Modeling Equity for Alternative Water Rate Structures

Science.gov (United States)

Griffin, R.; Mjelde, J.

2011-12-01

The rising popularity of increasing block rates for urban water runs counter to mainstream economic recommendations, yet decision makers in rate design forums are attracted to the notion of higher prices for larger users. Among economists, it is widely appreciated that uniform rates have stronger efficiency properties than increasing block rates, especially when volumetric prices incorporate intrinsic water value. Yet, except for regions where water market purchases have forced urban authorities to include water value in water rates, economic arguments have weakly penetrated policy. In this presentation, recent evidence will be reviewed regarding long term trends in urban rate structures while observing economic principles pertaining to these choices. The main objective is to investigate the equity of increasing block rates as contrasted to uniform rates for a representative city. Using data from four Texas cities, household water demand is established as a function of marginal price, income, weather, number of residents, and property characteristics. Two alternative rate proposals are designed on the basis of recent experiences for both water and wastewater rates. After specifying a reasonable number (~200) of diverse households populating the city and parameterizing each household's characteristics, every household's consumption selections are simulated for twelve months. This procedure is repeated for both rate systems. Monthly water and wastewater bills are also computed for each household. Most importantly, while balancing the budget of the city utility we compute the effect of switching rate structures on the welfares of households of differing types. Some of the empirical findings are as follows. Under conditions of absent water scarcity, households of opposing characters such as low versus high income do not have strong preferences regarding rate structure selection. This changes as water scarcity rises and as water's opportunity costs are allowed to

Structural determinants of phenotypic diversity and replication rate of human prions.

Directory of Open Access Journals (Sweden)

Jiri G Safar

2015-04-01

Full Text Available The infectious pathogen responsible for prion diseases is the misfolded, aggregated form of the prion protein, PrPSc. In contrast to recent progress in studies of laboratory rodent-adapted prions, current understanding of the molecular basis of human prion diseases and, especially, their vast phenotypic diversity is very limited. Here, we have purified proteinase resistant PrPSc aggregates from two major phenotypes of sporadic Creutzfeldt-Jakob disease (sCJD, determined their conformational stability and replication tempo in vitro, as well as characterized structural organization using recently emerged approaches based on hydrogen/deuterium (H/D exchange coupled with mass spectrometry. Our data clearly demonstrate that these phenotypically distant prions differ in a major way with regard to their structural organization, both at the level of the polypeptide backbone (as indicated by backbone amide H/D exchange data as well as the quaternary packing arrangements (as indicated by H/D exchange kinetics for histidine side chains. Furthermore, these data indicate that, in contrast to previous observations on yeast and some murine prion strains, the replication rate of sCJD prions is primarily determined not by conformational stability but by specific structural features that control the growth rate of prion protein aggregates.

Investigation of the fluid flow dynamic parameters for Newtonian and non-Newtonian materials: an approach to understanding the fluid flow-like structures within fault zones

Science.gov (United States)

Tanaka, H.; Shiomi, Y.; Ma, K.-F.

2017-11-01

To understand the fault zone fluid flow-like structure, namely the ductile deformation structure, often observed in the geological field (e.g., Ramsay and Huber The techniques of modern structure geology, vol. 1: strain analysis, Academia Press, London, 1983; Hobbs and Ord Structure geology: the mechanics of deforming metamorphic rocks, Vol. I: principles, Elsevier, Amsterdam, 2015), we applied a theoretical approach to estimate the rate of deformation, the shear stress and the time to form a streak-line pattern in the boundary layer of viscous fluids. We model the dynamics of streak lines in laminar boundary layers for Newtonian and pseudoplastic fluids and compare the results to those obtained via laboratory experiments. The structure of deformed streak lines obtained using our model is consistent with experimental observations, indicating that our model is appropriate for understanding the shear rate, flow time and shear stress based on the profile of deformed streak lines in the boundary layer in Newtonian and pseudoplastic viscous materials. This study improves our understanding of the transportation processes in fluids and of the transformation processes in fluid-like materials. Further application of this model could facilitate understanding the shear stress and time history of the fluid flow-like structure of fault zones observed in the field.[Figure not available: see fulltext.

The rate-size trade-off structures intraspecific variation in Daphnia ambigua life history parameters.

Science.gov (United States)

DeLong, John P; Hanley, Torrance C

2013-01-01

The identification of trade-offs is necessary for understanding the evolution and maintenance of diversity. Here we employ the supply-demand (SD) body size optimization model to predict a trade-off between asymptotic body size and growth rate. We use the SD model to quantitatively predict the slope of the relationship between asymptotic body size and growth rate under high and low food regimes and then test the predictions against observations for Daphnia ambigua. Close quantitative agreement between observed and predicted slopes at both food levels lends support to the model and confirms that a 'rate-size' trade-off structures life history variation in this population. In contrast to classic life history expectations, growth and reproduction were positively correlated after controlling for the rate-size trade-off. We included 12 Daphnia clones in our study, but clone identity explained only some of the variation in life history traits. We also tested the hypothesis that growth rate would be positively related to intergenic spacer length (i.e. the growth rate hypothesis) across clones, but we found that clones with intermediate intergenic spacer lengths had larger asymptotic sizes and slower growth rates. Our results strongly support a resource-based optimization of body size following the SD model. Furthermore, because some resource allocation decisions necessarily precede others, understanding interdependent life history traits may require a more nested approach.

The rate-size trade-off structures intraspecific variation in Daphnia ambigua life history parameters.

Directory of Open Access Journals (Sweden)

John P DeLong

Full Text Available The identification of trade-offs is necessary for understanding the evolution and maintenance of diversity. Here we employ the supply-demand (SD body size optimization model to predict a trade-off between asymptotic body size and growth rate. We use the SD model to quantitatively predict the slope of the relationship between asymptotic body size and growth rate under high and low food regimes and then test the predictions against observations for Daphnia ambigua. Close quantitative agreement between observed and predicted slopes at both food levels lends support to the model and confirms that a 'rate-size' trade-off structures life history variation in this population. In contrast to classic life history expectations, growth and reproduction were positively correlated after controlling for the rate-size trade-off. We included 12 Daphnia clones in our study, but clone identity explained only some of the variation in life history traits. We also tested the hypothesis that growth rate would be positively related to intergenic spacer length (i.e. the growth rate hypothesis across clones, but we found that clones with intermediate intergenic spacer lengths had larger asymptotic sizes and slower growth rates. Our results strongly support a resource-based optimization of body size following the SD model. Furthermore, because some resource allocation decisions necessarily precede others, understanding interdependent life history traits may require a more nested approach.

An Insight towards Conceptual Understanding: Looking into the Molecular Structures of Compounds

Science.gov (United States)

Uyulgan, Melis Arzu; Akkuzu, Nalan

2016-01-01

The subject of molecular structures is one of the most important and complex subject in chemistry which a majority of the undergraduate students have difficulties to understand its concepts and characteristics correctly. To comprehend the molecular structures and their characteristics the students need to understand related subjects such as Lewis…

Development of children’s early understanding of numeric structure

Directory of Open Access Journals (Sweden)

Vasilyeva, Marina

2016-09-01

Full Text Available Understanding of the base-10 structure of multi-digit numbers is one of the critical aspects in early mathematics learning. It has been documented that children from different countries vary in their use of base-10 representations. Questions concerning potential sources of this variability have been debated for decades. One commonly posited explanation is that some languages provide explicit cues about the structure of multi-digit numbers, facilitating the development of base-10 representations. In the present study, we tested this view against an alternative view, positing that variability in children’s learning of numeric structure may reflect differences in their experiences with numbers. The study examined kindergartners and first-graders from four countries: Taiwan, South Korea, the USA, and Russia. Results showed that the use of base-10 representations by American first-graders increased dramatically over the last decades, following changes in curricular guidelines. First-graders across the four countries showed some differences in performance (however, not consistent with the language account, whereas kindergartners performed comparably despite the differences in their languages. The results suggest that the nature of early math instruction may be critical for children’s developing understanding of numeric structure.

Effects of Structural Transparency in System Dynamics Simulators on Performance and Understanding

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Birgit Kopainsky

2015-10-01

Full Text Available Prior exploration is an instructional strategy that has improved performance and understanding in system-dynamics-based simulators, but only to a limited degree. This study investigates whether model transparency, that is, showing users the internal structure of models, can extend the prior exploration strategy and improve learning even more. In an experimental study, participants in a web-based simulation learned about and managed a small developing nation. All participants were provided the prior exploration strategy but only half received prior exploration embedded in a structure-behavior diagram intended to make the underlying model’s structure more transparent. Participants provided with the more transparent strategy demonstrated better understanding of the underlying model. Their performance, however, was the equivalent to those in the less transparent condition. Combined with previous studies, our results suggest that while prior exploration is a beneficial strategy for both performance and understanding, making the model structure transparent with structure-behavior diagrams is more limited in its effect.

Tools to Understand Structural Property Relationships for Wood Cell Walls

Science.gov (United States)

Joseph E. Jakes; Daniel J. Yelle; Charles R. Frihart

2011-01-01

Understanding structure-property relationships for wood cell walls has been hindered by the complex polymeric structures comprising these cell walls and the difficulty in assessing meaningful mechanical property measurements of individual cell walls. To help overcome these hindrances, we have developed two experimental methods: 1) two-dimensional solution state nuclear...

Evolutionary rate variation and RNA secondary structure prediction

DEFF Research Database (Denmark)

Knudsen, B.; Andersen, E.S.; Damgaard, C.

2004-01-01

Predicting RNA secondary structure using evolutionary history can be carried out by using an alignment of related RNA sequences with conserved structure. Accurately determining evolutionary substitution rates for base pairs and single stranded nucleotides is a concern for methods based on this type...... by applying rates derived from tRNA and rRNA to the prediction of the much more rapidly evolving 5'-region of HIV-1. We find that the HIV-1 prediction is in agreement with experimental data, even though the relative evolutionary rate between A and G is significantly increased, both in stem and loop regions...

Advanced understanding on electronic structure of molecular semiconductors and their interfaces

Science.gov (United States)

Akaike, Kouki

2018-03-01

Understanding the electronic structure of organic semiconductors and their interfaces is critical to optimizing functionalities for electronics applications, by rational chemical design and appropriate combination of device constituents. The unique electronic structure of a molecular solid is characterized as (i) anisotropic electrostatic fields that originate from molecular quadrupoles, (ii) interfacial energy-level lineup governed by simple electrostatics, and (iii) weak intermolecular interactions that make not only structural order but also energy distributions of the frontier orbitals sensitive to atmosphere and interface growth. This article shows an overview on these features with reference to the improved understanding of the orientation-dependent electronic structure, comprehensive mechanisms of molecular doping, and energy-level alignment. Furthermore, the engineering of ionization energy by the control of the electrostatic fields and work function of practical electrodes by contact-induced doping is briefly described for the purpose of highlighting how the electronic structure impacts the performance of organic devices.

Reactive Molecular Dynamics Simulations to Understand Mechanical Response of Thaumasite under Temperature and Strain Rate Effects.

Science.gov (United States)

Hajilar, Shahin; Shafei, Behrouz; Cheng, Tao; Jaramillo-Botero, Andres

2017-06-22

Understanding the structural, thermal, and mechanical properties of thaumasite is of great interest to the cement industry, mainly because it is the phase responsible for the aging and deterioration of civil infrastructures made of cementitious materials attacked by external sources of sulfate. Despite the importance, effects of temperature and strain rate on the mechanical response of thaumasite had remained unexplored prior to the current study, in which the mechanical properties of thaumasite are fully characterized using the reactive molecular dynamics (RMD) method. With employing a first-principles based reactive force field, the RMD simulations enable the description of bond dissociation and formation under realistic conditions. From the stress-strain curves of thaumasite generated in the x, y, and z directions, the tensile strength, Young's modulus, and fracture strain are determined for the three orthogonal directions. During the course of each simulation, the chemical bonds undergoing tensile deformations are monitored to reveal the bonds responsible for the mechanical strength of thaumasite. The temperature increase is found to accelerate the bond breaking rate and consequently the degradation of mechanical properties of thaumasite, while the strain rate only leads to a slight enhancement of them for the ranges considered in this study.

A Note on Interest Rates and Structural Federal Budget Deficits

OpenAIRE

Kitchen, John

2002-01-01

This paper provides evidence on the response of interest rates to Federal budget deficits. A simple model is presented that incorporates the role of monetary policy in the determination of short-run interest rates and that ascribes the effects of government budget imbalances on the term structure of interest rates to uncertainty about the expected evolution of inflation and real interest rates. Empirical results support the view that the term structure of interest rates is affected by Fede...

Technological and structural change : Understanding economic growth in countries and regions

NARCIS (Netherlands)

Diodato, D.

2017-01-01

The research aims at improving our understanding of the link between economic structure and growth, by tackling a number of open questions. First, it asks whether economic structure – meaning the distribution of production factors among different industries – can significantly explain differences in

Experimental design and estimation of growth rate distributions in size-structured shrimp populations

International Nuclear Information System (INIS)

Banks, H T; Davis, Jimena L; Ernstberger, Stacey L; Hu, Shuhua; Artimovich, Elena; Dhar, Arun K

2009-01-01

We discuss inverse problem results for problems involving the estimation of probability distributions using aggregate data for growth in populations. We begin with a mathematical model describing variability in the early growth process of size-structured shrimp populations and discuss a computational methodology for the design of experiments to validate the model and estimate the growth-rate distributions in shrimp populations. Parameter-estimation findings using experimental data from experiments so designed for shrimp populations cultivated at Advanced BioNutrition Corporation are presented, illustrating the usefulness of mathematical and statistical modeling in understanding the uncertainty in the growth dynamics of such populations

Cold Climate Structural Fire Danger Rating System?

Directory of Open Access Journals (Sweden)

Maria-Monika Metallinou

2018-03-01

Full Text Available Worldwide, fires kill 300,000 people every year. The fire season is usually recognized to be in the warmer periods of the year. Recent research has, however, demonstrated that the colder season also has major challenges regarding severe fires, especially in inhabited (heated wood-based structures in cold-climate areas. Knowledge about the effect of dry cellulose-based materials on fire development, indoor and outdoor, is a motivation for monitoring possible changes in potential fire behavior and associated fire risk. The effect of wind in spreading fires to neighboring structures points towards using weather forecasts as information on potential fire spread behavior. As modern weather forecasts include temperature and relative humidity predictions, there may already be sufficient information available to develop a structural fire danger rating system. Such a system may include the following steps: (1 Record weather forecasts and actual temperature and relative humidity inside and outside selected structures; (2 Develop a meteorology-data-based model to predict indoor relative humidity levels; (3 Perform controlled drying chamber experiments involving typical hygroscopic fire fuel; (4 Compare the results to the recorded values in selected structures; and (5 Develop the risk model involving the results from drying chamber experiments, weather forecasts, and separation between structures. Knowledge about the structures at risk and their use is also important. The benefits of an automated fire danger rating system would be that the society can better plan for potentially severe cold-climate fires and thereby limit the negative impacts of such fires.

Understanding the defect structure of solution grown zinc oxide

Energy Technology Data Exchange (ETDEWEB)

Liew, Laura-Lynn [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, Block N4.1 Nanyang Avenue, Singapore 639798 (Singapore); Sankar, Gopinathan, E-mail: g.sankar@ucl.ac.uk [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Handoko, Albertus D. [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore); Goh, Gregory K.L., E-mail: g-goh@imre.a-star.edu.sg [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, Block N4.1 Nanyang Avenue, Singapore 639798 (Singapore); Kohara, Shinji [Japan Synchrotron Radiation Research Institute (JASRI), Mikazuki, Sayo, Hyogo 679-5198 (Japan)

2012-05-15

Zinc oxide (ZnO) is a wide bandgap semiconducting oxide with many potential applications in various optoelectronic devices such as light emitting diodes (LEDs) and field effect transistors (FETs). Much effort has been made to understand the ZnO structure and its defects. However, one major issue in determining whether it is Zn or O deficiency that provides ZnO its unique properties remains. X-ray absorption spectroscopy (XAS) is an ideal, atom specific characterization technique that is able to probe defect structure in many materials, including ZnO. In this paper, comparative studies of bulk and aqueous solution grown ({<=}90 Degree-Sign C) ZnO powders using XAS and x-ray pair distribution function (XPDF) techniques are described. The XAS Zn-Zn correlation and XPDF results undoubtedly point out that the solution grown ZnO contains Zn deficiency, rather than the O deficiency that were commonly reported. This understanding of ZnO short range order and structure will be invaluable for further development of solid state lighting and other optoelectronic device applications. - Graphical abstract: Highlights: Black-Right-Pointing-Pointer ZnO powders have been synthesized through an aqueous solution method. Black-Right-Pointing-Pointer Defect structure studied using XAS and XPDF. Black-Right-Pointing-Pointer Zn-Zn correlations are less in the ZnO powders synthesized in solution than bulk. Black-Right-Pointing-Pointer Zn vacancies are present in the powders synthesized. Black-Right-Pointing-Pointer EXAFS and XPDF, when used complementary, are useful characterization techniques.

Teaching structure: student use of software tools for understanding macromolecular structure in an undergraduate biochemistry course.

Science.gov (United States)

Jaswal, Sheila S; O'Hara, Patricia B; Williamson, Patrick L; Springer, Amy L

2013-01-01

Because understanding the structure of biological macromolecules is critical to understanding their function, students of biochemistry should become familiar not only with viewing, but also with generating and manipulating structural representations. We report a strategy from a one-semester undergraduate biochemistry course to integrate use of structural representation tools into both laboratory and homework activities. First, early in the course we introduce the use of readily available open-source software for visualizing protein structure, coincident with modules on amino acid and peptide bond properties. Second, we use these same software tools in lectures and incorporate images and other structure representations in homework tasks. Third, we require a capstone project in which teams of students examine a protein-nucleic acid complex and then use the software tools to illustrate for their classmates the salient features of the structure, relating how the structure helps explain biological function. To ensure engagement with a range of software and database features, we generated a detailed template file that can be used to explore any structure, and that guides students through specific applications of many of the software tools. In presentations, students demonstrate that they are successfully interpreting structural information, and using representations to illustrate particular points relevant to function. Thus, over the semester students integrate information about structural features of biological macromolecules into the larger discussion of the chemical basis of function. Together these assignments provide an accessible introduction to structural representation tools, allowing students to add these methods to their biochemical toolboxes early in their scientific development. © 2013 by The International Union of Biochemistry and Molecular Biology.

Understanding specificity in metabolic pathways-Structural biology of human nucleotide metabolism

International Nuclear Information System (INIS)

Welin, Martin; Nordlund, Paer

2010-01-01

Interactions are the foundation of life at the molecular level. In the plethora of activities in the cell, the evolution of enzyme specificity requires the balancing of appropriate substrate affinity with a negative selection, in order to minimize interactions with other potential substrates in the cell. To understand the structural basis for enzyme specificity, the comparison of structural and biochemical data between enzymes within pathways using similar substrates and effectors is valuable. Nucleotide metabolism is one of the largest metabolic pathways in the human cell and is of outstanding therapeutic importance since it activates and catabolises nucleoside based anti-proliferative drugs and serves as a direct target for anti-proliferative drugs. In recent years the structural coverage of the enzymes involved in human nucleotide metabolism has been dramatically improved and is approaching completion. An important factor has been the contribution from the Structural Genomics Consortium (SGC) at Karolinska Institutet, which recently has solved 33 novel structures of enzymes and enzyme domains in human nucleotide metabolism pathways and homologs thereof. In this review we will discuss some of the principles for substrate specificity of enzymes in human nucleotide metabolism illustrated by a selected set of enzyme families where a detailed understanding of the structural determinants for specificity is now emerging.

Effect of Conceptual Change Approach on Students' Understanding of Reaction Rate Concepts

Science.gov (United States)

Kingir, Sevgi; Geban, Omer

2012-01-01

The purpose of the present study was to investigate the effect of conceptual change text oriented instruction compared to traditional instruction on 10th grade students' understanding of reaction rate concepts. 45 students from two classes of the same teacher in a public high school participated in this study. Students in the experimental group…

New protein structures provide an updated understanding of phenylketonuria.

Science.gov (United States)

Jaffe, Eileen K

2017-08-01

Phenylketonuria (PKU) and less severe hyperphenylalaninemia (HPA) constitute the most common inborn error of amino acid metabolism, and is most often caused by defects in phenylalanine hydroxylase (PAH) function resulting in accumulation of Phe to neurotoxic levels. Despite the success of dietary intervention in preventing permanent neurological damage, individuals living with PKU clamor for additional non-dietary therapies. The bulk of disease-associated mutations are PAH missense variants, which occur throughout the entire 452 amino acid human PAH protein. While some disease-associated mutations affect protein structure (e.g. truncations) and others encode catalytically dead variants, most have been viewed as defective in protein folding/stability. Here we refine this view to address how PKU-associated missense variants can perturb the equilibrium among alternate native PAH structures (resting-state PAH and activated PAH), thus shifting the tipping point of this equilibrium to a neurotoxic Phe concentration. This refined view of PKU introduces opportunities for the design or discovery of therapeutic pharmacological chaperones that can help restore the tipping point to healthy Phe levels and how such a therapeutic might work with or without the inhibitory pharmacological chaperone BH 4 . Dysregulation of an equilibrium of architecturally distinct native PAH structures departs from the concept of "misfolding", provides an updated understanding of PKU, and presents an enhanced foundation for understanding genotype/phenotype relationships. Copyright © 2017 Elsevier Inc. All rights reserved.

Understanding and Representing Changing Work Structures and Practices through Art

Science.gov (United States)

Wieland, Stacey M. B.

2018-01-01

Courses: Organizational Communication, Advanced Organizational Communication, Organizing Work, Management/Organizational History. Objectives: This activity will help students to understand major shifts in the organization of work and creatively represent changing work structures and practices. An optional follow-up assignment is included. A…

[Acceptance and understandability of various methods of health valuations for the chronically ill: willingness to pay, visual analogue scale and rating scale].

Science.gov (United States)

Meder, M; Farin, E

2009-11-01

Health valuations are one way of measuring patient preferences with respect to the results of their treatment. The study examines three different methods of health valuations--willingness to pay (WTP), visual analogue scale (VAS), and a rating question for evaluating the subjective significance. The goal is to test the understandability and acceptance of these methods for implementation in questionnaires. In various rehabilitation centres, a total of six focus groups were conducted with 5-9 patients each with a mean age of 57.1 years. The illnesses considered were chronic-ischaemic heart disease, chronic back pain, and breast cancer. Patients filled out a questionnaire that was then discussed in the group. In addition to the quantitative evaluation of the data in the questionnaire, a qualitative analysis of the contents of the group discussion protocols was made. We have results from a total of 42 patients. 14.6% of the patients had "great difficulties" understanding the WTP or rated it as "completely incomprehensible"; this value was 7.3% for VAS and 0% for the rating scale. With respect to acceptance, 31.0% of the patients indicated that they were "not really" or "not at all" willing to answer such a WTP question in a questionnaire; this was 6.6% for the VAS, and again 0% for the rating scale. The qualitative analysis provided an indication as to why some patients view the WTP question in particular in a negative light. Many difficulties in understanding it were related to the formulation of the question and the structure of the questionnaire. However, the patients' statements also made it apparent that the hypothetical nature of the WTP questionnaire was not always recognised. The most frequent reason for the lack of acceptance of the WTP was the patients' fear of negative financial consequences of their responses. With respect to understandability and acceptance, VAS questions appear to be better suited for reflecting patient preferences than WTP questions. The

Structured Head and Neck CT Angiography Reporting Reduces Resident Revision Rates.

Science.gov (United States)

Johnson, Tucker F; Brinjikji, Waleed; Doolittle, Derrick A; Nagelschneider, Alex A; Welch, Brian T; Kotsenas, Amy L

2018-04-12

This resident-driven quality improvement project was undertaken to assess the effectiveness of structured reporting to reduce revision rates for afterhours reports dictated by residents. The first part of the study assessed baseline revision rates for head and neck CT angiography (CTA) examinations dictated by residents during afterhours call. A structured report was subsequently created based on templates on the RSNA informatics reporting website and critical findings that should be assessed for on all CTA examinations. The template was made available to residents through the speech recognition software for all head and neck CTA examinations for a duration of 2 months. Report revision rates were then compared with and without use of the structured template. The structured template was found to reduce revision rates by approximately 50% with 10/41 unstructured reports revised and 2/17 structured reports revised. We believe that structured reporting can help reduce reporting errors, particularly in term of typographical errors, train residents to evaluate complex examinations in a systematic fashion, and assist them in recalling critical findings on these examinations. Copyright © 2018 Elsevier Inc. All rights reserved.

Understanding recall rates in screening mammography: A conceptual framework review of the literature

International Nuclear Information System (INIS)

Mohd Norsuddin, N.; Reed, W.; Mello-Thoms, C.; Lewis, S.J.

2015-01-01

Recall rates are one of the performance measures used to evaluate the effectiveness of mammography screening programs. There is conflicting evidence regarding the link between recall rates and cancer detection rates and a variety of differing recall rates exist between countries and readers. This variability in recall rates may have important clinical and economic implications such as unnecessary follow-up procedures, additional costs to the health care system and psychological effects for the women themselves associated with false-positive mammograms results. In order to reduce the impact of false positive recall rates in screening mammography, it is essential for all multidisciplinary health care providers, especially those in medical imaging, to fully understand the factors that may contribute and affect recall rates. The multifactorial nature of recall rates is explored in this paper through the construction of a conceptual map based on a review of the current literature. - Highlights: • Recall rates vary across countries and readers and for initial and subsequent screens. • Falsely recalling women has important clinical, cost and psycho-social implications. • Imaging technology, readers' expertise and patient presentation affect recall rates. • Higher recall rates do not translate into improved sensitivity at higher thresholds. • Multidisciplinary approaches to reduce recall rates may improve women experiences.

EXCHANGE RATE PASS-THROUGH, IMPORT PRICES AND INFLATION UNDER STRUCTURAL BREAKS

Directory of Open Access Journals (Sweden)

Arintoko Arintoko

2011-09-01

Full Text Available This research estimates the exchange rate pass-through (ERPT into import prices by applying an extension of the basic model of ERPT on Indonesia. It estimates models of cointegration and error-correction mechanism (ECM, with and without structural breaks. It uses the techniques of Zivot-Andrews and of Gregory-Hansen to test for structural breaks and cointegration with the structural breaks, respectively. The results show that with the control variables, inflation affects import prices and lower the pass-through for short term, in a condition of free floating exchange rate. In the short term, with the inclusion of structural breaks, significant inflation affects import prices and lowers the ERPT coefficient.  Keywords:    Exchange rate pass-through, inflation, structural breaks, cointegration, error-correction mechanismJEL classification numbers: C22, C32, E31, F41

Metrology challenges for high-rate nanomanufacturing of polymer structures

Science.gov (United States)

Mead, Joey; Barry, Carol; Busnaina, Ahmed; Isaacs, Jacqueline

2012-10-01

The transfer of nanoscience accomplishments into commercial products is hindered by the lack of understanding of barriers to nanoscale manufacturing. We have developed a number of nanomanufacturing processes that leverage available high-rate plastics fabrication technologies. These processes include directed assembly of a variety of nanoelements, such as nanoparticles and nanotubes, which are then transferred onto a polymer substrate for the fabrication of conformal/flexible electronic materials, among other applications. These assembly processes utilize both electric fields and/or chemical functionalization. Conducting polymers and carbon nanotubes have been successfully transferred to a polymer substrate in times less than 5 minutes, which is commercially relevant and can be utilized in a continuous (reel to reel/roll to roll) process. Other processes include continuous high volume mixing of nanoelements (CNTs, etc) into polymers, multi-layer extrusion and 3D injection molding of polymer structures. These nanomanufacturing processes can be used for wide range of applications, including EMI shielding, flexible electronics, structural materials, and novel sensors (specifically for chem/bio detection). Current techniques to characterize the quality and efficacy of the processes are quite slow. Moreover, the instrumentation and metrology needs for these manufacturing processes are varied and challenging. Novel, rapid, in-line metrology to enable the commercialization of these processes is critically needed. This talk will explore the necessary measurement needs for polymer based nanomanufacturing processes for both step and continuous (reel to reel/roll to roll) processes.

The structure of XIAP BIR2: understanding the selectivity of the BIR domains

Energy Technology Data Exchange (ETDEWEB)

Lukacs, Christine, E-mail: cmlukacs230@gmail.com; Belunis, Charles; Crowther, Robert; Danho, Waleed; Gao, Lin; Goggin, Barry; Janson, Cheryl A.; Li, Shirley; Remiszewski, Stacy; Schutt, Andrew [Hoffmann-La Roche, 340 Kingsland Street, Nutley, NJ 07110 (United States); Thakur, Manish K.; Singh, Saroj K.; Swaminathan, Srinivasan; Pandey, Rajat; Tyagi, Rajiv; Gosu, Ramachandraiah; Kamath, Ajith V. [Jubilant Biosys Ltd, Bangalore (India); Kuglstatter, Andreas, E-mail: cmlukacs230@gmail.com [Hoffmann-La Roche, 340 Kingsland Street, Nutley, NJ 07110 (United States)

2013-09-01

The high-resolution crystal structures of apo and peptide-bound XIAP BIR2 are presented and compared with BIR3 structures to understand their selectivity. This crystal system can be used to determine the structures of BIR2–inhibitor complexes. XIAP, a member of the inhibitor of apoptosis family of proteins, is a critical regulator of apoptosis. Inhibition of the BIR domain–caspase interaction is a promising approach towards treating cancer. Previous work has been directed towards inhibiting the BIR3–caspase-9 interaction, which blocks the intrinsic apoptotic pathway; selectively inhibiting the BIR2–caspase-3 interaction would also block the extrinsic pathway. The BIR2 domain of XIAP has successfully been crystallized; peptides and small-molecule inhibitors can be soaked into these crystals, which diffract to high resolution. Here, the BIR2 apo crystal structure and the structures of five BIR2–tetrapeptide complexes are described. The structural flexibility observed on comparing these structures, along with a comparison with XIAP BIR3, affords an understanding of the structural elements that drive selectivity between BIR2 and BIR3 and which can be used to design BIR2-selective inhibitors.

A Spatial Framework for Understanding Population Structure and Admixture.

Science.gov (United States)

Bradburd, Gideon S; Ralph, Peter L; Coop, Graham M

2016-01-01

Geographic patterns of genetic variation within modern populations, produced by complex histories of migration, can be difficult to infer and visually summarize. A general consequence of geographically limited dispersal is that samples from nearby locations tend to be more closely related than samples from distant locations, and so genetic covariance often recapitulates geographic proximity. We use genome-wide polymorphism data to build "geogenetic maps," which, when applied to stationary populations, produces a map of the geographic positions of the populations, but with distances distorted to reflect historical rates of gene flow. In the underlying model, allele frequency covariance is a decreasing function of geogenetic distance, and nonlocal gene flow such as admixture can be identified as anomalously strong covariance over long distances. This admixture is explicitly co-estimated and depicted as arrows, from the source of admixture to the recipient, on the geogenetic map. We demonstrate the utility of this method on a circum-Tibetan sampling of the greenish warbler (Phylloscopus trochiloides), in which we find evidence for gene flow between the adjacent, terminal populations of the ring species. We also analyze a global sampling of human populations, for which we largely recover the geography of the sampling, with support for significant histories of admixture in many samples. This new tool for understanding and visualizing patterns of population structure is implemented in a Bayesian framework in the program SpaceMix.

Structural and climatic determinants of demographic rates of Scots pine forests across the Iberian Peninsula.

Science.gov (United States)

Vilà-Cabrera, Albert; Martínez-Vilalta, Jordi; Vayreda, Jordi; Retana, Javier

2011-06-01

The demographic rates of tree species typically show large spatial variation across their range. Understanding the environmental factors underlying this variation is a key topic in forest ecology, with far-reaching management implications. Scots pine (Pinus sylvestris L.) covers large areas of the Northern Hemisphere, the Iberian Peninsula being its southwestern distribution limit. In recent decades, an increase in severe droughts and a densification of forests as a result of changes in forest uses have occurred in this region. Our aim was to use climate and stand structure data to explain mortality and growth patterns of Scots pine forests across the Iberian Peninsula. We used data from 2392 plots dominated by Scots pine, sampled for the National Forest Inventory of Spain. Plots were sampled from 1986 to 1996 (IFN2) and were resampled from 1997 to 2007 (IFN3), allowing for the calculation of growth and mortality rates. We fitted linear models to assess the response of growth and mortality rates to the spatial variability of climate, climatic anomalies, and forest structure. Over the period of approximately 10 years between the IFN2 and IFN3, the amount of standing dead trees increased 11-fold. Higher mortality rates were related to dryness, and growth was reduced with increasing dryness and temperature, but results also suggested that effects of climatic stressors were not restricted to dry sites only. Forest structure was strongly related to demographic rates, suggesting that stand development and competition are the main factors associated with demography. In the case of mortality, forest structure interacted with climate, suggesting that competition for water resources induces tree mortality in dry sites. A slight negative relationship was found between mortality and growth, indicating that both rates are likely to be affected by the same stress factors. Additionally, regeneration tended to be lower in plots with higher mortality. Taken together, our results

What do children know and understand about universal gravitation? Structural and developmental aspects

NARCIS (Netherlands)

Frappart, S.; Raijmakers, M.; Frède, V.

2014-01-01

Children's understanding of universal gravitation starts at an early age but changes until adulthood, which makes it an interesting topic for studying the development and structure of knowledge. Children's understanding of gravitation was tested for a variety of contexts and across a wide age range

Does ownership structure improve credit ratings?

Directory of Open Access Journals (Sweden)

Aws AlHares

2018-04-01

Full Text Available This study seeks to examine the impact of Block Ownership structure on Credit Ratings in OECD countries. This research seeks to contribute to the extant literature by exploring the effects of Corporate Governance (CG mechanisms on corporate credit ratings. The study uses a panel data of 200 companies from Anglo American and European countries between 2010 and 2014. The ordinary least square regression is used to examine the relationships. Additionally, to alleviate the concern of potential endogeneity, we use fixed effect regression, two-stage least squares using instrumental variables. The results show there is a negative and significant relationship between block ownership and credit ratings, with a greater significance among Anglo American countries than among European countries. The rationale for this is that Anglo-American system gives preferential treatment to individual shareholders and its accounting tradition leads to a decline in risk and increase in credit ratings. The result is consistent with the multi-theoretical framework predictions derived from the agency and stewardship theories. Future research could investigate credit ratings using other credit rating agencies, selecting a larger sample that includes small, mid-size and large companies. This paper extends, as well as contributes to extant CG literature by offering new evidence on the effect of block ownership on credit ratings between two different traditions. This will be explored by employing firm-level CG mechanisms by accounting for control variables. The findings will help regulators and policymakers in OECD countries in evaluating the adequacy of current CG reforms to prevent management misconduct and scandals.

Understanding Early Elementary Children's Conceptual Knowledge of Plant Structure and Function through Drawings

Science.gov (United States)

Anderson, Janice L.; Ellis, Jane P.; Jones, Alan M.

2014-01-01

This study examined children's drawings to explain children's conceptual understanding of plant structure and function. The study explored whether the children's drawings accurately reflect their conceptual understanding about plants in a manner that can be interpreted by others. Drawing, survey, interview, and observational data were collected…

Fundamental challenges in mechanistic enzymology: progress toward understanding the rate enhancements of enzymes.

Science.gov (United States)

Herschlag, Daniel; Natarajan, Aditya

2013-03-26

Enzymes are remarkable catalysts that lie at the heart of biology, accelerating chemical reactions to an astounding extent with extraordinary specificity. Enormous progress in understanding the chemical basis of enzymatic transformations and the basic mechanisms underlying rate enhancements over the past decades is apparent. Nevertheless, it has been difficult to achieve a quantitative understanding of how the underlying mechanisms account for the energetics of catalysis, because of the complexity of enzyme systems and the absence of underlying energetic additivity. We review case studies from our own work that illustrate the power of precisely defined and clearly articulated questions when dealing with such complex and multifaceted systems, and we also use this approach to evaluate our current ability to design enzymes. We close by highlighting a series of questions that help frame some of what remains to be understood, and we encourage the reader to define additional questions and directions that will deepen and broaden our understanding of enzymes and their catalysis.

Understanding structure of urban traffic network based on spatial-temporal correlation analysis

Science.gov (United States)

Yang, Yanfang; Jia, Limin; Qin, Yong; Han, Shixiu; Dong, Honghui

2017-08-01

Understanding the structural characteristics of urban traffic network comprehensively can provide references for improving road utilization rate and alleviating traffic congestion. This paper focuses on the spatial-temporal correlations between different pairs of traffic series and proposes a complex network-based method of constructing the urban traffic network. In the network, the nodes represent road segments, and an edge between a pair of nodes is added depending on the result of significance test for the corresponding spatial-temporal correlation. Further, a modified PageRank algorithm, named the geographical weight-based PageRank algorithm (GWPA), is proposed to analyze the spatial distribution of important segments in the road network. Finally, experiments are conducted by using three kinds of traffic series collected from the urban road network in Beijing. Experimental results show that the urban traffic networks constructed by three traffic variables all indicate both small-world and scale-free characteristics. Compared with the results of PageRank algorithm, GWPA is proved to be valid in evaluating the importance of segments and identifying the important segments with small degree.

Optical and electrical properties of structured multilayer with tunable transparency rate

International Nuclear Information System (INIS)

Bou, Adrien; Torchio, Philippe; Barakel, Damien; Guillou, Aurélie; Thoulon, Pierre-Yves; Ricci, Marc; Ayachi, Boubakeur

2015-01-01

An experimental study has been carried out on structured multilayer with tunable transparency rate. In this paper, we present the optical and electrical characterization of an oxide | metal | oxide structured electrode manufactured by e-beam deposition and patterned by a lift-off process. The obtained samples are made of grids with different geometrical parameters that lead to varying surface coverage rate on glass. The electrical and optical parameters of SnO x |Ag|SnO x grids are investigated to determine the efficiency, sustainability and limitations of such structures. A linear relationship between the transmittance of the electrodes and the increase of the surface coverage rate is obtained. Coupled to an optimization process, we are able to define a high transparency in a chosen spectral range. Electrical results show a relative stability of the resistivity from 2.9   ×   10   −  4  Ω.cm for an as-grown electrode to 5.6   ×   10   −  4  Ω.cm for a structured electrode with a surface coverage rate of 59%. (paper)

The construction of an amino acid network for understanding protein structure and function.

Science.gov (United States)

Yan, Wenying; Zhou, Jianhong; Sun, Maomin; Chen, Jiajia; Hu, Guang; Shen, Bairong

2014-06-01

Amino acid networks (AANs) are undirected networks consisting of amino acid residues and their interactions in three-dimensional protein structures. The analysis of AANs provides novel insight into protein science, and several common amino acid network properties have revealed diverse classes of proteins. In this review, we first summarize methods for the construction and characterization of AANs. We then compare software tools for the construction and analysis of AANs. Finally, we review the application of AANs for understanding protein structure and function, including the identification of functional residues, the prediction of protein folding, analyzing protein stability and protein-protein interactions, and for understanding communication within and between proteins.

Stochastic demography and the neutral substitution rate in class-structured populations.

Science.gov (United States)

Lehmann, Laurent

2014-05-01

The neutral rate of allelic substitution is analyzed for a class-structured population subject to a stationary stochastic demographic process. The substitution rate is shown to be generally equal to the effective mutation rate, and under overlapping generations it can be expressed as the effective mutation rate in newborns when measured in units of average generation time. With uniform mutation rate across classes the substitution rate reduces to the mutation rate.

Three Mile Island: Impact on electric rate structures

International Nuclear Information System (INIS)

Carter, E.F.

1983-01-01

The historical significance of the March 28, 1979 accident at TMI-2 has not, can not and will not likely be fully appreciated by our generation. The nuclear industry, the financial community, regulator of electric utilities and the investor-owned electric utilities are beginning to understand this newly added complex dimension that has entered our daily work process. The degree of understanding that each possesses is a function of his involvement in the restoration process in evaluating whether the nuclear option is to survive. The body of material presented herein represents an effort to capsulize the significant associated with providing electricity at reasonable prices to all service classifications that followed in the wake of the March 29, 1979 TMI accident. Highlights of some of the oft-conflicting activities and cost implications are defined. An attempt is also made to quantify the rate changes, subsequent to the accident, as to TMI related and non-TMI related cost. Some of the cost allocation difficulties encountered are also enumerated. There are no classic textbooks, treatise, or manuals on the market that abridge the traditional approaches to ratemaking. Finally, a perspective comparison is made to demonstrate that GPU's rates are still reasonable considering other factors - namely overall inflation and regional electricity prices

Understanding the mechanisms behind coking pressure: Relationship to pore structure

Energy Technology Data Exchange (ETDEWEB)

John J. Duffy; M. Castro Diaz; Colin E. Snape; Karen M. Steel; Merrick R. Mahoney [University of Nottingham, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre, School of Chemical, Environmental and Mining Engineering

2007-09-15

Three low volatile coals A, B and C with oven wall pressures of 100 kPa, 60 kPa and 20 kPa respectively were investigated using high-temperature rheometry, {sup 1}H NMR, thermogravimetric analysis and SEM, with the primary aim to better understand the mechanisms behind the coking pressure phenomenon. Rheometer plate displacement measurements ({Delta}L) have shown differences in the expansion and contraction behaviour of the three coals, which seem to correlate with changes in rheological properties; while SEM images have shown that the expansion process coincides with development of pore structure. It is considered that the point of maximum plate height ({Delta}L{sub max}) prior to contraction may be indicative of a cell opening or pore network forming process, based on analogies with other foam systems. Such a process may be considered important for coking pressure since it provides a potential mechanism for volatile escape, relieving internal gas pressure and inducing charge contraction. For coal C, which has the highest fluidity {delta}L{sub max} occurs quite early in the softening process and consequently a large degree of contraction is observed; while for the lower fluidity coal B, the process is delayed since pore development and consequently wall thinning progress at a slower rate. When {Delta}L{sub max} is attained, a lower degree of contraction is observed because the event occurs closer to resolidification where the increasing viscosity/elasticity can stabilise the expanded pore structure. For coal A which is relatively high fluidity, but also high coking pressure, a greater degree of swelling is observed prior to cell rupture, which may be due to greater fluid elasticity during the expansion process. This excessive expansion is considered to be a potential reason for its high coking pressure. 58 refs., 15 figs., 1 tab.

Understanding of Android-Based Robotic and Game Structure

Science.gov (United States)

Phongtraychack, A.; Syryamkin, V.

2018-05-01

The development of an android with impressive lifelike appearance and behavior has been a long-standing goal in robotics and a new and exciting approach of smartphone-based robotics for research and education. Recent years have been progressive for many technologies, which allowed creating such androids. There are different examples including the autonomous Erica android system capable of conversational interaction and speech synthesis technologies. The behavior of Android-based robot could be running on the phone as the robot performed a task outdoors. In this paper, we present an overview and understanding of the platform of Android-based robotic and game structure for research and education.

Structure factors for tunneling ionization rates of molecules

DEFF Research Database (Denmark)

Madsen, L.B.; Jensen, F.; Tolstikhin, O.I.

2013-01-01

Within the weak-field asymptotic theory, the dependence of the tunneling ionization rate of a molecule in a static electric field on its orientation with respect to the field is determined by the structure factor for the highest occupied molecular orbital (HOMO). An accurate determination...

Exponential decay of GC content detected by strand-symmetric substitution rates influences the evolution of isochore structure.

Science.gov (United States)

Karro, J E; Peifer, M; Hardison, R C; Kollmann, M; von Grünberg, H H

2008-02-01

The distribution of guanine and cytosine nucleotides throughout a genome, or the GC content, is associated with numerous features in mammals; understanding the pattern and evolutionary history of GC content is crucial to our efforts to annotate the genome. The local GC content is decaying toward an equilibrium point, but the causes and rates of this decay, as well as the value of the equilibrium point, remain topics of debate. By comparing the results of 2 methods for estimating local substitution rates, we identify 620 Mb of the human genome in which the rates of the various types of nucleotide substitutions are the same on both strands. These strand-symmetric regions show an exponential decay of local GC content at a pace determined by local substitution rates. DNA segments subjected to higher rates experience disproportionately accelerated decay and are AT rich, whereas segments subjected to lower rates decay more slowly and are GC rich. Although we are unable to draw any conclusions about causal factors, the results support the hypothesis proposed by Khelifi A, Meunier J, Duret L, and Mouchiroud D (2006. GC content evolution of the human and mouse genomes: insights from the study of processed pseudogenes in regions of different recombination rates. J Mol Evol. 62:745-752.) that the isochore structure has been reshaped over time. If rate variation were a determining factor, then the current isochore structure of mammalian genomes could result from the local differences in substitution rates. We predict that under current conditions strand-symmetric portions of the human genome will stabilize at an average GC content of 30% (considerably less than the current 42%), thus confirming that the human genome has not yet reached equilibrium.

The term structure of interest rates and macroeconomic factors: Evidence from Indian financial market

Directory of Open Access Journals (Sweden)

K. Hassan Shareef

2017-12-01

Full Text Available The term structure of interest rate per-se is not impeccable for explaining the behavior of the future economic conditions and hence incorporating macro factors in the term structure model is more tractable. The study uses monthly data of macro factors for a period of eighteen years from April 1998 to May 2016. Using structural vector auto regression estimates, Granger causality/block exogeneity wald test along with impulse response functions and forecast error variance decomposition analysis the study tests the proportion of term structure attributable to macro-economic shocks. The findings of the study show that short term rates are mainly influenced by the fiscal deficit present in emerging economies while long term rates get affected when market participants revise their expectation on yields. In addition, the output growth of the country is mainly depended on long and short rates and exchange rate fluctuations have a significant role in the fiscal deficit of the country. Keywords: Term structure of interest rates, Inflation, Output growth, NEER, Monetary policy rate, JEL Classification: E43, E31, E2

Predator attack rate evolution in space: the role of ecology mediated by complex emergent spatial structure and self-shading.

Science.gov (United States)

Messinger, Susanna M; Ostling, Annette

2013-11-01

Predation interactions are an important element of ecological communities. Population spatial structure has been shown to influence predator evolution, resulting in the evolution of a reduced predator attack rate; however, the evolutionary role of traits governing predator and prey ecology is unknown. The evolutionary effect of spatial structure on a predator's attack rate has primarily been explored assuming a fixed metapopulation spatial structure, and understood in terms of group selection. But endogenously generated, emergent spatial structure is common in nature. Furthermore, the evolutionary influence of ecological traits may be mediated through the spatial self-structuring process. Drawing from theory on pathogens, the evolutionary effect of emergent spatial structure can be understood in terms of self-shading, where a voracious predator limits its long-term invasion potential by reducing local prey availability. Here we formalize the effects of self-shading for predators using spatial moment equations. Then, through simulations, we show that in a spatial context self-shading leads to relationships between predator-prey ecology and the predator's attack rate that are not expected in a non-spatial context. Some relationships are analogous to relationships already shown for host-pathogen interactions, but others represent new trait dimensions. Finally, since understanding the effects of ecology using existing self-shading theory requires simplifications of the emergent spatial structure that do not apply well here, we also develop metrics describing the complex spatial structure of the predator and prey populations to help us explain the evolutionary effect of predator and prey ecology in the context of self-shading. The identification of these metrics may provide a step towards expansion of the predictive domain of self-shading theory to more complex spatial dynamics. Copyright © 2013 Elsevier Inc. All rights reserved.

Essays on financial econometrics : modeling the term structure of interest rates

NARCIS (Netherlands)

Bouwman, Kees Evert

2008-01-01

This dissertation bundles five studies in financial econometrics that are related to the theme of modeling the term structure of interest rates. The main contribution of this dissertation is a new arbitrage-free term structure model that is applied in an empirical analysis of the US term structure.

Understanding heart rate alarm adjustment in the intensive care units through an analytical approach.

Directory of Open Access Journals (Sweden)

Richard L Fidler

Full Text Available Heart rate (HR alarms are prevalent in ICU, and these parameters are configurable. Not much is known about nursing behavior associated with tailoring HR alarm parameters to individual patients to reduce clinical alarm fatigue.To understand the relationship between heart rate (HR alarms and adjustments to reduce unnecessary heart rate alarms.Retrospective, quantitative analysis of an adjudicated database using analytical approaches to understand behaviors surrounding parameter HR alarm adjustments. Patients were sampled from five adult ICUs (77 beds over one month at a quaternary care university medical center. A total of 337 of 461 ICU patients had HR alarms with 53.7% male, mean age 60.3 years, and 39% non-Caucasian. Default HR alarm parameters were 50 and 130 beats per minute (bpm. The occurrence of each alarm, vital signs, and physiologic waveforms was stored in a relational database (SQL server.There were 23,624 HR alarms for analysis, with 65.4% exceeding the upper heart rate limit. Only 51% of patients with HR alarms had parameters adjusted, with a median upper limit change of +5 bpm and -1 bpm lower limit. The median time to first HR parameter adjustment was 17.9 hours, without reduction in alarms occurrence (p = 0.57.HR alarms are prevalent in ICU, and half of HR alarm settings remain at default. There is a long delay between HR alarms and parameters changes, with insufficient changes to decrease HR alarms. Increasing frequency of HR alarms shortens the time to first adjustment. Best practice guidelines for HR alarm limits are needed to reduce alarm fatigue and improve monitoring precision.

Change in Family Structure and Rates of Violent Juvenile Delinquency

OpenAIRE

Fry, Jeannie A

2010-01-01

This paper addresses the question: Have the changes in family structure in the U.S. become a catalyst for juvenile delinquency? For this research, I use existing statistics for my three independent variables: divorce rates, rate of working mothers with children under age 18, percent female-headed households. My dependent variable, juvenile violent crime rates, is measured using data from the Office of Juvenile Justice and Delinquency Prevention. My control variables consist of the followin...

PROSPECTIVE TEACHERS’ COGNITIVE STRUCTURES CONCERNING PROTEIN SYNTHESIS AND THEIR DEGREE OF UNDERSTANDING

Directory of Open Access Journals (Sweden)

Cem Gerçek

2018-02-01

Full Text Available The purpose of education is to actualise meaningful learning. Therefore, researching the issues on how students process information and how they configure it is important for meaningful learning. The issue of protein synthesis contains a number of abstract topics and concepts. Hence, it is important in biology teaching to be informed of students’ cognitive structures concerning protein synthesis. This research aims to analyse prospective teachers’ cognitive structures about protein synthesis and their degree of understanding the subject. The research group was composed of 17 volunteering prospective teachers who had been chosen through purposeful sampling. The data were collected via semi-structured interviews. Flow maps and content analysis were used in analysing the data. The results demonstrated that prospective teachers had too many misconceptions about protein synthesis and that their knowledge extent and rich connection are inadequate. The prospective teachers’ degree of understanding protein synthesis was divided into three categories. The results obtained in this research suggested that teachers should be careful in teaching the subject of protein synthesis. Students’ prior knowledge and their misconceptions should be determined and content or contexts to facilitate them to learn an abstract subject such as protein synthesis should be presented.

Understanding Content-and-Structure

NARCIS (Netherlands)

Kamps, J.; Marx, M.J.; de Rijke, M.; Sigurbjörnsson, B.; Trotman, A.; Lalmas, M.; Fuhr, N.

2005-01-01

Document-centric XML is a mixture of text and structure. +With the increased availability of document-centric XML content comes a need for query facilities in which both structural constraints and constraints on the content of the documents can be expressed. This has generated considerable interest

A generalized one-factor term structure model and pricing of interest rate derivative securities

NARCIS (Netherlands)

Jiang, George J.

1997-01-01

The purpose of this paper is to propose a nonparametric interest rate term structure model and investigate its implications on term structure dynamics and prices of interest rate derivative securities. The nonparametric spot interest rate process is estimated from the observed short-term interest

31 CFR 351.12 - What do I need to know about the long-term savings bond rate, to understand redemption value...

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false What do I need to know about the long-term savings bond rate, to understand redemption value calculations in this subpart? 351.12 Section 351... What do I need to know about the long-term savings bond rate, to understand redemption value...

31 CFR 351.11 - What do I need to know about the short-term savings bond rate, to understand redemption value...

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false What do I need to know about the short-term savings bond rate, to understand redemption value calculations in this subpart? 351.11... Provisions § 351.11 What do I need to know about the short-term savings bond rate, to understand redemption...

31 CFR 351.13 - What do I need to know about the savings bond rate to understand redemption value calculations in...

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false What do I need to know about the savings bond rate to understand redemption value calculations in this subpart? 351.13 Section 351.13 Money... What do I need to know about the savings bond rate to understand redemption value calculations in this...

Generation time, net reproductive rate, and growth in stage-age-structured populations

DEFF Research Database (Denmark)

Steiner, Uli; Tuljapurkar, Shripad; Coulson, Tim

2014-01-01

examples to show how reproductive timing Tc and level R0 are shaped by stage dynamics (individual trait changes), selection on the trait, and parent-offspring phenotypic correlation. We also show how population structure can affect dispersion in reproduction among ages and stages. These macroscopic...... to age-structured populations. Here we generalize this result to populations structured by stage and age by providing a new, unique measure of reproductive timing (Tc) that, along with net reproductive rate (R0), has a direct mathematical relationship to and approximates growth rate (r). We use simple...

Higher Education Support Services and Graduation Rates of Structured Education Program Students

Science.gov (United States)

Hepner, Seth

2017-01-01

The 1st-year retention rate of the Structured Education Program (SEP) is 90%, yet the 6-year graduation rate of SEP students is 29%. The gap between SEP 1st-year retention and graduation rates is the problem that this study addressed. The low graduation rate of SEP students is an important issue because graduation rates are used to measure the…

Understanding Structure of Poverty Dimensions in East Java: Bicluster Approach

Directory of Open Access Journals (Sweden)

Budi Yuniarto

2017-07-01

Full Text Available Poverty is still become a main problem for Indonesia, where recently, the view point of poverty is not just from income or consumption, but it’s defined multidimensionally. The understanding of the structure of multidimensional poverty is essential to government to develop policies for poverty reduction. This paper aims to describe the structure of poverty in East Java by using variables forming the dimensions of poverty and to investigate any clustering patterns in the region of East Java with considering the poverty variables using biclustering method. Biclustering is an unsupervised technique in data mining where we are grouping scalars from the two-dimensional matrix. Using bicluster analysis, we found two bicluster where each bicluster has different characteristics.DOI: 10.15408/sjie.v6i2.4769

Culture’s Influence: Regionally Differing Social Milieus and Variations in Fertility Rates

OpenAIRE

Fulda, B.

