Science.gov

Sample records for natural solution concept

  1. Naturally selecting solutions

    PubMed Central

    Manning, Timmy; Sleator, Roy D; Walsh, Paul

    2013-01-01

    For decades, computer scientists have looked to nature for biologically inspired solutions to computational problems; ranging from robotic control to scheduling optimization. Paradoxically, as we move deeper into the post-genomics era, the reverse is occurring, as biologists and bioinformaticians look to computational techniques, to solve a variety of biological problems. One of the most common biologically inspired techniques are genetic algorithms (GAs), which take the Darwinian concept of natural selection as the driving force behind systems for solving real world problems, including those in the bioinformatics domain. Herein, we provide an overview of genetic algorithms and survey some of the most recent applications of this approach to bioinformatics based problems. PMID:23222169

  2. Natural Concepts in Pigeons

    ERIC Educational Resources Information Center

    Herrnstein, R. J.; And Others

    1976-01-01

    Pigeons learned discrimination rapidly and responded differentially to pictures seen for the first time. The essential feature of a natural discrimination--which is the ability to cope with natural ranges of variation--was approached and earlier experimental results were extended using other classes of stimuli. (Author/RK)

  3. On the Nature of Concepts.

    ERIC Educational Resources Information Center

    Ninnes, L. E.

    It is difficult to give a precise meaning to the term "concept" because to specify any sense to the term is already to be using concepts. It is impossible to talk about concepts without at the same time having made epistemological and metaphysical commitments. If the epistemological and metaphysical commitments are inadequate, then the…

  4. On the Nature of Concepts.

    ERIC Educational Resources Information Center

    Ninnes, L. E.

    It is difficult to give a precise meaning to the term "concept" because to specify any sense to the term is already to be using concepts. It is impossible to talk about concepts without at the same time having made epistemological and metaphysical commitments. If the epistemological and metaphysical commitments are inadequate, then the…

  5. Concept analysis: some limitations and possible solutions.

    PubMed

    Botes, A

    2002-08-01

    Concepts are the basic building blocks of scientific knowledge or theoretical frameworks for any discipline. The strength of the theories that guide a discipline is dependent on the quality of the concept analysis. Thus, the utilisation of poorly understood concepts in research and theory development will result in questionable reliability and validity. Concept analysis is associated with the research design of philosophical inquiry. The purpose of philosophical inquiry is to perform research using intellectual analysis to clarify meaning. Traditionally, no empirical (qualitative or quantitative) investigations were used to clarify the meaning of concepts. The lack of empirical investigation to clarify concepts, results in certain limitations in the methodology of concept analysis. It seems that methodological innovations for enhancing concept analysis is urgently required. The purpose of this article is to describe the utilisation of qualitative and quantitative strategies with literature review in concept analysis as a possible solution to limitations. This article will firstly, describe the limitations in the traditional Wilsonian methods of concept analysis and will secondly demonstrate how the introduction of qualitative and quantitative methods with literature review can overcome some of the limitations. An example a research study on quality of life (Ferrans, 1997:110) will be used to demonstrate how qualitative and quantitative empirical methods with literature review can enhance the quality of concept analysis.

  6. A natural species concept for prokaryotes

    NASA Technical Reports Server (NTRS)

    Ward, D. M.

    1998-01-01

    Direct molecular analyses of natural microbial populations reveal patterns that should compel microbiologists to adopt a more natural species concept that has been known to biologists for decades. The species debate can be exploited to address a larger issue - microbiologists need, in general, to take a more natural view of the organisms they study.

  7. A natural species concept for prokaryotes

    NASA Technical Reports Server (NTRS)

    Ward, D. M.

    1998-01-01

    Direct molecular analyses of natural microbial populations reveal patterns that should compel microbiologists to adopt a more natural species concept that has been known to biologists for decades. The species debate can be exploited to address a larger issue - microbiologists need, in general, to take a more natural view of the organisms they study.

  8. Childrens' Conceptions of Nature

    ERIC Educational Resources Information Center

    Payne, Phillip

    2014-01-01

    This paper describes a study of sixth grade children's conceptions of nature and the environment. In so doing, it asks that environmental educators pay more attention to children's preconceived notions of environment and nature. Should this occur the theory-practice gap in environmental education may be diminished. Learners' concept…

  9. Teaching Russian Culture: Concepts of Nature.

    ERIC Educational Resources Information Center

    Jones, Dianne

    Russian culture is very much influenced by its huge land area, peculiar topography, and harsh climate. To understand Russian culture one must know how Russians perceive nature. This paper discusses how this concept may be conveyed to U.S. middle school students through poetry. Poems about nature can provide students an opportunity to understand…

  10. Missing concepts in natural selection theory reconstructions.

    PubMed

    Ginnobili, Santiago

    2016-09-01

    The concept of fitness has generated a lot of discussion in philosophy of biology. There is, however, relative agreement about the need to distinguish at least two uses of the term: ecological fitness on the one hand, and population genetics fitness on the other. The goal of this paper is to give an explication of the concept of ecological fitness by providing a reconstruction of the theory of natural selection in which this concept was framed, that is, based on the way the theory was put to use in Darwin's main texts. I will contend that this reconstruction enables us to account for the current use of the theory of natural selection. The framework presupposed in the analysis will be that of metatheoretical structuralism. This framework will provide both a better understanding of the nature of ecological fitness and a more complete reconstruction of the theory. In particular, it will provide what I think is a better way of understanding how the concept of fitness is applied through heterogeneous cases. One of the major advantages of my way of thinking about natural selection theory is that it would not have the peculiar metatheoretical status that it has in other available views. I will argue that in order to achieve these goals it is necessary to make several concepts explicit, concepts that are frequently omitted in usual reconstructions.

  11. Nature, Human Nature, and Solutions to Problems.

    ERIC Educational Resources Information Center

    Pedrini, D. T.; Pedrini, B. C.

    This paper promotes an undergraduate course that would discuss the great ideas of Plato, St. Paul, Karl Marx, Sigmund Freud, Jean Paul Sartre, B. F. Skinner, and Konrad Lorenz. This course would help students understand human values and behaviors while focusing on historical, world, and national problems. Tentative solutions would then be…

  12. Nature, Human Nature, and Solutions to Problems.

    ERIC Educational Resources Information Center

    Pedrini, D. T.; Pedrini, B. C.

    This paper promotes an undergraduate course that would discuss the great ideas of Plato, St. Paul, Karl Marx, Sigmund Freud, Jean Paul Sartre, B. F. Skinner, and Konrad Lorenz. This course would help students understand human values and behaviors while focusing on historical, world, and national problems. Tentative solutions would then be…

  13. Semen analysis and prediction of natural conception.

    PubMed

    Leushuis, Esther; van der Steeg, Jan Willem; Steures, Pieternel; Repping, Sjoerd; Bossuyt, Patrick M M; Mol, Ben Willem J; Hompes, Peter G A; van der Veen, Fulco

    2014-07-01

    Do two semen analyses predict natural conception better than a single semen analysis and will adding the results of repeated semen analyses to a prediction model for natural pregnancy improve predictions? A second semen analysis does not add helpful information for predicting natural conception compared with using the results of a single semen analysis and addition of the second analysis to a prediction model for natural conception did not improve predictions. A major problem with semen analyses is the large variability of results within an individual. High-quality evidence is lacking on how many semen analyses need to be performed during the fertility workup to achieve an accurate prediction of conception. We conducted a prospective cohort study of 897 consecutive couples presenting with subfertility in two university hospitals in the period 2002-2004 in the Netherlands. The laboratories scored sperm parameters according to the 1999 WHO criteria. Sperm concentration was counted and motility was assessed in a Makler counting chamber at a magnification of ×200. All assessments were performed by trained laboratory technicians. Follow-up started at the completion of the infertility workup and ended after 12 months. Primary end-point was natural conception resulting in an ongoing pregnancy. We constructed models for three strategies for the prediction of natural conception, using univariable and multivariable Cox hazard regression analyses. We evaluated the performance of the three strategies by comparing goodness-of-fit, discrimination and calibration. First, we analysed the semen parameters only. Secondly, we analysed the semen parameters in addition to the multivariable Hunault prediction model. Of the 897 couples, 132 (15%) achieved a pregnancy by natural conception. Using the results of a single semen analysis only, the calculated probabilities of natural conception within 12 months across the study population ranged from 0.12 to 0.38, with a median of 0.16 (IQR

  14. Student conceptions of the nature of science

    NASA Astrophysics Data System (ADS)

    Talbot, Amanda L.

    Research has shown that students from elementary school to college have major misconceptions about the nature of science. While an appropriate understanding of the nature of science has been an objective of science education for a century, researchers using a variety of instruments, continue to document students' inadequate conceptions of what science is and how it operates as an enterprise. Current research involves methods to improve student understanding of the nature of science. Students often misunderstand the creative, subjective, empirical, and tentative nature of science. They do not realize the relationship between laws and theories, nor do they understand that science does not follow a prescribed method. Many do not appreciate the influence culture, society, and politics; nor do they have an accurate understanding of the types of questions addressed by science. This study looks at student understanding of key nature of science (NOS) concepts in order to examine the impact of implementing activities intended to help students better understand the process of science and to see if discussion of key NOS concepts following those activities will result in greater gains in NOS understanding. One class received an "activities only" treatment, while the other participated in the same activities followed by explicit discussion of key NOS themes relating to the activity. The interventions were implemented for one school year in two high school anatomy and physiology courses composed of juniors and seniors. Student views of the nature of science were measured using the Views of the Nature of Science-Form C (VNOS-C). Students in both classes demonstrated significant gains in NOS understanding. However, contrary to current research, the addition of explicit discussion did not result in significantly greater gains in NOS understanding. This suggests that perhaps students in higher-level science classes can draw the correlations between NOS related activities and

  15. Portable long trace profiler: Concept and solution

    SciTech Connect

    Qian, Shinan; Takacs, Peter; Sostero, Giovanni; Cocco, Daniele

    2001-08-01

    Since the early development of the penta-prism long trace profiler (LTP) and the in situ LTP, and following the completion of the first in situ distortion profile measurements at Sincrotrone Trieste (ELETTRA) in Italy in 1995, a concept was developed for a compact, portable LTP with the following characteristics: easily installed on synchrotron radiation beam lines, easily carried to different laboratories around the world for measurements and calibration, convenient for use in evaluating the LTP as an in-process tool in the optical workshop, and convenient for use in temporarily installation as required by other special applications. The initial design of a compact LTP optical head was made at ELETTRA in 1995. Since 1997 further efforts to reduce the optical head size and weight, and to improve measurement stability have been made at Brookhaven National Laboratory. This article introduces the following solutions and accomplishments for the portable LTP: (1) a new design for a compact and very stable optical head, (2) the use of a small detector connected to a laptop computer directly via an enhanced parallel port, and there is no extra frame grabber interface and control box, (3) a customized small mechanical slide that uses a compact motor with a connector-sized motor controller, and (4) the use of a laptop computer system. These solutions make the portable LTP able to be packed into two laptop-size cases: one for the computer and one for the rest of the system.

  16. Portable long trace profiler: Concept and solution

    NASA Astrophysics Data System (ADS)

    Qian, Shinan; Takacs, Peter; Sostero, Giovanni; Cocco, Daniele

    2001-08-01

    Since the early development of the penta-prism long trace profiler (LTP) and the in situ LTP, and following the completion of the first in situ distortion profile measurements at Sincrotrone Trieste (ELETTRA) in Italy in 1995, a concept was developed for a compact, portable LTP with the following characteristics: easily installed on synchrotron radiation beam lines, easily carried to different laboratories around the world for measurements and calibration, convenient for use in evaluating the LTP as an in-process tool in the optical workshop, and convenient for use in temporarily installation as required by other special applications. The initial design of a compact LTP optical head was made at ELETTRA in 1995. Since 1997 further efforts to reduce the optical head size and weight, and to improve measurement stability have been made at Brookhaven National Laboratory. This article introduces the following solutions and accomplishments for the portable LTP: (1) a new design for a compact and very stable optical head, (2) the use of a small detector connected to a laptop computer directly via an enhanced parallel port, and there is no extra frame grabber interface and control box, (3) a customized small mechanical slide that uses a compact motor with a connector-sized motor controller, and (4) the use of a laptop computer system. These solutions make the portable LTP able to be packed into two laptop-size cases: one for the computer and one for the rest of the system.

  17. A Review of Solution Chemistry Studies: Insights into Students' Conceptions

    ERIC Educational Resources Information Center

    Calyk, Muammer; Ayas, Alipa; Ebenezer, Jazlin V.

    2005-01-01

    This study has reviewed the last two decades of student conception research in solution chemistry pertaining to aims, methods of exploring students' conception, general knowledge claims, students' conceptions and difficulties, and conceptual change studies. The aims of solution chemistry studies have been to assess students' understanding level of…

  18. A Review of Solution Chemistry Studies: Insights into Students' Conceptions

    ERIC Educational Resources Information Center

    Calyk, Muammer; Ayas, Alipa; Ebenezer, Jazlin V.

    2005-01-01

    This study has reviewed the last two decades of student conception research in solution chemistry pertaining to aims, methods of exploring students' conception, general knowledge claims, students' conceptions and difficulties, and conceptual change studies. The aims of solution chemistry studies have been to assess students' understanding level of…

  19. Natural tuning: towards a proof of concept

    NASA Astrophysics Data System (ADS)

    Dubovsky, Sergei; Gorbenko, Victor; Mirbabayi, Mehrdad

    2013-09-01

    The cosmological constant problem and the absence of new natural physics at the electroweak scale, if confirmed by the LHC, may either indicate that the nature is fine-tuned or that a refined notion of naturalness is required. We construct a family of toy UV complete quantum theories providing a proof of concept for the second possibility. Low energy physics is described by a tuned effective field theory, which exhibits relevant interactions not protected by any symmetries and separated by an arbitrary large mass gap from the new "gravitational" physics, represented by a set of irrelevant operators. Nevertheless, the only available language to describe dynamics at all energy scales does not require any fine-tuning. The interesting novel feature of this construction is that UV physics is not described by a fixed point, but rather exhibits asymptotic fragility. Observation of additional unprotected scalars at the LHC would be a smoking gun for this scenario. Natural tuning also favors TeV scale unification.

  20. The natural flow wing-design concept

    NASA Technical Reports Server (NTRS)

    Wood, Richard M.; Bauer, Steven X. S.

    1992-01-01

    A wing-design study was conducted on a 65 degree swept leading-edge delta wing in which the wing geometry was modified to take advantage of the naturally occurring flow that forms over a slender wing in a supersonic flow field. Three-dimensional nonlinear analysis methods were used in the study which was divided into three parts: preliminary design, initial design, and final design. In the preliminary design, the wing planform, the design conditions, and the near-conical wing-design concept were derived, and a baseline standard wing (conventional airfoil distribution) and a baseline near-conical wing were chosen. During the initial analysis, a full-potential flow solver was employed to determine the aerodynamic characteristics of the baseline standard delta wing and to investigate modifications to the airfoil thickness, leading-edge radius, airfoil maximum-thickness position, and wing upper to lower surface asymmetry on the baseline near-conical wing. The final design employed an Euler solver to analyze the best wing configurations found in the initial design and to extend the study of wing asymmetry to develop a more refined wing. Benefits resulting from each modification are discussed, and a final 'natural flow' wing geometry was designed that provides an improvement in aerodynamic performance compared with that of a baseline conventional uncambered wing, linear-theory cambered wing, and near-conical wing.

  1. Exploring the folkbiological conception of human nature

    PubMed Central

    Linquist, Stefan; Machery, Edouard; Griffiths, Paul E.; Stotz, Karola

    2011-01-01

    Integrating the study of human diversity into the human evolutionary sciences requires substantial revision of traditional conceptions of a shared human nature. This process may be made more difficult by entrenched, ‘folkbiological’ modes of thought. Earlier work by the authors suggests that biologically naive subjects hold an implicit theory according to which some traits are expressions of an animal's inner nature while others are imposed by its environment. In this paper, we report further studies that extend and refine our account of this aspect of folkbiology. We examine biologically naive subjects' judgments about whether traits of an animal are ‘innate’, ‘in its DNA’ or ‘part of its nature’. Subjects do not understand these three descriptions to be equivalent. Both innate and in its DNA have the connotation that the trait is species-typical. This poses an obstacle to the assimilation of the biology of polymorphic and plastic traits by biologically naive audiences. Researchers themselves may not be immune to the continuing pull of folkbiological modes of thought. PMID:21199848

  2. Bringing nature-based solutions to scale

    NASA Astrophysics Data System (ADS)

    Jongman, Brenden; Lange, Glenn-Marie; Balog, Simone; van Wesenbeeck, Bregje

    2017-04-01

    Coastal communities in developing countries are highly exposed and vulnerable to coastal flood risk, and are likely to suffer from climate change induced changes in risk. Over the last decade, strong evidence has surfaced that nature-based solutions or ecosystem-based approaches are efficient and effective alternatives for flood risk reduction and climate change adaptation. In developing countries, numerous projects have therefore been implemented, often driven by international donors and NGOs. Some of these projects have been successful in reducing risk while improving environmental and socioeconomic conditions. However, the feasibility assessment, design and implementation of nature-based solutions is a multifaceted process, which needs to be well-understood before such solutions can be effectively implemented as an addition or alternative to grey infrastructure. This process has not always been followed. As a result, many projects have failed to deliver positive outcomes. The international community therefore has a challenge in bringing nature-based solutions to scale in an effective way. In this presentation, we will present best practice guidelines on nature-based solution implementation that are currently being discussed by the international community. Furthermore, we will present the alpha version of a new web platform being developed by the World Bank that will serve as a much-needed central repository for project information on nature-based solutions, and that will host actionable implementation guidelines. The presentation will also serve as an invitation to the scientific community to share their experience and lessons learned, and contribute to the outlining of best practice guidance.

  3. Natural optical design concepts for highly miniaturized camera systems

    NASA Astrophysics Data System (ADS)

    Voelkel, Reinhard

    1999-08-01

    Microcameras for computers, mobile phones, watches, security system and credit cards is a very promising future market. Semiconductor industry is now able to integrate light reception, signal amplification and processing in a low- power-consuming microchip of a few mm2 size. Active pixel sensors supply each pixel in an image sensor with an individually programmable functionality. Beside the electronic receptor chip, a highly miniaturized lens system is required. Compared to the progress in microelectronics, optics has not yet made a significant step. Today's microcamera lenses are usually a downscaled version of a classical lens system and rarely smaller than 3 mm X 3 mm X 3 mm. This lagging of optics is quite surprising. Biologists have systematically studied all types of natural eye sensors since the 18th Century. Mother Nature provides a variety of highly effective examples for miniaturized imaging system. Single-aperture systems are the appropriate solution if the size is a free design parameter. If the budget is tight and optics limited to size, nature prefers multiple-aperture systems, the so-called compound eyes. As compound eyes are limited in resolution and night view, a cluster of single-aperture eyes, as jumping spiders use, is probably a better solution. The recent development in micro- optics offers the chance to imitate such natural design concepts. We have investigated miniaturized imaging systems based on microlens array and natural optical design concepts. Practical limitations for system design, packaging and assembling are given. Examples for micro-optical components and imaging systems are presented.

  4. Marine geodesy - Problem areas and solution concepts

    NASA Technical Reports Server (NTRS)

    Saxena, N.

    1974-01-01

    This paper deals with a conceptional geodetic approach to solve various oceanic problems, such as submersible navigation under iced seas, demarcation/determination of boundaries in open ocean, resolving sea-level slope discrepancy, improving tsunami warning system, ecology, etc., etc. The required instrumentation is not described here. The achieved as well as desired positional accuracy estimates in open ocean for various tasks are also given.

  5. Marine geodesy - Problem areas and solution concepts

    NASA Technical Reports Server (NTRS)

    Saxena, N.

    1974-01-01

    This paper deals with a conceptional geodetic approach to solve various oceanic problems, such as submersible navigation under iced seas, demarcation/determination of boundaries in open ocean, resolving sea-level slope discrepancy, improving tsunami warning system, ecology, etc., etc. The required instrumentation is not described here. The achieved as well as desired positional accuracy estimates in open ocean for various tasks are also given.

  6. Naturally selecting solutions: the use of genetic algorithms in bioinformatics.

    PubMed

    Manning, Timmy; Sleator, Roy D; Walsh, Paul

    2013-01-01

    For decades, computer scientists have looked to nature for biologically inspired solutions to computational problems; ranging from robotic control to scheduling optimization. Paradoxically, as we move deeper into the post-genomics era, the reverse is occurring, as biologists and bioinformaticians look to computational techniques, to solve a variety of biological problems. One of the most common biologically inspired techniques are genetic algorithms (GAs), which take the Darwinian concept of natural selection as the driving force behind systems for solving real world problems, including those in the bioinformatics domain. Herein, we provide an overview of genetic algorithms and survey some of the most recent applications of this approach to bioinformatics based problems.

  7. Relationships between proenvironmental attitudes and concepts of nature.

    PubMed

    Iwata, O

    2001-02-01

    The author investigated relationships between proenvironmental attitudes and concepts of nature. Proenvironmental attitudes were measured on a 5-point scale containing 27 items. The author developed a 5-point scale containing 20 items to assess concepts of nature. The author administered those 2 scales to 140 young adults and adolescents at 2 Japanese institutions of higher education. An investigation of 6 proenvironmental attitudes and 20 concepts of nature showed some significant relationships. Factor analysis of the 20 concepts of nature produced 2 factors: Positive Evaluation of Nature and Rejection of Manipulation of Human Life. Most relationships were significant between the scores for the 6 proenvironmental attitudes and those for the 2 factors of concepts of nature.

  8. The Fuzzy Nature Of Concepts: Stochastic Objects

    NASA Astrophysics Data System (ADS)

    Sotiropoulos, Megaklis Th.

    2010-09-01

    Concept is every assignment of a prototype to an icon, whatever may be the prototype or the icon. We call the prototype "object" and the icon "attributes". Concepts are couples of sets O and A, that is assignments, of the object O (a set of none, or one or more elements -there is no real difference), to the set A of (their common) attributes. The objects change according to the sequence of attributes. So, only couples of objects and attributes, enriched with the proper operations, are adequate for our Knowledge Space. Concepts are proved to have the structure (order) of a Boolean Algebra(Lattice), which is more complex than linear or hierarchical ones. The lattice is created by two algebraic operations ("intersection of concepts" as the multiplication and "symmetric-difference(!) of concepts" as the addition (!)). There are two other operations (the "union of two concepts" and the "complement of a concept"). Intersection and union(which cannot play the role of multiplication) express similarities, while the other two operations express dissimilarities. Union, intersection and the complement are used for the definition of the symmetric-difference. The complement cannot be expressed by the two predefined operations union and intersection, which have the meaning of "common". Besides, it is not a deterministic function: the complement Oc may have attributes inside the complement Ac of attributes (and if yes, we do not know, from the beginning, which of them). Now, the situation becomes stochastic: if Ω' is the set of n attributes we are interested in (e.g., in m sequential experiments), suppose that, in each experiment, some attributes appear(are detected) and the rest from Ω' do not appear. Everyone from the m experiments consists of n Bernulli trials (one for every attribute) and, consequently, we get m stochastically changing objects (concepts) and the (complete, if we are very lucky) lattice of the m concepts. Everyone from the n attributes corresponds to a B

  9. A Review of Solution Chemistry Studies: Insights into Students? Conceptions

    NASA Astrophysics Data System (ADS)

    Çalýk, Muammer; Ayas, Alipaşa; Ebenezer, Jazlin V.

    2005-03-01

    This study has reviewed the last two decades of student conception research in solution chemistry pertaining to aims, methods of exploring students' conception, general knowledge claims, students' conceptions and difficulties, and conceptual change studies. The aims of solution chemistry studies have been to assess students' understanding level of solution chemistry and in some studies compare understanding based on age and year at school or college. The methods of exploring students' conceptions consisted of interviews, paper and pencil surveys (open-ended questions and multiple-choice questions), free writing and drawings and the validity of these methods have been highlighted. The general knowledge claims synthesized in this study are students' (a) attending to mechanical events, (b) preference for everyday language usage over chemical language, (c) confusing solution chemistry with non-related concepts, (d) lack of sub-microscopic explanation for macroscopic observation, (e) difficulty with visualizing and representing sub-microscopic ideas, (f) difficulty with symbolic representations, (g) inconsistent explanations, (h) development of student understanding with age, and (i) development of conservation reasoning with age. To incorporate students' conceptions, conceptual change studies have used strategies such as worksheet, analogy, collaboratively working with a teacher, hypermedia, and group exploration. The results of conceptual change studies generally have had a positive impact enabling students to consider their ideas and develop plausible models of solution chemistry. For improvement of student learning in chemistry, this review of solution chemistry studies sheds light on teacher thinking and capacity building with respect to explicitly incorporating students' conceptions into chemistry curriculum; practicing research-based strategies; forging links among types of chemical knowledge; collaborating for experimental teaching; and conducting further

  10. Assessment of future natural gas vehicle concepts

    NASA Astrophysics Data System (ADS)

    Groten, B.; Arrigotti, S.

    1992-10-01

    The development of Natural Gas Vehicles is progressing rapidly under the stimulus of recent vehicle emission regulations. The development is following what can be viewed as a three step progression. In the first step, contemporary gasoline or diesel fueled automobiles are retrofitted with equipment enabling the vehicle to operate on either natural gas or standard liquid fuels. The second step is the development of vehicles which utilize traditional internal combustion engines that have been modified to operate exclusively on natural gas. These dedicated natural gas vehicles operate more efficiently and have lower emissions than the dual fueled vehicles. The third step is the redesigning, from the ground up, of a vehicle aimed at exploiting the advantages of natural gas as an automotive fuel while minimizing its disadvantages. The current report is aimed at identifying the R&D needs in various fuel storage and engine combinations which have potential for providing increased efficiency, reduced emissions, and reductions in vehicle weight and size. Fuel suppliers, automobile and engine manufacturers, many segments of the natural gas and other industries, and regulatory authorities will influence or be affected by the development of such a third generation vehicle, and it is recommended that GRI act to bring these groups together in the near future to begin, developing the focus on a 'designed-for-natural-gas' vehicle.

  11. Solution dynamics of synthetic and natural polyelectrolytes

    NASA Astrophysics Data System (ADS)

    Krause, Wendy E.

    Polyelectrolytes are abundant in nature and essential to life, and used extensively in industry. This work discussed two polyelectrolytes: sodium poly(2-acrylamido-2-methylpropanesulfonate) (NaPAMS), synthetic polyelectrolyte, and sodium hyaluronate (NaHA), a glycosaminoglycan. Rheological data of NaPAMS solutions of variable chain length and concentration were reported. A strong dependence of viscosity eta on chain length: eta ˜ M2.4 was found. The comparison of the rheological data with two proposed scaling theories (Dobrynin 1995, Witten 1987) forces the conclusion that neither theory is correct. A possible interpretation of the viscosity data falling between the predictions of the two scaling theories is that some chain rigidity may persist beyond the correlation length. A sample model for the conductivity of semidilute polyelectrolytes with no added salt was presented. The model correctly describes the logarithmic decrease of specific conductance observed for many polyelectrolytes at low concentration (below ca. 10-2M), and is in good agreement with data from NaPAMS solutions. NaHA in phosphate buffered saline behaves as a typical polyelectrolyte in the high-salt limit, as Newtonian viscosities are observed over a wide range of shear rates. There is no evidence of intermolecular hydrogen bonding causing gel formation in NaHA solutions without protein present. The viscosity of 3 mg/mL NaHA was measured in the presence of the selected anti-inflammatory agents. Of the seven additives investigated only (D)-penicillamine significantly altered the rheology of HA. (D)-Penicillamine dramatically reduced the viscosity of HA, probably by disrupting intramolecular hydrogen bonding. The plasma proteins albumin and gamma-globulins bind to HA in solution to form a weak reversible gel. The rheology and osmotic pressure of the simple model for synovial fluid, consisting of 3mg/mL NaHA, 11 mg/mL albumin, and 7 mg/mL gamma-globulins in phosphate buffered saline, were studied

  12. Natural regeneration - small ownerships from concept to practice

    Treesearch

    Arthur G., Jr. Dodge

    1977-01-01

    Established concepts of successful natural regeneration are not necessarily practiced on small ownerships of ten to 500 acres. Unevenage management will be the primary management system on small ownerships and natural regeneration is the most practical method of providing for continuous forest production. We can obtain satisfactory natural regeneration by good planning...

  13. Feature integration in natural language concepts.

    PubMed

    Hampton, James A; Storms, Gert; Simmons, Claire L; Heussen, Daniel

    2009-12-01

    Two experiments measured the joint influence of three key sets of semantic features on the frequency with which artifacts (Experiment 1) or plants and creatures (Experiment 2) were categorized in familiar categories. For artifacts, current function outweighed both originally intended function and current appearance. For biological kinds, appearance and behavior, an inner biological function, and appearance and behavior of offspring all had similarly strong effects on categorization. The data were analyzed to determine whether an independent cue model or an interactive model best accounted for how the effects of the three feature sets combined. Feature integration was found to be additive for artifacts but interactive for biological kinds. In keeping with this, membership in contrasting artifact categories tended to be superadditive, indicating overlapping categories, whereas for biological kinds, it was subadditive, indicating conceptual gaps between categories. It is argued that the results underline a key domain difference between artifact and biological concepts.

  14. Threshold concepts: implications for the management of natural resources

    USGS Publications Warehouse

    Guntenspergen, Glenn R.; Gross, John

    2014-01-01

    Threshold concepts can have broad relevance in natural resource management. However, the concept of ecological thresholds has not been widely incorporated or adopted in management goals. This largely stems from the uncertainty revolving around threshold levels and the post hoc analyses that have generally been used to identify them. Natural resource managers have a need for new tools and approaches that will help them assess the existence and detection of conditions that demand management actions. Recognition of additional threshold concepts include: utility thresholds (which are based on human values about ecological systems) and decision thresholds (which reflect management objectives and values and include ecological knowledge about a system) as well as ecological thresholds. All of these concepts provide a framework for considering the use of threshold concepts in natural resource decision making.

  15. Natural Kinds and Concepts of Physics

    NASA Astrophysics Data System (ADS)

    Fano, Vincenzo

    A classification of different levels between experience and theories of mathematical physics is outlined. Moving from these distinctions it is possible to detect four kinds of kinds, from natural ones to abstract ones of theoretical physics. Then it is argued that the interpretation of physics as an increasingly better understanding of essences, which descends from Kripke's and Putnam's theory of reference, is not very plausible. On the other side it is possible to single out a structural analogy between the perceptual notion of object and that of theoretical physics based on the correspondence between the notions of similarity and invariance.

  16. Exploring Prospective Teachers' Worldviews and Conceptions of Nature of Science

    ERIC Educational Resources Information Center

    Liu, Shiang-Yao; Lederman, Norman G.

    2007-01-01

    This study explores the relationship, if any, between an individual's culturally based worldviews and conceptions of nature of science. In addition, the implications of this relationship (or lack of relationship) for science teaching and learning are discussed. Participants were 54 Taiwanese prospective science teachers. Their conceptions of…

  17. The nature of dissection: Exploring student conceptions

    NASA Astrophysics Data System (ADS)

    York, Katharine

    The model of conceptual change in science describes the process of learning as a complete restructuring of knowledge, when learners discover or are shown more plausible, intelligent alternatives to existing conceptions. Emotions have been acknowledged as part of a learner's conceptual ecology, but the effects of emotions on learning have yet to be described. This research was conducted to examine the role that emotions have on learning for thirteen high school students, as they dissected cats in a Human Anatomy and Physiology class. The project also investigated whether a student's emotional reactions may be used to develop a sense of connectedness with the nonhuman world, which is defined as ecological literacy. This study utilized a grounded theory approach, in which student responses to interviews were the primary source of data. Interviews were transcribed, and responses were coded according to a constant comparative method of analysis. Responses were compared with the four conditions necessary for conceptual change to occur, and also to five principles of ecological literacy. Students who had negative reactions to dissection participated less in the activity, and demonstrated less conceptual change. Two female students showed the strongest emotional reactions to dissection, and also the lowest amount of conceptual change. One male student also had strong negative reactions to death, and showed no conceptual change. The dissection experiences of the students in this study did not generally reflect ecological principles. The two students whose emotional reactions to dissection were the most negative demonstrated the highest degree of ecological literacy. These results provide empirical evidence of the effects that emotions have on learning, and also supports the opinions of educators who do not favor dissection, because it does not teach students to respect all forms of life.

  18. Wallpaper concept solution fabrication experiences in FGD systems

    SciTech Connect

    Agarwal, D.C.; Flasche, L.H.

    1987-01-01

    In the last few years, a concentrated research effort has led to a better understanding of the corrosion problems in flue gas desulfurization (FGD) systems of coal fired power plants. At first look, operation of a typical limestone FGD system appears very simple, hence the first generation scrubbers of early to mid 70's were designers inspiration. However, the designers inspiration soon turned into a utility's nightmare due to failures of metals and non-metals, both failing in a an embarrassingly short time. A solution was needed which had to be reliable, simple, and cost effective. This objective was met via the application of wallpaper concept, which now has been very well accepted in the industry and is becoming increasingly more popular due to the many successful case histories. This paper describes the wallpaper concept solution, the fabrication techniques, the experiences at certain utilities, the precautions which need to be followed, the associated economics, and some case histories.

  19. Solution Concepts for Distributed Decision-Making without Coordination

    NASA Technical Reports Server (NTRS)

    Beling, Peter A.; Patek, Stephen D.

    2005-01-01

    Consider a single-stage problem in which we have a group N agents who are attempting to minimize the expected cost of their joint actions, without the benefit of communication or a pre-established protocol but with complete knowledge of the expected cost of any joint set of actions for the group. We call this situation a static coordination problem. The central issue in defining an appropriate solution concept for static coordination problems is considering how to deal with the fact that if the agents axe faced with a set of multiple (mixed) strategies that are equally attractive in terms of cost, a failure of coordination may lead to an expected cost value that is worse than that of any of the strategies in the set. In this proposal, we describe the notion of a general coordination problem, describe initial efforts at developing a solution concept for static coordination problems, and then outline a research agenda that centers on activities that will be basis for obtaining a complete understanding of solutions to static coordination problems.

  20. Turkish Primary Students' Conceptions about the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Ozmen, Haluk

    2011-01-01

    This study was conducted to determine 4th, 5th, and 6th grade primary students' conceptions about the particulate nature of matter in daily-life events. Five questions were asked of students and interviews were used to collect data. The interviews were conducted with 12 students, four students from each grade, after they finished the formal…

  1. Pre-Service Physics Teachers' Conceptions of Nature of Science

    ERIC Educational Resources Information Center

    Buaraphan, Khajornsak

    2011-01-01

    Understanding of NOS (nature of science) appears as a prerequisite of a scientifically literate person. Promoting adequate understanding of NOS in pre-service physics teachers is, therefore, an important task of science educators. Before doing that, science educators must have information concerning their pre-service teachers' conceptions of NOS.…

  2. Nature-Based Solutions in the EU: Innovating with nature to address social, economic and environmental challenges.

    PubMed

    Faivre, Nicolas; Fritz, Marco; Freitas, Tiago; de Boissezon, Birgit; Vandewoestijne, Sofie

    2017-11-01

    Contemporary societies are facing a broad range of challenges, from pressures on human health and well-being to natural capital depletion, and the security of food, water and energy. These challenges are deeply intertwined with global processes, such as climate change and with local events such as natural disasters. The EU's research & innovation (R&I) policy is now seeking to address these challenges from a new perspective, with Nature-Based Solutions, and turn them into innovation opportunities that optimise the synergies between nature, society and the economy. Nature-Based Solutions can be an opportunity for innovation, and are here promoted by both policymakers and practitioners as a cost-effective way of creating a greener, more sustainable, and more competitive economy. Since 2013, the European Commission has devoted particular attention to Nature-Based Solutions through consultations and dialogues that sought to make the concept of these solutions more concrete and to define the concept's place within the spectrum of ecosystem-based approaches. In 2014, the Commission launched an expert group, which conducted further analysis, and made recommendations to help increase the use of Nature-Based Solutions and bring nature back into cities. In 2015, a survey was conducted on citizens' views and perceptions of 'Nature in Cities' to provide further insight for future work. Based on these elements and on results from running EU projects, the Commission has developed an R&I agenda for Nature-Based Solutions and has published targeted calls for proposals for large-scale demonstration projects in this field in 2016 and 2017. Additional R&I actions at EU level that promote systemic Nature-Based Solutions and their benefits to cities and territories are planned with the aim to improve the implementation capacity and evidence base for deploying Nature-Based Solutions and developing corresponding future markets. They are also expected to foster an interdisciplinary R

  3. Concepts and implementations of natural language query systems

    NASA Technical Reports Server (NTRS)

    Dominick, Wayne D. (Editor); Liu, I-Hsiung

    1984-01-01

    The currently developed user language interfaces of information systems are generally intended for serious users. These interfaces commonly ignore potentially the largest user group, i.e., casual users. This project discusses the concepts and implementations of a natural query language system which satisfy the nature and information needs of casual users by allowing them to communicate with the system in the form of their native (natural) language. In addition, a framework for the development of such an interface is also introduced for the MADAM (Multics Approach to Data Access and Management) system at the University of Southwestern Louisiana.

  4. Green Extraction of Natural Products: Concept and Principles

    PubMed Central

    Chemat, Farid; Vian, Maryline Abert; Cravotto, Giancarlo

    2012-01-01

    The design of green and sustainable extraction methods of natural products is currently a hot research topic in the multidisciplinary area of applied chemistry, biology and technology. Herein we aimed to introduce the six principles of green-extraction, describing a multifaceted strategy to apply this concept at research and industrial level. The mainstay of this working protocol are new and innovative technologies, process intensification, agro-solvents and energy saving. The concept, principles and examples of green extraction here discussed, offer an updated glimpse of the huge technological effort that is being made and the diverse applications that are being developed. PMID:22942724

  5. Rewilding as nature based solution in land management

    NASA Astrophysics Data System (ADS)

    Novara, Agata; Gristina, Luciano; Keesstra, Saskia; Pereira, Paulo; Cerda, Artemio

    2017-04-01

    Rewilding is an effective tool of ecological restoration and a nature based solution for hydro-meteorological risk control. Rewilding contributes to reduce flood risk, resist droughts, helps to restore soil organic matter content, increases soil and plant biodiversity, improves the overall ecosystem and human health. The key element of rewilding is not the nature control, but following the natural processes to restore the key soil ecological factors and their connectivity. Rewilding can be applicable at different ecosystem stages, from natural reserve to more anthropogenic system such as agricultural land through the restoration of wild soil function trough permaculture or forest farming. The proposed nature based solution not only avoid the investment in traditional engineering but it also an opportunities for creating new economics model based on wild nature (ecoturism, education, wild edible plants). This work is a review of applied rewilding actions and considerations on future nature based solutions applications will be discussed .

  6. "The City Snuffs out Nature": Young People's Conceptions of and Relationship with Nature

    ERIC Educational Resources Information Center

    Pointon, Pam

    2014-01-01

    This paper reports a study of 384 13-14-year olds' written responses to open-ended questions about their understanding of and relationship with "nature." Using constant comparative method the responses were coded, categorised and themed. Most students held scientific conceptions of nature (excluding humans) and a utilitarian relationship…

  7. "The City Snuffs out Nature": Young People's Conceptions of and Relationship with Nature

    ERIC Educational Resources Information Center

    Pointon, Pam

    2014-01-01

    This paper reports a study of 384 13-14-year olds' written responses to open-ended questions about their understanding of and relationship with "nature." Using constant comparative method the responses were coded, categorised and themed. Most students held scientific conceptions of nature (excluding humans) and a utilitarian relationship…

  8. Children's Concepts of Natural Phenomena: Use of a Cognitive Mapping Approach to Describe These Concepts.

    ERIC Educational Resources Information Center

    Rowell, Richard M.

    Reported is a study based on the summary findings of a series of studies which indicated that many children who receive organized instruction designed around the few major concepts of science do, in fact, use scientific models to explain their observations of natural phenomena. The instruction that children in the study received was delivered by…

  9. The Concept of Ecologically Oriented Progress and Natural Resource Preservation

    NASA Astrophysics Data System (ADS)

    Gasanov, M. A.; Kolotov, K. A.; Demidenko, K. A.; Podgornaya, E. A.; Kadnikova, O. V.

    2017-01-01

    The most important issue of scientific and technological progress is considering the environment challenges of industrial development. It means that the progress must be ecologically oriented and environmentally friendly. The most adequate concept for the approach to the issue of “man - society - nature” relations is the ontology of the noosphere - the idea of a common space for human beings and nature. It presents an ideal example of an optimistic attitude towards the coordination between accelerating the scientific and technological development and natural resource saving. However, to maintain the balance between human needs and environmental processes determined by this concept, it is essential to include the lean production training into technological development of society.

  10. Natural adsorbents of dyes from aqueous solution

    NASA Astrophysics Data System (ADS)

    Rahmani, Meryem; El Hajjaji, souad; Dahchour, Abdelmalek; El M'Rabet, Mohammadine

    2017-04-01

    Contamination of natural waters is a current environmental problem and lot of work has been done to find methods for its, prevention and remediation such as ionic exchange, adsorption on active carbon, filtration, electrolysis, biodegradation …etc. Adsorption is one of the most applied methods according to its effectiveness and easy management. Some adsorbents with good properties such as active alumina, zeolites, crop residues … etc, are suitable to substitute usual active carbon. This study aimed at the removal of dyes using oil shale as natural support, and its optimization by factorial experiment. Three factors were considered namly:pollutant concentration, pH and weight of the adsorbent. Tests have been performed with cationic and anionic dyes. Experimental results show that pseudo-first-order kinetic model provided the best fit to the experimental data for the adsorption by the oil shale. Langmuir, Freundlich and Temkin isotherm models were tested to fit experimental data, the adsorption equilibrium was well described by Freundlich isotherm for methylorange and Temkin for methyl blue. Analysis were completed by oil shale characterization educing XRD, IR, XRF techniques, and cationic exchange capacity.

  11. Optical integration of incisoproximal restorations using the natural layering concept.

    PubMed

    Magne, Pascal; So, Woong Seup

    2008-09-01

    To evaluate the optical integration of 4 contemporary composite resin materials used for incisoproximal restorations and the natural layering concept. Miris 2 (M2; Coltene Whaledent), Gradia Direct (GD; GC), Enamel Plus HFO (HFO; Micerium), and Filtek Supreme Plus (FSP; 3M ESPE) composite resins were used to consecutively restore 6 extracted incisors with incisoproximal restorations using the natural layering concept, mimicking the natural anatomy of the tooth with only 2 composite resin masses (dentin and enamel). Following each restoration, the specimen was allowed to rehydrate for 2 weeks and was then photographed under standardized conditions (direct, indirect, and fluorescent lights). Six independent evaluators scored each light condition using an optical integration score on a scale from 1 to 4 (1 = worst optical integration, restoration can be easily distinguished from remaining tissues; 4 = optimal optical integration, restoration "invisible"). Mean optical integration scores (from the 6 evaluators) were analyzed with a 2-way analysis of variance (ANOVA) (composite resin brand and light condition). Pooled data of M2 and HFO (single-hue systems) and GD and FSP (multiple-hue systems) were also analyzed with a 2-way ANOVA (shade system and light condition). M2 obtained the highest optical integration scores (P < .03), followed by GD and HFO (not significantly different, P = .99). FSP showed the least favorable optical behavior (P < .0001), which is explained in part by the lack of fluorescence and possible inappropriateness for use with the natural layering technique. Single-hue systems (M2 and HFO) achieved better optical integration (P < .02) compared to multihue systems (GD and FSP). For M2, the simplified natural layering concept produced incisoproximal restorations with excellent optical integration. GD and HFO are also suitable for this technique. FSP failed to produce acceptable optical integration in the present study.

  12. Natural language solution to a Tuff problem

    SciTech Connect

    Langkopf, B.S.; Mallory, L.H.

    1984-12-31

    A scientific data base, the Tuff Data Base, is being created at Sandia National Laboratories on the Cyber 170/855, using System 2000. It is being developed for use by scientists and engineers investigating the feasibility of locating a high-level radioactive waste repository in tuff (a type of volcanic rock) at Yucca Mountain on and adjacent to the Nevada Test Site. This project, the Nevada Nuclear Waste Storage Investigations (NNWSI) Project, is managed by the Nevada Operations Office of the US Department of Energy. A user-friendly interface, PRIMER, was developed that uses the Self-Contained Facility (SCF) command SUBMIT and System 2000 Natural Language functions and parametric strings that are schema resident. The interface was designed to: (1) allow users, with or without computer experience or keyboard skill, to sporadically access data in the Tuff Data Base; (2) produce retrieval capabilities for the user quickly; and (3) acquaint the users with the data in the Tuff Data Base. This paper gives a brief description of the Tuff Data Base Schema and the interface, PRIMER, which is written in Fortran V. 3 figures.

  13. A Concept-Centric Framework for Building Natural Language Interfaces

    NASA Astrophysics Data System (ADS)

    Funakoshi, Kotaro; Nakano, Mikio; Hasegawa, Yuji; Tsujino, Hiroshi

    Natural language interfaces are expected to come into practical use in many situations. It is, however, not practical to expect to achieve a universal interface because language use is so diverse. To that end, not only advancements in speech and language technologies but also well-designed development frameworks are required so that developers can build domain-specific interfaces rapidly and easily. This paper proposes KNOLU, a framework for building natural language interfaces of a broad range of applications. Developers using this framework can easily build an interface capable of understanding subsets of natural language expressions just by providing an ontology (a concept hierarchy with semantic frames and a lexicon), an onomasticon (a set of instances and their names) and API functions that provide procedural knowledge required to connect the interface to a target application. To develop an interface using KNOLU, first developers define a concept hierarchy for a target domain. Then they provide other declarative and procedural knowledge components with these knowledge components asscicated to the hierarchy. This developmental flow affords an unobstructed view both for development and maintanance. KNOLU uses an existing general-purpose parser and requires neither grammar rules nor expression patterns. It does not require rules to generate semantic interpretations from parsing results, either. Therefore, developers can build an interface without deep knowledge and experience of natural language processing. We applied KNOLU to two applications and confirmed the effectiveness.

  14. The concept of nature in Islamic science teaching

    NASA Astrophysics Data System (ADS)

    Zarman, Wendi

    2016-02-01

    Science teaching is basically value laden activities. One of the values tells that science is not related to any religion. This secular value is reflected to science teaching in many places, including religious country like Indonesia. However, we argue that in Indonesia science teaching should not be secular as in the Western country since one of the basic aim of National Education according to the Indonesian constitution Undang-Undang Dasar 1945, is to inculcate faith and god-fearing to One God Almighty. As we know, Indonesia is a Moslem country and has many Islamic schools in it too. Thus, it is important to design a science teaching framework base on Islamic teaching to fulfill the basic aim of National Education This paper discusses concept of nature, the key term in science, based on Islamic view that may used as a framework to develop Islamic science teaching. In Islam, science has a strong relation to religion since nature reflects the existence of the Creator. This concept is derived from the analysis of several verses from Qur'an as the main source of Islamic teaching. There are several principle can be derived from this analysis. Firstly, visible world is not the only world, but there is also the unseen world. Secondly, the nature is not merely matter that doesn't have any sacred value, but it is the indication or symbol of God existence and His Nature. Thirdly, The Qur'an and the nature are both Books of Allah that contain messages of Him, so they are complementary to each other

  15. Action being character: a promising perspective on the solution concept of game theory.

    PubMed

    Deng, Kuiying; Chu, Tianguang

    2011-05-09

    The inconsistency of predictions from solution concepts of conventional game theory with experimental observations is an enduring question. These solution concepts are based on the canonical rationality assumption that people are exclusively self-regarding utility maximizers. In this article, we think this assumption is problematic and, instead, assume that rational economic agents act as if they were maximizing their implicit utilities, which turns out to be a natural extension of the canonical rationality assumption. Implicit utility is defined by a player's character to reflect his personal weighting between cooperative, individualistic, and competitive social value orientations. The player who actually faces an implicit game chooses his strategy based on the common belief about the character distribution for a general player and the self-estimation of his own character, and he is not concerned about which strategies other players will choose and will never feel regret about his decision. It is shown by solving five paradigmatic games, the Dictator game, the Ultimatum game, the Prisoner's Dilemma game, the Public Goods game, and the Battle of the Sexes game, that the framework of implicit game and its corresponding solution concept, implicit equilibrium, based on this alternative assumption have potential for better explaining people's actual behaviors in social decision making situations.

