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Sample records for understanding structural effects

  1. Physical models have gender-specific effects on student understanding of protein structure-function relationships.

    Science.gov (United States)

    Forbes-Lorman, Robin M; Harris, Michelle A; Chang, Wesley S; Dent, Erik W; Nordheim, Erik V; Franzen, Margaret A

    2016-07-08

    Understanding how basic structural units influence function is identified as a foundational/core concept for undergraduate biological and biochemical literacy. It is essential for students to understand this concept at all size scales, but it is often more difficult for students to understand structure-function relationships at the molecular level, which they cannot as effectively visualize. Students need to develop accurate, 3-dimensional mental models of biomolecules to understand how biomolecular structure affects cellular functions at the molecular level, yet most traditional curricular tools such as textbooks include only 2-dimensional representations. We used a controlled, backward design approach to investigate how hand-held physical molecular model use affected students' ability to logically predict structure-function relationships. Brief (one class period) physical model use increased quiz score for females, whereas there was no significant increase in score for males using physical models. Females also self-reported higher learning gains in their understanding of context-specific protein function. Gender differences in spatial visualization may explain the gender-specific benefits of physical model use observed. © 2016 The Authors Biochemistry and Molecular Biology Education published by Wiley Periodicals, Inc. on behalf of International Union of Biochemistry and Molecular Biology, 44(4):326-335, 2016. © 2016 The International Union of Biochemistry and Molecular Biology.

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

    Directory of Open Access Journals (Sweden)

    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.

  3. 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.

  4. 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

  5. The Effect of Three-Dimensional Simulations on the Understanding of Chemical Structures and Their Properties

    Science.gov (United States)

    Urhahne, Detlef; Nick, Sabine; Schanze, Sascha

    2009-08-01

    In a series of three experimental studies, the effectiveness of three-dimensional computer simulations to aid the understanding of chemical structures and their properties was investigated. Arguments for the usefulness of three-dimensional simulations were derived from Mayer’s generative theory of multimedia learning. Simulations might lead to a decrease in cognitive load and thus support active learning. In our studies, the learning effectiveness of three-dimensional simulations was compared to two-dimensional illustrations by use of different versions of a computer programme concerning the modifications of carbon. The first and third study with freshman students of chemistry and biochemistry show that no more knowledge was acquired when participants learnt with three-dimensional simulations than with two-dimensional figures. In the second study with 16-year old secondary school students, use of simulations facilitated the acquisition of conceptual knowledge. It was concluded that three-dimensional simulations are more effective for younger students who lack the experience of learning with different visual representation formats in chemistry. In all three studies, a significant relationship between spatial ability and conceptual knowledge about the modifications of carbon was detected.

  6. Understanding the proton radius puzzle: Nuclear structure effects in light muonic atoms

    Directory of Open Access Journals (Sweden)

    Ji Chen

    2016-01-01

    Full Text Available We present calculations of nuclear structure effects to the Lamb shift in light muonic atoms. We adopt a modern ab-initio approach by combining state-of-the-art nuclear potentials with the hyperspherical harmonics method. Our calculations are instrumental to the determination of nuclear charge radii in the Lamb shift measurements, which will shed light on the proton radius puzzle.

  7. 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

  8. Understanding the effect of secondary structure on molecular interactions of poly-L-lysine with different substrates by SFA.

    Science.gov (United States)

    Binazadeh, Mojtaba; Faghihnejad, Ali; Unsworth, Larry D; Zeng, Hongbo

    2013-10-14

    Nonspecific adsorption of proteins on biomaterial surfaces challenges the widespread application of engineered materials, and understanding the impact of secondary structure of proteins and peptides on their adsorption process is of both fundamental and practical importance in bioengineering. In this work, poly-L-lysine (PLL)-based α-helices and β-sheets were chosen as a model system to investigate the effect of secondary structure on peptide interactions with substrates of various surface chemistries. Circular dichroism (CD) was used to confirm the presence of both α-helix and β-sheet structured PLL in aqueous solutions and upon adsorption to quartz, where these secondary structures seemed to be preserved. Atomic force microscopy (AFM) imaging showed different surface patterns for adsorbed α-helix and β-sheet PLL. Interactions between PLL of different secondary structures and various substrates (i.e., PLL, Au, mica, and poly(ethylene glycol) (PEG)) were directly measured using a surface forces apparatus (SFA). It was found that β-sheet PLL films showed higher adsorbed layer thicknesses in general. Adhesion energies of β-sheet versus Au and β-sheet versus β-sheet were considerably higher than that of α-helix versus Au and α-helix versus α-helix systems, respectively. Au and β-sheet PLL interactions seemed to be more dependent on the salt concentration than that of α-helix, while the presence of a grafted PEG layer greatly diminished any attraction with either PLL structure. The molecular interaction mechanism of peptide in different secondary structures is discussed in terms of Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, Alexander-de Gennes (AdG) steric model and hydrogen bonding, which provides important insight into the fundamental understanding of the interaction mechanism between proteins and biomaterials.

  9. Nuclear structure effects in quasifission – understanding the formation of the heaviest elements

    Directory of Open Access Journals (Sweden)

    Hinde D. J.

    2016-01-01

    Full Text Available Quasifission is an important process suppressing the fusion of two heavy nuclei in reactions used to create superheavy elements. Quasifission results in rapid separation of the dinuclear system initially formed at contact. Achieving reliable a priori prediction of quasifission probabilities is a very diffcult problem. Through measurements with projectiles from C to Ni, the Australian National University’s Heavy Ion Accelerator Facility and CUBE spectrometer have been used to map out mass-angle distributions (MAD - the fission mass-ratio as a function of centre-of-mass angle. These provide information on quasifission dynamics in the least modeldependent way. Average quasifission time-scales have been extracted, and compared with TDHF calculations of the collisions, with good agreement being found. With the baseline information from the survey of experimental MAD, strong influences of the nuclear structure of the projectile and target nuclei can be clearly determined.

  10. 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)

  11. 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

  12. 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

  13. 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

  14. 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

  15. Understanding the Structure of Bones

    Science.gov (United States)

    ... structure of bone is very similar to reinforced concrete that is used to make a building or ... a defective blueprint is produced that tells the cell to produce deformed collagen, resulting in bad collagen ...

  16. Understanding structural conservation through materials science:

    DEFF Research Database (Denmark)

    Fuster-López, Laura; Krarup Andersen, Cecil

    2014-01-01

    provide both explanation and prediction of failure in materials. It has therefore shown to be an effective method for developing useful solutions to conservation problems. Since materials science and mechanics can help conservators predict the long term consequences of their treatments and provide them......Mechanical properties and the structure of materials are key elements in understanding how structural interventions in conservation treatments affect cultural heritage objects. In this context, engineering mechanics can help determine the strength and stability found in art objects as it can...... with tools to avoid future problems, it should be present in all conservation-restoration training programs to help promote students’ understanding of the degradation mechanisms in cultural materials (and their correlation with chemical and biological degradation) as well as the implications behind...

  17. 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…

  18. 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.

  19. Investigating Student Understanding of the Universe: Structure

    Science.gov (United States)

    Hayes, Virginia; Coble, K.; Nickerson, M.; Cochran, G.; Camarillo, C. T.; Bailey, J. M.; McLin, K. M.; Cominsky, L. R.

    2011-05-01

    Chicago State University (CSU) offers an introductory astronomy course that services students from a variety of majors including pre-service teachers. At CSU, we have been investigating methods and tools that will improve student conceptual understanding in astronomy for this diverse group of students. We have analyzed pre-course surveys, pre-course essays, exams, and interviews in an effort to better understand the ideas and difficulties in understanding that students have in regards to the structure of the universe. Analysis of written essays has revealed that our students do have some knowledge of the objects in the universe, but interviews inform us that their understanding of the structure of the universe is superficial. This project is a part of a larger study; also see our posters on student ideas about dark matter, the age and expansion of the universe, and perceptions of astronomical sizes and distances. This work was supported by NASA ROSES E/PO Grant #NNXlOAC89G, as well as by the Illinois Space Grant Consortium and National Science Foundation CCLI Grant #0632563 at Chicago State University and the Fermi E/PO program at Sonoma State University.

  20. 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.

  1. Report on Understanding and Predicting Effects of Thermal Aging on Microstructure and Tensile Properties of Grade 91 Steel for Structural Components

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meimei [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, K. [Argonne National Lab. (ANL), Argonne, IL (United States); Chen, Weiying [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-08-01

    This report provides an update on understanding and predicting the effects of long-term thermal aging on microstructure and tensile properties of G91 to corroborate the ASME Code rules in strength reduction due to elevated temperature service. The research is to support the design and long-term operation of G91 structural components in sodium-cooled fast reactors (SFRs). The report is a Level 2 deliverable in FY17 (M2AT-17AN1602017), under the Work Package AT-17AN160201, “SFR Materials Testing” performed by the Argonne National Laboratory (ANL), as part of the Advanced Reactor Technologies Program.

  2. 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.

  3. Understanding cooperative behavior in structurally disordered populations

    Science.gov (United States)

    Xu, C.; Zhang, W.; Du, P.; Choi, C. W.; Hui, P. M.

    2016-06-01

    The effects of an inhomogeneous competing environment on the extent of cooperation are studied within the context of a site-diluted evolutionary snowdrift game on a square lattice, with the occupied sites representing the players, both numerically and analytically. The frequency of cooperation ℱ C generally shows a non-monotonic dependence on the fraction of occupied sites ρ, for different values of the payoff parameter r. Slightly diluting a lattice leads to a lower cooperation for small and high values of r. For a range of r, however, dilution leads to an enhanced cooperation. An analytic treatment is developed for ℱC I + ℱC II, with ℱC I emphasizing the importance of the small clusters of players especially for ℱC II from the other players is shown to be inadequate. A local configuration approximation (LCA) that treats the local competing configurations as the variables and amounts to include spatial correlation up to the neighborhood of a player's neighbors is developed. Results of ℱ C ( ρ) and the number of different local configurations from LCA are in good agreement with simulation results. A transparent physical picture of the dynamics stemming from LCA is also presented. The theoretical approach provides a framework that can be readily applied to competing agent-based models in structurally ordered and disordered populations.

  4. Understanding Microbial Communities: Function, Structure and Dynamics

    Science.gov (United States)

    2015-02-11

    microbial communities: Function, structure and dynamics’, at the Isaac Newton Institute, University of Cambridge, United Kingdom, from August to...dynamics’, at the Isaac Newton Institute, University of Cambridge, United Kingdom, from August to December 2014. The programme involved over 150...Communities: Function, Structure and Dynamics’, at the Isaac Newton Institute, Cambridge University, UK, from 19th August 2014 – 19th December 2014

  5. Understanding water's anomalies with locally favoured structures.

    Science.gov (United States)

    Russo, John; Tanaka, Hajime

    2014-04-02

    Water is a complex liquid that displays a surprising array of unusual properties, the most famous being the density maximum at about 4 °C. The origin of these anomalies is still a matter of debate, and so far a quantitative description of water's phase behaviour starting from the molecular arrangements is still missing. Here we report a study of the microscopic structural features of water as obtained from computer simulations. We identify locally favoured structures having a high degree of translational order in the second shell, and a two-state model is used to describe the behaviour of liquid water over a wide region of the phase diagram. Furthermore, we show that locally favoured structures not only have translational order in the second shell but also contain five-membered rings of hydrogen-bonded molecules. This suggests their mixed character: the former helps crystallization, whereas the latter causes frustration against crystallization.

  6. Understanding water's anomalies with locally favored structures

    OpenAIRE

    Russo, John; Tanaka, Hajime

    2013-01-01

    Water is a complex structured liquid of hydrogen-bonded molecules that displays a surprising array of unusual properties, also known as water anomalies, the most famous being the density maximum at about $4^\\circ$C. The origin of these anomalies is still a matter of debate, and so far a quantitative description of water's phase behavior starting from the molecular arrangements is still missing. Here we provide a simple physical description from microscopic data obtained through computer simul...

  7. Cardiovascular effects of microgravity: evolution of understanding

    Science.gov (United States)

    Short, H. D.

    1998-01-01

    The understanding of cardiovascular effects of spaceflight has evolved throughout the course of the American manned spaceflight program. Originally descriptive in nature, the present understanding is based on empiric measurements of vascular volume, cardiac output, vascular reflexes, and peripheral and central autonomic control. More detailed understanding of cardiovascular effects has allowed us to separate those symptoms from symptoms caused by musculoskeletal or neurovestibular abnormalities.

  8. 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...

  9. Understanding the defect structure of solution grown zinc oxide

    International Nuclear Information System (INIS)

    Liew, Laura-Lynn; Sankar, Gopinathan; Handoko, Albertus D.; Goh, Gregory K.L.; Kohara, Shinji

    2012-01-01

    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 °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: ► ZnO powders have been synthesized through an aqueous solution method. ► Defect structure studied using XAS and XPDF. ► Zn–Zn correlations are less in the ZnO powders synthesized in solution than bulk. ► Zn vacancies are present in the powders synthesized. ► EXAFS and XPDF, when used complementary, are useful characterization techniques.

  10. New understanding of photocatalytic properties of zigzag and armchair g-C3N4 nanotubes from electronic structures and carrier effective mass

    Science.gov (United States)

    Liu, Jianjun; Cheng, Bei

    2018-02-01

    Low-dimensional g-C3N4 nanostructures own distinct electronic structure and remarkable photocatalytic properties, hence their wide application in the photocatalysis field. However, the correlations of structures and photoinduced carrier migrations with the photocatalytic properties of g-C3N4 nanostructures remain unclear. In this study, the geometrical and electronic structures and the photocatalytic properties of zigzag (n, 0) and armchair (n, n) g-C3N4 nanotubes (n = 6, 9, 12) were systematically investigated using hybrid DFT. Results indicated that the differences in geometrical structures of g-C3N4 nanotubes changed the band gaps and effective mass of carriers. Accordingly, the photocatalytic properties of g-C3N4 nanotubes also changed. Notably, the change trends of band gaps and the effective mass of the electrons and holes were the opposite for zigzag (n, 0) and armchair (n, n) g-C3N4 nanotubes. The absolute band edge potential of (n, 0) and (n, n) g-C3N4 nanotubes can split water for hydrogen production. These theoretical results revealed the correlations of structures and carrier effective mass with the photocatalytic properties of g-C3N4 nanotubes, and provided significant guidance for designing low-dimensional g-C3N4 nanostructures.

  11. A density functional reactivity theory (DFRT) based approach to understand the effect of symmetry of fullerenes on the kinetic, thermodynamic and structural aspects of carbon NanoBuds

    International Nuclear Information System (INIS)

    Sarmah, Amrit; Roy, Ram Kinkar

    2016-01-01

    Highlights: • Kinetic and thermodynamic aspects of the interaction between fullerene (C 32 ) and SWCNT using CDASE scheme. • Role of symmetry of fullerenes as well as the site of covalent attachment to the SWCNT in the structural stability of the NanoBud structure. • Increase in the fullerene symmetry improves the relative stability of hybrid NanoBud structure. - Abstract: In the present study, we have rationalized the effect of variation in the symmetry of relatively smaller fullerene (C 32 ) on the mode of its interaction with semi-conducting Single-Walled Carbon Nanotubes (SWCNTs) in the process of formation of stable hybrid carbon NanoBuds. Thermodynamic and kinetic parameters, along with the charge transfer values associated with the interaction between fullerene and SWCNTs, have been evaluated using an un-conventional and computationally cost–effective method based on density functional reactivity theory (DFRT). In addition to this, conventional DFT based studies are also performed to substantiate the growth of NanoBud structures formed by the interaction between fullerene and SWCNTs. The findings of the present study suggest that the kinetic, thermodynamic and structural aspects of hybrid carbon NanoBuds are significantly influenced by both the symmetry of C 32 fullerene and its site of covalent attachment to the SWCNT.

  12. Understanding the Effectiveness of Performance Management Practices

    Science.gov (United States)

    2010-03-01

    Stragetic human resource management at Praxair. Human Resources Management , 38 (4), 315-320. Heathfield, S. (2007). Performance appraisals. The...UNDERSTANDING THE EFFECTIVENESS OF PERFORMANCE MANAGEMENT PRACTICES THESIS Ross T. Johnston, Major...M07 UNDERSTANDING THE EFFECTIVENESS OF PERFORMANCE MANAGEMENT PRACTICES AFIT-GRD-ENV-10-M07 Presented to the Faculty

  13. Using decision trees to understand structure in missing data.

    Science.gov (United States)

    Tierney, Nicholas J; Harden, Fiona A; Harden, Maurice J; Mengersen, Kerrie L

    2015-06-29

    Demonstrate the application of decision trees--classification and regression trees (CARTs), and their cousins, boosted regression trees (BRTs)--to understand structure in missing data. Data taken from employees at 3 different industrial sites in Australia. 7915 observations were included. The approach was evaluated using an occupational health data set comprising results of questionnaires, medical tests and environmental monitoring. Statistical methods included standard statistical tests and the 'rpart' and 'gbm' packages for CART and BRT analyses, respectively, from the statistical software 'R'. A simulation study was conducted to explore the capability of decision tree models in describing data with missingness artificially introduced. CART and BRT models were effective in highlighting a missingness structure in the data, related to the type of data (medical or environmental), the site in which it was collected, the number of visits, and the presence of extreme values. The simulation study revealed that CART models were able to identify variables and values responsible for inducing missingness. There was greater variation in variable importance for unstructured as compared to structured missingness. Both CART and BRT models were effective in describing structural missingness in data. CART models may be preferred over BRT models for exploratory analysis of missing data, and selecting variables important for predicting missingness. BRT models can show how values of other variables influence missingness, which may prove useful for researchers. Researchers are encouraged to use CART and BRT models to explore and understand missing data. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  14. Understanding Self-Effects in Social Media

    NARCIS (Netherlands)

    Valkenburg, P.M.

    2017-01-01

    The aim of this article is to improve understanding of self-effects in social media, and to compare self-effects with reception effects. Self-effects are the effects of messages the cognitions, emotions, attitudes, and behaviors of the message creators/senders themselves. A total of 4 theories have

  15. Understanding the effects of two bound glucose in Sudlow site I on structure and function of human serum albumin: theoretical studies.

    Science.gov (United States)

    Awang, Tadsanee; Wiriyatanakorn, Nuttapon; Saparpakorn, Patchreenart; Japrung, Deanpen; Pongprayoon, Prapasiri

    2017-03-01

    Human serum albumin (HSA) is the most abundant protein found in blood serum. It carries essential metabolites and many drugs. The glycation of HSA causes abnormal biological effects. Importantly, glycated HSA (GHSA) is of interest as a biomarker for diabetes. Recently, the first HSA structure with bound pyranose (GLC) and open-chain (GLO) glucose at Sudlow site I has been crystallised. We therefore employed molecular dynamics (MD) simulations and ONIOM calculations to study the dynamic nature of two bound glucose in a pre-glycated HSA (pGHSA) and observe how those sugars alter a protein structure comparing to wild type (Apo) and fatty acid-bound HSA (FA). Our analyses show that the overall structural stability of pGHSA is similar to Apo and FA, except Sudlow site II. Having glucose induces large protein flexibility at Sudlow site II. Besides, the presence of glucose causes W214 to reorient resulting in a change in W214 microenvironment. Considering sugars, both sugars are exposed to water, but GLO is more solvent-accessible. ONIOM results show that glucose binding is favoured for HSA (-115.04 kcal/mol) and GLO (-85.10 kcal/mol) is more preferable for Sudlow site I over GLC (-29.94 kcal/mol). GLO can strongly react with K195 and K199, whereas K195 and K199 provide slightly repulsive forces for GLC. This can confirm that an open-chain GLO is more favourable inside a pocket.

  16. 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...

  17. 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

    2014-09-01

    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.

  18. Understanding metallic bonding: Structure, process and interaction by Rasch analysis

    Science.gov (United States)

    Cheng, Maurice M. W.; Oon, Pey-Tee

    2016-08-01

    This paper reports the results of a survey of 3006 Year 10-12 students on their understandings of metallic bonding. The instrument was developed based on Chi's ontological categories of scientific concepts and students' understanding of metallic bonding as reported in the literature. The instrument has two parts. Part one probed into students' understanding of metallic bonding as (a) a submicro structure of metals, (b) a process in which individual metal atoms lose their outermost shell electrons to form a 'sea of electrons' and octet metal cations or (c) an all-directional electrostatic force between delocalized electrons and metal cations, that is, an interaction. Part two assessed students' explanation of malleability of metals, for example (a) as a submicro structural rearrangement of metal atoms/cations or (b) based on all-directional electrostatic force. The instrument was validated by the Rasch Model. Psychometric assessment showed that the instrument possessed reasonably good properties of measurement. Results revealed that it was reliable and valid for measuring students' understanding of metallic bonding. Analysis revealed that the structure, process and interaction understandings were unidimensional and in an increasing order of difficulty. Implications for the teaching of metallic bonding, particular through the use of diagrams, critiques and model-based learning, are discussed.

  19. Understanding the structure and electronic properties of N-doped ...

    Indian Academy of Sciences (India)

    2014-11-12

    Nov 12, 2014 ... Understanding the structure and electronic properties of N-doped graphene nanoribbons upon hydrogen saturation. MICHAEL MANANGHAYA. Department of Chemical Engineering, De La Salle University, 2401 Taft Ave, Manila 1004 Philippines e-mail: mikemananghaya@gmail.com. MS received 31 May ...

  20. 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…

  1. Liberal Liability. Understanding Students’ Conceptions of Gender Structures

    Directory of Open Access Journals (Sweden)

    Linda Murstedt

    2014-04-01

    Full Text Available Research has shown that teaching gender theories tends to be an educational challenge and elicits student resistance. However, little is known about students’ learning processes in social science. This study aims to explore these learning processes by drawing on feminist pedagogy and conceptual change theory. The results show that when students are asked to perform analysis from a structural gender perspective, they recurrently introduce other explanatory frameworks based on non-structural understandings. The students’ learning processes involve reformulating questions and making interpretations based on liberal understandings of power, freedom of choice and equality. We argue that this process is due to the hegemonic position of the liberal paradigm as well as to the dominant ideas about science. Clarifying the underlying presumptions of a liberal perspective and a structural perspective may help students to recognise applied premises and enable them to distinguish relevant explanations.

  2. Understanding Citizenship, Understanding Social Media? The effects of digital media on citizenship understanding and political participation

    DEFF Research Database (Denmark)

    Ohme, Jakob; Albæk, Erik

    Is there a connection between increased use of digital media and changing patterns of political participation? This study tests how use of online media for different purposes (social interaction, creative expression, online news use, social media news use) is related to three types of political...... online survey waves and a smartphone-based media diary that documents respondents’ social media use. Results indicate support for a new pathway to participation, but the relationship depends on whether citizens are socialized in a digital media environment....... participation. It examines whether mobilizing effects are partly indirect due to different understandings of citizenship (dutiful, optional, individual, collective) that may be fostered by digital media use. The study is based on a survey of a sample of the Danish population (n=1322), including data from two...

  3. 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.

  4. Understanding the Structural Basis of Adhesion GPCR Functions.

    Science.gov (United States)

    Araç, Demet; Sträter, Norbert; Seiradake, Elena

    2016-01-01

    Unlike conventional G-protein-coupled receptors (GPCRs), adhesion GPCRs (aGPCRs) have large extracellular regions that are autoproteolytically cleaved from their membrane-embedded seven-pass transmembrane helices. Autoproteolysis occurs within the conserved GPCR-Autoproteolysis INducing (GAIN) domain that is juxtaposed to the transmembrane domain and cleaves the last beta strand of the GAIN domain. The other domains of the extracellular region are variable and specific to each aGPCR and are likely involved in adhering to various ligands. Emerging evidence suggest that extracellular regions may modulate receptor function and that ligand binding to the extracellular regions may induce receptor activation via multiple mechanisms. Here, we summarize current knowledge about the structural understanding for the extracellular regions of aGPCRs and discuss their possible functional roles that emerge from the available structural information.

  5. 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.

  6. Quantum effects in the understanding of consciousness.

    Science.gov (United States)

    Hameroff, Stuart R; Craddock, Travis J A; Tuszynski, Jack A

    2014-06-01

    This paper presents a historical perspective on the development and application of quantum physics methodology beyond physics, especially in biology and in the area of consciousness studies. Quantum physics provides a conceptual framework for the structural aspects of biological systems and processes via quantum chemistry. In recent years individual biological phenomena such as photosynthesis and bird navigation have been experimentally and theoretically analyzed using quantum methods building conceptual foundations for quantum biology. Since consciousness is attributed to human (and possibly animal) mind, quantum underpinnings of cognitive processes are a logical extension. Several proposals, especially the Orch OR hypothesis, have been put forth in an effort to introduce a scientific basis to the theory of consciousness. At the center of these approaches are microtubules as the substrate on which conscious processes in terms of quantum coherence and entanglement can be built. Additionally, Quantum Metabolism, quantum processes in ion channels and quantum effects in sensory stimulation are discussed in this connection. We discuss the challenges and merits related to quantum consciousness approaches as well as their potential extensions.

  7. 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.

  8. Using Instruments to Understand Argument Structure: Evidence for Gradient Representation

    Science.gov (United States)

    Rissman, Lilia; Rawlins, Kyle; Landau, Barbara

    2015-01-01

    The arguments of a verb are commonly assumed to correspond to the event participants specified by the verb. That is, drink has two arguments because drink specifies two participants: someone who drinks and something that gets drunk. This correspondence does not appear to hold, however, in the case of instrumental participants, e.g. John drank the soda with a straw. Verbs such as slice and write have been argued to specify an instrumental participant, even though instruments do not pattern like arguments given other criteria. In this paper, we investigated how instrumental verbs are represented, testing the hypothesis that verbs such as slice encode three participants in the same way that dative verbs such as lend encode three participants. In two experiments English-speakers reported their judgments about the number of participants specified by a verb, e.g. that drink specifies two participants. These judgments indicate that slice does not encode three distinct arguments. Nonetheless, some verbs were systematically more likely to elicit the judgment that the instrument is specified by the verb, a pattern that held across individual subjects. To account for these findings, we propose that instruments are not independent verbal arguments but are represented in a gradient away: an instrument may be a more or less salient part of the force exerted by an agent. These results inform our understanding of the relationship between argument structure and event representation, raising questions concerning the role of arguments in language processing and learning. PMID:26057832

  9. 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.

  10. Ultrathin (Understanding the processing, structure, and physical and electrical limits

    Science.gov (United States)

    Green, M. L.; Gusev, E. P.; Degraeve, R.; Garfunkel, E. L.

    2001-09-01

    The outstanding properties of SiO2, which include high resistivity, excellent dielectric strength, a large band gap, a high melting point, and a native, low defect density interface with Si, are in large part responsible for enabling the microelectronics revolution. The Si/SiO2 interface, which forms the heart of the modern metal-oxide-semiconductor field effect transistor, the building block of the integrated circuit, is arguably the worlds most economically and technologically important materials interface. This article summarizes recent progress and current scientific understanding of ultrathin (understanding of the limits of these gate dielectrics, i.e., how their continuously shrinking thickness, dictated by integrated circuit device scaling, results in physical and electrical property changes that impose limits on their usefulness. We observe, in conclusion, that although Si microelectronic devices will be manufactured with SiO2 and Si-O-N for the foreseeable future, continued scaling of integrated circuit devices, essentially the continued adherence to Moore's law, will necessitate the introduction of an alternate gate dielectric once the SiO2 gate dielectric thickness approaches ˜1.2 nm. It is hoped that this article will prove useful to members of the silicon microelectronics community, newcomers to the gate dielectrics field, practitioners in allied fields, and graduate students. Parts of this article have been adapted from earlier articles by the authors [L. Feldman, E. P. Gusev, and E. Garfunkel, in Fundamental Aspects of Ultrathin Dielectrics on Si-based Devices, edited by E. Garfunkel, E. P. Gusev, and A. Y. Vul' (Kluwer, Dordrecht, 1998), p. 1 [Ref. 1]; E. P. Gusev, H. C. Lu, E. Garfunkel, T. Gustafsson, and M. Green, IBM J. Res. Dev. 43, 265 (1999) [Ref. 2]; R. Degraeve, B. Kaczer, and G. Groeseneken, Microelectron. Reliab. 39, 1445 (1999) [Ref. 3].

  11. Understanding the edge effect in wetting: a thermodynamic approach.

    Science.gov (United States)

    Fang, Guoping; Amirfazli, A

    2012-06-26

    Edge effect is known to hinder spreading of a sessile drop. However, the underlying thermodynamic mechanisms responsible for the edge effect still is not well-understood. In this study, a free energy model has been developed to investigate the energetic state of drops on a single pillar (from upright frustum to inverted frustum geometries). An analysis of drop free energy levels before and after crossing the edge allows us to understand the thermodynamic origin of the edge effect. In particular, four wetting cases for a drop on a single pillar with different edge angles have been determined by understanding the characteristics of FE plots. A wetting map describing the four wetting cases is given in terms of edge angle and intrinsic contact angle. The results show that the free energy barrier observed near the edge plays an important role in determining the drop states, i.e., (1) stable or metastable drop states at the pillar's edge, and (2) drop collapse by liquid spilling over the edge completely or staying at an intermediate sidewall position of the pillar. This thermodynamic model presents an energetic framework to describe the functioning of the so-called "re-entrant" structures. Results show good consistency with the literature and expand the current understanding of Gibbs' inequality condition.

  12. Understanding Metallic Bonding: Structure, Process and Interaction by Rasch Analysis

    Science.gov (United States)

    Cheng, Maurice M. W.; Oon, Pey-Tee

    2016-01-01

    This paper reports the results of a survey of 3006 Year 10-12 students on their understandings of metallic bonding. The instrument was developed based on Chi's ontological categories of scientific concepts and students' understanding of metallic bonding as reported in the literature. The instrument has two parts. Part one probed into students'…

  13. 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.

  14. Understanding dementia: effective information access from the Deaf community's perspective.

    Science.gov (United States)

    Young, Alys; Ferguson-Coleman, Emma; Keady, John

    2016-01-01

    This study concerns older Deaf sign language users in the UK. Its aim was to explore how to enable effective information access and promote awareness and understanding of dementia from a culturally Deaf perspective. A purposive sample of 26 Deaf people without dementia participated in one of three focus groups facilitated directly in British Sign Language (BSL) without an intermediate interpreter. The sample was differentiated by age, role in the Deaf community, and diversity of educational attainment and professional experience. A phenomenological approach underpinned the thematic analysis of data. The findings demonstrate: (i) translation into (BSL) is a necessary but not sufficient condition to support understanding. Attention to culturally preferred means of engagement with information is vital; (ii) the content of information is best presented utilising structures and formats which cohere with Deaf people's visual cognitive strengths; and (iii) the importance of cultural values and cultural practices in raising awareness and building understanding of dementia. These include collective rather than individual responsibility for knowledge transfer and the pan-national nature of knowledge transfer among Deaf people(s). The discussion demonstrates how these specific features of effective information access and awareness building have universal implications relevant to public engagement and the promotion of general knowledge consistent with the National Dementia Strategy (England). © 2014 The Authors. Health and Social Care in the Community Published by John Wiley & Sons Ltd.

  15. Understanding Local Structure versus Long-Range Structure: The Case of UO2.

    Science.gov (United States)

    Desgranges, Lionel; Ma, Yue; Garcia, Philippe; Baldinozzi, Gianguido; Siméone, David; Fischer, Henry E

    2018-02-09

    A recent trend in the development of new optimized materials makes use of crystalline domains having nanometer sizes for which characterization methods at the atomic scale are mandatory. Amongst them is pair-distribution function analysis (PDF-analysis), a diffraction technique that has already shown that a short-range or "local" atomic structure of a given domain, having a lower symmetry than the average long-range structure, often exists in many compounds having valuable properties for industrial applications, such as pyrochlores, spinels, and doped ceria among others. However, the manner by which these domains are arranged to produce the average long-range structure is still an open question. Herein, the first structural model that accounts for both the local structure (inside a given domain) and the long-range structure (averaged over all domains) that is observed in the PDF of uranium dioxide is presented. The structural model describes domain walls in such a way as to preserve the uranium coordination polyhedron and to obey the needed symmetry rules. The proper description of domain walls is an important step in the understanding and the modelling of nanostructured materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Lay understandings of the effects of poverty: a Canadian perspective.

    Science.gov (United States)

    Reutter, Linda I; Veenstra, Gerry; Stewart, Miriam J; Raphael, Dennis; Love, Rhonda; Makwarimba, Edward; McMurray, Susan

    2005-11-01

    Although there is a large body of research dedicated to exploring public attributions for poverty, considerably less attention has been directed to public understandings about the effects of poverty. In this paper, we describe lay understandings of the effects of poverty and the factors that potentially influence these perceptions, using data from a telephone survey conducted in 2002 on a random sample (n=1671) of adults from eight neighbourhoods in two large Canadian cities (Edmonton and Toronto). These data were supplemented with interview data obtained from 153 people living in these same neighbourhoods. Multivariate linear and logistic regressions were used to determine the effects of basic demographic variables, exposure to poverty and attribution for poverty on three dependent variables relating to the effects of poverty: participation in community life, the relationship between poverty and health and challenges facing low-income people. Ninety-one per cent of survey respondents agreed that poverty is linked to health, while 68% agreed that low-income people are less likely to participate in community life. Affordable housing was deemed especially difficult to obtain by 96%, but other resources (obtaining healthy food, giving children a good start in life, and engaging in healthy behaviours) were also viewed as challenging by at least 70% of respondents. The regression models revealed that when controlling for demographics, exposure to poverty explained some of the variance in recognising the effects of poverty. Media exposure positively influenced recognition of the poverty-health link, and attending formal talks was strongly related to understanding challenges of poverty. Attributions for poverty accounted for slightly more of the variance in the dependent variables. Specifically, structural and sociocultural attributions predicted greater recognition of the effects of poverty, in particular the challenges of poverty, while individualistic attributions

  17. 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 ...

  18. Effectiveness of CAM therapy: understanding the evidence.

    Science.gov (United States)

    Staud, Roland

    2011-02-01

    By definition, complementary and alternative medicine (CAM) attempts to diagnose and treat illnesses in unconventional ways. CAM has been classified as: (1) alternative medical systems (eg, traditional Chinese medicine [including acupuncture], naturopathic medicine, ayurvedic medicine, and homeopathy); (2) biologic-based therapies (eg, herbal, special dietary, and individual biologic treatments); (3) energy therapies (eg, Reiki, therapeutic touch, magnet therapy, Qi Gong, and intercessory prayer); (4) manipulative and body-based systems (eg, chiropractic, osteopathy, and massage); and (5) mind-body interventions (eg, meditation, biofeedback, hypnotherapy, and the relaxation response). This review focuses on how to assess the effectiveness of CAM therapies for chronic musculoskeletal pains, emphasizing the role of specific and nonspecific analgesic mechanisms, including placebo. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Understanding Digital Learning and Its Variable Effects

    Science.gov (United States)

    Means, B.

    2016-12-01

    An increasing proportion of undergraduate courses use an online or blended learning format. This trend signals major changes in the kind of instruction students receive in their STEM courses, yet evidence about the effectiveness of these new approaches is sparse. Existing syntheses and meta-analyses summarize outcomes from experimental or quasi-experimental studies of online and blended courses and document how few studies incorporate proper controls for differences in student characteristics, instructor behaviors, and other course conditions. The evidence that is available suggests that on average blended courses are equal to or better than traditional face-to-face courses and that online courses are equivalent in terms of learning outcomes. But these averages conceal a tremendous underlying variability. Results vary markedly from course to course, even when the same technology is used in both. Some research suggests that online instruction puts lower-achieving students at a disadvantage. It is clear that introducing digital learning per se is no guarantee that student engagement and learning will be enhanced. Getting more consistently positive impacts out of learning technologies is going to require systematic characterization of the features of learning technologies and associated instructional practices as well as attention to context and student characteristics. This presentation will present a framework for characterizing essential features of digital learning resources, implementation practices, and conditions. It will also summarize the research evidence with respect to the learning impacts of specific technology features including spaced practice, immediate feedback, mastery learning based pacing, visualizations and simulations, gaming features, prompts for explanations and reflection, and tools for online collaboration.

  20. 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.

  1. Fundamental understanding and rational design of high energy structural microbatteries

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuxing; Li, Qiuyan; Cartmell, Samuel; Li, Huidong; Mendoza, Sarah; Zhang, Ji-Guang; Deng, Zhiqun Daniel; Xiao, Jie

    2018-01-01

    Microbatteries play a critical role in determining the lifetime of downsized sensors, wearable devices and medical applications, etc. More often, structural batteries are required from the perspective of aesthetics and space utilization, which is however rarely explored. Herein, we discuss the fundamental issues associated with the rational design of practically usable high energy microbatteries. The tubular shape of the cell further allows the flexible integration of microelectronics. A functioning acoustic micro-transmitter continuously powered by this tubular battery has been successfully demonstrated. Multiple design features adopted to accommodate large mechanical stress during the rolling process are discussed providing new insights in designing the structural microbatteries for emerging technologies.

  2. Using a structured morbidity and mortality meeting to understand the ...

    African Journals Online (AJOL)

    2013-11-04

    Nov 4, 2013 ... We report our experience with these meetings. Methods. A structured template was developed for each morbidity and mortality meeting. We used a grid to analyse mortality and classify the death as: (i) death expected/death unexpected; and (ii) death unpreventable/death preventable. Individual cases were ...

  3. Understanding Protein-Protein Interactions Using Local Structural Features

    DEFF Research Database (Denmark)

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

    2013-01-01

    of this classification suggests that the balance between favoring and disfavoring structural features determines if a pair of proteins interacts or not. Our results are in agreement with previous works and support the funnel-like intermolecular energy landscape theory that explains PPIs. We have used these features...

  4. Understanding Practices in Mathematics Education: Structure and Text

    Science.gov (United States)

    Morgan, Candia

    2014-01-01

    The practices of mathematics education can be investigated at a wide variety of levels: from the actions of individual students or teachers through classroom interactions, school structures, curriculum specifications and materials, teacher development programmes and local, national or international systems of instruction and assessment. These…

  5. Understanding the structure and electronic properties of N-doped ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Structures and electronic properties of zigzag graphene nanoribbon (ZGNR) with pyridine (3NVZGNR) functionalized by Scandium (Sc) at the edge were studied through quantum chemical calculations in the formalism of density-functional theory (DFT). Pyridine-like nitrogen defects is very crucial for ...

  6. Schools as Racial Spaces: Understanding and Resisting Structural Racism

    Science.gov (United States)

    Blaisdell, Benjamin

    2016-01-01

    Analyzing schools as racial spaces can help researchers examine the role of teachers in the perpetuation of structural racism in schools. Based on ethnographic and autoethnographic work, this article offers examples of schools as racial spaces, spaces where whiteness controlled access. It also highlights four teachers who pursued racial equity in…

  7. Understanding and quantifying urban forest structure, functions, and value

    Science.gov (United States)

    David J. Nowak; Daniel E. Crane; Jeffrey T. Walton; Daniel B. Twardus; John F. Dwyer

    2002-01-01

    Trees in urban areas can have a significant impact on human health and the environment. Unfortunately, there is relatively little data about the structure, health, functions, and long-term changes in this important resource. In the United States, a number of efforts are underway to assess urban forest attributes at the local to national scales. In addition, tools are...

  8. Using a structured morbidity and mortality meeting to understand the ...

    African Journals Online (AJOL)

    Background. Several authors have suggested that the traditional surgical morbidity and mortality meeting be developed as a tool to identify surgical errors and turn them into learning opportunities for staff. We report our experience with these meetings. Methods. A structured template was developed for each morbidity and ...

  9. 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

  10. Understanding `galaxy groups' as a unique structure in the universe

    Science.gov (United States)

    Paul, S.; John, R. S.; Gupta, P.; Kumar, H.

    2017-10-01

    'Galaxy groups' have hardly been realized as a separate class of objects with specific characteristics in the structural hierarchy. The presumption that the self-similarity of dark matter structures is a valid prescription for the baryonic universe at all scales has rendered smaller structures undetectable by current observational facilities, leading to lesser dedicated studies on them. Some recent reports that indicate a deviation from LX-T scaling in groups compared to clusters have motivated us to study their physical properties in depth. In this article, we report the extensive study on physical properties of groups in comparison to the clusters through cosmological hydrodynamic plus N-body simulations using enzo 2.2 code. As additional physics, radiative cooling, heating due to supernova and star motions, star formation and stellar feedback have been implemented. We have produced a mock sample of 362 objects with mass ranging from 5 × 1012 M⊙ to 2.5 × 1015 M⊙. Strikingly, we have found that objects with mass below ˜8 × 1013 M⊙ do not follow any of the cluster self-similar laws in hydrostatics, not even in thermal and non-thermal energies. Two distinct scaling laws are observed to be followed with breaks at ˜8 × 1013 M⊙ for mass, ˜1 keV for temperature and ˜1 Mpc for radius. This places groups as a distinct entity in the hierarchical structures, well demarcated from clusters. This study reveals that groups are mostly far away from virialization, suggesting the need for formulating new models for deciphering their physical parameters. They are also shown to have high turbulence and more non-thermal energy stored, indicating better visibility in the non-thermal regime.

  11. Understanding 'Galaxy Groups' as a Unique Structure in the Universe

    Science.gov (United States)

    John, Reju Sam; Paul, Surajit; Gupta, Prateek; Kumar, Harish

    2017-07-01

    'Galaxy groups' have hardly been realized as a separate class of objects with specific characteristics in the structural hierarchy of the universe. The presumption that the self-similarity of dark matter structures is a valid prescription for the baryonic universe also at all scales has rendered smaller structures undetectable by current observational facilities, leading to lesser dedicated studies on them. Some recent reports on deviation of {L_x}-T scaling in groups from that of clusters have motivated us to study their physical properties in depth. In this article, we report the extensive study on physical properties of groups in comparison with clusters through cosmological hydrodynamic plus N-body simulations using ENZO 2.2 code. We have included cooling and heating physics and star formation feedback in the simulation. And produced a mock sample of 362 objects with mass ranging from 5×10^{12} M_{⊙} to 2.5×10^{15} M_{⊙}. Strikingly, we have found that objects with a mass below ˜ 8×10^{13} M_{⊙} do not follow any of the cluster self-similar laws in hydrostatics, not even in thermal and non-thermal regimes. Two distinct scaling laws are observed to be followed with breaks at ˜ 6-8× 10^{13} M_{⊙} for mass, ˜1 keV for temperature and ˜1 Mpc for radius. This places groups as a distinct entity in the hierarchical structures, well demarcated from clusters. This study reveals that groups are mostly far away from virialization, suggesting the need for formulating new models for deciphering their physical parameters. They are also shown to have high turbulence and more non-thermal energy stored, indicating better visibility in the non-thermal regime.

  12. From structure of the complex to understanding of the biology

    Energy Technology Data Exchange (ETDEWEB)

    Rossmann, Michael G., E-mail: mr@purdue.edu [Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054 (United States); Arisaka, Fumio [Graduate School and School of Bioscience and Biotechnology, Tokyo Institute of Technology, 5249 Nagatsuta-cho, Yokohama 226-8501-B39 (Japan); Battisti, Anthony J.; Bowman, Valorie D.; Chipman, Paul R.; Fokine, Andrei; Hafenstein, Susan [Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054 (United States); Kanamaru, Shuji [Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054 (United States); Graduate School and School of Bioscience and Biotechnology, Tokyo Institute of Technology, 5249 Nagatsuta-cho, Yokohama 226-8501-B39 (Japan); Kostyuchenko, Victor A. [Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054 (United States); Mesyanzhinov, Vadim V.; Shneider, Mikhail M. [Laboratory of Molecular Bioengineering, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 16/10 Miklukho-Maklaya Street, Moscow, 117997 (Russian Federation); Morais, Marc C.; Leiman, Petr G. [Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054 (United States); Palermo, Laura M.; Parrish, Colin R. [James A. Baker Institute, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853 (United States); Xiao, Chuan [Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054 (United States)

    2007-01-01

    The most extensive structural information on viruses relates to apparently icosahedral virions and is based on X-ray crystallography and on cryo-electron microscopy single-particle reconstructions. This paper concerns itself with the study of the macromolecular complexes that constitute viruses, using structural hybrid techniques. The most extensive structural information on viruses relates to apparently icosahedral virions and is based on X-ray crystallography and on cryo-electron microscopy (cryo-EM) single-particle reconstructions. Both techniques lean heavily on imposing icosahedral symmetry, thereby obscuring any deviation from the assumed symmetry. However, tailed bacteriophages have icosahedral or prolate icosahedral heads that have one obvious unique vertex where the genome can enter for DNA packaging and exit when infecting a host cell. The presence of the tail allows cryo-EM reconstructions in which the special vertex is used to orient the head in a unique manner. Some very large dsDNA icosahedral viruses also develop special vertices thought to be required for infecting host cells. Similarly, preliminary cryo-EM data for the small ssDNA canine parvovirus complexed with receptor suggests that these viruses, previously considered to be accurately icosahedral, might have some asymmetric properties that generate one preferred receptor-binding site on the viral surface. Comparisons are made between rhinoviruses that bind receptor molecules uniformly to all 60 equivalent binding sites, canine parvovirus, which appears to have a preferred receptor-binding site, and bacteriophage T4, which gains major biological advantages on account of its unique vertex and tail organelle.

  13. Understanding the structure of nuclei at finite temperatures

    International Nuclear Information System (INIS)

    Baktash, C.

    1988-01-01

    The purpose of this commentary is to briefly review several works on nuclear structure and to enumerate a few of the difficulties encountered in the interpretation of the experimental results. To be brief, comments are confined to the studies in the particle-bound regime, i.e., a temperature range of T ≤ 1 MeV. Among the interesting topics to be addressed in this temperature range are the question of thermal fluctuations, and the variations of the pairing correlations, shape parameters, nuclear collectivity, and rotational damping width with spin and excitation energy

  14. Understanding the Mixing Phenomena - from Structural Stability to Chaos

    Directory of Open Access Journals (Sweden)

    Adela Ionescu

    2011-01-01

    Full Text Available Nowadays, computational fluid dynamics (CFD becomes
    more and more mature. In the same time, it becomes more and more difficult to contribute fundamental research to it. Although the software tools in this area are increasing in importance, the way how CFD develops remain unpredictable, and it is part of what makes it an exciting and attractive discipline. The mixing phenomena - and the mixing theory - are using more and more CFD tools. This modern theory issued in the flow kinematics after hundred of years of stability study, has mathematical methods and techniques which are developing a continuous signi¯cant relation between turbulence and chaos. The turbulence is an important feature of dynamic systems with few freedom degrees, the so-called far from equilibrium systems. These are widespread between the models of excitable media. The present paper exhibits some recent results of the turbulent mixing study, based on computational tools of MAPLE11 soft. The data would be statistically analyzed, in order to construct a significant guideline in understanding the transition from stability to
    chaos in these excitable media.

  15. Children's Home Environments: Understanding the Role of Family Structure Changes

    Science.gov (United States)

    Kowaleski-Jones, Lori; Dunifon, Rachel

    2004-01-01

    Using data from the 1996 National Longitudinal Survey of Youth (NLSY79) merged mother-child sample, we investigate the impact of two family events, parental divorce and the birth of a sibling, on the cognitive stimulation and emotional support provided to children in the home. We use fixed-effect regression techniques to control for unmeasured…

  16. Effect of Linked Rules on Business Process Model Understanding

    DEFF Research Database (Denmark)

    Wang, Wei; Indulska, Marta; Sadiq, Shazia

    2017-01-01

    of business processes has not been empirically evaluated. In this paper, we report on an experiment that investigates the effect of linked rules, a specific rule integration approach, on business process model understanding. Our results indicate that linked rules are associated with better time efficiency......Business process models are widely used in organizations by information systems analysts to represent complex business requirements and by business users to understand business operations and constraints. This understanding is extracted from graphical process models as well as business rules. Prior...... research advocated integrating business rules into business process models to improve the effectiveness of important organizational activities, such as developing shared understanding, effective communication, and process improvement. However, whether such integrated modeling can improve the understanding...

  17. 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…

  18. Domain decomposition-based structural condensation of large protein structures for understanding their conformational dynamics.

    Science.gov (United States)

    Kim, Jae In; Na, Sungsoo; Eom, Kilho

    2011-01-15

    Normal mode analysis (NMA) with coarse-grained model, such as elastic network model (ENM), has allowed the quantitative understanding of protein dynamics. As the protein size is increased, there emerges the expensive computational process to find the dynamically important low-frequency normal modes due to diagonalization of massive Hessian matrix. In this study, we have provided the domain decomposition-based structural condensation method that enables the efficient computations on low-frequency motions. Specifically, our coarse-graining method is established by coupling between model condensation (MC; Eom et al., J Comput Chem 2007, 28, 1400) and component mode synthesis (Kim et al., J Chem Theor Comput 2009, 5, 1931). A protein structure is first decomposed into substructural units, and then each substructural unit is coarse-grained by MC. Once the NMA is implemented to coarse-grained substructural units, normal modes and natural frequencies for each coarse-grained substructural unit are assembled by using geometric constraints to provide the normal modes and natural frequencies for whole protein structure. It is shown that our coarse-graining method enhances the computational efficiency for analysis of large protein complexes. It is clearly suggested that our coarse-graining method provides the B-factors of 100 large proteins, quantitatively comparable with those obtained from original NMA, with computational efficiency. Moreover, the collective behaviors and/or the correlated motions for model proteins are well delineated by our suggested coarse-grained models, quantitatively comparable with those computed from original NMA. It is implied that our coarse-grained method enables the computationally efficient studies on conformational dynamics of large protein complex.

  19. Understanding the Structural Evolution of Single Conjugated Polymer Chain Conformers

    Directory of Open Access Journals (Sweden)

    Adam J. Wise

    2016-11-01

    Full Text Available Single molecule photoluminescence (PL spectroscopy of conjugated polymers has shed new light on the complex structure–function relationships of these materials. Although extensive work has been carried out using polarization and excitation intensity modulated experiments to elucidate conformation-dependent photophysics, surprisingly little attention has been given to information contained in the PL spectral line shapes. We investigate single molecule PL spectra of the prototypical conjugated polymer poly[2-methoxy-5-(2-ethylhexyloxy-1,4-phenylenevinylene] (MEH-PPV which exists in at least two emissive conformers and can only be observed at dilute levels. Using a model based on the well-known “Missing Mode Effect” (MIME, we show that vibronic progression intervals for MEH-PPV conformers can be explained by relative contributions from particular skeletal vibrational modes. Here, observed progression intervals do not match any ground state Raman active vibrational frequency and instead represent a coalescence of multiple modes in the frequency domain. For example, the higher energy emitting “blue” MEH-PPV form exhibits PL maxima at ~18,200 cm−1 with characteristic MIME progression intervals of ~1200–1350 cm−1, whereas the lower energy emitting “red” form peaks at ~17,100 cm−1 with intervals in the range of ~1350–1450 cm−1. The main differences in blue and red MEH-PPV chromophores lie in the intra-chain order, or, planarity of monomers within a chromophore segment. We demonstrate that the Raman-active out-of-plane C–H wag of the MEH-PPV vinylene group (~966 cm−1 has the greatest influence in determining the observed vibronic progression MIME interval. Namely, larger displacements (intensities—indicating lower intra-chain order—lower the effective MIME interval. This simple model provides useful insights into the conformational characteristics of the heterogeneous chromophore landscape without requiring costly and

  20. 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.

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

    Directory of Open Access Journals (Sweden)

    Sydney A Martinez

    Full Text Available 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.

  2. AGING EFFECTS ON SHIP STRUCTURAL INTEGRITY

    Directory of Open Access Journals (Sweden)

    Joško Parunov

    2017-01-01

    Full Text Available The most important degradation effects of ship structures are corrosion and fatigue cracks. Both of these aging effects have clear consequences of increasing the level of stresses and degrading the strength of ship structures for almost all relevant failure modes. This study presents an overview of some recent developments on the aging effects on the ship structural integrity. The analysis of the thickness measurements has been undertaken to improve understanding of the corrosion degradation phenomena and to develop prediction models of aging effects suitable for practical applications in the ship structural design and analysis. The study also deals with the application of the non-linear finite element analysis as a suitable tool for a collapse assessment of uniaxially loaded plates and stiffened panels of ship structures weakened by non-uniform corrosion degradation and fatigue cracks. Experimental studies have also been reviewed to better understand the recently found degradation of mechanical properties of corroded steel, while theoretical calculations have been performed to evaluate consequences of such degradation on the ship structural integrity.