2015-01-01

How can we understand subnational differences in fertility rates? The most common explanations see the key to these differences in the socio-structural composition of a region’s population and its structural conditions. However, such explanations fail to account for fertility rate differences in regions with similar populations and structures. This paper analyzes two social milieus in southern Germany and argues that variations in their fertility rates can only be understood through their cul...

Characterization of radon entry rates and indoor concentrations in underground structures

International Nuclear Information System (INIS)

Borak, T.B.; Whicker, F.W.; Fraley, L.; Gadd, M.S.; Ibrahim, S.A.; Monette, F.A.; Morris, R.; Ward, D.C.

1992-01-01

An experimental facility has been designed to comprehensively determine the influence of soil and meterological conditions on the transport of radon into underground structures. Two identical basements are equipped to continuously monitor pressure differentials, temperatures, soil moisture, precipitation, barometric pressure, wind speed, wind direction, natural ventiliation rates, and radon concentrations. A computerized data acquisition system accumulates and processes data at the rate of 6000 points per day. The experimental design is based on performing experiments in one structure, with the other used as a control. Indoor radon concentrations have temporal variations ranging from 150 to 1400 Bq m -3 . The corresponding entry rate of radon ranges from 300 to 10,000 Bq h -1 . When the radon entry rate is high, the indoor radon concentration decreases, whereas elevated radon concentrations seem to be associated with slow but persistent radon entry rates. This inverse relationship is partially due to compensation from enhanced natural ventilation during periods when the radon entry rate is high. Correlations between measured variables in the soil and indoor-outdoor atmospheres are used to interpret these data. This laboratory has the capability to generate essential data required for developing and testing radon transport models

Understanding the Disproportionately Low Marriage Rate among African Americans: An Amalgam of Sociological and Psychological Constraints

Science.gov (United States)

Chambers, Anthony L.; Kravitz, Aliza

2011-01-01

African Americans have the lowest marriage rate of any racial and ethnic group in America. Although the low marriage rate among African Americans has been largely examined through a sociological lens by documenting structural barriers, which has important policy implications, researchers have not sufficiently examined the psychological and…

Application of Characterization, Modeling, and Analytics Towards Understanding Process Structure Linkages in Metallic 3D Printing (Postprint)

Science.gov (United States)

2017-08-01

METALLIC 3D PRINTING (POSTPRINT) M.A. Groeber, E. Schwalbach, S. Donegan, K. Chaput, T. Butler, and J. Miller AFRL/RX 27 JULY...MODELING, AND ANALYTICS TOWARDS UNDERSTANDING PROCESS- STRUCTURE LINKAGES IN METALLIC 3D PRINTING (POSTPRINT) 5a. CONTRACT NUMBER IN-HOUSE 5b...characterization, modelling, and analytics towards understanding process-structure linkages in metallic 3D printing M A Groeber, E Schwalbach, S Donegan, K

Measuring Implicit Rental Rates for Farm Capital

OpenAIRE

Hrubovcak, James

1986-01-01

Developing implicit rental rates for capital inputs is an Important step in understanding the Impact of tax law changes on agricultural investments This article develops a methodology for estimating implicit rental rates and presents annual estimates of rental rates for seven categories of farm equipment and structures from 1955 to 1979 This article also compares these rental rates With those estimated under a no-tax alternative The author developed a method for estimating marginal Federal In...

Understanding surface structure and chemistry of single crystal lanthanum aluminate

KAUST Repository

Pramana, Stevin S.

2017-03-02

The surface crystallography and chemistry of a LaAlO3 single crystal, a material mainly used as a substrate to deposit technologically important thin films (e.g. for superconducting and magnetic devices), was analysed using surface X-ray diffraction and low energy ion scattering spectroscopy. The surface was determined to be terminated by Al-O species, and was significantly different from the idealised bulk structure. Termination reversal was not observed at higher temperature (600 °C) and chamber pressure of 10−10 Torr, but rather an increased Al-O occupancy occurred, which was accompanied by a larger outwards relaxation of Al from the bulk positions. Changing the oxygen pressure to 10−6 Torr enriched the Al site occupancy fraction at the outermost surface from 0.245(10) to 0.325(9). In contrast the LaO, which is located at the next sub-surface atomic layer, showed no chemical enrichment and the structural relaxation was lower than for the top AlO2 layer. Knowledge of the surface structure will aid the understanding of how and which type of interface will be formed when LaAlO3 is used as a substrate as a function of temperature and pressure, and so lead to improved design of device structures.

Testing for long-range dependence in the Brazilian term structure of interest rates

International Nuclear Information System (INIS)

Cajueiro, Daniel O.; Tabak, Benjamin M.

2009-01-01

This paper presents empirical evidence of fractional dynamics in interest rates for different maturities for Brazil. A variation of a newly developed test for long-range dependence, the V/S statistic, with a post-blackening bootstrap is employed. Results suggest that Brazilian interest rates possess strong long-range dependence in volatility, even when considering the structural break in 1999. These findings imply that the development of policy models that give rise to long-range dependence in interest rates' volatility could be very useful. The long-short-term interest rates spread has strong long-range dependence, which suggests that traditional tests of expectation hypothesis of the term structure of interest rates may be misspecified.

Structural image and video understanding

NARCIS (Netherlands)

Lou, Z.

2016-01-01

In this thesis, we have discussed how to exploit the structures in several computer vision topics. The five chapters addressed five computer vision topics using the image structures. In chapter 2, we proposed a structural model to jointly predict the age, expression and gender of a face. By modeling

Towards new understanding of the heart structure and function.

Science.gov (United States)

Torrent-Guasp, Francisco; Kocica, Mladen J; Corno, Antonio F; Komeda, Masashi; Carreras-Costa, Francesc; Flotats, A; Cosin-Aguillar, Juan; Wen, Han

2005-02-01

Structure and function in any organ are inseparable categories, both in health and disease. Whether we are ready to accept, or not, many questions in cardiovascular medicine are still pending, due to our insufficient insight in the basic science. Even so, any new concept encounters difficulties, mainly arising from our inert attitude, which may result either in unjustified acceptance or denial. The ventricular myocardial band concept, developed over the last 50 years, has revealed unavoidable coherence and mutual coupling of form and function in the ventricular myocardium. After more than five centuries long debate on macroscopic structure of the ventricular myocardium, this concept has provided a promising ground for its final understanding. Recent validations of the ventricular myocardial band, reviewed here, as well as future research directions that are pointed out, should initiate much wider scientific interest, which would, in turn, lead to reconciliation of some exceeded concepts about developmental, electrical, mechanical and energetical events in human heart. The benefit of this, of course, would be the most evident in the clinical arena.

Understanding erosion rates in the Himalayan orogen: A case study from the Arun Valley

Science.gov (United States)

Olen, Stephanie M.; Bookhagen, Bodo; Hoffmann, Bernd; Sachse, Dirk; Adhikari, D. P.; Strecker, Manfred R.

2015-10-01

Understanding the rates and pattern of erosion is a key aspect of deciphering the impacts of climate and tectonics on landscape evolution. Denudation rates derived from terrestrial cosmogenic nuclides (TCNs) are commonly used to quantify erosion and bridge tectonic (Myr) and climatic (up to several kiloyears) time scales. However, how the processes of erosion in active orogens are ultimately reflected in 10Be TCN samples remains a topic of discussion. We investigate this problem in the Arun Valley of eastern Nepal with 34 new 10Be-derived catchment-mean denudation rates. The Arun Valley is characterized by steep north-south gradients in topography and climate. Locally, denudation rates increase northward, from <0.2 mm yr-1 to ~1.5 mm yr-1 in tributary samples, while main stem samples appear to increase downstream from ~0.2 mm yr-1 at the border with Tibet to 0.91 mm yr-1 in the foreland. Denudation rates most strongly correlate with normalized channel steepness (R2 = 0.67), which has been commonly interpreted to indicate tectonic activity. Significant downstream decrease of 10Be concentration in the main stem Arun suggests that upstream sediment grains are fining to the point that they are operationally excluded from the processed sample. This results in 10Be concentrations and denudation rates that do not uniformly represent the upstream catchment area. We observe strong impacts on 10Be concentrations from local, nonfluvial geomorphic processes, such as glaciation and landsliding coinciding with areas of peak rainfall rates, pointing toward climatic modulation of predominantly tectonically driven denudation rates.

[Do laymen understand information about hospital quality? An empirical verification using risk-adjusted mortality rates as an example].

Science.gov (United States)

Sander, Uwe; Kolb, Benjamin; Taheri, Fatemeh; Patzelt, Christiane; Emmert, Martin

2017-11-01

The effect of public reporting to improve quality in healthcare is reduced by the limited intelligibility of information about the quality of healthcare providers. This may result in worse health-related choices especially for older people and those with lower levels of education. There is, as yet, little information as to whether laymen understand the concepts behind quality comparisons and if this comprehension is correlated with hospital choices. An instrument with 20 items was developed to analyze the intelligibility of five technical terms which were used in German hospital report cards to explain risk-adjusted death rates. Two online presentations of risk-adjusted death rates for five hospitals in the style of hospital report cards were developed. An online survey of 353 volunteers tested the comprehension of the risk-adjusted mortality rates and included an experimental hospital choice. The intelligibility of five technical terms was tested: risk-adjusted, actual and expected death rate, reference range and national average. The percentages of correct answers for the five technical terms were in the range of 75.0-60.2%. Between 23.8% and 5.1% of the respondents were not able to answer the question about the technical term itself. The least comprehensible technical terms were "risk-adjusted death rate" and "reference range". The intelligibility of the 20 items that were used to test the comprehension of the risk-adjusted mortality was between 89.5% and 14.2%. The two items that proved to be least comprehensible were related to the technical terms "risk-adjusted death rate" and "reference range". For all five technical terms it was found that a better comprehension correlated significantly with better hospital choices. We found a better than average intelligibility for the technical terms "actual and expected death rate" and for "national average". The least understandable were "risk-adjusted death rate" and "reference range". Since the self

Evaluation of soil structure in the framework of an overall soil quality rating

DEFF Research Database (Denmark)

Mueller, L; Shepherd, T G; Schindler, U

2013-01-01

Soil structure is an important aspect of agricultural soil quality, and its preservation and improvement are key to sustaining soil functions. Methods of overall soil quality assessment which include visual soil structure information can be useful tools for monitoring and managing the global soil...... resource. The aim of the paper is: (i) to demonstrate the role of visual quantification of soil structure within the procedure of the overall soil quality assessment by the Muencheberg Soil Quality Rating (M-SQR), (ii) to quantify the magnitude and variability of soil structure and overall M......-SQR on a number of agricultural research sites and (iii) to analyse the correlations of soil quality rating results with crop yields. We analysed visual soil structure and overall soil quality on a range of 20 experimental sites in seven countries. To assess visual soil structure we utilised the Visual Soil...

[Do online ratings reflect structural differences in healthcare? The example of German physician-rating websites].

Science.gov (United States)

Meszmer, Nina; Jaegers, Lena; Schöffski, Oliver; Emmert, Martin

2018-04-01

Previous surveys have shown that patient satisfaction varies with the regional supply of physicians. Online ratings on physician-rating websites represent a relatively new instrument to display patient satisfaction results. The aim of this study was (1) to assess the current state of online ratings for two medical disciplines (dermatologists and ear, nose and throat (ENT) specialists), and (2) to analyze online derived patient satisfaction results according to the physician density in Germany. We collected online ratings for 420 dermatologists and 450 ear, nose, and throat (ENT) specialists on twelve German physician-rating websites. We analyzed the online ratings according to the physician density (low, medium, high physician density). For this purpose, we collected secondary data from both physician-rating websites and the regional associations of statutory health insurance physicians. Data analysis was performed using Median tests and Chi-square tests. In total, 10,239 online ratings for dermatologists and 8,168 online ratings for ENT specialists were analyzed. Almost all dermatologists (99.3 %) and ENT specialists (98.9 %) were listed on one of the physician-rating websites. A total of 93.5 % of all listed dermatologists and 96.9 % of ENT-specialists were rated on at least one of the physician-rating websites. Significant differences were found in the distribution (i.e., percentage of listed or rated physicians) of the ratings according to the regional physician density on only one physician-rating website (pexample, dermatologist ratings were better in regions with a higher physician density compared to regions with a lower number of physicians (average rating: 2.16 vs. 2.67; p<0.001). Online ratings of dermatologists and ENT specialists hardly differ in terms of regional physician density. Physician-rating websites thus do not appear to be appropriate to mirror differences in the health service delivery structure. Our findings thus do not confirm the

Measurement of fatigue crack growth rate of reactor structural material in air based on DCPD method

International Nuclear Information System (INIS)

Du Donghai; Chen Kai; Yu Lun; Zhang Lefu; Shi Xiuqiang; Xu Xuelian

2014-01-01

The principles and details of direct current potential drop (DCPD) in monitoring the crack growth of reactor structural materials was introduced in this paper. Based on this method, the fatigue crack growth rate (CGR) of typical structural materials in nuclear power systems was measured. The effects of applied load, load ratio and loading frequency on the fatigue crack growth rate of reactor structural materials were discussed. The result shows that the fatigue crack growth rate of reactor structural materials depends on the hardness of materials, and the harder the material is, the higher the rate of crack growth is. (authors)

In pursuit of tax equity: lessons from VAT rate structure adjustment in Poland

Directory of Open Access Journals (Sweden)

Artur Świstak

2015-06-01

Full Text Available In 2011, in the aftermath of the economic crisis, Poland increased its value added tax rates. Despite an already large VAT policy gap, further rate differentiation was used to address distributional concerns and to protect the most vulnerable households. We find that the changes to the VAT rate structure hardly improved the overall progressivity of the VAT and the tax system as a whole. While providing only minimal relief to the poor, taxation of food products at a super reduced rate greatly subsidized the richer households. With a small change to the income tax structure, the government could have secured more progressivity at a lower cost in terms of revenue foregone.

Understanding twinning nucleation and dislocation core structure through interscale hybrid method

DEFF Research Database (Denmark)

Xu, Ben; Zhang, Xiaodan

2014-01-01

The variety of emerging simulation methods and improved computational power advance the understanding in nanometals as a good compensation of the experiments. In this paper, the first principle methods are discussed, especially as a useful combination of the classical molecular dynamics, to overc......, to overcome the disadvantages of the latter method. Two examples are given as: the nucleation of the {10-12} deformation twinning in magnesium, and the screw dislocation core structure with/without hydrogen in tungsten....

Understanding the biological activity of high rate algae ponds through the calculation of oxygen balances.

Science.gov (United States)

Arbib, Zouhayr; de Godos Crespo, Ignacio; Corona, Enrique Lara; Rogalla, Frank

2017-06-01

Microalgae culture in high rate algae ponds (HRAP) is an environmentally friendly technology for wastewater treatment. However, for the implementation of these systems, a better understanding of the oxygenation potential and the influence of climate conditions is required. In this work, the rates of oxygen production, consumption, and exchange with the atmosphere were calculated under varying conditions of solar irradiance and dilution rate during six months of operation in a real scale unit. This analysis allowed determining the biological response of these dynamic systems. The rates of oxygen consumption measured were considerably higher than the values calculated based on the organic loading rate. The response to light intensity in terms of oxygen production in the bioreactor was described with one of the models proposed for microalgae culture in dense concentrations. This model is based on the availability of light inside the culture and the specific response of microalgae to this parameter. The specific response to solar radiation intensity showed a reasonable stability in spite of the fluctuations due to meteorological conditions. The methodology developed is a useful tool for optimization and prediction of the performance of these systems.

Do Students Understand Our Course Structure? Implications for Important Classroom Attitudes and Behavior

Science.gov (United States)

Elicker, Joelle D.; Foust, Michelle Singer; Perry, Jennifer L.

2015-01-01

The complexity of a course's structure may influence how well students understand what is expected of them. Using the foundation of the industrial/organizational (I/O) psychology literature, the authors modified a measure of "Perceived System Knowledge" (Williams & Levy, 1992) for employee performance appraisal to be appropriate for…

Understanding the structure of Exmoor's peatland ecosystems using laser-scanning technologies

Science.gov (United States)

Luscombe, D. J.; Anderson, K.; Wetherelt, A.; Grand-Clement, E.; Le-Feuvre, N.; Smith, D.; Brazier, R. E.

2012-04-01

Upland blanket peatlands in the UK are of high conservation value and in an intact state, provide important landscape services, such as carbon sequestration and flood attenuation. The drainage of many such wetlands for agricultural reclamation has resulted in changes to upland blanket mire topography, ecology, hydrological processes and carbon fluxes. There is a need for spatially explicit monitoring approaches at peatland sites in the UK as although there has been a national effort to restore drained peat uplands, baseline and post restoration monitoring of changes to ecosystem structure and function is largely absent. Climate change policy and the emerging carbon markets also necessitate the need for enhanced system understanding to inform carbon targets and understand the impacts of restoration. Exmoor is the focus of this research because many areas of upland peat have, in the past, been extensively drained through government "moorland reclamation" programs. A large restoration project funded by South West Water is currently underway in association with Exmoor National Park, The Environment Agency and Natural England. Exmoor also provides an analogue for other westerly peatlands in the British Isles in terms of its climate, ecology and drainage characteristics. Our approach employed airborne LiDAR data gathered by the Environment Agency Geomatics Group coupled with Terrestrial Laser Scanning (TLS) surveys. LiDAR data were processed to produce digital surface models (DSM) of the peatland surface at a 0.5m resolution. These data were further interrogated to separate vegetation structures and geomorphic features such as man-made drainage channels which have damaged the peatland. Over small extents the LiDAR derived DSM surface was then compared to a TLS derived DSM to examine the ability of these models to describe fine scale vegetation and geomorphic structure, which could then be extrapolated to larger spatial extents. Exploration of the data has shown that

Central Bank Communication Affects the Term-Structure of Interest Rates

Directory of Open Access Journals (Sweden)

Fernando Chague

2015-06-01

Full Text Available We empirically analyze how the Brazilian Central Bank (BCB communication affects the term structure of future interest rates. Using principal components analysis, we construct a measure of the Monetary Policy Committee Minutes content that reflects policy makers optimism about the economic conditions. We call this measure the Optimism Factor (OF. When policy makers are more optimistic, reflected by increments in the OF, markets expectations respond and long-term future interest rates drop. Furthermore, when policy makers are pessimistic, reflected by a decrease in the OF, volatility on future interest rates increases. Our result indicates that policy maker communication has an effective impact on market expectations.

Geometry effect on energy transfer rate in a coupled-quantum-well structure: nonlinear regime

International Nuclear Information System (INIS)

Salavati-fard, T; Vazifehshenas, T

2014-01-01

We study theoretically the effect of geometry on the energy transfer rate at nonlinear regime in a coupled-quantum-well system using the balance equation approach. To investigate comparatively the effect of both symmetric and asymmetric geometry, different structures are considered. The random phase approximation dynamic dielectric function is employed to include the contributions from both quasiparticle and plasmon excitations. Also, the short-range exchange interaction is taken into account through the Hubbard approximation. Our numerical results show that the energy transfer rate increases by increasing the well thicknesses in symmetric structures. Furthermore, by increasing spatial asymmetry, the energy transfer rate decreases for the electron temperature range of interest. From numerical calculations, it is obtained that the nonlinear energy transfer rate is proportional to the square of electron drift velocity in all structures and also, found that the influence of Hubbard local field correction on the energy transfer rate gets weaker by increasing the strength of applied electric field. (paper)

Understanding the effects of alpha self-irradiation on the glass structure by coupling spectroscopic studies and atomistic modeling

International Nuclear Information System (INIS)

Bureau, G.

2008-12-01

Our objective was to assess irradiation effects on nuclear containment glass in order to guarantee glass performance when subjected to high alpha decay doses. Experimental studies and molecular dynamics modeling provided a better understanding of the impact of cumulative alpha decay on the structural behavior of complex nuclear glass formulations and of simplified glass models. A mechanism typical of sodium borosilicate glass was identified in response to nuclear interactions or ballistic collisions. The glass local order is slightly modified by the conversion of a fraction of the boron atoms from coordination number IV to III, releasing charge-compensating alkali ions that become available as network modifiers, and resulting in a slight increase in the number of non bridging oxygen atoms. The medium-range order shifts toward increasing disorder in the glass as indicated by broadening of the angular, radial, and size distributions. A model of accumulated quasi-thermal quenching is proposed to account for these changes, based on the two steps describing the reaction of the glass to the alpha decay recoil nucleus: a cascade generates a ballistic phase that completely destabilizes the glass structure with no short and medium-range order, resulting in the loss of the initial structure; glass reconstruction is controlled only by the 'quenching rate' in the displacement cascade, i.e. by its thermal history and the corresponding relaxation options. From this standpoint the final glass structure is the consequence of the ballistic changes and the regenerative capacity of the glass structure, resulting in a higher fictive-temperature glass corresponding to the structural changes identified in this study. (author)

Estimating evolutionary rates using time-structured data: a general comparison of phylogenetic methods.

Science.gov (United States)

Duchêne, Sebastián; Geoghegan, Jemma L; Holmes, Edward C; Ho, Simon Y W

2016-11-15

In rapidly evolving pathogens, including viruses and some bacteria, genetic change can accumulate over short time-frames. Accordingly, their sampling times can be used to calibrate molecular clocks, allowing estimation of evolutionary rates. Methods for estimating rates from time-structured data vary in how they treat phylogenetic uncertainty and rate variation among lineages. We compiled 81 virus data sets and estimated nucleotide substitution rates using root-to-tip regression, least-squares dating and Bayesian inference. Although estimates from these three methods were often congruent, this largely relied on the choice of clock model. In particular, relaxed-clock models tended to produce higher rate estimates than methods that assume constant rates. Discrepancies in rate estimates were also associated with high among-lineage rate variation, and phylogenetic and temporal clustering. These results provide insights into the factors that affect the reliability of rate estimates from time-structured sequence data, emphasizing the importance of clock-model testing. sduchene@unimelb.edu.au or garzonsebastian@hotmail.comSupplementary information: Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

On the Information in the Interest Rate Term Structure and Option Prices

NARCIS (Netherlands)

de Jong, F.; Driessen, J.; Pelsser, A.

2004-01-01

We examine whether the information in cap and swaption prices is consistent with realized movements of the interest rate term structure. To extract an option-implied interest rate covariance matrix from cap and swaption prices, we use Libor market models as a modelling framework. We propose a

From patterns to causal understanding: Structural equation modeling (SEM) in soil ecology

Science.gov (United States)

Eisenhauer, Nico; Powell, Jeff R; Grace, James B.; Bowker, Matthew A.

2015-01-01

In this perspectives paper we highlight a heretofore underused statistical method in soil ecological research, structural equation modeling (SEM). SEM is commonly used in the general ecological literature to develop causal understanding from observational data, but has been more slowly adopted by soil ecologists. We provide some basic information on the many advantages and possibilities associated with using SEM and provide some examples of how SEM can be used by soil ecologists to shift focus from describing patterns to developing causal understanding and inspiring new types of experimental tests. SEM is a promising tool to aid the growth of soil ecology as a discipline, particularly by supporting research that is increasingly hypothesis-driven and interdisciplinary, thus shining light into the black box of interactions belowground.

Structural evolution of biomass char and its effect on the gasification rate

DEFF Research Database (Denmark)

Fatehi, Hesameddin; Bai, Xue Song

2017-01-01

The evolution of char porous structure can affect the conversion rate of the char by affecting the intra-particle transport, especially in the zone II conversion regime. A multi-pore model based on the capillary pore theory is developed to take into account different conversion rates for pores wi...

Rate-, temperature-, and structure-dependent yield kinetics of isotactic polypropylene

NARCIS (Netherlands)

Erp, van T.B.; Cavallo, D.; Peters, G.W.M.; Govaert, L.E.

2012-01-01

The influence of cooling rate on the structure and resulting mechanical performance is explored for a set of isotactic polypropylenes with varying molecular weight, insertion of counits, and addition of a nucleating agent. A continuous variation of crystal type (a–mesomorphic phase competition) and

General approach to understanding the electronic structure of graphene on metals

International Nuclear Information System (INIS)

Voloshina, E N; Dedkov, Yu S

2014-01-01

This manuscript presents the general approach to the understanding of the connection between bonding mechanism and electronic structure of graphene on metals. To demonstrate its validity, two limiting cases of ‘weakly’ and ‘strongly’ bonded graphene on Al(111) and Ni(111) are considered, where the Dirac cone is preserved or fully destroyed, respectively. Furthermore, the electronic structure, i.e. doping level, hybridization effects, as well as a gap formation at the Dirac point of the intermediate system, graphene/Cu(111), is fully understood in the framework of the proposed approach. This work summarises the long-term debates regarding connection of the bonding strength and the valence band modification in the graphene/metal systems and paves a way for the effective control of the electronic states of graphene in the vicinity of the Fermi level. (paper)

Functional understanding of the diverse exon-intron structures of human GPCR genes.

Science.gov (United States)

Hammond, Dorothy A; Olman, Victor; Xu, Ying

2014-02-01

The GPCR genes have a variety of exon-intron structures even though their proteins are all structurally homologous. We have examined all human GPCR genes with at least two functional protein isoforms, totaling 199, aiming to gain an understanding of what may have contributed to the large diversity of the exon-intron structures of the GPCR genes. The 199 genes have a total of 808 known protein splicing isoforms with experimentally verified functions. Our analysis reveals that 1301 (80.6%) adjacent exon-exon pairs out of the total of 1,613 in the 199 genes have either exactly one exon skipped or the intron in-between retained in at least one of the 808 protein splicing isoforms. This observation has a statistical significance p-value of 2.051762 * e(-09), assuming that the observed splicing isoforms are independent of the exon-intron structures. Our interpretation of this observation is that the exon boundaries of the GPCR genes are not randomly determined; instead they may be selected to facilitate specific alternative splicing for functional purposes.

Understanding the structure of nanocatalysts with high resolution scanning/transmission electron microscopy

International Nuclear Information System (INIS)

Francis, L D; Rivas, J; José-Yacamán, M

2014-01-01

Nanomaterials including nanoparticles, nanowires and nanotubes play an important role in heterogeneous catalysis. Thanks to the rapid improvement of the electron microscopic techniques and with the advent of aberration corrected electron microscopy as well as theoretical methodologies, the potential effects induced by nanocatalysts are better understood than before by unravelling their atomic structure. A brief introduction to advanced electron microscopic techniques namely aberration corrected scanning transmission electron microscopy (Cs-STEM) is presented and subsequently two examples of nanocatalysts are considered in the present review. The first example will focus on the study of bimetallic/core-shell nanoalloys. In heterogeneous catalysis, catalysts containing two or more metals might show significantly different catalytic properties compared to the parent metals and thus are widely utilized in several catalytic reactions. Atom-by-atom insights of the nanoalloy based catalysts ex: Au-Pd will be described in the present review using a combination of advanced electron microscopic and spectroscopic techniques. A related example on the understanding of bimetallic clusters by HAADF-STEM will also be presented in addition to nanoparticles. In the second case understanding the structure of transition metal chalcogenide based nanocatalysts by HRTEM and aberration corrected STEM, for the case of MoS 2 will be discussed. MoS 2 -based catalysts serve as model catalysts and are employed in the hydrodesulphurisations (HDS) reactions in the removal of sulphur from gasoline and related petrochemical products. They have been studied in various forms including nanowires, nanotubes and nanoplates. Their structure, atomic insights and as a consequence elucidation of their corresponding catalytic activity are thus important

Impact of Alternative Rate Structures on Distributed Solar Customer Electricity Bills

Energy Technology Data Exchange (ETDEWEB)

McLaren, Joyce A [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-03-02

Electric utilities are increasingly proposing changes to residential rate structures, in order to address concerns about their inability to recover fixed system costs from customers with grid connected distributed generation. The most common proposals have been to increase fixed charges, set minimum bills or instigate residential demand charges. This presentation provides results of an analysis to explore how these rate design alternatives impact electricity bills for PV and non-PV customers.

Investigating the Effectiveness of Case-based Learning Instruction on Students’ Understanding the Subject of Reaction Rate

Directory of Open Access Journals (Sweden)

Aysel Ünal SÜMEN

2015-04-01

Full Text Available This study has been carried out to determine the effectiveness of case-based learning related to reaction rate on students’ conceptual understanding and conceptual change. In this respect, a class of 11th grade students in an Anatolian High School in the center of Izmir city was chosen randomly as experimental group (n=26 and another as control group (n=22. Reaction rate unit was taught to the experimental group within case-based learning method, and to the control group through activities defined in Chemistry curriculum. Comprehension Test developed by Cakmakci (2005 was utilized as data collecting instrument. The Comprehension Test was applied simultaneously to both experimental and control groups before and after the teaching. The data collected via the Comprehension Test was analyzed in terms of both quantity and quality. As a result of the study, it was noted that there was a significant difference between the groups after the instruction in favor of the experimental group. Also, it was determined that case-based learning was more effective in promoting conceptual change and assuring higher level of conceptual understanding for students.

The term structure of interest rates and inflation forecast targeting

Directory of Open Access Journals (Sweden)

Eric Schaling

2011-08-01

Full Text Available This paper examines the implications of the expectations theory of the term structure of interest rates for the implementation of inflation targeting. We show that the responsiveness of the central bank’s instrument to the underlying state of the economy is increasing in the duration of the long-term bond.  On the other hand, an increase in duration will make long-term inflationary expectations - and therefore also the long-term nominal interest rate - less responsive to the state of the economy. The extent to which the central bank is concerned with output stabilisation will exert a moderating influence on the central bank’s response to leading indicators of future inflation. However, the effect of an increase in this parameter on the long-term nominal interest rate turns out to be ambiguous. Next, we show that both the sensitivity of the nominal term spread to economic fundamentals and the extent to which the spread predicts future output, are increasing in the duration of the long bond and the degree of structural output persistence. However, if the central bank becomes relatively less concerned about inflation stabilisation the term spread will be less successful in predicting real economic activity.

A Model of Target Changes and the Term Structure of Interest Rates

OpenAIRE

Pierluigi Balduzzi; Giuseppe Bertola; Silverio Foresi

1993-01-01

We explore the effects of official targeting policy on the term-structure of nominal interest rates, adapting relevant insights from theoretical work on "peso problems" to account for realistic infrequency of target changes. Our analysis of daily U.S. interest rates and newly available historical targets provides an interpretation for persistent spreads between short-term money-market rates and overnight fed-funds targets, and for the poor performance of expectations-hypothesis tests: it is t...

Structure correlation and chemistry

International Nuclear Information System (INIS)

Buergi, H.B.

1998-01-01

The main goal of crystal and molecular structure determination is to provide a starting point for understanding the physical, chemical and biological properties of matter. At present, results from nearly 300000 crystal structure studies are available in computer-readable form. Structure correlation attempts to extract knowledge and understanding from this body of information, which is not available from its parts. This article reviews some typical examples: libraries of prototypal molecular dimensions, mappings of chemical reaction pathways, correlations between structure on one hand and energy, reaction rate, catalytic activity or magnetism on the other. The knowledge gained from structure-correlation studies, together with quantum-chemical and other modeling techniques, provides conceptual and practical tools for designing molecules and materials with tailor-made properties. (orig.)

Rate Dependent Multicontinuum Progressive Failure Analysis of Woven Fabric Composite Structures under Dynamic Impact

Directory of Open Access Journals (Sweden)

James Lua

2004-01-01

Full Text Available Marine composite materials typically exhibit significant rate dependent response characteristics when subjected to extreme dynamic loading conditions. In this work, a strain-rate dependent continuum damage model is incorporated with multicontinuum technology (MCT to predict damage and failure progression for composite material structures. MCT treats the constituents of a woven fabric composite as separate but linked continua, thereby allowing a designer to extract constituent stress/strain information in a structural analysis. The MCT algorithm and material damage model are numerically implemented with the explicit finite element code LS-DYNA3D via a user-defined material model (umat. The effects of the strain-rate hardening model are demonstrated through both simple single element analyses for woven fabric composites and also structural level impact simulations of a composite panel subjected to various impact conditions. Progressive damage at the constituent level is monitored throughout the loading. The results qualitatively illustrate the value of rate dependent material models for marine composite materials under extreme dynamic loading conditions.

Big bang nucleosynthesis with a varying fine structure constant and nonstandard expansion rate

International Nuclear Information System (INIS)

Ichikawa, Kazuhide; Kawasaki, Masahiro

2004-01-01

We calculate the primordial abundances of light elements produced during big bang nucleosynthesis when the fine structure constant and/or the cosmic expansion rate take nonstandard values. We compare them with the recent values of observed D, 4 He, and 7 Li abundances, which show a slight inconsistency among themselves in the standard big bang nucleosynthesis scenario. This inconsistency is not solved by considering either a varying fine structure constant or a nonstandard expansion rate separately but solutions are found by their simultaneous existence

Application of characterization, modelling, and analytics towards understanding process-structure linkages in metallic 3D printing

Science.gov (United States)

Groeber, M. A.; Schwalbach, E.; Donegan, S.; Chaput, K.; Butler, T.; Miller, J.

2017-07-01

This paper presents methods for combining process monitoring, thermal modelling and microstructure characterization together to draw process-to-structure relationships in metal additive manufacturing. The paper discusses heterogeneities in the local processing conditions within additively manufactured components and how they affect the resulting material structure. Methods for registering and fusing disparate data sources are presented, and some effort is made to discuss the utility of different data sources for specific microstructural features of interest. It is the intent that this paper will highlight the need for improved understanding of metallic additive manufacturing processes and show that combining experimental data with modelling and advanced data processing and analytics methods will accelerate that understanding.

Energy structure, marginal efficiency and substitution rate: An empirical study of China

International Nuclear Information System (INIS)

Han Zhiyong; Fan Ying; Jiao Jianling; Yan Jisheng; Wei Yiming

2007-01-01

Energy efficiency is an important factor in developing energy policies as it represents the extent to which resources support economic output. In recent literature, relevant studies have mainly focused on aggregate energy efficiency, but rarely touched on the marginal efficiency of diverse energy resources and their comparative substitution rate. During 1978-2003, China's energy efficiency continually increased; and consequently became a hot topic in contemporary literature. However, there is no empirical study on the relationship between energy structure and energy efficiency. In order to close the gap, this paper reports the empirical study of the impact of China's energy structure on its energy efficiency from 1978 to 2003. The work covered primary estimation of the marginal efficiency of coal and petroleum in China, as well as the comparative substitution rate. Results indicate that the substitution rate between petroleum and coal is a factor of 5.38

Application of first order rate kinetics to explain changes in bloom toxicity—the importance of understanding cell toxin quotas

Science.gov (United States)

Orr, Philip T.; Willis, Anusuya; Burford, Michele A.

2018-04-01

Cyanobacteria are oxygenic photosynthetic Gram-negative bacteria that can form potentially toxic blooms in eutrophic and slow flowing aquatic ecosystems. Bloom toxicity varies spatially and temporally, but understanding the mechanisms that drive these changes remains largely a mystery. Changes in bloom toxicity may result from changes in intracellular toxin pool sizes of cyanotoxins with differing molecular toxicities, and/or from changes in the cell concentrations of toxic and non-toxic cyanobacterial species or strains within bloom populations. We show here how first-order rate kinetics at the cellular level can be used to explain how environmental conditions drive changes in bloom toxicity at the ecological level. First order rate constants can be calculated for changes in cell concentration (μ c: specific cell division rate) or the volumetric biomass concentration (μ g: specific growth rate) between short time intervals throughout the cell cycle. Similar first order rate constants can be calculated for changes in nett volumetric cyanotoxin concentration (μ tox: specific cyanotoxin production rate) over similar time intervals. How μ c (or μ g ) covaries with μ tox over the cell cycle shows conclusively when cyanotoxins are being produced and metabolised, and how the toxicity of cells change in response to environment stressors. When μ tox/μ c>1, cyanotoxin cell quotas increase and individual cells become more toxic because the nett cyanotoxin production rate is higher than the cell division rate. When μ tox/μ c=1, cell cyanotoxin quotas remains fixed because the nett cyanotoxin production rate matches the cell division rate. When μ tox/μ ccyanotoxin cell quota decreases because either the nett cyanotoxin production rate is lower than the cell division rate, or metabolic breakdown and/or secretion of cyanotoxins is occurring. These fundamental equations describe cyanotoxin metabolism dynamics at the cellular level and provide the necessary

Structural evolution of biomass char and its effect on the gasification rate

International Nuclear Information System (INIS)

Fatehi, Hesameddin; Bai, Xue-Song

2017-01-01

Highlights: • A comprehensive model was developed to describe the evolution of biomass char structure. • An effectiveness factor was used to account for the intra-particle chemical and physical processes. • The effect of the structural evolution of the multi-pore structure on biomass char reactivity was analyzed. • The multi-pore model yields results in satisfactory agreement with experiments. - Abstract: The evolution of char porous structure can affect the conversion rate of the char by affecting the intra-particle transport, especially in the zone II conversion regime. A multi-pore model based on the capillary pore theory is developed to take into account different conversion rates for pores with different radii. The model is valid for biomass chars produced under relatively low heating rates, when the original beehive structure of the biomass is not destroyed during the pyrolysis stage. The contribution of different pores with different radius is taken into account using an effectiveness factor presented for each pore radius with respect to different reactions. As the char conversion proceeds, the pore enlargement increases the contribution of micro-pores; consequently the effective surface area will increase. The increase in the effective surface area leads to an increased reactivity of char during the entire conversion process. This model is used to analyze the steam gasification process of biomass char of centimeter sizes. The results from the present multi-pore model are in better agreement with experimental data than those from a corresponding single pore model. Since the multi-pore model accommodates the detailed intra-particle transport, it is a useful basis toward developing a more predictive model for biomass char gasification.

Corporate Governance Rating and Ownership Structure in the Case of Turkey

Directory of Open Access Journals (Sweden)

Sevin Gurarda

2016-04-01

Full Text Available By using corporate governance data on 22 publicly traded Turkish companies we estimate the determinants of corporate governance ratings for these companies with a focus on ownership structure. Our results show that company earnings, financial risk and firm size positively influence the corporate governance ratings (CGR that Turkish firms receive. In the meantime, we find some weak evidence that family ownership has a negative and foreign ownership has a positive impact on CGR scores.

Modeling the Interest Rate Term Structure: Derivatives Contracts Dynamics and Evaluation

Directory of Open Access Journals (Sweden)

Pedro L. Valls Pereira

2005-06-01

Full Text Available This article deals with a model for the term structure of interest rates and the valuation of derivative contracts directly dependent on it. The work is of a theoretical nature and deals, exclusively, with continuous time models, making ample use of stochastic calculus results and presents original contributions that we consider relevant to the development of the fixed income market modeling. We develop a new multifactorial model of the term structure of interest rates. The model is based on the decomposition of the yield curve into the factors level, slope, curvature, and the treatment of their collective dynamics. We show that this model may be applied to serve various objectives: analysis of bond price dynamics, valuation of derivative contracts and also market risk management and formulation of operational strategies which is presented in another article.

Active vision and image/video understanding with decision structures based on the network-symbolic models

Science.gov (United States)

Kuvich, Gary

2003-08-01

Vision is a part of a larger information system that converts visual information into knowledge structures. These structures drive vision process, resolve ambiguity and uncertainty via feedback projections, and provide image understanding that is an interpretation of visual information in terms of such knowledge models. The ability of human brain to emulate knowledge structures in the form of networks-symbolic models is found. And that means an important shift of paradigm in our knowledge about brain from neural networks to "cortical software". Symbols, predicates and grammars naturally emerge in such active multilevel hierarchical networks, and logic is simply a way of restructuring such models. Brain analyzes an image as a graph-type decision structure created via multilevel hierarchical compression of visual information. Mid-level vision processes like clustering, perceptual grouping, separation of figure from ground, are special kinds of graph/network transformations. They convert low-level image structure into the set of more abstract ones, which represent objects and visual scene, making them easy for analysis by higher-level knowledge structures. Higher-level vision phenomena are results of such analysis. Composition of network-symbolic models works similar to frames and agents, combines learning, classification, analogy together with higher-level model-based reasoning into a single framework. Such models do not require supercomputers. Based on such principles, and using methods of Computational intelligence, an Image Understanding system can convert images into the network-symbolic knowledge models, and effectively resolve uncertainty and ambiguity, providing unifying representation for perception and cognition. That allows creating new intelligent computer vision systems for robotic and defense industries.

The contribution of solid-state NMR spectroscopy to understanding biomineralization: Atomic and molecular structure of bone

Science.gov (United States)

Duer, Melinda J.

2015-04-01

Solid-state NMR spectroscopy has had a major impact on our understanding of the structure of mineralized tissues, in particular bone. Bone exemplifies the organic-inorganic composite structure inherent in mineralized tissues. The organic component of the extracellular matrix in bone is primarily composed of ordered fibrils of collagen triple-helical molecules, in which the inorganic component, calcium phosphate particles, composed of stacks of mineral platelets, are arranged around the fibrils. This perspective argues that key factors in our current structural model of bone mineral have come about through NMR spectroscopy and have yielded the primary information on how the mineral particles interface and bind with the underlying organic matrix. The structure of collagen within the organic matrix of bone or any other structural tissue has yet to be determined, but here too, this perspective shows there has been real progress made through application of solid-state NMR spectroscopy in conjunction with other techniques. In particular, NMR spectroscopy has highlighted the fact that even within these structural proteins, there is considerable dynamics, which suggests that one should be cautious when using inherently static structural models, such as those arising from X-ray diffraction analyses, to gain insight into molecular roles. It is clear that the NMR approach is still in its infancy in this area, and that we can expect many more developments in the future, particularly in understanding the molecular mechanisms of bone diseases and ageing.

Risks and rewards of variable-rate debt.

Science.gov (United States)

Jordahl, Eric A

2012-05-01

Hospital and health system finance leaders should position their organizations to participate in the variable-rate market. To this end, one important step is to establish the right baseline variable-rate exposure target for the organization based on its credit and risk profile. Leaders also should be thoroughly familiar with the available products and understand the circumstances (pricing, terms, and embedded risk) under which the organization would be willing to deploy them within the overall capital structure.

Overnight weight loss: relationship with sleep structure and heart rate variability

OpenAIRE

Walter Moraes; Dalva Poyares; Christian Guilleminault; Agostinho Rosa; Marco Tulio Mello; Adriana Rueda; Sergio Tufik

2008-01-01

Background: Weight loss can be caused by a loss of body mass due to metabolism and by water loss as unsensible water loss, sweating, or excretion in feces and urine. Although weight loss during sleep is a well-known phenomenon, it has not yet been studied in relation to sleep structure or autonomic tonus during sleep. Our study is proposed to be a first step in assessing the relationship between overnight weight loss, sleep structure, and HRV (heart rate variability) parameters.Methods: Twent...

Establishing the solubility and local structure(s) of Amorphous Calcium Carbonate (ACC): Toward an understanding of invertebrate biomineralization

Science.gov (United States)

Mergelsberg, S. T.; Ulrich, R. N.; Michel, F. M.; Dove, P. M.

2017-12-01

Recent advances in high-resolution imaging show the widespreadd occurrence of multistep pathways to mineralization in biological and geological settings (De Yoreo et al., 2015, Science). For example, carbonate biomineralization often involves precipitation of amorphous calcium carbonate (ACC) as a reactive intermediate that subsequently transforms to crystalline products with diverse structures. Although current carbonate mineral proxies are based upon the composition of final crystalline products, the final signatures may be recording the properties of the initial amorphous phase. Thus, it is critical to establish the physical properties of ACC and understand the factors that influence its evolution to final products at conditions that approximate biological environments. This disconnect limits our ability to build a process-based understanding of when/how minor and trace elements are recorded in mineral composition proxies. In this experimental study, we quantified the chemical and physical properties of ACC and its evolution to final products. We first determined ACC solubility under controlled chemical conditions using a new type of flow-through reactor developed by our research group (Blue and Dove, 2015, GCA; Blue et al., 2017, GCA). The experimental design varied Mg concentration and total alkalinity while maintaining a mild pH that approximates biological environments. ACC solubility was measured at specific time points during the precipitation (from super- and undersaturated conditions) and during its subsequent evolution. Parallel experiments characterized the structure of the corresponding amorphous products using in situ pair distribution function (PDF) and small-angle x-ray scattering (SAXS) analyses. The measurements demonstrate at least two types of ACC can be produced by tuning Mg concentration and alkalinity. Each "phase" exhibits distinct short-range ordering that demonstrates structure-specific solubility. We also find temporal changes in the

UNDERSTANDING THE STRUCTURE OF THE HOT INTERSTELLAR MEDIUM IN NORMAL EARLY-TYPE GALAXIES.

Science.gov (United States)

Traynor, Liam; Kim, Dong-Woo; Chandra Galaxy Atlas

2018-01-01

The hot interstellar medium (ISM) of early-type galaxies (ETG's) provides crucial insight into the understanding of their formation and evolution. Mechanisms such as type Ia supernovae heating, AGN feedback, deepening potential depth through dark matter assembly and ramp-pressure stripping are known to affect the structure of the ISM. By using temperature maps and radial temperature profiles of the hot ISM from ~70 ETG's with archival Chandra data, it is possible to classify the galaxy's ISM into common structural types. This is extended by using 3D fitting of the radial temperature profile in order to provide models that further constrain the structural types. Five structural types are present, negative (temperature decreases with radii), positive (temperature increases with radii), hybrid-dip (temperature decreases at small radii and increases at large radii), hybrid-bump (inverse of hybrid-dip) and quasi-isothermal (temperature is constant at all radii). This work will be continued by 1) determining which mechanisms are present in which galaxies and 2) analysing the model parameters between galaxies within each structural type to determine whether each type can be described by a single set of model parameters, indicating that the same physical processes are responsible for creating that structural type.

Two-band tariff for domestic use: Italian Electricity Board rate structure

International Nuclear Information System (INIS)

Barteselli, R.

1992-01-01

ENEL (the Italian National Electricity Board) has begun to introduce a new rate structure for households: the 'two-band tariff'. This article is an effort to examine in principle how the new tariff could optimize load management when applied to the whole household sector

Risk management under a two-factor model of the term structure of interest rates

OpenAIRE

Manuel Moreno

1997-01-01

This paper presents several applications to interest rate risk management based on a two-factor continuous-time model of the term structure of interest rates previously presented in Moreno (1996). This model assumes that default free discount bond prices are determined by the time to maturity and two factors, the long-term interest rate and the spread (difference between the long-term rate and the short-term (instantaneous) riskless rate). Several new measures of ``generalized duration" are p...

Understanding of radiation effect on sink in aluminum base structure materials

International Nuclear Information System (INIS)

Choi, Sang Il; Kim, Ji Hyun

2014-01-01

In case of aluminum, a slightly different approach is needed for the evaluation of radiation damage. Unlikely other structure materials such as zirconium alloy and iron based alloy, aluminum generate not only matrix defect but also much transmutation. Quantitative analysis of radiation damage of aluminum have been done in two research method. First research method is calculation of radiation damage quantity in the matrix. In this research, quantity of transmutation and matrix damage are evaluated by KMC simulation from ENDF database of IAEA. Most recently, radiation damage such as defect and transmutation are calculated in the MNSR reactor environment. The second research method is evaluation of sink morphology change by irradiation, which research method focus on accumulating behavior of radiation defects. Matrix defect and transmutation are clustering or dissolved by thermal diffusion and energy statue. These clustering defect such as dislocation loop, void and bubble directly affect mechanical properties. In this research area, it is hard to using deterministic method because it should describe envious and various reaction module in detail. However, in case of probabilistic method, it could be explained without detail reaction module. Most recently, there was KMC modeling about vacancy and helium cluster. From this cluster modeling, transmutation is quantitatively analyzed. After that cluster effect on swelling are explained. Unfortunately, silicon, which is another transmutation of aluminum, effect are neglected. Also primary cluster, which is generated by cascade, effect are neglected. For the fundamental understanding of radiation effect on aluminum alloy, it is needed that more various parameter such as alloy element and primary cluster effect should be researched. However, until now there was not general modeling which include alloy element and primary cluster effect on aluminum. However, there was not specified KMC platform for the quantitative analysis of

Understanding molecular structure from molecular mechanics.

Science.gov (United States)

Allinger, Norman L

2011-04-01

Molecular mechanics gives us a well known model of molecular structure. It is less widely recognized that valence bond theory gives us structures which offer a direct interpretation of molecular mechanics formulations and parameters. The electronic effects well-known in physical organic chemistry can be directly interpreted in terms of valence bond structures, and hence quantitatively calculated and understood. The basic theory is outlined in this paper, and examples of the effects, and their interpretation in illustrative examples is presented.

Calibration of short rate term structure models from bid-ask coupon bond prices

Science.gov (United States)

Gomes-Gonçalves, Erika; Gzyl, Henryk; Mayoral, Silvia

2018-02-01

In this work we use the method of maximum entropy in the mean to provide a model free, non-parametric methodology that uses only market data to provide the prices of the zero coupon bonds, and then, a term structure of the short rates. The data used consists of the prices of the bid-ask ranges of a few coupon bonds quoted in the market. The prices of the zero coupon bonds obtained in the first stage, are then used as input to solve a recursive set of equations to determine a binomial recombinant model of the short term structure of the interest rates.

Understanding and Improving High-Temperature Structural Properties of Metal-Silicide Intermetallics

Energy Technology Data Exchange (ETDEWEB)

Bruce S. Kang

2005-10-10

The objective of this project was to understand and improve high-temperature structural properties of metal-silicide intermetallic alloys. Through research collaboration between the research team at West Virginia University (WVU) and Dr. J.H. Schneibel at Oak Ridge National Laboratory (ORNL), molybdenum silicide alloys were developed at ORNL and evaluated at WVU through atomistic modeling analyses, thermo-mechanical tests, and metallurgical studies. In this study, molybdenum-based alloys were ductilized by dispersing MgAl2O4 or MgO spinel particles. The addition of spinel particles is hypothesized to getter impurities such as oxygen and nitrogen from the alloy matrix with the result of ductility improvement. The introduction of fine dispersions has also been postulated to improve ductility by acting as a dislocation source or reducing dislocation pile-ups at grain boundaries. The spinel particles, on the other hand, can also act as local notches or crack initiation sites, which is detrimental to the alloy mechanical properties. Optimization of material processing condition is important to develop the desirable molybdenum alloys with sufficient room-temperature ductility. Atomistic analyses were conducted to further understand the mechanism of ductility improvement of the molybdenum alloys and the results showed that trace amount of residual oxygen may be responsible for the brittle behavior of the as-cast Mo alloys. For the alloys studied, uniaxial tensile tests were conducted at different loading rates, and at room and elevated temperatures. Thermal cycling effect on the mechanical properties was also studied. Tensile tests for specimens subjected to either ten or twenty thermal cycles were conducted. For each test, a follow-up detailed fractography and microstructural analysis were carried out. The test results were correlated to the size, density, distribution of the spinel particles and processing time. Thermal expansion tests were carried out using thermo

Making Sense of Abstract Algebra: Exploring Secondary Teachers' Understandings of Inverse Functions in Relation to Its Group Structure

Science.gov (United States)

Wasserman, Nicholas H.

2017-01-01

This article draws on semi-structured, task-based interviews to explore secondary teachers' (N = 7) understandings of inverse functions in relation to abstract algebra. In particular, a concept map task is used to understand the degree to which participants, having recently taken an abstract algebra course, situated inverse functions within its…

Impact on breeding rate of different Molten Salt reactor core structures

International Nuclear Information System (INIS)

Wang Haiwei; Mei Longwei; Cai Xiangzhou; Chen Jingen; Guo Wei; Jiang Dazhen

2013-01-01

Background: Molten Salt Reactor (MSR) has several advantages over the other Generation IV reactor. Referred to the French CNRS research and compared to the fast reactor, super epithermal neutron spectrum reactor type is slightly lower and beading rate reaches 1.002. Purpose: The aim is to explore the best conversion zone layout scheme in the super epithermal neutron spectrum reactor. This study can make nuclear fuel as one way to solve the energy problems of mankind in future. Methods: Firstly, SCALE program is used for molten salt reactor graphite channel, molten salt core structure, control rods, graphite reflector and layer cladding structure. And the SMART modules are used to record the important actinides isotopes and their related reaction values of each reaction channel. Secondly, the thorium-uranium conversion rate is calculated. Finally, the better molten salt reactor core optimum layout scheme is studied comparing with various beading rates. Results: Breading zone layout scheme has an important influence on the breading rate of MSR. Central graphite channels in the core can get higher neutron flux irradiation. And more 233 Th can convert to 233 Pa, which then undergoes beta decay to become 233 U. The graphite in the breading zone gets much lower neutron flux irradiation, so the life span of this graphite can be much longer than that of others. Because neutron flux irradiation in the uranium molten salt graphite has nearly 10 times higher than the graphite in the breading zone, it has great impact on the thorium-uranium conversion rates. For the super epithermal neutron spectrum molten salt reactors, double salt design cannot get higher thorium-uranium conversion rates. The single molten salt can get the same thorium-uranium conversion rate, meanwhile it can greatly extend the life of graphite in the core. Conclusions: From the analysis of calculation results, Blanket breeding area in different locations in the core can change the breeding rates of thorium

Rate Structures for Customers With Onsite Generation: Practice and Innovation

Energy Technology Data Exchange (ETDEWEB)

Johnston, L.; Takahashi, K.; Weston, F.; Murray, C.

2005-12-01

Recognizing that innovation and good public policy do not always proclaim themselves, Synapse Energy Economics and the Regulatory Assistance Project, under a contract with the California Energy Commission (CEC) and the National Renewable Energy Laboratory (NREL), undertook a survey of state policies on rates for partial-requirements customers with onsite distributed generation. The survey investigated a dozen or so states. These varied in geography and the structures of their electric industries. By reviewing regulatory proceedings, tariffs, publications, and interviews, the researchers identified a number of approaches to standby and associated rates--many promising but some that are perhaps not--that deserve policymakers' attention if they are to promote the deployment of cost-effective DG in their states.

"Very Good" Ratings in a Survey of Maternity Care: Kindness and Understanding Matter to Australian Women.

