens of thousands of tandem simple sequence repeat (SSR) tracts, with motifs ranging from 1 to 6 nucleotides. SSRs were well distributed throughout the genome. Mononucleotide SSRs were over-represented in noncoding regions and under-represented in open reading frames (ORFs). Nucleotide composition of mono- and dinucleotide SSRs, both in ORFs and in noncoding regions, differed from that of the genomic region in which they occurred, with 93% of all mononucleotide SSRs proving to be of A or T. Computer-based analysis of the fine position of every SSR locus in the noncoding portion of the genome relative to downstream ORFs showed SSRs located in areas that could affect gene regulation. DNA sequences at 14 arbitrarily chosen SSR tracts were compared among E. coli strains. Polymorphisms of SSR copy number were observed at four of seven mononucleotide SSR tracts screened, with all polymorphisms occurring in noncoding regions. SSR polymorphism could prove important as a genome-wide source of variation, both for practical applications (including rapid detection, strain identification, and detection of loci affecting key phenotypes) and for evolutionary adaptation of microbes.[The sequence data described in this paper have been submitted to the GenBank data library under accession numbers AF209020–209030 and AF209508–209518.

Gur-Arie, Riva; Cohen, Cyril J.; Eitan, Yuval; Shelef, Leora; Hallerman, Eric M.; Kashi, Yechezkel

2000-01-01

273

Species Composition and Distribution of Adult Anopheles (Diptera: Culicidae) in Panama  

PubMed Central

Anopheles (Diptera: Culicidae) species composition and distribution were studied using human landing catch data over a 35-yr period in Panama. Mosquitoes were collected from 77 sites during 228 field trips carried out by members of the National Malaria Eradication Service. Fourteen Anopheles species were identified. The highest average human biting rates were recorded from Anopheles (Nyssorhynchus) albimanus (Wiedemann) (9.8 bites/person/night) and Anopheles (Anopheles) punctimacula (Dyar and Knab) (6.2 bites/person/night). These two species were also the most common, present in 99.1 and 74.9%, respectively, of the sites. Anopheles (Nyssorhynchus) aquasalis (Curry) was encountered mostly in the indigenous Kuna Yala Comarca along the eastern Atlantic coast, where malaria case history and average human biting rate (9.3 bites/person/night) suggest a local role in malaria transmission. An. albimanus, An. punctimacula, and Anopheles (Anopheles) vestitipennis (Dyar and Knab) were more abundant during the rainy season (May–December), whereas An. aquasalis was more abundant in the dry season (January–April). Other vector species collected in this study were Anopheles (Kerteszia) neivai (Howard, Dyar, and Knab) and Anopheles (Anopheles) pseudopunctipennis s.l. (Theobald). High diversity of Anopheles species and six confirmed malaria vectors in endemic areas of Panama emphasize the need for more detailed studies to better understand malaria transmission dynamics.

LOAIZA, J. R.; BERMINGHAM, E.; SCOTT, M. E.; ROVIRA, J. R.; CONN, J. E.

2010-01-01

274

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

PubMed Central

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

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

2011-01-01

275

Structure, Bonding, and Composition of Precambrian Carbonaceous Materials: Evidence of Early Life or Abiotic Processes?  

NASA Astrophysics Data System (ADS)

Robust detection of carbonaceous biosignatures is essential in the search for life elsewhere in the universe. However, the biogenicity of ancient kerogen-like residues on our own planet is suspect in some cases, such as microbe-like features within 3.5 Ga Apex cherts, potentially the oldest evidence of life on Earth, and stromatolite-like features within the slightly younger Strelley Pool Chert. We analyzed carbonaceous material in situ within these cherts using TEM, EELS, XANES, and SIMS. Samples were compared with Gunflint kerogen, graphite, amorphous carbon, and two abiotic Fischer-Tropsch-type (FTT) carbons. The two Archean samples are similar to Gunflint kerogen. Carbonaceous material is localized along quartz grain boundaries and at triple junctions, and when mechanically separated from chert particles it appears as long strings or crisscrossing networks. EELS spectra indicate a complex, kerogen-like substance distinct from both amorphous carbon and graphite, containing significant domains of polyaromatic carbon. The higher energy resolution of corresponding XANES spectra allows the resolution of a spectral peak consistent with carbonyl functional groups and a minor peak attributable to phenol groups. Minor concentrations of N, S, and P are detected with SIMS. These results strongly suggest that the ancient carbonaceous materials preserved within the Apex and Strelley Pool Cherts are indeed kerogen, and that the respective microbe-like and stromatolite- like features are also biogenic. FTT carbon is visually and spectrally distinct from ancient kerogen-like matter, but contains some similar characteristics. For example, EELS and XANES spectra of FTT material are similar except for much larger concentrations of carbonyl. We present one possible model for geologic processing of FTT products within an ancient hydrothermal vent. Hydrophobic FTT molecules may aggregate and precipitate on vent walls, protected by precipitated chert. During diagenesis, FTT material would lose volatile groups and condense to form polyaromatic domains, significantly reducing the intensity of the original carbonyl peak. Afterwards, the structure and bonding of this mature FTT material may be virtually identical to kerogen. This model depends on several assumptions: (1) the original FTT products are complex enough to withstand typical abiotic degradation processes during diagenesis; (2) N, S, and P can be easily incorporated into FTT products; (3) carbonyl groups on hydrocarbon chains can be efficiently transformed into hydroxyl groups on polyaromatic domains during condensation.

de Gregorio, B. T.; Sharp, T. G.; Flynn, G. J.

2006-12-01

276

Chronic social stress during adolescence in mice alters fat distribution in late life: prevention by antidepressant treatment.  

PubMed

Obesity and visceral fat accumulation are key features of the metabolic syndrome that represents one of the main health problems in western societies due to its neurovascular and cardiovascular complications. Epidemiological studies have identified chronic stress exposure as an important risk factor for the development of obesity and metabolic syndrome, but also psychiatric diseases, especially affective disorders. However, it is still unclear if chronic stress has merely transient or potentially lasting effects on body composition. Here, we investigated the effects of chronic social stress during the adolescent period on body fat composition in mice one year after the cessation of the stressor. We found that stress exposure during the adolescent period decreases subcutaneous fat content, without change in visceral fat, and consequently increases the visceral fat/subcutaneous fat ratio in adulthood. Further, we demonstrated that treatment with a selective serotonin reuptake inhibitor (paroxetine) during stress exposure prevented later effects on body fat distribution. These results from a recently validated chronic stress paradigm in mice provide evidence that stressful experiences during adolescence can alter body fat distribution in adulthood, thereby possibly contributing to an increased risk for metabolic diseases. Antidepressant treatment disrupted this effect underlining the link between the stress hormone system, metabolic homeostasis and affective disorders. PMID:18951248

Schmidt, M V; Czisch, M; Sterlemann, V; Reinel, C; Sämann, P; Müller, M B

2009-01-01

277

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.

2013-01-01

278

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

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

279

Stress distribution and strength prediction of composite laminates with multiple holes  

NASA Astrophysics Data System (ADS)

The major purpose of this study was to investigate failure of composite laminates with multiple unloaded holes in close proximity. The least square boundary collocation method for anisotropic materials was utilized to determine the state of stress. The approach utilized collocation on both the internal and external boundaries, making it relatively easy to implement. The method compared favorably to both published and finite element solutions. A failure prediction approach for an infinite, symmetric and balanced laminate, with two holes in close proximity was presented. The baseline material for consideration was IM7/977-3, a carbon fiber/epoxy lamina. The failure prediction method was an extension of the Whitney-Nuismer point stress failure criterion and was flexible enough to account for an arbitrary characteristic dimension value. Conditions for holes oriented transverse to the load and in-line with the load were considered. Both the "hole interaction effect" and "hole size effect" were simultaneously included in the failure prediction. Multiple hole spacings, hole size ratios, and layups were considered for stress distribution and strength prediction. For two equal holes oriented transverse to the load, the predicted strength was at least 95.0% of the single hole strength when the center to center distance divided by diameter, or l/D, was ? 3.5. For this same condition, the strength prediction response was nearly layup independent for l/D ? 3.0. The presented failure prediction approach was compared to published experimental data and was shown to have good correlation. A series of design curves were presented that allow for the quick determination of a structure's strength with two holes by only requiring the characteristic dimension for a single hole. Two approaches to approximately determine the orthotropic stress concentration factor by using only two parameters were presented. Ten composite materials were investigated to determine the accuracy of the approximation for a variety of material systems. The results showed that a good approximation to the orthotropic stress concentration factor can be obtained by using only the parameters Ex/Ey and Ex/Gxy, regardless of the material system.

Esp, Brian

280

Dietary composition during fetal and neonatal life affects neuropeptide Y functioning in adult offspring.  

PubMed

The aim of this study was to examine the impact of maternal diet during the gestation and lactation periods on the neuropeptide Y (NPY) system in adult offspring. Male Long-Evans rats were obtained from dams fed either on a well-balanced diet (C), a high carbohydrate diet (HC) or a high-fat diet (HF) and fed themselves on the well-balanced diet for their whole life. At 6 months of age, their feeding response to various doses of NPY injected in the lateral brain ventricle was measured in one group and NPY concentrations in microdissected nuclei of the hypothalamic were measured in a second group. The HF rats were lighter than the two other groups (P<0.001). The control rats showed a typical dose-dependent feeding response to NPY. The HC rats showed a continuous increase in the response, starting at the intermediate dose (1.0 microg) only while the HF rats had a maximal response at the lowest dose (0.5 microg). The HF rats ate twice as much as the HC rats at the lowest dose tested 1 h after injection (4.4+/-0.6 vs. 2.7+/-0.4 g; P<0.05), showing therefore the greatest sensitivity to NPY. This change in the sensitivity was not related to hypothalamic NPY concentration as it was not modified in the arcuate and paraventricular nuclei. The diet imposed on the mother could have long-lasting effects on body weight regulation of the offsprings and alter the NPY system likely through modifications at the receptor level. PMID:11154763

Kozak, R; Burlet, A; Burlet, C; Beck, B

2000-12-29

281

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

282

Effect of the particle size distribution of spinel on the mechanical properties and thermal shock performance of MgO–spinel composites  

Microsoft Academic Search

The influence of varying the amounts of spinel with a similar median particle size, but with different distribution, on the mechanical properties and thermal shock performance of MgO–spinel composites was investigated. Mechanical properties of composites decreased significantly with increasing spinel content due to the thermal expansion mismatch. However, ?WOF values of composites increased markedly, because of a significant change in

Cemail Aksel; Frank L. Riley

2003-01-01

283

Educational attainment and late life telomere length in the Health, Aging and Body Composition Study.  

PubMed

Morbidity and mortality are greater among socially disadvantaged racial/ethnic groups and those of lower socioeconomic status (SES). Greater chronic stress exposure in disadvantaged groups may contribute to this by accelerating cellular aging, indexed by shorter age-adjusted telomere length. While studies consistently relate shorter leukocyte telomere length (LTL) to stress, the few studies, mostly from the UK, examining associations of LTL with SES have been mixed. The current study examined associations between educational attainment and LTL among 2599 high-functioning black and white adults age 70-79 from the Health, Aging and Body Composition Study. Multiple regression analyses tested associations of race/ethnicity, educational attainment and income with LTL, adjusting for potential confounders. Those with only a high school education had significantly shorter mean LTL (4806 basepairs) than those with post-high school education (4926 basepairs; B=125, SE=47.6, p=.009). A significant interaction of race and education (B=207.8, SE=98.7, p=.035) revealed more beneficial effects of post-high school education for blacks than for whites. Smokers had shorter LTL than non-smokers, but the association of education and LTL remained significant when smoking was covaried (B=119.7, SE=47.6, p=.012). While higher income was associated with longer LTL, the effect was not significant (p>.10). This study provides the first demonstration of an association between educational attainment and LTL in a US population where higher education appears to have a protective effect against telomere shortening, particularly in blacks. PMID:22981835

Adler, Nancy; Pantell, Matthew S; O'Donovan, Aoife; Blackburn, Elizabeth; Cawthon, Richard; Koster, Annemarie; Opresko, Patricia; Newman, Anne; Harris, Tamara B; Epel, Elissa

2012-09-05

284

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

285

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

286

Chemical Composition and Size Distributions of Coastal Aerosols Observed on the U.S. East Coast  

NASA Astrophysics Data System (ADS)

Aerosol input is an important source of certain limiting nutrients, such as iron, for phytoplankton growth in several large oceanic regions. As the efficiency of biological uptake of nutrients may depend on the aerosol properties, a better knowledge of aerosol properties is critically important. Characterizing aerosols over the coastal ocean needs special attention, because the properties of aerosols could be altered by many anthropogenic processes in this land-ocean transition zone before they are transported over the remote ocean. The goal of this experiment was to examine aerosol properties, in particular chemical composition, particle-size distributions and iron solubility, over the US Eastern Seaboard, an important boundary for the transport of continental substances from North America to the North Atlantic Ocean. Our field sampling site was located at Tuckerton (39°N, 74°W) on the southern New Jersey coast. Fourteen sets of High-Volume aerosol samples and three sets of size segregated aerosol samples by a 10-stage MOUDI impactor were collected during 2007 and 2008. The ICP-MS methodology was used to analyze aerosol samples for the concentrations of thirteen trace elements: Al, Fe, Mn, Sc, Cd, Pb, Sb, Ni, Co, Cr, Cu, Zn and V. The IC procedures were applied to determine five cations (sodium, ammonium, potassium, magnesium and calcium) and eleven anions (fluoride, acetate, propionate, formate, MSA, chloride, nitrate, succinate, malonate, sulfate and oxalate). The UV spectrometry was employed for the determination of iron solubility. Preliminary results suggest three major sources of aerosols: anthropogenic, crustal and marine. At this location, the concentrations of iron (II) ranged from 2.8 to 29ng m-3, accounting for ~20% of the total iron. The iron concentrations at this coastal site were substantially lower than those observed in Newark, an urban site in northern NJ. High concentrations of iron (II) were associated with both fine and coarse aerosol particles, suggesting the impacts of different sources on the particle-size distributions of atmospheric iron. More results will be discussed during the presentation at the meeting.

Xia, L.; Song, F.; Jusino-Atresino, R.; Thuman, C.; Gao, Y.

2008-12-01

287

Lithium Isotopic Composition of Mantle Plumes and the Distribution of Lithium Isotopes Among Earth's Reservoirs  

NASA Astrophysics Data System (ADS)

We have determined lithium isotopic compositions of seventy nearly unaltered basaltic lavas from the Samoan and Cook-Austral volcanic chains, and Pitcairn Island. In addition, the Li isotope record of Mauna Kea has been extended from 3.1 km to 3.3 km using the newly recovered deep drill core of Hawaii Scientific Drilling Project (HSDP-2). From the results of the Hawaii and South Pacific hotspots, we examine the source components of mantle plumes and consider the distribution of Li isotopes among Earth's major reservoirs. The total ?^{7}Li range observed in South Pacific and Hawaiian islands is 2.5 to 7.5‰, suggesting considerable heterogeneity in the deep mantle. The Hawaiian plume occupies the lower range, 2.5 to 5.7‰. Cook-Austral samples depict mixing between HIMU and depleted mantle (DM) components. The DM endmember has ?^{7}Li values of 3.2 to 4.2‰, identical to MORB. HIMU type lavas are isotopically heavier than MORB, reflecting the influence of recycled oceanic crust. The most extreme HIMU signature was observed at Mangaia (7.4‰; Nishio et al., 2005). The EM1 composition shown by Pitcairn is relatively light (3.3 to 4.1‰) and resembles the global average of subducting sediments (~3‰). Malumalu seamount of the Samoan chain defines the most extreme composition of the EM2 mantle; ?^{7}Li range from 4.5 to 5.6‰. High 3He/4He samples of Ofu Island (R/Ra = 24 to 33.7) suggest that the least degassed mantle has ?^{7}Li of about 3‰. In addition to these classic mantle endmembers, we observe an additional component that elevates Samoan lavas above the typical mantle baseline (~3‰) up to 7.5‰. The source of this enrichment is likely mantle wedge material that has been metasomatized by 7Li-rich slab fluids (Elliott et al., 2004). On the other hand, recent studies suggest that a large portion of subducted Li can be retained in high-pressure metamorphosed slab (Marschall et al., in press). This implies that deeply subducted slab need not be isotopically light but can be the origin of elevated ?^{7}Li of HIMU lavas. The global ocean island basalts yield an average ?^{7}Li value of 4.7 ± 0.9‰ (1?). Thus the deep mantle is isotopically heavier than the upper mantle (3 to 4‰), volcanic arcs (3.5 ± 1.5‰), and the upper continental crust (0 ± 2‰). The implication is that heavy Li that enters the subduction zone is not significantly recycled to the crust but largely returned to the deep mantle via the slab-modified mantle wedge and possibly the residual slab. Unusually light Li does not appear to to be common in the deep mantle although it has been implicated by orogenic eclogites and subcontinental mantle xenoliths. References: Elliott T., A. Jeffcoate, and C. Bouman (2004) Earth Planet. Sci. Lett. 220, 231-245. Marschall H.R., R. Altherr, T. Ludwig et al. (in press) Geochim. Cosmochim. Acta. Nishio N., S. Nakai, T. Kogiso, and H.G. Barsczus (2005)Geochem. J. 39, 91-103.

Chan, L.; Hart, S. R.; Blusztajn, J. S.; Lassiter, J. C.; Frey, F. A.; Hauri, E. H.

2006-12-01

288

Screening of urban aerosol particulate composites for selected metal distribution and their dependence on meteorological parameters.  