  16. Action Being Character: A Promising Perspective on the Solution Concept of Game Theory

    PubMed Central

    Deng, Kuiying; Chu, Tianguang

    2011-01-01

    The inconsistency of predictions from solution concepts of conventional game theory with experimental observations is an enduring question. These solution concepts are based on the canonical rationality assumption that people are exclusively self-regarding utility maximizers. In this article, we think this assumption is problematic and, instead, assume that rational economic agents act as if they were maximizing their implicit utilities, which turns out to be a natural extension of the canonical rationality assumption. Implicit utility is defined by a player's character to reflect his personal weighting between cooperative, individualistic, and competitive social value orientations. The player who actually faces an implicit game chooses his strategy based on the common belief about the character distribution for a general player and the self-estimation of his own character, and he is not concerned about which strategies other players will choose and will never feel regret about his decision. It is shown by solving five paradigmatic games, the Dictator game, the Ultimatum game, the Prisoner's Dilemma game, the Public Goods game, and the Battle of the Sexes game, that the framework of implicit game and its corresponding solution concept, implicit equilibrium, based on this alternative assumption have potential for better explaining people's actual behaviors in social decision making situations. PMID:21573055

  17. Implementation of Lamarckian concepts in a Genetic Algorithm for structure solution from powder diffraction data

    NASA Astrophysics Data System (ADS)

    Turner, Giles W.; Tedesco, Emilio; Harris, Kenneth D. M.; Johnston, Roy L.; Kariuki, Benson M.

    2000-04-01

    Previous implementations of Genetic Algorithms in direct-space strategies for structure solution from powder diffraction data have employed the operations of mating, mutation and natural selection, with the fitness of each structure based on comparison between calculated and experimental powder diffraction patterns (we define fitness as a function of weighted-profile R-factor Rwp). We report an extension to this method, in which each structure generated in the Genetic Algorithm is subjected to local minimization of Rwp with respect to structural variables. This approach represents an implementation of Lamarckian concepts of evolution, and is found to give significant improvements in efficiency and reliability.

  18. Monitoring the Impact of Solution Concepts within a Given Problematic

    NASA Astrophysics Data System (ADS)

    Cavallucci, Denis; Rousselot, François; Zanni, Cecilia

    It is acknowledged that one of the most critical issues facing today’s organizations concerns the substantial leaps required to methodologically structure innovation. Among other published work, some suggest that a complete rethinking of current practices is required. In this article, we propose a methodology aiming at providing controlled R&D choices based on a monitoring of the impact Solution Concepts provoke on a problematic situation. Initially this problematic situation is modeled in a graph form, namely a Problem Graph. It has the objective to assists R&D managers when choosing which activities to support and bring them concrete arguments to defend their choices. We postulate that by improving the robustness of such approaches we help deciders to switch from intuitive decisions (mostly built upon their past experiences, fear regarding risks, and awareness of the company’s level of acceptance of novelties) to thoroughly constructed inventive problem solving strategies. Our approach will be discussed using a computer application that illustrates our hypothesis after being tested in several industrial applications.

  19. What's Natural about Nature? Deceptive Concepts in Socio-Scientific Decision-Making

    ERIC Educational Resources Information Center

    Lindahl, Mats Gunnar; Linder, Cedric

    2015-01-01

    The conflicts between nature and nurture are brought to the fore and challenges socio-scientific decision-making in science education. The multitude of meanings of these concepts and their roles in societal discourses can impede students' development of understanding for different perspectives, e.g. on gene technology. This study problematizes…

  20. Undergraduate Students' Conceptions of Natural and Anthropogenic Climate Change

    NASA Astrophysics Data System (ADS)

    Trenbath, K. L.

    2011-12-01

    constructed definition removes human-causes from association with the word "climate change", which may influence their climate change understanding. Of the two higher achieving students, one emphasized anthropogenic climate change at the beginning of the semester, but later focused on natural climate change during his interviews. The other high achieving student included tangential environmental topics in her descriptions of climate change throughout the entire semester, thus conflating climate change's definition. These alternative definitions of climate change indicate that the learners constructed hybrid conceptions in order to incorporate class content with their prior ideas. These hybrid conceptions indicate that the students' understandings lie somewhere between misconceptions and conceptual change. Since the students demonstrated these hybrid conceptions at the end of class, perhaps more time is needed for the students to process the information. These case studies identify the gaps the professor should address for conceptual change to fully occur.

  1. Quantifying nature: ideological representations in the concept of diversity.

    PubMed

    Nikisianis, Nikos; Stamou, George P

    2011-01-01

    The conflicts around the scientific status of the concept of diversity are considered here as symptoms of hidden, socially originated, ideological representations inherent in the theoretical context of western ecology. Species diversity was coined in the 1940s, as a constant in the statistical models that described the distribution of individuals into different species and, therefore, as the expression of all the parameters that determine ecologically this distribution. The assumption of such a regular distribution is attributed to the influence of organicism and the correlated presuppositions of harmony and homeostasis. Nevertheless, as species diversity was the only unknown parameter in these models, it reversed the direction of the functions and established itself as the main variable under question. After the 1950s, the concept of species diversity was empowered by the strong impact of cybernetics and systems theories; in this context, diversity was considered as a self-regulating mechanism that assures overall stability. Diversity emerges as a natural and one-dimensional measure of community complexity, maturity, and stability. In the perspective of the arising ecological crisis, diversity--because of its property to compare and evaluate--arises as the nodal point of the new scientific/ideological fields of nature conservation and ecosystem management.

  2. Natural Orifice Surgery: Transdouglas Surgery—a New Concept

    PubMed Central

    Stark, Michael

    2008-01-01

    Background: During the 20th century, laparoscopic procedures replaced most traditional abdominal operations and achieved high-quality standards. It seemed that the optimal surgical method had been achieved; however, a new concept, which might possibly become even safer and simpler is now being developed, the concept of Natural Orifice Surgery (NOS). The existing natural openings of the body started to be used for introduction of surgical instruments for diagnostic purposes and surgical procedures, avoiding penetrating the abdominal wall. Parallel to the American Natural Orifice Surgery Consortium for Assessment and Research (NOSCAR) group, is the New European Surgical Academy (NESA) established in Berlin on June 23, 2006. It is the first European-based NOS working group with participation of scientists and surgeons from different disciplines and countries. After the published experimental achievements had been presented and discussed, the working group decided to concentrate mainly on the transvaginal/transdouglas access in women. Database: A new surgical instrument, the Transdouglas Endoscopic Device (TED) has been designed. This is a flexible multichannel instrument enabling single-entry surgical, urological, and gynecological operations. TED respects the anatomy of the pelvis. To get to the upper abdomen, an S-shaped device was designed, bending first to the front, and then backwards. For the lower abdomen, the U-shaped mode of the instrument was designed. The wide diameter of the device (35 mm) and its multichannel design enables simultaneous use of different instruments, therefore avoiding hybrid procedures. Various surgical and gynecological procedures have been successfully simulated, and the manufacturing of the device is in progress. Preclinical studies will start soon. Conclusions: Transvaginal/transdouglas surgery is expected to be a valid alternative to traditional endoscopic procedures in women. It seems that NOS will create a spectrum of innovative

  3. Metabiotics: novel idea or natural development of probiotic conception

    PubMed Central

    Shenderov, Boris A.

    2013-01-01

    Traditionally, probiotics on the base of live microorganisms are considered to be both beneficial and safe. Unfortunately, their effects may have short-term success or are absent or uncertain. Some symbiotic (probiotic) microorganisms with known beneficial health affects may cause opportunistic infections, increase incidence of allergic sensitization and autoimmune disorders, produce microecological imbalance, modify gene expression, transfer antibiotic resistant and virulence genes, cause disorders in epigenome and genome integrity, induce chromosomal DNA damage, and activate signaling pathways associated with cancer and other chronic diseases. The commercially available probiotics should be considered as a first generation means of correcting microecological disorders. Further, their development will include the selection of natural metabiotics and/or working out the synthetic (or semi-synthetic) metabiotics that will be analogies or improved copies of natural bioactives, produced by symbiotic (probiotic) microorganisms. Metabiotics are the structural components of probiotic microorganisms and/or their metabolites and/or signaling molecules with a determined (known) chemical structure that can optimize host-specific physiological functions, regulator, metabolic and/or behavior reactions connected with the activity of host indigenous microbiota. Metabiotics have some advantages because of their exact chemical structure, well dosed, very safe and long shelf-life. Thus, now metabiotics should not consider myth; they are the result of the natural evolution of probiotic conception. PMID:23990841

  4. Photodegradation of triazine herbicides in aqueous solutions and natural waters.

    PubMed

    Evgenidou, E; Fytianos, K

    2002-10-23

    The photodegradation of three triazines, atrazine, simazine, and prometryn, in aqueous solutions and natural waters using UV radiation (lambda > 290 nm) has been studied. Experimental results showed that the dark reactions were negligible. The rate of photodecomposition in aqueous solutions depends on the nature of the triazines and follows first-order kinetics. In the case of the use of hydrogen peroxide and UV radiation, a synergistic effect was observed. The number of photodegradation products detected, using FIA/MS and FIA/MS/MS techniques, suggests the existence of various degradation routes resulting in complex and interconnected pathways.

  5. The Concept of Human Nature in Three Cultures: A Developmental Approach.

    ERIC Educational Resources Information Center

    Oerter, Rolf

    This study compares the concept of human nature in Germany, Java, and the United States. The study assumes cross-cultural similarities in the formal structure of the concept of human nature, while hypothesizing variation in content, for example, in the value systems. Four components of the concept of human nature were presented (personality…

  6. The science, policy and practice of nature-based solutions: An interdisciplinary perspective.

    PubMed

    Nesshöver, Carsten; Assmuth, Timo; Irvine, Katherine N; Rusch, Graciela M; Waylen, Kerry A; Delbaere, Ben; Haase, Dagmar; Jones-Walters, Lawrence; Keune, Hans; Kovacs, Eszter; Krauze, Kinga; Külvik, Mart; Rey, Freddy; van Dijk, Jiska; Vistad, Odd Inge; Wilkinson, Mark E; Wittmer, Heidi

    2017-02-01

    In this paper, we reflect on the implications for science, policy and practice of the recently introduced concept of Nature-Based Solutions (NBS), with a focus on the European context. First, we analyse NBS in relation to similar concepts, and reflect on its relationship to sustainability as an overarching framework. From this, we derive a set of questions to be addressed and propose a general framework for how these might be addressed in NBS projects by funders, researchers, policy-makers and practitioners. We conclude that: To realise their full potential, NBS must be developed by including the experience of all relevant stakeholders such that 'solutions' contribute to achieving all dimensions of sustainability. As NBS are developed, we must also moderate the expectations placed on them since the precedent provided by other initiatives whose aim was to manage nature sustainably demonstrates that we should not expect NBS to be cheap and easy, at least not in the short-term.

  7. Constructing Concept Schemes From Astronomical Telegrams Via Natural Language Clustering

    NASA Astrophysics Data System (ADS)

    Graham, Matthew; Zhang, M.; Djorgovski, S. G.; Donalek, C.; Drake, A. J.; Mahabal, A.

    2012-01-01

    The rapidly emerging field of time domain astronomy is one of the most exciting and vibrant new research frontiers, ranging in scientific scope from studies of the Solar System to extreme relativistic astrophysics and cosmology. It is being enabled by a new generation of large synoptic digital sky surveys - LSST, PanStarrs, CRTS - that cover large areas of sky repeatedly, looking for transient objects and phenomena. One of the biggest challenges facing these is the automated classification of transient events, a process that needs machine-processible astronomical knowledge. Semantic technologies enable the formal representation of concepts and relations within a particular domain. ATELs (http://www.astronomerstelegram.org) are a commonly-used means for reporting and commenting upon new astronomical observations of transient sources (supernovae, stellar outbursts, blazar flares, etc). However, they are loose and unstructured and employ scientific natural language for description: this makes automated processing of them - a necessity within the next decade with petascale data rates - a challenge. Nevertheless they represent a potentially rich corpus of information that could lead to new and valuable insights into transient phenomena. This project lies in the cutting-edge field of astrosemantics, a branch of astroinformatics, which applies semantic technologies to astronomy. The ATELs have been used to develop an appropriate concept scheme - a representation of the information they contain - for transient astronomy using hierarchical clustering of processed natural language. This allows us to automatically organize ATELs based on the vocabulary used. We conclude that we can use simple algorithms to process and extract meaning from astronomical textual data.

  8. Nature is (a) mine: conceptions of nature in the Dutch ecogenomics community.

    PubMed

    Van der Hout, Sanne

    2014-12-01

    Every field of science, but especially biology, contains particular conceptions of nature. These conceptions are not merely epistemological or ontological, but also have normative dimensions; they provide an ethos, a framework for moral orientation. These normative dimensions, whilst often remaining 'hidden' and inarticulate, influence the way in which biologists practice their profession. In this paper, I explore what happens when different versions of these implicit normative frameworks collide. To do so, I will focus on a case study from the field of ecological genomics as it has evolved in one particular country, namely the Netherlands. During an important inaugural meeting, the director of one of the most sizeable Dutch ecogenomics centres gave a presentation in which he introduced the term 'nature mining'. Part of the audience immediately embraced the term, but others were very reluctant. This mixed response is generally explained as a culmination of growing tension about the future direction of the field: due to new funding demands, a shift had occurred from fundamental research to research more interested in 'valorisation'.In addition to this current interpretation, I will argue that the turmoil caused by the use of the term 'nature mining' also reveals a more fundamental difference between the various parties involved in the Dutch ecogenomics community. This term is part of a vocabulary that emphasises the beneficial 'goods' produced by nature. Whereas part of the audience saw no harm in this commodification of nature, others had difficulties with the reduction of nature to a reservoir to be exploited using the latest technologies. I will conclude by arguing that, although at present, the core of Dutch ecogenomics research reflects a more or less instrumental attitude towards nature, the field also harbours other interpretations of nature as a significant and meaningful order. For instance, ecogenomics might further develop the image of land as a

  9. Reuse of spent natural gas liquid sweetening solutions

    SciTech Connect

    Hahn, W.J.; McKim, M.N.; Smith, L.S.

    1995-12-01

    Partially spent caustic solutions from natural gas liquids (NGL) sweetening processes can be used as reagent for sulfur dioxide (SO{sub 2}) scrubbing facilities, reducing the costs for purchasing scrubber reagent and eliminating the costs and liabilities associated with waste disposal. This paper discusses: (1) the characteristics of typical spent NGL sweetening solutions, (2) State and Federal regulations governing the disposal of these solutions as wastes, (3) the operational variables affecting reuse of these solutions in SO{sub 2} scrubbers, (4) field and laboratory analytical data from a pilot project conducted to evaluate the reuse of a partially spent NGL sweetening solution as SO{sub 2} scrubber reagent, and (5) economic data from the pilot project. For the pilot project, a partially spent caustic NGL sweetening solution was used in place of soda ash solution as reagent in a SO{sub 2} scrubber serving two steam generators burning sour gas. Emissions testing of the scrubber demonstrated that the solution provided effective removal of oxides of sulfur (SO{sub x}) in both gaseous and particulate phases to meet permitted limits. Data from the pilot project is used in the paper to: (1) quantify SO{sub 2} scrubber performance with partially spent caustic solutions in terms of SO{sub x} removal efficiency, (2) identify the necessary modifications in scrubber operation (reagent feed rate, scrubber liquor pH and specific gravity, blowdown rate) to achieve acceptable performance using partially spent caustic solutions, and (3) describe the effect that the use of partially spent caustic solutions has on physical and chemical properties of scrubber liquor.

  10. [Mouthwash solutions with microencapsuled natural extracts: Efficiency for dental plaque and gingivitis].

    PubMed

    Vervelle, A; Mouhyi, J; Del Corso, M; Hippolyte, M-P; Sammartino, G; Dohan Ehrenfest, D M

    2010-06-01

    Mouthwash solutions are mainly used for their antiseptic properties. They currently include synthetic agents (chlorhexidine, triclosan, etc.) or essential oils (especially Listerine). Many natural extracts may also be used. These associate both antiseptic effects and direct action on host response, due to their antioxidant, immunoregulatory, analgesic, buffering, or healing properties. The best known are avocado oil, manuka oil, propolis oil, grapefruit seed extract, pycnogenol, aloe vera, Q10 coenzyme, green tea, and megamin. The development of new technologies, such as microencapsulation (GingiNat concept), may allow an in situ slow release of active ingredients during several hours, and open new perspectives for mouthwash solutions.

  11. Teaching Concepts of Natural Sciences to Foreigners through Content-Based Instruction: The Adjunct Model

    ERIC Educational Resources Information Center

    Satilmis, Yilmaz; Yakup, Doganay; Selim, Guvercin; Aybarsha, Islam

    2015-01-01

    This study investigates three models of content-based instruction in teaching concepts and terms of natural sciences in order to increase the efficiency of teaching these kinds of concepts in realization and to prove that the content-based instruction is a teaching strategy that helps students understand concepts of natural sciences. Content-based…

  12. Ammonia removal from leachate solution using natural Chinese clinoptilolite.

    PubMed

    Wang, Yuqiu; Liu, Shijun; Xu, Ze; Han, Tianwei; Chuan, Sun; Zhu, Tan

    2006-08-25

    This paper assesses the potential of natural Chinese clinoptilolite for ammonia removal from the leachate solution of sewage sludge. In batch study the effects of relevant parameters, such as contact time, initial ammonia concentration and particle size of clinoptilolite, were examined respectively. The results show that the data obtained from batch studies were fit to Langmuir and Freundlich isotherms and the Langmuir isotherms reflect more reasonable for ammonium ion uptake onto clinoptilolite; the clinoptilolite adsorption process has been proved effective, at laboratory scale, the maximum adsorption capacity of the clinoptilolite, for ammonium concentration ranging from 11.12 to 115.16 mg NH(4)-N L(-1) in leachate solution, was about 1.74 mg NH(4)-Ng(-1); the time to adsorption equilibrium was 2.5 h in leachate solution and 1.5 h more than for in NH(4)Cl synthetic solution; ammonium adsorption increased with decreasing clinoptilolite particle size; the ammonia removal capacity of clinoptilolite increased with increasing initial ammonia concentration. It is believed that as adsorption agent for NH(4)-N removal from sludge leachate, natural Chinese clinoptilolite can be feasible.

  13. Advanced control concepts. [trim solution for space shuttle

    NASA Technical Reports Server (NTRS)

    Hutton, M. F.; Friedland, B.

    1973-01-01

    The selection of a trim solution that provides the space shuttle with the highest level of performance and dynamic control in the presense of wind disturbances and bias torques due to misalignment of rocket engines is described. It was determined that engine gimballing is insufficient to provide control to trim the vehicle for headwind and sidewind disturbances, and that it is necessary to use aerodynamic surfaces in conjunction with engine gimballing to achieve trim. The algebraic equations for computing the trim solution were derived from the differential equations describing the motion of the vehicle by substituting the desired trim conditions. The general problem of showing how the trim equations are derived from the equations of motion and the mathematical forms of the performance criterion is discussed in detail, along with the general equations for studying the dynamic response of the trim solution.

  14. MODELLING OF AGRICHEMICALS IN ENVIRONMENTAL COMPARTMENTS - CONCEPTS, PROBLEMS, AND SOLUTIONS

    EPA Science Inventory

    The potential of plant protection chemicals to migrate away from application sites and expose non-target biota is of continuing interest and concern to regulatory specialists, ecotoxicologists, agriculturalists, and natural resource managers. Regulatory decisions can wait upon ne...

  15. MODELLING OF AGRICHEMICALS IN ENVIRONMENTAL COMPARTMENTS - CONCEPTS, PROBLEMS, AND SOLUTIONS

    EPA Science Inventory

    The potential of plant protection chemicals to migrate away from application sites and expose non-target biota is of continuing interest and concern to regulatory specialists, ecotoxicologists, agriculturalists, and natural resource managers. Regulatory decisions can wait upon ne...

  16. Adaptive management of natural resources: theory, concepts, and management institutions.

    Treesearch

    George H. Stankey; Roger N. Clark; Bernard T. Bormann

    2005-01-01

    This report reviews the extensive and growing literature on the concept and application of adaptive management. Adaptive management is a central element of the Northwest Forest Plan and there is a need for an informed understanding of the key theories, concepts, and frameworks upon which it is founded. Literature from a diverse range of fields including social learning...

  17. ARPA-E: Creating Practical, Affordable Natural Gas Storage Solutions

    SciTech Connect

    Boysen, Dane; Loukus, Josh; Hansen, Rita

    2014-02-24

    Allowing people to refuel natural gas vehicles at home could revolutionize the way we power our cars and trucks. Currently, our nation faces two challenges in enabling natural gas for transportation. The first is improving the way gas tanks are built for natural gas vehicles; they need to be conformable, allowing them to fit tightly into the vehicle. The second challenge is improving the way those tanks are refueled while maintaining cost-effectiveness, safety, and reliability. This video highlights two ARPA-E project teams with innovative solutions to these challenges. REL is addressing the first challenge by developing a low-cost, conformable natural gas tank with an interconnected core structure. Oregon State University and OnBoard Dynamics are addressing the second challenge by developing a self-refueling natural gas vehicle that integrates a compressor into its engine-using one of the engine's cylinders to compress gas eliminates the need for an expensive at-home refueling system. These two distinct technologies from ARPA-E's MOVE program illustrate how the Agency takes a multi-pronged approach to problem solving and innovation.

  18. ARPA-E: Creating Practical, Affordable Natural Gas Storage Solutions

    ScienceCinema

    Boysen, Dane; Loukus, Josh; Hansen, Rita

    2016-07-12

    Allowing people to refuel natural gas vehicles at home could revolutionize the way we power our cars and trucks. Currently, our nation faces two challenges in enabling natural gas for transportation. The first is improving the way gas tanks are built for natural gas vehicles; they need to be conformable, allowing them to fit tightly into the vehicle. The second challenge is improving the way those tanks are refueled while maintaining cost-effectiveness, safety, and reliability. This video highlights two ARPA-E project teams with innovative solutions to these challenges. REL is addressing the first challenge by developing a low-cost, conformable natural gas tank with an interconnected core structure. Oregon State University and OnBoard Dynamics are addressing the second challenge by developing a self-refueling natural gas vehicle that integrates a compressor into its engine-using one of the engine's cylinders to compress gas eliminates the need for an expensive at-home refueling system. These two distinct technologies from ARPA-E's MOVE program illustrate how the Agency takes a multi-pronged approach to problem solving and innovation.

  19. The interstellar conundrum: a survey of concepts and proposed solutions.

    PubMed

    Gilster, Paul A

    2005-12-01

    Once considered intractable, the problem of interstellar flight is slowly yielding to analysis. Although manned missions to the stars are exceedingly improbable in this century, the possibility of interstellar robotic probes should not be ruled out. Recent laboratory work and theoretical analysis suggest several near-term technologies that could, given the development of an adequate space-based infrastructure, provide the needed propulsion. Laser-driven lightsails offer the key advantage of leaving the fuel behind, with the laser beam focused by a large Fresnel lens in the outer Solar System. Perhaps more efficient is the use of a particle beam to boost a spacecraft by interacting with its magnetic sail, the latter a system already under intense scrutiny. Variations on "pellet" propulsion using macroscopic objects continue to surface, their mass converted to energy as they arrive at the departing starship. Interstellar flight will be both difficult and expensive, although it can no longer be considered an impossibility. This paper examines the above concepts and relates them to older ideas, such as the Bussard ramjet, that are currently out of favor. The vibrancy of interstellar flight studies is its syncretism-it was through analysis of the drag problem in fusion ramjet designs that a practical means of decelerating an interstellar probe by deployment of a magnetic sail emerged. The intermingling of such ideas offers the hope of robust hybrid concepts that may make interstellar flight a reality.

  20. Urban natural environments as nature-based solutions for improved public health - A systematic review of reviews.

    PubMed

    van den Bosch, M; Ode Sang, Å

    2017-10-01

    Increasing urbanisation, changing disease scenarios, and current predictions of climate change impacts require innovative strategies for providing healthy and sustainable cities, now and in the future. The recently coined concept, Nature-based solutions (NBS), is one such strategy referring to actions that are inspired by, supported by, or copied from nature, designed to address a range of environmental challenges. The objective with this article is to evaluate the evidence on public health benefits of exposure to natural environments and explore how this knowledge could be framed within the NBS concept. We conducted a systematic review of reviews following established methodology, including keyword search in several databases, predefined inclusion criteria, and a data extraction in accordance with the PICOS structure. We reviewed literature on associations between public health and natural environments in relation to pathways - sociobehavioural/cultural ecosystem services (e.g. stress and physical activity) and regulating ecosystem services (e.g. heat reduction) - or defined health outcomes (e.g. cardiovascular mortality). The results show that there is strong evidence for improved affect as well as on heat reduction from urban natural environments. These conditions may mediate the effect seen on cardiovascular disease (CVD)-related mortality by exposure to natural environments. By also reviewing existing literature on NBS and health, we phrase the results within the NBS context, providing guidelines on how public health and well-being could be integrated into implementation of NBS for resilient and liveable urban landscapes and health in a changing climate. Copyright © 2017. Published by Elsevier Inc.

  1. Solution of naturally-ocurring glasses in the geological environment

    NASA Technical Reports Server (NTRS)

    Glass, B. P.

    1982-01-01

    As part of a study to investigate the feasibility of putting nuclear wastes in glass containers and burying them on land or dumping them in the ocean, the amount of solution experience by naturally occurring glasses from two land sites and thirty-four deep sea sites was studied. The glasses are microtektites from three strewn fields and from the Zhamanshin impact crater. The microtektites range in age from 0.7 to 35 m.y. and have a wide range in composition. The weight percent SiO2, for example, ranges from 44.8 to 81.7. Although several criteria for determining the amount of solution were considered, most of the conclusions are based on two criteria: (1) width of cracks, and (2) elevation of silica rich inclusions above the adjacent microtektite surface. All the measurements were made on scanning electron microscope photomicrographs of the microtektites.

  2. Brazil-Bolivia natural gas project challenges and solutions

    SciTech Connect

    Costa, A.S.C.

    1993-12-31

    PETROBRAS, the Brazilian/International Integrated Oil and Gas Company, is leading US$ 4 billion natural gas project. The goal of this paper is to identify Project challenges and propose solutions. It starts with fundamentals. Natural gas` share in Brazilian primary energy demand is only 2%. Economic aspects and environmental concerns, however, are changing this picture. For the Bolivian economy to be linked to a relatively huge market, in the long-term, is certainly a suitable decision. Besides, this Project will promote regional integration, within and outside Marcosur economies. Reserves, market data and economics give support to a feasible Project Financial structure is the main challenge. INTERGAS, a new subsidiary of PETROBRAS is opened for 49% stock to private sector participation. As an integrated Project, many opportunities will be generated during construction and operation. E&P, pipeline and downstream investments could bring different investors to different sectors.

  3. School Students' Conceptions about Biodiversity Loss: Definitions, Reasons, Results and Solutions

    NASA Astrophysics Data System (ADS)

    Kilinc, Ahmet; Yeşiltaş, Namik Kemal; Kartal, Tezcan; Demiral, Ümit; Eroğlu, Baris

    2013-12-01

    Environmental degradation stemming from anthropocentric causes threatens the biodiversity more than ever before, leading scholars to warn governments about the impending consequences of biodiversity loss (BL). At this point, it is of great importance to study the public's conceptions of BL in order to identify significant educational implications. However, a review of the literature reveals a relatively small body of research about the public understanding of BL. In this qualitative study, we thus strived to elicit Turkish school students' conceptions about BL using a written questionnaire including open-ended questions with respect to the definition of biodiversity as well as reasons for, results of and solutions to BL. The sample consisted of 245 school students in a relatively small city. A two-staged content analysis was run on the responses. The results showed that school students most commonly preferred species-focused definitions of biodiversity and understood BL through such various conceptual patterns as, `balance of nature', `forest', `global warming', `hunting' and `indirect conservation'. At the end of the paper, the possible educational implications and future perspectives were discussed.

  4. High School Biology Students' Transfer of the Concept of Natural Selection: A Mixed-Methods Approach

    ERIC Educational Resources Information Center

    Pugh, Kevin J.; Koskey, Kristin L. K.; Linnenbrink-Garcia, Lisa

    2014-01-01

    The concept of natural selection serves as a foundation for understanding diverse biological concepts and has broad applicability to other domains. However, we know little about students' abilities to transfer (i.e. apply to a new context or use generatively) this concept and the relation between students' conceptual understanding and transfer…

  5. High School Biology Students' Transfer of the Concept of Natural Selection: A Mixed-Methods Approach

    ERIC Educational Resources Information Center

    Pugh, Kevin J.; Koskey, Kristin L. K.; Linnenbrink-Garcia, Lisa

    2014-01-01

    The concept of natural selection serves as a foundation for understanding diverse biological concepts and has broad applicability to other domains. However, we know little about students' abilities to transfer (i.e. apply to a new context or use generatively) this concept and the relation between students' conceptual understanding and transfer…

  6. Photosensitized degradation of amoxicillin in natural organic matter isolate solutions.

    PubMed

    Xu, Haomin; Cooper, William J; Jung, Jinyoung; Song, Weihua

    2011-01-01

    Amoxicillin is a widely used antibiotic and has been detected in natural waters. Its environmental fate is in part determined by hydrolysis, and, direct and indirect photolysis. The hydrolysis rate in distilled water and water to which five different isolated of dissolved organic matter (DOM) was added, were evaluated. In the five different DOM solutions hydrolysis accounted for 5-18% loss of amoxicillin. Direct and indirect photolysis rates were determined using a solar simulator and it appeared that indirect photolysis was the dominant loss mechanism. Direct photolysis, in a solar simulator, accounted for 6-21% loss of amoxicillin in the simulated natural waters. The steady-state concentrations of singlet oxygen, (1)ΔO(2) (∼10(-13) M) and hydroxyl radical, •OH (∼10(-17) M) were obtained in aqueous solutions of five different dissolved organic matter samples using a solar simulator. The bimolecular reaction rate constant of (1)ΔO(2) with amoxicillin was measured in the different solutions, k(ΔO(2)) = 1.44 × 10(4) M(-1) s(-1). The sunlight mediated amoxicillin loss rate with (1)ΔO(2) (∼10(-9) s(-1)), and with •OH (∼10(-7) s(-1)), were also determined for the different samples of DOM. While (1)ΔO(2) only accounted for 0.03-0.08% of the total loss rate, the hydroxyl radical contributed 10-22%. It appears that the direct reaction of singlet and triplet excited state DOM ((3)DOM(∗)) with amoxicillin accounts for 48-74% of the loss of amoxicillin. Furthermore, the pseudo first-order photodegradation rate showed a positive correlation with the sorption of amoxicillin to DOM, which further supported the assumption that excited state DOM∗ plays a key role in the photochemical transformation of amoxicillin in natural waters. This is the first study to report the relative contribution of all five processes to the fate of amoxicillin in aqueous solution.

  7. Framework for city planning including nature-based solutions (NBS)

    NASA Astrophysics Data System (ADS)

    Alkan Olsson, Johanna; Sörensen, Johanna; Persson, Anna

    2017-04-01

    A common strategy to lower the demand for intense land use and energy consumption is the densification of urban areas. While this might be a fruitful strategy for its main objectives, one concern is that space for green areas and surface water will be decreased. Therefore, densification increases the need of strategies to develop and increase the quality of nature-based solutions (NBS) in urban areas. Smarter city planning strategies are needed, both for maintenance of existing NBS and for implementation of NBS in new developments. City planning must be based on well-evaluated solutions, which in turn must be based on a decent data material for each city. Today there is however several type of difficulties related to adequate provision of data to ensure a better implementation of NBS. The challenges arise from issues such as lack of information about for example costs of maintenance of existing NBS, citizens' perceptions and preferred use of NBS to difficulties of a more technical character such as the format of available GIS information. This study focuses on this information gap regarding NBS that persists in most cities today. The project aims to develop a framework that can help city planners to overcome the gaps and facilitate the inclusion of high quality nature-based solutions where developed or maintained. The framework, which is detailed by identifying information gaps through a literature review and selected interviews with urban planners and experts in the area of NBS, is based on the idea that well-structured and user-friendly data supporting city-planning strategies are essential to facilitate the implementation of NBS. What can be understood as well structured and user-friendly data depends on the goals and needs expressed in the strategic plans, which mean that there is a need for a close interaction between the development data and the strategic political goals expressed in the plans.

  8. Design Conception of a Solution Ion Source Based Particle Accelerator

    NASA Astrophysics Data System (ADS)

    Ashis, Das

    2004-05-01

    Particle accelerators till date have been based on several ion source principles such as thermal ionization, stripping etc. Such methods of ion source enabling is very limited by high temperature of ionization required in cases of very heavy ions generation. Heavy ions speeding in accelerator may lead to experiments with such ions in both accelerators and colliders, that is believed capable of opening new regimes of particle accelerator studies that is very heavy very heavy collision. Literature indicate that many yet-unknown mysteries of atomic and subnuclear Physics, creation and fate of Universe, new element synthesis all lie in this regime of investigation. In this paper, I outline a simpler and less energetic manner of creating, particularly, speeding very heavy ions using a solution ion stripping source such as with liquid ammonia which has ability to dissolve many heavy metals in form of ammonia-metal ion clusters, that can be led to a specially designed accelerator chamber as detailed in the paper. It is surprising indeed why such easy road to ions source generation was not conceived by particle accelerator Physicists earlier.

  9. Fuels Containing Methane of Natural Gas in Solution

    NASA Technical Reports Server (NTRS)

    Sullivan, Thomas A.

    2004-01-01

    While exploring ways of producing better fuels for propulsion of a spacecraft on the Mars sample return mission, a researcher at Johnson Space Center (JSC) devised a way of blending fuel by combining methane or natural gas with a second fuel to produce a fuel that can be maintained in liquid form at ambient temperature and under moderate pressure. The use of such a blended fuel would be a departure for both spacecraft engines and terrestrial internal combustion engines. For spacecraft, it would enable reduction of weights on long flights. For the automotive industry on Earth, such a fuel could be easily distributed and could be a less expensive, more efficient, and cleaner-burning alternative to conventional fossil fuels. The concept of blending fuels is not new: for example, the production of gasoline includes the addition of liquid octane enhancers. For the future, it has been commonly suggested to substitute methane or compressed natural gas for octane-enhanced gasoline as a fuel for internal-combustion engines. Unfortunately, methane or natural gas must be stored either as a compressed gas (if kept at ambient temperature) or as a cryogenic liquid. The ranges of automobiles would be reduced from their present values because of limitations on the capacities for storage of these fuels. Moreover, technical challenges are posed by the need to develop equipment to handle these fuels and, especially, to fill tanks acceptably rapidly. The JSC alternative to provide a blended fuel that can be maintained in liquid form at moderate pressure at ambient temperature has not been previously tried. A blended automotive fuel according to this approach would be made by dissolving natural gas in gasoline. The autogenous pressure of this fuel would eliminate the need for a vehicle fuel pump, but a pressure and/or flow regulator would be needed to moderate the effects of temperature and to respond to changing engine power demands. Because the fuel would flash as it entered engine

  10. Effect of solute nature on the polyamorphic transition in glassy polyol aqueous solutions

    NASA Astrophysics Data System (ADS)

    Suzuki, Yoshiharu

    2017-08-01

    I examined the polyamorphic behavior of glassy dilute aqueous solutions of polyols (ethylene glycol, glycerol, meso-erythritol, xylitol, and D-sorbitol) under pressure at low temperatures. Although the volume change of the glassy aqueous solution varied continuously against pressure, the rate of the volume change appeared to vary discontinuously at the onset pressure of the gradual polyamorphic transition. It is thought that low-density liquid-like solvent water and high-density liquid-like solvent water coexist during the transition. Moreover, the existence of a solute induces the shift of polyamorphic transition to the lower-pressure side. The effect of a solute on the polyamorphic transition becomes larger in the order ethylene glycol, glycerol, meso-erythritol, xylitol, and D-sorbitol. Therefore, the solute can become a variable controlling the polyamorphic state of liquid water. This experimental result suggests that the metastable-equilibrium phase boundary between the low-density and the high-density amorphs for pure water is likely to be located at 0.22-0.23 GPa at about 150 K, which is slightly larger than the previously estimated pressure. Moreover, the solute-nature dependence on the polyamorphic transition seems to connect to that on the homogeneous nucleation temperature of polyol aqueous solution at ambient pressure. The region in which a low-density liquid appears coincides with the region in which the nucleus of ice Ih appears, suggesting that the formation of a low-density liquid is a precursory phenomenon of the nucleation of ice Ih.

  11. The restoration experience: volunteers' motives, values, and concepts of nature

    Treesearch

    Herbert W. Schroeder

    2000-01-01

    The last several years have brought significant changes in the management of public lands and natural resources in the United States. As a result of debates over management practices, shifts in the goods and services demanded by the public, and evelopment in scientific knowledge, there has emerged a general philosophical shift toward managing natural environmnets as...

  12. Teaching the Nature of Science through the Concept of Living

    ERIC Educational Resources Information Center

    Kim, Byoung-Sug; McKinney, Mary

    2007-01-01

    By virtue of its connection with scientific literacy, the nature of science has been considered essential subject matter for the science curriculum. With this in mind, seventh-grade students were introduced to three aspects of the nature of science: (1) the distinction between observation and inference, (2) the subjective, and (3) the tentative…

  13. Teachers' Conceptions and Misconceptions Concerning Three Natural Phenomena

    ERIC Educational Resources Information Center

    Kikas, Eve

    2004-01-01

    This study focuses on the conceptions of trainee, primary, and subject teachers about three phenomena: the motion of objects, seasonal changes, and aggregate changes of matter. A total of 198 participants completed a questionnaire concerning two types of tasks. First, teachers evaluated the adequacy of a given explanation as compared to their…

  14. Tsunami Simulators in Physical Modelling - Concept to Practical Solutions

    NASA Astrophysics Data System (ADS)

    Chandler, Ian; Allsop, William; Robinson, David; Rossetto, Tiziana; McGovern, David; Todd, David

    2017-04-01

    Whilst many researchers have conducted simple 'tsunami impact' studies, few engineering tools are available to assess the onshore impacts of tsunami, with no agreed methods available to predict loadings on coastal defences, buildings or related infrastructure. Most previous impact studies have relied upon unrealistic waveforms (solitary or dam-break waves and bores) rather than full-duration tsunami waves, or have used simplified models of nearshore and over-land flows. Over the last 10+ years, pneumatic Tsunami Simulators for the hydraulic laboratory have been developed into an exciting and versatile technology, allowing the forces of real-world tsunami to be reproduced and measured in a laboratory environment for the first time. These devices have been used to model generic elevated and N-wave tsunamis up to and over simple shorelines, and at example coastal defences and infrastructure. They have also reproduced full-duration tsunamis including Mercator 2004 and Tohoku 2011, both at 1:50 scale. Engineering scale models of these tsunamis have measured wave run-up on simple slopes, forces on idealised sea defences, pressures / forces on buildings, and scour at idealised buildings. This presentation will describe how these Tsunami Simulators work, demonstrate how they have generated tsunami waves longer than the facilities within which they operate, and will present research results from three generations of Tsunami Simulators. Highlights of direct importance to natural hazard modellers and coastal engineers include measurements of wave run-up levels, forces on single and multiple buildings and comparison with previous theoretical predictions. Multiple buildings have two malign effects. The density of buildings to flow area (blockage ratio) increases water depths and flow velocities in the 'streets'. But the increased building densities themselves also increase the cost of flow per unit area (both personal and monetary). The most recent study with the Tsunami

  15. Australian Secondary School Students' Concepts Regarding the Nature of Science.

    ERIC Educational Resources Information Center

    Griffiths, Alan K.; Barman, Charles R.

    1993-01-01

    Describes a study in which secondary students (N=32) were interviewed to determine their understanding of the nature of scientific knowledge. Presents some of the strengths and weaknesses of these views and provides cross-cultural comparisons. (DDR)

  16. Developing an instrument for assessing students' concepts of the nature of technology

    NASA Astrophysics Data System (ADS)

    Liou, Pey-Yan

    2015-05-01

    Background:The nature of technology has been rarely discussed despite the fact that technology plays an essential role in modern society. It is important to discuss students' concepts of the nature of technology, and further to advance their technological literacy and adaptation to modern society. There is a need to assess high school students' concepts of the nature of technology. Purpose:This study aims to engage in discourse on students' concepts of the nature of technology based on a proposed theoretical framework. Moreover, another goal is to develop an instrument for measuring students' concepts of the nature of technology. Sample:Four hundred and fifty-five high school students' perceptions of technology were qualitatively analyzed. Furthermore, 530 students' responses to a newly developed questionnaire were quantitatively analyzed in the final test. Design and method:First, content analysis was utilized to discuss and categorize students' statements regarding technology and its related issues. The Student Concepts of the Nature of Technology Questionnaire was developed based on the proposed theoretical framework and was supported by the students' qualitative data. Finally, exploratory factor analysis and reliability analysis were applied to determine the structure of the items and the internal consistency of each scale. Results:Through a process of instrument development, the Student Concepts of the Nature of Technology Questionnaire was shown to be a valid and reliable tool for measuring students' concepts of the nature of technology. This newly developed questionnaire is composed of 29 items in six scales, namely 'technology as artifacts,' 'technology as an innovation change,' 'the current role of technology in society,' 'technology as a double-edged sword,' 'technology as a science-based form,' and 'history of technology.' Conclusions:The Student Concepts of the Nature of Technology Questionnaire has been confirmed as a reasonably valid and reliable

  17. The Nature of Science in Science Curricula: Methods and Concepts of Analysis

    ERIC Educational Resources Information Center

    Ferreira, Sílvia; Morais, Ana M.

    2013-01-01

    The article shows methods and concepts of analysis of the nature of science in science curricula through an exemplary study made in Portugal. The study analyses the extent to which the message transmitted by the Natural Science curriculum for Portuguese middle school considers the nature of science. It is epistemologically and sociologically…

  18. The Nature of Science in Science Curricula: Methods and Concepts of Analysis

    ERIC Educational Resources Information Center

    Ferreira, Sílvia; Morais, Ana M.

    2013-01-01

    The article shows methods and concepts of analysis of the nature of science in science curricula through an exemplary study made in Portugal. The study analyses the extent to which the message transmitted by the Natural Science curriculum for Portuguese middle school considers the nature of science. It is epistemologically and sociologically…

  19. Natural resource valuation: A primer on concepts and techniques

    SciTech Connect

    Ulibarri, C.A.; Wellman, K.F.

    1997-07-01

    Natural resource valuation has always had a fundamental role in the practice of cost-benefit analysis of health, safety, and environmental issues. Today, this role is becoming all the more apparent in the conduct of natural resource damage assessments (NRDA) and cost-benefit analyses of environmental restoration (ER) and waste management (WM) activities. As such, environmental professionals are more interested in how natural resource values are affected by ER and WM activities. This professional interest extends to the use of NRDA values as measures of liability and legal causes of action under such environmental status as the Clean Water Act (CWA); the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA, as amended); and the Oil Pollution Act (OPA) of 1990. Also, environmental professionals are paying closer attention to NRDA values in cost-benefit analyses of risk and pollution-abatement standards, and in meeting environmental and safety standards - for achievable (ALARA). This handbook reviews natural resource valuation techniques that may be applied to resources at DOE sites within the foregoing contexts.

  20. Turkish Pupils' Conceptions of the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Boz, Yezdan

    2006-01-01

    The purpose of this research study is to explore year 6, 8 & 11 (13, 15 and 17 years old respectively) Turkish pupils' views about the particulate nature of matter within the context of phase changes. About 300 pupils participated in the study. Questionnaires distributed to year 6, 8 and 11 pupils included 6-item open-ended questions about (a)…

  1. Turkish Pupils' Conceptions of the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Boz, Yezdan

    2006-01-01

    The purpose of this research study is to explore year 6, 8 & 11 (13, 15 and 17 years old respectively) Turkish pupils' views about the particulate nature of matter within the context of phase changes. About 300 pupils participated in the study. Questionnaires distributed to year 6, 8 and 11 pupils included 6-item open-ended questions about (a)…

  2. Applying the dark diversity concept to nature conservation.

    PubMed

    Lewis, Rob J; de Bello, Francesco; Bennett, Jonathan A; Fibich, Pavel; Finerty, Genevieve E; Götzenberger, Lars; Hiiesalu, Inga; Kasari, Liis; Lepš, Jan; Májeková, Maria; Mudrák, Ondřej; Riibak, Kersti; Ronk, Argo; Rychtecká, Terezie; Vitová, Alena; Pärtel, Meelis

    2017-02-01

    Linking diversity to biological processes is central for developing informed and effective conservation decisions. Unfortunately, observable patterns provide only a proportion of the information necessary for fully understanding the mechanisms and processes acting on a particular population or community. We suggest conservation managers use the often overlooked information relative to species absences and pay particular attention to dark diversity (i.e., a set of species that are absent from a site but that could disperse to and establish there, in other words, the absent portion of a habitat-specific species pool). Together with existing ecological metrics, concepts, and conservation tools, dark diversity can be used to complement and further develop conservation prioritization and management decisions through an understanding of biodiversity relativized by its potential (i.e., its species pool). Furthermore, through a detailed understanding of the population, community, and functional dark diversity, the restoration potential of degraded habitats can be more rigorously assessed and so to the likelihood of successful species invasions. We suggest the application of the dark diversity concept is currently an underappreciated source of information that is valuable for conservation applications ranging from macroscale conservation prioritization to more locally scaled restoration ecology and the management of invasive species.

  3. Elucidating concepts in drug design through taste with natural and artificial sweeteners.

    PubMed

    Lipchock, James M; Lipchock, Sarah V

    2016-11-12

    Fundamental concepts in biochemistry important for drug design often lack connection to the macroscopic world and can be difficult for students to grasp, particularly those in introductory science courses at the high school and college level. Educational research has shown that multisensory teaching facilitates learning, but teaching at the high school and college level is almost exclusively limited to the visual and auditory senses. This approach neglects the lifetime of experience our students bring to the classroom in the form of taste perception and makes our teaching less supportive of those with sensory impairment. In this article, we outline a novel guided-inquiry activity that utilizes taste perception for a series of natural and artificial sweetener solutions to introduce the concepts of substrate affinity and selectivity in the context of drug design. The findings from this study demonstrate clear gains in student knowledge, as well as an increase in enthusiasm for the fields of biochemistry and drug design. © 2016 by The International Union of Biochemistry and Molecular Biology, 44(6):550-554, 2016. © 2016 The International Union of Biochemistry and Molecular Biology.

  4. Zeta potential of artificial and natural calcite in aqueous solution.

    PubMed

    Al Mahrouqi, Dawoud; Vinogradov, Jan; Jackson, Matthew D

    2017-02-01

    Despite the broad range of interest and applications, controls on calcite surface charge in aqueous solution, especially at conditions relevant to natural systems, remain poorly understood. The primary data source to understand calcite surface charge comprises measurements of zeta potential. Here we collate and review previous measurements of zeta potential on natural and artificial calcite and carbonate as a resource for future studies, compare and contrast the results of these studies to determine key controls on zeta potential and where uncertainties remain, and report new measurements of zeta potential relevant to natural subsurface systems. The results show that the potential determining ions (PDIs) for the carbonate mineral surface are the lattice ions Ca(2+), Mg(2+) and CO3(2-). The zeta potential is controlled by the concentration-dependent adsorption of these ions within the Stern layer, primarily at the Outer Helmholtz Plane (OHP). Given this, the Iso-Electric Point (IEP) at which the zeta potential is zero should be expressed as pCa (or pMg). It should not be reported as pH, similar to most metal oxides. The pH does not directly control the zeta potential. Varying the pH whilst holding pCa constant yields constant zeta potential. The pH affects the zeta potential only by moderating the equilibrium pCa for a given CO2 partial pressure (pCO2). Experimental studies that appear to yield a systematic relationship between pH and zeta potential are most likely observing the relationship between pCa and zeta potential, with pCa responding to the change in pH. New data presented here show a consistent linear relationship between equilibrium pH and equilibrium pCa or pMg irrespective of sample used or solution ionic strength. The surface charge of calcite is weakly dependent on pH, through protonation and deprotonation reactions that occur within a hydrolysis layer immediately adjacent to the mineral surface. The Point of Zero Charge (PZC) at which the surface

  5. The Concept of Race on Campus: Exploring the Nature of College Students' Racial Conceptions

    ERIC Educational Resources Information Center

    Johnston, Marc P.