Science.gov (United States)

Todd, Angela L; Ampt, Amanda J; Roberts, Christine L

2017-03-01

Surveys have shown that women are highly satisfied with their maternity care. Their satisfaction has been associated with various demographic, personal, and care factors. Isolating the factors that most matter to women about their care can guide quality improvement efforts. This study aimed to identify the most significant factors associated with high ratings of care by women in the three maternity periods (antenatal, birth, and postnatal). A survey was sent to 2,048 women who gave birth at seven public hospitals in New South Wales, Australia, exploring their expectations of, and experiences with maternity care. Women's overall ratings of care for the antenatal, birth, and postnatal periods were analyzed, and a number of maternal characteristics and care factors examined as potential predictors of "Very good" ratings of care. Among 886 women with a completed survey, 65 percent assigned a "Very good" rating for antenatal care, 74 percent for birth care, 58 percent for postnatal care, and 44 percent for all three periods. One factor was strongly associated with care ratings in all three maternity periods: women who were "always or almost always" treated with kindness and understanding were 1.8-2.8 times more likely to rate their antenatal, birth, and postnatal care as "Very good." A limited number of other factors were significantly associated with high care ratings for one or two of the maternity periods. Women's perceptions about the quality of their interpersonal interactions with health caregivers have a significant bearing on women's views about their maternity care journey. © 2016 Wiley Periodicals, Inc.

Understanding Boron through Size-Selected Clusters: Structure, Chemical Bonding, and Fluxionality

Energy Technology Data Exchange (ETDEWEB)

Sergeeva, Alina P.; Popov, Ivan A.; Piazza, Zachary A.; Li, Wei-Li; Romanescu, Constantin; Wang, Lai S.; Boldyrev, Alexander I.

2014-04-15

Conspectus Boron is an interesting element with unusual polymorphism. While three-dimensional (3D) structural motifs are prevalent in bulk boron, atomic boron clusters are found to have planar or quasi-planar structures, stabilized by localized two-center–two-electron (2c–2e) σ bonds on the periphery and delocalized multicenter–two-electron (nc–2e) bonds in both σ and π frameworks. Electron delocalization is a result of boron’s electron deficiency and leads to fluxional behavior, which has been observed in B13+ and B19–. A unique capability of the in-plane rotation of the inner atoms against the periphery of the cluster in a chosen direction by employing circularly polarized infrared radiation has been suggested. Such fluxional behaviors in boron clusters are interesting and have been proposed as molecular Wankel motors. The concepts of aromaticity and antiaromaticity have been extended beyond organic chemistry to planar boron clusters. The validity of these concepts in understanding the electronic structures of boron clusters is evident in the striking similarities of the π-systems of planar boron clusters to those of polycyclic aromatic hydrocarbons, such as benzene, naphthalene, coronene, anthracene, or phenanthrene. Chemical bonding models developed for boron clusters not only allowed the rationalization of the stability of boron clusters but also lead to the design of novel metal-centered boron wheels with a record-setting planar coordination number of 10. The unprecedented highly coordinated borometallic molecular wheels provide insights into the interactions between transition metals and boron and expand the frontier of boron chemistry. Another interesting feature discovered through cluster studies is boron transmutation. Even though it is well-known that B–, formed by adding one electron to boron, is isoelectronic to carbon, cluster studies have considerably expanded the possibilities of new structures and new materials using the B�

How relevant are assembled equilibrium samples in understanding structure formation during lipid digestion?

Science.gov (United States)

Phan, Stephanie; Salentinig, Stefan; Hawley, Adrian; Boyd, Ben J

2015-10-01

Lipid-based formulations are gaining interest for use as drug delivery systems for poorly water-soluble drug compounds. During digestion, the lipolysis products self-assemble with endogenous surfactants in the gastrointestinal tract to form colloidal structures, enabling enhanced drug solubilisation. Although earlier studies in the literature focus on assembled equilibrium systems, little is known about structure formation under dynamic lipolysis conditions. The purpose of this study was to investigate the likely colloidal structure formation in the small intestine after the ingestion of lipids, under equilibrium and dynamic conditions. The structural aspects were studied using small angle X-ray scattering and dynamic light scattering, and were found to depend on lipid composition, lipid chain length, prandial state and emulsification. Incorporation of phospholipids and lipolysis products into bile salt micelles resulted in swelling of the structure. At insufficient bile salt concentrations, a co-existing lamellar phase was observed, due to a reduction in the solubilisation capacity for lipolysis products. Emulsification accelerated the rate of lipolysis and structure formation. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparison of radiation and quenching rate effects on the structure of a sodium borosilicate glass

International Nuclear Information System (INIS)

Peuget, Sylvain; Maugeri, Emilio-Andrea; Mendoza, Clement; Fares, Toby; Bouty, Olivier; Jegou, Christophe; Charpentier, Thibault; Moskura, Melanie

2013-01-01

The effects of quenching rate and irradiation on the structure of a sodium borosilicate glass were compared using 29 Si, 11 B, and 23 Na nuclear magnetic resonance and Raman spectroscopy. Quenching rate ranging from 0.1 to 3 * 10 4 K min -1 was studied. Various irradiation conditions were performed, i.e. gold-ion irradiation in a multi-energy mode (from 1 to 6.75 MeV), and Kr and Xe ion irradiations with energy of 74 and 92 MeV, respectively. In pile irradiation with thermal neutron flux was performed as well, to study the effect of alpha radiation from the nuclear reaction 10 B(n,α) 7 Li. Both irradiation and high quenching rate induce similar local order modification of the glass structure, mainly a decrease of the mean boron coordination and an increase of Q 3 units. Nevertheless, the variations observed under irradiation are more pronounced than the ones induced by the quenching rate. Moreover, some important modifications of the glass medium range order, i.e. the emergence of the D2 band associated to three members silica rings and a modification of the Si-O-Si angle distribution were only noticed after irradiation. These results suggest that the irradiated structure is certainly not exactly the one obtained by a rapidly quenched equilibrated melt, but rather a more disordered structure that was weakly relaxed during the very rapid quenching phase following the energy deposition step. Raman spectroscopy showed a similar irradiated structure whereas the glass evolutions were controlled by the electronic energy loss in the ion track formation regime for Kr-ion irradiation or by the nuclear energy loss for Au and OSIRIS irradiation. The similar irradiated structure despite different irradiation routes, suggests that the final structural state of this sodium borosilicate glass is mainly controlled by the glass reconstruction after the energy deposition step. (authors)

Ecological Understanding 2: Transformation--A Key to Ecological Understanding.

Science.gov (United States)

Carlsson, Britta

2002-01-01

Describes the structure and general features of the phenomenon of ecological understanding. Presents qualitatively different ways of experiencing cycling of matter and the flow of energy in the context of ecosystems. The idea of transformation is key to the development of ecological understanding. (Contains 17 references.) (Author/YDS)

Urban ecological stewardship: understanding the structure, function and network of community-based urban land management

Science.gov (United States)

Erika s. Svendsen; Lindsay K. Campbell

2008-01-01

Urban environmental stewardship activities are on the rise in cities throughout the Northeast. Groups participating in stewardship activities range in age, size, and geography and represent an increasingly complex and dynamic arrangement of civil society, government and business sectors. To better understand the structure, function and network of these community-based...

Structural Breaks and Long Memory Property in Korean Won Exchange Rates: Adaptive FIGARCH Model

Directory of Open Access Journals (Sweden)

Young Wook Han

2011-06-01

Full Text Available This paper explores the issue of structural breaks and long memory property in the conditional variance process of the Korean exchange rates. To analyze the above in detail, this paper examines the dynamics of the structural breaks and the long memory in the conditional variance process of the Korean exchange returns by using the daily KRW-USD and KRW-JPY exchange rates for the period from 2000 through 2007. In particular, this paper employs the Adaptive FIGARCH model of Baillie and Morana (2009 which account for the structural breaks and the long memory property together. This paper also finds that the new Adaptive FIGARCH model outperforms the usual FIGARCH model of Baillie et al. (1996 when the structural breaks are present and that the long memory property in the conditional variance process of the Korean exchange returns is significantly reduced after the structural breaks are accounted for. Thus, these results suggest that the upward biased long memory property observed in the conditional variance process of the Korean exchange returns could partially have been imparted as a result of neglecting the structural breaks.

Determination of the sterile release rate for stopping growing age-structured populations

International Nuclear Information System (INIS)

Barclay, Hugh John

2016-01-01

A freely-growing age-structured population was modelled for growth and control by sterile male releases. Equilibrium populations yield critical sterile male release rates that would hold the population at equilibrium. It is shown here that these rates may be different from the release rates required to stop a growing population and bring it to an equilibrium. A computer simulation was constructed of this population and a parameter sensitivity analysis graphed the effects on the required sterile male release rate of fertility, mating delay in adult females, net juvenile survivorship, three adult survivorship curves, the time spent in the juvenile stages, and total life span. The adult survivorship curves had the greatest effect on the required sterile release rate for population elimination. The required release rate was also determined for Ceratitis capitata (Wiedemann) using survivorship and fertility data from a laboratory strain. The concepts of over-flooding ratio and release ratio were discussed and quantified for the cases above. (author)

The influence of sediment transport rate on the development of structure in gravel bed rivers

Science.gov (United States)

Ockelford, Annie; Rice, Steve; Powell, Mark; Reid, Ian; Nguyen, Thao; Tate, Nick; Wood, Jo

2013-04-01

Although adjustments of surface grain size are known to be strongly influenced by sediment transport rate little work has systematically explored how different transport rates can affect the development of surface structure in gravel bed rivers. Specifically, it has been well established that the transport of mixed sized sediments leads to the development of a coarser surface or armour layer which occurs over larger areas of the gravel bed. Armour layer development is known to moderate overall sediment transport rate as well as being extremely sensitive to changes in applied shear stress. However, during this armouring process a bed is created where, smaller gain scale changes, to the bed surface are also apparent such as the development of pebble clusters and imbricate structures. Although these smaller scale changes affect the overall surface grain size distribution very little their presence has the ability to significantly increase the surface stability and hence alter overall sediment transport rates. Consequently, the interplay between the moderation of transport rate as a function of surface coarsening at a larger scale and moderation of transport rate as a function of the development of structure on the bed surface at the smaller scale is complicated and warrants further investigation. During experiments a unimodal grain size distribution (σg = 1.30, D50 = 8.8mm) was exposed to 3 different levels of constant discharge that produced sediment transport conditions ranging from marginal transport to conditions approaching full mobility of all size fractions. Sediment was re-circulated during the experiments surface grain size distribution bed load and fractional transport rates were measured at a high temporal resolution such that the time evolution of the beds could be fully described. Discussion concentrates on analysing the effects of the evolving bed condition sediment transport rate (capacity) and transported grain size (competence). The outcome of this

Mapping the perceptual structure of rectangles through goodness-of-fit ratings.

Science.gov (United States)

Palmer, Stephen E; Guidi, Stefano

2011-01-01

Three experiments were carried out to investigate the internal structure of a rectangular frame to test Arnheim's (1974 Art and Visual Perception, 1988 The Power of the Center) proposals about its 'structural skeleton'. Observers made subjective ratings of how well a small probe circle fit within a rectangle at different interior positions. In experiment 1, ratings of 77 locations were highest in the center, decreased with distance from the center, greatly elevated along vertical and horizontal symmetry axes, and somewhat elevated along the local symmetry axes. A linear regression model with six symmetry-related factors accounted for 95% of the variance. In experiment 2 we measured perceived fit along local symmetry axes versus global diagonals near the corners to determine which factor was relevant. 2AFC probabilities were elevated only along the local symmetry axes and were higher when the probe was closer to the vertex. In experiment 3 we examined the effect of dividing a rectangular frame into two rectangular 'subframes' using an additional line. The results show that the primary determinant of good fit is the position of the target circle within the local subframes. In general, the results are consistent with Arnheim's proposals about the internal structure of a rectangular frame, but an alternative interpretation is offered in terms of the Gestalt concept of figural goodness.

Understanding patterns of vegetation structure and distribution across Great Smoky Mountains National Park using LiDAR and meteorology data

Science.gov (United States)

Kumar, J.; Hargrove, W. W.; Norman, S. P.; Hoffman, F. M.

2017-12-01

Great Smoky Mountains National Park (GSMNP) in Tennessee is a biodiversity hotspot and home to a large number of plant, animal and bird species. Driven by gradients of climate (ex. temperature, precipitation regimes), topography (ex. elevation, slope, aspect), geology (ex. soil types, textures, depth), hydrology (ex. drainage, moisture availability) etc. GSMNP offers a diverse composition and distribution of vegetation which in turn supports an array of wildlife. Understanding the vegetation canopy structure is critical to understand, monitor and manage the complex forest ecosystems like the Great Smoky Mountain National Park (GSMNP). Vegetation canopies not only help understand the vegetation, but are also a critically important habitat characteristics of many threatened and endangered animal and bird species that GSMNP is home to. Using airborne Light Detection and Ranging (LiDAR) we characterize the three-dimensional structure of the vegetation. LiDAR based analysis gives detailed insight in the canopy structure (overstory and understory) and its spatial variability within and across forest types. Vegetation structure and spatial distribution show strong correlation with climate, topographic, and edaphic variables and our multivariate analysis not just mines rich and large LiDAR data but presents ecological insights and data for vegetation within the park that can be useful to forest managers in their management and conservation efforts.

Exploring consumer understanding and preferences for pharmacy quality information

Science.gov (United States)

Shiyanbola, Olayinka O.; Mort, Jane R.

2014-01-01

Objective: To describe consumer understanding of pharmacy quality measures and consumer preferences for pharmacy quality information. Methods: Semi-structured focus group design was combined with survey methods. Adults who filled prescription medications for self-reported chronic illnesses at community pharmacies discussed their understanding of Pharmacy Quality Alliance approved quality measures. Questions examined preference of pharmacy quality information rating systems (e.g. stars versus percentages) and desired data display/formats. During the focus group, participants completed a survey examining their understanding of each pharmacy quality measure. All focus group discussions were transcribed verbatim. Data were analyzed using thematic analysis and descriptive statistics. Results: Thirty-four individuals participated (mean age= 62.85; SD=16.05). Participants were unfamiliar with quality measures information and their level of understanding differed for each quality measure. Surveys indicated 94.1% understood “Drug-Drug Interactions” and “Helping Patients Get Needed Medications” better than other measures (e.g., 76.5% understood “Suboptimal Treatment of Hypertension in Patients with Diabetes”). Qualitative analysis indicated participants preferred an overall pharmacy rating for quick access and use. However, participants also wanted quality measures information displayed by health conditions. Participants favored comparison of their pharmacy to city data instead of state data. Most participants liked star ratings better than percentages, letter grades, or numerical ratings. Conclusions: Individuals who have a chronic illness and regularly use community pharmacies are interested in pharmacy quality measures. However, specific quality measures were not understood by some participants. Participants had specific preferences for the display of pharmacy quality information which will be helpful in the design of appropriate quality report systems. PMID

Exploring consumer understanding and preferences for pharmacy quality information

Directory of Open Access Journals (Sweden)

Shiyanbola OO

2014-12-01

Full Text Available Objective: To describe consumer understanding of pharmacy quality measures and consumer preferences for pharmacy quality information. Methods: Semi-structured focus group design was combined with survey methods. Adults who filled prescription medications for self-reported chronic illnesses at community pharmacies discussed their understanding of Pharmacy Quality Alliance approved quality measures. Questions examined preference of pharmacy quality information rating systems (e.g. stars versus percentages and desired data display/formats. During the focus group, participants completed a survey examining their understanding of each pharmacy quality measure. All focus group discussions were transcribed verbatim. Data were analyzed using thematic analysis and descriptive statistics. Results: Thirty-four individuals participated (mean age= 62.85; SD=16.05. Participants were unfamiliar with quality measures information and their level of understanding differed for each quality measure. Surveys indicated 94.1% understood “Drug-Drug Interactions” and “Helping Patients Get Needed Medications” better than other measures (e.g., 76.5% understood “Suboptimal Treatment of Hypertension in Patients with Diabetes”. Qualitative analysis indicated participants preferred an overall pharmacy rating for quick access and use. However, participants also wanted quality measures information displayed by health conditions. Participants favored comparison of their pharmacy to city data instead of state data. Most participants liked star ratings better than percentages, letter grades, or numerical ratings. Conclusions: Individuals who have a chronic illness and regularly use community pharmacies are interested in pharmacy quality measures. However, specific quality measures were not understood by some participants. Participants had specific preferences for the display of pharmacy quality information which will be helpful in the design of appropriate quality

Extinction rate, historical population structure and ecological role of the Caribbean monk seal.

Science.gov (United States)

McClenachan, Loren; Cooper, Andrew B

2008-06-22

The productivity and biomass of pristine coral reef ecosystems is poorly understood, particularly in the Caribbean where communities have been impacted by overfishing and multiple other stressors over centuries. Using historical data on the spatial distribution and abundance of the extinct Caribbean monk seal (Monachus tropicalis), this study reconstructs the population size, structure and ecological role of this once common predator within coral reef communities, and provides evidence that historical reefs supported biomasses of fishes and invertebrates up to six times greater than those found on typical modern Caribbean reefs. An estimated 233,000-338,000 monk seals were distributed among 13 colonies across the Caribbean. The biomass of reef fishes and invertebrates required to support historical seal populations was 732-1018 gm(-2) of reefs, which exceeds that found on any Caribbean reef today and is comparable with those measured in remote Pacific reefs. Quantitative estimates of historically dense monk seal colonies and their consumption rates on pristine reefs provide concrete data on the magnitude of decline in animal biomass on Caribbean coral reefs. Realistic reconstruction of these past ecosystems is critical to understanding the profound and long-lasting effect of human hunting on the functioning of coral reef ecosystems.

Nonparametric modeling of US interest rate term structure dynamics and implications on the prices of derivative securities

NARCIS (Netherlands)

Jiang, GJ

1998-01-01

This paper develops a nonparametric model of interest rate term structure dynamics based an a spot rate process that permits only positive interest rates and a market price of interest rate risk that precludes arbitrage opportunities. Both the spot rate process and the market price of interest rate

Energy density and rate limitations in structural composite supercapacitors

Science.gov (United States)

Snyder, J. F.; Gienger, E.; Wetzel, E. D.; Xu, K.

2012-06-01

The weight and volume of conventional energy storage technologies greatly limits their performance in mobile platforms. Traditional research efforts target improvements in energy density to reduce device size and mass. Enabling a device to perform additional functions, such as bearing mechanical load, is an alternative approach as long as the total mass efficiency exceeds that of the individual materials it replaces. Our research focuses on structural composites that function as batteries and supercapacitors. These multifunctional devices could be used to replace conventional structural components, such as vehicle frame elements, to provide significant system-level weight reductions and extend mission times. Our approach is to design structural properties directly into the electrolyte and electrode materials. Solid polymer electrolyte materials bind the system and transfer load to the fibers while conducting ions between the electrodes. Carbon fiber electrodes provide a route towards optimizing both energy storage and load-bearing capabilities, and may also obviate the need for a separate current collector. The components are being integrated using scalable, cost-effective composite processing techniques that are amenable to complex part shapes. Practical considerations of energy density and rate behavior are described here as they relate to materials used. Our results highlight the viability as well as the challenges of this multifunctional approach towards energy storage.

Integrating Model-Based Learning and Animations for Enhancing Students' Understanding of Proteins Structure and Function

Science.gov (United States)

Barak, Miri; Hussein-Farraj, Rania

2013-01-01

This paper describes a study conducted in the context of chemistry education reforms in Israel. The study examined a new biochemistry learning unit that was developed to promote in-depth understanding of 3D structures and functions of proteins and nucleic acids. Our goal was to examine whether, and to what extent teaching and learning via…

Measurement of reaction rates of interest in stellar structure and evolution

International Nuclear Information System (INIS)

Terrasi, F.; D''Onofrio, A.; Campajola, L.; Imbriani, G.; Gialanella, L.; Greife, U.; Rolfs, C.; Strieder, F.; Trautvetter, H.P.; Roca, V.; Romano, M.; Straniero, O.

1998-01-01

Accurate determinations of reaction rates at astrophysical energies are very important in stellar structure and evolution studies. The cases of two key reactions, namely 7 Be(p,γ) 8 B and 12 C(α,γ) 16 O are discussed, both from the point of view of their astrophysical interest and of the experimental difficulties in the measurement of their cross section. (orig.)

New rate structure of the Dutch natural gas trading company Gasunie

International Nuclear Information System (INIS)

Koevoet, H.

1999-01-01

Starting January 1, 2000, many of Gasunie's large-scale consumers will have to deal with a new rate structure: the CDS (Dutch abbreviation for Commodity Services System). Unlike in the old zone system, the consumption profile is of great importance in the CDS. Those who must heat large spaces have a particular interest in sizing up the consequences of the CDS

Fibronectin alters the rate of formation and structure of the fibrin matrix.

Science.gov (United States)

Ramanathan, Anand; Karuri, Nancy

2014-01-10

Plasma fibronectin is a vital component of the fibrin clot; however its role on clot structure is not clearly understood. The goal of this study was to examine the influence of fibronectin on the kinetics of formation, structural characteristics and composition of reconstituted fibrin clots or fibrin matrices. Fibrin matrices were formed by adding thrombin to 1, 2 or 4 mg/ml fibrinogen supplemented with 0-0.4 mg/ml fibronectin. The rate of fibrin matrix formation was then monitored by measuring light absorbance properties at different time points. Confocal microscopy of fluorescein conjugated fibrinogen was used to visualize the structural characteristics of fibrin matrices. The amount of fibronectin in fibrin matrices was determined through electrophoresis and immunoblotting of solubilized matrices. Fibronectin concentration positively correlated with the initial rate of fibrin matrix formation and with steady state light absorbance values of fibrin matrices. An increase in fibronectin concentration resulted in thinner and denser fibers in the fibrin matrices. Electrophoresis and immunoblotting showed that fibronectin was covalently and non-covalently bound to fibrin matrices and in the form of high molecular weight multimers. The formation of fibronectin multimers was attributed to cross-linking of fibronectin by trace amounts Factor XIIIa. These findings are novel because they link results from light absorbance studies to microcopy analyses and demonstrate an influence of fibronectin on fibrin matrix structural characteristics. This data is important in developing therapies that destabilize fibrin clots. Copyright © 2014. Published by Elsevier Inc.

Future Mars geophysical observatories for understanding its internal structure, rotation, and evolution

Science.gov (United States)

Dehant, Veronique; Banerdt, Bruce; Lognonné, Philippe; Grott, Matthias; Asmar, Sami; Biele, Jens; Breuer, Doris; Forget, François; Jaumann, Ralf; Johnson, Catherine; Knapmeyer, Martin; Langlais, Benoit; Le Feuvre, Mathieu; Mimoun, David; Mocquet, Antoine; Read, Peter; Rivoldini, Attilio; Romberg, Oliver; Schubert, Gerald; Smrekar, Sue; Spohn, Tilman; Tortora, Paolo; Ulamec, Stephan; Vennerstrøm, Susanne

2012-08-01

Our fundamental understanding of the interior of the Earth comes from seismology, geodesy, geochemistry, geomagnetism, geothermal studies, and petrology. For the Earth, measurements in those disciplines of geophysics have revealed the basic internal layering of the Earth, its dynamical regime, its thermal structure, its gross compositional stratification, as well as significant lateral variations in these quantities. Planetary interiors not only record evidence of conditions of planetary accretion and differentiation, they exert significant control on surface environments. We present recent advances in possible in-situ investigations of the interior of Mars, experiments and strategies that can provide unique and critical information about the fundamental processes of terrestrial planet formation and evolution. Such investigations applied on Mars have been ranked as a high priority in virtually every set of European, US and international high-level planetary science recommendations for the past 30 years. New seismological methods and approaches based on the cross-correlation of seismic noise by two seismic stations/landers on the surface of Mars and on joint seismic/orbiter detection of meteorite impacts, as well as the improvement of the performance of Very Broad-Band (VBB) seismometers have made it possible to secure a rich scientific return with only two simultaneously recording stations. In parallel, use of interferometric methods based on two Earth-Mars radio links simultaneously from landers tracked from Earth has increased the precision of radio science experiments by one order of magnitude. Magnetometer and heat flow measurements will complement seismic and geodetic data in order to obtain the best information on the interior of Mars. In addition to studying the present structure and dynamics of Mars, these measurements will provide important constraints for the astrobiology of Mars by helping to understand why Mars failed to sustain a magnetic field, by

Do central banks respond to exchange rate movements? Some new evidence from structural estimation

OpenAIRE

Wei Dong

2013-01-01

This paper investigates the impact of exchange rate movements on the conduct of monetary policy in Australia, Canada, New Zealand and the United Kingdom. We develop and estimate a structural general equilibrium two-sector model with sticky prices and wages and limited exchange rate pass-through. Different specifications for the monetary policy rule and the real exchange rate process are examined. The results indicate that the Reserve Bank of Australia, the Bank of Canada and the Bank of Engla...

Understanding the chemical and structural transformations of lignin macromolecule during torrefaction

International Nuclear Information System (INIS)

Wen, Jia-Long; Sun, Shao-Long; Yuan, Tong-Qi; Xu, Feng; Sun, Run-Cang

2014-01-01

Highlights: • The terrified bamboo has a high energy yield of 85.7% and a HHV of 20.13 MJ/kg. • The structural changes of hemicelluloses, cellulose, and lignin were investigated. • First study on the structural transformations of lignin during torrefaction. • The mechanism of structural changes of lignin has been proposed. - Abstract: Torrefaction is an efficient method to recover energy from biomass. Herein, the characteristics (mass yield, energy yield, physical, and chemical characteristics) of torrefied bamboo at diverse temperatures (200–300 °C) were firstly evaluated by elemental analysis, XRD, and CP–MAS 13 C NMR methodologies. Under an optimal condition the terrified bamboo has a relative high energy yield of 85.7% and a HHV of 20.13 MJ/kg. The chemical and structural transformations of lignin induced by thermal treatment were thoroughly investigated by FT-IR and solution-state NMR techniques (quantitative 13 C NMR, 2D-HSQC, and 31 P-NMR methodologies). The results highlighted the chemical reactions of the native bamboo lignins towards severe torrefaction treatments occurred, such as depolymerization, demethoxylation, bond cleavage, and condensation reactions. NMR results indicated that aryl-ether bonds (β-O-4) and p-coumaric ester in lignin were cleaved during the torrefaction process at mild conditions. The severe treatments of bamboo (275 °C and 300 °C) induced a dramatic enrichment in lignin content together with the almost complete disappearance of β-O-4, β-β, and β-5 linkages. Further analysis of the molecular weight of milled wood lignin (MWL) indicated that the average molecular weights of “torrefied MWL” were lower than those of control MWL. It is believed that understanding of the reactivity and chemical transformations of lignin during torrefaction will contribute to the integrated torrefaction mechanism

Exchange Rate Pass-through and Monetary Policy in South Africa

OpenAIRE

Aron, Janine; Farrell, Greg; Muellbauer, John; Sinclair, Peter

2010-01-01

Understanding how import prices adjust to exchange rates helps anticipate inflation effects and monetary policy responses. This paper examines exchange rate passthrough to the monthly import price index in South Africa during 1980-2009. A methodological innovation allows various short-run pass-through estimates to be calculated simply without recourse to a full structural model, yet without neglecting the long-run relationships between prices or the effects of previous import price changes, a...

Crash simulation of hybrid structures considering the stress and strain rate dependent material behavior of thermoplastic materials

Science.gov (United States)

Hopmann, Ch.; Schöngart, M.; Weber, M.; Klein, J.

2015-05-01

Thermoplastic materials are more and more used as a light weight replacement for metal, especially in the automotive industry. Since these materials do not provide the mechanical properties, which are required to manufacture supporting elements like an auto body or a cross bearer, plastics are combined with metals in so called hybrid structures. Normally, the plastics components are joined to the metal structures using different technologies like welding or screwing. Very often, the hybrid structures are made of flat metal parts, which are stiffened by a reinforcement structure made of thermoplastic materials. The loads on these structures are very often impulsive, for example in the crash situation of an automobile. Due to the large stiffness variation of metal and thermoplastic materials, complex states of stress and very high local strain rates occur in the contact zone under impact conditions. Since the mechanical behavior of thermoplastic materials is highly dependent on these types of load, the crash failure of metal plastic hybrid parts is very complex. The problem is that the normally used strain rate dependent elastic/plastic material models are not capable to simulate the mechanical behavior of thermoplastic materials depended on the state of stress. As part of a research project, a method to simulate the mechanical behavior of hybrid structures under impact conditions is developed at the IKV. For this purpose, a specimen for the measurement of mechanical properties dependet on the state of stress and a method for the strain rate depended characterization of thermoplastic materials were developed. In the second step impact testing is performed. A hybrid structure made from a metal sheet and a reinforcement structure of a Polybutylenterephthalat Polycarbonate blend is tested under impact conditions. The measured stress and strain rate depended material data are used to simulate the mechanical behavior of the hybrid structure under highly dynamic load with

Measurement of reaction rates of interest in stellar structure and evolution

Energy Technology Data Exchange (ETDEWEB)

Terrasi, F; D` Onofrio, A [Dipt. di Scienze Ambientali, Seconda Univ. di Napoli, Caserta (Italy); [INFN, Napoli (Italy); Campajola, L; Imbriani, G [INFN, Napoli (Italy); [Dipt. di Scienze Fisiche, Univ. Federico II, Napoli (Italy); Gialanella, L [INFN, Napoli (Italy); [Dipt. di Scienze Fisiche, Univ. Federico II, Napoli (Italy); [Inst. fuer Experimentalphysik III, Ruhr-Univ. Bochum, Bochum (Germany); Greife, U; Rolfs, C; Strieder, F; Trautvetter, H P [Inst. fuer Experimentalphysik III, Ruhr-Univ. Bochum, Bochum (Germany); Roca, V; Romano, M [INFN, Napoli (Italy); [Dipt. di Scienze Fisiche, Univ. Federico II, Napoli (Italy); Straniero, O [Osservatorio Astronomico di Collurania, Teramo (Italy)

1998-06-01

Accurate determinations of reaction rates at astrophysical energies are very important in stellar structure and evolution studies. The cases of two key reactions, namely {sup 7}Be(p,{gamma}){sup 8}B and {sup 12}C({alpha},{gamma}){sup 16}O are discussed, both from the point of view of their astrophysical interest and of the experimental difficulties in the measurement of their cross section. (orig.)

Understanding estimated worker absenteeism rates during an influenza pandemic.

Science.gov (United States)

Thanner, Meridith H; Links, Jonathan M; Meltzer, Martin I; Scheulen, James J; Kelen, Gabor D

2011-01-01

Published employee absenteeism estimates during an influenza pandemic range from 10 to 40 percent. The purpose of this study was to estimate daily employee absenteeism through the duration of an influenza pandemic and to determine the relative impact of key variables used to derive the estimates. Using the Centers for Disease Control and Prevention's FluWorkLoss program, the authors estimated the number of absent employees on any given day over the course of a simulated 8-week pandemic wave by using varying attack rates. Employee data from a university with a large academic health system were used. Sensitivity of the program outputs to variation in predictor (inputs) values was assessed. Finally, the authors examined and documented the algorithmic sequence of the program. Using a 35 percent attack rate, a total of 47,270 workdays (or 3.4 percent of all available workdays) would be lost over the course of an 8-week pandemic among a population of 35,026 employees. The highest (peak) daily absenteeism estimate was 5.8 percent (minimum 4.8 percent; maximum 7.4 percent). Sensitivity analysis revealed that varying days missed for nonhospitalized illness had the greatest potential effect on peak absence rate (3.1 to 17.2 percent). Peak absence with 15 and 25 percent attack rates were 2.5 percent and 4.2 percent, respectively. The impact of an influenza pandemic on employee availability may be less than originally thought, even with a high attack rate. These data are generalizable and are not specific to institutions of higher education or medical centers. Thus, these findings provide realistic and useful estimates for influenza pandemic planning for most organizations.

Understanding your capital options.

Science.gov (United States)

Payne, Christopher T

2012-05-01

When planning capital expenditures, hospitals and health systems should understand the following financing considerations: Traditional fixed-rate tax-exempt bonds; Variable-rate financing alternatives; Basel III Accord requirements; Direct tax-exempt bank loans; Total return swaps Taxable financings; Interest-rate swaps and collateral requirements

Cationic amino acids specific biomimetic silicification in ionic liquid: a quest to understand the formation of 3-D structures in diatoms.

Directory of Open Access Journals (Sweden)

Rajesh Ramanathan

Full Text Available The intricate, hierarchical, highly reproducible, and exquisite biosilica structures formed by diatoms have generated great interest to understand biosilicification processes in nature. This curiosity is driven by the quest of researchers to understand nature's complexity, which might enable reproducing these elegant natural diatomaceous structures in our laboratories via biomimetics, which is currently beyond the capabilities of material scientists. To this end, significant understanding of the biomolecules involved in biosilicification has been gained, wherein cationic peptides and proteins are found to play a key role in the formation of these exquisite structures. Although biochemical factors responsible for silica formation in diatoms have been studied for decades, the challenge to mimic biosilica structures similar to those synthesized by diatoms in their natural habitats has not hitherto been successful. This has led to an increasingly interesting debate that physico-chemical environment surrounding diatoms might play an additional critical role towards the control of diatom morphologies. The current study demonstrates this proof of concept by using cationic amino acids as catalyst/template/scaffold towards attaining diatom-like silica morphologies under biomimetic conditions in ionic liquids.

Understanding vaccination rates and attitudes among patients with rheumatoid arthritis.

Science.gov (United States)

Sandler, Diana S; Ruderman, Eric M; Brown, Tiffany; Lee, Ji Young; Mixon, Amanda; Liss, David T; Baker, David W

2016-03-01

Appropriate vaccinations are important for patients with rheumatoid arthritis (RA), who are often treated with highly immunosuppressive therapies that increase their risk of infection. However, rates of vaccination among patients with RA are below optimal levels. We conducted a patient survey to assess self-reported vaccination status and to compare that status with electronic health record (EHR) data. We recruited randomly selected patients with RA in an academic practice in 2013. Eligible participants had a diagnosis of RA, at least 1 visit to a rheumatology clinic in each of the previous 2 years, were 18 years or older, and had English listed as their preferred language. The survey included the following domains: a) patient self-reported receipt of influenza, pneumococcal (PNVX), and herpes zoster (HZVX) vaccinations; b) attitudes about these vaccines, including reasons for unvaccinated status, if applicable; and c) provider recommendations about these vaccines. Based on participants' self-report, we found a high vaccination rate for influenza during the previous season (79.4%), a moderate rate of any previous vaccination for pneumococcus (53.9%), and a very low rate of any previous vaccination for herpes zoster (7.8%). If we assume that all self-reports are accurate and we include vaccinations recorded in the EHR that were not reported by patients, the vaccination rates were approximately 8% to 9% higher for PNVX and HZVX. Vaccination rates are low among patients with RA based on self-report data. Further research is needed to investigate system-level barriers to vaccination and the impact of evidence-based, provider-level interventions on vaccination rates.

Heterogeneous Information about the Term Structure of Interest rates, Least-Squares Learning and Optimal Interest Rate Rules for Inflation Forecast Targeting

NARCIS (Netherlands)

Schaling, E.; Eijffinger, S.C.W.; Tesfaselassie, M.F.

2004-01-01

In this paper we incorporate the term structure of interest rates in a standard inflation forecast targeting framework.Learning about the transmission process of monetary policy is introduced by having heterogeneous agents - i.e. the central bank and private agents - who have different information

Stress Wave E-Rating of Structural Timber—Size and Moisture Content Effects

Science.gov (United States)

Xiping Wang

2013-01-01

The objectives of this study were to investigate the influence of cross sectional size and moisture content on stress wave properties of structural timber in various sizes and evaluate the feasibility of using stress wave method to E-rate timber in green conditions. Four different sizes of Douglas-fir (Pseudotsuga menziesii) square timbers were...

Cooling rate dependence of simulated Cu{sub 64.5}Zr{sub 35.5} metallic glass structure

Energy Technology Data Exchange (ETDEWEB)

Ryltsev, R. E. [Institute of Metallurgy, Ural Branch of Russian Academy of Sciences, 101 Amundsen Str., 620016 Ekaterinburg (Russian Federation); Ural Federal University, 19 Mira Str., 620002 Ekaterinburg (Russian Federation); L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences, 2 Kosygina Str., 119334 Moscow (Russian Federation); Klumov, B. A. [L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences, 2 Kosygina Str., 119334 Moscow (Russian Federation); Aix-Marseille-Université, CNRS, Laboratoire PIIM, UMR 7345, 13397 Marseille Cedex 20 (France); High Temperature Institute, Russian Academy of Sciences, 13/2 Izhorskaya Str., 125412 Moscow (Russian Federation); Chtchelkatchev, N. M. [Institute of Metallurgy, Ural Branch of Russian Academy of Sciences, 101 Amundsen Str., 620016 Ekaterinburg (Russian Federation); L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences, 2 Kosygina Str., 119334 Moscow (Russian Federation); Moscow Institute of Physics and Technology, 9 Institutskiy Per., Dolgoprudny, 141700 Moscow Region (Russian Federation); All-Russia Research Institute of Automatics, 22 Sushchevskaya, 127055 Moscow (Russian Federation); Shunyaev, K. Yu. [Institute of Metallurgy, Ural Branch of Russian Academy of Sciences, 101 Amundsen Str., 620016 Ekaterinburg (Russian Federation); Ural Federal University, 19 Mira Str., 620002 Ekaterinburg (Russian Federation)

2016-07-21

Using molecular dynamics simulations with embedded atom model potential, we study structural evolution of Cu{sub 64.5}Zr{sub 35.5} alloy during the cooling in a wide range of cooling rates γ ∈ (1.5 ⋅ 10{sup 9}, 10{sup 13}) K/s. Investigating short- and medium-range orders, we show that the structure of Cu{sub 64.5}Zr{sub 35.5} metallic glass essentially depends on cooling rate. In particular, a decrease of the cooling rate leads to an increase of abundances of both the icosahedral-like clusters and Frank-Kasper Z16 polyhedra. The amounts of these clusters in the glassy state drastically increase at the γ{sub min} = 1.5 ⋅ 10{sup 9} K/s. Analysing the structure of the glass at γ{sub min}, we observe the formation of nano-sized crystalline grain of Cu{sub 2}Zr intermetallic compound with the structure of Cu{sub 2}Mg Laves phase. The structure of this compound is isomorphous with that for Cu{sub 5}Zr intermetallic compound. Both crystal lattices consist of two types of clusters: Cu-centered 13-atom icosahedral-like cluster and Zr-centered 17-atom Frank-Kasper polyhedron Z16. That suggests the same structural motifs for the metallic glass and intermetallic compounds of Cu–Zr system and explains the drastic increase of the abundances of these clusters observed at γ{sub min}.

A study of the influence of a gravel subslab layer on radon entry rate using two basement structures

International Nuclear Information System (INIS)

Robinson, A.L.; Sextro, R.G.; Fisk, W.J.; Garbesi, K.; Wooley, J.; Wollenberg, H.A.

1993-01-01

In buildings with elevated radon concentrations, the dominant transport mechanism of radon is advective flow of soil gas into the building substructure. However, the building-soil system is often complex, making detailed studies of the radon source term difficult. In order to examine radon entry into buildings, the authors have constructed two room-size, precisely-fabricated basement structures at a site with relatively homogeneous, moderately permeable soil. The basements are identical except that one lies directly on native soil whereas the other lies on a high permeability aggregate layer. The soil pressure field and radon entry rate have been measured for different basement pressures and environmental conditions. The subslab gravel layer greatly enhances the advective entry of radon into the structure; when the structures are depressurized, the radon entry rate into the structure with the subslab gravel layer is more than a factor of 3 times the radon entry rate into the other structure for the same depressurization. The gravel subslab layer also spreads the pressure field around the structure, extending the field of influence of the structure and the region from which it draws radon

A study of the influence of a gravel subslab layer on radon entry rate using two basement structures

International Nuclear Information System (INIS)

Robinson, A.L.; Sextro, R.G.; Fisk, W.J.; Garbesi, K.; Wooley, J.; Wollenberg, H.A.

1993-01-01

In buildings with elevated radon concentrations, the dominant transport mechanism of radon is advective flow of soil gas into the building substructure. However, the building-soil system is often complex, making detailed studies of the radon source term difficult. In order-to examine radon entry into buildings, we have constructed two room-size, precisely-fabricated basement structures at a site with relatively homogeneous, moderately permeable soil. The basements are identical except that one lies directly on native soil whereas the other lies on a high permeability aggregate layer. The soil pressure field and radon entry rate have been measured for different basement pressures and environmental conditions. The subslab gravel layer greatly enhances the advective entry of radon into the structure; when the structures are depressurized, the radon entry rate into the structure with the subslab gravel layer is more than a factor of 3 times the radon entry rate into the other structure for the same depressurization. The gravel subslab layer also spreads the pressure field around the structure, extending the field of influence of the structure and the region from which it draws radon. (orig.). (7 refs., 3 figs.)

Understanding Structural Features of Microbial Lipases–-An Overview

Directory of Open Access Journals (Sweden)

John Geraldine Sandana Mala

2008-01-01

Full Text Available The structural elucidations of microbial lipases have been of prime interest since the 1980s. Knowledge of structural features plays an important role in designing and engineering lipases for specific purposes. Significant structural data have been presented for few microbial lipases, while, there is still a structure-deficit, that is, most lipase structures are yet to be resolved. A search for ‘lipase structure’ in the RCSB Protein Data Bank ( http://www.rcsb.org/pdb/ returns only 93 hits (as of September 2007 and, the NCBI database ( http://www.ncbi.nlm.nih.gov reports 89 lipase structures as compared to 14719 core nucleotide records. It is therefore worthwhile to consider investigations on the structural analysis of microbial lipases. This review is intended to provide a collection of resources on the instrumental, chemical and bioinformatics approaches for structure analyses. X-ray crystallography is a versatile tool for the structural biochemists and is been exploited till today. The chemical methods of recent interests include molecular modeling and combinatorial designs. Bioinformatics has surged striking interests in protein structural analysis with the advent of innumerable tools. Furthermore, a literature platform of the structural elucidations so far investigated has been presented with detailed descriptions as applicable to microbial lipases. A case study of Candida rugosa lipase (CRL has also been discussed which highlights important structural features also common to most lipases. A general profile of lipase has been vividly described with an overview of lipase research reviewed in the past.

Analisa Korelasi Inflasi, Economic Growth, Economic Structure, Dan Tax Rate Terhadap Tax Revenue Di Negara-negara ASEAN

OpenAIRE

Lim, Richard; Toly, Agus Arianto

2013-01-01

Penelitian ini bertujuan untuk mengetahui korelasi dari inflasi, economic growth, economic structure serta tax rate terhadap tax revenue di negara-negara Asean. Penelitian ini adalah penelitian kuantitatif dan penelitian ini menggunakan data sekunder mengenai inflasi, economic growth, economic structure, tax rate, serta tax revenue yang diperoleh melalui website world bank yaitu http://data.worldbank.org. Sampel yang digunakan dalam penelitian ini adalah negara-negara Asean tahun 2002 sampai ...

Influence of temperature, strain rate and thermal aging on the structure/property behavior of uranium 6 wt% Nb

Energy Technology Data Exchange (ETDEWEB)

Cady, C.M.; Gray, G.T.; Chen, S.R.; Lopez, M.F. [Los Alamos National Lab., MST-8, MS G-755, NM (United States); Field, R.D.; Korzekwa, D.R. [Los Alamos National Lab., MST-6, MS G-770, NM (United States); Hixson, R.S. [Los Alamos National Lab, DX-9, MS P-952, NM (United States)

2006-08-15

A rigorous experimentation and validation program is being undertaken to create constitutive models that elucidate the fundamental mechanisms controlling plasticity in uranium-6 wt% niobium alloys (U-6Nb). These models should accurately predict high-strain-rate large-strain plasticity, damage evolution and failure. The goal is a physically-based constitutive model that captures 1) an understanding of how strain rate, temperature, and aging affects the mechanical response of a material, and 2) an understanding of the operative deformation mechanisms. The stress-strain response of U-6Nb has been studied as a function of temperature, strain-rate, and thermal aging. U-6Nb specimens in a solution-treated and quenched condition and after subsequent aging at 473 K for 2 hours were studied. The constitutive behavior was evaluated over the range of strain rates from quasi-static (0.001 s{sup -1}) to dynamic ({approx} 2000 s{sup -1}) and temperatures ranging from 77 to 773 K. The yield stress of U-6Nb was exhibited pronounced temperature sensitivity. The strain hardening rate is seen to be less sensitive to strain rate and temperature beyond plastic strains of 0.10. The yield strength of the aged material is less significantly affected by temperature and the work hardening rate shows adiabatic heating at lower strains rates (1/s). (authors)

Deep-Sea Microbes: Linking Biogeochemical Rates to -Omics Approaches

Science.gov (United States)

Herndl, G. J.; Sintes, E.; Bayer, B.; Bergauer, K.; Amano, C.; Hansman, R.; Garcia, J.; Reinthaler, T.

2016-02-01

Over the past decade substantial progress has been made in determining deep ocean microbial activity and resolving some of the enigmas in understanding the deep ocean carbon flux. Also, metagenomics approaches have shed light onto the dark ocean's microbes but linking -omics approaches to biogeochemical rate measurements are generally rare in microbial oceanography and even more so for the deep ocean. In this presentation, we will show by combining metagenomics, -proteomics and biogeochemical rate measurements on the bulk and single-cell level that deep-sea microbes exhibit characteristics of generalists with a large genome repertoire, versatile in utilizing substrate as revealed by metaproteomics. This is in striking contrast with the apparently rather uniform dissolved organic matter pool in the deep ocean. Combining the different -omics approaches with metabolic rate measurements, we will highlight some major inconsistencies and enigmas in our understanding of the carbon cycling and microbial food web structure in the dark ocean.

Understanding volatility correlation behavior with a magnitude cross-correlation function

Science.gov (United States)

Jun, Woo Cheol; Oh, Gabjin; Kim, Seunghwan

2006-06-01

We propose an approach for analyzing the basic relation between correlation properties of the original signal and its magnitude fluctuations by decomposing the original signal into its positive and negative fluctuation components. We use this relation to understand the following phenomenon found in many naturally occurring time series: the magnitude of the signal exhibits long-range correlation, whereas the original signal is short-range correlated. The applications of our approach to heart rate variability signals and high-frequency foreign exchange rates reveal that the difference between the correlation properties of the original signal and its magnitude fluctuations is induced by the time organization structure of the correlation function between the magnitude fluctuations of positive and negative components. We show that this correlation function can be described well by a stretched-exponential function and is related to the nonlinearity and the multifractal structure of the signals.

Understanding volatility correlation behavior with a magnitude cross-correlation function.

Science.gov (United States)

Jun, Woo Cheol; Oh, Gabjin; Kim, Seunghwan

2006-06-01

We propose an approach for analyzing the basic relation between correlation properties of the original signal and its magnitude fluctuations by decomposing the original signal into its positive and negative fluctuation components. We use this relation to understand the following phenomenon found in many naturally occurring time series: the magnitude of the signal exhibits long-range correlation, whereas the original signal is short-range correlated. The applications of our approach to heart rate variability signals and high-frequency foreign exchange rates reveal that the difference between the correlation properties of the original signal and its magnitude fluctuations is induced by the time organization structure of the correlation function between the magnitude fluctuations of positive and negative components. We show that this correlation function can be described well by a stretched-exponential function and is related to the nonlinearity and the multifractal structure of the signals.

Parent and teacher ratings of attention-deficit/hyperactivity disorder symptoms: Factor structure and normative data.

Science.gov (United States)

DuPaul, George J; Reid, Robert; Anastopoulos, Arthur D; Lambert, Matthew C; Watkins, Marley W; Power, Thomas J

2016-02-01

Comprehensive assessment of attention-deficit/hyperactivity disorder (ADHD) symptoms includes parent and teacher questionnaires. The ADHD Rating Scale-5 was developed to incorporate changes for the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5; American Psychiatric Association, 2013). This study examined the fit of a correlated, 2-factor structure of ADHD (i.e., DSM-5 conceptual model) and alternative models; determined whether ADHD symptom ratings varied across teacher and child demographic characteristics; and presented normative data. Two samples were included: (a) 2,079 parents and guardians (1,131 female, 948 male) completed ADHD symptom ratings for children (N = 2,079; 1,037 males, 1,042 females) between 5 and 17 years old (M = 10.68; SD = 3.75) and (b) 1,070 teachers (766 female, 304 male) completed ADHD symptom ratings for students (N = 2,140; 1,070 males, 1,070 females) between 5 and 17 years old (M = 11.53; SD = 3.54) who attended kindergarten through 12th grade. The 2-factor structure was confirmed for both parent and teacher ratings and was invariant across child gender, age, informant, informant gender, and language. In general, boys were higher in symptom frequency than girls; older children were rated lower than younger children, especially for hyperactivity-impulsivity; and non-Hispanic children were rated higher than Hispanic children. Teachers also rated non-Hispanic African American children higher than non-Hispanic White, Asian, and Hispanic children. Non-Hispanic White teachers provided lower hyperactivity-impulsivity ratings than non-Hispanic, African American, and Hispanic teachers. Normative data are reported separately for parent and teacher ratings by child gender and age. The merits of using the ADHD Rating Scale-5 in a multimodal assessment protocol are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Space and panic : The application of space syntax to understand the relationship between mortality rates and spatial configuration in Banda Aceh during the tsunami 2004

NARCIS (Netherlands)

Fakhrurrazi, F.; Van Nes, A.

2012-01-01

The aim of this paper is to reveal the correlation between mortality rates from the tsunami of 2004 and the spatial structure of Banda Aceh’s street net. Structurally, the city is divided up in several small villages, which consists of a couple of urban blocks. The mortality rates for each of these

Causes and implications of the correlation between forest productivity and tree mortality rates

Science.gov (United States)

Stephenson, Nathan L.; van Mantgem, Philip J.; Bunn, Andrew G.; Bruner, Howard; Harmon, Mark E.; O'Connell, Kari B.; Urban, Dean L.; Franklin, Jerry F.

2011-01-01

At global and regional scales, tree mortality rates are positively correlated with forest net primary productivity (NPP). Yet causes of the correlation are unknown, in spite of potentially profound implications for our understanding of environmental controls of forest structure and dynamics and, more generally, our understanding of broad-scale environmental controls of population dynamics and ecosystem processes. Here we seek to shed light on the causes of geographic patterns in tree mortality rates, and we consider some implications of the positive correlation between mortality rates and NPP. To reach these ends, we present seven hypotheses potentially explaining the correlation, develop an approach to help distinguish among the hypotheses, and apply the approach in a case study comparing a tropical and temperate forest.

EFFECTS OF PORE STRUCTURE CHANGE AND MULTI-SCALE HETEROGENEITY ON CONTAMINANT TRANSPORT AND REACTION RATE UPSCALING

Energy Technology Data Exchange (ETDEWEB)

Lindquist, W. Brent; Jones, Keith W.; Um, Wooyong; Rockhold, mark; Peters, Catherine A.; Celia, Michael A.

2013-02-15

This project addressed the scaling of geochemical reactions to core and field scales, and the interrelationship between reaction rates and flow in porous media. We targeted reactive transport problems relevant to the Hanford site - specifically the reaction of highly caustic, radioactive waste solutions with subsurface sediments, and the immobilization of 90Sr and 129I through mineral incorporation and passive flow blockage, respectively. We addressed the correlation of results for pore-scale fluid-soil interaction with field-scale fluid flow, with the specific goals of (i) predicting attenuation of radionuclide concentration; (ii) estimating changes in flow rates through changes of soil permeabilities; and (iii) estimating effective reaction rates. In supplemental work, we also simulated reactive transport systems relevant to geologic carbon sequestration. As a whole, this research generated a better understanding of reactive transport in porous media, and resulted in more accurate methods for reaction rate upscaling and improved prediction of permeability evolution. These scientific advancements will ultimately lead to better tools for management and remediation of DOE’s legacy waste problems. We established three key issues of reactive flow upscaling, and organized this project in three corresponding thrust areas. 1) Reactive flow experiments. The combination of mineral dissolution and precipitation alters pore network structure and the subsequent flow velocities, thereby creating a complex interaction between reaction and transport. To examine this phenomenon, we conducted controlled laboratory experimentation using reactive flow-through columns. Results and Key Findings: Four reactive column experiments (S1, S3, S4, S5) have been completed in which simulated tank waste leachage (STWL) was reacted with pure quartz sand, with and without Aluminum. The STWL is a caustic solution that dissolves quartz. Because Al is a necessary element in the formation of

Development and reliability of a structured interview guide for the Montgomery Asberg Depression Rating Scale (SIGMA).

Science.gov (United States)

Williams, Janet B W; Kobak, Kenneth A

2008-01-01

The Montgomery-Asberg Depression Rating Scale (MADRS) is often used in clinical trials to select patients and to assess treatment efficacy. The scale was originally published without suggested questions for clinicians to use in gathering the information necessary to rate the items. Structured and semi-structured interview guides have been found to improve reliability with other scales. To describe the development and test-retest reliability of a structured interview guide for the MADRS (SIGMA). A total of 162 test-retest interviews were conducted by 81 rater pairs. Each patient was interviewed twice, once by each rater conducting an independent interview. The intraclass correlation for total score between raters using the SIGMA was r=0.93, Preliability. Use of the SIGMA can result in high reliability of MADRS scores in evaluating patients with depression.

Embodied Understanding

Directory of Open Access Journals (Sweden)

Mark Leonard Johnson

2015-06-01

Full Text Available Western culture has inherited a view of understanding as an intellectual cognitive operation of grasping of concepts and their relations. However, cognitive science research has shown that this received intellectualist conception is substantially out of touch with how humans actually make and experience meaning. The view emerging from the mind sciences recognizes that understanding is profoundly embodied, insofar as our conceptualization and reasoning recruit sensory, motor, and affective patterns and processes to structure our understanding of, and engagement with, our world. A psychologically realistic account of understanding must begin with the patterns of ongoing interaction between an organism and its physical and cultural environments and must include both our emotional responses to changes in our body and environment, and also the actions by which we continuously transform our experience. Consequently, embodied understanding is not merely a conceptual/propositional activity of thought, but rather constitutes our most basic way of being in, and engaging with, our surroundings in a deep visceral manner.