  3. Mini-review: Current Understanding of the Correlation of Lignin Structure with Biomass Recalcitrance

    Directory of Open Access Journals (Sweden)

    Mi Li

    2016-11-01

    Full Text Available Lignin, a complex aromatic polymer in terrestrial plants, contributes significantly to biomass recalcitrance to microbial and/or enzymatic deconstruction. To reduce biomass recalcitrance, substantial endeavors have been exerted on pretreatment and lignin engineering in the past few decades. Lignin removal and/or alteration of lignin structure have been shown to result in reduced biomass recalcitrance with improved cell wall digestibility. While high lignin content is usually a barrier to a cost-efficient application of bioresource to biofuels, the direct correlation of lignin structure and its concomitant properties with biomass remains unclear due to the complexity of cell wall and lignin structure. Advancement in application of biorefinery to production of biofuels, chemicals, and biomaterials necessitates a fundamental understanding of the relationship of lignin structure and biomass recalcitrance. In this mini-review, we focus on recent investigations on the influence of lignin chemical properties on bioprocessability— pretreatment and enzymatic hydrolysis of biomass. Specifically, lignin-enzyme interaction and the effects of lignin compositional units, hydroxycinnamates, and lignin functional groups on biomass recalcitrance have been highlighted, which will be useful not only in addressing biomass recalcitrance but also in deploying renewable lignocelluloses efficiently.

  4. 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

  5. Understanding herding based on a co-evolutionary model for strategy and game structure

    International Nuclear Information System (INIS)

    Wang, Tao; Huang, Keke; Cheng, Yuan; Zheng, Xiaoping

    2015-01-01

    Highlights: •We model herding effect in emergency from perspective of evolutionary game theory. •Rational subpopulation survives only when the game parameter is significantly large. •Herding effect may arise if the relative rewarding for rational agents is small. •Increasing the relative rewarding for rational agents will prevent herding effect. •The evolution result is unstable if the game parameter approaches critical points. -- Abstract: So far, there has been no conclusion on the mechanism for herding, which is often discussed in the academia. Assuming escaping behavior of individuals in emergency is rational rather than out of panic according to recent findings in social psychology, we investigate the behavioral evolution of large crowds from the perspective of evolutionary game theory. Specifically, evolution of the whole population divided into two subpopulations, namely the co-evolution of strategy and game structure, is numerically simulated based on the game theoretical models built and the evolutionary rule designed, and a series of phenomena including extinction of one subpopulation and herding effect are predicted in the proposed framework. Furthermore, if the rewarding for rational agents becomes significantly larger than that for emotional ones, herding effect will disappear. It is exciting that some phase transition points with interesting properties for the system can be found. In addition, our model framework is able to explain the fact that it is difficult for mavericks to prevail in society. The current results of this work will be helpful in understanding and restraining herding effect in real life

  6. 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 ...

  7. 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

  8. Combining computational chemistry and crystallography for a better understanding of the structure of cellulose

    Science.gov (United States)

    The approaches in this article seek to enhance understanding of cellulose at the molecular level, independent of the source and the particular crystalline form of cellulose. Four main areas of structure research are reviewed. Initially the molecular shape is inferred from the crystal structures of m...

  9. Understanding Structure-Property Relations of Compressed Glasses through Relaxation Studies

    DEFF Research Database (Denmark)

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

    When a glassy material or its liquid state is subjected to sufficiently high pressure, significant changes can take place in the short- and medium-range structure, vibrational density of states, and physical properties. It is crucial to determine and understand the structure-property relations un...

  10. 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

  11. 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.

  12. Understanding and Utilizing the Effectiveness of e‐Learning

    DEFF Research Database (Denmark)

    Noesgaard, Signe Schack; Ørngreen, Rikke

    2014-01-01

    . At the same time, learning and development professionals within public and private organizations are increasingly met with a demand to prove the effectiveness of their learning and development initiatives. This paper investigates the concepts of effectiveness in e-Learning. It broadens the definition......A structured search of librarian databases revealed that the research into the effectiveness of e-Learning has heavily increased within the last 5 years. Taking a closer look at the search results, the authors discovered that researchers define and investigate effectiveness in multiple ways...... of effectiveness and qualifies certain measurements of same. Preliminary results from a literature study and an empirical investigation of ‘the effectiveness of e-Learning’ for science teachers (K12) are combined. The paper discusses the following research questions: How is the effectiveness of e-Learning defined...

  13. 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.)

  14. 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.

  15. A structural equation modeling analysis of students' understanding in basic mathematics

    Science.gov (United States)

    Oktavia, Rini; Arif, Salmawaty; Ferdhiana, Ridha; Yuni, Syarifah Meurah; Ihsan, Mahyus

    2017-11-01

    This research, in general, aims to identify incoming students' understanding and misconceptions of several basic concepts in mathematics. The participants of this study are the 2015 incoming students of Faculty of Mathematics and Natural Science of Syiah Kuala University, Indonesia. Using an instrument that were developed based on some anecdotal and empirical evidences on students' misconceptions, a survey involving 325 participants was administered and several quantitative and qualitative analysis of the survey data were conducted. In this article, we discuss the confirmatory factor analysis using Structural Equation Modeling (SEM) on factors that determine the new students' overall understanding of basic mathematics. The results showed that students' understanding on algebra, arithmetic, and geometry were significant predictors for their overall understanding of basic mathematics. This result supported that arithmetic and algebra are not the only predictors of students' understanding of basic mathematics.

  16. Understanding Consumer Confidence in the Safety of Food: Its Two-Dimensional Structure and Determinants

    NARCIS (Netherlands)

    Jonge, de J.; Trijp, van J.C.M.; Renes, R.J.; Frewer, L.J.

    2007-01-01

    Understanding of the determinants of consumer confidence in the safety of food is important if effective risk management and communication are to be developed. In the research reported here, we attempt to understand the roles of consumer trust in actors in the food chain and regulators, consumer

  17. Toward Better Understanding of Turbulence Effects on Bridge Aerodynamics

    Directory of Open Access Journals (Sweden)

    Shuyang Cao

    2017-12-01

    Full Text Available With the trend of variable cross-sections for long-span bridges from truss-stiffened to quasi-streamlined, and then to multiple-box cross-section geometries, the importance of aeroelastic performance is becoming increasingly significant in wind-resistant design. This article shows that there is clearly insufficient qualitative as well as quantitative understanding of turbulence effects on bridge aerodynamics, particularly the mechanisms behind them. Although turbulence might help the stabilization of long-span bridges, and is thus not a conclusive parameter in wind-resistant design, turbulence effects on the aerodynamic and aeroelastic behaviors of a bridge need to be better understood because interaction between a bridge and turbulence always exists. This article also briefly introduces a newly developed multiple-fan wind tunnel that is designed to control turbulence to assist the study of turbulence effects.

  18. Understanding local residents of Korea using nuclear effective safety

    International Nuclear Information System (INIS)

    Chung, Yun Hyung; Lee, Gey Hwi; Hah, Yeonhee; Kim, Beom Jun

    2010-01-01

    The risk perception gap between experts and lay people is based on the use of different concept on risk. It is getting increasingly important for nuclear practitioners to understand the lay people's subjective perception on nuclear safety. We proposed the nuclear effective safety index (NESI) which is based on data of the public survey of local inhabitants. We extracted the four factors for effective safety indicators; communication, trust, plant emergency response capability, and personal emergency coping skills. The latest NESI was 41.54, which was increased from 38.22 but still low. The three-year data of NESI showed the differences between genders and between sites as well as trend. The survey of antecedents of effective safety showed some meaningful events and profound differences between plant employees and local inhabitants. The NESI can be utilized as useful communication tool between the local inhabitants and nuclear practitioners. (authors)

  19. 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…

  20. Using Concrete & Representational Experiences to Understand the Structure of DNA: A Four-Step Instructional Framework

    Science.gov (United States)

    Harrell, Pamela Esprivalo; Richards, Debbie; Collins, James; Taylor, Sarah

    2005-01-01

    A description of learning experience that uses a four-step instrumentational framework involving concrete and representational experiences to promote conceptual understanding of abstract biological concepts by a series of closely-related activities is presented. The students are introduced to the structure and implications of DNA using four…

  1. 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...

  2. 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…

  3. On the Conceptual Understanding of the Photoelectric Effect

    Science.gov (United States)

    Foong, S. K.; Lee, P.; Wong, D.; Chee, Y. P.

    2010-07-01

    We attempt an in-depth literature review that focuses on some finer aspects of the photoelectric effect that will help build a more coherent understanding of the phenomenon. These include the angular distribution of photoelectrons, multi-photon photoelectron emission and the work function in the photoelectric equation as being that associated with the collector rather than the emitter. We attempt to explain the intricacies of the related concepts in a way that is accessible to teachers and students at the Singapore GCE A-level or pre-university level.

  4. Understanding the Functions of Long Non-Coding RNAs through Their Higher-Order Structures

    Directory of Open Access Journals (Sweden)

    Rui Li

    2016-05-01

    Full Text Available Although thousands of long non-coding RNAs (lncRNAs have been discovered in eukaryotes, very few molecular mechanisms have been characterized due to an insufficient understanding of lncRNA structure. Therefore, investigations of lncRNA structure and subsequent elucidation of the regulatory mechanisms are urgently needed. However, since lncRNA are high molecular weight molecules, which makes their crystallization difficult, obtaining information about their structure is extremely challenging, and the structures of only several lncRNAs have been determined so far. Here, we review the structure–function relationships of the widely studied lncRNAs found in the animal and plant kingdoms, focusing on the principles and applications of both in vitro and in vivo technologies for the study of RNA structures, including dimethyl sulfate-sequencing (DMS-seq, selective 2′-hydroxyl acylation analyzed by primer extension-sequencing (SHAPE-seq, parallel analysis of RNA structure (PARS, and fragmentation sequencing (FragSeq. The aim of this review is to provide a better understanding of lncRNA biological functions by studying them at the structural level.

  5. Using Model Building in Structural Engineering to Enhance Understanding of Construction Principles and Methods

    Directory of Open Access Journals (Sweden)

    Niall Holmes

    2013-05-01

    Full Text Available This paper presents a new model building exercise in a second year module in the Department of Civil & Structural Engineering in the Dublin Institute of Technology (DIT. The activity aimed to improve students’ understanding of structural engineering, construction principles and methods. It allowed students to practically apply lecture material and construct a scaled model giving them an opportunity to study and visualise a real structure and generate their own ideas on how it should be assembled within a constructivist active learning environment. As a result, lectures were found to be more interactive and students more engaged in the discussions and provided a pathway to bridge the gap between theory (presented in lectures and the reality of their professions, which can aid them in their graduate careers. It is hoped that this type of active learning can be used in other engineering programmes to improve student understanding and as an opportunity to better apply lecture material to the real world.

  6. 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

    /C analogy. It is believed that the electronic transmutation concept will be effective and valuable in aiding the design of new boride materials with predictable properties. The study of boron clusters with intermediate properties between those of individual atoms and bulk solids has given rise to a unique opportunity to broaden the frontier of boron chemistry. Understanding boron clusters has spurred experimentalists and theoreticians to find new boron-based nanomaterials, such as boron fullerenes, nanotubes, two-dimensional boron, and new compounds containing boron clusters as building blocks. Here, a brief and timely overview is presented addressing the recent progress made on boron clusters and the approaches used in the authors’ laboratories to determine the structure, stability, and chemical bonding of size-selected boron clusters by joint photoelectron spectroscopy and theoretical studies. Specifically, key findings on all-boron hydrocarbon analogues, metal-centered boron wheels, and electronic transmutation in boron clusters are summarized.

  7. Understanding specificity in metabolic pathways--structural biology of human nucleotide metabolism.

    Science.gov (United States)

    Welin, Martin; Nordlund, Pär

    2010-05-21

    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. 2010. Published by Elsevier Inc.

  8. 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.

  9. Understanding the GPCR biased signaling through G protein and arrestin complex structures.

    Science.gov (United States)

    Zhou, X Edward; Melcher, Karsten; Xu, H Eric

    2017-08-01

    G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors and are important drug targets for many human diseases. The determination of the 3-D structure of GPCRs and their signaling complexes has promoted our understanding of GPCR biology and provided templates for structure-based drug discovery. In this review, we focus on the recent structure work on GPCR signaling complexes, the β2-adrenoreceptor-Gs and the rhodopsin-arrestin complexes in particular, and highlight the structural features of GPCR complexes involved in G protein- and arrestin-mediated signal transduction. The crystal structures reveal distinct structural mechanisms by which GPCRs recruit a G protein and an arrestin. A comparison of the two complex structures provides insight into the molecular mechanism of functionally selective GPCR signaling, and a structural basis for the discovery of G protein- and arrestin-biased treatments of human diseases related to GPCR signal transduction. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Understanding noise suppression in heterojunction field-effect transistors

    International Nuclear Information System (INIS)

    Green, F.

    1996-01-01

    Full text: The enhanced transport properties displayed by quantum-well-confined, two-dimensional, electron systems underpin the success of heterojunction, field-effect transistors. At cryogenic temperatures, these devices exhibit impressive mobilities and, as a result, high signal gain and low noise. Conventional wisdom has it that the same favourable conditions also hold for normal room-temperature operation. In that case, however, high mobilities are precluded by abundant electron-phonon scattering. Our recent study of nonequilibrium current noise shows that quantum confinement, not high mobility, is the principal source of noise in these devices; this opens up new and exciting opportunities in low-noise transistor design. As trends in millimetre-wave technology push frequencies beyond 100 GHz, it is essential to develop a genuine understanding of noise processes in heterojunction devices

  11. The Placebo Effect in Cardiology: Understanding and Using It.

    Science.gov (United States)

    Sheldon, Robert; Opie-Moran, Morwenna

    2017-12-01

    The placebo effect is the clinical benefit caused by interaction with a caregiver and health care system in the absence of a biologically active intervention and has been used successfully for millennia. The placebo response results from the interaction of psychosocial mechanisms, human relationships, and preconceptions functioning in specific neuroanatomic locations with known genes and neurotransmitters. It occurs with or without the administration of an inactive substance to deliberately deceive patients. Our purpose is to review the history, benefits, and mechanisms of the placebo effect. The placebo response results from classic conditioning and positive expectations about outcome expressed by the caregiver. The outcomes are usually symptoms such as pain rather than biological outcomes such as death, and the powerful placebo may account for more than half the effect of treatment in many situations. The placebo effect results from activation of opioid, cannabinoid, and dopaminergic pathways involved in reward, expectancy, conditioning, and pain modulation. Eleven specific anatomic features in the brain identified by positron emission tomography and magnetic resonance imaging are involved. Polymorphisms in the structural genes for catecholamine O-methyltransferase and fatty acid amide oxidase significantly influence the placebo response. The placebo effect may be important in symptom suppression in angina, paroxysmal atrial fibrillation, and congestive heart failure. In the absence of deliberate deception, there are no ethical issues and given its potency, the time has come to consider how best to use the placebo in clinical practice. Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    Barak, Miri; Hussein-Farraj, Rania

    2013-04-01

    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 model-based learning and animations of biomolecules affect students' chemical understanding. Applying the mixed methods research paradigm, pre- and post-questionnaires as well as class-observations were employed in the collection, analysis, and interpretation of data. The research population included 175 grade twelve students, divided into three research groups: (a) hands-on exploration of animations, (b) teacher's demonstrations of animations, (c) traditional learning using textbooks. Findings indicated that the integration of model-based learning and 3D animations enhanced students' understanding of proteins' structure and function and their ability to transfer across different levels of chemistry understanding. Findings also indicated that teachers' demonstrations of animations may enhance students' `knowledge'—a low order thinking skill; however, in order to enhance higher levels of thinking, students should be able to explore 3D animations on their own. Applying constructivist and interpretative analysis of the data, three themes were raised, corresponding to cognitive, affective, and social aspects of learning while exploring web-based models and animations.

  13. The Pathology of structure of explanations in understanding of literary texts

    Directory of Open Access Journals (Sweden)

    Mahyar Alavi Moghaddam

    2011-02-01

    Full Text Available Abstract Traditional and non-scientific classification shade to educational and research Persian literature and literary education and research haven't grown up. The aim of explanation of text is to rub off difficulties and to lead reader to deep understanding. In semantics studies of understanding and interpretation of text, to familiar with the place of meaning in literary tradition and new approaches of criticism, the acceptance of multi meaning in interpretation texts are necessary. The role of interpreter is very important, because he can relate between the world of text and the world of reader and so between semantic horizon of writer and poet and mental horizon.   We can step in analysing interpretation of Hafez' poem and pathology of this area, because of expanding of research about Hafez and his explanations. There are four difficulties in these explanations: structural, semantic, lexical and figural. In this article, we will pay attention to just structural difficulties. These structural difficulties are unversatility system, incomprehensiveness, nonalaystic of explanations, mistake methods in educating and to ignore relation between Hafez's Verses in semantic texture of Ghazal. Certainly, it is necessary to pay scientific, analytic criticism in Hafez's explanations as one of the areas in understanding of his poems.

  14. Compreendendo o Efeito Placebo / Understanding the Placebo Effect

    Directory of Open Access Journals (Sweden)

    Elayne Vieira Dias

    2015-12-01

    Full Text Available Placebo é definido em termos farmacológicos como uma substância inerte, sem propriedades farmacológicas intrínsecas. No entanto, essa definição é superficial, visto que o placebo pode gerar efeitos terapêuticos que dependem de diversos fatores como palavras, rituais, símbolos e significados que acompanham seu uso. Assim, o efeito placebo não diz respeito apenas a uma substância, mas, envolve fatores cognitivos, genéticos e mecanismos de aprendizagem implícita e explícita. Nessa revisão nós abordamos os aspectos gerais do efeito placebo apoiados em diversos estudos com diferentes enfoques, visando uma melhor compreensão desse fenômeno que pode se somar ao tratamento ativo e otimizar os resultados na prática médica. Placebo is pharmacologically defined as an inert substance, with nointrinsic pharmacological properties. However, this is a superficial definition, since placebo may trigger therapeutic effects and its effectiveness depends on various factors such as words, rituals, symbols and meanings following its use. Thus, placebo effect does not refer just to the substance, but it also involves cognitive and genetic factors and learning mechanisms. Here, we review general aspects of the placebo effect supported by several studies with different approaches, to better understand this phenomenon which may contribute to active treatment as well as optimize the results in the clinical practice.

  15. 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

  16. Physical models have gender‐specific effects on student understanding of protein structure–function relationships

    Science.gov (United States)

    Harris, Michelle A.; Chang, Wesley S.; Dent, Erik W.; Nordheim, Erik V.; Franzen, Margaret A.

    2016-01-01

    Abstract Understanding how basic structural units influence function is identified as a foundational/core concept for undergraduate biological and biochemical literacy. It is essential for students to understand this concept at all size scales, but it is often more difficult for students to understand structure–function relationships at the molecular level, which they cannot as effectively visualize. Students need to develop accurate, 3‐dimensional mental models of biomolecules to understand how biomolecular structure affects cellular functions at the molecular level, yet most traditional curricular tools such as textbooks include only 2‐dimensional representations. We used a controlled, backward design approach to investigate how hand‐held physical molecular model use affected students' ability to logically predict structure–function relationships. Brief (one class period) physical model use increased quiz score for females, whereas there was no significant increase in score for males using physical models. Females also self‐reported higher learning gains in their understanding of context‐specific protein function. Gender differences in spatial visualization may explain the gender‐specific benefits of physical model use observed. © 2016 The Authors Biochemistry and Molecular Biology Education published by Wiley Periodicals, Inc. on behalf of International Union of Biochemistry and Molecular Biology, 44(4):326–335, 2016. PMID:26923186

  17. Understanding Effects of Traumatic Insults on Brain Structure and Function

    Science.gov (United States)

    2016-08-01

    modeled via cable equations.76 Electrical activity within each neuronal compartment was simulated using up to 15 distinct Hodgkin - Huxley type voltage...and potassium. Hodgkin - Huxley -like simulations of neuronal electrical activity include a term to represent the passive permeability of the neuronal...conditions were used for the face that has the piston. The opposing face and the boundaries in the x and y dimensions are fixed. The simulation

  18. Multifunctional light escaping architecture inspired by compound eye surface structures: From understanding to experimental demonstration.

    Science.gov (United States)

    Song, Young Min; Park, Gyeong Cheol; Jang, Sung Jun; Ha, Jong Hoon; Yu, Jae Su; Lee, Yong Tak

    2011-03-14

    We present bioinspired artificial compound eye surface structures that consist of antireflective subwavelength structures (SWSs) on hexagonally patterned microstructures (MSs), for the purpose of efficient light escaping inside light-emitting materials/devices. Theoretical understanding and geometrical optimization of SWSs on MSs are described together with rigorous coupled-wave analysis. As a proof of this concept, AlGaInP red light-emitting diodes (LEDs) with SWS/MSs were fabricated, and a light output power enhancement of 72.47% was achieved as compared to that of conventional LEDs. The artificial compound eye structures are not limited to LEDs, and the fabrication process is compatible with most semiconductor device manufacturing processes; hence, this concept opens up new possibilities for improving the optical performance of various optoelectronic device applications.

  19. Molecular Modeling of Enzyme Dynamics Towards Understanding Solvent Effects

    DEFF Research Database (Denmark)

    Wedberg, Nils Hejle Rasmus Ingemar

    ) in water and organic solvents. The effects of solvent on structural and dynamical enzyme properties are studied, and special attention is given to how enzyme properties in organic solvents are affected by the hydration level, which is shown to be related to the water activity. In experimental studies...... of enzyme kinetics in non-aqueous media, it has been a fruitful approach to fix the enzyme hydration level by controlling the water activity of the medium. In this work, a protocol is therefore developed for determining the water activity in non-aqueous protein simulations. The method relies on determining......This thesis describes the development of a molecular simulation methodology to study properties of enzymes in non-aqueous media at fixed thermodynamic water activities. The methodology is applied in a molecular dynamics study of the industrially important enzyme Candida antarctica lipase B (CALB...

  20. 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.

  1. Understanding human thiol dioxygenase enzymes: structure to function, and biology to pathology.

    Science.gov (United States)

    Sarkar, Bibekananda; Kulharia, Mahesh; Mantha, Anil K

    2017-04-01

    Amino acid metabolism is a significant metabolic activity in humans, especially of sulphur-containing amino acids, methionine and cysteine (Cys). Cys is cytotoxic and neurotoxic in nature; hence, mammalian cells maintain a constant intracellular level of Cys. Metabolism of Cys is mainly regulated by two thiol dioxygenases: cysteine dioxygenase (CDO) and 2-aminoethanethiol dioxygenase (ADO). CDO and ADO are the only human thiol dioxygenases reported with a role in Cys metabolism and localized to mitochondria. This metabolic pathway is important in various human disorders, as it is responsible for the synthesis of antioxidant glutathione and is also for the synthesis of hypotaurine and taurine. CDO is the most extensively studied protein, whose high-resolution crystallographic structures have been solved. As compared to CDO, ADO is less studied, even though it has a key role in cysteamine metabolism. To further understand ADO's structure and function, the three-dimensional structures have been predicted from I-TASSER and SWISS-MODEL servers and validated with PROCHECK software. Structural superimposition approach using iPBA web server further confirmed near-identical structures (including active sites) for the predicted protein models of ADO as compared to CDO. In addition, protein-protein interaction and their association in patho-physiology are crucial in understanding protein functions. Both ADO and CDO interacting partner profiles have been presented using STRING database. In this study, we have predicted a 3D model structure for ADO and summarized the biological roles and the pathological consequences which are associated with the altered expression and functioning of ADO and CDO in case of cancer, neurodegenerative disorders and other human diseases. © 2017 The Authors. International Journal of Experimental Pathology © 2017 International Journal of Experimental Pathology.

  2. 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

  3. Understanding Sulfide Capacity of Molten Aluminosilicates via Structural Information from 'Raman' and 'NMR' Spectroscopic Methodologies

    Science.gov (United States)

    Park, Joo Hyun

    The effect of Ca-Mn substitution on the sulfide capacity of the MnO-CaO-SiO2 (-Al2O3-MgO) melts were explained from the Raman scattering data, from which the structure information for the network modifying role and sulfur stabilizing role of Ca2+ and Mn2+ ions were obtained. The effect of Ce2O3 on the sulfide capacity of the MnO-SiO2-Al2O3-Ce2O3 melts were understood based on the structure data, from which the charge compensating role of Ce3+ and the amphoteric behavior of alumina were obtained. Employing the structure analysis, the thermochemical properties such as capacity of the oxide melts with no thermodynamic data can be understood in terms of `composition-structure-property' relationship.

  4. 3D lidar imaging for detecting and understanding plant responses and canopy structure.

    Science.gov (United States)

    Omasa, Kenji; Hosoi, Fumiki; Konishi, Atsumi

    2007-01-01

    Understanding and diagnosing plant responses to stress will benefit greatly from three-dimensional (3D) measurement and analysis of plant properties because plant responses are strongly related to their 3D structures. Light detection and ranging (lidar) has recently emerged as a powerful tool for direct 3D measurement of plant structure. Here the use of 3D lidar imaging to estimate plant properties such as canopy height, canopy structure, carbon stock, and species is demonstrated, and plant growth and shape responses are assessed by reviewing the development of lidar systems and their applications from the leaf level to canopy remote sensing. In addition, the recent creation of accurate 3D lidar images combined with natural colour, chlorophyll fluorescence, photochemical reflectance index, and leaf temperature images is demonstrated, thereby providing information on responses of pigments, photosynthesis, transpiration, stomatal opening, and shape to environmental stresses; these data can be integrated with 3D images of the plants using computer graphics techniques. Future lidar applications that provide more accurate dynamic estimation of various plant properties should improve our understanding of plant responses to stress and of interactions between plants and their environment. Moreover, combining 3D lidar with other passive and active imaging techniques will potentially improve the accuracy of airborne and satellite remote sensing, and make it possible to analyse 3D information on ecophysiological responses and levels of various substances in agricultural and ecological applications and in observations of the global biosphere.

  5. 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.

  6. Understanding the structural drivers governing glass-water interactions in borosilicate based model bioactive glasses.

    Science.gov (United States)

    Stone-Weiss, Nicholas; Pierce, Eric M; Youngman, Randall E; Gulbiten, Ozgur; Smith, Nicholas J; Du, Jincheng; Goel, Ashutosh

    2018-01-01

    The past decade has witnessed a significant upsurge in the development of borate and borosilicate based resorbable bioactive glasses owing to their faster degradation rate in comparison to their silicate counterparts. However, due to our lack of understanding about the fundamental science governing the aqueous corrosion of these glasses, most of the borate/borosilicate based bioactive glasses reported in the literature have been designed by "trial-and-error" approach. With an ever-increasing demand for their application in treating a broad spectrum of non-skeletal health problems, it is becoming increasingly difficult to design advanced glass formulations using the same conventional approach. Therefore, a paradigm shift from the "trial-and-error" approach to "materials-by-design" approach is required to develop new-generations of bioactive glasses with controlled release of functional ions tailored for specific patients and disease states, whereby material functions and properties can be predicted from first principles. Realizing this goal, however, requires a thorough understanding of the complex sequence of reactions that control the dissolution kinetics of bioactive glasses and the structural drivers that govern them. While there is a considerable amount of literature published on chemical dissolution behavior and apatite-forming ability of potentially bioactive glasses, the majority of this literature has been produced on silicate glass chemistries using different experimental and measurement protocols. It follows that inter-comparison of different datasets reveals inconsistencies between experimental groups. There are also some major experimental challenges or choices that need to be carefully navigated to unearth the mechanisms governing the chemical degradation behavior and kinetics of boron-containing bioactive glasses, and to accurately determine the composition-structure-property relationships. In order to address these challenges, a simplified

  7. Understanding the Global Structure and Evolution of Coronal Mass Ejections in the Solar Wind

    Science.gov (United States)

    Riley, Pete

    2004-01-01

    This report summarizes the technical progress made during the first six months of the second year of the NASA Living with a Star program contract Understanding the global structure and evolution of coronal mass ejections in the solar wind, between NASA and Science Applications International Corporation, and covers the period November 18, 2003 - May 17,2004. Under this contract SAIC has conducted numerical and data analysis related to fundamental issues concerning the origin, intrinsic properties, global structure, and evolution of coronal mass ejections in the solar wind. During this working period we have focused on a quantitative assessment of 5 flux rope fitting techniques. In the following sections we summarize the main aspects of this work and our proposed investigation plan for the next reporting period. Thus far, our investigation has resulted in 6 refereed scientific publications and we have presented the results at a number of scientific meetings and workshops.

  8. A Study to Understand the Potential Vulnerabilities to the Foundations of Historic Structures in Coastal Areas

    Science.gov (United States)

    Hall, C. L.; Curran, B.; Jefferson, M.; Routhier, M.; Mulukutla, G. K.

    2011-12-01

    Sea level rise, one of the most important manifestations of climate change is expected to result in increased coastal erosion and storm surge flooding. This work reports on a project undertaken to assess the vulnerability of foundations of historic structures in coastal areas to the potential consequences from climate change resulting from increased storm surge flooding. Foundations of historic buildings are especially vulnerable to the seepage and ground water intrusion. Many historic structures themselves are used to house valuable historic collections making it all the important to preserve and protect these structures. Data collected from a field subsurface geophysical survey, geospatial field survey, and a simulation to understand the hydrological conditions of the site useful to build an understanding of threats to foundations of historic structures located on the coast. The study site chosen for this project is the Strawbery Banke Living History Museum, in Portsmouth, NH. Located very close to the banks of the Piscataqua River at its meeting point with the Atlantic Ocean, it consists of many buildings of historical importance dating as far back as 1690. Upstream of the river is the tidal estuary system, the Great Bay which itself is formed by a confluence of seven major rivers, making it a highly dynamic, tide-dominated body of fresh and saltwater. Strawbery Banke is representative of historic structures, located on the Northeastern coast of the US, that will likely be impacted by climate change. The primary threat to the sub-structures for the site is Puddle Dock; a tidal inlet , that lies at the heart of the facility, that once provided direct river access to Strawbery Banke (and since filled around 1900). Results from the long term deployment of in -situ water level loggers in test wells, temperature and relative humidity sensors, and a ground penetration radar survey of the Puddle Dock, along with the detailed fine-scale elevation survey of the site

  9. 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

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

    Science.gov (United States)

    Arnau, Gemma; Bhattacharjee, Ranjana; Mn, Sheela; Chair, Hana; Malapa, Roger; 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.

  11. Capacity mechanisms and effects on market structure

    International Nuclear Information System (INIS)

    Elberg, Christina; Kranz, Sebastian

    2014-01-01

    Liberalized electricity markets are characterized by fluctuating priceinelastic demand of non-storable electricity, often defined by a substantial market share held by one or few incumbent firms. These characteristics have led to a controversial discussion concerning the need for and the design of capacity mechanisms, which combine some form of capacity payments with price caps in the spot market. The purpose of this study is to understand the effects of capacity mechanisms on the market structure. We consider a model with dominant firms and a competitive fringe and investigate the impact of price caps and capacity payments on investment incentives and market concentration. While lower price caps reduce the potential for the exercise of market power in static models, we find that in the dynamic model with endogenous investments, lower price caps result in an increase in market concentration, the frequency of capacity withholding and the profits of the dominant firms.

  12. A Life Course Approach to Understanding Neighbourhood Effects

    NARCIS (Netherlands)

    de Vuijst, E.; van Ham, M.; Kleinhans, R.J.

    2016-01-01

    Many theories on so-called neighbourhood effectseffects of the residential context on individual outcomes such as employment, education, and health – implicitly, or explicitly suggest lagged effects, duration effects, or for example, intergenerational effects of neighbourhoods. However, these

  13. Understanding and tuning the quantum-confinement effect and edge magnetism in zigzag graphene nanoribbon.

    Science.gov (United States)

    Huang, Liang Feng; Zhang, Guo Ren; Zheng, Xiao Hong; Gong, Peng Lai; Cao, Teng Fei; Zeng, Zhi

    2013-02-06

    The electronic structure of zigzag graphene nanoribbon (ZGNR) is studied using density functional theory. The mechanisms underlying the quantum-confinement effect and edge magnetism in ZGNR are systematically investigated by combining the simulated results and some useful analytic models. The quantum-confinement effect and the inter-edge superexchange interaction can be tuned by varying the ribbon width, and the spin polarization and direct exchange splitting of the edge states can be tuned by varying their electronic occupations. The two edges of ZGNR can be equally or unequally tuned by charge doping or Li adsorption, respectively. The Li adatom has a site-selective adsorption on ZGNR, and it is a nondestructive and memorable approach to effectively modify the edge states in ZGNR. These systematic understanding and effective tuning of ZGNR electronics presented in this work are helpful for further investigation and application of ZGNR and other magnetic graphene systems.

  14. 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......’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...... and thus address the dearth of literature on the micro foundations of parties. Whilst the underlying conceptualization of a political market orientation draws on the management-based ‘relationship marketing’ approach, we acknowledge that the commercial and political contexts are not isomorphic, and thus we...

  15. 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).

  16. 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.

  17. Understanding the reaction of nuclear graphite with molecular oxygen: Kinetics, transport, and structural evolution

    Science.gov (United States)

    Kane, Joshua J.; Contescu, Cristian I.; Smith, Rebecca E.; Strydom, Gerhard; Windes, William E.

    2017-09-01

    For the next generation of nuclear reactors, HTGRs specifically, an unlikely air ingress warrants inclusion in the license applications of many international regulators. Much research on oxidation rates of various graphite grades under a number of conditions has been undertaken to address such an event. However, consequences to the reactor result from the microstructural changes to the graphite rather than directly from oxidation. The microstructure is inherent to a graphite's properties and ultimately degradation to the graphite's performance must be determined to establish the safety of reactor design. To understand the oxidation induced microstructural change and its corresponding impact on performance, a thorough understanding of the reaction system is needed. This article provides a thorough review of the graphite-molecular oxygen reaction in terms of kinetics, mass and energy transport, and structural evolution: all three play a significant role in the observed rate of graphite oxidation. These provide the foundations of a microstructurally informed model for the graphite-molecular oxygen reaction system, a model kinetically independent of graphite grade, and capable of describing both the observed and local oxidation rates under a wide range of conditions applicable to air-ingress.

  18. Understanding the inverse magnetocaloric effect in antiferro- and ferrimagnetic arrangements

    International Nuclear Information System (INIS)

    Von Ranke, P J; De Oliveira, N A; Alho, B P; Plaza, E J R; De Sousa, V S R; Caron, L; Reis, M S

    2009-01-01

    The inverse magnetocaloric effect occurs when a magnetic material cools down under applied magnetic field in an adiabatic process. Although the existence of the inverse magnetocaloric effect was recently reported experimentally, a theoretical microscopic description is almost nonexistent. In this paper we theoretically describe the inverse magnetocaloric effect in antiferro- and ferrimagnetic systems. The inverse magnetocaloric effects were systematically investigated as a function of the model parameters. The influence of the Neel and the compensation temperature on the magnetocaloric effect is also analyzed using a microscopic model.

  19. Understanding the inverse magnetocaloric effect in antiferro- and ferrimagnetic arrangements

    Energy Technology Data Exchange (ETDEWEB)

    Von Ranke, P J; De Oliveira, N A; Alho, B P; Plaza, E J R; De Sousa, V S R [Instituto de Fisica ' Armando Dias Tavares' , Universidade do Estado do Rio de Janeiro-UERJ, Rua Sao Francisco Xavier, 524, 20550-013, RJ (Brazil); Caron, L [Instituto de Fisica ' Gleb Wataghin' , Universidade Estadual de Campinas-UNICAMP, 13083-970 Campinas, SP (Brazil); Reis, M S [CICECO, Universidade de Aveiro, 3810-193 Aveiro (Portugal)], E-mail: von.ranke@uol.com.br

    2009-02-04

    The inverse magnetocaloric effect occurs when a magnetic material cools down under applied magnetic field in an adiabatic process. Although the existence of the inverse magnetocaloric effect was recently reported experimentally, a theoretical microscopic description is almost nonexistent. In this paper we theoretically describe the inverse magnetocaloric effect in antiferro- and ferrimagnetic systems. The inverse magnetocaloric effects were systematically investigated as a function of the model parameters. The influence of the Neel and the compensation temperature on the magnetocaloric effect is also analyzed using a microscopic model.

  20. 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

  1. 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

  2. Probing The Structure North China To Better Understand Its Evolution, Natural Resources, And Seismic Hazards (Invited)

    Science.gov (United States)

    Keller, G. R.; Gao, R.; Qu, G.; Li, Q.; Liu, M.

    2010-12-01

    also recorded across the southern portion of this array. This profile crossed a region where the 3 main faults that pose the major hazard to the city are expressed at the surface. Some shots along this profile were also recorded by the 3-D array, and an earthquake occurred along the edge of the array during one of recording windows. Together, these data are producing an improved understanding of the structure of this area and will aid hazard assessments. These efforts are also being used a basis to conduct comparative studies to better understand seismic hazards in the central U.S. and the tectonic evolution of both regions.

  3. 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…

  4. Towards an understanding of staggering effects in dissipative binary collisions

    International Nuclear Information System (INIS)

    D'Agostino, M.; Bruno, M.; Gulminelli, F.; Morelli, L.; Baiocco, G.; Bardelli, L.; Barlini, S.; Cannata, F.; Casini, G.; Geraci, E.; Gramegna, F.; Kravchuk, V.L.; Marchi, T.; Moroni, A.; Ordine, A.; Raduta, Ad.R.

    2012-01-01

    The reactions 32 S+ 58,64 Ni are studied at 14.5 A MeV. Evidence is found for important odd–even effects in isotopic observables of selected peripheral collisions corresponding to the decay of a projectile-like source. The influence of secondary decays on the staggering is studied with a correlation function technique. It is shown that this method is a powerful tool to get experimental information on the evaporation chain, in order to constrain model calculations. Specifically, we show that odd–even effects are due to interplay between pairing effects in the nuclear masses and in the level densities.

  5. Understanding and Applying the Cognitive Foundations of Effective Teamwork

    National Research Council Canada - National Science Library

    Noble, David

    2004-01-01

    .... It reviews a theory describing the knowledge that teams need to work together effectively and summarizing how teams use this knowledge when making decisions about collecting and sharing information...

  6. THE Blast-Wave-Driven Instability as a Vehicle for Understanding Supernova Explosion Structure

    Science.gov (United States)

    Miles, Aaron R.

    2009-05-01

    Blast-wave-driven instabilities play a rich and varied role in supernovae (SNe) evolution from explosion to remnant, but interpreting their role is difficult due to the enormous complexity of stellar systems. We consider the simpler idealized problem of an interface between two constant-density fluids perturbed from spherical and driven by a central blast wave. Where valid, the existence of unified solutions suggests that general conclusions can be drawn about the likely asymptotic structure of the mixing zone. To this end, we apply buoyancy-drag and bubble merger models that include effects of divergence and compressibility. In general, these effects preclude the true self-similar evolution of classical Rayleigh-Taylor (RT), but can be incorporated into a quasi-self-similar growth model. Loss of memory of initial conditions (ICs) can occur in the model, but requires pre-explosion mode numbers higher than predicted for Type II SNe, suggesting that their late-time structure is influenced by details of the initial perturbations. Where low modes dominate, as in the Type Ia Tycho remnant, they result from initial perturbations rather than generation from smaller scales. Therefore, the structure observed now contains direct information about the explosion process. When large-amplitude modes exist in the ICs, the contribution from the Richtmyer-Meshkov (RM) instability is significant compared to RT. Such RM growth can yield proximity of the forward shock to the growing spikes and structure that strongly resembles that observed in Tycho. Laser-driven laboratory experiments offer a promising avenue for testing model and simulation descriptions of blast-wave-driven instabilities and making connections to their astrophysical counterparts.

  7. Understanding the inverse magnetocaloric effect through a simple theoretical model

    Energy Technology Data Exchange (ETDEWEB)

    Ranke, P.J. von, E-mail: von.ranke@uol.com.b [Instituto de Fisica Armando Dias Tavares-Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier, 524, Rio de Janeiro 20550-013 (Brazil); Alho, B.P.; Nobrega, E.P.; Oliveira, N.A. de [Instituto de Fisica Armando Dias Tavares-Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier, 524, Rio de Janeiro 20550-013 (Brazil)

    2009-10-15

    We investigated the inverse magnetocaloric effect using a theoretical magnetic model formed by two coupled magnetic lattices to describe a ferrimagnetic system. The influence of the compensation temperature, and the ferrimagnetic-paramagnetic phase transition on the magnetocaloric effect was analyzed. Also, a relation between the area under the magnetocaloric curve and the net magnetic moment of a ferrimagnetic system was established in this work.

  8. Graphene nanoribbons on gold: understanding superlubricity and edge effects

    Science.gov (United States)

    Gigli, L.; Manini, N.; Benassi, A.; Tosatti, E.; Vanossi, A.; Guerra, R.

    2017-12-01

    We address the atomistic nature of the longitudinal static friction against sliding of graphene nanoribbons (GNRs) deposited on gold, a system whose structural and mechanical properties have been recently the subject of intense experimental investigation. By means of numerical simulations and modeling we show that the GNR interior is structurally lubric (‘superlubric’) so that the static friction is dominated by the front/tail regions of the GNR, where the residual uncompensated lateral forces arising from the interaction with the underneath gold surface opposes the free sliding. As a result of this edge pinning the static friction does not grow with the GNR length, but oscillates around a fairly constant mean value. These friction oscillations are explained in terms of the GNR-Au(111) lattice mismatch: at certain GNR lengths close to an integer number of the beat (or moiré) length there is good force compensation and superlubric sliding; whereas close to half odd-integer periods there is significant pinning of the edge with larger friction. These results make qualitative contact with recent state-of-the-art atomic force microscopy experiment, as well as with the sliding of other different incommensurate systems.

  9. Urban Ecological Stewardship: Understanding the Structure, Function and Network of Community-based Urban Land Management

    Directory of Open Access Journals (Sweden)

    Lindsay K. Campbell

    2008-01-01

    Full Text Available 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 urban land managers, an assessment was conducted in 2004 by the research subcommittee of the Urban Ecology Collaborative. The goal of the assessment was to better understand the role of stewardship organizations engaged in urban ecology initiatives in selected major cities in the Northeastern U.S.: Boston, New Haven, New York City, Pittsburgh, Baltimore, and Washington, D.C. A total of 135 active organizations participated in this assessment. Findings include the discovery of a dynamic social network operating within cities, and a reserve of social capital and expertise that could be better utilized. Although often not the primary land owner, stewardship groups take an increasingly significant responsibility for a wide range of land use types including street and riparian corridors, vacant lots, public parks and gardens, green roofs, etc. Responsibilities include the delivery of public programs as well as daily maintenance and fundraising support. While most of the environmental stewardship organizations operate on staffs of zero or fewer than ten, with small cohorts of community volunteers, there is a significant difference in the total amount of program funding. Nearly all respondents agree that committed resources are scarce and insufficient with stewards relying upon and potentially competing for individual donations, local foundations, and municipal support. This makes it a challenge for the groups to grow beyond their current capacity and to develop long-term programs critical to resource management and education. It also fragments groups, making it difficult for planners and

  10. 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.

  11. 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.

  12. Understanding fluxes as media for directed synthesis: in situ local structure of molten potassium polysulfides.

    Science.gov (United States)

    Shoemaker, Daniel P; Chung, Duck Young; Mitchell, J F; Bray, Travis H; Soderholm, L; Chupas, Peter J; Kanatzidis, Mercouri G

    2012-06-06

    Rational exploratory synthesis of new materials requires routes to discover novel phases and systematic methods to tailor their structures and properties. Synthetic reactions in molten fluxes have proven to be an excellent route to new inorganic materials because they promote diffusion and can serve as an additional reactant, but little is known about the mechanisms of compound formation, crystal precipitation, or behavior of fluxes themselves at conditions relevant to synthesis. In this study we examine the properties of a salt flux system that has proven extremely fertile for growth of new materials: the potassium polysulfides spanning K(2)S(3) and K(2)S(5), which melt between 302 and 206 °C. We present in situ Raman spectroscopy of melts between K(2)S(3) and K(2)S(5) and find strong coupling between n in K(2)S(n) and the molten local structure, implying that the S(n)(2-) chains in the crystalline state are mirrored in the melt. In any reactive flux system, K(2)S(n) included, a signature of changing species in the melt implies that their evolution during a reaction can be characterized and eventually controlled for selective formation of compounds. We use in situ X-ray total scattering to obtain the pair distribution function of molten K(2)S(5) and model the length of S(n)(2-) chains in the melt using reverse Monte Carlo simulations. Combining in situ Raman and total scattering provides a path to understanding the behavior of reactive media and should be broadly applied for more informed, targeted synthesis of compounds in a wide variety of inorganic fluxes.

  13. Understanding Graduate School Aspirations: The Effect of Good Teaching Practices

    Science.gov (United States)

    Hanson, Jana M.; Paulsen, Michael B.; Pascarella, Ernest T.

    2016-01-01

    This study examined the effects of good teaching practices on post-baccalaureate degree aspirations using logistic regression techniques on a multi-institutional, longitudinal sample of students at 4-year colleges and universities in the USA. We examined whether eight good teaching practices (non-classroom interactions with faculty, prompt…

  14. Understanding the stabilizing effects of IT on organizations

    NARCIS (Netherlands)

    Boogaard, Martin; Huysman, Marleen H.

    1994-01-01

    In the literature, two distinct ways in which the application of IT stabilizes organizations are indicated. The first stabilizing effect concerns the difficult, time-consuming, and costly adjustments of existing ISs when changes to ISs have to be made. Consequently, when circumstances change

  15. Assessing Teacher Quality: Understanding Teacher Effects on Instruction and Achievement

    Science.gov (United States)

    Kelly, Sean, Ed.

    2011-01-01

    Recent educational reforms have promoted accountability systems which attempt to identify "teacher effects" on student outcomes and hold teachers accountable for producing learning gains. But in the complex world of classrooms, it may be difficult to attribute "success" or "failure" to teachers. In this timely…

  16. Understanding the Effects of Climate on Airfield Pavement Deterioration Rates

    Science.gov (United States)

    2013-03-01

    eliminating frost susceptible materials frost heave effects can be minimized. Using properly designed asphalt binders that perform well in cold...processes that operate on or near the surface of our planet ” (de Smith, Goodchild, & Longley, 2007). Spatial interpolation is a spatial analysis

  17. Understanding why probiotic therapies can be effective in treating IBD.

    Science.gov (United States)

    Fedorak, Richard N

    2008-09-01

    Probiotics, for the treatment of inflammatory bowel disease, are a group of specific nonpathogenic bacteria that are functionally and genetically defined by their ability to reduce inflammation in the intestine. Although probiotics also seem to have broad beneficial effects in humans, both as a food and as a therapeutic agent, there are specific identified mechanisms in some, but not all, of these bacteria that are important relative to the pathogenesis of inflammatory bowel disease. Recently, studies relative to the mechanism of action of probiotics have identified that these organisms can have a direct effect on epithelial cell function and intestinal health, including enhancing epithelial barrier function, modulating epithelial cytokine secretion into an anti-inflammatory dominant profile, altering mucus production, changing bacterial luminal flora, modifying the innate and systemic immune system, and inducing regulatory T-cell effects. For probiotics to have a therapeutic role in the management of clinical inflammatory bowel disease, their therapeutic mechanism of action must be aligned with the pathogenic mechanism of action of the disease. In this regard, the role of probiotics for the clinical treatment of inflammatory bowel disease is emerging as the mechanisms and pathogenesis are being unraveled. It remains clear that probiotics are able to reduce gastrointestinal inflammation by exerting positive effects on epithelial cell and mucosal immune dysfunction.

  18. Improving Food Production by Understanding the Effects of ...

    African Journals Online (AJOL)

    This paper quantifies the effects of population density and intercropping on the development and growth of nitrogen fixing attributes of soybean and explains how these attributes influence food through yielding process. Information for this study was obtained from a field study conducted over two rainy seasons comprising of ...

  19. Understanding Effectiveness in School Administration: A Discourse Analysis

    Science.gov (United States)

    Büyükgöze, Hilal

    2016-01-01

    The current paper primarily aims to investigate and interpret the observations, perceptions, and experiences of an effective school's principal through a qualitative approach. The study was designed as a case study. The participant of the study was a primary science education teacher with 17 years of experience in the profession who has been a…

  20. Understanding electromagnetic effects using printed circuit board demos

    NARCIS (Netherlands)

    Buesink, Frederik Johannes Karel; Leferink, Frank Bernardus Johannes

    2009-01-01

    Electromagnetic fields are considered by many students as a difficult subject. Unwanted electromagnetic fields are even tougher for students. We have developed many experiments as demonstrations (demos) to show the effect of electromagnetic fields in real life products. This paper gives a brief

  1. Understanding the effects of end-loss on linear Fresnelcollectors

    Science.gov (United States)

    Ma, Jing; Chang, Zheng

    2018-02-01

    In this paper, the end loss effect of linear Fresnel collector was analyzed. The aim of this work was to investigate the seasonal effects of end losses on the linear Fresnel collectors deployed, and analyze the change of the month average for end loss at different locations. Furthermore, a end loss compensated approach is proposed, and the increased instantaneous thermal efficiency of the experimental system is measured. A two-meter long linear Fresnel collector experimental system with horizontal north-south axis is performed, The result that compensation of the end loss of the linear Fresnel reflector system stands a good improvement for thermal performance. Meanwhile, in comparison with the reflector field prior to the change, an instantaneous thermal efficiency has increased by approximately 50%, and it increased by almost 20% at the afternoon time. All this work can offer some valuable references to the further study on high-efficiency linear Fresnel concentrating system.

  2. Understanding substituent effects in noncovalent interactions involving aromatic rings.

    Science.gov (United States)

    Wheeler, Steven E

    2013-04-16

    Noncovalent interactions involving aromatic rings such as π-stacking, cation/π, and anion/π interactions are central to many areas of modern chemistry. Decades of experimental studies have provided key insights into the impact of substituents on these interactions, leading to the development of simple intuitive models. However, gas-phase computational studies have raised some doubts about the physical underpinnings of these widespread models. In this Account we review our recent efforts to unravel the origin of substituent effects in π-stacking and ion/π interactions through computational studies of model noncovalent dimers. First, however, we dispel the notion that so-called aromatic interactions depend on the aromaticity of the interacting rings by studying model π-stacked dimers in which the aromaticity of one of the monomers can be "switched off". Somewhat surprisingly, the results show that not only is aromaticity unnecessary for π-stacking interactions, but it actually hinders these interactions to some extent. Consequently, when thinking about π-stacking interactions, researchers should consider broader classes of planar molecules, not just aromatic systems. Conventional models maintain that substituent effects in π-stacking interactions result from changes in the aryl π-system. This view suggests that π-stacking interactions are maximized when one ring is substituted with electron-withdrawing groups and the other with electron donors. In contrast to these prevailing models, we have shown that substituent effects in π-stacking interactions can be described in terms of direct, local interactions between the substituents and the nearby vertex of the other arene. As a result, in polysubstituted π-stacked dimers the substituents operate independently unless they are in each other's local environment. This means that in π-stacked dimers in which one arene is substituted with electron donors and the other with electron acceptors the interactions will

  3. Structure-Based Understanding of Binding Affinity and Mode of Estrogen Receptor α Agonists and Antagonists.

    Directory of Open Access Journals (Sweden)

    Sehan Lee

    Full Text Available The flexible hydrophobic ligand binding pocket (LBP of estrogen receptor α (ERα allows the binding of a wide variety of endocrine disruptors. Upon ligand binding, the LBP reshapes around the contours of the ligand and stabilizes the complex by complementary hydrophobic interactions and specific hydrogen bonds with the ligand. Here we present a framework for quantitative analysis of the steric and electronic features of the human ERα-ligand complex using three dimensional (3D protein-ligand interaction description combined with 3D-QSAR approach. An empirical hydrophobicity density field is applied to account for hydrophobic contacts of ligand within the LBP. The obtained 3D-QSAR model revealed that hydrophobic contacts primarily determine binding affinity and govern binding mode with hydrogen bonds. Several residues of the LBP appear to be quite flexible and adopt a spectrum of conformations in various ERα-ligand complexes, in particular His524. The 3D-QSAR was combined with molecular docking based on three receptor conformations to accommodate receptor flexibility. The model indicates that the dynamic character of the LBP allows accommodation and stable binding of structurally diverse ligands, and proper representation of the protein flexibility is critical for reasonable description of binding of the ligands. Our results provide a quantitative and mechanistic understanding of binding affinity and mode of ERα agonists and antagonists that may be applicable to other nuclear receptors.

  4. 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.

  5. IMPORTANCE OF FULL COULOMB INTERACTIONS FOR UNDERSTANDING THE ELECTRONIC STRUCTURE OF DELTA-Pu

    Energy Technology Data Exchange (ETDEWEB)

    Gorelov, E; Kolorenc, J; Wehling, T; Hafermann, H; Lichtenstein, A I; Shick, A B; Rubtsov, A N; Katsnelson, M I; Landa, A; McMahan, A K

    2010-04-01

    The solid-state properties of most elements are now well understood on the basis of quantum physics - with few exceptions, notably the element number 94, plutonium. Plutonium has six crystalline phases at ambient pressure, some of which are separated by unusual phase transitions with large discontinuities in volume, exhibit negative thermal expansion coefficients, or form exotic low-symmetry structures. The main challenge to explain these anomalous properties is that the characteristic ingredient of actinides, the 5f electronic states, are in the cross-over regime between the localized and delocalized (itinerant) behaviour in Pu. The early part of the actinide series with the 5f states being itinerant, i.e. part of the metallic bond, culminates with Pu; starting with Am (Z = 95), the 5f states are localized, nonbonding, and resemble the 4f states in lanthanides. Both itinerant and localized regimes are well covered by existing theories, but they cannot be simply interpolated due to the importance of dynamical electron-electron correlations. Here we present accurate quantum Monte Carlo calculations achieving previously inaccessible resolution. Obtained results demonstrate that interplay of the full Coulomb interaction vertex with spin-orbital coupling is crucial for understanding the experimentally observed spectral properties of plutonium near the Fermi level.