    2014-01-01

    Despite the widely documented benefits associated with racial diversity in higher education, less is known about why and how race matters. A potential answer may be found in how students conceptualize race. This qualitative study explores students' underlying racial conceptions, which have been shown to influence various attitudes and…

  6. Registered nurses' constructed meaning of concepts of solution and their use in clinical practice

    NASA Astrophysics Data System (ADS)

    Wilkes, Lesley M.; Batts, Judith E.

    1991-12-01

    Since the introduction of nursing into tertiary institutions in Australia in 1975, there has been increasing interest in the teaching of physical science to nurses. Various courses in physical science for nurse students have been developed. They vary in length and content but there is agreement that concepts taught should be closely related to nursing applications. The choice of relevant concepts tends to be made by individual curriculum developers. This paper reports an examination of the use of physical science concepts and their relevance from the perspective of registered nurses practising in general ward areas. Inherent in this study is the premise that for registered nurses to have ideas of the physical science underlying their practice they must have constructed meaning first for these concepts. Specific chemical concepts related to solutions are discussed in these terms.

  7. Segregation of solutes and gases in experimental freezing of dilute solutions: implications for natural glacial systems

    NASA Astrophysics Data System (ADS)

    Killawee, J. A.; Fairchild, I. J.; Tison, J.-L.; Janssens, L.; Lorrain, R.

    1998-12-01

    Low ionic strength waters containing significant calcium and bicarbonate are common in nature, but little literature exists on their behaviour during freezing. Modelling indicates that freezing-induced concentration of solutes (in a closed-system) would lead to progressive increase in calcite saturation index, despite rising partial pressure of CO 2 (PCO 2), but the consequences of CaCO 3 precipitation for the distribution of matter between solid, liquid, and gas phases required experimental investigation. We studied the effects of variations in the rate of advance of an ice-water interface and in the initial degree of saturation for calcite on the behaviour of the system. Downward growth of ice in a 24-cm diameter cylindrical vessel was achieved at a constant linear rate of 3 or 8 mm/h by the progressive cooling of an overlying alcohol reservoir, and the expansion of volume accommodated by regular water sampling through side ports, together with a small expansion chamber. Initial air-saturated solutions (initial PCO 2 in the range 10 -3 to 10 -3.2) were prepared to reflect a range from strongly undersaturated to supersaturated for calcite. Comparative blank experiments were run using deionized water. Ice growth led to enrichment in solutes at the ice-water interface and the creation of a diffusive boundary layer, calculated to be 0.6 mm thick, truncated below by convecting fluid. The first-formed ice (stage 1), was relatively solute-rich because of initial rapid ice nucleation. Where solutions were not strongly supersaturated for calcite this was followed by formation of a solute-poor (stage 2) ice. Ice-interface water segregation coefficients of stage 2 ice were calculated to be 0.0004-0.003 for various solute ions. The relative magnitude of segregation coefficients (Mg 2+ > Ca 2+ > Sr 2+) is attributed to interstitial incorporation (coupled with HCO 3-) in the ice lattice, and controlled by ion size. Air bubbles nucleated once nitrogen supersaturation had

  8. Natural resource validation: A primer on concepts and techniques

    SciTech Connect

    Ulibarri, C.A.; Wellman, K.F.

    1997-07-01

    Natural resource valuation has always had a fundamental role in the practice of cost-benefit analysis of health, safety, and environmental issues. The authors provide an objective overview of resource valuation techniques and describe their potential role in environmental restoration/waste management (ER/WM) activities at federal facilities. This handbook considers five general classes of valuation techniques: (1) market-based techniques, which rely on historical information on market prices and transactions to determine resource values; (2) nonmarket techniques that rely on indirect estimates of resource values; (3) nonmarket techniques that are based on direct estimates of resource values; (4) cross-cutting valuation techniques, which combine elements of one or more of these methods; and (5) ecological valuation techniques used in the emerging field of ecological economics. The various valuation techniques under consideration are described by highlighting their applicability in environmental management and regulation. The handbook also addresses key unresolved issues in the application of valuation techniques generally, including discounting future values, incorporating environmental equity concerns, and concerns over the uncertainties in the measurement of natural resource values and environmental risk.

  9. Arguments about the nature of concepts: Symbols, embodiment, and beyond.

    PubMed

    Mahon, Bradford Z; Hickok, Gregory

    2016-08-01

    How are the meanings of words, events, and objects represented and organized in the brain? This question, perhaps more than any other in the field, probes some of the deepest and most foundational puzzles regarding the structure of the mind and brain. Accordingly, it has spawned a field of inquiry that is diverse and multidisciplinary, has led to the discovery of numerous empirical phenomena, and has spurred the development of a wide range of theoretical positions. This special issue brings together the most recent theoretical developments from the leaders in the field, representing a range of viewpoints on issues of fundamental significance to a theory of meaning representation. Here we introduce the special issue by way of pulling out some key themes that cut across the contributions that form this issue and situating those themes in the broader literature. The core issues around which research on conceptual representation can be organized are representational format, representational content, the organization of concepts in the brain, and the processing dynamics that govern interactions between the conceptual system and sensorimotor representations. We highlight areas in which consensus has formed; for those areas in which opinion is divided, we seek to clarify the relation of theory and evidence and to set in relief the bridging assumptions that undergird current discussions.

  10. Different Conceptions of the Nature of Science among Preservice Elementary Teachers of Two Countries

    ERIC Educational Resources Information Center

    Park, Do-Yong; Lee, Yong Bok

    2009-01-01

    This study examined the differences of the nature of science (NOS) conceptions portrayed by preservice teachers in Korea (N = 42) and the United States (N = 50). We conducted a survey of preservice elementary science teachers' NOS conceptions followed by interviews in both countries to further investigate their viewpoints. The NOS domains of this…

  11. Exploring South African High School Teachers' Conceptions of the Nature of Scientific Inquiry: A Case Study

    ERIC Educational Resources Information Center

    Dudu, Washington T.

    2014-01-01

    The paper explores conceptions of the nature of scientific inquiry (NOSI) held by five teachers who were purposively and conveniently sampled. Teachers' conceptions of the NOSI were determined using a Probes questionnaire. To confirm teachers' responses, a semi-structured interview was conducted with each teacher. The Probes questionnaire was…

  12. Pluralities of place: A user's guide to place concepts, theories, and philosophies in natural resource management

    Treesearch

    Daniel R. Williams

    2008-01-01

    Place ideas are capturing increasing attention in recreation and natural resource management. But there are important and sometimes incompatible differences among the various concepts. In this paper I describe some of the reasons for the growing interest in place concepts and distinguish between four basic approaches: attitude, meaning, ethical, and political. My aim...

  13. Preservice Teachers' Classroom Practice and Their Conceptions of the Nature of Science.

    ERIC Educational Resources Information Center

    Mellado, Vicente

    1997-01-01

    Describes research conducted with student teachers of elementary and secondary science education. Analyzes and compares the preservice teachers' conceptions of science with their classroom practices when teaching a science lesson. Results indicate that there is no correspondence between student teacher conceptions of the nature of science and…

  14. Technology Knowledge: High School Science Teachers' Conceptions of the Nature of Technology

    ERIC Educational Resources Information Center

    Waight, Noemi

    2014-01-01

    In-depth interviews guided by video elicitations examined 30 high school science teachers' conceptions of technology and by extension how these conceptions reflected dimensions of nature of technology. Altogether, 64% of the teachers characterized their schools and departments as aggressive-moderate adopters with generous access and support…

  15. Technology Knowledge: High School Science Teachers' Conceptions of the Nature of Technology

    ERIC Educational Resources Information Center

    Waight, Noemi

    2014-01-01

    In-depth interviews guided by video elicitations examined 30 high school science teachers' conceptions of technology and by extension how these conceptions reflected dimensions of nature of technology. Altogether, 64% of the teachers characterized their schools and departments as aggressive-moderate adopters with generous access and support…

  16. Investigating the Relationship between Teachers' Nature of Science Conceptions and Their Practice of Inquiry Science

    ERIC Educational Resources Information Center

    Atar, Hakan Yavuz; Gallard, Alejandro

    2011-01-01

    In addition to recommending inquiry as the primary approach to teaching science, developers of recent reform efforts in science education have also strongly suggested that teachers develop a sound understanding of the nature of science. Most studies on teachers' NOS conceptions and inquiry beliefs investigated these concepts of teachers' NOS…

  17. Natural and artificial hyperimmune solutions: Impact on health in puppies.

    PubMed

    Mila, H; Grellet, A; Mariani, C; Feugier, A; Guard, B; Suchodolski, J; Steiner, J; Chastant-Maillard, S

    2017-04-01

    Colostrum and milk are complex mammary secretions providing the puppy with many nutritional and immunological factors, which play a crucial role for its correct development and survival. In the case of colostrum and/or milk intake deficiency, puppies are at increased risk of infectious diseases. This work reviews the various nutritional hyperimmune supplementations proposed to provide a passive immune protection and to positively impact puppies' health. Some strategies rely on canine immunoglobulins: canine colostrum banking and canine serum/plasma supplementation. Others involve heterologous sources of antibodies and other immune factors: bovine colostrum or hyperimmune egg powder. Among the different solutions evaluated from birth to weaning, canine plasma and hyperimmune egg powder showed promising beneficial effect on puppies' health. Canine plasma seems to positively impact not only growth (increased growth during the neonatal period), but also digestive health (higher species richness of intestinal microbiota) and the general health (tendency of lower morbidity). Puppies supplemented with hyperimmune egg powder presented increased neonatal growth and decreased risk of canine parvovirus infection. Nevertheless, natural canine maternal colostrum and milk ingestion remains the optimal guarantee for puppies' health and survival, as a source of immunity, energy and growth factors. © 2016 Blackwell Verlag GmbH.

  18. Categorization of novel stimuli in well-known natural concepts: a case study.

    PubMed

    Storms, G; De Boeck, P; Ruts, W

    2001-06-01

    In this study, we investigated to what extent exemplar-based and prototype predictors can be applied to predicting categorization in natural language concepts. Participants categorized novel tropical foods into two well-known natural language concepts: fruits and vegetables. The results indicate that both the prototype predictors and the exemplar predictors contribute significantly in accounting for the categorization choices but that the contribution of the prototype predictor comes from just a limited number of features.

  19. Investigating the Effectiveness of an Analogy Activity in Improving Students' Conceptual Change for Solution Chemistry Concepts

    ERIC Educational Resources Information Center

    Calik, Muammer; Ayas, Alipasa; Coll, Richard K.

    2009-01-01

    This paper reports on an investigation on the use of an analogy activity and seeks to provide evidence of whether the activity enables students to change alternative conceptions towards views more in accord with scientific views for aspects of solution chemistry. We were also interested in how robust any change was and whether these changes in…

  20. Multiple Solutions Approach (MSA): Conceptions and Practices of Primary School Teachers in Ghana

    ERIC Educational Resources Information Center

    Nabie, Michael Johnson; Raheem, Kolawole; Agbemaka, John Bijou; Sabtiwu, Rufai

    2016-01-01

    The study explored the curriculum guidelines and primary school teachers' conceptions and practices of the Multiple Solutions Approach (MSA) in teaching mathematics using basic qualitative research design. Informal conversation interviews (ICIs), observations, video and document analyses were used to collect data. Participants included a purposive…

  1. Investigating the Effectiveness of an Analogy Activity in Improving Students' Conceptual Change for Solution Chemistry Concepts

    ERIC Educational Resources Information Center

    Calik, Muammer; Ayas, Alipasa; Coll, Richard K.

    2009-01-01

    This paper reports on an investigation on the use of an analogy activity and seeks to provide evidence of whether the activity enables students to change alternative conceptions towards views more in accord with scientific views for aspects of solution chemistry. We were also interested in how robust any change was and whether these changes in…

  2. On the Concept of Information and Its Role in Nature

    NASA Astrophysics Data System (ADS)

    Roederer, Juan G.

    2003-03-01

    In this article we address some fundamental questions concerning information: Can the existing laws of physics adequately deal with the most striking property of information, namely to cause specific changes in the structure and energy flows of a complex system, without the information in itself representing fields, forces or energy in any of their characteristic forms? Or is information irreducible to the laws of physics and chemistry? Are information and complexity related concepts? Does the Universe, in its evolution, constantly generate new information? Or are information and information-processing exclusive attributes of living systems, related to the very definition of life? If that were the case, what happens with the physical meanings of entropy in statistical mechanics or wave function in quantum mechanics? How many distinct classes of information and information processing do exist in the biological world? How does information appear in Darwinian evolution? Does the human brain have unique properties or capabilities in terms of information processing? In what ways does information processing bring about human self-consciousness? We shall introduce the meaning of "information" in a way that is detached from human technological systems and related algorithms and semantics, and that is not based on any mathematical formula. To accomplish this we turn to the concept of interaction as the basic departing point, and identify two fundamentally different classes, with information and information-processing appearing as the key discriminator: force-field driven interactions between elementary particles and ensembles of particles in the macroscopic physical domain, and information-based interactions between certain kinds of complex systems that form the biological domain. We shall show that in an abiotic world, information plays no role; physical interactions just happen, they are driven by energy exchange between the interacting parts and do not require any

  3. Natural conception rates in subfertile couples following fertility awareness training.

    PubMed

    Frank-Herrmann, P; Jacobs, C; Jenetzky, E; Gnoth, C; Pyper, C; Baur, S; Freundl, G; Goeckenjan, M; Strowitzki, T

    2017-04-01

    To analyze cumulative pregnancy rates of subfertile couples after fertility awareness training. A prospective observational cohort study followed 187 subfertile women, who had received training in self-observation of the fertile phase of the menstrual cycle with the Sensiplan method, for 8 months. The women, aged 21-47 years, had attempted to become pregnant for 3.5 years on average (range 1-8 years) before study entry. Amenorrhea, known tubal occlusion and severe male factor had been excluded. An additional seven women, who had initially been recruited, became pregnant during the cycle immediately prior to Sensiplan training: this is taken to be the spontaneous pregnancy rate per cycle in the cohort in the absence of fertility awareness training. The cumulative pregnancy rate of subfertile couples after fertility awareness training was 38% (95% CI 27-49%; 58 pregnancies) after eight observation months, which is significantly higher than the estimated basic pregnancy rate of 21.6% in untrained couples in the same cohort. For couples who had been seeking to become pregnant for 1-2 years, the pregnancy rate increased to 56% after 8 months. A female age above 35 (cumulative pregnancy rate 25%, p = 0.06), couples who had attempted to become pregnant for more than 2 years (cumulative pregnancy rate 17%, p < 0.01), all significantly reduce the chances of conceiving naturally at some point. Training women to identify their fertile window in the menstrual cycle seems to be a reasonable first-line therapy in the management of subfertility.

  4. Subject's Conception of Human Nature in Indonesia: Experiences in Research Cooperation.

    ERIC Educational Resources Information Center

    Oerter, Rolf

    The main purpose of this paper on a study of Indonesian concepts of human nature is to demonstrate practical instances of cooperation between Western and Third World researchers. It is asserted that Western researchers must understand the general views of human nature held by individuals in Third World countries before they can apply theories in…

  5. A Study of Taiwanese Children's Conceptions of and Relation to Nature: Curricular and Policy Implications

    ERIC Educational Resources Information Center

    Dai, Amy Hsin-I

    2011-01-01

    The present study investigated children's conceptions of and relations to nature. Understanding the factors that influence them was the goal. The study used the Contextual Model of Learning as the theoretical framework to structure the research questions and data analysis to understand children's nature learning in the personal, sociocultural, and…

  6. Developing an Instrument for Assessing Students' Concepts of the Nature of Technology

    ERIC Educational Resources Information Center

    Liou, Pey-Yan

    2015-01-01

    Background: The nature of technology has been rarely discussed despite the fact that technology plays an essential role in modern society. It is important to discuss students' concepts of the nature of technology, and further to advance their technological literacy and adaptation to modern society. There is a need to assess high school students'…

  7. Science Teachers' Conceptions of Nature of Science: The Case of Bangladesh

    ERIC Educational Resources Information Center

    Sarkar, Md. Mahbub Alam; Gomes, Jui Judith

    2010-01-01

    This study explored Bangladeshi science teachers' conceptions of nature of science (NOS) with a particular focus on the nature of (a) scientific knowledge, (b) scientific inquiry and (c) scientific enterprise. The tentative, inferential, subjective and creative NOS, in addition to the myths of the scientific method and experimentation, the nature…

  8. Conceptions of the Nature of Science--Are They General or Context Specific?

    ERIC Educational Resources Information Center

    Urhahne, Detlef; Kremer, Kerstin; Mayer, Juergen

    2011-01-01

    The study investigates the relationship between general and context-specific conceptions of the nature of science (NOS). The categorization scheme by Osborne et al. (J Res Sci Teach 40:692-720, "2003") served as the theoretical framework of the study. In the category "nature of scientific knowledge", the certainty, development, simplicity,…

  9. Science Teachers' Conceptions of Nature of Science: The Case of Bangladesh

    ERIC Educational Resources Information Center

    Sarkar, Md. Mahbub Alam; Gomes, Jui Judith

    2010-01-01

    This study explored Bangladeshi science teachers' conceptions of nature of science (NOS) with a particular focus on the nature of (a) scientific knowledge, (b) scientific inquiry and (c) scientific enterprise. The tentative, inferential, subjective and creative NOS, in addition to the myths of the scientific method and experimentation, the nature…

  10. Conceptions of the Nature of Science--Are They General or Context Specific?

    ERIC Educational Resources Information Center

    Urhahne, Detlef; Kremer, Kerstin; Mayer, Juergen

    2011-01-01

    The study investigates the relationship between general and context-specific conceptions of the nature of science (NOS). The categorization scheme by Osborne et al. (J Res Sci Teach 40:692-720, "2003") served as the theoretical framework of the study. In the category "nature of scientific knowledge", the certainty, development, simplicity,…

  11. A Study of Taiwanese Children's Conceptions of and Relation to Nature: Curricular and Policy Implications

    ERIC Educational Resources Information Center

    Dai, Amy Hsin-I

    2011-01-01

    The present study investigated children's conceptions of and relations to nature. Understanding the factors that influence them was the goal. The study used the Contextual Model of Learning as the theoretical framework to structure the research questions and data analysis to understand children's nature learning in the personal, sociocultural, and…

  12. Developing an Instrument for Assessing Students' Concepts of the Nature of Technology

    ERIC Educational Resources Information Center

    Liou, Pey-Yan

    2015-01-01

    Background: The nature of technology has been rarely discussed despite the fact that technology plays an essential role in modern society. It is important to discuss students' concepts of the nature of technology, and further to advance their technological literacy and adaptation to modern society. There is a need to assess high school students'…

  13. Treatment should be considered a competing risk when predicting natural conception in subfertile women.

    PubMed

    Van Geloven, N; Broeze, K A; Bossuyt, P M M; Zwinderman, A H; Mol, B W

    2012-03-01

    Prediction of natural conception in subfertile couples can help to differentiate between couples who should have immediate treatment and couples who can aim for natural conception for some time. Natural conception rates are often estimated using standard techniques such as Kaplan-Meier or Cox proportional hazard models. These estimates can be biased by incorrect handling of data from women who start assisted reproductive technology therapy before the end of the follow-up period. This paper discusses the validity and the impact of the assumption of non-informative censoring as used in the Kaplan-Meier and Cox models. In a cohort of 5360 subfertile couples with suspected tubal pathology, the probability of natural conception and the prognostic value of additional tests for tubal pathology were estimated using traditional methods and with a competing risks analysis. The estimated probability of natural conception within 3 years was almost 2-fold higher when assuming non-informative censoring compared with the competing risks model, 41 versus 22%. The prognostic value of tests was more conservative using the competing risks model than with the traditional methods, the fecundity rate ratio for Chlamydia antibody testing was 0.72 versus 0.67, for hysterosalpingography, 0.83 versus 0.71 and for diagnostic laparoscopy, 0.89 versus 0.74. Given the improbable validity of the non-informative censoring assumption, the predictions of natural conception and of the prognostic value of tests are likely to be overestimated by the traditional analytic methods. We suggest the use of competing risks models as an alternative, more conservative, form of analysis when predicting natural conception and evaluating prognostic fertility tests.

  14. An Investigation of Effectiveness of Conceptual Change Text-Oriented Instruction on Students' Understanding of Solution Concepts

    ERIC Educational Resources Information Center

    Pinarbasi, Tacettin; Canpolat, Nurtac; Bayrakceken, Samih; Geban, Omer

    2006-01-01

    This study investigated the effect of conceptual change text-oriented instruction over traditional instruction on students' understanding of solution concepts (e.g., dissolving, solubility, factors affecting solubility, concentrations of solutions, types of solutions, physical properties of solutions) and their attitudes towards chemistry. The…

  15. An Investigation of Effectiveness of Conceptual Change Text-Oriented Instruction on Students' Understanding of Solution Concepts

    ERIC Educational Resources Information Center

    Pinarbasi, Tacettin; Canpolat, Nurtac; Bayrakceken, Samih; Geban, Omer

    2006-01-01

    This study investigated the effect of conceptual change text-oriented instruction over traditional instruction on students' understanding of solution concepts (e.g., dissolving, solubility, factors affecting solubility, concentrations of solutions, types of solutions, physical properties of solutions) and their attitudes towards chemistry. The…

  16. The effect of teachers' language on students' conceptions of the nature of science

    NASA Astrophysics Data System (ADS)

    Zeidler, Dana L.; Lederman, Norman G.

    Conveying an adequate conception of the nature of science to students is implicit in the border context of what has come to be known as scientific literacy. However, it has previously been demonstrated that possession of valid conceptions of the nature of science does not necessarily result in the performance of those teaching behaviors that are related to improved student conceptions. The present study examines the possibility that the language teachers use to communicate science content may provide the context (Realist or Instrumentalist orientations) in which students come to formulate a world view of science. Eighteen high school biology teachers and one randomly selected class from each of their sections (n = 409 students) were administered pre- and posttests at the beginning and end of the fall term using the Nature of Scientific Knowledge Scale (NSKS). Composite scores of the student changes on the Testable, Developmental, and Creative subscales were used to compare those six classes that exhibited the greatest change with those six classes that had the least change on the NSKS. Intensive qualitative observations of each teacher were also conducted over the fall semester, resulting in complete transcripts of teacher-student interactions. Qualitative comparisons of classes with respect to six variables related to Realist and Instrumentalist conceptions of the nature of science were conducted. TEACHERS' ordinary language in the presentation of subject matter was found to have significant impact on students' conceptions of the nature of science. These variables represented different contexts (Realist-Instrumental) teachers used to express themselves, scientific information, and concepts. Determining the extent to which TEACHERS' language has an impact on changes in students' conception of the nature of science has direct bearing on all preservice and inservice science teacher education programs.

  17. Taiwanese Preservice Teachers' Conceptions of Nature and the Nature of Science.

    ERIC Educational Resources Information Center

    Liu, Shiang-Yao; Lederman, Norman G.

    This study examined views of the human relationship with the natural world and understandings about the nature of science (NOS) held by preservice elementary teachers in the context of Taiwan. The participants included 54 third-year students enrolled in the departments of science education and mathematics education at a teacher college. Data were…

  18. Natural conception in HIV-serodiscordant couples with the infected partner in suppressive antiretroviral therapy

    PubMed Central

    Del Romero, Jorge; Baza, María Begoña; Río, Isabel; Jerónimo, Adrián; Vera, Mar; Hernando, Victoria; Rodríguez, Carmen; Castilla, Jesús

    2016-01-01

    Abstract The potential of antiretroviral treatment (ART) to prevent the sexual transmission of HIV has increased the number of serodiscordant couples who are considering natural conception. We aim to describe the results of a protocol for reproductive counseling aimed at HIV serodiscordant couples who desire natural conception, in which the infected partner, the index case, is receiving suppressive antiretroviral treatment. A prospective cohort included all HIV serodiscordant couples attended a counseling program in the period 2002 to 2013 who opted for natural conception and met the following criteria: index case on ART with persistent plasma viral suppression for at least the previous 6 months, ART compliance over 95%, preserved immune status, undetectable HIV viral and proviral load in semen in male index cases, and absence of genitourinary infections and fertility problems in both members of the couple. Of the 161 HIV serodiscordant couples included, 133 with male index cases, 66% achieved at least 1 pregnancy, 18% a second one, and 5% a third pregnancy. A total of 144 natural pregnancies occurred and 107 babies were born. The pregnancy rate was 1.9 for each 100 acts of vaginal intercourse, and the mean time to conception was 6.1 months, both independently of the sex of the index case. No case of sexual or vertical HIV transmission occurred. In the absence of fertility problems and under controlled conditions, natural conception might be a safe and effective reproductive method for those HIV serodiscordant couples who choose this reproductive option. PMID:27472733

  19. Natural Conception May Be an Acceptable Option in HIV-Serodiscordant Couples in Resource Limited Settings.

    PubMed

    Sun, Lijun; Wang, Fang; Liu, An; Xin, Ruolei; Zhu, Yunxia; Li, Jianwei; Shao, Ying; Ye, Jiangzhu; Chen, Danqing; Li, Zaicun

    2015-01-01

    Many HIV serodiscordant couples have a strong desire to have their own biological children. Natural conception may be the only choice in some resource limited settings but data about natural conception is limited. Here, we reported our findings of natural conception in HIV serodiscordant couples. Between January 2008 and June 2014, we retrospectively collected data on 91 HIV serodiscordant couples presenting to Beijing Youan Hospital with childbearing desires. HIV counseling, effective ART on HIV infected partners, pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP) in negative female partners and timed intercourse were used to maximally reduce the risk of HIV transmission. Of the 91 HIV serodiscordant couples, 43 were positive in male partners and 48 were positive in female partners. There were 196 unprotected vaginal intercourses, 100 natural conception and 97 newborns. There were no cases of HIV seroconversion in uninfected sexual partners. Natural conception may be an acceptable option in HIV-serodiscordant couples in resource limited settings if HIV-positive individuals have undetectable viremia on HAART, combined with HIV counseling, PrEP, PEP and timed intercourse.

  20. Employment of Gibbs-Donnan-based concepts for interpretation of the properties of linear polyelectrolyte solutions

    USGS Publications Warehouse

    Marinsky, J.A.; Reddy, M.M.

    1991-01-01

    Earlier research has shown that the acid dissociation and metal ion complexation equilibria of linear, weak-acid polyelectrolytes and their cross-linked gel analogues are similarly sensitive to the counterion concentration levels of their solutions. Gibbs-Donnan-based concepts, applicable to the gel, are equally applicable to the linear polyelectrolyte for the accommodation of this sensitivity to ionic strength. This result is presumed to indicate that the linear polyelectrolyte in solution develops counterion-concentrating regions that closely resemble the gel phase of their analogues. Advantage has been taken of this description of linear polyelectrolytes to estimate the solvent uptake by these regions. ?? 1991 American Chemical Society.

  1. Data Mining and Concept Clustering in Determining the Nature of a Network Attack

    DTIC Science & Technology

    2002-08-01

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP013329 TITLE: Data Mining and Concept Clustering in Determining the...Click here to view PowerPoint presentation; Press Esc to exit 18-1 Data Mining and Concept Clustering in Determining the Nature of a Network Attack...by a rule. The USAF Enterprise Defence project is intended to develop * Better data mining tools and techniques are needed to the next-generation

  2. Liquid absorbent solutions for separating nitrogen from natural gas

    DOEpatents

    Friesen, Dwayne T.; Babcock, Walter C.; Edlund, David J.; Lyon, David K.; Miller, Warren K.

    2000-01-01

    Nitrogen-absorbing and -desorbing compositions, novel ligands and transition metal complexes, and methods of using the same, which are useful for the selective separation of nitrogen from other gases, especially natural gas.

  3. Liquid absorbent solutions for separating nitrogen from natural gas

    DOEpatents

    Friesen, Dwayne T.; Babcock, Walter C.; Edlund, David J.; Lyon, David K.; Miller, Warren K.

    2000-01-01

    Nitrogen-absorbing and -desorbing compositions, novel ligands and transition metal complexes, and methods of using the same, which are useful for the selective separation of nitrogen from other gases, especially natural gas.

  4. On the nature of insight solutions: evidence from skill differences in anagram solution.

    PubMed

    Novick, Laura R; Sherman, Steven J

    2003-02-01

    According to the Gestalt psychologists, problem solutions that pop into mind suddenly with no awareness of the process by which they were generated are objectively as well as subjectively sudden. Thus, such pop-out solutions are qualitatively different from search solutions, which are constructed incrementally. The authors tested this claim in the domain of anagram solution. Experiment 1 documented that anagrams yield pop-out solutions, especially among highly skilled solvers. The results of Experiment 2 indicated that both pop-out and search solutions depended on the gradual accumulation of partial information, contrary to the Gestalt view of problem solving. Nevertheless, some aspects of the Experiment 2 results, as well as new analyses of an anagram study reported elsewhere, suggest that there may in fact be a qualitative difference between pop-out and search solutions. In particular, pop-out solutions may result from parallel processing of the constraints on the rearranged order of the anagram letters, whereas search solutions may result from a serial hypothesis-testing procedure. Like dynamite, the insightful solution explodes on the solver's cognitive landscape with breathtaking suddenness, but if one looks closely, a long fuse warns of the impending reorganization. (Durso, Rea, & Dayton, 1994, p. 98)

  5. College biology students' conceptions related to the nature of biological knowledge: Implications for conceptual change

    NASA Astrophysics Data System (ADS)

    Ameny, Gloria Millie Apio

    Adequate understanding of the nature of science is a major goal of science education. Understanding of the evolutionary nature of biological knowledge is a means of reinforcing biology students' understanding of the nature of science. It provides students with the philosophical basis, explanatory ideals, and subject matter-specific views of what counts as a scientifically-acceptable biological explanation. This study examined 121 college introductory biology and advanced zoology students for their conceptions related to the nature of biological knowledge. A 60-item Likert-scale questionnaire called the Nature of Biological Knowledge Scale and student interviews were used as complementary research instruments. Firstly, the study showed that 80--100% of college biology students have an adequate understanding of scientific methods, and that a similar percentage of students had learned the theory of evolution by natural selection in their biology courses. Secondly, the study showed that at least 60--80% of the students do not understand the importance of evolution in biological knowledge. Yet the study revealed that a statistically significant positive correlation exist among students' understanding of natural selection, divergent, and convergent evolutionary models. Thirdly, the study showed that about 20--58% of college students hold prescientific conceptions which, in part, are responsible for students' lack of understanding of the nature of biological knowledge. A statistically significant negative correlation was found among students' prescientific conceptions about basis of biological knowledge and nature of change in biological processes, and their understanding of natural selection and evolutionary models. However, the study showed that students' characteristics such as gender, age, major, or years in college have no statistically significant influence on students' conceptions related to the nature of biological knowledge. Only students' depth of biological

  6. Thai Pre-Service Science Teachers' Conceptions of the Nature of Science

    ERIC Educational Resources Information Center

    Buaraphan, Khajornsak; Sung-ong, Sunun

    2009-01-01

    The conceptions of the nature of science (NOS), particularly scientific knowledge, scientific method, scientists' work, and scientific enterprise, of 113 Thai pre-service science teachers were was captured by the Myths of Science Questionnaire (MOSQ) in the first semester of the 2008 academic year. The data was quantitatively and qualitatively…

  7. Thai and Bangladeshi In-Service Science Teachers' Conceptions of Nature of Science: A Comparative Study

    ERIC Educational Resources Information Center

    Buaraphan, Khajornsak; Abedin Forhad, Ziaul

    2014-01-01

    Understanding of nature of science (NOS) serves as one of the desirable characteristics of science teachers. The current study explored 55 Thai and 110 Bangladeshi in-service secondary science teachers' conceptions of NOS regarding scientific knowledge, scientific method, scientists' work, and scientific enterprise, by using the Myths of Science…

  8. Representations of Fundamental Chemistry Concepts in Relation to the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Kirbulut, Zubeyde Demet; Beeth, Michael Edward

    2013-01-01

    This study investigated high school students' understanding of fundamental chemistry concepts - states of matter, melting, evaporation, condensation, boiling, and vapor pressure, in relation to their understanding of the particulate nature of matter. A sample of six students (four females and two males) enrolled in a second year chemistry course…

  9. Representations of Fundamental Chemistry Concepts in Relation to the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Kirbulut, Zübeyde Demet; Beeth, Michael Edward

    2013-01-01

    This study investigated high school students' understanding of fundamental chemistry concepts--states of matter, melting, evaporation, condensation, boiling, and vapor pressure, in relation to their understanding of the particulate nature of matter. A sample of six students (four females and two males) enrolled in a second year chemistry course at…

  10. Beyond Exemplars and Prototypes as Memory Representations of Natural Concepts: A Clustering Approach

    ERIC Educational Resources Information Center

    Verbeemen, Timothy; Vanpaemel, Wolf; Pattyn, Sven; Storms, Gert; Verguts, Tom

    2007-01-01

    Categorization in well-known natural concepts is studied using a special version of the Varying Abstraction Framework (Vanpaemel, W., & Storms, G. (2006). A varying abstraction framework for categorization. Manuscript submitted for publication; Vanpaemel, W., Storms, G., & Ons, B. (2005). A varying abstraction model for categorization. In B. Bara,…

  11. Students' Conceptions of the Nature of Science: Perspectives from Canadian and Korean Middle School Students

    ERIC Educational Resources Information Center

    Park, Hyeran; Nielsen, Wendy; Woodruff, Earl

    2014-01-01

    This study examined and compared students' understanding of nature of science (NOS) with 521 Grade 8 Canadian and Korean students using a mixed methods approach. The concepts of NOS were measured using a survey that had both quantitative and qualitative elements. Descriptive statistics and one-way multivariate analysis of variances examined the…

  12. Teachers' Knowledge Structures for Nature of Science and Scientific Inquiry: Conceptions and Classroom Practice

    ERIC Educational Resources Information Center

    Bartos, Stephen A.; Lederman, Norman G.

    2014-01-01

    Research on nature of science (NOS) and scientific inquiry (SI) has indicated that a teacher's knowledge of each, however well developed, is not sufficient to ensure that these conceptions necessarily manifest themselves in classroom practice (Lederman & Druger, 1985; Lederman, 2007). In light of considerable research that has examined…

  13. Thai Pre-Service Science Teachers' Conceptions of the Nature of Science

    ERIC Educational Resources Information Center

    Buaraphan, Khajornsak; Sung-ong, Sunun

    2009-01-01

    The conceptions of the nature of science (NOS), particularly scientific knowledge, scientific method, scientists' work, and scientific enterprise, of 113 Thai pre-service science teachers were was captured by the Myths of Science Questionnaire (MOSQ) in the first semester of the 2008 academic year. The data was quantitatively and qualitatively…

  14. Beyond Exemplars and Prototypes as Memory Representations of Natural Concepts: A Clustering Approach

    ERIC Educational Resources Information Center

    Verbeemen, Timothy; Vanpaemel, Wolf; Pattyn, Sven; Storms, Gert; Verguts, Tom

    2007-01-01

    Categorization in well-known natural concepts is studied using a special version of the Varying Abstraction Framework (Vanpaemel, W., & Storms, G. (2006). A varying abstraction framework for categorization. Manuscript submitted for publication; Vanpaemel, W., Storms, G., & Ons, B. (2005). A varying abstraction model for categorization. In B. Bara,…

  15. Students' Conceptions of the Nature of Science: Perspectives from Canadian and Korean Middle School Students

    ERIC Educational Resources Information Center

    Park, Hyeran; Nielsen, Wendy; Woodruff, Earl

    2014-01-01

    This study examined and compared students' understanding of nature of science (NOS) with 521 Grade 8 Canadian and Korean students using a mixed methods approach. The concepts of NOS were measured using a survey that had both quantitative and qualitative elements. Descriptive statistics and one-way multivariate analysis of variances examined the…

  16. Thai In-Service Science Teachers' Conceptions of the Nature of Science

    ERIC Educational Resources Information Center

    Buaraphan, Khajornsak

    2009-01-01

    Understanding of the Nature of Science (NOS) serves as one of the desirable characteristics of science teachers. The current study attempted to explore 101 Thai in-service science teachers' conceptions of the NOS, particularly scientific knowledge, the scientific method, scientists' work, and scientific enterprise, by using the Myths of Science…

  17. Test-Enhanced Learning of Natural Concepts: Effects on Recognition Memory, Classification, and Metacognition

    ERIC Educational Resources Information Center

    Jacoby, Larry L.; Wahlheim, Christopher N.; Coane, Jennifer H.

    2010-01-01

    Three experiments examined testing effects on learning of natural concepts and metacognitive assessments of such learning. Results revealed that testing enhanced recognition memory and classification accuracy for studied and novel exemplars of bird families on immediate and delayed tests. These effects depended on the balance of study and test…

  18. Test-Enhanced Learning of Natural Concepts: Effects on Recognition Memory, Classification, and Metacognition

    ERIC Educational Resources Information Center

    Jacoby, Larry L.; Wahlheim, Christopher N.; Coane, Jennifer H.

    2010-01-01

    Three experiments examined testing effects on learning of natural concepts and metacognitive assessments of such learning. Results revealed that testing enhanced recognition memory and classification accuracy for studied and novel exemplars of bird families on immediate and delayed tests. These effects depended on the balance of study and test…

  19. Thai and Bangladeshi In-Service Science Teachers' Conceptions of Nature of Science: A Comparative Study

    ERIC Educational Resources Information Center

    Buaraphan, Khajornsak; Abedin Forhad, Ziaul

    2014-01-01

    Understanding of nature of science (NOS) serves as one of the desirable characteristics of science teachers. The current study explored 55 Thai and 110 Bangladeshi in-service secondary science teachers' conceptions of NOS regarding scientific knowledge, scientific method, scientists' work, and scientific enterprise, by using the Myths of Science…

  20. Thai In-Service Science Teachers' Conceptions of the Nature of Science

    ERIC Educational Resources Information Center

    Buaraphan, Khajornsak

    2009-01-01

    Understanding of the Nature of Science (NOS) serves as one of the desirable characteristics of science teachers. The current study attempted to explore 101 Thai in-service science teachers' conceptions of the NOS, particularly scientific knowledge, the scientific method, scientists' work, and scientific enterprise, by using the Myths of Science…

  1. How to Learn the Natural Numbers: Inductive Inference and the Acquisition of Number Concepts

    ERIC Educational Resources Information Center

    Margolis, Eric; Laurence, Stephen

    2008-01-01

    Theories of number concepts often suppose that the natural numbers are acquired as children learn to count and as they draw an induction based on their interpretation of the first few count words. In a bold critique of this general approach, Rips, Asmuth, Bloomfield [Rips, L., Asmuth, J. & Bloomfield, A. (2006). Giving the boot to the bootstrap:…

  2. Students' and Teachers' Conceptions of the Nature of Science: A Review of the Research.

    ERIC Educational Resources Information Center

    Lederman, Norman G.

    1992-01-01

    Reviews research from the past 40 years on students' and teachers' conceptions of the nature of science, clarifies the basic assumptions and logic which have guided earlier research efforts, contrasts the results from qualitative and quantitative research, makes recommendations about research methods, and suggests avenues for future research about…

  3. The Problematic Nature of the Artist Teacher Concept and Implications for Pedagogical Practice

    ERIC Educational Resources Information Center

    Hoekstra, Marike

    2015-01-01

    The main argument of this article is that the problematic nature of the artist teacher concept might not be the duality between art and education, but might refer to a limited understanding of education, in such a way that art would appear to be contrasting to education. A different definition of education is required to understand the qualities…

  4. [Plinius and Greek physicians in Rome: the concept of nature and medical critique in Naturalis Historia].

    PubMed

    Hahn, J

    1991-01-01

    Pliny's historical outline of the development of medicine, in Natural History 29.1-27, is our primary source concerning the reception of scientific medicine at Rome during the later Republic and early Empire. Here, as elsewhere, Pliny handles Greek doctors and their medical practices with vehement disapproval. But this attitude, at first glance anti-Hellene, traditionalistic, and critical of his coevals, arises from more deeply rooted notions: a specific conception of nature which can be shown to be the basis of Pliny's critique of medicine and his own times. Reconstruction of this "Plinean" conception reveals a view of nature marked by Stoic terminology and categories, though in fact derivate from various sources, idiosyncratic and characterized by a genuine love of and respect for nature and her creations. True comprehension of the lessons offered by nature, resulting in concrete mores of behaviour and moral categories, as opposed to theory and speculation, is the proper modus operandi for Pliny. And thus, with regard to the human process of self-discovery in the natural world, medicine plays a decisive role--for providential nature displays herself most clearly in the production of healing substances. Pliny notes among the proponents of scientific medicine, a general disregard for nature and her rules, while he finds just the opposite in traditional medicine. His own accomplishment resides not only in the safeguarding of numberless recipies from the world of folk medicine, but also in the facts that he under-pins these traditional methods of healing, and their basic principles, with a specific conception of nature, and that he marks out an exceptionally important place for traditional methods of healing in the canon of general knowledge.

  5. A study of Taiwanese children's conceptions of and relation to nature: Curricular and policy implications

    NASA Astrophysics Data System (ADS)

    Dai, Amy Hsin-I.

    The present study investigated children's conceptions of and relations to nature. Understanding the factors that influence them was the goal. The study used the Contextual Model of Learning as the theoretical framework to structure the research questions and data analysis to understand children's nature learning in the personal, sociocultural, and physical contexts that change over time. Twelve children aged 5 and 6 were prompted to draw a picture of themselves in nature. They were interviewed about the sources of those ideas and living experiences, and if they thought photographs of scenery were nature. These twelve children's parents also participated in a survey to study the family influence. I used interpretational analysis to seek for common patterns and themes. Scoring rubrics, coaxial comparison, constant comparison, and the theoretical framework were used to triangulate and investigate influential factors of children's ideas of nature. The study showed that children at this age already had developed a basic conception of what is nature, but also need to learn about the role of human beings in nature and the interrelations of nature in order to develop environmental education ideas. Most children also had a positive feeling toward nature. Children's definitions of nature were developed mainly from what parents and grandparents had told them and their firsthand exposure to nature. Only during the weekend did the children's families have time to visit nature. It was found that most parents in this study stated that they were inspired by nature and were very willing to take their children to nature settings. The most visited natural places that were reported visited were parks in the city and the mountains surrounding the city. However, very often parents missed teachable opportunities to make the experiences with nature meaningful to children. Implications of the study apply to curriculum designers, educators, urban planners, and parents. It is recommended

  6. An Investigation of Effectiveness of Conceptual Change Text-oriented Instruction on Students' Understanding of Solution Concepts

    NASA Astrophysics Data System (ADS)

    Pinarbaşi; , Tacettin; Canpolat, Nurtaç; Bayrakçeken, Samih; Geban, Ömer

    2006-12-01

    This study investigated the effect of conceptual change text-oriented instruction over traditional instruction on students' understanding of solution concepts (e.g., dissolving, solubility, factors affecting solubility, concentrations of solutions, types of solutions, physical properties of solutions) and their attitudes towards chemistry. The sample of this study consisted of 87 undergraduate students from two classes enrolled in an introductory chemistry course. One of the classes was assigned randomly to the control group, and the other class were assigned randomly to the experimental group. During teaching the topic of solution concepts in the chemistry curriculum, a conceptual change text-oriented instruction was applied in the experimental group whereas traditional instruction was followed in the control group. The results showed that the students in the experimental group performed better with respect to solution concepts. In addition, it has been found that there was no significant difference between the attitudes of students in the experimental and control groups towards chemistry.

  7. Experienced Teachers' Strategies for Assessing Nature of Science Conceptions in the Elementary Classroom

    NASA Astrophysics Data System (ADS)

    Akerson, Valarie L.; Cullen, Theresa A.; Hanson, Deborah L.

    2010-10-01

    This study explored the nature of science (NOS) assessments K-4 classroom teachers developed for measuring students’ understandings of NOS elements. We used the Views of Nature of Science Questionnaire-Form VNOS-D2 (Views of Nature of Science Elementary School Version 2) and interviews to verify that teachers’ conceptions of NOS were sufficient to enable them to teach and assess NOS. We collected copies of teachers’ action research designs, lesson plans, and assessment tools, conducted classroom observations and made field notes of their science instruction and assessments. We videotaped conversations at monthly workshops to note discussion surrounding teaching and assessing NOS in K-4 classrooms. We found that experienced teachers designed a variety of strategies for assessing NOS conceptions that differed by grade level.

  8. Anthropology from a Kantian point of view: toward a cosmopolitan conception of human nature.

    PubMed

    Louden, Robert B

    2008-12-01

    Anthropology was a new field of study when Kant first began lecturing on it in 1772, and Kant himself was the first academic to teach regular courses in this area. As is well known, his own approach to anthropology is self-described as 'pragmatic', and Kant's pragmatic anthropology differs markedly from the anthropologies that other early contributors to the new discipline were advocating. In this essay I focus on a fundamental feature of Kant's anthropology that has been under-appreciated in previous discussions; namely, the particular conception of human nature that he believes anthropology, when pursued properly, leads to. I call this conception a cosmopolitan conception of human nature. In addition to establishing the central importance of this idea for Kant's project in anthropology, I also try in this essay to unravel some of its ambiguities and tensions as well as to highlight its underlying moral motives. The cosmopolitan conception of human nature that is central to Kant's anthropology is a further indication of the significance of his anthropology for ethics.

  9. Sargassum as a natural solution to enhance dune plant growth.

    PubMed

    Williams, Amy; Feagin, Rusty

    2010-11-01

    Many beach management practices focus on creating an attractive environment for tourists, but can detrimentally affect long-term dune integrity. One such practice is mechanical beach raking in which the wrack line is removed from the beach front. In Texas, Sargassum fluitans and natans, types of brown alga, are the main components of wrack and may provide a subsidy to the ecosystem. In this study, we used greenhouse studies to test the hypothesis that the addition of sargassum can increase soil nutrients and produce increased growth in dune plants. We also conducted an analysis of the nutrients in the sargassum to determine the mechanisms responsible for any growth enhancement. Panicum amarum showed significant enhancement of growth with the addition of sargassum, and while Helianthus debilis, Ipomoea stolonifera, Sporobolus virginicus, and Uniola paniculata responded slightly differently to the specific treatments, none were impaired by the addition of sargassum. In general, plants seemed to respond well to unwashed sargassum and multiple additions of sargassum, indicating that plants may have adapted to capitalize on the subsidy in its natural state directly from the ocean. For coastal managers, the use of sargassum as a fertilizer could be a positive, natural, and efficient method of dealing with the accumulation of wrack on the beach.

  10. Student concepts of Natural Selection from a resource-based perspective

    NASA Astrophysics Data System (ADS)

    Benjamin, Scott Shawn

    The past two decades have produced a substantial amount of research about the teaching and learning of evolution; however, recent research often lacks a theoretical foundation. Application of a new theoretical framework could help fill the void and improve research about student concepts of evolution. This study seeks to show that a resource-based framework (Hammer et al., 2005) can improve research into student concepts of natural selection. Concepts of natural selection from urban community college students were assessed via qualitative (interviews, written open-response questions, and write/think aloud procedures) and quantitative methods (coded open response analysis, Concept Inventory for Natural Selection (CINS)(Anderson, Fisher, & Norman, 2002). Results showed that students demonstrate four important aspects of resource-based framework: the multi-faceted construction of concepts, context sensitivity/ concept flexibility, at-the-moment activation of resources, and perceptual frames. In open response assessment, evolutionary-gain responses produced significantly different responses than evolutionary-loss questions with: 1) significantly more correct answers for the gain than loss question (Wilcoxon signed rank test, z = -3.68, p=0.0002); 2) more Lamarckian responses to loss than the gain question (Fisher exact, p=0.0039); and significantly different distributions in expanded need vs basic need answers (Fishers exact, p = 0.02). Results from CINS scores showed significant differences in post activity scores between students that held different naive concepts associated with origin of variation, origin of species, differential reproduction, and limited survival suggesting that some naive ideas facilitate learning. Outcomes also suggest that an everyday or self-experience typological perceptual frame is an underlying source of many incorrect ideas about evolution. Interview and write/think aloud assessments propose four process resources applied by students as

  11. Natural solution to antibiotic resistance: bacteriophages 'The Living Drugs'.

    PubMed

    Jassim, Sabah A A; Limoges, Richard G

    2014-08-01

    Antibiotics have been a panacea in animal husbandry as well as in human therapy for decades. The huge amount of antibiotics used to induce the growth and protect the health of farm animals has lead to the evolution of bacteria that are resistant to the drug's effects. Today, many researchers are working with bacteriophages (phages) as an alternative to antibiotics in the control of pathogens for human therapy as well as prevention, biocontrol, and therapy in animal agriculture. Phage therapy and biocontrol have yet to fulfill their promise or potential, largely due to several key obstacles to their performance. Several suggestions are shared in order to point a direction for overcoming common obstacles in applied phage technology. The key to successful use of phages in modern scientific, farm, food processing and clinical applications is to understand the common obstacles as well as best practices and to develop answers that work in harmony with nature.