PubMed

Local atmospheric aerosol particulate samples, collected as composites on daily 6-12 hour basis, at Quaid-i-Azam University campus, Islamabad, Pakistan, using high volume sampling technique, were analysed for Pb, Na, K, Fe, Mn, Cd, Cr, Ni, Zn and Co by FAAS method. The monitoring period ran from October, 2001 through March, 2002, with a total of 105 samples collected on cellulose filters, treated in part with the HNO3-based wet digestion method for metal quantification, and for particle size distribution separately. The metal content of the aerosols was examined in relation to dependence on meteorological parameters, such as temperature, relative humidity, wind speed, sun shine and pan evaporation. Statistical correlation analysis was conducted for multiple metal pairs in aerosols, and the data were examined in relation to meteorological parameters and relevant aerosol particle size fractions. The study revealed no viable strong correlation between the meteorological parameters and metal levels; in general, however, a significant positive correlation was found for temperature. A strong positive correlation was observed for PM<25 and PM2.5-10. For coarse particles (PM10-100 and PM>100), however, a negative correlation was observed. The levels of Na, K, Fe and Zn were found in the range of 1-5 microg/m3 while those for the rest of the metals in the sub microg/m3 range. Principal component analysis and cluster analysis were performed on dataset for source identification and appointment. Largest contribution (33%) was shown by the industrial emissions followed by traffic/road dust (16.7%). PMID:15626241

Shah, Munir H; Shaheen, Nazia; Jaffar, M

2004-11-01

289

A note on Brock: prioritarianism, egalitarianism and the distribution of life years.  

PubMed

The moral philosopher Dan Brock has argued that equality of health outcomes "even if achievable" is problematic as a goal in its own right-because it is open to the levelling down objection. The levelling down objection to egalitarianism has received surprisingly little attention in the bioethics literature on distribution of health and healthcare and deserves more attention. This paper discusses and accepts an example given by Brock showing that prioritarianism and egalitarianism may judge distributions of health outcomes differently. We should accept that levelling down is never a good thing, all things considered, but that equality often is. By discussing variants of Brock's example, it is demonstrated that if equality, prioritarianism and aggregation are combined, as in a population-wide summary measure of health, such as the health achievement index, this combined set of principles is not open to levelling down. The paper suggests-although a more thorough investigation of the properties of the achievement index is needed-that this measure (a) is always sensitive to inequality in health, (b) is always sensitive to average health, (c) can assign priority to those with lowest health outcomes and (d) is not sensitive to levelling down. Levelling down is not an embarrassment for egalitarians if they adopt a pluralist theory that integrates fairness with goodness. Equality is not the only value egalitarians promote. But equality is so important that we should not reject it. PMID:19717696

Norheim, O F

2009-09-01

290

A Life Cycle Assessment on a Fuel Production Through Distributed Biomass Gasification Process  

NASA Astrophysics Data System (ADS)

In this paper, we estimated life cycle inventories (energy intensities and CO2 emissions) on the biomass gasification CGS, Bio-H2, Bio-MeOH (methanol) and Bio-DME (di-methyl ether), using the bottom-up methodology. CO2 emissions and energy intensities on material's chipping, transportation and dryer operation were estimated. Also, the uncertainties on the moisture content of biomass materials and the transportation distance to the plant were considered by the Monte Carlo simulation. The energy conversion system was built up by gasification through the BLUE Tower process, with either CGS, PSA (Pressure Swing Absorption) system or the liquefaction process. In our estimation, the biomass materials were the waste products from Japanese Cedar. The uncertainties of moisture content and transportation distance were assumed to be 20 to 50 wt.% and 5 to 50 km, respectively. The capability of the biomass gasification plant was 10 t-dry/d, that is, an annual throughput of 3,000 t-dry/yr. The production energy in each case was used as a functional unit. Finally, the energy intensities of 1.12 to 3.09 MJ/MJ and CO2 emissions of 4.79 to 88.0 g-CO2/MJ were obtained. CGS case contributes to the environmental mitigation, and Bio-H2 and/or Bio-DME cases have a potential to reduce CO2 emissions, compared to the conventional ones.

Dowaki, Kiyoshi; Eguchi, Tsutomu; Ohkubo, Rui; Genchi, Yutaka

291

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

2013-03-15

292

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

PubMed

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

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

2013-07-01

293

Subcellular distribution and life cycle of Epstein-Barr virus in keratinocytes of oral hairy leukoplakia.  

PubMed

The authors investigated the life cycle of Epstein-Barr virus (EBV) in keratinocytes of oral hairy leukoplakia by combining immunohistochemistry. DNA in situ hybridization, and lectin histochemistry with electron microscopy. Diffuse-staining components of the EBV early antigen complex (EA-D), EBV 150-kd capsid antigen (VCA), EBV membrane antigen (gp350/220), and double-stranded DNA were labeled with monoclonal antibodies. An EBV-DNA probe was used to locate EBV DNA. Wheat-germ agglutinin (WGA) was employed to distinguish Golgi-associated compartments. The authors found EBV proteins and EBV DNA only in keratinocytes with apparent viral assembly. In situ hybridization showed EBV DNA in free corelike material and in electron-dense cores of mature nucleocapsids. Monoclonal antibodies to nonspecific double-stranded DNA attached to the same structures and to marginated chromatin. Components of EA-D were dispersed throughout the nuclei but accumulated near condensed chromatin and in 'punched-out' regions of the chromatin. Epstein-Barr virus 150-kd capsid antigen was found only in the nuclei, where it appeared preferentially on mature nucleocapsids. As yet unexplained arrays of intranuclear particles that remained unlabeled with all EBV-specific probes reacted intensely with an antiserum against common papillomavirus antigen. Gp350/220 was detectable in various cellular membrane compartments and was highly concentrated on EBV envelopes in peripheral Golgi-associated secretory vesicles. It was less abundant on the extracellular EBV, indicating that viral membrane antigen partly dissociates from the mature virus. Combined lectin-binding histochemistry and electron microscopy demonstrated for the first time that EBV is processed in the Golgi apparatus, which eventually releases the virus by fusion with the plasma membrane. These results provide insight into the biologic events that occur during complete EBV replication in vivo. PMID:1649554

Rabanus, J P; Greenspan, D; Petersen, V; Leser, U; Wolf, H; Greenspan, J S

1991-07-01

294

On the Distribution of Delamination in Composite Structures and Compressive Strength Prediction for Laminates with Embedded Delaminations  

NASA Astrophysics Data System (ADS)

In this study, large numbers of aircraft composite structures were inspected, and the distribution of delamination sizes and though thickness positions in the composite laminates are investigated. An experiment is conducted to probe into the influence of delamination sizes and through thickness positions on the compressive strengths of laminates with single embedded circular delamination, with the most dangerous delamination sizes and positions defined from the distribution. Furthermore, a shell model is established for compressive strength prediction, with delamination propagation assessed using a mixed mode criterion. The finite element (FE) prediction comes out to be in good agreement with the experimental measurements, for the predicted compressive strengths stand within 10% error of experimental results. It was observed that the compressive strength was highly influenced by the delamination size, while the through thickness position of delamination did not have significant effect on the compressive strength.

Huimin, Fu; Yongbo, Zhang

2011-06-01

295

Size distribution and chemical composition of secondary organic aerosol formed from C1-initiated oxidation of toluene.  

PubMed

Secondary organic aerosol (SOA) formed from C1-initiated oxidation of toluene was investigated in a home-made smog chamber. The size distribution and chemical composition of SOA particles were measured using aerodynamic particle sizer spectrometer and the aerosol laser time-of-flight mass spectrometer (ALTOFMS), respectively. According to a large number of single aerosol diameter and mass spectra, the size distribution and chemical composition of SOA were obtained statistically. Experimental results showed that SOA particles created by C1-initiated oxidation of toluene is predominantly in the form of fine particles, which have diameters less than 2.5 microm (i.e., PM2.5), and glyoxal, benzaldehyde, benzyl alcohol, benzoquinone, benzoic acid, benzyl hydroperoxide and benzyl methyl nitrate are the major products components in the SOA. The possible reaction mechanisms leading to these products are also proposed. PMID:22893963

Huang, Mingqiang; Zhang, Weijun; Gu, Xuejun; Hu, Changjin; Zhao, Weixiong; Wang, Zhenya; Fang, Li

2012-01-01

296

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

297

Thermoelectric figure of merit for bulk nanostructured composites with distributed parameters  

SciTech Connect

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

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

2012-05-15

298

Distributed Brillouin fiber optic strain monitoring applications in advanced composite materials  

Microsoft Academic Search

Composite materials based on glass, carbon and aramid fibers have many advantages such as fast application, lightweight and corrosion resistance, and are widely diffused for manufacturing of tanks, pipings and for restoration, upgrade and seismic retrofit of structures and historical heritage. As several questions regarding long term durability of composite strengthenings remains still unsolved, monitoring of strain and temperature is

Filippo Bastianini; Mario Cargnelutti; Angelo Di Tommaso; Massimo Toffanin

2003-01-01

299

Changes in body composition and fat distribution after short-term weight gain in patients with anorexia nervosa13  

Microsoft Academic Search

The most commonly described psychologic ab- normality associated with anorexia nervosa is a distorted percep- tion of body weight and shape. This perception may contribute to the anorexic patient's resistance to gaining weight even when it is a medical necessity. The purpose of this study was to assess body-composition and fat-distribution changes after short-term weight gain in 26 female anorexia

Charitini I Orphanidou; Linda J McCargar; C Laird Birmingham; Allen S Belzberg

300

Composition and Ecological Distribution of Cry Proteins and Their Genotypes of Bacillus thuringiensis Isolates from Warehouses in China  

Microsoft Academic Search

The composition and distribution of insecticidal crystal proteins (Cry proteins) and their genotypes of Bacillus thuringiensis isolates from warehouses were evaluated through SDS–PAGE and PCR techniques. The results showed that the electrophoretic patterns of ?-endotoxin crystal preparations were divided into five types. The isolates containing ?135 kDa with a 65-kDa protein or only a ?135-kDa protein, which amounted to 55.74

Zhang Hongyu; Yu Ziniu; Deng Wangxi

2000-01-01

301

Characterization of melting properties in dark chocolates from varying particle size distribution and composition using differential scanning calorimetry  

Microsoft Academic Search

Melting properties in dark chocolates processed from varying particle size distribution (PSD), fat and lecithin content were studied using differential scanning calorimetry (DSC). Compositional parameters were PSD (D90 (90% finer than this size) of 18, 25, 35 and 50?m), fat (25%, 30% and 35%) and lecithin (0.3% and 0.5%) contents. Variations in PSD had no influence on crystallinity of products.

Emmanuel Ohene Afoakwa; Alistair Paterson; Mark Fowler; Joselio Vieira

2008-01-01

302

Analysis of the distribution of the isotopic composition of evapotranspiration flux in a semi-arid savanna.  

NASA Astrophysics Data System (ADS)

The cycling of water in semi-arid regions is critical for the ecohydrologic processes of savanna systems. Stable isotopes of water serve as important tracers of water movement, and studies of how the isotopic distribution of rainfall is transformed through geomorphic basin characteristics into an isotopic distribution of runoff have yielded insight into watershed dynamics. However, in many drylands, the majority of return flux of water out of ecosystems is in the form of evapotranspiration. Through a combination of field measurements and modeling, we present a study of the factors that influence the transformation of the isotopic distribution of precipitation into an isotopic distribution of evapotranspiration. Field observations were collected at a micrometerological tower located in a mixed-savanna in Laikipa, Kenya. The tower is equipped with an off-axis integrated cavity output spectroscopy system (ICOS), and the isotopic composition of atmospheric water vapor has been sampled at 1 Hz from 2010 through 2012. Evapotranspiration isotopic composition is estimated based on Keeling plots for each 30 minute time period, with seasonal dynamics evident throughout this multi-year study. Isotopic analysis of collected rainfall and cryogenic vacuum distillation of soil and plant samples at the site aid in the interpretation of water cycling. A decrease in the variance of evapotranspiration flux composition relative to precipitation is indicative of soil water mixing as well as runoff and recharge effects. Stochastic modeling of the isotopic inputs and outputs of the semi-arid systems demonstrates the strength of the influence that rainfall climatology, plant rooting depth, and evapotranspiration characteristics have on the ratio of the variances of input and output isotopic composition.

Good, Stephen; O'Connor, Molly; Soderberg, Keir; Wang, Lixin; Caylor, Kelly

2013-04-01

303

Evaluation of the Body Composition and Fat Distribution in Long-Term Users of Hormone Replacement Therapy  

Microsoft Academic Search

The aim of the study was to evaluate the body composition and fat distribution in long-term users of hormonal replacement therapy (HRT). 18 healthy menopausal women, long-term users of HRT (transdermal estradiol 50 ?g continuously administered and 10 mg\\/day of medroxyprogesterone acetate for 12 days\\/month) and 18 healthy menopausal women, who had never used HRT were included in the study.

G. Perrone; Y. Liu; O. Capri; C. Critelli; F. Barillaro; P. Galoppi; L. Zichella

1999-01-01

304

The Influence of Body Composition, Fat Distribution, and Sustained Weight Loss on Left Ventricular Mass and Geometry in Obesity  

Microsoft Academic Search

Alterations in left ventricular mass and geometry vary along with the degree of obesity, but mechanisms underlying such covariation are not clear. In a case–control study, we examined how body composition and fat distribution relate to left ventricular structure and examine how sustained weight loss affects left ventricular mass and geometry. At the 10-year follow-up of the Swedish obese subjects

Dimitris Kardassis; Odd Bech-Hanssen; Marie Schönander; Lars Sjöström; Kristjan Karason

2012-01-01

305

The effect of stitch distribution on Mode I delamination toughness of stitched laminated composites – experimental results and FEA simulation  

Microsoft Academic Search

In this paper, a tabbed double cantilevered beam test is performed on Vectran® stitched laminated composites with varying stitch distributions. The woven carbon fibre plies were laid-up in a symmetrical manner [0,±45,90]2, then stitched in dry preform state followed by a resin film infusion stage. To prevent the stitched specimens from failing in flexure, thick aluminium reinforcing tabs were adhesively

Michael D. K. Wood; Xiannian Sun; Liyong Tong; Anthony Katzos; Adrian R. Rispler; Yiu-Wing Mai

2007-01-01

306

Possibility of recent changes in vertical distribution and size composition of chlorophyll-a in the western North Pacific region  

Microsoft Academic Search

Our analysis of the last three decades of retrospective data of vertical distributions and size composition of chlorophyll-a\\u000a (Chl-a) over the western North Pacific has revealed significant changes of three indices related to Chl-a during summer season,\\u000a as follows: (1) decreasing linear trend of the proportion of Chl-a in surface layer to that of the whole water column by 0.4

Hiroshi Ishida; Yutaka W. Watanabe; Joji Ishizaka; Toshiya Nakano; Naoki Nagai; Yuji Watanabe; Akifumi Shimamoto; Nobuhiro Maeda; Michimasa Magi

2009-01-01

307

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

SciTech Connect

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

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

2006-03-15

308

Effects of different types of exercise on body composition and fat distribution in HIV-infected patients: a brief review.  

PubMed

HIV infection and its treatment is associated with unfavourable metabolic and morphological abnormalities. These metabolic abnormalities, particularly alterations in body composition and fat distribution, may increase the risk for cardiovascular and metabolic complications, as well as reduce functional independence and lower self-esteem. Thus there is an urgent need to develop interventions intended to manage secondary side effects of HIV or antiretroviral therapy-related complications. In poly-treated patients, nonpharmacological interventions are a logical first step. Exercise training in particular may help alleviate some of the metabolic adverse effects associated with antiretroviral therapy by favourably altering body composition and patterns of body fat distribution. Studies have shown that exercise training, particularly aerobic training, can help reduce total body and visceral fat, as well as normalizing lipid profiles in HIV-infected patients. The results for resistance training, however, are less conclusive. Knowledge of the use of resistance and aerobic training and its attendant effects on insulin resistance and adipocytokines may represent an effective nonpharmacologic means for treating metabolic complications of HIV-infected persons who are receiving appropriate antiretroviral therapy. In this brief review we examine the effects of aerobic and resistance training on body composition, body fat distribution, and selected metabolic outcomes. PMID:15981790

Malita, Florin M; Karelis, Antony D; Toma, Emil; Rabasa-Lhoret, Remi

2005-04-01

309

Analysis of knitted fabric reinforced composites: Part I. Fibre orientation distribution  

Microsoft Academic Search

The fibre orientation distributions in different types of warp knitted fabric are studied. The fibre orientations are represented by orientation tensors. This allows for the production of second- and fourth-order approximations of the orientation distribution function, which contain the relevant part of the orientation distribution for second- and fourth-order tensorial properties, respectively. Also, the symmetry that is present in the

B. Gommers; I. Verpoest; P. Van Houtte

1998-01-01

310

Turning the Analysis of Obesity-Mortality Associations Upside Down: Modeling Years of Life Lost Through Conditional Distributions  

PubMed Central

The analysis of longevity as a function of risk factors such as body mass index (BMI; kg/m2), activity levels, and dietary factors is a mainstay of obesity research. Modeling survival through hazard functions, relative risks, or odds of dying with methods such as Cox proportional hazards or logistic regression are the most common approaches and have many advantages. However, they also have disadvantages in terms of the ease of interpretability, especially for non-statisticians; the need for additional data to convert parameter estimates to estimates of years of life lost (YLL); and debates about the appropriate time scale in the model. Parametric survival models are able to provide more direct answers, and in our analysis of an obesity-related data set, gave consistent YLL estimates regardless of the distribution used. Additionally, we offer alternative approaches to the analyses of censored survival data including a modified or ‘compressed’ Gaussian distribution. We therefore recommend increased consideration of parametric survival models in chronic disease and risk factor epidemiology.