  6. Understanding the effects of violent video games on violent crime

    OpenAIRE

    Cunningham, A. Scott; Engelstätter, Benjamin; Ward, Michael R.

    2011-01-01

    Psychological studies invariably find a positive relationship between violent video game play and aggression. However, these studies cannot account for either aggressive effects of alternative activities video game playing substitutes for or the possible selection of relatively violent people into playing violent video games. That is, they lack external validity. We investigate the relationship between the prevalence of violent video games and violent crimes. Our results are consistent with t...

  7. Retention in STEM: Understanding the Effectiveness of Science Posse

    Science.gov (United States)

    Godsoe, Kimberly

    One of the major areas of debate in higher education is how to best support underrepresented racial minority students in their study of Science, Technology, Engineering, and Math. In 2008, Brandeis University began a new program in conjunction with the Posse Foundation for students interested in studying science at the college-level. The research used a mixed methods design. A detailed quantitative analysis was conducted to understand how being part of Science Posse impacted the probability of doing well in initial science classes, influenced perceptions of the difficulty of studying science, and predicted the probability of majoring in STEM at Brandeis. The qualitative data was drawn from 89 student interviews, including 38 Science Posse Scholars, 24 students from backgrounds similar to the Scholars, and 25 students from well-resourced families. The qualitative analysis demonstrated how students had been exposed to the sciences prior to enrollment, how they navigated the sciences at Brandeis, and how they demonstrated resilience when science becomes challenging. This research study had four key findings. The first was in the quantitative analysis which demonstrated that Science Posse Scholars experience strong feelings of doubt about their academic abilities; based on previous research, this should have resulted in their not declaring majors in STEM disciplines. Instead, Science Posse Scholars were more likely to earn a B+ or above in their entry level science courses and declare a major in a STEM discipline, even when factors such as math and verbal SAT scores were included in the analysis. The second finding was in the qualitative analysis, which demonstrated that the cohort model in which Science Posse Scholars participate was instrumental to their success. The third finding was that students who attended academically less rigorous high schools could succeed in the sciences at a highly selective research institution such as Brandeis without academic remediation

  8. Radiation effects on structural materials

    International Nuclear Information System (INIS)

    Ghoniem, N.M.

    1991-01-01

    This report discusses the following topics on the effect radiation has on thermonuclear reactor materials: Atomic Displacements; Microstructure Evolution; Materials Engineering, Mechanics, and Design; Research on Low-Activation Steels; and Research Motivated by Grant Support

  9. Understanding the Effects of Marriage and Divorce on Financial Investments

    DEFF Research Database (Denmark)

    Christiansen, Charlotte; Joensen, Juanna Schröter; Rangvid, Jesper

    2015-01-01

    We investigate how changes in marital status affect financial investments and how these effects vary with background risk. We use detailed register-based panel data and difference-in-differences estimators to benchmark common unobserved influences on financial investments. Women increase...... is important for financial risk taking and investment responses to marital transitions....... the fraction of wealth invested in stocks after marriage and decrease it after divorce, whereas men show the opposite behavior. Households whose joint labor income risk is reduced more by marriage have a higher increase in their exposure to risky assets in marriage. Thus income risk sharing in the household...

  10. Understanding cavity QED effects from cavity classical electrodynamics

    International Nuclear Information System (INIS)

    Taddei, M.M.; Kort-Kamp, W.J.M.; Farina, C.

    2011-01-01

    Full text: Our work intends to show how cavity classical electrodynamics can be used for achieving results with direct quantum analogues. It is shown how the classical interaction between a real radiating electric dipole and a perfectly-conducting surface can be used to obtain information about some cavity quantum electrodynamics effects related to radiative properties of atomic systems. Based on the case of an oscillating electric dipole (a classical representation of an excited atom) in front of a perfectly-conducting sphere, two main physical quantities can be computed, the classical dipole frequency shift and the change in the rate of energy loss from radiation reaction, both due to the presence of the sphere. The link from classical to quantum can be made via interpreting, for example, the dipole frequency as the atom's dominant transition frequency. The frequency shift due to the sphere can be related through E = (h/2π) to the energy shift of the system, i.e., the dispersive interaction between the atom and the sphere; while the change in energy loss can be related to the alteration of the atom's spontaneous emission due to the sphere. The amazing result is that this classical method, once corresponded classical quantities to quantum ones such as exemplified above with frequency, can predict the two above-mentioned quantum effects analytically with the correct functional dependencies on all geometric and atomic parameters, being off only by a constant pre factor. (author)

  11. Understanding the "Weekend Effect" for Emergency General Surgery.

    Science.gov (United States)

    Hoehn, Richard S; Go, Derek E; Dhar, Vikrom K; Kim, Young; Hanseman, Dennis J; Wima, Koffi; Shah, Shimul A

    2018-02-01

    Several studies have identified a "weekend effect" for surgical outcomes, but definitions vary and the cause is unclear. Our aim was to better characterize the weekend effect for emergency general surgery using mortality as a primary endpoint. Using data from the University HealthSystem Consortium from 2009 to 2013, we identified urgent/emergent hospital admissions for seven procedures representing 80% of the national burden of emergency general surgery. Patient characteristics and surgical outcomes were compared between cases that were performed on weekdays vs weekends. Hospitals varied widely in the proportion of procedures performed on the weekend. Of the procedures examined, four had higher mortality for weekend cases (laparotomy, lysis of adhesions, partial colectomy, and small bowel resection; p surgery (p surgery procedures that incur higher mortality when performed on weekends. This may be due to acute changes in patient status that require weekend surgery or indications for urgent procedures (ischemia, obstruction) compared to those without a weekend mortality difference (infection). Hospitals that perform weekend surgery must acknowledge and identify ways to manage this increased risk.

  12. Current Understanding of the Health Effects of Electromagnetic Fields.

    Science.gov (United States)

    Miah, Tayaba; Kamat, Deepak

    2017-04-01

    There has been an exponential increase in the use of electronic devices over the past few decades. This has led to increased exposure to electromagnetic fields (EMF). Electric fields result from differences in voltage, whereas magnetic fields result from the flow of electric current. Higher-frequency waves of EMF have more energy than lower-frequency waves, and thus generally tend to be more harmful. An EMF activates cellular stress response and also causes breaks in DNA strands. There are many methodological barriers to effectively measuring the associations of EMF and childhood cancers. The consensus from multiple studies is that there is no causal role of extremely low-frequency EMFs in childhood cancers, including brain cancer. A recent study showed a link between EMF radiation and the development of malignant tumors in rats. In light of that study, the American Academy of Pediatrics set out new recommendations to decrease the adverse effects of cellphone exposure on children. [Pediatr Ann. 2017;46(4):e172-e174.]. Copyright 2017, SLACK Incorporated.

  13. Understanding Soliton Spectral Tunneling as a Spectral Coupling Effect

    DEFF Research Database (Denmark)

    Guo, Hairun; Wang, Shaofei; Zeng, Xianglong

    2013-01-01

    Soliton eigenstate is found corresponding to a dispersive phase profile under which the soliton phase changes induced by the dispersion and nonlinearity are instantaneously counterbalanced. Much like a waveguide coupler relying on a spatial refractive index profile that supports mode coupling...... between channels, here we suggest that the soliton spectral tunneling effect can be understood supported by a spectral phase coupler. The dispersive wave number in the spectral domain must have a coupler-like symmetric profile for soliton spectral tunneling to occur. We show that such a spectral coupler...... exactly implies phase as well as group-velocity matching between the input soliton and tunneled soliton, namely a soliton phase matching condition. Examples in realistic photonic crystal fibers are also presented....

  14. Stochastic models of cellular circadian rhythms in plants help to understand the impact of noise on robustness and clock structure

    Directory of Open Access Journals (Sweden)

    Maria Luisa eGuerriero

    2014-10-01

    Full Text Available Rhythmic behavior is essential for plants; for example, daily (circadian rhythms control photosynthesis and seasonal rhythms regulate their life cycle. The core of the circadian clock is a genetic network that coordinates the expression of specific clock genes in a circadian rhythm reflecting the 24-hour day/night cycle.Circadian clocks exhibit stochastic noise due to the low copy numbers of clock genes and the consequent cell-to-cell variation: this intrinsic noise plays a major role in circadian clocks by inducing more robust oscillatory behavior. Another source of noise is the environment, which causes variation in temperature and light intensity: this extrinsic noise is part of the requirement for the structural complexity of clock networks.Advances in experimental techniques now permit single-cell measurements and the development of single-cell models. Here we present some modeling studies showing the importance of considering both types of noise in understanding how plants adapt to regular and irregular light variations. Stochastic models have proven useful for understanding the effect of regular variations. By contrast, the impact of irregular variations and the interaction of different noise sources are less studied.

  15. Stochastic models of cellular circadian rhythms in plants help to understand the impact of noise on robustness and clock structure

    Science.gov (United States)

    Guerriero, Maria L.; Akman, Ozgur E.; van Ooijen, Gerben

    2014-01-01

    Rhythmic behavior is essential for plants; for example, daily (circadian) rhythms control photosynthesis and seasonal rhythms regulate their life cycle. The core of the circadian clock is a genetic network that coordinates the expression of specific clock genes in a circadian rhythm reflecting the 24-h day/night cycle. Circadian clocks exhibit stochastic noise due to the low copy numbers of clock genes and the consequent cell-to-cell variation: this intrinsic noise plays a major role in circadian clocks by inducing more robust oscillatory behavior. Another source of noise is the environment, which causes variation in temperature and light intensity: this extrinsic noise is part of the requirement for the structural complexity of clock networks. Advances in experimental techniques now permit single-cell measurements and the development of single-cell models. Here we present some modeling studies showing the importance of considering both types of noise in understanding how plants adapt to regular and irregular light variations. Stochastic models have proven useful for understanding the effect of regular variations. By contrast, the impact of irregular variations and the interaction of different noise sources are less well studied. PMID:25374576

  16. Understanding the Structure-Function Relationships of Dendrimers in Environmental and Biomedical Applications

    Science.gov (United States)

    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

  17. Structural and effective connectivity in focal epilepsy

    Directory of Open Access Journals (Sweden)

    Christopher S. Parker

    2018-01-01

    Full Text Available Patients with medically-refractory focal epilepsy may be candidates for neurosurgery and some may require placement of intracranial EEG electrodes to localise seizure onset. Assessing cerebral responses to single pulse electrical stimulation (SPES may give diagnostically useful data. SPES produces cortico-cortical evoked potentials (CCEPs, which infer effective brain connectivity. Diffusion-weighted images and tractography may be used to estimate structural brain connectivity. This combination provides the opportunity to observe seizure onset and its propagation throughout the brain, spreading contiguously along the cortex explored with electrodes, or non-contiguously. We analysed CCEPs and diffusion tractography in seven focal epilepsy patients and reconstructed the effective and structural brain networks. We aimed to assess the inter-modal similarity of the networks at a large scale across the cortex, the effective and structural connectivity of the ictal-onset zone, and investigate potential mechanisms of non-contiguous seizure spread. We found a significant overlap between structural and effective networks. Effective network CCEP amplitude, baseline variation, and outward connectivity was higher at ictal-onset zones, while structural connection strength within the ictal-onset zone tended to be higher. These findings support the concept of hyperexcitable cortex being associated with seizure generation. The high prevalence of structural and effective connections from the ictal-onset zone to sites of non-contiguous spread suggests that macroscopic structural and effective connections are plausible routes for non-contiguous seizure spread.

  18. Understanding barotrauma in fish passing hydro structures: a global strategy for sustainable development of water resources

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Richard S.; Colotelo, Alison HA; Pflugrath, Brett D.; Boys, Craig A.; Baumgartner, Lee J.; Deng, Zhiqun; Silva, Luiz G.; Brauner, Colin J.; Mallen-Cooper, Martin; Phonekhampeng, Oudom; Thorncraft, Garry; Singhanouvong, Douangkham

    2014-03-24

    Freshwater fishes are one of the most imperiled groups of vertebrates and species declines have been linked to a number of anthropogenic influences. This is alarming as the diversity and stability of populations are at risk. In addition, freshwater fish serve as important protein sources, particularly in developing countries. One of the focal activities thought to influence freshwater fish population declines is water resource development, which is anticipated to increase over the next several decades. For fish encountering hydro structures, such as passing through hydroturbines, there may be a rapid decrease in pressure which can lead to injuries commonly referred to as barotraumas. The authors summarize the research to date that has examined the effects of rapid pressure changes on fish and outline the most important factors to consider (i.e., swim bladder morphology, depth of acclimation, migration pattern and life stage) when examining the susceptibility of barotraumas for fish of interest.

  19. Understanding ligand effects in gold clusters using mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Grant E.; Laskin, Julia

    2016-01-01

    This review summarizes recent research on the influence of phosphine ligands on the size, stability, and reactivity of gold clusters synthesized in solution. Sub-nanometer clusters exhibit size- and composition-dependent properties that are unique from those of larger nanoparticles. The highly tunable properties of clusters and their high surface-to-volume ratio make them promising candidates for a variety of technological applications. However, because “each-atom-counts” toward defining cluster properties it is critically important to develop robust synthesis methods to efficiently prepare clusters of predetermined size. For decades phosphines have been known to direct the size-selected synthesis of gold clusters. Despite the preparation of numerous species it is still not understood how different functional groups at phosphine centers affect the size and properties of gold clusters. Using electrospray ionization mass spectrometry (ESI-MS) it is possible to characterize the effect of ligand substitution on the distribution of clusters formed in solution at defined reaction conditions. In addition, ligand exchange reactions on preformed clusters may be monitored using ESI-MS. Collision induced dissociation (CID) may also be employed to obtain qualitative insight into the fragmentation of mixed ligand clusters and the relative binding energies of differently substituted phosphines. Quantitative ligand binding energies and cluster stability may be determined employing surface induced dissociation (SID) in a custom-built Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS). Rice-Ramsperger-Kassel-Marcus (RRKM) based modeling of the SID data allows dissociation energies and entropy values to be extracted that may be compared with the results of high-level theoretical calculations. The charge reduction and reactivity of atomically precise gold clusters, including partially ligated species generated in the gas-phase by in source CID, on well

  20. Understanding ligand effects in gold clusters using mass spectrometry.

    Science.gov (United States)

    Johnson, Grant E; Laskin, Julia

    2016-06-21

    This review summarizes recent research on the influence of phosphine ligands on the size, stability, and reactivity of gold clusters synthesized in solution. Sub-nanometer clusters exhibit size- and composition-dependent properties that are unique from those of larger nanoparticles. The highly tunable properties of clusters and their high surface-to-volume ratio make them promising candidates for a variety of technological applications. However, because "each-atom-counts" toward defining cluster properties it is critically important to develop robust synthesis methods to efficiently prepare clusters of predetermined size. For decades phosphines have been known to direct the size-selected synthesis of gold clusters. Despite the preparation of numerous species it is still not understood how different functional groups at phosphine centers affect the size and properties of gold clusters. Using electrospray ionization mass spectrometry (ESI-MS) it is possible to characterize the effect of ligand substitution on the distribution of clusters formed in solution at defined reaction conditions. In addition, ligand exchange reactions on preformed clusters may be monitored using ESI-MS. Collision induced dissociation (CID) may also be employed to obtain qualitative insight into the fragmentation of mixed ligand clusters and the relative binding energies of differently substituted phosphines. Quantitative ligand binding energies and cluster stability may be determined employing surface induced dissociation (SID) in a custom-built Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS). Rice-Ramsperger-Kassel-Marcus (RRKM) based modeling of the SID data allows dissociation energies and entropy values to be extracted. The charge reduction and reactivity of atomically precise gold clusters, including partially ligated species generated in the gas-phase by in source CID, on well-defined surfaces may be explored using ion soft landing (SL) in a custom

  1. Modeling and understanding of effects of randomness in arrays of resonant meta-atoms

    DEFF Research Database (Denmark)

    Tretyakov, Sergei A.; Albooyeh, Mohammad; Alitalo, Pekka

    2013-01-01

    In this review presentation we will discuss approaches to modeling and understanding electromagnetic properties of 2D and 3D lattices of small resonant particles (meta-atoms) in transition from regular (periodic) to random (amorphous) states. Nanostructured metasurfaces (2D) and metamaterials (3D......) are arrangements of optically small but resonant particles (meta-atoms). We will present our results on analytical modeling of metasurfaces with periodical and random arrangements of electrically and magnetically resonant meta-atoms with identical or random sizes, both for the normal and oblique-angle excitations....... We show how the electromagnetic response of metasurfaces is related to the statistical parameters of the structure. Furthermore, we will discuss the phenomenon of anti-resonance in extracted effective parameters of metamaterials and clarify its relation to the periodicity (or amorphous nature...

  2. 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.

  3. Understanding the Effects of Host Evolution and Skin Bacteria Composition on Disease Vector Choices

    Science.gov (United States)

    2016-04-14

    Distribution Unlimited UU UU UU UU 14-04-2016 1-Sep-2014 31-Dec-2015 Final Report: Understanding the effects of host evolution and skin bacteria...reviewed journals: Final Report: Understanding the effects of host evolution and skin bacteria composition on disease vector choices Report Title Here...SECURITY CLASSIFICATION OF: Here we sought to understand how host biology influences the composition of skin microbes, how skin microbes influence

  4. Understanding influential factors on implementing green supply chain management practices: An interpretive structural modelling analysis.

    Science.gov (United States)

    Agi, Maher A N; Nishant, Rohit

    2017-03-01

    In this study, we establish a set of 19 influential factors on the implementation of Green Supply Chain Management (GSCM) practices and analyse the interaction between these factors and their effect on the implementation of GSCM practices using the Interpretive Structural Modelling (ISM) method and the "Matrice d'Impacts Croisés Multiplication Appliquée à un Classement" (MICMAC) analysis on data compiled from interviews with supply chain (SC) executives based in the Gulf countries (Middle East region). The study reveals a strong influence and driving power of the nature of the relationships between SC partners on the implementation of GSCM practices. We especially found that dependence, trust, and durability of the relationship with SC partners have a very high influence. In addition, the size of the company, the top management commitment, the implementation of quality management and the employees training and education exert a critical influence on the implementation of GSCM practices. Contextual elements such as the industry sector and region and their effect on the prominence of specific factors are also highlighted through our study. Finally, implications for research and practice are discussed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. 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.

  6. Effective spacetime understanding emergence in effective field theory and quantum gravity

    CERN Document Server

    Crowther, Karen

    2016-01-01

    This book discusses the notion that quantum gravity may represent the "breakdown" of spacetime at extremely high energy scales. If spacetime does not exist at the fundamental level, then it has to be considered "emergent", in other words an effective structure, valid at low energy scales. The author develops a conception of emergence appropriate to effective theories in physics, and shows how it applies (or could apply) in various approaches to quantum gravity, including condensed matter approaches, discrete approaches, and loop quantum gravity.

  7. Understanding characteristics in multivariate traffic flow time series from complex network structure

    Science.gov (United States)

    Yan, Ying; Zhang, Shen; Tang, Jinjun; Wang, Xiaofei

    2017-07-01

    Discovering dynamic characteristics in traffic flow is the significant step to design effective traffic managing and controlling strategy for relieving traffic congestion in urban cities. A new method based on complex network theory is proposed to study multivariate traffic flow time series. The data were collected from loop detectors on freeway during a year. In order to construct complex network from original traffic flow, a weighted Froenius norm is adopt to estimate similarity between multivariate time series, and Principal Component Analysis is implemented to determine the weights. We discuss how to select optimal critical threshold for networks at different hour in term of cumulative probability distribution of degree. Furthermore, two statistical properties of networks: normalized network structure entropy and cumulative probability of degree, are utilized to explore hourly variation in traffic flow. The results demonstrate these two statistical quantities express similar pattern to traffic flow parameters with morning and evening peak hours. Accordingly, we detect three traffic states: trough, peak and transitional hours, according to the correlation between two aforementioned properties. The classifying results of states can actually represent hourly fluctuation in traffic flow by analyzing annual average hourly values of traffic volume, occupancy and speed in corresponding hours.

  8. Revisiting the structure, age, and evolution of the Wharton Basin to better understand subduction under Indonesia.

    Digital Repository Service at National Institute of Oceanography (India)

    Jacob, J.; Dyment, J.; Yatheesh, V.

    Understanding the subduction processes along the Sunda Trench requires detailed constraints on the subducting lithosphere. We build a detailed tectonic map of the Wharton Basin based on reinterpretation of satellite-derived gravity anomalies...

  9. TOWARD AN IMPROVED UNDERSTANDING OF STRUCTURE AND MAGNETISM IN NEPTUNIUM AND PLUTONIUM PHOSPHONATES AND SULFONATES

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht-Schmitt, Thomas

    2012-03-01

    This grant supported the exploratory synthesis of new actinide materials with all of the actinides from thorium to californium with the exceptions of protactinium and berkelium. We developed detailed structure-property relationships that allowed for the identification of novel materials with selective ion-exchange, selective oxidation, and long-range magnetic ordering. We found novel bonding motifs and identified periodic trends across the actinide series. We identified structural building units that would lead to desired structural features and novel topologies. We also characterized many different spectroscopic trends across the actinide series. The grant support the preparation of approximately 1200 new compounds all of which were structurally characterized.

  10. 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,…

  11. Structural characteristics and antihypertensive effects of angiotensin ...

    African Journals Online (AJOL)

    Structural characteristics and antihypertensive effects of angiotensin-iconverting enzyme inhibitory peptides in the renin-angiotensin and kallikrein kinin systems. ... Background: The commercially available synthetic angiotensin-I-converting enzyme (ACE) inhibitors are known to exert negative side effects which have driven ...

  12. Centrifuge modelling of seismic soil structure interaction effects

    International Nuclear Information System (INIS)

    Ghosh, B.; Madabhushi, S.P.G.

    2007-01-01

    Proper understanding of the role of unbounded soil in the evaluation of dynamic soil structure interaction (SSI) problem is very important for structures used in the nuclear industry. In this paper, the results from a series of dynamic centrifuge tests are reported. These tests were performed on different types of soil stratifications supporting a rigid containment structure. Test results indicate that accelerations transmitted to the structure's base are dependent on the stiffness degradation in the supporting soil. Steady build up of excess pore pressure leads to softening of the soil, which decreases the shear modulus and shear strength and subsequently changes the dynamic responses. It is also shown that the presence of the structure reduces the translational component of the input base motion and induces rocking of the structure. The test results are compared with some standard formulae used for evaluating interaction in the various building codes. It was concluded that the dynamic shear modulus values used should be representative of the site conditions and can vary dramatically due to softening. Damping values used are still very uncertain and contain many factors, which cannot be accounted in the experiments. It is emphasized that simplified design processes are important to gain an insight into the behaviour of the physical mechanism but for a complete understanding of the SSI effects sophisticated methods are necessary to account for non-linear behaviour of the soil material

  13. Primary Student-Teachers' Conceptual Understanding of the Greenhouse Effect: A mixed method study

    Science.gov (United States)

    Ratinen, Ilkka Johannes

    2013-04-01

    The greenhouse effect is a reasonably complex scientific phenomenon which can be used as a model to examine students' conceptual understanding in science. Primary student-teachers' understanding of global environmental problems, such as climate change and ozone depletion, indicates that they have many misconceptions. The present mixed method study examines Finnish primary student-teachers' understanding of the greenhouse effect based on the results obtained via open-ended and closed-form questionnaires. The open-ended questionnaire considers primary student-teachers' spontaneous ideas about the greenhouse effect depicted by concept maps. The present study also uses statistical analysis to reveal respondents' conceptualization of the greenhouse effect. The concept maps and statistical analysis reveal that the primary student-teachers' factual knowledge and their conceptual understanding of the greenhouse effect are incomplete and even misleading. In the light of the results of the present study, proposals for modifying the instruction of climate change in science, especially in geography, are presented.

  14. 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...

  15. Bernoulli's Principle: The Effects of Instruction on Young Children's Understanding of Flight.

    Science.gov (United States)

    Fleege, Pamela O.; And Others

    This study examined the effects of hands-on instruction on young children's understanding of an aspect of flight, specifically Bernoulli's principle. First, 137 public school children, ages 5 through 8 years, were interviewed about their understanding of how an airplane flies. Two weeks later, the subjects participated in two hands-on…

  16. Improving Elementary School Students' Understanding of Historical Time: Effects of Teaching with "Timewise"

    Science.gov (United States)

    de Groot-Reuvekamp, Marjan; Ros, Anje; van Boxtel, Carla

    2018-01-01

    The teaching of historical time is an important aspect in elementary school curricula. This study focuses on the effects of a curriculum intervention with "Timewise," a teaching approach developed to improve students' understanding of historical time using timelines as a basis with which students can develop their understanding of…

  17. Surface Structure of Silver Nanoparticles as a Model for Understanding the Oxidative Dissolution of Silver Ions

    NARCIS (Netherlands)

    Molleman, Bastiaan; Hiemstra, Tjisse

    2015-01-01

    The toxicity of silver nanoparticles (AgNPs) has been related to the release of ionic silver. This process is influenced by a large variety of factors and is poorly understood. The key to understanding Ag+ release by AgNPs is its subvalency. This is a fundamental property of Ag that

  18. A Phenomenographic Study of the Ways of Understanding Conditional and Repetition Structures in Computer Programming Languages

    Science.gov (United States)

    Bucks, Gregory Warren

    2010-01-01

    Computers have become an integral part of how engineers complete their work, allowing them to collect and analyze data, model potential solutions and aiding in production through automation and robotics. In addition, computers are essential elements of the products themselves, from tennis shoes to construction materials. An understanding of how…

  19. Soil-structure interaction studies for understanding the behavior of integral abutment bridges.

    Science.gov (United States)

    2012-03-01

    Integral Abutment Bridges (IAB) are bridges without any joints within the bridge deck or between the : superstructure and the abutments. An IAB provides many advantages during construction and maintenance of : a bridge. Soil-structure interactions at...

  20. Understanding nanocellulose chirality and structure-properties relationship at the single fibril level

    Science.gov (United States)

    Usov, Ivan; Nyström, Gustav; Adamcik, Jozef; Handschin, Stephan; Schütz, Christina; Fall, Andreas; Bergström, Lennart; Mezzenga, Raffaele

    2015-06-01

    Nanocellulose fibrils are ubiquitous in nature and nanotechnologies but their mesoscopic structural assembly is not yet fully understood. Here we study the structural features of rod-like cellulose nanoparticles on a single particle level, by applying statistical polymer physics concepts on electron and atomic force microscopy images, and we assess their physical properties via quantitative nanomechanical mapping. We show evidence of right-handed chirality, observed on both bundles and on single fibrils. Statistical analysis of contours from microscopy images shows a non-Gaussian kink angle distribution. This is inconsistent with a structure consisting of alternating amorphous and crystalline domains along the contour and supports process-induced kink formation. The intrinsic mechanical properties of nanocellulose are extracted from nanoindentation and persistence length method for transversal and longitudinal directions, respectively. The structural analysis is pushed to the level of single cellulose polymer chains, and their smallest associated unit with a proposed 2 × 2 chain-packing arrangement.

  1. Novel targeted approach to better understand how natural structural barriers govern carotenoid in vitro bioaccessibility in vegetable-based systems.

    Science.gov (United States)

    Palmero, Paola; Lemmens, Lien; Ribas-Agustí, Albert; Sosa, Carola; Met, Kristof; de Dieu Umutoni, Jean; Hendrickx, Marc; Van Loey, Ann

    2013-12-01

    An experimental approach, allowing us to understand the effect of natural structural barriers (cell walls, chromoplast substructures) on carotenoid bioaccessibility, was developed. Different fractions with different levels of carotenoid bio-encapsulation (carotenoid-enriched oil, chromoplasts, small cell clusters, and large cell clusters) were isolated from different types of carrots and tomatoes. An in vitro method was used to determine carotenoid bioaccessibility. In the present work, a significant decrease in carotenoid in vitro bioaccessibility could be observed with an increasing level of bio-encapsulation. Differences in cell wall material and chromoplast substructure between matrices influenced carotenoid release and inclusion in micelles. For carrots, cell walls and chromoplast substructure were important barriers for carotenoid bioaccessibility while, in tomatoes, the chromoplast substructure represented the most important barrier governing bioaccessibility. The highest increase in carotenoid bioaccessibility, for all matrices, was obtained after transferring carotenoids into the oil phase, a system lacking cell walls and chromoplast substructures that could hamper carotenoid release. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Understanding the structural transformation, stability of medium-sized neutral and charged silicon clusters

    Science.gov (United States)

    Ding, Li Ping; Zhang, Fang Hui; Zhu, Yong Sheng; Lu, Cheng; Kuang, Xiao Yu; Lv, Jian; Shao, Peng

    2015-01-01

    The structural and electronic properties for the global minimum structures of medium-sized neutral, anionic and cationic Sinμ (n = 20–30, μ = 0, −1 and +1) clusters have been studied using an unbiased CALYPSO structure searching method in conjunction with first-principles calculations. A large number of low-lying isomers are optimized at the B3PW91/6-311 + G* level of theory. Harmonic vibrational analysis has been performed to assure that the optimized geometries are stable. The growth behaviors clearly indicate that a structural transition from the prolate to spherical-like geometries occurs at n = 26 for neutral silicon clusters, n = 27 for anions and n = 25 for cations. These results are in good agreement with the available experimental and theoretical predicted findings. In addition, no significant structural differences are observed between the neutral and cation charged silicon clusters with n = 20–24, both of them favor prolate structures. The HOMO-LUMO gaps and vertical ionization potential patterns indicate that Si22 is the most chemical stable cluster, and its dynamical stability is deeply discussed by the vibrational spectra calculations. PMID:26526519

  3. Toward a Demographic Understanding of Incarceration Disparities: Race, Ethnicity, and Age Structure.

    Science.gov (United States)

    Vogel, Matt; Porter, Lauren C

    2016-01-01

    Non-Hispanic blacks and Hispanics in the United States are more likely to be incarcerated than non-Hispanic whites. The risk of incarceration also varies with age, and there are striking differences in age distributions across racial/ethnic groups. Guided by these trends, the present study examines the extent to which differences in age structure account for incarceration disparities across racial and ethnic groups. We apply two techniques commonly employed in the field of demography, age-standardization and decomposition, to data provided by the Bureau of Justice Statistics and the 2010 decennial census to assess the contribution of age structure to racial and ethnic disparities in incarceration. The non-Hispanic black and Hispanic incarceration rates in 2010 would have been 13-20 % lower if these groups had age structures identical to that of the non-Hispanic white population. Moreover, age structure accounts for 20 % of the Hispanic/white disparity and 8 % of the black/white disparity. The comparison of crude incarceration rates across racial/ethnic groups may not be ideal because these groups boast strikingly different age structures. Since the risk of imprisonment is tied to age, criminologists should consider adjusting for age structure when comparing rates of incarceration across groups.

  4. EFFECTIVE HYPERFINE-STRUCTURE FUNCTIONS OF AMMONIA

    International Nuclear Information System (INIS)

    Augustovičová, L.; Soldán, P.; Špirko, V.

    2016-01-01

    The hyperfine structure of the rotation-inversion ( v 2 = 0 + , 0 − , 1 + , 1 − ) states of the 14 NH 3 and 15 NH 3 ammonia isotopomers is rationalized in terms of effective (ro-inversional) hyperfine-structure (hfs) functions. These are determined by fitting to available experimental data using the Hougen’s effective hyperfine-structure Hamiltonian within the framework of the non-rigid inverter theory. Involving only a moderate number of mass independent fitting parameters, the fitted hfs functions provide a fairly close reproduction of a large majority of available experimental data, thus evidencing adequacy of these functions for reliable prediction. In future experiments, this may help us derive spectroscopic constants of observed inversion and rotation-inversion transitions deperturbed from hyperfine effects. The deperturbed band centers of ammonia come to the forefront of fundamental physics especially as the probes of a variable proton-to-electron mass ratio.

  5. Incorporating modeling and simulations in undergraduate biophysical chemistry course to promote understanding of structure-dynamics-function relationships in proteins.

    Science.gov (United States)

    Hati, Sanchita; Bhattacharyya, Sudeep

    2016-01-01

    A project-based biophysical chemistry laboratory course, which is offered to the biochemistry and molecular biology majors in their senior year, is described. In this course, the classroom study of the structure-function of biomolecules is integrated with the discovery-guided laboratory study of these molecules using computer modeling and simulations. In particular, modern computational tools are employed to elucidate the relationship between structure, dynamics, and function in proteins. Computer-based laboratory protocols that we introduced in three modules allow students to visualize the secondary, super-secondary, and tertiary structures of proteins, analyze non-covalent interactions in protein-ligand complexes, develop three-dimensional structural models (homology model) for new protein sequences and evaluate their structural qualities, and study proteins' intrinsic dynamics to understand their functions. In the fourth module, students are assigned to an authentic research problem, where they apply their laboratory skills (acquired in modules 1-3) to answer conceptual biophysical questions. Through this process, students gain in-depth understanding of protein dynamics-the missing link between structure and function. Additionally, the requirement of term papers sharpens students' writing and communication skills. Finally, these projects result in new findings that are communicated in peer-reviewed journals. © 2016 The International Union of Biochemistry and Molecular Biology.

  6. 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.

  7. Understanding regional scale structural uncertainty: The onshore Gulf of Corinth Rift as a hydrocarbon exploration analogue

    OpenAIRE

    Wood, AM; Paton, DA; Collier, REL; O'Connor, V

    2015-01-01

    A major challenge when exploring for hydrocarbons in frontier areas is a lack of data coverage. Data may be restricted to regional scale 2D seismic lines, from which assumptions of the 3D geometric configuration are drawn. Understanding the limitations and uncertainties when extrapolating 2D data into 3D space is crucial when assessing the requirements for acquiring additional data such as 3D seismic or exploration wells, and of assigning geologically reasonable uncertainty ranges. The Onshor...

  8. Understanding NOx SCR Mechanism and Activity on Cu/Chabazite Structures throughout the Catalyst Life Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Fabio; Delgass, Nick; Gounder, Rajmani; Schneider, William F.; Miller, Jeff; Yezerets, Aleksey; McEwen, Jean-Sabin; Peden, Charles HF; Howden, Ken

    2014-12-09

    Oxides of nitrogen (NOx) compounds contribute to acid rain and photochemical smog and have been linked to respiratory ailments. NOx emissions regulations continue to tighten, driving the need for high performance, robust control strategies. The goal of this project is to develop a deep, molecular level understanding of the function of Cu-SSZ-13 and Cu-SAPO-34 materials that catalyze the SCR of NOx with NH3.

  9. Students' Perceived Understanding Mediates the Effects of Teacher Clarity and Nonverbal Immediacy on Learner Empowerment

    Science.gov (United States)

    Finn, Amber N.; Schrodt, Paul

    2012-01-01

    This study examined students' perceived understanding as a mediator of the relationship between student perceptions of teacher clarity, nonverbal immediacy cues, and learner empowerment (i.e., meaningfulness, competence, and impact). Participants included 261 undergraduate students who completed survey instruments. Results of structural equation…

  10. Improved understanding of moisture effects on outdoor wood–adhesive bondlines

    Science.gov (United States)

    Joseph E. Jakes; Nayomi Plaza-Rodriguez; Xavier Arzola Villegas; Charles R. Frihart

    2017-01-01

    The development of improved moisture-durable wood adhesives for outdoor applications, such as repairing historic covered bridges, is hindered by an incomplete mechanistic understanding of what makes a wood–adhesive bond moisture-durable. The wood–adhesive bondline is extraordinarily difficult to study because of the chemical, structural, and mechanical complexities and...

  11. Effective mass and damping of submerged structures

    Energy Technology Data Exchange (ETDEWEB)

    Dong, R.G.

    1978-04-01

    Various structures important for safety in nuclear power plants must remain functioning in the event of an earthquake or other dynamic phenomenon. Some of these important structures, such as spent-fuel storage racks, main pressure-relief valve lines, and internal structures in the reactor vessel, are submerged in water. Dynamic analysis must include the force and damping effects of water. This report provides a technical basis for evaluating the wide variety of modeling assumptions currently used in design analysis. Current design analysis techniques and information in the literature form the basis of our conclusions and recommendations. We surveyed 32 industrial firms and reviewed 49 technical references. We compare various theories with published experimental results wherever possible. Our findings generally pertain to idealized structures, such as single isolated members, arrays of members, and coaxial cylinders. We relate these findings to the actual reactor structures through observations and recommendations. Whenever possible we recommend a definite way to evaluate the effect of hydrodynamic forces on these structures.

  12. Effective mass and damping of submerged structures

    International Nuclear Information System (INIS)

    Dong, R.G.

    1978-01-01

    Various structures important for safety in nuclear power plants must remain functioning in the event of an earthquake or other dynamic phenomenon. Some of these important structures, such as spent-fuel storage racks, main pressure-relief valve lines, and internal structures in the reactor vessel, are submerged in water. Dynamic analysis must include the force and damping effects of water. This report provides a technical basis for evaluating the wide variety of modeling assumptions currently used in design analysis. Current design analysis techniques and information in the literature form the basis of our conclusions and recommendations. We surveyed 32 industrial firms and reviewed 49 technical references. We compare various theories with published experimental results wherever possible. Our findings generally pertain to idealized structures, such as single isolated members, arrays of members, and coaxial cylinders. We relate these findings to the actual reactor structures through observations and recommendations. Whenever possible we recommend a definite way to evaluate the effect of hydrodynamic forces on these structures

  13. Understanding the mechanism of nanotube synthesis for controlled production of specific (n,m) structures

    Energy Technology Data Exchange (ETDEWEB)

    Resasco, Daniel E.

    2010-02-11

    This report shows the extensive research on the mechanism responsible for the formation of single walled carbon nanotubes in order to get control over their structural parameters (diameter and chirality). Catalyst formulations, pre-treatment conditions, and reaction conditions are described in detail as well as mechanisms to produce nanotubes structures of specific arrays (vertical forest, nanotube pillars). Applications of SWNT in different fields are also described in this report. In relation to this project five students have graduated (3 PhD and 2 MS) and 35 papers have been published.

  14. Radiation effects on structural ceramics in fusion

    International Nuclear Information System (INIS)

    Hopkins, G.R.; Price, R.J.; Trester, P.W.

    1986-01-01

    Ceramics are required to serve in a conventional role as electrical and thermal insulators and dielectrics in fusion power reactors. In addition, certain ceramic materials can play a unique structural role in fusion power reactors by virtue of their very low induced radioactivity from fusion neutron capture. The aspects of safety, long-term radioactive waste management, and personnel access for maintenance and repair can all be significantly improved by applying the low-activation ceramics to the structural materials of the first-wall and blanket regions of a fusion reactor. Achievement of long service life at high structural loads and thermal stresses on the materials exposed to high-radiation doses presents a critical challenge for fusion. In this paper, we discuss radiation effects on structural ceramics for fusion application

  15. Understanding the Impact of Trauma Exposure on Posttraumatic Stress Symptomatology: A Structural Equation Modeling Approach

    Science.gov (United States)

    Chen, Wei; Wang, Long; Zhang, Xing-Li; Shi, Jian-Nong

    2012-01-01

    The objective of this study was to investigate the impact of trauma exposure on the posttraumatic stress symptomatology (PTSS) of children who resided near the epicenter of the 2008 Wenchuan earthquake. The mechanisms of this impact were explored via structural equation models with self-esteem and coping strategies included as mediators. The…

  16. Understanding the Phenotypic Structure of Adult Retrospective ADHD Symptoms during Childhood in the United States

    Science.gov (United States)

    Ranby, Krista W.; Boynton, Marcella H.; Kollins, Scott H.; McClernon, F. Joseph; Yang, Chongming; Fuemmeler, Bernard F.

    2012-01-01

    Attention-deficit/hyperactivity disorder (ADHD) is a highly heterogeneous disorder, and the phenotypic structure comprising inattentive and hyperactive-impulsive type symptoms has been the focus of a growing body of recent research. Methodological studies are needed to better characterize phenotypes to advance research as well as clinical…

  17. Towards the understanding of structure formation and dynamics in bio-nano systems

    DEFF Research Database (Denmark)

    Yakubovich, Alexander V.; Solov'yov, Ilia; Solov'yov, Andrey V.

    2008-01-01

    This paper gives an overview of a number of key structure formation processes involving the well known biomolecular and nano objects such as fullerenes, nanotubes, polypeptides, proteins and DNA molecules. We formulate the problems, describe the main experimental observations and theoretical...

  18. Implementation of Structured Inquiry Based Model Learning toward Students' Understanding of Geometry

    Science.gov (United States)

    Salim, Kalbin; Tiawa, Dayang Hjh

    2015-01-01

    The purpose of this study is implementation of a structured inquiry learning model in instruction of geometry. The model used is a model with a quasi-experimental study amounted to two classes of samples selected from the population of the ten classes with cluster random sampling technique. Data collection tool consists of a test item…

  19. Interactive tool that empowers structural understanding and enables FEM analysis in a parametric design environment

    DEFF Research Database (Denmark)

    Christensen, Jesper Thøger; Parigi, Dario; Kirkegaard, Poul Henning

    2014-01-01

    This paper introduces an interactive tool developed to integrate structural analysis in the architectural design environment from the early conceptual design stage. The tool improves exchange of data between the design environment of Rhino Grasshopper and the FEM analysis of Autodesk Robot...

  20. Energy--Structure--Life. A Learning System for Understanding Science, Book Two.

    Science.gov (United States)

    Bixby, Louis W.; And Others

    This learning guide contains materials for the second year of Energy/Structure/ Life, a two year high school program in integrated science. The guide is programed to permit the student to proceed on his own at a self-determined pace. The two year course is a sequence of physics, chemistry, and biology with the chemical (continued from the first…

  1. Energy--Structure--Life, A Learning System for Understanding Science. A Potpourri of Miscellany.

    Science.gov (United States)

    Bixby, Louis W.; And Others

    A discussion of the philosophy and rationale of Energy - Structure - Life, a two year high school sequence in integrated science, is contained in the introductory section of this manual. The student's copy of the laboratory activities and the quizzes for the first year of the program constitute the major portion of this volume. The two year course…

  2. Institutional Racist Melancholia: A Structural Understanding of Grief and Power in Schooling

    Science.gov (United States)

    Vaught, Sabina E.

    2012-01-01

    In this article, Sabina Vaught undertakes the theoretical and analytical project of conceptually integrating "Whiteness as property", a key structural framework of Critical Race Theory (CRT), and "melancholia", a framework originally emerging from psychoanalysis. Specifically, Vaught engages "Whiteness as property" as…

  3. Structural Violence: Moving beyond ethnicity towards and understanding of electoral violence in kenya

    DEFF Research Database (Denmark)

    Owiso, Michael Omondi

    2018-01-01

    , but at the same time expose the disconnect in electoral violence studies. The study is based on desk research and digs into books, journals, memoirs, newspapers and official government documents to unearth the underlying structure of Kenya (the actors, institutions, cultural hegemony, history and ideologies...

  4. Insights in understanding aggregate formation and dissociation in cation exchange chromatography for a structurally unstable Fc-fusion protein.

    Science.gov (United States)

    Chen, Zhiqiang; Huang, Chao; Chennamsetty, Naresh; Xu, Xuankuo; Li, Zheng Jian

    2016-08-19

    Cation-exchange chromatography (CEX) of a structurally unstable Fc-fusion protein exhibited multi-peak elution profile upon a salt-step elution due to protein aggregation during intra-column buffer transition where low pH and high salt coexisted. The protein exhibited a single-peak elution behavior during a pH-step elution; nevertheless, the levels of soluble aggregates (i.e. high molecular weight species, HMW) in the CEX eluate were still found up to 12-fold higher than that for the load material. The amount of the aggregates formed upon the pH-step elution was dependent on column loading with maximum HMW achieved at intermediate loading levels, supporting the hypothesis that the aggregation was the result of both the conformational changes of the bound protein and the solution concentration of the aggregation-susceptible proteins during elution. Factors such as high load pH, short protein/resin contact time, hydrophilic resin surface, and weak ionizable ligand were effective, to some extent, to reduce aggregate formation by improving the structural integrity of the bound protein. An orthogonal technique, differential scanning fluorimetry (DSF) using Sypro Orange dye confirmed that the bound protein exposed more hydrophobic area than the native molecule in free solution, especially in the pH 4-5 range. The Sypro Orange dye study of resin surface property also demonstrated that the poly[styrene-divinylbenzene]-based Poros XS with polyhydroxyl surface coating is more hydrophobic compared to the agarose-based CM Sepharose FF and SP Sepharose FF. The hydrophobic property of Poros XS contributed to stronger interactions with the partially unfolded bound protein and consequently to the higher aggregate levels seen in Poros XS eluate. This work also investigates the aggregation reversibility in CEX eluate where up to 66% of the aggregates were observed to dissociate into native monomers over a period of 120h, and links the aggregate stability to such conditions as resin

  5. Entropic effects in formation of chromosome territories: towards understanding of radiation-induced gene translocation frequency

    Science.gov (United States)

    Gudowska-Nowak, Ewa; Ritter, Sylvia; Durante, Marco; Deperas-Standylo, Joanna; Ciesla, Michal

    2012-07-01

    A detailed understanding of structural organization of biological target, such as geometry of an inter-phase chromosome, is an essential prerequisite for gaining deeper insight into relationship between radiation track structure and radiation-induced biological damage [1]. In particular, coupling of biophysical models aimed to describe architecture of chromosomes and their positioning in a cell nucleus [2-4] with models of local distribution of ionizations caused by passing projectiles, are expected to result in more accurate estimates of aberration induction caused by radiation. There is abundant experimental evidence indicating that arrangements of chromosomes in eukaryotic cell nucleus is non-random and has been evolutionary conserved in specific cell types. Moreover, the radial position of a given chromosome territory (CT) within the cell nucleus has been shown to correlate with its size and gene density. Usually it is assumed that chromosomal geometry and positioning result from the action of specific forces acting locally, such as hydrogen bonds, electrostatic, Van der Waals or hydrophobic interactions operating between nucleosomes and within their interiors. However, it is both desirable and instructive to learn to what extend organization of inter-phase chromosomes is affected by nonspecific entropic forces. In this study we report results of a coarse-grained analysis of a chromatin structure modeled by two distinct approaches. In the first method, we adhere to purely statistical analysis of chromatin packing within a chromosome territory. On the basis of the polymer theory, the chromatin fiber of diameter 30nm is approximated by a chain of spheres, each corresponding to about 30 kbp. Random positioning of the center of the domain is repeated for 1000 spherical nuclei. Configuration of the domain is determined by a random packing of a polymer (a string of identical beads) in estimated fraction of space occupied by a chromosome of a given length and mass

  6. A SEM Model in Assessing the Effect of Convergent, Divergent and Logical Thinking on Students' Understanding of Chemical Phenomena

    Science.gov (United States)

    Stamovlasis, D.; Kypraios, N.; Papageorgiou, G.

    2015-01-01

    In this study, structural equation modeling (SEM) is applied to an instrument assessing students' understanding of chemical change. The instrument comprised items on understanding the structure of substances, chemical changes and their interpretation. The structural relationships among particular groups of items are investigated and analyzed using…

  7. The effect of Phet Simulation media for physics teacher candidate understanding on photoelectric effect concept

    Directory of Open Access Journals (Sweden)

    Supurwoko Supurwoko

    2017-02-01

    Full Text Available Indonesian new Curriculum for senior high school students required student-centered learning. One of the curriculum implementation constraint was the difficulty of providing learning media. PhET simulations media is one of the options that can help implementation of new curriculum on learning. However, the use of this media in Indonesia still needs to be studied comprehensively. The learning was conducted on students of physics education Study Program in sebelas maret university in 2013. The sample consisted of 62 students that was taking quantum physics course. The method that was used in the research was descriptive qualitative.  The method that was used in learning was demonstration’s method that used PhET media and accompanied by a question and answer and groups discussion. The data was collected using multiple choice test and interview through email. We found that any students still did not understand about photoelectric effect concept. They were confused when asked about the thick material and cross section of the targets as related with the regardless of electrons in the photoelectric effect event. Other than that, the concept of the waves as a particle and its relation with the kinetic energy of the electrons was not understood by most students.

  8. Modelling of Deterioration Effects on Concrete Structures

    Directory of Open Access Journals (Sweden)

    B. Teplý

    2002-01-01

    Full Text Available In order to predict the service life of concrete structures models for deterioration effects are needed. This paper has the form of a survey, listing and describing such analytical models, namely carbonation of concrete, ingress of chlorides, corrosion of reinforcing steel and prestressing tendons. The probabilistic approach is applied.

  9. Proceedings of the 14th Summer School - Understanding the Structure of Hadrons - Prague - Czech Republic, July 9-13, 2001

    Czech Academy of Sciences Publication Activity Database

    Adam, Jiří; Bydžovský, Petr; Mareš, Jiří

    2002-01-01

    Roč. 52, Suppl.2 (2002), B3 ISSN 0011-4626. [Proceedings of the 14th Summer School - Understanding the Structury of Hadrons. Prague, 09.07.2001-13.07.2001] R&D Projects: GA AV ČR KSK1048102 Institutional research plan: CEZ:AV0Z1048901 Keywords : structure * hadrons Subject RIV: BE - Theoretical Physics Impact factor: 0.311, year: 2002

  10. An efficient approach to understanding and predicting the effects of multiple task characteristics on performance.

    Science.gov (United States)

    Richardson, Miles

    2017-04-01

    In ergonomics there is often a need to identify and predict the separate effects of multiple factors on performance. A cost-effective fractional factorial approach to understanding the relationship between task characteristics and task performance is presented. The method has been shown to provide sufficient independent variability to reveal and predict the effects of task characteristics on performance in two domains. The five steps outlined are: selection of performance measure, task characteristic identification, task design for user trials, data collection, regression model development and task characteristic analysis. The approach can be used for furthering knowledge of task performance, theoretical understanding, experimental control and prediction of task performance. Practitioner Summary: A cost-effective method to identify and predict the separate effects of multiple factors on performance is presented. The five steps allow a better understanding of task factors during the design process.

  11. Metal Oxide Nanomaterial QNAR Models: Available Structural Descriptors and Understanding of Toxicity Mechanisms

    Directory of Open Access Journals (Sweden)

    Jiali Ying

    2015-10-01

    Full Text Available Metal oxide nanomaterials are widely used in various areas; however, the divergent published toxicology data makes it difficult to determine whether there is a risk associated with exposure to metal oxide nanomaterials. The application of quantitative structure activity relationship (QSAR modeling in metal oxide nanomaterials toxicity studies can reduce the need for time-consuming and resource-intensive nanotoxicity tests. The nanostructure and inorganic composition of metal oxide nanomaterials makes this approach different from classical QSAR study; this review lists and classifies some structural descriptors, such as size, cation charge, and band gap energy, in recent metal oxide nanomaterials quantitative nanostructure activity relationship (QNAR studies and discusses the mechanism of metal oxide nanomaterials toxicity based on these descriptors and traditional nanotoxicity tests.

  12. Understanding the structure and role of academics' ego-networks on social networking sites

    OpenAIRE

    Jordan, Katy

    2017-01-01

    Academic social networking sites (SNS) seek to bring the benefits of online networking to an academic audience. Currently, the two largest sites are Academia.edu and ResearchGate. The ability to make connections to others is a defining affordance of SNS, but what are the characteristics of the network structures being facilitated by academic SNS, and how does this relate to their professional use by academics?\\ud \\ud This study addressed this question through mixed methods social network anal...

  13. Fundamental Understanding of Crack Growth in Structural Components of Generation IV Supercritical Light Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Iouri I. Balachov; Takao Kobayashi; Francis Tanzella; Indira Jayaweera; Palitha Jayaweera; Petri Kinnunen; Martin Bojinov; Timo Saario

    2004-11-17

    This work contributes to the design of safe and economical Generation-IV Super-Critical Water Reactors (SCWRs) by providing a basis for selecting structural materials to ensure the functionality of in-vessel components during the entire service life. During the second year of the project, we completed electrochemical characterization of the oxide film properties and investigation of crack initiation and propagation for candidate structural materials steels under supercritical conditions. We ranked candidate alloys against their susceptibility to environmentally assisted degradation based on the in situ data measure with an SRI-designed controlled distance electrochemistry (CDE) arrangement. A correlation between measurable oxide film properties and susceptibility of austenitic steels to environmentally assisted degradation was observed experimentally. One of the major practical results of the present work is the experimentally proven ability of the economical CDE technique to supply in situ data for ranking candidate structural materials for Generation-IV SCRs. A potential use of the CDE arrangement developed ar SRI for building in situ sensors monitoring water chemistry in the heat transport circuit of Generation-IV SCWRs was evaluated and proved to be feasible.