  12. Bolivia-Brazil natural gas project: Challenges and solutions

    SciTech Connect

    Bassani, A.

    1993-12-31

    The development of the natural gas reserves in Bolivia and Brazil is discussed. The development of these reserves is being conducted by the Private Corporation for Gas Development. The Corporation was created to promote participation of the private sector in an area that was exclusively managed by federal or state governments. In order to promote participation by the private sector and at the same time to motivate foreign investors, the corporation is conducting a program of activities and studies that includes a legal and institutional analysis, a feasibility study in accordance with the viewpoints of the private sector, and also the structure of a business development plan, according to the perspective of private investors.

  13. Natural gas production problems : solutions, methodologies, and modeling.

    SciTech Connect

    Rautman, Christopher Arthur; Herrin, James M.; Cooper, Scott Patrick; Basinski, Paul M.; Olsson, William Arthur; Arnold, Bill Walter; Broadhead, Ronald F.; Knight, Connie D.; Keefe, Russell G.; McKinney, Curt; Holm, Gus; Holland, John F.; Larson, Rich; Engler, Thomas W.; Lorenz, John Clay

    2004-10-01

    Natural gas is a clean fuel that will be the most important domestic energy resource for the first half the 21st centtuy. Ensuring a stable supply is essential for our national energy security. The research we have undertaken will maximize the extractable volume of gas while minimizing the environmental impact of surface disturbances associated with drilling and production. This report describes a methodology for comprehensive evaluation and modeling of the total gas system within a basin focusing on problematic horizontal fluid flow variability. This has been accomplished through extensive use of geophysical, core (rock sample) and outcrop data to interpret and predict directional flow and production trends. Side benefits include reduced environmental impact of drilling due to reduced number of required wells for resource extraction. These results have been accomplished through a cooperative and integrated systems approach involving industry, government, academia and a multi-organizational team within Sandia National Laboratories. Industry has provided essential in-kind support to this project in the forms of extensive core data, production data, maps, seismic data, production analyses, engineering studies, plus equipment and staff for obtaining geophysical data. This approach provides innovative ideas and technologies to bring new resources to market and to reduce the overall environmental impact of drilling. More importantly, the products of this research are not be location specific but can be extended to other areas of gas production throughout the Rocky Mountain area. Thus this project is designed to solve problems associated with natural gas production at developing sites, or at old sites under redevelopment.

  14. Confronting, Representing, and Believing Counterintuitive Concepts: Navigating the Natural and the Supernatural.

    PubMed

    Lane, Jonathan D; Harris, Paul L

    2014-03-01

    Recent research shows that even preschoolers are skeptical; they frequently reject claims from other people when the claims conflict with their own perceptions and concepts. Yet, despite their skepticism, both children and adults come to believe in a variety of phenomena that defy their first-hand perceptions and intuitive conceptions of the world. In this review, we explore how children and adults acquire such concepts. We describe how a similar developmental process underlies mental representation of both the natural and the supernatural world, and we detail this process for two prominent supernatural counterintuitive ideas-God and the afterlife. In doing so, we highlight the fact that conceptual development does not always move in the direction of greater empirical truth, as described within naturalistic domains. We consider factors that likely help overcome skepticism and, in doing so, promote belief in counterintuitive phenomena. These factors include qualities of the learners, aspects of the context, qualities of the informants, and qualities of the information.

  15. A natural compromise: a moderate solution to the GMO & "natural" labeling disputes.

    PubMed

    Amaru, Stephanie

    2014-01-01

    In the United States, genetically modified (GM) foods are labeled no differently from their natural counterparts, leaving consumers with no mechanism for deciphering genetically modified food content. The Food and Drug Administration (FDA) has not formally defined the term "natural," which is frequently used on food labels despite consumer confusion as to what it means. The FDA should initiate a notice and comment rulemaking addressing the narrow issue of whether use of the word "natural" should be permitted oil GM food labels. Prohibition of the use of"natural" on genetically modified foods would mitigate consumer deception regarding genetically modified food content without significantly disadvantaging genetically modified food producers.

  16. 'Natures' and 'Laws': The making of the concept of law of nature - Robert Grosseteste (c. 1168-1253) and Roger Bacon (1214/1220-1292).

    PubMed

    Kedar, Yael; Hon, Giora

    2017-02-01

    Contemporary scholars set the Greek conception of an immanent natural order in opposition to the seventeenth century mechanistic conception of extrinsic laws imposed upon nature from without. By contrast, we argue that in the process of making the concept of law of nature, forms and laws were coherently used in theories of natural causation. We submit that such a combination can be found in the thirteenth century. The heroes of our claim are Robert Grosseteste who turned the idea of corporeal form into the common feature of matter, and Roger Bacon who described the effects of that common feature. Bacon detached the explanatory principle from matter and rendered it independent and therefore external to natural substances. Our plausibility argument, anchored in close reading of the relevant texts, facilitates a coherent conception of both 'natures' and 'laws'.

  17. Teaching the courses of astronomy and concepts of modern natural science in Kazan Federal University

    NASA Astrophysics Data System (ADS)

    Nefedyev, Yu.; Zabbarova, R.; Kutlenkov, M.; Varaksina, N.; Churkin, K.

    There are varieties of advanced techniques of training in the courses in astronomy and concepts of the modern natural science in Kazan Federal University (KFU). It should be emphasized that the course of the modern natural science (COMNS) has a great part of astronomy. It was considered that astronomy is cosmic and distant. Chemistry, biology, physics are terrestrial and close. Nevertheless, astronomy is the most universal and connecting science. When we speak about the course in COMNS, we should remember that this course must be taught by astronomers or other science professors, because COMNS philosophy has nothing to do with science.

  18. A New Solution Concept for the Ultimatum Game leading to the Golden Ratio.

    PubMed

    Schuster, Stefan

    2017-07-17

    The Ultimatum Game is a paradigmatic two-player game. A proposer can offer a certain fraction of some valuable good. A responder can accept the offer or reject it, implying that the two players receive nothing. The only subgame-perfect Nash equilibrium is to only offer an infinitesimal amount and to accept this. However, this equilibrium is not in agreement with experimental observations, which show varying accepted offers around 40%. While some authors suggest that the fairest split of 50% vs. 50% would be explainable on theoretical grounds or by computer simulation, a few authors (including myself) have recently suggested that the Golden Ratio, about 0.618 vs. about 0.382, would be the solution, in striking agreement with observations. Here we propose a solution concept, based on an optimality approach and epistemic arguments, leading to that suggested solution. The optimality principle is explained both in an axiomatic way and by bargaining arguments, and the relation to Fibonacci numbers is outlined. Our presentation complements the Economic Harmony theory proposed by R. Suleiman and is based on infinite continued fractions. The results are likely to be important for the theory of fair salaries, justice theory and the predictive value of game theory.

  19. Normality and naturalness: a comparison of the meanings of concepts used within veterinary medicine and human medicine.

    PubMed

    Lerner, Henrik; Hofmann, Bjørn

    2011-12-01

    This article analyses the different connotations of "normality" and "being natural," bringing together the theoretical discussion from both human medicine and veterinary medicine. We show how the interpretations of the concepts in the different areas could be mutually fruitful. It appears that the conceptions of "natural" are more elaborate in veterinary medicine, and can be of value to human medicine. In particular they can nuance and correct conceptions of nature in human medicine that may be too idealistic. Correspondingly, the wide ranging conceptions of "normal" in human medicine may enrich conceptions in veterinary medicine, where the discussions seem to be sparse. We do not argue that conceptions from veterinary medicine should be used in human medicine and vice versa, but only that it could be done and that it may well be fruitful. Moreover, there are overlaps between some notions of normal and natural, and further conceptual analysis on this overlap is needed.

  20. The Electromagnetic Conception of Nature at the Root of the Special and General Relativity Theories and Its Revolutionary Meaning

    ERIC Educational Resources Information Center

    Giannetto, Enrico R. A.

    2009-01-01

    The revolution in XX century physics, induced by relativity theories, had its roots within the electromagnetic conception of Nature. It was developed through a tradition related to Brunian and Leibnizian physics, to the German "Naturphilosophie" and English XIXth physics. The electromagnetic conception of Nature was in some way realized by the…

  1. The Electromagnetic Conception of Nature at the Root of the Special and General Relativity Theories and Its Revolutionary Meaning

    ERIC Educational Resources Information Center

    Giannetto, Enrico R. A.

    2009-01-01

    The revolution in XX century physics, induced by relativity theories, had its roots within the electromagnetic conception of Nature. It was developed through a tradition related to Brunian and Leibnizian physics, to the German "Naturphilosophie" and English XIXth physics. The electromagnetic conception of Nature was in some way realized by the…

  2. Conceptions of the Nature of Science Held by Undergraduate Pre-Service Biology Teachers in South-West Nigeria

    ERIC Educational Resources Information Center

    Adedoyin, A. O.; Bello, G.

    2017-01-01

    This study investigated the conceptions of the nature of science held by pre-service undergraduate biology teachers in South-West, Nigeria. Specifically, the study examined the influence of their gender on their conceptions of the nature of science. The study was a descriptive research of the survey method. The population for the study comprised…

  3. Solution--What Does It Mean? Helping Linear Algebra Students Develop the Concept While Improving Research Tools

    ERIC Educational Resources Information Center

    DeVries, David; Arnon, Ilana

    2004-01-01

    Twelve linear algebra students were interviewed about the concept of a Solution of a System of Equations. The interviews were analyzed using APOS tools, in particular the ideas of Action, Process, Object and Schema, and Genetic Decomposition. The analysis of the interviews revealed several misconceptions of Solution. The analysis also revealed…

  4. Teaching Nature of Science to Preservice Science Teachers: A Phenomenographic Study of Chinese Teacher Educators' Conceptions

    NASA Astrophysics Data System (ADS)

    Wan, Zhi Hong; Wong, Siu Ling; Zhan, Ying

    2013-10-01

    Drawing from the phenomenographic perspective, this study investigated Chinese science teacher educators' conceptions of teaching nature of science (NOS) to preservice science teachers through two semi-structured interviews. The subjects were twenty-four science teacher educators in the developed regions in China. Five key dimensions emerged from the data on the conceptions of teaching NOS, including value of teaching NOS, NOS content to be taught, incorporation of NOS instruction in courses, learning of NOS, and role of the teacher. While some of these dimensions share much similarity with those reported in the studies of conceptions of teaching in general, some are distinctively different, which is embedded in some unique features of teaching NOS to preservice science teachers. These key dimensions can constitute the valuable components of the module or course to train science teachers or teacher educators to teach NOS, provide a framework to interpret the practice of teaching NOS, as well as lay a foundation for probing the conceptions of teaching NOS of other groups of subjects (e.g., school teachers' conceptions of teaching NOS) or in other contexts (e.g., teaching NOS to in-service teacher).

  5. Rate-Limited Organic Solute Sorption to Natural Soil: Concentration, Organic Matter Content, and Solute Effects

    NASA Astrophysics Data System (ADS)

    Smith, J. A.; Riddle, S. A.; Deitsch, J. J.

    2002-05-01

    Sorption of phenanthrene to two soil types and 1,2-dichlorobenzene (DCB) to three soil types was quantified for different incubation times and for different equilibrium aqueous concentrations using a batch sorption methodology. The organic-carbon contents of the soils studied ranged from 0.5 to 30%. A lognormal distributed rate model was used to simulate the kinetic sorption data. The simulations were conducted to determine the optimal untransformed mean and standard deviation for the lognormal distribution of the water-soil mass-transfer coefficients. The 95% confidence regions for these parameters were also determined. The means of the mass-transfer coefficient distributions between experiments were then compared. For phenanthrene sorption to the Woodburn soil (1.3% organic carbon), and for DCB sorption to the Woodburn and Picatinny sand (0.53% organic carbon) soils, the mean mass-transfer rate increased with increasing solute aqueous equilibrium concentration. For phenanthrene sorption to the Picatinny sand and 1,2-dichlorobenzene sorption to the Picatinny peat soil (30% organic carbon), there was no strong relation between the distribution of mass-transfer coefficients and the equilibrium aqueous concentration of the solute. Second, the mean of the distribution of mass-transfer rate coefficients decreased as the organic-carbon content of the sorbent increased. This effect was observed for both solutes. Third, for a given soil and relative concentration (equilibrium solute concentration normalized to aqueous solubility), the means of the distribution of mass-transfer rate coefficients were consistently greater for phenanthrene than for DCB. The mechanistic implications of these observations will be discussed.

  6. Eulerian-Lagrangian solution of the convection-dispersion equation in natural co-ordinates.

    USGS Publications Warehouse

    Cheng, R.T.; Casulli, V.; Milford, S.N.

    1984-01-01

    The vast majority of numerical investigations of transport phenomena use an Eulerian formulation for the convenience that the computational grids are fixed in space. An Eulerian-Lagrangian method (ELM) of solution for the convection-dispersion equation is discussed and analyzed. The ELM uses the Lagrangian concept in an Eulerian computational grid system.-from Authors

  7. Evolvability Is an Evolved Ability: The Coding Concept as the Arch-Unit of Natural Selection.

    PubMed

    Janković, Srdja; Ćirković, Milan M

    2016-03-01

    Physical processes that characterize living matter are qualitatively distinct in that they involve encoding and transfer of specific types of information. Such information plays an active part in the control of events that are ultimately linked to the capacity of the system to persist and multiply. This algorithmicity of life is a key prerequisite for its Darwinian evolution, driven by natural selection acting upon stochastically arising variations of the encoded information. The concept of evolvability attempts to define the total capacity of a system to evolve new encoded traits under appropriate conditions, i.e., the accessible section of total morphological space. Since this is dependent on previously evolved regulatory networks that govern information flow in the system, evolvability itself may be regarded as an evolved ability. The way information is physically written, read and modified in living cells (the "coding concept") has not changed substantially during the whole history of the Earth's biosphere. This biosphere, be it alone or one of many, is, accordingly, itself a product of natural selection, since the overall evolvability conferred by its coding concept (nucleic acids as information carriers with the "rulebook of meanings" provided by codons, as well as all the subsystems that regulate various conditional information-reading modes) certainly played a key role in enabling this biosphere to survive up to the present, through alterations of planetary conditions, including at least five catastrophic events linked to major mass extinctions. We submit that, whatever the actual prebiotic physical and chemical processes may have been on our home planet, or may, in principle, occur at some time and place in the Universe, a particular coding concept, with its respective potential to give rise to a biosphere, or class of biospheres, of a certain evolvability, may itself be regarded as a unit (indeed the arch-unit) of natural selection.

  8. Evolvability Is an Evolved Ability: The Coding Concept as the Arch-Unit of Natural Selection

    NASA Astrophysics Data System (ADS)

    Janković, Srdja; Ćirković, Milan M.

    2016-03-01

    Physical processes that characterize living matter are qualitatively distinct in that they involve encoding and transfer of specific types of information. Such information plays an active part in the control of events that are ultimately linked to the capacity of the system to persist and multiply. This algorithmicity of life is a key prerequisite for its Darwinian evolution, driven by natural selection acting upon stochastically arising variations of the encoded information. The concept of evolvability attempts to define the total capacity of a system to evolve new encoded traits under appropriate conditions, i.e., the accessible section of total morphological space. Since this is dependent on previously evolved regulatory networks that govern information flow in the system, evolvability itself may be regarded as an evolved ability. The way information is physically written, read and modified in living cells (the "coding concept") has not changed substantially during the whole history of the Earth's biosphere. This biosphere, be it alone or one of many, is, accordingly, itself a product of natural selection, since the overall evolvability conferred by its coding concept (nucleic acids as information carriers with the "rulebook of meanings" provided by codons, as well as all the subsystems that regulate various conditional information-reading modes) certainly played a key role in enabling this biosphere to survive up to the present, through alterations of planetary conditions, including at least five catastrophic events linked to major mass extinctions. We submit that, whatever the actual prebiotic physical and chemical processes may have been on our home planet, or may, in principle, occur at some time and place in the Universe, a particular coding concept, with its respective potential to give rise to a biosphere, or class of biospheres, of a certain evolvability, may itself be regarded as a unit (indeed the arch-unit) of natural selection.

  9. Flexible thermal control systems: Concepts and solutions for Clean Air Act and NESHAP regulation limits

    SciTech Connect

    Deshpande, M.S.; Curtis, T.; Harada, Y.

    1996-03-01

    The impact of limits set by the Clean Air Act (1990) and NESHAP regulation on the use of flexible thermal control material systems will be discussed. These regulations affect use of flexible thermal control material systems and baffle coating systems such as S13GP/LO-1, MH21S/LO, MH41SCB/LO, MH21SC/LO and MH2200 which are currently used on space hardware. Regulatory activities impact on space coatings will be discussed. During the last symposium, we have described the material concepts and process alternates along with the initial results obtained. These efforts have been continued during the past as IR&D efforts at IITRI. The results on suggested material concepts and process solutions will be presented along with data obtained for CVCM/TML properties. These data indicate approaches for control technique guidelines (CTGS) for further use of the flexible thermal control materials and baffle coatings to meet Clean Air Act and NESHAP regulations. The cost impact of such CTG on space hardware will also be discussed. {copyright} {ital 1996 American Institute of Physics.}

  10. New concepts, experimental approaches, and dereplication strategies for the discovery of novel phytoestrogens from natural sources.

    PubMed

    Michel, Thomas; Halabalaki, Maria; Skaltsounis, Alexios-Leandros

    2013-05-01

    Phytoestrogens constitute an attractive research topic due to their estrogenic profile and their biological involvement in woman's health. Therefore, numerous studies are currently performed in natural products chemistry area aiming at the discovery of novel phytoestrogens. The main classes of phytoestrogens are flavonoids (flavonols, flavanones), isoflavonoids (isoflavones, coumestans), lignans, stilbenoids as well as miscellaneous chemical groups abundant in several edible and/or medicinal plants, belonging mostly to the Leguminosae family. As for other bioactives, the detection of new structures and more potent plant-derived phytoestrogens typically follows the general approaches currently available in the natural product discovery process. Plant-based approaches selected from traditional medicine knowledge and bioguided concepts are routinely employed. However, these approaches are associated with serious disadvantages such as time-consuming, repeated, and labor intensive processes as well as lack of specificity and reproducibility. In recent years, the natural products chemistry became more technology-driven, and several different strategies have been developed. Structure-oriented procedures and miniaturized approaches employing advanced hyphenated analytical platforms have recently emerged. They facilitate significantly not only the discovery of novel phytoestrogens but also the dereplication procedure leading to the anticipation of major drawbacks in natural products discovery. In this review, apart from the traditional concepts followed in phytochemistry for the discovery of novel biologically active compounds, recent applications in the field of extraction, analysis, fractionation, and identification of phytoestrogens will be discussed. Moreover, specific methodologies combining identification of actives and biological evaluation in parallel, such as liquid chromatography-biochemical detection, frontal affinity chromatography-mass spectrometry and pulsed

  11. Conceptions of the nature of science and worldviews of preservice elementary science teachers in Taiwan

    NASA Astrophysics Data System (ADS)

    Liu, Shiang-Yao

    This exploratory investigation aimed to identify preservice science teachers' conceptions of the nature of science (NOS), and worldviews that represent their culturally dependent beliefs about the world, in the context of Taiwan. The interrelationships between the responses elicited from both the assessments of NOS understandings and worldviews were examined. Participants included 54 third-year students enrolled in the departments of science education and mathematics education at a teachers college. Their worldviews and NOS conceptions were tabulated by two questionnaires and 14 of them were purposefully selected to participate follow-up interviews. The worldview questionnaire contained five open-ended items, of which each examines one of the worldview domains in Kearney's model (1984). The NOS questionnaire consisting of nine open-ended questions was developed, specifically addressing cultural characteristics, to assess participants' views on the development of scientific knowledge. An anthropocentric-moderate continuum emerged to describe participants' views of the humanity's relationship with Nature. It was found that participants with informed NOS conceptions were more likely to emphasize harmony with Nature, recognize the limitations of scientific knowledge, and accept the idea that science involves subjective and cultural components. On the other hand, participants who provided a pragmatic perspective of Nature seemed to possess narrow views about the scientific enterprises by describing science as close to technology and as a materialistic benefit. Authoritarianism was also a noticeable cultural trait hindering some participants from reflecting on the values inherent to the development of scientific knowledge, and also prohibiting them from searching empirical evidence to solve problems. It was found that there were differences between science education and mathematics education majors in their worldviews and NOS understandings. The results in this study not

  12. Inter-clinic variation in the chances of natural conception of subfertile couples.

    PubMed

    Tjon-Kon-Fat, R I; Lar, D N; Steyerberg, E W; Broekmans, F J; Hompes, P; Mol, B W J; Steures, P; Bossuyt, P M M; van der Veen, F; van der Steeg, J W; Eijkemans, M J C

    2013-05-01

    Are there differences between clinics in the chances of natural conception of couples? We found significant differences between clinics in the couples' natural conception chances, which could not be explained by differences in characteristics of the patients or the clinics. In pooled data from multiple centers the synthesis prediction model for natural conception was found to be valid, yet the outcome of interest (i.e. natural conception) might differ between centers. Possible differences between clinics in natural conception rates, as well as the validity of the prediction model in each individual clinic are addressed in this paper. A secondary data-analysis of a prospective cohort study among 3020 subfertile couples recruited in 38 clinics in the Netherlands between January 2002 and December 2004. Clinics with less than 20 couples were excluded from the analyses, resulting in 21 clinics with 2916 couples. Inclusion of 2916 subfertile couples who underwent a basic fertility work-up. Couples were excluded who had a fertility disorder (one or two-sided tubal pathology, ovulation disorder, total motile sperm count <3 × 10(6)). Included couples were counseled for expectant management for at least six months or followed until the first day of treatment. Follow-up began at the completion of the fertility work-up. Couples lost to follow-up were censored at the last day of contact. Kaplan-Meier survival curves and a log-rank statistic were estimated. Crude and adjusted hazard ratios were determined, adjusted for patient characteristics and the type of clinic (university hospitals with an assisted conception unit (ACU), non-university hospitals with an ACU and non-university hospitals without an ACU). Hazard ratios were also ascertained with empirical Bayes (EB) estimates. Validation of the prediction model per clinic was performed through calibration. We found significant differences between clinics in the chance of ongoing pregnancy (P < 0.001); even after adjustment

  13. Analysis of Saudi Arabian middle and high school science teachers' conceptions of the nature of science

    NASA Astrophysics Data System (ADS)

    Almazroa, Hiya Mohammed

    This study was conducted to explore Saudi middle and high school science teachers' conceptions of the Nature of Science (NOS). It also detected the effects of gender, science content major, and years of teaching experience on teachers' conceptions of the NOS. The study included a sample of 786 science teachers (137 male and 649 female) who were teaching in middle and high schools in Riyadh, Saudi Arabia in the 1995-1996 academic year. The study was conducted using a translated version of the Nature of Science Scale (NOSS) developed by Kimball (1967). The scale contains 29 items ranging from "agree" to "disagree", and the scoring of the items ranged from 29 to 87. The lowest score is 29 (1 x 29) and the highest score possible on the test is 87 (3 x 29 items). The data collected was statistically analyzed using descriptive statistics and Analysis of Variance (ANOVA). The study revealed that Saudi science teachers as a group hold numerous misconceptions about the NOS with a significant difference in understanding the NOS between the male and female teachers. The study also showed that teachers with a major in physics held more adequate views than did teachers with other majors. In addition, novice teachers were found to have more adequate conceptions of the NOS than did experienced teachers.

  14. Sperm quality and its relationship to natural and assisted conception: British Fertility Society guidelines for practice.

    PubMed

    Tomlinson, Mathew; Lewis, Sheena; Morroll, David

    2013-09-01

    Reports on the influence of semen parameters on natural or assisted pregnancy are contradictory, suggesting that the many confounding variables which contribute to outcome have not been taken into account. However, it is possible to derive some consensus for both natural and assisted conception by focussing on studies which use WHO-recommended semen analysis on relatively large populations, applying appropriate statistics and accounting for 'female factors'. The concentration of progressively motile sperm has consistently been shown to be the most predictive factor with regard to outcome. Around 64% of studies suggest that a reasonable chance of success with artificial insemination requires at least 5 × 10⁶ motile sperm and this is supported by the WHO's revised reference range for natural conception. Sperm morphology remains controversial, with a lack of standardisation across centres, the adoption of ever-stricter scoring criteria and changing reference values. Antisperm antibodies do not appear to influence outcome independently of sperm motility and agglutination. Sperm DNA damage appears to be related to sperm quality, embryo development and pregnancy loss, yet there remains no consensus on the best testing procedures, clinical reference values and how patients with an adverse result should be managed. In conclusion, laboratories should continue to focus on reducing the uncertainty and improving the quality of their basic semen analysis.

  15. The Nature of Science in Science Curricula: Methods and concepts of analysis

    NASA Astrophysics Data System (ADS)

    Ferreira, Sílvia; Morais, Ana M.

    2013-11-01

    The article shows methods and concepts of analysis of the nature of science in science curricula through an exemplary study made in Portugal. The study analyses the extent to which the message transmitted by the Natural Science curriculum for Portuguese middle school considers the nature of science. It is epistemologically and sociologically grounded with particular emphasis on Bernstein's theory of pedagogic discourse and Ziman's conceptualization of science construction. The study used a mixed methodology and followed a dialectical process between the theoretical and the empirical. The results show that the nature of science has a low status in the curriculum with the exception of the external sociological dimension of science. Intra-disciplinary relations between scientific and metascientific knowledge are mostly absent. Recontextualization processes occurred between the two main parts of the curriculum. These results are discussed and their consequences in terms of scientific learning are explored. The mode of analysis used in the study has the potential of highlighting the level of a science curriculum, in terms of specific aspects of the nature of science.

  16. Sperm selection in natural conception: what can we learn from Mother Nature to improve assisted reproduction outcomes?

    PubMed Central

    Sakkas, Denny; Ramalingam, Mythili; Garrido, Nicolas; Barratt, Christopher L.R.

    2015-01-01

    BACKGROUND In natural conception only a few sperm cells reach the ampulla or the site of fertilization. This population is a selected group of cells since only motile cells can pass through cervical mucus and gain initial entry into the female reproductive tract. In animals, some studies indicate that the sperm selected by the reproductive tract and recovered from the uterus and the oviducts have higher fertilization rates but this is not a universal finding. Some species show less discrimination in sperm selection and abnormal sperm do arrive at the oviduct. In contrast, assisted reproductive technologies (ART) utilize a more random sperm population. In this review we contrast the journey of the spermatozoon in vivo and in vitro and discuss this in the context of developing new sperm preparation and selection techniques for ART. METHODS A review of the literature examining characteristics of the spermatozoa selected in vivo is compared with recent developments in in vitro selection and preparation methods. Contrasts and similarities are presented. RESULTS AND CONCLUSIONS New technologies are being developed to aid in the diagnosis, preparation and selection of spermatozoa in ART. To date progress has been frustrating and these methods have provided variable benefits in improving outcomes after ART. It is more likely that examining the mechanisms enforced by nature will provide valuable information in regard to sperm selection and preparation techniques in vitro. Identifying the properties of those spermatozoa which do reach the oviduct will also be important for the development of more effective tests of semen quality. In this review we examine the value of sperm selection to see how much guidance for ART can be gleaned from the natural selection processes in vivo. PMID:26386468

  17. Sperm selection in natural conception: what can we learn from Mother Nature to improve assisted reproduction outcomes?

    PubMed

    Sakkas, Denny; Ramalingam, Mythili; Garrido, Nicolas; Barratt, Christopher L R

    2015-01-01

    In natural conception only a few sperm cells reach the ampulla or the site of fertilization. This population is a selected group of cells since only motile cells can pass through cervical mucus and gain initial entry into the female reproductive tract. In animals, some studies indicate that the sperm selected by the reproductive tract and recovered from the uterus and the oviducts have higher fertilization rates but this is not a universal finding. Some species show less discrimination in sperm selection and abnormal sperm do arrive at the oviduct. In contrast, assisted reproductive technologies (ART) utilize a more random sperm population. In this review we contrast the journey of the spermatozoon in vivo and in vitro and discuss this in the context of developing new sperm preparation and selection techniques for ART. A review of the literature examining characteristics of the spermatozoa selected in vivo is compared with recent developments in in vitro selection and preparation methods. Contrasts and similarities are presented. New technologies are being developed to aid in the diagnosis, preparation and selection of spermatozoa in ART. To date progress has been frustrating and these methods have provided variable benefits in improving outcomes after ART. It is more likely that examining the mechanisms enforced by nature will provide valuable information in regard to sperm selection and preparation techniques in vitro. Identifying the properties of those spermatozoa which do reach the oviduct will also be important for the development of more effective tests of semen quality. In this review we examine the value of sperm selection to see how much guidance for ART can be gleaned from the natural selection processes in vivo. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology.

  18. Pharmacognosy and reverse pharmacognosy: a new concept for accelerating natural drug discovery.

    PubMed

    Do, Quoc-Tuan; Bernard, Philippe

    2004-11-01

    Combinatorial chemistry and high-throughput screening (HTS) have led to the identification of numerous agents that are active and selective in vitro. Identifying drugs that are active in vivo, however, remains a challenge. Traditional medicinal cures based on natural materials have proven useful for many populations worldwide, representing huge and disperse tracts of knowledge that are sometimes neglected in Western research due to differences in the concepts of illness. In this review we introduce a new approach, termed 'reverse pharmacognosy' (from diverse molecules to plants), which can be coupled with pharmacognosy (from biodiverse plants to molecules). Reverse pharmacognosy utilizes new techniques, such as HTS, virtual screening and a knowledge database containing the traditional uses of plants. Integrating pharmacognosy and reverse pharmacognosy in the research process may provide an efficient and rapid tool for natural drug discovery.

  19. The World Atlas of Desertification assessment concept for conscious land use solutions

    NASA Astrophysics Data System (ADS)

    Cherlet, Michael; Ivits, Eva; Kutnjak, Hrvoje; Smid, Marek; Sommer, Stefan; Zucca, Claudio

    2015-04-01

    Land degradation and desertification are complex phenomena that result in environmental damage, economic inefficiency and social inequity and are reflected by a reducing productive capacity of the land and soil. Research indicated that they are driven by a multiple but a limited number of causal aspects that unbalance the capacity of the environment system to sustainably produce ecosystem services and economic value. Competition for land, driven by societal needs or economic opportunities, adds further stress on the land resources. To address these complex global challenges, a monitoring and assessment system offering up-to-date information on the status and trends of land degradation and their causes and effects is needed to provide science-based routes for possible land use solutions. The assessment concept that has been outlined for the compilation of the new World Atlas of Desertification (WAD) confronts this complexity by converging evidence of stress on the land system caused by various issues. These issues relate to sets of dynamics of the human-environment system and include changing agricultural or pastoral land use and management practices, changing population and societal aspects, changing aridity and drought. The WAD describes the issues, spatially documents their change, whenever data is available, highlights the importance of the issues in relation to land degradation processes and illustrates the integrated assessment concepts. The first step is the preparation of solid global data layers that are related to, or express aspects that can be related to, land-system productivity dynamics and status. These can be used for identifying and evaluating the interaction of spatial variables with the land-system productivity dynamics. Initial analysis of the land productivity dynamics within stratified land cover/use areas, such as the global croplands, show substantial differences in the extension, geographic location and possible related causes of potentially

  20. Students' Conceptions of the Nature of Science: Perspectives from Canadian and Korean Middle School Students

    NASA Astrophysics Data System (ADS)

    Park, Hyeran; Nielsen, Wendy; Woodruff, Earl

    2014-05-01

    This study examined and compared students' understanding of nature of science (NOS) with 521 Grade 8 Canadian and Korean students using a mixed methods approach. The concepts of NOS were measured using a survey that had both quantitative and qualitative elements. Descriptive statistics and one-way multivariate analysis of variances examined the quantitative data while a conceptually clustered matrix classified the open-ended responses. The country effect could explain 3-12 % of the variances of subjectivity, empirical testability and diverse methods, but it was not significant for the concepts of tentativeness and socio-cultural embeddedness of science. The open-ended responses showed that students believed scientific theories change due to errors or discoveries. Students regarded empirical evidence as undeniable and objective although they acknowledged experiments depend on theories or scientists' knowledge. The open responses revealed that national situations and curriculum content affected their views. For our future democratic citizens to gain scientific literacy, science curricula should include currently acknowledged NOS concepts and should be situated within societal and cultural perspectives.

  1. Preservice Biology Teachers' Conceptions About the Tentative Nature of Theories and Models in Biology

    NASA Astrophysics Data System (ADS)

    Reinisch, Bianca; Krüger, Dirk

    2016-11-01

    In research on the nature of science, there is a need to investigate the role and status of different scientific knowledge forms. Theories and models are two of the most important knowledge forms within biology and are the focus of this study. During interviews, preservice biology teachers (N = 10) were asked about their understanding of theories and models. They were requested to give reasons why they see theories and models as either tentative or certain constructs. Their conceptions were then compared to philosophers' positions (e.g., Popper, Giere). A category system was developed from the qualitative content analysis of the interviews. These categories include 16 conceptions for theories (n tentative = 11; n certain = 5) and 18 conceptions for models (n tentative = 10; n certain = 8). The analysis of the interviews showed that the preservice teachers gave reasons for the tentativeness or certainty of theories and models either due to their understanding of the terms or due to their understanding of the generation or evaluation of theories and models. Therefore, a variety of different terminology, from different sources, should be used in learning-teaching situations. Additionally, an understanding of which processes lead to the generation, evaluation, and refinement or rejection of theories and models should be discussed with preservice teachers. Within philosophy of science, there has been a shift from theories to models. This should be transferred to educational contexts by firstly highlighting the role of models and also their connections to theories.

  2. Confronting, Representing, and Believing Counterintuitive Concepts: Navigating the Natural and the Supernatural

    PubMed Central

    Lane, Jonathan D.; Harris, Paul. L.

    2014-01-01

    Recent research shows that even preschoolers are skeptical; they frequently reject claims from other people when the claims conflict with their own perceptions and concepts. Yet, despite their skepticism, both children and adults come to believe in a variety of phenomena that defy their first-hand perceptions and intuitive conceptions of the world. In this review, we explore how children and adults acquire such concepts. We describe how a similar developmental process underlies mental representation of both the natural and the supernatural world, and we detail this process for two prominent supernatural counterintuitive ideas—God and the afterlife. In doing so, we highlight the fact that conceptual development does not always move in the direction of greater empirical truth, as described within naturalistic domains. We consider factors that likely help overcome skepticism, and in doing so promote belief in counterintuitive phenomena. These factors include qualities of the learners, aspects of the context, qualities of the informants, and qualities of the information. PMID:24683418

  3. Nature as an engineer: one simple concept of a bio-inspired functional artificial muscle.

    PubMed

    Schmitt, S; Haeufle, D F B; Blickhan, R; Günther, M

    2012-09-01

    The biological muscle is a powerful, flexible and versatile actuator. Its intrinsic characteristics determine the way how movements are generated and controlled. Robotic and prosthetic applications expect to profit from relying on bio-inspired actuators which exhibit natural (muscle-like) characteristics. As of today, when constructing a technical actuator, it is not possible to copy the exact molecular structure of a biological muscle. Alternatively, the question may be put how its characteristics can be realized with known mechanical components. Recently, a mechanical construct for an artificial muscle was proposed, which exhibits hyperbolic force-velocity characteristics. In this paper, we promote the constructing concept which is made by substantiating the mechanical design of biological muscle by a simple model, proving the feasibility of its real-world implementation, and checking their output both for mutual consistency and agreement with biological measurements. In particular, the relations of force, enthalpy rate and mechanical efficiency versus contraction velocity of both the construct's technical implementation and its numerical model were determined in quick-release experiments. All model predictions for these relations and the hardware results are now in good agreement with the biological literature. We conclude that the construct represents a mechanical concept of natural actuation, which is suitable for laying down some useful suggestions when designing bio-inspired actuators.

  4. Advanced onboard storage concepts for natural gas-fueled automotive vehicles

    NASA Technical Reports Server (NTRS)

    Remick, R. J.; Elkins, R. H.; Camara, E. H.; Bulicz, T.

    1984-01-01

    The evaluation of several advanced concepts for storing natural gas at reduced pressure is presented. The advanced concepts include adsorption on high surface area carbon, adsorption in high porosity zeolite, storage in clathration compounds, and storage by dissolution in liquid solvents. High surface area carbons with high packing density are the best low pressure storage mediums. A simple mathematical model is used to compare adsorption storage on a state of the art carbon with compression storage. The model indicates that a vehicle using adsorption storage of natural gas at 3.6 MPa will have 36 percent of the range, on the EPA city cycle, of a vehicle operating on a compression storage system having the same physical size and a peak storage pressure of 21 MPa. Preliminary experiments and current literature suggest that the storage capacity of state of the art carbons could be improved by as much as 50 percent, and that adsorption systems having a capacity equal to compression storage at 14 MPa are possible without exceeding a maximum pressure of 3.6 MPa.

  5. The nature of multiple solutions for surface wind speed over the oceans from scatterometer measurements

    NASA Technical Reports Server (NTRS)

    Price, J. C.

    1975-01-01

    The satellite SEASAT-A will carry a radar scatterometer in order to measure microwave backscatter from the sea surface. From pairs of radar measurements at angles separated by 90 deg in azimuth the surface wind speed and direction may be inferred, though not uniquely. The character of the solutions for wind speed and direction is displayed, as well as the nature of the ambiguities of these solutions. An economical procedure for handling such data is described, plus a criterion for the need for conventional (surface) data in order to resolve the ambiguities of solutions.

  6. Making Learning Last: Teachers' Long-Term Retention of Improved Nature of Science Conceptions and Instructional Rationales

    ERIC Educational Resources Information Center

    Mulvey, Bridget K.; Bell, Randy L.

    2017-01-01

    Despite successful attempts to improve learners' nature of science (NOS) conceptions through explicit, reflective approaches, retention of improved conceptions is rarely addressed in research. The issue of context for NOS instruction has implications for this retention. Whether to contextualise has been the question occupying science educators'…

  7. Professional Development of Elementary and Science Teachers in a Summer Science Camp: Changing Nature of Science Conceptions

    ERIC Educational Resources Information Center

    Karaman, Ayhan

    2016-01-01

    Many countries all over the world have recently integrated nature of science (NOS) concepts into their science education standards. Providing professional support to teachers about NOS concepts is crucially important for successful implementation of the standards. For this purpose, a summer science camp was offered to elementary and science…

  8. Dynamics of a Definition: A Framework to Analyse Student Construction of the Concept of Solution to a Differential Equation

    ERIC Educational Resources Information Center

    Raychaudhuri, Debasree

    2008-01-01

    In this note we develop a framework that makes explicit the inherent dynamic structure of certain mathematical definitions by means of the four facets of context-entity-process-object. These facets and their interrelations are then used to capture and interpret specific aspects of student constructions of the concept of solution to first order…

  9. Solitary wave solutions of nonlinear financial markets: data-modeling-concept-practicing

    NASA Astrophysics Data System (ADS)

    Ma, Jin-Long; Ma, Fei-Te

    2007-07-01

    This paper seeks to solve the difficult nonlinear problem in financial markets on the complex system theory and the nonlinear dynamics principle, with the data-model-concept-practice issue-oriented reconstruction of the phase space by the high frequency trade data. In theory, we have achieved the differentiable manifold geometry configuration, discovered the Yang-Mills functional in financial markets, obtained a meaningful conserved quantity through corresponding space-time non-Abel localization gauge symmetry transformation, and derived the financial solitons, which shows that there is a strict symmetry between manifold fiber bundle and guage field in financial markets. In practical applications of financial markets, we have repeatedly carried out experimental tests in a fluctuant evolvement, directly simulating and validating the existence of solitons by researching the price fluctuations (society phenomena) using the same methods and criterion as in natural science and in actual trade to test the stock Guangzhou Proprietary and the futures Fuel Oil in China. The results demonstrate that the financial solitons discovered indicates that there is a kind of new substance and form of energy existing in financial trade markets, which likely indicates a new science paradigm in the economy and society domains beyond physics.

  10. Nature of fluid flows in differentially heated cylindrical container filled with a stratified solution

    NASA Technical Reports Server (NTRS)

    Wang, Jai-Ching

    1992-01-01

    Semiconductor crystals such as Hg(1-x)Cd(x)Te grown by unidirectional solidification Bridgmann method have shown compositional segregations in both the axial and radial directions. Due to the wide separation between the liquidus and the solidus of its pseudobinary phase diagram, there is a diffusion layer of higher HgTe content built up in the melt near the melt-solid interface which gives a solute concentration gradient in the axial direction. Because of the higher thermal conductivity in the melt than that in the crystal there is a thermal leakage through the fused silica crucible wall near the melt-solid interface. This gives a thermal gradient in the radial direction. Hart (1971), Thorpe, Hutt and Soulsby (1969) have shown that under such condition a fluid will become convectively unstable as a result of different diffusivities of temperature and solute. It is quite important to understand the effects of this thermosolute convection on the compositional segregation in the unidirectionally solidified crystals. To reach this goal, we start with a simplified problem. We study the nature of fluid flows of a stratified solution in a cylindrical container with a radial temperature gradient. The cylindrical container wall is considered to be maintained at a higher temperature than that at the center of the solution and the solution in the lower gravitational direction has higher solute concentration which decrease linearly to a lower concentration and then remain constant to the top of the solution. The sample solution is taken to be salt water.

  11. Challenging the Concept of Natural Distributions: Global Change Turns Trees Into Weeds

    NASA Astrophysics Data System (ADS)

    Gleadow, R.; O'Leary, B.; Burd, M.

    2015-12-01

    National parks and nature reserves are set aside to preserve certain ecosystems, reflecting species distributions at a moment in time. Changing climate and fire dynamics can mean that the species most suited to that area are different, leading new tree species to 'invade' the conservation areas. Pittosporum undulatum is an invasive tree native tree species with a natural range from southeast Queensland to Eastern Victoria, Australia. Soon after European settlement this species became a popular ornamental tree in gardens and was planted outside of its natural range across the continent and introduced to the USA (where it is known as Victorian Box), the Hawaiian Islands, Jamaica, southern Africa and the Azores. The reason this is important is because high density of P. undulatum lead to reduced biodiversity and often the complete suppression of regeneration of exiting forest trees. In Australia, changes in fire dynamics have played a major part in its in dominance. New strategies for forest management were proposed by Gleadow an Ashton in the 1980s, but lack of action has led us to predict that the entire Dandenong Ranges, near Melbourne, will be invaded within 25 years resulting in the loss of a major recreational and conservation area. This is a model of the type of problems that can be expected as the climate envelope for species changes in the coming century, challenging the very concept of a "native ".

  12. RMS Titanic and the emergence of new concepts on consortial nature of microbial events.

    PubMed

    Cullimore, D Roy; Pellegrino, Charles; Johnston, Lori

    2002-01-01

    The RMS Titanic sank in 1912 and created a historical event that still ripples through time. Stories were told and lessons learned but the science has only just begun. Today the fading remains of the ship resemble the hanging gardens of Babylon except that it is not plants that drape the walls but complex microbial growths called rusticles. These organisms have been found to be not a species, like plants and animals, but to be structures created by complex communities of bacterial species. Like the discovery of tube worms in the mid-oceanic vents, the nature of these rusticles presents another biological discovery of a fundamental nature. Essentially these microbial consortia on the RMS Titanic have generated structures of a mass that would rival whales and elephants while gradually extracting the iron from the steel. Rusticle-like consortia appear to play many roles within the environment, and it is perhaps the RMS Titanic that is showing that there is a new way to understand the form, function, and nature of microorganisms. This understanding would develop by considering the bacteria not as individual species functioning independently but as consortia of species functioning in community structures within a common habitat. This concept, if adopted, would change dramatically the manner in which a microbial ecologist and any scientist or engineer would view the occurrence of a slime, encrustation, biocolloid, rust flake, iron pan, salt deposit, and perhaps even some of the diseases that remain unexplained as a disease of unknown cause.

  13. The evolution of cellular computing: nature's solution to a computational problem.

    PubMed

    Landweber, L F; Kari, L

    1999-10-01

    How do cells and nature 'compute'? They read and 'rewrite' DNA all the time, by processes that modify sequences at the DNA or RNA level. In 1994, Adleman's elegant solution to a seven-city directed Hamiltonian path problem using DNA launched the new field of DNA computing, which in a few years has grown to international scope. However, unknown to this field, two ciliated protozoans of the genus Oxytricha had solved a potentially harder problem using DNA several million years earlier. The solution to this problem, which occurs during the process of gene unscrambling, represents one of nature's ingenious solutions to the problem of the creation of genes. RNA editing, which can also be viewed as a computational process, offers a second algorithm for the construction of functional genes from encrypted pieces of the genome.

  14. A Resource for Eliciting Student Alternative Conceptions: Examining the Adaptability of a Concept Inventory for Natural Selection at the Secondary School Level

    ERIC Educational Resources Information Center

    Lucero, Margaret M.; Petrosino, Anthony J.

    2017-01-01

    The Conceptual Inventory of Natural Selection (CINS) is an example of a research-based instrument that assesses conceptual understanding in an area that contains well-documented alternative conceptions. Much of the CINS's use and original validation has been relegated to undergraduate settings, but the information learned from student responses on…

  15. Student Conceptions of Ionic Compounds in Solution and the Influences of Sociochemical Norms on Individual Learning

    NASA Astrophysics Data System (ADS)

    Warfa, Abdi-Rizak M.

    Using the symbolic interactionist perspective that meaning is constituted as individuals interact with one another, this study examined how group thinking during cooperative inquiry-based activity on chemical bonding theories shaped and influenced college students' understanding of the properties of ionic compounds in solution. The analysis revealed the development of sociochemical norms and specific ways of reasoning about chemical ideas that led to shifts in student thinking and understanding of the nature of dissolved ionic solids. The analysis similarly revealed two kinds of teacher-initiated discourses, dialogical and monologic, that impacted student learning differently. I discuss the nature of this teacher-initiated discourse and number of moves, such as confirming, communicative, and re-orienting, that the course instructor made to communicate to students what counts as justifiable chemical reasoning and appropriate representations of chemical knowledge. I further describe the use of sociochemical dialogues as lens to study the ways in which chemistry instructors and students develop normative ways of reasoning and chemical justifications. Because the activity was designed as an intervention to target student misconceptions about ionic bonding, I also examined the extent to which the activity elicited and corrected commonly found student chemical misconceptions. To do so, student-generated particulate drawings were coded qualitatively into one of four broad themes: i) use of molecular framework with discrete atoms, ii) use of ionic framework with discrete ionic species, iii) use of quasi-ionic framework with partial ionic-molecular thinking, or iv) use of an all-encompassing "other" category. The findings suggested the intervention significantly improved students' conceptual knowledge of ionic compounds in solution - there was statistically significant increase in the number of drawings using ionic and quasi-ionic frameworks in the pre-activity vs. post

  16. 'Normal', 'natural', 'good' or 'good-enough' birth: examining the concepts.

    PubMed

    Darra, Susanne

    2009-12-01

    In the face of increasing intervention in childbirth, 'normal birth' is currently being promoted by the World Health Organization, national governments, professional bodies and other organisations throughout the world. This paper takes a postmodernist stance and explores the idea of the 'normal' before going on to analyse normal childbirth, referring to concepts of the normal and the natural. It refers to historical developments in childbearing and lay organisations along with research relating to women's views of childbirth, to question the appropriateness of using 'normal' to describe the very individual experiences of childbirth. It laments the way in which women have been treated and arguably continue to be 'cared for' in maternity/obstetric services. It adds to the current discussion by recalling psychoanalytical theory and philosophical analysis to conclude with a call for future consideration of the 'good-enough' birth instead of concentrating on promoting normal birth which is very difficult, if not impossible to define in retrospect, or to prospectively promote.

  17. An Investigation into the Relationship between Students' Conceptions of the Particulate Nature of Matter and Their Understanding of Chemical Bonding

    ERIC Educational Resources Information Center

    Othman, Jazilah; Treagust, David F.; Chandrasegaran, A. L.