Robertson, Henry T.; de los Campos, Gustavo; Allison, David B.

2012-01-01

311

Vertical distribution, population structure and life cycle of Neocalanus cristatus (Crustacea: Copepoda) in the Oyashio region, with notes on its regional variations  

Microsoft Academic Search

Vertical distribution and population structure of Neocalanus cristatus were investigated at Site H in the Oyashio region from September 1996 through October 1997 to evaluate their life cycle mode.\\u000a Additional temporary samplings were also made at several stations covering the entire subarctic Pacific, Okhotsk Sea and Japan\\u000a Sea, as a basis for regional comparison of life cycles of this species.

T. Kobari; T. Ikeda

1999-01-01

312

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.

313

Distribution of Fishes in Seagrass Meadows: Role of Macrophyte Biomass and Species Composition.  

National Technical Information Service (NTIS)

Large spatial variation was found in the abundance and species composition of ichthyofauna in seagrass meadows of Apalachee Bay and Indian River lagoon, Florida. Abundance of fishes was a direct function of aboveground seagrass biomass in Apalachee Bay wh...

A. W. Stoner

1983-01-01

314

The Effect of Oxidizer Particle Size Distribution on the Steady and Nonsteady Combustion of Composite Propellants.  

National Technical Information Service (NTIS)

A theoretical analysis of the combustion of composite propellants (with an emphasis on the heterogeneous effects) is presented. The analysis based on the combination of a unique statistical treatment of the burning surface with a very comprehensive multip...

J. A. Condon J. R. Osborn

1978-01-01

315

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

316

Lipid composition and partitioning of deepwater chondrichthyans: inferences of feeding ecology and distribution  

Microsoft Academic Search

The composition of lipids and fatty acids was determined for the livers, muscle, pancreas, kidney and stomach fluids of deepwater\\u000a chondrichthyan species (including 11 squaliformes, 3 chimaeriformes, 1 hexanchiforme and 3 carcharhiniformes) caught as bycatch\\u000a from continental waters off south-eastern Australia. The lipid class, fatty acid and fatty alcohol composition differed markedly\\u000a in each tissue and in each species. The

Heidi Pethybridge; Ross Daley; Patti Virtue; Peter Nichols

2010-01-01

317

Contrasted glass-whole rock compositions and phenocryst re-distribution, IPOD Sites 417 and 418  

Microsoft Academic Search

Major element composition ranges of closely associated basalt glass-whole rock pairs from individual small cooling units approach the total known range of basalt glass and whole rock compositions at IPOD sites 417 and 418. The whole rock samples fall into two groups: one is depleted in MgO and distinctly enriched in plagioclase but has lost some olivine and\\/or pyroxene relative

H. Staudigel; W. B. Bryan

1982-01-01

318

A re-interpretation of Volcano Ranch lateral distribution measurements to infer the mass composition of cosmic rays  

NASA Astrophysics Data System (ADS)

In the course of its operation, the Volcano Ranch array collected data on the lateral distribution of showers produced by cosmic rays at energies above 1017 eV. From these data very precise measurements of the steepness of the lateral distribution function, characterized by the ? parameter, were made. The current availability of sophisticated hadronic interaction models has prompted a reinterpretation of the measurements. We use the interaction models QGSJET and SIBYLL in the AIRES Monte Carlo code to generate showers together with GEANT4 to simulate the response of the detectors to ground particles. As part of an effort to estimate the primary mass composition of cosmic rays at this energy range, we present the results of our preliminary analysis of the distribution of ?.

Dova, M. T.; Mancen~Ido, M. E.; Mariazzi, A. G.; McCauley, T. P.; Watson, A. A.

2003-07-01

319

Composition and distribution of the main active components in selenium-enriched fruit bodies of Cordyceps militaris link.  

PubMed

Selenium-enriched Cordyceps militaris fruit bodies are industrially cultivated as functional food or medicinal food in China and southeast Asia. However, composition of selenium compounds and distribution of the main bioactive components are still unknown. In the selenium-enriched fruit bodies, the main soluble selenium compounds of low molecular weight were identified as SeMet (selenomethionine), and the main selenium compounds bound in proteins were identified as SeMet and SeCys (methylselenocysteine). Trace minerals as Se (selenium), Zn (zinc), Fe (iron) and the main active components as adenosine, cordycepin and carotenoids were mostly distributed in the terminal of fruit bodies, while P (phosphorus) and K (potassium) were evenly distributed in the fruit bodies. The results indicated that terminal of the fruit bodies should be the better materials for production of advanced functional food. So cultivation of relatively short and thick fruit bodies with bigger terminals deserves further research. PMID:23200005

Dong, Jing Z; Ding, J; Yu, Pei Z; Lei, Can; Zheng, Xiao J; Wang, Y

2012-11-02

320

Interfacial reactions in titanium-matrix composites  

SciTech Connect

A study of the interfacial reaction characteristics of SiC fiber-reinforced titanium aluminide and disordered titanium alloy composites has determined that the matrix alloy compositions affect the microstructure and the distribution of the reaction products, as well as the growth kinetics of the reaction zones. The interfacial reaction products in the ordered titanium aluminide composite are more complicated than those in the disordered titanium-alloy composite. The activation energy of the interfacial reaction in the ordered titanium aluminide composite is also higher than that in the disordered titanium alloy composite. Designing an optimum interface is necessary to enhance the reliability and service life at elevated temperatures. 16 refs.

Yang, J.M.; Jeng, S.M. (California Univ., Los Angeles (USA))

1989-11-01

321

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

SciTech Connect

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

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

2010-03-01

322

Active Distributed Mixers Based on Composite Right\\/Left-Handed Transmission Lines  

Microsoft Academic Search

Distributed mixers are based on the active coupling of two artificial transmission lines (TLs) and provide ultra-wideband performance. This paper shows that it is possible to design distributed mixers with novel performances if artificial TLs with dispersion diagrams different from those provided by conventional series-inductor\\/shunt-capacitor TLs are used. In particular, three novel distributed mixers, presenting dual-band\\/diplexer behavior, with and without

Javier Mata-Contreras; Carlos Camacho-Penalosa; Teresa M. Martin-Guerrero

2009-01-01

323

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

324

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

PubMed

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

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

2012-05-01

325

Controls on the molecular distribution and carbon isotopic composition of alkenones in certain haptophyte algae  

NASA Astrophysics Data System (ADS)

Although the biochemical functions and biosynthetic pathways of alkenones are still largely unknown, alkenone unsaturation ratios are now used extensively to infer ancient sea surface temperature, and their isotopic compositions have been used to reconstruct ancient atmospheric CO2 levels. The inferred relationships between alkenone unsaturation ratios, isotopic compositions, and growth conditions are based on empirical laboratory and field studies and, in the case of isotope fractionation, on simple models of carbon acquisition and fixation. Significant uncertainty still exists concerning the physiological and ecological factors affecting cellular production of alkenones, unsaturation ratios, and isotopic composition. Phytoplankton culture conditions have been shown to affect alkenone unsaturation (U37K'), cellular alkenone content, intracellular isotopic compositions (??), and changes in fractionation (?P) as a function of the quotient of algal growth rate and aqueous carbon dioxide concentration (?/CO2). Such studies imply that plant physiology can affect the interpretation of environmental signals. The factor(s) controlling cellular alkenone concentrations and unsaturation ratios are reviewed, as well as the carbon isotopic composition of the alkenone-producing algae. A new technique is presented to determine growth rates of the alkenone-containing algae in natural settings that will facilitate testing laboratory-based hypotheses concerning the carbon isotopic fractionation and its relationship to growth rate/growth status of alkenone-producing algae in the field.

Laws, Edward A.; Popp, Brian N.; Bidigare, Robert R.; Riebesell, Ulf; Burkhardt, Steffen; Wakeham, Stuart G.

2001-01-01

326

Fuzzy load flow in balanced and unbalanced radial distribution systems incorporating composite load model  

Microsoft Academic Search

This paper presents a fuzzy approach load flow for balanced and unbalanced radial distribution systems with incorporating load model. Fuzzy set theory proposes an appropriate way to model inexactly expressed information and data which have uncertainty. In this paper the combination of fuzzy models and techniques for electrical distribution systems is presented. The theories relating to the fuzzy numbers are

Belal Mohammadi Kalesar; Ali Reza Seifi

2010-01-01

327

Distribution and Stable Isotopic Composition of Amino Acids from Fungal Peptaibiotics: Assessing the Potential for Meteoritic Contamination  

NASA Astrophysics Data System (ADS)

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 C4 and C5 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.

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

2011-03-01

328

Aerosol Size Distribution, Composition, and Hygroscopicity Measurements During CSTRIPE Using an Aerosol Mass Spectrometer and a Dual Differential Mobility Analyzer  

NASA Astrophysics Data System (ADS)

During July 2003, the CIRPAS Twin Otter aircraft was deployed in the CSTRIPE (Coastal STRatocumulus Imposed Perturbation Experiment) field experiment in order to quantify the effects of aerosols on the microphysics and dynamics of marine stratocumulus clouds. In order to characterize the effects of different aerosol types on stratocumulus clouds, various air masses were sampled, including local fire plumes, pollution over the San Joaquin valley, unperturbed marine stratocumulus clouds, and stratocumulus clouds perturbed by seeding flares. Some research flights were also dedicated to characterize the seeding flares in the clear sky. Measurements of aerosol mass distribution and composition, using an Aerodyne Aerosol Mass Spectrometer (AMS), and size distribution and hygroscopic behavior, using a Dual Differential Mobility Analyzer (Dual DMA) with one column at dry conditions and another at a relative humidity of approximately 70 percent, will be presented here. During a number of in-cloud sampling periods, the Counter-flow Virtual Impactor (CVI) was used to select and dry cloud droplets, which were then analyzed by the AMS and the Dual DMA. The AMS composition measurements showed that sulfate and organics comprised most of the mass of the non-refractory components of the aerosol. The DMA showed a mixture of unimodal and bimodal size distributions in most types of air masses. The air mass over the San Joaquin valley, however, showed strong evidence of freshly nucleated particles, with aerosol number concentrations often above 80,000 cm-3.

Bahreini, R.; Varutbangkul, V.; Conant, W. C.; Flagan, R. C.; Seinfeld, J. H.; Buzorius, G.; Jonsson, H. H.

2003-12-01

329

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

SciTech Connect

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, P.A.

1991-08-01

330

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

331

Monte Carlo Simulation of Thermal Conductivity in Randomly Distributed Nanowire Composites  

Microsoft Academic Search

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

W. Tian; R. Yang

2007-01-01

332

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

Microsoft Academic Search

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

William J. Woelkerling; Stephen B. Gough

1976-01-01

333

The influence of silicate melt composition on distribution of siderophile elements among metal and silicate liquids  

NASA Astrophysics Data System (ADS)

Liquid metal-liquid silicate partitioning of Fe, Ni, Co, P, Ge, W and Mo among a carbon-saturated metal and a variety of silicate melts (magnesian-tholeiitic-siliceous-aluminous-aluminosiliceous basalts) depends modestly to strongly upon silicate melt structure and composition. Low valency siderophile elements, Fe, Ni and Co, show a modest influence of silicate melt composition on partitioning. Germanium shows a moderate but consistent preference for the depolymerized magnesian melt. High valency siderophile elements, P, Mo, and W, show more than an order of magnitude decrease in metal-silicate partition coefficients as the silicate melt becomes more depolymerized. Detailed inspection of our and other published W data shows that polymerization state, temperature and pressure are more important controls on W partitioning than oxidation state. For this to be true for a high and variable valence element implies a secondary role in general for oxidation state, even though some role must be present. Equilibrium core segregation through a magma ocean of ‘ultrabasic’ composition can provide a resolution to the ‘excess’ abundances of Ge, P, W and Mo in the mantle, but the mantle composition alone cannot explain the excess abundances of nickel and cobalt in chondritic proportions.

Jana, Dipayan; Walker, David

1997-08-01

334

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

335

In situ monitoring of the fibre strain distribution in carbon-fibre thermoplastic composites1. Application of a tensile stress field  

Microsoft Academic Search

The distribution of residual thermal strains and the mechanical response of carbon-fibre thermoplastic composites on the application of an external tensile stress have been studied. Confocal laser Raman microscopy has been employed to monitor the Raman wavenumbers of the embedded carbon fibres, within a predefined ‘window’ of observation. The application of a tensile stress field on the P75\\/ PEEK composite

C. Filiou; C. Galiotis

1999-01-01

336

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

2011-05-18

337

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

338

Characterization of Reinforcement Distribution in Cast Al-Alloy\\/SiC p Composites  

Microsoft Academic Search

The distribution of reinforcement in 10% SiC and 20% SiCp reinforced A356 alloy processed by gravity casting, squeeze casting, and roll casting is studied by using the mean free path, nearest neighbor distance, radial distribution function, and quadrat methods. The study is performed by using computer image analysis methods in an automated procedure to prevent operator errors, improve sample size,

P. A. Karnezis; G. Durrant; B. Cantor

1998-01-01

339

Characterization of reinforcement distribution in cast Al-alloy\\/SiC{sub p} composites  

Microsoft Academic Search

The distribution of reinforcement in 10% SiC and 20% SiC{sub p} reinforced A356 alloy processed by gravity casting, squeeze casting, and roll casting is studied by using the mean free path, nearest neighbor distance, radial distribution function, and quadrat methods. The study is performed by using computer image analysis methods in an automated procedure to prevent operator errors, improve sample

P. A. Karnezis; G. Durrant; B. Cantor

1998-01-01

340

Particles in the lower troposphere over the High Plains of the United States. I - Size distributions, elemental compositions and morphologies  

NASA Astrophysics Data System (ADS)

Airborne measurements of particle size distributions obtained during the spring and summer of 1975-1976 at various locations in the high plains of the U.S. are presented. The instrumentation and techniques used to collect the data are described. Particle number, surface area, and volume distribution are measured; differences in particle concentrations are investigated. Variables in particle size are related to changes in strength of ground sources of Aitken nuclei, age of the particle population, and presence or absence of rain. An accumulation mode between particles diameters of 0.1-1 micron, a coarse particle mode between particle diameters between 10-20 microns, and a nucleation mode at particle diameters less than 0.1 micron are detected. The control of the accommodation and coarse particle modes and their influence on particle concentration are studied. The elemental composition of the particles is analyzed and the morphologies are examined with an electron scanner microscope.

Hobbs, P. V.; Radke, W. F.; Bowdle, D. A.

1985-12-01

341

A feasibility study of altered spatial distribution of losses induced by eddy currents in body composition analysis  

PubMed Central

Background Tomographic imaging has revealed that the body mass index does not give a reliable state of overall fitness. However, high measurement costs make the tomographic imaging unsuitable for large scale studies or repeated individual use. This paper reports an experimental investigation of a new electromagnetic method and its feasibility for assessing body composition. The method is called body electrical loss analysis (BELA). Methods The BELA method uses a high-Q parallel resonant circuit to produce a time-varying magnetic field. The Q of the resonator changes when the sample is placed in its coil. This is caused by induced eddy currents in the sample. The new idea in the BELA method is the altered spatial distribution of the electrical losses generated by these currents. The distribution of losses is varied using different excitation frequencies. The feasibility of the method was tested using simplified phantoms. Two of these phantoms were rough estimations of human torso. One had fat in the middle of its volume and saline solution in the outer shell volume. The other had reversed conductivity distributions. The phantoms were placed in the resonator and the change in the losses was measured. Five different excitation frequencies from 100 kHz to 200 kHz were used. Results The rate of loss as a function of frequency was observed to be approximately three times larger for a phantom with fat in the middle of its volume than for one with fat in its outer shell volume. Conclusions At higher frequencies the major signal contribution can be shifted toward outer shell volume. This enables probing the conductivity distribution of the subject by weighting outer structural components. The authors expect that the loss changing rate over frequency can be a potential index for body composition analysis.

2010-01-01

342

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

Microsoft Academic Search

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

S. F. Corbin; D. S. Wilkinson

1994-01-01

343

Phytoplankton composition and spatial distribution of copper and zinc in the Fal Estuary (Cornwall, UK)  

Microsoft Academic Search

In the estuaries near Falmouth (Cornwall, UK) levels of dissolved copper and zinc are high, due to drainage of copper and tin mines. Phytoplankton species composition in the autumn of 1989 deviated in the metal-contaminated Restronguet Creek from that in other estuarine branches,viz. Fal, Tresillian and Percuil. In the riverine part of Restronguet Creek (Carnon River)Euglena mutabilis, known as an

J. W. Rijstenbil; A. G. A. Merks; J. Peene; T. C. W. Poortvliet; J. A. Wijnholds

1991-01-01

344

The distribution and composition of vascular plant communities on Heard Island  

Microsoft Academic Search

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

Jocelyne M. R. Hughes

1987-01-01

345

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

346

Representing Collections as Compositions to support distributed creative cognition and situated creative learning  

Microsoft Academic Search

We investigate how the creativity support tool combinFormation supports the creativity- oriented course, The Design Process, by representing collections as compositions. Undergraduate students in The Design Process are charged with working in inter- disciplinary teams to develop new inventions. combinFormation is a mixed-initiative system that integrates browsing, searching, representing, manipulating, and collecting digital information resources, using the form of the

Andruid Kerne; Eunyee Koh

2007-01-01

347

Stress distribution of bulk metallic glass\\/metal laminate composites during uni-axial fracture  

Microsoft Academic Search

The fracture behaviors of laminated composites of bulk metallic glass (BMG (Vitreloy1))\\/crystalline layer have been examined via both experimental and simulation approaches. The specimen array of BMG\\/Zr\\/BMG by an electron-discharge bonding technique showed a completed bonding, and the fracture tests showed that when the number of BMG layer increases up to three layers, the fracture energy for the laminated specimen

Y. H. Go; J. Cho; C. Y. Jeong; C. S. Kang; J. S. Park

2007-01-01

348

Effective wave number of composite materials with oriented randomly distributed inclusions  

Microsoft Academic Search

The design of composite materials with specific electromagnetic properties is important to applications in the aerospace, communications, defense, food, medical, power and transportation industries. In this paper, we follow the T-matrix method (P.C. Waterman, Proc. IEEE, vol. 53, no. 8, pp. 805-812, 1965; and Phys. Rev. D, vol. 3, no. 4, pp. 825-839, 1971), configurational averaging technique (L.L. Foldy, Phys.