  14. Understanding structure-stability relationships of Candida antartica lipase B in ionic liquids.

    Science.gov (United States)

    De Diego, Teresa; Lozano, Pedro; Gmouh, Said; Vaultier, Michel; Iborra, José L

    2005-01-01

    Two different water-immiscible ionic liquids (ILs), 1-ethyl-3-methylimidizolium bis(trifluoromethylsulfonyl)imide and butyltrimethylammonium bis(trifluoromethylsulfonyl)imide, were used for butyl butyrate synthesis from vinyl butyrate catalyzed by Candida antarctica lipase B (CALB) at 2% (v/v) water content and 50 degrees C. Both the synthetic activity and stability of the enzyme in these ILs were enhanced as compared to those in hexane. Circular dichroism and intrinsic fluorescence spectroscopic techniques have been used over a period of 4 days to determine structural changes in the enzyme associated with differences in its stability for each assayed medium. CALB showed a loss in residual activity higher than 75% after 4 days of incubation in both water and hexane media at 50 degrees C, being related to great changes in both alpha-helix and beta-strand secondary structures. The stabilization of CALB, which was observed in the two ILs studied, was associated with both the maintenance of the 50% of initial alpha-helix content and the enhancement of beta-strands. Furthermore, intrinsic fluorescence studies clearly showed how a classical enzyme unfolding was occurring with time in both water and hexane media. However, the structural changes associated with the incubation of the enzyme in both ILs might be attributed to a compact and active enzyme conformation, resulting in an enhancement of the stability in these nonaqueous environments.

  15. Histological investigation of the supra-glottal structures in humans for understanding abnormal phonation

    Science.gov (United States)

    Kimura, Miwako; Sakakibara, Ken-Ichi; Imagawa, Hiroshi; Chan, Roger; Niimi, Seijii; Tayama, Niro

    2002-11-01

    Phonation is the vocal fold vibration on normal voice. But sometimes we can observe the other phonation styles like as the pressed voice or some throat singings like as ''kargyraa'' or ''drone'' in Khoomei in Mongolian music. Also, clinically, we know that some patients who have the wide glottal slit in phonation because of the recurrence nerve palsy or after partial laryngectomy, could make the ''supra-glottal phonation.'' The ''supra-glottal phonation'' would be made from the vibration of ''supra-glottal structures'' such as the false vocal folds, the arytenoids and the epiglottis, etc. Endoscopic examination suggests the existence of some contractile functions in supra-glottal space. However, these phonation systems have not been clear to explain their neuromuscular mechanism in histology. This study aimed to find the basis for making the supra-glottal phonation from the points of view of the histological structures. We tried to investigate if there were any muscles that could contract the supra-glottal structures. The samples are the excised larynx of human beings. They were fixed by formalin after excision. We observed their macroscopic anatomy, and also with the microscopic observation their histological preparations after the process of the embedding in paraffin, slicing for the preparation and HE (hematoxylin-eosin) staining.

  16. Understanding E-Learning Adoption in Brazil: Major Determinants and Gender Effects

    Directory of Open Access Journals (Sweden)

    Shintaro Okazaki

    2012-10-01

    Full Text Available The objective of this study is to examine factors influencing e-learning adoption and the moderating role of gender. This study extends the technology acceptance model (TAM by adding attitude and social interaction. The new construct of social interaction is applied to the South American context. Gender effects on e-learning adoption from educators’ perspectives have seldom been explored. The data collection takes place in three major Brazilian universities. In total, 446 faculty members responded to the questionnaire. Our structural equation modeling reveals that ease of use and perceived usefulness are significant antecedents of attitude, which in turn affects intention. However, unlike the original TAM, perceived usefulness is not a direct driver of intention. In terms of moderation, gender affects three relationships: (1 ease of use –› perceived usefulness; (2 perceived usefulness –› attitude, and (3 intention –› actual behavior. The analysis is carried out in a single country; thus, caution should be taken in generalization of the results. The findings will help academics, educators, and policy makers to better understand the mechanism of e-learning adoption in Brazil.

  17. Understanding the psychiatric effects of concussion on constructed identity in hockey players: Implications for health professionals

    Science.gov (United States)

    Todd, Ryan; Bhalerao, Shree; Soklaridis, Sophie; Cusimano, Michael D.

    2018-01-01

    Objective The following study was undertaken to investigate the effect of concussion and psychiatric illness on athletes and their caregivers. Methods Semi-structured interviews with 20 ice hockey stakeholders (17 men and 3 women) including minor and professional players, coaches, parents, and physicians were conducted over two years (2012–2014). These interviews were analyzed using grounded theory. Results From this analysis, a common biographical theme emerged whereby the subject’s identity as a hockey player, constructed early in life over many years, was disrupted by concussion. Furthermore, some players underwent a biographical deconstruction when they experienced post-concussive mental illness, which was amplified by isolation, stigma from peers, and lack of a clear life trajectory. Many players obtained support from family and peers and were able to recover, as evidenced by the biographical reconstruction of their identity post-hockey concussion. Conclusions and implications for practice Understanding the process of biographical deconstruction and reconstruction has significant psychosocial treatment implications for both healthcare professionals and caregivers of this population. Specifically, the authors suggest that interpersonal psychotherapy (IPT) that focuses on role transitions may create opportunities to facilitate the process of biographical reconstruction and life transition. PMID:29466377

  18. Understanding the Greenhouse Effect by Embodiment - Analysing and Using Students' and Scientists' Conceptual Resources

    Science.gov (United States)

    Niebert, Kai; Gropengießer, Harald

    2014-01-01

    Over the last 20 years, science education studies have reported that there are very different understandings among students of science regarding the key aspects of climate change. We used the cognitive linguistic framework of experientialism to shed new light on this valuable pool of studies to identify the conceptual resources of understanding climate change. In our study, we interviewed 35 secondary school students on their understanding of the greenhouse effect and analysed the conceptions of climate scientists as drawn from textbooks and research reports. We analysed all data by metaphor analysis and qualitative content analysis to gain insight into students' and scientists' resources for understanding. In our analysis, we found that students and scientists refer to the same schemata to understand the greenhouse effect. We categorised their conceptions into three different principles the conceptions are based on: warming by more input, warming by less output, and warming by a new equilibrium. By interrelating students' and scientists' conceptions, we identified the students' learning demand: First, our students were afforded with experiences regarding the interactions of electromagnetic radiation and CO2. Second, our students reflected about the experience-based schemata they use as source domains for metaphorical understanding of the greenhouse effect. By uncovering the-mostly unconscious-deployed schemata, we gave students access to their source domains. We implemented these teaching guidelines in interventions and evaluated them in teaching experiments to develop evidence-based and theory-guided learning activities on the greenhouse effect.

  19. Using Interactive Technology to Support Students' Understanding of the Greenhouse Effect and Global Warming

    Science.gov (United States)

    Varma, Keisha; Linn, Marcia C.

    2012-01-01

    In this work, we examine middle school students' understanding of the greenhouse effect and global warming. We designed and refined a technology-enhanced curriculum module called "Global Warming: Virtual Earth". In the module activities, students conduct virtual experiments with a visualization of the greenhouse effect. They analyze data and draw…

  20. Effect of Technology Enhanced Conceptual Change Texts on Students' Understanding of Buoyant Force

    Science.gov (United States)

    Ozkan, Gulbin; Selcuk, Gamze Sezgin

    2015-01-01

    In this study, the effect of technology enhanced conceptual change texts on elementary school students' understanding of buoyant force was investigated. The conceptual change texts (written forms) used in this study are proven for effectiveness and are enriched by using technology support in this study. These texts were tried out on two groups. A…

  1. Understanding the Fatigue Behavior of FML Structures and Materials under Complex Variable Amplitude Loading

    NARCIS (Netherlands)

    Alderdiesten, R.; Benedictus, R.; Khan, S.

    2009-01-01

    This paper presents various failure mechanisms in FMLs, highlights the presence or absence of interaction effects, and describes how the failure mechanisms can be described for predicting damage growth under arbitrary complex load spectra.

  2. Understanding the internal structures of X(4140), X(4274), X(4500) and X(4700)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hua-Xing; Cui, Er-Liang [Beihang University, School of Physics and Beijing Key Laboratory of Advanced Nuclear Materials and Physics, Beijing (China); Chen, Wei [University of Saskatchewan, Department of Physics and Engineering Physics, Saskatoon, Saskatchewan (Canada); Liu, Xiang [Lanzhou University, School of Physical Science and Technology, Lanzhou (China); Lanzhou University and Institute of Modern Physics of CAS, Research Center for Hadron and CSR Physics, Lanzhou (China); Zhu, Shi-Lin [Peking University, School of Physics and State Key Laboratory of Nuclear Physics and Technology, Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Peking University, Center of High Energy Physics, Beijing (China)

    2017-03-15

    We investigate the newly observed X(4500) and X(4700) based on the diquark-antidiquark configuration within the framework of QCD sum rules. Both of them may be interpreted as the D-wave cs anti c anti s tetraquark states of J{sup P} = 0{sup +}, but with opposite color structures, which is remarkably similar to the result obtained in Chen and Zhu (Phys Rev D 83:034010, 2011) that X(4140) and X(4274) can be both interpreted as the S-wave cs anti c anti s tetraquark states of J{sup P} = 1{sup +}, also with opposite color structures. However, the extracted masses and these suggested assignments to these X states do depend on these running quark masses where m{sub s}(2 GeV) = 95 ± 5 MeV and m{sub c}(m{sub c}) = 1.23 ± 0.09 GeV. As a byproduct, the masses of the hidden-bottom partner states of X(4500) and X(4700) are extracted to be both around 10.64 GeV, which can be searched for in the Υφ invariant mass distribution. (orig.)

  3. Understanding the structure and performance of self-assembled triblock terpolymer membranes

    KAUST Repository

    Pendergast, MaryTheresa M.

    2013-10-01

    Nanoporous membranes represent a possible route towards more precise particle and macromolecular separations, which are of interest across many industries. Here, we explored membranes with vertically-aligned nanopores formed from a poly(isoprene-. b-styrene-. b-4 vinyl pyridine) (ISV) triblock terpolymer via a hybrid self-assembly/nonsolvent induced phase separation process (S-NIPS). ISV concentration, solvent composition, and evaporation time in the S-NIPS process were varied to tailor ordering of the selective layer and produce enhanced water permeability. Here, water permeability was doubled over previous versions of ISV membranes. This was achieved by increasing volatile solvent concentration, thereby decreasing the evaporation period required for self-assembly. Fine-tuning was required, however, since overly-rapid evaporation did not yield the desired pore structure. Transport models, used to relate the in-. situ structure to the performance of these materials, revealed narrowing of pores and blocking by the dense region below. It was shown that these vertically aligned nanoporous membranes compare favorably with commercial ultrafiltration membranes formed by NIPS and track-etching processes, which suggests that there is practical value in further developing and optimizing these materials for specific industrial separations. © 2013 Elsevier B.V.

  4. Understanding structural changes in NMC Li-ion cells by in situ neutron diffraction

    Science.gov (United States)

    Dolotko, O.; Senyshyn, A.; Mühlbauer, M. J.; Nikolowski, K.; Ehrenberg, H.

    2014-06-01

    Commercial NMC cells of 18650-type based on a Lix(Ni0.5Mn0.3Co0.2)O2 cathode and a graphitic anode were studied in situ using a combination of high-resolution monochromatic neutron powder diffraction and electrochemical analysis. The structural changes of the electrode materials during cell charge/discharge have been determined using Rietveld refinement and single profile decomposition techniques. A transformation of the graphitic anode to LiC12 and LiC6 through the formation of higher ordered lithium intercalated carbons was observed. A different behavior of electrochemically-driven lattice distortion was observed for NMC material in comparison to LixCoO2 and its influence on the overall cell performance has been discussed in brief. Detailed analysis of the structural changes in the Lix(Ni0.5Mn0.3Co0.2)O2 cathode material revealed reversible Li/Ni cation mixing (5.6(8)%), which is state-of-charge independent below 1600 mAh and vanishing above 1800 mAh (∼0.8Qmax).

  5. 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.

  6. A Capability Approach to Understanding Sport for Social Inclusion: Agency, Structure and Organisations

    Directory of Open Access Journals (Sweden)

    Naofumi Suzuki

    2017-06-01

    Full Text Available Despite the global diffusion of the term social inclusion, as well as the use of sport to promote it, questions have been raised regarding the extent to which sport is able to contribute to transforming the exclusive nature of the social structure. The lack of analytical clarity of the concept has not helped to address these questions. This article proposes a conceptual framework based on Amartya Sen’s capability approach, considering social exclusion as the denial of social relations that leads to serious deprivation of important capabilities. A person’s capabilities could potentially be improved through micro-, meso-, and macro-level social processes. At the micro level, sport-based social inclusion programmes could offer such social relations to varying degrees, though sport’s values are only relative to other leisure activities. The scale of impact depends primarily on the meso-level processes, in which the size and quality of each programme can be improved through organisational learning, and secondarily on the macro-level processes whereby the organisational population is institutionalised. It is argued that more research needs to be done on the meso and macro levels, as they are concerned with the ultimate potential of sport to facilitate structural transformation towards more socially inclusive society.

  7. Unraveling Structural Infrasound: understanding the science for persistent remote monitoring of critical infrastructure (Invited)

    Science.gov (United States)

    McKenna, S. M.; Diaz-Alvarez, H.; McComas, S.; Costley, D.; Whitlow, R. D.; Jordan, A. M.; Taylor, O.

    2013-12-01

    In 2006, the Engineer Research and Development Center (ERDC) began a program designed to meet the capability gap associated with remote assessment of critical infrastructure. This program addresses issues arising from the use of geophysical techniques to solve engineering problems through persistent monitoring of critical infrastructure using infrasound. In the original 2006-2009 study of a railroad bridge in Ft. Leonard Wood, MO, the fundamental modes of motion of the structure were detected at up to 30 km away, with atmospheric excitation deemed to be the source driver. Follow-on research focused on the mechanically driven modes excited by traffic, with directional acoustic emanations. The success of the Ft. Wood ambient excitation study resulted in several subsequent programs to push the boundaries of this new technique for standoff assessment, discussed herein. Detection of scour and river system health monitoring are serious problems for monitoring civil infrastructure, from both civilian and military perspectives. Knowledge of overall system behavior over time is crucial for assessment of bridge foundations and barge navigation. This research focuses on the same steel-truss bridge from the Ft. Wood study, and analyzes 3D and 2D substructure models coupled with the superstructure reaction loads to assess the modal deformations within the infrasound bandwidth and the correlation to scour of embedment material. The Urban infrasound program is infrasound modeling, data analysis, and sensor research leading to the detection, classification and localization of threat activities in complex propagation environments. Three seismo-acoustic arrays were deployed on rooftops across the Southern Methodist University campus in Dallas, Texas, to characterize the urban infrasound environment. Structural sources within 15 km of the arrays have been identified through signal processing and confirmed through acoustical models. Infrasound is also being studied as a means of

  8. Thermal Effects Modeling Developed for Smart Structures

    Science.gov (United States)

    Lee, Ho-Jun

    1998-01-01

    Applying smart materials in aeropropulsion systems may improve the performance of aircraft engines through a variety of vibration, noise, and shape-control applications. To facilitate the experimental characterization of these smart structures, researchers have been focusing on developing analytical models to account for the coupled mechanical, electrical, and thermal response of these materials. One focus of current research efforts has been directed toward incorporating a comprehensive thermal analysis modeling capability. Typically, temperature affects the behavior of smart materials by three distinct mechanisms: Induction of thermal strains because of coefficient of thermal expansion mismatch 1. Pyroelectric effects on the piezoelectric elements; 2. Temperature-dependent changes in material properties; and 3. Previous analytical models only investigated the first two thermal effects mechanisms. However, since the material properties of piezoelectric materials generally vary greatly with temperature (see the graph), incorporating temperature-dependent material properties will significantly affect the structural deflections, sensory voltages, and stresses. Thus, the current analytical model captures thermal effects arising from all three mechanisms through thermopiezoelectric constitutive equations. These constitutive equations were incorporated into a layerwise laminate theory with the inherent capability to model both the active and sensory response of smart structures in thermal environments. Corresponding finite element equations were formulated and implemented for both the beam and plate elements to provide a comprehensive thermal effects modeling capability.

  9. 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.

  10. 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

  11. Nucleus structure and dust morphology: Post-Rosetta understanding and implications

    Science.gov (United States)

    Levasseur-Regourd, A.; Bentley, Mark; Ciarletti, Valérie; Kofman, Woldek; Lasue, Jeremie; Mannel, Thurid; Herique, Alain

    2017-10-01

    The structure of cometary nuclei and the morphology of dust particles they eject have long been unknowns in cometary science. The combination of these two subjects, as revealed by the Rosetta mission at 67P/C-G, is currently providing an unprecedented insight about Solar System formation and early evolution.Rosetta has established that the bulk porosity of 67P/C-G nucleus is high, in the 70% to 85% range, both from the determination of its density and from permittivity measurements with CONSERT bistatic radar experiment [1-2]. CONSERT, through operations after Philae landing on 12-13 November 2014, has also allowed us to estimate that i) the porosity is likely to be higher inside the nucleus than on its subsurface, ii) a major component of the nucleus is refractory carbonaceous compounds, and iii) the small lobe is homogeneous at a scale of a few wavelengths (i.e., about 10 m), while heterogeneities in the 3-m range (similar to the rounded nodules noticed on walls of large pits) cannot be ruled out [2-4].Rosetta has also established, through its 26 months rendezvous with 67P/C-G, the aggregated structure of dust particles within a wide range of sizes in the inner cometary coma. The MIDAS atomic force microscope experiment has given us evidence (from 3D topographic images with nano- to micrometer resolution) for i) a hierarchical structure of aggregated dust particles, down to tens of nm-sized grains, ii) one extremely porous dust particle, with a fractal dimension of (1.7 ± 0.1) [5-6]. The accuracy of comparisons between cometary dust particles and interplanetary dust particles collected in the stratosphere (including CP-IDPs) could thus be improved.Such results should further refine the main processes (e.g., low velocity aggregation) that allowed the formation of comets in the early Solar System, and the implications of a possible late heavy bombardment on the interplanetary dust clouds and on telluric planets.References. 1. Pätzold et al. Nature 530 63 2016. 2

  12. 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

    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......, 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...

  13. Understanding the subsurface thermal structure of deep sedimentary basins in Denmark - measurements and modelling results

    DEFF Research Database (Denmark)

    Balling, N.; Poulsen, Søren Erbs; Bording, Thue Sylvester

    2015-01-01

    Most of the Danish area is characterized by deep sedimentary basins with a great potential for exploitation of geothermal energy. Geothermal reservoirs are present at various depths and temperatures. Currently, three geothermal plants are operating producing warm water for district heating purposes...... of different conductivity. Mean geothermal gradients from surface to depths of 1000 to 3000 m are generally between 20 and 35 °C/km. The subsurface thermal structure is clearly dominated by conduction. Advection by groundwater migration is generally insignificant. Heat flow increases significantly with depth...... due to perturbation from long-term palaeoclimatic surface temperature variations. Examples of modelled temperature distribution for selected geothermal reservoir are shown. In the Gassum Formation, which is present in most of the Danish area, temperatures are largely between 35 and 90 °C for depths...

  14. Understanding Nomophobia: Structural Equation Modeling and Semantic Network Analysis of Smartphone Separation Anxiety.

    Science.gov (United States)

    Han, Seunghee; Kim, Ki Joon; Kim, Jang Hyun

    2017-07-01

    This study explicates nomophobia by developing a research model that identifies several determinants of smartphone separation anxiety and by conducting semantic network analyses on smartphone users' verbal descriptions of the meaning of their smartphones. Structural equation modeling of the proposed model indicates that personal memories evoked by smartphones encourage users to extend their identity onto their devices. When users perceive smartphones as their extended selves, they are more likely to get attached to the devices, which, in turn, leads to nomophobia by heightening the phone proximity-seeking tendency. This finding is also supplemented by the results of the semantic network analyses revealing that the words related to memory, self, and proximity-seeking are indeed more frequently used in the high, compared with low, nomophobia group.

  15. Understanding and Curing Structural Defects in Colloidal GaAs Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Vishwas [Department of Chemistry; Liu, Wenyong [Department of Chemistry; Janke, Eric M. [Department of Chemistry; Kamysbayev, Vladislav [Department of Chemistry; Filatov, Alexander S. [Department of Chemistry; Sun, Cheng-Jun [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States; Lee, Byeongdu [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States; Rajh, Tijana [Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States; Schaller, Richard D. [Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States; Department of; Talapin, Dmitri V. [Department of Chemistry; Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States

    2017-02-22

    Nearly three decades since the first report on the synthesis of colloidal GaAs nanocrystals (NCs), the preparation and properties of this material remain highly controversial. Traditional synthetic routes either fail to produce the GaAs phase or result in materials that do not show expected optical properties such as excitonic transitions. In this work, we demonstrate a variety of synthetic routes toward crystalline GaAs NCs. By using a combination of Raman, EXAFS and transient absorption spectroscopies, we conclude that unusual optical properties of 2 colloidal GaAs NCs can be related to the presence of vacancies and lattice disorder. We introduce novel molten salt based annealing approach to alleviate these structural defects and show the emergence of size-dependent excitonic transitions in colloidal GaAs quantum dots.

  16. Sharpening the edges of understanding the structure/function of the LPA1 receptor

    Science.gov (United States)

    Murph, Mandi; Nguyen, Giang; Radhakrishna, Harish; Mills, Gordon B.

    2008-01-01

    Since the molecular cloning of the vzg-1/Edg-2/LPA1 gene, studies have attempted to characterize LPA1 receptor functionality into a single categorical role, different from the other Edg-family LPA receptors. The desire to categorize LPA1 function has highlighted its complexity and demonstrated that the LPA1 receptor does not have one absolute function throughout every system. The central nervous system is highly enriched in the LPA1 receptor, suggesting an integral role in neuronal processes. Metastatic and invasive breast cancer also appears to have LPA-mediated LPA1 receptor functions that enhance phenotypes associated with tumorigenesis. LPA1 possesses a number of motifs conserved among G protein-coupled receptors (GPCRs): a DRY-like motif, a PDZ domain, Ser/Thr predicted sites of phosphorylation, a dileucine motif, double cysteines in the tail and conserved residues that stabilize structure and determine ligand binding. The third intracellular loop of the LPA1 receptor may be the crux of receptor signaling and attenuation with phosphorylation of Thr-236 potentially a key determinant of basal LPA1 signaling. Mutagenesis data supports the notion that Thr-236 regulates this process since mutating Thr-236 to Ala-236 increased basal and LPA-mediated serum response factor (SRF) signaling activity and Lys-236 further increased this basal signaling. Here we describe progress on defining the major functions of the LPA1 receptor, discuss a context dependent dualistic role as both a negative regulator in cancer and a proto-oncogene, outline its structural components at the molecular amino-acid level and present mutagenesis data on the third intracellular loop of the receptor. PMID:18501205

  17. Structure sensitivity and nanoscale effects in electrocatalysis

    Science.gov (United States)

    Koper, Marc T. M.

    2011-05-01

    This review discusses the role of the detailed nanoscale structure of catalytic surfaces on the activity of various electrocatalytic reactions of importance for fuel cells, hydrogen production, and other environmentally important catalytic reactions, such as carbon monoxide oxidation, methanol and ethanol oxidation, ammonia oxidation, nitric oxide reduction, hydrogen evolution, and oxygen reduction. Specifically, results and insights obtained from surface-science single-crystal-based model experiments are linked to experiments on well-defined shape-controlled nanoparticles. A classification of structure sensitive effects in electrocatalysis is suggested, based both on empirical grounds and on quantum-chemical viz. thermochemical considerations. The mutual relation between the two classification schemes is also discussed. The review underscores the relevance of single-crystal modeling of nanoscale effects in catalysis, and points to the special role of two kinds of active sites for electrocatalysis on nanoparticulate surfaces: (i) steps and defects in (111) terraces or facets, and (ii) long-range (100) terraces or facets.

  18. Baroque Tower on a Gothic Base: A Lakatosian Reconstruction of Students' and Teachers' Understanding of Structure of the Atom

    Science.gov (United States)

    Blanco, Rafael; Niaz, Mansoor

    The main objective of this study is a reconstruction of students' and teachers' understanding of structure of the atom based on the following framework: a) history of science can be conceived as that of competing rival research programs; b) some of the greatest scientific research programs progressed on inconsistent foundations; c) in actual scientific practice, counter-examples would be considered as mere anomalies; d) work of Thomson, Rutherford and Bohr led to the postulation of atomic models based on competing frameworks of understanding. This study is based on 171 freshman students enrolled in General Chemistry I and 7 chemistry teachers at the Instituto Universitario de Tecnología, El Tigre, Venezuela. All the students and teachers were asked to respond to a 11 item questionnaire and explain their responses. The questionnaire was administered about a month after the students/teachers had finished the topic of atomic structure. Students' and teachers' responses were classified in the following categories: Positivist/inductivist, Transitional and Lakatosian. Results obtained show that students and teachers: a) have a very similar positivist understanding of the progress of science; b) are inconsistent in their responses by switching from a positivist response on one item to a Lakatosian on an another; c) also showed some consistent response patterns by resisting changes in some of their core beliefs by invoking "auxiliary hypotheses"; and d) consider that observable hard experimental facts give science its objective status, whereas the interpretations being subjective perhaps go beyond the fold of science.

  19. Proximity effects in ferromagnet/superconductor structures

    International Nuclear Information System (INIS)

    Yu, H.L.; Sun, G.Y.; Yang, L.Y.; Xing, D.Y.

    2004-01-01

    The Nambu spinor Green's function approach is applied to study proximity effects in ferromagnet/superconductor (FM/SC) structures. They include the induced superconducting order parameter and density of states (DOS) with superconducting feature on the FM side, and spin-dependent DOS within the energy gap on the SC side. The latter indicates an appearance of gapless superconductivity and a coexistence of ferromagnetism and superconductivity in a small regime near the interface. The influence of exchange energy in FM and barrier strength at interface on the proximity effects is discussed

  20. A contribution to the understanding of the high burn-up structure formation in nuclear fuels

    International Nuclear Information System (INIS)

    Jonnet, J.

    2007-01-01

    An increase of the discharge burn-up of UO 2 nuclear fuels in the light water reactors results in the appearance of a change of microscopic structure, called HBS. Although well characterised experimentally, important points on the mechanisms of its formation remain to be cleared up. In order to answer these questions, a study of the contribution of the dislocation-type defects was conducted. In a first part, a calculation method of the stress field associated with periodic configurations of dislocations was developed. The method was applied to the cases of edge dislocation pile-up and wall, for which an explicit expression of the internal stress potential was obtained. Through the study of other examples of dislocation configurations, it was highlighted that this method also allows the calculation of any periodic dislocation configuration. In a second part, the evolution of interstitial-type dislocation loops was studied in UO 2 fuel samples doped with 10% in mass of alpha emitters. The experimental loop size distributions were obtained for these samples stored during 4 and 7 years at room temperature. Kinetic equations are proposed in order to study the influence of the resolution process of interstitials from a loop back to the matrix due to an impact with the recoil atom 234 U, as well as the coalescence of two interstitial loops that can diffuse by a volume mechanism. The application of the model shows that the two processes must be considered in the study of the evolution of radiation damage. (author)

  1. Toward an understanding of the Middle Pleistocene Transition as a structural change in climate stability

    Science.gov (United States)

    Ditlevsen, Peter

    2016-04-01

    The Middle Pleistocene transition signifies a change approximately 1 Myr ago from a period with 40 kyr glacial cycles to a period of approximately 100 kyr cycles in response to the orbital forcing. This change from the "40 kyr world" to the "100 kyr world" is not reflected in noticeable changes in the forcing. To explain this we present a low order conceptual model for the oscillatory dynamics of the ice sheets in terms of a relaxation oscillator with multiple levels subject to the Milankovitch forcing. The model exhibits smooth transitions between three different climate states; an interglacial (i), a mild glacial (g) and a deep glacial (G) as proposed by Paillard (1998). The model suggests a dynamical explanation in terms of the structure of a slow manifold for the observed allowed and ``forbidden'' transitions between the three climate states. With the model, the pacing of the climate oscillations by the astronomical forcing is through the mechanism of phase-resetting of relaxation oscillations in which the internal phase of the oscillation is affected by the forcing.

  2. Isolated catalyst sites on amorphous supports: A systematic algorithm for understanding heterogeneities in structure and reactivity

    Science.gov (United States)

    Goldsmith, Bryan R.; Sanderson, Evan D.; Bean, Daniel; Peters, Baron

    2013-05-01

    Methods for modeling catalytic sites on amorphous supports lag far behind methods for modeling catalytic sites on metal surfaces, zeolites, and other crystalline materials. One typical strategy for amorphous supports uses cluster models with arbitrarily chosen constraints to model the rigid amorphous support, but these constraints arbitrarily influence catalyst site activity. An alternative strategy is to use no constraints, but this results in catalytic sites with unrealistic flexibility. We present a systematic ab initio method to model isolated active sites on insulating amorphous supports using small cluster models. A sequential quadratic programming framework helps us relate chemical properties, such as the activation energy, to active site structure. The algorithm is first illustrated on an empirical valence bond model energy landscape. We then use the algorithm to model an off-pathway kinetic trap in olefin metathesis by isolated Mo sites on amorphous SiO2. The cluster models were terminated with basis set deficient fluorine atoms to mimic the properties of an extended silica framework. We also discuss limitations of the current algorithm formulation and future directions for improvement.

  3. Toward understanding the evolution of griseofulvin crystal structure to a mesophase after cryogenic milling.

    Science.gov (United States)

    Feng, Tao; Bates, Simon; Carvajal, M Teresa

    2009-02-09

    The purpose of this research is to investigate the response of crystalline griseofulvin to mechanically induced stress through cryogenic milling. Crystalline griseofulvin was subjected to cryogenic milling for two different lengths of time. Following cryo-milling, the samples were immediately analyzed by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD). The DSC thermograms of cryo-milled griseofulvin showed a complex exothermic event at around 65 degrees C for the 30min cryo-milled sample and around 75 degrees C for the 60min cryo-milled sample. A glass transition event was not observed for the cryo-milled samples. This is in direct contrast to the X-ray amorphous griseofulvin sample prepared through the quench melt method The XRPD patterns of cryo-milled griseofulvin show a loss of the crystalline Bragg peaks and a corresponding increase in diffuse scattering (halos). The disordered griseofulvin material produced through cryo-milling appears X-ray amorphous, yet different from the amorphous phase produced using the quench melt method. Both X-ray amorphous materials have distinctive DSC thermograms and X-ray powder patterns. These findings suggest that the evolution of the griseofulvin crystal structure during cryo-milling is not simply a crystal-to-amorphous transition but a transition to an intermediate mesophase.

  4. PROTEIN STRUCTURE: A OBSTACLE TO THE UNDERSTANDING OF BIOCHEMICAL PROCESSES FOR HIGH SCHOOL TEACHERS

    Directory of Open Access Journals (Sweden)

    S. L. Menezes

    2007-05-01

    Full Text Available Biochemistry underlays many subjects taught in high school but most teacherslack enough biochemical bases to explore them properly. To investigate their alternativeconceptions we have applied the distance course Biochemistry of Drugs to public schoolteachers, with class load of 30 hours and six modules: Statistics and basic concepts;Marijuana; Tobacco; Inhalants; Alcohol; Legalization vs Criminalization. The conceptionswere analyzed through the course records and the most important was the lack ofknowledge on the protein chemical structure, which impaired the comprehension ofproposed molecular mechanisms (involving receptors, neurotransmitters, enzymeinhibition, etc.. Several interventions promoted the overcoming of many misconceptionsas detected by written tests on chemical nature of involved compounds; neurotransmissionmechanism and the role of drugs in neurotransmission. Among 63 questions only 10 hadless than 50% correct answers. The teachers’ performances were impaired by readingdifficulties and poor scientific background that difficult their distinction of facts and scientificmodels from common sense or personal opinion. The teachers’ and the course staffevaluations were highly positive. Most of them declared that their knowledge was amplifiedand that they would recommend this course to colleagues. They also were favorablysurprised with the deep level of the topics, the demanded dedication and the fact that thecourse was addressed to themselves instead of to their students.

  5. Alveoli, teeth, and tooth loss: Understanding the homology of internal mandibular structures in mysticete cetaceans.

    Directory of Open Access Journals (Sweden)

    Carlos Mauricio Peredo

    Full Text Available The evolution of filter feeding in baleen whales (Mysticeti facilitated a wide range of ecological diversity and extreme gigantism. The innovation of filter feeding evolved in a shift from a mineralized upper and lower dentition in stem mysticetes to keratinous baleen plates that hang only from the roof of the mouth in extant species, which are all edentulous as adults. While all extant mysticetes are born with a mandible lacking a specialized feeding structure (i.e., baleen, the bony surface retains small foramina with elongated sulci that often merge together in what has been termed the alveolar gutter. Because mysticete embryos develop tooth buds that resorb in utero, these foramina have been interpreted as homologous to tooth alveoli in other mammals. Here, we test this homology by creating 3D models of the internal mandibular morphology from terrestrial artiodactyls and fossil and extant cetaceans, including stem cetaceans, odontocetes and mysticetes. We demonstrate that dorsal foramina on the mandible communicate with the mandibular canal via smaller canals, which we explain within the context of known mechanical models of bone resorption. We suggest that these dorsal foramina represent distinct branches of the inferior alveolar nerve (or artery, rather than alveoli homologous with those of other mammals. As a functional explanation, we propose that these branches provide sensation to the dorsal margin of the mandible to facilitate placement and occlusion of the baleen plates during filer feeding.

  6. Understanding the Pathophysiology of Spinocerebellar Ataxias through genetics, neurophysiology, structural and functional neuroimaging

    Directory of Open Access Journals (Sweden)

    Pramod Kumar Pal

    2015-12-01

    largely absent with additional activity in contralateral cortices and in thalami in patients with SCA1; increased thalamic function could be one of the causes for disinhibition of the motor cortex contributing to uncoordinated movements.Studies on larger cohort of each subtype of SCAs to validate the above findings, follow-up studies to determine the rate and nature of progression of neurodegeneration and evaluation of pre-symptomatic genetically confirmed SCAs will help understand the pathophysiology of the SCAs.

  7. Practical and effective management of libraries integrating case studies, general management theory and self-understanding

    CERN Document Server

    Moniz, Jr, Richard

    2010-01-01

    Aimed at library science students and librarians with newly assigned administrative duties the book is about improving one's thinking and decision making in a role as a library manager. Most librarians get very little exposure to management issues prior to finding themselves in a management role. Furthermore, most library science students do not expect that they will need to understand management yet they quickly find that there is a need to understand this perspective to be effective at almost any library job. Effective library management is about having some tools to make decisions (such as

  8. Discovering and measuring a layered Earth: A foundational laboratory for developing students' understanding of Earth's interior structure

    Science.gov (United States)

    Hubenthal, M.; Braile, L. W.; Olds, S. E.; Taber, J.

    2010-12-01

    Geophysics research is continuously revealing new insights about Earth’s interior structure. Before students can grasp theses new complexities, they first must internalize the 1st order layered structure of Earth and comprehend how seismology contributes to the development of such models. Earth structure is of course covered in most introductory geoscience courses, though all too often instruction of this content is limited to didactic methods that make little effort to inspire or engage the minds of students. In the process, students are expected to blindly accept our understanding of the unseen and abstract. Thus, it is not surprising then that many students can draw a layered Earth diagram, yet not know that knowledge of Earth’s interior is based on information from earthquakes. Cognitive learning theory would suggest that what has been missing from instruction of Earth structure is a feasible method to present students with seismic evidence in a manner that allows students to become minds-on with the content; discovering or dispelling the presence of a layered Earth for themselves. Recent advances in serving seismic data to a non-seismologist audience have made the development of such laboratory investigations possible. In this exercise students use an inquiry approach to examine seismic evidence and determine that the Earth cannot have a homogeneous composition. Further they use the data to estimate the dimensions of Earth’s outer core. To reach these conclusions, students are divided into two teams, theoreticians and seismologists, to test the simplest hypothesis for Earth's internal structure; a homogeneous Earth. The theoreticians create a scale model of a homogeneous Earth and predict when seismic waves should arrive at various points on the model. Simultaneously, seismologists interpret a seismic record section from a recent earthquake noting when seismic waves arrive at various points around Earth. The two groups of students then compare the

  9. A contribution to understanding the structure of amphivasal secondary bundles in monocotyledons

    Directory of Open Access Journals (Sweden)

    Joanna Jura-Morawiec

    2014-04-01

    Full Text Available Secondary growth of monocotyledonous plants is connected with the activity of the monocot cambium that accumulates most of the derivatives inner to the cambial cylinder. These derivatives differentiate into (a secondary bundles with the amphivasal arrangement, i.e. xylem composed of tracheids surrounds the phloem cells and (b the parenchymatous secondary conjunctive tissue in which the bundles are embedded. The amphivasal secondary bundles differ in the arrangement of xylem cells as visible on single cross sections through the secondary body of the monocots. Apart from the bundles with typical ring of tracheids also the bundles where tracheids do not quite surround the phloem are present. We aimed to elucidate the cross sectional anatomy of the amphivasal secondary bundles with the use of the serial sectioning method which allowed us to follow very precisely the bundle structure along its length. The studies were carried out with the samples of secondary tissues collected from the stem of Dracaena draco L. growing in the greenhouses of the Polish Academy of Sciences Botanical Garden – CBDC in Powsin and the Adam Mickiewicz University Botanical Garden. The material was fixed in a mixture of glycerol and ethanol (1:1; v/v, dehydrated stepwise with graded ethanol series and finally embedded in epon resin. Afterwards, the material was sectioned with microtome into continuous series of thin (3 μm sections, stained with PAS/toluidine blue and examined under the light microscope. The results, described in details in Jura‑Morawiec & Wiland-Szymańska (2014, revealed novel facts about tracheids arrangement. Each amphivasal bundle is composed of sectors where tracheids form a ring as well as of such where tracheids are separated by vascular parenchyma cells. We hypothesize that strands of vascular parenchyma cells locally separating the tracheids enable radial transport of assimilates from sieve elements of the bundle towards the sink tissues, e

  10. Understanding the response of pulsed electric field on osteoblast functions in three-dimensional mesh structures.

    Science.gov (United States)

    Kumar, A; Nune, K C; Misra, Rdk

    2016-10-01

    The endogenous electric field plays a determining role in impacting biological functions including communication with the physiological system, brain, and bone regeneration by influencing cellular functions. From this perspective, the objective of the study described here is to elucidate the effect of external electric field under dynamic conditions, in providing a guiding cue to osteoblasts in terms of cell-cell interactions and synthesis of prominent adhesion and cytoskeleton proteins. This was accomplished using pulsed direct current electric field of strength 0.1-1 V/cm. The electric field provided guided cue to the cells to migrate toward cathode. Membrane blebbing or necrosis was nearly absent in the vicinity of cathode at 0.1 and 0.5 V/cm electric field strength. Moreover, a higher cell proliferation as well as higher expression of vinculin and densely packed actin stress fibers was observed. At anode, the cells though healthy but expression of actin and vinculin was less. We underscore for the first time that the biological functionality can be favorably modulated on 3D printed scaffolds in the presence of electric field and under dynamic conditions with consequent positive effect on cell proliferation, growth, and expression level of prominent proteins. © The Author(s) 2016.

  11. Deeper understanding about the genetic structure of dengue virus using SVM

    Directory of Open Access Journals (Sweden)

    Choi Subin

    2016-01-01

    Full Text Available Dengue fever, mainly found in the tropical and subtropical regions, is carried by mosquitoes. With the help of greenhouse effect, places considered to be a Dengue safe-zone are becoming more and more dangerous. Dengue fever shows similar aspects to MERS, which caused heavy casualties in South Korea; Dengue virus does not have clear treatments nor vaccines like MERS. Development of Dengue vaccine is actively investigated lately. However, it is not easy to succeed; the fact that Dengue’s 4 serotypes have different properties and that repeated infections worsen the symptoms. This research aims to analyze the 4 serotypes (DENV1, DENV2, DENV3, DENV4 using SVM and ANN algorithms to investigate the constraints in the development of Dengue’s vaccines and treatments.

  12. Fundamental Understanding of Ambient and High-Temperature Plasticity Phenomena in Structural Materials in Advanced Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Deo, Chaitanya; Zhu, Ting; McDowell, David

    2013-11-17

    The goal of this research project is to develop the methods and tools necessary to link unit processes analyzed using atomistic simulations involving interaction of vacancies and interstitials with dislocations, as well as dislocation mediation at sessile junctions and interfaces as affected by radiation, with cooperative influence on higher-length scale behavior of polycrystals. These tools and methods are necessary to design and enhance radiation-induced damage-tolerant alloys. The project will achieve this goal by applying atomistic simulations to characterize unit processes of: 1. Dislocation nucleation, absorption, and desorption at interfaces 2. Vacancy production, radiation-induced segregation of substitutional Cr at defect clusters (point defect sinks) in BCC Fe-Cr ferritic/martensitic steels 3. Investigation of interaction of interstitials and vacancies with impurities (V, Nb, Ta, Mo, W, Al, Si, P, S) 4. Time evolution of swelling (cluster growth) phenomena of irradiated materials 5. Energetics and kinetics of dislocation bypass of defects formed by interstitial clustering and formation of prismatic loops, informing statistical models of continuum character with regard to processes of dislocation glide, vacancy agglomeration and swelling, climb and cross slip This project will consider the Fe, Fe-C, and Fe-Cr ferritic/martensitic material system, accounting for magnetism by choosing appropriate interatomic potentials and validating with first principles calculations. For these alloys, the rate of swelling and creep enhancement is considerably lower than that of face-centered cubic (FCC) alloys and of austenitic Fe-Cr-Mo alloys. The team will confirm mechanisms, validate simulations at various time and length scales, and improve the veracity of computational models. The proposed research?s feasibility is supported by recent modeling of radiation effects in metals and alloys, interfacial dislocation transfer reactions in nano-twinned copper, and dislocation

  13. Cygnus Loop supernova remnant: new observations and a framework for understanding its structure and evolution

    International Nuclear Information System (INIS)

    Hester, J.J.

    1985-01-01

    New observational data on the Cygnus Loop supernova remnant (SNR) include: (1) a detailed high resolution comparison of x-ray and optical emission for a field in the SE; (2) a map of the [O III] electron temperature for the field previously studied by Hester, Parker, and Dufour (1983); and (3) CCD imagery of the NE limb in the light of four emission lines. A wide range of new and existing observations of the Loop are for the first time interpreted within the context of a single physical description. The Cygnus Loop is not an evaporative SNR evolving into the McKee and Ostriker (1977) ISM, nor are tiny cloudlets necessary to explain its morphology. The data show the Cygnus Loop to be evolving into a medium consisting primarily of an intercloud phase with N 0 approx. 0.1 cm -3 containing clouds with parsec dimensions and N 0 less than or equal to 10 cm -3 . The optical emission arises from extensive sheet like radiative shock fronts driven into the clouds. These fronts locally form the outer boundary of the remnant. The appearance of x-ray emission outside the optical emission on the limbs is due solely to projection effects. The distorted and bumpy shock front is shown to give rise in projection to the filamentary morphology of the remnant

  14. Alternative Conformational Model of a Seed Protein DeK1 for Better Understanding of Structure-Function Relationship

    Directory of Open Access Journals (Sweden)

    Surya Bhushan Kumar

    2010-12-01

    Full Text Available Understanding of the cell development and differentiation processes in plant seeds in general is poor. One gene, among others, that predominantly regulates the aleurone cell formation, differentiation and specification in seeds is called defective kernel (DeK1 and several cell biology and genetic experiments have unequivocally established this fact. However, the mechanism behind such processes is still unclear and understanding the protein functionality of DeK1 is vital to elucidating its role in endosperm cell development. Only preliminary investigations have been performed for just one domain of the protein in vitro and its functional implications have been highlighted lately. An initial attempt at in silico modeling of the protein has shown promise and necessitated thorough investigation of the protein to help understand structure-function relationship in details thus corroborating experimental findings and laying foundation for further studies. DeK1 sequences in public databases were used as raw material for elaborate computational analysis of the protein. DeK1 is a multi-pass membrane protein with interesting structural features and the present analysis provides an alternative model for DeK1 structure that can help pan both in vitro and in vivo studies. The transmembrane helices were shown to have a number of conserved charged and polar residues that can form salt bridges and help in ligand binding or transmitting an external signal in addition to maintaining structural integrity. The protein possesses a big loop of about 280-300 amino acid residues on the cytoplasmic side of the membrane. It has a number of putative phosphorylation sites, multiple cysteine residues and a high density of charged residues, all of which could be important for protein-protein interaction and signaling pathways. The loop has a nuclear localization propensity as well. The long C-terminal tail of DeK1 with homology to calpain domain may be activated by the big

  15. Anisotropy of magnetoviscous effect in structure-forming ferrofluids

    Science.gov (United States)

    Sreekumari, Aparna; Ilg, Patrick

    2015-07-01

    The magnetoviscous effect, change in viscosity with change in magnetic field strength, and the anisotropy of the magnetoviscous effect, change in viscosity with orientation of magnetic field, have been a focus of interest for four decades. A satisfactory understanding of the microscopic origin of anisotropy of the magnetoviscous effect in magnetic fluids is still a matter of debate and a field of intense research. Here, we present an extensive simulation study to understand the relation between the anisotropy of the magnetoviscous effect and the underlying change in microstructures of ferrofluids. Our results indicate that field-induced chainlike structures respond very differently depending on their orientation relative to the direction of an externally applied shear flow, which leads to a pronounced anisotropy of viscosity. In this work, we focus on three exemplary values of dipolar interaction strengths which correspond to weak, intermediate, and strong interactions between dipolar colloidal particles. We compare our simulation results with an experimental study on cobalt-based ferrofluids as well as with an existing theoretical model called the chain model. A nonmonotonic behavior in the anisotropy of the magnetoviscous effect is observed with increasing dipolar interaction strength and is explained in terms of microstructure formation.

  16. Advances in understanding the structure of borosilicate glasses: A Raman spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Manara, D.; Grandjean, A. [CEA Marcoule, Serv Confinement Deches and Vitrificat, DTCD, DEN - 30 (France); Neuville, D.R. [Institut Physique Globe, Physique des Mineraux et Magmas, CNRS, F-75252 Paris 05 (France)

    2009-05-15

    This study is focused on the behavior of ternary SiO{sub 2}-Na{sub 2}O-B{sub 2}O{sub 3} borosilicate glasses at temperatures between 298 and 1800 K. Unpolarized Raman spectra were measured up to high temperature. SiO{sub 2}-Na{sub 2}O-B{sub 2}O{sub 3} glass samples were prepared with different values of the ratio R [Na{sub 2}O]/[B{sub 2}O{sub 3}], while the ratio K = [SiO{sub 2}]/[B{sub 2}O{sub 3}] was kept constant and equal 2.12. Spectra were measured at room temperature in samples with 0.43 {<=} R {<=} 1.68, and the effect of the modifier content was clearly observed in these glasses, only in partial agreement with previous literature results. In particular, the formation in the glass of sodium-danburite units Na{sub 2}O-B{sub 2}O{sub 3}-2SiO{sub 2} was postulated. This feature led to a new assessment of R{sup *}, the critical value of R above which every new alkali atom added to the system breaks a Fo-O-Fo (Fo=glass former) bridge causing depolymerization of the glass. A revised formula is proposed to obtain the value of R{sup *} as a function of K. Raman spectra measured at high temperature yielded important information about the temperature-dependent evolution of the borosilicate system. In particular, borate and borosilicate units including tetra-coordinated boron seem to be unstable at high temperature, where the formation of metaborate chains or rings is fostered. Above 1500 degrees C, evaporation of borate compounds is clearly observed, stemming from the small sample size. (authors)

  17. Effects of a Co-operative Learning Strategy on Ninth-Graders' Understanding of Human Nutrition.

    Science.gov (United States)

    Soyibo, Kola; Evans, Hermel G.

    2002-01-01

    Looks at the effect of teaching strategies on a group's attitude toward biology and understanding human nutrition. Used an experimental group that participated in co-operative learning and a control group taught using the lecture method. Involves ninth graders (n=156) from two high schools in Jamaica. (Author/YDS)

  18. Effects of Representation Sequences and Spatial Ability on Students' Scientific Understandings about the Mechanism of Breathing

    Science.gov (United States)

    Wu, Hsin-Kai; Lin, Yu-Fen; Hsu, Ying-Shao

    2013-01-01

    The purpose of this study was to investigate the effects of representation sequences and spatial ability on students' scientific understandings about the mechanism of breathing in human beings. 130 seventh graders were assigned to two groups with different sequential combinations of static and dynamic representations: SD group (i.e., viewing…

  19. The Effect of Modeling and Visualization Resources on Student Understanding of Physical Hydrology

    Science.gov (United States)

    Marshall, Jilll A.; Castillo, Adam J.; Cardenas, M. Bayani

    2015-01-01

    We investigated the effect of modeling and visualization resources on upper-division, undergraduate and graduate students' performance on an open-ended assessment of their understanding of physical hydrology. The students were enrolled in one of five sections of a physical hydrology course. In two of the sections, students completed homework…

  20. Understanding Crowdsourcing: Effects of motivation and rewards on participation and performance in voluntary online activities

    NARCIS (Netherlands)

    W.A.M. Borst (Irma)

    2010-01-01

    textabstractCompanies increasingly outsource activities to volunteers that they approach via an open call on the internet. The phenomenon is called ‘crowdsourcing’. For an effective use of crowdsourcing it is important to understand what motivated these online volunteers and what is the influence of

  1. The Effect of Using the History of Sciences on Conceptual Understanding and Intrinsic Motivation

    Science.gov (United States)

    Blizak, Djanette

    2017-01-01

    This study investigates the effect of using the history of science in teaching geometrical optics on the motivation and conceptual understanding of first year university students. For this purpose, 54 students were randomly selected, then divided into two groups: the experimental group was taught by using history of science before traditional…

  2. Effect of Cooperative Learning Strategies on Students' Understanding of Concepts in Electrochemistry

    Science.gov (United States)

    Acar, Burcin; Tarhan, Leman

    2007-01-01

    The present study was conducted to investigate the degree of effectiveness of cooperative learning instruction over a traditional approach on 11th grade students' understanding of electrochemistry. The study involved forty-one 11th grade students from two science classes with the same teacher. To determine students' misconceptions concerning…

  3. Effectiveness of Instruction Based on the Constructivist Approach on Understanding Chemical Equilibrium Concepts

    Science.gov (United States)

    Akkus, Huseyin; Kadayifci, Hakki; Atasoy, Basri; Geban, Omer

    2003-01-01

    The purpose of this study was to identify misconceptions concerning chemical equilibrium concepts and to investigate the effectiveness of instruction based on the constructivist approach over traditional instruction on 10th grade students' understanding of chemical equilibrium concepts. The subjects of this study consisted of 71 10th grade…

  4. 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…

  5. Understanding the effectiveness of vegetated streamside management zones for protecting water quality (Chapter 5)

    Science.gov (United States)

    Philip Smethurst; Kevin Petrone; Daniel Neary

    2012-01-01

    We set out to improve understanding of the effectiveness of streamside management zones (SMZs) for protecting water quality in landscapes dominated by agriculture. We conducted a paired-catchment experiment that included water quality monitoring before and after the establishment of a forest plantation as an SMZ on cleared farmland that was used for extensive grazing....