    2008-01-01

    A thorough understanding of chemical bonding requires familiarity with the particulate nature of matter. In this study, a two-tier multiple-choice diagnostic instrument consisting of ten items (five items involving each of the two concepts) was developed to assess students' understanding of the particulate nature of matter and chemical bonding so…

  18. An Investigation into the Relationship between Students' Conceptions of the Particulate Nature of Matter and Their Understanding of Chemical Bonding

    ERIC Educational Resources Information Center

    Othman, Jazilah; Treagust, David F.; Chandrasegaran, A. L.

    2008-01-01

    A thorough understanding of chemical bonding requires familiarity with the particulate nature of matter. In this study, a two-tier multiple-choice diagnostic instrument consisting of ten items (five items involving each of the two concepts) was developed to assess students' understanding of the particulate nature of matter and chemical bonding so…

  19. The Electromagnetic Conception of Nature at the Root of the Special and General Relativity Theories and its Revolutionary Meaning

    NASA Astrophysics Data System (ADS)

    Giannetto, Enrico R. A.

    2009-06-01

    The revolution in XX century physics, induced by relativity theories, had its roots within the electromagnetic conception of Nature. It was developed through a tradition related to Brunian and Leibnizian physics, to the German Naturphilosophie and English XIXth physics. The electromagnetic conception of Nature was in some way realized by the relativistic dynamics of Poincaré of 1905. Einstein, on the contrary, after some years, linked relativistic dynamics to a semi-mechanist conception of Nature. He developed general relativity theory on the same ground, but Hilbert formulated it starting from the electromagnetic conception of Nature. Here, a comparison between these two conceptions is proposed in order to understand the conceptual foundations of special relativity within the context of the changing world views. The whole history of physics as well as history of science can be considered as a conflict among different worldviews. Every theory, as well as every different formulation of a theory implies a different worldview: a particular image of Nature implies a particular image of God (atheism too has a particular image of God) as well as of mankind and of their relationship. Thus, it is very relevant for scientific education to point out which image of Nature belongs to a particular formulation of a theory, which image comes to dominate and for which ideological reason.

  20. Investigating the Nature of Third Grade Students' Experiences with Concept Maps to Support Learning of Science Concepts

    ERIC Educational Resources Information Center

    Merrill, Margaret L.

    2012-01-01

    To support and improve effective science teaching, educators need methods to reveal student understandings and misconceptions of science concepts and to offer all students an opportunity to reflect on their own knowledge construction and organization. Students can benefit by engaging in scientific activities in which they build personal…

  1. BOOK REVIEW: Critical Phenomena in Natural Sciences: Chaos, Fractals, Selforganization and Disorder: Concepts and Tools

    NASA Astrophysics Data System (ADS)

    Franz, S.

    2004-10-01

    Since the discovery of the renormalization group theory in statistical physics, the realm of applications of the concepts of scale invariance and criticality has pervaded several fields of natural and social sciences. This is the leitmotiv of Didier Sornette's book, who in Critical Phenomena in Natural Sciences reviews three decades of developments and applications of the concepts of criticality, scale invariance and power law behaviour from statistical physics, to earthquake prediction, ruptures, plate tectonics, modelling biological and economic systems and so on. This strongly interdisciplinary book addresses students and researchers in disciplines where concepts of criticality and scale invariance are appropriate: mainly geology from which most of the examples are taken, but also engineering, biology, medicine, economics, etc. A good preparation in quantitative science is assumed but the presentation of statistical physics principles, tools and models is self-contained, so that little background in this field is needed. The book is written in a simple informal style encouraging intuitive comprehension rather than stressing formal derivations. Together with the discussion of the main conceptual results of the discipline, great effort is devoted to providing applied scientists with the tools of data analysis and modelling necessary to analyse, understand, make predictions and simulate systems undergoing complex collective behaviour. The book starts from a purely descriptive approach, explaining basic probabilistic and geometrical tools to characterize power law behaviour and scale invariant sets. Probability theory is introduced by a detailed discussion of interpretative issues warning the reader on the use and misuse of probabilistic concepts when the emphasis is on prediction of low probability rare---and often catastrophic---events. Then, concepts that have proved useful in risk evaluation, extreme value statistics, large limit theorems for sums of independent

  2. Capturing the multiple benefits associated with nature-based solutions: lessons from natural flood management project in the Cotswolds, UK

    NASA Astrophysics Data System (ADS)

    Short, Chrisopher; Clarke, Lucy; Uttley, Chris; Smith, Brian

    2017-04-01

    Following severe flooding in 2007, and subsequent smaller flood events, a decision was taken in 2012 to explore nature-based solutions in 250km2 river catchment in the southern Cotswolds in the UK. A major tributary within the catchment has been designated as rapid response; with a primarily limestone geology limestone and a mixture of spring and surface drained sources along a number of tributaries feeding in the river, with one main population centre where the water bodies converge. The project involves landscape and land management interventions aimed at attenuating high flows to reduce flood risk through changes in land management practices in both agriculture and forestry and slowing peak flows in surface flows through increased infiltration and attenuation areas. After three years of the project it is clear that the threshold for effectiveness requires the majority of the upstream catchment area to be implementing these measures. However, the cost effectiveness of the approach seems to be substantial compared to traditional hard-engineering approaches. The level of community involvement, including local flood forums, is high and the social, and natural, capital has been enhanced through the project. Early results suggest that there have been localized improvements in water quality and biodiversity as well as a reduction in peak flow but such changes are difficult to directly associate to the project. What is clear is the role of communities, landowners and partners to implement natural flood management on a catchment wide scale. In this sense the project has adopted a co-management or adaptive management approach which brings together the knowledges of hydrologists, ecologists, farmers, woodland owners and the local community to implement locally be-spoke solutions within a broader project framework. This paper will outline the initial findings and the governance structure that has assisted in the early success of the project within a theoretical framework of

  3. Toward a new concept of "natural balance" in oral estroprogestin contraception.

    PubMed

    Chabbert-Buffet, Nathalie; Gerris, Jan; Jamin, Christian; Lello, Stefano; Lete, Inaki; Lobo, Paloma; Nappi, Rossella E; Pintiaux, Axelle

    2013-10-01

    The Pill has undergone many changes since its first appearance some 50 years ago. Key developments included the reduction of ethinylestradiol doses and the synthesis of new progestins in order to increase safety, compliance and efficiency. Low-dose combined oral contraceptives (COCs) are currently the preferred option for millions of women. Due to this widespread use, it has been argued that the safety of COCs should be even better, raising the threshold for excellence. Yet in spite of major improvements, there is still an associated risk of venous thromboembolism (VTE). The next step in COCs' evolution should take total estrogenicity and hepatic estro-androgenic balance into account. The focus on the estrogen component--which has not changed in 50 years--has yielded a new class of natural estrogen pills. Following the introduction of a first quadriphasic pill, a monophasic estradiol pill based on the concept of "natural balance" was subsequently made available. These recent achievements could represent a step forward in the evolution of COCs and pave the way for better safety.

  4. Natural convection in binary gases due to horizontal thermal and solutal gradients

    NASA Technical Reports Server (NTRS)

    Weaver, J. A.; Viskanta, R.

    1991-01-01

    The influence of augmenting and opposing thermal and solutal buoyancy forces on natural convection of binary gases due to horizontal temperature and concentration gradients is examined through comparison of smoke flow visualization and measured temperature and concentration distributions with numerical predictions. The observed flow at the cold wall was unsteady for opposing body forces. The same basic flow structure was observed, but the unsteady flow intensifies as the opposing solutal buoyancy force increases as compared to the thermal buoyancy force. Comparison of predicted and measured temperatures and concentrations is fair overall, but the steady-state analytical model fails to predict the unsteady flow and heat and mass transport for opposing body forces.

  5. Natural conception in HIV-serodiscordant couples with the infected partner in suppressive antiretroviral therapy: A prospective cohort study.

    PubMed

    Del Romero, Jorge; Baza, María Begoña; Río, Isabel; Jerónimo, Adrián; Vera, Mar; Hernando, Victoria; Rodríguez, Carmen; Castilla, Jesús

    2016-07-01

    The potential of antiretroviral treatment (ART) to prevent the sexual transmission of HIV has increased the number of serodiscordant couples who are considering natural conception. We aim to describe the results of a protocol for reproductive counseling aimed at HIV serodiscordant couples who desire natural conception, in which the infected partner, the index case, is receiving suppressive antiretroviral treatment.A prospective cohort included all HIV serodiscordant couples attended a counseling program in the period 2002 to 2013 who opted for natural conception and met the following criteria: index case on ART with persistent plasma viral suppression for at least the previous 6 months, ART compliance over 95%, preserved immune status, undetectable HIV viral and proviral load in semen in male index cases, and absence of genitourinary infections and fertility problems in both members of the couple.Of the 161 HIV serodiscordant couples included, 133 with male index cases, 66% achieved at least 1 pregnancy, 18% a second one, and 5% a third pregnancy. A total of 144 natural pregnancies occurred and 107 babies were born. The pregnancy rate was 1.9 for each 100 acts of vaginal intercourse, and the mean time to conception was 6.1 months, both independently of the sex of the index case. No case of sexual or vertical HIV transmission occurred.In the absence of fertility problems and under controlled conditions, natural conception might be a safe and effective reproductive method for those HIV serodiscordant couples who choose this reproductive option.

  6. Transport of reacting solutes in porous media: Relation between mathematical nature of problem formulation and chemical nature of reactions

    USGS Publications Warehouse

    Rubin, Jacob

    1983-01-01

    Examples involving six broad reaction classes show that the nature of transport-affecting chemistry may have a profound effect on the mathematical character of solute transport problem formulation. Substantive mathematical diversity among such formulations is brought about principally by reaction properties that determine whether (1) the reaction can be regarded as being controlled by local chemical equilibria or whether it must be considered as being controlled by kinetics, (2) the reaction is homogeneous or heterogeneous, (3) the reaction is a surface reaction (adsorption, ion exchange) or one of the reactions of classical chemistry (e.g., precipitation, dissolution, oxidation, reduction, complex formation). These properties, as well as the choice of means to describe them, stipulate, for instance, (1) the type of chemical entities for which a formulation's basic, mass-balance equations should be written; (2) the nature of mathematical transformations needed to change the problem's basic equations into operational ones. These and other influences determine such mathematical features of problem formulations as the nature of the operational transport-equation system (e.g., whether it involves algebraic, partial-differential, or integro-partial-differential simultaneous equations), the type of nonlinearities of such a system, and the character of the boundaries (e.g., whether they are stationary or moving). Exploration of the reasons for the dependence of transport mathematics on transport chemistry suggests that many results of this dependence stem from the basic properties of the reactions' chemical-relation (i.e., equilibrium or rate) equations.

  7. Effect of sonication process on natural zeolite at ferric chloride hexahydrate solution

    NASA Astrophysics Data System (ADS)

    Prasetyo, T. A. B.; Soegijono, B.

    2017-04-01

    Natural zeolite in FeCl3.6H2O solution which was exposed with high intensity ultrasonic for 40 min, 80 min and 120 min has been studied. X-Ray Diffraction (XRD) pattern revealed changed pattern and new peaks due to sonication process. Sonication contributed into element composition changes and it had been found also during quantitative chemical microanalysis analysis (EDX) and indicates an increment of 320.81 % (ZAM2) Fe element. Noninvasive back scatter (NIBS) analysis of various ultrasonic times affected to the particle size distribution, surface area and pore analysis. By using density functional theory (DFT), we revealed some improvements such as 44.03% surface area and 67.25% pore radius. We believe that controllable ultrasonic processing in the ferric chloride hexahydrate solution will produce uniform natural zeolite physical and chemical properties as a candidate of adsorbent materials.

  8. Microbially-enhanced redox solution reoxidation for sweetening sour natural gas

    SciTech Connect

    Rai, C.

    1995-06-01

    About twenty five percent of natural gas produced in the United States is sour containing significant volumes of hydrogen sulfide and other contaminants. Liquid redox processes remove hydrogen sulfide from natural gas. Aqueous solution of chelated ferric ions oxidize the hydrogen sulfide to elemental sulfur. The reduced iron chelate is then oxidized by contact with air and recycled. This requires expensive equipment for regeneration, costly chemicals and the process is usually energy intensive. Recent studies show that the ferric ion regeneration rates are substantially enhanced in presence of acidophilic bacteria. The specific objectives of this project are to advance the technology and improve the economics of the commercial iron-based chelate processes utilizing biologically-enhanced reoxidation of the redox solutions used in these processes, such as LO-CAT II and SulFerox.

  9. Natural micro-scale heterogeneity induced solute and nanoparticle retardation in fractured crystalline rock.

    PubMed

    Huber, F; Enzmann, F; Wenka, A; Bouby, M; Dentz, M; Schäfer, T

    2012-05-15

    We studied tracer (Tritiated Water (HTO); Tritium replaces one of the stable hydrogen atoms in the H(2)O molecule) and nanoparticle (quantum dots (QD)) transport by means of column migration experiments and comparison to 3D CFD modeling. Concerning the modeling approach, a natural single fracture was scanned using micro computed tomography (μCT) serving as direct input for the model generation. The 3D simulation does not incorporate any chemical processes besides the molecular diffusion coefficient solely reflecting the impact of fracture heterogeneity on mass (solute and nanoparticles) transport. Complex fluid velocity distributions (flow channeling and flowpath heterogeneity) evolve as direct function of fracture geometry. Both experimental and simulated solute and colloidal breakthrough curves show heavy tailing (non-Fickian transport behavior), respectively. Regarding the type of quantum dots and geochemical conditions prevailing (Grimsel ground water chemistry, QD and diorite surface charge, respectively and porosity of the Äspö diorite drill core) experimental breakthrough of the quantum dots always arrives faster than the solute tracer in line with the modeling results. Besides retardation processes like sorption, filtration, straining or matrix diffusion, the results show that natural 3D fracture heterogeneity represents an important additional retardation mechanism for solutes and colloidal phases. This is clearly verified by the numerical simulations, where the 3D real natural fracture geometry and the resulting complex flow velocity distribution is the only possible process causing solute/nanoparticle retardation. Differences between the experimental results and the simulations are discussed with respect to uncertainties in the μCT measurements and experimental and simulation boundary conditions, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Removal Of Copper From Aqueous Solutions By Using Natural And Fe-Modified Clinoptilolite

    NASA Astrophysics Data System (ADS)

    Lipovský, Marek; Sirotiak, Maroš; Soldán, Maroš

    2015-06-01

    Removal of copper from aqueous solution on the natural and modified clinoptilolite was studied under static conditions. Batch adsorptions of copper were performed to investigate the effects of contact time and initial metal ion concentration. The Freundlich and Langmuir adsorption isotherms were used to analyse the experimental data. The kinetic analyses of the adsorption processes were performed using the pseudo-first-order and pseudo-second-order kinetic models.

  11. Upscaling solute transport in naturally fractured porous media with the continuous time random walk method

    SciTech Connect

    Geiger, S.; Cortis, A.; Birkholzer, J.T.

    2010-04-01

    Solute transport in fractured porous media is typically 'non-Fickian'; that is, it is characterized by early breakthrough and long tailing and by nonlinear growth of the Green function-centered second moment. This behavior is due to the effects of (1) multirate diffusion occurring between the highly permeable fracture network and the low-permeability rock matrix, (2) a wide range of advection rates in the fractures and, possibly, the matrix as well, and (3) a range of path lengths. As a consequence, prediction of solute transport processes at the macroscale represents a formidable challenge. Classical dual-porosity (or mobile-immobile) approaches in conjunction with an advection-dispersion equation and macroscopic dispersivity commonly fail to predict breakthrough of fractured porous media accurately. It was recently demonstrated that the continuous time random walk (CTRW) method can be used as a generalized upscaling approach. Here we extend this work and use results from high-resolution finite element-finite volume-based simulations of solute transport in an outcrop analogue of a naturally fractured reservoir to calibrate the CTRW method by extracting a distribution of retention times. This procedure allows us to predict breakthrough at other model locations accurately and to gain significant insight into the nature of the fracture-matrix interaction in naturally fractured porous reservoirs with geologically realistic fracture geometries.

  12. Upscaling solute transport in naturally fractured porous media with the continuous time random walk method

    NASA Astrophysics Data System (ADS)

    Geiger, S.; Cortis, A.; Birkholzer, J. T.

    2010-12-01

    Solute transport in fractured porous media is typically "non-Fickian"; that is, it is characterized by early breakthrough and long tailing and by nonlinear growth of the Green function-centered second moment. This behavior is due to the effects of (1) multirate diffusion occurring between the highly permeable fracture network and the low-permeability rock matrix, (2) a wide range of advection rates in the fractures and, possibly, the matrix as well, and (3) a range of path lengths. As a consequence, prediction of solute transport processes at the macroscale represents a formidable challenge. Classical dual-porosity (or mobile-immobile) approaches in conjunction with an advection-dispersion equation and macroscopic dispersivity commonly fail to predict breakthrough of fractured porous media accurately. It was recently demonstrated that the continuous time random walk (CTRW) method can be used as a generalized upscaling approach. Here we extend this work and use results from high-resolution finite element-finite volume-based simulations of solute transport in an outcrop analogue of a naturally fractured reservoir to calibrate the CTRW method by extracting a distribution of retention times. This procedure allows us to predict breakthrough at other model locations accurately and to gain significant insight into the nature of the fracture-matrix interaction in naturally fractured porous reservoirs with geologically realistic fracture geometries.

  13. Trapping the lead ion in multi-components aqueous solution by natural clinoptilolite.

    PubMed

    Tao, Yu Fei; Qiu, Yue; Fang, Shu Yu; Liu, Zhu Yun; Wang, Ying; Zhu, Jian Hua

    2010-08-15

    To study whether natural clinoptilolite could selectively capture Pb(2+) ion in the aqueous solution containing salt and glycine as well as nitrosamines, the natural zeolite was utilized in the complex solution with pH value of 1.2 in comparison with other porous materials such as zeolite NaZSM-5 and activated carbon. Clinoptilolite exhibited the highest capability in adsorbing Pb(2+) ion in the solution at 37 degrees C, achieving the capacity of 7 mg/g, two times more than that by other zeolites and six times over that by activated carbon, and the adsorption equilibrium could be achieved within 2h. The impacts of solid-liquid ratio, initial concentration of Pb(2+) and the competition of other metal ions or volatile nitrosamines on the adsorption were examined, and the change in Gibbs energy for the ion-exchanged of Pb(2+) ion by clinoptilolite was discussed, through which the ion-exchange process was proven to be spontaneous. Moreover, both the selectivity of clinoptilolite toward Pb(2+) ion in complex solution and the venial toxicity of clinoptilolite on the viability of RAW264.7 cells were investigated in this article.

  14. The separation of uranium ions by natural and modified diatomite from aqueous solution.

    PubMed

    Sprynskyy, Myroslav; Kovalchuk, Iryna; Buszewski, Bogusław

    2010-09-15

    In this work the natural and the surfactant modified diatomite has been tested for ability to remove uranium ions from aqueous solutions. Such controlling factors of the adsorption process as initial uranium concentration, pH, contact time and ionic strength have been investigated. Effect of ionic strength of solution has been examined using the solutions of NaCl, Na(2)CO(3) and K(2)SO(4). The pseudo-first order and the pseudo-second order models have been used to analyze the adsorption kinetic results, whereas the Langmuir and the Freundlich isotherms have been used to the equilibrium adsorption data. The effects of the adsorbent modification as well as uranium adsorption on the diatomite surface have been studied using X-ray powder diffraction, scanning electron microscopy and FTIR spectroscopy. The maximum adsorption capacities of the natural and the modified diatomite towards uranium were 25.63 micromol/g and 667.40 micromol/g, respectively. The desorptive solutions of HCl, NaOH, Na(2)CO(3), K(2)SO(4), CaCO(3), humic acid, cool and hot water have been tested to recover uranium from the adsorbent. The highest values of uranium desorption (86%) have been reached using 0.1M HCl. Copyright 2010 Elsevier B.V. All rights reserved.

  15. Trends in rates of natural conceptions among Danish women born during 1960-1984.

    PubMed

    Lassen, Tina Harmer; Sobotka, Tomás; Jensen, Tina Kold; Jacobsen, Rune; Erb, Karin; Skakkebæk, Niels E

    2012-09-01

    The aim of the study was to analyse trends in the rate of natural conceptions (RNC) among birth cohorts of women born during the period 1960-1984. In this nationwide study of Danish-born female cohorts born during the period 1960-1984, we found a gradual decline in the RNC with successive birth cohorts. Our results confirm the findings from a previous study on trends in RNC among native Danish women. This is a register-based cohort study. Our data set included 803 435 native Danish women born in 1960-1984, of whom 68.2% had conceived at least one child as of 1 January 2008, by which time the follow-up was terminated. Data from Danish national registers were linked at the individual level using unique personal numbers assigned at birth to each resident. We analysed the data for the cohorts of native Danish women born in 1960-1984 and resident in Denmark in 2008. For these cohorts, we estimated the RNC per woman, defined as the mean number of live births minus live births after assisted reproductive technology (ART) plus the mean number of induced abortions. Births, abortions and births after ART were partly projected for the younger cohorts who had not finished their reproductive years before 2008. In addition, we looked at trends in hormonal contraception use. In the main projection scenario, the RNC gradually declined with successive cohorts from 2.39 among women born in 1960 to 2.15 among women born in 1984, with stable values of 2.15-2.16 projected in the youngest cohorts analysed, 1979-1984. The projected decline was a consequence of a decrease in induced abortion rates and an increase in the use of ART among the younger cohorts. Furthermore, we projected a cohort increase in the share of women without natural conceptions. A considerable portion of the results was based on projections, which involve uncertainty, especially concerning the results for women born in 1980 and later. In addition, information on IUI could not be included, which led to underestimation

  16. Sperm DNA fragmentation and mitochondrial membrane potential combined are better for predicting natural conception than standard sperm parameters.

    PubMed

    Malić Vončina, Slađana; Golob, Barbara; Ihan, Alojz; Kopitar, Andreja Nataša; Kolbezen, Mojca; Zorn, Branko

    2016-03-01

    To evaluate whether DNA fragmentation and/or mitochondrial membrane potential (MMP) predict natural conception better than standard sperm parameters. Prospective cross-sectional study. University medical center. Eighty-five infertile and 51 fertile men. Assessment of sperm DNA fragmentation, MMP, and standard semen parameters over a 6- to 12-month observation period. Comparison between the results of DNA fragmentation, MMP, and standard sperm parameters alone or combined and achievement of natural conception. Twenty-six of the 85 (31%) men from infertile couples conceived naturally. The median values of DNA fragmentation and MMP in the men who conceived within the observation period were similar to those in the fertile controls. Optimal threshold values of DNA fragmentation and MMP were 25% as determined by receiver operating characteristic analysis (area under the curve [AUC], 0.70; 95% confidence interval (CI) 0.58-0.82) and 62.5% (AUC, 0.68, 95% CI 0.56-0.80), respectively. The men in the infertile group with values of DNA fragmentation ≤25% and with MMP values ≥62.5% had significantly higher odds for conception (odds ratio [OR], 5.22; 95% CI 1.82-14.93] and OR, 4.67; 95% CI 1.74-12.5, respectively). Normal semen analysis alone had no predictive value for natural conception (OR, 1.84; 95% CI 0.67-5.07]). Both sperm function tests combined had significant odds for natural conception (OR, 8.24; 95% CI 2.91-23.33]), with a probability of 0.607 (60.7%) for both normal values and 0.158 (15.8%) for abnormal values. Sperm DNA fragmentation and MMP combined may be superior to standard semen parameters for the prediction of natural conception. Copyright © 2016. Published by Elsevier Inc.

  17. Nature of Science and Science Content Learning: The Relation between Students' Nature of Science Understanding and Their Learning about the Concept of Energy

    ERIC Educational Resources Information Center

    Michel, Hanno; Neumann, Irene

    2016-01-01

    Besides viewing knowledge about the nature of science (NOS) as important for its own value with respect to scientific literacy, an adequate understanding of NOS is expected to improve science content learning by fostering the ability to interrelate scientific concepts and, thus, coherently acquire scientific content knowledge. However, there is a…

  18. Structuring Process Skills and the Solution of Verbal Problems Involving Science Concepts.

    ERIC Educational Resources Information Center

    Champagne, Audrey B.; Klopfer, Leopold E.

    1981-01-01

    Investigates the interaction between semantic knowledge and process skills in eighth-grade students' (N=27) performance in solving two types of problems (analogies and set-membership) of inducing structure drawn from physical geology concepts. (DS)

  19. Children's Conceptions of Air Pressure: Exploring the Nature of Conceptual Change.

    ERIC Educational Resources Information Center

    Tytler, Russell

    1998-01-01

    Constructs case studies of individuals to explore the way conceptions change over time, and the difficulties presented by the concept of atmospheric pressure. Evaluates different structural theories of conceptual change. Contains 62 references. (DDR)

  20. Children's Conceptions of Air Pressure: Exploring the Nature of Conceptual Change.

    ERIC Educational Resources Information Center

    Tytler, Russell

    1998-01-01

    Constructs case studies of individuals to explore the way conceptions change over time, and the difficulties presented by the concept of atmospheric pressure. Evaluates different structural theories of conceptual change. Contains 62 references. (DDR)

  1. Drops of water and of soap solution: Students' constraining mental models of the nature of matter

    NASA Astrophysics Data System (ADS)

    Eilam, Billie

    2004-12-01

    This study investigates how 25 junior high school students employed their bodies of knowledge and responded to problem cues while individually performing a science experiment and reasoning about a drops phenomenon. Line-by-line content analysis conducted on students' written ad hoc explanations aimed to reveal students' concepts and their relations within their explanations, and to construe students' mental models for the science phenomenon based on level of specification, models' correspondence with scientific claims, macro versus micro view of matter, and type of evidence used. We then inferred four types of knowledge representations for the nature of matter. Findings are discussed in terms of implications for science teaching.

  2. A conceptual change analysis of nature of science conceptions: The deep roots and entangled vines of a conceptual ecology

    NASA Astrophysics Data System (ADS)

    Johnston, Adam Thomas

    This research used theories of conceptual change to analyze learners' understandings of the nature of science (NOS). Ideas regarding the NOS have been advocated as vital aspects of science literacy, yet learners at many levels (students and teachers) have difficulty in understanding these aspects in the way that science literacy reforms advocate. Although previous research has shown the inadequacies in learners' NOS understandings and have documented ways by which to improve some of these understandings, little has been done to show how these ideas develop and why learners' preexisting conceptions of NOS are so resistant to conceptual change. The premise of this study, then, was to describe the nature of NOS conceptions and of the conceptual change process itself by deeply analyzing the conceptions of individual learners. Toward this end, 4 individuals enrolled in a physical science course designed for preservice elementary teachers were selected to participate in a qualitative research study. These individuals answered questionnaires, surveys, direct interview questions, and a variety of interview probes (e.g., critical incidents, responses to readings/videos, reflections on coursework, card sorting tasks, etc.) which were administered throughout the duration of a semester. By utilizing these in-depth, qualitative probes, learners' conceptions were not only assessed but also described in great detail, revealing the source of their conceptions as well as identifying many instances in which a learner's directly stated conception was contradictory to that which was reflected by more indirect probes. As a result of this research, implications regarding NOS conceptions and their development have been described. In addition, various descriptions of conceptual change have been further refined and informed. Especially notable, the influence of a learner's conceptual ecology and its extrarational influences on conceptual change have been highlighted. It is argued that

  3. Detecting Underspecification in SNOMED CT Concept Definitions Through Natural Language Processing

    PubMed Central

    Pacheco, Edson; Stenzhorn, Holger; Nohama, Percy; Paetzold, Jan; Schulz, Stefan

    2009-01-01

    Quality assurance and audit issues play a major role in maintening large biomedical terminology, such as SNOMED CT. Several automatized techniques have been proposed to facilitate the identification of weak spots and suggest adequate improvements. In this study, we address a well-known issue within SNOMED CT: Albeit the wording of many free-text concept descriptions suggests a connection to other concepts, they are often not referred to in the logical concept definition. To detect such inconsistencies, we use a semantic indexing approach which maps free text onto a sequence of semantic identifiers. Applied to SNOMED CT concepts without attributes, our technique spots refinable concepts and suggests appropriate attributes, i.e., connections to other concepts. Based on a manual analysis of random samples, we estimate that approximately 18,000 refinable concepts can be found. PMID:20351905

  4. Is the calorie concept a real solution to the obesity epidemic?

    PubMed Central

    Camacho, Salvador; Ruppel, Andreas

    2017-01-01

    ABSTRACT Background: The obesity epidemic has been growing steadily across the whole world, and so far not a single country has been able to reverse it. The cause of obesity is stated by the World Health Organization as an energy imbalance between calories consumed and calories expended. However, growing evidence suggests that the calorie imbalance concept may not be sufficient to manage and reverse the obesity epidemic. Objective: To discuss the use of the calorie imbalance concept and its elements as a tool for weight management as well as its possible negative consequences and implications for public health, with the aim to point toward the need of an updated concept for causes of obesity. This update should guide public health interventions more efficiently to limit obesity by preventing weight gain or promoting weight loss. Methods: This is a literature reviews based on a semi-structured approach to determine the material to be examined. Results: After revisiting general facts about fat generation and accumulation, we propose an updated concept for the causes of obesity including diet composition and hormonal regulation of fat metabolism. Conclusions: We discuss how this updated concept could benefit the overall efficiency of strategies against obesity, and hypothesize how potential resistance to adopting this new view could be lowered. PMID:28485680

  5. Urban e-Mobility - Challenges and potential solutions using the example of the "E3W" concept vehicle

    NASA Astrophysics Data System (ADS)

    Perterer, M.; Martin, P.; Lochner, H.

    2014-05-01

    Due to the increasing number of people in urban areas, there is a need for affordable individual transportation. Limited space in cities together with the need for a significant reduction of pollution will lead to new mobility concepts in the near future. The aim of these concepts is not replacing the car itself, but to supply an additional personal transportation solution with local zero emission. Therefore, electrical powered vehicle concepts may be used. Due to the limited energy density and high cost of current Li-ion batteries, a significant weight reduction of the vehicle could lead to acceptable range and cost. In order to develop an affordable urban concept, the requirements for this kind of vehicle also have to be adjusted in comparison to conventional cars. This concept, the so called "E3W", combines the advantages of a two-wheeler with those of a four-wheeler, resulting in a lightweight and compact vehicle. This concept accommodates space for two persons with luggage and guarantees a high level of safety including wind and weather protection. The overall measures of this vehicle are smaller than current compact cars and allow therefore better use in cities. In order to fulfill technical and commercial requirements, a load carrying, short fiber reinforced thermoplastic body structure is chosen, combining good weight specific mechanical properties and low production costs. This highly integrated body structure also provides the body cover all in one. Pultruded glass fiber reinforced plastic (GFRP) beams are used as the backbone for the vehicle by carrying the main loads, the front crash structure and the rear swingarm. Finally, two prototypes are built to investigate the driving behavior, proof the concept and the suitability for daily use.

  6. Weak solution concept and Galerkin's matrix for the exterior of an oblate ellipsoid of revolution in the representation of the Earth's gravity potential by buried masses

    NASA Astrophysics Data System (ADS)

    Holota, Petr; Nesvadba, Otakar

    2017-04-01

    The paper is motivated by the role of boundary value problems in Earth's gravity field studies. The discussion focuses on Neumann's problem formulated for the exterior of an oblate ellipsoid of revolution as this is considered a basis for an iteration solution of the linear gravimetric boundary value problem in the determination of the disturbing potential. The approach follows the concept of the weak solution and Galerkin's approximations are applied. This means that the solution of the problem is approximated by linear combinations of basis functions with scalar coefficients. The construction of Galerkin's matrix for basis functions generated by elementary potentials (point masses) is discussed. Ellipsoidal harmonics are used as a natural tool and the elementary potentials are expressed by means of series of ellipsoidal harmonics. The problem, however, is the summation of the series that represent the entries of Galerkin's matrix. It is difficult to reduce the number of summation indices since in the ellipsoidal case there is no analogue to the addition theorem known for spherical harmonics. Therefore, the straightforward application of series of ellipsoidal harmonics is complemented by deeper relations contained in the theory of ordinary differential equations of second order and in the theory of Legendre's functions. Subsequently, also hypergeometric functions and series are used. Moreover, within some approximations the entries are split into parts. Some of the resulting series may be summed relatively easily, apart from technical tricks. For the remaining series the summation was converted to elliptic integrals. The approach made it possible to deduce a closed (though approximate) form representation of the entries in Galerkin's matrix. The result rests on concepts and methods of mathematical analysis. In the paper it is confronted with a direct numerical approach applied for the implementation of Legendre's functions. The computation of the entries is more

  7. Natural Hazard Problem and Solution Definition in the News Media: the Case of Tropical Storm Allison

    NASA Astrophysics Data System (ADS)

    Lindquist, Eric; Mosher-Howe, Katrina

    2010-05-01

    Focusing events such as natural or technological disasters can have significant impacts on public policy and planning in both the near and long term. These impacts can manifest at different temporal scales ranging from the period of immediate attention and disaster relief through the period of recovery and reconstruction and beyond. These impacts and associated decisions can be studied in retrospect and understood as not only short-term reactions, but as long-term components of subsequent natural hazard planning and public policy. By studying in detail how an event was defined, and the policy and planning alternatives that were raised or recommended in response to a disaster event, we can better understand the role that disaster-related focusing events play in the long-term evolution of a community's public policy, infrastructural planning efforts, and responses to natural disasters. This paper will use a focusing event framework to explore the local and regional policy impacts over time of a major urban flood in Houston, Texas, Tropical Storm Allison. Tropical Storm Allison (TSA), dropped 36 inches of rain on Houston over a period of four days in early June 2001, and was responsible for 22 deaths, 70,000 flood damaged homes, and 5 billion in damage to the region. The primary data source for this effort is a database of 500 articles from the major regional newspaper, the Houston Chronicle, over the period of 2001 through 2008. These articles were coded for multiple variables, including, cause, effect and impact (financial and social), blame, problem and solution definition and solution acceptance). This paper focuses primarily on the measures of problem definition (how was TSA, as an event, defined in the media, for example, as an act of God, or as a result of poor planning or decision making, etc), and on solution definition (what solutions were proposed to mitigate or adapt to future storms of this magnitude, how were they linked to the definition of the problem

  8. CONCEPT LEARNING AND CONCEPT TEACHING.

    ERIC Educational Resources Information Center

    GLASER, ROBERT

    REVIEWED ARE THE PSYCHOLOGICAL STUDIES OF CONCEPT LEARNING AS THEY RELATE TO CONCEPT TEACHING. AN ANALYSIS IS MADE OF THE NATURE OF CONCEPT LEARNING AS IT IS STUDIED IN THE PSYCHOLOGIST'S LABORATORY, INCLUDING THE NATURE OF CONCEPT TASKS AS THEY APPEAR IN SUBJECT MATTER LEARNING. THE PRIMARY KINDS OF CONCEPT LEARNING SITUATIONS, INCLUDING THE…

  9. A simple protocol for the visual discrimination of natural cyclodextrins in aqueous solution using perichromic probes

    NASA Astrophysics Data System (ADS)

    Nandi, Leandro G.; Nicoleti, Celso R.; Stock, Rafaela I.; Barboza, Tainá A.; Andreaus, Jürgen; Machado, Vanderlei G.

    2015-02-01

    Three synthesized compounds, 4-(4-nitrostyryl)phenol, 2,6-dibromo-4-(2,4-dinitrobenzylideneamino)phenol and 2,6-dichloro-4-(2,4-dinitrobenzylideneamino)phenol, were deprotonated to generate the perichromic dyes 2b, 3b and 4b, respectively. These dyes were used as probes to investigate the micropolarity of natural cyclodextrins (CyDs) and it was observed that they interact differently with the CyDs according to the molecular structure of the dye and the diameter of the CyD. The solvatochromic bands of the dyes that interacted with the CyDs were bathochromically shifted, suggesting that the probes were transferred to the hydrophobic interior of the CyD in aqueous solution. Dyes 2b and 4b were found to be very selective for α-CyD and γ-CyD, respectively, while β- and γ-CyD changed the color of the solution of compound 3b. These dyes were then successfully used in a simple assay that allows the naked-eye discrimination of natural CyDs in aqueous solution, without the need for expensive techniques.

  10. Adsorption characteristics of Pb(II) from aqueous solutions onto a natural biosorbent, fallen arborvitae leaves.

    PubMed

    Shi, Jie; Zhao, Zhiwei; Liang, Zhijie; Sun, Tianyi

    2016-01-01

    In this study, the potential of the oriental arborvitae leaves for the adsorption of Pb(II) from aqueous solutions was evaluated. Brunauer-Emmett-Teller analysis showed that the surface area of arborvitae leaves was 29.52 m(2)/g with pore diameter ranging from 2 to 50 nm. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy showed C-C or C-H, C-O, and O-C=O were the main groups on the arborvitae leaves, which were the main sites for surface complexation. Finally, effects of adsorbent dose, initial pH, contact time, and coexisting natural organic matters (humic acid (HA)) on the adsorption of Pb(II) were investigated. The results indicated that the pHZPC (adsorbents with zero point charge at this pH) was 5.3 and the adsorption reached equilibrium in 120 min. Isotherm simulations revealed that the natural arborvitae leaves exhibit effective adsorption for Pb(II) in aqueous solution, giving adsorptive affinity and capacity in an order of 'no HA' > 5 mg/L HA > 10 mg/L HA, and according to the Langmuir models, the maximum adsorptions of Pb(II) were 43.67 mg/g, 38.61 mg/g and 35.97 mg/g, respectively. The results demonstrated that the oriental arborvitae leaves showed high potentials for the adsorption of Pb(II) from aqueous solutions.

  11. A simple protocol for the visual discrimination of natural cyclodextrins in aqueous solution using perichromic probes.

    PubMed

    Nandi, Leandro G; Nicoleti, Celso R; Stock, Rafaela I; Barboza, Tainá A; Andreaus, Jürgen; Machado, Vanderlei G

    2015-02-05

    Three synthesized compounds, 4-(4-nitrostyryl)phenol, 2,6-dibromo-4-(2,4-dinitrobenzylideneamino)phenol and 2,6-dichloro-4-(2,4-dinitrobenzylideneamino)phenol, were deprotonated to generate the perichromic dyes 2b, 3b and 4b, respectively. These dyes were used as probes to investigate the micropolarity of natural cyclodextrins (CyDs) and it was observed that they interact differently with the CyDs according to the molecular structure of the dye and the diameter of the CyD. The solvatochromic bands of the dyes that interacted with the CyDs were bathochromically shifted, suggesting that the probes were transferred to the hydrophobic interior of the CyD in aqueous solution. Dyes 2b and 4b were found to be very selective for α-CyD and γ-CyD, respectively, while β- and γ-CyD changed the color of the solution of compound 3b. These dyes were then successfully used in a simple assay that allows the naked-eye discrimination of natural CyDs in aqueous solution, without the need for expensive techniques. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. The effectiveness of conceptual change texts and concept clipboards in learning the nature of science

    NASA Astrophysics Data System (ADS)

    Çil, Emine; Çepni, Salih

    2016-01-01

    Background: One of the most important goals of science education is to enable students to understand the nature of science (NOS). However, generally regular science teaching in classrooms does not help students improve informed NOS views. Purpose: This study investigated the influence of an explicit reflective conceptual change approach compared with an explicit reflective inquiry-oriented approach on seventh graders' understanding of NOS. Sample: The research was conducted with seventh grade students. A total of 44 students participated in the study. Design and method: The study was an interpretive study because this study focused on the meanings that students attach to target aspects of NOS. Participants were divided into two groups, each consisting of 22 students. One of the groups learned NOS with an explicit reflective conceptual change approach. The requirements of conceptual change were provided through the use of conceptual change texts and concept cartoons. The other group learned NOS with an explicit reflective inquiry-oriented approach. The data were collected through open-ended questionnaires and semi-structured interviews. These instruments were employed in a pre-test, a post-test and a delayed test. Students' views of the aspects of NOS were categorized as naive, transitional and informed. Results: The result of this study indicated that before receiving instruction, most of the participants had transitional views of the tentative, empirical and imaginative and creative aspects of the NOS, and they had naive understandings of the distinction between observation and inference. The instruction in the experimental group led to a 60% - a 25% increase in the number of students who possessed an informed understanding of the tentative, empirical, creative and observation and inference aspect of the NOS. The instruction in the control group led to a 30% - a 15% increase in the informed NOS views. Conclusion: The explicit reflective conceptual change approach

  13. Designing an Illustrated Food Web to Teach Ecological Concepts: Challenges and Solutions.

    ERIC Educational Resources Information Center

    Godkin, Celia M.

    1999-01-01

    Argues that food webs are an efficient method through which to communicate the core idea of ecology--that all living things are interconnected. Assesses the challenges and solutions to using illustrated food webs. (Author/CCM)

  14. Designing an Illustrated Food Web to Teach Ecological Concepts: Challenges and Solutions.

    ERIC Educational Resources Information Center

    Godkin, Celia M.

    1999-01-01

    Argues that food webs are an efficient method through which to communicate the core idea of ecology--that all living things are interconnected. Assesses the challenges and solutions to using illustrated food webs. (Author/CCM)

  15. Comprehending the multiple 'values' of green infrastructure - Valuing nature-based solutions for urban water management from multiple perspectives.

    PubMed

    Wild, T C; Henneberry, J; Gill, L

    2017-10-01

    The valuation of urban water management practices and associated nature-based solutions (NBS) is highly contested, and is becoming increasingly important to cities seeking to increase their resilience to climate change whilst at the same time facing budgetary pressures. Different conceptions of 'values' exist, each being accompanied by a set of potential measures ranging from calculative practices (closely linked to established market valuation techniques) - through to holistic assessments that seek to address wider concerns of sustainability. Each has the potential to offer important insights that often go well beyond questions of balancing the costs and benefits of the schemes concerned. However, the need to address - and go beyond - economic considerations presents policy-makers, practitioners and researchers with difficult methodological, ethical and practical challenges, especially when considered without the benefit of a broader theoretical framework or in the absence of well-established tools (as might apply within more traditional infrastructural planning contexts, such as the analysis of transport interventions). Drawing on empirical studies undertaken in Sheffield over a period of 10 years, and delivered in partnership with several other European cities and regions, we compare and examine different attempts to evaluate the benefits of urban greening options and future development scenarios. Comparing these different approaches to the valuation of nature-based solutions alongside other, more conventional forms of infrastructure - and indeed integrating both 'green and grey' interventions within a broader framework of infrastructures - throws up some surprising results and conclusions, as well as providing important sign-posts for future research in this rapidly emerging field. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Changing High School Students' Conceptions of the Nature of Science: The Partnership for Research and Education in Plants (PREP)

    ERIC Educational Resources Information Center

    Brooks, Eric Dwayne

    2011-01-01

    This study investigated whether participation in the Partnership for Research and Education in Plants (PREP), a long-term authentic plant research project, in conjunction with explicit verses implicit instruction can change high school students' conceptions of the nature of science (NOS). The participants included a total of 134 students comprised…

  17. Realist Ontology and Natural Processes: A Semantic Tool to Analyze the Presentation of the Osmosis Concept in Science Texts

    ERIC Educational Resources Information Center

    Spinelli Barria, Michele; Morales, Cecilia; Merino, Cristian; Quiroz, Waldo

    2016-01-01

    In this work, we developed an ontological tool, based on the scientific realism of Mario Bunge, for the analysis of the presentation of natural processes in science textbooks. This tool was applied to analyze the presentation of the concept of osmosis in 16 chemistry and biology books at different educational levels. The results showed that more…

  18. A Logico-Structural, Worldview Analysis of the Interrelationship between Science Interest, Gender, and Concept of Nature.

    ERIC Educational Resources Information Center

    Cobern, William W.; And Others

    The purpose of this research was to provide information about gender-related worldview structures, among college students, that can inform the instructional decision making process. Information was generated in a logico-structural investigation of the interrelationship of gender, interest in science, and concept of nature. The strength of the…

  19. Outcomes of Nature of Science Instruction along a Context Continuum: Preservice Secondary Science Teachers' Conceptions and Instructional Intentions

    ERIC Educational Resources Information Center

    Bell, Randy L.; Mulvey, Bridget K.; Maeng, Jennifer L.

    2016-01-01

    This investigation examined outcomes associated with nature of science (NOS) instruction along a science-content context continuum on the development of secondary preservice science teachers' conceptions of and plans to teach NOS, moving beyond the common dichotomy of contextualized versus noncontextualized instruction. Participants comprised six…

  20. An Examination of the Documentary Film "Einstein and Eddington" in Terms of Nature of Science Themes, Philosophical Movements, and Concepts

    ERIC Educational Resources Information Center

    Kapucu, Munise Seçkin

    2016-01-01

    This study aims to examine nature of science themes, philosophical movements, and overall concepts covered in the documentary film, "Einstein and Eddington". A qualitative research method was used. In this study, the documentary film "Einstein and Eddington," the viewing time of which is 1 hour and 28 minutes, was used as the…

  1. Changing High School Students' Conceptions of the Nature of Science: The Partnership for Research and Education in Plants (PREP)

    ERIC Educational Resources Information Center

    Brooks, Eric Dwayne

    2011-01-01

    This study investigated whether participation in the Partnership for Research and Education in Plants (PREP), a long-term authentic plant research project, in conjunction with explicit verses implicit instruction can change high school students' conceptions of the nature of science (NOS). The participants included a total of 134 students comprised…

  2. Outcomes of Nature of Science Instruction along a Context Continuum: Preservice Secondary Science Teachers' Conceptions and Instructional Intentions

    ERIC Educational Resources Information Center

    Bell, Randy L.; Mulvey, Bridget K.; Maeng, Jennifer L.

    2016-01-01

    This investigation examined outcomes associated with nature of science (NOS) instruction along a science-content context continuum on the development of secondary preservice science teachers' conceptions of and plans to teach NOS, moving beyond the common dichotomy of contextualized versus noncontextualized instruction. Participants comprised six…

  3. Realist Ontology and Natural Processes: A Semantic Tool to Analyze the Presentation of the Osmosis Concept in Science Texts

    ERIC Educational Resources Information Center

    Spinelli Barria, Michele; Morales, Cecilia; Merino, Cristian; Quiroz, Waldo

    2016-01-01

    In this work, we developed an ontological tool, based on the scientific realism of Mario Bunge, for the analysis of the presentation of natural processes in science textbooks. This tool was applied to analyze the presentation of the concept of osmosis in 16 chemistry and biology books at different educational levels. The results showed that more…

  4. An Examination of the Documentary Film "Einstein and Eddington" in Terms of Nature of Science Themes, Philosophical Movements, and Concepts

    ERIC Educational Resources Information Center

    Kapucu, Munise Seçkin

    2016-01-01

    This study aims to examine nature of science themes, philosophical movements, and overall concepts covered in the documentary film, "Einstein and Eddington". A qualitative research method was used. In this study, the documentary film "Einstein and Eddington," the viewing time of which is 1 hour and 28 minutes, was used as the…

  5. Changing Preservice Science Teachers' Views of Nature of Science: Why Some Conceptions May Be More Easily Altered than Others

    ERIC Educational Resources Information Center

    Mesci, Gunkut; Schwartz, Renee' S.

    2017-01-01

    The purpose of this study was to assess preservice teachers' views of Nature of Science (NOS), identify aspects that were challenging for conceptual change, and explore reasons why. This study particularly focused on why and how some concepts of NOS may be more easily altered than others. Fourteen preservice science teachers enrolled in a NOS and…

  6. Using the History of Research on Sickle Cell Anemia to Affect Preservice Teachers' Conceptions of the Nature of Science.

    ERIC Educational Resources Information Center

    Howe, Eric M.