STRUCTURAL BREAKS AND BILATERAL EXCHANGE RATE PASS-THROUGH: AN EMPIRICAL CASE OF INDONESIA–UNITED STATES

Directory of Open Access Journals (Sweden)

Arintoko Arintoko

2011-06-01

Full Text Available This study estimates the exchange rate pass-through into domestic prices in Indonesia in the two-stage approach. The study focuses on first step pass-through, i.e. ERPT into import prices and second step pass-through, i.e. into consumer prices, using cointegration and error-correction mechanism (ECM model. This research uses a Zivot-Andrews technique to test for structural breaks and Gregory-Hansen models to tests. The results show that the long run ERPT to import prices with structural breaks is relatively low compared to the results without them. The absolut error correction term values resulted from cointegration are decreased and the error-correction models need period lagged longer than one-period if the estimation included the estimated structural breaks. The main finding is that allowing for possible breaks around the crises in Indonesia, and a shift of the exchange rate management from managed to free floating in 1997 helps to restore a long run cointegration relationship estimation.

Towards the determination of deformation rates - pinch-and-swell structures as a natural and simulated paleo-strain rate gage

Science.gov (United States)

Peters, Max; Poulet, Thomas; Karrech, Ali; Regenauer-Lieb, Klaus; Herwegh, Marco

2014-05-01

Layered rocks deformed under viscous deformation conditions frequently show boudinage, a phenomenon that results from differences in effective viscosity between the involved layers. In the case of continuous necking of a mechanically stiffer layer embedded in a weaker matrix, symmetric boudins are interpreted as the result of dominant visco-plastic deformation (Goscombe et al., 2004). However, information on the physical conditions, material properties and deformation processes are yet unknown. Natural samples deformed under low-grade (TAustin and Evans (2007) combined with the thermodynamic approach of Regenauer-Lieb and Yuen (2004). Depending on the dissipated energy, grain sizes in these domains vary substantially in space and time. While low strain rates (low stresses) in the swells favor grain growth and GSI dominated deformation, high strain rates in the pinches provoke dramatic grain size reduction with an increasing contribution of GSS as a function of decreasing grain size. The development of symmetric necks observed in nature thus seems to coincide with the transition from dislocation to diffusion creep dominated flow with continuous grain size reduction and growth from swell to neck at relatively high extensional strains. REFERENCES Austin, N. and Evans, B. (2007). Paleowattmeters: A scaling relation for dynamically recrystallized grain size. Geology, 35. Goscombe, B.D., Passchier, C.W. and Hand, M. (2004). Boudinage classification: End-member boudin types and modified boudin structures, Journal of Structural Geology, 26. Herwegh, M., Poulet, T., Karrech, A. and Regenauer-Lieb, K. (in press). From transient to steady state deformation and grain size: A thermodynamic approach using elasto-visco-plastic numerical modeling. Journal of Geophysical Research. Karrech, A., Regenauer-Lieb, K. and Poulet, T. (2011a). A Damaged visco-plasticity model for pressure and temperature sensitive geomaterials. Journal of Engineering Science 49. Regenauer-Lieb, K. and Yuen

Capital accumulation, structural change and real exchange rate in a Keynesian-Structuralist growth model

Directory of Open Access Journals (Sweden)

Oreiro José Luis

2015-01-01

Full Text Available The aim of this paper is to show at theoretical level that maintaining a competitive real exchange rate positively affects the economic growth of developing countries by means of a Keynesian-Structuralist model that combines elements of Kaleckian growth models with the balance of payments constrained growth models pioneered developed by Thirlwall. In this setting, the level of real exchange rate is capable, due to its effect over capital accumulation, to induce a structural change in the economy, making endogenous income elasticities of exports and imports. For reasonable parameter values it is shown that in steady-state growth there is two long-run equilibrium values for real exchange rate, one that corresponds to an under-valued currency and another that corresponds to an over-valued currency. If monetary authorities run exchange rate policy in order to target a competitive level for real exchange rate, than under-valued equilibrium is stable and the economy will show a high growth rate in the long-run.

Household structure vs. composition: Understanding gendered effects on educational progress in rural South Africa.

Science.gov (United States)

Madhavan, Sangeetha; Myroniuk, Tyler W; Kuhn, Randall; Collinson, Mark A

2017-01-01

Demographers have long been interested in the relationship between living arrangements and gendered outcomes for children in sub-Saharan Africa. Most extant research conflates household structure with composition and has revealed little about the pathways that link these components to gendered outcomes. First, we offer a conceptual approach that differentiates structure from composition with a focus on gendered processes that operate in the household; and second, we demonstrate the value of this approach through an analysis of educational progress for boys and girls in rural South Africa. We use data from the 2002 round of the Agincourt Health and Demographic Surveillance System. Our analytical sample includes 22,997 children aged 6-18 who were neither parents themselves nor lived with a partner or partner's family. We employ ordinary least squares regression models to examine the effects of structure and composition on educational progress of girls and boys. The results suggest that non-nuclear structures are associated with similar negative effects for both boys and girls compared to children growing up in nuclear households. However, the presence of other kin in the absence of one or both parents results in gendered effects favouring boys. The absence of any gendered effects when using a household structure typology suggests that secular changes to attitudes about gender equity trump any specific gendered processes stemming from particular configurations. On the other hand, gendered effects that appear when one or both parents are absent show that traditional gender norms and/or resource constraints continue to favour boys. Despite the wealth of literature on household structure and children's educational outcomes in sub-Saharan Africa, the conceptual basis of these effects has not been well articulated. We have shown the value of unpacking household structure to better understand how gender norms and gendered resource allocations impact education.

Political Market Orientation: A Framework for Understanding Relationship Structures in Political Parties

DEFF Research Database (Denmark)

Ormrod, Robert P.; Savigny, Heather

2012-01-01

This article is motivated by the growing need to integrate the current political science and marketing literature in order to provide a deeper understanding of the behaviour of political actors and their relationships with relevant stakeholder groups. In our article, we demonstrate how Ormrod...... strive for contextual sensitivity. By adopting this approach it is hoped that the fears noted by political scientists that political marketing is solely concerned with applying standard management models to political parties with the resulting emphasis on communication tactics at election time, together......’s conceptual model of political market orientation complements political science models of party organization by drawing attention to the competing interests of stakeholders in shaping party strategy and organizational structure. We treat parties as a multitude of actors rather than as monolithic entities...

Cooling rate and size effects on the medium-range structure of multicomponent oxide glasses simulated by molecular dynamics

Energy Technology Data Exchange (ETDEWEB)

Tilocca, Antonio [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

2013-09-21

A set of molecular dynamics simulations were performed to investigate the effect of cooling rate and system size on the medium-range structure of melt-derived multicomponent silicate glasses, represented by the quaternary 45S5 Bioglass composition. Given the significant impact of the glass degradation on applications of these materials in biomedicine and nuclear waste disposal, bulk structural features which directly affect the glass dissolution process are of particular interest. Connectivity of the silicate matrix, ion clustering and nanosegregation, distribution of ring and chain structural patterns represent critical features in this context, which can be directly extracted from the models. A key issue is represented by the effect of the computational approach on the corresponding glass models, especially in light of recent indications questioning the suitability of conventional MD approaches (that is, involving melt-and-quench of systems containing ∼10{sup 3} atoms at cooling rates of 5-10 K/ps) when applied to model these glasses. The analysis presented here compares MD models obtained with conventional and nonconventional cooling rates and system sizes, highlighting the trend and range of convergence of specific structural features in the medium range. The present results show that time-consuming computational approaches involving much lower cooling rates and/or significantly larger system sizes are in most cases not necessary in order to obtain a reliable description of the medium-range structure of multicomponent glasses. We identify the convergence range for specific properties and use them to discuss models of several glass compositions for which a possible influence of cooling-rate or size effects had been previously hypothesized. The trends highlighted here represent an important reference to obtain reliable models of multicomponent glasses and extract converged medium-range structural features which affect the glass degradation and thus their

Cooling rate and size effects on the medium-range structure of multicomponent oxide glasses simulated by molecular dynamics

International Nuclear Information System (INIS)

Tilocca, Antonio

2013-01-01

A set of molecular dynamics simulations were performed to investigate the effect of cooling rate and system size on the medium-range structure of melt-derived multicomponent silicate glasses, represented by the quaternary 45S5 Bioglass composition. Given the significant impact of the glass degradation on applications of these materials in biomedicine and nuclear waste disposal, bulk structural features which directly affect the glass dissolution process are of particular interest. Connectivity of the silicate matrix, ion clustering and nanosegregation, distribution of ring and chain structural patterns represent critical features in this context, which can be directly extracted from the models. A key issue is represented by the effect of the computational approach on the corresponding glass models, especially in light of recent indications questioning the suitability of conventional MD approaches (that is, involving melt-and-quench of systems containing ∼10 3 atoms at cooling rates of 5-10 K/ps) when applied to model these glasses. The analysis presented here compares MD models obtained with conventional and nonconventional cooling rates and system sizes, highlighting the trend and range of convergence of specific structural features in the medium range. The present results show that time-consuming computational approaches involving much lower cooling rates and/or significantly larger system sizes are in most cases not necessary in order to obtain a reliable description of the medium-range structure of multicomponent glasses. We identify the convergence range for specific properties and use them to discuss models of several glass compositions for which a possible influence of cooling-rate or size effects had been previously hypothesized. The trends highlighted here represent an important reference to obtain reliable models of multicomponent glasses and extract converged medium-range structural features which affect the glass degradation and thus their application

Statistics of vacuum breakdown in the high-gradient and low-rate regime

Science.gov (United States)

Wuensch, Walter; Degiovanni, Alberto; Calatroni, Sergio; Korsbäck, Anders; Djurabekova, Flyura; Rajamäki, Robin; Giner-Navarro, Jorge

2017-01-01

In an increasing number of high-gradient linear accelerator applications, accelerating structures must operate with both high surface electric fields and low breakdown rates. Understanding the statistical properties of breakdown occurrence in such a regime is of practical importance for optimizing accelerator conditioning and operation algorithms, as well as of interest for efforts to understand the physical processes which underlie the breakdown phenomenon. Experimental data of breakdown has been collected in two distinct high-gradient experimental set-ups: A prototype linear accelerating structure operated in the Compact Linear Collider Xbox 12 GHz test stands, and a parallel plate electrode system operated with pulsed DC in the kV range. Collected data is presented, analyzed and compared. The two systems show similar, distinctive, two-part distributions of number of pulses between breakdowns, with each part corresponding to a specific, constant event rate. The correlation between distance and number of pulses between breakdown indicates that the two parts of the distribution, and their corresponding event rates, represent independent primary and induced follow-up breakdowns. The similarity of results from pulsed DC to 12 GHz rf indicates a similar vacuum arc triggering mechanism over the range of conditions covered by the experiments.

Household structure vs. composition: Understanding gendered effects on educational progress in rural South Africa

Directory of Open Access Journals (Sweden)

Sangeetha Madhavan

2017-12-01

Full Text Available Background: Demographers have long been interested in the relationship between living arrangements and gendered outcomes for children in sub-Saharan Africa. Most research conflates household structure with composition and has revealed little about the pathways that link these components to gendered outcomes. Objective: We offer a conceptual approach that differentiates structure from composition with a focus on gendered processes that operate in the household in rural South Africa. Methods: We use data from the 2002 round of the Agincourt Health and Socio-Demographic Surveillance System. Our analytical sample includes 22,997 children aged 6‒18 who were neither parents themselves nor lived with a partner or partner's family. We employ ordinary least squares regression models to examine the effects of structure and composition on educational progress of girls and boys. Results: Non-nuclear structures are associated with similar negative effects for both boys and girls compared to children growing up in nuclear households. However, the presence of other kin in the absence of one or both parents results in gendered effects favouring boys. Conclusions: The absence of any gendered effects when using a household structure typology suggests that secular changes to attitudes about gender equity trump any specific gendered processes stemming from particular configurations. On the other hand, gendered effects that appear when one or both parents are absent show that traditional gender norms and/or resource constraints continue to favour boys. Contribution: We have shown the value of unpacking household structure to better understand how gender norms and gendered resource allocations are linked to an important outcome for children in sub-Saharan Africa.

Thermodynamic and structural models compared with the initial dissolution rates of SON glass samples

International Nuclear Information System (INIS)

Tovena, I.; Advocat, T.; Ghaleb, D.; Vernaz, E.

1993-01-01

The experimentally determined initial dissolution rate R 0 of nuclear glass was correlated with thermodynamic parameters and structural parameters. The initial corrosion rates of six ''R7T7'' glass samples measured at 100 deg C in a Soxhlet device were correlated with the glass free hydration energy and the glass formation enthalpy. These correlations were then tested with a group of 26 SON glasses selected for their wide diversity of compositions. The thermodynamic models provided a satisfactory approximation of the initial dissolution rate determined under Soxhlet conditions for SON glass samples that include up to 15 wt% of boron and some alumina. Conversely, these models are inaccurate if the boron concentration exceeds 15 wt% and the glass contains no alumina. Possible correlations between R 0 and structural parameters, such as the boron coordination number and the number of nonbridging oxygen atoms, were also investigated. The authors show that R 0 varies inversely with the number of 4-coordinate boron atoms; conversely, the results do not substantiate published reports of a correlation between R 0 and the number of nonbridging oxygen atoms. (authors). 13 refs., 2 figs., 4 tabs

Effect of pyrolysis pressure and heating rate on radiata pine char structure and apparent gasification reactivity

Energy Technology Data Exchange (ETDEWEB)

E. Cetin; R. Gupta; B. Moghtaderi [University of Newcastle, Callaghan, NSW (Australia). Discipline of Chemical Engineering, Faculty of Engineering and Built Environment, School of Engineering

2005-07-01

The knowledge of biomass char gasification kinetics has considerable importance in the design of advanced biomass gasifiers, some of which operate at high pressure. The char gasification kinetics themselves are influenced by char structure. In this study, the effects of pyrolysis pressure and heating rate on the char structure were investigated using scanning electron microscopy (SEM) analysis, digital cinematography, and surface area analysis. Char samples were prepared at pressures between 1 and 20 bar, temperatures ranging from 800 to 1000{degree}C, and heating rates between 20 and 500{degree}C/s. Our results indicate that pyrolysis conditions have a notable impact on the biomass char morphology. Pyrolysis pressure, in particular, was found to influence the size and the shape of char particles while high heating rates led to plastic deformation of particles (i.e. melting) resulting in smooth surfaces and large cavities. The global gasification reactivities of char samples were also determined using thermogravimetric analysis (TGA) technique. Char reactivities were found to increase with increasing pyrolysis heating rates and decreasing pyrolysis pressure. 22 refs., 8 figs., 2 tabs.

A phenomenographic study of the ways of understanding conditional and repetition structures in computer programming languages

Science.gov (United States)

Bucks, Gregory Warren

exploring the different ways of understanding held by individuals of two programming concepts: conditional structures and repetition structures. This work lays the foundation for the development of language independent assessment instruments, which can ultimately be used to assess the pedagogical implications of various programming environments.

Effects of system size and cooling rate on the structure and properties of sodium borosilicate glasses from molecular dynamics simulations.

Science.gov (United States)

Deng, Lu; Du, Jincheng

2018-01-14

Borosilicate glasses form an important glass forming system in both glass science and technologies. The structure and property changes of borosilicate glasses as a function of thermal history in terms of cooling rate during glass formation and simulation system sizes used in classical molecular dynamics (MD) simulation were investigated with recently developed composition dependent partial charge potentials. Short and medium range structural features such as boron coordination, Si and B Q n distributions, and ring size distributions were analyzed to elucidate the effects of cooling rate and simulation system size on these structure features and selected glass properties such as glass transition temperature, vibration density of states, and mechanical properties. Neutron structure factors, neutron broadened pair distribution functions, and vibrational density of states were calculated and compared with results from experiments as well as ab initio calculations to validate the structure models. The results clearly indicate that both cooling rate and system size play an important role on the structures of these glasses, mainly by affecting the 3 B and 4 B distributions and consequently properties of the glasses. It was also found that different structure features and properties converge at different sizes or cooling rates; thus convergence tests are needed in simulations of the borosilicate glasses depending on the targeted properties. The results also shed light on the complex thermal history dependence on structure and properties in borosilicate glasses and the protocols in MD simulations of these and other glass materials.

Effects of system size and cooling rate on the structure and properties of sodium borosilicate glasses from molecular dynamics simulations

Science.gov (United States)

Deng, Lu; Du, Jincheng

2018-01-01

Borosilicate glasses form an important glass forming system in both glass science and technologies. The structure and property changes of borosilicate glasses as a function of thermal history in terms of cooling rate during glass formation and simulation system sizes used in classical molecular dynamics (MD) simulation were investigated with recently developed composition dependent partial charge potentials. Short and medium range structural features such as boron coordination, Si and B Qn distributions, and ring size distributions were analyzed to elucidate the effects of cooling rate and simulation system size on these structure features and selected glass properties such as glass transition temperature, vibration density of states, and mechanical properties. Neutron structure factors, neutron broadened pair distribution functions, and vibrational density of states were calculated and compared with results from experiments as well as ab initio calculations to validate the structure models. The results clearly indicate that both cooling rate and system size play an important role on the structures of these glasses, mainly by affecting the 3B and 4B distributions and consequently properties of the glasses. It was also found that different structure features and properties converge at different sizes or cooling rates; thus convergence tests are needed in simulations of the borosilicate glasses depending on the targeted properties. The results also shed light on the complex thermal history dependence on structure and properties in borosilicate glasses and the protocols in MD simulations of these and other glass materials.

Experimental characterization of true spontaneous emission rate of optically-pumped InGaAs/GaAs quantum-well laser structure

Directory of Open Access Journals (Sweden)

Q.-N. Yu

2017-08-01

Full Text Available In this paper, an experimental approach to acquiring true spontaneous emission rate of optically-pumped InGaAs/GaAs quantum-well laser structure is described. This method is based on a single edge-emitting laser chip with simple sample processing. The photoluminescence spectra are measured at both facets of the edge-emitting device and transformed to the spontaneous emission rate following the theory described here. The unusual double peaks appearing in the spontaneous emission rate spectra are observed for the InGaAs/GaAs quantum-well structure. The result is analyzed in terms of Indium-rich island and Model-Solid theories. The proposed method is suitable for electrically-pumped quantum-well laser structures, as well.

Nuclear structure and weak rates of heavy waiting point nuclei under rp-process conditions

Science.gov (United States)

Nabi, Jameel-Un; Böyükata, Mahmut

2017-01-01

The structure and the weak interaction mediated rates of the heavy waiting point (WP) nuclei 80Zr, 84Mo, 88Ru, 92Pd and 96Cd along N = Z line were studied within the interacting boson model-1 (IBM-1) and the proton-neutron quasi-particle random phase approximation (pn-QRPA). The energy levels of the N = Z WP nuclei were calculated by fitting the essential parameters of IBM-1 Hamiltonian and their geometric shapes were predicted by plotting potential energy surfaces (PESs). Half-lives, continuum electron capture rates, positron decay rates, electron capture cross sections of WP nuclei, energy rates of β-delayed protons and their emission probabilities were later calculated using the pn-QRPA. The calculated Gamow-Teller strength distributions were compared with previous calculation. We present positron decay and continuum electron capture rates on these WP nuclei under rp-process conditions using the same model. For the rp-process conditions, the calculated total weak rates are twice the Skyrme HF+BCS+QRPA rates for 80Zr. For remaining nuclei the two calculations compare well. The electron capture rates are significant and compete well with the corresponding positron decay rates under rp-process conditions. The finding of the present study supports that electron capture rates form an integral part of the weak rates under rp-process conditions and has an important role for the nuclear model calculations.

Change in the structures, dynamics and disease-related mortality rates of the population of Qatari nationals: 2007-2011.

Science.gov (United States)

Al-Thani, Mohamed H; Sadoun, Eman; Al-Thani, Al-Anoud; Khalifa, Shamseldin A; Sayegh, Suzan; Badawi, Alaa

2014-12-01

Developing effective public health policies and strategies for interventions necessitates an assessment of the structure, dynamics, disease rates and causes of death in a population. Lately, Qatar has undertaken development resurgence in health and economy that resulted in improving the standard of health services and health status of the entire Qatari population (i.e., Qatari nationals and non-Qatari residents). No study has attempted to evaluate the population structure/dynamics and recent changes in disease-related mortality rates among Qatari nationals. The present study examines the population structure/dynamics and the related changes in the cause-specific mortality rates and disease prevalence in the Qatari nationals. This is a retrospective, analytic descriptive analysis covering a period of 5years (2007-2011) and utilizes a range of data sources from the State of Qatar including the population structure, disease-related mortality rates, and the prevalence of a range of chronic and infectious diseases. Factors reflecting population dynamics such as crude death (CDR), crude birth (CBR), total fertility (TFR) and infant mortality (IMR) rates were also calculated. The Qatari nationals is an expansive population with an annual growth rate of ∼4% and a stable male:female ratio. The CDR declined by 15% within the study period, whereas the CBR was almost stable. The total disease-specific death rate, however, was decreased among the Qatari nationals by 23% due to the decline in mortality rates attributed to diseases of the blood and immune system (43%), nervous system (44%) and cardiovascular system (41%). There was a high prevalence of a range of chronic diseases, whereas very low frequencies of the infectious diseases within the study population. Public health strategies, approaches and programs developed to reduce disease burden and the related death, should be tailored to target the population of Qatari nationals which exhibits characteristics that vary from

Understanding the genetic diversity and population structure of yam (Dioscorea alata L.) using microsatellite markers

Science.gov (United States)

Arnau, Gemma; MN, Sheela; Chair, Hana; Lebot, Vincent; K, Abraham; Perrier, Xavier; Petro, Dalila; Penet, Laurent; Pavis, Claudie

2017-01-01

Yams (Dioscorea sp.) are staple food crops for millions of people in tropical and subtropical regions. Dioscorea alata, also known as greater yam, is one of the major cultivated species and most widely distributed throughout the tropics. Despite its economic and cultural importance, very little is known about its origin, diversity and genetics. As a consequence, breeding efforts for resistance to its main disease, anthracnose, have been fairly limited. The objective of this study was to contribute to the understanding of D. alata genetic diversity by genotyping 384 accessions from different geographical regions (South Pacific, Asia, Africa and the Caribbean), using 24 microsatellite markers. Diversity structuration was assessed via Principal Coordinate Analysis, UPGMA analysis and the Bayesian approach implemented in STRUCTURE. Our results revealed the existence of a wide genetic diversity and a significant structuring associated with geographic origin, ploidy levels and morpho-agronomic characteristics. Seventeen major groups of genetically close cultivars have been identified, including eleven groups of diploid cultivars, four groups of triploids and two groups of tetraploids. STRUCTURE revealed the existence of six populations in the diploid genetic pool and a few admixed cultivars. These results will be very useful for rationalizing D. alata genetic resources in breeding programs across different regions and for improving germplasm conservation methods. PMID:28355293

Understanding Atomic Structure: Is There a More Direct and Compelling Connection between Atomic Line Spectra and the Quantization of an Atom's Energy?

Science.gov (United States)

Rittenhouse, Robert C.

2015-01-01

The "atoms first" philosophy, adopted by a growing number of General Chemistry textbook authors, places greater emphasis on atomic structure as a key to a deeper understanding of the field of chemistry. A pivotal concept needed to understand the behavior of atoms is the restriction of an atom's energy to specific allowed values. However,…

Understanding and Predicting Profile Structure and Parametric Scaling of Intrinsic Rotation

Science.gov (United States)

Wang, Weixing

2016-10-01

It is shown for the first time that turbulence-driven residual Reynolds stress can account for both the shape and magnitude of the observed intrinsic toroidal rotation profile. Nonlinear, global gyrokinetic simulations using GTS of DIII-D ECH plasmas indicate a substantial ITG fluctuation-induced non-diffusive momentum flux generated around a mid-radius-peaked intrinsic toroidal rotation profile. The non-diffusive momentum flux is dominated by the residual stress with a negligible contribution from the momentum pinch. The residual stress profile shows a robust anti-gradient, dipole structure in a set of ECH discharges with varying ECH power. Such interesting features of non-diffusive momentum fluxes, in connection with edge momentum sources and sinks, are found to be critical to drive the non-monotonic core rotation profiles in the experiments. Both turbulence intensity gradient and zonal flow ExB shear are identified as major contributors to the generation of the k∥-asymmetry needed for the residual stress generation. By balancing the residual stress and the momentum diffusion, a self-organized, steady-state rotation profile is calculated. The predicted core rotation profiles agree well with the experimentally measured main-ion toroidal rotation. The validated model is further used to investigate the characteristic dependence of global rotation profile structure in the multi-dimensional parametric space covering turbulence type, q-profile structure and collisionality with the goal of developing physics understanding needed for rotation profile control and optimization. Interesting results obtained include intrinsic rotation reversal induced by ITG-TEM transition in flat-q profile regime and by change in q-profile from weak to normal shear.. Fluctuation-generated poloidal Reynolds stress is also shown to significantly modify the neoclassical poloidal rotation in a way consistent with experimental observations. Finally, the first-principles-based model is applied

Understanding nucleic acid structural changes by comparing wide-angle x-ray scattering (WAXS) experiments to molecular dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Pabit, Suzette A.; Katz, Andrea M.; Pollack, Lois [School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States); Tolokh, Igor S. [Department of Computer Science, Virginia Tech, Blacksburg, Virginia 24061 (United States); Drozdetski, Aleksander [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States); Baker, Nathan [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Onufriev, Alexey V. [Department of Computer Science, Virginia Tech, Blacksburg, Virginia 24061 (United States); Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States)

2016-05-28

Wide-angle x-ray scattering (WAXS) is emerging as a powerful tool for increasing the resolution of solution structure measurements of biomolecules. Compared to its better known complement, small angle x-ray scattering (SAXS), WAXS targets higher scattering angles and can enhance structural studies of molecules by accessing finer details of solution structures. Although the extension from SAXS to WAXS is easy to implement experimentally, the computational tools required to fully harness the power of WAXS are still under development. Currently, WAXS is employed to study structural changes and ligand binding in proteins; however, the methods are not as fully developed for nucleic acids. Here, we show how WAXS can qualitatively characterize nucleic acid structures as well as the small but significant structural changes driven by the addition of multivalent ions. We show the potential of WAXS to test all-atom molecular dynamics (MD) simulations and to provide insight into understanding how the trivalent ion cobalt(III) hexammine (CoHex) affects the structure of RNA and DNA helices. We find that MD simulations capture the RNA structural change that occurs due to addition of CoHex.

Weak-interaction rates in stellar conditions

Science.gov (United States)

Sarriguren, Pedro

2018-05-01

Weak-interaction rates, including β-decay and electron captures, are studied in several mass regions at various densities and temperatures of astrophysical interest. In particular, we study odd-A nuclei in the pf-shell region, which are involved in presupernova formations. Weak rates are relevant to understand the late stages of the stellar evolution, as well as the nucleosynthesis of heavy nuclei. The nuclear structure involved in the weak processes is studied within a quasiparticle proton-neutron random-phase approximation with residual interactions in both particle-hole and particle-particle channels on top of a deformed Skyrme Hartree-Fock mean field with pairing correlations. First, the energy distributions of the Gamow-Teller strength are discussed and compared with the available experimental information, measured under terrestrial conditions from charge-exchange reactions. Then, the sensitivity of the weak-interaction rates to both astrophysical densities and temperatures is studied. Special attention is paid to the relative contribution to these rates of thermally populated excited states in the decaying nucleus and to the electron captures from the degenerate electron plasma.

Differences in proleptic and epicormic shoot structures in relation to water deficit and growth rate in almond trees (Prunus dulcis).

Science.gov (United States)

Negrón, Claudia; Contador, Loreto; Lampinen, Bruce D; Metcalf, Samuel G; Guédon, Yann; Costes, Evelyne; DeJong, Theodore M

2014-02-01

Shoot characteristics differ depending on the meristem tissue that they originate from and environmental conditions during their development. This study focused on the effects of plant water status on axillary meristem fate and flowering patterns along proleptic and epicormic shoots, as well as on shoot growth rates on 'Nonpareil' almond trees (Prunus dulcis). The aims were (1) to characterize the structural differences between proleptic and epicormic shoots, (2) to determine whether water deficits modify shoot structures differently depending on shoot type, and (3) to determine whether shoot structures are related to shoot growth rates. A hidden semi-Markov model of the axillary meristem fate and number of flower buds per node was built for two shoot types growing on trees exposed to three plant water status treatments. The models segmented observed shoots into successive homogeneous zones, which were compared between treatments. Shoot growth rates were calculated from shoot extension measurements made during the growing season. Proleptic shoots had seven successive homogeneous zones while epicormic shoots had five zones. Shoot structures were associated with changes in growth rate over the season. Water deficit (1) affected the occurrence and lengths of the first zones of proleptic shoots, but only the occurrence of the third zone was reduced in epicormic shoots; (2) had a minor effect on zone flowering patterns and did not modify shoot or zone composition of axillary meristem fates; and (3) reduced growth rates, although patterns over the season were similar among treatments. Two meristem types, with different latency durations, produced shoots with different growth rates and distinct structures. Differences between shoot type structure responses to water deficit appeared to reflect their ontogenetic characteristics and/or resource availability for their development. Tree water deficit appeared to stimulate a more rapid progression through ontogenetic states.

PAN-based carbon fiber negative electrodes for structural lithium-ion batteries

OpenAIRE

Hellqvist Kjell, Maria; Jacques, Eric; Zenkert, Dan; Behm, Mårten; Lindbergh, Göran

2011-01-01

Several grades of commercially-available polyacrylonitrile (PAN)-based carbon fibers have been studied for structural lithium-ion batteries to understand how the sizing, different lithiation rates and number of fibers per tow affect the available reversible capacity, when used as both current collector and electrode, for use in structural batteries. The study shows that at moderate lithiation rates, 100 mA g-1, most of the carbon fibers display a reversible capacity close to or above 100 mAh ...

Charging/discharging processes in nanocrystaline MOS structures - Theoretical study

International Nuclear Information System (INIS)

Tanous, D; Mazurak, A; Majkusiak, B

2016-01-01

We present the study of impact of some parameters of the metal-insulator-semiconductor structure with nanocrystals embedded in the insulator layer on the current-voltage and capacitance-voltage characteristics with the bias voltage ramp rate as a parameter. The developed model is used as a tool for theoretical understanding the physics behind charging and discharging processes in the considered structures. (paper)

Time-of-use rates vs. Hopkinson tariffs redux: an analysis of the choice of rate structures in a regulated electricity distribution company

International Nuclear Information System (INIS)

Seeto, Dewey; Woo, C.K.; Horowitz, Ira

1997-01-01

Recent proposals to restructure the electricity industry in North America may effect the disintegration of a vertically integrated company into several smaller entities, including distribution companies (DISCOs) We explore whether time-of-use (TOU) pricing or a Hopkinson tariff would be more suitable for a regulated DISCO. Focusing on the economic efficiency of these alternative rate structures, we argue that a Hopkinson tariff with demand subscription is superior to TOU rates, as it can better handle the limited load diversity of local transmission and distribution (TD) demands made on the contemporary DISCO, while finessing the problem of endogenous marginal costs of local TD capacity. (Author)

Implementation of 5E Inquiry Incorporated with Analogy Learning Approach to Enhance Conceptual Understanding of Chemical Reaction Rate for Grade 11 Students

Science.gov (United States)

Supasorn, Saksri; Promarak, Vinich

2015-01-01

The main purpose of this study was to enhance student understanding of the scientific concepts of chemical reaction rate. Forty-four grade 11 students were the target group. The treatment tools were seven learning plans of 5E inquiry incorporated with an analogy learning approach during 15 hours of class time. In each learning plan, the students…

Statistics of vacuum breakdown in the high-gradient and low-rate regime

Directory of Open Access Journals (Sweden)

Walter Wuensch

2017-01-01

Full Text Available In an increasing number of high-gradient linear accelerator applications, accelerating structures must operate with both high surface electric fields and low breakdown rates. Understanding the statistical properties of breakdown occurrence in such a regime is of practical importance for optimizing accelerator conditioning and operation algorithms, as well as of interest for efforts to understand the physical processes which underlie the breakdown phenomenon. Experimental data of breakdown has been collected in two distinct high-gradient experimental set-ups: A prototype linear accelerating structure operated in the Compact Linear Collider Xbox 12 GHz test stands, and a parallel plate electrode system operated with pulsed DC in the kV range. Collected data is presented, analyzed and compared. The two systems show similar, distinctive, two-part distributions of number of pulses between breakdowns, with each part corresponding to a specific, constant event rate. The correlation between distance and number of pulses between breakdown indicates that the two parts of the distribution, and their corresponding event rates, represent independent primary and induced follow-up breakdowns. The similarity of results from pulsed DC to 12 GHz rf indicates a similar vacuum arc triggering mechanism over the range of conditions covered by the experiments.

A Theory-Based Model for Understanding Faculty Intention to Use Students Ratings to Improve Teaching in a Health Sciences Institution in Puerto Rico

Science.gov (United States)

Collazo, Andrés A.

2018-01-01

A model derived from the theory of planned behavior was empirically assessed for understanding faculty intention to use student ratings for teaching improvement. A sample of 175 professors participated in the study. The model was statistically significant and had a very large explanatory power. Instrumental attitude, affective attitude, perceived…

Correlation structures in short-term variabilities of stock indices and exchange rates

Science.gov (United States)

Nakamura, Tomomichi; Small, Michael

2007-09-01

Financial data usually show irregular fluctuations and some trends. We investigate whether there are correlation structures in short-term variabilities (irregular fluctuations) among financial data from the viewpoint of deterministic dynamical systems. Our method is based on the small-shuffle surrogate method. The data we use are daily closing price of Standard & Poor's 500 and the volume, and daily foreign exchange rates, Euro/US Dollar (USD), British Pound/USD and Japanese Yen/USD. We found that these data are not independent.

Strain rate effects in stress corrosion cracking

Energy Technology Data Exchange (ETDEWEB)

Parkins, R.N. (Newcastle upon Tyne Univ. (UK). Dept. of Metallurgy and Engineering Materials)

1990-03-01

Slow strain rate testing (SSRT) was initially developed as a rapid, ad hoc laboratory method for assessing the propensity for metals an environments to promote stress corrosion cracking. It is now clear, however, that there are good theoretical reasons why strain rate, as opposed to stress per se, will often be the controlling parameter in determining whether or not cracks are nucleated and, if so, are propagated. The synergistic effects of the time dependence of corrosion-related reactions and microplastic strain provide the basis for mechanistic understanding of stress corrosion cracking in high-pressure pipelines and other structures. However, while this may be readily comprehended in the context of laboratory slow strain tests, its extension to service situations may be less apparent. Laboratory work involving realistic stressing conditions, including low-frequency cyclic loading, shows that strain or creep rates give good correlation with thresholds for cracking and with crack growth kinetics.

Structure and superconducting properties of Nb-Zr alloy films made by a high-rate sputtering

International Nuclear Information System (INIS)

Sekine, Hisashi; Inoue, Kiyoshi; Tachikawa, Kyoji

1978-01-01

Superconducting Nb-Zr alloy films have been prepared by a continuous high-rate sputtering on tantalum substrates. A deposition rate of 330 nm/min has been attained. The compositional profile in the Nb-Zr film is quite uniform and the film has nearly the same composition as that of the target. The films deposited in a pure argon atmosphere show a columnar structure grown perpendicular to the substrate. The grain size strongly depends on the substrate temperature. The phase transformations in the Nb-Zr film become more apparent and the structure becomes closer to the equilibrium state as the film is deposited in higher atmosphere pressures and/or at lower target voltages. The superconducting transition temperature T sub(c) of the films is about the same as that of bulk samples. The dependence of T sub(c) on the substrate temperature is explainable on the phase transformations in the film. Critical current density J sub(c) and its anisotropy is closely related to the grain structure of the film. Grain boundaries seem to act as the most predominant flux pinning centers in the films. Effects of oxygen in the sputtering atmosphere on the structure and superconducting properties of the Nb-Zr films have been also investigated. Oxygen significantly decreases the grain size of the film. Oxygen increases J sub(c) but decreases T sub(c) of the film. (auth.)

Understanding the structure of chocolate

Energy Technology Data Exchange (ETDEWEB)

Schenk, H. E-mail: schenk@science.uva.nl; Peschar, R

2004-11-01

Crystallization of cocoa-butter in the {beta} phase from the melt under static conditions is only possible using the memory effect of cocoa-butter. Under all other conditions polymorphs with lower melting temperatures develop, whereas the {beta} phase is the preferred one in chocolate. SAXS experiments proved 1,3-distearoyl-2-oleoylglycerol seeds with triple chain-length packing initiate the {beta}-crystallization. Models for the different phases may be based on the crystal structure determinations of triacylglycerols. A new, patented, way of chocolate making is in development in which the traditional tempering process is replaced by another pre-crystallization process. The process is based on the use of seed crystals in the liquid phase and driven by a feedback system.

Understanding the structure of chocolate

International Nuclear Information System (INIS)

Schenk, H.; Peschar, R.

2004-01-01

Crystallization of cocoa-butter in the β phase from the melt under static conditions is only possible using the memory effect of cocoa-butter. Under all other conditions polymorphs with lower melting temperatures develop, whereas the β phase is the preferred one in chocolate. SAXS experiments proved 1,3-distearoyl-2-oleoylglycerol seeds with triple chain-length packing initiate the β-crystallization. Models for the different phases may be based on the crystal structure determinations of triacylglycerols. A new, patented, way of chocolate making is in development in which the traditional tempering process is replaced by another pre-crystallization process. The process is based on the use of seed crystals in the liquid phase and driven by a feedback system

Understanding the structure of chocolate

Science.gov (United States)

Schenk, H.; Peschar, R.

2004-10-01

Crystallization of cocoa-butter in the β phase from the melt under static conditions is only possible using the memory effect of cocoa-butter. Under all other conditions polymorphs with lower melting temperatures develop, whereas the β phase is the preferred one in chocolate. SAXS experiments proved 1,3-distearoyl-2-oleoylglycerol seeds with triple chain-length packing initiate the β-crystallization. Models for the different phases may be based on the crystal structure determinations of triacylglycerols. A new, patented, way of chocolate making is in development in which the traditional tempering process is replaced by another pre-crystallization process. The process is based on the use of seed crystals in the liquid phase and driven by a feedback system.

Understanding ill-structured engineering ethics problems through a collaborative learning and argument visualization approach.

Science.gov (United States)

Hoffmann, Michael; Borenstein, Jason

2014-03-01

As a committee of the National Academy of Engineering recognized, ethics education should foster the ability of students to analyze complex decision situations and ill-structured problems. Building on the NAE's insights, we report about an innovative teaching approach that has two main features: first, it places the emphasis on deliberation and on self-directed, problem-based learning in small groups of students; and second, it focuses on understanding ill-structured problems. The first innovation is motivated by an abundance of scholarly research that supports the value of deliberative learning practices. The second results from a critique of the traditional case-study approach in engineering ethics. A key problem with standard cases is that they are usually described in such a fashion that renders the ethical problem as being too obvious and simplistic. The practitioner, by contrast, may face problems that are ill-structured. In the collaborative learning environment described here, groups of students use interactive and web-based argument visualization software called "AGORA-net: Participate - Deliberate!". The function of the software is to structure communication and problem solving in small groups. Students are confronted with the task of identifying possible stakeholder positions and reconstructing their legitimacy by constructing justifications for these positions in the form of graphically represented argument maps. The argument maps are then presented in class so that these stakeholder positions and their respective justifications become visible and can be brought into a reasoned dialogue. Argument mapping provides an opportunity for students to collaborate in teams and to develop critical thinking and argumentation skills.

Understanding the proton's spin structure

Energy Technology Data Exchange (ETDEWEB)

Myhrer, Fred [Univ. of South Carolina, Columbia, SC (United States); Thomas, Anthony W. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); College of William and Mary, Williamsburg, VA (United States)

2010-02-01

We discuss the tremendous progress that has been towards an understanding of how the spin of the proton is distributed on its quark and gluon constituents. This is a problem that began in earnest twenty years ago with the discovery of the proton "spin crisis" by the European Muon Collaboration. The discoveries prompted by that original work have given us unprecedented insight into the amount of spin carried by polarized gluons and the orbital angular momentum of the quarks.

The Structure and Dynamics of GRB Jets

Energy Technology Data Exchange (ETDEWEB)

Granot, Jonathan; /KIPAC, Menlo Park

2006-10-25

There are several lines of evidence which suggest that the relativistic outflows in gamma-ray bursts (GRBs) are collimated into narrow jets. The jet structure has important implications for the true energy release and the event rate of GRBs, and can constrain the mechanism responsible for the acceleration and collimation of the jet. Nevertheless, the jet structure and its dynamics as it sweeps up the external medium and decelerates, are not well understood. In this review I discuss our current understanding of GRB jets, stressing their structure and dynamics.

Understanding changes in cellulose crystalline structure of lignocellulosic biomass during ionic liquid pretreatment by XRD.

Science.gov (United States)

Zhang, Jiafu; Wang, Yixun; Zhang, Liye; Zhang, Ruihong; Liu, Guangqing; Cheng, Gang

2014-01-01

X-ray diffraction (XRD) was used to understand the interactions of cellulose in lignocellulosic biomass with ionic liquids (ILs). The experiment was designed in such a way that the process of swelling and solubilization of crystalline cellulose in plant cell walls was followed by XRD. Three different feedstocks, switchgrass, corn stover and rice husk, were pretreated using 1-butyl-3-methylimidazolium acetate ([C4mim][OAc]) at temperatures of 50-130°C for 6h. At a 5 wt.% biomass loading, increasing pretreatment temperature led to a drop in biomass crystallinity index (CrI), which was due to swelling of crystalline cellulose. After most of the crystalline cellulose was swollen with IL molecules, a low-order structure was found in the pretreated samples. Upon further increasing temperature, cellulose II structure started to form in the pretreated biomass samples as a result of solubilization of cellulose in [C4mim][OAc] and subsequent regeneration. Copyright © 2013 Elsevier Ltd. All rights reserved.

The everyday lives of video game developers: Experimentally understanding underlying systems/structures

Directory of Open Access Journals (Sweden)

Casey O'Donnell

2009-03-01

Full Text Available This essay examines how tensions between work and play for video game developers shape the worlds they create. The worlds of game developers, whose daily activity is linked to larger systems of experimentation and technoscientific practice, provide insights that transcend video game development work. The essay draws on ethnographic material from over 3 years of fieldwork with video game developers in the United States and India. It develops the notion of creative collaborative practice based on work in the fields of science and technology studies, game studies, and media studies. The importance of, the desire for, or the drive to understand underlying systems and structures has become fundamental to creative collaborative practice. I argue that the daily activity of game development embodies skills fundamental to creative collaborative practice and that these capabilities represent fundamental aspects of critical thought. Simultaneously, numerous interests have begun to intervene in ways that endanger these foundations of creative collaborative practice.

Do purchasing power parity and uncovered interest rate parity hold in the long run?

DEFF Research Database (Denmark)

Juselius, Katarina

1995-01-01

The long-run foreign transmission effects are analyzed in a multivariate time-series model of Danish and German prices, exchange rates and interest rates. The analysis of the likelihood function reveals that the vector process is I(2), but that a linear transformation of the prices and the nomical...... exchange rate removes the I(2) trend from the data. A structural representation of the full cointegration space is found to facilitate the understanding of the interaction between the goods and the capital market and hence the mechanisms behind the inflationary effects transmitted from abroad...

Attitudes and Defaults Save Lives and Protect the Environment Jointly and Compensatorily: Understanding the Behavioral Efficacy of Nudges and Other Structural Interventions

Directory of Open Access Journals (Sweden)

Florian G. Kaiser

2014-07-01

Full Text Available A better understanding of when and why nudges (e.g., defaults, visibility or accessibility alterations and other structural behavior-change measures work or fail can help avoid subsequent surprises such as unexpected political opposition. In this paper, we challenge the unilateral focus on structural interventions—which seemingly control people's behavioral decisions—as such a focus ignores the flipside—namely, attitudes or, as they are called in economics, preferences. We argue for a conceptual understanding of individual behavior that views personal attitudes and behavioral costs as its two separate compensatorily effective determinants. This classical understanding was reintroduced into attitude research as the Campbell paradigm. In the logic of the Campbell paradigm, a person's attitude becomes obvious in the face of the behavioral costs the person surmounts. Technically, individual attitudes reveal themselves in a set of cost-dependent transitively ordered performances. Behavioral costs in turn reflect the structural boundary conditions that are relevant as obstructive and/or supportive environmental forces that generically affect a specific behavior. So far, our research on people’s attitudes toward environmental protection has demonstrated that the Campbell paradigm—and thus its conceptual account of individual behavior—holds true for approximately 95% of the people in a given society.

Attitudes and defaults save lives and protect the environment jointly and compensatorily: understanding the behavioral efficacy of nudges and other structural interventions.

Science.gov (United States)

Kaiser, Florian G; Arnold, Oliver; Otto, Siegmar

2014-09-01

A better understanding of when and why nudges (e.g., defaults, visibility or accessibility alterations) and other structural behavior-change measures work or fail can help avoid subsequent surprises such as unexpected political opposition. In this paper, we challenge the unilateral focus on structural interventions-which seemingly control people's behavioral decisions-as such a focus ignores the flipside-namely, attitudes or, as they are called in economics, preferences. We argue for a conceptual understanding of individual behavior that views personal attitudes and behavioral costs as its two separate compensatorily effective determinants. This classical understanding was reintroduced into attitude research as the Campbell paradigm. In the logic of the Campbell paradigm, a person's attitude becomes obvious in the face of the behavioral costs the person surmounts. Technically, individual attitudes reveal themselves in a set of cost-dependent transitively ordered performances. Behavioral costs in turn reflect the structural boundary conditions that are relevant as obstructive and/or supportive environmental forces that generically affect a specific behavior. So far, our research on people's attitudes toward environmental protection has demonstrated that the Campbell paradigm-and thus its conceptual account of individual behavior-holds true for approximately 95% of the people in a given society.

Attitudes and Defaults Save Lives and Protect the Environment Jointly and Compensatorily: Understanding the Behavioral Efficacy of Nudges and Other Structural Interventions

Science.gov (United States)

Kaiser, Florian G.; Arnold, Oliver; Otto, Siegmar

2014-01-01

A better understanding of when and why nudges (e.g., defaults, visibility or accessibility alterations) and other structural behavior-change measures work or fail can help avoid subsequent surprises such as unexpected political opposition. In this paper, we challenge the unilateral focus on structural interventions—which seemingly control people's behavioral decisions—as such a focus ignores the flipside—namely, attitudes or, as they are called in economics, preferences. We argue for a conceptual understanding of individual behavior that views personal attitudes and behavioral costs as its two separate compensatorily effective determinants. This classical understanding was reintroduced into attitude research as the Campbell paradigm. In the logic of the Campbell paradigm, a person's attitude becomes obvious in the face of the behavioral costs the person surmounts. Technically, individual attitudes reveal themselves in a set of cost-dependent transitively ordered performances. Behavioral costs in turn reflect the structural boundary conditions that are relevant as obstructive and/or supportive environmental forces that generically affect a specific behavior. So far, our research on people’s attitudes toward environmental protection has demonstrated that the Campbell paradigm—and thus its conceptual account of individual behavior—holds true for approximately 95% of the people in a given society. PMID:25379277

Aeroelastic impact of above-rated wave-induced structural motions on the near-wake stability of a floating offshore wind turbine rotor

Science.gov (United States)

Rodriguez, Steven; Jaworski, Justin

2017-11-01

The impact of above-rated wave-induced motions on the stability of floating offshore wind turbine near-wakes is studied numerically. The rotor near-wake is generated using a lifting-line free vortex wake method, which is strongly coupled to a finite element solver for kinematically nonlinear blade deformations. A synthetic time series of relatively high-amplitude/high-frequency representative of above-rated conditions of the NREL 5MW referece wind turbine is imposed on the rotor structure. To evaluate the impact of these above-rated conditions, a linear stability analysis is first performed on the near wake generated by a fixed-tower wind turbine configuration at above-rated inflow conditions. The platform motion is then introduced via synthetic time series, and a stability analysis is performed on the wake generated by the floating offshore wind turbine at the same above-rated inflow conditions. The stability trends (disturbance modes versus the divergence rate of vortex structures) of the two analyses are compared to identify the impact that above-rated wave-induced structural motions have on the stability of the floating offshore wind turbine wake.

Rate-based structural health monitoring using permanently installed sensors

Science.gov (United States)

Corcoran, Joseph

2017-09-01

Permanently installed sensors are becoming increasingly ubiquitous, facilitating very frequent in situ measurements and consequently improved monitoring of `trends' in the observed system behaviour. It is proposed that this newly available data may be used to provide prior warning and forecasting of critical events, particularly system failure. Numerous damage mechanisms are examples of positive feedback; they are `self-accelerating' with an increasing rate of damage towards failure. The positive feedback leads to a common time-response behaviour which may be described by an empirical relation allowing prediction of the time to criticality. This study focuses on Structural Health Monitoring of engineering components; failure times are projected well in advance of failure for fatigue, creep crack growth and volumetric creep damage experiments. The proposed methodology provides a widely applicable framework for using newly available near-continuous data from permanently installed sensors to predict time until failure in a range of application areas including engineering, geophysics and medicine.

Public understandings of genetics and health.

Science.gov (United States)

Condit, C M

2010-01-01

This review of adult public understandings of genetics related to health indicates that the public's understandings overlap with those of professionals in some areas, but not others. Specifically, the majority of the world's people who have been studied understand genetics through the lens of heredity, not in terms of the structural and functional nature of genes. Public understandings of hereditary processes are influenced by models of social relationships and by experiential familiarity with particular conditions as much as by academic research results. Most people hold a fairly strong belief that many health conditions are substantially influenced by both genes and other factors. However, they do not have a stable understanding of the nature of gene-environment interactions. People in cultures where science is not a prominent cultural mode are even less likely to hold the belief structures of professional geneticists. In some areas--notably with regard to racialization of genetic medicine and characterizations of genetic variations as 'mutations'--at least some members of the public strongly reject some geneticists' constructions. Public understanding of details pertinent to genetic testing generally appears to be weak.

Development of highly flexible and ultra-low permeation rate thin-film barrier structure for organic electronics

International Nuclear Information System (INIS)

Kim, Namsu; Graham, Samuel

2013-01-01

A flexible thin-film encapsulation architecture for organic electronics was built and consisted of a silicon oxide/alumina and parylene layer deposited over Ca sensors on a barrier-coated polyethylene terephthalate substrate. The film's effective water vapor transmission rate was 2.4 ± 1.5 × 10 −5 g/m 2 /day at 20 °C and 50% relative humidity. Flexural tests revealed that for films deposited on the polyethylene terephthalate substrate, the barrier layer failed due to cracking at a curvature radius of 6.4 mm, corresponding to a strain of 0.8%. Adding an epoxy top coat of suitable thickness shifted the neutral axis toward the encapsulation layer, reducing the induced strain. Barrier performance was maintained under the 6.4 mm radius of curvature in this encapsulation structure. Thus, shifting the neutral axis via device structural design is an effective method of extending the flexibility of thin-film encapsulation structure without compromising the performance loss as a barrier layer. - Highlights: • High performance barrier is fabricated on flexible substrate. • The water vapor transmission rate is 2.4 ± 1.5 × 10 −5 g/m 2 /day. • The structure maintains its performance under a small radius of bending curvature

Understanding understanding in secondary school science: An interpretive study

Science.gov (United States)

O'Neill, Maureen Gail

This study investigated the teaching of secondary school science with an emphasis on promoting student understanding. In particular, I focused on two research questions: What are the possible meanings of teaching for understanding? And, how might one teach secondary school science for understanding? After semi-structured interviews were conducted with 13 secondary school science teachers, grounded theory methodology was used to interpret the data. As a result of the selective coding process, I was able to identify 14 connected components of teaching for understanding (TfU). The process of TfU involves: puzzle-solving, a specific pedagogy and a conscious decision. The teacher must be a reflective practitioner who has some knowledge of the facets of understanding. The teacher comes to a critical incident or crisis in his or her pedagogy and adopts a mindset which highlights TfU as a personal problematic. Teachers operate with student-centred rather than teacher-centred metaphors. TfU requires a firm belief in and passion for the process, a positive attitude and excellent pedagogical content knowledge. It hinges on a performance view of understanding and demands risk-taking in the science classroom. Abstracting these ideas to a theory led me to the notion of Purposive Teaching . In their purposive-driven role as pedagogues, these teachers have placed TfU at the core of their daily practice. Constraints and challenges facing TfU as well as implications of the findings are discussed. Keywords. science teaching, teaching for understanding, purposive teaching, constructivism, understanding, pedagogy, pedagogical content knowledge, memorization, meaningful learning, reflective practice.

Structure analysis of tax revenue and inflation rate in Banda Aceh using vector error correction model with multiple alpha

Science.gov (United States)

Sofyan, Hizir; Maulia, Eva; Miftahuddin

2017-11-01

A country has several important parameters to achieve economic prosperity, such as tax revenue and inflation rate. One of the largest revenues of the State Budget in Indonesia comes from the tax sector. Meanwhile, the rate of inflation occurring in a country can be used as an indicator, to measure the good and bad economic problems faced by the country. Given the importance of tax revenue and inflation rate control in achieving economic prosperity, it is necessary to analyze the structure of tax revenue relations and inflation rate. This study aims to produce the best VECM (Vector Error Correction Model) with optimal lag using various alpha and perform structural analysis using the Impulse Response Function (IRF) of the VECM models to examine the relationship of tax revenue, and inflation in Banda Aceh. The results showed that the best model for the data of tax revenue and inflation rate in Banda Aceh City using alpha 0.01 is VECM with optimal lag 2, while the best model for data of tax revenue and inflation rate in Banda Aceh City using alpha 0.05 and 0,1 VECM with optimal lag 3. However, the VECM model with alpha 0.01 yielded four significant models of income tax model, inflation rate of Banda Aceh, inflation rate of health and inflation rate of education in Banda Aceh. While the VECM model with alpha 0.05 and 0.1 yielded one significant model that is income tax model. Based on the VECM models, then there are two structural analysis IRF which is formed to look at the relationship of tax revenue, and inflation in Banda Aceh, the IRF with VECM (2) and IRF with VECM (3).