  6. Student Teacher Understanding of the Greenhouse Effect, Ozone Layer Depletion, and Acid Rain.

    Science.gov (United States)

    Dove, Jane

    1996-01-01

    Describes the results of a survey designed to ascertain details of student teachers' knowledge and misconceptions about the greenhouse effect, acid rain, and ozone layer depletion. Results indicate familiarity with the issues but little understanding of the concepts involved and many commonly held misconceptions. (JRH)

  7. The Effects of Swedish Knife Model on Students' Understanding of the Digestive System

    Science.gov (United States)

    Cerrah Ozsevgec, Lale; Artun, Huseyin; Unal, Melike

    2012-01-01

    This study was designed to examine the effect of Swedish Knife Model on students' understanding of digestive system. A simple experimental design (pretest-treatment-posttest) was used in the study and internal comparison of the results of the one group was made. The sample consisted of 40 7th grade Turkish students whose ages range from 13 to 15.…

  8. Exploring the Effectiveness of a Measurement Error Tutorial in Helping Teachers Understand Score Report Results

    Science.gov (United States)

    Zapata-Rivera, Diego; Zwick, Rebecca; Vezzu, Margaret

    2016-01-01

    The goal of this study was to explore the effectiveness of a short web-based tutorial in helping teachers to better understand the portrayal of measurement error in test score reports. The short video tutorial included both verbal and graphical representations of measurement error. Results showed a significant difference in comprehension scores…

  9. Effectiveness of Understanding Relations between Community, Home, and School for Future Educators

    Science.gov (United States)

    Peralta, Claudia; Galaviz, Sonia

    2013-01-01

    As educators committed to preparing teachers to teach effectively across differences and in ways that actively resist perpetuating injustices, we have found that designing opportunities that take teachers into the children's community is the best way to learn about the cultural wealth existing in homes and to understand the importance of including…

  10. Encouraging a "Romantic Understanding" of Science: The Effect of the Nikola Tesla Story

    Science.gov (United States)

    Hadzigeorgiou, Yannis; Klassen, Stephen; Klassen, Cathrine Froese

    2012-01-01

    The purpose of this paper is to discuss and apply the notion of romantic understanding by outlining its features and its potential role in science education, to identify its features in the story of Nikola Tesla, and to describe an empirical study conducted to determine the effect of telling such a story to Grade 9 students. Elaborated features of…

  11. The Effect of Enriched Learning Environments on the Conceptual Understanding of Students: "The Erosion and Landslide"

    Science.gov (United States)

    Çoruhlu, Tülay Senel; Bilgin, Arzu Kirman; Nas, Sibel Er

    2016-01-01

    The aim of this research is to investigate the effect of enriched learning environments which have been developed in the framework of the "erosion and landslide" concepts on the conceptual understanding of students. A quasi-experimental method has been used in this research. The sample consists of 40 students. 5th grade students (aged…

  12. The Effect of a Conceptual Change Approach on Understanding of Students' Chemical Equilibrium Concepts

    Science.gov (United States)

    Atasoy, Basri; Akkus, Huseyin; Kadayifci, Hakki

    2009-01-01

    The purpose of this study was to compare the effects of a conceptual change approach over traditional instruction on tenth-grade students' conceptual achievement in understanding chemical equilibrium. The study was conducted in two classes of the same teacher with participation of a total of 44 tenth-grade students. In this study, a…

  13. The Effect of Herrmann Whole Brain Teaching Method on Students' Understanding of Simple Electric Circuits

    Science.gov (United States)

    Bawaneh, Ali Khalid Ali; Nurulazam Md Zain, Ahmad; Salmiza, Saleh

    2011-01-01

    The purpose of this study was to investigate the effect of Herrmann Whole Brain Teaching Method over conventional teaching method on eight graders in their understanding of simple electric circuits in Jordan. Participants (N = 273 students; M = 139, F = 134) were randomly selected from Bani Kenanah region-North of Jordan and randomly assigned to…

  14. Development of Solid State NMR Methods for the Structural Characterization of Membrane Proteins: Applications to Understand Multiple Sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Cosman, M; Tran, A T; Ulloa, J; Maxwell, R S

    2003-03-04

    Multiple sclerosis (MS) is a relapsing-remitting disorder of the central nervous system that results in the loss of the myelin sheaths insulating nerve fibers (axons). Strong evidence suggests that MS is an autoimmune disease mediated by T-cell and antibody responses against myelin antigens. Myelin oligodendrocyte glycoprotein (MOG) is a 26 kD to 28 kD an integral membrane protein of the central nervous system implicated as a target for autoaggressive antibodies in MS. To date, the conformation of MOG in association with the myelin membrane is unknown and the exact nature of the interactions between this protein and disease-inducing immune responses have not been determined. Since membrane associated proteins are typically characterized by decreased correlation times, solution state NMR methodologies are often impracticable. Membrane proteins are also often difficult to crystallize for X-ray diffraction studies, Consequently, there is an urgent need to develop new structure characterization tools for this important class of biomolecules. The research described here overviews the initial stages of our effort to develop an integrated, NMR based approach to structural studies of MOG over the many structural domains it is postulated to posses. The structural knowledge gained about this important MS antigen in its native environment will contribute significantly to our understanding of its function in vivo. This project will also aid in the development of therapeutics to inhibit the antigedantibody interaction and thus prevent demyelination in MS patients.

  15. 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.

  16. 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

  17. Effect of science magic applied in interactive lecture demonstrations on conceptual understanding

    Science.gov (United States)

    Taufiq, Muhammad; Suhandi, Andi; Liliawati, Winny

    2017-08-01

    Research about the application of science magic-assisting Interactive Lecture Demonstrations (ILD) has been conducted. This research is aimed at providing description about the comparison of the improvement of the conceptual understanding of lesson on pressure between students who receive physics lesson through science magic-assisting ILD and students who receive physics lesson through ILD without science magic. This research used a quasi-experiment methods with Control Group Pretest-Posttest Design. The subject of the research is all students of class VIII in one of MTs (Islamic junior high school) in Pekalongan. Research samples were selected using random sampling technique. Data about students' conceptual understanding was collected using test instrument of conceptual understanding in the form of multiple choices. N-gain average calculation was performed in order to determine the improvement of students' conceptual understanding. The result of the research shows that conceptual understanding of students on lesson about pressure who received lesson with ILD using science magic is higher than students who received lesson with ILD without science magic . Therefore, the conclusion is that the application of science magic ILD is more effective to improve the conceptual understanding of lesson on pressure.

  18. Understanding Teacher Effectiveness: Significant State Data Capacity Is Required to Measure and Improve Teacher Effectiveness. Data for Action 2012

    Science.gov (United States)

    Data Quality Campaign, 2012

    2012-01-01

    States are increasingly focused on understanding and improving teacher effectiveness. There are several funding opportunities that incentivize states to use data to inform measurements of teacher effectiveness. Local, state, and federal efforts support using data to improve teacher preparation programs. Preparation programs seek "access to data…

  19. Flow structure of knuckling effect in footballs

    OpenAIRE

    Asai, Takeshi; Kamemoto, Kyoji

    2011-01-01

    The flight trajectory of a non-spinning or slow-spinning soccer ball might fluctuate in unpredictable ways, as for example, in the many free kicks of C. Ronaldo. Such anomalous horizontal shaking or rapid falling is termed the ‘knuckling effect’. However, the aerodynamic properties and boundary-layer dynamics affecting a ball during the knuckling effect are not well understood. In this study, we analyse the characteristics of the vortex structure of a soccer ball subject to the knuckling effe...

  20. The effect of background music and song texts on the emotional understanding of children with autism.

    Science.gov (United States)

    Katagiri, June

    2009-01-01

    The purpose of this study was to examine the effect of background music and song texts to teach emotional understanding to children with autism. Participants were 12 students (mean age 11.5 years) with a primary diagnosis of autism who were attending schools in Japan. Each participant was taught four emotions to decode and encode: happiness, sadness, anger, and fear by the counterbalanced treatment-order. The treatment consisted of the four conditions: (a) no contact control (NCC)--no purposeful teaching of the selected emotion, (b) contact control (CC)--teaching the selected emotion using verbal instructions alone, (c) background music (BM)--teaching the selected emotion by verbal instructions with background music representing the emotion, and singing songs (SS)--teaching the selected emotion by singing specially composed songs about the emotion. Participants were given a pretest and a posttest and received 8 individual sessions between these tests. The results indicated that all participants improved significantly in their understanding of the four selected emotions. Background music was significantly more effective than the other three conditions in improving participants' emotional understanding. The findings suggest that background music can be an effective tool to increase emotional understanding in children with autism, which is crucial to their social interactions.

  1. Understanding the implementation and adoption of an information technology intervention to support medicine optimisation in primary care: qualitative study using strong structuration theory.

    Science.gov (United States)

    Jeffries, Mark; Phipps, Denham; Howard, Rachel L; Avery, Anthony; Rodgers, Sarah; Ashcroft, Darren

    2017-05-10

    Using strong structuration theory, we aimed to understand the adoption and implementation of an electronic clinical audit and feedback tool to support medicine optimisation for patients in primary care. This is a qualitative study informed by strong structuration theory. The analysis was thematic, using a template approach. An a priori set of thematic codes, based on strong structuration theory, was developed from the literature and applied to the transcripts. The coding template was then modified through successive readings of the data. Clinical commissioning group in the south of England. Four focus groups and five semi-structured interviews were conducted with 18 participants purposively sampled from a range of stakeholder groups (general practitioners, pharmacists, patients and commissioners). Using the system could lead to improved medication safety, but use was determined by broad institutional contexts; by the perceptions, dispositions and skills of users; and by the structures embedded within the technology. These included perceptions of the system as new and requiring technical competence and skill; the adoption of the system for information gathering; and interactions and relationships that involved individual, shared or collective use. The dynamics between these external, internal and technological structures affected the adoption and implementation of the system. Successful implementation of information technology interventions for medicine optimisation will depend on a combination of the infrastructure within primary care, social structures embedded in the technology and the conventions, norms and dispositions of those utilising it. Future interventions, using electronic audit and feedback tools to improve medication safety, should consider the complexity of the social and organisational contexts and how internal and external structures can affect the use of the technology in order to support effective implementation. © Article author(s) (or their

  2. Examining the Effects of Model-Based Inquiry on Concepetual Understanding and Engagement in Science

    Science.gov (United States)

    Baze, Christina L.

    Model-Based Inquiry (MBI) is an instructional model which engages students in the scientific practices of modeling, explanation, and argumentation while they work to construct explanations for natural phenomena. This instructional model has not been previously studied at the community college level. The purpose of this study is to better understand how MBI affects the development of community college students' conceptual understanding of evolution and engagement in the practices of science. Mixed-methods were employed to collect quantitative and qualitative data through the multiple-choice Concepts Inventory of Natural Selection, student artifacts, and semi-structured interviews. Participants were enrolled in Biology Concepts, an introductory class for non-science majors, at a small, rural community college in the southwestern United States. Preliminary data shows that conceptual understanding is not adversely affected by the implementation of MBI, and that students gain valuable insights into the practices of science. Specifically, students who participated in the MBI intervention group gained a better understanding of the role of models in explaining and predicting phenomena and experienced feeling ownership of their ideas, an appropriate depth of thinking, more opportunities for collaboration, and coherence and context within the unit. Implications of this study will be of interest to postsecondary science educators and researchers who seek to reform and improve science education.

  3. 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.

  4. Flow structure of knuckling effect in footballs

    Science.gov (United States)

    Asai, Takeshi; Kamemoto, Kyoji

    2011-07-01

    The flight trajectory of a non-spinning or slow-spinning soccer ball might fluctuate in unpredictable ways, as for example, in the many free kicks of C. Ronaldo. Such anomalous horizontal shaking or rapid falling is termed the ‘knuckling effect’. However, the aerodynamic properties and boundary-layer dynamics affecting a ball during the knuckling effect are not well understood. In this study, we analyse the characteristics of the vortex structure of a soccer ball subject to the knuckling effect (knuckleball), using high-speed video images and smoke-generating agents. Two high-speed video cameras were set at one side and in front of the ball trajectory between the ball position and the goal; further, photographs were taken at 1000 fps and a resolution of 1024×512 pixels. Although in a previous study (Taneda, 1978), shedding of horseshoe vortices was observed for smooth spheres in the Reynolds number (Re) range of 3.8×105ball, the vortex structure, which consisted of distorted loop vortices, appeared in the wake behind the ball in the supercritical Re number region. Moreover, after the knuckleballs were airborne, large-scale undulations were observed in the vortex trail visualised with a smoke technique. On the other hand, aerodynamic forces acting on the ball were estimated from the data of the ball’s flight trajectory, and a statistically high correlation (r=0.94, pball.

  5. Effectiveness of Dry Cell Microscopic Simulation (DCMS) to Promote Conceptual Understanding about Battery

    Science.gov (United States)

    Catur Wibowo, Firmanul; Suhandi, Andi; Rusdiana, Dadi; Samsudin, Achmad; Rahmi Darman, Dina; Faizin, M. Noor; Wiyanto; Supriyatman; Permanasari, Anna; Kaniawati, Ida; Setiawan, Wawan; Karyanto, Yudi; Linuwih, Suharto; Fatah, Abdul; Subali, Bambang; Hasani, Aceng; Hidayat, Sholeh

    2017-07-01

    Electricity is a concept that is abstract and difficult to see by eye directly, one example electric shock, but cannot see the movement of electric current so that students have difficulty by students. A computer simulation designed to improve the understanding of the concept of the workings of the dry cell (battery). This study was conducted to 82 students (aged 18-20 years) in the experimental group by learning to use the Dry Cell Microscopic Simulation (DCMS). The result shows the improving of students’ conceptual understanding scores from post test were statistically significantly of the workings of batteries. The implication using computer simulations designed to overcome the difficulties of conceptual understanding, can effectively help students in facilitating conceptual change.

  6. Photoelectric effect experiment for understanding the concept of quantization of radiation energy

    Directory of Open Access Journals (Sweden)

    Yeimy Gerardine Berrios Saavedra

    2016-09-01

    Full Text Available This study forms part of research on the teaching of physics. The question that directed it was: How a proposed classroom, based on the photoelectric effect experiment helps pres-service teachers of physics of the Universidad Pedagógica Nacional to expand their understanding of the concept of quantization energy of radiation? The construction of the theoretical framework developed on the one hand, with scientific ideas about the quantization of energy, and moreover, with the educational proposals of teaching for understanding. This pedagogical approach was guided by the investigative gaze of the study methodology based on design, taking as main element the use of learning tools such as the task to Predict, Experiment and Explain (PEE. It was found that these tasks fomented the initial understandings of students about the concept, while they enriched and transformed progressively their models and scientific ideas, promoting aspects of scientific work in developing curiosity, imagination and motivation.

  7. Understanding Data Structures

    Science.gov (United States)

    1975-02-01

    Data Division. Ibis task has hrrn left to the sub-schema processor as defined by the DBTG. A Frame (a sot of format logical rules) defines the DMLP...C^nclo h,\\r hrrn p.onrratet) to (lctrrniif>e tfie valuPS, relative to ACTl’itl, of ill MMM m the ITMS U’A NEXTLEVnUT««(lTMS) (■<,.|.. I ,K. \\i

  8. Arabidopsis mutants in sphingolipid synthesis as tools to understand the structure and function of membrane microdomains in plasmodesmata

    Directory of Open Access Journals (Sweden)

    ARIADNA eGONZÁLEZ-SOLÍS

    2014-01-01

    Full Text Available Plasmodesmata –intercellular channels that communicate adjacent cells– possess complex membranous structures. Recent evidences indicate that plasmodesmata contain membrane microdomains. In order to understand how these submembrane regions collaborate to plasmodesmata function, it is necessary to characterize their size, composition and dynamics. An approach that can shed light on these microdomain features is based on the use of Arabidopsis mutants in sphingolipid synthesis. Sphingolipids are canonical components of microdomains together with sterols and some glycerolipids. Moreover, sphingolipids are transducers in pathways that display programmed cell death as a defense mechanism against pathogens. The study of Arabidopsis mutants would allow determining which structural features of the sphingolipids are important for the formation and stability of microdomains, and if defense signaling networks using sphingoid bases as second messengers are associated to plasmodesmata operation. Such studies need to be complemented by analysis of the ultrastructure and the use of protein probes for plasmodesmata microdomains and may constitute a very valuable source of information to analyze these membrane structures.

  9. Arabidopsis mutants in sphingolipid synthesis as tools to understand the structure and function of membrane microdomains in plasmodesmata

    Science.gov (United States)

    González-Solís, Ariadna; Cano-Ramírez, Dora L.; Morales-Cedillo, Francisco; Tapia de Aquino, Cinthya; Gavilanes-Ruiz, Marina

    2013-01-01

    Plasmodesmata—intercellular channels that communicate adjacent cells—possess complex membranous structures. Recent evidences indicate that plasmodesmata contain membrane microdomains. In order to understand how these submembrane regions collaborate to plasmodesmata function, it is necessary to characterize their size, composition and dynamics. An approach that can shed light on these microdomain features is based on the use of Arabidopsis mutants in sphingolipid synthesis. Sphingolipids are canonical components of microdomains together with sterols and some glycerolipids. Moreover, sphingolipids are transducers in pathways that display programmed cell death as a defense mechanism against pathogens. The study of Arabidopsis mutants would allow determining which structural features of the sphingolipids are important for the formation and stability of microdomains, and if defense signaling networks using sphingoid bases as second messengers are associated to plasmodesmata operation. Such studies need to be complemented by analysis of the ultrastructure and the use of protein probes for plasmodesmata microdomains and may constitute a very valuable source of information to analyze these membrane structures. PMID:24478783

  10. Periodic vortex pinning by regular structures in Nb thin films: magnetic vs. structural effects

    Science.gov (United States)

    Montero, Maria Isabel; Jonsson-Akerman, B. Johan; Schuller, Ivan K.

    2001-03-01

    The defects present in a superconducting material can lead to a great variety of static and dynamic vortex phases. In particular, the interaction of the vortex lattice with regular arrays of pinning centers such as holes or magnetic dots gives rise to commensurability effects. These commensurability effects can be observed in the magnetoresistance and in the critical current dependence with the applied field. In recent years, experimental results have shown that there is a dependence of the periodic pinning effect on the properties of the vortex lattice (i.e. vortex-vortex interactions, elastic energy and vortex velocity) and also on the dots characteristics (i.e. dot size, distance between dots, magnetic character of the dot material, etc). However, there is not still a good understanding of the nature of the main pinning mechanisms by the magnetic dots. To clarify this important issue, we have studied and compared the periodic pinning effects in Nb films with rectangular arrays of Ni, Co and Fe dots, as well as the pinning effects in a Nb film deposited on a hole patterned substrate without any magnetic material. We will discuss the differences on pinning energies arising from magnetic effects as compared to structural effects of the superconducting film. This work was supported by NSF and DOE. M.I. Montero acknowledges postdoctoral fellowship by the Secretaria de Estado de Educacion y Universidades (Spain).

  11. Effect of a Diagram on Primary Students' Understanding About Electric Circuits

    Science.gov (United States)

    Preston, Christine Margaret

    2017-09-01

    This article reports on the effect of using a diagram to develop primary students' conceptual understanding about electric circuits. Diagrammatic representations of electric circuits are used for teaching and assessment despite the absence of research on their pedagogical effectiveness with young learners. Individual interviews were used to closely analyse Years 3 and 5 (8-11-year-old) students' explanations about electric circuits. Data was collected from 20 students in the same school providing pre-, post- and delayed post-test dialogue. Students' thinking about electric circuits and changes in their explanations provide insights into the role of diagrams in understanding science concepts. Findings indicate that diagram interaction positively enhanced understanding, challenged non-scientific views and promoted scientific models of electric circuits. Differences in students' understanding about electric circuits were influenced by prior knowledge, meta-conceptual awareness and diagram conventions including a stylistic feature of the diagram used. A significant finding that students' conceptual models of electric circuits were energy rather than current based has implications for electricity instruction at the primary level.

  12. Effects of multiple scattering on structural color in disordered colloids

    Science.gov (United States)

    Hwang, Victoria; Stephenson, Anna; Manoharan, Vinothan N.

    Disordered packings of colloidal spheres can show structural colors that are independent of the angle between light source and observer (E.R. Dufresne et al, Adv. Mater. 2010, XX, 1-6). This phenomenon arises from constructive interference of scattered light, but the disordered structure produces homogeneous colors, in contrast to the angle-dependent, or iridescent, colors of colloidal crystals. Although the color can be understood qualitatively through single-scattering models, these systems also show weak multiple scattering where neither single scattering nor diffusive transport assumptions are valid. To understand the effect of multiple scattering on the color, we perform polarization experiments to characterize multiple scattering in structurally-colored samples. We find that multiple scattering dominates at short wavelengths. In the observed reflection spectrum, this contribution adds to the single scattering from individual particles and from interference between scattered waves. Because multiple scattering reduces the saturation of color, we seek to minimize its effects for applications. To do this, we calculate the transport length of disordered colloids using Mie theory and use microfluidics to find the regimes of sample thickness that lead to optimal color saturation. Xerox University Affairs Committee, NSF GRFP 2015200426.

  13. Applications of condensed matter understanding to medical tissues and disease progression: Elemental analysis and structural integrity of tissue scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, D.A., E-mail: d.a.bradley@surrey.ac.u [Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Farquharson, M.J. [Department of Radiography, School of Community and Health Sciences, City University, London (United Kingdom); Gundogdu, O. [Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Al-Ebraheem, Alia [Department of Radiography, School of Community and Health Sciences, City University, London (United Kingdom); Che Ismail, Elna [Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Kaabar, W., E-mail: w.kaabar@surrey.ac.u [Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Bunk, O. [Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Pfeiffer, F. [Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Falkenberg, G. [Hamburger Synchrotronstrahlungslabor HASYLAB at Deutsches Elektronensynchrotron DESY, Notkestr. 85, D-22603 Hamburg (Germany); Bailey, M. [Surrey Ion Beam Centre, Advanced Technology Institute, University of Surrey, Guildford GU2 7XH (United Kingdom)

    2010-02-15

    The investigations reported herein link tissue structure and elemental presence with issues of environmental health and disease, exemplified by uptake and storage of potentially toxic elements in the body, the osteoarthritic condition and malignancy in the breast and other soft tissues. Focus is placed on application of state-of-the-art ionizing radiation techniques, including, micro-synchrotron X-ray fluorescence (mu-SXRF) and particle-induced X-ray emission/Rutherford backscattering mapping (mu-PIXE/RBS), coherent small-angle X-ray scattering (cSAXS) and X-ray phase-contrast imaging, providing information on elemental make-up, the large-scale organisation of collagen and anatomical features of moderate and low atomic number media. For the particular situations under investigation, use of such facilities is allowing information to be obtained at an unprecedented level of detail, yielding new understanding of the affected tissues and the progression of disease.

  14. Informing people about radiation risks: a review of obstacles to public understanding and effective risk communication

    International Nuclear Information System (INIS)

    Covello, V.T.

    1988-01-01

    This paper reviews the literature on informing people about radiation risks. The paper focuses on obstacles to public understanding and effective risk communication. The paper concludes with a set of guidelines for communicating information about radiation risks to the public. The paper also includes an appendix that reviews the literature on one of the most important tools for communicating information about radiation risks: risk comparisons

  15. Understanding treatment effect mechanisms of the CAMBRA randomized trial in reducing caries increment

    OpenAIRE

    Cheng, J; Chaffee, BW; Cheng, NF; Gansky, SA; Featherstone, JDB

    2015-01-01

    © International & American Associations for Dental Research 2014. The Caries Management By Risk Assessment (CAMBRA) randomized controlled trial showed that an intervention featuring combined antibacterial and fluoride therapy significantly reduced bacterial load and suggested reduced caries increment in adults with 1 to 7 baseline cavitated teeth. While trial results speak to the overall effectiveness of an intervention, insight can be gained from understanding the mechanism by which an int...

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

    Science.gov (United States)

    Kissine, Mikhail; Cano-Chervel, Julie; Carlier, Sophie; De Brabanter, Philippe; Ducenne, Lesley; Pairon, Marie-Charlotte; Deconinck, Nicolas; Delvenne, Véronique; Leybaert, Jacqueline

    2015-01-01

    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.

  17. Middle-School Understanding of the Greenhouse Effect using a NetLogo Computer Model

    Science.gov (United States)

    Schultz, L.; Koons, P. O.; Schauffler, M.

    2009-12-01

    We investigated the effectiveness of a freely available agent based, modeling program as a learning tool for seventh and eighth grade students to explore the greenhouse effect without added curriculum. The investigation was conducted at two Maine middle-schools with 136 seventh-grade students and 11 eighth-grade students in eight classes. Students were given a pre-test that consisted of a concept map, a free-response question, and multiple-choice questions about how the greenhouse effect influences the Earth's temperature. The computer model simulates the greenhouse effect and allows students to manipulate atmospheric and surface conditions to observe the effects on the Earth’s temperature. Students explored the Greenhouse Effect model for approximately twenty minutes with only two focus questions for guidance. After the exploration period, students were given a post-test that was identical to the pre-test. Parametric post-test analysis of the assessments indicated middle-school students gained in their understanding about how the greenhouse effect influences the Earth's temperature after exploring the computer model for approximately twenty minutes. The magnitude of the changes in pre- and post-test concept map and free-response scores were small (average free-response post-test score of 7.0) compared to an expert's score (48), indicating that students understood only a few of the system relationships. While students gained in their understanding about the greenhouse effect, there was evidence that students held onto their misconceptions that (1) carbon dioxide in the atmosphere deteriorates the ozone layer, (2) the greenhouse effect is a result of humans burning fossil fuels, and (3) infrared and visible light have similar behaviors with greenhouse gases. We recommend using the Greenhouse Effect computer model with guided inquiry to focus students’ investigations on the system relationships in the model.

  18. Quantitative Analysis of the Effective Functional Structure in Yeast Glycolysis

    Science.gov (United States)

    De la Fuente, Ildefonso M.; Cortes, Jesus M.

    2012-01-01

    The understanding of the effective functionality that governs the enzymatic self-organized processes in cellular conditions is a crucial topic in the post-genomic era. In recent studies, Transfer Entropy has been proposed as a rigorous, robust and self-consistent method for the causal quantification of the functional information flow among nonlinear processes. Here, in order to quantify the functional connectivity for the glycolytic enzymes in dissipative conditions we have analyzed different catalytic patterns using the technique of Transfer Entropy. The data were obtained by means of a yeast glycolytic model formed by three delay differential equations where the enzymatic rate equations of the irreversible stages have been explicitly considered. These enzymatic activity functions were previously modeled and tested experimentally by other different groups. The results show the emergence of a new kind of dynamical functional structure, characterized by changing connectivity flows and a metabolic invariant that constrains the activity of the irreversible enzymes. In addition to the classical topological structure characterized by the specific location of enzymes, substrates, products and feedback-regulatory metabolites, an effective functional structure emerges in the modeled glycolytic system, which is dynamical and characterized by notable variations of the functional interactions. The dynamical structure also exhibits a metabolic invariant which constrains the functional attributes of the enzymes. Finally, in accordance with the classical biochemical studies, our numerical analysis reveals in a quantitative manner that the enzyme phosphofructokinase is the key-core of the metabolic system, behaving for all conditions as the main source of the effective causal flows in yeast glycolysis. PMID:22393350

  19. The Effect of Topical Structure Analysis Instruction on University Students' Writing Quality

    Science.gov (United States)

    Liangprayoon, Somlak; Chaya, Walaiporn; Thep-ackraphong, Tipa

    2013-01-01

    Coherence is considered one of the characteristics of effective writing. Topical structure analysis (TSA) has been taught to students as a revision strategy to raise their awareness of importance of textual coherence and helps them clearly understand its concept. This study aimed to investigate the effectiveness of TSA instruction in improving…

  20. The impact of the linkage between grade distribution and petrofabric on the understanding of structurally controlled mineral deposits: Ouro Fino Gold Mine, Brazil

    Science.gov (United States)

    Monteiro, R. N.; Fyfe, W. S.; Chemale, F.

    2004-06-01

    Ore deposit structural analysis, using a combination of structural geology and geostatistics, has direct application in the mining industry. Its main goal is to integrate structural measurements and assay data to create a method in which structurally controlled deposits are modeled numerically. This provides guidance to grade control and pit optimization during mining, improves prediction of orebody geometry and orientation, and provides more effective exploration strategies for surrounding areas. The method leads to a better understanding of how mineralized fluids percolated and were focused at the Ouro Fino Mine, a shear zone-hosted gold deposit in Minas Gerais State, Brazil. In this mine, gold is distributed along permeability pathways within rock fabrics that were produced or modified during the Brasiliano orogeny, when the Espinhaço-Araçuaı´ sequence was inverted towards the São Francisco craton during a basement-involved fold-and-thrust regime. The resulting permeable zones are conformable with the C surface, within which two other clusters of fabric elements control the large-scale features of the mineralization: (1) a cluster of fabric elements (mineral, stretching and intersection lineations) that plunges SE; and (2) a sub-horizontal cluster along folds and intersection lineations and the strike of the shear zone.

  1. Understanding peer effects - On the nature, estimation and channels of peer effects

    NARCIS (Netherlands)

    Feld, J.F.; Zölitz, U.N.

    2016-01-01

    This paper estimates peer effects in a university context where students are randomly assigned to sections. While students benefit from better peers on average, low-achieving students are harmed by high-achieving peers. Analyzing students’ course evaluations suggests that peer effects are driven by

  2. Understanding peer effects : on the nature, estimation and channels of peer effects

    NARCIS (Netherlands)

    Feld, J.F.; Zölitz, U.N.

    2016-01-01

    This paper estimates peer effects in a university context where students are randomly assigned to sections. While students benefit from better peers on average, lowachieving students are harmed by high-achieving peers. Analyzing students’ course evaluations suggests that peer effects are driven by

  3. Towards a better understanding of the geometrical and orientational aspects of the electronic structure of halogens (F–I) adsorption on graphene

    International Nuclear Information System (INIS)

    Widjaja, Hantarto; Jiang, Zhong-Tao; Altarawneh, Mohammednoor; Yin, Chun-Yang; Goh, Bee-Min; Mondinos, Nicholas; Dlugogorski, Bogdan Z.

    2015-01-01

    Graphical abstract: - Highlights: • Examines the orientation (zigzag, armchair) effects of F/Cl/Br/I-adsorbed graphene. • F cases are site-dependent, while Cl/Br/I cases have minimal orientation dependence. • F is adsorbed to graphene at about three times stronger than Cl/Br/I. • To prompt re-examination of elemental-graphene systems to account for orientation. - Abstract: Adding impurities or doping through adsorption is an effective way to modify the properties of graphene-based materials. The capability of making predictions pertinent to the trends of elemental adsorption on graphene is very instrumental towards a better understanding of the more complex adsorption cases. It also affords useful guidelines for fabricating 2-D graphene materials with novel properties. The electronic structure of elemental adsorption on graphene is affected by side of adsorption (single- or double-sided), site of adsorption (i.e. bridge, hollow or top), and the relative orientation of the adsorbed sites (i.e. zigzag or armchair). In this contribution, we apply density functional theory (DFT) calculations to investigate the electronic structures of halogens (F, Cl, Br, I) adsorbed on graphene at lower concentrations spanning 1:6, 1:8 and 1:18 atomic ratios, in order to elucidate effects of adsorption trends. We demonstrate that adsorption of F is merely site-dependent (top). On the contrary, adsorptions of Cl, Br and I display a minimal dependence towards orientation (i.e. the effects of the deployed supercells). Our findings provide a deeper understanding of the elemental adsorption on graphene in terms of geometry which may aid in reexamining previous studies and producing better predictions for future studies, in which the inclusion of orientation is indispensable.

  4. Analysis of the effect of specific vocabulary instruction on high school chemistry students' knowledge and understanding

    Science.gov (United States)

    Labrosse, Peggy

    The purpose of this study was to analyze the effects of specific vocabulary instruction on high school chemistry students' knowledge and understanding. Students might be able to formally recite a definition for a term without actually having understood the meaning of the term and its connection to other terms or to related concepts. Researchers (Cassels & Johnstone, 1983; Gabel, 1999; Johnstone, 1991) have been studying the difficulty students have in learning science, particularly chemistry. Gabel (1999) suggests that, "while research into misconceptions (also known as alternative conceptions) and problem-solving has dominated the field for the past 25 years, we are no closer to a solution that would improve the teaching and learning of chemistry" (P. 549). Gabel (1999) relates the difficulty in learning chemistry to use of language. She refers to student difficulty both with words that have more than one meaning in English and with words that are used to mean one idea in chemistry and another idea in every day language. The Frayer Model, a research-based teaching strategy, is a graphic organizer which students use to create meaningful definitions for terms in context (Frayer, Frederick, & Klausmeier, 1969). It was used as the treatment---the specific vocabulary instruction---in this research study. The researcher collected and analyzed data to answer three research questions that focused on the effect of using the Frayer model (a graphic organizer) on high school students' knowledge and understanding of academic language used in chemistry. The research took place in a New England high school. Four intact chemistry classes provided the student participants; two classes were assigned to the treatment group (TG) and two classes were assigned to the control group (CG). The TG received vocabulary instruction on 14 chosen terms using the Frayer Model. The CG received traditional vocabulary instruction with no special attention to the 14 terms selected for this study

  5. Integrated Experimental and Computational Approach to Understand the Effects of Heavy Ion Radiation on Skin Homeostasis.

    Energy Technology Data Exchange (ETDEWEB)

    von Neubeck, Claere; Shankaran, Harish; Geniza, Matthew; Kauer, Paula M.; Robinson, Robert J.; Chrisler, William B.; Sowa, Marianne B.

    2013-08-08

    The effects of low dose high linear energy transfer (LET) radiation on human health are of concern for both space and clinical exposures. As epidemiological data for such radiation exposures are scarce for making relevant predictions, we need to understand the mechanism of response especially in normal tissues. Our objective here is to understand the effects of heavy ion radiation on tissue homeostasis in a realistic model system. Towards this end, we exposed an in vitro three dimensional skin equivalent to low fluences of Neon (Ne) ions (300 MeV/u), and determined the differentiation profile as a function of time following exposure using immunohistochemistry. We found that Ne ion exposures resulted in transient increases in the tissue regions expressing the differentiation markers keratin 10, and filaggrin, and more subtle time-dependent effects on the number of basal cells in the epidermis. We analyzed the data using a mathematical model of the skin equivalent, to quantify the effect of radiation on cell proliferation and differentiation. The agent-based mathematical model for the epidermal layer treats the epidermis as a collection of heterogeneous cell types with different proliferation/differentiation properties. We obtained model parameters from the literature where available, and calibrated the unknown parameters to match the observed properties in unirradiated skin. We then used the model to rigorously examine alternate hypotheses regarding the effects of high LET radiation on the tissue. Our analysis indicates that Ne ion exposures induce rapid, but transient, changes in cell division, differentiation and proliferation. We have validated the modeling results by histology and quantitative reverse transcription polymerase chain reaction (qRT-PCR). The integrated approach presented here can be used as a general framework to understand the responses of multicellular systems, and can be adapted to other epithelial tissues.

  6. "There is a chain of connections": using syndemics theory to understand HIV treatment side effects.

    Science.gov (United States)

    Gagnon, Marilou

    2018-03-12

    Side effects are central to the experience of living longer with HIV but rarely have they been studied alone. Unlike other aspects of that experience, like quality of life, treatment adherence, chronicity, episodic disability, aging, health, and viral load suppression, side effects have not benefited from the same level of empirical and theoretical engagement from qualitative researchers. In this paper, we draw on syndemics theory and 50 qualitative interviews to better understand the experience of HIV treatment side effects. Two main categories were identified in the data: side effects as a product and side effects as a risk factor. The first category suggests that side effects are not just the product of taking antiretroviral drugs. They are also the product of particular conditions and tend to cluster with other health problems. The second category puts forward the idea that side effects can act as a syndemic risk factor by exposing PLWH to a greater risk of developing health problems and creating conditions in which psychosocial issues are more likely to emerge. The paper concludes by calling for more research on the complex nature of side effects and for the development of comprehensive approaches for the assessment and management of side effects.

  7. The Effect of Brain Based Learning on Second Grade Junior Students’ Mathematics Conceptual Understanding on Polyhedron

    Directory of Open Access Journals (Sweden)

    I Made Suarsana

    2017-06-01

    Full Text Available The aim of this study is to examine the effect of Brain Based Learning on second grade junior high school students’ conceptual understanding on polyhedron. This study was conducted by using post-test only control group quasi-experimental design. The subjects of this study were 148 students that divided into three classes. Two classes were taken as sample by using cluster random sampling technique. One of the classes was randomly selected as an experimental group and the other as control group. There were 48 students in experimental group and 51 students in control group. The data were collected with post-test which contained mathematical conceptual understanding on fractions. The post-test consisted of 8 essay question types.  The normality and variance homogeny test result showed that the scores are normally distributed and have no difference in variance. The data were analyzed by using one tailed t-test with significance level of 5%. The result of data analysis revealed that the value of t-test = 6,7096 greater than t-table = 1,987, therefore; the null hypothesis is rejected. There is positive effect of of Brain Based Learning on second grade junior students’ conceptual understanding in polyhedron.

  8. 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,…

  9. Embodied understanding.

    Science.gov (United States)

    Johnson, Mark

    2015-01-01

    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.

  10. Influence of osmolytes on protein and water structure: a step to understanding the mechanism of protein stabilization.

    Science.gov (United States)

    Bruździak, Piotr; Panuszko, Aneta; Stangret, Janusz

    2013-10-03

    Results concerning the thermostability of hen egg white lysozyme in aqueous solutions with stabilizing osmolytes, trimethylamine-N-oxide (TMAO), glycine (Gly), and its N-methyl derivatives, N-methylglycine (NMG), N,N-dimethylglycine (DMG), and N,N,N-trimethylglycine (betaine, TMG), have been presented. The combination of spectroscopic (IR) and calorimetric (DSC) data allowed us to establish a link between osmolytes' influence on water structure and their ability to thermally stabilize protein molecule. Structural and energetic characteristics of stabilizing osmolytes' and lysozyme's hydration water appear to be very similar. The osmolytes increase lysozyme stabilization in the order bulk water molecules affected by osmolytes in their surrounding. Obtained results verified the hypothesis concerning the role of water molecules in protein stabilization, explained the osmophobic effect, and finally helped to bring us nearer to the exact mechanism of protein stabilization by osmolytes.

  11. Effect of acid hydrolysis on starch structure and functionality: a review.

    Science.gov (United States)

    Wang, Shujun; Copeland, Les

    2015-01-01

    Acid hydrolysis is an important chemical modification that can significantly change the structural and functional properties of starch without disrupting its granular morphology. A deep understanding of the effect of acid hydrolysis on starch structure and functionality is of great importance for starch scientific research and its industrial applications. During acid hydrolysis, amorphous regions are hydrolyzed preferentially, which enhances the crystallinity and double helical content of acid hydrolyzed starch. This review discusses current understanding of the effect of acid hydrolysis on starch structure and functionality. The effects of acid hydrolysis on amylose content, chain length distribution of amylopectin molecules, molecular and crystalline organization (including lamellar structure) and granular morphology are considered. Functional properties discussed include swelling power, gelatinization, retrogradation, pasting, gel texture, and in vitro enzyme digestibility. The paper also highlights some promising applications of acid hydrolyzed starch (starch nanocrystals) in the preparation of biodegradable nanocomposites, bio-hydrogen, and slowly digestible starch-based healthy foods.

  12. Long and Short Term Cumulative Structural Priming Effects

    OpenAIRE

    Kaschak, Michael P.; Kutta, Timothy J.; Coyle, Jacqueline M.

    2012-01-01

    We present six experiments that examine cumulative structural priming effects (i.e., structural priming effects that accumulate across many utterances). Of particular interest is whether (1) cumulative priming effects transfer across language production tasks and (2) the transfer of cumulative priming effects across tasks persists over the course of a week. Our data suggest that cumulative structural priming effects do transfer across language production tasks (e.g., from written stem complet...

  13. 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...

  14. Large scale structure statistics: Finite volume effects

    Science.gov (United States)

    Colombi, S.; Bouchet, F. R.; Schaeffer, R.

    1994-01-01

    We study finite volume effects on the count probability distribution function PN(l) and the averaged Q-body correlations Xi-barQ (2 less than or = Q less than or equal 5). These statistics are computed for cubic cells, of size l. We use as an example the case of the matter distribution of a cold dark matter (CDM) universe involving approximately 3 x 105 particles. The main effect of the finiteness of the sampled volume is to induce an abrupt cut-off on the function PN(l) at large N. This clear signature makes an analysis of the consequences easy, and one can envisage a correction procedure. As a matter of fact, we demonstrate how an unfair sample can strongly affect the estimates of the functions Xi-barQ for Q greater than or = 3 (and decrease the measured zero of the two-body correlation function). We propose a method to correct for this are fact, or at least to evaluate the corresponding errors. We show that the correlations are systematically underestimated by direct measurements. We find that, once corrected, the statistical properties of the CDM universe appear compatible with the scaling relation SQ identically equals Xi-bar2 exp Q-1 = constant with respect to scale, in the non-linear regime; it was not the case with direct measurments. However, we note a deviation from scaling at scales close to the correlation length. It is probably due to the transition between the highly non-linear regime and the weakly correlated regime, where the functions SQ also seem to present a plateau. We apply the same procedure to simulations with hot dark matter (HDM) and white noise initial conditions, with similar results. Our method thus provides the first accurate measurement of the normalized skewness, S3, and the normalized kurtosis, S4, for three typical models of large scale structure formation in an expanding universe.

  15. Focus, accent, and argument structure: effects on language comprehension.

    Science.gov (United States)

    Birch, S; Clifton, C

    1995-01-01

    Four experiments investigated the effect of syntactic argument structure on the evaluation and comprehension of utterances with different patterns of pitch accents. Linguistic analyses of the relation between focus and prosody note that it is possible for certain accented constituents within a broadly focused phrase to project focus to the entire phrase. We manipulated focus requirements and accent in recorded question-answer pairs and asked listeners to make linguistic judgments of prosodic appropriateness (Experiments 1 and 3) or to make judgments based on meaningful comprehension (Experiments 2 and 4). Naive judgments of prosodic appropriateness were generally consistent with the linguistic analyses, showing preferences for utterances in which contextually new noun phrases received accent and old noun phrases did not, but suggested that an accented new argument NP was not fully effective in projecting broad focus to the entire VP. However, the comprehension experiments did demonstrate that comprehension of a sentence with broad VP focus was as efficient when only a lexical argument NP received accent as when both NP and verb received accent. Such focus projection did not occur when the argument NP was an "independent quantifier" such as nobody or everything. The results extend existing demonstrations that the ease of understanding spoken discourse depends on appropriate intonational marking of focus to cases where certain structurally-defined words can project focus-marking to an entire phrase.

  16. Effects of Error Messages on a Student's Ability to Understand and Fix Programming Errors

    Science.gov (United States)

    Beejady Murthy Kadekar, Harsha Kadekar

    Assemblers and compilers provide feedback to a programmer in the form of error messages. These error messages become input to the debugging model of the programmer. For the programmer to fix an error, they should first locate the error in the program, understand what is causing that error, and finally resolve that error. Error messages play an important role in all three stages of fixing of errors. This thesis studies the effects of error messages in the context of teaching programming. Given an error message, this work investigates how it effects student's way of 1) understanding the error, and 2) fixing the error. As part of the study, three error message types were developed--Default, Link and Example, to better understand the effects of error messages. The Default type provides an assembler-centric single line error message, the Link type provides a program-centric detailed error description with a hyperlink for more information, and the Example type provides a program centric detailed error description with a relevant example. All these error message types were developed for assembly language programming. A think aloud programming exercise was conducted as part of the study to capture the student programmer's knowledge model. Different codes were developed to analyze the data collected as part of think aloud exercise. After transcribing, coding, and analyzing the data, it was found that the Link type of error message helped to fix the error in less time and with fewer steps. Among the three types, the Link type of error message also resulted in a significantly higher ratio of correct to incorrect steps taken by the programmer to fix the error.

  17. Understanding semantics

    DEFF Research Database (Denmark)

    Thrane, Torben

    1997-01-01

    Understanding natural language is a cognitive, information-driven process. Discussing some of the consequences of this fact, the paper offers a novel look at the semantic effect of lexical nouns and the identification of reference types....

  18. Toward understanding subtle instrumentation effects associated with weak seismic events in the near field

    Czech Academy of Sciences Publication Activity Database

    Zahradník, J.; Plešinger, Axel

    2010-01-01

    Roč. 100, č. 1 (2010), s. 59-73 ISSN 0037-1106 R&D Projects: GA AV ČR IAA300120911 Grant - others:GA ČR(CZ) GA205/07/0502 Institutional research plan: CEZ:AV0Z30120515 Keywords : instrumentation effects * broadband seismology * weak earthquakes Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.027, year: 2010

  19. Understanding and Predicting Effect of Sodium Exposure on Microstructure of Grade 91 Steel

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meimei [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, K. [Argonne National Lab. (ANL), Argonne, IL (United States); Chen, Wei-Ying [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-08-01

    This report provides an update on the understanding of the effect of sodium exposures on microstructure and tensile properties of Grade 91 (G91) steel in support of the design and operation of G91 components in sodium-cooled fast reactors (SFRs). The report is a Level 3 deliverable in FY17 (M3AT-17AN1602018), under the Work Package AT-17AN160201, “SFR Materials Testing” performed by the Argonne National Laboratory (ANL), as part of the Advanced Reactor Technologies Program.

  20. PCI compliance understand and implement effective PCI data security standard compliance

    CERN Document Server

    Williams, Branden R

    2012-01-01

    The credit card industry established the PCI Data Security Standards to provide a minimum standard for how vendors should protect data to ensure it is not stolen by fraudsters. PCI Compliance, 3e, provides the information readers need to understand the current PCI Data Security standards, which have recently been updated to version 2.0, and how to effectively implement security within your company to be compliant with the credit card industry guidelines and protect sensitive and personally identifiable information. Security breaches continue to occur on a regular basis, affecting millions of

  1. Applying a Computational Fluid Dynamics model to understand flow structures in a large river: the Rio Paraná

    Science.gov (United States)

    Sandbach, S. D.; Hardy, R. J.; Lane, S. N.; Ashworth, P. J.; Parsons, D. R.

    2010-12-01

    Our understanding of large rivers is limited due to the difficulties in obtaining field data at these large scales. Data rich results may be obtained using computational fluid dynamic (CFD) models permitting the investigation of detailed flow patterns that would otherwise not be available. However, the application of these models to large rivers is not without its own complications and has yet to be fully developed. This is the result of two limiting factors, our inability; i) to design numerically stable meshes for complex topographies at these spatial resolutions; and; ii) to collect high resolution data appropriate for the boundary conditions of the numerical scheme. Here, we demonstrate a five-term mass-flux scaling algorithm (MFSA) for including bed topography in a very large river, where the discretised form of the mass and momentum equations are modified using a numerical blockage. Converged solutions were obtained using the Reynolds-averaged Navier stokes (RANS) equations modelling turbulence with a κ-ɛ RNG turbulence model. The boundary conditions were supplied from a field investigation of the Rio Paraná upstream of the Paraguay-Paraná confluence. A 38 km long reach was investigated where topographic and velocity data was collected using an acoustic Doppler current profiler (aDcp) and a single beam echo sounder. The model was validated against the aDcp data and in general showed good agreement. The model was then used to explore the impacts of roughness height upon key characteristics of the 3D flow field in large rivers. The results demonstrate the importance of topographic forcing on determining flow structures including the detection of large helical flow structures.

  2. Extension, sedimentation and diapirism: understanding evolution of diapiric structures in the Central High Atlas using analogue modelling

    Science.gov (United States)

    Moragas, Mar; Vergés, Jaume; Nalpas, Thierry; Saura, Eduard; Diego Martín-Martín, Juan; Messager, Grégoire; Hunt, David William

    2017-04-01

    Analogue modelling has proven to be an essential tool for the study and analysis of the mechanisms involved in tectonic processes. Applied to salt tectonics, analogue modelling has been used to understand the mechanisms that trigger the onset of diapirs and the evolution of diapiric structures and minibasins. Analogue modelling has also been applied to analyse the impact of the progradation of sedimentary systems above a ductile layer, representing the source of diapirs. However, these models did not consider ongoing tectonic processes during progradation. To analyse how extension and sedimentary progradation influence on the formation of diapiric structures and their geometries, we present models composed of a mildly extension followed by post-extension period. Each model includes a particular sedimentary pattern: homogeneous sedimentation during extension and post-extension, homogeneous sedimentation during extension followed by prograding sedimentation during post-extension and prograding sedimentation during both extension and post-extension. Proximal high sedimentation rates enhance the mobilization of ductile material towards growing diapirs, resulting well-developed passive diapirs. Diapirs from distal domain of the model with post-extension progradation show silicone extrusions, that are caused by the decreased sedimentation rate associated to the progradation. By contrast, reduced sedimentation in the distal part of the model with syn- and post-extension progradation (3.5 times smaller than in the proximal domain) causes a limited migration of the silicone and hampers the transition from reactive diapirs to active and passive diapirs. These models show that the ratio between diapir growth and sedimentation rate, the time of the onset of the progradation and the relative thickness of the sedimentary cover beneath the prograding system have a clear impact on the final diapiric geometries. Additionally, we present two models with increasing amounts of

  3. The Effect of Simulated Interaural Frequency Mismatch on Speech Understanding and Spatial Release From Masking.

    Science.gov (United States)

    Goupell, Matthew J; Stoelb, Corey A; Kan, Alan; Litovsky, Ruth Y

    2018-01-15

    The binaural-hearing system interaurally compares inputs, which underlies the ability to localize sound sources and to better understand speech in complex acoustic environments. Cochlear implants (CIs) are provided in both ears to increase binaural-hearing benefits; however, bilateral CI users continue to struggle with understanding speech in the presence of interfering sounds and do not achieve the same level of spatial release from masking (SRM) as normal-hearing listeners. One reason for diminished SRM in CI users could be that the electrode arrays are inserted at different depths in each ear, which would cause an interaural frequency mismatch. Because interaural frequency mismatch diminishes the salience of interaural differences for relatively simple stimuli, it may also diminish binaural benefits for spectral-temporally complex stimuli like speech. This study evaluated the effect of simulated frequency-to-place mismatch on speech understanding and SRM. Eleven normal-hearing listeners were tested on a speech understanding task. There was a female target talker who spoke five-word sentences from a closed set of words. There were two interfering male talkers who spoke unrelated sentences. Nonindividualized head-related transfer functions were used to simulate a virtual auditory space. The target was presented from the front (0°), and the interfering speech was either presented from the front (colocated) or from 90° to the right (spatially separated). Stimuli were then processed by an eight-channel vocoder with tonal carriers to simulate aspects of listening through a CI. Frequency-to-place mismatch ("shift") was introduced by increasing the center frequency of the synthesis filters compared with the corresponding analysis filters. Speech understanding was measured for different shifts (0, 3, 4.5, and 6 mm) and target-to-masker ratios (TMRs: +10 to -10 dB). SRM was calculated as the difference in the percentage of correct words for the colocated and separated

  4. Ferenczi's concept of identification with the aggressor: understanding dissociative structure with interacting victim and abuser self-states.

    Science.gov (United States)

    Howell, Elizabeth F

    2014-03-01

    No one has described more passionately than Ferenczi the traumatic induction of dissociative trance with its resulting fragmentation of the personality. Ferenczi introduced the concept and term, identification with the aggressor in his seminal "Confusion of Tongues" paper, in which he described how the abused child becomes transfixed and robbed of his senses. Having been traumatically overwhelmed, the child becomes hypnotically transfixed by the aggressor's wishes and behavior, automatically identifying by mimicry rather than by a purposeful identification with the aggressor's role. To expand upon Ferenczi's observations, identification with the aggressor can be understood as a two-stage process. The first stage is automatic and initiated by trauma, but the second stage is defensive and purposeful. While identification with the aggressor begins as an automatic organismic process, with repeated activation and use, gradually it becomes a defensive process. Broadly, as a dissociative defense, it has two enacted relational parts, the part of the victim and the part of the aggressor. This paper describes the intrapersonal aspects (how aggressor and victim self-states interrelate in the internal world), as well as the interpersonal aspects (how these become enacted in the external). This formulation has relevance to understanding the broad spectrum of the dissociative structure of mind, borderline personality disorder, and dissociative identity disorder.

  5. Understanding the structured processes followed by organisations prior to engaging in agile processes: A South African Perspective

    Directory of Open Access Journals (Sweden)

    Nimrod Noruwana

    2012-06-01

    Full Text Available There appears to be a lack of knowledge on the phases South African (SA organisations go through while adopting agile methods. As a means to address this gap, this study uncovered empirical evidence on the phases SA organisations go through whilst adopting agile methods as well as the disparities between agile prescriptions and the way SA organisations actually implement agile methods. The data collected using a case study approach was analysed through the lens of Actor-Network Theory (ANT. The results reveal that there is no structured process for adopting agile methods and organisations go through various phases in their attempts to adopt agile methods. During the various phases, organisations face challenges which are culture as well as people related. Through this study South African practitioners could now be aware that before adopting an agile methodology, there has to be a common understanding of the problems at hand and the envisioned solution. The findings also inform aspiring adopters in South Africa that adoption of the methods does not have to be as prescribed. They are free to adopt only those aspects the organisations need most.

  6. A Better Understanding of Protein Structure and Function by the Synthesis and Incorporation of Selenium- and Tellurium Containing Tryptophan Analogs

    Energy Technology Data Exchange (ETDEWEB)

    Helmey, Sherif Samir [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Bioscience Division; Belmont Univ., Nashville, TN (United States). Dept. of Chemistry and Physics; Rice, Ambrose Eugene [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Bioscience Division; Belmont Univ., Nashville, TN (United States). Dept. of Chemistry and Physics; Hatch, Duane Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Bioscience Division; Belmont Univ., Nashville, TN (United States). Dept. of Chemistry and Physics; Silks, Louis A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Bioscience Division; Marti-Arbona, Ricardo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Bioscience Division

    2016-08-17

    Unnatural heavy metal-containing amino acid analogs have shown to be very important in the analysis of protein structure, using methods such as X-ray crystallography, mass spectroscopy, and NMR spectroscopy. Synthesis and incorporation of selenium-containing methionine analogs has already been shown in the literature however with some drawbacks due to toxicity to host organisms. Thus synthesis of heavy metal tryptophan analogs should prove to be more effective since the amino acid tryptophan is naturally less abundant in many proteins. For example, bioincorporation of β-seleno[3,2-b]pyrrolyl-L-alanine ([4,5]SeTrp) and β-selenolo[2,3-b]pyrrolyl-L-alanine ([6,7]SeTrp) has been shown in the following proteins without structural or catalytic perturbations: human annexin V, barstar, and dihydrofolate reductase. The reported synthesis of these Se-containing analogs is currently not efficient for commercial purposes. Thus a more efficient, concise, high-yield synthesis of selenotryptophan, as well as the corresponding, tellurotryptophan, will be necessary for wide spread use of these unnatural amino acid analogs. This research will highlight our progress towards a synthetic route of both [6,7]SeTrp and [6,7]TeTrp, which ultimately will be used to study the effect on the catalytic activity of Lignin Peroxidase (LiP).