    This paper examines how using a series of lessons developed from the history of research on sickle cell anemia affects preservice teacher conceptions of the nature of science (NOS). The importance of a pedagogy that has students do science through an integral use of the history of science is effective at enriching students' NOS views is presented.…

  7. School Students' Conceptions about Biodiversity Loss: Definitions, Reasons, Results and Solutions

    ERIC Educational Resources Information Center

    Kilinc, Ahmet; Yesiltas, Namik Kemal; Kartal, Tezcan; Demiral, Ümit; Eroglu, Baris

    2013-01-01

    Environmental degradation stemming from anthropocentric causes threatens the biodiversity more than ever before, leading scholars to warn governments about the impending consequences of biodiversity loss (BL). At this point, it is of great importance to study the public's conceptions of BL in order to identify significant educational implications.…

  8. School Students' Conceptions about Biodiversity Loss: Definitions, Reasons, Results and Solutions

    ERIC Educational Resources Information Center

    Kilinc, Ahmet; Yesiltas, Namik Kemal; Kartal, Tezcan; Demiral, Ümit; Eroglu, Baris

    2013-01-01

    Environmental degradation stemming from anthropocentric causes threatens the biodiversity more than ever before, leading scholars to warn governments about the impending consequences of biodiversity loss (BL). At this point, it is of great importance to study the public's conceptions of BL in order to identify significant educational implications.…

  9. Reaction of trace mercury in natural gas with dilute polysulfide solutions in a packed column

    SciTech Connect

    Not Available

    1991-12-01

    This paper reports that the natural gas produced around the world can contain traces of mercury which have to be removed. It is difficult to purify gas to desired mercury levels using conventional techniques. By scrubbing with dilute polysulfide solution, the residual mercury in the gas can be removed from about 0.1 to below 0.01 ppb, a reduction of 90%. In this system, the gas is passed through a packed tower wetted with a solution containing 3 ppm of polysulfide salt. Stainless steel packings are effective for this application. In addition to promoting gas-liquid contact, the stainless steel packings adsorb and concentrate polysulfides which react with Hg in the gas to form insoluble HgS, and thus remove Hg from the gas.

  10. Dizygotic twin pregnancies after medically assisted reproduction and after natural conception: maternal and perinatal outcomes.

    PubMed

    Bensdorp, Alexandra J; Hukkelhoven, Chantal W; van der Veen, Fulco; Mol, Ben W J; Lambalk, Cornelis B; van Wely, Madelon

    2016-08-01

    To compare maternal and perinatal outcomes in dizygotic twin pregnancies conceived after medically assisted reproduction (MAR) with outcomes after natural conception (NC). Nationwide registry based study. Academic medical center. Primiparous women who delivered opposite sex twins between January 2000 and December 2012 in the Netherlands, comprising dizygotic twin pregnancies: 6,694 women, 470 after ovulation induction (OI), 511 after intrauterine insemination with controlled ovarian hyperstimulation (IUI-COH), 2,437 after in vitro fertilization (IVF) with intracytoplasmic sperm injection (ICSI), and 3,276 after NC. None. Multivariable logistic regression and generalized linear mixed models to evaluate differences in outcomes: maternal outcomes of hypertension, preeclampsia, preterm delivery, hemorrhage, and delivery mode, perinatal outcomes including small for gestational age (SGA) with birth weight <10th percentile, birth weight <1,500 g, 5-minute Apgar score <7, admission to neonatal intensive care unit, congenital anomalies, and perinatal mortality. We found no statistically significant differences in maternal or perinatal outcomes after OI compared with NC. Women pregnant after IVF-ICSI had a lower risk for hypertension (adjusted odds ratio [aOR] 0.74; 95% confidence interval [CI], 0.66-0.83) compared with women pregnant after NC. After IUI-COH more children had Apgar scores <7 (adjusted odds ratio (aOR) 1.38; 95% confidence interval (CI) 1.05-1.81) and perinatal mortality rates were higher (aOR 1.56; 95% CI, 1.04-2.33) compared with NC. We found no differences in perinatal outcomes after IVF-ICSI compared with NC. Overall, maternal and perinatal risks other than those due to multiplicity are similar for twin pregnancies conceived after MAR and after NC. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  11. On the nature of bladder sensation: the concept of sensory modulation.

    PubMed

    De Wachter, S G; Heeringa, R; van Koeveringe, G A; Gillespie, J I

    2011-09-01

    Going to the toilet is an essential everyday event. Normally, we do not give much thought to the sensations and factors that trigger voiding behavior: we just go. For many people, this apparently simple task is complicated and dominates their life. They have strong sensations and sudden desires to void, often resulting in incontinence. It is therefore important that we understand the origins for this functional change and identify means to alleviate it. Literature survey. A considerable body of work has focused on this problem and ideas and concepts on the nature of bladder sensations are embedded in the literature. In this paper we argue the necessity to return to first principles and a re-examination of the problem. We explore the use of focus groups to identify relevant bladder sensation and what triggers 'bladder' behavior. We argue that there are differences in what can be described as 'introspective bladder sensations' and the sensations reported immediately before a void, 'void sensations'. Finally, we propose an alternative model describing how peripheral information generating 'introspective sensations' and 'void sensations' might be different but interrelated sensations. By exploring such ideas and identifying such complexity it is our intention to stimulate debate and generate further research in the field in order to understand better the physiology of bladder sensation and the pathology of increased urge, frequency and incontinence. Review of the literature on bladder sensation and the established ideas suggests that we might be missing something and the problem of normal and increased sensation and of urgency may be much more complex. Copyright © 2011 Wiley-Liss, Inc.

  12. The contribution of nature to people: Applying concepts of values and properties to rate the management importance of natural elements.

    PubMed

    Smith, Michael J; Wagner, Christian; Wallace, Ken J; Pourabdollah, Amir; Lewis, Loretta

    2016-06-15

    An important, and yet unresolved question in natural resource management is how best to manage natural elements and their associated values to ensure human wellbeing. Specifically, there is a lack of measurement tools to assess the contribution of nature to people. We present one approach to overcome this global issue and show that the preferred state of any system element, in terms of realising human values, is a function of element properties. Consequently, natural resource managers need to understand the nature of the relationships between element properties and values if they are to successfully manage for human wellbeing. In two case studies of applied planning, we demonstrate how to identify key element properties, quantify their relationships to priority human values, and combine this information to model the contribution of elements to human wellbeing. In one of the two case studies we also compared the modelling outputs with directly elicited stakeholder opinions regarding the importance of the elements for realising the given priority values. The two, largely congruent outputs provide additional support for the approach. The study shows that rating sets of elements on their relative overall value for human wellbeing, or utility, provides critical information for subsequent management decisions and a basis for productive new research. We consider that the described approach is broadly applicable within the domain of natural resource management.

  13. An alkalinizing oral rehydration solution containing lecithin-coated citrus fiber is superior to a nonalkalinizing solution in treating 360 calves with naturally acquired diarrhea.

    PubMed

    Goodell, G M; Campbell, J; Hoejvang-Nielsen, L; Stansen, W; Constable, P D

    2012-11-01

    The aim of this field study was to compare the efficacy and cost of 2 commercially available oral rehydration therapy (ORT) solutions in treating dairy calves with naturally acquired diarrhea. A total of 1,349 newborn Holstein-Friesian calves were prospectively enrolled in the study. Calves were housed in individual hutches and fed a mixture of pasteurized hospital milk and an all-milk protein milk replacer twice per day. Calves were monitored twice each day from d 2 of life until 30 d of age for the presence or absence of diarrhea, and were assigned a fecal score and a hydration score at each examination. Calves that developed mild to severe diarrhea that did not need intravenous fluids and did not have clinical evidence of concurrent disease (n = 360) were assigned randomly to receive 1 of 2 commercial ORT solutions: a hypertonic alkalinizing ORT containing lecithin-coated citrus fibers (Diaque, group D, n = 180; Boehringer Ingelheim, Ingelheim, Germany), and an isotonic nonalkalinizing ORT (RE-SORB, group R, n = 180; Pfizer Animal Health, New York, NY) for 2 to 8d; the duration of treatment depended on whether diarrhea was still present. No significant differences were observed in mortality rates or treatment failure rates between the 2 treatment groups. Fecal consistency returned to normal more quickly in group D calves than in group R calves; consequently, group D calves were treated for 1d less than were group R calves. The increase in body weight after 4d of treatment was larger in group D than in group R. The average daily gain from birth to weaning in calves that did not develop concurrent disease (such as pneumonia) during the study period tended to be higher in group D calves (0.53±0.11 kg/d) than in group R calves (0.51±0.09 kg/d). The smaller number of treatments at a lower cost per treatment produced a cost advantage of $4.82 per treated calf in group D calves compared with group R calves. Our findings support the concept that milk should continue

  14. Water and Solute Transport in the Shallow Subsurface of a Natural Levee

    NASA Astrophysics Data System (ADS)

    Newman, A.; Keim, R.

    2008-12-01

    In riverine wetlands, river channels are separated from backswamps by natural levees that form adjacent to the channel by sediment deposition during floods. The conventional conceptual framework is that backswamp water is impounded and disconnected from surface flow; however, layered sediments, shrink-swell clays, roots and decayed organic matter, and animal burrows likely form preferential pathways for subsurface flow and may substantially affect water and solute exchange between wetlands and river channels. To test the hypothesis that preferential flow is an important pathway of subsurface water movement through natural levees, we measured hydraulic gradients and solute tracers in a 5 x 5 m grid of 19 shallow (2m) monitoring wells within a large representative elementary volume (300 m3) of natural levee in the Atchafalaya Basin, Louisiana. In addition to measuring transient responses to precipitation, we constructed a small reservoir on the backswamp side of the levee to simulate a seasonal hydraulic gradient from the swamp to the adjacent river channel. Results indicate rapid response of water levels in all monitoring wells to the imposed hydraulic gradient as well as rain events, which included two tropical cyclones. In contrast, tracer response was highly variable, both spatially and across events, indicating a complex relationship between subsurface flow processes and water chemistry. Groundwater chemistry indicated spatially variable flowpaths. In some wells, hydraulic response coincided with a chemical shift toward low-conductivity surface water; however, other wells showed similar hydraulic responses but no change in tracer concentrations or even a shift toward higher-conductivity water that was presumably stored in the soil matrix. This spatial variation in tracer response indicates multiple mechanisms of hydraulic response, each of which has important implications for biogeochemical interactions between backswamps and channels in the shallow subsurface

  15. A new approach to evaluate natural zeolite ability to sorb lead (Pb) from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Drosos, Evangelos I. P.; Karapanagioti, Hrissi K.

    2013-04-01

    Lead (Pb) is a hazardous pollutant commonly found in aquatic ecosystems. Among several methods available, the addition of sorbent amendments to soils or sediments is attractive, since its application is relatively simple, while it can also be cost effective when a low cost and re-usable sorbent is used; e.g. natural zeolites. Zeolites are crystalline aluminosilicates with a three-dimensional structure composed of a set of cavities occupied by large ions and water molecules. Zeolites can accommodate a wide variety of cations, such as Na+, K+, Ca2+, Mg2+, which are rather loosely held and can readily be exchanged for others in an aqueous solution. Natural zeolites are capable of removing cations, such as lead, from aqueous solutions by ion exchange. There is a wide variation in the cation exchange capacity (CEC) of natural zeolites because of the different nature of various zeolites cage structures, natural structural defects, adsorbed ions, and their associated gangue minerals. Naturally occurring zeolites are rarely pure and are contaminated to varying degrees by other minerals, such as clays and feldspars, metals, quartz, or other zeolites as well. These impurities affect the CEC even for samples originated from the same region but from a different source. CEC of the material increases with decreasing impurity content. Potentially exchangeable ions in such impurities do not necessarily participate in ion exchange mechanism, while, in some cases, impurities may additionally block the access to active sites. For zeoliferous rocks having the same percentage of a zeolitic phase, the CEC increases with decreasing Si/Al ratio, as the more Si ions are substituted by Al ions, the more negative the valence of the matrix becomes. Sodium seems to be the most effective exchangeable ion for lead. On the contrary, it is unlikely that the potassium content of the zeolite would be substituted. A pretreatment with high concentration solutions of Na, such as 2 M NaCl, can

  16. The Online Dissemination of Nature-Health Concepts: Lessons from Sentiment Analysis of Social Media Relating to "Nature-Deficit Disorder".

    PubMed

    Palomino, Marco; Taylor, Tim; Göker, Ayse; Isaacs, John; Warber, Sara

    2016-01-19

    Evidence continues to grow supporting the idea that restorative environments, green exercise, and nature-based activities positively impact human health. Nature-deficit disorder, a journalistic term proposed to describe the ill effects of people's alienation from nature, is not yet formally recognized as a medical diagnosis. However, over the past decade, the phrase has been enthusiastically taken up by some segments of the lay public. Social media, such as Twitter, with its opportunities to gather "big data" related to public opinions, offers a medium for exploring the discourse and dissemination around nature-deficit disorder and other nature-health concepts. In this paper, we report our experience of collecting more than 175,000 tweets, applying sentiment analysis to measure positive, neutral or negative feelings, and preliminarily mapping the impact on dissemination. Sentiment analysis is currently used to investigate the repercussions of events in social networks, scrutinize opinions about products and services, and understand various aspects of the communication in Web-based communities. Based on a comparison of nature-deficit-disorder "hashtags" and more generic nature hashtags, we make recommendations for the better dissemination of public health messages through changes to the framing of messages. We show the potential of Twitter to aid in better understanding the impact of the natural environment on human health and wellbeing.

  17. Student Learning of Thermochemical Concepts in the Context of Solution Calorimetry.

    ERIC Educational Resources Information Center

    Greenbowe, Thomas J.; Meltzer, David E.

    2003-01-01

    Analyzes student performance on solution calorimetry problems in an introductory university chemistry class. Includes data from written classroom exams for 207 students and an extensive longitudinal interview with a student. Indicates learning difficulties, most of which appear to originate from failure to understand, that net increases and…

  18. Student Conceptions of Ionic Compounds in Solution and the Influences of Sociochemical Norms on Individual Learning

    ERIC Educational Resources Information Center

    Warfa, Abdi-Rizak M.

    2013-01-01

    Using the symbolic interactionist perspective that meaning is constituted as individuals interact with one another, this study examined how group thinking during cooperative inquiry-based activity on chemical bonding theories shaped and influenced college students' understanding of the properties of ionic compounds in solution. The analysis…

  19. Exploring Fundamental Concepts in Aqueous Solution Conductivity: A General Chemistry Laboratory Exercise

    ERIC Educational Resources Information Center

    Nyasulu, Frazier; Stevanov, Kelly; Barlag, Rebecca

    2010-01-01

    Using a conductivity sensor, a temperature sensor, and a datalogger, fundamental factors that affect conductivity are explored. These factors are (i) concentration, (ii) temperature, (iii) ion charge, and (iv) size and or mass of anion. In addition, the conductivities of a number of other solutions are measured. This lab has been designed to…

  20. Student Learning of Thermochemical Concepts in the Context of Solution Calorimetry.

    ERIC Educational Resources Information Center

    Greenbowe, Thomas J.; Meltzer, David E.

    2003-01-01

    Analyzes student performance on solution calorimetry problems in an introductory university chemistry class. Includes data from written classroom exams for 207 students and an extensive longitudinal interview with a student. Indicates learning difficulties, most of which appear to originate from failure to understand, that net increases and…

  1. Student Conceptions of Ionic Compounds in Solution and the Influences of Sociochemical Norms on Individual Learning

    ERIC Educational Resources Information Center

    Warfa, Abdi-Rizak M.

    2013-01-01

    Using the symbolic interactionist perspective that meaning is constituted as individuals interact with one another, this study examined how group thinking during cooperative inquiry-based activity on chemical bonding theories shaped and influenced college students' understanding of the properties of ionic compounds in solution. The analysis…

  2. Innovative Learning Solutions in New Communities: Opportunities and Challenges to Teachers' Conceptions of Workspace

    ERIC Educational Resources Information Center

    Costley, Debra

    2007-01-01

    This article explores the possibilities and opportunities created by large-scale property developers for new ways of learning and working in master-planned communities. The discussion is based on the findings from research of one developer's innovative solutions to learning in newly developed communities and specifically draws on data from one…

  3. Innovative Learning Solutions in New Communities: Opportunities and Challenges to Teachers' Conceptions of Workspace

    ERIC Educational Resources Information Center

    Costley, Debra

    2007-01-01

    This article explores the possibilities and opportunities created by large-scale property developers for new ways of learning and working in master-planned communities. The discussion is based on the findings from research of one developer's innovative solutions to learning in newly developed communities and specifically draws on data from one…

  4. Exploring Fundamental Concepts in Aqueous Solution Conductivity: A General Chemistry Laboratory Exercise

    ERIC Educational Resources Information Center

    Nyasulu, Frazier; Stevanov, Kelly; Barlag, Rebecca

    2010-01-01

    Using a conductivity sensor, a temperature sensor, and a datalogger, fundamental factors that affect conductivity are explored. These factors are (i) concentration, (ii) temperature, (iii) ion charge, and (iv) size and or mass of anion. In addition, the conductivities of a number of other solutions are measured. This lab has been designed to…

  5. Prevalences and pregnancy outcome of vanishing twin pregnancies achieved by in vitro fertilization versus natural conception.

    PubMed

    Márton, Virág; Zádori, János; Kozinszky, Zoltan; Keresztúri, Attila

    2016-11-01

    To evaluate whether vanishing twin (VT) pregnancies achieved by in vitro fertilization and intracytoplasmic sperm injection (IVF-ICSI) had a more adverse perinatal outcome than those after natural conception. Longitudinal, retrospective cohort study. Tertiary university hospital. Three hundred and six (78 after IVF-ICSI and 228 after natural conception) VT pregnancies over a 22-year period, with VT cases matched to primarily singleton controls. None. Obstetric and neonatal outcome data. The incidence of VT was statistically significantly higher after natural conception (18.2% of twins) than after IVF-ICSI (12.6% of twins). The odds of VT in pregnancies complicated with pregestational or gestational diabetes were disproportionally higher in IVF-ICSI cases than in spontaneously conceived VT pregnancies (adjusted odds ratio [AOR]: 0.80 vs. 3.10 and 1.00 vs. 1.07, respectively). Previous induced abortion (AOR 1.34) or second-trimester fetal loss (AOR 3.3) increased the risk of VT pregnancies after spontaneous conception. Gestational diabetes mellitus in both the previous (AOR 5.41) and the present (AOR 2.3) pregnancy as well as chronic maternal diseases (AOR 3.5) and placentation anomalies all represented independent risk factors for VT after IVF-ICSI. Vanishing twin pregnancies had a lower prevalence and a worse perinatal outcome after IVF-ICSI as compared with those of their spontaneously conceived counterparts. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  6. [Adsorption of Phosphate by Lanthanum Hydroxide/Natural Zeolite Composites from Low Concentration Phosphate Solution].

    PubMed

    Lin, Jian-wei; Wang, Hong; Zhan, Yan-hui; Chen, Dong-mei

    2016-01-15

    A series of composites of lanthanum hydroxide/natural zeolite ( La( OH) 3/NZ composites) were prepared by co-precipitation method, and these composites were used as adsorbents to remove phosphate from aqueous solution. The phosphate adsorption capacities of different composites prepared with different precipitated pH values were compared in batch mode. The adsorption characteristics of phosphate from aqueous solution on the La(OH)3/NZ composite prepared with the precipitated pH value of 11 was investigated using batch experiments. The results showed that the La(OH)3/NZ composite prepared with the precipitated pH values of 5-7 and 13 had a low adsorption capacity for phosphate in aqueous solution, while the La( OH) 3/NZ composites prepared with the precipitated pH values of 9-12 exhibited much higher phosphate adsorption capacity. The phosphate adsorption capacity of the La (OH)3/NZ composite increased with the increase of the precipitated pH value from 9 to 11, but remained basically unchanged with the increase of the precipitated pH value from 11 to 12. The equilibrium adsorption data of phosphate from aqueous solution on the La ( OH ) 3/NZ composite prepared with the precipitated pH value of 11 could be described by the Langmuir isotherm model with the predicted maximum phosphate adsorption of 44 mg x g(-1) (phosphate solution pH 7 and 30 degrees C). The kinetic data of phosphate adsorption from low concentration phosphate solution on the La(OH)3/NZ composite prepared with the precipitated pH value of 11 well followed a pseudo-second-order model. The presence of Cl- and SO4(2-) in low concentration phosphate solution had no negative effect on phosphate adsorption onto the La(OH)3/NZ composite prepared with the precipitated pH value of 11, while the presence of HCO3- slightly inhibited the adsorption of phosphate. Coexisting humic acid had a negative effect on the adsorption of phosphate at low concentration on the La(OH)3/NZ composite prepared with the

  7. An inverse problem solution to the flow of tracers in naturally fractured reservoirs

    SciTech Connect

    Jetzabeth Ramirez S.; Fernando Samaniego V.; Fernando Rodriguez; Jesus Rivera R.

    1994-01-20

    This paper presents a solution for the inverse problem to the flow of tracers in naturally fractured reservoirs. The models considered include linear flow in vertical fractures, radial flow in horizontal fractures, and cubic block matrix-fracture geometry. The Rosenbrock method for nonlinear regression used in this study, allowed the estimation of up to six parameters for the cubic block matrix fracture geometry. The nonlinear regression for the three cases was carefully tested against syntetical tracer concentration responses affected by random noise, with the objective of simulating as close as possible step injection field data. Results were obtained within 95 percent confidence limits. The sensitivity of the inverse problem solution on the main parameters that describe this flow problem was investigated. The main features of the nonlinear regression program used in this study are also discussed. The procedure of this study can be applied to interpret tracer tests in naturally fractured reservoirs, allowing the estimation of fracture and matrix parameters of practical interest (longitudinal fracture dispersivity alpha, matrix porosity phi2, fracture half-width w, matrix block size d, matrix diffusion coefficient D2 and the adsorption constant kd). The methodology of this work offers a practical alternative for tracer flow tests interpretation to other techniques.

  8. On the viscosity of natural hyper-saline solutions and its importance: The Dead Sea brines

    NASA Astrophysics Data System (ADS)

    Weisbrod, Noam; Yechieli, Yoseph; Shandalov, Semion; Lensky, Nadav

    2016-01-01

    The relationship between the density, temperature and viscosity of hypersaline solutions, both natural and synthetic, is explored. An empirical equation of the density-viscosity relationship as a function of temperature was developed for the Dead Sea brine and its dilutions. The viscosity levels of the Dead Sea brine (density of 1.24 ṡ 103 kg/m3; viscosity of 3.6 mPa s at 20 °C) and of the more extremely saline natural brine (density of 1.37 ṡ 103 kg/m3) were found to be ∼3 and ∼10 times greater than that of fresh water, respectively. The combined effect of the above changes in viscosity and density on the hydraulic conductivity is reduction by a factor of 3-7. The chemical composition significantly affects the viscosity of brines with similar densities, whereby solutions with a higher Mg/Na ratio have higher viscosity. This explains the extremely high viscosity of the Dead Sea and related Mg-rich brines in comparison with the much lower values of NaCl and KCl brines with similar density. Possible impacts of the results include reduced settling velocity of grains in hypersaline viscous brines and changing hydraulic dynamics at the freshwater-saltwater and the vicinity of sinkholes.

  9. Radiation effects on bifurcation and dual solutions in transient natural convection in a horizontal annulus

    SciTech Connect

    Luo, Kang; Yi, Hong-Liang Tan, He-Ping

    2014-05-15

    Transitions and bifurcations of transient natural convection in a horizontal annulus with radiatively participating medium are numerically investigated using the coupled lattice Boltzmann and direct collocation meshless (LB-DCM) method. As a hybrid approach based on a common multi-scale Boltzmann-type model, the LB-DCM scheme is easy to implement and has an excellent flexibility in dealing with the irregular geometries. Separate particle distribution functions in the LBM are used to calculate the density field, the velocity field and the thermal field. In the radiatively participating medium, the contribution of thermal radiation to natural convection must be taken into account, and it is considered as a radiative term in the energy equation that is solved by the meshless method with moving least-squares (MLS) approximation. The occurrence of various instabilities and bifurcative phenomena is analyzed for different Rayleigh number Ra and Prandtl number Pr with and without radiation. Then, bifurcation diagrams and dual solutions are presented for relevant radiative parameters, such as convection-radiation parameter Rc and optical thickness τ. Numerical results show that the presence of volumetric radiation changes the static temperature gradient of the fluid, and generally results in an increase in the flow critical value. Besides, the existence and development of dual solutions of transient convection in the presence of radiation are greatly affected by radiative parameters. Finally, the advantage of LB-DCM combination is discussed, and the potential benefits of applying the LB-DCM method to multi-field coupling problems are demonstrated.

  10. Radiation effects on bifurcation and dual solutions in transient natural convection in a horizontal annulus

    NASA Astrophysics Data System (ADS)

    Luo, Kang; Yi, Hong-Liang; Tan, He-Ping

    2014-05-01

    Transitions and bifurcations of transient natural convection in a horizontal annulus with radiatively participating medium are numerically investigated using the coupled lattice Boltzmann and direct collocation meshless (LB-DCM) method. As a hybrid approach based on a common multi-scale Boltzmann-type model, the LB-DCM scheme is easy to implement and has an excellent flexibility in dealing with the irregular geometries. Separate particle distribution functions in the LBM are used to calculate the density field, the velocity field and the thermal field. In the radiatively participating medium, the contribution of thermal radiation to natural convection must be taken into account, and it is considered as a radiative term in the energy equation that is solved by the meshless method with moving least-squares (MLS) approximation. The occurrence of various instabilities and bifurcative phenomena is analyzed for different Rayleigh number Ra and Prandtl number Pr with and without radiation. Then, bifurcation diagrams and dual solutions are presented for relevant radiative parameters, such as convection-radiation parameter Rc and optical thickness τ. Numerical results show that the presence of volumetric radiation changes the static temperature gradient of the fluid, and generally results in an increase in the flow critical value. Besides, the existence and development of dual solutions of transient convection in the presence of radiation are greatly affected by radiative parameters. Finally, the advantage of LB-DCM combination is discussed, and the potential benefits of applying the LB-DCM method to multi-field coupling problems are demonstrated.

  11. Growing three-dimensional biomorphic graphene powders using naturally abundant diatomite templates towards high solution processability

    NASA Astrophysics Data System (ADS)

    Chen, Ke; Li, Cong; Shi, Liurong; Gao, Teng; Song, Xiuju; Bachmatiuk, Alicja; Zou, Zhiyu; Deng, Bing; Ji, Qingqing; Ma, Donglin; Peng, Hailin; Du, Zuliang; Rümmeli, Mark Hermann; Zhang, Yanfeng; Liu, Zhongfan

    2016-11-01

    Mass production of high-quality graphene with low cost is the footstone for its widespread practical applications. We present herein a self-limited growth approach for producing graphene powders by a small-methane-flow chemical vapour deposition process on naturally abundant and industrially widely used diatomite (biosilica) substrates. Distinct from the chemically exfoliated graphene, thus-produced biomorphic graphene is highly crystallized with atomic layer-thickness controllability, structural designability and less noncarbon impurities. In particular, the individual graphene microarchitectures preserve a three-dimensional naturally curved surface morphology of original diatom frustules, effectively overcoming the interlayer stacking and hence giving excellent dispersion performance in fabricating solution-processible electrodes. The graphene films derived from as-made graphene powders, compatible with either rod-coating, or inkjet and roll-to-roll printing techniques, exhibit much higher electrical conductivity (~110,700 S m-1 at 80% transmittance) than previously reported solution-based counterparts. This work thus puts forward a practical route for low-cost mass production of various powdery two-dimensional materials.

  12. Growing three-dimensional biomorphic graphene powders using naturally abundant diatomite templates towards high solution processability.

    PubMed

    Chen, Ke; Li, Cong; Shi, Liurong; Gao, Teng; Song, Xiuju; Bachmatiuk, Alicja; Zou, Zhiyu; Deng, Bing; Ji, Qingqing; Ma, Donglin; Peng, Hailin; Du, Zuliang; Rümmeli, Mark Hermann; Zhang, Yanfeng; Liu, Zhongfan

    2016-11-07

    Mass production of high-quality graphene with low cost is the footstone for its widespread practical applications. We present herein a self-limited growth approach for producing graphene powders by a small-methane-flow chemical vapour deposition process on naturally abundant and industrially widely used diatomite (biosilica) substrates. Distinct from the chemically exfoliated graphene, thus-produced biomorphic graphene is highly crystallized with atomic layer-thickness controllability, structural designability and less noncarbon impurities. In particular, the individual graphene microarchitectures preserve a three-dimensional naturally curved surface morphology of original diatom frustules, effectively overcoming the interlayer stacking and hence giving excellent dispersion performance in fabricating solution-processible electrodes. The graphene films derived from as-made graphene powders, compatible with either rod-coating, or inkjet and roll-to-roll printing techniques, exhibit much higher electrical conductivity (∼110,700 S m(-1) at 80% transmittance) than previously reported solution-based counterparts. This work thus puts forward a practical route for low-cost mass production of various powdery two-dimensional materials.

  13. Growing three-dimensional biomorphic graphene powders using naturally abundant diatomite templates towards high solution processability

    PubMed Central

    Chen, Ke; Li, Cong; Shi, Liurong; Gao, Teng; Song, Xiuju; Bachmatiuk, Alicja; Zou, Zhiyu; Deng, Bing; Ji, Qingqing; Ma, Donglin; Peng, Hailin; Du, Zuliang; Rümmeli, Mark Hermann; Zhang, Yanfeng; Liu, Zhongfan

    2016-01-01

    Mass production of high-quality graphene with low cost is the footstone for its widespread practical applications. We present herein a self-limited growth approach for producing graphene powders by a small-methane-flow chemical vapour deposition process on naturally abundant and industrially widely used diatomite (biosilica) substrates. Distinct from the chemically exfoliated graphene, thus-produced biomorphic graphene is highly crystallized with atomic layer-thickness controllability, structural designability and less noncarbon impurities. In particular, the individual graphene microarchitectures preserve a three-dimensional naturally curved surface morphology of original diatom frustules, effectively overcoming the interlayer stacking and hence giving excellent dispersion performance in fabricating solution-processible electrodes. The graphene films derived from as-made graphene powders, compatible with either rod-coating, or inkjet and roll-to-roll printing techniques, exhibit much higher electrical conductivity (∼110,700 S m−1 at 80% transmittance) than previously reported solution-based counterparts. This work thus puts forward a practical route for low-cost mass production of various powdery two-dimensional materials. PMID:27819652

  14. Removal of phosphate from aqueous solutions and sewage using natural and surface modified coir pith.

    PubMed

    Krishnan, K Anoop; Haridas, Ajit

    2008-04-01

    Iron impregnated coir pith (CP-Fe-I) can be effectively used for the removal of phosphate from aqueous streams and sewage. Iron impregnation on natural coir pith was carried out by drop by drop addition method. The effect of various factors such as pH, initial concentration of phosphate, contact time and adsorbent dose on phosphate adsorption was studied by batch technique. The pH at 3.0 favored the maximum adsorption of phosphate from aqueous solutions. The effect of pH on phosphate adsorption was explained by pH(zpc), phosphate speciation in solution and affinity of anions towards the adsorbent sites. A comparative study of the adsorption of phosphate using CP-Fe-I and CP (coir pith) was made and results show that the former one is five to six times more effective than the latter. Kinetic studies revealed that the adsorption process followed a pseudo-second order kinetic model. Adsorption followed Langmuir isotherm model. Column studies were conducted to examine the utility of the investigated adsorbent for the removal of phosphate from continuously flowing aqueous solutions.

  15. Pyrene and phenanthrene sorption to model and natural geosorbents in single- and binary-solute systems.

    PubMed

    Zhang, Jing; Séquaris, Jean-Marie; Narres, Hans-Dieter; Vereecken, Harry; Klumpp, Erwin

    2010-11-01

    Sorption of pyrene and phenanthrene to model (illite and charcoal) and natural (Yangtze sediment) geosorbents were investigated by batch techniques using fluorescence spectroscopy. A higher adsorption of phenanthrene was observed with all sorbents, which is related to the better accessibility of smaller molecules to micropores in the molecular sieve sorbents. In addition, pyrene sorption in binary-solute systems with a constant initial concentration of phenanthrene (0.1 μmol L(-1) or 2 μmol L(-1)) was studied. A 0.1 μmol L(-1) concentration of phenanthrene causes no competitive effect on the pyrene sorption. A 2 μmol L(-1) concentration of phenanthrene significantly suppresses the sorption of pyrene, especially in the low concentration range; nonlinearity of the pyrene sorption isotherms thus decreases. The competitive effect of 2 μmol L(-1) phenanthrene on the pyrene sorption is overestimated by the ideal adsorbed solution theory (IAST) using the fitted single sorption results of both solutes. An adjustment of the IAST application by taking into account the molecular sieve effect is proposed, which notably improves the IAST prediction for the competitive effect.

  16. Electromagnetic Field Solutions for the Natural Modes of a Cylindrical Cavity Loaded with Lossy Materials.

    NASA Astrophysics Data System (ADS)

    Manring, Edward Benjamin

    A rigorous solution is presented for the natural mode fields of a circular cylindrical cavity coaxially loaded with homogeneous, isotropic, lossy materials for loads of arbitrary length and distance from the cavity end plates. Field expressions and numerically stable characteristic equations are derived for the coaxially-loaded waveguide, the coaxially-loaded cavity with cavity-length loads (cavity -short type), and the coaxially-loaded cavity with loads of length less than cavity-length (cavity-open type). Cavity -open type solutions are constructed using a mode-matching technique which is shown to be more numerically stable than the mode-matching method previously published for lossless loads. Theoretical and experimental resonant frequency are shown to agree to within 0.2% for a 1" diameter nylon load in a 6" diameter cavity for the cavity-short type configuration and to within 0.06% for all lengths from zero to cavity-length of a 0.5" diameter nylon load in a 6" diameter cavity for the cavity-open type configuration. A solution is included for the azimuthally symmetric TM modes of the cavity-open type configuration for a conducting load; this solution equally applies to the reentrant cavity. Numerical solutions are presented for TE, TM, and hybrid modes of the coaxially-loaded waveguide and the cavity-short type configuration, and the TM modes of the cavity-open type configuration. Complex mode behavior is demonstrated in the waveguide for lossless loads with high dielectric constant. For lossy loads, a backward wave region is discovered in the low frequency range for TM modes. Mode charts presented for the cavity-short type configuration show that mode behavior is highly diverse and that modes cannot be consistently labeled by association with corresponding empty cavity modes which are approached as the load radius becomes small or the dielectric constant approaches unity. Very high loss factor loads are shown to behave like good conductors. It is shown that a

  17. [Mouthwash solutions containing microencapsulated natural extracts: Clinical results on dental plaque and gingivitis].

    PubMed

    Mouhyi, J; Del Corso, M; Hippolyte, M-P; Sammartino, G; Dohan Ehrenfest, D M

    2010-06-01

    New mouthwash solutions containing microencapsulated natural extracts have been developed. Besides antiseptic activity, these solutions have antioxidant and immunoregulatory properties on oral tissues. The objective of this preliminary clinical study was to assess the efficiency of a mouthwash containing microencapsulated natural extracts (GingiNat, LoB5 Foundation, Paris, France) on gingivitis. Twenty volunteers (37 + or - 2 years) with significant gingivitis (bleeding when tooth-brushing) used a 6% GingiNat mouthwash solution, two to three times per day (according to oral hygiene habits) for 21 days in addition to their usual oral care. Each volunteer was examined at day 0, 4, 7 and 21. The Löe and Silness Plaque Index, the Russel Periodontal Index, a breath index (halitosis), and oral tissue tolerance were assessed. Finally, each volunteer filled in a daily follow-up form and answered a questionnaire on tolerance and acceptability. A significant decrease of the dental plaque index was observed on day 4, 7, and 21, in respectively 29, 48 and 71% of volunteers. This decrease reached 18% on day 4 (p=0.014), 32% on day 7 (p=0.002), and 47% on day 21 (p<0.001). A significant decrease of the periodental index was observed on day 4, 7 and 21, in respectively 52, 81 and 95% of volunteers. This decrease reached 30% (p=0.001) on day 4, 49% (p<0.001) on day 7, and 78% (p<0.001) on day 21. A significant improvement of the breath index was noted on day 4, 7, and 21, in respectively 43, 52 and 48% of volunteers. This improvement reached 29% (p=0.004) on day 4, 35% (p=0.001) on day 7, and 32% (p=0.002) on day 21. The mouthwash was well tolerated. The patients liked its effectiveness and organoleptic properties. All patients expressed the wish to continue using this solution. The GingiNat mouthwash solution at 6% had a significant efficiency on plaque, gingivitis, and halitosis after 21 days of use. This makes it a good complementary treatment for gingivitis. Tolerance and

  18. Multi-period natural gas market modeling Applications, stochastic extensions and solution approaches

    NASA Astrophysics Data System (ADS)

    Egging, Rudolf Gerardus

    This dissertation develops deterministic and stochastic multi-period mixed complementarity problems (MCP) for the global natural gas market, as well as solution approaches for large-scale stochastic MCP. The deterministic model is unique in the combination of the level of detail of the actors in the natural gas markets and the transport options, the detailed regional and global coverage, the multi-period approach with endogenous capacity expansions for transportation and storage infrastructure, the seasonal variation in demand and the representation of market power according to Nash-Cournot theory. The model is applied to several scenarios for the natural gas market that cover the formation of a cartel by the members of the Gas Exporting Countries Forum, a low availability of unconventional gas in the United States, and cost reductions in long-distance gas transportation. 1 The results provide insights in how different regions are affected by various developments, in terms of production, consumption, traded volumes, prices and profits of market participants. The stochastic MCP is developed and applied to a global natural gas market problem with four scenarios for a time horizon until 2050 with nineteen regions and containing 78,768 variables. The scenarios vary in the possibility of a gas market cartel formation and varying depletion rates of gas reserves in the major gas importing regions. Outcomes for hedging decisions of market participants show some significant shifts in the timing and location of infrastructure investments, thereby affecting local market situations. A first application of Benders decomposition (BD) is presented to solve a large-scale stochastic MCP for the global gas market with many hundreds of first-stage capacity expansion variables and market players exerting various levels of market power. The largest problem solved successfully using BD contained 47,373 variables of which 763 first-stage variables, however using BD did not result in

  19. Methods and Devices for Fighting Natural Fires Within a New Concept of Control of Natural and Man-Made Disasters

    NASA Astrophysics Data System (ADS)

    Grishin, A. M.; Zima, V. P.; Kasymov, D. P.

    2014-07-01

    Developments of methods and devices for localization and suppression of natural fires are presented. These developments have been created with account taken of the knowledge on the frame structure. With them, one can destroy, by relatively small energy actions, the most vulnerable parts of the fire front: the zones of pyrolysis and mixing of combustible pyrolysis products with the air oxygen.

  20. Concepts and solutions for future-proof health information systems and health networks.

    PubMed

    Blobel, Bernd

    2003-01-01

    Based on shared care information systems' requirements for high level interoperability, a generic component architecture has been derived. For implementing, running and maintaining acceptable and useable health information systems components, all views of the ISO Reference Model--Open Distributed Processing have to be considered. Following the Model Driven Architecture (MDA) paradigm, a reference model as well as concept-representing domain models both independent of platforms must be specified, which are combined and harmonised as well as automatically transferred into the platform-specific models using appropriate tools.

  1. Supply Chain Based Solution to Prevent Fuel Tax Evasion: Proof of Concept Final Report

    SciTech Connect

    Capps, Gary J; Lascurain, Mary Beth; Franzese, Oscar; Earl, Dennis Duncan; West, David L; McIntyre, Timothy J; Chin, Shih-Miao; Hwang, Ho-Ling; Connatser, Raynella M; Lewis Sr, Samuel Arthur; Moore, Sheila A

    2011-12-01

    The goal of this research was to provide a proof-of-concept (POC) system for preventing non-taxable (non-highway diesel use) or low-taxable (jet fuel) petrochemical products from being blended with taxable fuel products and preventing taxable fuel products from cross-jurisdiction evasion. The research worked to fill the need to validate the legitimacy of individual loads, offloads, and movements by integrating and validating, on a near-real-time basis, information from global positioning system (GPS), valve sensors, level sensors, and fuel-marker sensors.

  2. A Resource for Eliciting Student Alternative Conceptions: Examining the Adaptability of a Concept Inventory for Natural Selection at the Secondary School Level

    NASA Astrophysics Data System (ADS)

    Lucero, Margaret M.; Petrosino, Anthony J.

    2016-07-01

    The Conceptual Inventory of Natural Selection (CINS) is an example of a research-based instrument that assesses conceptual understanding in an area that contains well-documented alternative conceptions. Much of the CINS's use and original validation has been relegated to undergraduate settings, but the information learned from student responses on the CINS can also potentially be a useful resource for teachers at the secondary level. Because of its structure, the CINS can have a role in eliciting alternative conceptions and induce deeper conceptual understanding by having student ideas leveraged during instruction. In a first step toward this goal, the present study further investigated the CINS's internal properties by having it administered to a group (n = 339) of students among four different biology teachers at a predominantly Latino, economically disadvantaged high school. In addition, incidences of the concept inventory's use among the teachers' practices were collected for support of its adaptability at the secondary level. Despite the teachers' initial enthusiasm for the CINS's use as an assessment tool in the present study, results from a principal components analysis demonstrate inconsistencies between the original and present validations. Results also reveal how the teachers think CINS items may be revised for future use among secondary student populations.

  3. A Resource for Eliciting Student Alternative Conceptions: Examining the Adaptability of a Concept Inventory for Natural Selection at the Secondary School Level

    NASA Astrophysics Data System (ADS)

    Lucero, Margaret M.; Petrosino, Anthony J.

    2017-08-01

    The Conceptual Inventory of Natural Selection (CINS) is an example of a research-based instrument that assesses conceptual understanding in an area that contains well-documented alternative conceptions. Much of the CINS's use and original validation has been relegated to undergraduate settings, but the information learned from student responses on the CINS can also potentially be a useful resource for teachers at the secondary level. Because of its structure, the CINS can have a role in eliciting alternative conceptions and induce deeper conceptual understanding by having student ideas leveraged during instruction. In a first step toward this goal, the present study further investigated the CINS's internal properties by having it administered to a group ( n = 339) of students among four different biology teachers at a predominantly Latino, economically disadvantaged high school. In addition, incidences of the concept inventory's use among the teachers' practices were collected for support of its adaptability at the secondary level. Despite the teachers' initial enthusiasm for the CINS's use as an assessment tool in the present study, results from a principal components analysis demonstrate inconsistencies between the original and present validations. Results also reveal how the teachers think CINS items may be revised for future use among secondary student populations.

  4. Darwin's "Imaginary Illustrations": Creatively Teaching Evolutionary Concepts & the Nature of Science

    ERIC Educational Resources Information Center

    Love, Alan C.

    2010-01-01

    An overlooked feature of Darwin's work is his use of "imaginary illustrations" to show that natural selection is competent to produce adaptive, evolutionary change. When set in the context of Darwin's methodology, these thought experiments provide a novel way to teach natural selection and the nature of science.

  5. Darwin's "Imaginary Illustrations": Creatively Teaching Evolutionary Concepts & the Nature of Science

    ERIC Educational Resources Information Center

    Love, Alan C.

    2010-01-01

    An overlooked feature of Darwin's work is his use of "imaginary illustrations" to show that natural selection is competent to produce adaptive, evolutionary change. When set in the context of Darwin's methodology, these thought experiments provide a novel way to teach natural selection and the nature of science.

  6. Adsorptive removal of Cd(II) from aqueous solution using natural and modified rice husk.

    PubMed

    Ye, Hengpeng; Zhu, Qing; Du, Dongyun

    2010-07-01

    In this study, the natural and modified rice husk were tested to remove Cd(II) ions from water. The modified rice husk was prepared by being treated with alkali. The results showed the Cd(II) adsorption capacity was 73.96, 125.94 mg/g, respectively, for the natural and modified rice husk. The modified rice husk had faster kinetics and higher adsorption capacities than the natural rice husk, which can be attributed to the surface structural changes of the material. Equilibrium adsorption data are more consistent with the Langmuir isotherm equation than with the Freundlich equation. The Cd(II) adsorption on the two adsorbents tends to increase with the increase of pH. The optimum pH for Cd(II) adsorption is 6.5. Both pseudo-first-order and pseudo-second-order equations were able to describe properly the kinetics of Cd(II) adsorption. The desorbability of Cd(II) is about 95.8-99.1% by 0.1M HCl solution.

  7. Nature of Science and Science Content Learning. The Relation Between Students' Nature of Science Understanding and Their Learning About the Concept of Energy

    NASA Astrophysics Data System (ADS)

    Michel, Hanno; Neumann, Irene

    2016-12-01

    Besides viewing knowledge about the nature of science (NOS) as important for its own value with respect to scientific literacy, an adequate understanding of NOS is expected to improve science content learning by fostering the ability to interrelate scientific concepts and, thus, coherently acquire scientific content knowledge. However, there is a lack of systematic investigations, which clarify the relations between NOS and science content learning. In this paper, we present the results of a study, conducted to investigate how NOS understanding relates to students' acquisition of a proper understanding of the concept of energy. A total of 82 sixth and seventh grade students received an instructional unit on energy, with 41 of them receiving generic NOS instruction beforehand. This NOS instruction, however, did not result in students having higher scores on the NOS instrument. Thus, correlational analyses were performed to investigate how students' NOS understanding prior to the energy unit related to their learning about science content. Results show that a more adequate understanding of NOS might relate to students' perspective on the concept of energy and might support them in understanding the nature of energy as a theoretical concept. Students with higher NOS understanding, for example, seemed to be more capable of learning how to relate the different energy forms to each other and to justify why they can be subsumed under the term of energy. Further, we found that NOS understanding may also be related to students' approach toward energy degradation—a concept that can be difficult for students to master—while it does not seem to have a substantive impact on students' learning gain regarding energy forms, transformation, or conservation.

  8. Nature of Science and Science Content Learning - The Relation Between Students' Nature of Science Understanding and Their Learning About the Concept of Energy

    NASA Astrophysics Data System (ADS)

    Michel, Hanno; Neumann, Irene

    2017-01-01

    Besides viewing knowledge about the nature of science (NOS) as important for its own value with respect to scientific literacy, an adequate understanding of NOS is expected to improve science content learning by fostering the ability to interrelate scientific concepts and, thus, coherently acquire scientific content knowledge. However, there is a lack of systematic investigations, which clarify the relations between NOS and science content learning. In this paper, we present the results of a study, conducted to investigate how NOS understanding relates to students' acquisition of a proper understanding of the concept of energy. A total of 82 sixth and seventh grade students received an instructional unit on energy, with 41 of them receiving generic NOS instruction beforehand. This NOS instruction, however, did not result in students having higher scores on the NOS instrument. Thus, correlational analyses were performed to investigate how students' NOS understanding prior to the energy unit related to their learning about science content. Results show that a more adequate understanding of NOS might relate to students' perspective on the concept of energy and might support them in understanding the nature of energy as a theoretical concept. Students with higher NOS understanding, for example, seemed to be more capable of learning how to relate the different energy forms to each other and to justify why they can be subsumed under the term of energy. Further, we found that NOS understanding may also be related to students' approach toward energy degradation—a concept that can be difficult for students to master—while it does not seem to have a substantive impact on students' learning gain regarding energy forms, transformation, or conservation.

  9. A Natural Language Processing System to Extract and Code Concepts Relating to Congestive Heart Failure from Chest Radiology Reports

    PubMed Central

    Friedlin, Jeff; McDonald, Clement J.

    2006-01-01

    We have developed a natural language processing system for extracting and coding clinical data from free text reports. The system is designed to be easily modified and adapted to a variety of free text clinical reports such as admission notes, radiology and pathology reports, and discharge summaries. This report presents the results of this system to extract and code clinical concepts related to congestive heart failure from 39,000 chest radiology reports. The system detects the presence or absence of six concepts: congestive heart failure, Kerley B lines, cardiomegaly, prominent pulmonary vasculature, pulmonary edema, and pleural effusion. We compared its output to a gold standard which consisted of specially trained human coders as well as an experienced physician. Results indicate that the system had high specificity, recall and precision for each of the concepts it is designed to detect. PMID:17238345

  10. Sustainable Solution for Crude Oil and Natural Gas Separation using Concentrated Solar Power Technology

    NASA Astrophysics Data System (ADS)

    Choudhary, Piyush; Srivastava, Rakesh K.; Nath Mahendra, Som; Motahhir, Saad

    2017-08-01

    In today’s scenario to combat with climate change effects, there are a lot of reasons why we all should use renewable energy sources instead of fossil fuels. Solar energy is one of the best options based on features like good for the environment, independent of electricity prices, underutilized land, grid security, sustainable growth, etc. This concept paper is oriented primarily focused on the use of Solar Energy for the crude oil heating purpose besides other many prospective industrial applications to reduce cost, carbon footprint and moving towards a sustainable and ecologically friendly Oil & Gas Industry. Concentrated Solar Power technology based prototype system is proposed to substitute the presently used system based on natural gas burning method. The hybrid system which utilizes the solar energy in the oil and gas industry would strengthen the overall field working conditions, safety measures and environmental ecology. 40% reduction on natural gas with this hybrid system is estimated. A positive implication for an environment, working conditions and safety precautions is the additive advantage. There could also decrease air venting of CO2, CH4 and N2O by an average of 30-35%.

  11. Using nurses' natural language entries to build a concept-oriented terminology for patients' chief complaints in the emergency department.