Impact of deposition rate on the structural and magnetic properties of sputtered Ni/Cu multilayer thin films

Energy Technology Data Exchange (ETDEWEB)

Karpuz, Ali [Karamanoglu Mehmetbey Univ., Karaman (Turkey). Dept. of Physics; Colmekci, Salih; Kockar, Hakan; Kuru, Hilal; Uckun, Mehmet [Balikesir Univ. (Turkey). Dept. of Physics

2018-04-01

The structural and corresponding magnetic properties of Ni/Cu films sputtered at low and high deposition rates were investigated as there is a limited number of related studies in this field. 5[Ni(10 nm)/Cu(30 nm)] multilayer thin films were deposited using two DC sputtering sources at low (0.02 nm/s) and high (0.10 nm/s) deposition rates of Ni layers. A face centered cubic phase was detected for both films. The surface of the film sputtered at the low deposition rate has a lot of micro-grains distributed uniformly and with sizes from 0.1 to 0.4 μm. Also, it has a vertical acicular morphology. At high deposition rate, the number of micro-grains considerably decreased, and some of their sizes increased up to 1 μm. The surface of the Ni/Cu multilayer deposited at the low rate has a relatively more grainy and rugged structure, whereas the surface of the film deposited at the high rate has a relatively larger lateral size of surface grains with a relatively fine morphology. Saturation magnetisation, M{sub s}, values were 90 and 138 emu/cm{sup 3} for deposition rates of 0.02 and 0.10 nm/s, respectively. Remanence, M{sub r}, values were also found to be 48 and 71 emu/cm{sup 3} for the low and high deposition rates, respectively. The coercivity, H{sub c}, values were 46 and 65 Oe for the low and high Ni deposition rates, respectively. The changes in the film surfaces provoked the changes in the H{sub c} values. The M{sub s}, M{sub r}, and H{sub c} values of the 5[Ni(10 nm)/Cu(30 nm)] films can be adjusted considering the surface morphologies and film contents caused by the different Ni deposition rates.

Effect of temperature gradient and crystallization rate on morphological peculiarities of cellular-dendrite structure in iron-nickel alloys

International Nuclear Information System (INIS)

Kralina, A.A.; Vorontsov, V.B.

1977-01-01

Cellular and dendritic structure of Fe-Ni single crystals (31 and 45 wt%Ni) grown according to Bridgeman have been studied by metallography. Growth rates at which the crystallization frontier becomes unstable and splits into cells have been determined for three temperature gradients. The transition from cells to dendrites occurs gradually through the changes in the cells regular structure and formation of secondary and tertiary branches. The dependence of cell diameter and distance between dendrites on crystallization rate and temperature gradient are discussed in terms of the admixture substructures development according to the schedule: cells - cellular dendrites - dendrites

Testing Hypotheses in an I(2) Model with Applications to the Persistent Long Swings in the Dmk/$ Rate

DEFF Research Database (Denmark)

Johansen, Søren; Juselius, Katarina; Frydman, Roman

and persistent swings in the foreign exchange market between Germany and USA. The data analyzed consist of nominal exchange rates, relative prices, US inflation rate, two long-term interest rates and two short-term interest rates over the 1975-1999 period. One important aim of the paper is to demonstrate...... that by structuring the data with the help of the I(2) model one can achieve a better understanding of the empirical regularities underlying the persistent swings in nominal exchange rates, typical in periods of floating exchange rates...

Formation of hydrogen bonds precedes the rate-limiting formation of persistent structure in the folding of ACBP

DEFF Research Database (Denmark)

Teilum, K; Kragelund, B B; Knudsen, J

2000-01-01

A burst phase in the early folding of the four-helix two-state folder protein acyl-coenzyme A binding protein (ACBP) has been detected using quenched-flow in combination with site-specific NMR-detected hydrogen exchange. Several of the burst phase structures coincide with a structure consisting...... of eight conserved hydrophobic residues at the interface between the two N and C-terminal helices. Previous mutation studies have shown that the formation of this structure is rate limiting for the final folding of ACBP. The burst phase structures observed in ACBP are different from the previously reported...

Structural growth trajectories and rates of change in the first 3 months of infant brain development.

Science.gov (United States)

Holland, Dominic; Chang, Linda; Ernst, Thomas M; Curran, Megan; Buchthal, Steven D; Alicata, Daniel; Skranes, Jon; Johansen, Heather; Hernandez, Antonette; Yamakawa, Robyn; Kuperman, Joshua M; Dale, Anders M

2014-10-01

The very early postnatal period witnesses extraordinary rates of growth, but structural brain development in this period has largely not been explored longitudinally. Such assessment may be key in detecting and treating the earliest signs of neurodevelopmental disorders. To assess structural growth trajectories and rates of change in the whole brain and regions of interest in infants during the first 3 months after birth. Serial structural T1-weighted and/or T2-weighted magnetic resonance images were obtained for 211 time points from 87 healthy term-born or term-equivalent preterm-born infants, aged 2 to 90 days, between October 5, 2007, and June 12, 2013. We segmented whole-brain and multiple subcortical regions of interest using a novel application of Bayesian-based methods. We modeled growth and rate of growth trajectories nonparametrically and assessed left-right asymmetries and sexual dimorphisms. Whole-brain volume at birth was approximately one-third of healthy elderly brain volume, and did not differ significantly between male and female infants (347 388 mm3 and 335 509 mm3, respectively, P = .12). The growth rate was approximately 1%/d, slowing to 0.4%/d by the end of the first 3 months, when the brain reached just more than half of elderly adult brain volume. Overall growth in the first 90 days was 64%. There was a significant age-by-sex effect leading to widening separation in brain sizes with age between male and female infants (with male infants growing faster than females by 200.4 mm3/d, SE = 67.2, P = .003). Longer gestation was associated with larger brain size (2215 mm3/d, SE = 284, P = 4×10-13). The expected brain size of an infant born one week earlier than average was 5% smaller than average; at 90 days it will not have caught up, being 2% smaller than average. The cerebellum grew at the highest rate, more than doubling in 90 days, and the hippocampus grew at the slowest rate, increasing by 47% in 90 days. There was left

Size and structure of Chlorella zofingiensis /FeCl ₃ flocs in a shear flow: Algae Floc Structure

Energy Technology Data Exchange (ETDEWEB)

Wyatt, Nicholas B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); O' Hern, Timothy J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Shelden, Bion [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hughes, Lindsey G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mondy, Lisa A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2013-07-26

Flocculation is a promising method to overcome the economic hurdle to separation of algae from its growth medium in large scale operations. But, understanding of the floc structure and the effects of shear on the floc structure are crucial to the large scale implementation of this technique. The floc structure is important because it determines, in large part, the density and settling behavior of the algae. Freshwater algae floc size distributions and fractal dimensions are presented as a function of applied shear rate in a Couette cell using ferric chloride as a flocculant. Comparisons are made with measurements made for a polystyrene microparticle model system taken here as well as reported literature results. The algae floc size distributions are found to be self-preserving with respect to shear rate, consistent with literature data for polystyrene. Moreover, three fractal dimensions are calculated which quantitatively characterize the complexity of the floc structure. Low shear rates result in large, relatively dense packed flocs which elongate and fracture as the shear rate is increased. Our results presented here provide crucial information for economically implementing flocculation as a large scale algae harvesting strategy.

Predicting prey population dynamics from kill rate, predation rate and predator-prey ratios in three wolf-ungulate systems.

Science.gov (United States)

Vucetich, John A; Hebblewhite, Mark; Smith, Douglas W; Peterson, Rolf O

2011-11-01

1. Predation rate (PR) and kill rate are both fundamental statistics for understanding predation. However, relatively little is known about how these statistics relate to one another and how they relate to prey population dynamics. We assess these relationships across three systems where wolf-prey dynamics have been observed for 41 years (Isle Royale), 19 years (Banff) and 12 years (Yellowstone). 2. To provide context for this empirical assessment, we developed theoretical predictions of the relationship between kill rate and PR under a broad range of predator-prey models including predator-dependent, ratio-dependent and Lotka-Volterra dynamics. 3. The theoretical predictions indicate that kill rate can be related to PR in a variety of diverse ways (e.g. positive, negative, unrelated) that depend on the nature of predator-prey dynamics (e.g. structure of the functional response). These simulations also suggested that the ratio of predator-to-prey is a good predictor of prey growth rate. That result motivated us to assess the empirical relationship between the ratio and prey growth rate for each of the three study sites. 4. The empirical relationships indicate that PR is not well predicted by kill rate, but is better predicted by the ratio of predator-to-prey. Kill rate is also a poor predictor of prey growth rate. However, PR and ratio of predator-to-prey each explained significant portions of variation in prey growth rate for two of the three study sites. 5. Our analyses offer two general insights. First, Isle Royale, Banff and Yellowstone are similar insomuch as they all include wolves preying on large ungulates. However, they also differ in species diversity of predator and prey communities, exploitation by humans and the role of dispersal. Even with the benefit of our analysis, it remains difficult to judge whether to be more impressed by the similarities or differences. This difficulty nicely illustrates a fundamental property of ecological

The Application of Structural Equation Modeling to Maternal Ratings of Twins' Behavior and Emotional Problems.

Science.gov (United States)

Silberg, Judy L.; And Others

1994-01-01

Applied structural equation modeling to twin data to assess impact of genetic and environmental factors on children's behavioral and emotional functioning. Applied models to maternal ratings of behavior of 515 monozygotic and 749 dizygotic twin pairs. Importance of genetic, shared, and specific environmental factors for explaining variation was…

Effect of Heating Rate on Grain Structure and Superplasticity of 7B04 Aluminum Alloy Sheets

Directory of Open Access Journals (Sweden)

CHEN Min

2017-03-01

Full Text Available Fine-grained 7B04 aluminum alloy sheets were manufactured through thermo-mechanical treatment. The effects of anneal heating rate on grain structure and superplasticity were investigated using electron back scattering diffraction(EBSD and high temperature tensile test. The results show that at the heating rate of 5.0×10-3K/s, the average grain sizes along the rolling direction(RD and normal direction(ND are 28.2μm and 13.9μm respectively, the nucleation rate is 1/1000. With the increase of heating rate, the average grain size decreases, and the nucleation rate increases. When the heating rate increases to 30.0K/s, the average grain sizes along the RD and ND decrease respectively to 9.9μm and 5.1μm, and the nucleation rate increases to 1/80. Besides, with the increase of heating rate, the elongation of sheets also increases. The elongation of the specimens increases from 100% to 730% under the deforming condition of 773K/8×10-4s-1.

Appreciating the ties that bind technical communication to culture: A dynamic model to help us understand differences in discourse structure

DEFF Research Database (Denmark)

Kastberg, Peter; Kampf, Constance

In order to support an explicit understanding of cultural patterns as both dynamic and structured, we will examine Hofstede?s model for stabilization of cultural patterns, and use this model to explore some cultural consequences for patterns of logic and signs that influence the effectiveness of ...

Asymmetry and Risk Premia in the Brazilian Term Structure of Interest Rates

Directory of Open Access Journals (Sweden)

Marcelo Ganem

2011-06-01

Full Text Available The risk premium in the Brazilian term structure of interest rates is partially driven by some specific defensive behavior following past monetary decisions. Until 2008, the Brazilian Central Bank has primarily dealt with domestic and external crises by raising the short term rate to restrain capital outflows, generating a well-known asymmetry in the market’s response functions to risk aversion. Therefore, the traditional parameterization of risk based on mean and variance estimators fails to capture the market price of risk eventually assigned to higher order moments of bond returns across several maturities. In this paper we propose an arbitrage-free, discrete-time model that provides the form for a lagged endogenous regression which tests the significance and magnitude of the market price of asymmetry in the Brazilian fixed income market. The results are analyzed from a historical perspective, comparing the evolution of the price of asymmetry, the improvement of Brazil’s sovereign risk and the monetary policy conduction from 2003 to 2009.

Pre-operational proof and leakage rate testing requirements for concrete containment structures for CANDU nuclear power plants

International Nuclear Information System (INIS)

1994-02-01

This Standard provides the requirements for pre-operational proof tests and leakage rate tests of concrete containment structures of a containment system designed as Class Containment components. 1 fig

Chiropractic physicians: toward a select conceptual understanding of bureaucratic structures and functions in the health care institution

Science.gov (United States)

Fredericks, Marcel; Kondellas, Bill; Hang, Lam; Fredericks, Janet; Ross, Michael WV

2011-01-01

Objective The purpose of this article is to present select concepts and theories of bureaucratic structures and functions so that chiropractic physicians and other health care professionals can use them in their respective practices. The society-culture-personality model can be applied as an organizational instrument for assisting chiropractors in the diagnosis and treatment of their patients irrespective of locality. Discussion Society-culture-personality and social meaningful interaction are examined in relationship to the structural and functional aspects of bureaucracy within the health care institution of a society. Implicit in the examination of the health care bureaucratic structures and functions of a society is the focus that chiropractic physicians and chiropractic students learn how to integrate, synthesize, and actualize values and virtues such as empathy, integrity, excellence, diversity, compassion, caring, and understanding with a deep commitment to self-reflection. Conclusion It is essential that future and current chiropractic physicians be aware of the structural and functional aspects of an organization so that chiropractic and other health care professionals are able to deliver care that involves the ingredients of quality, affordability, availability, accessibility, and continuity for their patients. PMID:22693481

Chiropractic physicians: toward a select conceptual understanding of bureaucratic structures and functions in the health care institution.

Science.gov (United States)

Fredericks, Marcel; Kondellas, Bill; Hang, Lam; Fredericks, Janet; Ross, Michael Wv

2011-12-01

The purpose of this article is to present select concepts and theories of bureaucratic structures and functions so that chiropractic physicians and other health care professionals can use them in their respective practices. The society-culture-personality model can be applied as an organizational instrument for assisting chiropractors in the diagnosis and treatment of their patients irrespective of locality. Society-culture-personality and social meaningful interaction are examined in relationship to the structural and functional aspects of bureaucracy within the health care institution of a society. Implicit in the examination of the health care bureaucratic structures and functions of a society is the focus that chiropractic physicians and chiropractic students learn how to integrate, synthesize, and actualize values and virtues such as empathy, integrity, excellence, diversity, compassion, caring, and understanding with a deep commitment to self-reflection. It is essential that future and current chiropractic physicians be aware of the structural and functional aspects of an organization so that chiropractic and other health care professionals are able to deliver care that involves the ingredients of quality, affordability, availability, accessibility, and continuity for their patients.

Effects of cooking methods and starch structures on starch hydrolysis rates of rice.

Science.gov (United States)

Reed, Michael O; Ai, Yongfeng; Leutcher, Josh L; Jane, Jay-lin

2013-07-01

This study aimed to understand effects of different cooking methods, including steamed, pilaf, and traditional stir-fried, on starch hydrolysis rates of rice. Rice grains of 3 varieties, japonica, indica, and waxy, were used for the study. Rice starch was isolated from the grain and characterized. Amylose contents of starches from japonica, indica, and waxy rice were 13.5%, 18.0%, and 0.9%, respectively. The onset gelatinization temperature of indica starch (71.6 °C) was higher than that of the japonica and waxy starch (56.0 and 56.8 °C, respectively). The difference was attributed to longer amylopectin branch chains of the indica starch. Starch hydrolysis rates and resistant starch (RS) contents of the rice varieties differed after they were cooked using different methods. Stir-fried rice displayed the least starch hydrolysis rate followed by pilaf rice and steamed rice for each rice variety. RS contents of freshly steamed japonica, indica, and waxy rice were 0.7%, 6.6%, and 1.3%, respectively; those of rice pilaf were 12.1%, 13.2%, and 3.4%, respectively; and the stir-fried rice displayed the largest RS contents of 15.8%, 16.6%, and 12.1%, respectively. Mechanisms of the large RS contents of the stir-fried rice were studied. With the least starch hydrolysis rate and the largest RS content, stir-fried rice would be a desirable way of preparing rice for food to reduce postprandial blood glucose and insulin responses and to improve colon health of humans. © 2013 Institute of Food Technologists®

Understanding the oil price-exchange rate nexus for the Fiji islands

International Nuclear Information System (INIS)

Narayan, Paresh Kumar; Narayan, Seema; Prasad, Arti

2008-01-01

In this paper, we examine the relationship between oil price and the Fiji-US exchange rate using daily data for the period 2000-2006. We use the generalised autoregressive conditional heteroskedasticity (GARCH) and exponential GARCH (EGARCH) models to estimate the impact of oil price on the nominal exchange rate. We find that a rise in oil prices leads to an appreciation of the Fijian dollar vis-a-vis the US dollar. (author)

Structural correlation method for model reduction and practical estimation of patient specific parameters illustrated on heart rate regulation

DEFF Research Database (Denmark)

Ottesen, Johnny T.; Mehlsen, Jesper; Olufsen, Mette

2014-01-01

We consider the inverse and patient specific problem of short term (seconds to minutes) heart rate regulation specified by a system of nonlinear ODEs and corresponding data. We show how a recent method termed the structural correlation method (SCM) can be used for model reduction and for obtaining...... a set of practically identifiable parameters. The structural correlation method includes two steps: sensitivity and correlation analysis. When combined with an optimization step, it is possible to estimate model parameters, enabling the model to fit dynamics observed in data. This method is illustrated...... in detail on a model predicting baroreflex regulation of heart rate and applied to analysis of data from a rat and healthy humans. Numerous mathematical models have been proposed for prediction of baroreflex regulation of heart rate, yet most of these have been designed to provide qualitative predictions...

Interest Rates with Long Memory: A Generalized Affine Term-Structure Model

DEFF Research Database (Denmark)

Osterrieder, Daniela

.S. government bonds, we model the time series of the state vector by means of a co-fractional vector autoregressive model. The implication is that yields of all maturities exhibit nonstationary, yet mean-reverting, long-memory behavior of the order d ≈ 0.87. The long-run dynamics of the state vector are driven......We propose a model for the term structure of interest rates that is a generalization of the discrete-time, Gaussian, affine yield-curve model. Compared to standard affine models, our model allows for general linear dynamics in the vector of state variables. In an application to real yields of U...... forecasts that outperform several benchmark models, especially at long forecasting horizons....

The type I error rate for in vivo Comet assay data when the hierarchical structure is disregarded

DEFF Research Database (Denmark)

Hansen, Merete Kjær; Kulahci, Murat

the type I error rate is greater than the nominal _ at 0.05. Closed-form expressions based on scaled F-distributions using the Welch-Satterthwaite approximation are provided to show how the type I error rate is aUected. With this study we hope to motivate researchers to be more precise regarding......, and this imposes considerable impact on the type I error rate. This study aims to demonstrate the implications that result from disregarding the hierarchical structure. DiUerent combinations of the factor levels as they appear in a literature study give type I error rates up to 0.51 and for all combinations...

Influence of air flow rate on structural and electrical properties of undoped indium oxide thin films

International Nuclear Information System (INIS)

Mirzapour, S.; Rozati, S.M.; Takwale, M.G.; Marathe, B.R.; Bhide, V.G.

1993-01-01

Using the spray pyrolysis technique thin films of indium oxide were prepared on Corning glass (7059) at a substrate temperature of 425 C at different flow rates. The electrical and structural properties of these films were studied. The Hall measurements at room temperature showed that the films prepared in an air flow rate of 7 litre min -1 have the highest mobility of 47 cm 2 V -1 s -1 and a minimum resistivity of 1.125 x 10 -3 Ω cm. The X-ray diffraction patterns showed that the films have a preferred orientation of [400] which peaks at the air flow rate of 7 litre min -1 . (orig.)

EFFECTS OF PORE STRUCTURE CHANGE AND MULTI-SCALE HETEROGENEITY ON CONTAMINANT TRANSPORT AND REACTION RATE UPSCALING

Energy Technology Data Exchange (ETDEWEB)

Peters, Catherine A [Princeton University

2013-05-15

This project addressed the scaling of geochemical reactions to core and field scales, and the interrelationship between reaction rates and flow in porous media. We targeted reactive transport problems relevant to the Hanford site specifically the reaction of highly caustic, radioactive waste solutions with subsurface sediments, and the immobilization of 90Sr and 129I through mineral incorporation and passive flow blockage, respectively. We addressed the correlation of results for pore-scale fluid-soil interaction with field-scale fluid flow, with the specific goals of (i) predicting attenuation of radionuclide concentration; (ii) estimating changes in flow rates through changes of soil permeabilities; and (iii) estimating effective reaction rates. In supplemental work, we also simulated reactive transport systems relevant to geologic carbon sequestration. As a whole, this research generated a better understanding of reactive transport in porous media, and resulted in more accurate methods for reaction rate upscaling and improved prediction of permeability evolution. These scientific advancements will ultimately lead to better tools for management and remediation of DOE legacy waste problems.

Structured health care for subjects with diabetic foot ulcers results in a reduction of major amputation rates

Science.gov (United States)

2013-01-01

Objective We tested the effects of structured health care for the diabetic foot in one region in Germany aiming to reduce the number of major amputations. Research design and methods In a prospective study we investigated patients with diabetic foot in a structured system of outpatient, in-patient and rehabilitative treatment. Subjects were recruited between January 1st, 2000 and December 31, 2007. All participants underwent a two-year follow-up. The modified University of Texas Wound Classification System (UT) was the basis for documentation and data analysis. We evaluated numbers of major amputations, rates of ulcer healing and mortality. In order to compare the effect of the structured health care program with usual care in patients with diabetic foot we evaluated the same parameters at another regional hospital without interdisciplinary care of diabetic foot (controls). Results 684 patients with diabetic foot and 508 controls were investigated. At discharge from hospital 28.3% (structured health care program, SHC) vs. 23.0% (controls) of all ulcers had healed completely. 51.5% (SHC) vs. 49.8% (controls) were in UT grade 1. Major amputations were performed in 32 subjects of the structured health care program group (4.7%) vs. 110 (21.7%) in controls (p<0.0001). Mortality during hospitalization was 2.5% (SHC) vs. 9.4% in controls (p<0.001). Conclusions With the structured health care program we achieved a significant reduction of major amputation rates by more than 75% as compared to standard care. PMID:23497152

The rise of cancer in urban India: Cultural understandings, structural inequalities and the emergence of the clinic.

Science.gov (United States)

Broom, Alex; Doron, Assa

2012-05-01

Cancer services in India have evolved and expanded significantly in recent years, with a surge in the availability of biomedical oncological treatment facilities for certain cohorts of the Indian population in urban areas. Despite significant and sustained economic development in many areas of India, major issues persist in the delivery of cancer care, even in the context of relatively prosperous urban populations. This article explores the dilemmas evident in Indian cancer care as perceived by a group of Indian oncology clinicians. Specifically, the interviews focused on their perspectives on the key challenges facing cancer patients, particularly in relation to help-seeking and access to care. The main concerns that emerged in the interviews were: (a) practical constraint (i.e. access and treatment); (b) cultural values (i.e. communication, stigma and the clinic); and (c) structural conditions (i.e. inequalities related to place, gender and class). We unpack these as important elements of cancer care in contemporary India, and present Farmer's notion of structural violence, among other concepts, as potentially useful for understanding some facets of this social problem. We conclude that without a greater understanding of social and cultural issues shaping cancer care in India, little progress will be made in coping with a disease that is set to become a major burden within an increasingly prosperous and ageing population.

Relationships between structure and function: System structure matters whether you are in a wetland or a college classroom

Science.gov (United States)

Andrews, Sarah Elizabeth

Part I of this dissertation describes two research projects I undertook to understand how structure influences function in freshwater wetlands. In the first study I tested the hypothesis that wetland structure (created versus natural) would influence function (methane cycling). Created wetlands had reduced rates of potential methane production and potential methane oxidation compared to natural wetlands; this was most likely explained by differences in edaphic factors that characterized each wetland, particularly soil moisture and soil organic matter. In the second study (Andrews et al. 2013), I tested the hypothesis that plant community structure (functional group composition, richness, presence/absence) would influence function (methane and iron cycling) in wetland mesocosms. Plant functional group richness was less important than the type of vegetation present: the presence of perennial vegetation (reeds or tussocks) led to increased rates of potential iron reduction compared to when only annual vegetation was present. Part II of this dissertation describes research I undertook to understand how structure influences function in an undergraduate soil science course. In the first study I tested the hypothesis that course structure (traditional versus studio) would influence function (student performance) in the course. Students in the studio course outperformed students in the traditional course; there was also a decrease in the fail rate. In the second study I looked at students' perspectives on their learning and experiences (function) in the studio course and asked whether students' epistemological development influenced this function. Interviews with students revealed that active learning, the integrated nature of the course, community, and variety of learning and assessment methods helped student learning. Students' epistemological development (interpreted from the Measure of Epistemological Reflection) permeated much of what they spoke about during the

Illuminating the dark side of DOM: A bottom up approach to understanding the structure and composition of DOM.

Science.gov (United States)

Zito, P.; Tarr, M. A.; Spencer, R. G.; Podgorski, D. C.

2017-12-01

Dissolved organic matter (DOM) is one of the most complex natural mixtures on Earth. It is generally comprised of hydrocarbons incorporating a diverse subset of oxygen-containing functional groups along with a small amount of nitrogen, sulfur and phosphorous heteroatoms all of which make it very difficult to chromatographically separate. The only way to directly characterize and quantify these structural and compositional changes is by separating the DOM continuum into defined bins of structure and chemistry. In this study, we take an alternate bottom-up approach that utilizes petroleum to work toward identifying the molecular structures of DOM. Although petroleum is the most structurally diverse mixture in nature, it is almost exclusively comprised of hydrocarbons with only trace quantities of heteroatoms, including oxygen. Here, crude oil was chromatographically separated into bins based on the number of aromatic rings to be used as a starting carbon source. Photochemically produced DOM from these aromatic ring bins provides unique opportunities to gain insight in the compositional controls associated with transport, processing and fate of DOM in natural systems. Here, we present EEMs data from individual ring fractions that were subjected to 24 hours of sunlight to use as a model to fingerprint specific aromatic regions in the DOM fraction. Results illustrate that the 1-, 2-, 3-, 4- and 5- ring fractions exhibit a wide range of structurally dependent excitation and emission spectra. A well-known red-shift in the emission and excitation occurs as the number of rings increase. In order to understand changes in the elemental composition of the data, ultra high-resolution mass spectrometry was used to obtain molecular level information. Together, these data will provide a tool to help understand the relationship of the composition and structure of DOM released into the environment in terms of aromaticity. It is well known that aromaticity is an important indicator

Free Energy Rate Density and Self-organization in Complex Systems

OpenAIRE

Georgiev, Georgi Yordanov; Gombos, Erin; Bates, Timothy; Henry, Kaitlin; Casey, Alexander; Daly, Michael

2015-01-01

One of the most important tasks in science is to understand the self-organization's arrow of time. To attempt this we utilize the connection between self-organization and non-equilibrium thermodynamics. Eric Chaisson calculated an exponential increase of Free Energy Rate Density (FERD) in Cosmic Evolution, from the Big Bang until now, paralleling the increase of system's structure. We term these studies "Devology". We connect FERD to the principle of least action for complex systems, driving ...

Understanding inter-industry wage structures in the euro area

OpenAIRE

Genre, Véronique; Momferatou, Daphne; Kohn, Karsten

2009-01-01

This paper focuses on the euro area wage structure and its potential determinants from a sectoral viewpoint. Merging information from the OECD Structural Analysis database with data from the EU Labour Force Survey, we construct a cross-country panel of 22 industries in 8 euro area countries for 1991-2002. Data inspection confirms the existence of a fairly stable inter- industry wage structure that is similar across countries. We then apply panel data techniques to identify factors explaining ...

ON THE STAR FORMATION RATES IN MOLECULAR CLOUDS

International Nuclear Information System (INIS)

Lada, Charles J.; Lombardi, Marco; Alves, Joao F.

2010-01-01

In this paper, we investigate the level of star formation activity within nearby molecular clouds. We employ a uniform set of infrared extinction maps to provide accurate assessments of cloud mass and structure and compare these with inventories of young stellar objects within the clouds. We present evidence indicating that both the yield and rate of star formation can vary considerably in local clouds, independent of their mass and size. We find that the surface density structure of such clouds appears to be important in controlling both these factors. In particular, we find that the star formation rate (SFR) in molecular clouds is linearly proportional to the cloud mass (M 0.8 ) above an extinction threshold of A K ∼ 0.8 mag, corresponding to a gas surface density threshold of Σ gas ∼ 116 M sun pc 2 . We argue that this surface density threshold corresponds to a gas volume density threshold which we estimate to be n(H 2 ) ∼ 10 4 cm -3 . Specifically, we find SFR (M sun yr -1 ) = 4.6 ± 2.6 x 10 -8 M 0.8 (M sun ) for the clouds in our sample. This relation between the rate of star formation and the amount of dense gas in molecular clouds appears to be in excellent agreement with previous observations of both galactic and extragalactic star-forming activity. It is likely the underlying physical relationship or empirical law that most directly connects star formation activity with interstellar gas over many spatial scales within and between individual galaxies. These results suggest that the key to obtaining a predictive understanding of the SFRs in molecular clouds and galaxies is to understand those physical factors which give rise to the dense components of these clouds.

Combined techniques for characterising pasta structure reveals how the gluten network slows enzymic digestion rate.

Science.gov (United States)

Zou, Wei; Sissons, Mike; Gidley, Michael J; Gilbert, Robert G; Warren, Frederick J

2015-12-01

The aim of the present study is to characterise the influence of gluten structure on the kinetics of starch hydrolysis in pasta. Spaghetti and powdered pasta were prepared from three different cultivars of durum semolina, and starch was also purified from each cultivar. Digestion kinetic parameters were obtained through logarithm-of-slope analysis, allowing identification of sequential digestion steps. Purified starch and semolina were digested following a single first-order rate constant, while pasta and powdered pasta followed two sequential first-order rate constants. Rate coefficients were altered by pepsin hydrolysis. Confocal microscopy revealed that, following cooking, starch granules were completely swollen for starch, semolina and pasta powder samples. In pasta, they were completely swollen in the external regions, partially swollen in the intermediate region and almost intact in the pasta strand centre. Gluten entrapment accounts for sequential kinetic steps in starch digestion of pasta; the compact microstructure of pasta also reduces digestion rates. Copyright © 2015 Elsevier Ltd. All rights reserved.

TecDEM: A MATLAB Based Toolbox for understanding Tectonics from Digital Elevation Models

Science.gov (United States)

Shahzad, F.; Mahmood, S. A.; Gloaguen, R.

2009-04-01

TecDEM is a MATLAB based tool box for understanding the tectonics from digital elevation models (DEMs) of any area. These DEMs can be derived from data of any spatial resolution (Low, medium and High). In the first step we extract drainage network from the DEMs using flow grid approach. Drainage network is a group of streams having elevation and catchment area information as a function of spatial locations. We implement an array of stream structure to study this drainage network. Knickpoints can be identified on each stream of the drainage network by a graphical user interface and are helpful for understanding stream morphology. Stream profile analysis in steady state condition is applied on all streams to calculate geomorphic parameters and regional uplift rates. Hack index is calculated for all the profiles at a certain interval and over the change of knickpoints. Reports menu of this tool box generates detailed statistics report, complete tabulated report, graphical output of each analyzed stream profile and Hack index profile. All the calculated values are part of stream structure and is saved as .mat file for later use with this tool box. The spatial distribution of geomorphic parameters, uplift rates and knickpoints are exported as a shape files for visualization in professional GIS software. We test this tool box on DEMs from different tectonic settings worldwide and received verifiable results with other studies.

Structural Covariance of the Prefrontal-Amygdala Pathways Associated with Heart Rate Variability.

Science.gov (United States)

Wei, Luqing; Chen, Hong; Wu, Guo-Rong

2018-01-01

The neurovisceral integration model has shown a key role of the amygdala in neural circuits underlying heart rate variability (HRV) modulation, and suggested that reciprocal connections from amygdala to brain regions centered on the central autonomic network (CAN) are associated with HRV. To provide neuroanatomical evidence for these theoretical perspectives, the current study used covariance analysis of MRI-based gray matter volume (GMV) to map structural covariance network of the amygdala, and then determined whether the interregional structural correlations related to individual differences in HRV. The results showed that covariance patterns of the amygdala encompassed large portions of cortical (e.g., prefrontal, cingulate, and insula) and subcortical (e.g., striatum, hippocampus, and midbrain) regions, lending evidence from structural covariance analysis to the notion that the amygdala was a pivotal node in neural pathways for HRV modulation. Importantly, participants with higher resting HRV showed increased covariance of amygdala to dorsal medial prefrontal cortex and anterior cingulate cortex (dmPFC/dACC) extending into adjacent medial motor regions [i.e., pre-supplementary motor area (pre-SMA)/SMA], demonstrating structural covariance of the prefrontal-amygdala pathways implicated in HRV, and also implying that resting HRV may reflect the function of neural circuits underlying cognitive regulation of emotion as well as facilitation of adaptive behaviors to emotion. Our results, thus, provide anatomical substrates for the neurovisceral integration model that resting HRV may index an integrative neural network which effectively organizes emotional, cognitive, physiological and behavioral responses in the service of goal-directed behavior and adaptability.

Structural Equation Modeling (SEM) for Satisfaction and Dissatisfaction Ratings; Multiple Group Invariance Analysis across Scales with Different Response Format

Science.gov (United States)

Mazaheri, Mehrdad; Theuns, Peter

2009-01-01

The current study evaluates three hypothesized models on subjective well-being, comprising life domain ratings (LDR), overall satisfaction with life (OSWL), and overall dissatisfaction with life (ODWL), using structural equation modeling (SEM). A sample of 1,310 volunteering students, randomly assigned to six conditions, rated their overall life…

Selectivity control of photosensitive structures based on gallium arsenide phosphide solid solutions by changing the rate of surface recombination

International Nuclear Information System (INIS)

Tarasov, S A; Andreev, M Y; Lamkin, I A; Solomonov, A V

2016-01-01

In this paper, we demonstrate the effect of surface recombination on spectral sensitivity of structures based on gallium arsenide phosphide solid solutions. Simulation of the effect for structures based on a p-n junction and a Schottky barrier was carried out. Photodetectors with different rates of surface recombination were fabricated by using different methods of preliminary treatment of the semiconductor surface. We experimentally demonstrated the possibility to control photodetector selectivity by altering the rate of surface recombination. The full width at half maximum was reduced by almost 4 times, while a relatively small decrease in sensitivity at the maximum was observed. (paper)

Do brain image databanks support understanding of normal ageing brain structure? A systematic review

International Nuclear Information System (INIS)

Dickie, David Alexander; Job, Dominic E.; Wardlaw, Joanna M.; Poole, Ian; Ahearn, Trevor S.; Staff, Roger T.; Murray, Alison D.

2012-01-01

To document accessible magnetic resonance (MR) brain images, metadata and statistical results from normal older subjects that may be used to improve diagnoses of dementia. We systematically reviewed published brain image databanks (print literature and Internet) concerned with normal ageing brain structure. From nine eligible databanks, there appeared to be 944 normal subjects aged ≥60 years. However, many subjects were in more than one databank and not all were fully representative of normal ageing clinical characteristics. Therefore, there were approximately 343 subjects aged ≥60 years with metadata representative of normal ageing, but only 98 subjects were openly accessible. No databank had the range of MR image sequences, e.g. T2*, fluid-attenuated inversion recovery (FLAIR), required to effectively characterise the features of brain ageing. No databank supported random subject retrieval; therefore, manual selection bias and errors may occur in studies that use these subjects as controls. Finally, no databank stored results from statistical analyses of its brain image and metadata that may be validated with analyses of further data. Brain image databanks require open access, more subjects, metadata, MR image sequences, searchability and statistical results to improve understanding of normal ageing brain structure and diagnoses of dementia. (orig.)

Gene-Culture Coevolution in a Social Cetacean: Integrating Acoustic and Genetic Data to Understand Population Structure in the Short-Finned Pilot Whale (Globicephala macrorhynchus)

Science.gov (United States)

Van Cise, Amy

The evolutionary ecology of a species is driven by a combination of random events, ecological and environmental mechanisms, and social behavior. Gene-culture coevolutionary theory attempts to understand the evolutionary trajectory of a species by examining the interactions between these potential drivers. Further, our choice of data type will affect the patterns we observe, therefore by integrating several types of data we achieve a holistic understanding of the various aspects of evolutionary ecology within a species. In order to understand population structure in short-finned pilot whales, I use a combination of genetic and acoustic data to examine structure on evolutionary (genetic) and cultural (acoustic) timescales. I first examine structure among geographic populations in the Pacific Ocean. Using genetic sequences from the mitochondrial control region, I show that two genetically and morphologically distinct types of short-finned pilot whale, described off the coast of Japan, have non-overlapping distributions throughout their range in the Pacific Ocean. Analysis of the acoustic features of their social calls indicates that they are acoustically differentiated, possibly due to limited communication between the two types. This evidence supports the hypothesis that the two types may be separate species or subspecies. Next, I examine structure among island communities and social groups within the Hawaiian Island population of short-finned pilot whales. Using a combination of mitochondrial and nuclear DNA, I showed that the hierarchical social structure in Hawaiian pilot whales is driven by genetic relatedness; individuals remain in groups with their immediate family members, and preferentially associate with relatives. Similarly, social structure affects genetic differentiation, likely by restricting access to mates. Acoustic differentiation among social groups indicates that social structure may also restrict the flow of cultural information, such as vocal

The influence of interest rates on the exchange rate and exchange rate volatility

OpenAIRE

Florin MAVRIS; Dumitru-Cristian OANEA

2014-01-01

The dynamic of interest rates has been the subject of attention by both traders and researchers. We see in what manner different factors that depend on the actions of central banks that influence them by using a GARCH type model and we compare its performance with other models to see what approach explains and predicts the movement of the exchange rate. To better understand the type of model that is applicable the data is tested for heteroskedasticity, and only after that the model is impleme...

Scrambling the Nest Egg: How Well Do Teachers Understand Their Pensions, and What Do They Think about Alternative Pension Structures?

Science.gov (United States)

DeArmond, Michael; Goldhaber, Dan

2010-01-01

In this article we focus on two questions: How well do teachers understand their current pension plans, and what do they think about alternative plan structures? The data come from administrative records and a 2006 survey of teachers in Washington State. The results suggest that Washington's teachers are fairly knowledgeable about their pensions,…

The impact of retail rate structures on the economics of commercial photovoltaic systems in California

International Nuclear Information System (INIS)

Mills, Andrew; Wiser, Ryan; Barbose, Galen; Golove, William

2008-01-01

This article examines the impact of retail electricity rate design on the economic value of grid-connected photovoltaic (PV) systems, focusing on commercial customers in California. Using 15-min interval building load and PV production data from a sample of 24 actual commercial PV installations, we compare the value of the bill savings across 20 commercial-customer retail electricity rates currently offered in the state. Across all combinations of customers and rates, we find that the annual bill savings from PV, per kWh generated, ranges from 0.05 to 0.24/kWh. This sizable range in rate-reduction value reflects differences in rate structures, revenue requirements, the size of the PV system relative to building load, and customer load shape. The most significant rate design issue for the value of commercial PV is found to be the percentage of total utility bills recovered through demand charges, though a variety of other factors are also found to be of importance. The value of net metering is found to be substantial, but only when energy from commercial PV systems represents a sizable portion of annual customer load. Though the analysis presented here is specific to California, our general results demonstrate the fundamental importance of retail rate design for the customer-economics of grid-connected, customer-sited PV. (author)

Analysis of multiplicities in e+e- interactions using 2-jet rates from different jet algorithms

International Nuclear Information System (INIS)

Dahiya, S.; Kaur, M.; Dhamija, S.

2002-01-01

The shoulder structure of charged particle multiplicity distribution measured in full phase space in e + e - interactions at various c.m. energies from 91 to 189 GeV has been analysed in terms of weighted superposition of two negative binomial distributions associated with 2-jet and multi-jet production. The 2-jet rates have been obtained from various jet algorithms. This phenomenological parametrization reproduces the shoulder structure behaviour quantitatively and improves the agreement with the experimental distributions than the conventional negative binomial distribution. The analysis at the higher energies where the shoulder structure appears more prominently, is important for the understanding of underlying structure. (author)

Impact of a structured surgical curriculum on ophthalmic resident cataract surgery complication rates.

Science.gov (United States)

Rogers, Gina M; Oetting, Thomas A; Lee, Andrew G; Grignon, Connie; Greenlee, Emily; Johnson, A Tim; Beaver, Hilary A; Carter, Keith

2009-11-01

To determine whether institution of a structured surgical curriculum for ophthalmology residents decreased the rate of sentinel surgical complications. Veterans Affairs Medical Center, Des Moines, Iowa, USA. A retrospective review was performed of third-year ophthalmic resident quality-assurance surgical outcomes data at a single residency-training site from 1998 to 2008. The primary outcome measure was defined as a sentinel event; that is, a posterior capsule tear (with or without vitreous loss) or vitreous loss (from any cause) occurring during a resident-performed case. The study population was divided into 2 groups. Group 1 comprised surgical cases of residents trained before the surgical curriculum change (academic years 1998 to 2003) and Group 2, surgical cases of residents trained with the enhanced curriculum (academic years 2004 to 2008). Data from 1 year (academic year 2003 to 2004) were excluded because the transition to the enhanced curriculum occurred during that period. The data were analyzed and adjusted for surgical experience. In Group 1 (before institution of surgical curriculum), there were 823 cases with 59 sentinel complications. In Group 2 (after institution of surgical curriculum), there were 1009 cases with 38 sentinel complications. There was a statistically significant reduction in the sentinel complication rate, from 7.17% before the curriculum changes to 3.77% with the enhanced curriculum (P = .001, unpaired 2-tailed t test). Implementation of a structured surgical curriculum resulted in a statistically significant reduction in sentinel event complications, even after adjusting for surgical experience.

Understanding the structure of data when planning for analysis ...

African Journals Online (AJOL)

Human beings and other living creatures tend to exist within organisational structures, such as families, schools, and business organisations. In an educational system, for example, students exist within a hierarchical social structure that can include classroom, grade level, school, school district and country. Data obtained ...

Deep-UV Raman spectroscopic analysis of structure and dissolution rates of silica-rich sodium borosilicate glasses

Energy Technology Data Exchange (ETDEWEB)

Windisch, Charles F.; Pierce, Eric M.; Burton, Sarah D.; Bovaird, Chase C.

2011-03-24

As part of ongoing studies to evaluate the relationships between structural variations in silicate glasses and rates of glass dissolution in aqueous media, molecular structures present in sodium borosilicate glasses of composition Na2O.xB2O3.(3-x)SiO2, with x 1 (Na2O/B2O3 ratio 1), were analyzed using deep-UV Raman spectroscopy. The results were quantified in terms of the fraction of SiO4 tetrahedra with one non-bridging oxygen (Q3) and then correlated with Na2O and B2O3 content. Increasing Na2O was found to raise the fraction of Q3 units in the glasses systematically, in agreement with studies on related glasses, and, as long as the value of x was not too high, contribute to higher rates of dissolution in single pass flow-through testing. The finding was obtained across more than one series of silica-rich glasses prepared for independent dissolution studies. In contrast, dissolution rates were less strongly determined by the Q3 fraction when the value of x was near unity and appeared to grow larger upon further reduction of the Q3 fraction. The results were interpreted to indicate the increasingly important role of network hydrolysis in the glass dissolution mechanism as the BO4 tetrahedron replaces the Q3 unit as the charge-compensating structure for Na+ ions. Finally, the use of deep-UV Raman spectroscopy was found to be advantageous in studying finely powdered glasses in cases where visible Raman spectroscopy suffered from weak Raman scattering and fluorescence interference.

Empirical Studies of Exchange Rates: Price Behavior, Rate Determinationand Market Efficiency

OpenAIRE

Richard M. Levich

1983-01-01

Theoretical and empirical research completed over the last decade has dramatically increased our understanding of exchange rate behavior. The major insight to come from this decade of research is that foreign exchange is a financial asset. In an asset pricing framework, current exchange rates reflect the expected values of future exogenous variables. The purpose of this paper is to survay the empirical evidence on exchange rate behavior, market efficiency and related topics. Section 2 present...

A Matérn model of the spatial covariance structure of point rain rates

KAUST Repository

Sun, Ying; Bowman, Kenneth P.; Genton, Marc G.; Tokay, Ali

2014-01-01

It is challenging to model a precipitation field due to its intermittent and highly scale-dependent nature. Many models of point rain rates or areal rainfall observations have been proposed and studied for different time scales. Among them, the spectral model based on a stochastic dynamical equation for the instantaneous point rain rate field is attractive, since it naturally leads to a consistent space–time model. In this paper, we note that the spatial covariance structure of the spectral model is equivalent to the well-known Matérn covariance model. Using high-quality rain gauge data, we estimate the parameters of the Matérn model for different time scales and demonstrate that the Matérn model is superior to an exponential model, particularly at short time scales.

A Matérn model of the spatial covariance structure of point rain rates

KAUST Repository

Sun, Ying

2014-07-15

It is challenging to model a precipitation field due to its intermittent and highly scale-dependent nature. Many models of point rain rates or areal rainfall observations have been proposed and studied for different time scales. Among them, the spectral model based on a stochastic dynamical equation for the instantaneous point rain rate field is attractive, since it naturally leads to a consistent space–time model. In this paper, we note that the spatial covariance structure of the spectral model is equivalent to the well-known Matérn covariance model. Using high-quality rain gauge data, we estimate the parameters of the Matérn model for different time scales and demonstrate that the Matérn model is superior to an exponential model, particularly at short time scales.

Age, growth and population structure of invasive lionfish (Pterois volitans/miles in northeast Florida using a length-based, age-structured population model

Directory of Open Access Journals (Sweden)

Eric G. Johnson

2016-12-01

Full Text Available The effective management of invasive species requires detailed understanding of the invader’s life history. This information is essential for modeling population growth and predicting rates of expansion, quantifying ecological impacts and assessing the efficacy of removal and control strategies. Indo-Pacific lionfish (Pterois volitans/miles have rapidly invaded the western Atlantic, Gulf of Mexico and Caribbean Sea with documented negative impacts on native ecosystems. To better understand the life history of this species, we developed and validated a length-based, age-structured model to investigate age, growth and population structure in northeast Florida. The main findings of this study were: (1 lionfish exhibited rapid growth with seasonal variation in growth rates; (2 distinct cohorts were clearly identifiable in the length-frequency data, suggesting that lionfish are recruiting during a relatively short period in summer; and (3 the majority of lionfish were less than two years old with no lionfish older than three years of age, which may be the result of culling efforts as well as ontogenetic habitat shifts to deeper water.

Age, growth and population structure of invasive lionfish (Pterois volitans/miles) in northeast Florida using a length-based, age-structured population model.

Science.gov (United States)

Johnson, Eric G; Swenarton, Mary Katherine

2016-01-01

The effective management of invasive species requires detailed understanding of the invader's life history. This information is essential for modeling population growth and predicting rates of expansion, quantifying ecological impacts and assessing the efficacy of removal and control strategies. Indo-Pacific lionfish ( Pterois volitans/miles ) have rapidly invaded the western Atlantic, Gulf of Mexico and Caribbean Sea with documented negative impacts on native ecosystems. To better understand the life history of this species, we developed and validated a length-based, age-structured model to investigate age, growth and population structure in northeast Florida. The main findings of this study were: (1) lionfish exhibited rapid growth with seasonal variation in growth rates; (2) distinct cohorts were clearly identifiable in the length-frequency data, suggesting that lionfish are recruiting during a relatively short period in summer; and (3) the majority of lionfish were less than two years old with no lionfish older than three years of age, which may be the result of culling efforts as well as ontogenetic habitat shifts to deeper water.

Dynamics and structure of stretched flames

Energy Technology Data Exchange (ETDEWEB)

Law, C.K. [Princeton Univ., NJ (United States)

1993-12-01

This program aims to gain fundamental understanding on the structure, geometry, and dynamics of laminar premixed flames, and relate these understanding to the practical issues of flame extinction and stabilization. The underlying fundamental interest here is the recent recognition that the response of premixed flames can be profoundly affected by flame stretch, as manifested by flow nonuniformity, flame curvature, and flame/flow unsteadiness. As such, many of the existing understanding on the behavior of premixed flames need to be qualitatively revised. The research program consists of three major thrusts: (1) detailed experimental and computational mapping of the structure of aerodynamically-strained planar flames, with emphasis on the effects of heat loss, nonequidiffusion, and finite residence time on the flame thickness, extent of incomplete reaction, and the state of extinction. (2) Analytical study of the geometry and dynamics of stretch-affected wrinkled flame sheets in simple configurations, as exemplified by the Bunsen flame and the spatially-periodic flame, with emphasis on the effects of nonlinear stretch, the phenomena of flame cusping, smoothing, and tip opening, and their implications on the structure and burning rate of turbulent flames. (3) Stabilization and blowoff of two-dimensional inverted premixed and stabilization and determining the criteria governing flame blowoff. The research is synergistically conducted through the use of laser-based diagnostics, computational simulation of the flame structure with detailed chemistry and transport, and mathematical analysis of the flame dynamics.

Infant mortality rates and structure in a town near a nuclear power enterprise

International Nuclear Information System (INIS)

Tret'yakov, F.D.; Voronina, Z.I.; Voronin, P.F.; Demin, S.N.

1991-01-01

The paper is devoted to analysis of the rates and structure of mortality of infants aged under 1 in a town, situated near a nuclear power enterprise (NPE). Altogether 38124 infants born in 1950-1978, were investigated. The dead infants (1160) were divided into 3 groups with relation to their parents' place of work: 1 - infants whose parents worked in the NPE; 2 - infants whose parents worked in town factories and offices; 3 - all infants in the town. The total doses of γ-irradiation for mothers were 10-400 cSv, those for fathers - 30-520 cSv, intrauterine irradiation of a fetus was 0.5-0.55 cSv. The individual effective equivalent dose of irradiation of the residents of the town was 17.3 cSv over 40 years. Occupational γ-irradiation of the parents at doses exceeding the maximum permissible ones in the first 10 years of work at the NPE made no effect on the mortality rates in infants of the first generation

Understanding unemployment

OpenAIRE

Guillaume Rocheteau

2006-01-01

Modern economists have built models of the labor market, which isolate the market’s key drivers and describe the way these interact to produce particular levels of unemployment. One of the most popular models used by macroeconomists today is the search-matching model of equilibrium unemployment. We explain this model, and show how it can be applied to understand the way various policies, such as unemployment benefits, taxes, or technological changes, can affect the unemployment rate.

Thermodynamic and structural models compared with the initial dissolution rates of open-quotes SONclose quotes glass samples

International Nuclear Information System (INIS)

Tovena, I.; Advocat, T.; Ghaleb, D.; Vernaz, E.; Larche, F.

1994-01-01

The experimentally determined initial dissolution rate R 0 of nuclear glass was correlated with thermodynamic parameters and structural parameters. The initial corrosion rates of six open-quotes R7T7close quotes glass samples measured at 100 degrees C in a Soxhlet device were correlated with the glass free hydration energy and the glass formation enthalpy. These correlations were then tested with a group of 26 SON glasses selected for their wide diversity of compositions. The thermodynamic models provided a satisfactory approximation of the initial dissolution rate determined under Soxhlet conditions for SON glass samples that include up to 15 wt% of boron and some alumina. Conversely, these models are inaccurate if the boron concentration exceeds 15 wt% and the glass contains no alumina. Possible correlations between R 0 and structural parameters, such as the boron coordination number and the number of nonbridging oxygen atoms, were also investigated. The authors show that R 0 varies inversely with the number of 4-coordinate boron atoms; conversely, the results do not substantiate published reports of a correlation between R 0 and the number of nonbridging oxygen atoms

Atomic-level structure and structure-property relationship in metallic glass

Science.gov (United States)

Cheng, Yongqiang

One of the key tasks in material science is to understand the structure and structure-property relationship. The recently emerging bulk metallic glasses (BMGs) have demonstrated unique properties, especially intriguing mechanical properties such as their high strength and high propensity to localize deformation in shear bands. However, a comprehensive understanding of the structure of BMGs has been hindered by the complexity of these amorphous materials. Even more challenging is the structure-property correlation, which has been well established in crystals but has been seriously lacking for BMGs. This thesis presents a systematic study of the atomic-level structures of two representative BMGs, Cu-Zr and Cu-Zr-Al. The interpenetrating Cu-centered icosahedral clusters have been identified to be the primary structural feature. The fraction of icosahedra increases with increasing Cu or Al contents, and with decreasing cooling rate. The effect of Al in improving the icosahedral order is two-fold: the geometric effect due to the atomic-size mismatch and the chemical effect originated from the Cu-Al bond shortening. The resolved structure is used to study the structure-property relationship. The full icosahedra are found to be responsible for the dynamical slowdown of the supercooled liquid, which underlies the non-Arrhenius behavior, and explains the composition dependence of glass transition temperature, glass forming ability, and the room temperature strength. By simulated deformation, the initiation of plasticity and tendency for strain localization are also investigated. The full icosahedra are found to be the most rigid and resistant cluster with solid-like character, while the unstable clusters with liquid-like character serve as the fertile sites for initiating shear transformations. In addition, the elastic moduli are calculated and analyzed, and the origins of the different configurational dependence of shear modulus (G) and bulk modulus ( B) are explained. The

Testing hypotheses in an I(2) model with applications to the persistent long swings in the Dmk/$ rate

DEFF Research Database (Denmark)

Johansen, Søren; Juselius, Katarina; Frydman, Roman

long-term interest rates and two short-term interest rates over the 1975-1999 period. One important aim of the paper is to demonstrate that by structuring the data with the help of the I(2) model one can achieve a better understanding of the empirical regularities underlying the persistent swings...... components in the I(2) model is discussed at some length. Model specification and tests are illustrated with an empirical analysis of long and persistent swings in the foreign exchange market between Germany and USA. The data analyzed consist of nominal exchange rates, relative prices, US inflation rate, two...... in nominal exchange rates, typical in periods of floating exchange rates....