  7. Fundamental understanding of oxygen reduction and reaction behavior and developing high performance and stable hetero-structured cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xingbo [West Virginia Univ., Morgantown, WV (United States)

    2016-11-14

    New unique hetero-structured cathode has been developed in this project. La2NiO4+δ (LNO) as a surface catalyst with interstitial oxygen defects was introduced onto the state-of-the-art (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ (LSCF) cathode to enhance the surface-limited ORR kinetics on SOFC cathode. Furthermore, the hetero-structured cathode surface maintains high activity under electrode polarization with much less negative effects from surface cation segregation of Sr, which is known to cause degradation issues for conventional LSCF and LSC cathodes, thus improving the cathode long-term stability. The interface chemistry distribution and oxygen transport properties have been studied to prove the enhancement of power out and stability of LNO-infiltrated LSCF cathode. The further investigation demonstrates that CeO2 & La2-xNiO4+δ (x=0-0.2) co-infiltration is a simple and cost-effective method to improve both performance and stability of LSCF cathode by limiting nano-particles growth/delamination and further improve the surface stability. For the first time, a physical model is proposed to illustrate how unique interstitial species on hetero-structured cathode surface work to regulate the exchange rate of the incorporation reaction. Meanwhile, fundamental investigation of the surface oxygen exchange and bulk oxygen transport properties under over-potential conditions across cathode materials have been carried out in this project, which were discussed and compared to the Nernst equation that is generally applied to treat any oxide electrodes under equilibrium.

  8. Photoelectric effect in surface-barrier structures

    International Nuclear Information System (INIS)

    Kononenko, V.K.; Tupenevich, P.A.

    1985-08-01

    Deviations from the Fowler law were observed when investigating photoelectric emission in p-type ZnTe surface-barrier structures. The revealed peculiarities of the structure photosensitivity spectrum are explained by the electron transitions involving surface states at the metal-semiconductor interface. (author)

  9. Heterogeneous nucleation of hydroxyapatite on protein: structural effect of silk sericin

    Science.gov (United States)

    Takeuchi, Akari; Ohtsuki, Chikara; Miyazaki, Toshiki; Kamitakahara, Masanobu; Ogata, Shin-ichi; Yamazaki, Masao; Furutani, Yoshiaki; Kinoshita, Hisao; Tanihara, Masao

    2005-01-01

    Acidic proteins play an important role during mineral formation in biological systems, but the mechanism of mineral formation is far from understood. In this paper, we report on the relationship between the structure of a protein and hydroxyapatite deposition under biomimetic conditions. Sericin, a type of silk protein, was adopted as a suitable protein for studying structural effect on hydroxyapatite deposition, since it forms a hydroxyapatite layer on its surface in a metastable calcium phosphate solution, and its structure has been reported. Sericin effectively induced hydroxyapatite nucleation when it has high molecular weight and a β sheet structure. This indicates that the specific structure of a protein can effectively induce heterogeneous nucleation of hydroxyapatite in a biomimetic solution, i.e. a metastable calcium phosphate solution. This finding is useful in understanding biomineralization, as well as for the design of organic polymers that can effectively induce hydroxyapatite nucleation. PMID:16849195

  10. Understanding the Electronic Structures and Absorption Properties of Porphyrin Sensitizers YD2 and YD2-o-C8 for Dye-Sensitized Solar Cells

    Science.gov (United States)

    Han, Li-Heng; Zhang, Cai-Rong; Zhe, Jian-Wu; Jin, Neng-Zhi; Shen, Yu-Lin; Wang, Wei; Gong, Ji-Jun; Chen, Yu-Hong; Liu, Zi-Jiang

    2013-01-01

    The electronic structures and excitation properties of dye sensitizers determine the photon-to-current conversion efficiency of dye sensitized solar cells (DSSCs). In order to understand the different performance of porphyrin dye sensitizers YD2 and YD2-o-C8 in DSSC, their geometries and electronic structures have been studied using density functional theory (DFT), and the electronic absorption properties have been investigated via time-dependent DFT (TDDFT) with polarizable continuum model for solvent effects. The geometrical parameters indicate that YD2 and YD2-o-C8 have similar conjugate length and charge transfer (CT) distance. According to the experimental spectra, the HSE06 functional in TDDFT is the most suitable functional for describing the Q and B absorption bands of porphyrins. The transition configurations and molecular orbital analysis suggest that the diarylamino groups are major chromophores for effective CT excitations (ECTE), and therefore act as electron donor in photon-induced electron injection in DSSCs. The analysis of excited states properties and the free energy changes for electron injection support that the better performance of YD2-o-C8 in DSSCs result from the more excited states with ECTE character and the larger absolute value of free energy change for electron injection. PMID:24152435

  11. Understanding the Electronic Structures and Absorption Properties of Porphyrin Sensitizers YD2 and YD2-o-C8 for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Zi-Jiang Liu

    2013-10-01

    Full Text Available The electronic structures and excitation properties of dye sensitizers determine the photon-to-current conversion efficiency of dye sensitized solar cells (DSSCs. In order to understand the different performance of porphyrin dye sensitizers YD2 and YD2-o-C8 in DSSC, their geometries and electronic structures have been studied using density functional theory (DFT, and the electronic absorption properties have been investigated via time-dependent DFT (TDDFT with polarizable continuum model for solvent effects. The geometrical parameters indicate that YD2 and YD2-o-C8 have similar conjugate length and charge transfer (CT distance. According to the experimental spectra, the HSE06 functional in TDDFT is the most suitable functional for describing the Q and B absorption bands of porphyrins. The transition configurations and molecular orbital analysis suggest that the diarylamino groups are major chromophores for effective CT excitations (ECTE, and therefore act as electron donor in photon-induced electron injection in DSSCs. The analysis of excited states properties and the free energy changes for electron injection support that the better performance of YD2-o-C8 in DSSCs result from the more excited states with ECTE character and the larger absolute value of free energy change for electron injection.

  12. Effects of Understanding the Problem Statement on Students' Mathematical Performance of Senior Secondary Schools in Borno State, Nigeria

    Science.gov (United States)

    Banus, Abdullahi Audu; Dauda, Bala

    2015-01-01

    The study assessed the relative effectiveness of understanding the problem statement on students' mathematical behaviours in Borno State Secondary Schools. The study was guided by an objective: to determine the Understanding the problem statement on student's performance in senior secondary school and a null hypothesis: there was no effect of…

  13. Improving Students' Conceptual Understanding of the Greenhouse Effect Using Theory-Based Learning Materials that Promote Deep Learning

    Science.gov (United States)

    Reinfried, Sibylle; Aeschbacher, Urs; Rottermann, Benno

    2012-01-01

    Students' everyday ideas of the greenhouse effect are difficult to change. Environmental education faces the challenge of developing instructional settings that foster students' conceptual understanding concept of the greenhouse effect in order to understand global warming. To facilitate students' conceptual development with regard to the…

  14. Children's experiences of food insecurity can assist in understanding its effect on their well-being.

    Science.gov (United States)

    Connell, Carol L; Lofton, Kristi L; Yadrick, Kathy; Rehner, Timothy A

    2005-07-01

    An understanding of the experience of food insecurity by children is essential for better measurement and assessment of its effect on children's nutritional, physical, and mental health. Our qualitative study explored children's perceptions of household food insecurity to identify these perceptions and to use them to establish components of children's food insecurity experience. Children (n = 32; 11-16 y old) from after school programs and a middle school in low-income areas participated in individual semistructured in-depth interviews. Children as young as 11 y could describe behaviors associated with food insecurity if they had experienced it directly or indirectly. Using the constant comparative method of qualitative data analysis, children's descriptions of behaviors associated with food insecurity were categorized into components of quantity of food, quality of food, psychological aspects, and social aspects described in the household food insecurity literature. Aspects of quantity included eating less than usual and eating more or eating fast when food was available. Aspects of quality included use of a few kinds of low-cost foods. Psychological aspects included worry/anxiety/sadness about the family food supply, feelings of having no choice in the foods eaten, shame/fear of being labeled as poor, and attempts to shield children. Social aspects of food insecurity centered on using social networks to acquire food or money and social exclusion. These results provide valuable information in understanding the effect of food insecurity on children's well-being especially relative to the social and emotional aspects of well-being.

  15. Understanding reliance on automation: effects of error type, error distribution, age and experience

    Science.gov (United States)

    Sanchez, Julian; Rogers, Wendy A.; Fisk, Arthur D.; Rovira, Ericka

    2015-01-01

    An obstacle detection task supported by “imperfect” automation was used with the goal of understanding the effects of automation error types and age on automation reliance. Sixty younger and sixty older adults interacted with a multi-task simulation of an agricultural vehicle (i.e. a virtual harvesting combine). The simulator included an obstacle detection task and a fully manual tracking task. A micro-level analysis provided insight into the way reliance patterns change over time. The results indicated that there are distinct patterns of reliance that develop as a function of error type. A prevalence of automation false alarms led participants to under-rely on the automation during alarm states while over relying on it during non-alarms states. Conversely, a prevalence of automation misses led participants to over-rely on automated alarms and under-rely on the automation during non-alarm states. Older adults adjusted their behavior according to the characteristics of the automation similarly to younger adults, although it took them longer to do so. The results of this study suggest the relationship between automation reliability and reliance depends on the prevalence of specific errors and on the state of the system. Understanding the effects of automation detection criterion settings on human-automation interaction can help designers of automated systems make predictions about human behavior and system performance as a function of the characteristics of the automation. PMID:25642142

  16. Toward understanding the thermodynamics of TALSPEAK process. Medium effects on actinide complexation

    Energy Technology Data Exchange (ETDEWEB)

    Peter R Zalupski; Leigh R Martin; Ken Nash; Yoshinobu Nakamura; Masahiko Yamamoto

    2009-07-01

    The ingenious combination of lactate and diethylenetriamine-N,N,N’,N”,N”-pentaacetic acid (DTPA) as an aqueous actinide-complexing medium forms the basis of the successful separation of americium and curium from lanthanides known as the TALSPEAK process. While numerous reports in the prior literature have focused on the optimization of this solvent extraction system, considerably less attention has been devoted to the understanding of the basic thermodynamic features of the complex fluids responsible for the separation. The available thermochemical information of both lactate and DTPA protonation and metal complexation reactions are representative of the behavior of these ions under idealized conditions. Our previous studies of medium effects on lactate protonation suggest that significant departures from the speciation predicted based on reported thermodynamic values should be expected in the TALSPEAK aqueous environment. Thermodynamic parameters describing the separation chemistry of this process thus require further examination at conditions significantly removed from conventional ideal systems commonly employed in fundamental solution chemistry. Such thermodynamic characterization is the key to predictive modelling of TALSPEAK. Improved understanding will, in principle, allow process technologists to more efficiently respond to off-normal conditions during large scale process operation. In this report, the results of calorimetric and potentiometric investigations of the effects of aqueous electrolytes on the thermodynamic parameters for lactate protonation and lactate complexation of americium and neodymium will be presented. Studies on the lactate protonation equilibrium will clearly illustrate distinct thermodynamic variations between strong electrolyte aqueous systems and buffered lactate environment.

  17. The Effects of Conceptual Understanding Procedures (CUPs) Towards Critical Thinking Skills of Senior High School Students

    Science.gov (United States)

    Sukaesih, S.; Sutrisno

    2017-04-01

    The aim of the study was to analyse the effect of the application of Conceptual Understanding Procedures (CUPs) learning to the students’ critical thinking skills in the matter of categorisaed in SMA Negeri 1 Larangan. This study was quasi-experimental design using nonequivalent control group design. The population in this study was entire class X. The samples that were taken by convenience sampling were class X MIA 1 and X MIA 2. Primary data in the study was the student’s critical thinking skills, which was supported by student activity, the level of adherence to the CUPs learning model, student opinion and teacher opinion. N-gain test results showed that the students’ critical thinking skills of experimental class increased by 89.32%, while the control group increased by 57.14%. Activity grade of experimental class with an average value of 72.37 was better than that of the control class with an average of only 22.69 student and teacher opinions to the learning were excellegoodnt. Based on this study concluded that the model of Conceptual Understanding Procedures (CUPs) had an effect on the student’s critical thinking skills in the matter of protest in SMA Negeri 1 Larangan.

  18. Understanding the Doppler effect by analysing spectrograms of the sound of a passing vehicle

    Science.gov (United States)

    Lubyako, Dmitry; Martinez-Piedra, Gordon; Ushenin, Arthur; Denvir, Patrick; Dunlop, John; Hall, Alex; Le Roux, Gus; van Someren, Laurence; Weinberger, Harvey

    2017-11-01

    The purpose of this paper is to demonstrate how the Doppler effect can be analysed to deduce information about a moving source of sound waves. Specifically, we find the speed of a car and the distance of its closest approach to an observer using sound recordings from smartphones. A key focus of this paper is how this can be achieved in a classroom, both theoretically and experimentally, to deepen students’ understanding of the Doppler effect. Included are our own experimental data (48 sound recordings) to allow others to reproduce the analysis, if they cannot repeat the whole experiment themselves. In addition to its educational purpose, this paper examines the percentage errors in our results. This enabled us to determine sources of error, allowing those conducting similar future investigations to optimize their accuracy.

  19. Understanding of latent tuberculosis, its treatment and treatment side effects in immigrant and refugee patients.

    Science.gov (United States)

    Butcher, Katie; Biggs, Beverley-Ann; Leder, Karin; Lemoh, Chris; O'Brien, Daniel; Marshall, Caroline

    2013-08-29

    Isoniazid treatment of latent tuberculosis infection (LTBI) is commonly prescribed in refugees and immigrants. We aimed to assess understanding of information provided about LTBI, its treatment and potential side effects. A questionnaire was administered in clinics at a tertiary hospital. Total Knowledge (TKS) and Total Side Effect Scores (TSES) were derived. Logistic regression analyses were employed to correlate socio-demographic factors with knowledge. Fifty-two participants were recruited, 20 at isoniazid commencement and 32 already on isoniazid. The average TKS were 5.04/9 and 6.23/9 respectively and were significantly associated with interpreter use. Approximately half did not know how tuberculosis was transmitted. The average TSES were 5.0/7 and 3.5/7 respectively, but were not influenced by socio-demographic factors. There was suboptimal knowledge about LTBI. Improvements in health messages delivered via interpreters and additional methods of distributing information need to be developed for this patient population.

  20. Understanding Romanowsky staining. I: The Romanowsky-Giemsa effect in blood smears.

    Science.gov (United States)

    Horobin, R W; Walter, K J

    1987-01-01

    Normal blood smears were stained by the standardised azure B-eosin Y Romanowsky procedure recently introduced by the ICSH, and the classical picture resulted. The effects of varying the times and temperature of staining, the composition of the solvent (buffer concentration, methanol content, & pH), the concentration of the dyes, and the mode of fixation were studied. The results are best understood in terms of the following staining mechanism. Initial colouration involves simple acid and basic dyeing. Eosin yields red erythrocytes and eosinophil granules. Azure B very rapidly gives rise to blue stained chromatin, neutrophil specific granules, platelets and ribosome-rich cytoplasms; also to violet basophil granules. Subsequently the azure B in certain structures combines with eosin to give purple azure B-eosin complexes, leaving other structures with their initial colours. The selectivity of complex formation is controlled by rate of entry of eosin into azure B stained structures. Only faster staining structures (i.e. chromatin, neutrophil specific granules, and platelets) permit formation of the purple complex in the standard method. This staining mechanism illuminates scientific problems (e.g. the nature of 'toxic' granules) and assists technical trouble-shooting (e.g. why nuclei sometimes stain blue, not purple).

  1. Modeling Cable-Harness Effects on Spacecraft Structures

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed research involves modeling the effects of cable-harnesses and wiring on the dynamics of spacecraft structures. As space structure mass decreases due to...

  2. Integrative relational machine-learning for understanding drug side-effect profiles.

    Science.gov (United States)

    Bresso, Emmanuel; Grisoni, Renaud; Marchetti, Gino; Karaboga, Arnaud Sinan; Souchet, Michel; Devignes, Marie-Dominique; Smaïl-Tabbone, Malika

    2013-06-26

    Drug side effects represent a common reason for stopping drug development during clinical trials. Improving our ability to understand drug side effects is necessary to reduce attrition rates during drug development as well as the risk of discovering novel side effects in available drugs. Today, most investigations deal with isolated side effects and overlook possible redundancy and their frequent co-occurrence. In this work, drug annotations are collected from SIDER and DrugBank databases. Terms describing individual side effects reported in SIDER are clustered with a semantic similarity measure into term clusters (TCs). Maximal frequent itemsets are extracted from the resulting drug x TC binary table, leading to the identification of what we call side-effect profiles (SEPs). A SEP is defined as the longest combination of TCs which are shared by a significant number of drugs. Frequent SEPs are explored on the basis of integrated drug and target descriptors using two machine learning methods: decision-trees and inductive-logic programming. Although both methods yield explicit models, inductive-logic programming method performs relational learning and is able to exploit not only drug properties but also background knowledge. Learning efficiency is evaluated by cross-validation and direct testing with new molecules. Comparison of the two machine-learning methods shows that the inductive-logic-programming method displays a greater sensitivity than decision trees and successfully exploit background knowledge such as functional annotations and pathways of drug targets, thereby producing rich and expressive rules. All models and theories are available on a dedicated web site. Side effect profiles covering significant number of drugs have been extracted from a drug ×side-effect association table. Integration of background knowledge concerning both chemical and biological spaces has been combined with a relational learning method for discovering rules which explicitly

  3. Multiple stressor effects in Chlamydomonas reinhardtii--toward understanding mechanisms of interaction between effects of ultraviolet radiation and chemical pollutants.

    Science.gov (United States)

    Korkaric, Muris; Behra, Renata; Fischer, Beat B; Junghans, Marion; Eggen, Rik I L

    2015-05-01

    The effects of chemical pollutants and environmental stressors, such as ultraviolet radiation (UVR), can interact when organisms are simultaneously exposed, resulting in higher (synergistic) or lower (antagonistic) multiple stressor effects than expected based on the effects of single stressors. Current understanding of interactive effects is limited due to a lack of mechanism-based multiple stressor studies. It has been hypothesized that effect interactions may generally occur if chemical and non-chemical stressors cause similar physiological effects in the organism. To test this hypothesis, we exposed the model green alga Chlamydomonas reinhardtii to combinations of UVR and single chemicals displaying modes of action (MOA) similar or dissimilar to the impact of UVR on photosynthesis. Stressor interactions were analyzed based on the independent action model. Effect interactions were found to depend on the MOA of the chemicals, and also on their concentrations, the exposure time and the measured endpoint. Indeed, only chemicals assumed to cause effects on photosynthesis similar to UVR showed interactions with UVR on photosynthetic yield: synergistic in case of Cd(II) and paraquat and antagonistic in case of diuron. No interaction on photosynthesis was observed for S-metolachlor, which acts dissimilarly to UVR. However, combined effects of S-metolachlor and UVR on algal reproduction were synergistic, highlighting the importance of considering additional MOA of UVR. Possible mechanisms of stressor effect interactions are discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Understanding the determinants of the complex interplay between cost-effectiveness and equitable impact in maternal and child mortality reduction.

    Science.gov (United States)

    Chopra, Mickey; Campbell, Harry; Rudan, Igor

    2012-06-01

    One of the most unexpected outcomes arising from the efforts towards maternal and child mortality reduction is that all too often the objective success has been coupled with increased inequity in the population. The aim of this study is to analyze the determinants of the complex interplay between cost-effectiveness and equity and suggest strategies that will promote an impact on mortality that reduce population child health inequities. We developed a conceptual framework that exposes the nature of the links between the five key determinants that need to be taken into account when planning equitable impact. These determinants are: (i) efficiency of intervention scale-up (requires knowledge of differential increase in cost of intervention scale-up by equity strata in the population); (ii) effectiveness of intervention (requires understanding of differential effectiveness of interventions by equity strata in the population); (iii) the impact on mortality (requires knowledge of differential mortality levels by equity strata, and understanding the differences in cause composition of overall mortality in different equity strata); (iv) cost-effectiveness (compares the initial cost and the resulting impact on mortality); (v) equity structure of the population. The framework is presented visually as a four-quadrant graph. We use the proposed framework to demonstrate why the relationship between cost-effectiveness and equitable impact of an intervention cannot be intuitively predicted or easily planned. The relationships between the five determinants are complex, often nonlinear, context-specific and intervention-specific. We demonstrate that there will be instances when an equity-promoting approach, ie, trying to reach for the poorest and excluded in the population with health interventions, will also be the most cost-effective approach. However, there will be cases in which this will be entirely unfeasible, and where equity-neutral or even inequity-promoting approaches may

  5. Restraint Effects in Early Age Concrete Structures

    OpenAIRE

    Al-Gburi, Majid

    2015-01-01

    One of the widespread issues in concrete structures is cracks occurring at early age. Cracks that appear in the young concrete may cause early start of corrosion of rebars or early penetration of harmful liquids or gases into the concrete body. These situations could result in reduced service life and in significantly increased maintenance cost of structures. Therefore it is important for construction companies to avoid these cracks.Volumetric deformations in early age concrete are caused by ...

  6. Metabolic Effects of Berries with Structurally Diverse Anthocyanins

    Directory of Open Access Journals (Sweden)

    John Overall

    2017-02-01

    Full Text Available Overconsumption of energy dense foods and sedentary lifestyle are considered as major causes of obesity-associated insulin resistance and abnormal glucose metabolism. Results from both cohort studies and randomized trials suggested that anthocyanins from berries may lower metabolic risks, however these reports are equivocal. The present study was designed to examine effects of six berries with structurally diverse anthocyanin profiles (normalized to 400 µg/g total anthocyanin content on development of metabolic risk factors in the C57BL/6 mouse model of polygenic obesity. Diets supplemented with blackberry (mono-glycosylated cyanidins, black raspberry (acylated mono-glycosylated cyanidins, blackcurrant (mono- and di-glycosylated cyanidins and delphinidins, maqui berry (di-glycosylated delphinidins, Concord grape (acylated mono-glycosylated delphinidins and petunidins, and blueberry (mono-glycosylated delphinidins, malvidins, and petunidins showed a prominent discrepancy between biological activities of delphinidin/malvidin-versus cyanidin-type anthocyanins that could be explained by differences in their structure and metabolism in the gut. Consumption of berries also resulted in a strong shift in the gastrointestinal bacterial communities towards obligate anaerobes that correlated with decrease in the gastrointestinal luminal oxygen and oxidative stress. Further work is needed to understand mechanisms that lead to nearly anoxic conditions in the gut lumens, including the relative contributions of host, diet and/or microbial oxidative activity, and their implication to human health.

  7. Recent progress to understand stress corrosion cracking in sodium borosilicate glasses: linking the chemical composition to structural, physical and fracture properties

    Science.gov (United States)

    Rountree, Cindy L.

    2017-08-01

    This topical review is dedicated to understanding stress corrosion cracking in oxide glasses and specifically the SiO_2{\\text-B_2O_3{\\text-}Na_2O} (SBN) ternary glass systems. Many review papers already exist on the topic of stress corrosion cracking in complex oxide glasses or overly simplified glasses (pure silica). These papers look at how systematically controlling environmental factors (pH, temperature...) alter stress corrosion cracking, while maintaining the same type of glass sample. Many questions still exist, including: What sets the environmental limit? What sets the velocity versus stress intensity factor in the slow stress corrosion regime (Region I)? Can researchers optimize these two effects to enhance a glass’ resistance to failure? To help answer these questions, this review takes a different approach. It looks at how systemically controlling the glass’ chemical composition alters the structure and physical properties. These changes are then compared and contrasted to the fracture toughness and the stress corrosion cracking properties. By taking this holistic approach, researchers can begin to understand the controlling factors in stress corrosion cracking and how to optimize glasses via the initial chemical composition.

  8. Reading in the Australian Curriculum English: Describing the Effects of Structure and Organisation on Multimodal Texts

    Science.gov (United States)

    Exley, Beryl; Cottrell, Amber

    2012-01-01

    The recently introduced "Australian Curriculum: English" (Australian Curriculum, Assessment and Reporting Authority (ACARA), 2012) requires students to "read" multimodal text and describe the effects of structure and organisation. We begin this article by tracing the variable understandings of what reading multimodal text might…

  9. Hydrologic Synthesis Across the Critical Zone Observatory Network: A Step Towards Understanding the Coevolution of Critical Zone Function and Structure

    Science.gov (United States)

    Wlostowski, A. N.; Harman, C. J.; Molotch, N. P.

    2017-12-01

    generation). Storage-discharge relationships vary widely across the Network, and may be associated with inter-site differences in sub-surface architecture. Moving forward, we seek to reconcile top-down analysis results against the bottom-up understanding of critical zone structure and hydrologic function at each CZO site.

  10. Effects of migration on family structure.

    Science.gov (United States)

    Pekin, H

    1989-06-01

    This paper examines the situation and problems of migration on family structure, with emphasis on family reunification. The study is based on conditions and practices in Western Europe and Mediterranean countries relating to temporary labor migration. Most migrant workers have no intention of settling permanently and return to their country within a few years. The International Labour Office estimated in 1974 that at least 1/2 the migrant workers in Western Europe live without their families. Generally, migrants send for their families only when they are employed, earning adequate wages, and have adequate housing. Some reasons why migrants live apart from their families include 1) the receiving country discourages family immigration because it does not coincide with the economic necessities of migration policy and 2) some sending countries discourage it to ensure that the migrant worker returns to his own country. The main danger arising from family separation is that it frequently leads to the break up of the family. The leading European authorities recognize as a fundamental right the freedom of a migrant worker and his family to lead a normal family life in the receiving country. The author outlines the conditions for admission for residence and employment of migrant spouses and children for the Federal Republic of Germany, France, Belgium, Switzerland, the Netherlands, Sweden, Norway, Austria, Luxembourg, and the United Kingdom. All countries require that the head be in regular employment for some time and be able to provide his family with suitable housing. Other problems concerning the arrival of migrant spouses and children include 1) acquiring employment and social information and counseling, 2) education of children, 3) obtaining vocational training and adaptation and 4) achieving entitlement to social security benefits. The effects of migration in the family context in sending countries include 1) providing activities for migrants to maintain cultural

  11. Understanding the toxic potencies of xenobiotics inducing TCDD/TCDF-like effects.

    Science.gov (United States)

    Şahin, A D; Saçan, M T

    2018-02-01

    Toxic potencies of xenobiotics such as halogenated aromatic hydrocarbons inducing 2,3,7,8-tetrachlorodibenzo-p-dioxin/2,3,7,8-tetrachlorodibenzofuran (TCDD/TCDF)-like effects were investigated by quantitative structure-toxicity relationships (QSTR) using their aryl hydrocarbon receptor (AhR) binding affinity data. A descriptor pool was created using the SPARTAN 10, DRAGON 6.0 and ADMET 8.0 software packages, and the descriptors were selected using QSARINS (v.2.2.1) software. The QSTR models generated for AhR binding affinities of chemicals with TCDD/TCDF-like effects were internally and externally validated in line with the Organization of Economic Co-operation and Development (OECD) principles. The TCDD-based model had six descriptors from DRAGON 6.0 and ADMET 8.0, whereas the TCDF-based model had seven descriptors from DRAGON 6.0. The predictive ability of the generated models was tested on a diverse group of chemicals including polychlorinated/brominated biphenyls, dioxins/furans, ethers, polyaromatic hydrocarbons with fused heterocyclic rings (i.e. phenoxathiins, thianthrenes and dibenzothiophenes) and polyaromatic hydrocarbons (i.e. halogenated naphthalenes and phenanthrenes) with no AhR binding data. For the external set chemicals, the structural coverage of the generated models was 90% and 89% for TCDD and TCDF-like effects, respectively.

  12. Understanding treatment effect mechanisms of the CAMBRA randomized trial in reducing caries increment.

    Science.gov (United States)

    Cheng, J; Chaffee, B W; Cheng, N F; Gansky, S A; Featherstone, J D B

    2015-01-01

    The Caries Management By Risk Assessment (CAMBRA) randomized controlled trial showed that an intervention featuring combined antibacterial and fluoride therapy significantly reduced bacterial load and suggested reduced caries increment in adults with 1 to 7 baseline cavitated teeth. While trial results speak to the overall effectiveness of an intervention, insight can be gained from understanding the mechanism by which an intervention acts on putative intermediate variables (mediators) to affect outcomes. This study conducted mediation analyses on 109 participants who completed the trial to understand whether the intervention reduced caries increment through its action on potential mediators (oral bacterial load, fluoride levels, and overall caries risk based on the composite of bacterial challenge and salivary fluoride) between the intervention and dental outcomes. The primary outcome was the increment from baseline in decayed, missing, and filled permanent surfaces (ΔDMFS) 24 mo after completing restorations for baseline cavitated lesions. Analyses adjusted for baseline overall risk, bacterial challenge, and fluoride values under a potential outcome framework using generalized linear models. Overall, the CAMBRA intervention was suggestive in reducing the 24-mo DMFS increment (reduction in ΔDMFS: -0.96; 95% confidence interval [CI]: -2.01 to 0.08; P = 0.07); the intervention significantly reduced the 12-mo overall risk (reduction in overall risk: -19%; 95% CI, -7 to -41%;], P = 0.005). Individual mediators, salivary log10 mutans streptococci, log10 lactobacilli, and fluoride level, did not represent statistically significant pathways alone through which the intervention effect was transmitted. However, 36% of the intervention effect on 24-mo DMFS increment was through a mediation effect on 12-mo overall risk (P = 0.03). These findings suggest a greater intervention effect carried through the combined action on multiple aspects of the caries process rather than

  13. Making meaningful improvements to direct care worker training through informed policy: Understanding how care setting structure and culture matter.

    Science.gov (United States)

    Kemeny, M Elizabeth; Mabry, J Beth

    2017-01-01

    Well-intentioned policy governing the training of direct care workers (DCWs) who serve older persons, in practice, may become merely a compliance issue for organizations rather than a meaningful way to improve quality of care. This study investigates the relationships between best practices in DCW training and the structure and culture of long term support service (LTSS) organizations. Using a mixed-methods approach to analyzing data from 328 licensed LTSS organizations in Pennsylvania, the findings suggest that public policy should address methods of training, not just content, and consider organizational variations in size, training evaluation practices, DCW integration, and DCW input into care planning. Effective training also incorporates support for organizations and supervisors as key aspects of DCWs' learning and working environment.

  14. Multiple stressor effects in Chlamydomonas reinhardtii – Toward understanding mechanisms of interaction between effects of ultraviolet radiation and chemical pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Korkaric, Muris [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, 8600, Duebendorf (Switzerland); ETH Zürich, Institute of Biogeochemistry and Pollutant Dynamics, 8092 Zürich (Switzerland); Behra, Renata; Fischer, Beat B. [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, 8600, Duebendorf (Switzerland); Junghans, Marion [Swiss Center for Applied Ecotoxicology Eawag-EPFL, 8600, Duebendorf (Switzerland); Eggen, Rik I.L., E-mail: rik.eggen@eawag.ch [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, 8600, Duebendorf (Switzerland); ETH Zürich, Institute of Biogeochemistry and Pollutant Dynamics, 8092 Zürich (Switzerland)

    2015-05-15

    Highlights: • Systematic study of multiple stressor effects of UVR and chemicals in C. reinhardtii. • UVR and chemicals did not act independently on algal photosynthesis and reproduction. • Multiple stressor effects of UVR and chemicals depended on chemical MOA. • Synergistic effect interactions not limited to oxidative stress inducing chemicals. • Multiple MOAs of UVR may limit applicability of current prediction models. - Abstract: The effects of chemical pollutants and environmental stressors, such as ultraviolet radiation (UVR), can interact when organisms are simultaneously exposed, resulting in higher (synergistic) or lower (antagonistic) multiple stressor effects than expected based on the effects of single stressors. Current understanding of interactive effects is limited due to a lack of mechanism-based multiple stressor studies. It has been hypothesized that effect interactions may generally occur if chemical and non-chemical stressors cause similar physiological effects in the organism. To test this hypothesis, we exposed the model green alga Chlamydomonas reinhardtii to combinations of UVR and single chemicals displaying modes of action (MOA) similar or dissimilar to the impact of UVR on photosynthesis. Stressor interactions were analyzed based on the independent action model. Effect interactions were found to depend on the MOA of the chemicals, and also on their concentrations, the exposure time and the measured endpoint. Indeed, only chemicals assumed to cause effects on photosynthesis similar to UVR showed interactions with UVR on photosynthetic yield: synergistic in case of Cd(II) and paraquat and antagonistic in case of diuron. No interaction on photosynthesis was observed for S-metolachlor, which acts dissimilarly to UVR. However, combined effects of S-metolachlor and UVR on algal reproduction were synergistic, highlighting the importance of considering additional MOA of UVR. Possible mechanisms of stressor effect interactions are

  15. Multiple stressor effects in Chlamydomonas reinhardtii – Toward understanding mechanisms of interaction between effects of ultraviolet radiation and chemical pollutants

    International Nuclear Information System (INIS)

    Korkaric, Muris; Behra, Renata; Fischer, Beat B.; Junghans, Marion; Eggen, Rik I.L.

    2015-01-01

    Highlights: • Systematic study of multiple stressor effects of UVR and chemicals in C. reinhardtii. • UVR and chemicals did not act independently on algal photosynthesis and reproduction. • Multiple stressor effects of UVR and chemicals depended on chemical MOA. • Synergistic effect interactions not limited to oxidative stress inducing chemicals. • Multiple MOAs of UVR may limit applicability of current prediction models. - Abstract: The effects of chemical pollutants and environmental stressors, such as ultraviolet radiation (UVR), can interact when organisms are simultaneously exposed, resulting in higher (synergistic) or lower (antagonistic) multiple stressor effects than expected based on the effects of single stressors. Current understanding of interactive effects is limited due to a lack of mechanism-based multiple stressor studies. It has been hypothesized that effect interactions may generally occur if chemical and non-chemical stressors cause similar physiological effects in the organism. To test this hypothesis, we exposed the model green alga Chlamydomonas reinhardtii to combinations of UVR and single chemicals displaying modes of action (MOA) similar or dissimilar to the impact of UVR on photosynthesis. Stressor interactions were analyzed based on the independent action model. Effect interactions were found to depend on the MOA of the chemicals, and also on their concentrations, the exposure time and the measured endpoint. Indeed, only chemicals assumed to cause effects on photosynthesis similar to UVR showed interactions with UVR on photosynthetic yield: synergistic in case of Cd(II) and paraquat and antagonistic in case of diuron. No interaction on photosynthesis was observed for S-metolachlor, which acts dissimilarly to UVR. However, combined effects of S-metolachlor and UVR on algal reproduction were synergistic, highlighting the importance of considering additional MOA of UVR. Possible mechanisms of stressor effect interactions are

  16. Understanding the effects of short-term international service-learning trips on medical students.

    Science.gov (United States)

    Abedini, Nauzley C; Gruppen, Larry D; Kolars, Joseph C; Kumagai, Arno K

    2012-06-01

    The purpose of this qualitative study was to understand what meaning(s) preclinical students attributed to participation in one-week international service-learning trips (ISLTs) and what specific experiences during the trips accounted for such perspectives. Twenty-four first-year students who had participated in one-week ISLTs at the University of Michigan Medical School during February 2010 were invited to participate. Individual, semistructured interviews were conducted from March to August 2010 with 13 student participants. Using grounded theory analysis, several major themes were identified. Acquisition of clinical/language skills and knowledge of other health care systems were explicit benefits associated with student ISLT experiences. However, in-depth, reflective discussions revealed implicit insights and lessons, the most pervasive of which were student ambivalence concerning the value and effect of ISLTs on communities, issues of privilege and power, and ethical concerns when working with vulnerable populations. These implicit lessons stimulated new insights into future involvement in global health and emphasized the importance of reflection and discussion to enhance ISLT experiences. The current study suggests that one-week ISLTs may engender implicit insights and lessons regarding ethical and societal issues involved with global health and may stimulate the development of critical reflection on current and future professional roles for student participants. Furthermore, these activities should allow time and space for dialogue and reflection to ensure that this implicit understanding can be put to constructive educational and service-oriented uses.

  17. Role understanding and effective communication as core competencies for collaborative practice.

    Science.gov (United States)

    Suter, Esther; Arndt, Julia; Arthur, Nancy; Parboosingh, John; Taylor, Elizabeth; Deutschlander, Siegrid

    2009-01-01

    The ability to work with professionals from other disciplines to deliver collaborative, patient-centred care is considered a critical element of professional practice requiring a specific set of competencies. However, a generally accepted framework for collaborative competencies is missing, which makes consistent preparation of students and staff challenging. Some authors have argued that there is a lack of conceptual clarity of the "active ingredients" of collaboration relating to quality of care and patient outcomes, which may be at the root of the competencies issue. As part of a large Health Canada funded study focused on interprofessional education and collaborative practice, our goal was to understand the competencies for collaborative practice that are considered most relevant by health professionals working at the front line. Interview participants comprised 60 health care providers from various disciplines. Understanding and appreciating professional roles and responsibilities and communicating effectively emerged as the two perceived core competencies for patient-centred collaborative practice. For both competencies there is evidence of a link to positive patient and provider outcomes. We suggest that these two competencies should be the primary focus of student and staff education aimed at increasing collaborative practice skills.

  18. 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.

  19. A cross-cultural, multilevel study of inquiry-based instruction effects on conceptual understanding and motivation in physics

    Science.gov (United States)

    Negishi, Meiko

    Student achievement and motivation to learn physics is highly valued in many industrialized countries including the United States and Japan. Science education curricula in these countries emphasize the importance and encourage classroom teachers to use an inquiry approach. This dissertation investigated high school students' motivational orientations and their understanding of physics concepts in a context of inquiry-based instruction. The goals were to explore the patterns of instructional effects on motivation and learning in each country and to examine cultural differences and similarities. Participants consisted of 108 students (55 females, 53 males) and 9 physics teachers in the United States and 616 students (203 females and 413 males) and 11 physics teachers in Japan. Students were administered (a) Force Concept Inventory measuring physics conceptual understanding and (b) Attitudes about Science Questionnaire measuring student motivational orientations. Teachers were given a survey regarding their use of inquiry teaching practices and background information. Additionally, three teachers in each country were interviewed and observed in their classrooms. For the data analysis, two-level hierarchical linear modeling (HLM) methods were used to examine individual student differences (i.e., learning, motivation, and gender) within each classroom (i.e., inquiry-based teaching, teaching experience, and class size) in the U.S. and Japan, separately. Descriptive statistical analyses were also conducted. The results indicated that there was a cultural similarity in that current teaching practices had minimal influence on conceptual understanding as well as motivation of high school students between the U.S. and Japan. In contrast, cultural differences were observed in classroom structures and instructional approaches. Furthermore, this study revealed gender inequity in Japanese students' conceptual understanding and self-efficacy. Limitations of the study, as well as

  20. The Lusi seismic experiment: An initial study to understand the effect of seismic activity to Lusi

    Energy Technology Data Exchange (ETDEWEB)

    Karyono, E-mail: karyonosu@gmail.com [Agency for Meteorology, Climatology and Geophysics (BMKG), Jakarta (Indonesia); OSLO University (Norway); Padjadjaran University (UNPAD), Bandung (Indonesia); Mazzini, Adriano; Sugiharto, Anton [OSLO University (Norway); Lupi, Matteo [ETH Zurich (Switzerland); Syafri, Ildrem [Padjadjaran University (UNPAD), Bandung (Indonesia); Masturyono,; Rudiyanto, Ariska; Pranata, Bayu; Muzli,; Widodo, Handi Sulistyo; Sudrajat, Ajat [Agency for Meteorology, Climatology and Geophysics (BMKG), Jakarta (Indonesia)

    2015-04-24

    The spectacular Lumpur Sidoarjo (Lusi) eruption started in northeast Java on the 29 of May 2006 following a M6.3 earthquake striking the island [1,2]. Initially, several gas and mud eruption sites appeared along the reactivated strike-slip Watukosek fault system [3] and within weeks several villages were submerged by boiling mud. The most prominent eruption site was named Lusi. The Lusi seismic experiment is a project aims to begin a detailed study of seismicity around the Lusi area. In this initial phase we deploy 30 seismometers strategically distributed in the area around Lusi and along the Watukosek fault zone that stretches between Lusi and the Arjuno Welirang (AW) complex. The purpose of the initial monitoring is to conduct a preliminary seismic campaign aiming to identify the occurrence and the location of local seismic events in east Java particularly beneath Lusi.This network will locate small event that may not be captured by the existing BMKG network. It will be crucial to design the second phase of the seismic experiment that will consist of a local earthquake tomography of the Lusi-AW region and spatial and temporal variations of vp/vs ratios. The goal of this study is to understand how the seismicity occurring along the Sunda subduction zone affects to the behavior of the Lusi eruption. Our study will also provide a large dataset for a qualitative analysis of earthquake triggering studies, earthquake-volcano and earthquake-earthquake interactions. In this study, we will extract Green’s functions from ambient seismic noise data in order to image the shallow subsurface structure beneath LUSI area. The waveform cross-correlation technique will be apply to all of recordings of ambient seismic noise at 30 seismographic stations around the LUSI area. We use the dispersive behaviour of the retrieved Rayleigh waves to infer velocity structures in the shallow subsurface.

  1. The Lusi seismic experiment: An initial study to understand the effect of seismic activity to Lusi

    International Nuclear Information System (INIS)

    Karyono; Mazzini, Adriano; Sugiharto, Anton; Lupi, Matteo; Syafri, Ildrem; Masturyono,; Rudiyanto, Ariska; Pranata, Bayu; Muzli,; Widodo, Handi Sulistyo; Sudrajat, Ajat

    2015-01-01

    The spectacular Lumpur Sidoarjo (Lusi) eruption started in northeast Java on the 29 of May 2006 following a M6.3 earthquake striking the island [1,2]. Initially, several gas and mud eruption sites appeared along the reactivated strike-slip Watukosek fault system [3] and within weeks several villages were submerged by boiling mud. The most prominent eruption site was named Lusi. The Lusi seismic experiment is a project aims to begin a detailed study of seismicity around the Lusi area. In this initial phase we deploy 30 seismometers strategically distributed in the area around Lusi and along the Watukosek fault zone that stretches between Lusi and the Arjuno Welirang (AW) complex. The purpose of the initial monitoring is to conduct a preliminary seismic campaign aiming to identify the occurrence and the location of local seismic events in east Java particularly beneath Lusi.This network will locate small event that may not be captured by the existing BMKG network. It will be crucial to design the second phase of the seismic experiment that will consist of a local earthquake tomography of the Lusi-AW region and spatial and temporal variations of vp/vs ratios. The goal of this study is to understand how the seismicity occurring along the Sunda subduction zone affects to the behavior of the Lusi eruption. Our study will also provide a large dataset for a qualitative analysis of earthquake triggering studies, earthquake-volcano and earthquake-earthquake interactions. In this study, we will extract Green’s functions from ambient seismic noise data in order to image the shallow subsurface structure beneath LUSI area. The waveform cross-correlation technique will be apply to all of recordings of ambient seismic noise at 30 seismographic stations around the LUSI area. We use the dispersive behaviour of the retrieved Rayleigh waves to infer velocity structures in the shallow subsurface

  2. Structural priming and frequency effects interact in Chinese sentence comprehension

    Directory of Open Access Journals (Sweden)

    Hang eWei

    2016-02-01

    Full Text Available Previous research in several European languages has shown that the language processing system is sensitive to both structural frequency and structural priming effects. However, it is currently not clear whether these two types of effects interact during online sentence comprehension, especially for languages that do not have morphological markings. To explore this issue, the present study investigated the possible interplay between structural priming and frequency effects for sentences containing the Chinese ambiguous construction V NP1 de NP2 in a self-paced reading experiment. The sentences were disambiguated to either the more frequent/preferred NP structure or the less frequent VP structure. Each target sentence was preceded by a prime sentence of three possible types: NP primes, VP primes, and neutral primes. When the ambiguous construction V NP1 de NP2 was disambiguated to the dispreferred VP structure, participants experienced more processing difficulty following an NP prime relative to following a VP prime or a neutral baseline. When the ambiguity was resolved to the preferred NP structure, prime type had no effect. These results suggest that structural priming in comprehension is modulated by the baseline frequency of alternative structures, with the less frequent structure being more subject to structural priming effects. These results are discussed in the context of the error-based, implicit learning account of structural priming.

  3. Multiple intelligences and alternative teaching strategies: The effects on student academic achievement, conceptual understanding, and attitude

    Science.gov (United States)

    Baragona, Michelle

    The purpose of this study was to investigate the interactions between multiple intelligence strengths and alternative teaching methods on student academic achievement, conceptual understanding and attitudes. The design was a quasi-experimental study, in which students enrolled in Principles of Anatomy and Physiology, a developmental biology course, received lecture only, problem-based learning with lecture, or peer teaching with lecture. These students completed the Multiple Intelligence Inventory to determine their intelligence strengths, the Students' Motivation Toward Science Learning questionnaire to determine student attitudes towards learning in science, multiple choice tests to determine academic achievement, and open-ended questions to determine conceptual understanding. Effects of intelligence types and teaching methods on academic achievement and conceptual understanding were determined statistically by repeated measures ANOVAs. No significance occurred in academic achievement scores due to lab group or due to teaching method used; however, significant interactions between group and teaching method did occur in students with strengths in logical-mathematical, interpersonal, kinesthetic, and intrapersonal intelligences. Post-hoc analysis using Tukey HSD tests revealed students with strengths in logical-mathematical intelligence and enrolled in Group Three scored significantly higher when taught by problem-based learning (PBL) as compared to peer teaching (PT). No significance occurred in conceptual understanding scores due to lab group or due to teaching method used; however, significant interactions between group and teaching method did occur in students with strengths in musical, kinesthetic, intrapersonal, and spatial intelligences. Post-hoc analysis using Tukey HSD tests revealed students with strengths in logical-mathematical intelligence and enrolled in Group Three scored significantly higher when taught by lecture as compared to PBL. Students with

  4. Current Understanding on Antihepatocarcinoma Effects of Xiao Chai Hu Tang and Its Constituents

    Directory of Open Access Journals (Sweden)

    Ningning Zheng

    2013-01-01

    Full Text Available Xiao Chai Hu Tang (XCHT, a compound formula originally recorded in an ancient Chinese medical book Shanghanlun, has been used to treat chronic liver diseases for a long period of time in China. Although extensive studies have been demonstrated the efficacy of this formula to treat chronic hepatitis, hepatic fibrosis, and hepatocarcinoma, how it works against these diseases still awaits full understanding. Here, we firstly present an overview arranging from the entire formula to mechanism studies of single herb in XCHT and their active components, from a new perspective of “separation study,” and we tried our best to both detailedly and systematically organize the antihepatocarcinoma effects of it, hoping that the review will facilitate the strive on elucidating how XCHT elicits its antihepatocarcinoma role.

  5. Toward understanding the thermodynamics of TALSPEAK process. Medium effects on actinide complexation

    International Nuclear Information System (INIS)

    Zalupski, Peter R.; Martin, Leigh R.; Nash, Ken; Nakamura, Yoshinobu; Yamamoto, Masahiko

    2009-01-01

    The ingenious combination of lactate and diethylenetriamine-N,N,N',N(double p rime),N(double p rime)-pentaacetic acid (DTPA) as an aqueous actinide-complexing medium forms the basis of the successful separation of americium and curium from lanthanides known as the TALSPEAK process. While numerous reports in the prior literature have focused on the optimization of this solvent extraction system, considerably less attention has been devoted to the understanding of the basic thermodynamic features of the complex fluids responsible for the separation. The available thermochemical information of both lactate and DTPA protonation and metal complexation reactions are representative of the behavior of these ions under idealized conditions. Our previous studies of medium effects on lactate protonation suggest that significant departures from the speciation predicted based on reported thermodynamic values should be expected in the TALSPEAK aqueous environment. Thermodynamic parameters describing the separation chemistry of this process thus require further examination at conditions significantly removed from conventional ideal systems commonly employed in fundamental solution chemistry. Such thermodynamic characterization is the key to predictive modelling of TALSPEAK. Improved understanding will, in principle, allow process technologists to more efficiently respond to off-normal conditions during large scale process operation. In this report, the results of calorimetric and potentiometric investigations of the effects of aqueous electrolytes on the thermodynamic parameters for lactate protonation and lactate complexation of americium and neodymium will be presented. Studies on the lactate protonation equilibrium will clearly illustrate distinct thermodynamic variations between strong electrolyte aqueous systems and buffered lactate environment.

  6. Understanding the protective effects of wine components and their metabolites in the brain function

    Directory of Open Access Journals (Sweden)

    Esteban-Fernández A.

    2016-01-01

    Full Text Available Moderate wine consumption has been suggested to exert a positive effect in prevention of neurodegenerative process and cognitive impairment. With the ultimate aim of achieving a better understanding of the molecular mechanisms behind this benefit, we have investigated the role of certain wine- derived phenolic metabolites and aroma compounds in the MAPK cascade (including ERK1/2, p38, one of the routes directly related to inflammation in neuronal cells. Some of the tested phenolic compounds, especially in the case of 3,4-dihydroxyphenylacetic acid, showed a significant neuroprotective effect against SIN-1-induced neuronal death. Regarding their effect over MAPK phosphorylation, inmunoblotting technique revealed a beneficial and significant decrease on the phosphorylation of p38 and ERK1/2 kinases after incubation with wine constituents. In addition, activity of caspase3-like protease, an executor of neuronal apoptosis and a downstream signal of MAPK, was significantly diminished by 3-(3-hydroxyphenyl propionic acid and linalool, counterbalancing the increase produced by SIN-1. Altogether, these results suggest that wine aroma, phenolic compounds and their gut metabolites could exert neuroprotective actions by modulating MAPK signalling and caspase-3 proteases activation, which are known to play a key role in oxidative/ nitrosative stress-induced response.

  7. CALCULATING ROTATING HYDRODYNAMIC AND MAGNETOHYDRODYNAMIC WAVES TO UNDERSTAND MAGNETIC EFFECTS ON DYNAMICAL TIDES

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xing, E-mail: xing.wei@sjtu.edu.cn [Institute of Natural Sciences and Department of Physics and Astronomy, Shanghai Jiao Tong University (China); Princeton University Observatory, Princeton, NJ 08544 (United States)

    2016-09-01

    To understand magnetic effects on dynamical tides, we study the rotating magnetohydrodynamic (MHD) flow driven by harmonic forcing. The linear responses are analytically derived in a periodic box under the local WKB approximation. Both the kinetic and Ohmic dissipations at the resonant frequencies are calculated, and the various parameters are investigated. Although magnetic pressure may be negligible compared to thermal pressure, the magnetic field can be important for the first-order perturbation, e.g., dynamical tides. It is found that the magnetic field splits the resonant frequency, namely the rotating hydrodynamic flow has only one resonant frequency, but the rotating MHD flow has two, one positive and the other negative. In the weak field regime the dissipations are asymmetric around the two resonant frequencies and this asymmetry is more striking with a weaker magnetic field. It is also found that both the kinetic and Ohmic dissipations at the resonant frequencies are inversely proportional to the Ekman number and the square of the wavenumber. The dissipation at the resonant frequency on small scales is almost equal to the dissipation at the non-resonant frequencies, namely the resonance takes its effect on the dissipation at intermediate length scales. Moreover, the waves with phase propagation that is perpendicular to the magnetic field are much more damped. It is also interesting to find that the frequency-averaged dissipation is constant. This result suggests that in compact objects, magnetic effects on tidal dissipation should be considered.

  8. Understanding Birnessite MnO2: Effects of Small Polaron and Local Dipole

    Science.gov (United States)

    Peng, Haowei; Perdew, John P.