    PubMed

    Travers, Debbie A; Haas, Stephanie W

    2003-01-01

    Information about the chief complaint (CC), also known as the patient's reason for seeking emergency care, is critical for patient prioritization for treatment and determination of patient flow through the emergency department (ED). Triage nurses document the CC at the start of the ED visit, and the data are increasingly available in electronic form. Despite the clinical and operational significance of the CC to the ED, there is no standard CC terminology. We propose the construction of concept-oriented nursing terminologies from the actual language used by experts. We use text analysis to extract CC concepts from triage nurses' natural language entries. Our methodology for building the nursing terminology utilizes natural language processing techniques and the Unified Medical Language System.

  12. Exploring the Relationship between Secondary Science Teachers' Subject Matter Knowledge and Knowledge of Student Conceptions While Teaching Evolution by Natural Selection

    ERIC Educational Resources Information Center

    Lucero, Margaret M.; Petrosino, Anthony J.; Delgado, Cesar

    2017-01-01

    The fundamental scientific concept of evolution occurring by natural selection is home to many deeply held alternative conceptions and considered difficult to teach. Science teachers' subject matter knowledge (SMK) and the pedagogical content knowledge (PCK) component of knowledge of students' conceptions (KOSC) can be valuable resources for…

  13. Exploring the Relationship between Secondary Science Teachers' Subject Matter Knowledge and Knowledge of Student Conceptions While Teaching Evolution by Natural Selection

    ERIC Educational Resources Information Center

    Lucero, Margaret M.; Petrosino, Anthony J.; Delgado, Cesar

    2017-01-01

    The fundamental scientific concept of evolution occurring by natural selection is home to many deeply held alternative conceptions and considered difficult to teach. Science teachers' subject matter knowledge (SMK) and the pedagogical content knowledge (PCK) component of knowledge of students' conceptions (KOSC) can be valuable resources for…

  14. Effects of radiation damping for biomolecular NMR experiments in solution: a hemisphere concept for water suppression.

    PubMed

    Ishima, Rieko

    2015-09-01

    Abundant solvent nuclear spins, such as water protons in aqueous solution, cause radiation damping in NMR experiments. It is important to know how the effect of radiation damping appears in high-resolution protein NMR because macromolecular studies always require very high magnetic field strengths with a highly sensitive NMR probe that can easily cause radiation damping. Here, we show the behavior of water magnetization after a pulsed-field gradient (PFG) using nutation experiments at 900 MHz with a cryogenic probe: when water magnetization is located in the upper hemisphere (having +Z component, parallel to the external magnetic field), dephasing of the magnetization by a PFG effectively suppresses residual water magnetization in the transverse plane. In contrast, when magnetization is located in the lower hemisphere (having -Z component), the small residual transverse component remaining after a PFG is still sufficient to induce radiation damping. Based on this observation, we designed (1)H-(15)N HSQC experiments in which water magnetization is maintained in the upper hemisphere, but not necessarily along Z, and compared them with the conventional experiments, in which water magnetization is inverted during the t1 period. The result demonstrates moderate gain of signal-to-noise ratio, 0-28%. Designing the experiments such that water magnetization is maintained in the upper hemisphere allows shorter pulses to be used compared to the complete water flip-back and, thereby, is useful as a building block of protein NMR pulse programs in solution.

  15. Effects of radiation damping for biomolecular NMR experiments in solution: a hemisphere concept for water suppression

    PubMed Central

    Ishima, Rieko

    2016-01-01

    Abundant solvent nuclear spins, such as water protons in aqueous solution, cause radiation damping in NMR experiments. It is important to know how the effect of radiation damping appears in high-resolution protein NMR because macromolecular studies always require very high magnetic field strengths with a highly sensitive NMR probe that can easily cause radiation damping. Here, we show the behavior of water magnetization after a pulsed-field gradient (PFG) using nutation experiments at 900 MHz with a cryogenic probe: when water magnetization is located in the upper hemisphere (having +Z component, parallel to the external magnetic field), dephasing of the magnetization by a PFG effectively suppresses residual water magnetization in the transverse plane. In contrast, when magnetization is located in the lower hemisphere (having −Z component), the small residual transverse component remaining after a PFG is still sufficient to induce radiation damping. Based on this observation, we designed 1H-15N HSQC experiments in which water magnetization is maintained in the upper hemisphere, but not necessarily along Z, and compared them with the conventional experiments, in which water magnetization is inverted during the t1 period. The result demonstrates moderate gain of signal-to-noise ratio, 0–28%. Designing the experiments such that water magnetization is maintained in the upper hemisphere allows shorter pulses to be used compared to the complete water flip-back and, thereby, is useful as a building block of protein NMR pulse programs in solution. PMID:27524944

  16. Solving problems on base of concepts formalization of language image and figurative meaning of the natural-language constructs

    NASA Astrophysics Data System (ADS)

    Bisikalo, Oleg V.; Cieszczyk, Sławomir; Yussupova, Gulbahar

    2015-12-01

    Building of "clever" thesaurus by algebraic means on base of concepts formalization of language image and figurative meaning of the natural-language constructs in the article are proposed. A formal theory based on a binary operator of directional associative relation is constructed and an understanding of an associative normal form of image constructions is introduced. A model of a commutative semigroup, which provides a presentation of a sentence as three components of an interrogative language image construction, is considered.

  17. New fundamental evidence of non-classical structure in the combination of natural concepts.

    PubMed

    Aerts, D; Sozzo, S; Veloz, T

    2016-01-13

    We recently performed cognitive experiments on conjunctions and negations of two concepts with the aim of investigating the combination problem of concepts. Our experiments confirmed the deviations (conceptual vagueness, underextension, overextension etc.) from the rules of classical (fuzzy) logic and probability theory observed by several scholars in concept theory, while our data were successfully modelled in a quantum-theoretic framework developed by ourselves. In this paper, we isolate a new, very stable and systematic pattern of violation of classicality that occurs in concept combinations. In addition, the strength and regularity of this non-classical effect leads us to believe that it occurs at a more fundamental level than the deviations observed up to now. It is our opinion that we have identified a deep non-classical mechanism determining not only how concepts are combined but, rather, how they are formed. We show that this effect can be faithfully modelled in a two-sector Fock space structure, and that it can be exactly explained by assuming that human thought is the superposition of two processes, a 'logical reasoning', guided by 'logic', and a 'conceptual reasoning', guided by 'emergence', and that the latter generally prevails over the former. All these findings provide new fundamental support to our quantum-theoretic approach to human cognition.

  18. Microbially-Enhanced Redox Solution Reoxidation for Sour Natural Gas Sweetening

    SciTech Connect

    Kenneth Brezinsky

    2008-01-15

    The specific objective of this project are to advance the technology and improve the economics of the commercial iron-based chelate processes such as LO-CAT II and SulFerox process utilizing biologically enhanced reoxidation of the redox solutions used in these processes. The project is based on the use of chelated ferric iron as the catalyst for the production of elemental sulfur, and then oxidizing bacteria, such as Thiobacillus Ferrooxidans (ATCC 23270) as an oxidizer. The regeneration of Fe{sup 3+} - chelate is accomplished by the use of these same microbes under mild conditions at 25-30 C and at atmospheric pressure to minimize the chelate degradation process. The pH of the redox solution was observed to be a key process parameter. Other parameters such as temperature, total iron concentration, gas to liquid ratio and bacterial cell densities also influence the overall process. The second part of this project includes experimental data and a kinetic model of microbial H{sub 2}S removal from sour natural gas using thiobacillus species. In the experimental part, a series of experiments were conducted with a commercial chelated iron catalyst at pH ranges from 8.7 to 9.2 using a total iron concentration range from 925 ppm to 1050 ppm in the solution. Regeneration of the solution was carried out by passing air through the solution. Iron oxidizing bacteria were used at cell densities of 2.3 x 10{sup 7}cells/ml for optimum effective performance. In the modeling part, oxidation of Fe{sup 2+} ions by the iron oxidizing bacteria - Thiobacillus Ferrooxidans was studied for application to a continuous stirred tank reactor (CSTR). The factors that can directly affect the oxidation rate such as dilution rate, temperature, and pH were analyzed. The growth of the microorganism was assumed to follow Monod type of growth kinetics. Dilution rate had influence on the rate of oxidation of ferrous iron. Higher dilution rates caused washout of the biomass. The oxidation rate was

  19. Ipomoea dasysperma seed gum: an effective natural coagulant for the decolorization of textile dye solutions.

    PubMed

    Sanghi, Rashmi; Bhattacharya, Bani; Dixit, Awantika; Singh, Vandana

    2006-10-01

    An investigation of dye decolorization from synthetic dye solutions using the non-ionic, water-soluble, high molecular weight seed gums Ipomoea dasysperma and guar gum as coagulants was undertaken. The use of galactomannans derived from plants in this system presents a sustainable method of textile effluent treatment. These natural coagulants extracted from plants proved to be workable alternatives to conventional coagulants like polyaluminum chloride, as they are biodegradable, safe to human health, are cost effective when compared to imported chemicals and have a wider effective dosage range for flocculation of various colloidal suspensions. Coagulant dose and coagulation pH are important factors influencing the mechanism of coagulation. Also the type and chemical structure of the dye plays an important role in the coagulation process. The seed gums alone were found to be effective for decolorization of direct dye and in combination with PAC their coagulation efficiency was well extended even for reactive and acid dyes.

  20. Solution to Shape Identification of Unsteady Natural Convection Fields to Control Temperature Distribution

    NASA Astrophysics Data System (ADS)

    Katamine, Eiji; Imai, Shinya; Mathmatical design Team; Computational mechanics Team

    2016-11-01

    This paper presents a numerical solution to shape identification of unsteady natural convection fields to control temperature to a prescribed distribution. The square error integral between the actual temperature distributions and the prescribed temperature distributions on the prescribed sub-boundaries during the specified period of time is used as the objective functional. Shape gradient of the shape identification problem is derived theoretically using the Lagrange multiplier method, adjoint variable method, and the formulae of the material derivative. Reshaping is carried out by the traction method proposed as an approach to solving shape optimization problems. Numerical analyses program for the shape identification is developed based on FreeFem++, and the validity of proposed method is confirmed by results of 2D numerical analyses.

  1. Natural convection in binary gases driven by combined horizontal thermal and vertical solutal gradients

    NASA Technical Reports Server (NTRS)

    Weaver, J. A.; Viskanta, Raymond

    1992-01-01

    An investigation of natural convection is presented to examine the influence of a horizontal temperature gradient and a concentration gradient occurring from the bottom to the cold wall in a cavity. As the solutal buoyancy force changes from augmenting to opposing the thermal buoyancy force, the fluid motion switches from unicellular to multicellular flow (fluid motion is up the cold wall and down the hot wall for the bottom counterrotating flow cell). Qualitatively, the agreement between predicted streamlines and smoke flow patterns is generally good. In contrast, agreement between measured and predicted temperature and concentration distributions ranges from fair to poor. Part of the discrepancy can be attributed to experimental error. However, there remains considerable discrepancy between data and predictions due to the idealizations of the mathematical model, which examines only first-order physical effects. An unsteady flow, variable thermophysical properties, conjugate effects, species interdiffusion, and radiation were not accounted for in the model.

  2. Cultivating nature-based solutions: The governance of communal urban gardens in the European Union.

    PubMed

    van der Jagt, Alexander P N; Szaraz, Luca R; Delshammar, Tim; Cvejić, Rozalija; Santos, Artur; Goodness, Julie; Buijs, Arjen

    2017-08-17

    In many countries in the European Union (EU), the popularity of communal urban gardening (CUG) on allotments and community gardens is on the rise. Given the role of this practice in increasing urban resilience, most notably social resilience, municipalities in the Global North are promoting CUG as a nature-based solution (NbS). However, the mechanisms by which institutional actors can best support and facilitate CUG are understudied, which could create a gap between aspiration and reality. The aim of this study is therefore to identify what governance arrangements contribute to CUG delivering social resilience. Through the EU GREEN SURGE project, we studied six CUG initiatives from five EU-countries, representing different planning regimes and traditions. We selected cases taking a locally unique or innovative approach to dealing with urban challenges. A variety of actors associated with each of the cases were interviewed to achieve as complete a picture as possible regarding important governance arrangements. A cross-case comparison revealed a range of success factors, varying from clearly formulated objectives and regulations, municipal support, financial resources and social capital through to the availability of local food champions and facilitators engaging in community building. Municipalities can support CUG initiatives by moving beyond a rigid focus on top-down control, while involved citizens can increase the impact of CUG by pursuing political, in addition to hands-on, activities. We conclude that CUG has clear potential to act as a nature-based solution if managed with sensitivity to local dynamics and context. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. The protein folds as platonic forms: new support for the pre-Darwinian conception of evolution by natural law.

    PubMed

    Denton, Michael J; Marshall, Craig J; Legge, Michael

    2002-12-07

    Before the Darwinian revolution many biologists considered organic forms to be determined by natural law like atoms or crystals and therefore necessary, intrinsic and immutable features of the world order, which will occur throughout the cosmos wherever there is life. The search for the natural determinants of organic form-the celebrated "Laws of Form"-was seen as one of the major tasks of biology. After Darwin, this Platonic conception of form was abandoned and natural selection, not natural law, was increasingly seen to be the main, if not the exclusive, determinant of organic form. However, in the case of one class of very important organic forms-the basic protein folds-advances in protein chemistry since the early 1970s have revealed that they represent a finite set of natural forms, determined by a number of generative constructional rules, like those which govern the formation of atoms or crystals, in which functional adaptations are clearly secondary modifications of primary "givens of physics." The folds are evidently determined by natural law, not natural selection, and are "lawful forms" in the Platonic and pre-Darwinian sense of the word, which are bound to occur everywhere in the universe where the same 20 amino acids are used for their construction. We argue that this is a major discovery which has many important implications regarding the origin of proteins, the origin of life and the fundamental nature of organic form. We speculate that it is unlikely that the folds will prove to be the only case in nature where a set of complex organic forms is determined by natural law, and suggest that natural law may have played a far greater role in the origin and evolution of life than is currently assumed.

  4. Outcomes of nature of science instruction along a context continuum: preservice secondary science teachers' conceptions and instructional intentions

    NASA Astrophysics Data System (ADS)

    Bell, Randy L.; Mulvey, Bridget K.; Maeng, Jennifer L.

    2016-02-01

    This investigation examined outcomes associated with nature of science (NOS) instruction along a science-content context continuum on the development of secondary preservice science teachers' conceptions of and plans to teach NOS, moving beyond the common dichotomy of contextualized versus noncontextualized instruction. Participants comprised six teacher cohorts (n = 70) enrolled in a two-year Master of Teaching program. Participants were explicitly taught current NOS conceptions using activities that incorporated varied degrees of contextualization and were informed by conceptual change principles during the first program year. Participants' pre- and post-instruction conceptions were assessed using VNOS-C questionnaire written responses and follow-up interviews. Participants' views were classified by degree of alignment (non, partially, or fully aligned) with current NOS conceptions. Interview transcripts were analyzed using analytic induction to verify/refine VNOS responses and to identify patterns in NOS instructional plans and rationales. Wilcoxon signed ranks tests were run to assess possible statistical significance of pre- to post-instruction changes. Participants' responses shifted markedly toward more aligned NOS conceptions post-instruction, with substantial and statistically significant gains for each assessed tenet (all p-values <.001). All participants planned future NOS instruction and most expressed a sophisticated rationale for this choice, including that NOS supported the teaching of key concepts such as evolution. These results indicate that teaching and scaffolding NOS lessons along a context continuum can be effective in eliciting desired changes in preservice teachers' NOS conceptions and instructional intentions within the confines of the science methods course. Future research will examine post-methods course and post-program NOS instruction.

  5. Photoproduction of hydrated electrons from natural organic solutes in aquatic environments

    USGS Publications Warehouse

    Zepp, R.G.; Braun, A.M.; Hoigne, J.; Leenheer, J.A.

    1987-01-01

    Laser flash photolysis was used to investigate the transients formed on absorption of 355-nm light by dissolved organic matter (DOM) from natural water bodies and from soil. Absorption spectra and quenching studies of the transients provided confirming evidence that hydrated electrons were formed by all of the DOM that were studied. The DOM from the Suwannee River in Georgia and from the Greifensee, a Swiss lake, exhibited great variability in light-absorbing properties. Despite this high variability in absorption coefficients, the primary quantum yields for electron ejection from the Greifensee and Suwannee DOM fell in a narrow range (0.005-0.008). Steady-state irradiations (355 nm) of the DOM with 2-chloroethanol (0.02 M) present as an electron scavenger produced chloride ions with quantum yields that were about 2 orders of magnitude lower than the primary quantum yields. This result indicates that most of the photoejected electrons recombine with cations before escaping into bulk solution. Irradiations of DOM solutions under sunlight (April, latitude 34?? N) photoproduced electrons at rates falling in the range of 0.2-0.4 ??mol/[(mg of DOC) h]. These results indicate that hydrated electrons can play a significant role in the environmental photoreduction of persistent, electronegative pollutants but may be relatively unimportant in the environmental production of hydrogen peroxide. ?? 1987 American Chemical Society.

  6. Ammonium removal from aqueous solutions by using natural Chinese (Chende) zeolite as adsorbent.

    PubMed

    Huang, Haiming; Xiao, Xianming; Yan, Bo; Yang, Liping

    2010-03-15

    This paper presents a study of the removal of ammonium ion from aqueous solutions using natural Chinese (Chende) zeolite. A series of experiments was conducted to examine the effects of solution pH, particle size, contact time, adsorbent dosage, and the presence of other cation- and anion species on ammonium removal. The findings indicated that these parameters named had a significant effect on the removal of ammonium by the zeolite. The effect of other cations on the removal of ammonium followed the order of preference Na(+)>K(+)>Ca(2+)>Mg(2+) at identical mass concentrations, and the effect of the presence of individual anions followed the order of preference carbonate>chloride>sulfate>phosphate at identical mass concentrations of ammonium ions. Kinetic analysis showed that the adsorption of ammonium on zeolite at different ranges of particle size well followed the pseudo-second-order model and followed the intra-particle diffusion model only during the initial 60 min of the adsorption process. Equilibrium isotherm data was fitted to the linear Langmuir- and Freundlich models with the latter model providing the better description of the process (R(2)=0.991-0.997) compared to the former (R(2)=0.902-0.989).

  7. Soil engineering in vivo: harnessing natural biogeochemical systems for sustainable, multi-functional engineering solutions.

    PubMed

    DeJong, Jason T; Soga, Kenichi; Banwart, Steven A; Whalley, W Richard; Ginn, Timothy R; Nelson, Douglas C; Mortensen, Brina M; Martinez, Brian C; Barkouki, Tammer

    2011-01-06

    Carbon sequestration, infrastructure rehabilitation, brownfields clean-up, hazardous waste disposal, water resources protection and global warming-these twenty-first century challenges can neither be solved by the high-energy consumptive practices that hallmark industry today, nor by minor tweaking or optimization of these processes. A more radical, holistic approach is required to develop the sustainable solutions society needs. Most of the above challenges occur within, are supported on, are enabled by or grown from soil. Soil, contrary to conventional civil engineering thought, is a living system host to multiple simultaneous processes. It is proposed herein that 'soil engineering in vivo', wherein the natural capacity of soil as a living ecosystem is used to provide multiple solutions simultaneously, may provide new, innovative, sustainable solutions to some of these great challenges of the twenty-first century. This requires a multi-disciplinary perspective that embraces the science of biology, chemistry and physics and applies this knowledge to provide multi-functional civil and environmental engineering designs for the soil environment. For example, can native soil bacterial species moderate the carbonate cycle in soils to simultaneously solidify liquefiable soil, immobilize reactive heavy metals and sequester carbon-effectively providing civil engineering functionality while clarifying the ground water and removing carbon from the atmosphere? Exploration of these ideas has begun in earnest in recent years. This paper explores the potential, challenges and opportunities of this new field, and highlights one biogeochemical function of soil that has shown promise and is developing rapidly as a new technology. The example is used to propose a generalized approach in which the potential of this new field can be fully realized.

  8. Surface features and alteration products of natural zirconolite leached in silica-saturated solutions

    SciTech Connect

    Helean, K.B.; Lutze, W.; Ewing, R.C.

    1999-07-01

    Zirconolite, CaZrTi{sub 2}P{sub 7}, has been proposed as an immobilization phase for the disposition of excess weapons Pu and other actinides (e.g., {sup 235}U). Due to actinide incorporation, zirconolite is expected to sustain {alpha}-decay event damage and become aperiodic (=metamict) over time. The leaching behavior of metamict zirconolite is, therefore, of interest. Because groundwater in a variety of geologic settings contains up to saturation concentrations of silicic acid, H{sub 4}SiO{sub 4}, silica-saturated solutions were used. Natural, metamict (>10{sup 26} {alpha}-decay events per m{sup 3}) zirconolite grains, nominally (Ca,Th)ZrTi{sub 2}O{sub 7} (US National Museum sample No. B20392, Walawada, Sri Lanka) were leached in two separate silica-saturated solutions at 150 C for 60 days. Surface features and alteration products were examined using scanning electron microscopy (SEM) and quantitative energy dispersive X-ray spectroscopy (EDS). Secondary electron (SEI) images of the surfaces of the leached grains from both experiments revealed pores, probably due to the accumulation of He-bubbles from {alpha}-decay events, of approximately 4% as estimated by contrast enhanced gray-scale analysis of digital images. SEI of the zirconolite surface before leaching showed a smooth surface. The pores not only increase the surface area of the metamict zirconolite, but also act as nucleation sites for alteration phase growth. One experiment was conducted in a silica-saturated solution containing approximately 100 ppm P as measured by atomic absorption spectroscopy (AAS). The main alteration phase was euhedral, monoclinic cheralite, (Th,Ca,Ce)(P,Si)O{sub 4} (monazite group). The second experiment was conducted in the absence of P. The main alteration phase was subhedral cubic thorianite, ThO{sub 2}.

  9. Soil engineering in vivo: harnessing natural biogeochemical systems for sustainable, multi-functional engineering solutions

    PubMed Central

    DeJong, Jason T.; Soga, Kenichi; Banwart, Steven A.; Whalley, W. Richard; Ginn, Timothy R.; Nelson, Douglas C.; Mortensen, Brina M.; Martinez, Brian C.; Barkouki, Tammer

    2011-01-01

    Carbon sequestration, infrastructure rehabilitation, brownfields clean-up, hazardous waste disposal, water resources protection and global warming—these twenty-first century challenges can neither be solved by the high-energy consumptive practices that hallmark industry today, nor by minor tweaking or optimization of these processes. A more radical, holistic approach is required to develop the sustainable solutions society needs. Most of the above challenges occur within, are supported on, are enabled by or grown from soil. Soil, contrary to conventional civil engineering thought, is a living system host to multiple simultaneous processes. It is proposed herein that ‘soil engineering in vivo’, wherein the natural capacity of soil as a living ecosystem is used to provide multiple solutions simultaneously, may provide new, innovative, sustainable solutions to some of these great challenges of the twenty-first century. This requires a multi-disciplinary perspective that embraces the science of biology, chemistry and physics and applies this knowledge to provide multi-functional civil and environmental engineering designs for the soil environment. For example, can native soil bacterial species moderate the carbonate cycle in soils to simultaneously solidify liquefiable soil, immobilize reactive heavy metals and sequester carbon—effectively providing civil engineering functionality while clarifying the ground water and removing carbon from the atmosphere? Exploration of these ideas has begun in earnest in recent years. This paper explores the potential, challenges and opportunities of this new field, and highlights one biogeochemical function of soil that has shown promise and is developing rapidly as a new technology. The example is used to propose a generalized approach in which the potential of this new field can be fully realized. PMID:20829246

  10. Problem Definition and Solution Concept for En Route Constrained Airspace Problems

    NASA Technical Reports Server (NTRS)

    Green, Steven; Vivona, Robert

    2000-01-01

    NASA's AATT Program is investigating potential ground-based decision support tool (DST) development for en route controllers and managers. NASA's previous work in en route DST development has focused on Transition airspace, where aircraft are impacted by constraints associated with the transition of aircraft from en route to terminal airspace. This paper investigates the problems associated with aircraft in non-transitional en route airspace, termed Constrained Airspace. A literature search was performed to catalog previously identified constrained airspace problems. The results of this search were investigated with industry representatives to validate these problems were significant in constrained airspace. Three general problem areas were identified. The first problem area involves negative impacts caused by a loss of airspace (e.g., activation of Special Use Airspace (SUA), weather cell formation, and overloaded sectors). The second problem area is the lack of identifying and taking advantage of gained airspace (e.g., SUA deactivation, weather dissipation, and sector loading reductions). The third problem area is unforeseen negative impacts caused by the acceptance of user routing requests (e.g., a route change into an area of congestion that negated the users intended benefit). Based upon the problems identified, an operational concept was developed for a DST to help handle these problems efficiently. The goal is to strategically identify constrained airspace problems and to provide functionality to support ARTCC TMUs in resolving the identified impacts. The capability lends itself well to TMU and Airline Operations Center (AOC) collaboration.

  11. Concepts of Nature and Power: Environmental Ethics of the Northern Ute.

    ERIC Educational Resources Information Center

    Romeo, Stephanie

    1985-01-01

    Describes the approach to resource development of the Northern Ute tribe of Utah. This model preserves the traditional way of life, increases revenues, and minimizes environmental damage. The Ute's historical background and ideology of nature are discussed as well as their fundamental beliefs and moral imperatives associated with natural elements.…

  12. Influence of Teachers' Conceptions of the Nature of Science on Classroom Practice

    ERIC Educational Resources Information Center

    Sarieddine, Diana; BouJaoude, Saouma

    2014-01-01

    Whether teachers' conceptions of NOS are reflected in their instructional planning and classroom practice remains an important research question. Consequently, this study investigated teachers' NOS views and their relationship to their classroom practice and delineated the factors that facilitate or impede this relationship. To achieve this, seven…

  13. Using a Concept Cartoon© Method to Address Elementary School Students' Ideas about Natural Phenomena

    ERIC Educational Resources Information Center

    Minárechová, Michaela

    2016-01-01

    This study investigated the identification and subsequent development or modification of students´ ideas about scientific phenomena by teaching by concept cartoons© method. We found out ideas of students of the fourth grade of primary school by conceptual tasks which were parts of quasi-experiment (pretest and posttest design). For triangulation…

  14. Meaning Making: What Reflective Essays Reveal about Biology Students' Conceptions about Natural Selection

    ERIC Educational Resources Information Center

    Balgopal, Meena M.; Montplaisir, Lisa M.

    2011-01-01

    The process of reflective writing can play a central role in making meaning as learners process new information and connect it to prior knowledge. An examination of the written discourse can therefore be revealing of learners' cognitive understanding and affective (beliefs, feelings, motivation to learn) responses to concepts. Despite reflective…

  15. The Development of an Instrument to Evaluate Teachers' Concepts about Nature of Mathematical Knowledge

    ERIC Educational Resources Information Center

    Kean, Lesa L. Conditt

    2012-01-01

    While there does seem to be widespread consensus that teachers' beliefs and concepts influence the way they teach, even the most recent international studies suggest that research-based evidence for this consensus is limited. In an effort to enlarge and enhance the pool of evidence that shows specific relationships between teacher beliefs and…

  16. A Comparison of Applied and Theoretical Knowledge of Concepts Based on the Particulate Nature of Matter.

    ERIC Educational Resources Information Center

    Haidar, Abdullateef H.; Abraham, Michael R.

    1991-01-01

    High school chemistry students' (n=183) applied and theoretical knowledge of dissolution, diffusion, effusion, and states of matter were compared. Study found that students' formal reasoning ability and their preexisting knowledge are associated with their conceptions and use of particulate theory. A significant difference between applied and…

  17. The Nature of Living Systems: An Exposition of the Basic Concepts in General Systems Theory.

    ERIC Educational Resources Information Center

    Miller, James G.

    General systems theory is a set of related definitions, assumptions, and propositions which deal with reality as an integrated hierarchy of organizations of matter and energy. In this paper, the author defines the concepts of space, time, matter, energy, and information in terms of their meaning in general systems theory. He defines a system as a…

  18. Influence of Teachers' Conceptions of the Nature of Science on Classroom Practice

    ERIC Educational Resources Information Center

    Sarieddine, Diana; BouJaoude, Saouma

    2014-01-01

    Whether teachers' conceptions of NOS are reflected in their instructional planning and classroom practice remains an important research question. Consequently, this study investigated teachers' NOS views and their relationship to their classroom practice and delineated the factors that facilitate or impede this relationship. To achieve this, seven…

  19. Ammonium exchange in aqueous solution using Chinese natural clinoptilolite and modified zeolite.

    PubMed

    Wang, Y-F; Lin, F; Pang, W-Q

    2007-04-02

    In this study, the Chinese natural clinoptilolite (sample 1) was fused with sodium hydroxide prior to hydrothermal reaction, and it was transformed to modified zeolite Na-Y (sample 2). The uptake of ammonium ion from aqueous solutions in the concentration range 50-250 mg NH(4)(+)/l on to the two samples was compared and the equilibrium isotherms have been got. The influence of other cations present in water upon the ammonia uptake was also determined. The cations studied were potassium, calcium and magnesium. In all cases the anionic counterion present was chloride. The results showed that sample 2 exhibited much higher uptake capacity compared with sample 1. At the initial concentration of 250 mg NH(4)(+)/l, the ammonium ion uptake value of sample 2 was 19.29 mg NH(4)(+)g(-1) adsorbent, while sample 1 was only 10.49 mg NH(4)(+)g(-1) adsorbent. For the natural clinoptilolite, the effect of the metal ions suggested an order of preference K(+)>Ca(2+)>Mg(2+). These contrasted with the modified zeolite, where the order appeared to be Mg(2+)>Ca(2+)>K(+).

  20. Photosensitized degradation of acetaminophen in natural organic matter solutions: The role of triplet states and oxygen.

    PubMed

    Li, Yanyun; Pan, Yanheng; Lian, Lushi; Yan, Shuwen; Song, Weihua; Yang, Xin

    2017-02-01

    The photolysis of acetaminophen, a widely used pharmaceutical, in simulated natural organic matter solutions was investigated. The triplet states of natural organic matter ((3)NOM*) were found to play the dominant role in its photodegradation, while the contributions from hydroxyl radicals and singlet oxygen were negligible. Dissolved oxygen (DO) plays a dual role. From anaerobic to microaerobic (0.5 mg/L DO) conditions, the degradation rate of acetaminophen increased by 4-fold. That suggests the involvement of DO in reactions with the degradation intermediates. With increasing oxygen levels to saturated conditions (26 mg/L DO), the degradation rate became slower, mainly due to DO's quenching effect on (3)NOM*. Superoxide radical (O2(-)) did not react with acetaminophen directly, but possibly quenched the intermediates to reverse the degradation process. The main photochemical pathways were shown to involve phenoxyl radical and N-radical cations, finally yielding hydroxylated derivatives, dimers and nitrosophenol. A reaction mechanism involving (3)NOM*, oxygen and O2(-) is proposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Cell-Mediated Immunity to AAV Vectors, Evolving Concepts and Potential Solutions.

    PubMed

    Basner-Tschakarjan, Etiena; Mingozzi, Federico

    2014-01-01

    Adeno-associated virus (AAV) vectors are one of the most efficient in vivo gene delivery platforms. Over the past decade, clinical trials of AAV vector-mediated gene transfer led to some of the most exciting results in the field of gene therapy and, recently, to the market approval of an AAV-based drug in Europe. With clinical development, however, it became obvious that the host immune system represents an important obstacle to successful gene transfer with AAV vectors. In this review article, we will discuss the issue of cytotoxic T cell responses directed against the AAV capsid encountered on human studies. While over the past several years the field has acquired a tremendous amount of information on the interactions of AAV vectors with the immune system, a lot of questions are still unanswered. Novel concepts are emerging, such as the relationship between the total capsid dose and the T cell-mediated clearance of transduced cells, the potential role of innate immunity in vector immunogenicity highlighted in preclinical studies, and the cross talk between regulatory and effector T cells in the determination of the outcome of gene transfer. There is still a lot to learn about immune responses in AAV gene transfer, for example, it is not well understood what are the determinants of the kinetics of activation of T cells in response to vector administration, why not all subjects develop detrimental T cell responses following gene transfer, and whether the intervention strategies currently in use to block T cell-mediated clearance of transduced cells will be safe and effective for all gene therapy indications. Results from novel preclinical models and clinical studies will help to address these points and to reach the important goal of developing safe and effective gene therapy protocols to treat human diseases.

  2. Developing an Evidence-Based Epilepsy Risk Assessment eHealth Solution: From Concept to Market.

    PubMed

    Newman, Craig; Shankar, Rohit; Hanna, Jane; McLean, Brendan; Osland, Alex; Milligan, Cathryn; Ball, Abbie; Jory, Caryn; Walker, Matthew

    2016-06-07

    Sudden unexpected death in epilepsy (SUDEP) is possibly the most common cause of death as a result of complications from epilepsy. The need to educate and regularly review risk for all patients with epilepsy is paramount, but rarely delivered in actual clinical practice. Evidence suggests that education around SUDEP and modifiable risk variables translate into better self-management of epilepsy. We aimed to develop and implement an eHealth solution to support education and self-management of risks, in epilepsy. We undertook an innovation pathways approach, including problem identification, feasibility assessment, design, implementation, and marketing. People with epilepsy were provided a smartphone-based app (Epilepsy Self-Monitor, EpSMon), which translates the clinical risk assessment tool into an educational and self-monitoring platform, for the self-management of epilepsy. Results include the success of the marketing campaign, and in what areas, with an estimated reach of approximately 38 million people. EpSMon has proved a success in academic and clinical circles, attracting awards and nominations for awards. The number of users of EpSMon, after 3 months, turned out to be lower than expected (N=221). A 4-month trial of the app in use in the United Kingdom, and the success of the marketing strategy, point to necessary changes to the model of delivery and marketing, summarized in this paper. These include the marketing message, user cost model, and need for the availability of an Android version. EpSMon has proven a success in respect to its reception by academics, clinicians, stakeholder groups, and the patients who use it. There is work needed to promote the model and increase its acceptability/attractiveness, including broadening the marketing message, increasing its availability, and reducing its cost. Future development and promotion of the tool will hopefully inform iterative design of its core features for a receptive audience and lead to increased uptake

  3. Student Knowledge of Scientific and Natural Resource Concepts Concerning Acidic Deposition.

    ERIC Educational Resources Information Center

    Brody, Michael; And Others

    1989-01-01

    Assessed is the level of scientific and natural resource knowledge possessed by fourth-, eighth- and eleventh-grade students. Misconceptions are noted. Discussed are implications for teaching about acidic deposition. (CW)

  4. Assessing explicit and tacit conceptions of the nature of science among preservice elementary teachers

    NASA Astrophysics Data System (ADS)

    Craven, John A., III; Hand, Brian; Prain, Vaughan

    2002-08-01

    This paper reports on the processes and outcomes of practices in a preservice, elementary science methods course designed to: (1) fathom existing student perceptions of the nature of science and (2) move students from holding individually constructed, typically limited views on the nature of science towards more rich, publicly negotiated views. In the course of 15 weeks, 27 preservice elementary students engaged in a series of individual and collaborative exercises that required them to explore their tacit and explicit knowledge about the nature of science. The data were analysed using the interpretative-descriptive approach. Analyses revealed notable, positive changes in the language students used to describe both the nature and structure of the scientific enterprise. The findings of this study support continued efforts in the search for ways of understanding and affecting the views of science that preservice elementary teachers typically hold.

  5. Developing an Evidence-Based Epilepsy Risk Assessment eHealth Solution: From Concept to Market

    PubMed Central

    Shankar, Rohit; Hanna, Jane; McLean, Brendan; Osland, Alex; Milligan, Cathryn; Ball, Abbie; Jory, Caryn; Walker, Matthew

    2016-01-01

    Introduction Sudden unexpected death in epilepsy (SUDEP) is possibly the most common cause of death as a result of complications from epilepsy. The need to educate and regularly review risk for all patients with epilepsy is paramount, but rarely delivered in actual clinical practice. Evidence suggests that education around SUDEP and modifiable risk variables translate into better self-management of epilepsy. Objective We aimed to develop and implement an eHealth solution to support education and self-management of risks, in epilepsy. Methods We undertook an innovation pathways approach, including problem identification, feasibility assessment, design, implementation, and marketing. People with epilepsy were provided a smartphone-based app (Epilepsy Self-Monitor, EpSMon), which translates the clinical risk assessment tool into an educational and self-monitoring platform, for the self-management of epilepsy. Results Results include the success of the marketing campaign, and in what areas, with an estimated reach of approximately 38 million people. EpSMon has proved a success in academic and clinical circles, attracting awards and nominations for awards. The number of users of EpSMon, after 3 months, turned out to be lower than expected (N=221). A 4-month trial of the app in use in the United Kingdom, and the success of the marketing strategy, point to necessary changes to the model of delivery and marketing, summarized in this paper. These include the marketing message, user cost model, and need for the availability of an Android version. Conclusions EpSMon has proven a success in respect to its reception by academics, clinicians, stakeholder groups, and the patients who use it. There is work needed to promote the model and increase its acceptability/attractiveness, including broadening the marketing message, increasing its availability, and reducing its cost. Future development and promotion of the tool will hopefully inform iterative design of its core features for

  6. Regulating urban surface runoff through nature-based solutions - An assessment at the micro-scale.

    PubMed

    Zölch, Teresa; Henze, Lisa; Keilholz, Patrick; Pauleit, Stephan

    2017-08-01

    Urban development leads to changes of surface cover that disrupt the hydrological cycle in cities. In particular, impermeable surfaces and the removal of vegetation reduce the ability to intercept, store and infiltrate rainwater. Consequently, the volume of stormwater runoff and the risk of local flooding rises. This is further amplified by the anticipated effects of climate change leading to an increased frequency and intensity of heavy rain events. Hence, urban adaptation strategies are required to mitigate those impacts. A nature-based solution, more and more promoted in politics and academia, is urban green infrastructure as it contributes to the resilience of urban ecosystems by providing services to maintain or restore hydrological functions. However, this poses a challenge to urban planners in deciding upon effective adaptation measures as they often lack information on the performance of green infrastructure to moderate surface runoff. It remains unclear what type of green infrastructure (e.g. trees, green roofs), offers the highest potential to reduce discharge volumes and to what extent. Against this background, this study provides an approach to gather quantitative evidence on green infrastructure's regulation potential. We use a micro-scale scenario modelling approach of different variations of green cover under current and future climatic conditions. The scenarios are modelled with MIKE SHE, an integrated hydrological simulation tool, and applied to a high density residential area of perimeter blocks in Munich, Germany. The results reveal that both trees and green roofs increase water storage capacities and hence reduce surface runoff, although the main contribution of trees lies in increasing interception and evapotranspiration, whereas green roofs allow for more retention through water storage in their substrate. With increasing precipitation intensities as projected under climate change their regulating potential decreases due to limited water

  7. A study of elementary teachers' conceptions of nature of science and their beliefs about the developmental appropriateness and importance of nature of science throughout a professional development program

    NASA Astrophysics Data System (ADS)

    Adibelli, Elif

    This qualitative study aimed to explore the changes in elementary science teachers' conceptions of nature of science (NOS) and their beliefs about the developmental appropriateness and importance of NOS after participating in an academic, year-long professional development program (PDP) as well as the factors facilitating these changes. The PDP consisted of two phases. In the first phase, the participants received NOS training designed with an explicit-reflective instructional approach. In the second phase, the participants implemented several NOS training activities in their classrooms. Four elementary science teachers who volunteered and completed all components of the PDP (i.e., the NOS training and the NOS teaching) comprised the participants of the present study. A multiple-embedded case study design was employed to explore the changes in the elementary science teachers' conceptions of NOS and their beliefs about the developmental appropriateness and importance of NOS. The study data were collected from multiple sources. The primary data sources included (a) Views of Nature of Science Elementary School Version 2 (VNOS-D2) questionnaire (Lederman & Khishfe, 2002), (b) Ideas about Science for Early Elementary (K-4) Students questionnaire (Sweeney, 2010), and (c) follow-up semi-structured interviews. The secondary data sources included videotaping of meetings with teachers, reflective field notes, and artifacts produced by teachers and their students. Data were analyzed using Yin's (1994, 2003) analytic tactics of pattern matching, explanation building, and cross-case synthesis. The findings of the study revealed that the elementary science teachers showed gradual, but substantial changes in their conceptions, and beliefs about the developmental appropriateness and importance of the NOS aspects over the course of participation in the PDP. Moreover, the participants identified nine components in the PDP that facilitated these changes in their conceptions, and

  8. Nature of science conceptions, attitudes towards evolution and global climate change, and course achievement in an introductory biology course

    NASA Astrophysics Data System (ADS)

    Carter, Benjamin Elijah

    Many researchers have studied student attitudes toward and knowledge of evolutionary science, attitudes towards global climate change (GCC), conceptions about the nature of science (NOS), and course success. However, at the time of this writing, no studies explicitly link these topics. It is overwhelmingly acknowledged by the scientific community that evolution and global climate change (GCC) are undeniably supported by physical evidence. And yet, both topics remain very politically contentious in the United States. Efforts to mitigate the disconnects between the scientific community and the general public on these issues are imperative to science education. Such undertakings need to examine students' conceptions of the nature of science (NOS), how evidence is treated, how theories are constructed, and how scientific consensus is reached, as these may be key factors in acceptance of evolution and GCC. If students have a more thorough understanding of the weight behind scientific consensus and better tools to discern scientific versus non-scientific arguments, they may become more likely to accept strongly supported scientific ideas. Our study explored this hypothesis guided by the following questions: Do changes in NOS conceptions correlate with changes in attitudes towards evolution or GCC? If there are correlations, are they similar for evolution and GCC? What demographic factors affect these correlations? Further, we asked whether attitudes towards evolution before the course began was a significant predictor of achievement in the course. Previously-developed tools were used to measure students' conceptions of the nature of science and attitudes towards evolution, while national public opinion poll questions were used to measure attitudes towards GCC. Demographic questions were produced to target factors thought to influence attitudes towards evolution or global climate change. Overall sample size was N=620. Principle Components Analysis was used to determine

  9. Adsorption of sulfur dioxide on natural clinoptilolite chemically modified with salt solutions.

    PubMed

    Ivanova, Emilia; Koumanova, Bogdana

    2009-08-15

    Various ion exchange forms of preliminary partly decationised zeolite (hydrogen forms) were obtained by indirect modification with metal salt solutions, as well as by direct treatment of natural clinoptilolite taken from Bulgarian deposits. Direct modification leads to a higher extent of samples enrichment with corresponding ion. Independently of the conditions, the alkaline and alkaline earth metal ions (especially sodium and calcium) were inserted at a greater extent, while the transitional metals-at a comparatively lower extent. The cationic forms of clinoptilolite were used for adsorption and desorption experiments. The breakthrough adsorption curves and the concentration curves at temperature-programmed desorption were obtained and compared. The breakthrough and saturation times, the adsorption capacity, the distribution coefficient, the adsorbed SO(2), the portions desorbed as SO(2) and SO(3), respectively, as well as the not desorbed portion of SO(2), were determined using these curves. It was established that a definite quantity of undesorbed SO(2) has remained in the zeolite forms modified with transitional metal cations. This statement was proved not only by the comparison between the adsorbed and desorbed quantities, but also by three-cycle adsorption-desorption experiments for the Cu(2+)-form. The results demonstrate a decrease in the capacity for each following cycle in an extent similar to the undesorbed SO(2) quantity. It was not observed a visible difference in the values of the distribution coefficients for adsorption on identical cation forms, directly or indirectly obtained. However, the breakthrough time of the samples obtained by ion exchange of the hydrogen form was longer in all cases. Definite quantities of desorbed SO(3) were registered for all forms, except for the natural clinoptilolite and the samples enriched with alkaline and alkaline earth metal cations.

  10. Application of natural resource valuation concepts for development of sustainable remediation plans for groundwater.

    PubMed

    Connor, John A; Paquette, Shawn; McHugh, Thomas; Gie, Elaine; Hemingway, Mark; Bianchi, Gino

    2017-04-07

    This paper explores the application of natural resource assessment and valuation procedures as a tool for developing groundwater remediation strategies that achieve the objectives for health and environmental protection, in balance with considerations of economic viability and conservation of natural resources. The natural resource assessment process, as applied under U.S. and international guidelines, entails characterization of groundwater contamination in terms of the pre-existing beneficial services of the impacted resource, the loss of these services caused by the contamination, and the measures and associated costs necessary to restore or replace the lost services. Under many regulatory programs, groundwater remediation objectives assume that the impacted groundwater may be used as a primary source of drinking water in the future, even if not presently in use. In combination with a regulatory preference for removal or treatment technologies, this assumed exposure, while protective of human health, can drive the remedy selection process toward remedies that may not be protective of the groundwater resource itself or of the other natural resources (energy, materials, chemicals, etc.) that may be consumed in the remediation effort. To achieve the same health and environmental protection goals under a sustainable remediation framework, natural resource assessment methods can be applied to restore the lost services and preserve the intact services of the groundwater so as to protect both current and future users of that resource. In this paper, we provide practical guidelines for use of natural resource assessment procedures in the remedy selection process and present a case study demonstrating the use of these protocols for development of sustainable remediation strategies. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  11. Suppressing Synonymy with a Homonym: The Emergence of the Nomenclatural Type Concept in Nineteenth Century Natural History.

    PubMed

    Witteveen, Joeri

    2016-02-01

    'Type' in biology is a polysemous term. In a landmark article, Paul Farber (Journal of the History of Biology 9(1): 93-119, 1976) argued that this deceptively plain term had acquired three different meanings in early nineteenth century natural history alone. 'Type' was used in relation to three distinct type concepts, each of them associated with a different set of practices. Important as Farber's analysis has been for the historiography of natural history, his account conceals an important dimension of early nineteenth century 'type talk.' Farber's taxonomy of type concepts passes over the fact that certain uses of 'type' began to take on a new meaning in this period. At the closing of the eighteenth century, terms like 'type specimen,' 'type species,' and 'type genus' were universally recognized as referring to typical, model members of their encompassing taxa. But in the course of the nineteenth century, the same terms were co-opted for a different purpose. As part of an effort to drive out nomenclatural synonymy - the confusing state of a taxon being known to different people by different names - these terms started to signify the fixed and potentially atypical name-bearing elements of taxa. A new type concept was born: the nomenclatural type. In this article, I retrace this perplexing nineteenth century shift in meaning of 'type.' I uncover the nomenclatural disorder that the new nomenclatural type concept dissolved, and expose the conceptual confusion it left in its tracks. What emerges is an account of how synonymy was suppressed through the coinage of a homonym.

  12. Characterization of the hydraulics at natural step crests in step-pool streams via weir flow concepts

    NASA Astrophysics Data System (ADS)

    Dust, David; Wohl, Ellen

    2012-09-01

    The hydraulics of step-pool streams are characterized by rapidly varied flow at the step crest, a hydraulic jump, and gradually varied flow in the pool unit of the step-pool sequence. The flow characteristics at the step crests act as the hydraulic control for the water surface profile within the upstream pool unit. Using both field and flume investigations, we demonstrate the use of weir flow concepts for assessing and categorizing the hydraulic characteristics of natural step-crests in step-pool streams. We categorize the results of our investigations in terms of the crest-clast, planform, longitudinal, and instream wood geometries of the step crests. The broad-crested weir equation can be expressed asQ = C* g0.5Wh3/2, where Q is the flowrate, C* is a dimensionless discharge coefficient, W is the crest width, g is the acceleration of gravity, and h is the upstream flow depth above the step crest. Although the flow over a natural step is generally more complex than for an engineered weir, the results of our investigations indicate that the C*-value for simulated and natural steps increases linearly as a function of the upstream head (h), with C* values ranging from 0.15 to 0.97. As a result, the application of weir flow concepts to natural steps provides means for (1) indirectly estimating flow rates; (2) characterizing the hydraulics for individual steps; (3) defining external and/or internal boundary conditions at step crests for hydraulic model simulations of natural or restored step-pool streams; and (4) estimating the upstream pressure force acting on step-crest clasts.