Understanding the Structure of High-K Gate Oxides - Oral Presentation

Energy Technology Data Exchange (ETDEWEB)

Miranda, Andre [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2015-08-25

Hafnium Oxide (HfO₂) amorphous thin films are being used as gate oxides in transistors because of their high dielectric constant (κ) over Silicon Dioxide. The present study looks to find the atomic structure of HfO₂ thin films which hasn’t been done with the technique of this study. In this study, two HfO₂ samples were studied. One sample was made with thermal atomic layer deposition (ALD) on top of a Chromium and Gold layer on a silicon wafer. The second sample was made with plasma ALD on top of a Chromium and Gold layer on a Silicon wafer. Both films were deposited at a thickness of 50nm. To obtain atomic structure information, Grazing Incidence X-ray diffraction (GIXRD) was carried out on the HfO₂ samples. Because of this, absorption, footprint, polarization, and dead time corrections were applied to the scattering intensity data collected. The scattering curves displayed a difference in structure between the ALD processes. The plasma ALD sample showed the broad peak characteristic of an amorphous structure whereas the thermal ALD sample showed an amorphous structure with characteristics of crystalline materials. This appears to suggest that the thermal process results in a mostly amorphous material with crystallites within. Further, the scattering intensity data was used to calculate a pair distribution function (PDF) to show more atomic structure. The PDF showed atom distances in the plasma ALD sample had structure up to 10 Å, while the thermal ALD sample showed the same structure below 10 Å. This structure that shows up below 10 Å matches the bond distances of HfO₂ published in literature. The PDF for the thermal ALD sample also showed peaks up to 20 Å, suggesting repeating atomic spacing outside the HfO₂ molecule in the sample. This appears to suggest that there is some crystalline structure within the thermal ALD sample.

CH3-ReO3 on gamma-Al2O3: understanding its structure, initiation,and reactivity in olefin metathesis

Energy Technology Data Exchange (ETDEWEB)

Salameh, Alain; Joubert, Jerome; Baudouin, Anne; Lukens, Wayne; Delbecq, Francoise; Sautet, Philippe; Basset, Jean Marie; Coperet,Christophe

2007-01-20

Me-ReO3 on gamma-alumina: understanding the structure, theinitiation and thereactivity of a highly active olefin metathesiscatalyst Heterolytic splitting of the C-H bond of the methyl group ofCH3ReO3 on AlsO reactive sites of alumina as a way to generate the activesite of CH3ReO3 supported on gamma-Al203.

The Impact of Complexity, Rate of Change and Information Availability on the Production Planning and Control Structure

NARCIS (Netherlands)

M.F. van Assen (Marcel); S.L. van de Velde (Steef)

2003-01-01

textabstractThe organizational theory literature argues that the more uncertain the environment, the more likely the firm’s operational decision structure is decentralized. However, it remains unclear which uncertainty dimensions (i.e. complexity, rate of change and lack of information) impacts the

Understanding Socio Technical Modularity

DEFF Research Database (Denmark)

Thuesen, Christian Langhoff; Kudsk, Anders; Hvam, Lars

2011-01-01

Modularity has gained an increasing popularity as a central concept for exploring product structure, process structure, organization structure and supply chain structure. With the offset in system theory the predominant understanding of modularity however faces difficulties in explaining the social...... dimension of modularity like irrational behaviors, cultural differences, learning processes, social organization and institutional influences on modularity. The paper addresses this gab offering a reinterpretation of the modularity concept from a socio-technical perspective in general and Actor Network...... Theory in particular. By formulating modularity from an ANT perspective covering social, material and process aspects, the modularity of a socio-technical system can be understood as an entanglement of product, process, organizational and institutional modularity. The theoretical framework is illustrated...

Understanding comorbidity among internalizing problems: Integrating latent structural models of psychopathology and risk mechanisms

Science.gov (United States)

Hankin, Benjamin L.; Snyder, Hannah R.; Gulley, Lauren D.; Schweizer, Tina H.; Bijttebier, Patricia; Nelis, Sabine; Toh, Gim; Vasey, Michael W.

2016-01-01

It is well known that comorbidity is the rule, not the exception, for categorically defined psychiatric disorders, and this is also the case for internalizing disorders of depression and anxiety. This theoretical review paper addresses the ubiquity of comorbidity among internalizing disorders. Our central thesis is that progress in understanding this co-occurrence can be made by employing latent dimensional structural models that organize both psychopathology as well as vulnerabilities and risk mechanisms and by connecting the multiple levels of risk and psychopathology outcomes together. Different vulnerabilities and risk mechanisms are hypothesized to predict different levels of the structural model of psychopathology. We review the present state of knowledge based on concurrent and developmental sequential comorbidity patterns among common discrete psychiatric disorders in youth, and then we advocate for the use of more recent bifactor dimensional models of psychopathology (e.g., p factor, Caspi et al., 2014) that can help to explain the co-occurrence among internalizing symptoms. In support of this relatively novel conceptual perspective, we review six exemplar vulnerabilities and risk mechanisms, including executive function, information processing biases, cognitive vulnerabilities, positive and negative affectivity aspects of temperament, and autonomic dysregulation, along with the developmental occurrence of stressors in different domains, to show how these vulnerabilities can predict the general latent psychopathology factor, a unique latent internalizing dimension, as well as specific symptom syndrome manifestations. PMID:27739389

Understanding Racial and Ethnic Disparities in U.S. Infant Mortality Rates

Science.gov (United States)

... different compared with non-Hispanic white women. Table. Gestational age-specific infant mortality rates, by race and Hispanic origin of mother: United States, 2007 Gestational age (weeks) Total Less ...

Evaluation of Dynamic Deformation Behaviors in Metallic Materials under High Strain-Rates Using Taylor Bar Impact Test

Energy Technology Data Exchange (ETDEWEB)

Bae, Kyung Oh; Shin, Hyung Seop [Andong National Univ., Andong (Korea, Republic of)

2016-09-15

To ensure the reliability and safety of various mechanical systems in accordance with their high-speed usage, it is necessary to evaluate the dynamic deformation behavior of structural materials under impact load. However, it is not easy to understand the dynamic deformation behavior of the structural materials using experimental methods in the high strain-rate range exceeding 10{sup 4} s{sup -1}. In this study, the Taylor bar impact test was conducted to investigate the dynamic deformation behavior of metallic materials in the high strain-rate region, using a high-speed photography system. Numerical analysis of the Taylor bar impact test was performed using AUTODYN S/W. The results of the analysis were compared with the experimental results, and the material behavior in the high strain-rate region was discussed.

Effect of temperature, of oxygen content and the downstream effect on corrosion rate of structural materials in liquid sodium

International Nuclear Information System (INIS)

Ilincev, G.

1988-01-01

The effects were experimentally tested of temperature and of oxygen content on the corrosion rate of structural materials in liquid sodium and on reducing the corrosion rate down the sodium stream. The results of the experiments are shown in graphs and tables and are discussed in detail. The duration of all tests was standard 1,000 hours. The test parameters were set such as to determine the effect of temperature on corrosion of a quantity of various materials in sodium with a low oxygen content (1.2 to 2 ppm) at temperatures of 500 to 800 degC and in sodium with a high oxygen content (345 ppm) at temperatures of 500 to 700 degC. More experiments served the determination of the effect of a different oxygen content varying between 1.2 and 2 ppm at a constant temperature of 600 degC. The materials being tested included main structural materials used for fast reactor construction and materials allowing to establish the effect of main alloying elements on their corrosion in liquid sodium of different temperatures and purity grades. The relationships showing the effects of temperature and oxygen content in sodium on the rate of corrosion of various structural materials in hot parts of the installation and on the reduction in the rate of corrosion downstream due to sodium saturation with corrosion products were constructed using the experimental results. (Z.M.). 15 figs., 2 tabs., 7 refs

Effect of chemical structure on the radioactive decay rate of 71Ge

International Nuclear Information System (INIS)

Makariunas, K.; Makariuniene, E.; Dragunas, A.

1979-01-01

The influence of the chemical structure on the electron capture radioactive decay rate of 71 Ge was observed. 71 Ge nuclei in bivalent sulphide GeS decay faster than in quadrivalent sulphide GeS 2 . The relative change Δlambda/lambda of the decay constant lambda is + (11.4 +- 1.7) X 10 -4 . A possibility to use the experimental values of Δlambda/lambda to determine the chemical changes in the electron density at germanium nuclei in germanium chemical compounds is discussed. Quantitative determination of the changes in the electron density is complicated because of insufficient reliability of the published values of exchange and overlap corrections to the electron capture probabilities. (Auth.)

Differences in self-rated health by employment contract and household structure among Japanese employees: a nationwide cross-sectional study.

Science.gov (United States)

Kachi, Yuko; Inoue, Mariko; Nishikitani, Mariko; Yano, Eiji

2014-01-01

The aim of this study was to examine whether the association between employment contract and self-rated health differs by household structure in a representative sample of employees in Japan. The participants were 81,441 male and 64,471 female employees aged 18-59 years who had participated in the 2010 Comprehensive Survey of Living Conditions. We assessed the interactive effect of employment contract (permanent or precarious) and household structure (couple only, couple with children, single parent, single person, or other multi-person) on fair/poor health, adjusting for covariates by using logistic regression. We then calculated the relative poverty rate by employment contract and household structure. The interaction effect was significant for women (p<0.001) but not for men (p=0.413). A higher percentage of female precarious workers who lived in single-parent households (20.2%) reported fair/poor health compared with those in other types of households (10.4-13.2%), although the prevalence of fair/poor health did not differ substantially by household structure among female permanent workers. The relative poverty rates of female precarious workers who lived in single-parent households were higher compared with those of other female workers. Our results suggest that female precarious workers are not a homogeneous group and that those living in single-parent households suffer from poor health due to low income and insufficient coverage by insurance firms and family-based safety nets.

Flow-induced structure in colloidal suspensions

Energy Technology Data Exchange (ETDEWEB)

Vermant, J [Department of Chemical Engineering, K U Leuven, W de Croylaan 46, B-3001 Leuven (Belgium); Solomon, M J [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2136 (United States)

2005-02-02

We review the sequences of structural states that can be induced in colloidal suspensions by the application of flow. Structure formation during flow is strongly affected by the delicate balance among interparticle forces, Brownian motion and hydrodynamic interactions. The resulting non-equilibrium microstructure is in turn a principal determinant of the suspension rheology. Colloidal suspensions with near hard-sphere interactions develop an anisotropic, amorphous structure at low dimensionless shear rates. At high rates, clustering due to strong hydrodynamic forces leads to shear thickening rheology. Application of steady-shear flow to suspensions with repulsive interactions induces a rich sequence of transitions to one-, two-and three-dimensional order. Oscillatory-shear flow generates metastable ordering in suspensions with equilibrium liquid structure. On the other hand, short-range attractive interactions can lead to a fluid-to-gel transition under quiescent suspensions. Application of flow leads to orientation, breakup, densification and spatial reorganization of aggregates. Using a non-Newtonian suspending medium leads to additional possibilities for organization. We examine the extent to which theory and simulation have yielded mechanistic understanding of the microstructural transitions that have been observed. (topical review)

Marine Structures with Extreme Overtopping Rates

DEFF Research Database (Denmark)

Kofoed, Jens Peter; Frigaard, Peter

2000-01-01

In design of sea defence structures like seawalls, breakwaters and dikes, one of the main objectives is to minimize or even eliminate wave overtopping. For this reason numerous investigations have been performed over the past many years to determine the amount of overtopping occurring for typical...

Improving Rice Modeling Success Rate with Ternary Non-structural Fertilizer Response Model.

Science.gov (United States)

Li, Juan; Zhang, Mingqing; Chen, Fang; Yao, Baoquan

2018-06-13

Fertilizer response modelling is an important technical approach to realize metrological fertilization on rice. With the goal of solving the problems of a low success rate of a ternary quadratic polynomial model (TPFM) and to expand the model's applicability, this paper established a ternary non-structural fertilizer response model (TNFM) based on the experimental results from N, P and K fertilized rice fields. Our research results showed that the TNFM significantly improved the modelling success rate by addressing problems arising from setting the bias and multicollinearity in a TPFM. The results from 88 rice field trials in China indicated that the proportion of typical TNFMs that satisfy the general fertilizer response law of plant nutrition was 40.9%, while the analogous proportion of TPFMs was only 26.1%. The recommended fertilization showed a significant positive linear correlation between the two models, and the parameters N 0 , P 0 and K 0 that estimated the value of soil supplying nutrient equivalents can be used as better indicators of yield potential in plots where no N or P or K fertilizer was applied. The theoretical analysis showed that the new model has a higher fitting accuracy and a wider application range.

Survey of strain-rate effects for some common structural materials used in radioactive material packaging and transportation systems

International Nuclear Information System (INIS)

Robinson, R.A.; Zielenbach, W.J.; Lawrence, A.A.

1976-08-01

In safety evaluation of radioactive material packaging and transport systems during accidents mechanical property data for the structural materials under impact conditions are needed in order to assess the damage and consequences of the accident. This document reviews the status of dynamic material property data for the following common structural materials: lead, uranium, stainless steels, steels, aluminum, copper, and brass. The strain rate data reviewed were limited to the range from static to dynamic impact velocities of 50 ft/s or strain rates of 10 2 /second; temperature conditions were limited to the range -40 to 1000 0 F. Purpose of this document is to explain the test methods, present some of the relevant data, and identify some of the needs for additional data. 7 tables, 14 figures, 77 references

Working Paper - WP/12/08- Exchange Rate Pass-through to Import Prices, and Monetary Policy in South Africa

OpenAIRE

Janine Aron; Greg Farrell; John Muellbauer; Peter Sinclair

2012-01-01

Understanding how import prices adjust to exchange rates helps anticipate inflation effects and monetary policy responses. This paper examines exchange rate pass-through to the monthly import price index in South Africa during 1980–2009. Various short-run pass-through estimates are calculated simply without recourse to a full structural model, yet without neglecting the long-run relationships between prices or the effects of previous import price changes, and controlling for domestic and fore...

Structure factors for tunneling ionization rates of molecules: General Hartree-Fock-based integral representation

Science.gov (United States)

Madsen, Lars Bojer; Jensen, Frank; Dnestryan, Andrey I.; Tolstikhin, Oleg I.

2017-07-01

In the leading-order approximation of the weak-field asymptotic theory (WFAT), the dependence of the tunneling ionization rate of a molecule in an electric field on its orientation with respect to the field is determined by the structure factor of the ionizing molecular orbital. The WFAT yields an expression for the structure factor in terms of a local property of the orbital in the asymptotic region. However, in general quantum chemistry approaches molecular orbitals are expanded in a Gaussian basis which does not reproduce their asymptotic behavior correctly. This hinders the application of the WFAT to polyatomic molecules, which are attracting increasing interest in strong-field physics. Recently, an integral-equation approach to the WFAT for tunneling ionization of one electron from an arbitrary potential has been developed. The structure factor is expressed in an integral form as a matrix element involving the ionizing orbital. The integral is not sensitive to the asymptotic behavior of the orbital, which resolves the difficulty mentioned above. Here, we extend the integral representation for the structure factor to many-electron systems treated within the Hartree-Fock method and show how it can be implemented on the basis of standard quantum chemistry software packages. We validate the methodology by considering noble-gas atoms and the CO molecule, for which accurate structure factors exist in the literature. We also present benchmark results for CO2 and for NH3 in the pyramidal and planar geometries.

Evidence for the functional significance of diazotroph community structure in soil.

Science.gov (United States)

Hsu, Shi-Fang; Buckley, Daniel H

2009-01-01

Microbial ecologists continue to seek a greater understanding of the factors that govern the ecological significance of microbial community structure. Changes in community structure have been shown to have functional significance for processes that are mediated by a narrow spectrum of organisms, such as nitrification and denitrification, but in some cases, functional redundancy in the community seems to buffer microbial ecosystem processes. The functional significance of microbial community structure is frequently obscured by environmental variation and is hard to detect in short-term experiments. We examine the functional significance of free-living diazotrophs in a replicated long-term tillage experiment in which extraneous variation is minimized and N-fixation rates can be related to soil characteristics and diazotroph community structure. Soil characteristics were found to be primarily impacted by tillage management, whereas N-fixation rates and diazotroph community structure were impacted by both biomass management practices and interactions between tillage and biomass management. The data suggest that the variation in diazotroph community structure has a greater impact on N-fixation rates than do soil characteristics at the site. N-fixation rates displayed a saturating response to increases in diazotroph community diversity. These results show that the changes in the community structure of free-living diazotrophs in soils can have ecological significance and suggest that this response is related to a change in community diversity.

Genetic diversity, outcrossing rate, and demographic history along a climatic gradient in the ruderal plant Ruellia nudiflora (Acanthaceae)

OpenAIRE

Vargas-Mendoza, Carlos F.; Ortegón-Campos, Ilka; Marrufo-Zapata, Denis; Herrera, Carlos M.; Parra-Tabla, Víctor

2015-01-01

Ruellia nudiflora has shown a high potential to easily invade disturbed areas. Outcrossing rate and genetic structure and diversity in this species were examined along a climatic gradient in the Yucatán Peninsula (Mexico) in order to understand the effects of environmental heterogeneity - isolation by environment (IBE) - as well as correlation in herkogamy on genetic structure, diversity, and demographic history in this species. Nine populations were sampled along a temperature-precipitation ...

Three Dimensional Response Spectrum Soil Structure Modeling Versus Conceptual Understanding To Illustrate Seismic Response Of Structures

International Nuclear Information System (INIS)

Touqan, Abdul Razzaq

2008-01-01

Present methods of analysis and mathematical modeling contain so many assumptions that separate them from reality and thus represent a defect in design which makes it difficult to analyze reasons of failure. Three dimensional (3D) modeling is so superior to 1D or 2D modeling, static analysis deviates from the true nature of earthquake load which is ''a dynamic punch'', and conflicting assumptions exist between structural engineers (who assume flexible structures on rigid block foundations) and geotechnical engineers (who assume flexible foundations supporting rigid structures). Thus a 3D dynamic soil-structure interaction is a step that removes many of the assumptions and thus clears reality to a greater extent. However such a model cannot be analytically analyzed. We need to anatomize and analogize it. The paper will represent a conceptual (analogical) 1D model for soil structure interaction and clarifies it by comparing its outcome with 3D dynamic soil-structure finite element analysis of two structures. The aim is to focus on how to calculate the period of the structure and to investigate effect of variation of stiffness on soil-structure interaction

Between individual agency and structure in HIV prevention: understanding the middle ground of social practice.

Science.gov (United States)

Kippax, Susan; Stephenson, Niamh; Parker, Richard G; Aggleton, Peter

2013-08-01

When HIV prevention targets risk and vulnerability, it focuses on individual agency and social structures, ignoring the centrality of community in effective HIV prevention. The neoliberal concept of risk assumes individuals are rational agents who act on information provided to them regarding HIV transmission. This individualistic framework does not recognize the communities in which people act and connect. The concept of vulnerability on the other hand acknowledges the social world, but mainly as social barriers that make it difficult for individuals to act. Neither approach to HIV prevention offers understanding of community practices or collective agency, both central to success in HIV prevention to date. Drawing on examples of the social transformation achieved by community action in Australia and Brazil, this article focuses on this middle ground and its role in effective HIV prevention.

The validity and structure of culture-level personality scores: data from ratings of young adolescents.

Science.gov (United States)

McCrae, Robert R; Terracciano, Antonio; De Fruyt, Filip; De Bolle, Marleen; Gelfand, Michele J; Costa, Paul T

2010-06-01

We examined properties of culture-level personality traits in ratings of targets (N=5,109) ages 12 to 17 in 24 cultures. Aggregate scores were generalizable across gender, age, and relationship groups and showed convergence with culture-level scores from previous studies of self-reports and observer ratings of adults, but they were unrelated to national character stereotypes. Trait profiles also showed cross-study agreement within most cultures, 8 of which had not previously been studied. Multidimensional scaling showed that Western and non-Western cultures clustered along a dimension related to Extraversion. A culture-level factor analysis replicated earlier findings of a broad Extraversion factor but generally resembled the factor structure found in individuals. Continued analysis of aggregate personality scores is warranted.

Studies on muon tomography for archaeological internal structures scanning

Science.gov (United States)

Gómez, H.; Carloganu, C.; Gibert, D.; Jacquemier, J.; Karyotakis, Y.; Marteau, J.; Niess, V.; Katsanevas, S.; Tonazzo, A.

2016-05-01

Muon tomography is a potential non-invasive technique for internal structure scanning. It has already interesting applications in geophysics and can be used for archaeological purposes. Muon tomography is based on the measurement of the muon flux after crossing the structure studied. Differences on the mean density of these structures imply differences on the detected muon rate for a given direction. Based on this principle, Monte Carlo simulations represent a useful tool to provide a model of the expected muon rate and angular distribution depending on the composition of the studied object, being useful to estimate the expected detected muons and to better understand the experimental results. These simulations are mainly dependent on the geometry and composition of the studied object and on the modelling of the initial muon flux at surface. In this work, the potential of muon tomography in archaeology is presented and evaluated with Monte Carlo simulations by estimating the differences on the muon rate due to the presence of internal structures and its composition. The influence of the chosen muon model at surface in terms of energy and angular distributions in the final result has been also studied.

Long Maturity Forward Rates

DEFF Research Database (Denmark)

Christiansen, Charlotte

2001-01-01

The paper aims to improve the knowledge of the empirical properties of the long maturity region of the forward rate curve. Firstly, the theoretical negative correlation between the slope at the long end of the forward rate curve and the term structure variance is recovered empirically and found...... to be statistically significant. Secondly, the expectations hypothesis is analyzed for the long maturity region of the forward rate curve using "forward rate" regressions. The expectations hypothesis is numerically close to being accepted but is statistically rejected. The findings provide mixed support...... for the affine term structure model....

Understanding and Improvement of an Experiment Measuring Chemical Reaction Rates by Monitoring Volume Change of a Gas: On the Reaction between HCl(aq) and Mg(s)

International Nuclear Information System (INIS)

Bang, Jeong Ah; Yoon, Hee Sook; Jeong, Dae Hong; Choi, Won Ho

2006-01-01

In this study we analyzed and improved an experiment measuring chemical reaction rates introduced in the high school science textbooks through an understanding of the phenomena observed in carrying out the experiment. For this purpose, the contents of textbooks related to the experiment were analyzed, and the problems observed in carrying out the experiment were addressed through experimental analysis. When the experiment was carried out by the method of aquatic transposition presented in textbooks, the observed volume change of H 2 gas was delayed and chemical reaction rate was increased in the early stage of reaction period. To resolve these problems, an improved method for measuring the reaction rates was suggested. In the improved experiment the reaction rate was measured to be constant on time, which was interpreted in terms of the concentration of H + and the surface area of magnesium

Brittle materials at high-loading rates: an open area of research

Science.gov (United States)

Forquin, Pascal

2017-01-01

Brittle materials are extensively used in many civil and military applications involving high-strain-rate loadings such as: blasting or percussive drilling of rocks, ballistic impact against ceramic armour or transparent windshields, plastic explosives used to damage or destroy concrete structures, soft or hard impacts against concrete structures and so on. With all of these applications, brittle materials are subjected to intense loadings characterized by medium to extremely high strain rates (few tens to several tens of thousands per second) leading to extreme and/or specific damage modes such as multiple fragmentation, dynamic cracking, pore collapse, shearing, mode II fracturing and/or microplasticity mechanisms in the material. Additionally, brittle materials exhibit complex features such as a strong strain-rate sensitivity and confining pressure sensitivity that justify expending greater research efforts to understand these complex features. Currently, the most popular dynamic testing techniques used for this are based on the use of split Hopkinson pressure bar methodologies and/or plate-impact testing methods. However, these methods do have some critical limitations and drawbacks when used to investigate the behaviour of brittle materials at high loading rates. The present theme issue of Philosophical Transactions A provides an overview of the latest experimental methods and numerical tools that are currently being developed to investigate the behaviour of brittle materials at high loading rates. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

An Evolutionary Framework for Understanding Sex Differences in Croatian Mortality Rates

Directory of Open Access Journals (Sweden)

Daniel J. Kruger

2006-12-01

Full Text Available Being male is the strongest demographic predictor of early mortality in Croatia. For every woman who dies between the ages of 15 and 34, three men die. Between the ages of 15 and 54, men are four times as likely as women to die from behavioral causes of death, such as accidents, homicides, and suicides. A causal explanation for sex differences in mortality must be based on an understanding of how sex differences were shaped by natural selection, and how those differences interact with environmental factors to create observed patterns and variations. In brief, males have been selected for riskier behavioral and physiological strategies than women, because of the greater variance and skew in male reproductive success. This paper examines the sex difference in Croatian mortality in three parts. First, we quantify the Croatian Male to Female Mortality Ratio (M:F MR for 9 major causes of death across age group to provide a richer understanding of the sex difference in mortality from a life history framework. Second, we compare the Croatian M:F MR from behavioral, internal, and all causes with that of the available world population to demonstrate how Croatian mortality can be understood as part of a universal pattern that is influenced by unique environmental context. Third, we investigate how the War of Independence in 1991-1995 affected mortality patterns though its impact on behavioral strategies and the physical embodiment of distress.

Structured Open Urban Data: Understanding the Landscape.

Science.gov (United States)

Barbosa, Luciano; Pham, Kien; Silva, Claudio; Vieira, Marcos R; Freire, Juliana

2014-09-01

A growing number of cities are now making urban data freely available to the public. Besides promoting transparency, these data can have a transformative effect in social science research as well as in how citizens participate in governance. These initiatives, however, are fairly recent and the landscape of open urban data is not well known. In this study, we try to shed some light on this through a detailed study of over 9,000 open data sets from 20 cities in North America. We start by presenting general statistics about the content, size, nature, and popularity of the different data sets, and then examine in more detail structured data sets that contain tabular data. Since a key benefit of having a large number of data sets available is the ability to fuse information, we investigate opportunities for data integration. We also study data quality issues and time-related aspects, namely, recency and change frequency. Our findings are encouraging in that most of the data are structured and published in standard formats that are easy to parse; there is ample opportunity to integrate different data sets; and the volume of data is increasing steadily. But they also uncovered a number of challenges that need to be addressed to enable these data to be fully leveraged. We discuss both our findings and issues involved in using open urban data.

The Prospective and Retrospective Memory Questionnaire (PRMQ): latent structure, normative data and discrepancy analysis for proxy-ratings.

Science.gov (United States)

Crawford, John R; Henry, Julie D; Ward, Aileen L; Blake, John

2006-03-01

To evaluate the proxy-rating version of the Prospective and Retrospective Memory Questionnaire (PRMQ) and provide norms and methods for score interpretation. Cross-sectional and correlational. The PRMQ was administered to a large sample drawn from the general adult population (N=570). Confirmatory factor analysis (CFA) was used to test competing models of its latent structure. Various psychometric methods were applied to provide clinicians with tools for score interpretation. The CFA model with optimal fit specified a general memory factor together with additional prospective and retrospective factors. The reliabilities of the PRMQ were acceptable (.83 to .92), and demographic variables did not influence ratings. Tables are presented for conversion of raw scores on the Total scale and Prospective and Retrospective scales to T scores. In addition, tables are provided to allow users to assess the reliability and abnormality of differences between proxy ratings on the Prospective and Retrospective scales. Finally, tables are also provided to compare proxy-ratings with self-ratings (using data from the present sample and self-rating data from a previous study). The proxy-rating version of the PRMQ provides a useful measure of everyday memory for use in clinical research and practice.

Children with Autism Understand Indirect Speech Acts: Evidence from a Semi-Structured Act-Out Task.

Directory of Open Access Journals (Sweden)

Mikhail Kissine

Full Text Available Children with Autism Spectrum Disorder are often said to present a global pragmatic impairment. However, there is some observational evidence that context-based comprehension of indirect requests may be preserved in autism. In order to provide experimental confirmation to this hypothesis, indirect speech act comprehension was tested in a group of 15 children with autism between 7 and 12 years and a group of 20 typically developing children between 2:7 and 3:6 years. The aim of the study was to determine whether children with autism can display genuinely contextual understanding of indirect requests. The experiment consisted of a three-pronged semi-structured task involving Mr Potato Head. In the first phase a declarative sentence was uttered by one adult as an instruction to put a garment on a Mr Potato Head toy; in the second the same sentence was uttered as a comment on a picture by another speaker; in the third phase the same sentence was uttered as a comment on a picture by the first speaker. Children with autism complied with the indirect request in the first phase and demonstrated the capacity to inhibit the directive interpretation in phases 2 and 3. TD children had some difficulty in understanding the indirect instruction in phase 1. These results call for a more nuanced view of pragmatic dysfunction in autism.

Cyclic strength of metals at impact strain rates

International Nuclear Information System (INIS)

Eleiche, A.M.; El-Kady, M.M.

1987-01-01

Rigorous understanding of the effects of impact loading on the mechanical response of materials and structures is essential for the optimum design and safe operation of many sophisticated engineering systems and components, such as industrial high-energy-rate fabrication processes and nuclear reactor containments. Extensive data are available at present on the dynamic behaviour of most metals in uniaxial tension, compression, torsion and pure shear, when they are subjected to diversified loading conditions, ranging from those characterised by monotonic constant rates, to those involving forward or reverse strain-rate jumps of several orders of magnitude. What appears to be missing in the current material data banks, however, is detailed information concerning the mechanical response under cyclic loading at impact strain rates. Such data are needed for engineering design purposes on one hand, and for the formulation of proper constitutive equations and the accurate modeling of deformation processes on the other. In the present paper, typical stress-strain characteristics at ambient temperature for copper, mild steel and titanium are first exhibited. The application of the unified Bodner-Partom constitutive theory to these data is then presented and discussed. (orig./GL)

Understanding the relationships between molecule structure and imprinting effect of two acetyl-nitrogen heterocyclic compounds.

Science.gov (United States)

Wang, Jian; Dong, Xiao; Xue, Min; Dong, Xuemin; Xu, Zhibin; Meng, Zihui; Luo, Jun

2016-06-01

The molecularly imprinted polymers (MIPs) for two structural analogs, 1,3,5-triacetyl-1,3,5-triazacyclohexane (TRAT) and 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT), have been synthesized respectively under the same conditions. The TAT-MIP showed excellent imprinting effect, whereas the TRAT-MIP did not. To understand the different imprinting effects of the MIPs prepared from these two templates, the geometric structures and energetic properties of complexes formed around TAT and TRAT were studied computationally. The results indicate that in liquid phase, for the complexes formed with TAT and its nearest neighbor molecules, the magnitude of the binding energy increases with the number of surrounding TAT, methacrylic acid, and acetonitrile (ACT), whereas for the cases of TRAT, the magnitude of the binding energy increases with the number of surrounding TRAT and trimethylolpropane trimethacrylate. The studied systems form stronger and thus more stable networks encapsulating TAT than with TRAT. ACT may also play an important role in the polymerization phase in stabilizing the shapes of the cavities that TATs reside in. We propose these as the major factors that affect the different imprinting effects of the two MIPs. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Engineering Mathematical Analysis Method for Productivity Rate in Linear Arrangement Serial Structure Automated Flow Assembly Line

Directory of Open Access Journals (Sweden)

Tan Chan Sin

2015-01-01

Full Text Available Productivity rate (Q or production rate is one of the important indicator criteria for industrial engineer to improve the system and finish good output in production or assembly line. Mathematical and statistical analysis method is required to be applied for productivity rate in industry visual overviews of the failure factors and further improvement within the production line especially for automated flow line since it is complicated. Mathematical model of productivity rate in linear arrangement serial structure automated flow line with different failure rate and bottleneck machining time parameters becomes the basic model for this productivity analysis. This paper presents the engineering mathematical analysis method which is applied in an automotive company which possesses automated flow assembly line in final assembly line to produce motorcycle in Malaysia. DCAS engineering and mathematical analysis method that consists of four stages known as data collection, calculation and comparison, analysis, and sustainable improvement is used to analyze productivity in automated flow assembly line based on particular mathematical model. Variety of failure rate that causes loss of productivity and bottleneck machining time is shown specifically in mathematic figure and presents the sustainable solution for productivity improvement for this final assembly automated flow line.

Regularities in structure formation of magnesium-yttrium alloy of Mg-Y-Mn-Cd system in relation to temperature and hot working rate

International Nuclear Information System (INIS)

Ovechkin, B.I.; Miklina, N.V.; Blokhin, N.N.; Sorokin, A.F.

1981-01-01

Problems of the structure formation of magnesium-yttrium alloy of Mg-G-Mn-Cd system with 7.8 % G in a wide range of temperature-rate parameters of hot working are studied. On the basis of X-ray analysis results ascertained with metallographic and electron microscopic investigations, a diagram of structural states after hot working of Mg-G-Mn-Cd system alloy has been plotted. A change in grain size in relation to temperature-rate conditions of hot working

Understanding Protein-Protein Interactions Using Local Structural Features

DEFF Research Database (Denmark)

Planas-Iglesias, Joan; Bonet, Jaume; García-García, Javier

2013-01-01

Protein-protein interactions (PPIs) play a relevant role among the different functions of a cell. Identifying the PPI network of a given organism (interactome) is useful to shed light on the key molecular mechanisms within a biological system. In this work, we show the role of structural features...... interacting and non-interacting protein pairs to classify the structural features that sustain the binding (or non-binding) behavior. Our study indicates that not only the interacting region but also the rest of the protein surface are important for the interaction fate. The interpretation...... to score the likelihood of the interaction between two proteins and to develop a method for the prediction of PPIs. We have tested our method on several sets with unbalanced ratios of interactions and non-interactions to simulate real conditions, obtaining accuracies higher than 25% in the most unfavorable...

Understanding structural engineering from theory to practice

CERN Document Server

Chen, Wai-Fah

2011-01-01

In our world of seemingly unlimited computing, numerous analytical approaches to the estimation of stress, strain, and displacement, including analytical, numerical, physical, and analog techniques, have greatly advanced the practice of engineering. Combining theory and experimentation, computer simulation has emerged as a third path for engineering design and performance evaluation. As a result, structural engineers working in the practical world of engineering must apply, and ideally, thrive, on these idealizations of science-based theories. Analyzing the major achievements in the field, Und

Comparison between continuous and localized methods to evaluate the flow rate through containment concrete structures

Energy Technology Data Exchange (ETDEWEB)

Jason, L., E-mail: ludovic.jason@cea.fr [Atomic Energy Commission (CEA), DEN, DANS, DM2S, SEMT, Mechanics and System Simulation Laboratory (LM2S), F-91191 Gif sur Yvette (France); LaMSID, UMR CNRS-EDF-CEA 8193, F-92141 Clamart (France); Masson, B. [Electricité de France (EDF), SEPTEN, F-69628 Villeurbanne (France)

2014-10-01

Highlights: • The contribution focuses on the gas transfer through reinforced concrete structures. • A continuous approach with a damage–permeability law is investigated. • It is significant, for this case, only when the damage variable crosses the section. • In this case, two localized approaches are compared. • It helps at evaluating a “reference” crack opening for engineering laws. - Abstract: In this contribution, different techniques are compared to evaluate the gas flow rate through a representative section of a reinforced and prestressed concrete containment structure. A continuous approach is first applied which is based on the evaluation of the gas permeability as a function of the damage variable. The calculations show that the flow rate becomes significant only when the damage variable crosses the section. But in this situation, the continuous approach is no longer fully valid. That is why localized approaches, based on a fine description of the crack openings, are then investigated. A comparison between classical simplified laws (Poiseuille flow) and a more refined model which takes into account the evolution of the crack opening in the depth of the section enables to define the validity domain of the simplified laws and especially the definition of the associated “reference opening”.

Rates of star formation

International Nuclear Information System (INIS)

Larson, R.B.

1977-01-01

It is illustrated that a theoretical understanding of the formation and evolution of galaxies depends on an understanding of star formation, and especially of the factors influencing the rate of star formation. Some of the theoretical problems of star formation in galaxies, some approaches that have been considered in models of galaxy evolution, and some possible observational tests that may help to clarify which processes or models are most relevant are reviewed. The material is presented under the following headings: power-law models for star formation, star formation processes (conditions required, ways of achieving these conditions), observational indications and tests, and measures of star formation rates in galaxies. 49 references

Southern Ocean frontal structure and sea-ice formation rates revealed by elephant seals

Science.gov (United States)

Charrassin, J.-B.; Hindell, M.; Rintoul, S. R.; Roquet, F.; Sokolov, S.; Biuw, M.; Costa, D.; Boehme, L.; Lovell, P.; Coleman, R.; Timmermann, R.; Meijers, A.; Meredith, M.; Park, Y.-H.; Bailleul, F.; Goebel, M.; Tremblay, Y.; Bost, C.-A.; McMahon, C. R.; Field, I. C.; Fedak, M. A.; Guinet, C.

2008-01-01

Polar regions are particularly sensitive to climate change, with the potential for significant feedbacks between ocean circulation, sea ice, and the ocean carbon cycle. However, the difficulty in obtaining in situ data means that our ability to detect and interpret change is very limited, especially in the Southern Ocean, where the ocean beneath the sea ice remains almost entirely unobserved and the rate of sea-ice formation is poorly known. Here, we show that southern elephant seals (Mirounga leonina) equipped with oceanographic sensors can measure ocean structure and water mass changes in regions and seasons rarely observed with traditional oceanographic platforms. In particular, seals provided a 30-fold increase in hydrographic profiles from the sea-ice zone, allowing the major fronts to be mapped south of 60°S and sea-ice formation rates to be inferred from changes in upper ocean salinity. Sea-ice production rates peaked in early winter (April–May) during the rapid northward expansion of the pack ice and declined by a factor of 2 to 3 between May and August, in agreement with a three-dimensional coupled ocean–sea-ice model. By measuring the high-latitude ocean during winter, elephant seals fill a “blind spot” in our sampling coverage, enabling the establishment of a truly global ocean-observing system. PMID:18695241

Understanding the structural differences between spherical and rod-shaped human insulin nanoparticles produced by supercritical fluids precipitation.

Science.gov (United States)

Park, Yeonju; Seo, Yongil; Chae, Boknam; Pyo, Dongjin; Chung, Hoeil; Hwang, Hyonseok; Jung, Young Mee

2015-02-02

In this study, the thermal denaturation mechanism and secondary structures of two types of human insulin nanoparticles produced by a process of solution-enhanced dispersion by supercritical fluids using dimethyl sulfoxide (DMSO) and ethanol (EtOH) solutions of insulin are investigated using spectroscopic approaches and molecular dynamics calculations. First, the temperature-dependent IR spectra of spherical and rod-shaped insulin nanoparticles prepared from DMSO and EtOH solution, respectively, are analyzed using principal component analysis (PCA) and 2D correlation spectroscopy to obtain a deeper understanding of the molecular structures and thermal behavior of the two insulin particle shapes. All-atom molecular dynamics (AAMD) calculations are performed to investigate the influence of the solvent molecules on the production of the insulin nanoparticles and to elucidate the geometric differences between the two types of nanoparticles. The results of the PCA, the 2D correlation spectroscopic analysis, and the AAMD calculations clearly reveal that the thermal denaturation mechanisms and the degrees of hydrogen bonding in the spherical and rod-shaped insulin nanoparticles are different. The polarity of the solvent might not alter the structure or function of the insulin produced, but the solvent polarity does influence the synthesis of different shapes of insulin nanoparticles. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Strength and Deformation Rate of Plate Boundaries: The Rheological Effects of Grain Size Reduction, Structure, and Serpentinization.

Science.gov (United States)

Montesi, L.; Gueydan, F.

2016-12-01

Global strain rate maps reveal 1000-fold contrasts between plate interiors, oceanic or continental diffuse plate boundaries and narrow plate boundaries. Here, we show that rheological models based on the concepts of shear zone localization and the evolution of rock structure upon strain can explain these strain rate contrasts. Ductile shear zones constitute a mechanical paradox in the lithosphere. As every plastic deformation mechanism is strain-rate-hardening, ductile rocks are expected to deform at low strain rate and low stress (broad zone of deformation). Localized ductile shear zones require either a localized forcing (locally high stress) or a thermal or structural anomaly in the shear zone; either can be inherited or develop progressively as rocks deform. We previously identified the most effective process at each depth level of the lithosphere. In the upper crust and middle crust, rocks fabric controls localization. Grain size reduction is the most efficient mechanism in the uppermost mantle. This analysis can be generalized to consider a complete lithospheric section. We assume strain rate does not vary with depth and that the depth-integrated strength of the lithospheric does not change over time, as the total force is controlled by external process such as mantle convection and plate and slab buoyancy. Reducing grain size from a coarse value typical of undeformed peridotite to a value in agreement with the stress level (piezometer) while letting that stress vary from depth to depth (the integrated stress remains the same) increases the lithospheric strain rate by about a factor of 1000. This can explain the development of diffuse plate boundaries. The slightly higher strain rate of continental plate boundary may reflect development of a layered rock fabric in the middle crust. Narrow plate boundaries require additional weakening process. The high heat flux near mid-ocean ridge implies a thin lithosphere, which enhances stress (for constant integrated

Understanding MARC: Another Look

Directory of Open Access Journals (Sweden)

Roy Chang

1989-12-01

Full Text Available 無MARC format has been widely used and discussed in our profession. However, there appear to have a wide spread misunderstanding of its real structure and attributes. This article discuss the needs for us to understand it a little more. Also, it presents the general misconceptions about MARC, the compatibility of MARC, the structure of MARC, standardization and - data communication, and some major issues related to MARC format. In this library automation age, MARC is a key element in library services, and it deserves us to take another look.

Microbes as engines of ecosystem function: when does community structure enhance predictions of ecosystem processes?

Directory of Open Access Journals (Sweden)

Emily B. Graham

2016-02-01

Full Text Available Microorganisms are vital in mediating the earth’s biogeochemical cycles; yet, despite our rapidly increasing ability to explore complex environmental microbial communities, the relationship between microbial community structure and ecosystem processes remains poorly understood. Here, we address a fundamental and unanswered question in microbial ecology: ‘When do we need to understand microbial community structure to accurately predict function?’ We present a statistical analysis investigating the value of environmental data and microbial community structure independently and in combination for explaining rates of carbon and nitrogen cycling processes within 82 global datasets. Environmental variables were the strongest predictors of process rates but left 44% of variation unexplained on average, suggesting the potential for microbial data to increase model accuracy. Although only 29% of our datasets were significantly improved by adding information on microbial community structure, we observed improvement in models of processes mediated by narrow phylogenetic guilds via functional gene data, and conversely, improvement in models of facultative microbial processes via community diversity metrics. Our results also suggest that microbial diversity can strengthen predictions of respiration rates beyond microbial biomass parameters, as 53% of models were improved by incorporating both sets of predictors compared to 35% by microbial biomass alone. Our analysis represents the first comprehensive analysis of research examining links between microbial community structure and ecosystem function. Taken together, our results indicate that a greater understanding of microbial communities informed by ecological principles may enhance our ability to predict ecosystem process rates relative to assessments based on environmental variables and microbial physiology.

Some new understanding on the characteristics of geological structure and uranium metallogenetic prospect on both sides of the Shandianhe down-faulted zone

International Nuclear Information System (INIS)

Zhang Xuequan

1992-01-01

On the basis of the systematic work in the field and at the laboratory, the metallogenetic prognosis map (1:100000) of geological structures and uranium metallogenetic prospect on both sides of the Shandianhe down-faulted zone is compiled. According to this, the regional setting of metallogenesis is emphatically expounded and some new understanding is presented. After the detailed study on the characteristics of geological structures on both sides of the Shangdianhe down-faulted zone, the metallogenetic prospective area are selected and the further prospecting targets in the area are suggested

A structural equation modeling approach to understanding pathways that connect socioeconomic status and smoking.

Science.gov (United States)

Martinez, Sydney A; Beebe, Laura A; Thompson, David M; Wagener, Theodore L; Terrell, Deirdra R; Campbell, Janis E

2018-01-01

The inverse association between socioeconomic status and smoking is well established, yet the mechanisms that drive this relationship are unclear. We developed and tested four theoretical models of the pathways that link socioeconomic status to current smoking prevalence using a structural equation modeling (SEM) approach. Using data from the 2013 National Health Interview Survey, we selected four indicator variables (poverty ratio, personal earnings, educational attainment, and employment status) that we hypothesize underlie a latent variable, socioeconomic status. We measured direct, indirect, and total effects of socioeconomic status on smoking on four pathways through four latent variables representing social cohesion, financial strain, sleep disturbance, and psychological distress. Results of the model indicated that the probability of being a smoker decreased by 26% of a standard deviation for every one standard deviation increase in socioeconomic status. The direct effects of socioeconomic status on smoking accounted for the majority of the total effects, but the overall model also included significant indirect effects. Of the four mediators, sleep disturbance and psychological distress had the largest total effects on current smoking. We explored the use of structural equation modeling in epidemiology to quantify effects of socioeconomic status on smoking through four social and psychological factors to identify potential targets for interventions. A better understanding of the complex relationship between socioeconomic status and smoking is critical as we continue to reduce the burden of tobacco and eliminate health disparities related to smoking.

Future Mars geophysical observatories for understanding its internal structure, rotation, and evolution

DEFF Research Database (Denmark)

Dehant, Veronique; Banerdt, Bruce; Lognonné, Philippe

2012-01-01

of Mars, these measurements will provide important constraints for the astrobiology of Mars by helping to understand why Mars failed to sustain a magnetic field, by helping to understand the planet’s climate evolution, and by providing a limit for the energy available to the chemoautotrophic biosphere...

Deep-UV Raman spectroscopic analysis of structure and dissolution rates of silica-rich sodium borosilicate glasses

Energy Technology Data Exchange (ETDEWEB)

Pierce, Eric M [ORNL; WindischJr., Charles F. [Pacific Northwest National Laboratory (PNNL); Burton, Sarah D. [Pacific Northwest National Laboratory (PNNL); Bovaird, Chase C. [Pacific Northwest National Laboratory (PNNL)

2010-01-01

As part of ongoing studies to evaluate relationships between structure and rates of dissolution of silicate glasses in aqueous media, sodium borosilicate glasses of composition Na2O xB2O3 (3 x)SiO2, with x 1 (Na2O/B2O3 ratio 1), were analyzed using deep-UV Raman spectroscopy. Results were quantified in terms of the fraction of SiO4 tetrahedra with one non-bridging oxygen (Q3) and then correlated with Na2O and B2O3 content. The Q3 fractionwas found to increase with increasing Na2O content, in agreement with studies on related glasses, and, as long as the value of x was not too high, this contributed to higher rates of dissolution in single pass flow-through testing. In contrast, dissolution rates were less strongly determined by the Q3 fraction when the value of x was near unity, and appeared to grow larger upon further reduction of the Q3 fraction. Results were interpreted to indicate the increasingly important role of network hydrolysis in the glass dissolution mechanism as the BO4 tetrahedron replaces the Q3 unit as the charge-compensating structure for Na+ ions. Finally, the use of deep-UV Raman spectroscopy was found to be advantageous in studying finely powdered glasses in cases where visible Raman spectroscopy suffered from weak Raman scattering and fluorescence interference.

Impact of the canine double-deletion β1 adrenoreceptor polymorphisms on protein structure and heart rate response to atenolol, a β1-selective β-blocker.

Science.gov (United States)

Meurs, Kathryn M; Stern, Josh A; Reina-Doreste, Yamir; Maran, Brian A; Chdid, Lhoucine; Lahmers, Sunshine; Keene, Bruce W; Mealey, Katrina L

2015-09-01

β-Adrenergic receptor antagonists are widely utilized for the management of cardiac diseases in dogs. We have recently identified two deletion polymorphisms in the canine adrenoreceptor 1 (ADRB1) gene.We hypothesized that canine ADRB1 deletions would alter the structure of the protein, as well as the heart rate response to the β-adrenergic receptor antagonist, atenolol. The objectives of this study were to predict the impact of these deletions on the predicted structure of the protein and on the heart rate response to atenolol in a population of healthy adult dogs. Eighteen apparently healthy, mature dogs with (11) and without (seven) ADRB1 deletions were evaluated. The heart rate of the dogs was evaluated with a baseline ambulatory ECG before and 14-21 days after atenolol therapy (1 mg/kg orally q12 h). Minimum, average, and maximum heart rates were compared between groups of dogs (deletions, controls) using an unpaired t-test and within each group of dogs using a paired t-test. The protein structure of ADRB1 was predicted by computer modeling. Deletions were predicted to alter the structure of the ADRB1 protein. The heart rates of the dogs with deletions were lower than those of the control dogs (the average heart rates were significantly lower). ADRB1 deletions appear to have structural and functional consequences. Individual genome-based treatment recommendations could impact the management of dogs with heart disease.

Genetic diversity, outcrossing rate, and demographic history along a climatic gradient in the ruderal plant Ruellia nudiflora (Acanthaceae)

OpenAIRE

Vargas-Mendoza, Carlos F.; Ortegón-Campos, Ilka; Marrufo-Zapata, Denis; Herrera, Carlos M.; Parra-Tabla, Víctor

2015-01-01

© 2015 Universidad Nacional Autónoma de México, Instituto de Biología. All Rights Reserved. Ruellia nudiflora has shown a high potential to easily invade disturbed areas. Outcrossing rate and genetic structure and diversity in this species were examined along a climatic gradient in the Yucatán Peninsula (Mexico) in order to understand the effects of environmental heterogeneity - isolation by environment (IBE) - as well as correlation in herkogamy on genetic structure, diversity, and demograph...

Organisational Structure

Science.gov (United States)

National Centre for Vocational Education Research (NCVER), 2006

2006-01-01

An understanding of organisational structure can provide guidance for organisations that want to change and innovate. Many writers agree that this understanding allows organisations to shape how their work is done to ultimately achieve their business goals--and that too often structure is given little consideration in business strategy and…

Influence of the crack propagation rate in the obtaining opening and closing stress intensity factor by finite element method

OpenAIRE

Luiz Carlos H. Ricardo; Carlos Alexandre J. Miranda

2016-01-01

Crack propagation simulation began with the development of the finite element method; the analyses were conducted to obtain a basic understanding of the crack growth. Today structural and materials engineers develop structures and materials properties using this technique as criterion design. The aim of this paper is to verify the effect of different crack propagation rates in determination of crack opening and closing stress of an ASTM specimen under a standard suspension spectrum loading fr...

Understanding the atmospheric pressure ionization of petroleum components: The effects of size, structure, and presence of heteroatoms

International Nuclear Information System (INIS)

Huba, Anna Katarina; Huba, Kristina; Gardinali, Piero R.

2016-01-01

Understanding the composition of crude oil and its changes with weathering is essential when assessing its provenience, fate, and toxicity. High-resolution mass spectrometry (HRMS) has provided the opportunity to address the complexity of crude oil by assigning molecular formulae, and sorting compounds into “classes” based on heteroatom content. However, factors such as suppression effects and discrimination towards certain components severely limit a truly comprehensive mass spectrometric characterization, and, despite the availability of increasingly better mass spectrometers, a complete characterization of oil still represents a major challenge. In order to fully comprehend the significance of class abundances, as well as the nature and identity of compounds detected, a good understanding of the ionization efficiency of the various compound classes is indispensable. The current study, therefore, analyzed model compounds typically found in crude oils by high-resolution mass spectrometry with atmospheric pressure photoionization (APPI), atmospheric pressure chemical ionization (APCI), and electrospray ionization (ESI), in order to provide a better understanding of benefits and drawbacks of each source. The findings indicate that, overall, APPI provides the best results, being able to ionize the broadest range of compounds, providing the best results with respect to ionization efficiencies, and exhibiting the least suppression effects. However, just like in the other two sources, in APPI several factors have shown to affect the ionization efficiency of petroleum model compounds. The main such factor is the presence or absence of functional groups that can be easily protonated/deprotonated, in addition to other factors such as size, methylation level, presence of heteroatoms, and ring structure. Overall, this study evidences the intrinsic limitations and benefits of each of the three sources, and should provide the fundamental knowledge required to expand the

Understanding the atmospheric pressure ionization of petroleum components: The effects of size, structure, and presence of heteroatoms

Energy Technology Data Exchange (ETDEWEB)

Huba, Anna Katarina; Huba, Kristina [Department of Chemistry & Biochemistry, Florida International University, 3000 NE 151 Street, Biscayne Bay Campus, North Miami, Florida 33181 (United States); Gardinali, Piero R. [Department of Chemistry & Biochemistry, Florida International University, 3000 NE 151 Street, Biscayne Bay Campus, North Miami, Florida 33181 (United States); Southeast Environmental Research Center (SERC), Florida International University, 3000 NE 151 Street, Biscayne Bay Campus, North Miami, Florida 33181 (United States)

2016-10-15

Understanding the composition of crude oil and its changes with weathering is essential when assessing its provenience, fate, and toxicity. High-resolution mass spectrometry (HRMS) has provided the opportunity to address the complexity of crude oil by assigning molecular formulae, and sorting compounds into “classes” based on heteroatom content. However, factors such as suppression effects and discrimination towards certain components severely limit a truly comprehensive mass spectrometric characterization, and, despite the availability of increasingly better mass spectrometers, a complete characterization of oil still represents a major challenge. In order to fully comprehend the significance of class abundances, as well as the nature and identity of compounds detected, a good understanding of the ionization efficiency of the various compound classes is indispensable. The current study, therefore, analyzed model compounds typically found in crude oils by high-resolution mass spectrometry with atmospheric pressure photoionization (APPI), atmospheric pressure chemical ionization (APCI), and electrospray ionization (ESI), in order to provide a better understanding of benefits and drawbacks of each source. The findings indicate that, overall, APPI provides the best results, being able to ionize the broadest range of compounds, providing the best results with respect to ionization efficiencies, and exhibiting the least suppression effects. However, just like in the other two sources, in APPI several factors have shown to affect the ionization efficiency of petroleum model compounds. The main such factor is the presence or absence of functional groups that can be easily protonated/deprotonated, in addition to other factors such as size, methylation level, presence of heteroatoms, and ring structure. Overall, this study evidences the intrinsic limitations and benefits of each of the three sources, and should provide the fundamental knowledge required to expand the

Structural study of Ge/GaAs thin films

International Nuclear Information System (INIS)

Lazarov, V K; Lari, L; Lytvyn, P M; Kholevchuk, V V; Mitin, V F

2012-01-01

Ge/GaAs heterostructure research is largely motivated by the application of this material in solar cells, metal-oxide-semiconductor field-effect transistors, mm-wave mixer diodes, temperature sensors and photodetectors. Therefore, understanding of how the properties of Ge/GaAs heterostructure depend on its preparation (growth) is of importance for various high-efficiency devices. In this work, by using thermal Ge evaporation on GaAs(100), we studied structural properties of these films as a function of the deposition rate. Film grains size and morphology show strong dependence of the deposition rate. Low deposition rates results in films with large crystal grains and rough surface. At high deposition rates films become flatter and their crystal grains size decreases, while at very high deposition rates films become amorphous. Cross-sectional TEM of the films show that the Ge films are granular single crystal epitaxially grown on GaAs. The Ge/GaAs interface is atomically abrupt and free from misfit dislocations. Stacking faults along the [111] directions that originate at the interface were also observed. Finally by using the Kelvin probe microscopy we show that work function changes are related to the grain structure of the film.