    Birnessite MnO2, usually with cations like K and Na intercalated between layers, is a class of potential cheap oxygen evolution reaction (OER) catalyst. Using hybrid density functional calculations, we investigate the electronic structures of the layered MnO2 with the intercalated cation modelled as a defect. We found that an electron small polaron will form when an extra electron is doped in the pure MnO2, turning a Mn(IV) to a Mn(III) with a singly occupied eg orbital located within the band gap, and the resulting small-polaron hopping conduction explains the observed low electric conductivity. The inter-layer doped K atom will donate one electron to one Mn ion as expected, and also contributes to a local dipole forming between K and the Mn(III), raising the electrostatic potential of the specific layer. With a certain spatial distribution of such local dipoles, the small-polaron eg states become comparable in energy with the global conduction band minimum, and charge transfer occurs. This further results in a singly or partially occupied eg orbital near the Fermi level, which has been regarded as a signal for an excellent OER catalyst. Our calculation helps understanding several experimental observations. This work was supported as part of the CCDM-EFRC funded by the U.S. DOE, Office of Science, Basic Energy Sciences.

  9. Increasing the understanding of chemical concepts: The effectiveness of multiple exposures

    Science.gov (United States)

    Bius, Janet H.

    Chemistry is difficult because it has multilevels of knowledge with each level presenting challenges in vocabulary, abstract thinking, and symbolic language. Students have to be able to transfer between levels to understand the concepts and the theoretical models of chemistry. The cognitive theories of constructivism and cognitive-load theory are used to explain the difficulties novice learners have with the subject of chemistry and methods to increase success for students. The relationship between external representations, misconceptions and topics on the success of students are addressed. If students do not know the formalisms associated with chemical diagrams and graphs, the representations will decrease student success. Misconceptions can be formed when new information is interpreted based on pre-existing knowledge that is faulty. Topics with large amount of interacting elements that must be processed simultaneously are considered difficult to understand. New variables were created to measure the number of times a student is exposed to a chemical concept. Each variable was coded according to topic and learning environment, which are the lecture and laboratory components of the course, homework assignments and textbook examples. The exposure variables are used to measure the success rate of students on similar exam questions. Question difficulty scales were adapted for this project from those found in the chemical education literature. The exposure variables were tested on each level of the difficulty scales to determine their effect at decreasing the cognitive demand of these questions. The subjects of this study were freshmen science majors at a large Midwest university. The effects of the difficulty scales and exposure variables were measured for those students whose exam scores were in the upper one-fourth percentile, for students whose test scores were in the middle one-half percentile, and the lower one-fourth percentile are those students that scored the

  10. Understanding the physics of a possible non-Abelian fractional quantum hall effect state.

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Wei; Crawford, Matthew; Tallakulam, Madhu; Ross, Anthony Joseph, III

    2010-10-01

    We wish to present in this report experimental results from a one-year Senior Council Tier-1 LDRD project that focused on understanding the physics of a possible non-Abelian fractional quantum Hall effect state. We first give a general introduction to the quantum Hall effect, and then present the experimental results on the edge-state transport in a special fractional quantum Hall effect state at Landau level filling {nu} = 5/2 - a possible non-Abelian quantum Hall state. This state has been at the center of current basic research due to its potential applications in fault-resistant topological quantum computation. We will also describe the semiconductor 'Hall-bar' devices we used in this project. Electron physics in low dimensional systems has been one of the most exciting fields in condensed matter physics for many years. This is especially true of quantum Hall effect (QHE) physics, which has seen its intellectual wealth applied in and has influenced many seemingly unrelated fields, such as the black hole physics, where a fractional QHE-like phase has been identified. Two Nobel prizes have been awarded for discoveries of quantum Hall effects: in 1985 to von Klitzing for the discovery of integer QHE, and in 1998 to Tsui, Stormer, and Laughlin for the discovery of fractional QHE. Today, QH physics remains one of the most vibrant research fields, and many unexpected novel quantum states continue to be discovered and to surprise us, such as utilizing an exotic, non-Abelian FQHE state at {nu} = 5/2 for fault resistant topological computation. Below we give a briefly introduction of the quantum Hall physics.

  11. Understanding the complex determinants of height and adiposity in disadvantaged daycare preschoolers in Salvador, NE Brazil through structural equation modelling.

    Science.gov (United States)

    Lander, Rebecca L; Williams, Sheila M; Costa-Ribeiro, Hugo; Mattos, Angela P; Barreto, Danile L; Houghton, Lisa A; Bailey, Karl B; Lander, Alastair G; Gibson, Rosalind S

    2015-10-23

    Earlier we reported on growth and adiposity in a cross-sectional study of disadvantaged Brazilian preschoolers. Here we extend the work on these children, using structural equation modelling (SEM) to gather information on the complex relationships between the variables influencing height and adiposity. We hope this information will help improve the design and effectiveness of future interventions for preschoolers. In 376 preschoolers aged 3-6 years attending seven philanthropic daycares in Salvador, we used SEM to examine direct and indirect relationships among biological (sex, ethnicity, birth order, maternal height and weight), socio-economic, micronutrient (haemoglobin, serum selenium and zinc), and environmental (helminths, de-worming) variables on height and adiposity, as reflected by Z-scores for height-for-age (HAZ) and body mass index (BMIZ). Of the children, 11 % had HAZ  1. Of their mothers, 8 % had short stature, and 50 % were overweight or obese. Based on standardized regression coefficients, significant direct effects (p children.

  12. Neighborhood structure effects on the Dynamic response of soil-structure interaction by harmonic analysis

    Directory of Open Access Journals (Sweden)

    Pan Dan-guang

    2015-01-01

    Full Text Available For realizing the variation of structural dynamic characteristics due to neighbor structure in buildings group, the surface structure is idealized as an equivalent single degree of freedom system with rigid base whose site consists of a single homogeneous layer. Based on the model, a equivalent method on the equivalent seismic excitation is proposed. Then, the differences of seismic response and equivalent seismic input between soil - structure interaction (SSI system and structure -soil-structure interaction (SSSI system are investigated by harmonic analysis. The numerical results show that dynamic responses would be underestimated in SSSI system when the forcing frequencies are close to the Natural frequency if the effects of neighborhood structure were ignored. Neighborhood structure would make the translational displacement increase and rocking vibration decrease. When establishing an effective seismic input, it is necessary to consider the impact of inertia interaction.

  13. Effects of structural nonlinearity and foundation sliding on probabilistic response of a nuclear structure

    Energy Technology Data Exchange (ETDEWEB)

    Hashemi, Alidad, E-mail: sahashem@bechtel.com; Elkhoraibi, Tarek; Ostadan, Farhang

    2015-12-15

    Highlights: • Probabilistic SSI analysis including structural nonlinearity and sliding are shown. • Analysis is done for a soil and a rock site and probabilistic demands are obtained. • Structural drift ratios and In-structure response spectra are evaluated. • Structural nonlinearity significantly impacts local demands in the structure. • Sliding generally reduces seismic demands and can be accommodated in design. - Abstract: This paper examines the effects of structural nonlinearity and foundation sliding on the results of probabilistic structural analysis of a typical nuclear structure where structural nonlinearity, foundation sliding and soil-structure interaction (SSI) are explicitly included. The evaluation is carried out for a soil and a rock site at 10{sup 4}, 10{sup 5}, and 10{sup 6} year return periods (1E − 4, 1E − 5, and 1E − 6 hazard levels, respectively). The input motions at each considered hazard level are deaggregated into low frequency (LF) and high frequency (HF) motions and a sample size of 30 is used for uncertainty propagation. The statistical distribution of structural responses including story drifts, and in-structure response spectra (ISRS) as well as foundation sliding displacements are examined. The probabilistic implementation of explicit structural nonlinearity and foundation sliding in combination with the SSI effects are demonstrated using nonlinear response history analysis (RHA) of the structure with the foundation motions obtained from elastic SSI analyses, which are applied as input to fixed-base inelastic analyses. This approach quantifies the expected structural nonlinearity and sliding for the particular structural configuration and provides a robust analytical basis for the estimation of the probabilistic distribution of selected demands parameters both at the design level and beyond design level seismic input. For the subject structure, the inclusion of foundation sliding in the analysis is found to have

  14. Effects of structural nonlinearity and foundation sliding on probabilistic response of a nuclear structure

    International Nuclear Information System (INIS)

    Hashemi, Alidad; Elkhoraibi, Tarek; Ostadan, Farhang

    2015-01-01

    Highlights: • Probabilistic SSI analysis including structural nonlinearity and sliding are shown. • Analysis is done for a soil and a rock site and probabilistic demands are obtained. • Structural drift ratios and In-structure response spectra are evaluated. • Structural nonlinearity significantly impacts local demands in the structure. • Sliding generally reduces seismic demands and can be accommodated in design. - Abstract: This paper examines the effects of structural nonlinearity and foundation sliding on the results of probabilistic structural analysis of a typical nuclear structure where structural nonlinearity, foundation sliding and soil-structure interaction (SSI) are explicitly included. The evaluation is carried out for a soil and a rock site at 10 4 , 10 5 , and 10 6 year return periods (1E − 4, 1E − 5, and 1E − 6 hazard levels, respectively). The input motions at each considered hazard level are deaggregated into low frequency (LF) and high frequency (HF) motions and a sample size of 30 is used for uncertainty propagation. The statistical distribution of structural responses including story drifts, and in-structure response spectra (ISRS) as well as foundation sliding displacements are examined. The probabilistic implementation of explicit structural nonlinearity and foundation sliding in combination with the SSI effects are demonstrated using nonlinear response history analysis (RHA) of the structure with the foundation motions obtained from elastic SSI analyses, which are applied as input to fixed-base inelastic analyses. This approach quantifies the expected structural nonlinearity and sliding for the particular structural configuration and provides a robust analytical basis for the estimation of the probabilistic distribution of selected demands parameters both at the design level and beyond design level seismic input. For the subject structure, the inclusion of foundation sliding in the analysis is found to have reduced both

  15. Neuroimaging studies towards understanding the central effects of pharmacological cannabis products on patients with epilepsy.

    Science.gov (United States)

    Allendorfer, Jane B; Szaflarski, Jerzy P

    2017-05-01

    Recent interest for the use of cannabis-derived products as therapeutic agents in the treatment of epilepsies has necessitated a reevaluation of their effects on brain and behavior. Overall, prolonged cannabis use is thought to result in functional and structural brain alterations. These effects may be dependent on a number of factors: e.g., which phytocannabinoid is used (e.g., cannabidiol (CBD) vs. tetrahyrocannabinol (THC)), the frequency of use (occasional vs. heavy), and at what age (prenatal, childhood, adulthood) the use began. However, due to the fact that there are over seven hundred constituents that make up the Cannabis sativa plant, it is difficult to determine which compound or combination of compounds is responsible for specific effects when studying recreational users. Therefore, this review focuses only on the functional MRI studies investigating the effects of specific pharmacological preparations of cannabis compounds, specifically THC, tetrahydrocannabivarin (THCV), and CBD, on brain function in healthy individuals and persons with epilepsy with references to non-epilepsy studies only to underline the gaps in research that need to be filled before cannabis-derived products are considered for a wide use in the treatment of epilepsy. This article is part of a Special Issue entitled "Cannabinoids and Epilepsy". Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Use of the Primitive Unit Cell in Understanding Subtle Features of the Cubic Closest-Packed Structure

    Science.gov (United States)

    Hawkins, John A.; Rittenhouse, Jeffrey L.; Soper, Linda M.; Rittenhouse, Robert C.

    2008-01-01

    One of the most important crystal structures adopted by metals is characterized by the "abcabc"...stacking of close-packed layers. This structure is commonly referred to in textbooks as the cubic close-packed (ccp) or face-centered cubic (fcc) structure, since the entire lattice can be generated by replication of a face-centered cubic unit cell…

  17. Tree growth variation in the tropical forest: understanding effects of temperature, rainfall and CO2.

    Science.gov (United States)

    Schippers, Peter; Sterck, Frank; Vlam, Mart; Zuidema, Pieter A

    2015-01-28

    Tropical forest responses to climatic variability have important consequences for global carbon cycling, but are poorly understood. As empirical, correlative studies cannot disentangle the interactive effects of climatic variables on tree growth, we used a tree growth model (IBTREE) to unravel the climate effects on different physiological pathways and in turn on stem growth variation. We parameterized the model for canopy trees of Toona ciliata (Meliaceae) from a Thai monsoon forest and compared predicted and measured variation from a tree-ring study over a 30-year period. We used historical climatic variation of minimum and maximum day temperature, precipitation and carbon dioxide (CO 2 ) in different combinations to estimate the contribution of each climate factor in explaining the inter-annual variation in stem growth. Running the model with only variation in maximum temperature and rainfall yielded stem growth patterns that explained almost 70% of the observed inter-annual variation in stem growth. Our results show that maximum temperature had a strong negative effect on the stem growth by increasing respiration, reducing stomatal conductance and thus mitigating a higher transpiration demand, and - to a lesser extent - by directly reducing photosynthesis. Although stem growth was rather weakly sensitive to rain, stem growth variation responded strongly and positively to rainfall variation owing to the strong inter-annual fluctuations in rainfall. Minimum temperature and atmospheric CO 2 concentration did not significantly contribute to explaining the inter-annual variation in stem growth. Our innovative approach - combining a simulation model with historical data on tree-ring growth and climate - allowed disentangling the effects of strongly correlated climate variables on growth through different physiological pathways. Similar studies on different species and in different forest types are needed to further improve our understanding of the sensitivity of

  18. Managing a new collaborative entity in business organizations: understanding organizational communities of practice effectiveness.

    Science.gov (United States)

    Kirkman, Bradley L; Mathieu, John E; Cordery, John L; Rosen, Benson; Kukenberger, Michael

    2011-11-01

    Companies worldwide are turning to organizational communities of practice (OCoPs) as vehicles to generate learning and enhance organizational performance. OCoPs are defined as groups of employees who share a concern, a set of problems, or a passion about a topic and who strengthen their knowledge and expertise by interacting on a consistent basis. To date, OCoP research has drawn almost exclusively from the community of practice (CoP) literature, even though the organizational form of CoPs shares attributes of traditional CoPs and of organizational teams. Drawing on Lave and Wenger's (1991) original theory of legitimate peripheral participation, we integrate theory and research from CoPs and organizational teams to develop and empirically examine a model of OCoP effectiveness that includes constructs such as leadership, empowerment, the structure of tasks, and OCoP relevance to organizational effectiveness. Using data from 32 OCoPs in a U.S.-based multinational mining and minerals processing firm, we found that external community leaders play an important role in enhancing OCoP empowerment, particularly to the extent that task interdependence is high. Empowerment, in turn, was positively related to OCoP effectiveness. We also found that OCoPs designated as "core" by the organization (e.g., working on critical issues) were more effective than those that were noncore. Task interdependence also was positively related to OCoP effectiveness. We provide scholars and practitioners with insights on how to effectively manage OCoPs in today's organizations. (c) 2011 APA, all rights reserved.

  19. Using a balloon-borne accelerometer to improve understanding of the turbulent structure of the atmosphere for aviation.

    Science.gov (United States)

    Marlton, Graeme; Harrison, Giles; Nicoll, Keri; Williams, Paul

    2017-04-01

    This work describes the instrument development, characterisation and data analysis from 51 radiosondes specially equipped with accelerometers to measure atmospheric turbulence. Turbulence is hazardous to aircraft as it cannot be observed in advance. It is estimated that turbulence costs the airline industry millions of US dollars a year through damage to aircraft and injuries to passengers and crew. To avoid turbulence pilots and passengers rely on Clear Air Turbulence forecasts, which have limited skill. One limitation in this area is lack of quantitative unbiased observations. The main source of turbulence observations is from commercial airline pilot reports, which are subjective, biased by the size of aircraft and pilot experience. This work seeks to improve understanding of turbulence through a standardised method of turbulence observations amenable throughout the troposphere. A sensing package has been developed to measure the acceleration of the radiosonde as it swings in response to turbulent agitation of its carrier balloon. The accelerometer radiosonde has been compared against multiple turbulence remote sensing methods to characterise its measurements including calibration with Doppler lidar eddy dissipation rate in the boundary layer. A further relationship has been found by comparison with the spectral width of a Mesospheric, Stratospheric and Tropospheric (MST) radar. From the full dataset of accelerometer sonde ascents a standard deviation of 5 m s-2 is defined as a threshold for significant turbulence. The dataset spans turbulence generated in meteorological phenomena such as jet streams, clouds and in the presence of convection. The analysis revealed that 77% of observed turbulence could be explained by the aforementioned phenomena. In jet streams, turbulence generation was often caused by horizontal processes such as deformation. In convection, turbulence is found to form when CAPE >150 J kg-1. Deeper clouds were found to be more turbulent due to

  20. Understanding health care provider barriers to hospital affiliated medical fitness center facility referral: a questionnaire survey and semi structured interviews.

    Science.gov (United States)

    Smock, Carissa; Alemagno, Sonia

    2017-08-03

    The purpose of this study is to understand health care provider barriers to referring patients to Medical Fitness Center Facilities within an affiliated teaching hospital system using referral of diabetic services as an example. The aims of this study include: (1) to assess health care providers' awareness and use of facilities, (2) to determine barriers to referring patients to facilities, (3) identify current and needed resources and/or changes to increase referral to facilities. A 20-item electronic survey and requests for semi-structured interviews were administered to hospital system directors and managers (n = 51). Directors and managers instructed physicians and staff to complete the survey and interviews as applicable. Perceived barriers, knowledge, utilization, and referral of patients to Medical Fitness Center Facilities were collected and examined. Descriptive statistics were generated regarding practice characteristics, provider characteristics, and referral. Of the health care providers surveyed and interviewed (n = 25) 40% indicated verbally suggesting use of facilities, 24% provided a flyer about the facilities. No respondents indicated that they directly referred patients to the facilities. However, 16% referred patients to other locations for physical activity - including their own department's management and prevention services. 20% do not refer to Medical Fitness Center Facilities or any other lifestyle programs/locations. Lack of time (92%) and lack of standard guidelines and operating procedures (88%) are barriers to referral. All respondents indicated a strong ability to refer patients to Medical Fitness Center Facilities if given education about referral programs available as well as standard clinical guidelines and protocol for delivery. The results of this study indicate that, although few healthcare providers are currently referring patients to Medical Fitness Center Facilities, health care providers with an affiliated Medical Fitness

  1. Understanding the structure, dynamics, and mass transport properties of self assembling peptide hydrogels for injectable, drug delivery applications

    Science.gov (United States)

    Branco, Monica Cristina

    hydrogels as a function of peptide sequence and concentration. Changes in nanoscale dynamics and structure inherently lead to substantial differences in bulk properties, such as the elastic modulus and network mesh size. Learning how the material properties of the gels influence the transport rate of therapeutics through the hydrogel is essential to the development of delivery vehicles. The remainder of the thesis focuses on correlating the mesh sizes of MAX1 and MAX8 gels to the diffusion and mass transport properties of model dextran and protein probes. Here, work is centered on how peptide charge and concentration, as well as probe structure, in particular hydrodynamic diameter and charge, dictate the temporal release of model probes from the peptide hydrogels. Experiments include self diffusion studies and bulk release experiments with model dextrans and proteins from gels before and after syringe delivery. Overall, this thesis will demonstrate the importance of understanding material properties from the nanoscale up to the macroscale for application based design. With this approach, better and specific development of self-assembling peptide materials can be achieved, allowing for the rational engineering of peptide sequences to form hydrogels appropriate for specific drug delivery applications.

  2. Composition-Effects of Context-based Learning Opportunities on Students' Understanding of Energy

    Science.gov (United States)

    Podschuweit, Sören; Bernholt, Sascha

    2017-05-01

    Context-based learning has become a widespread approach in science education. While positive motivational effects of such approaches have been well established empirically, clear results regarding cognitive aspects of students' learning are still missing. In this article, we argue that this circumstance might be mainly rooted in the definition of context itself. Based on this argument, we shift from the issue of if contexts are cognitively beneficial to focus on the question of which composition of contexts is, at least by tendency, more effective than another. Based on theories of conceptual change, we therefore conducted a small-scale intervention study comparing two groups of students learning in different sets of contexts focusing on the same scientific concept—the cross-cutting concept of energy. Results suggest that learning in a more heterogeneous set of contexts eases transfer to new contexts in comparison to learning in a more homogeneous set of contexts. However, a more abstract understanding of the energy concept does not seem to be fostered by either of these approaches. Theoretical as well as practical implications of these finding are discussed.

  3. Effectiveness of the Wavelet Transform on the Surface EMG to Understand the Muscle Fatigue During Walk

    Science.gov (United States)

    Hussain, M. S.; Mamun, Md.

    2012-01-01

    Muscle fatigue is the decline in ability of a muscle to create force. Electromyography (EMG) is a medical technique for measuring muscle response to nervous stimulation. During a sustained muscle contraction, the power spectrum of the EMG shifts towards lower frequencies. These effects are due to muscle fatigue. Muscle fatigue is often a result of unhealthy work practice. In this research, the effectiveness of the wavelet transform applied to the surface EMG (SEMG) signal as a means of understanding muscle fatigue during walk is presented. Power spectrum and bispectrum analysis on the EMG signal getting from right rectus femoris muscle is executed utilizing various wavelet functions (WFs). It is possible to recognize muscle fatigue appreciably with the proper choice of the WF. The outcome proves that the most momentous changes in the EMG power spectrum are symbolized by WF Daubechies45. Moreover, this research has compared bispectrum properties to the other WFs. To determine muscle fatigue during gait, Daubechies45 is used in this research to analyze the SEMG signal.

  4. A transdisciplinary approach to understanding the health effects of wildfire and prescribed fire smoke regimes

    Science.gov (United States)

    Williamson, G. J.; Bowman, D. M. J. S.; Price, O. F.; Henderson, S. B.; Johnston, F. H.

    2016-12-01

    Prescribed burning is used to reduce the occurrence, extent and severity of uncontrolled fires in many flammable landscapes. However, epidemiologic evidence of the human health impacts of landscape fire smoke emissions is shaping fire management practice through increasingly stringent environmental regulation and public health policy. An unresolved question, critical for sustainable fire management, concerns the comparative human health effects of smoke from wild and prescribed fires. Here we review current knowledge of the health effects of landscape fire emissions and consider the similarities and differences in smoke from wild and prescribed fires with respect to the typical combustion conditions and fuel properties, the quality and magnitude of air pollution emissions, and the potential for dispersion to large populations. We further examine the interactions between these considerations, and how they may shape the longer term smoke regimes to which populations are exposed. We identify numerous knowledge gaps and propose a conceptual framework that describes pathways to better understanding of the health trade-offs of prescribed and wildfire smoke regimes.

  5. Understanding the effects of electronic polarization and delocalization on charge-transport levels in oligoacene systems

    KAUST Repository

    Sutton, Christopher

    2017-06-13

    Electronic polarization and charge delocalization are important aspects that affect the charge-transport levels in organic materials. Here, using a quantum mechanical/ embedded-charge (QM/EC) approach based on a combination of the long-range corrected omega B97X-D exchange-correlation functional (QM) and charge model 5 (CM5) point-charge model (EC), we evaluate the vertical detachment energies and polarization energies of various sizes of crystalline and amorphous anionic oligoacene clusters. Our results indicate that QM/EC calculations yield vertical detachment energies and polarization energies that compare well with the experimental values obtained from ultraviolet photoemission spectroscopy measurements. In order to understand the effect of charge delocalization on the transport levels, we considered crystalline naphthalene systems with QM regions including one or five-molecules. The results for these systems show that the delocalization and polarization effects are additive; therefore, allowing for electron delocalization by increasing the size of the QM region leads to the additional stabilization of the transport levels. Published by AIP Publishing.

  6. Individual differences in children's emotion understanding: Effects of age and language

    DEFF Research Database (Denmark)

    Pons, Francisco; Lawson, J.: Harris, P.; Rosnay, M. de

    2003-01-01

    Over the last two decades, it has been established that children's emotion understanding changes as they develop. Recent studies have also begun to address individual differences in children's emotion understanding. The first goal of this study was to examine the development of these individual...... differences across a wide age range with a test assessing nine different components of emotion understanding. The second goal was to examine the relation between language ability and individual differences in emotion understanding. Eighty children ranging in age from 4 to 11 years were tested. Children...... displayed a clear improvement with age in both their emotion understanding and language ability. In each age group, there were clear individual differences in emotion understanding and language ability. Age and language ability together explained 72% of emotion understanding variance; 20% of this variance...

  7. Understanding uncertainty in temperature effects on vector-borne disease: a Bayesian approach.

    Science.gov (United States)

    Johnson, Leah R; Ben-Horin, Tal; Lafferty, Kevin D; McNally, Amy; Mordecai, Erin; Paaijmans, Krijn P; Pawar, Samraat; Ryan, Sadie J

    2015-01-01

    Extrinsic environmental factors influence the distribution and population dynamics of many organisms, including insects that are of concern for human health and agriculture. This is particularly true for vector-borne infectious diseases like malaria, which is a major source of morbidity and mortality in humans. Understanding the mechanistic links between environment and population processes for these diseases is key to predicting the consequences of climate change on transmission and for developing effective interventions. An important measure of the intensity of disease transmission is the reproductive number R0. However, understanding the mechanisms linking R0 and temperature, an environmental factor driving disease risk, can be challenging because the data available for parameterization are often poor. To address this, we show how a Bayesian approach can help identify critical uncertainties in components of R0 and how this uncertainty is propagated into the estimate of R0. Most notably, we find that different parameters dominate the uncertainty at different temperature regimes: bite rate from 15 degrees C to 25 degrees C; fecundity across all temperatures, but especially approximately 25-32 degrees C; mortality from 20 degrees C to 30 degrees C; parasite development rate at degrees 15-16 degrees C and again at approximately 33-35 degrees C. Focusing empirical studies on these parameters and corresponding temperature ranges would be the most efficient way to improve estimates of R0. While we focus on malaria, our methods apply to improving process-based models more generally, including epidemiological, physiological niche, and species distribution models.

  8. Understanding uncertainty in temperature effects on vector-borne disease: a Bayesian approach

    Science.gov (United States)

    Johnson, Leah R.; Ben-Horin, Tal; Lafferty, Kevin D.; McNally, Amy; Mordecai, Erin A.; Paaijmans, Krijn P.; Pawar, Samraat; Ryan, Sadie J.

    2015-01-01

    Extrinsic environmental factors influence the distribution and population dynamics of many organisms, including insects that are of concern for human health and agriculture. This is particularly true for vector-borne infectious diseases like malaria, which is a major source of morbidity and mortality in humans. Understanding the mechanistic links between environment and population processes for these diseases is key to predicting the consequences of climate change on transmission and for developing effective interventions. An important measure of the intensity of disease transmission is the reproductive number R0. However, understanding the mechanisms linking R0 and temperature, an environmental factor driving disease risk, can be challenging because the data available for parameterization are often poor. To address this, we show how a Bayesian approach can help identify critical uncertainties in components of R0 and how this uncertainty is propagated into the estimate of R0. Most notably, we find that different parameters dominate the uncertainty at different temperature regimes: bite rate from 15°C to 25°C; fecundity across all temperatures, but especially ~25–32°C; mortality from 20°C to 30°C; parasite development rate at ~15–16°C and again at ~33–35°C. Focusing empirical studies on these parameters and corresponding temperature ranges would be the most efficient way to improve estimates of R0. While we focus on malaria, our methods apply to improving process-based models more generally, including epidemiological, physiological niche, and species distribution models.

  9. Streamflow depletion by wells--Understanding and managing the effects of groundwater pumping on streamflow

    Science.gov (United States)

    Barlow, Paul M.; Leake, Stanley A.

    2012-11-02

    Groundwater is an important source of water for many human needs, including public supply, agriculture, and industry. With the development of any natural resource, however, adverse consequences may be associated with its use. One of the primary concerns related to the development of groundwater resources is the effect of groundwater pumping on streamflow. Groundwater and surface-water systems are connected, and groundwater discharge is often a substantial component of the total flow of a stream. Groundwater pumping reduces the amount of groundwater that flows to streams and, in some cases, can draw streamflow into the underlying groundwater system. Streamflow reductions (or depletions) caused by pumping have become an important water-resource management issue because of the negative impacts that reduced flows can have on aquatic ecosystems, the availability of surface water, and the quality and aesthetic value of streams and rivers. Scientific research over the past seven decades has made important contributions to the basic understanding of the processes and factors that affect streamflow depletion by wells. Moreover, advances in methods for simulating groundwater systems with computer models provide powerful tools for estimating the rates, locations, and timing of streamflow depletion in response to groundwater pumping and for evaluating alternative approaches for managing streamflow depletion. The primary objective of this report is to summarize these scientific insights and to describe the various field methods and modeling approaches that can be used to understand and manage streamflow depletion. A secondary objective is to highlight several misconceptions concerning streamflow depletion and to explain why these misconceptions are incorrect.

  10. The Compensatory Effect of Graphic Organizer Instruction on Text Structure.

    Science.gov (United States)

    Alvermann, Donna E.

    This study has three purposes: (1) to determine whether the graphic organizer (a schematic representation of text structure using key vocabulary terms) could be used to compensate for the effects of a passage organized with a description top-level structure; (2) to explore the effectiveness of providing students differing in reading ability with…

  11. Size effect in the strength of concrete structures

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Longman) pp 151–165. Karihaloo B L 1999 Size effect in shallow and deep notched quasi-brittle structures. Int. J. Fracture. 95: 379–390. Karihaloo B L, Abdalla H M 2001 Size effect in hardened cement paste and high strength concrete. In. Fracture mechanics of concrete structures (eds) de Borst et al (Lisse: Balkema) vol.2 ...

  12. Proximity effect gaps in S/N/FI structures

    NARCIS (Netherlands)

    Huertas-Hernando, D.; Nazarov, Y.V.

    2005-01-01

    We study the proximity effect in hybrid structures consisting of superconductor and ferromagnetic insulator separated by a normal diffusive metal (S/N/FI structures). These stuctures were proposed to realize the absolute spin-valve effect. We pay special attention to the gaps in the density of

  13. Effect of Fracture on Crushing of Ship Structures

    DEFF Research Database (Denmark)

    Simonsen, Bo Cerup; Abramowicz, W.

    2003-01-01

    This paper is concerned with loads and energy absorption during crushing of ship structures. Particular focus is on the effect of fracture of welds or parent material on the energy absorption of typical structural subassemblies of ships during deep collapse. The paper presents experiments...... absorption in axial crushing of typical ship structural components. This effect of fracture has been neglected in previously published studies of bow crushing mechanics....

  14. Atomic-scale understanding of non-stoichiometry effects on the electrochemical performance of Ni-rich cathode materials

    Science.gov (United States)

    Kong, Fantai; Liang, Chaoping; Longo, Roberto C.; Zheng, Yongping; Cho, Kyeongjae

    2018-02-01

    As the next-generation high energy capacity cathode materials for Li-ion batteries, Ni-rich oxides face the problem of obtaining near-stoichiometric phases due to excessive Ni occupying Li sites. These extra-Ni-defects drastically affect the electrochemical performance. Despite of its importance, the fundamental correlation between such defects and the key electrochemical properties is still poorly understood. In this work, using density-functional-theory, we report a comprehensive study on the effects of non-stoichiometric phases on properties of Ni-rich layered oxides. For instance, extra-Ni-defects trigger charge disproportionation reaction within the system, alleviating the Jahn-Teller distortion of Ni3+ ions, which constitutes an important reason for their low formation energies. Kinetic studies of these defects reveal their immobile nature, creating a "pillar effect" that increases the structural stability. Ab initio molecular dynamics revealed Li depletion regions surrounding extra-Ni-defects, which are ultimate responsible for the arduous Li diffusion and re-intercalation, resulting in poor rate performance and initial capacity loss. Finally, the method with combination of high valence cation doping and ion-exchange synthesis is regarded as the most promising way to obtain stoichiometric oxides. Overall, this work not only deepens our understanding of non-stoichiometric Ni-rich layered oxides, but also enables further optimizations of high energy density cathode materials.

  15. Structuring a cost-effective site characterization

    International Nuclear Information System (INIS)

    Berven, B.A.; Little, C.A.; Swaja, R.E.

    1990-01-01

    Successful chemical and radiological site characterizations are complex activities which require meticulously detailed planning. Each layer of investigation is based upon previously generated information about the site. Baseline historical, physical, geological, and regulatory information is prerequisite for preliminary studies at a site. Preliminary studies then provide samples and measurements which define the identity of potential contaminants and define boundaries around the area to be investigated. The goal of a full site characterization is to accurately determine the extent and magnitude of contaminants and carefully define the site conditions such that the future movements of site contaminants can be assessed for potential exposure to human occupants and/or environmental impacts. Critical to this process is the selection of appropriate measurement and sampling methodology, selection and use of appropriate instrumentation and management/interpretation of site information. Site investigations require optimization between the need of information to maximize the understanding of site conditions and the cost of acquiring that information. 5 refs., 1 tab

  16. Understanding negative impacts of perceived cognitive load on job learning effectiveness: a social capital solution.

    Science.gov (United States)

    Lin, Chieh-Peng

    2010-12-01

    This study proposes a model explaining how social capital helps ease excessively required mental effort. Although organizational researchers have studied both social capital and cognitive load, no prior research has critically examined the role of social capital in improving individuals' mental load and effort and consequently enhancing job learning effectiveness. This study surveys participants made up of professionals in Taiwan's information technology industry. It measures the constructs with the use of 5-point Likert-type scale items modified from existing literature. The survey data were analyzed with the use of structural equation modeling. Job learning effectiveness is negatively influenced by role ambiguity and role conflict. Time pressure has a positive influence on role ambiguity and role conflict Although the relationship between task complexity and role ambiguity is insignificant, task complexity has a positive influence on role conflict. Because the relationship between network ties and role conflict is insignificant, trust has a negative influence on role conflict. Last, shared vision has a negative influence on role ambiguity. This study provides an example of how social capital can be applied as a useful remedy to ease the negative impact of perceived cognitive load on job learning effectiveness. The negative relationship between shared vision and role ambiguity suggests that a shared vision helps in disseminating organizationally common goals and directions among employees to alleviate individuals' mental efforts in dealing with the ambiguity of their job roles. A firm's management team should take actions to decrease role conflict by strengthening trust among employees.

  17. Lagrangian Flow Network: a new tool to evaluate connectivity and understand the structural complexity of marine populations

    Science.gov (United States)

    Rossi, V.; Dubois, M.; Ser-Giacomi, E.; Monroy, P.; Lopez, C.; Hernandez-Garcia, E.

    2016-02-01

    Assessing the spatial structure and dynamics of marine populations is still a major challenge for ecologists. The necessity to manage marine resources from a large-scale perspective and considering the whole ecosystem is now recognized but the absence of appropriate tools to address these objectives limits the implementation of globally pertinent conservation planning. Inspired from Network Theory, we present a new methodological framework called Lagrangian Flow Network which allows a systematic characterization of multi-scale dispersal and connectivity of early life history stages of marine organisms. The network is constructed by subdividing the basin into an ensemble of equal-area subregions which are interconnected through the transport of propagules by ocean currents. The present version allows the identification of hydrodynamical provinces and the computation of various connectivity proxies measuring retention and exchange of larvae. Due to our spatial discretization and subsequent network representation, as well as our Lagrangian approach, further methodological improvements are handily accessible. These future developments include a parametrization of habitat patchiness, the implementation of realistic larval traits and the consideration of abiotic variables (e.g. temperature, salinity, planktonic resources...) and their effects on larval production and survival. While the model is potentially tunable to any species whose biological traits and ecological preferences are precisely known, it can also be used in a more generic configuration by efficient computing and analysis of a large number of experiments with relevant ecological parameters. It permits a better characterization of population connectivity at multiple scales and it informs its ecological and managerial interpretations.

  18. Understanding the effect of polylysine architecture on DNA binding using molecular dynamics simulations.

    Science.gov (United States)

    Elder, Robert M; Emrick, Todd; Jayaraman, Arthi

    2011-11-14

    Polycations with varying chemistries and architectures have been synthesized and used in DNA transfection. In this paper we connect poly-L-lysine (PLL) architecture to DNA-binding strength, and in turn transfection efficiency, since experiments have shown that graft-type oligolysine architectures [e.g., poly(cyclooctene-g-oligolysine)] exhibit higher transfection efficiency than linear PLL. We use atomistic molecular dynamics simulations to study structural and thermodynamic effects of polycation-DNA binding for linear PLL and grafted oligolysines of varying graft lengths. Structurally, linear PLL binds in a concerted manner, while each oligolysine graft binds independently of its neighbors in the grafted architecture. Additionally, the presence of a hydrophobic backbone in the grafted architecture weakens binding to DNA compared to linear PLL. The binding free energy varies nonmonotonically with the graft length primarily due to entropic contributions. The binding free energy normalized to the number of bound amines is similar between the grafted and linear architectures at the largest (Poly5) and smallest (Poly2) graft length and stronger than the intermediate graft lengths (Poly3 and Poly4). These trends agree with experimental results that show higher transfection efficiency for Poly3 and Poly4 grafted oligolysines than for Poly5, Poly2, and linear PLL.

  19. Structure effect on wear resistance of alloys

    International Nuclear Information System (INIS)

    Stepina, A.I.; Sidorova, L.I.; Tolstenko, E.V.

    1982-01-01

    The dependence of wear resistance on hardness of steels with different microstructure is studied under conditions of gas-abrasion wear of surface layers. It is found out that at the same hardness the wear resistance of α-alloys is higher than that of γ-alloys in spite of considerable surface hardening of austenitic alloys. Fracture of surface in the process of abrasive wear occurs after achievement of definite values of microhardness and the width of a diffraction line for each structural class of alloys [ru

  20. Tax issues in structuring effective cogeneration vehicles

    International Nuclear Information System (INIS)

    Ebel, S.R.

    1999-01-01

    An overview of the Canadian income tax laws that apply to cogeneration projects was presented. Certain tax considerations could be taken into account in deciding upon ownership and financing structures for cogeneration projects, particularly those that qualify for class 43.1 capital cost allowance treatment. The tax treatment of project revenues and expenses were described. The paper also reviewed the 1999 federal budget proposals regarding the manufacturing and processing tax credit, the capital cost allowance system applicable to cogeneration assets and the treatment of the Canadian renewable conservation expense

  1. Understanding of the mechanical and structural changes induced by alpha particles and heavy ions in the French simulated nuclear waste glass

    International Nuclear Information System (INIS)

    Karakurt, G.; Abdelouas, A.; Guin, J.-P.; Nivard, M.; Sauvage, T.; Paris, M.; Bardeau, J.-F.

    2016-01-01

    Borosilicate glasses are considered for the long-term confinement of high-level nuclear wastes. External irradiations with 1 MeV He + ions and 7 MeV Au 5+ ions were performed to simulate effects produced by alpha particles and by recoil nuclei in the simulated SON68 nuclear waste glass. To better understand the structural modifications, irradiations were also carried out on a 6-oxides borosilicate glass, a simplified version of the SON68 glass (ISG glass). The mechanical and macroscopic properties of the glasses were studied as function of the deposited electronic and nuclear energies. Alpha particles and gold ions induced a volume change up to −0.7% and −2.7%, respectively, depending on the glass composition. Nano-indentations tests were used to determine the mechanical properties of the irradiated glasses. A decrease of about −22% to −38% of the hardness and a decrease of the reduced Young's modulus by −8% were measured after irradiations. The evolution of the glass structure was studied by Raman spectroscopy, and also 11 B and 27 Al Nuclear Magnetic Resonance (MAS-NMR) on a 20 MeV Kr irradiated ISG glass powder. A decrease of the silica network connectivity after irradiation with alpha particles and gold ions is deduced from the structural changes observations. NMR spectra revealed a partial conversion of BO 4 to BO 3 units but also a formation of AlO 5 and AlO 6 species after irradiation with Kr ions. The relationships between the mechanical and structural changes are also discussed. - Highlights: • Mechanical and structural properties of two borosilicate glass compositions irradiated with alpha particles and heavy ions were investigated. • Both kinds of particles induced a decrease of the hardness, reduced Young's modulus and density. • Electronic and nuclear interactions are responsible for the changes observed. • The evolution of the mechanical properties under irradiation is linked to the changes occured in the

  2. Effective propagation in a perturbed periodic structure

    Science.gov (United States)

    Maurel, Agnès; Pagneux, Vincent

    2008-08-01

    In a recent paper [D. Torrent, A. Hakansson, F. Cervera, and J. Sánchez-Dehesa, Phys. Rev. Lett. 96, 204302 (2006)] inspected the effective parameters of a cluster containing an ensemble of scatterers with a periodic or a weakly disordered arrangement. A small amount of disorder is shown to have a small influence on the characteristics of the acoustic wave propagation with respect to the periodic case. In this Brief Report, we inspect further the effect of a deviation in the scatterer distribution from the periodic distribution. The quasicrystalline approximation is shown to be an efficient tool to quantify this effect. An analytical formula for the effective wave number is obtained in one-dimensional acoustic medium and is compared with the Berryman result in the low-frequency limit. Direct numerical calculations show a good agreement with the analytical predictions.

  3. Effective propagation in a perturbed periodic structure

    International Nuclear Information System (INIS)

    Maurel, Agnes; Pagneux, Vincent

    2008-01-01

    In a recent paper [D. Torrent, A. Hakansson, F. Cervera, and J. Sanchez-Dehesa, Phys. Rev. Lett. 96, 204302 (2006)] inspected the effective parameters of a cluster containing an ensemble of scatterers with a periodic or a weakly disordered arrangement. A small amount of disorder is shown to have a small influence on the characteristics of the acoustic wave propagation with respect to the periodic case. In this Brief Report, we inspect further the effect of a deviation in the scatterer distribution from the periodic distribution. The quasicrystalline approximation is shown to be an efficient tool to quantify this effect. An analytical formula for the effective wave number is obtained in one-dimensional acoustic medium and is compared with the Berryman result in the low-frequency limit. Direct numerical calculations show a good agreement with the analytical predictions

  4. Chiral Liquid Crystals: Structures, Phases, Effects

    Directory of Open Access Journals (Sweden)

    Ingo Dierking

    2014-06-01

    Full Text Available The introduction of chirality, i.e., the lack of mirror symmetry, has a profound effect on liquid crystals, not only on the molecular scale but also on the supermolecular scale and phase. I review these effects, which are related to the formation of supermolecular helicity, the occurrence of novel thermodynamic phases, as well as electro-optic effects which can only be observed in chiral liquid crystalline materials. In particular, I will discuss the formation of helical superstructures in cholesteric, Twist Grain Boundary and ferroelectric phases. As examples for the occurrence of novel phases the Blue Phases and Twist Grain Boundary phases are introduced. Chirality related effects are demonstrated through the occurrence of ferroelectricity in both thermotropic as well as lyotropic liquid crystals. Lack of mirror symmetry is also discussed briefly for some biopolymers such as cellulose and DNA, together with its influence on liquid crystalline behavior.

  5. The effect of aging on network structure

    OpenAIRE

    Zhu, Han; Wang, Xin-Ran; Zhu, Jian-Yang

    2003-01-01

    In network evolution, the effect of aging is universal: in scientific collaboration network, scientists have a finite time span of being active; in movie actors network, once popular stars are retiring from stage; devices on the Internet may become outmoded with techniques developing so rapidly. Here we find in citation networks that this effect can be represented by an exponential decay factor, $e^{-\\beta \\tau}$, where $\\tau $ is the node age, while other evolving networks (the Internet for ...

  6. Impact hazard mitigation: understanding the effects of nuclear explosive outputs on comets and asteroids

    Energy Technology Data Exchange (ETDEWEB)

    Clement, Ralph R C [Los Alamos National Laboratory; Plesko, Catherine S [Los Alamos National Laboratory; Bradley, Paul A [Los Alamos National Laboratory; Conlon, Leann M [Los Alamos National Laboratory

    2009-01-01

    The NASA 2007 white paper ''Near-Earth Object Survey and Deflection Analysis of Alternatives'' affirms deflection as the safest and most effective means of potentially hazardous object (PHO) impact prevention. It also calls for further studies of object deflection. In principle, deflection of a PHO may be accomplished by using kinetic impactors, chemical explosives, gravity tractors, solar sails, or nuclear munitions. Of the sudden impulse options, nuclear munitions are by far the most efficient in terms of yield-per-unit-mass launched and are technically mature. However, there are still significant questions about the response of a comet or asteroid to a nuclear burst. Recent and ongoing observational and experimental work is revolutionizing our understanding of the physical and chemical properties of these bodies (e.g ., Ryan (2000) Fujiwara et al. (2006), and Jedicke et al. (2006)). The combination of this improved understanding of small solar-system bodies combined with current state-of-the-art modeling and simulation capabilities, which have also improved dramatically in recent years, allow for a science-based, comprehensive study of PHO mitigation techniques. Here we present an examination of the effects of radiation from a nuclear explosion on potentially hazardous asteroids and comets through Monte Carlo N-Particle code (MCNP) simulation techniques. MCNP is a general-purpose particle transport code commonly used to model neutron, photon, and electron transport for medical physics reactor design and safety, accelerator target and detector design, and a variety of other applications including modeling the propagation of epithermal neutrons through the Martian regolith (Prettyman 2002). It is a massively parallel code that can conduct simulations in 1-3 dimensions, complicated geometries, and with extremely powerful variance reduction techniques. It uses current nuclear cross section data, where available, and fills in the gaps with

  7. Research Plans for Improving Understanding of Effects of Very Low-Frequency Noise of Heavy Lift Rotorcraft

    Science.gov (United States)

    Fidell, Sanford; Horonieff, Richard D.; Schmitz, Fredric H.

    2010-01-01

    This report reviews the English-language technical literature on infrasonic and low-frequency noise effects; identifies the most salient effects of noise produced by a future large civil tiltrotor aircraft on crew, passengers, and communities near landing areas; and recommends research needed to improve understanding of the effects of such noise on passengers, crew, and residents of areas near landing pads.

  8. The contribution of spatial analysis to understanding HIV/TB mortality in children: a structural equation modelling approach

    Directory of Open Access Journals (Sweden)

    Eustasius Musenge

    2013-01-01

    Full Text Available Background: South Africa accounts for more than a sixth of the global population of people infected with HIV and TB, ranking her highest in HIV/TB co-infection worldwide. Remote areas often bear the greatest burden of morbidity and mortality, yet there are spatial differences within rural settings. Objectives: The primary aim was to investigate HIV/TB mortality determinants and their spatial distribution in the rural Agincourt sub-district for children aged 1–5 years in 2004. Our secondary aim was to model how the associated factors were interrelated as either underlying or proximate factors of child mortality using pathway analysis based on a Mosley-Chen conceptual framework. Methods: We conducted a secondary data analysis based on cross-sectional data collected in 2004 from the Agincourt sub-district in rural northeast South Africa. Child HIV/TB death was the outcome measure derived from physician assessed verbal autopsy. Modelling used multiple logit regression models with and without spatial household random effects. Structural equation models were used in modelling the complex relationships between multiple exposures and the outcome (child HIV/TB mortality as relayed on a conceptual framework. Results: Fifty-four of 6,692 children aged 1–5 years died of HIV/TB, from a total of 5,084 households. Maternal death had the greatest effect on child HIV/TB mortality (adjusted odds ratio=4.00; 95% confidence interval=1.01–15.80. A protective effect was found in households with better socio-economic status and when the child was older. Spatial models disclosed that the areas which experienced the greatest child HIV/TB mortality were those without any health facility. Conclusion: Low socio-economic status and maternal deaths impacted indirectly and directly on child mortality, respectively. These factors are major concerns locally and should be used in formulating interventions to reduce child mortality. Spatial prediction maps can guide policy

  9. Understanding effects in reviews of implementation interventions using the Theoretical Domains Framework.

    Science.gov (United States)

    Little, Elizabeth A; Presseau, Justin; Eccles, Martin P

    2015-06-17

    Behavioural theory can be used to better understand the effects of behaviour change interventions targeting healthcare professional behaviour to improve quality of care. However, the explicit use of theory is rarely reported despite interventions inevitably involving at least an implicit idea of what factors to target to implement change. There is a quality of care gap in the post-fracture investigation (bone mineral density (BMD) scanning) and management (bisphosphonate prescription) of patients at risk of osteoporosis. We aimed to use the Theoretical Domains Framework (TDF) within a systematic review of interventions to improve quality of care in post-fracture investigation. Our objectives were to explore which theoretical factors the interventions in the review may have been targeting and how this might be related to the size of the effect on rates of BMD scanning and osteoporosis treatment with bisphosphonate medication. A behavioural scientist and a clinician independently coded TDF domains in intervention and control groups. Quantitative analyses explored the relationship between intervention effect size and total number of domains targeted, and as number of different domains targeted. Nine randomised controlled trials (RCTs) (10 interventions) were analysed. The five theoretical domains most frequently coded as being targeted by the interventions in the review included "memory, attention and decision processes", "knowledge", "environmental context and resources", "social influences" and "beliefs about consequences". Each intervention targeted a combination of at least four of these five domains. Analyses identified an inverse relationship between both number of times and number of different domains coded and the effect size for BMD scanning but not for bisphosphonate prescription, suggesting that the more domains the intervention targeted, the lower the observed effect size. When explicit use of theory to inform interventions is absent, it is possible to

  10. 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…

  11. Effects of Structural Correlations on Electronic Properties

    International Nuclear Information System (INIS)

    Pastawski, H.M.; Weisz, J.F.

    1984-01-01

    A one dimensional alloy model is treated in the nearest neighbour tight binding approximation in which the correlation of the atoms can be adjusted. The correlation can be changed from a situation in which there is a tendency for atoms to alternate to a situation in which the atoms are randomly located, consistent with a fixed concentration c for A c B 1-c . The results show that when there is short range order, at certain energies there is a tendency for localized states and formation of structure induced minimum in the density of states. The results for the ordered case are similar to those of Charge Density Wave (CDW). A smooth transition is carried out between this case and the randomly disordered case which behaves like the Anderson model for uncorrelated disorder. (M.W.O.) [pt

  12. Chemical effects in the mine structure

    International Nuclear Information System (INIS)

    1992-02-01

    The main objective of the workshop was to bring together, and get talking to each other, long-term safety modellers, geochemical modellers and experimenters working in the field of chemical effects, and to give an insight into their respective activity areas and problem constellations. Lectures on the following subjects were given: modelling of chemical effects in long-term safety analysis; influence of brines; corrosion experiments; sorption experiments; actinide chemistry experiments; geochemical modelling; requirements of safety analyses and geochemical modelling. The workshop concluded with a detailed discussion of the subjects raised and of interdisciplinary aspects. (orig./DG) [de

  13. Challenging effective public outreach activities for increasing mutual understanding of nuclear energy

    International Nuclear Information System (INIS)

    Gunji, Ikuko

    2006-01-01

    An outreach activity is two-way communication for communicating information. The public outreach activities of USA and Japan for increasing mutual understanding of nuclear energy, and the effective outreach activities are stated. On USA, many communicators in the member of ANS (American Nuclear Society) play an active part in the outreach activities for the policy makers, educators, students, and stakeholders. NEI (Nuclear Energy Institute, USA) provides people with useful information such as benefits and safety control system of nuclear energy, and it has carried out an attitude survey. FPL (Florida Power and Light Company) selected the communicators by ten evaluation items and they made a group and a clear grasp of the goal, needs, and plans and then communicated residents, and sent out questionnaires. Some examples of the special education program for training the communicators in USA are described. In Japan, JAEA gave lessons of nuclear energy, radiation and disaster prevention at the primary, junior high and high schools, friendly talks with local residents, preparing the teaching materials with residents and training of communicators. (S.Y.)

  14. Understanding the effects of stress and alcohol cues on motivation for alcohol via behavioral economics.

    Science.gov (United States)

    Amlung, Michael; MacKillop, James

    2014-06-01

    Psychological stress and alcohol cues are common antecedents of both ongoing drinking and relapse. One candidate mechanism of risk from these factors is acute increases in craving, but experimental support for this hypothesis is mixed. Furthermore, the combination of stress and cues has been largely unstudied. The current study employed a behavioral economic approach to investigate the combined roles of psychosocial stress and alcohol cues on motivation for alcohol. In a sample of 84 adult heavy drinkers, we examined the effects of an acute laboratory stress induction and an alcohol cue exposure on subjective craving and stress, arousal, and behavioral economic decision making. Primary dependent measures included an intertemporal cross-commodity multiple-choice procedure (ICCMCP), incorporating both price and delay elements, an alcohol purchase task (APT), measuring alcohol demand, and a monetary delay discounting task, measuring intertemporal choice. The stress induction significantly increased stress, craving, and the incentive value of alcohol on the ICCMCP and APT. Stress-related increases in value on the ICCMCP were mediated by increased alcohol demand. Exposure to alcohol cues only significantly affected craving, APT breakpoint, and arousal. Delay discounting was not affected by either stress or cues. These results reveal unique behavioral economic dimensions of motivation for alcohol following acute stress and an alcohol cue exposure. More broadly, as the first application of this approach to understanding the role of stress in drug motivation, these findings support its utility and potential in future applications. Copyright © 2014 by the Research Society on Alcoholism.