Anyong Qing; Xin Xu; Yeow Beng Gan

2003-01-01

349

Chemical composition of arctic snow: concentration levels and regional distribution of major elements  

Microsoft Academic Search

At the end of the northern winter 1996\\/1997, 21 snow samples were collected from 17 arctic localities in Norway, Sweden, Finland, Svalbard, Russia, Alaska, Canada, Greenland and Iceland. Major element concentrations of the filtered (0.45 ?m) melted snow indicate that most samples are consistent with a diluted seawater composition. Deviations from this behaviour indicate additional SO42? and Cl? relative to

Patrice de Caritat; Gwendy Hall; William Belsey; Marlene Braun; Natalia I. Goloubeva; Hans Kristian Olsen; Jon Ove Scheie; Judy E. Vaive

2005-01-01

350

Multiple scale composition and spatial distribution patterns of the north-eastern Minnesota presettlement forest  

Microsoft Academic Search

Summary 1 Bearing tree data were used to characterize the composition and spatial structure of the southern boreal presettlement forest in north-eastern Minnesota, United States of America. Data collected during the General Land Office Survey (GLO) between 1853 and 1917, represents 35 324 samples (each with 1-4 trees) in a 3.2 million-hectare landscape. Nine tree species contributed at least 1%

Steven K. Friedman; Peter B. Reich; Lee E. Frelich

2001-01-01

351

[Effects of heavy metals pollution on paddy soil aggregates composition and heavy metals distribution].  

PubMed

Topsoil samples were collected from a polluted and an adjacent non-polluted paddy field in the Taihu Lake region of China. Different particle size fractions of soil aggregates were separated by low-energy dispersion procedure, and their mass composition and Pb, Cd, Hg, and As concentrations were determined. Under heavy metals pollution, the mass composition of sand-sized fractions reduced, while that of clay-sized fractions increased. The concentrations of test metals in different particle size fractions differed, with the highest in < 0.002 mm fraction, followed by in 2-0.2 mm fraction. In 0.02-0.002 mm and 0.2-0.02 mm fractions, all the test metals were relatively deficient, with an enrichment index of 0.56-0.96. The present study showed that the aggregation of fine particles could be depressed by heavy metals pollution, which in turn, led to a relative increase in the mass composition of fine particles and the associated allocation of heavy metals in weakly aggregated silt particles, and further, increased the risks of heavy metals translocation from polluted farmland into water and atmosphere. Further studies should be made on the impacts of heavy metals pollution on soil biophysical and biochemical processes and related mechanisms. PMID:20136020

Zhang, Liang-Yun; Li, Lian-Qing; Pan, Gen-Xing; Cui, Li-Qiang; Li, Hong-Lei; Wu, Xiao-Yan; Shao, Jie-Qi

2009-11-01

352

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

353

Stress distribution in a transversely loaded cross-shaped single fiber SCS-6/Ti-6Al-4V composite  

SciTech Connect

In most structural applications utilizing fiber reinforced metal matrix composites (MMCs), the mechanical response normal to the fiber direction has to be considered. The transverse response is very sensitive to the interface bond strength, which has commonly been determined by testing straight-sided 90{degree} specimens and interpreting debond initiation from the knee in the stress-strain curve as well as from a sudden drop in the Poisson`s ratio. In an attempt to modify the debond initiation site to an internal location free of uncharacteristic states of stress, a cross-shaped specimen has been developed. Experiments conducted by Gundel et al. indicated that this geometry was successful in obtaining the appropriate crack initiation site. In the present study, finite element analysis (FEA) was done on the cross-shaped specimen to obtain the stress distribution in the composite under transverse loading, in an effort to corroborate the success of this geometry in determining the true transverse response of the composite.

Warrier, S.G.; Gundel, D.B. [Systran Corp., Dayton, OH (United States); Majumdar, B.S. [UES Inc., Dayton, OH (United States); Miracle, D.B. [Wright Lab., Wright-Patterson AFB, OH (United States). Materials Directorate

1996-01-15

354

Age and menopause-associated variations in body composition and fat distribution in healthy women as measured by dual-energy x-ray absorptiometry  

Microsoft Academic Search

To assess the variation with age and menopause, 407 healthy normal women aged 18 to 75 years had body composition and fat distribution measured by dual-energy x-ray absorptiometry (DEXA). The mean ± SD are given for different age decades. Postmenopausal women had significantly more fat, a more central fat distribution, and less lean tissue mass (LTM) than premenopausal women. In

Ole Lander Svendsen; Christian Hassager; Claus Christiansen

1995-01-01

355

Flashover due to lightning of composite insulators used on distribution line  

Microsoft Academic Search

The problem of estimating lightning insulation strength of distribution line designs is complicated due to numerous factors. In general, classical techniques that account for air gap flashover do not apply. The fundamental reasons for these complications are still not precisely reported. Some researchers relate them to small distances between electrodes, others to the presence of wood insulation, insulator size, hardware

M. K. Izzularab; M. H. Shwehdi; A. S. Farag; C. A. Belhadj

1998-01-01

356

Aluminium-containing scales in water distribution systems: Prevalence and composition  

Microsoft Academic Search

Aluminium (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. Disruption of the scales could cause the release of associated trace metals. However, there is also the possibility that they have a protective effect on pipe surfaces

Vernon L. Snoeyink; Michael R. Schock; Lili Wang; Abraham S.-C. Chen; Stephen M. Harmon; Pankaj Sarin

357

Separating the Concerns of Distributed Deployment and Dynamic Composition in Internet Application Systems  

Microsoft Academic Search

The Internet is currently evolving from a global information network into a distributed application system. For example, some Internet applications are based on executing remote services which have been previously installed on possibly multiple Internet nodes, whereas parts of other Internet applications are dynamically moved from several remote nodes to be executed on a single node. In this paper, we

Stefan Paal; Reiner Kammüller; Bernd Freisleben

2003-01-01

358

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 ...

359

Particle size distribution and chemical composition of coal-tar fumes  

Microsoft Academic Search

The study was intended to characterize the chemical and physical nature of coal-tar fumes emitted from spreading applications of coal tar. Two separate experiments were performed. The first resulted in the determination of a coal-tar fume particle size distribution. The second experiment resulted in the identification of the primary compounds found in collected tar fumes and a determination of their

DOUGLAS C. HITTLE; JAMES J. STUKEL

1976-01-01

360

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.

Magalhaes, Tais C. A.; Vieira, Sarah A.; Priore, Silvia E.; Ribeiro, Andreia Q.; Lamounier, Joel A.; Franceschini, Sylvia C. C.; Sant'Ana, Luciana F. R.

2012-01-01

361

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

362

Chemical composition of essential oils of Litsea cubeba harvested from its distribution areas in China.  

PubMed

Litsea cubeba (Lour.) Pers. is a promising industrial crop with fruits rich in essential oils. The chemical composition of essential oils of L. cubeba (EOLC) were determined for fruits harvested from eight regions in China. The overall essential oil content, obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), ranged from 3.04% to 4.56%. In total, 59 compounds were identified, the dominant components being monoterpenes (94.4-98.4%), represented mainly by neral and geranial (78.7-87.4%). D-Limonene was unexpectedly a lesser constituent (0.7-5.3%) in fruits, which differed from previous reports (6.0-14.6%). Several components were only detected in certain regions and compounds such as o-cymene and eremophilene have never before been reported in EOLC. These results demonstrate significant regional variation in the chemical composition of EOLC. This investigation provides important information with regard to the bioactivity, breeding work and industrial applications of L. cubeba. PMID:22683894

Si, Linlin; Chen, Yicun; Han, Xiaojiao; Zhan, Zhiyong; Tian, Shengping; Cui, Qinqin; Wang, Yangdong

2012-06-08

363

Microscopic theory of optical properties of composite media with chaotically distributed nanoparticles  

SciTech Connect

The boundary problem of light reflection and transmission by a film with chaotically distributed nanoinclusions is considered. Based on the proposed microscopic approach, analytic expressions are derived for distributions inside and outside the nanocomposite medium. Good agreement of the results with exact calculations and (at low concentrations of nanoparticles) with the integral Maxwell-Garnett effective-medium theory is demonstrated. It is shown that at high nanoparticle concentrations, averaging the dielectric constant in volume as is done within the framework of the effective-medium theory yields overestimated values of the optical film density compared to the values yielded by the proposed microscopic approach. We also studied the dependence of the reflectivity of a system of gold nanoparticles on their size, the size dependence of the plasmon resonance position along the wavelength scale, and demonstrated a good agreement with experimental data. (photonics and nanotechnology)

Shalin, A S [V.A. Kotel'nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Ul'yanovsk Branch, Ul'yanovsk (Russian Federation)

2010-12-29

364

The distribution and stable carbon isotopic composition of dissolved organic carbon in estuaries  

Microsoft Academic Search

The distributions of dissolved organic carbon (DOC) and the natural carbon isotope ratio of DOC (DO13C) in estuaries reflect the predominant sources and sinks of organic matter from both allochthonous and autochthonous origins.\\u000a The traditional view is that DOC in land-margin ecosystems reflects mainly the mixing of land-derived and oceanic DOC. However,\\u000a this view is not consistent with the bulk

Bruce Peterson; Brian Fry; Meredith Hullar; Susan Saupe; Richard Wright

1994-01-01

365

Composition, Distribution, and Characterization of Organochlorine Pesticides in Sandstorm Depositions in Beijing, China  

Microsoft Academic Search

Sandstorms which distribute a great number of particles are a special atmospheric occurrence and are uncommon in northern\\u000a China. This study was conducted to determine, for the first time, the concentration of organochlorine pesticides (OCPs) in\\u000a sandstorm depositions. Samples were collected from urban areas of Beijing and a total of eight OCPs were measured. All samples\\u000a contained OCP residues. The

S. Fu; K. Li; Z. Z. Yang; X. B. Xu

2008-01-01

366

Composition and distribution of phytoplankton with size fraction results at southwestern east\\/japan sea  

Microsoft Academic Search

Abundance and distribution of phytoplankton in seawater at southwestern East\\/Japan Sea near Gampo were investigated by HPLC\\u000a analysis of photosynthetic pigments during summer of 1999. Detected photosynthetic pigments were chlorophyll a, b, c1+2 (Chl a, Chl b, Chl c1+2), fucoxanthin (Fuco), prasinoxanthin (Pras), zeaxanthin (Zea), 19’-butanoyloxyfucoxanthin (But-fuco) and beta-carotene (?-Car).\\u000a Major carotenoid was fucoxanthin (bacillariophyte) and minor carotenoids were Pras

Mi Ok Park

2006-01-01

367

Composition and distribution of phytoplankton with size fraction results at southwestern east\\/japan sea  

Microsoft Academic Search

Abundance and distribution of phytoplankton in seawater at southwestern East\\/Japan Sea near Gampo were investigated by HPLC analysis of photosynthetic pigments during summer of 1999. Detected photosynthetic pigments were chlorophyll a, b, c1+2 (Chl a, Chl b, Chl c1+2), fucoxanthin (Fuco), prasinoxanthin (Pras), zeaxanthin (Zea), 19'-butanoyloxyfucoxanthin (But-fuco) and beta-carotene (beta-Car). Major carotenoid was fucoxanthin (bacillariophyte) and minor carotenoids were Pras

Mi Ok Park

2006-01-01

368

Abundance, distribution and prey composition of scyphomedusae in the southern North Sea  

Microsoft Academic Search

The annual cycle of abundance and distribution of the scyphozoan medusae Aurelia aurita, Cyanea lamarckii, C. capillata and Chrysaora hysoscella were studied in the southern North Sea in 2004 and 2005. Three different patterns of seasonal occurrence of medusae were\\u000a distinguished: (1) the early occurring C. lamarckii (February–August), (2) C. capillata and A. aurita (April–August) and (3) the late appearing

Kristina Barz; Hans-Jürgen Hirche

2007-01-01

369

Distributed Aspect-Oriented Service Composition for Business Compliance Governance with Public Service Processes  

Microsoft Academic Search

Service-Oriented Architecture offers a technical foundation for Enterprise Application Integration and business collaboration through service-based business components. With increasing process outsourcing and cloud computing, enterprises need process-level integration and collaboration (process-oriented) to quickly launch new business processes for new customers and products. However, business processes that cross organisations' compliance regulation boundaries are still unaddressed. We introduce a distributed aspect-oriented service

MingXue Wang; Kosala Yapa Bandara; Claus Pahl

2010-01-01

370

Distributions of C4 plants along environmental and compositional gradients in southeastern Arizona  

Microsoft Academic Search

Distributional patterns of C4 plants were investigated in 4 study areas located in se Arizona: granite slopes in the Mule Mountains, limestone slopes in the Mule Mountains, calcareous bajada (alluvial plain) below the Mule Mountains, and limestone slopes in the Huachuca Mountains. Cover data for all vascular species were obtained from 238 0.1 ha (20×50 m) sample quadrats located over

T. R. Wentworth

1983-01-01

371

Identity, Meaning, and Engagement with School: A Native American Student's Composition of a Life Map in a Senior English Class  

ERIC Educational Resources Information Center

|This case study of a Native American high school senior focuses on one of the final assignments he completed before dropping out of school early in the school year. The task was to draw a life map--a nonverbal text that identified 10 key life events on his journey to that point--as part of a larger unit on identity for his senior English class.…

Smagorinsky, Peter; Anglin, Joanna L.; O'Donnell-Allen, Cindy

2012-01-01

372

Diatom valve distribution and sedimentary fatty acid composition in Larsen Bay, Eastern Antarctica Peninsula  

NASA Astrophysics Data System (ADS)

During austral summer 2006-2007, five sediment cores were recovered from the Eastern Antarctic Peninsula (EAP) continental shelf. Microscopic observations and sediment fatty acid (FA) composition analyses were carried out to investigate whether the drastic changes at the sea surface in EAP may be reflected in the sedimentary record. A sharp decrease in the number of diatom valves was observed below 2 cm depth. This difference between the upper 2 cm of sediment and the deeper part of the sediment column was attributed to the drastic change in the upper water column conditions after the collapse of the ice shelves, which allowed the arrival of phytoplankton debris and fresh organic matter to the sea floor in EAP. The presence of bacterial-, zooplankton- and detrital-related FA throughout EAP cores suggests that there has been an input of older and more refractory organic matter into the region, presumably by lateral transport before the Larsen ice shelves disintegration.

Sañé, E.; Isla, E.; Pruski, A. M.; Bárcena, M. A.; Vétion, G.; DeMaster, D.

2011-08-01

373

Sicilian lemon oil: Composition of volatile and oxygen heterocyclic fractions and enantiomeric distribution of volatile components.  

PubMed

A total of 92 samples of Sicilian lemon oils (Citrus limon (L.) Burm. f.) produced from September 2008 to June 2009, industrially cold-pressed by different extraction techniques (Brown Oil Extractor and Food Machinery Corporation), were analyzed by GC-flame ionization detector (FID) and GC/MS-LRI to investigate the volatile fraction; by RP-HPLC/PDA to determine the non-volatile components and by enantio-GC-FID to determine the enantiomeric ratios of 12 volatile components. This study provides a detailed investigation on the composition of Sicilian lemon essential oils industrially produced during a productive season, with the aim to recognize quality parameters for the characterization of this product. The results obtained are discussed to evaluate seasonal variation, influence of the extraction techniques, and are compared with those obtained for samples produced during different seasons. PMID:20931614

Dugo, Paola; Ragonese, Carla; Russo, Marina; Sciarrone, Danilo; Santi, Luca; Cotroneo, Antonella; Mondello, Luigi

2010-11-01

374

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

NASA Astrophysics Data System (ADS)

Particulate scattering and backscattering are two quantities that have traditionally been used to quantify in situ particulate concentration. The ratio of the backscattering by particles to total scattering by particles (the particulate backscattering ratio) is weakly dependent on concentration and therefore provides us with information on the characteristics of the particulate material, such as the index of refraction. The index of refraction is an indicator of the bulk particulate composition, as inorganic minerals have high indices of refraction relative to oceanic organic particles such as phytoplankton and detrital material that typically have a high water content. We use measurements collected near the Rutgers University Long-term Ecosystem Observatory in 15 m of water in the Mid-Atlantic Bight to examine application of the backscattering ratio. Using four different instruments, the HOBILabs Hydroscat-6, the WETLabs ac-9 and EcoVSF, and a prototype VSF meter, three estimates of the ratio of the particulate backscattering ratio were obtained and found to compare well. This is remarkable because these are new instruments with large differences in design and calibration. The backscattering ratio is used to map different types of particles in the nearshore region, suggesting that it may act as a tracer of water movement. We find a significant relationship between the backscattering ratio and the ratio of chlorophyll to beam attenuation. This implies that these more traditional measurements may be used to identify when phytoplankton or inorganic particles dominate. In addition, it provides an independent confirmation of the link between the backscattering ratio and the bulk composition of particles.

Boss, E.; Pegau, W. S.; Lee, M.; Twardowski, M.; Shybanov, E.; Korotaev, G.; Baratange, F.