Structural shell analysis understanding and application

CERN Document Server

Blaauwendraad, Johan

2014-01-01

The mathematical description of the properties of a shell is much more elaborate than those of beam and plate structures. Therefore many engineers and architects are unacquainted with aspects of shell behaviour and design, and are not familiar with sufficiently reliable shell theories for the different shell types as derived in the middle of the 20th century. Rather than contributing to theory development, this university textbook focuses on architectural and civil engineering schools. Of course, practising professionals will profit from it as well. The book deals with thin elastic shells, in particular with cylindrical, conical and spherical types, and with elliptic and hyperbolic paraboloids. The focus is on roofs, chimneys, pressure vessels and storage tanks. Special attention is paid to edge bending disturbance zones, which is indispensable knowledge in FE meshing. A substantial part of the book results from research efforts in the mid 20th century at Delft University of Technology. As such, it is a valua...

The Effect of Logical Thinking and Two Cognitive Styles on Understanding the Structure of Matter: An Analysis with the Random Walk Method

Science.gov (United States)

Stamovlasis, Dimitrios; Tsitsipis, Georgios; Papageorgiou, George

2010-01-01

This work uses the concepts and tools of complexity theory to examine the effect of logical thinking and two cognitive styles, such as, the degree of field dependence/independence and the convergent/divergent thinking on students' understanding of the structure of matter. Students were categorized according to the model they adopted for the…

Pre-treatment factor structures of the Montgomery and Åsberg Depression Rating scale as predictors of response to escitalopram in Indian patients with non-psychotic major depressive disorder.

Science.gov (United States)

Basu, Aniruddha; Chadda, Rakesh; Sood, Mamta; Rizwan, S A

2017-08-01

Major Depressive Disorder (MDD) is a broad heterogeneous construct resolving into several symptom-clusters by factor analysis. The aim was to find the factor structures of MDD as per Montgomery and Asberg Depression Rating Scale (MADRS) and whether they predict escitalopram response. In a longitudinal study at a tertiary institute in north India, 116 adult out-patients with non-psychotic unipolar MDD were assessed with MADRS before and after treatment with escitalopram (10-20mg) over 6-8 weeks for drug response. For total 116 patients pre-treatment four factor structures of MADRS extracted by principal component analysis with varimax rotation altogether explained a variance of 57%: first factor 'detachment' (concentration difficulty, lassitude, inability to feel); second factor 'psychic anxiety' (suicidal thoughts and inner tension); third 'mood-pessimism' (apparent sadness, reported sadness, pessimistic thoughts) and fourth 'vegetative' (decreased sleep, appetite). Eighty patients (68.9%) who completed the study had mean age 35.37±10.9 yrs, majority were male (57.5%), with mean pre-treatment MADRS score 28.77±5.18 and majority (65%) having moderate severity (MADRS escitalopram. At the end of the treatment there were significant changes in all the 4 factor structures (pescitalopram treatment. Understanding the factor structure is important as they can be important predictor of escitalopram response. Copyright © 2017 Elsevier B.V. All rights reserved.

EVALUATION OF THE STRUCTURAL FUNDS ABSORPTION RATE BY MEANS OF THE HERMIN MODEL

Directory of Open Access Journals (Sweden)

Opritescu Elena Madalina

2012-07-01

Full Text Available The main objective of this article is to highlight the main method that could quantify the impact of the structural funds on the Gross Domestic Product. I also presented the regional disparities situation and the European funds absorption rate. The HERMIN model has been designed considering the evolution of macro-variables throughout transition and pre-accession process, as well as out of the need to analyze the gradual alignment of Romania’s economic policies to those of EU. The fact that, initially, the HERMIN model was designed for the European Union’s less developed economies represented the cornerstone in choosing it, as it was the case for Romania, too. However, the quantitative evaluation must always be accompanied by a qualitative evaluation, in order to comprise factors which cannot be measured by the econometrical modeling. For this purpose, when the results of econometrical model based evaluation are used, it is important to be aware of the fact that models simplify reality, no matter the impressive mathematical calculations they employ. Also, we must not omit the fact that Romania’s major development needs and the current economic context imperatively demand a high as possible level of structural funds absorption, as well as their efficient use, meant to generate a significant impact at a national, regional and local level. One of the main instruments employed to sustain economic growth, while also reducing disparities between regions is represented by the structural funds. These funds, consisting in financial contributions of the member states, according to their level of development, are redistributed in compliance with an extremely complex regulating and procedural frame, to those EU states of regions which are fallen behind from a social and economical development perspective Nevertheless, when absorption capacity of a member state is evaluated, the used percentage from the allocated funds is not the only

Change in the structures, dynamics and disease-related mortality rates of the population of Qatari nationals: 2007–2011

OpenAIRE

Mohamed H. Al-Thani; Eman Sadoun; Al-Anoud Al-Thani; Shamseldin A. Khalifa; Suzan Sayegh; Alaa Badawi

2014-01-01

Background: Developing effective public health policies and strategies for interventions necessitates an assessment of the structure, dynamics, disease rates and causes of death in a population. Lately, Qatar has undertaken development resurgence in health and economy that resulted in improving the standard of health services and health status of the entire Qatari population (i.e., Qatari nationals and non-Qatari residents). No study has attempted to evaluate the population structure/dynamics...

Understanding Structure-Property Relations of Compressed Glasses through Relaxation Studies

DEFF Research Database (Denmark)

Smedskjær, Morten Mattrup; Svenson, Mouritz Nolsøe; Youngman, Randall E.

under high pressure from both scientific and technological perspectives, since the glass structures frozen-in under elevated pressure may give rise to properties unattainable under ambient pressure. However, the structural and topological origins of the pressure-induced changes in macroscopic properties...

Understanding Mediation Support

OpenAIRE

Lanz, David; Pring, Jamie; von Burg, Corinne; Zeller, Mathias

2017-01-01

Recent decades have witnessed increasing institutionalization of mediation support through the establishment of mediation support structures (MSS) within foreign ministries and secretariats of multilateral organizations. This study sheds light on this trend and aims to better understand the emergence, design and development of different MSS. This study analyzes six MSS, namely those established in the United Nations (UN), the Organization for Security and Co-operation in Europe (OSCE), the Eu...

Understanding Resilience

Directory of Open Access Journals (Sweden)

Gang eWu

2013-02-01

Full Text Available Resilience is the ability to adapt successfully in the face of stress and adversity. Stressful life events, trauma and chronic adversity can have a substantial impact on brain function and structure, and can result in the development of PTSD, depression and other psychiatric disorders. However, most individuals do not develop such illnesses after experiencing stressful life events, and are thus thought to be resilient. Resilience as successful adaptation relies on effective responses to environmental challenges and ultimate resistance to the deleterious effects of stress, therefore a greater understanding of the factors that promote such effects is of great relevance. This review focuses on recent findings regarding genetic, epigenetic, developmental, psychosocial and neurochemical factors that are considered essential contributors to the development of resilience. Neural circuits and pathways involved in mediating resilience are also discussed. The growing understanding of resilience factors will hopefully lead to the development of new pharmacological and psychological interventions for enhancing resilience and mitigating the untoward consequences.

What is religion? an African understanding

OpenAIRE

Beyers, Jaco

2010-01-01

Western thought has influenced the way that religion is understood. Western philosophy supported the separation between the sacred and the profane. Modernism, focusing on human rationality, reduced religion to a set of correctly formulated dogmas and doctrines. Western thought, dominated by Christianity, created a hierarchical structure of world religions through a theology of religions. Can an African understanding of religion make a contribution to the understanding of what religion is? Suc...

Understanding biochar mechanisms for practical implementation

Energy Technology Data Exchange (ETDEWEB)

Glaser, Bruno [Halle-Wittenberg Univ. (Germany). Inst. fuer Agrar- und Ernaehrungeswissenschaften Bodenbiogeochemie; Kammann, Claudia [Arbeitskreis zur Nutzung von Sekundaerrohstoffen und fuer Klimaschutz (ANS) e.V., Braunschweig (Germany). Fachausschuss Biokohle; Hochschule Geisenheim Univ. (Germany). Klimafolgenforschung-Klimawandel in Spezialkulturen; Loewen, Achim (ed.) [Arbeitskreis zur Nutzung von Sekundaerrohstoffen und fuer Klimaschutz (ANS) e.V., Braunschweig (Germany); HAWK Hochschule fuer Angewandte Wissenschaft und Kunst Hildesheim, Holzminden, Goettingen (Germany). Fachgebiet Nachhaltige Energie- und Umwelttechnik NEUtec

2015-07-01

The conference on ''understanding biochar mechanisms for practical implementation'' 2015 at the Geisenheim University aims at understanding biochar mechanism, that are crucial for beneficial and safety biochar technology implementation. Further issues are ecotoxicology, biochar in agriculture, horticulture, and animal husbandry. Practical issues concern analysis and characterization of technological processes, sustainable uses and certification, regulation and marketing aspects. The Conference is structured in 10 sessions.

Credit Rating As a Factor of Stability in the Global Capital Market

Directory of Open Access Journals (Sweden)

Ismail Musabegović

2014-12-01

Full Text Available Credit rating has an outstanding importance on the capital market. Opinions and assessments of rating agencies help us to improve growth, stability and efficiency of international and domestic markets, which now include over 80 trillion dollars of rated bonds and other securities with the fixed income. The contribution of the credit agencies to the market stability and efficiency is reflected in their ability to provide accurate, clear and reliable assessments of the solvency of participants on the financial markets. An adequate and proper risk assessment of securities contributes to stability. In order to achieve a given goal and to satisfy its purpose, the assessments should be based on a fundamental understanding of the key components of the credit risk. Also, in order to ensure a reliable framework for making investment decisions, the rating agencies are obliged to offer and to provide a wide range of securities, which are based on a global comparability of rating symbols and onthe support given by the credit rating assignment committee and by the other relevant decision making bodies. Markets for structured products could not have developed without the quality assurance provided by CRAs. When analyzing a securitization program CRAs examine legal and structural protections provided to investors. Since the globalization is an inevitable phenomenon in today’s world the importance of the credit rating becomes more noticeable. On the other hand, the rating agencies have an obligation to reanalyze their decision making models in order to contribute tothe reliability of the evaluation.

ICYESS 2013: Understanding and Interpreting Uncertainty

Science.gov (United States)

Rauser, F.; Niederdrenk, L.; Schemann, V.; Schmidt, A.; Suesser, D.; Sonntag, S.

2013-12-01

We will report the outcomes and highlights of the Interdisciplinary Conference of Young Earth System Scientists (ICYESS) on Understanding and Interpreting Uncertainty in September 2013, Hamburg, Germany. This conference is aimed at early career scientists (Masters to Postdocs) from a large variety of scientific disciplines and backgrounds (natural, social and political sciences) and will enable 3 days of discussions on a variety of uncertainty-related aspects: 1) How do we deal with implicit and explicit uncertainty in our daily scientific work? What is uncertain for us, and for which reasons? 2) How can we communicate these uncertainties to other disciplines? E.g., is uncertainty in cloud parameterization and respectively equilibrium climate sensitivity a concept that is understood equally well in natural and social sciences that deal with Earth System questions? Or vice versa, is, e.g., normative uncertainty as in choosing a discount rate relevant for natural scientists? How can those uncertainties be reconciled? 3) How can science communicate this uncertainty to the public? Is it useful at all? How are the different possible measures of uncertainty understood in different realms of public discourse? Basically, we want to learn from all disciplines that work together in the broad Earth System Science community how to understand and interpret uncertainty - and then transfer this understanding to the problem of how to communicate with the public, or its different layers / agents. ICYESS is structured in a way that participation is only possible via presentation, so every participant will give their own professional input into how the respective disciplines deal with uncertainty. Additionally, a large focus is put onto communication techniques; there are no 'standard presentations' in ICYESS. Keynote lectures by renowned scientists and discussions will lead to a deeper interdisciplinary understanding of what we do not really know, and how to deal with it. Many

A quantitative theory of solid tumor growth, metabolic rate and vascularization.

Directory of Open Access Journals (Sweden)

Alexander B Herman

Full Text Available The relationships between cellular, structural and dynamical properties of tumors have traditionally been studied separately. Here, we construct a quantitative, predictive theory of solid tumor growth, metabolic rate, vascularization and necrosis that integrates the relationships between these properties. To accomplish this, we develop a comprehensive theory that describes the interface and integration of the tumor vascular network and resource supply with the cardiovascular system of the host. Our theory enables a quantitative understanding of how cells, tissues, and vascular networks act together across multiple scales by building on recent theoretical advances in modeling both healthy vasculature and the detailed processes of angiogenesis and tumor growth. The theory explicitly relates tumor vascularization and growth to metabolic rate, and yields extensive predictions for tumor properties, including growth rates, metabolic rates, degree of necrosis, blood flow rates and vessel sizes. Besides these quantitative predictions, we explain how growth rates depend on capillary density and metabolic rate, and why similar tumors grow slower and occur less frequently in larger animals, shedding light on Peto's paradox. Various implications for potential therapeutic strategies and further research are discussed.

Composition and crystal structure of N doped TiO2 film deposited at different O2 flow rate by direct current sputtering.

Science.gov (United States)

Ding, Wanyu; Ju, Dongying; Chai, Weiping

2011-06-01

N doped Ti02 films were deposited by direct current pulse magnetron sputtering system at room temperature. The influence of 02 flow rate on the crystal structure of deposited films was studied by Stylus profilometer, X-ray photoelectron spectroscopy, and X-ray diffractometer. The results indicate that the 02 flow rate strongly controls the growth behavior and crystal structure of N doped Ti02 film. It is found that N element mainly exists as substitutional doped state and the chemical stiochiometry is near to TiO1.68±0.06N0.11±0.01 for all film samples. N doped Ti02 film deposited with 2 sccm (standard-state cubic centimeter per minute) 02 flow rate is amorphous structure with high growth rate, which contains both anatase phase and rutile phase crystal nucleuses. In this case, the film displays the mix-phase of anatase and rutile after annealing treatment. While N doped Ti02 film deposited with 12 cm(3)/min 02 flow rate displays anatase phase before and after annealing treatment. And it should be noticed that no TiN phase appears for all samples before and after annealing treatment. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Simulation modeling to understand how selective foraging by beaver can drive the structure and function of a willow community

Science.gov (United States)

Peinetti, H.R.; Baker, B.W.; Coughenour, M.B.

2009-01-01

Beaver-willow (Castor-Salix) communities are a unique and vital component of healthy wetlands throughout the Holarctic region. Beaver selectively forage willow to provide fresh food, stored winter food, and construction material. The effects of this complex foraging behavior on the structure and function of willow communities is poorly understood. Simulation modeling may help ecologists understand these complex interactions. In this study, a modified version of the SAVANNA ecosystem model was developed to better understand how beaver foraging affects the structure and function of a willow community in a simulated riparian ecosystem in Rocky Mountain National Park, Colorado (RMNP). The model represents willow in terms of plant and stem dynamics and beaver foraging in terms of the quantity and quality of stems cut to meet the energetic and life history requirements of beaver. Given a site where all stems were equally available, the model suggested a simulated beaver family of 2 adults, 2 yearlings, and 2 kits required a minimum of 4 ha of willow (containing about10 stems m-2) to persist in a steady-state condition. Beaver created a willow community where the annual net primary productivity (ANPP) was 2 times higher and plant architecture was more diverse than the willow community without beaver. Beaver foraging created a plant architecture dominated by medium size willow plants, which likely explains how beaver can increase ANPP. Long-term simulations suggested that woody biomass stabilized at similar values even though availability differed greatly at initial condition. Simulations also suggested that willow ANPP increased across a range of beaver densities until beaver became food limited. Thus, selective foraging by beaver increased productivity, decreased biomass, and increased structural heterogeneity in a simulated willow community.

Evaluating wildlife-cattle contact rates to improve the understanding of dynamics of bovine tuberculosis transmission in Michigan, USA.

Science.gov (United States)

Lavelle, Michael J; Kay, Shannon L; Pepin, Kim M; Grear, Daniel A; Campa, Henry; VerCauteren, Kurt C

2016-12-01

Direct and indirect contacts among individuals drive transmission of infectious disease. When multiple interacting species are susceptible to the same pathogen, risk assessment must include all potential host species. Bovine tuberculosis (bTB) is an example of a disease that can be transmitted among several wildlife species and to cattle, although the potential role of several wildlife species in spillback to cattle remains unclear. To better understand the complex network of contacts and factors driving disease transmission, we fitted proximity logger collars to beef and dairy cattle (n=37), white-tailed deer (Odocoileus virginianus; n=29), raccoon (Procyon lotor; n=53), and Virginia opossum (Didelphis virginiana; n=79) for 16 months in Michigan's Lower Peninsula, USA. We determined inter- and intra-species direct and indirect contact rates. Data on indirect contact was calculated when collared animals visited stationary proximity loggers placed at cattle feed and water resources. Most contact between wildlife species and cattle was indirect, with the highest contact rates occurring between raccoons and cattle during summer and fall. Nearly all visits (>99%) to cattle feed and water sources were by cattle, whereas visitation to stored cattle feed was dominated by deer and raccoon (46% and 38%, respectively). Our results suggest that indirect contact resulting from wildlife species visiting cattle-related resources could pose a risk of disease transmission to cattle and deserves continued attention with active mitigation. Published by Elsevier B.V.

Toward a new understanding of the links between poverty and illegal wildlife hunting.

Science.gov (United States)

Duffy, Rosaleen; St John, Freya A V; Büscher, Bram; Brockington, Dan

2016-02-01

Conservation organizations have increasingly raised concerns about escalating rates of illegal hunting and trade in wildlife. Previous studies have concluded that people hunt illegally because they are financially poor or lack alternative livelihood strategies. However, there has been little attempt to develop a richer understanding of the motivations behind contemporary illegal wildlife hunting. As a first step, we reviewed the academic and policy literatures on poaching and illegal wildlife use and considered the meanings of poverty and the relative importance of structure and individual agency. We placed motivations for illegal wildlife hunting within the context of the complex history of how wildlife laws were initially designed and enforced to indicate how hunting practices by specific communities were criminalized. We also considered the nature of poverty and the reasons for economic deprivation in particular communities to indicate how particular understandings of poverty as material deprivation ultimately shape approaches to illegal wildlife hunting. We found there is a need for a much better understanding of what poverty is and what motivates people to hunt illegally. © 2015 Society for Conservation Biology.

Shapley ratings in brain networks

Directory of Open Access Journals (Sweden)

Rolf Kötter

2007-11-01

Full Text Available Recent applications of network theory to brain networks as well as the expanding empirical databases of brain architecture spawn an interest in novel techniques for analyzing connectivity patterns in the brain. Treating individual brain structures as nodes in a directed graph model permits the application of graph theoretical concepts to the analysis of these structures within their large-scale connectivity networks. In this paper, we explore the application of concepts from graph and game theory toward this end. Specifically, we utilize the Shapley value principle, which assigns a rank to players in a coalition based upon their individual contributions to the collective profit of that coalition, to assess the contributions of individual brain structures to the graph derived from the global connectivity network. We report Shapley values for variations of a prefrontal network, as well as for a visual cortical network, which had both been extensively investigated previously. This analysis highlights particular nodes as strong or weak contributors to global connectivity. To understand the nature of their contribution, we compare the Shapley values obtained from these networks and appropriate controls to other previously described nodal measures of structural connectivity. We find a strong correlation between Shapley values and both betweenness centrality and connection density. Moreover, a stepwise multiple linear regression analysis indicates that approximately 79% of the variance in Shapley values obtained from random networks can be explained by betweenness centrality alone. Finally, we investigate the effects of local lesions on the Shapley ratings, showing that the present networks have an immense structural resistance to degradation. We discuss our results highlighting the use of such measures for characterizing the organization and functional role of brain networks.

Factors Associated with Asthma ED Visit Rates among Medicaid-enrolled Children: A Structural Equation Modeling Approach

Directory of Open Access Journals (Sweden)

Luceta McRoy

2017-02-01

Full Text Available Background: Asthma is one of the leading causes of emergency department visits and school absenteeism among school-aged children in the United States, but there is significant local-area variation in emergency department visit rates, as well as significant differences across racial-ethnic groups. Analysis: We first calculated emergency department (ED visit rates among Medicaid-enrolled children age 5–12 with asthma using a multi-state dataset. We then performed exploratory factor analysis using over 226 variables to assess whether they clustered around three county-level conceptual factors (socioeconomic status, healthcare capacity, and air quality thought to be associated with variation in asthma ED visit rates. Measured variables (including ED visit rate as the outcome of interest were then standardized and tested in a simple conceptual model through confirmatory factor analysis. Results: County-level (contextual variables did cluster around factors declared a priori in the conceptual model. Structural equation models connecting the ED visit rates to socioeconomic status, air quality, and healthcare system professional capacity factors (consistent with our conceptual framework converged on a solution and achieved a reasonable goodness of fit on confirmatory factor analysis. Conclusion: Confirmatory factor analysis offers an approach for quantitatively testing conceptual models of local-area variation and racial disparities in asthma-related emergency department use.

Brittle materials at high-loading rates: an open area of research

Science.gov (United States)

2017-01-01

Brittle materials are extensively used in many civil and military applications involving high-strain-rate loadings such as: blasting or percussive drilling of rocks, ballistic impact against ceramic armour or transparent windshields, plastic explosives used to damage or destroy concrete structures, soft or hard impacts against concrete structures and so on. With all of these applications, brittle materials are subjected to intense loadings characterized by medium to extremely high strain rates (few tens to several tens of thousands per second) leading to extreme and/or specific damage modes such as multiple fragmentation, dynamic cracking, pore collapse, shearing, mode II fracturing and/or microplasticity mechanisms in the material. Additionally, brittle materials exhibit complex features such as a strong strain-rate sensitivity and confining pressure sensitivity that justify expending greater research efforts to understand these complex features. Currently, the most popular dynamic testing techniques used for this are based on the use of split Hopkinson pressure bar methodologies and/or plate-impact testing methods. However, these methods do have some critical limitations and drawbacks when used to investigate the behaviour of brittle materials at high loading rates. The present theme issue of Philosophical Transactions A provides an overview of the latest experimental methods and numerical tools that are currently being developed to investigate the behaviour of brittle materials at high loading rates. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’. PMID:27956517

Understanding resident ratings of teaching in the workplace: a multi-centre study.

Science.gov (United States)

Fluit, Cornelia R M G; Feskens, Remco; Bolhuis, Sanneke; Grol, Richard; Wensing, Michel; Laan, Roland

2015-08-01

Providing clinical teachers with feedback about their teaching skills is a powerful tool to improve teaching. Evaluations are mostly based on questionnaires completed by residents. We investigated to what extent characteristics of residents, clinical teachers, and the clinical environment influenced these evaluations, and the relation between residents' scores and their teachers' self-scores. The evaluation and feedback for effective clinical teaching questionnaire (EFFECT) was used to (self)assess clinical teachers from 12 disciplines (15 departments, four hospitals). Items were scored on a five-point Likert scale. Main outcome measures were residents' mean overall scores (MOSs), specific scale scores (MSSs), and clinical teachers' self-evaluation scores. Multilevel regression analysis was used to identify predictors. Residents' scores and self-evaluations were compared. Residents filled in 1,013 questionnaires, evaluating 230 clinical teachers. We received 160 self-evaluations. 'Planning Teaching' and 'Personal Support' (4.52, SD .61 and 4.53, SD .59) were rated highest, 'Feedback Content' (CanMEDS related) (4.12, SD .71) was rated lowest. Teachers in affiliated hospitals showed highest MOS and MSS. Medical specialty did not influence MOS. Female clinical teachers were rated higher for most MSS, achieving statistical significance. Residents in year 1-2 were most positive about their teachers. Residents' gender did not affect the mean scores, except for role modeling. At group level, self-evaluations and residents' ratings correlated highly (Kendall's τ 0.859). Resident evaluations of clinical teachers are influenced by teacher's gender, year of residency training, type of hospital, and to a lesser extent teachers' gender. Clinical teachers and residents agree on strong and weak points of clinical teaching.

The Hanford Site's Gable Mountain structure: A comparison of the recurrence of design earthquakes based on fault slip rates and a probabilistic exposure model

International Nuclear Information System (INIS)

Rohay, A.C.

1991-01-01

Gable Mountain is a segment of the Umtanum Ridge-Gable Mountain structural trend, an east-west trending series of anticlines, one of the major geologic structures on the Hanford Site. A probabilistic seismic exposure model indicates that Gable Mountain and two adjacent segments contribute significantly to the seismic hazard at the Hanford Site. Geologic measurements of the uplift of initially horizontal (11-12 Ma) basalt flows indicate that a broad, continuous, primary anticline grew at an average rate of 0.009-0.011 mm/a, and narrow, segmented, secondary anticlines grew at rates of 0.009 mm/a at Gable Butte and 0.018 mm/a at Gable Mountain. The buried Southeast Anticline appears to have a different geometry, consisting of a single, intermediate-width anticline with an estimated growth rate of 0.007 mm/a. The recurrence rate and maximum magnitude of earthquakes for the fault models were used to estimate the fault slip rate for each of the fault models and to determine the implied structural growth rate of the segments. The current model for Gable Mountain-Gable Butte predicts 0.004 mm/a of vertical uplift due to primary faulting and 0.008 mm/a due to secondary faulting. These rates are roughly half the structurally estimated rates for Gable Mountain, but the model does not account for the smaller secondary fold at Gable Butte. The model predicted an uplift rate for the Southeast Anticline of 0.006 mm/a, caused by the low open-quotes fault capabilityclose quotes weighting rather than a different fault geometry. The effects of previous modifications to the fault models are examined and potential future modifications are suggested. For example, the earthquake recurrence relationship used in the current exposure model has a b-value of 1.15, compared to a previous value of 0.85. This increases the implied deformation rates due to secondary fault models, and therefore supports the use of this regionally determined b-value to this fault/fold system

STRUCTURAL INTERACTIONS OF HYDROGEN WITH BULK AMORPHOUS MICROSTRUCTURES IN METALLIC SYSTEMS UNDERSTANDING THE ROLE OF PARTIAL CRYSTALLINITY ON PERMEATION AND EMBRITTLEMENT

Energy Technology Data Exchange (ETDEWEB)

Brinkman, Kyle; Fox, Elise; Korinko, Paul; Adams, Thad

2010-05-10

The development of metallic glasses in bulk form has led to a resurgence of interest into the utilization of these materials for a variety of applications. A potentially exciting application for these bulk metallic glass (BMG) materials is their use as composite membranes to replace high cost Pd/Pd-alloy membranes for enhanced gas separation processes. One of the major drawbacks to the industrial use of Pd/Pd-alloy membranes is that during cycling above and below a critical temperature an irreversible change takes place in the palladium lattice structure which can result in significant damage to the membrane. Furthermore, the cost associated with Pd-based membranes is a potential detractor for their continued use and BMG alloys offer a potentially attractive alternative. Several BMG alloys have been shown to possess high permeation rates, comparable to those measured for pure Pd metal. In addition, high strength and toughness when either in-situ or ex-situ second phase dispersoids are present. Both of these properties, high permeation and high strength/toughness, potentially make these materials attractive for gas separation membranes that could resist hydrogen 'embrittlement'. However, a fundamental understanding of the relationship between partially crystalline 'structure'/devitrification and permeation/embrittlement in these BMG materials is required in order to determine the operating window for separation membranes and provide additional input to the material synthesis community for improved alloy design. This project aims to fill the knowledge gap regarding the impact of crystallization on the permeation properties of metallic glass materials. The objectives of this study are to (i) determine the crystallization behavior in different gas environments of Fe and Zr based commercially available bulk metallic glass and (ii) quantify the effects of partial crystallinity on the hydrogen permeation properties of these metallic glass membranes.

Structure and dynamics of solutions

CERN Document Server

Ohtaki, H

2013-01-01

Recent advances in the study of structural and dynamic properties of solutions have provided a molecular picture of solute-solvent interactions. Although the study of thermodynamic as well as electronic properties of solutions have played a role in the development of research on the rate and mechanism of chemical reactions, such macroscopic and microscopic properties are insufficient for a deeper understanding of fast chemical and biological reactions. In order to fill the gap between the two extremes, it is necessary to know how molecules are arranged in solution and how they change their pos

[Dose rate-dependent cellular and molecular effects of ionizing radiation].

Science.gov (United States)

Przybyszewski, Waldemar M; Wideł, Maria; Szurko, Agnieszka; Maniakowski, Zbigniew

2008-09-11

The aim of radiation therapy is to kill tumor cells while minimizing damage to normal cells. The ultimate effect of radiation can be apoptotic or necrotic cell death as well as cytogenetic damage resulting in genetic instability and/or cell death. The destructive effects of radiation arise from direct and indirect ionization events leading to peroxidation of macromolecules, especially those present in lipid-rich membrane structures as well as chromatin lipids. Lipid peroxidative end-products may damage DNA and proteins. A characteristic feature of radiation-induced peroxidation is an inverse dose-rate effect (IDRE), defined as an increase in the degree of oxidation(at constant absorbed dose) accompanying a lower dose rate. On the other hand, a low dose rate can lead to the accumulation of cells in G2, the radiosensitive phase of the cell cycle since cell cycle control points are not sensitive to low dose rates. Radiation dose rate may potentially be the main factor improving radiotherapy efficacy as well as affecting the intensity of normal tissue and whole-body side effects. A better understanding of dose rate-dependent biological effects may lead to improved therapeutic intervention and limit normal tissue reaction. The study reviews basic biological effects that depend on the dose rate of ionizing radiation.

Movements in the term structure of interest rates

OpenAIRE

Robert R. Bliss

1997-01-01

Bond prices tend to move together. Stocks tend to go their own way. This distinction requires completely different approaches to managing risks for these securities. For equities the emphasis is on reducing idiosyncratic risk through portfolio diversification. For interest rate-sensitive securities it is on precisely balancing a portfolio to achieve the desired exposure to systematic risk factors. ; Hedging to reduce or eliminate the common factors influencing an interest rate-sensitive portf...

The feasible study of the water flow in the micro channel with the Y-junction and narrow structure for various flow rates

Directory of Open Access Journals (Sweden)

Jasikova D.

2015-01-01

Full Text Available Here we present the results of measurement in micro-channel with the Y-junction and narrow structure for various flow rates. There was used BSG micro-channel with trapezoidal cross-section. The parameters of the channel are described in the paper. The flow in the micro-channel was invested with micro-PIV technique and various flow rates were set on each inlet. The resulting flow rate in the steady area follows the laminar flow with very low Re 30. Here we are focused on the flow characteristic in the Y-junction and in selected narrow structure. The fluid flow is evaluated with vector and scalar maps and the profile plots that were taken in the point of interest.

Shape understanding system machine understanding and human understanding

CERN Document Server

Les, Zbigniew

2015-01-01

This is the third book presenting selected results of research on the further development of the shape understanding system (SUS) carried out by authors in the newly founded Queen Jadwiga Research Institute of Understanding. In this book the new term Machine Understanding is introduced referring to a new area of research aiming to investigate the possibility of building machines with the ability to understand. It is presented that SUS needs to some extent mimic human understanding and for this reason machines are evaluated according to the rules applied for the evaluation of human understanding. The book shows how to formulate problems and how it can be tested if the machine is able to solve these problems.    

Understanding the organization of cognitive approaches to translation

DEFF Research Database (Denmark)

Serban, Maria

2017-01-01

Cognitive approaches to translation studies are driven by three interrelated aims: to understand the structure and organization of the capacities of cognitive agents involved in processes of translation, to build better theories and models of translation, and to develop more efficient methods...... theory, it is more descriptively adequate and more fruitful to understand it as a family of projects based on multiple theories that are relevant for studying different aspects of the translation process. This perspective allows us to extract the erotetic structure of these programs which are organized...

Long-term rate orientations: Development plan 1993

International Nuclear Information System (INIS)

1992-01-01

Hydro-Quebec's preferred rate orientations for Quebec markets are presented. The background for a rate structure revision is outlined, followed by proposed changes to residential and general rates, and by a plan to implement the new rate structure. Some of the principles used in setting rates are described. The new rate structure proposals are intended to provide a better reflection of the utility's costs of supply and a clearer signal in favor of the rational use of electricity, thereby limiting long-term increases in both supply costs and electricity rates. It is proposed to use marginal costs to design rate structures, while the overall rate level will continue to reflect changes in average costs of supply. Also included in the proposed changes are time-of-use rates, which will help reduce costs by shifting loads from peak to off-peak periods and by encouraging the adoption of energy-conservation measures. Moreover, the integration of time-of-use options into the rate system will not only provide Hydro-Quebec with more powerful load-management tools but also give customers the opportunity to change their consumption patterns and thereby reduce their electricity bills. 11 figs., 11 tabs

Testing hypotheses in an I(2) model with piecewise linear trends. An analysis of the persistent long swings in the Dmk/$ rate

DEFF Research Database (Denmark)

Johansen, Søren; Juselius, Katarina; Frydman, Roman

2010-01-01

This paper discusses the I(2) model with breaks in the deterministic component and illustrates with an analysis of German and US prices, exchange rates, and interest rates in 1975--1999. It provides new results on the likelihood ratio test of overidentifying restrictions on the cointegrating...... relations when they contain piecewise linear trends. One important aim of the paper is to demonstrate that a structured I(2) analysis is useful for a better understanding of the empirical regularities underlying the persistent swings in nominal exchange rates, typical in periods of floating exchange rates....

High-speed imaging and small-scale explosive characterization techniques to understand effects of primary blast-induced injury on nerve cell structure and function

Science.gov (United States)

Piehler, T.; Banton, R.; Zander, N.; Duckworth, J.; Benjamin, R.; Sparks, R.

2018-01-01

Traumatic brain injury (TBI) is often associated with blast exposure. Even in the absence of penetrating injury or evidence of tissue injury on imaging, blast TBI may trigger a series of neural/glial cellular and functional changes. Unfortunately, the diagnosis and proper treatment of mild traumatic brain injury (mTBI) caused by explosive blast is challenging, as it is not easy to clinically distinguish blast from non-blast TBI on the basis of patient symptoms. Damage to brain tissue, cell, and subcellular structures continues to occur slowly and in a manner undetectable by conventional imaging techniques. The threshold shock impulse levels required to induce damage and the cumulative effects upon multiple exposures are not well characterized. Understanding how functional and structural damage from realistic blast impact at cellular and tissue levels at variable timescales after mTBI events may be vital for understanding this injury phenomenon and for linking mechanically induced structural changes with measurable effects on the nervous system. Our working hypothesis is that there is some transient physiological dysfunction occurring at cellular and subcellular levels within the central nervous system due to primary blast exposure. We have developed a novel in vitro indoor experimental system that uses real military explosive charges to more accurately represent military blast exposure and to probe the effects of primary explosive blast on dissociated neurons. We believe this system offers a controlled experimental method to analyze and characterize primary explosive blast-induced cellular injury and to understand threshold injury phenomenon. This paper will also focus on the modeling aspect of our work and how it relates to the experimental work.

The ARTT motif and a unified structural understanding of substraterecognition in ADP ribosylating bacterial toxins and eukaryotic ADPribosyltransferases

Energy Technology Data Exchange (ETDEWEB)

Han, S.; Tainer, J.A.

2001-08-01

motif structural framework. Thus, we propose here that the ARTT motif represents an experimentally testable general recognition motif region for many ADP-ribosyltransferases and thereby potentially provides a unified structural understanding of substrate recognition in ADP-ribosylation processes.

Toward a better understanding of the comparatively high prostate cancer incidence rates in Utah.

Science.gov (United States)

Merrill, Ray M; Hilton, Sterling C; Wiggins, Charles L; Sturgeon, Jared D

2003-04-29

This study assesses whether comparatively high prostate cancer incidence rates among white men in Utah represent higher rates among members of the Church of Jesus Christ of Latter-day Saints (LDS or Mormons), who comprise about 70% of the state's male population, and considers the potential influence screening has on these rates. Analyses are based on 14,693 histologically confirmed invasive prostate cancer cases among men aged 50 years and older identified through the Utah Cancer Registry between 1985 and 1999. Cancer records were linked to LDS Church membership records to determine LDS status. Poisson regression was used to derive rate ratios of LDS to nonLDS prostate cancer incidence, adjusted for age, disease stage, calendar time, and incidental detection. LDS men had a 31% (95% confidence interval, 26%-36%) higher incidence rate of prostate cancer than nonLDS men during the study period. Rates were consistently higher among LDS men over time (118% in 1985-88, 20% in 1989-92, 15% in 1993-1996, and 13% in 1997-99); age (13% in ages 50-59, 48% in ages 60-69, 28% in ages 70-79, and 16% in ages 80 and older); and stage (36% in local/regional and 17% in unstaged). An age- and stage-shift was observed for both LDS and nonLDS men, although more pronounced among LDS men. Comparatively high prostate cancer incidence rates among LDS men in Utah are explained, at least in part, by more aggressive screening among these men.

From structure to mechanism—understanding initiation of DNA replication

Science.gov (United States)

Riera, Alberto; Barbon, Marta; Noguchi, Yasunori; Reuter, L. Maximilian; Schneider, Sarah; Speck, Christian

2017-01-01

DNA replication results in the doubling of the genome prior to cell division. This process requires the assembly of 50 or more protein factors into a replication fork. Here, we review recent structural and biochemical insights that start to explain how specific proteins recognize DNA replication origins, load the replicative helicase on DNA, unwind DNA, synthesize new DNA strands, and reassemble chromatin. We focus on the minichromosome maintenance (MCM2–7) proteins, which form the core of the eukaryotic replication fork, as this complex undergoes major structural rearrangements in order to engage with DNA, regulate its DNA-unwinding activity, and maintain genome stability. PMID:28717046

Experimental Study of the Effect of Beam Loading on RF Breakdown Rate in CLIC High-Gradient Accelerating Structures

CERN Document Server

Tecker, F; Kelisani, M; Doebert, S; Grudiev, A; Quirante, J; Riddone, G; Syratchev, I; Wuensch, W; Kononenko, O; Solodko, A; Lebet, S

2013-01-01

RF breakdown is a key issue for the multi-TeV highluminosity e+e- Compact Linear Collider (CLIC). Breakdowns in the high-gradient accelerator structures can deflect the beam and decrease the desired luminosity. The limitations of the accelerating structures due to breakdowns have been studied so far without a beam present in the structure. The presence of the beam modifies the distribution of the electrical and magnetic field distributions, which determine the breakdown rate. Therefore an experiment has been designed for high power testing a CLIC prototype accelerating structure with a beam present in the CLIC Test Facility (CTF3). A special beam line allows extracting a beam with nominal CLIC beam current and duration from the CTF3 linac. The paper describes the beam optics design for this experimental beam line and the commissioning of the experiment with beam.

Understanding of catalysis on early transition metal oxide-based catalysts through exploration of surface structure and chemistry during catalysis using in-situ approaches

Energy Technology Data Exchange (ETDEWEB)

Tao, Franklin [Univ. of Kansas, Lawrence, KS (United States). Dept. of Chemical and Petroleum Engineering. Dept. of Chemistry

2015-09-14

Two main categories of heterogeneous catalysts are metal and metal oxide which catalyze 80% chemical reactions at solid-gas and solid-liquid interfaces. Metal oxide catalysts are much more complicated than metal catalysts. The reason is that the cations of the metal atoms could exhibit a few different oxidation states on surface of the same catalyst particle such as Co₃O₄ or change of their oxidation states under different reactive environments. For a metal catalyst, there is only one oxidation state typically. In addition, surface of a metal oxide can be terminated with multiple surface functionalities including O atoms with different binding configurations and OH group. For metal, only metal atoms are exposed typically. Obviously, the complication of surface chemistry and structure of a metal oxide makes studies of surface of an oxide catalyst very challenging. Due to the complication of surface of a meal oxide, the electronic and geometric structures of surface of a metal oxide and the exposed species have received enormous attention since oxide catalysts catalyze at least 1/3 chemical reactions in chemical and energy industries. Understanding of catalytic reactions on early transition metal oxide-based catalysts is fundamentally intriguing and of great practical interest in energy- and environment-related catalysis. Exploration of surface chemistry of oxide-based catalysts at molecular level during catalysis has remained challenging though it is critical in deeply understanding catalysis on oxide-based catalysts and developing oxide-based catalysts with high activity and selectivity. Thus, the overall objective of this project is to explore surface chemistry and structure of early transition metal oxide-based catalysts through in-situ characterization of surface of catalysts, measurements of catalytic performances, and then build an intrinsic correlation of surface chemistry and structure with their catalytic performances in a few

Scrambling the Nest Egg: How Well Do Teachers Understand Their Pensions, and What Do They Think about Alternative Pension Structures? Working Paper 51

Science.gov (United States)

DeArmond, Michael; Goldhaber, Dan

2010-01-01

This paper addresses two questions: How well do teachers understand their current pension plans? And, what do they think about alternative plan structures? The data come from administrative records and a 2006 survey of teachers in Washington State. The results suggest Washington's teachers are fairly knowledgeable about their pensions, though new…

Understanding of electrochemical and structural changes of polypyrrole/polyethylene glycol composite films in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Pirvu, Cristian, E-mail: c_pirvu@chim.pub.ro [University Polytechnic of Bucharest, Faculty of Applied Chemistry and Materials Science, 1-7 Polizu, 011061 Bucharest (Romania); Manole, Claudiu Constantin; Stoian, Andrei Bogdan; Demetrescu, Ioana [University Polytechnic of Bucharest, Faculty of Applied Chemistry and Materials Science, 1-7 Polizu, 011061 Bucharest (Romania)

2011-11-30

Highlights: > Electrochemical monitoring of PPy and PPy-PEG films over immersion time. > Electrochemical and surface analysis showed that PEG improves the stability of PPy films. > Mott-Schottky analysis reveals p-type conductance for both films. > In situ AFM analysis sustains electrochemical behaviour. > A model of PPy and PPy-PEG films behaviour during immersion was elaborated. - Abstract: Electrochemical monitoring of electrical and structural changes of both PPy and PPy-PEG films electrochemical deposited, in order to highlight if the structural stability offered by PEG has an influence on electrical properties and stability in aqueous solution over immersion time was investigated. Electrochemical analysis suggests that PPy-PEG film inserts cations easier than PPy film for a short immersion time probably due to ability of PEG to form complexes with metal cations. The FTIR spectra showed that the PEG incorporation decreases the rate of PPy overoxidation probably by restraining the electron release and by rendering O{sub 2} inaccessible to PPy. Mott-Schottky analysis based on capacitance measurement reveal p-type conductance for both films. The in situ AFM analysis sustains electrochemical behaviour and has permitted elaboration of a model of PPy and PPy-PEG films behaviour during immersion in testing solution.

The right friends in the right places: Understanding network structure as a predictor of voluntary turnover.

Science.gov (United States)

Ballinger, Gary A; Cross, Rob; Holtom, Brooks C

2016-04-01

Research examining the relationship between social networks and employee retention has focused almost exclusively on the number of direct links and generally found that having more ties decreases the likelihood of turnover. The present research moves beyond simple measures of network centrality to investigate the relationship between 2 additional, and theoretically distinct, facets of social capital and voluntary turnover. In 2 organizations, we found consistent evidence of a negative relationship between reputation, as measured by relationships with highly sought-out others (incoming eigenvector centrality) and voluntary turnover. Further, we found that the negative relationship between brokerage (structural holes) and turnover is significant, but only for higher-level employees. The theoretical and practical implications of expanding the suite of social capital measures to understand voluntary turnover are discussed. (c) 2016 APA, all rights reserved).

Structure-Activity Relationships for Rates of Aromatic Amine Oxidation by Manganese Dioxide.

Science.gov (United States)

Salter-Blanc, Alexandra J; Bylaska, Eric J; Lyon, Molly A; Ness, Stuart C; Tratnyek, Paul G

2016-05-17

New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO2) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. In this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammett σ constants (σ(-)), pKas of the amines, and energies of the highest occupied molecular orbital (EHOMO)] to specific for the likely rate-limiting step [one-electron oxidation potentials (Eox)]. The selection of calculated descriptors (pKa, EHOMO, and Eox) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to EHOMO (calculated with a modest level of theory).

Impact of AlN seeding layer growth rate in MOVPE growth of semi-polar gallium nitride structures on high index silicon

Energy Technology Data Exchange (ETDEWEB)

Ravash, Roghaiyeh; Blaesing, Juergen; Hempel, Thomas; Noltemeyer, Martin; Dadgar, Armin; Christen, Juergen; Krost, Alois [Otto-von-Guericke-University Magdeburg, FNW/IEP/AHE, Postfach 4120, 39016 Magdeburg (Germany)

2011-03-15

We present metal organic vapor phase epitaxy growth of semi-polar GaN structures on high index silicon surfaces. The crystallographic structure of GaN grown on Si(112), (115), and (117) substrates is investigated by X-ray analysis and scanning electron microscopy. X-ray diffraction was performed in Bragg Brentano geometry as well as pole figure measurements. The results demonstrate that the orientation of GaN crystallites on Si is significantly dependent on thickness of the AlN seeding layer and TMAl-flow rate. We observe that the crystallographic structures of GaN by applying thin AlN seeding layers grown with high TMAl-flow rate depend on Si surface direction while they are independent for thicker layers. By applying such seeding layer we obtain single crystalline semi-polar GaN on Si(112), while GaN structures grown with the same growth parameters on Si(117) show four components of GaN(0002). (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Influence of the crack propagation rate in the obtaining opening and closing stress intensity factor by finite element method

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Luiz Carlos H. Ricardo

2016-03-01

Full Text Available Crack propagation simulation began with the development of the finite element method; the analyses were conducted to obtain a basic understanding of the crack growth. Today structural and materials engineers develop structures and materials properties using this technique as criterion design. The aim of this paper is to verify the effect of different crack propagation rates in determination of crack opening and closing stress of an ASTM specimen under a standard suspension spectrum loading from FD&E SAE Keyhole Specimen Test Load Histories by finite element analysis. The crack propagation simulation was based on release nodes at the minimum loads to minimize convergence problems. To understand the crack propagation processes under variable amplitude loading, retardation effects are discussed.

An Integrated Assessment of Geochemical and Community Structure Determinants of Metal Reduction Rates in Subsurface Sediments. Final report

International Nuclear Information System (INIS)

Pfiffner, Susan

2010-01-01

The objective of this research was to examine the importance of microbial community structure in influencing uranium reduction rates in subsurface sediments. If the redox state alone is the key to metal reduction, then any organisms that can utilize the oxygen and nitrate in the subsurface can change the geochemical conditions so metal reduction becomes an energetically favored reaction. Thus, community structure would not be critical in determining rates or extent of metal reduction unless community structure influenced the rate of change in redox. Alternatively, some microbes may directly catalyze metal reduction (e.g., specifically reduce U). In this case the composition of the community may be more important and specific types of electron donors may promote the production of communities that are more adept at U reduction. Our results helped determine if the type of electron donor or the preexisting community is important in the bioremediation of metal-contaminated environments subjected to biostimulation. In a series of experiments at the DOE FRC site in Oak Ridge we have consistently shown that all substrates promoted nitrate reduction, while glucose, ethanol, and acetate always promoted U reduction. Methanol only occasionally promoted extensive U reduction which is possibly due to community heterogeneity. There appeared to be limitations imposed on the community related to some substrates (e.g. methanol and pyruvate). Membrane lipid analyses (phospholipids and respiratory quinones) indicated different communities depending on electron donor used. Terminal restriction fragment length polymorphism and clone libraries indicated distinct differences among communities even in treatments that promoted U reduction. Thus, there was enough metabolic diversity to accommodate many different electron donors resulting in the U bioimmobilization.

From structure to mechanism-understanding initiation of DNA replication.

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Riera, Alberto; Barbon, Marta; Noguchi, Yasunori; Reuter, L Maximilian; Schneider, Sarah; Speck, Christian

2017-06-01

DNA replication results in the doubling of the genome prior to cell division. This process requires the assembly of 50 or more protein factors into a replication fork. Here, we review recent structural and biochemical insights that start to explain how specific proteins recognize DNA replication origins, load the replicative helicase on DNA, unwind DNA, synthesize new DNA strands, and reassemble chromatin. We focus on the minichromosome maintenance (MCM2-7) proteins, which form the core of the eukaryotic replication fork, as this complex undergoes major structural rearrangements in order to engage with DNA, regulate its DNA-unwinding activity, and maintain genome stability. © 2017 Riera et al.; Published by Cold Spring Harbor Laboratory Press.

Cancer3D: understanding cancer mutations through protein structures.

Science.gov (United States)

Porta-Pardo, Eduard; Hrabe, Thomas; Godzik, Adam

2015-01-01

The new era of cancer genomics is providing us with extensive knowledge of mutations and other alterations in cancer. The Cancer3D database at http://www.cancer3d.org gives an open and user-friendly way to analyze cancer missense mutations in the context of structures of proteins in which they are found. The database also helps users analyze the distribution patterns of the mutations as well as their relationship to changes in drug activity through two algorithms: e-Driver and e-Drug. These algorithms use knowledge of modular structure of genes and proteins to separately study each region. This approach allows users to find novel candidate driver regions or drug biomarkers that cannot be found when similar analyses are done on the whole-gene level. The Cancer3D database provides access to the results of such analyses based on data from The Cancer Genome Atlas (TCGA) and the Cancer Cell Line Encyclopedia (CCLE). In addition, it displays mutations from over 14,700 proteins mapped to more than 24,300 structures from PDB. This helps users visualize the distribution of mutations and identify novel three-dimensional patterns in their distribution. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

The VIMOS Public Extragalactic Redshift Survey. Measuring the growth rate of structure around cosmic voids

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Hawken, A. J.; Granett, B. R.; Iovino, A.; Guzzo, L.; Peacock, J. A.; de la Torre, S.; Garilli, B.; Bolzonella, M.; Scodeggio, M.; Abbas, U.; Adami, C.; Bottini, D.; Cappi, A.; Cucciati, O.; Davidzon, I.; Fritz, A.; Franzetti, P.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; Polletta, M.; Pollo, A.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Arnouts, S.; Bel, J.; Branchini, E.; De Lucia, G.; Ilbert, O.; Moscardini, L.; Percival, W. J.

2017-11-01

We aim to develop a novel methodology for measuring thegrowth rate of structure around cosmic voids. We identified voids in the completed VIMOS Public Extragalactic Redshift Survey (VIPERS), using an algorithm based on searching for empty spheres. We measured the cross-correlation between the centres of voids and the complete galaxy catalogue. The cross-correlation function exhibits a clear anisotropy in both VIPERS fields (W1 and W4), which is characteristic of linear redshift space distortions. By measuring the projected cross-correlation and then de-projecting it we are able to estimate the un-distorted cross-correlation function. We propose that given a sufficiently well-measured cross-correlation function one should be able to measure the linear growth rate of structure by applying a simple linear Gaussian streaming model for the redshift space distortions (RSD). Our study of voids in 306 mock galaxy catalogues mimicking the VIPERS fields suggests that VIPERS is capable of measuring β, the ratio of the linear growth rate to the bias, with an error of around 25%. Applying our method to the VIPERS data, we find a value for the redshift space distortion parameter, β = 0.423-0.108+0.104 which, given the bias of the galaxy population we use, gives a linear growth rate of f σ8 = 0.296-0.078+0.075 at z = 0.727. These results are consistent with values observed in parallel VIPERS analyses that use standard techniques. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programs 182.A-0886 and partly 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in

Understanding how lake populations of arctic char are structured and function with special consideration of the potential effects of climate change: a multi-faceted approach.

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Budy, Phaedra; Luecke, Chris

2014-09-01

Size dimorphism in fish populations, both its causes and consequences, has been an area of considerable focus; however, uncertainty remains whether size dimorphism is dynamic or stabilizing and about the role of exogenous factors. Here, we explored patterns among empirical vital rates, population structure, abundance and trend, and predicted the effects of climate change on populations of arctic char (Salvelinus alpinus) in two lakes. Both populations cycle dramatically between dominance by small (≤300 mm) and large (>300 mm) char. Apparent survival (Φ) and specific growth rates (SGR) were relatively high (40-96%; SGR range 0.03-1.5%) and comparable to those of conspecifics at lower latitudes. Climate change scenarios mimicked observed patterns of warming and resulted in temperatures closer to optimal for char growth (15.15 °C) and a longer growing season. An increase in consumption rates (28-34%) under climate change scenarios led to much greater growth rates (23-34%). Higher growth rates predicted under climate change resulted in an even greater predicted amplitude of cycles in population structure as well as an increase in reproductive output (Ro) and decrease in generation time (Go). Collectively, these results indicate arctic char populations (not just individuals) are extremely sensitive to small changes in the number of ice-free days. We hypothesize years with a longer growing season, predicted to occur more often under climate change, produce elevated growth rates of small char and act in a manner similar to a "resource pulse," allowing a sub-set of small char to "break through," thus setting the cycle in population structure.

Role of structural inheritance on present-day deformation in intraplate domains

Science.gov (United States)

Tarayoun, A.; Mazzotti, S.; Gueydan, F.