  15. Understanding pH and ionic strength effects on aluminum sulfate-induced microalgae flocculation.

    Science.gov (United States)

    Cui, Y; Yuan, W; Cheng, J

    2014-08-01

    The objective of this study was to understand the effect of pH and ionic strength of aluminum sulfate on the flocculation of microalgae. It was found that changing pH and ionic strength influenced algal flocculation by changing the zeta potential of cells, which was described by the classical theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO). For both algal species of Scenedesmus dimorphus and Nannochloropsis oculata, cells with lower total DLVO interaction energy had higher flocculation efficiency, indicating that the DLVO model was qualitatively accurate in predicting the flocculation of the two algae. However, the two algae responded differently to changing pH and ionic strength. The flocculation of N. oculata increased with increasing aluminum sulfate concentration and favored either low (pH 5) or high (pH 10) pH where cells had relatively low negative surface charges. For S. dimorphus, the highest flocculation was achieved at low ionic strength (1 μM) or moderate pH (pH 7.5) where cell surface charges were fully neutralized (zero zeta potential).

  16. Understanding effect of formulation and manufacturing variables on the critical quality attributes of warfarin sodium product.

    Science.gov (United States)

    Rahman, Ziyaur; Korang-Yeboah, Maxwell; Siddiqui, Akhtar; Mohammad, Adil; Khan, Mansoor A

    2015-11-10

    Warfarin sodium (WS) is a narrow therapeutic index drug and its product quality should be thoroughly understood and monitored in order to avoid clinical performance issues. This study was focused on understanding the effect of manufacturing and formulation variables on WS product critical quality attributes (CQAs). Eight formulations were developed with lactose monohydrate (LM) or lactose anhydrous (LA), and were either wet granulated or directly compressed. Formulations were granulated either with ethanol, isopropyl alcohol (IPA) and IPA-water mixture (50:50). Formulations were characterized for IPA, water content, hardness, disintegration time (DT), assay, dissolution and drug physical forms (scanning electron microscopy (SEM), near infrared chemical imaging (NIR-CI), X-ray powder diffraction (XRPD) and solid state nuclear magnetic resonance (ssNMR)), and performed accelerated stability studies at 40°C/75% RH for three days. The DT and dissolution of directly compressed formulations were faster than wet granulated formulations. This was due to phase transformation of crystalline drug into its amorphous form as indicated by SEM, NIR-CI, XRPD and ssNMR data which itself act as a binder. Similarly, LM showed faster disintegration and dissolution than LA containing formulations. Stability results indicated an increase in hardness and DT, and a decrease in dissolution rate and extent. This was due to phase transformation of the drug and consolidation with particles' bonding. In conclusion, the CQAs of WS product were significantly affected by manufacturing and formulation variables. Published by Elsevier B.V.

  17. Understanding Motivations for Abstinence among Adolescent Young Women: Insights into Effective Sexual Risk Reduction Strategies

    Science.gov (United States)

    Long-Middleton, Ellen R.; Burke, Pamela J.; Lawrence, Cheryl A. Cahill; Blanchard, Lauren B.; Amudala, Naomi H.; Rankin, Sally H.

    2012-01-01

    Introduction Pregnancy and sexually transmitted infections pose a significant threat to the health and wellbeing of adolescent young women. Abstinence when practiced provides the most effective means in preventing these problems, yet the perspective of abstinent young women is not well understood. The purpose of the investigation was to characterize female adolescents’ motivations for abstinence. Method As part of a larger, cross-sectional quantitative study investigating predictors of HIV risk reduction behaviors, qualitative responses from study participants who never had intercourse were analyzed in a consensus-based process using content analysis and frequency counts. An urban primary care site in a tertiary care center served as the setting, with adolescent young women ages 15–19 years included in the sample. Results Five broad topic categories emerged from the data that characterized motivations for abstinence in this sample: 1) Personal Readiness, 2) Fear, 3) Beliefs and Values, 4) Partner Worthiness and 5) Lack of Opportunity. Discussion A better understanding of the motivations for abstinence may serve to guide the development of interventions to delay intercourse. PMID:22525893

  18. Magnetocaloric effect across the coupled structural and ...

    Indian Academy of Sciences (India)

    Wintec

    MCE is change in temperature of a magnetic material in adiabatic condition as a result of the alignment of its magnetic spins on exposure to an external magnetic field, the phenomenon which forms the basis for magnetic refrigeration. A large magnetocaloric effect was reported near room tem- perature in Gd and its alloys ...

  19. The Effects of Poverty Simulation, an Experiential Learning Modality, on Students' Understanding of Life in Poverty

    Science.gov (United States)

    Vandsburger, Etty; Duncan-Daston, Rana; Akerson, Emily; Dillon, Tom

    2010-01-01

    This research examines the impact of the Poverty Simulation Project, an experiential learning modality, on students' understanding of life in poverty. A total of 101 students representing 5 undergraduate majors in the College of Health and Human Services completed measures of critical thinking, understanding of others, and the active learning…

  20. Effects of structured versus non-structured learning on achievement and attitudes of fifth graders in a public aquarium

    Science.gov (United States)

    Kafka, Merryl Audrey

    diminishing attitudinal scores. The fact that students' learning-style variations for sociological, design, and perceptual preferences were simultaneously accommodated in this setting may have contributed to the overall positive effects of this structure-based intervention. The diversified teaching resources of the exhibit and the sense of self-empowerment in a student-directed environment may have elevated students' attitudes regardless of their learning-style need for structure. The students' acceptance of a trip sheet that promoted the understanding of science concepts may have contributed to academic success.

  1. Structural Optimization Including Centrifugal and Coriolis Effects

    Science.gov (United States)

    1988-01-01

    the desired frequency changes with excellent accuracy. MSC/ NASTRAN finite element solution sequences were modified to incorporate rotary effects. DMAP ...properties can be altered by a nonlinear change factor. These manipulations may be done by selective use of the MATMOD DMAP module. In the MSC/ NASTRAN ...Examples were carried out using the general purpose software package MSC/ NASTRAN and ADS (Automated Design Synthesis). "I OTIC copy INSpE TE 6

  2. Ionizing radiation effects on silicon test structures

    International Nuclear Information System (INIS)

    Kraner, H.W.; Beuttenmuller, R.; Chen, W.; Kierstead, J.A.; Li, Z.; Zhang, Y.; Dou, L.; Fretwurst, E.; Lindstroem, G.

    1993-12-01

    The effects of 60 Co gamma irradiation on MOSCAPS and special junction diode detectors have been studied. The capacitors were used to ellicit the charge accumulation and anneal in two types of thermally grown oxides representative of those used in routine detector processing. Ion implanted, oxide passivated junction detectors having 0.25 and 1 cm 2 areas and perimeter to area ratios of 1 (a square), 2 and 5 were designed and constructed to amplify the ionizing effects expected to largely affect junction edges through changes in fixed oxide charges. Detectors were exposed to over 4 Mrad and showed clear increases in leakage current in proportion to the junction edge length. Annealing schedules were determined to provide a continuous response to incremental irradiations and subsequent room temperature anneals of leakage current. Besides an increase in gate threshold, little effect on the C(V) response was found. PISCES simulation of the edge fields using different fixed oxide charge revealed regions of very high lateral fields near the junction edges for fixed charges in the 2 x 10 12 /cm 2 range expected from the capacitor studies which could be responsible for the observed leakage currents

  3. Understanding the photoluminescence characteristics of Eu{sup 3+}-doped double-perovskite by electronic structure calculation

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Binita [St. Paul’s Cathedral Mission College, 33/1Raja Rammohan Roy Road, Kolkata 700009 (India); Halder, Saswata; Sinha, T. P. [Department of Physics, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009 (India); Das, Sayantani [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009 (India)

    2016-05-23

    Europium-doped luminescent barium samarium tantalum oxide Ba{sub 2}SmTaO{sub 6} (BST) has been investigated by first-principles calculation, and the crystal structure, electronic structure, and optical properties of pure BST and Eu-doped BST have been examined and compared. Based on the calculated results, the luminescence properties and mechanism of Eu-doped BST has been discussed. In the case of Eu-doped BST, there is an impurity energy band at the Fermi level, which is formed by seven spin up energy levels of Eu and act as the luminescent centre, which is evident from the band structure calculations.

  4. Biological effect of radiation. Basis for understanding the risk of Fukushima nuclear accident

    International Nuclear Information System (INIS)

    Imaoka, Tatsuhiko

    2011-01-01

    The radionuclide release in the Fukushima Nuclear Accident has induced a tremendous anxiety on possible health effects of low dose radiation. When radiation hits a cell in an organism, it may induce DNA damages which, if not repaired properly, lead to either cell death or genetic mutation. If function of the tissue is lost as a result of cell death, various tissue responses including dysfunction of hematopoietic tissues, sterility and skin responses may occur; these responses are not manifested if the radiation dose is low enough. Genetic mutation is considered to occur, albeit at a low frequency, even if the radiation dose is very small. Cancer is a result of genetic mutation and its probability is considered to rise, albeit slightly, if radiation induces a small amount of additional mutations. These assumptions lead to a notion that there is no 'safety dose' below which radiation does not cause any cancer. On the other hand, the study of atomic bomb survivors of Hiroshima and Nagasaki provides the most reliable quantitative information on the relationship between radiation dose and accompanying increase in cancer risk. The analysis so far indicates that cancer risk increases by 0.5-fold, compared to a background level, if a human body is exposed to 1 sievert of radiation; at lower doses, the risk is proportional to the dose, but it is impossible to detect cancer risk associated with 100 milli sievert of exposure because of statistical limitations. Although exposure to atomic bomb radiation occurred in a very little instance, the current situation poses a prolonged (i.e., low dose rate) exposure, probably resulting in still lower cancer risk. Still, since current radiation exposure has no benefit, unlike that in medical situations, it is important to reduce it to a level as low as reasonably achievable. I will explain the biological effect of radiation, including its mechanistic basis and effects on the human body, and wish to help the audience to

  5. Effect of Fiber Reinforcement on the Response of Structural Members

    DEFF Research Database (Denmark)

    Fischer, Gregor; Li, Victor

    2007-01-01

    This paper describes a series of investigations on the effect of fiber reinforcement on the response of structural members in direct tension and flexure under reversed cyclic loading conditions. The design approach of the fiber reinforced cementitious composite is based on fracture mechanics...... and an ultimate tensile strain capacity on the order of several percent. Subsequently, the synergistic effects of composite deformation mechanisms in the ECC and structural members subjected to large shear reversals are identified. Beneficial effects observed in the reinforced ECC structural members as compared...... to conventional reinforced concrete include improved composite integrity, energy dissipation, ductility, and damage tolerance....

  6. Structuring Assignments to Improve Understanding and Presentation Skills: Experiential Learning in the Capstone Strategic Management Team Presentation

    Science.gov (United States)

    Helms, Marilyn M.; Whitesell, Melissa

    2017-01-01

    In the strategic management course, students select, analyze, and present viable future alternatives based on information provided in cases or computer simulations. Rather than understanding the entire process, the student's focus is on the final presentation. Chickering's (1977) research on active learning suggests students learn more effectively…

  7. Assessment of the effects of microbially influenced degradation on a massive concrete structure. Final report, Report 5

    International Nuclear Information System (INIS)

    Rogers, R.D.

    1995-01-01

    There is a need to estimate the effect of environmental conditions on construction materials to be used in the repository at Yucca Mountain. Previous reports from this project have demonstrated that it is important to develop an understanding of microbially influenced degradation (MID) development and its influence on massive concrete structures. Further, it has been shown that the most effective way to obtain quantitative data on the effects of MID on the structural integrity of repository concrete is to study manmade, analog structures known to be susceptible to MID. The cooling tower shell located at the Ohaaki Power Station near Wairakei, New Zealand is such a structure

  8. Assessment of the effects of microbially influenced degradation on a massive concrete structure. Final report, Report 5

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, R.D. [Biodegradation Systems, Inc., Idaho Falls, ID (United States)

    1995-07-08

    There is a need to estimate the effect of environmental conditions on construction materials to be used in the repository at Yucca Mountain. Previous reports from this project have demonstrated that it is important to develop an understanding of microbially influenced degradation (MID) development and its influence on massive concrete structures. Further, it has been shown that the most effective way to obtain quantitative data on the effects of MID on the structural integrity of repository concrete is to study manmade, analog structures known to be susceptible to MID. The cooling tower shell located at the Ohaaki Power Station near Wairakei, New Zealand is such a structure.

  9. Effective operators in nuclear-structure calculations

    International Nuclear Information System (INIS)

    Barrett, Bruce R

    2005-01-01

    A brief review of the history of the use of many-body perturbation theory to determine effective operators for shell-model calculations, i.e., for calculations in truncated model spaces, is given, starting with the ground-breaking work of Arima and Horie for electromagnetic moments. The problems encountered in utilizing this approach are discussed. New methods based on unitary-transformation approaches are introduced and analyzed. The old problems persist, but the new methods allow us to obtain a better insight into the nature of the physics involved in these processes

  10. 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.

  11. Insights into the effect of structure-directing agents on structural ...

    Indian Academy of Sciences (India)

    directing agents) and the cost-effective carbon precursors, such as phloroglucinol and formaldehyde. Selected sur- factants based on .... of structure-directing agent play a crucial role in tuning the geometry of the pore structure while .... ume than the Vulcan XC-72R carbon with an exception of. MCs derived from HTAB and ...

  12. MCTBI: a web server for predicting metal ion effects in RNA structures.

    Science.gov (United States)

    Sun, Li-Zhen; Zhang, Jing-Xiang; Chen, Shi-Jie

    2017-08-01

    Metal ions play critical roles in RNA structure and function. However, web servers and software packages for predicting ion effects in RNA structures are notably scarce. Furthermore, the existing web servers and software packages mainly neglect ion correlation and fluctuation effects, which are potentially important for RNAs. We here report a new web server, the MCTBI server (http://rna.physics.missouri.edu/MCTBI), for the prediction of ion effects for RNA structures. This server is based on the recently developed MCTBI, a model that can account for ion correlation and fluctuation effects for nucleic acid structures and can provide improved predictions for the effects of metal ions, especially for multivalent ions such as Mg 2+ effects, as shown by extensive theory-experiment test results. The MCTBI web server predicts metal ion binding fractions, the most probable bound ion distribution, the electrostatic free energy of the system, and the free energy components. The results provide mechanistic insights into the role of metal ions in RNA structure formation and folding stability, which is important for understanding RNA functions and the rational design of RNA structures. © 2017 Sun et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  13. Current steering effect of GaN nanoporous structure

    International Nuclear Information System (INIS)

    Lin, Chia-Feng; Wang, Jing-Hao; Cheng, Po-Fu; Tseng, Wang-Po; Fan, Feng-Hsu; Wu, Kaun-Chun; Lee, Wen-Che; Han, Jung

    2014-01-01

    Current steering effect of InGaN light emitting diode (LED) structure was demonstrated by forming a high resistivity GaN nanoporous structure. Disk-array patterns with current-injection bridge structures were fabricated on InGaN LED devices through a focused ion beam (FIB) system. GaN nanoporous structure was formed around the FIB-drilled holes through a electrochemical (EC) wet-etching process on a n-type GaN:Si layer under the InGaN active layer. High emission intensity and small peak wavelength blueshift phenomenon of the electroluminescence spectra were observed in the EC-treated region compared with the non-treated region. The branch-like nanoporous structure was formed along the lateral etched direction to steer the injection current in 5 μm-width bridge structures. In the FIB-drilled hole structure, high light emission intensity of the central-disk region was observed by enlarging the bridge width to 10 μm, with a 5 μm EC-treated width, that reduced the current steering effect and increased the light scattering effect on the nanoporous structure. The EC-treated GaN:Si nanoporous structure acted as a high light scattering structure and a current steering structure that has potential on the current confinement for vertical cavity surface emitting laser applications. - Highlights: • High resistivity nanoporous-GaN formed in InGaN LED through electrochemical process. • Branch-like nanoporous in 5 μm-width bridge structure can steer the injection current. • Nanoporous GaN acted as s light scattering and current steering structures in InGaN LED

  14. Understanding the effects of fire management practices on forest health: implications for weeds and vegetation structure

    Science.gov (United States)

    Anne E. Black; Peter Landres

    2012-01-01

    Current fire policy to restore ecosystem function and resiliency and reduce buildup of hazardous fuels implies a larger future role for fire (both natural and human ignitions) (USDA Forest Service and U.S. Department of the Interior 2000). Yet some fire management (such as building fire line, spike camps, or helispots) potentially causes both short- and longterm...

  15. Understanding the peculiarities of the piezoelectric effect in macro-porous BaTiO3.

    Science.gov (United States)

    Roscow, James I; Topolov, Vitaly Yu; Bowen, Christopher R; Taylor, John; Panich, Anatoly E

    2016-01-01

    This work demonstrates the potential of porous BaTiO 3 for piezoelectric sensor and energy-harvesting applications by manufacture of materials, detailed characterisation and application of new models. Ferroelectric macro-porous BaTiO 3 ceramics for piezoelectric applications are manufactured for a range of relative densities, α  = 0.30-0.95, using the burned out polymer spheres method. The piezoelectric activity and relevant parameters for specific applications are interpreted by developing two models: a model of a 3-0 composite and a 'composite in composite' model. The appropriate ranges of relative density for the application of these models to accurately predict piezoelectric properties are examined. The two models are extended to take into account the effect of 90° domain-wall mobility within ceramic grains on the piezoelectric coefficients [Formula: see text]. It is shown that porous ferroelectrics provide a novel route to form materials with large piezoelectric anisotropy [Formula: see text] at 0.20 ≤ α ≤ 0.45 and achieve a high squared figure of merit [Formula: see text] [Formula: see text]. The modelling approach allows a detailed analysis of the relationships between the properties of the monolithic and porous materials for the design of porous structures with optimum properties.

  16. Understanding the effect of flower extracts on the photoconducting properties of nanostructured TiO2.

    Science.gov (United States)

    Ansari, S G; Bhayana, Laitka; Umar, Ahmad; Al-Hajry, A; Al-Deyab, Salem S; Ansari, Z A

    2012-10-01

    Here we report an easy method to improve the optoelectronic properties of commercially available TiO2 nanopowder using extracts of various flowers viz. Calendula Orange (CO), Calendula Yellow (CY), Dahlia Violet (DV), Dahlia Yellow (DY), Rabbit flower (RF), Sweet Poppy (SP), Sweet Williams (SW) and their Mixed Extracts (ME). Various analysis techniques such as UV-Vis, FTIR, FESEM, XRD, and Raman spectroscopy were used to characterize for elemental, structural and morphological properties of the unmixed/mixed TiO2 nanopowder. TiO2 nanopowder was also calcined at 550 degrees C. Thick films of the these unmixed/mixed powder were printed, using conventional screen printing method, on fluorine doped tin oxide (FTO) substrate with organic binders and dried at 45 degrees C. The photoconducting properties are investigated as a function of wavelength from ultra-violet (UV) to infra-red (IR) region at a constant illumination intensity. Photocurrent gradually decreases when irradiated from UV to IR region. In case of unmixed and uncalcined TiO2, conductance decreased continuously whereas when extracts are added, a flat region of conductance is observed. The overall effect of extracts (colour pigments) is seen as an increase in the photoconductance. Highest photoconductance is observed in case of DY flower extract. Anthocyanins, present in flowers are known to have antioxidative properties and hence can contribute in photoconduction by reducing the surface adsorbed oxygen. This investigation indicates the potential use of flower extracts for dye sensitized solar cell (DSSC).

  17. Understanding effects of fire suppression, fuels treatment, and wildfire on bird communities in the Klamath-Siskiyou ecoregion

    Science.gov (United States)

    John D. Alexander; C. John Ralph; Bill Hogoboom; Nathaniel E. Seavy; Stewart Janes

    2004-01-01

    Although fire management is increasingly recognized as an important component of conservation in Klamath-Siskiyou ecosystems, empirical evidence on the ecological effects of fire in this region is limited. Here we describe a conceptual model as a framework for understanding the effects of fire and fire management on bird abundance. This model identifies three major...

  18. 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.

  19. Understanding the effect of watershed characteristic on the runoff using SCS curve number

    Science.gov (United States)

    Damayanti, Frieta; Schneider, Karl

    2015-04-01

    Runoff modeling is a key component in watershed management. The temporal course and amount of runoff is a complex function of a multitude of parameters such as climate, soil, topography, land use, and water management. Against the background of the current rapid environmental change, which is due to both i) man-made changes (e.g. urban development, land use change, water management) as well as ii) changes in the natural systems (e.g. climate change), understanding and predicting the impacts of these changes upon the runoff is very important and affects the wellbeing of many people living in the watershed. A main tool for predictions is hydrologic models. Particularly process based models are the method of choice to assess the impact of land use and climate change. However, many regions which experience large changes in the watersheds can be described as rather data poor, which limits the applicability of such models. This is particularly also true for the Telomoyo Watershed (545 km2) which is located in southern part of Central Java province. The average annual rainfall of the study area reaches 2971 mm. Irrigated paddy field are the dominating land use (35%), followed by built-up area and dry land agriculture. The only available soil map is the FAO soil digital map of the world, which provides rather general soil information. A field survey accompanied by a lab analysis 65 soil samples of was carried out to provide more detailed soil texture information. The soil texture map is a key input in the SCS method to define hydrological soil groups. In the frame of our study on 'Integrated Analysis on Flood Risk of Telomoyo Watershed in Response to the Climate and Land Use Change' funded by the German Academic Exchange service (DAAD) we analyzed the sensitivity of the modeled runoff upon the choice of the method to estimate the CN values using the SCS-CN method. The goal of this study is to analyze the impact of different data sources on the curve numbers and the

  20. A framework for understanding semi-permeable barrier effects on migratory ungulates

    Science.gov (United States)

    Sawyer, Hall; Kauffman, Matthew J.; Middleton, Arthur D.; Morrison, Thomas A.; Nielson, Ryan M.; Wyckoff, Teal B.

    2013-01-01

    1. Impermeable barriers to migration can greatly constrain the set of possible routes and ranges used by migrating animals. For ungulates, however, many forms of development are semi-permeable, and making informed management decisions about their potential impacts to the persistence of migration routes is difficult because our knowledge of how semi-permeable barriers affect migratory behaviour and function is limited. 2. Here, we propose a general framework to advance the understanding of barrier effects on ungulate migration by emphasizing the need to (i) quantify potential barriers in terms that allow behavioural thresholds to be considered, (ii) identify and measure behavioural responses to semi-permeable barriers and (iii) consider the functional attributes of the migratory landscape (e.g. stopovers) and how the benefits of migration might be reduced by behavioural changes. 3. We used global position system (GPS) data collected from two subpopulations of mule deer Odocoileus hemionus to evaluate how different levels of gas development influenced migratory behaviour, including movement rates and stopover use at the individual level, and intensity of use and width of migration route at the population level. We then characterized the functional landscape of migration routes as either stopover habitat or movement corridors and examined how the observed behavioural changes affected the functionality of the migration route in terms of stopover use. 4. We found migratory behaviour to vary with development intensity. Our results suggest that mule deer can migrate through moderate levels of development without any noticeable effects on migratory behaviour. However, in areas with more intensive development, animals often detoured from established routes, increased their rate of movement and reduced stopover use, while the overall use and width of migration routes decreased. 5. Synthesis and applications. In contrast to impermeable barriers that impede animal movement

  1. Proximity effect in normal metal-multiband superconductor hybrid structures

    NARCIS (Netherlands)

    Brinkman, Alexander; Golubov, Alexandre Avraamovitch; Kupriyanov, M. Yu

    2004-01-01

    A theory of the proximity effect in normal metal¿multiband superconductor hybrid structures is formulated within the quasiclassical Green's function formalism. The quasiclassical boundary conditions for multiband hybrid structures are derived in the dirty limit. It is shown that the existence of

  2. Bureaucratic Structure, Organizational Processes, and Three Dimensions of School Effectiveness.

    Science.gov (United States)

    Miskel, Cecil; And Others

    The purpose of this study was to test the hypotheses that schools with more participative processes and less structure have higher levels of perceived organizational effectiveness, teacher job satisfaction, and student achievement than schools with less participative climates and more structure. A sample of 114 school units and 1,632 teachers…

  3. CREATING EFFECTIVE MODELS OF VERTICAL INTEGRATED STRUCTURES IN UKRAINE

    Directory of Open Access Journals (Sweden)

    D. V. Koliesnikov

    2011-01-01

    Full Text Available The results of scientific research aimed at development of methodology-theoretical mechanisms of building the effective models of vertically-integrated structures are presented. A presence of vertically-integrated structures on natural-monopolistic markets at private and governmental sectors of economy and priority directions of integration are given.

  4. An effective pair potential for liquid semiconductor, Se: Structure and ...

    Indian Academy of Sciences (India)

    The effective pair potential of liquid semiconductor Se is extracted from its experimental structure factor data using an accurate liquid state theory and this shows important basic features. A model potential incorporating the basic features of the structure factor extracted potential is suggested. This model potential is then used ...

  5. Integral representation for structure functions and target mass effects

    International Nuclear Information System (INIS)

    Solovtsov, I.L.

    2000-01-01

    A method of studying target mass effects based on the Jost-Lehmann-Dyson integral representation for structure functions of the inelastic lepton-hadron scattering is developed; it accumulates general principles of local quantum field theory. It is shown that the expression obtained for the structure function that depends on the target mass has a correct spectral property

  6. Effects of thickness on electronic structure of titanium thin films

    Indian Academy of Sciences (India)

    Effects of thickness on the electronic structure of e-beam evaporated thin titanium films were studied using near-edge X-ray absorption fine structure (NEXAFS) technique at titanium 2,3 edge in total electron yield (TEY) mode and transmission yield mode. Thickness dependence of 2,3 branching ratio (BR) of titanium was ...

  7. Effects of dimethyl sulfoxide on the hydrogen bonding structure

    Indian Academy of Sciences (India)

    Effects of dimethyl-sulfoxide (DMSO) on the hydrogen bonding structure and dynamics in aqueousN-methylacetamide (NMA) solution are investigated by classical molecular dynamics simulations. Themodifications of structure and interaction between water and NMA in presence of DMSO molecules are calculatedby ...

  8. Effect of urbanization on the thermal structure in the atmosphere

    Science.gov (United States)

    R. Viskanta; R. O. Johnson; R. W., Jr. Bergstrom

    1977-01-01

    An unsteady two-dimensional transport model was used to study the short-term effects of urbanization and air pollution on the thermal structure in the urban atmosphere. A number of simulations for summer conditions representing the city of St. Louis were performed. The diurnal variation of the surface temperature and thermal structure are presented and the influences...

  9. Effects of thickness on electronic structure of titanium thin films

    Indian Academy of Sciences (India)

    Effects of thickness on the electronic structure of e-beam evaporated thin titanium films were studied using near-edge X-ray absorption ... become a powerful experimental technique to get electronic structural information of elements or .... the Stanford Synchrotron Radiation Laboratory (SSRL). The beamline 8·2 is a bending ...

  10. Effects of irradiation on structural properties of crystalline ceramics

    International Nuclear Information System (INIS)

    Clinard, F.W. Jr.; Hurley, G.F.

    1979-01-01

    Stability of crystalline ceramic nuclear waste may be degraded by self-irradiation damage. Changes in density, strength, thermal conductivity, and lattice structure are of concern. Structural damage of ceramics under various radiation conditions is discussed and related to possible effects in nuclear waste

  11. Effects of irradiation on structural properties of crystalline ceramics

    International Nuclear Information System (INIS)

    Clinard, F.W. Jr.; Hurley, G.F.

    1979-01-01

    Stability of crystalline ceramic nuclear waste may be degraded by self-irradiation damage. Changes in density, strength, thermal conductivity, and lattice structure are of concern. In this paper, structural damage of ceramics under various radiation conditions is discussed and related to possible effects in nuclear waste

  12. Simulating the effect of alcohol on the structure of a membrane.

    Science.gov (United States)

    Kranenburg, Marieke; Smit, Berend

    2004-06-18

    Adsorption of alcohol molecules or other small amphiphilic molecules in the cell membrane can induce significant changes in the structure of the membrane. To understand the molecular mechanisms underlying these structural changes, we developed a mesoscopic membrane model. Molecular simulations on this model nicely reproduce the experimental phase diagrams. We find that alcohol can induce an interdigitated structure in which the normal bilayer structure changes into a monolayer in which the alcohol molecules screen the hydrophobic tails from the water phase. We compute the effect of the chain length of the alcohol on the phase behaviour of the membrane. At low concentrations of alcohol, the membrane has domains of the interdigitated phase that are in coexistence with the normal membrane phase. We use our model to clarify some of the experimental questions related to the structure of the interdigitated phase and put forward a simple model that explains the alcohol chain length dependence of the stability of this interdigitated phase.

  13. Effects of material disintegration on structural performance

    International Nuclear Information System (INIS)

    Leckie, F.A.

    1975-01-01

    Using a state variable approach it will be shown how the results of appropriately chosen tests can be used to develop constitutive equations which describe the effects of creep deterioration on the deformation of metals operating at elevated temperatures. In this way a systematic phenomenological approach can be developed. Using this approach in conjunction with the results of multiaxial stress tests a set of constitutive equations are proposed which define the creep deformation rates in terms of applied stress and a material state variable, referred to as damage. In spite of the fact that the equations have been comstructed using purely phenomenological procedures, it is possible, nevertheless to demonstrate the physical interpretation of the damage state. Using the constitutive equations in conjunction with the virtual work relationships it is possible to obtain bounds on the rupture life of components subjected to both constant and cyclic loading. It is found convenient to express the results in terms of a so-called representative rupture stress, so that the uniaxial creep rupture curves can be used directly, thereby avoiding complex curve fitting procedures. The bounds are used to predict the rupture life of a number of components subjected to constant and variable load and comparison is made with experimental results. The components tested are: plane stress plates with holes and slots, subjected to uniaxial stress; plane stress plates with holes and slots subjected to biaxial tension; cylindrical bars with round notches; reinforced shell intersections subjected to internal pressure

  14. Structural Response to Blast Loading: The Effects of Corrosion on Reinforced Concrete Structures

    Directory of Open Access Journals (Sweden)

    Hakan Yalciner

    2014-01-01

    Full Text Available Structural blast design has become a necessary part of the design with increasing terrorist attacks. Terrorist attacks are not the one to make the structures important against blast loading where other explosions such as high gas explosions also take an important place in structural safety. The main objective of this study was to verify the structural performance levels under the impact of different blast loading scenarios. The blast loads were represented by using triangular pulse for single degree of freedom system. The effect of blast load on both corroded and uncorroded reinforced concrete buildings was examined for different explosion distances. Modified plastic hinge properties were used to ensure the effects of corrosion. The results indicated that explosion distance and concrete strength were key parameters to define the performance of the structures against blast loading.

  15. Effect of groundwater on soil-structure interaction

    International Nuclear Information System (INIS)

    Xu, J.; Bandyopadhyay, K.K.; Kassir, M.K.

    1995-01-01

    This paper presents results of a parametric study performed to investigate the effect of pore water in saturated soils on the response of nuclear containment structures to seismic motions. The technique employed uses frequency domain algorithm which incorporates impedances for both dry and saturated soils into an SSI model. A frequency domain time history analysis is carried out using the computer code CARES for a typical PWR containment structure. Structural responses presented in terms of floor response spectra indicate that considering the presence of the pore water in soils could benefit the design of massive nuclear containment structures

  16. Incorporating Modeling and Simulations in Undergraduate Biophysical Chemistry Course to Promote Understanding of Structure-Dynamics-Function Relationships in Proteins

    Science.gov (United States)

    Hati, Sanchita; Bhattacharyya, Sudeep

    2016-01-01

    A project-based biophysical chemistry laboratory course, which is offered to the biochemistry and molecular biology majors in their senior year, is described. In this course, the classroom study of the structure-function of biomolecules is integrated with the discovery-guided laboratory study of these molecules using computer modeling and…

  17. Understanding the effect of n-type and p-type doping in the channel ...

    Indian Academy of Sciences (India)

    channel device remains unsaturated. On comparing figures 2–8, we observe larger variations in on and off-currents in n-type-doped structure in compari- son with p-type-doped and undoped channel structures. It is also possible to obtain the important saturation characteris- tics on introducing n-type-doping near drain side, ...

  18. Team Leader Structuring for Team Effectiveness and Team Learning in Command-and-Control Teams.

    Science.gov (United States)

    van der Haar, Selma; Koeslag-Kreunen, Mieke; Euwe, Eline; Segers, Mien

    2017-04-01

    Due to their crucial and highly consequential task, it is of utmost importance to understand the levers leading to effectiveness of multidisciplinary emergency management command-and-control (EMCC) teams. We argue that the formal EMCC team leader needs to initiate structure in the team meetings to support organizing the work as well as facilitate team learning, especially the team learning process of constructive conflict. In a sample of 17 EMCC teams performing a realistic EMCC exercise, including one or two team meetings (28 in sum), we coded the team leader's verbal structuring behaviors (1,704 events), rated constructive conflict by external experts, and rated team effectiveness by field experts. Results show that leaders of effective teams use structuring behaviors more often (except asking procedural questions) but decreasingly over time. They support constructive conflict by clarifying and by making summaries that conclude in a command or decision in a decreasing frequency over time.

  19. Effects of micro- and nano-structures on the self-cleaning behaviour of lotus leaves

    Science.gov (United States)

    Cheng, Y. T.; Rodak, D. E.; Wong, C. A.; Hayden, C. A.

    2006-03-01

    When rain falls on lotus leaves water beads up with a high contact angle. The water drops promptly roll off the leaves, collecting dirt along the way. This self-cleaning ability or lotus effect has, in recent years, stimulated much research effort worldwide for a variety of applications ranging from self-cleaning window glasses, paints, and fabrics to low friction surfaces. What are the mechanisms giving rise to the lotus effect? Although chemical composition and surface structure are believed important, a systematic experimental investigation of their effects is still lacking. By altering the surface structure of the leaves while keeping their chemical composition approximately the same, we report in this study the influence of micro- and nano-scale structures on the wetting behaviour of lotus leaves. The findings of this work may help design self-cleaning surfaces and improve our understanding of wetting mechanisms.

  20. Team Leader Structuring for Team Effectiveness and Team Learning in Command-and-Control Teams

    Science.gov (United States)

    van der Haar, Selma; Koeslag-Kreunen, Mieke; Euwe, Eline; Segers, Mien

    2017-01-01

    Due to their crucial and highly consequential task, it is of utmost importance to understand the levers leading to effectiveness of multidisciplinary emergency management command-and-control (EMCC) teams. We argue that the formal EMCC team leader needs to initiate structure in the team meetings to support organizing the work as well as facilitate team learning, especially the team learning process of constructive conflict. In a sample of 17 EMCC teams performing a realistic EMCC exercise, including one or two team meetings (28 in sum), we coded the team leader’s verbal structuring behaviors (1,704 events), rated constructive conflict by external experts, and rated team effectiveness by field experts. Results show that leaders of effective teams use structuring behaviors more often (except asking procedural questions) but decreasingly over time. They support constructive conflict by clarifying and by making summaries that conclude in a command or decision in a decreasing frequency over time. PMID:28490856

  1. Coparticipation as Assumption of Effectiveness of Structural Injunctions Preliminarily Granted

    Directory of Open Access Journals (Sweden)

    Vanessa Sousa Vieira

    2016-10-01

    Full Text Available Unenforceable judgments are ineffective. However during the daytime, law operators are challenged to find ways to comply with court orders. In the case of the implementation of structural measures, this challenge is gigantic. The Democratic Constitutional process requires active participation of all those involved in the construction of the provision, because the effectiveness of the court decision, especially one that implements structural measures, is closely linked to reimbursement of all procedural subjects. It is argued, therefore, that the structural measure preliminary approval should be preceded by hearing the opposing party, to allow the delivery of effective decisions.

  2. Numerical calculations of effective elastic properties of two cellular structures

    International Nuclear Information System (INIS)

    Tuncer, Enis

    2005-01-01

    Young's moduli of regular two-dimensional truss-like and eye-shaped structures are simulated using the finite element method. The structures are idealizations of soft polymeric materials used in ferro-electret applications. In the simulations, the length scales of the smallest representative units are varied, which changes the dimensions of the cell walls in the structures. A power-law expression with a quadratic as the exponent term is proposed for the effective Young's moduli of the systems as a function of the solid volume fraction. The data are divided into three regions with respect to the volume fraction: low, intermediate and high. The parameters of the proposed power-law expression in each region are later represented as a function of the structural parameters, the unit-cell dimensions. The expression presented can be used to predict a structure/property relationship in materials with similar cellular structures. The contribution of the cell-wall thickness to the elastic properties becomes significant at concentrations >0.15. The cell-wall thickness is the most significant factor in predicting the effective Young's modulus of regular cellular structures at high volume fractions of solid. At lower concentrations of solid, the eye-shaped structure yields a lower Young's modulus than a truss-like structure with similar anisotropy. Comparison of the numerical results with those of experimental data for poly(propylene) show good agreement regarding the influence of cell-wall thickness on elastic properties of thin cellular films

  3. Effect of care management program structure on implementation: a normalization process theory analysis

    OpenAIRE

    Holtrop, Jodi Summers; Potworowski, Georges; Fitzpatrick, Laurie; Kowalk, Amy; Green, Lee A.

    2016-01-01

    Background Care management in primary care can be effective in helping patients with chronic disease improve their health status, however, primary care practices are often challenged with implementation. Further, there are different ways to structure care management that may make implementation more or less successful. Normalization process theory (NPT) provides a means of understanding how a new complex intervention can become routine (normalized) in practice. In this study, we used NPT to u...

  4. Understanding the Effects of Lower Boundary Conditions and Eddy Diffusion on the Ionosphere-Thermosphere System

    Science.gov (United States)

    Malhotra, G.; Ridley, A. J.; Marsh, D. R.; Wu, C.; Paxton, L. J.

    2017-12-01

    The exchange of energy between lower atmospheric regions with the ionosphere-thermosphere (IT) system is not well understood. A number of studies have observed day-to-day and seasonal variabilities in the difference between data and model output of various IT parameters. It is widely speculated that the forcing from the lower atmosphere, variability in weather systems and gravity waves that propagate upward from troposphere into the upper mesosphere and lower thermosphere (MLT) may be responsible for these spatial and temporal variations in the IT region, but their exact nature is unknown. These variabilities can be interpreted in two ways: variations in state (density, temperature, wind) of the upper mesosphere or spatial and temporal changes in the small-scale mixing, or Eddy diffusion that is parameterized within the model.In this study, firstly, we analyze the sensitivity of the thermospheric and ionospheric states - neutral densities, O/N2, total electron content (TEC), peak electron density, and peak electron height - to various lower boundary conditions in the Global Ionosphere Thermosphere Model (GITM). We use WACCM-X and GSWM to drive the lower atmospheric boundary in GITM at 100 km, and compare the results with the current MSIS-driven version of GITM, analyzing which of these simulations match the measurements from GOCE, GUVI, CHAMP, and GPS-derived TEC best. Secondly, we analyze the effect of eddy diffusion in the IT system. The turbulence due to eddy mixing cannot be directly measured and it is a challenge to completely characterize its linear and non-linear effects from other influences, since the eddy diffusion both influences the composition through direct mixing and the temperature structure due to turbulent conduction changes. In this study we input latitudinal and seasonal profiles of eddy diffusion into GITM and then analyze the changes in the thermospheric and ionospheric parameters. These profiles will be derived from both WACC-X simulations

  5. 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.

  6. The Effects of Case-Based Instruction on Undergraduate Biology Students' Understanding of the Nature of Science

    Science.gov (United States)

    Burniston, Amy Lucinda

    Undergraduate science education is currently seeing a dramatic pedagogical push towards teaching the philosophies underpinning science as well as an increase in strategies that employ active learning. Many active learning strategies stem from constructivist ideals and have been shown to affect a student's understanding of how science operates and its impact on society- commonly referred to as the nature of science (NOS). One particular constructivist teaching strategy, case-based instruction (CBI), has been recommended by researchers and science education reformists as an effective instructional strategy for teaching NOS. Furthermore, when coupled with explicit-reflective instruction, CBI has been found to significantly increasing understanding of NOS in elementary and secondary students. However, few studies aimed their research on CBI and NOS towards higher education. Thus, this study uses a quasi-experimental, nonequivalent group design to study the effects of CBI on undergraduate science students understandings of NOS. Undergraduate biology student's understanding of NOS were assessed using the Views of Science Education (VOSE) instrument pre and post CBI intervention in Cellular and Molecular Biology and Human Anatomy and Physiology II. Data analysis indicated statistically significant differences between students NOS scores in experimental versus control sections for both courses, with experimental groups obtaining higher posttest scores. The results of this study indicate that undergraduate male and female students have similarly poor understandings of NOS and the use of historical case based instruction can be used as a means to increase undergraduate understanding of NOS.

  7. The Effects of Structural Parameter Variation on Cable Force of Fast Cable-Net Structure

    Directory of Open Access Journals (Sweden)

    Qiming Wang

    2014-02-01

    Full Text Available Five-hundred-meter aperture spherical radio telescope (FAST is supported by a cable-net structure, which enables its surface to form a real-time paraboloid by active control. FAST project is currently in the construction and implementation stage. However, there are always a considerable amount of errors that existed in practice which may result in the deviation of the structure from its ideal model or design. Therefore, structural parameter sensitivity analysis was discussed, which is indispensable. However, such deformation operation would lead to about 500 MPa of fatigue stress variation amplitude in the cable-net structure. Optimized deformation strategy is proposed to release the fatigue stress of the cable-net structure, which would be of advantage to improve the reliability of the cable-net structure. In the paper, the variation ranges of structural parameters were rationally determined. Based on local sensitivity analysis and global sensitivity analysis method, finite element model was used to study the effect of different structural parameters on the static behavior. It can be concluded that the effect of several key design parameters such as the cutting length and the elastic modulus of cable on the cable force is significant. The global sensitivity analysis indicates that the cable force range of the cable-net is −19% to 27%.

  8. Jupiter internal structure: the effect of different equations of state

    Science.gov (United States)

    Miguel, Y.; Guillot, T.; Fayon, L.

    2016-12-01

    Context. Heavy elements, even though they are a smaller constituent, are crucial to understand the formation history of Jupiter. Interior models are used to determine the amount of heavy elements in the interior of Jupiter, but this range is still subject to degeneracies because of the uncertainties in the equations of state. Aims: Before Juno mission data arrive, we present optimized calculations for Jupiter that explore the effect of different model parameters on the determination of the core and the mass of heavy elements of Jupiter. We compare recently published equations of state. Methods: The interior model of Jupiter was calculated from the equations of hydrostatic equilibrium, mass, and energy conservation, and energy transport. The mass of the core and heavy elements was adjusted to match the observed radius and gravitational moments of Jupiter. Results: We show that the determination of the interior structure of Jupiter is tied to the estimation of its gravitational moments and the accuracy of equations of state of hydrogen, helium, and heavy elements. Locating the region where helium rain occurs and defining its timescale is important to determine the distribution of heavy elements and helium in the interior of Jupiter. We show that the differences found when modeling the interior of Jupiter with recent EOS are more likely due to differences in the internal energy and entropy calculation. The consequent changes in the thermal profile lead to different estimates of the mass of the core and heavy elements, which explains differences in recently published interior models of Jupiter. Conclusions: Our results help clarify the reasons for the differences found in interior models of Jupiter and will help interpreting upcoming Juno data. Full appendix tables are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/596/A114

  9. Understanding the evolutionary structural variability and target specificity of tick salivary Kunitz peptides using next generation transcriptome data

    Czech Academy of Sciences Publication Activity Database

    Schwarz, Alexandra; Cabezas Cruz, Alejandro; Kopecký, Jan; Valdés, James J.

    2014-01-01

    Roč. 14, JAN 2014 (2014), s. 4 ISSN 1471-2148 R&D Projects: GA ČR GPP302/11/P798; GA MŠk LH12002; GA ČR GAP302/12/2208; GA MŠk(CZ) EE2.3.30.0032 Institutional support: RVO:60077344 Keywords : Red Queen hypothesis * tick saliva * Kunitz-domain proteins * cysteine motif * structural bioinformatics Subject RIV: EC - Immunology Impact factor: 3.368, year: 2014

  10. In Silico Structure Prediction of Human Fatty Acid Synthase–Dehydratase: A Plausible Model for Understanding Active Site Interactions

    OpenAIRE

    Arun John; Vetrivel Umashankar; A. Samdani; Manoharan Sangeetha; Subramanian Krishnakumar; Perinkulam Ravi Deepa

    2016-01-01

    Fatty acid synthase (FASN, UniProt ID: P49327) is a multienzyme dimer complex that plays a critical role in lipogenesis. Consequently, this lipogenic enzyme has gained tremendous biomedical importance. The role of FASN and its inhibition is being extensively researched in several clinical conditions, such as cancers, obesity, and diabetes. X-ray crystallographic structures of some of its domains, such as ?-ketoacyl synthase, acetyl transacylase, malonyl transacylase, enoyl reductase, ?-ketoac...

  11. Progress in Understanding the Impacts of 3-D Cloud Structure on MODIS Cloud Property Retrievals for Marine Boundary Layer Clouds

    Science.gov (United States)

    Zhang, Zhibo; Werner, Frank; Miller, Daniel; Platnick, Steven; Ackerman, Andrew; DiGirolamo, Larry; Meyer, Kerry; Marshak, Alexander; Wind, Galina; Zhao, Guangyu

    2016-01-01

    Theory: A novel framework based on 2-D Tayler expansion for quantifying the uncertainty in MODIS retrievals caused by sub-pixel reflectance inhomogeneity. (Zhang et al. 2016). How cloud vertical structure influences MODIS LWP retrievals. (Miller et al. 2016). Observation: Analysis of failed MODIS cloud property retrievals. (Cho et al. 2015). Cloud property retrievals from 15m resolution ASTER observations. (Werner et al. 2016). Modeling: LES-Satellite observation simulator (Zhang et al. 2012, Miller et al. 2016).

  12. Toward understanding phosphoseryl-tRNACys formation: the crystal structure of Methanococcus maripaludis phosphoseryl-tRNA synthetase.

    Science.gov (United States)

    Kamtekar, Satwik; Hohn, Michael J; Park, Hee-Sung; Schnitzbauer, Michael; Sauerwald, Anselm; Söll, Dieter; Steitz, Thomas A

    2007-02-20

    A number of archaeal organisms generate Cys-tRNA(Cys) in a two-step pathway, first charging phosphoserine (Sep) onto tRNA(Cys) and subsequently converting it to Cys-tRNA(Cys). We have determined, at 3.2-A resolution, the structure of the Methanococcus maripaludis phosphoseryl-tRNA synthetase (SepRS), which catalyzes the first step of this pathway. The structure shows that SepRS is a class II, alpha(4) synthetase whose quaternary structure arrangement of subunits closely resembles that of the heterotetrameric (alphabeta)(2) phenylalanyl-tRNA synthetase (PheRS). Homology modeling of a tRNA complex indicates that, in contrast to PheRS, a single monomer in the SepRS tetramer may recognize both the acceptor terminus and anticodon of a tRNA substrate. Using a complex with tungstate as a marker for the position of the phosphate moiety of Sep, we suggest that SepRS and PheRS bind their respective amino acid substrates in dissimilar orientations by using different residues.

  13. Toward Understanding Phosphoseryl-tRNA Cys Formation: The Crystal Structure of Methanococcus maripaludis Phosphoseryl-tRNA Synthetase

    Energy Technology Data Exchange (ETDEWEB)

    Kamtekar ,S.; Hohn, M.; Park, h.; Schnitzbauer, M.; Sauerwald, A.; Soll, D.; Steitz, T.

    2007-01-01

    A number of archaeal organisms generate Cys-tRNA{sup Cys} in a two-step pathway, first charging phosphoserine (Sep) onto tRNA{sup Cys} and subsequently converting it to Cys-tRNA{sup Cys}. We have determined, at 3.2-{angstrom} resolution, the structure of the Methanococcus maripaludis phosphoseryl-tRNA synthetase (SepRS), which catalyzes the first step of this pathway. The structure shows that SepRS is a class II, {alpha}{sub 4} synthetase whose quaternary structure arrangement of subunits closely resembles that of the heterotetrameric ({alpha}{beta}){sub 2} phenylalanyl-tRNA synthetase (PheRS). Homology modeling of a tRNA complex indicates that, in contrast to PheRS, a single monomer in the SepRS tetramer may recognize both the acceptor terminus and anticodon of a tRNA substrate. Using a complex with tungstate as a marker for the position of the phosphate moiety of Sep, we suggest that SepRS and PheRS bind their respective amino acid substrates in dissimilar orientations by using different residues.

  14. WHAT DO WE UNDERSTAND FROM THE TERMS DEEP STRUCTURE AND SURFACE STRUCTURE? DERİN YAPI VE YÜZEY YAPI KAVRAMLARINDAN NE ANLIYORUZ?

    Directory of Open Access Journals (Sweden)

    Kerim DEMİRCİ

    2010-10-01

    Full Text Available According to the theory developed mostly by Port Royal school in the 17th century and later on formulated by Noam Chomsky, each sentence in a language has two levels of representation: a deep structure and a surface structure. The deep or underlying structure represents the semantic foundations of a sentence. Meanwhile the surface structure is the actual form of a sentence which essentially occurs in speech (the phonetic form or writing. While the speaker or the writer is on the side of deep structure as he/she is the one supposed to know the semantic layer of the sentence, the listener or the reader is passively exposed to the surface structure of a sentence. The surface structure of a sentence may have empty categories and traces that are normally full and existing in the deep layer of representation. In this study we will examine the language-internal and cross-linguistic versions of deep and surface structures. Başlangıçta 17. yüzyılda Port Royal Okulu tarafından ortaya atılan sonra Noam Chomsky tarafından formüle edilen teoriye göre her cümlenin derin yapı ve yüzey yapı olmak üzere iki katmanı vardır. Derin yapı adı verilen katman cümlenin anlambilimsel temelini oluşturur. Öte yandan yüzey yapı ise özellikle cümlenin en son söylenmiş veya yazılmış halini, yani gerçekte üretilmiş biçimini temsil eder. Cümlenin anlamına vakıf olan konuşur veya yazar dilbilimsel olarak derin yapı tarafında iken, dinleyici veya okuyucu yüzey yapı tarafındadır zira dinleyici veya okuyucu cümleye maruz kalan taraftır. Bir cümlenin yüzey yapısı boşluklarla ve izlerle dolu iken derin yapısı doluluk ve tamlık arz eder. Bu çalışmada derin ve yüzey yapı kavramlarının hem dil içi hem de diller arası türleri incelenecektir.

  15. Effective Use of Discovery Learning to Improve Understanding of Factors That Affect Quality

    Science.gov (United States)

    Mukherjee, Arup

    2015-01-01

    Undergraduate business majors are required to take a course in operations management. In this course, a great deal of emphasis is put on developing a good understanding of quality because this is likely to be the only required course that covers this important topic. Quality of output exhibits a great deal of variation. To produce high quality on…

  16. U.S. Policy and Canadian Lumber: Effects of the 1986 Memorandum of Understanding

    Science.gov (United States)

    David N. Wear; Karen J. Lee

    1993-01-01

    A 1986 Memorandum of Understanding on softwood lumber imports (MOU) between Canada and the United States required that provinvial governments levy export taxes on softwood lumber shipped to the United States. This agreement, with subsequent amendments, influenced trade from 1987 until it was abandoned by Canada in October of 1991. This paper investigates the market...

  17. Students' Understanding of Genetics Concepts: The Effect of Reasoning Ability and Learning Approaches

    Science.gov (United States)

    Kiliç, Didem; Saglam, Necdet

    2014-01-01

    Students tend to learn genetics by rote and may not realise the interrelationships in daily life. Because reasoning abilities are necessary to construct relationships between concepts and rote learning impedes the students' sound understanding, it was predicted that having high level of formal reasoning and adopting meaningful learning orientation…

  18. Effects of Experimenting with Physical and Virtual Manipulatives on Students' Conceptual Understanding in Heat and Temperature

    Science.gov (United States)

    Zacharia, Zacharias C.; Olympiou, Georgios; Papaevripidou, Marios

    2008-01-01

    This study aimed to investigate the comparative value of experimenting with physical manipulatives (PM) in a sequential combination with virtual manipulatives (VM), with the use of PM preceding the use of VM, and of experimenting with PM alone, with respect to changes in students' conceptual understanding in the domain of heat and temperature. A…

  19. Maternal Behavior Modifications during Pretense and Their Long-Term Effects on Toddlers' Understanding of Pretense

    Science.gov (United States)

    Nakamichi, Naoko

    2015-01-01

    Recent studies indicate the need to investigate the sources of toddlers' understanding of another person's pretense. The present study is a cultural and longitudinal extension of the work of Lillard and Witherington (2004), who claimed that mothers modify their behaviors during pretense and that the some of these behavior modifications help their…

  20. The Effect of Guided Note Taking during Lectures on Thai University Students' Understanding of Electromagnetism

    Science.gov (United States)

    Narjaikaew, Pattawan; Emarat, Narumon; Cowie, Bronwen

    2009-01-01

    This paper reports on the implementation of a guided note taking strategy to promote Thai students' understanding of electromagnetism during a lecture course. The aim of the study was to enhance student learning of electromagnetism concepts. The developed guided notes contain quotations, diagrams, pictures, problems, and blank spaces to encourage…