2004-01-01

375

Improvement in the conversion efficiency of single-junction SiGe solar cells by intentional introduction of the compositional distribution  

NASA Astrophysics Data System (ADS)

We attempted to clarify the impact of the compositional distribution on recently reported improvement in the conversion efficiency of solar cells based on bulk multicrystalline SiGe. For this purpose, Si1-xGex/Si1-yGey multiple quantum well structures on heavily doped Si-on-insulator were employed as model crystals. The combination of x and y, the width of each layer, and the number of repetitions were systematically changed to study the influence of the introduction of Ge on photocarrier generation and carrier transport while keeping the average Ge composition as 0.03. Spatial modulation of the band structure leads to formation of quantum wells for holes and gives negative impact especially in the photocarrier collection from the n-type region. When the depth of wells was designed to be constant, short-circuit carrier density was found to show a maximum at appropriate compositional distribution due to the competition between the increase in the photocarrier generation and the decrease in the minority carrier diffusion length. Within a limited compositional range, the overall performance of the solar cell was revealed to be improved by the introduction of the compositional distribution compared with that based on uniform Si0.97Ge0.03. Therefore, intentional introduction of the compositional distribution is concluded to be useful for improvement in the solar cell performance if appropriate dispersion is chosen.

Tayanagi, Misumi; Usami, Noritaka; Pan, Wugen; Ohdaira, Keisuke; Fujiwara, Kozo; Nose, Yoshitaro; Nakajima, Kazuo

2007-03-01

376

Distribution  

Microsoft Academic Search

e're closer than you think: Portland's geographic location and Oregon's transportation infra - structure offer unmatched con - nectivity and time savings to international and domestic markets. Our economic development practices combine project-ready property with efficient, high-capacity infrastructure to create today's logistics advantages. Connecting people, places and products is the core of Portland's distribution and logistics industry sec - tor.

F. Gregory; B. Boyd; R. Bridges; D. Mitchell; J. Halsell; S. Fancher; D. King; R. Fore; E. Mango; D. Berlinrut; M. Leinbach; M. Maier; M. Wetmore; H. Herring; J. Guidi; M. Coolidge; J. Heald; T. Knox; D. Bartine; R. Bailey; H. Delgado; P. Conant; J. Madura; R. Thomas; F. Merceret; G. Allen; E. Bensman; R. Dittemore; N. Feldman; C. Boykin; H. Tileston; F. Brody; L. Hagerman; S. Pearson; L. Uccellini; W. Vaughan; J. Golden; D. Johnson; J. McQueen; B. Roberts; L. Freeman; G. Jasper; B. Hagemeyer; A. McCool; X. W. Proenza; S. Glover

2006-01-01

377

Composition, distribution, and characterization of polycyclic aromatic hydrocarbons in soil in Linfen, China  

SciTech Connect

A total of 10 surface soil samples representing the entire area of Linfen City were collected and analyzed for the presence of 16 polycyclic aromatic hydrocarbons. The total polycyclic aromatic hydrocarbon concentration ranged from 1.1 to 63.7 {mu} g g{sup -1}. Analysis of the sources of contamination revealed that polycyclic aromatic hydrocarbons in the soil were derived from combustion sources. Specifically, the primary source of polycyclic aromatic hydrocarbons was coal combustion, but the samples were also effected to varying degrees by traffic emissions. Furthermore, increased levels of contamination were observed in northeast Linfen due to the distribution of industrial plants.

Fu, S.; Cheng, H.X.; Liu, Y.H.; Xia, X.J.; Xu, X.B. [Chinese Academy of Sciences, Beijing (China)

2009-02-15

378

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

PubMed Central

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

Huang, Cheng; Elo, Irma T.

2010-01-01

379

Design for cyclic loading endurance of composites  

NASA Astrophysics Data System (ADS)

The application of the computer code IPACS (Integrated Probabilistic Assessment of Composite Structures) to aircraft wing type structures is described. The code performs a complete probabilistic analysis for composites taking into account the uncertainties in geometry, boundary conditions, material properties, laminate lay-ups, and loads. Results of the analysis are presented in terms of cumulative distribution functions (CDF) and probability density function (PDF) of the fatigue life of a wing type composite structure under different hygrothermal environments subjected to the random pressure. The sensitivity of the fatigue life to a number of critical structural/material variables is also computed from the analysis.

Shiao, Michael C.; Murthy, Pappu L. N.; Chamis, Christos C.; Liaw, Leslie D. G.

1993-12-01

380

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

381

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

382

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

383

Characteristic features of first and second moments of fission-fragment energy distribution as functions of nucleon composition  

SciTech Connect

We discuss the totality of experimental data obtained at the Alma-Ata isochronous cyclotron for the mean kinetic energy /similar to/(E/sub k/) and energy dispersion sigma/sub E//sup 2/ for nuclei with Z = 68--85, A = 165--213. The dependences of these first two moments of the E/sub k/ distribution as functions of the nucleon composition of the fissioning nucleus are found to have a new feature: a ''break'' in the curve in the vicinity of (Z/sup 2//A/sup 1//sup ///sup 3/)/sub 0/approx. =1000. This effect is due to the fact that the descent-to-scission stage is absent for fissioning nuclei with Z/sup 2//A/sup 1//sup ///sup 3/<(Z/sup 2//A/sup 1//sup ///sup 3/)/sub 0/.

Gruzintsev, E.N.; Itkis, M.G.; Mul'gin, S.I.; Okolovich, V.N.; Rusanov, A.Y.; Serdyuk, O.I.; Smirenkin, G.N.; Subbotin, M.I.

1988-08-01

384

Impact of hydrothermal pre-treatment to chemical composition, enzymatic digestibility and spatial distribution of cell wall polymers.  

PubMed

The effect of hydrothermal pretreatment on chemical composition, microscopic structure and enzymatic digestibility of wheat straw was studied. Wheat straw was pretreated with increasing severity to obtain series of samples with altered chemistry and structure. The hydrothermal pretreatment caused solubilisation of arabinoxylan and phenolic acids and their dimers in a temperature dependent manner with minor effects on the cellulose and Klason lignin content. In the cell wall level, the pretreatment intensified staining of cellulose and relocalised xylan in the cell walls. The distribution, properties and content of the cell wall phenolic compounds was altered as observed with phloroglucinol and autofluorescence imaging. In the enzymatic hydrolysis, the highest yields were obtained from the samples with a low xylan and diferulate content. On the cell wall structural level, the sample with the highest digestibility was observed to have intensified cellulose staining, possibly reflecting the increased accessibility of cellulose. PMID:23612175

Holopainen-Mantila, Ulla; Marjamaa, Kaisa; Merali, Zara; Käsper, Andres; de Bot, Peter; Jääskeläinen, Anna-Stiina; Waldron, Keith; Kruus, Kristiina; Tamminen, Tarja

2013-03-31

385

Study of Interfacial Stress Distribution in SiC Fiber Reinforced Titanium Matrix Composites on Transverse Tensile Tests  

NASA Astrophysics Data System (ADS)

A combination of the transverse tensile test and the unilaterally coupled finite element method was used to evaluate the interfacial normal bond strength and stress distribution of titanium matrix composites (TMCs). In addition, in order to identify the interface shear failure mode of TMCs under transverse loading, both the push-out test and the finite element method have been developed to characterize the interfacial shear strength of TMCs, which is the interfacial shear failure criterion. This article studies the results of the experiments, which suggested that the interfacial normal bond and shear strength of SiCf/Ti-6Al-4V were 300 and 350 MPa, respectively, and the interface failure mode of TMCs under the transverse tensile test was radial failure rather than shear failure. Moreover, the effect of residual stress on the radial stress is also discussed in detail in this article.

Yanfang, Xu; Tiexiong, Su; Meini, Yuan

2012-11-01

386

Sources of aerosol as determined from elemental composition and size distributions in Beijing  

NASA Astrophysics Data System (ADS)

Samples of PM 2.5, PM 10, and TSP from 2001 to 2003 have been collected in Beijing during spring (low-dust), spring (high dust), summer and winter. The concentration of TSP, PM 10, and PM 2.5 was most abundant in spring with high dust followed by winter, spring with little dust and summer. The average mass ratios of PM > 10 , PM 2.5-10 and PM 2.5 to TSP show that the large coarse fraction (PM > 10 ) and the fine fraction (PM 2.5) contribute most in spring with high dust while PM 2.5, PM 2.5-10, and PM > 10 contributed similar fractions to TSP in summer and PM 2.5 in winter. Sixteen cascade impaction samples were collected for elemental analysis in 2000 and 2001 and 16 major components were analyzed by PIXE. Based on the characteristics of the size distribution, three different patterns are observed: coarse mode, fine mode and bimodal mode. Different groups showed different characteristics. Crustal elements showed stable size shapes between different seasons, however, pollution elements showed complex and more variations, and the size distribution showed tendency to vary between unimodal fine modes and bimodal modes. Additionally, the concentration of aerosols and the temporal variation of the elements varied significantly according to different meteorological conditions especially on haze-fog weather conditions. Different elements showed different size distributions on haze-fog weather, i.e. crustal elements of Al, Si, Ca showed similar variation with those average days, pollution elements of S, As, Zn showed significantly higher level than those average values but mixed elements of K, Mn, Cu, Pb showed not so higher than those pollution elements. The high S in haze-fog weather was most from water soluble sulfate parts, the bimodal modes of elements showed unimodal variation and the peak of accumulation modes showed tendency variation to the larger sizes in haze-fog weather. However, most crustal elements showed not much increase during haze-fog condition, which is consistent to other researches. Most of the elements in coarse fractions showed higher concentrations in the nighttime than those in the daytime. In addition, most peaks of accumulation modes showed higher in daytime than those in nighttime, and/or showed tendency to increase to larger sizes. Taking into account the properties of aerosols coming from different sources in the winter, the direction from which air masses are transported affects the characteristics of the particles, i.e. cleaner air from the northwest and more polluted air from the south. There were also similar variations in potassium and manganese, indicating waste incineration as a common source.

Zhang, Wenjie; Zhuang, Guoshun; Guo, Jinghua; Xu, Dongqun; Wang, Wei; Baumgardner, Darrel; Wu, Zhiyuan; Yang, Wen

2010-02-01

387

Latitudinal distribution of nitrogen isotopic composition in suspended particulate organic matter in tropical/subtropical seas.  

PubMed

Natural nitrogen isotopic composition (?(15)N) of suspended particulate organic matter (POM) and nitrogen fixation rates via (15)N(2) assay were measured in surface waters along 120° E from 30° N to 30° S in the Asian marginal seas (the East/South China Seas and the Sulu/Celebes/Java Seas) and the northeastern Indian Ocean in November-December 2005 and March 2006. The POM ?(15)N values ranged from-1.8 to 12.2‰ with an average of 3.6‰ and showed a decreasing trend towards the equator in both hemispheres. In parallel, the measured N(2) fixation rates showed an increase from the subtropical to the tropical seas. This implies that a higher contribution of (15)N-depleted POM was derived from enhanced N(2) fixation. Water temperature and the stability of water column were partly responsible for the observed variations in nitrogen fixation. The large-scale spatial variations in suspended POM ?(15)N and N(2) fixation rates suggest that the suspended POM ?(15)N may be a potential indicator of nitrogen fixation in surface waters in tropical/subtropical seas. PMID:22004405

Zhang, Run; Chen, Min; Ma, Qiang; Cao, Jianping; Qiu, Yusheng

2011-10-17

388

Plankton composition, distribution and significance in a tropical integrated pilot constructed treatment wetland in Uganda.  

PubMed

The importance of the plankton community in wastewater treatment has been under-estimated for a long time, simply because of its biomass accumulation resulting in final release of organic matter back into the system after decomposition. In a two-year 3-month periodical study on a tropical integrated wastewater treatment constructed wetland, the phytoplankton role was tested and it has been shown that, through harvesting, the phytoplankton community plays a significant role in municipal wastewater treatment. The high phytobiomass, which was dominated by green algae (Chlorophyta), enhanced high levels of dissolved oxygen and high pH within the open ponds, and because of this, the system was found to be highly efficient in BOD5 (81%) and NH4+-N (93%) removal. The high pH enhanced ammonia volatilization within the open ponds. Regression statistics between the plankton community composition and some of the physicochemical parameters (BOD, NH4+-N, DO, pH) within the wetland system show a significant relationship. In conclusion, open treatment wetlands provide a wide variety of planktonic organisms as water quality improvement systems through the provision of oxygen and alteration of the pH for BOD5 and ammonium reduction respectively. PMID:14621170

Luyiga, S; Kiwanuka, S

2003-01-01

389

Homogeneous distribution of 26Al in the solar system from the Mg isotopic composition of chondrules.  

PubMed

The timing of the formation of the first solids in the solar system remains poorly constrained. Micrometer-scale, high-precision magnesium (Mg) isotopic analyses demonstrate that Earth, refractory inclusions, and chondrules from primitive meteorites formed from a reservoir in which short-lived aluminum-26 (26Al) and Mg isotopes were homogeneously distributed at +/-10%. This level of homogeneity validates the use of 26Al as a precise chronometer for early solar system events. High-precision chondrule 26Al isochrons show that several distinct chondrule melting events took place from approximately 1.2 million years (My) to approximately 4 My after the first solids condensed from the solar nebula, with peaks between approximately 1.5 and approximately 3 My, and that chondrule precursors formed as early as 0.87(-0.16)(+0.19) My after. PMID:19696348

Villeneuve, Johan; Chaussidon, Marc; Libourel, Guy

2009-08-21

390

Impact of prebiotic synthesis and diagenesis on the distribution, stereochemistry, and stable isotope composition of amino acids in carbonaceous meteorites  

NASA Astrophysics Data System (ADS)

Simulation experiments for prebiotic synthesis result in racemic mixtures (D/L = 1.0) for protein and non-protein amino acids, irrespective of the composition of the precursor gas mixtures or the energy sources employed. It is therefore not surprising that it was commonly assumed that if amino acids in carbonaceous meteorites were formed by similar reactions they would also be racemic. Engel and Nagy1 and more recently Glavin et al.2 have shown that protein amino acids in carbonaceous meteorites often exhibit a moderate to strong L-amino acid excess (D/L ? 1.0). Engel3 hypothesized that this extraterrestrial L-excess might be the precursor material from which life as we know it originated. Stable isotope analysese.g 4 confirmed that the L-amino acid excess in meteorites was indigenous rather than the result of contamination subsequent to impact on Earth. A key question that arises is that since there are no known mechanisms for the direct prebiotic synthesis of amino acids with an L-enantiomer excess, how did these compounds come to exist in carbonaceous meteorites? It has been proposed5 and references therein that a series of diagenetic reactions subsequent to synthesis are responsible for the L-enantiomer excess. In this paper, this hypothesis is further explored with respect to explaining the range of D/L values for amino acids in the various types of carbonaceous meteorites as well as in different stones of the same meteorite. Possible effects of diagenesis on the stable isotope compositions of these compounds are also addressed.

Engel, Michael H.

2013-09-01

391

Chemical composition of arctic snow: concentration levels and regional distribution of major elements.  

PubMed

At the end of the northern winter 1996/1997, 21 snow samples were collected from 17 arctic localities in Norway, Sweden, Finland, Svalbard, Russia, Alaska, Canada, Greenland and Iceland. Major element concentrations of the filtered (0.45 mum) melted snow indicate that most samples are consistent with a diluted seawater composition. Deviations from this behaviour indicate additional SO(4)(2-) and Cl(-) relative to seawater, suggesting a minor contribution from (probably local) coal combustion emissions (Alaska, Finland, Sweden, Svalbard). The samples with the highest Na and Cl(-) content (Canada, Russia) also have higher Na/SO(4)(2-) and Cl(-)/SO(4)(2-) ratios than seawater, suggesting a slight contamination from (probably local) deicing activities. Local soil or rock dust inputs in the snow are indicated by 'excess' Ca contents (Alaska, Svalbard, Greenland, Sweden). No overall relationship was found between pH (range: 4.6-6.1) and total or non-seasalt SO(4)(2-) (NSS), suggesting that acidification due to long-range transport of SO(2) pollution is not operating on an arctic-wide scale. In a few samples (Alaska, Finland, Sweden, Svalbard), a significant proportion (>50%) of SO(4)(2-) is non-marine in origin. Sources for this non-marine SO(4)(2-) need not all be found in long-range atmospheric transport and more likely sources are local industry (Finland, Sweden), road traffic (Alaska) or minor snow-scooting traffic (one Svalbard locality). A few samples from northern Europe show a relatively weak trend of decreasing pH with increasing NO(3)(-). PMID:15589258

de Caritat, Patrice; Hall, Gwendy; Gìslason, Sigurdur; Belsey, William; Braun, Marlene; Goloubeva, Natalia I; Olsen, Hans Kristian; Scheie, Jon Ove; Vaive, Judy E

2005-01-01

392

A piezolaminated composite degenerated shell finite element for active control of structures with distributed piezosensors and actuators  

NASA Astrophysics Data System (ADS)

This paper deals with the formulation of a nine-noded piezolaminated degenerated shell finite element for modeling and analysis of multilayer composite general shell structures with bonded/embedded distributed piezoelectric sensors and actuators. The distributed PZT sensors and actuators used in the composite smart structures are relatively thin and could have arbitrary variation of curvatures and thicknesses. They cannot be modeled with shell elements based on curvilinear shell theories which would need the specification of constant shell curvatures and thicknesses. Modeling them with piezo finite elements available in popular commercial codes like ABAQUS, ANSYS, MARC, etc, would need relatively greater computational effort as they are based on solid element formulation. In view of these, the present proposed degenerated piezoelectric shell element would be a better choice giving good computational accuracy and efficiency. The main advantage of a degenerate shell element is that it is not based on any shell theories and is applicable over a wide range of curvatures and thicknesses. This element is developed by using the degenerate solid approach based on Reissner-Mindlin assumptions which allow the shear deformation and rotary inertia effect to be considered and the 3D field is reduced to a 2D field in terms of mid-surface nodal variables. Uniformly reduced integration is carried out to overcome membrane locking and shear locking and the numerical integration is carried out in all three directions to obtain accurate results. The present element has 45 elastic degrees of freedom and 10 electric degrees of freedom per piezoelectric layer in the element. The potential induced due to bending deformation is more accurately represented by assuming quadratic variation of the electric potential through the thickness of each piezoelectric layer. This is achieved by interpolating using nodal mid-plane electric potentials and one electric degree of freedom representing the potential difference between the top and bottom surfaces of the piezoelectric layer. Few case studies of composite general shells with piezoelectric sensors and actuators have been considered by modeling them with the above elements and the active vibration control performance has been studied using linear quadratic Gaussian (LQG) control.