2017-12-01

Understanding the role of structural inheritance on present day surface deformation is a key element for better characterizing the dynamism of intraplate earthquakes. Current deformation and seismicity are poorly understood phenomenon in intra-continental domains. A commonly used hypothesis, based on observations, suggests that intraplate deformation is related to the reactivation of large tectonic paleo-structures, which can act as locally weakened domains. The objective of our study is to quantify the impact of these weakened areas on present-day strain localizations and rates. We combine GPS observations and numerical modeling to analyze the role of structural inheritance on strain rates, with specific observations along the St. Lawrence Valley of eastern Canada. We processed 143 GPS stations from five different networks, in particular one dense campaign network situated along a recognized major normal faults system of the Iapetus paleo-rift, in order to accurately determine the GPS velocities and strain rates. Results of strain rates show magnitude varying from 1.5x10-10 to 6.8x10-9 yr-1 in the St Lawrence valley. Weakened area strain rates are up to one order of magnitude higher than surrounding areas. We compare strain rates inferred from GPS and the new postglacial rebound model. We found that GPS signal is one order of magnitude higher in the weakened zone, which is likely due to structural inheritance. The numerical modeling investigates the steady-state deformation of the continental lithosphere with presence of a weak area. Our new approach integrates ductile structural inheritance using a weakening coefficient that decreases the lithosphere strength at different depths. This allows studying crustal strain rates mainly as a function of rheological contrast and geometry of the weakened domains. Comparison between model predictions and observed GPS strain rates will allow us to investigate the respective role of crustal and mantle tectonic inheritance.

Growth Mechanism of Pumpkin-Shaped Vaterite Hierarchical Structures

Science.gov (United States)

Ma, Guobin; Xu, Yifei; Wang, Mu

2015-03-01

CaCO3-based biominerals possess sophisticated hierarchical structures and promising mechanical properties. Recent researches imply that vaterite may play an important role in formation of CaCO3-based biominerals. However, as a less common polymorph of CaCO3, the growth mechanism of vaterite remains not very clear. Here we report the growth of a pumpkin-shaped vaterite hierarchical structure with a six-fold symmetrical axis and lamellar microstructure. We demonstrate that the growth is controlled by supersaturation and the intrinsic crystallographic anisotropy of vaterite. For the scenario of high supersaturation, the nucleation rate is higher than the lateral extension rate, favoring the ``double-leaf'' spherulitic growth. Meanwhile, nucleation occurs preferentially in as determined by the crystalline structure of vaterite, modulating the grown products with a hexagonal symmetry. The results are beneficial for an in-depth understanding of the biomineralization of CaCO3. The growth mechanism may also be applicable to interpret the formation of similar hierarchical structures of other materials. The authors gratefully acknowledge the financial support from National Science Foundation of China (Grant Nos. 51172104 and 50972057) and National Key Basic Research Program of China (Grant No. 2010CB630705).

Measurement invariance of the Illness Intrusiveness Ratings Scale's three-factor structure in men and women with cancer.

Science.gov (United States)

Mah, Kenneth; Bezjak, Andrea; Loblaw, D Andrew; Gotowiec, Andrew; Devins, Gerald M

2011-02-01

Illness- and treatment-related disruptions to valued activities and interests (illness intrusiveness) are central to quality of life in chronic disease and are captured by three subscales of the Illness Intrusiveness Ratings Scale (IIRS): the Instrumental, Intimacy, and Relationships and Personal Development subscales. Using individual (CFA) and multisample confirmatory factor analyses (MSCFA), we evaluated measurement invariance of the IIRS's 3-factor structure in men and women with cancer. Men (n = 210) and women (n = 206) with 1 of 4 cancer diagnoses (gastrointestinal, head and neck, lymphoma, lung) recruited from outpatient clinics completed the IIRS. In the MSCFA, we applied an analysis of means and covariance structures approach to test increasingly stringent equality constraints on factor structure parameters to evaluate weak, strong, and strict measurement invariance of the 3-factor structure between men and women. Individual CFAs demonstrated fit of the hypothesized 3-factor structure for men and women, although more consistently for men. The 3-factor structure was superior to an alternative 1-factor structure. MSCFA results indicated that parameters of the 3-factor structure could be considered equivalent between the sexes up to the level of strong invariance. Strict invariance was not supported. Overall, IIRS scores can be interpreted similarly for men and women with cancer. Illness intrusiveness can be considered as important in the psychosocial adaptation of people with cancer as it is for people affected by other chronic conditions. (c) 2011 APA, all rights reserved

Contraction rate, flow modification and bed layering impact on scour at the elliptical guide banks

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Gjunsburgs, B.; Jaudzems, G.; Bizane, M.; Bulankina, V.

2017-10-01

Flow contraction by the bridge crossing structures, intakes, embankments, piers, abutments and guide banks leads to general scour and the local scour in the vicinity of the structures. Local scour is depending on flow, river bed and structures parameters and correct understanding of the impact of each parameter can reduce failure possibility of the structures. The paper explores hydraulic contraction, the discharge redistribution between channel and floodplain during the flood, local flow modification and river bed layering on depth, width and volume of scour hole near the elliptical guide banks on low-land rivers. Experiments in a flume, our method for scour calculation and computer modelling results confirm a considerable impact of the contraction rate of the flow, the discharge redistribution between channel and floodplain, the local velocity, backwater and river bed layering on the depth, width, and volume of scour hole in steady and unsteady flow, under clear water condition. With increase of the contraction rate of the flow, the discharge redistribution between channel and floodplain, the local velocity, backwater values, the scour depth increases. At the same contraction rate, but at a different Fr number, the scour depth is different: with increase in the Fr number, the local velocity, backwater, scour depth, width, and volume is increasing. Acceptance of the geometrical contraction of the flow, approach velocity and top sand layer of the river bed for scour depth calculation as accepted now, may be the reason of the structures failure and human life losses.

Use of designed sequences in protein structure recognition.

Science.gov (United States)

Kumar, Gayatri; Mudgal, Richa; Srinivasan, Narayanaswamy; Sandhya, Sankaran

2018-05-09

Knowledge of the protein structure is a pre-requisite for improved understanding of molecular function. The gap in the sequence-structure space has increased in the post-genomic era. Grouping related protein sequences into families can aid in narrowing the gap. In the Pfam database, structure description is provided for part or full-length proteins of 7726 families. For the remaining 52% of the families, information on 3-D structure is not yet available. We use the computationally designed sequences that are intermediately related to two protein domain families, which are already known to share the same fold. These strategically designed sequences enable detection of distant relationships and here, we have employed them for the purpose of structure recognition of protein families of yet unknown structure. We first measured the success rate of our approach using a dataset of protein families of known fold and achieved a success rate of 88%. Next, for 1392 families of yet unknown structure, we made structural assignments for part/full length of the proteins. Fold association for 423 domains of unknown function (DUFs) are provided as a step towards functional annotation. The results indicate that knowledge-based filling of gaps in protein sequence space is a lucrative approach for structure recognition. Such sequences assist in traversal through protein sequence space and effectively function as 'linkers', where natural linkers between distant proteins are unavailable. This article was reviewed by Oliviero Carugo, Christine Orengo and Srikrishna Subramanian.

Improved understanding of protein complex offers insight into DNA

Science.gov (United States)

Summer Science Writing Internship Improved understanding of protein complex offers insight into DNA clearer understanding of the origin recognition complex (ORC) - a protein complex that directs DNA replication - through its crystal structure offers new insight into fundamental mechanisms of DNA replication

Hydrogen/deuterium substitution methods: understanding water structure in solution

International Nuclear Information System (INIS)

Soper, A.K.

1993-01-01

The hydrogen/deuterium substitution method has been used for different applications, such as the short range order between water molecules in a number of different environments (aqueous solutions of organic molecules), or to study the partial structure factors of water at high pressure and temperature. The absolute accuracy that can be obtained remains uncertain, but important qualitative information can be obtained on the local organization of water in aqueous solution. Some recent results with pure water, methanol and dimethyl sulphoxide (DMSO) solutions are presented. It is shown that the short range water structure is not greatly affected by most solutes except at high concentrations and when the solute species has its own distinctive interaction with water (such as a dissolved small ion). 3 figs., 14 refs

Public relations and public understanding in the nuclear industry in Europe

Energy Technology Data Exchange (ETDEWEB)

Roos, E.; Michel, A. [Belgonucleaire, Brussels (Belgium)

1995-12-31

Before talking about public understanding and public relations in the nuclear industry in Europe, a word about the mosaic structure of the European energy policy and public is required because a similar structure will be found in the European public understanding policy. Afterwards, we explain what communications tools are available and how the different European countries apply them.

Factor structure of Bech's version of the Brief Psychiatric Rating Scale in Brazilian patients

Directory of Open Access Journals (Sweden)

J.A.S. Crippa

2002-10-01

Full Text Available The objective of the present study was to evaluate the factor structure of Bech's version of the Brief Psychiatric Rating Scale (BPRS, translated into Portuguese. The BPRS was administered to a heterogeneous group of psychiatric inpatients (N = 98 and outpatients (N = 62 in a University Hospital. Each patient was evaluated from one to eight times. The interval between consecutive interviews was one week for the inpatients and one month for the outpatients. The results were submitted to factorial analysis. The internal consistency of the total scale and of each factor was also estimated. Factorial analysis followed by normalized orthogonal rotation (Varimax yielded four factors: Withdrawal-Retardation, Thinking Disorder, Anxious-Depression and Activation. Internal consistency measured by Cronbach's alpha coefficient ranged from 0.766 to 0.879. The data show that the factor structure of the present instrument is similar to that of the American version of the BPRS which contains 18 items, except for the absence of the fifth factor of the latter scale, Hostile-Suspiciousness.

Large-eddy-simulation approach in understanding flow structures of 2D turbulent density currents over sloping surfaces

Science.gov (United States)

Nayamatullah, M.; Rao Pillalamarri, Narasimha; Bhaganagar, Kiran

2018-04-01

A numerical investigation was performed to understand the flow dynamics of 2D density currents over sloping surfaces. Large eddy simulation was conducted for lock-exchange (L-E) release currents and overflows. 2D Navier-Stokes equations were solved using the Boussinesq approximation. The effects of the lock aspect-ratio (height/length of lock), slope, and Reynolds number on the flow structures and turbulence mixing have been analyzed. Results have confirmed buoyancy within the head of the two-dimensional currents is not conserved which contradicts the classical thermal theory. The lock aspect-ratio dictates the fraction of initial buoyancy which is carried by the head of the current at the beginning of the slumping (horizontal) and accelerating phase (over a slope), which has important implications on turbulence kinetic energy production, and hence mixing in the current. For L-E flows over a slope, increasing slope angle enhances the turbulence production. Increasing slope results in shear reversal within the density current resulting in shear-instabilities. Differences in turbulence production mechanisms and flow structures exist between the L-E and constant-flux release currents resulting in significant differences in the flow characteristics between different releases.

Understanding the Structure-Function Relationships of Dendrimers in Environmental and Biomedical Applications

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Wang, Bo

We are living an era wherein nanoparticles (NPs) have been widely applied in our lives. Dendrimers are special polymeric NPs with unique physiochemical properties, which have been intensely explored for a variety of applications. Current studies on dendrimers are bottlenecked by insufficient understandings of their structure and dynamic behaviors from a molecular level. With primarily computational approaches supplemented by many other experimental technics, this dissertation aims to establish structure-function relationships of dendrimers in environmental and biomedical applications. More specifically, it thoroughly investigates the interactions between dendrimers and different biomolecules including carbon-based NPs, metal-based NPs, and proteins/peptides. Those results not only provide profound knowledge for evaluating the impacts of dendrimers on environmental and biological systems but also facilitate designing next-generation functional polymeric nanomaterials. The dissertation is organized as following. Chapter 1 provides an overview of current progresses on dendrimer studies, where methodology of Discrete Molecular Dynamics (DMD), my major research tool, is also introduced. Two directions of utilizing dendrimers will be discussed in following chapters. Chapter 2 will focus on environmental applications of dendrimers, where two back-to-back studies are presented. I will start from describing some interesting observations from experiments i.e. dendrimers dispersed model oil molecules. Then, I will reveal why surface chemistries of dendrimers lead to different remediation efficiencies by computational modelings. Finally, I will demonstrate different scenarios of dendrimer-small molecules association. Chapter 3 is centered on dendrimers in the biomedical applications including two subtopics. In the first topic, we will discuss dendrimers as surfactants that modulating the interactions between proteins and NPs. Some fundamental concepts regarding to NPs

Understanding social reproduction: The recursive nature of structure and agency within a science class

Science.gov (United States)

Seiler, Gale A.

Schools and science classrooms within schools continue to contribute to social reproduction and to the disenfranchisement of inner city African American students though attempts have been made to remedy the situation through standards, high-stakes testing, and compensatory programs. Such reforms ignore the sociocultural, political, and economic contexts of the individual students in the schools they are impacting. They do not take into account the uniqueness and diversity of the learners in these settings and have not included the voices of the students. Another possibility was studied here; that of starting with the cultural capital of the learner rather than with external standards. In a non-required science course at a local high school two coteachers endeavored to enact a student-emergent curriculum as a way to foster student agency and to counteract the reproductive nature of schools. The class was examined as a field within multiple other fields. The dialectical relationship between structure and agency in the class was used to frame the analysis and the tension between them was examined at several levels through video and audio analysis. Structural and rational choice views of action were abandoned in favor of an understanding hinged upon strategies of action that actors construct from cultural toolkits in and through practice. In this setting the students and teachers co-constructed a class that can be described and characterized in certain ways yet contained many counter-examples and alternative characterizations. A continuum of successes and failures, agency and subjectivity can be found in the trends and counter-trends in the course. The contradictions were examined to portray the complexity of the interactions and the possibilities for agency within them.

Effects of demographic structure on key properties of stochastic density-independent population dynamics.

Science.gov (United States)

Vindenes, Yngvild; Sæther, Bernt-Erik; Engen, Steinar

2012-12-01

The development of stochastic demography has largely been based on age structured populations, although other types of demographic structure, especially permanent and dynamic heterogeneity, are likely common in natural populations. The combination of stochasticity and demographic structure is a challenge for analyses of population dynamics and extinction risk, because the population structure will fluctuate around the stable structure and the population size shows transient fluctuations. However, by using a diffusion approximation for the total reproductive value, density-independent dynamics of structured populations can be described with only three population parameters: the expected population growth rate, the environmental variance and the demographic variance. These parameters depend on population structure via the state-specific vital rates and transition rates. Once they are found, the diffusion approximation represents a substantial reduction in model complexity. Here, we review and compare the key population parameters across a wide range of demographic structure, from the case of no structure to the most general case of dynamic heterogeneity, and for both discrete and continuous types. We focus on the demographic variance, but also show how environmental stochasticity can be included. This study brings together results from recent models, each considering a specific type of population structure, and places them in a general framework for structured populations. Comparison across different types of demographic structure reveals that the reproductive value is an essential concept for understanding how population structure affects stochastic dynamics and extinction risk. Copyright © 2011 Elsevier Inc. All rights reserved.

Realization of a passive micromixer using herringbone structure

Science.gov (United States)

Whulanza, Yudan; Utomo, Muhammad S.; Hilman, Adam

2018-02-01

Micromixing is an important research area for a variety of applications in sensing and diagnostics. In this paper, we are trying to develop an overall understanding of the process of mixing by allowing two fluid flows to flow through various asymmetrical structures. We have successfully realized and compared the performance of different passive micromixer designs based on the idea of staggered herringbone micromixer. The herringbone structure is expected to affect the flow rate. We design few microchannels using varieties on velocity, height and distance between herringbone. The layout of the structure is based on the staggered herringbone bilayers where the layer is positioned on the bottom wall of the microchannel. From simulation and experiment, it is known that the height of the channel and herringbone structure affect the flow, and the most effective height of the main channel and herringbone structure is 0.3 and 0.14 mm (2:1 ratio).

Experimental investigation of bond strength under high loading rates

Directory of Open Access Journals (Sweden)

Michal Mathias

2015-01-01

Full Text Available The structural behaviour of reinforced concrete is governed significantly by the transmission of forces between steel and concrete. The bond is of special importance for the overlapping joint and anchoring of the reinforcement, where rigid bond is required. It also plays an important role in the rotational capacity of plastic hinges, where a ductile bond behaviour is preferable. Similar to the mechanical properties of concrete and steel also the characteristics of their interaction changes with the velocity of the applied loading. For smooth steel bars with its main bond mechanisms of adhesion and friction, nearly no influence of loading rate is reported in literature. In contrast, a high rate dependence can be found for the nowadays mainly used deformed bars. For mechanical interlock, where ribs of the reinforcing steel are bracing concrete material surrounding the bar, one reason can be assumed to be in direct connection with the increase of concrete compressive strength. For splitting failure of bond, characterized by the concrete tensile strength, an even higher dynamic increase is observed. For the design of Structures exposed to blast or impact loading the knowledge of a rate dependent bond stress-slip relationship is required to consider safety and economical aspects at the same time. The bond behaviour of reinforced concrete has been investigated with different experimental methods at the University of the Bundeswehr Munich (UniBw and the Joint Research Centre (JRC in Ispra. Both static and dynamic tests have been carried out, where innovative experimental apparatuses have been used. The bond stress-slip relationship and maximum pull-out-forces for varying diameter of the bar, concrete compressive strength and loading rates have been obtained. It is expected that these experimental results will contribute to a better understanding of the rate dependent bond behaviour and will serve for calibration of numerical models.

Understanding The Process Of Strategic Change From A Structurational And Cognitive Perspective: Case Study Of The Users Of A New Technology

OpenAIRE

Slocum, Alesia

2007-01-01

How does strategic change happen, and how is it understood around technology? This ethnographic research has sought to better understand this process, from a structurational, cognitive and practice perspective. Researchers have shown that change is a continuous and ongoing process (Tsoukas and Chia, 2002; Weick and Quinn, 1999), while others have shown that change, while not determinate, can be intentional and directed to a large extent by change agents in practice (Balogun ...

Pre-service mathematics student teachers’ conceptions of nominal and effective interest rates

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Judah P. Makonye

2017-04-01

Full Text Available The general public consumes financial products such as loans that are administered in the realm of nominal and effective interest rates. It is debatable if most consumers really understand how these rates function. This article explores the conceptions that student teachers have about nominal and effective interest rates. The APOS theory illuminates analysis of students’ levels of conception. Seventy second-year mathematics students’ responses to Grade 12 tasks on effective and nominal interest rates were analysed, after which 12 students were interviewed about their mathematical thinking in solving the tasks. The findings varied. While some students could not do the tasks due to erratic use of formulae (algebra, I ascertained that some students obtained correct answers through scrupulous adherence to the external prompt of formulae. Most of those students remained stuck at the action and process stages and could not view their processes as mathematical objects. A few students had reached the object and schema stages, showing mature understanding of the relationship between nominal and effective interest rates. As most students remained at the operational stages rather than the structural, the findings accentuate that when teaching this topic, teachers ought to take their time to build learners’ schema for these notions. They need to guide their learners through the necessary action-process-object loop and refrain from introducing students to formulae too soon as this stalls their advancement to the object and schema stages which are useful in making them smart consumers of financial products.

Strain Rate and Anisotropic Microstructure Dependent Mechanical Behaviors of Silkworm Cocoon Shells.

Directory of Open Access Journals (Sweden)

Jun Xu

Full Text Available Silkworm cocoons are multi-layered composite structures comprised of high strength silk fiber and sericin, and their mechanical properties have been naturally selected to protect pupas during metamorphosis from various types of external attacks. The present study attempts to gain a comprehensive understanding of the mechanical properties of cocoon shell materials from wild silkworm species Antheraea pernyi under dynamic loading rates. Five dynamic strain rates from 0.00625 s-1 to 12.5 s-1 are tested to show the strain rate sensitivity of the cocoon shell material. In the meantime, the anisotropy of the cocoon shell is considered and the cocoon shell specimens are cut along 0°, 45° and 90° orientation to the short axis of cocoons. Typical mechanical properties including Young's modulus, yield strength, ultimate strength and ultimate strain are extracted and analyzed from the stress-strain curves. Furthermore, the fracture morphologies of the cocoon shell specimens are observed under scanning electron microscopy to help understand the relationship between the mechanical properties and the microstructures of the cocoon material. A discussion on the dynamic strain rate effect on the mechanical properties of cocoon shell material is followed by fitting our experimental results to two previous models, and the effect could be well explained. We also compare natural and dried cocoon materials for the dynamic strain rate effect and interestingly the dried cocoon shells show better overall mechanical properties. This study provides a different perspective on the mechanical properties of cocoon material as a composite material, and provides some insight for bio-inspired engineering materials.

Flow rate effect on the structure and morphology of molybdenum oxide nanoparticles deposited by atmospheric-pressure microplasma processing

International Nuclear Information System (INIS)

Bose, Arumugam Chandra; Shimizu, Yoshiki; Mariotti, Davide; Sasaki, Takeshi; Terashima, Kazuo; Koshizaki, Naoto

2006-01-01

Nanoparticles of crystalline molybdenum oxide were prepared by changing the flow rate of plasma gas (2% oxygen balanced by Ar) using an atmospheric-pressure microplasma technique. The morphology and crystalline structure of the nanoparticles were characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The FESEM results revealed that the shape of the deposited nanoparticles depended on the plasma gas flow rate. The TEM results supported the FESEM observations. The transmission electron diffraction (TED) pattern revealed that the obtained nanoparticles changed from MoO 2 to MoO 3 with the flow-rate increase, and correspondingly the nanoparticle size drastically decreased. A process mechanism is proposed from the observations of optical emission spectroscopy (OES) during the process and consumed wire surface analysis from x-ray photoelectron spectroscopy (XPS) and FESEM studies

Teaching Teaching & Understanding Understanding

DEFF Research Database (Denmark)

2006-01-01

"Teaching Teaching & Understanding Understanding" is a 19-minute award-winning short-film about teaching at university and higher-level educational institutions. It is based on the "Constructive Alignment" theory developed by Prof. John Biggs. The film delivers a foundation for understanding what...

Quality control of structural MRI images applied using FreeSurfer - a hands-on workflow to rate motion artifacts

Directory of Open Access Journals (Sweden)

Lea Luise Backhausen

2016-12-01

Full Text Available In structural magnetic resonance imaging motion artifacts are common, especially when not scanning healthy young adults. It has been shown that motion affects the analysis with automated image-processing techniques (e.g. FreeSurfer. This can bias results. Several developmental and adult studies have found reduced volume and thickness of gray matter due to motion artifacts. Thus, quality control is necessary in order to ensure an acceptable level of quality and to define exclusion criteria of images (i.e. determine participants with most severe artifacts. However, information about the quality control workflow and image exclusion procedure is largely lacking in the current literature and the existing rating systems differ. Here we propose a stringent workflow of quality control steps during and after acquisition of T1-weighted images, which enables researchers dealing with populations that are typically affected by motion artifacts to enhance data quality and maximize sample sizes. As an underlying aim we established a thorough quality control rating system for T1-weighted images and applied it to the analysis of developmental clinical data using the automated processing pipeline FreeSurfer. This hands-on workflow and quality control rating system will aid researchers in minimizing motion artifacts in the final data set, and therefore enhance the quality of structural magnetic resonance imaging studies.

Fusing Multiple Satellite Datasets Toward Defining and Understanding Organized Convection

Science.gov (United States)

Elsaesser, G.; Del Genio, A. D.

2017-12-01

How do we differentiate unorganized from organized convection? We might think of organized convection as being long lasting (at least longer than the lifetime of any individual cumulus cell), clustered at larger spatial scales (>100 km), and responsible for substantial rainfall accumulation. Organized convection is sustained on such scales due to the arrangement of moist/dry and buoyant/non-buoyant mesoscale circulations. The nature of these circulations is tied to system diabatic heating profiles; in particular, the 2nd baroclinic (top-heavy), stratiform heating mode is thought to be important for organized convection maintenance/propagation. We investigate the extent to which these characteristics are jointly found in propagating convective systems. Lifecycle information comes from hi-res IR data. Diabatic heating profiles, convective fractions and rainfall are provided by GPM retrievals mapped to convective system tracks. Moisture is provided by AIRS/AMSU and passive microwave retrievals. Instead of compositing heating profile information along a system track, where information is smoothed out, we sort system heating profile structures according to their "top heaviness" and then analyze PDFs of system rainfall, system sizes, durations, convective/stratiform ratios, etc. as a function of diabatic heating structure. Perhaps contrary to expectation, we find only small differences in PDFs of rainfall rates, system sizes, and system duration for different heating profile structures. If organization is defined according to heating structures, then one possible interpretation of these results is that organization is independent of system size, duration, and many times, even lifecycle stage. Is it possible that most systems "hobble" along and exhibit varying degrees of organization, dependent on local environment moisture/buoyancy variations, unlike the archetypical MCS paradigm? This presentation will also discuss the questions posed above within the context of

Structure-Activity Relationships for Rates of Aromatic Amine Oxidation by Manganese Dioxide

International Nuclear Information System (INIS)

Salter-Blanc, Alexandra J.; Lyon, Molly A.; Science University, Portland, OR; Ness, Stuart C.; Science University, Portland, OR; Tratnyek, Paul G.; Science University, Portland, OR

2016-01-01

New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO 2 ) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. Here in this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammett σ constants (σ − ), pK a s of the amines, and energies of the highest occupied molecular orbital (E HOMO )] to specific for the likely rate-limiting step [one-electron oxidation potentials (E ox )]. The selection of calculated descriptors (pK a ), E HOMO , and E ox ) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO 2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to E HOMO (calculated with a modest level of theory).

Booth Revisited: Identifying the Determinants of Capital Structure in the Sugar Sector

Directory of Open Access Journals (Sweden)

A.A. Kanwar

2007-07-01

Full Text Available The study assesses whether selected exogenous variables: tax rate, size, asset tangibility, volatility and profitability, affect capital structure in a significant manner in the sugar industry. It suggests that decision on capital structuring is found to be weakly affected by the variables chosen in our study. This is also consistent with the results of Booth et al (2001 where modern financial theory is found to be weakly portable across a group of developed and developing countries. It is recommended that more empirical work is done in order to understand the impact of capital structure choices.

Understanding how lake populations of arctic char are structured and function with special consideration of the potential effects of climate change: A multi-faceted approach.

Science.gov (United States)

Budy, Phaedra; Luecke, Chris

2014-01-01

Size dimorphism in fish populations, both its causes and consequences, has been an area of considerable focus; however, uncertainty remains whether size dimorphism is dynamic or stabilizing and about the role of exogenous factors. Here, we explored patterns among empirical vital rates, population structure, abundance and trend, and predicted the effects of climate change on populations of arctic char (Salvelinus alpinus) in two lakes. Both populations cycle dramatically between dominance by small (≤300 mm) and large (>300 mm) char. Apparent survival (Φ) and specific growth rates (SGR) were relatively high (40–96 %; SGR range 0.03–1.5 %) and comparable to those of conspecifics at lower latitudes. Climate change scenarios mimicked observed patterns of warming and resulted in temperatures closer to optimal for char growth (15.15 °C) and a longer growing season. An increase in consumption rates (28–34 %) under climate change scenarios led to much greater growth rates (23–34 %). Higher growth rates predicted under climate change resulted in an even greater predicted amplitude of cycles in population structure as well as an increase in reproductive output (Ro) and decrease in generation time (Go). Collectively, these results indicate arctic char populations (not just individuals) are extremely sensitive to small changes in the number of ice-free days. We hypothesize years with a longer growing season, predicted to occur more often under climate change, produce elevated growth rates of small char and act in a manner similar to a “resource pulse,” allowing a sub-set of small char to “break through,” thus setting the cycle in population structure.

Optimizing the data acquisition rate for a remotely controllable structural monitoring system with parallel operation and self-adaptive sampling

International Nuclear Information System (INIS)

Sheng, Wenjuan; Guo, Aihuang; Liu, Yang; Azmi, Asrul Izam; Peng, Gang-Ding

2011-01-01

We present a novel technique that optimizes the real-time remote monitoring and control of dispersed civil infrastructures. The monitoring system is based on fiber Bragg gating (FBG) sensors, and transfers data via Ethernet. This technique combines parallel operation and self-adaptive sampling to increase the data acquisition rate in remote controllable structural monitoring systems. The compact parallel operation mode is highly efficient at achieving the highest possible data acquisition rate for the FBG sensor based local data acquisition system. Self-adaptive sampling is introduced to continuously coordinate local acquisition and remote control for data acquisition rate optimization. Key issues which impact the operation of the whole system, such as the real-time data acquisition rate, data processing capability, and buffer usage, are investigated. The results show that, by introducing parallel operation and self-adaptive sampling, the data acquisition rate can be increased by several times without affecting the system operating performance on both local data acquisition and remote process control

Capping layer growth rate and the optical and structural properties of GaAsSbN-capped InAs/GaAs quantum dots

Energy Technology Data Exchange (ETDEWEB)

Ulloa, J. M., E-mail: jmulloa@isom.upm.es; Utrilla, A. D.; Guzman, A.; Hierro, A. [Institute for Systems based on Optoelectronics and Microtechnology (ISOM) and Dpto. Ingeniería Electrónica, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Reyes, D. F.; Ben, T.; González, D. [Departamento de Ciencia de los Materiales e IM y QI, Universidad de Cádiz, 11510 Puerto Real (Cádiz) (Spain)

2014-10-07

Changing the growth rate during the heteroepitaxial capping of InAs/GaAs quantum dots (QDs) with a 5 nm-thick GaAsSbN capping layer (CL) strongly modifies the QD structural and optical properties. A size and shape transition from taller pyramids to flatter lens-shaped QDs is observed when the CL growth rate is decreased from 1.5 to 0.5 ML/s. This indicates that the QD dissolution processes taking place during capping can be controlled to some extent by the GaAsSbN CL growth rate, with high growth rates allowing a complete preservation of the QDs. However, the dissolution processes are shown to have a leveling effect on the QD height, giving rise to a narrower size distribution for lower growth rates. Contrary to what could be expected, these effects are opposite to the strong blue-shift and improvement of the photoluminescence (PL) observed for higher growth rates. Nevertheless, the PL results can be understood in terms of the strong impact of the growth rate on the Sb and N incorporation into the CL, which results in lower Sb and N contents at higher growth rates. Besides the QD-CL band offsets and QD strain, the different CL composition alters the band alignment of the system, which can be transformed to type-II at low growth rates. These results show the key role of the alloyed CL growth parameters on the resulting QD properties and demonstrate an intricate correlation between the PL spectra and the sample morphology in complex QD-CL structures.

Modeling the time--varying subjective quality of HTTP video streams with rate adaptations.

Science.gov (United States)

Chen, Chao; Choi, Lark Kwon; de Veciana, Gustavo; Caramanis, Constantine; Heath, Robert W; Bovik, Alan C

2014-05-01

Newly developed hypertext transfer protocol (HTTP)-based video streaming technologies enable flexible rate-adaptation under varying channel conditions. Accurately predicting the users' quality of experience (QoE) for rate-adaptive HTTP video streams is thus critical to achieve efficiency. An important aspect of understanding and modeling QoE is predicting the up-to-the-moment subjective quality of a video as it is played, which is difficult due to hysteresis effects and nonlinearities in human behavioral responses. This paper presents a Hammerstein-Wiener model for predicting the time-varying subjective quality (TVSQ) of rate-adaptive videos. To collect data for model parameterization and validation, a database of longer duration videos with time-varying distortions was built and the TVSQs of the videos were measured in a large-scale subjective study. The proposed method is able to reliably predict the TVSQ of rate adaptive videos. Since the Hammerstein-Wiener model has a very simple structure, the proposed method is suitable for online TVSQ prediction in HTTP-based streaming.

Understanding of electrochemical and structural changes of polypyrrole/polyethylene glycol composite films in aqueous solution

International Nuclear Information System (INIS)

Pirvu, Cristian; Manole, Claudiu Constantin; Stoian, Andrei Bogdan; Demetrescu, Ioana

2011-01-01

Highlights: → Electrochemical monitoring of PPy and PPy-PEG films over immersion time. → Electrochemical and surface analysis showed that PEG improves the stability of PPy films. → Mott-Schottky analysis reveals p-type conductance for both films. → In situ AFM analysis sustains electrochemical behaviour. → A model of PPy and PPy-PEG films behaviour during immersion was elaborated. - Abstract: Electrochemical monitoring of electrical and structural changes of both PPy and PPy-PEG films electrochemical deposited, in order to highlight if the structural stability offered by PEG has an influence on electrical properties and stability in aqueous solution over immersion time was investigated. Electrochemical analysis suggests that PPy-PEG film inserts cations easier than PPy film for a short immersion time probably due to ability of PEG to form complexes with metal cations. The FTIR spectra showed that the PEG incorporation decreases the rate of PPy overoxidation probably by restraining the electron release and by rendering O 2 inaccessible to PPy. Mott-Schottky analysis based on capacitance measurement reveal p-type conductance for both films. The in situ AFM analysis sustains electrochemical behaviour and has permitted elaboration of a model of PPy and PPy-PEG films behaviour during immersion in testing solution.

Patient comprehension of emergency department care and instructions: are patients aware of when they do not understand?

Science.gov (United States)

Engel, Kirsten G; Heisler, Michele; Smith, Dylan M; Robinson, Claire H; Forman, Jane H; Ubel, Peter A

2009-04-01

To be able to adhere to discharge instructions after a visit to the emergency department (ED), patients should understand both the care that they received and their discharge instructions. The objective of this study is to assess, at discharge, patients' comprehension of their ED care and instructions and their awareness of deficiencies in their comprehension. We conducted structured interviews of 140 adult English-speaking patients or their primary caregivers after ED discharge in 2 health systems. Participants rated their subjective understanding of 4 domains: (1) diagnosis and cause; (2) ED care; (3) post-ED care, and (4) return instructions. We assessed patient comprehension as the degree of agreement (concordance) between patients' recall of each of these domains and information obtained from chart review. Two authors scored each case independently and discussed discrepancies before providing a final concordance rating (no concordance, minimal concordance, partial concordance, near concordance, complete concordance). Seventy-eight percent of patients demonstrated deficient comprehension (less than complete concordance) in at least 1 domain; 51% of patients, in 2 or more domains. Greater than a third of these deficiencies (34%) involved patients' understanding of post-ED care, whereas only 15% were for diagnosis and cause. The majority of patients with comprehension deficits failed to perceive them. Patients perceived difficulty with comprehension only 20% of the time when they demonstrated deficient comprehension. Many patients do not understand their ED care or their discharge instructions. Moreover, most patients appear to be unaware of their lack of understanding and report inappropriate confidence in their comprehension and recall.

Understanding effects of chemical structure on azo dye decolorization characteristics by Aeromonas hydrophila

Energy Technology Data Exchange (ETDEWEB)

Hsueh, Chung-Chuan [Department of Chemical and Materials Engineering, National I-Lan University, I-Lan 260, Taiwan (China); Chen, Bor-Yann, E-mail: bychen@niu.edu.tw [Department of Chemical and Materials Engineering, National I-Lan University, I-Lan 260, Taiwan (China); Yen, Chia-Yi [Department of Chemical and Materials Engineering, National I-Lan University, I-Lan 260, Taiwan (China)

2009-08-15

This novel comparative study tended to disclose how the molecular structures present in seven azo dyes including two types of azo dyes (i.e., naphthol type azo dyes - Reactive Black 5 (RB 5), Reactive Blue 171 (RB 171), Reactive Green 19 (RG19), Reactive Red 198 (RR198), Reactive Red 141 (RR141) and non-naphthol type azo dyes - Direct Yellow 86 (DY86), Reactive Yellow 84 (RY84)) affected color removal capability of Aeromonas hydrophila. Generally speaking, the decolorization rate of naphthol type azo dye with hydroxyl group at ortho to azo bond was faster than that of non-naphthol type azo dye without hydroxyl group, except of RG19. The azo dyes with electron-withdrawing groups (e.g., sulfo group in RR198, RB5 and RR141) would be easier to be decolorized than the azo dyes with the electron-releasing groups (e.g., -NH-triazine in RB171 and RG19). In addition, the azo dyes containing more electron-withdrawing groups (e.g., RR198, RB5 and RR141) showed significantly faster rate of decolorization. The azo dyes with electron-withdrawing groups (e.g., sulfo group) at para and ortho to azo bond (e.g., RR198, RB5 and RR141) could be more preferred for color removal than those at meta (e.g., DY86 and RY84). The former azo dyes with para and ortho sulfo group provided more effective resonance effects to withdraw electrons from azo bond, causing azo dyes to be highly electrophilic for faster rates of reductive biodecolorization. However, since the ortho substituent caused steric hindrance near azo linkage(s), azo dyes with para substituent could be more favorable (e.g., SO{sub 2}(CH{sub 2}){sub 2}SO{sub 4}{sup -} in RR198 and RB5) than those with ortho substituent (e.g., sulfo group at RR141) for decolorization. Thus, the ranking of the position for the electron-withdrawing substituent in azo dyes to escalate decolorization was para > ortho > meta. This study suggested that both the positions of substituents on the aromatic ring and the electronic characteristics of

Understanding leader representations: Beyond implicit leadership theory

OpenAIRE

Knee, Robert Everett

2006-01-01

The purpose of the present study was to establish evidence for the suggested integration of the theories of connectionism and leadership. Recent theoretical writings in the field of leadership have suggested that the dynamic representations generated by the connectionist perspective is an appropriate approach to understanding how we perceive leaders. Similarly, implicit leadership theory (ILT) explains that our cognitive understandings of leaders are based on a cognitive structure that we u...

Actinides and environmental interfaces: striving for molecular-level understanding

International Nuclear Information System (INIS)

Heino Nitsche

2005-01-01

Actinides can undergo a variety of complex chemical reactions in the environment. In addition to the formation of solid precipitates, colloids and dissolved solution species common to aqueous systems, actinide ions can interact with the surrounding geo and biomedia to change oxidation states or sorb on surfaces and colloids. The rate of migration is determined by aqueous solubility, and interactions with solid surfaces such as minerals, soils, natural organic matter, and soil microorganisms Sorption of aqueous actinide species on biological and geological matrices can be quantitatively described by a surface complexation or site-binding model. The disadvantage of this model is the difficulty in the experimental determination of the model parameters and surface reaction constants. Usually, a set of surface reactions and species are proposed based on knowledge of the solution speciation of the solute, and the reaction constants are usually derived by fitting computer-calculated absorption curves to experimental data. Because this process typically involves a large number of potentially adjustable parameters, it is likely to lead to non-unique parameter fitting and does not always result in a consistent set of parameters for the same systems. A fundamental molecular-level understanding of sorption processes of actinides on environmental surfaces is required to better understand and predict their transport behavior in nature. Several different surface spectroscopic techniques have been applied to the characterization of the adsorbed species and surface reactions and a direct determination of the sorbed species and surface reactions has become possible. The non-linear optical techniques of second harmonic and sum frequency generation (SHG and SFG) are ideally suited to study surfaces and interfaces of mineral oxides, biosurfactants and biopolymers, organic adlayers adsorbed on solid/mineral surfaces and soil organic matter, including humic and fulvic acids. Resonant

Measurement and Structural Invariance of Parent Ratings of ADHD and ODD Symptoms across Gender for American and Malaysian Children

Science.gov (United States)

Burns, G. Leonard; Walsh, James A.; Gomez, Rapson; Hafetz, Nina

2006-01-01

The purpose of this study was to examine the measurement (configural, metric, scalar, and residual) and structural (factor variance, factor covariance, and factor means) invariance of parent ratings of the attention-deficit/hyperactivity disorder-inattention (ADHD-IN), ADHD-hyperactivity/impulsivity (ADHD-HI), and oppositional defiant disorder…

Oil prices, inflation and interest rates in a structural cointegrated VAR model for the G-7 countries

International Nuclear Information System (INIS)

Cologni, Alessandro; Manera, Matteo

2008-01-01

Sharp increases in the price of oil are generally seen as a major contributor to business cycle asymmetries. Moreover, the very recent highs registered in the world oil market are causing concern about possible slowdowns in the economic performance of the most developed countries. In this paper a structural cointegrated VAR model has been considered for the G-7 countries in order to study the direct effects of oil price shocks on output and prices, and the reaction of monetary variables to external shocks. Our results can be summarized as follows: i) a stationary money demand, as suggested by the classic theory of money, can be identified for most countries; ii) according to the estimated coefficients of the structural part of the model, for all countries except Japan and U.K. the null hypothesis of an influence of oil prices on the inflation rate cannot be rejected. Inflation rate shocks are transmitted to the real economy by increasing interest rates; iii) impulse response analysis suggests, for most countries, the existence of an instantaneous, temporary effect of oil price innovations on prices; iv) impulse response functions indicate different monetary policy reactions to inflationary and growth shocks; v) the simulation exercises directed to estimate the total impact of the 1990 oil price shock indicate that for some countries (U.S.) a significant part of the effects of the oil price shock is due to the monetary policy reaction function. For other countries (Canada, France and Italy), however, the total impact is offset, at least in part, by an easing of monetary conditions. (author)

Understanding Large-scale Structure in the SSA22 Protocluster Region Using Cosmological Simulations

Science.gov (United States)

Topping, Michael W.; Shapley, Alice E.; Steidel, Charles C.; Naoz, Smadar; Primack, Joel R.

2018-01-01

We investigate the nature and evolution of large-scale structure within the SSA22 protocluster region at z = 3.09 using cosmological simulations. A redshift histogram constructed from current spectroscopic observations of the SSA22 protocluster reveals two separate peaks at z = 3.065 (blue) and z = 3.095 (red). Based on these data, we report updated overdensity and mass calculations for the SSA22 protocluster. We find {δ }b,{gal}=4.8+/- 1.8 and {δ }r,{gal}=9.5+/- 2.0 for the blue and red peaks, respectively, and {δ }t,{gal}=7.6+/- 1.4 for the entire region. These overdensities correspond to masses of {M}b=(0.76+/- 0.17)× {10}15{h}-1 {M}ȯ , {M}r=(2.15+/- 0.32)× {10}15{h}-1 {M}ȯ , and {M}t=(3.19+/- 0.40)× {10}15{h}-1 {M}ȯ for the red, blue, and total peaks, respectively. We use the Small MultiDark Planck (SMDPL) simulation to identify comparably massive z∼ 3 protoclusters, and uncover the underlying structure and ultimate fate of the SSA22 protocluster. For this analysis, we construct mock redshift histograms for each simulated z∼ 3 protocluster, quantitatively comparing them with the observed SSA22 data. We find that the observed double-peaked structure in the SSA22 redshift histogram corresponds not to a single coalescing cluster, but rather the proximity of a ∼ {10}15{h}-1 {M}ȯ protocluster and at least one > {10}14{h}-1 {M}ȯ cluster progenitor. Such associations in the SMDPL simulation are easily understood within the framework of hierarchical clustering of dark matter halos. We finally find that the opportunity to observe such a phenomenon is incredibly rare, with an occurrence rate of 7.4{h}3 {{{Gpc}}}-3. Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W.M. Keck Foundation.

The Effects of Flattening the Effective Marginal Rate Structure in Australia: Policy Simulations Using the Melbourne Institute Tax and Transfer Simulator

OpenAIRE

John Creedy; Guyonne Kalb; Hsein Kew

2001-01-01

This paper uses the Melbourne Institute Tax and Transfer Simulator (MITTS) to examine the effects of a reduction in the means-tested benefit taper, or withdrawal, rates in Australia to 30 per cent. That is, all taper rates of 50 per cent and 70 per cent in the 1998 system are reduced to 30 per cent, while leaving all basic benefit levels unchanged. This change is therefore expected to ‘flatten’ the tax structure by reducing the high marginal tax rates applying to those with relatively low inc...

Electric rate operations

International Nuclear Information System (INIS)

Maillard, D.

1993-01-01

The share of nuclear power in EDF production implies multiple rate structures. How are these rates determined. What are the new applications of electricity, and in particular those that make use of the especially low summer prices for electricity. These are topics of interest to the man in the street (witness EDF's recent 'red-white-blue' rates). This prompted the 'Nuclear Power in the Financial, Energy and Economic situation' department of France's nuclear power company to organize a conference bringing together an expert on rates - M.P. Bernard, head of the rate fixing service at the EDF's headquarters - and representatives from suppliers of equipment taking advantage of the various EDF rate options

Some structural aspects of language are more stable than others: a comparison of seven methods.

Directory of Open Access Journals (Sweden)

Dan Dediu

Full Text Available Understanding the patterns and causes of differential structural stability is an area of major interest for the study of language change and evolution. It is still debated whether structural features have intrinsic stabilities across language families and geographic areas, or if the processes governing their rate of change are completely dependent upon the specific context of a given language or language family. We conducted an extensive literature review and selected seven different approaches to conceptualising and estimating the stability of structural linguistic features, aiming at comparing them using the same dataset, the World Atlas of Language Structures. We found that, despite profound conceptual and empirical differences between these methods, they tend to agree in classifying some structural linguistic features as being more stable than others. This suggests that there are intrinsic properties of such structural features influencing their stability across methods, language families and geographic areas. This finding is a major step towards understanding the nature of structural linguistic features and their interaction with idiosyncratic, lineage- and area-specific factors during language change and evolution.

Understanding Structures and Affordances of Extended Teams in Global Software Development

DEFF Research Database (Denmark)

Ali Babar, Muhammad; Zahedi, Mansooreh

2013-01-01

Growing popularity of Global Software Development (GSD) has resulted in an increasing number of cross-organizational teams that are formed according to Extended Team Model (ETM). There is little known about the structures (work, social, and communication) that may exist in ETM and what affordances...... in the studied team help deal with different GSD challenges, these structures appear to have certain challenges inherent in them and the affordances they provide. We make a few recommendations for improving the current structures to deal with the observed challenges. Our findings are expected to provide insights...

Understanding Kelvin-Helmholtz instability in paraffin-based hybrid rocket fuels

Science.gov (United States)

Petrarolo, Anna; Kobald, Mario; Schlechtriem, Stefan

2018-04-01

Liquefying fuels show higher regression rates than the classical polymeric ones. They are able to form, along their burning surface, a low viscosity and surface tension liquid layer, which can become unstable (Kelvin-Helmholtz instability) due to the high velocity gas flow in the fuel port. This causes entrainment of liquid droplets from the fuel surface into the oxidizer gas flow. To better understand the droplets entrainment mechanism, optical investigations on the combustion behaviour of paraffin-based hybrid rocket fuels in combination with gaseous oxygen have been conducted in the framework of this research. Combustion tests were performed in a 2D single-slab burner at atmospheric conditions. High speed videos were recorded and analysed with two decomposition techniques. Proper orthogonal decomposition (POD) and independent component analysis (ICA) were applied to the scalar field of the flame luminosity. The most excited frequencies and wavelengths of the wave-like structures characterizing the liquid melt layer were computed. The fuel slab viscosity and the oxidizer mass flow were varied to study their influence on the liquid layer instability process. The combustion is dominated by periodic, wave-like structures for all the analysed fuels. Frequencies and wavelengths characterizing the liquid melt layer depend on the fuel viscosity and oxidizer mass flow. Moreover, for very low mass flows, no wavelength peaks are detected for the higher viscosity fuels. This is important to better understand and predict the onset and development of the entrainment process, which is connected to the amplification of the longitudinal waves.

How loan interest rate liberalization affects firms'loan maturity structure Evidence from listed manufacturing companies in China

Institute of Scientific and Technical Information of China (English)

Jianfang Zhou; Jingjing Wang; Jianping Ding

2014-01-01

Purpose-After loan interest rate upper limit deregulation in October 2004,the financing environment in China changed dramatically,and the banks were eligible for risk compensation.The purpose of this paper is to focus on the influence of the loan interest rate librealization on firms' loan maturity structure.Design/methodology/approach-Based on Rajan's (1992) model the authors constructed a tradeoff model of how the banks choose long-term and short-term loans scales,and further analyzed banks' loan term decisions under the loan interest rate upper limit deregulation or collateral cases.Then the authors used an unbalanced panel data set of 586 Chinese listed manufacturing companies and 9,376 observations during the period 1996-2011 to testify the theoretical conclusion.Furthermore,the authors studied the effect on firms with different characteristics of ownership or scale.Findings-The results show that the loan interest rate liberalization significantly decreases the private companies' reliance on short-term loans and increases sensitivity to interest rates of stateowned companies' long-term loans.But the results also show that the companies' ownership still plays a key role on the long-term loans availability.When monetary policy tightened,small companies still have to borrow short-term loans for long-term purposes.As the bank industry is still dominated by state-owned banks and the deposit interest rate has upper limits,the effect of the loan interest rate liberalization on easing long-term credit constraints is limited.Originality/value-From a new perspective,the content and findings of this paper contribute to the study of the effect of the interest rate liberalization on China economy.

Does the structure of wood contribute to understanding the oaks decline phenomenon?

Directory of Open Access Journals (Sweden)

Mirela Tulik

2014-04-01

Full Text Available Vascular cambium is a meristematic tissue which produces wood centriphugaly and phloem centripetaly. In the structure of wood and phloem, data concerning developmental processes taking place in the cambium is recorded. The history of the cambium is encoded in the dimensions, numbers and arrangements of the wood and phloem cells. For investigations, the wood is usually preferred because it is durable and such data could remain unchanged for centuries, whereas in the phloem due to distorted processes, it deranges after a few years. In broadleaves, the wood is composed of vessels, tracheids, fibers and parenchyma cells. The process of the wood formation consists of the cambial cell derivatives expansion, lignification of its walls and programmed cell death. Since the seventies of the nineteenth century, the process of declining oaks taking place in Europe on a regular basis has been observed. Oak decline is a complex process that involves interactions of both biotic and abiotic factors leading to increased trees mortality. The main goal of the studies is the examination of the structure of wood in declining oaks (Quercus robur L. in respect to physiological (conductive role of this tissue. It is known that on the level of the wood structure, water transport efficiency depends on the diameter of vessels - the main elements of the hydraulic conductivity system. Any reduction of the vessels lumen causes the reduction of the water transport to the organs of the trees body and, therefore, influences organisms survival rate. Anatomical analyses were carried out on wood samples (comprising all annual rings formed during the 30-40 years life of the analyzed trees collected at breast height from the main stem of healthy, weakened and dead oaks. The anatomical traits of the wood like as the width of the annual increments, the diameter and density of early wood vessels were measured. The results which are described in the paper by Tulik (2014 revealed that

Understanding nucleon structure using lattice simulations. Recent progress on three different structural observables

International Nuclear Information System (INIS)

Schroers, W.

2007-01-01

This review focuses on the discussion of three key results of nucleon structure calculations on the lattice. These three results are the quark contribution to the nucleon spin, J q , the nucleon-Δ transition form factors, and the nucleon axial coupling, g A . The importance for phenomenology and experiment is discussed and the requirements for future simulations are pointed out. (orig.)

Neural network signal understanding for instrumentation

DEFF Research Database (Denmark)

Pau, L. F.; Johansen, F. S.

1990-01-01

understanding research is surveyed, and the selected implementation and its performance in terms of correct classification rates and robustness to noise are described. Formal results on neural net training time and sensitivity to weights are given. A theory for neural control using functional link nets is given...

Elemental redistribution behavior in tellurite glass induced by high repetition rate femtosecond laser irradiation

International Nuclear Information System (INIS)

Teng, Yu; Zhou, Jiajia; Khisro, Said Nasir; Zhou, Shifeng; Qiu, Jianrong

2014-01-01

Highlights: • Abnormal elements redistribution behavior was observed in tellurite glass. • The refractive index and Raman intensity distribution changed significantly. • The relative glass composition remained unchanged while the glass density changed. • First time report on the abnormal element redistribution behavior in glass. • The glass network structure determines the elemental redistribution behavior. - Abstract: The success in the fabrication of micro-structures in glassy materials using femtosecond laser irradiation has proved its potential applications in the construction of three-dimensional micro-optical components or devices. In this paper, we report the elemental redistribution behavior in tellurite glass after the irradiation of high repetition rate femtosecond laser pulses. The relative glass composition remained unchanged while the glass density changed significantly, which is quite different from previously reported results about the high repetition rate femtosecond laser induced elemental redistribution in silicate glasses. The involved mechanism is discussed with the conclusion that the glass network structure plays the key role to determine the elemental redistribution. This observation not only helps to understand the interaction process of femtosecond laser with glassy materials, but also has potential applications in the fabrication of micro-optical devices

Estimating the effects of 17α-ethinylestradiol on stochastic population growth rate of fathead minnows: a population synthesis of empirically derived vital rates

Science.gov (United States)

Schwindt, Adam R.; Winkelman, Dana L.

2016-01-01

Urban freshwater streams in arid climates are wastewater effluent dominated ecosystems particularly impacted by bioactive chemicals including steroid estrogens that disrupt vertebrate reproduction. However, more understanding of the population and ecological consequences of exposure to wastewater effluent is needed. We used empirically derived vital rate estimates from a mesocosm study to develop a stochastic stage-structured population model and evaluated the effect of 17α-ethinylestradiol (EE2), the estrogen in human contraceptive pills, on fathead minnow Pimephales promelas stochastic population growth rate. Tested EE2 concentrations ranged from 3.2 to 10.9 ng L−1 and produced stochastic population growth rates (λ S ) below 1 at the lowest concentration, indicating potential for population decline. Declines in λ S compared to controls were evident in treatments that were lethal to adult males despite statistically insignificant effects on egg production and juvenile recruitment. In fact, results indicated that λ S was most sensitive to the survival of juveniles and female egg production. More broadly, our results document that population model results may differ even when empirically derived estimates of vital rates are similar among experimental treatments, and demonstrate how population models integrate and project the effects of stressors throughout the life cycle. Thus, stochastic population models can more effectively evaluate the ecological consequences of experimentally derived vital rates.

Understanding human DNA sequence variation.

Science.gov (United States)

Kidd, K K; Pakstis, A J; Speed, W C; Kidd, J R

2004-01-01

Over the past century researchers have identified normal genetic variation and studied that variation in diverse human populations to determine the amounts and distributions of that variation. That information is being used to develop an understanding of the demographic histories of the different populations and the species as a whole, among other studies. With the advent of DNA-based markers in the last quarter century, these studies have accelerated. One of the challenges for the next century is to understand that variation. One component of that understanding will be population genetics. We present here examples of many of the ways these new data can be analyzed from a population perspective using results from our laboratory on multiple individual DNA-based polymorphisms, many clustered in haplotypes, studied in multiple populations representing all major geographic regions of the world. These data support an "out of Africa" hypothesis for human dispersal around the world and begin to refine the understanding of population structures and genetic relationships. We are also developing baseline information against which we can compare findings at different loci to aid in the identification of loci subject, now and in the past, to selection (directional or balancing). We do not yet have a comprehensive understanding of the extensive variation in the human genome, but some of that understanding is coming from population genetics.

Structural optimization of Au–Pd bimetallic nanoparticles with improved particle swarm optimization method