Balamurugan, V.; Narayanan, S.

2008-06-01

393

Exogenous androgens influence body composition and regional body fat distribution in obese postmenopausal women--a clinical research center study.  

PubMed

Abdominal fat distribution is influenced by androgen levels in both men and women. The purpose of this study was to assess the effects on fat distribution of administering nandrolone decanoate (ND; an anabolic steroid with weak androgenic activity) or spironolactone (SP; an antiandrogen) in obese postmenopausal women. The design was a randomized, placebo-controlled, 9-month trial with simultaneous calorie restriction for weight loss. Women in all three groups lost comparable amounts of weight, but the ND-treated women gained lean mass relative to the other two groups (P < 0.0005) and lost more body fat than women in the SP group (P < 0.01). The resting metabolic rate also increased slightly in the ND group. ND treatment produced a gain in visceral fat, as determined by computed tomography scan, and a relatively greater loss of sc abdominal fat. SP-treated women lost significantly less sc fat than the other two groups. Serum cholesterol decreased in the placebo group, but increased slightly in the other two groups (significant for SP vs. placebo, P < 0.05). High density lipoprotein cholesterol decreased significantly in the ND-treated women. There were no significant changes in fasting glucose or insulin sensitivity. We conclude that administration of exogenous androgens modulates body composition in obese postmenopausal women and independently affects visceral and sc abdominal fat. PMID:8964851

Lovejoy, J C; Bray, G A; Bourgeois, M O; Macchiavelli, R; Rood, J C; Greeson, C; Partington, C

1996-06-01

394

Barely visible impact damage detection for composite sandwich structures by optical-fiber-based distributed strain measurement  

NASA Astrophysics Data System (ADS)

The authors developed an impact damage-detection system for large-scale composite sandwich structures using an optical fiber network running throughout the structure. A Brillouin-based sensing system with high spatial resolution (pre-pump pulse Brillouin optical time-domain analysis (PPP-BOTDA)) was utilized for distributed strain measurement. The PPP-BOTDA sensing system can measure axial strain along the optical fiber by employing stimulated Brillouin scattering. The system realizes a spatial resolution of 10 cm, a sampling interval of 5 cm, and a sensing range of more than 1 km. Our previous study revealed that a non-uniform axial strain within centimeter spatial resolution broadens the width of the Brillouin gain spectrum, which is the output of the PPP-BOTDA. The specific response of the PPP-BOTDA was employed to detect non-uniform strain distribution along a residual facesheet dent in a damaged area. First, the response of the optical fiber sensor network, formed in the adhesive layer, was simulated to clarify the effectiveness and limitations of the proposed damage-detection technique. The system was then validated by an experiment. As the damage became larger, the width of the Brillouin gain spectra became broader. Consequently, the location and size of barely visible damage could be estimated. The system developed is quite useful for a first inspection of large-scale sandwich structures in aerospace and marine applications.

Minakuchi, S.; Okabe, Y.; Mizutani, T.; Takeda, N.

2009-08-01

395

Raman Microscopy for Non-Invasive Imaging of Pharmaceutical Nanocarriers: Intracellular Distribution of Cationic Liposomes of Different Composition  

PubMed Central

Nanotechnology is playing an increasing role in targeted drug delivery into pathological tissues. Drug-loaded pharmaceutical nanocarriers can be delivered into diseased sites by passive targeting (spontaneous accumulation of nanocarriers in the areas with affected vasculature) or by active targeting (via site-specific ligands attached to the surface of drug-loaded nanocarriers). Subsequent level of targeting requires cellular internalization of nanocarriers and their specific association with certain individual cell organelles. The control over intracellular distribution of pharmaceutical nanocarriers requires effective and non-invasive methods of their visualization inside cells. In an attempt to enhance cellular internalization of pharmaceutical nanocarriers and their association with mitochondria specifically, we have prepared three types of cationic liposomes and investigated their intracellular distribution. The analysis was performed using Raman microspectroscopy in combination with optical microscopy, in order to provide morphological information as well as biochemical signatures of the sample. It was demonstrated that the Raman microscopy allows to evaluate the extent of mitochondrial association depending on the liposome composition.

Sawant, R. R.; Miljkovic, M.; Quintero, L.; Diem, M.

2012-01-01

396

The Effect of Solid Particle Erosion on the Mechanical Properties and Fatigue Life of Fiber-reinforced Composites  

Microsoft Academic Search

The effect of solid particle erosion on the strength and fatigue properties of E-glass\\/epoxy composite is investigated. Solid particle erosion with SiC particles of 400–500 &mgr;m in diameter is simulated on 12-ply [45°\\/–45°\\/0°\\/45°\\/–45°\\/0°]S E-glass\\/epoxy composites with a constant particle velocity of 42.5 m\\/s and a solid particle to air volume ratio of 6 kg\\/m3 at impact angles of 90, 60,

N. Yang; H. Nayeb-Hashemi

2007-01-01

397

Effect of Long-Term Somatotropin Treatment on Body Composition and Life Span in Aging Obese Zucker Rats  

Microsoft Academic Search

The objective of this work was to test the hypothesis that a somatotropin (STH)-induced reduction in body fat would pro- long the life span of the obese Zucker rat. Two experiments were conducted. In the first experiment, male and female, lean and obese Zucker rats were treated with STH (0 or 2 mg\\/d bovine STH) for 4 weeks, beginning at

MICHAEL J. AZAIN; J. ROGER BRODERSON; ROY J. MARTIN

398

Composition and distribution of phytoplankton with size fraction results at southwestern east/japan sea  

NASA Astrophysics Data System (ADS)

Abundance and distribution of phytoplankton in seawater at southwestern East/Japan Sea near Gampo were investigated by HPLC analysis of photosynthetic pigments during summer of 1999. Detected photosynthetic pigments were chlorophyll a, b, c1+2 (Chl a, Chl b, Chl c1+2), fucoxanthin (Fuco), prasinoxanthin (Pras), zeaxanthin (Zea), 19’-butanoyloxyfucoxanthin (But-fuco) and beta-carotene (?-Car). Major carotenoid was fucoxanthin (bacillariophyte) and minor carotenoids were Pras (prasinophyte), Zea (cyanophyte) and But-fuco (chrysophyte). Chl a concentrations were in the range of 0.16-8.3/land subsurface chlorophyll maxima were observed at 0-10m at inshore and 30-50 m at offshore. Thermocline and nutricline tilted to the offshore direction showed a mild upwelling condition. Results from size-fraction showed that contribution from nano+picoplankton at Chl a maximum layer was increased from 18% at inshore to 69% at offshore on average. The maximum contribution from nano+picoplankton was found as 87% at St. E4. It was noteworthy that contribution from nano+picoplanktonic crysophytes and green algae to total biomass of phytoplankton was significant at offshore. Satellite images of sea surface temperature indicated that an extensive area of the East/Japan Sea showed lower temperature (<18 °C) but the enhanced Chl a patch was confined to a narrow coastal region in summer, 1999. Exceptionally high flux of low saline water from the Korea/Tsushima Strait seemed to make upwelling weak in summer of 1999 in the study area. Results of comparisons among Chl a from SeaWIFs, HPLC and fluorometric analysis showed that presence of Chl b cause underestimation of Chl a about 30% by fluorometric analysis but overestimation by satellite data about 30-75% compared to HPLC data.

Park, Mi Ok

2006-12-01

399

Composition, acquisition, and distribution of the Vi exopolysaccharide-encoding Salmonella enterica pathogenicity island SPI-7.  

PubMed

Vi capsular polysaccharide production is encoded by the viaB locus, which has a limited distribution in Salmonella enterica serovars. In S. enterica serovar Typhi, viaB is encoded on a 134-kb pathogenicity island known as SPI-7 that is located between partially duplicated tRNA(pheU) sites. Functional and bioinformatic analysis suggests that SPI-7 has a mosaic structure and may have evolved as a consequence of several independent insertion events. Analysis of viaB-associated DNA in Vi-positive S. enterica serovar Paratyphi C and S. enterica serovar Dublin isolates revealed the presence of similar SPI-7 islands. In S. enterica serovars Paratyphi C and Dublin, the SopE bacteriophage and a 15-kb fragment adjacent to the intact tRNA(pheU) site were absent. In S. enterica serovar Paratyphi C only, a region encoding a type IV pilus involved in the adherence of S. enterica serovar Typhi to host cells was missing. The remainder of the SPI-7 islands investigated exhibited over 99% DNA sequence identity in the three serovars. Of 30 other Salmonella serovars examined, 24 contained no insertions at the equivalent tRNA(pheU) site, 2 had a 3.7-kb insertion, and 4 showed sequence variation at the tRNA(pheU)-phoN junction, which was not analyzed further. Sequence analysis of the SPI-7 region from S. enterica serovar Typhi strain CT18 revealed significant synteny with clusters of genes from a variety of saprophytic bacteria and phytobacteria, including Pseudomonas aeruginosa and Xanthomonas axonopodis pv. citri. This analysis suggested that SPI-7 may be a mobile element, such as a conjugative transposon or an integrated plasmid remnant. PMID:12923078

Pickard, Derek; Wain, John; Baker, Stephen; Line, Alexandra; Chohan, Sonia; Fookes, Maria; Barron, Andrew; Gaora, Peadar O; Chabalgoity, José A; Thanky, Niren; Scholes, Christoph; Thomson, Nicholas; Quail, Michael; Parkhill, Julian; Dougan, Gordon

2003-09-01

400

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

ERIC Educational Resources Information Center

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

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

2006-01-01

401

Human Health Impact as a Boundary Selection Criterion in the Life Cycle Assessment of Pultruded Fiber Reinforced Polymer Composite Materials  

Microsoft Academic Search

SummaryThe human health impact of fiber reinforced polymer (FRP) composite materials manufactured by the pultrusion industry is not fully understood. In particular, it is unclear whether the human health impact of toxic chemicals present in low concentrations in fire retardant pultruded FRP materials is disproportionately high. This impact may be an important criterion when making boundary selection decisions in the

John P. Basbagill; Michael D. Lepech; Subhan M. Ali

2012-01-01

402

Changes in the distribution and composition of plasma high density lipoproteins after ingestion of fat.  

PubMed

Following ingestion of a fatty meal there is an increase in concentration of phospholipids and proteins in the plasma high density lipoproteins (HDL). To evaluate the resulting changes in HDL subclasses, the plasma HDL of six subjects were analyzed 4 to 8 h after ingestion of 100 ml of corn oil or 80 ml of corn oil with four eggs. Isopycnic density gradient ultracentrifugation of fasting plasma showed two broad components of HDL: a major peak of density (d) 1.11 to 1.17 g/ml (HDL3) and a smaller peak of d 1.07 to 1.11 g/ml (HDL2). Following ingestion of either type of fatty meal, there was an increase in lipoprotein mass in both peaks of HDL and their centers of mass were shifted to lower density (1.140 leads to 1.120 to 1.130 g/ml; 1.095 leads to 1.090 g/ml). Calculation of changes in HDL concentration (lipemic minus fasting) showed that the alterations in density gradient profile were due to a major increase in lipoproteins of d 1.102 to 1.137 g/ml, a smaller increase in a separate lipoprotein peak of 1.080 to 1.102 g/ml, and a small decrease in lipoproteins of d 1.137 to 1.165 g/ml. Redistribution of HDL mass into larger, less dense lipoproteins was also demonstrated by agarose gel chromatography or by minimal spin density gradient ultracentrifugation in a vertical rotor. The increase in mass of 1.080 to 1.102 lipoproteins was largely due to increased concentrations of phospholipid, cholesterol ester, and apoA-I, while the increase in 1.102 to 1.137 lipoproteins was due to increased concentrations of apoA-I, apoA-II, phospholipids, cholesterol, and cholesterol esters. Analytical ultracentrifugation of representative samples within these density intervals showed lipoprotein species with molecular weights and sedimentation coefficients, respectively, of 378,000, 5.8 (d 1.080 to 1.095); 248,000, 3.5 (d 1.110 to 1.120); and 173,000, 1.6 (d 1.135 to 1.150). Polyacrylamide gradient gel electrophoresis showed that the 1.080 to 1.102 lipoproteins contained a single lipoprotein band of diameter approximately 10.7 nm; the 1.102 to 1.137 lipoproteins contained a single band which varied in size fro 10.0 to 9.2 nm: and the 1.137 to 1.165 lipoproteins contained three species of diameters approximately 9.2, 8.8, and 8.2 nm. Within density intervals, the molecular weights, sedimentation coefficients, and diameters of the different lipoproteins were similar in fasting and lipemic plasma. Calculation of average molecular compositions shows that the major incremental HDL of d approximately 1.12 g/ml could be derived by addition of lipids to the largest species of fasting HDL3. Within density intervals, the particle contents of apoA-I and apoA-II were unchanged during lipemia, suggesting that apoprotein transfer causes interconversion of existing HDL species or formation of new particles with the same content of apoA-I and apoA-II as existing species. PMID:6796585

Tall, A R; Blum, C B; Forester, G P; Nelson, C A

1982-01-10

403

Long-term changes in community composition and life-history traits in a highly exploited basin (northern Adriatic Sea): the role of environment and anthropogenic pressures.  

PubMed

The changes in a marine community in the northern Adriatic Sea were explored over a period of 65 years using landings data from a commercial fishing fleet, and the role of fishing pressure and environmental variations in driving these changes was investigated. A total of 40 taxonomic categories, including one or several species, were analysed, representing 93·7% of the total landings. From 1945 to 2010 a significant decrease in the evenness index was observed, indicating a trend towards landings dominated by fewer taxa. The composition of the landings showed a temporal shift during the 1980s; from 1945 to the 1980s a continuous, clear change in composition took place, probably driven by an increase in fishing pressure as well as riverine nutrient inputs. Since the 1980s, a different trend of changing composition emerged. Among the analysed predictors, fishing capacity, summer seawater temperature, inflow from the Po River (the major river of the northern Adriatic Sea) and nutrients were related to the changes in landings. In relation to life-history traits of the landed species, the community shifted from large, late-maturing species to more fecund, smaller and earlier-maturing species. A high fishing pressure is probably the major cause of these changes, possibly acting synergistically with environmental variations. PMID:22136236

Barausse, A; Michieli, A; Riginella, E; Palmeri, L; Mazzoldi, C

2011-12-01

404

The Use Of Composite Material Strips To Extend The Damage-Tolerance Life Of Integrally Stiffened Aluminum Panels  

Microsoft Academic Search

This paper describes testing and analysis performed on integrally stiffened aluminum panels reinforced by carbon-epoxy or\\u000a boron-epoxy bonded strips. Testing was performed at room-temperature and at ?50°C. The test results identify a large potential\\u000a for increasing significantly the damage-tolerance life of these panels. The analytical results, based on finite-element models,\\u000a correlate very well with the test results.

A. Brot; Y. Peleg-Wolfin; I. Kressel; Z. Yosef

405

Building Life Cycle Cost Computer Program (BLCC) Version 5.2-04 (software distributed on CD-ROM).  

National Technical Information Service (NTIS)

The NIST Building Life-Cycle Cost (BLCC) computer program provides economic analysis of proposed capital investments that are expected to reduce long-term operating costs of buildings or building systems. It is especially useful for evaluating the costs a...

2004-01-01

406

Probability distributions of facilities management costs for whole life cycle costing in acute care NHS hospital buildings  

Microsoft Academic Search

Whole life cycle costing (WLCC) can provide a valuable insight into the economic efficiency of National Health Service (NHS) acute care hospital buildings. The costs of the facilities management function form an integral part of that process. However, the nature of facilities management cost data collated by NHS Estates informs the analyst little about the relationship between the physical characteristics

Richard J. Kirkham; A. Halim Boussabaine; Belal H. Awwad

2002-01-01

407

Association of Coronary Wall Shear Stress With Atherosclerotic Plaque Burden, Composition, and Distribution in Patients With Coronary Artery Disease  

PubMed Central

Background Extremes of wall shear stress (WSS) have been associated with plaque progression and transformation, which has raised interest in the clinical assessment of WSS. We hypothesized that calculated coronary WSS is predicted only partially by luminal geometry and that WSS is related to plaque composition. Methods and Results Twenty?seven patients with coronary artery disease underwent virtual histology intravascular ultrasound and Doppler velocity measurement for computational fluid dynamics modeling for WSS calculation in each virtual histology intravascular ultrasound segment (N=3581 segments). We assessed the association of WSS with plaque burden and distribution and with plaque composition. WSS remained relatively constant across the lower 3 quartiles of plaque burden (P=0.08) but increased in the highest quartile of plaque burden (P<0.001). Segments distal to lesions or within bifurcations were more likely to have low WSS (P<0.001). However, the majority of segments distal to lesions (80%) and within bifurcations (89%) did not exhibit low WSS. After adjustment for plaque burden, there was a negative association between WSS and percent necrotic core and calcium. For every 10 dynes/cm2 increase in WSS, percent necrotic core decreased by 17% (P=0.01), and percent dense calcium decreased by 17% (P<0.001). There was no significant association between WSS and percent of fibrous or fibrofatty plaque components (P=NS). Conclusions In patients with coronary artery disease: (1) Luminal geometry predicts calculated WSS only partially, which suggests that detailed computational techniques must be used to calculate WSS. (2) Low WSS is associated with plaque necrotic core and calcium, independent of plaque burden, which suggests a link between WSS and coronary plaque phenotype. (J Am Heart Assoc. 2012;1:e002543 doi: 10.1161/JAHA.112.002543.)

Eshtehardi, Parham; McDaniel, Michael C.; Suo, Jin; Dhawan, Saurabh S.; Timmins, Lucas H.; Binongo, Jose Nilo G.; Golub, Lucas J.; Corban, Michel T.; Finn, Aloke V.; Oshinski, John N.; Quyyumi, Arshed A.; Giddens, Don P.; Samady, Habib

2012-01-01

408

Distribution, Composition and Diversity of Restoration Vegetation on Tudiling Giant Panda Corridor in the Upper Reaches of Minjiang River, SW China  

Microsoft Academic Search

Tudiling Giant Panda Corridor, is the typical region of the Giant Panda Corridor habitat and the vegetation degradation in the upper Minjiang River basin, in which the effects of the existing disturbance regimes on plant communities after the vegetation restoration in the 1980s were assessed, and the distribution, composition and species diversity of restoration vegetation were analyzed using the transect

Yong Jian Wang; Man Ping Tao; Wei Yin Zhang; Run Guo Zang

2008-01-01

409

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  

Microsoft Academic Search

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 CO2 by the ocean. The community composition, abundance and distribution of marine protists (phytoplankton and protozoa) was studied during the

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

2010-01-01

410

A study of the scattering properties of an ensemble of rectangular prisms of different composition, size distribution and aspect ratios: a possible application to cometary dust grains?  

NASA Astrophysics Data System (ADS)

We have approached the scattering properties of cometary dust using size and shape distributions of non-spherical randomly oriented compact particles having non-homogeneous composition. In our model we have used inhomogeneous rectangular prisms in which the aspect ratio between the main axes and the index of the power law size distribution are varied. Two different compositions have been considered. The first one is silicate with carbon inclusions mixed with dirty ice, while the second one is silicate with carbon inclusions. We have obtained that both the width and the depth of the negative polarization branch have a clear dependence on the aspect ratio of the rectangular prisms and the composition. The best fits to the linear polarization curve of cometary grains have been obtained by a non constant distribution of rectangular prisms of the second composition where the elongate-shaped prisms prevail. Moreover, although the irregularity is not accurately represented by this type of distribution, curiously, its usage has shown that the scattering matrix element F34/F11 is very sensitive to the aspect ratio of the particles constituting the synthetic sample.

Vilaplana, Rosario; Moreno, Fernando; Molina, Antonio

2005-01-01

411

Spatial distribution and species composition of tree seeds and seedlings under the canopy of the shrub, Chromolaena odorata Linn., in Ghana  

Microsoft Academic Search

The spatial distribution and species composition of tree seedlings and seeds under the canopy of the shrub, Chromolaena odorata Linn., were investigated at a 4ha disturbed site that was surrounded by natural forests on two sides. For the seedling study, one hundred and eight 5m2 circular plots were established systematically (at 20m intervals) with a random start point. For the

Y. A. K Honu; Q. L Dang

2002-01-01

412

Glycemic index and glycemic load in relation to changes in body weight, body fat distribution, and body composition in adult Danes13  

Microsoft Academic Search

Background: A diet with a high glycemic index (GI) and glycemic load (GL) may promote overconsumption of energy and increase the risk of weight gain. Objective: The objective of the study was to investigate the relation between GI and GL of habitual diets and subsequent 6-y changes in body weight, body fat distribution, and body composition in a ran- dom

Helle Hare-Bruun; Anne Flint; Berit L Heitmann

413

Nd isotope composition and rare earth element distribution in early Paleozoic biogenic apatite from Baltoscandia: A signature of Iapetus ocean water  

Microsoft Academic Search

Analyses of the Nd isotopic composition and REE distribution in biogenic apatite (organophosphatic brachiopods and conodont elements) from the Cambrian and Ordovician sequences of the Baltic plate give new insights into the development of the southeastern segment of the continental margin bounding the Iapetus ocean. The Nd isotope analyses show ?Nd(t) of ˜-8.0 for the Cambrian, indicating that the main

Sergei Felitsyn; Ulf Sturesson; Leonid Popov; Lars Holmer

1998-01-01

414

Prediction of cloud condensation nucleus number concentration using measurements of aerosol size distributions and composition and light scattering enhancement due to humidity  

Microsoft Academic Search

A cloud condensation nucleus (CCN) closure experiment is carried out using data from the Chebogue Point, Nova Scotia, ground site during the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field experiment in 2004. The number concentration of CCN at five supersaturations (?0.07% to ?0.5%) is predicted from measurements of aerosol size distribution, composition, and hygroscopic growth and

Barbara Ervens; Michael Cubison; Elisabeth Andrews; Graham Feingold; John A. Ogren; Jose L. Jimenez; Peter DeCarlo; Athanasios Nenes

2007-01-01

415

Prediction of cloud condensation nucleus number concentration using measurements of aerosol size distributions and composition and light scattering enhancement due to humidity  

Microsoft Academic Search

A cloud condensation nucleus (CCN) closure experiment is carried out using data from the Chebogue Point, Nova Scotia, ground site during the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field experiment in 2004. The number concentration of CCN at five supersaturations (~0.07% to ~0.5%) is predicted from measurements of aerosol size distribution, composition, and hygroscopic growth and

Barbara Ervens; Michael Cubison; Elisabeth Andrews; Graham Feingold; John A. Ogren; Jose L. Jimenez; Peter DeCarlo; Athanasios Nenes

2007-01-01

416

A methodology to predict creep life for advanced ceramics using continuum damage mechanics  

Microsoft Academic Search

A methodology is proposed to estimate creep rupture life for advanced ceramics such as continuous fiber reinforced ceramic matrix composites (CFCMC). Based on the premise that the damage pattern takes the form of a heterogeneous distribution of grain boundary cavities in the majority of creep life, a damage parameter is incorporated in various creep strain rate equations. The resulting constitutive

T. J. Chuang; S. F. Duffy

1994-01-01

417

Effects of dendrite cell size and particle distribution on the near-threshold fatigue crack growth behavior of cast Al-SiCp composites  

SciTech Connect

Fatigue crack growth tests and crack closure measurements were performed for A356 cast aluminium alloys reinforced by 10 or 20% SiC particles and their matrix A356 alloys with systematically controlled dendrite cell size and particle distribution. The cell size dependence of the fatigue crack growth behavior in the composite was found to be quite similar to that of the matrix alloy. This suggests that the cell size rather than the particle-crack tip interaction is the most important factor to control the fatigue crack growth of the composites. Near threshold fatigue crack growth properties were improved in the composites with coarser cell size and inhomogeneous particle distribution due to the enhanced roughness induced crack closure effect. These results were compared to those of powder-metallurgically-processed materials.

Kumai, S.; Hu, J.; Higo, Y.; Nunomura, S. [Tokyo Inst. of Tech., Yokohama (Japan). Precision and Intelligence Lab.

1996-06-01

418

Life cycle of Pseudocalanus acuspes Giesbrecht (Copepoda, Calanoida) in the Central Baltic Sea: I. Seasonal and spatial distribution  

Microsoft Academic Search

The seasonal and spatial distribution of Pseudocalanus acuspes in the Bornholm Basin (Central Baltic Sea) was studied on 16 cruises between March 2002 and May 2003 from stratified (10 m)\\u000a multinet samples. The highest abundances were reached in May 2002 and April 2003 (618×103 and 869×103 ind. m?2, respectively). Ontogenetic vertical distribution was stage specific with differences of mean annual weighted mean depth

Jasmin Renz; Hans-Jürgen Hirche

2006-01-01

419

Distribution patterns of small-molecule ligands in the protein universe and implications for origin of life and drug discovery  

Microsoft Academic Search

BACKGROUND: Extant life depends greatly on the binding of small molecules (such as ligands) with macromolecules (such as proteins), and one ligand can bind multiple proteins. However, little is known about the global patterns of ligand-protein mapping. RESULTS: By examining 2,186 well-defined small-molecule ligands and thousands of protein domains derived from a database of druggable binding sites, we show that

Hong-Fang Ji; De-Xin Kong; Liang Shen; Ling-Ling Chen; Bin-Guang Ma; Hong-Yu Zhang

2007-01-01

420

Life cycle monitoring of large-scale CFRP VARTM structure by fiber-optic-based distributed sensing  

Microsoft Academic Search

This study demonstrated fiber-optic-based life cycle monitoring of a representative carbon fiber reinforced plastic (CFRP) stiffened panel manufactured by vacuum assisted resin transfer molding (VARTM). A single optical fiber was embedded between the stiffeners and the skin during the laminate lay-up process and the formed fiber-optic network was then utilized to monitor the manufacturing process and subsequent impact tests. A

Shu Minakuchi; Nobuo Takeda; Shin-ichi Takeda; Yosuke Nagao; Alessandro Franceschetti; Xiaolin Liu

2011-01-01

421

Exposure to undernutrition in fetal life determines fat distribution, locomotor activity and food intake in ageing rats  

Microsoft Academic Search

Objective:To assess the long-term impact of undernutrition during specific periods of fetal life, upon central adiposity, control of feeding behaviour and locomotor activity.Design:Pregnant rats were fed a control or low-protein (LP) diet, targeted to early (LPE), mid (LPM) or late (LPL) pregnancy or throughout gestation (LPA). The offspring were studied at 9 and 18 months of age.Measurements:Adiposity was assessed by

L Bellinger; D V Sculley; S C Langley-Evans

2006-01-01

422

Ion acceleration in Ar-Xe and Ar-He plasmas. I. Electron energy distribution functions and ion composition  

SciTech Connect

Electron energy distribution functions (eedf), ion production, and ion composition are studied in Ar-Xe and Ar-He expanding helicon plasmas. It was found that under the conditions of constant total flow rate, Xe, in addition to Ar, changes the eedf from Maxwellian-like to Druyvesteyn-like with a shortening of the high energy tail at {approx}15 eV. The electron temperature exponentially decreases from {approx}7 eV in pure Ar plasma to {approx}4 eV in pure Xe plasma. Xenon ions dominate the ion population for Xe filling fractions greater than 10%. The plasma density increases by {approx}15% with increasing Xe fraction. For an Ar-He plasma, increasing the helium fraction increases the electron temperature from {approx}7 eV in pure Ar plasma to {approx}14 eV for a He filling fraction of 80%. The plasma density drops by more than three orders of magnitude from 1.14x10{sup 11} cm{sup -3} to 6.5x10{sup 7} cm{sup -3}. However, the inferred ion densities indicate that even at a helium fraction of 80%, argon ions significantly outnumber helium ions.

Biloiu, Ioana A.; Scime, Earl E. [Department of Physics, West Virginia University, Morganton, West Virginia 26506 (United States)

2010-11-15

423

Seasonal trends in the social composition and inside-trunk distribution of Kalotermes flavicollis (Isoptera: Kalotermitidae) colonizing grapevines.  

PubMed

The polyphagous drywood termite Kalotermes flavicollis (Fabricius) can establish its colonies inside living trees, causing a progressive debilitation that ends with the death of the plant. For this reason, it is considered one of the major pests of Sherry vineyards in Andalusia, SW Spain. To analyze the trends of colonization of this termite, a detailed investigation was performed during 16 mo in seven districts of the Sherry area, cutting randomly selected grapevine trunks into six sections, from which all individuals were collected and counted according to their developmental instar or caste. The results detected variations in the social composition of the groups colonizing grapevines according to the spatial distribution inside the vine trunk and in the numerical trends over the seasons. A pattern of seasonal migrations of the termites inside the trunk was inferred, with upward movements from spring to autumn and downward movements from autumn to winter. During winter, when termites were mainly located in the medium-basal sections of the trunk, a higher proportion of eggs and larvae was detected. Going from spring to summer, when the majority of the termites was located in the medium-upper sections of the trunk, there was an increase of nymphal instars followed, during autumn, by the appearance of alates, mostly located in the upper sections of the grapevine. Pseudergates and reproductives maintained their proportions and locations almost unchanged during the year. PMID:20388256

Maistrello, Lara; Ocete, Rafael; López, M Angeles

2010-04-01

424

LDL composition in E2/2 subjects and LDL distribution by Apo E genotype in type 1 diabetes  

PubMed Central

Apo E plays an important role in chylomicron and VLDL remnant processing, uptake or conversion to LDL. The type of lipoprotein that isolates in the LDL density of E2/2 subjects was investigated and the effect of the apo E isoforms on LDL mass was determined in all genotypes in a large group of Type 1 diabetics. Analysis of the LDL composition of E2/2 homozygotes (n = 6) compared to subjects with the common E3/3 isoform (n = 6) demonstrated an enrichment in apo E, unesterified cholesterol, phospholipid and triglyceride relative to apo B in E2/2 subjects, more typical of a dense IDL remnant than of LDL. Although diabetics were studied, these findings are considered to reflect those of the general population. Comparison of the lipoprotein distribution of homozygous and heterozygous subjects revealed that, as genotype changed from E4/4 (n = 22) to E3/4 (n = 262), E3/3 (n = 710) = E2/4 (n = 30), E2/3 (n = 151), E2/2 (n = 6), LDL cholesterol decreased significantly in a stepwise manner. The decrease was not in a specific subgroup of LDL. In conclusion, for E2/2 subjects, lipoproteins isolated in the LDL density range appear to be composed mainly of dense IDL remnants and some Lp(a). The apo E isoform also has a significant effect on LDL concentration in both homozygotes and heterozygotes.

Murdoch, Susan J.; Boright, Andrew P.; Paterson, Andrew D.; Zinman, Bernard; Steffes, Michael; Cleary, Patricia; Edwards, Karen; Marcovina, Santica S.; Purnell, Jonathan Q.; Brunzell, John D.

2009-01-01

425

Effect of the pulse repetition rate on the composition and ion charge-state distribution of pulsed vacuum arcs  

SciTech Connect

The plasma composition and ion charge-state distributions of pulsed vacuum arcs have been investigated for carbon, aluminum, silver, platinum, and tantalum cathodes using a time-of-flight (TOF) charge-to-mass spectrometer. With the exception of carbon, it was found that all results depend on the arc pulse repetition rate, a fact which, up to now, has not been reported in the literature. It is shown that adsorption of gas on the cathode between arc pulses leads to contamination of the metal plasma and to a reduction of metal ion charge states. These usually undesired effects can be avoided by operating at high arc pulse repetition rates of order 10 Hz or more. The results can be interpreted in terms of cathode spot type 1 (on contaminated cathode surfaces) and type 2 (on clean surfaces) which are well known from their different brightness and erosion behavior. The transition between the modes was found to be gradual. Fully ionized metal plasmas can be produced at vacuum arc cathode spots. They are used, for instance, in vacuum arc ion sources for ion implantation and ion injection into accelerators. Vacuum arc metal plasmas are also used for thin film deposition and the plasma synthesis of highly adhesive metal or compound films by metal plasma immersion ion implantation and deposition.

Yushkov, G.Y. [Russian Academy of Sciences, Tomsk (Russian Federation). High Current Electronics Inst.; Anders, A. [Lawrence Berkeley National Lab., CA (United States)

1998-04-01

426

Assessing community-level and single-species models predictions of species distributions and assemblage composition after 25 years of land cover change.  

PubMed

To predict the impact of environmental change on species distributions, it has been hypothesized that community-level models could give some benefits compared to species-level models. In this study we have assessed the performance of these two approaches. We surveyed 256 bird communities in an agricultural landscape in southwest France at the same locations in 1982 and 2007. We compared the ability of CQO (canonical quadratic ordination; a method of community-level GLM) and GLMs (generalized linear models) to i) explain species distributions in 1982 and ii) predict species distributions, community composition and species richness in 2007, after land cover change. Our results show that models accounting for shared patterns between species (CQO) slightly better explain the distribution of rare species than models that ignore them (GLMs). Conversely, the predictive performances were better for GLMs than for CQO. At the assemblage level, both CQO and GLMs overestimated species richness, compared with that actually observed in 2007, and projected community composition was only moderately similar to that observed in 2007. Species richness projections tended to be more accurate in sites where land cover change was more marked. In contrast, the composition projections tended to be less accurate in those sites. Both modelling approaches showed a similar but limited ability to predict species distribution and assemblage composition under conditions of land cover change. Our study supports the idea that our community-level model can improve understanding of rare species patterns but that species-level models can provide slightly more accurate predictions of species distributions. At the community level, the similar performance of both approaches for predicting patterns of assemblage variation suggests that species tend to respond individualistically or, alternatively, that our community model was unable to effectively account for the emergent community patterns. PMID:23349818

Bonthoux, Sébastien; Baselga, Andrés; Balent, Gérard

2013-01-17

427

A geochemical modelling study of the evolution of the chemical composition of seawater linked to a global glaciation: implications for life sustainability  

NASA Astrophysics Data System (ADS)

The Snowball Earth theory initially proposed by Kirschvink (Kirschvink, 1992) to explain the Neoproterozoic glacial episodes, suggested that the Earth was fully ice-covered at 720 My (Sturtian episode) and 640 My (Marinoan episode). This succession of extreme climatic crises induced a stress which is considered as a strong selective pressure on the evolution of life (Hoffman et al., 1998). However recent biological records (Corsetti, 2006) do not support this theory as little change is observed in the diversity of microfossils outcrops before and after the Marinoan glacial interval. In this contribution we address this apparent paradox. Using a numerical model of carbon-alkalinity global cycles, we quantify several environmental stresses caused by a global glaciation. We suggest that during global glaciations, the ocean becomes acidic (pH~6), and unsaturated with respect to carbonate minerals. Moreover the quick transition from ice-house to greenhouse conditions implies an abrupt and large shift of the oceanic surface temperature which causes an extended hypoxia. The intense continental weathering, in the aftermath of the glaciation, deeply affects the seawater composition inducing rapid changes in terms of pH and alkalinity. We also propose a new timing for post glacial perturbations and for the cap carbonates deposition, ~2 Myr instead of 200 kyr as suggested in a previous modelling study. In terms of Precambrian life sustainability, seawater pH modifications appear drastic all along the glaciation, but we show that the buffering action of the oceanic crust dissolution processes avoids a total collapse of biological productivity. In opposite short-lived and large post-glacial perturbations are more critical and may have played a role of environmental filter suggested in the classic snowball Earth theory. Only a permissive life (prokaryotes or simple eukaryotes) may explain the relative continuity in microfossils diversity observed before, during and after Neoproterozoic glaciation events.

Le Hir, G.; Goddéris, Y.; Donnadieu, Y.; Ramstein, G.

2007-06-01

428

Early life ecology of Alaska plaice ( Pleuronectes quadrituberculatus) in the eastern Bering Sea: Seasonality, distribution, and dispersal  

Microsoft Academic Search

We examined the patterns of abundance and distribution of Alaska plaice, Pleuronectes quadrituberculatus, eggs, larvae and pelagic juveniles over the southeastern Bering Sea shelf to better understand factors controlling transport and recruitment of flatfish in the Bering Sea. Ichthyoplankton data were derived from plankton surveys conducted in 1997, 1999, 2002, 2003, and 2005. Temperature, salinity, depth, and abundance of microzooplankton

Janet T. Duffy-Anderson; Miriam J. Doyle; Kathryn L. Mier; Phyllis J. Stabeno; Thomas K. Wilderbuer

2010-01-01

429

Low-cycle fatigue life prediction of spot welds based on hardness distribution and finite element analysis  

Microsoft Academic Search

Elasto-plastic finite element analysis was carried out for single spot tensile shear spot welds with software ANSYS. According to the relationship between micro-hardness and strength, cyclic material constants of different zones in the periphery of spot welds were determined in accordance with hardness distribution, as well as base material fatigue parameters. Using the local stress and strain obtained from finite

Rui-Jie Wang; De-Guang Shang

2009-01-01

430

Understanding evolution of product composition and volatility distribution through in situ GC × GC analysis: a case study of longifolene ozonolysis  

NASA Astrophysics Data System (ADS)

A method for predicting volatility and polarity based on chromatographic information was developed and applied to the smog chamber ozonolysis of the sesquiterpene longifolene. The products were collected and analyzed using a GC × GC Thermal Desorption Aerosol Gas Chromatograph/Mass Spectrometer (2D-TAG) and a quadrupole Aerodyne Aerosol Mass Spectrometer (AMS). All the secondary organic aerosol (SOA) was produced within the first half hour of the experiment. However, the oxidation level of the organic aerosol, as inferred from the fraction of ion m/z 44, suggested continued evolution of the SOA over the subsequent hours. Measurements of speciated organic compounds using 2D-TAG confirm that the composition of the particles changed over the course of the experiment. Nearly 200 oxidation products (thought to be mostly ketones and acids) were observed with 2D-TAG, but most could not be identified definitively due to a lack of standards and the absence of likely sesquiterpene oxidation products in available mass spectral databases. To categorize the observed products, the vapor pressure and oxygen-to-carbon ratio (O/C) of observed compounds were estimated based on their multi-dimensional chromatographic retention times relative to those of known standards, establishing a retention time correlation (RTC) method for using 2D-TAG to better constrain important modelling parameters. The product distribution continuously evolved in volatility and oxygenation during 5 h of oxidation. Using peak area as the best available proxy for mass, we conclude that the product mixture includes many non-negligible products; the most abundant 3 compounds accounted for only half of the total observed peak area and 80% of peak area was spread across 15 compounds. The data provide evidence for three conclusions: (1) 2D-TAG can provide valuable volatility and oxygenation information even in the absence of definitive species identification, (2) complex particle-phase chemistry causes continued evolution of particle composition after formation of new particles was complete, and (3) minor products contribute significantly to SOA from the ozonolysis of sesquiterpenes.

Isaacman, G.; Worton, D. R.; Kreisberg, N. M.; Hennigan, C. J.; Teng, A. P.; Hering, S. V.; Robinson, A. L.; Donahue, N. M.; Goldstein, A. H.

2011-01-01

431

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

NASA Astrophysics Data System (ADS)

The zooxanthellate mangrove jellyfish Cassiopea sp. represents a prominent invasive species and a potential bioindicator for nutrient monitoring in coral reefs. However, information about its spatial distribution in combination with abundance, habitat specificity and life cycle elements is barely available. This study, therefore, presents the results of field surveys conducted within four different benthic habitat types (coral reef, seagrass meadow, reef-sand transition and sand flat) in the Northern Red Sea. Cassiopea sp. exhibited a highly patchy distribution within the entire study area with mean abundance of 1.6 ± 0.3 animals m-2 and benthic coverage of 3.2%. Within coral reef habitats, maximum abundance of up to 31 animals m-2 and benthic coverage of up to 20% were detected. Additionally, this study revealed that 65% of all observed Cassiopea specimens were associated with the commensalistic crustacean mysid Idiomysis tsurnamali. Cassiopea abundance and size as well as association patterns with mysids differed between most of the surveyed habitats. In summary, the findings of the present study (1) characterize Cassiopea as one of the key organisms in investigated benthic habitats, (2) indicate active habitat selection by the jellyfish and (3) may hint to an unexplored life cycle of Cassiopea with central role of seagrass meadows providing cues for larval settlement and metamorphosis in the absence of mangroves.

Niggl, Wolfgang; Wild, Christian

2010-12-01

432

DataONE: A Distributed Environmental and Earth Science Data Network Supporting the Full Data Life Cycle  

NASA Astrophysics Data System (ADS)

Addressing grand environmental science challenges requires unprecedented access to easily understood data that cross the breadth of temporal, spatial, and thematic scales. Tools are needed to plan management of the data, discover the relevant data, integrate heterogeneous and diverse data, and convert the data to information and knowledge. Addressing these challenges requires new approaches for the full data life cycle of managing, preserving, sharing, and analyzing data. DataONE (Observation Network for Earth) represents a virtual organization that enables new science and knowledge creation through preservation and access to data about life on Earth and the environment that sustains it. The DataONE approach is to improve data collection and management techniques; facilitate easy, secure, and persistent storage of data; continue to increase access to data and tools that improve data interoperability; disseminate integrated and user-friendly tools for data discovery and novel analyses; work with researchers to build intuitive data exploration and visualization tools; and support communities of practice via education, outreach, and stakeholder engagement.

Cook, R.; Michener, W.; Vieglais, D.; Budden, A.; Koskela, R.

2012-04-01

433

Environmental drivers of megafaunal assemblage composition and biomass distribution over mainland and insular slopes of the Balearic Basin (Western Mediterranean)  

NASA Astrophysics Data System (ADS)

The influence of mesoscale physical and trophic variables on deep-sea megafauna, a scale of variation often neglected in deep-sea studies, is crucial for understanding their role in the ecosystem. Drivers of megafaunal assemblage composition and biomass distribution have been investigated in two contrasting areas of the Balearic basin in the NW Mediterranean: on the mainland slope (Catalonian coasts) and on the insular slope (North of Mallorca, Balearic Islands). An experimental bottom trawl survey was carried out during summer 2010, at stations in both sub-areas located between 450 and 2200 m water depth. Environmental data were collected simultaneously: near-bottom physical parameters, and the elemental and isotopic composition of sediments. Initially, data were analysed along the whole depth gradient, and then assemblages from the two areas were compared. Analysis of the trawls showed the existence of one group associated with the upper slope (US=450-690 m), another with the middle slope (MS=1000-1300 m) and a third with the lower slope (LS=1400-2200 m). Also, significant differences in the assemblage composition were found between mainland and insular slopes at MS. Dominance by different species was evident when the two areas were compared by SIMPER analysis. The greatest fish biomass was recorded in both areas at 1000-1300 m, a zone linked to minimum temperature and maximum O2 concentration on the bottom. Near the mainland, fish assemblages were best explained (43% of total variance, DISTLM analysis) by prey availability (gelatinous zooplankton biomass). On the insular slope, trophic webs seemed less complex and were based on vertical input of surface primary production. Decapods, which reached their highest biomass values on the upper slope, were correlated with salinity and temperature in both the areas. However, while hydrographic conditions (temperature and salinity) seemed to be the most important variables over the insular slope, resource availability (gelatinous zooplankton and Calocaris macandreae) predominated and explained 59% of decapod assemblage variation over the mainland slope. Both fish and decapods were linked to net primary production recorded over the mainland 3 months before sampling, while the delay between the input of food from the surface and fish abundance was only 1 month on the insular slope. Our results suggest that trophic relationships over insular slopes probably involve a shorter food chain than over mainland slopes and one that is likely more efficient in terms of energy transfer. HighlightsDeep assemblages differ at bathymetric and geographical (mainland vs. insular) scale.Species diversity is greater over mainland than on insular slope.Different environmental and trophic variables drive the observed patterns.Over the insular slope, benthopelagic species are more connected to vertical flux.Assemblages exploit both vertical and lateral advective inputs on the mainland slope.

Fanelli, E.; Cartes, J. E.; Papiol, V.; López-Pérez, C.

2013-08-01

434

Abundance, depth distribution, and composition of aerobic bacteriochlorophyll a-producing bacteria in four basins of the central Baltic Sea.  

PubMed

The abundance, vertical distribution, and diversity of aerobic anoxygenic phototrophic bacteria (AAP) were studied at four basins of the Baltic Sea. AAP were enumerated by infrared epifluorescence microscopy, and their diversity was analyzed by using pufM gene clone libraries. In addition, numbers of CFU containing the pufM gene were determined, and representative strains were isolated. Both approaches indicated that AAP reached maximal abundance in the euphotic zone. Maximal AAP abundance was 2.5 x 10(5) cells ml(-1) (11% of total prokaryotes) or 1.0 x 10(3) CFU ml(-1) (9 to 10% of total CFU). Environmental pufM clone sequences were grouped into 11 operational taxonomic units phylogenetically related to cultivated members of the Alpha-, Beta-, and Gammaproteobacteria. In spite of varying pufM compositions, five clones were present in all libraries. Of these, Jannaschia-related clones were always found in relative abundances representing 25 to 30% of the total AAP clones. The abundances of the other clones varied. Clones potentially affiliated with typical freshwater Betaproteobacteria sequences were present at three Baltic Sea stations, whereas clones grouping with Loktanella represented 40% of the total cell numbers in the Gotland Basin. For three alphaproteobacterial clones, probable pufM phylogenetic relationships were supported by 16S rRNA gene analyses of Baltic AAP isolates, which showed nearly identical pufM sequences. Our data indicate that the studied AAP assemblages represented a mixture of marine and freshwater taxa, thus characterizing the Baltic Sea as a "melting pot" of abundant, polyphyletic aerobic photoheterotrophic bacteria. PMID:18502937

Salka, Ivette; Moulisová, Vladimíra; Koblízek, Michal; Jost, Günter; Jürgens, Klaus; Labrenz, Matthias

2008-05-23

435

Fatigue failure of composite bolted joints  

SciTech Connect

The effects of a number of parameters on the fatigue characteristics of a bolted graphite/epoxy composite laminate are investigated. In particular, tests were performed in order to study the influence of three independent parameters; applied stress level, orientation of the outer layer reinforcing filaments, and the bolt torque level on the fatigue life of a graphite/epoxy composite. Analysis of variance and censoring techniques were used to analyze the experimentally obtained data. Fatigue life data was determined to be adequately characterized by using a log-normal distribution. 29 refs.

Herrington, P.D.; Sabbaghian, M. (New Orleans Univ., LA (United States) Louisiana State Univ., Baton Rouge (United States))

1993-01-01

436

Race, Socioeconomic Resources, and Late-Life Mobility and Decline: Findings From the Health, Aging, and Body Composition Study  

PubMed Central

Background. This study examines the relationship between race and mobility over 5 years in initially well-functioning older adults and evaluates how a broad set of socioeconomic status indicators affect this relationship. Methods. Data were from 2,969 black and white participants aged 70–79 from the Health, Aging, and Body Composition study. Mobility parameters included self-reported capacity to walk a quarter mile and climb 10 steps and usual gait speed. Incident mobility limitation was defined as reported difficulty walking a quarter mile or climbing 10 steps at two consecutive semiannual assessments. Gait speed decline was defined as a 4% reduction in speed per year. Results. At baseline, even though all participants were free of mobility limitation, blacks had slower walking speed than their white counterparts, which was not explained by poverty, education, reading level, or income adequacy. After 5 years, accounting for age, site, and baseline mobility, blacks were more likely to develop mobility limitation than whites. Adjusting for prevalent conditions at baseline eliminated this difference in women; controlling for education eliminated this difference in men. No differences in gait speed decline were identified. Conclusions. Higher rates of mobility loss observed in older blacks relative to older whites appear to be a function of both poorer initial mobility status and existing health conditions particularly for women. Education may also play a role especially for men.

Koster, Annemarie; Kritchevsky, Stephen B.; Newman, Anne B.; Harris, Tamara; Ayonayon, Hilsa N.; Perry, Sara; Rooks, Ronica N.; Simonsick, Eleanor M.

2011-01-01

437

The distribution of life cycle stages of two deep-water pleuronectids, Dover sole ( Microstomus pacificus) and rex sole ( Glyptocephalus zachirus), at the northern extent of their range in the Gulf of Alaska  

Microsoft Academic Search

Dover sole (Microstomus pacificus) and rex sole (Glyptocephalus zachirus) are both commercially valuable, long-lived pleuronectids that are distributed widely throughout the North Pacific. While their ecology and life cycle have been described for southern stocks, few investigations have focused on these species at higher latitudes. We synthesized historical research survey data among critical developmental stages to determine the distribution of

Alisa A. Abookire; Kevin M. Bailey

2007-01-01

438

Distribution and determinants of patient satisfaction in oncology with a focus on health related quality of life  

PubMed Central

Background Cancer patients usually undergo extensive and debilitating treatments, which make quality of life (QoL) and patient satisfaction important health care assessment measures. However, very few studies have evaluated the relationship between QoL and patient satisfaction in oncology. We investigated the clinical, demographic and QoL factors associated with patient satisfaction in a large heterogeneous sample of cancer patients. Methods A cohort of 538 cancer patients treated at Cancer Treatment Centers of America® (CTCA) was assessed. A patient satisfaction questionnaire developed in-house by CTCA was used. It covered the following dimensions of patient satisfaction: hospital operations and services, physicians and staff, and patient endorsements for themselves and others. QoL was assessed using the European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire (QLQ-C30). The clinical, demographic and QoL factors were evaluated for predictive significance using univariate and multivariate logistic regression. Results The mean age of our patient population was 54.1 years (SD = 10.5, range 17-86), with a slight preponderance of females (57.2%). Breast cancer (n = 124) and lung cancer (n = 101) were the most frequent cancer types. 481 (89.4%) patients were "very satisfied" with their overall experience. Age and several QoL function and symptom scales were predictive of overall patient satisfaction upon univariate analysis. In the multivariate modeling, only those with a score above the median on the fatigue measure (i.e. worse fatigue) had reduced odds of 0.28 of being very satisfied (p = 0.03). Conclusion Patient fatigue, as reported by the QoL fatigue scale, was an independent significant predictor of overall patient satisfaction. This finding argues for special attention and programs for cancer patients who report higher levels of fatigue given that fatigue is the most frequently reported symptom in cancer patients.

Lis, Christopher G; Rodeghier, Mark; Grutsch, James F; Gupta, Digant

2009-01-01

439

Mass composition of 1017- to 1018-eV primary cosmic rays according to data on the lateral distribution of radio emission from extensive air showers  

NASA Astrophysics Data System (ADS)

Experimental data obtained for the lateral distribution of radio emission from extensive air showers (EAS) at the array of Moscow State University (30-34 MHz) and the LOPES array (40-80 MHz) were comparedwith the results of calculations performed within amicroscopic approach based on aMonte Carlo simulation of EAS (CORSIKA code). The same experimental data were used to reconstruct the distribution of the depth of the EAS maximum at cosmic-ray energies in the range of 1017-1018 eV. The energy dependence of the depth of the EAS maximum was constructed for the case of data from the LOPES array, and the mass composition of cosmic rays was estimated for this case. From the resulting dependences, it follows that the mass composition shows a trend toward becoming lighter in the energy range being considered

Kalmykov, N. N.; Konstantinov, A. A.; Vedeneev, O. V.

2012-12-01

440

African genetic admixture is associated with body composition and fat distribution in a cross-sectional study of children  

Microsoft Academic Search

Objective:Although differences in body composition parameters among African American (AA), Hispanic American (HA) and European American (EA) children are well documented, the factors underlying these differences are not completely understood. Environmental and genetic contributors have been evaluated as contributors to observed differences. This study evaluated the extent to which African or European ancestral genetic background influenced body composition and fat

M Cardel; P B Higgins; A L Willig; A D Keita; K Casazza; B A Gower; J R Fernández; JR Fernández

2011-01-01