  13. Investigating inquiry beliefs and nature of science (NOS) conceptions of science teachers as revealed through online learning

    NASA Astrophysics Data System (ADS)

    Atar, Hakan Yavuz

    teachers NOS conceptions. Developing desired understanding of nature of science conceptions and having an adequate experience with inquiry learning is especially important for science teachers because science education literature suggests that the development of teachers' nature of science conceptions is influenced by their experiences with inquiry science (Akerson et. al. 2000) and implementation of science lessons reflect teachers' NOS conceptions (Abd-EL-Khalick & Boujaoude, 1997; Matson & Parsons, 1998; Rosenthal, 1993; Trowbridge, Bybee & Powell, 2000; Turner & Sullenger, 1999). Furthermore, the impediments to successful integration of inquiry based science instruction from teachers' perspective are particularly important, as they are the implementers of inquiry based science education reform. The purpose of this study is to understand the relationship between the teachers' NOS conceptions and their inquiry beliefs and practices in their classrooms and how this relationship impedes or contributes to the implementation of inquiry based science education reform efforts. The participants of this study were in-service teachers who were accepted into the online Masters Program in science education program at a southern university. Three online courses offered in the summer semester of 2005 constituted the research setting of this study: (1) Special Problems in the Teaching of Secondary School Science: Nature of Science & Science Teaching, (2) Curriculum in Science Education, and (3) Colloquium. Multiple data sources were used for data triangulation (Miles & Huberman, 1984; Yin, 1994) in order to understand the relationship between participants' NOS views and their conceptions and beliefs about inquiry-based science teaching. The study revealed that the relationship between the teachers' NOS conceptions and their inquiry beliefs and practices is far from being simple and linear. Data suggests that the teachers' sophistication of NOS conceptions influence their perception of

  14. The Effectiveness of Conceptual Change Texts and Concept Clipboards in Learning the Nature of Science

    ERIC Educational Resources Information Center

    Çil, Emine; Çepni, Salih

    2016-01-01

    Background: One of the most important goals of science education is to enable students to understand the nature of science (NOS). However, generally regular science teaching in classrooms does not help students improve informed NOS views. Purpose: This study investigated the influence of an explicit reflective conceptual change approach compared…

  15. Student Conceptions of Natural Selection and Its Role in Evolution, Research Series No. l65.

    ERIC Educational Resources Information Center

    Bishop, Beth A.; Anderson, Charles W.

    Pretests and posttests on the topic of evolution through natural selection were administered to students in a college nonmajors' biology course. Analysis of test responses revealed that most students understood evolution as a process in which species respond to environmental conditions by changing gradually over time. Student thinking differed…

  16. Political Nature and Socio-Professional Determinants of the Concept of Quality

    ERIC Educational Resources Information Center

    Olaskoaga-Larrauri, Jon; González-Laskibar, Xabier; Barrenetxea-Ayesta, Miren

    2015-01-01

    This paper is based on the hypothesis that the notions of teaching quality used in the higher education sector have a political nature; in other words, they may describe the approaches agents take as regards the duties they perform in institutions of higher education or the model of governance those institutions should adopt. This paper uses the…

  17. Political Nature and Socio-Professional Determinants of the Concept of Quality

    ERIC Educational Resources Information Center

    Olaskoaga-Larrauri, Jon; González-Laskibar, Xabier; Barrenetxea-Ayesta, Miren

    2015-01-01

    This paper is based on the hypothesis that the notions of teaching quality used in the higher education sector have a political nature; in other words, they may describe the approaches agents take as regards the duties they perform in institutions of higher education or the model of governance those institutions should adopt. This paper uses the…

  18. Pre-Service and In-Service Science Teachers' Conceptions of the Nature of Science

    ERIC Educational Resources Information Center

    Buaraphan, Khajornsak

    2010-01-01

    The author explores the history of nature of science beliefs among pre-service and in-service teachers primarily in the United States and Thailand and compares this history to findings in a current study being conducted in Thailand. Two research questions were used to guide this current study: What are pre-service and in-service science teachers'…

  19. Undergraduate Students' Conceptions of Natural and Anthropogenic Climate Change: A Case Study Approach

    ERIC Educational Resources Information Center

    Trenbath, Thien-Kim Leckie

    2012-01-01

    This dissertation shows the evolution of five undergraduate students' ideas of natural and anthropogenic climate change throughout a lecture hall course on climate change. This research was informed by conceptual change theory and students' inaccurate ideas of climate change. Subjects represented different levels of climate change understanding at…

  20. "Place" as an integrating concept in natural resource politics: propositions for a social science research agenda.

    Treesearch

    Antony S. Cheng; Linda E. Kruger; Steven E. Daniels

    2003-01-01

    This article lays out six propositions centering on a relationship between peopleplace connections and strategic behavior in natural resource politics. The first two propositions suggest a strong and direct connection between self-identity, place, and how individuals perceive and value the environment. The third, fourth, and fifth propositions tie together social group...

  1. Exploring the Conceptions of a Science Teacher from Karachi about the Nature of Science

    ERIC Educational Resources Information Center

    Shah, Mir Zaman

    2009-01-01

    The main purpose of this study is to investigate a science teacher's beliefs and understanding of the nature of science (NOS) in order to be able to relate these beliefs about the NOS to classroom practice and therefore student experience. Teachers' beliefs about the NOS are embedded in their experiences of learning and teaching science and hence,…

  2. Students' Conceptions of the Particulate Nature of Matter at Secondary and Tertiary Level

    ERIC Educational Resources Information Center

    Ayas, Alipasa; Ozmen, Haluk; Calik, Muammer

    2010-01-01

    The aim of the present study is to elicit students' understanding of the particulate nature of matter via a cross-age study ranging from secondary to tertiary educational levels. A questionnaire with five-item open-ended questions was administered to 166 students from the secondary to tertiary levels of education. In light of the findings, it can…

  3. Learning Nature of Science Concepts through a Research Apprenticeship Program: A Comparative Study of Three Approaches

    ERIC Educational Resources Information Center

    Burgin, Stephen R.; Sadler, Troy D.

    2016-01-01

    The merits of three approaches (explicit, reflective and implicit) to Nature of Science (NOS) teaching and learning in the context of a summer research experience on high school student participants' NOS ideas were explored in this study. The effectiveness of explicit over implicit approaches has been demonstrated in school contexts, but less…

  4. Learning Nature of Science Concepts through a Research Apprenticeship Program: A Comparative Study of Three Approaches

    ERIC Educational Resources Information Center

    Burgin, Stephen R.; Sadler, Troy D.

    2016-01-01

    The merits of three approaches (explicit, reflective and implicit) to Nature of Science (NOS) teaching and learning in the context of a summer research experience on high school student participants' NOS ideas were explored in this study. The effectiveness of explicit over implicit approaches has been demonstrated in school contexts, but less…

  5. Undergraduate Students' Conceptions of Natural and Anthropogenic Climate Change: A Case Study Approach

    ERIC Educational Resources Information Center

    Trenbath, Thien-Kim Leckie

    2012-01-01

    This dissertation shows the evolution of five undergraduate students' ideas of natural and anthropogenic climate change throughout a lecture hall course on climate change. This research was informed by conceptual change theory and students' inaccurate ideas of climate change. Subjects represented different levels of climate change understanding at…

  6. Units of nature or processes across scales? The ecosystem concept at age 75.

    PubMed

    Currie, William S

    2011-04-01

    The ecosystem has served as a central organizational concept in ecology for nearly a half century and continues to evolve. As a level in the biotic hierarchy, ecosystems are often viewed as ecological communities integrated with their abiotic environments. This has always been imperfect because of a mismatch of scales between communities and ecosystem processes as they are made operational for field study. Complexity theory has long been forecasted to provide a renewed foundation for ecosystem theory but has been slow to do so. Partly this has arisen from a difficulty in translating theoretical tenets into operational terms for testing in field studies. Ecosystem science has become an important applied science for studying global change and human environmental impacts. Vigorous and important directions in the study of ecosystems today include a growing focus on human-dominated landscapes and development of the concept of ecosystem services for human resource supply and well-being. Today, terrestrial ecosystems are viewed less as well-defined entities or as a level in the biotic hierarchy. Instead, ecosystem processes are being increasingly viewed as the elements in a hierarchy. These occur alongside landscape processes and socioeconomic processes, which combine to form coupled social-ecological systems across a range of scales.

  7. Biological classification historical case studies: Fostering high school students' conceptions of the nature of science

    NASA Astrophysics Data System (ADS)

    Friedman, Ami J.

    The history of science has long been infused in science education. Research conducted in this area has primarily focused on physics and chemistry classes and few studies examine the effects of historical case studies on shaping female students' perspectives of the nature of science. This study aimed to examine female, high school students' conceptualizations of the nature of science while learning biological classification using historical case studies. To meet this end, this study used qualitative methods to identify and explore a female cohort's conceptualizations of the nature of science. Data collection over eight weeks included audio taped individual interviews, audio tapes of lab groups working together, field notes, artifacts, journal entries, a modified VNOS survey, and final exam essays. These data were subjected to qualitative analysis techniques. Initially, younger cohort students, compared with older cohort students, held more limited views of science, whereas the difference between younger and older cohort students dissipated by the end of the unit. Not only did the cohort express a more comprehensive view of science, but they also conceptualized various aspects of science in multiple ways indicating that grade level was not an issue when developing complex notions of the nature of science at the high school level. In addition, cohort students demonstrated a deep understanding of the nature of science by providing examples that reached beyond the biological classification unit. One lesson from the unit specifically addressed gender issues and science, allowing students to role play what was like to be a naturalist or a naturalist's wife during the Age of Discovery. This lesson provided insights into how girls conceptualize issues related to gender and science. In particular, girls viewed the perceptions, experiences, and opportunities of female scientists as being different from those of male scientists. Finally, the implications of this study were

  8. Electrochemical removal of microcystin-LR from aqueous solution in the presence of natural organic pollutants.

    PubMed

    Tran, Nam; Drogui, Patrick

    2013-01-15

    Removal of microcystin-LR (MC-LR) from water was evaluated using an electro-oxidation process. Different operating parameters were investigated, including current density, reaction time, anode material and type of supporting electrolyte. The current density and the type of anode material played an important role in the MC-LR degradation efficiency, whereas the type of sodium salts influenced the removal efficiency. The degradation of MC-LR was mainly attributed to direct anodic oxidation. The best operating conditions (98% of MC-LR removal) for MC-LR (initial concentration of 11-13 μg L(-1)) degradation in solution were obtained at a current density of 38 mA cm(-2) for 60 min with a recycling rate of 0.1 L min(-1) using a Ti/BDD anode in the presence of 0.2 g L(-1) of Na(2)SO(4). The colour caused by the presence of natural organic matter (humic acid) could be diminished by up to 81%. Likewise, MC-LR decomposition exhibited first-order reaction behaviours with a rate coefficient of 0.049 min(-1). Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. High Fluorescence Anisotropy of Thioflavin T in Aqueous Solution Resulting from Its Molecular Rotor Nature.

    PubMed

    Kuznetsova, Irina M; Sulatskaya, Anna I; Maskevich, Alexander A; Uversky, Vladimir N; Turoverov, Konstantin K

    2016-01-05

    Thioflavin T (ThT) is widely used to study amyloid fibrils while its properties are still debated in the literature. By steady-state and femtosecond time-resolved fluorescence we showed that, unlike small sized rigid molecules, the fluorescence anisotropy value of the free ThT in aqueous solutions is very high, close to the limiting value. This is determined by the molecular rotor nature of ThT, where the direction of the ThT transition dipole moment S₀ → S₁* is not changed either by the internal rotation of the ThT benzothiazole and aminobenzene rings relative to each other in the excited state, because the axis of this rotation coincides with the direction of the transition dipole moment, or by the rotation of the ThT molecule as a whole, because the rate of this process is 3 orders of magnitude smaller than the rate of the internal rotation which leads to the fluorescence quenching. Consequently, ThT fluorescence anisotropy cannot be directly used to study amyloid fibrils formation, as it was proposed by some authors.

  10. The removal of heavy metals from aqueous solution using natural Jordanian zeolite

    NASA Astrophysics Data System (ADS)

    Taamneh, Yazan; Sharadqah, Suhail

    2016-02-01

    In this article, the adsorption process of cadmium and copper using natural Jordanian (NJ) zeolite as adsorbent has been experimentally estimated. The samples of NJ zeolite were obtained from Al Mafraq discrete, north east of Jordan. The influence of the bulk concentration (C o), contact time (t) and different adsorbent masses (m) of NJ zeolite on the removal of heavy metal were evaluated. These variables had a considerable function in promoting the sorption process of heavy metal using the NJ zeolite. The initial concentration of heavy metals in the stock solution was extended between 80 and 600 mg/L. The batch adsorption method was employed to investigate the adsorption process. The experimental data were correlated using Freundlich and Langmuir empirical formula. The ability of NJ zeolite to eliminate cadmium and copper was estimated according to Langmuir isotherm empirical formula and found 25.9 and 14.3 mg/g for cadmium and copper, respectively. The kinetics of adsorption of cadmium and copper have been analyzed and correlated by first-order and second-order reaction model. It was noticed that adsorption of cadmium and copper was better correlated with pseudo-second-order kinetic model. The results presented that NJ zeolite is practical adsorbent for removing cadmium and copper ion metal.

  11. The removal of heavy metals from aqueous solution using natural Jordanian zeolite

    NASA Astrophysics Data System (ADS)

    Taamneh, Yazan; Sharadqah, Suhail

    2017-07-01

    In this article, the adsorption process of cadmium and copper using natural Jordanian (NJ) zeolite as adsorbent has been experimentally estimated. The samples of NJ zeolite were obtained from Al Mafraq discrete, north east of Jordan. The influence of the bulk concentration ( C o), contact time ( t) and different adsorbent masses ( m) of NJ zeolite on the removal of heavy metal were evaluated. These variables had a considerable function in promoting the sorption process of heavy metal using the NJ zeolite. The initial concentration of heavy metals in the stock solution was extended between 80 and 600 mg/L. The batch adsorption method was employed to investigate the adsorption process. The experimental data were correlated using Freundlich and Langmuir empirical formula. The ability of NJ zeolite to eliminate cadmium and copper was estimated according to Langmuir isotherm empirical formula and found 25.9 and 14.3 mg/g for cadmium and copper, respectively. The kinetics of adsorption of cadmium and copper have been analyzed and correlated by first-order and second-order reaction model. It was noticed that adsorption of cadmium and copper was better correlated with pseudo-second-order kinetic model. The results presented that NJ zeolite is practical adsorbent for removing cadmium and copper ion metal.

  12. Ammonium sorption from aqueous solutions by the natural zeolite Transcarpathian clinoptilolite studied under dynamic conditions.

    PubMed

    Sprynskyy, Myroslav; Lebedynets, Mariya; Terzyk, Artur P; Kowalczyk, Piotr; Namieśnik, Jacek; Buszewski, Bogusław

    2005-04-15

    The scope of this study is ammonium-ion uptake from synthetic aqueous solutions onto raw and pretreated forms of the natural zeolite Transcarpathian clinoptilolite under dynamic conditions. Hydrogen ions displaced exchangeable cations on the clinoptilolite in distilled water (sodium ions) and hydrochloric acid (sodium, potassium, and calcium ions) and destroyed the zeolite framework structure in the last case. Ammonium uptake onto the zeolite occurs by exchange with Na(+), Ca(2+), and K(+) ions. Although Na(+) ions were observed to be more easily exchanged for both hydrogen and ammonium ions, the role of Ca(2+) ions increased with zeolite saturation by NH(+)(4) ions. The maximum sorption capacity of the clinoptilolite toward NH(+)(4) ions, estimated under dynamic conditions, is significantly higher than that measured under static conditions; proximity of the values of a distribution coefficient and a retardation factor for different conditions (215-265 dm(3)/kg and 979-1107, respectively) allows us to use these parameters to model ammonium uptake onto the clinoptilolite. Slowing down or interruption in filtration resulted in the improvement of ammonium sorption properties of the zeolite. The ammonium removal improves with use of the finer fractions of the clinoptilolite up to 0.35 mm. A recycling study results confirmed the importance of external diffusion for ammonium sorption by the clinoptilolite. Preliminary treatment of the sorbent confirmed the predominant importance of the ion-exchange mechanism. The advantage of prior NaCl treatment of the clinoptilolite in improvement of ammonium removal over the other techniques was shown.

  13. Undergraduate students' conceptions of natural and anthropogenic climate change: A case study approach

    NASA Astrophysics Data System (ADS)

    Trenbath, Thien-Kim Leckie

    This dissertation shows the evolution of five undergraduate students' ideas of natural and anthropogenic climate change throughout a lecture hall course on climate change. This research was informed by conceptual change theory and students' inaccurate ideas of climate change. Subjects represented different levels of climate change understanding at the beginning of the course and were selected based on their scores on a climate change questionnaire. The study was designed to research how students' ideas changed throughout the course and compare trajectories of lower and higher achieving students. At the beginning, students had different levels of understanding, but as the semester continued, the lower-performing students progressed more than the higher-performing students. At the end of the course, all students described more ideas than they did at the beginning; however some of these ideas were inconsistent with the professors' instruction. Lower-performing students struggled more than the higher-performing students. Struggles included differentiating climate change and its causes, effects, and consequences from other environmental problems. Students also struggled with the idea that climate change is anthropogenic despite it being natural in the past. In order to understand that climate change is impacted by human forcings in addition to natural forcings, students developed the relationship that climate change is natural and humans are "speeding it up." They took time to integrate this relationship into their prior ideas. Three of the students constructed a definition of climate change that was different than the professor's. Two students defined "climate change" as only the natural aspects of climate change and reserved the anthropogenic changes for the term "global warming". For a third student, "climate change" included damming rivers, eutrophication, frog mutations, ozone depletion, and overfishing, which are environmental ailments but not climate change.

  14. Evaluation of strategies for nature-based solutions to drought: a decision support model at the national scale

    NASA Astrophysics Data System (ADS)

    Simpson, Mike; Ives, Matthew; Hall, Jim

    2016-04-01

    There is an increasing body of evidence in support of the use of nature based solutions as a strategy to mitigate drought. Restored or constructed wetlands, grasslands and in some cases forests have been used with success in numerous case studies. Such solutions remain underused in the UK, where they are not considered as part of long-term plans for supply by water companies. An important step is the translation of knowledge on the benefits of nature based solutions at the upland/catchment scale into a model of the impact of these solutions on national water resource planning in terms of financial costs, carbon benefits and robustness to drought. Our project, 'A National Scale Model of Green Infrastructure for Water Resources', addresses this issue through development of a model that can show the costs and benefits associated with a broad roll-out of nature based solutions for water supply. We have developed generalised models of both the hydrological effects of various classes and implementations of nature-based approaches and their economic impacts in terms of construction costs, running costs, time to maturity, land use and carbon benefits. Our next step will be to compare this work with our recent evaluation of conventional water infrastructure, allowing a case to be made in financial terms and in terms of security of water supply. By demonstrating the benefits of nature based solutions under multiple possible climate and population scenarios we aim to demonstrate the potential value of using nature based solutions as a component of future long-term water resource plans. Strategies for decision making regarding the selection of nature based and conventional approaches, developed through discussion with government and industry, will be applied to the final model. Our focus is on keeping our work relevant to the requirements of decision-makers involved in conventional water planning. We propose to present the outcomes of our model for the evaluation of nature

  15. Using the history of research on sickle-cell anemia to affect preservice teachers' conceptions of the nature of science

    NASA Astrophysics Data System (ADS)

    Howe, Eric M.

    Preservice elementary teachers enrolled in an elective biology course participated in an eight-class unit of instruction based on the history of research in understanding the disease sickle-cell anemia. Students were introduced to the disease as a "mystery" for them to solve, and subsequently developed an understanding of the disease from several disciplines in biology (e.g., genetics, ecology, evolution, molecular biology). The unit involved open-ended problems in which students examined evidence and developed explanations in a manner analogous to the reasoning used by Anthony C. Allison and his colleagues during the early to middle part of the twentieth century. Throughout the unit, students were challenged to explicitly and reflectively connect their work with the historical material to more general conclusions about aspects of the nature of science. These aspects included (a) the nature of scientific theories, (b) the tentative nature of science, (c) the difference between scientific theories and laws, (d) the validity of observational methods in science, and (e) the subjective (theory-laden) nature of science. The research measured students' pre- and post-instruction views by using both an open-ended survey (VNOS) and follow-up, semi-structured interviews. The results indicated that an appreciable number of students underwent a change or enrichment in their views for some of the nature of science aspects. Moreover, change or enrichment in students' views was directly attributable to their work in the sickle-cell unit as evidenced from the specific examples students articulated in their post-instruction responses in support of their more informed views. In general, the findings of this research lend empirical support to the value of having students actively recapitulate the history of science to improve their nature of science conceptions. This is facilitated when the lessons challenge students to explicitly and reflectively develop views of the nature of

  16. Bovine superfetation by natural conception secondary to an embryo transfer pregnancy.

    PubMed

    Hall, W H

    1987-07-01

    There was only one embryo transferred to the recipient female. There was no chance for natural service to occur from 21 days prior to the transfer of the embryo to 31 days after the transfer of the 7 day old blastocyst. The surrogate female was palpated as being 38 days pregnant 31 days after the transfer of a 7 day old embryo by an experienced professional before being exposed to the natural service sire. The second fetus was of a different sex than the first and was approximately 60 days less mature. All other pregnancies within this well managed herd were accounted for and no other cows calved within the area close to that time. The remaining recipients carried pregnancies to the approximate expected calving date. Conclusion. This case report should support earlier evidence that superfetation in the bovine can and does occur.

  17. Restoring native fish assemblages to a regulated California stream using the natural flow regime concept.

    PubMed

    Kiernan, Joseph D; Moyle, Peter B; Crain, Patrick K

    2012-07-01

    We examined the response of fishes to establishment of a new flow regime in lower Putah Creek, a regulated stream in California, U.S.A. The new flow regime was designed to mimic the seasonal timing of natural increases and decreases in stream flow. We monitored fish assemblages annually at six sample sites distributed over approximately 30 km of stream for eight years before and nine years after the new flow regime was implemented. Our purpose was to determine whether more natural stream flow patterns would reestablish native fishes and reduce the abundances of alien (nonnative) fishes. At the onset of our study, native fishes were constrained to habitat immediately (<1 km) below the diversion dam, and alien species were numerically dominant at all downstream sample sites. Following implementation of the new flow regime, native fishes regained dominance across more than 20 km of lower Putah Creek. We propose that the expansion of native fishes was facilitated by creation of favorable spawning and rearing conditions (e.g., elevated springtime flows), cooler water temperatures, maintenance of lotic (flowing) conditions over the length of the creek, and displacement of alien species by naturally occurring high-discharge events. Importantly, restoration of native fishes was achieved by manipulating stream flows at biologically important times of the year and only required a small increase in the total volume of water delivered downstream (i.e., water that was not diverted for other uses) during most water years. Our results validate that natural flow regimes can be used to effectively manipulate and manage fish assemblages in regulated rivers.

  18. Isolation of nonvolatile, organic solutes from natural waters by zeotrophic distillation of water from N,N-dimethylformamide

    USGS Publications Warehouse

    Leenheer, J.A.; Brown, P.A.; Stiles, E.A.

    1987-01-01

    Nonvolatile, organic solutes that comprise the dissolved organic carbon (DOC) in saline waters were isolated by removal of the water by distillation from a N,N-dimethylformamideformic acid-acetonitrile mixture. Salts isolated with the DOC were removed by crystallization of sodium chloride and sodium sulfate from the solvent mixture, removal of silicic acid by acidification and precipitation, removal of boric acid by methylation and volatilization, and removal of phosphate by zinc acetate precipitation. Chemical alteration of the organic solutes was minimized during evaporative concentration steps by careful control of acid concentrations in the solvent mixture and was minimized during drying by conversion of the samples to pyridinium and sodium salts. Recoveries of various hydrophilic organic standards from aqueous salt solutions and recoveries of natural organic solutes from various water samples varied from 60 to 100%. Losses of organic solutes during the isolation procedure were nonselective and related to the number of salt- and precipitate-washing cycles in the procedure.

  19. Isolation of nonvolatile, organic solutes from natural waters by zeotrophic distillation of water from N,N-dimethylformamide

    SciTech Connect

    Leenheer, J.A.; Brown, P.A.; Stiles, E.A.

    1987-05-01

    Nonvolatile, organic solutes that comprise the dissolved organic carbon (DOC) in saline waters were isolated by removal of the water by distillation from a N,N-dimethylformamide-formic acid-acetonitrile mixture. Salts isolated with the DOC were removed by crystallization of sodium chloride and sodium sulfate from the solvent mixture, removal of silicic acid by acidification and precipitation, removal of boric acid by methylation and volatilization, and removal of phosphate by zinc acetate precipitation. Chemical alteration of the organic solutes was minimized during evaporative concentration steps by careful control of acid concentrations in the solvent mixture and was minimized during drying by conversion of the samples to pyridinium and sodium salts. Recoveries of various hydrophilic organic standards from aqueous salt solutions and recoveries of natural organic solutes from various water samples varied from 60 to 100%. Losses of organic solutes during the isolation procedure were nonselective and related to the number of salt- and precipitate-washing cycles in the procedure.

  20. Nature of Non-Fickian Solute Transport in Complex Heterogeneous Porous Media - Carbonates

    NASA Astrophysics Data System (ADS)

    Bijeljic, B.; Mostaghimi, P.; Blunt, M. J.

    2011-12-01

    Despite the range of significant practical applications of solute transport, including the long-term fate of nuclear waste repositories, secure storage of CO2 and improved oil recovery, even the qualitative behavior of most rocks is uncertain: vast carbonate sedimentary basins contain more than half the world's current oil reserves yet experimental data on transport in carbonates is scant. The relationship between pore structure, velocity field and transport remains unknown, particularly for heterogeneous carbonates. We simulate solute transport through 3D μ-CT images of different rock samples, representing geological media of increasing pore-scale complexity: a sandpack, a Berea sandstone and a Portland limestone. A finite-difference Stokes solver is employed to compute the flow field and transport particles semi-analytically along streamlines to represent advection with a random motion to model diffusion. We predict the propagators measured on similar cores in Nuclear Magnetic Resonance (NMR) experiments. Dispersion coefficient dependence on Peclet number is shown to have different scaling for complex carbonates. The behavior is explained using continuous time random walks with a truncated power-law distribution of travel times: transport is qualitatively different for the complex limestone compared to the sandstone or sandpack, with long tailing, an almost immobile peak concentration and a very slow approach to asymptotic dispersion. We demonstrate the different nature of non-Fickian transport in carbonates by analyzing the transit time probabilities ψ(τ) of traveling between two neighboring voxels for Portland carbonate that show an approximately power-law dependence of travel times ψ(τ) ~ τ -1-β with a slope corresponding to β = 0.7, as shown in Fig.1. The comparison with ψ(τ) of the sandpack and Berea sandstone for Pe = ∝ indicates quantitatively different generic behavior, as the sandpack and sandstone have slope corresponding to β = 1.8 (two

  1. Structure and nature of manganese(II) imidazole complexes in frozen aqueous solutions.

    PubMed

    Un, Sun

    2013-04-01

    A common feature of a large majority of the manganese metalloenzymes, as well as many synthetic biomimetic complexes, is the bonding between the manganese ion and imidazoles. This interaction was studied by examining the nature and structure of manganese(II) imidazole complexes in frozen aqueous solutions using 285 GHz high magnet-field continuous-wave electron paramagnetic resonance (cw-HFEPR) and 95 GHz pulsed electron-nuclear double resonance (ENDOR) and pulsed electron-double resonance detected nuclear magnetic resonance (PELDOR-NMR). The (55)Mn hyperfine coupling and isotropic g values of Mn(II) in frozen imidazole solutions continuously decreased with increasing imidazole concentration. ENDOR and PELDOR-NMR measurements demonstrated that the structural basis for this behavior arose from the imidazole concentration-dependent distribution of three six-coordinate and two four-coordinate species: [Mn(H2O)6](2+), [Mn(imidazole)(H2O)5](2+), [Mn(imidazole)2(H2O)4](2+), [Mn(imidazole)3(H2O)](2+), and [Mn(imidazole)4](2+). The hyperfine and g values of manganese proteins were also fully consistent with this imidazole effect. Density functional theory methods were used to calculate the structures, spin and charge densities, and hyperfine couplings of a number of different manganese imidazole complexes. The use of density functional theory with large exact-exchange admixture calculations gave isotropic (55)Mn hyperfine couplings that were semiquantitative and of predictive value. The results show that the covalency of the Mn-N bonds play an important role in determining not only magnetic spin parameters but also the structure of the metal binding site. The relationship between the isotropic (55)Mn hyperfine value and the number of imidazole ligands provides a quick and easy test for determining whether a protein binds an Mn(II) ion using histidine residues and, if so, how many are involved. Application of this method shows that as much as 40% of the Mn(II) ions in

  2. Nature-based flood risk management -challenges in implementing catchment-wide management concepts

    NASA Astrophysics Data System (ADS)

    Thaler, Thomas; Fuchs, Sven

    2017-04-01

    Traditionally, flood risk management focused on coping with the flow at a given point by, for example, building dikes or straightening the watercourse. Increasingly the emphasis has shifted to measures within the flood plain to delay the flow through storage. As such the fluent boundaries imposed by the behaviour of the catchment at a certain point are relocated upstream by the human intervention. Therefore, the implementation of flood storages and the use of natural retention areas are promoted as mitigation measures to support sustainable flood risk management. They aimed at reducing the effluent boundaries on the floodplain by increasing the effluent boundaries upstream. However, beyond the simple change of practices it is indeed often a question of land use change which is at stake in water management. As such, it poses the questions on how to govern both water and land to satisfy the different stakeholders. Nature-based strategies often follow with voluntary agreements, which are promoted as an alternative instrument to the traditional top-down command and control regulation. Voluntary agreements aim at bringing more efficiency, participatory and transparency in solving problems between different social groups. In natural hazard risk management voluntary agreements are now receiving high interests to complement the existing policy instruments in order to achieve the objectives the EU WFD and of the Floods Directive. This paper investigates the use of voluntary agreements as an alternative instrument to the traditional top-down command and control regulation in the implementation of flood storages in Austria. The paper provides a framework of analysis to reveal barriers and opportunities associated with such approach. The paper concludes that institution and power are the central elements to tackle for allowing the success of voluntary agreement.

  3. Nature based solution for improving mental health and well-being in urban areas.

    PubMed

    Vujcic, Maja; Tomicevic-Dubljevic, Jelena; Grbic, Mihailo; Lecic-Tosevski, Dusica; Vukovic, Olivera; Toskovic, Oliver

    2017-10-01

    recuperation from stress, depression and anxiety was possible and much more complete when participants were involved in horticulture therapy as a nature-based solution for improving mental health. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. CFD modeling of fluid flow and solute transport in a µXCT scanned natural fracture: Impact of fracture geometry on solute transport

    NASA Astrophysics Data System (ADS)

    Huber, F. M.; Enzmann, F.; Wenka, A.; Dentz, M.; Schaefer, T.

    2010-12-01

    Fluid flow and solute transport through fractures are a key process in both industrial and scientific issues ranging from e.g. geothermal energy production to the disposal of nuclear waste in deep geologic formations. Therefore, a fundamental understanding of the various interdependent processes governing fluid flow and solute transport in fractures over a broad range of length and time scales is of utmost importance. Numerous studies have shown the importance of fracture geometry on flow and solute transport. More recently, significance of so called recirculation zones which are accessible for solutes and colloids through hydrodynamic dispersion and molecular diffusion have been identified [1,2] which can be responsible for pronounced late time solute breakthrough (tailing). Unfortunately, these studies are mostly focused on 2D. Thus, the intention of the prevailing study is to investigate the influence of fracture geometry on solute transport under a broad range of flow conditions (Pe number from 0.1 up to 1000) and as a function of flow direction (that is, reversed flow direction) both in 2D and 3D. We present µXCT measurements with a spatial resolution of 80 µm of a natural single fracture in a diorite drill core from Äspö, Sweden, which serves as direct input for computational mesh generation in order to obtain a realistic 3D model. Besides, a 2D model was produced by projecting the 3D mesh into the x-y-plane to completely exclude the fracture aperture information. Computational fluid dynamic simulations in 2D and 3D have been conducted to study fluid flow and conservative tracer (HTO) transport by means of the finite volume code FLUENT. The natural fracture exhibits a very complex geometry with asperities, rough side walls and a heterogenous aperture distribution. Furthermore, the µXCT data clearly shows that the fracture is not filled with fault gauge material. Simulation results confirm the impact of fracture geometry/roughness on fluid flow causing

  5. Leukocytes and the natural history of deep vein thrombosis: current concepts and future directions

    PubMed Central

    P, Saha; J, Humphries; B, Modarai; K, Mattock; M, Waltham; C, Evans; A, Ahmad; A, Patel; S, Premaratne; OTA, Lyons; A, Smith

    2011-01-01

    Observational studies have shown that inflammatory cells accumulate within the thrombus and surrounding vein wall during the natural history of venous thrombosis. More recent studies have begun to unravel the mechanisms that regulate this interaction and have confirmed that thrombosis and inflammation are intimately linked. This review outlines our current knowledge of the complex relationship between inflammatory cell activity and venous thrombosis and highlights new areas of research in this field. A better understanding of this relationship could lead to the development of novel therapeutic targets that inhibit thrombus formation or promote its resolution. PMID:21325673

  6. Evaluation of unsupervised semantic mapping of natural language with Leximancer concept mapping.

    PubMed

    Smith, Andrew E; Humphreys, Michael S

    2006-05-01

    The Leximancer system is a relatively new method for transforming lexical co-occurrence information from natural language into semantic patterns in a nunsupervised manner. It employs two stages of co-occurrence information extraction-semantic and relational-using a different algorithm for each stage. The algorithms used are statistical, but they employ nonlinear dynamics and machine learning. This article is an attempt to validate the output of Leximancer, using a set of evaluation criteria taken from content analysis that are appropriate for knowledge discovery tasks.

  7. Dimerization of green sensitizing cyanines in solution. A spectroscopic and theoretical study of the bonding nature

    NASA Astrophysics Data System (ADS)

    Baraldi, I.; Caselli, M.; Momicchioli, F.; Ponterini, G.; Vanossi, D.

    2002-01-01

    The bonding nature in cyanine-dye aggregates has been investigated by studying dimerization in solution of 3,3 '-disulfopropyl-4,5,4 ',5 '-dibenzo-9-ethyloxacarbocyanine (D) and three other oxacarbocyanine analogues (E, F, G) used as photographic sensitizers in the green spectral region. Quantitative information on the monomer-dimer equilibrium of dye D in different solvents and of its analogues (E, F, G) in water was obtained by measurement of the absorption spectrum as a function of dye concentration and of temperature. Dimerization was found to be generally driven by enthalpic factors traceable to strong attractive van der Waals interactions between the two large and highly polarizable dye molecules. Entropic contributions to ΔG0 usually favour dissociation but are smaller than the enthalpic ones. The visible absorption spectrum of the dimer consists in a classic two-branched exciton band with a marked splitting ( 1600 cm-1 in water). The experimental observations were the subject of a theoretical study including classical molecular dynamics (MD) and Monte Carlo (MC) calculations of the dimer structure and comparative analysis of monomer and dimer spectra by the CS INDO CI method. Computer simulations led to three similar H-type structures, the most stable of which is characterized by a distance of 4.7 Å between the planes of the chromophores and an endo-endo configuration of the sulfopropyl substituents. The calculated dimer spectrum was clearly interpreted in terms of exciton model but a quantitative agreement with the two-maximum exciton band could be obtained only by assuming substantial deviation of the long molecular axes from parallelism. On the basis of normal coordinate calculations it is suggested that such configurations may occur with a high probability in virtue of twisting vibrational motions of extremely low frequency.

  8. Natural vermiculite as an exchanger support for heavy cations in aqueous solution.

    PubMed

    da Fonseca, Maria G; de Oliveira, Michelle M; Arakaki, Luiza N H; Espinola, José G P; Airoldi, Claudio

    2005-05-01

    The natural highly charged lamellar silicate vermiculite was investigated as an exchanger matrix in doubly distilled water solution to exchange magnesium inside the lamella with the heavy cations copper, nickel, cobalt, and lead at the solid/liquid interface. The extension of each exchange reaction was dependent on time of reaction, pH, and cation concentration. The maximum time presented the following order Pb2+ < Ni2+ < Cu2+ < Co2+, which corresponds to 12, 24, 48, and 72 h, respectively. The best performance was observed for nickel, as represented by the exchange capacity Nf, which gave values 0.59, 0.76, 0.84, and 0.93 mmol g(-1) for Pb2+ < Co2+ < Cu2+ < Ni2+, respectively. This capacity is dependent on pH interval variation from 1 to 9, being significantly increased in alkaline condition. The isotherm data were adjusted to a modified Langmuir equation and from the data the spontaneous Gibbs free energy was calculated. Linear correlations were obtained through Gibbs free energy or the maximum capacity against the cationic radius plot, with the lowest values for the largest cation lead. An exponential correlation was also observed for the maximum capacity versus enthalpy of hydration plot, indicating a difficulty of the less hydrated cation, lead, in exchanging with magnesium inside the lamellar space, as suggested by the proposed mechanism. The saturated matrices with cations presented a decrease in interlayer distance in comparison with the original vermiculite, which can be related to the hydrated phases, characteristic for each cation, with a lowest value for lead.

  9. Multiple Solutions in Natural Convection in an Air Filled Square Enclosure: Fractal Dimension of Attractors

    NASA Astrophysics Data System (ADS)

    Aklouche Benouaguef, S.; Zeghmati, B.; Bouhadef, K.; Daguenet, M.

    In this study, we investigated numerically the transient natural convection in a square cavity with two horizontal adiabatic sides and vertical walls composed of two regions of same size maintained at different temperatures. The flow has been assumed to be laminar and bi-dimensional. The governing equations written in dimensionless form and expressed in terms of stream function and vorticity, have been solved using the Alternating Direction Implicit (ADI) method and the GAUSS elimination method. Calculations were performed for air (Pr = 0.71), with a Rayleigh number varying from 2.5x105 to 3.7x106. We analysed the effect of the Rayleigh number on the route to the chaos of the system. The first transition has been found from steady-state to oscillatory flow and the second is a subharmonic bifurcation as the Rayleigh number is increased further. For sufficiently small Rayleigh numbers, present results show that the flow is characterized by four cells with horizontal and vertical symmetric axes. The attractor bifurcates from a stable fixed point to a limit cycle for a Rayleigh number varying from 2.5x105 to 2.51x105. A limit cycle settles from Ra = 3x105 and persists until Ra = 5x105. At a Rayleigh number of 2.5x105 the temporal evolution of the Nusselt number Nu(t) was stationary. As the Rayleigh number increases, the flow becomes unstable and bifurcates to a time periodic solution at a critical Rayleigh number between 2.5x105 and 2.51x105. After the first HOPF bifurcation at Ra = 2.51x105, the oscillatory flow undergoes several bifurcations and ultimately evolves into a chaotic flow.

  10. Nature-based solutions to promote human resilience and wellbeing in cities during increasingly hot summers.

    PubMed

    Panno, Angelo; Carrus, Giuseppe; Lafortezza, Raffaele; Mariani, Luigi; Sanesi, Giovanni

    2017-08-16

    Air temperatures are increasing because of global climate change. A warming phenomenon strongly related to global climate change is the urban heat island. It has been shown that the hotter temperatures occurring in cities during the summer negatively affect human wellbeing, but little is known about the potential mechanisms underlying the relationships between hotter temperatures, cognitive psychological resources and wellbeing. The aim of the present research is to understand whether, and how, spending time in urban green spaces, which can be considered as a specific kind of Nature-Based Solution (NBS), helps the recovery of cognitive resources and wellbeing. The main hypothesis is that contact with urban green is related to wellbeing through the depletion of cognitive resources (i.e., ego depletion). Moreover, we expected that individuals showing higher scores of ego depletion also report a higher estimate of the maximum temperature reached during the summer. The results of a survey (N = 115) conducted among visitors to Parco Nord Milano, a large urban park located in Milan (Italy), point out that people visiting the park during the summer show a higher level of wellbeing as well as a lower level of ego depletion. A mediation analysis shows that visiting urban green spaces is associated with greater wellbeing through less ego depletion. Our results also point out that, as expected, people showing a higher level of ego depletion tend to overestimate the maximum air temperature. Implications for future studies and applied interventions regarding the role of NBS to promote human wellbeing are discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. USING POPULATION GENOMICS TO DETECT SELECTION IN NATURAL POPULATIONS: KEY CONCEPTS AND METHODOLOGICAL CONSIDERATIONS

    PubMed Central

    Hohenlohe, Paul A.; Phillips, Patrick C.; Cresko, William A.

    2010-01-01

    Natural selection shapes patterns of genetic variation among individuals, populations, and species, and it does so differentially across genomes. The field of population genomics provides a comprehensive genome-scale view of the action of selection, even beyond traditional model organisms. However, even with nearly complete genomic sequence information, our ability to detect the signature of selection on specific genomic regions depends on choosing experimental and analytical tools appropriate to the biological situation. For example, processes that occur at different timescales, such as sorting of standing genetic variation, mutation-selection balance, or fixed interspecific divergence, have different consequences for genomic patterns of variation. Inappropriate experimental or analytical approaches may fail to detect even strong selection or falsely identify a signature of selection. Here we outline the conceptual framework of population genomics, relate genomic patterns of variation to evolutionary processes, and identify major biological factors to be considered in studies of selection. As data-gathering technology continues to advance, our ability to understand selection in natural populations will be limited more by conceptual and analytical weaknesses than by the amount of molecular data. Our aim is to bring critical biological considerations to the fore in population genomics research and to spur the development and application of analytical tools appropriate to diverse biological systems. PMID:21218185

  12. USING POPULATION GENOMICS TO DETECT SELECTION IN NATURAL POPULATIONS: KEY CONCEPTS AND METHODOLOGICAL CONSIDERATIONS.

    PubMed

    Hohenlohe, Paul A; Phillips, Patrick C; Cresko, William A

    2010-11-01

    Natural selection shapes patterns of genetic variation among individuals, populations, and species, and it does so differentially across genomes. The field of population genomics provides a comprehensive genome-scale view of the action of selection, even beyond traditional model organisms. However, even with nearly complete genomic sequence information, our ability to detect the signature of selection on specific genomic regions depends on choosing experimental and analytical tools appropriate to the biological situation. For example, processes that occur at different timescales, such as sorting of standing genetic variation, mutation-selection balance, or fixed interspecific divergence, have different consequences for genomic patterns of variation. Inappropriate experimental or analytical approaches may fail to detect even strong selection or falsely identify a signature of selection. Here we outline the conceptual framework of population genomics, relate genomic patterns of variation to evolutionary processes, and identify major biological factors to be considered in studies of selection. As data-gathering technology continues to advance, our ability to understand selection in natural populations will be limited more by conceptual and analytical weaknesses than by the amount of molecular data. Our aim is to bring critical biological considerations to the fore in population genomics research and to spur the development and application of analytical tools appropriate to diverse biological systems.

  13. Relict high-Andean ecosystems challenge our concepts of naturalness and human impact.

    PubMed

    Sylvester, Steven P; Heitkamp, Felix; Sylvester, Mitsy D P V; Jungkunst, Hermann F; Sipman, Harrie J M; Toivonen, Johanna M; Gonzales Inca, Carlos A; Ospina, Juan C; Kessler, Michael

    2017-06-13

    What would current ecosystems be like without the impact of mankind? This question, which is critical for ecosystem management, has long remained unanswered due to a lack of present-day data from truly undisturbed ecosystems. Using mountaineering techniques, we accessed pristine relict ecosystems in the Peruvian Andes to provide this baseline data and compared it with the surrounding accessible and disturbed landscape. We show that natural ecosystems and human impact in the high Andes are radically different from preconceived ideas. Vegetation of these 'lost worlds' was dominated by plant species previously unknown to science that have become extinct in nearby human-affected ecosystems. Furthermore, natural vegetation had greater plant biomass with potentially as much as ten times more forest, but lower plant diversity. Contrary to our expectations, soils showed relatively little degradation when compared within a vegetation type, but differed mainly between forest and grassland ecosystems. At the landscape level, a presumed large-scale forest reduction resulted in a nowadays more acidic soilscape with higher carbon storage, partly ameliorating carbon loss through deforestation. Human impact in the high Andes, thus, had mixed effects on biodiversity, while soils and carbon stocks would have been mainly indirectly affected through a suggested large-scale vegetation change.

  14. A Eurasian Mineralogy: Aleksandr Fersman’s Conception of the Natural World.

    PubMed

    Bruno, Andy

    2016-09-01

    Thoroughly a product of imperial Russia’s aristocratic culture, the mineralogist and geochemist Aleksandr Fersman rose to the top of the country’s scientific establishment after the Bolsheviks took control. He then remained a staunch supporter of various industrial projects through much of the Stalinist period. This essay puts Fersman’s thinking about the natural world in conversation with a quite distinctive mode of intellectual inquiry that developed contemporaneously. Eurasianism was a philosophical doctrine of a group of Russian émigrés who emphasized Russia’s unique status straddling Europe and Asia. While Fersman did not belong to this group of thinkers, a number of his ideas drew on specific experiences in the environments of the Eurasian landmass. Indeed, the article argues that Fersman’s dualistic understanding of nature, his advocacy for the field of geochemistry, his definition of deserts, and a scheme he proposed for industrial operations owed much to the Eurasian settings of the science he practiced. Furthermore, this case of a Eurasian mineralogist illuminates novel aspects of the interplay between national and global sciences.

  15. A new concept of hybrid photovoltaic thermal (PVT) collector with natural circulation

    NASA Astrophysics Data System (ADS)

    Lu, Longsheng; Wang, Xiaowu; Wang, Shuai; Liu, Xiaokang

    2017-07-01

    Hybrid photovoltaic thermal (PVT) technology refers to the integration of a photovoltaic module into a conventional solar thermal collector. Generally, the traditional design of a PVT collector has solar cells fixed on the top surface of an absorber in a flat-plate solar thermal collector. In this work, we presented a new concept of water-based PVT collector in which solar cells were directly placed on the bottom surface of its glass cover. A dynamic numerical model of this new PVT is developed and validated by experimental tests. With numerical analysis, it is found that at same covering factor, the electricity conversion efficiency of solar cells of the new PVT exceed that of the traditional PVT by nearly 10% while its thermal efficiency is approximately 30% lower than that of the traditional PVT. When the covering factor changes from 0.05 to 1, the thermal efficiency of the new PVT drops nearly 70%. The thermal efficiency of both the new PVT and the traditional PVT rise up as the water mass in tank increases. Meanwhile, the final water temperature in tank of the traditional PVT collector declines more than 17 °C, whereas that of the new PVT declines less than 6 °C, when the water mass increases from 100 to 300 kg.

  16. A new concept of hybrid photovoltaic thermal (PVT) collector with natural circulation

    NASA Astrophysics Data System (ADS)

    Lu, Longsheng; Wang, Xiaowu; Wang, Shuai; Liu, Xiaokang

    2017-02-01

    Hybrid photovoltaic thermal (PVT) technology refers to the integration of a photovoltaic module into a conventional solar thermal collector. Generally, the traditional design of a PVT collector has solar cells fixed on the top surface of an absorber in a flat-plate solar thermal collector. In this work, we presented a new concept of water-based PVT collector in which solar cells were directly placed on the bottom surface of its glass cover. A dynamic numerical model of this new PVT is developed and validated by experimental tests. With numerical analysis, it is found that at same covering factor, the electricity conversion efficiency of solar cells of the new PVT exceed that of the traditional PVT by nearly 10% while its thermal efficiency is approximately 30% lower than that of the traditional PVT. When the covering factor changes from 0.05 to 1, the thermal efficiency of the new PVT drops nearly 70%. The thermal efficiency of both the new PVT and the traditional PVT rise up as the water mass in tank increases. Meanwhile, the final water temperature in tank of the traditional PVT collector declines more than 17 °C, whereas that of the new PVT declines less than 6 °C, when the water mass increases from 100 to 300 kg.

  17. Elucidating elementary science teachers' conceptions of the nature of science: A view to beliefs about both science and teaching

    NASA Astrophysics Data System (ADS)

    Keske, Kristina Palmer

    The purpose of this interpretive case study was to elucidate the conceptions of the nature of science held by seven elementary science teachers. The constructivist paradigm provided the philosophical and methodological foundation for the study. Interviews were employed to collect data from the participants about their formal and informal experiences with science. In addition, the participants contributed their perspectives on four aspects of the nature of science: what is science; who is a scientist; what are the methods of science; and how is scientific knowledge constructed. Data analysis not only revealed these teachers' views of science, but also provided insights into how they viewed science teaching. Four themes emerged from the data. The first theme developed around the participants' portrayals of the content of science, with participant views falling on a continuum of limited to universal application of science as procedure. The second theme dealt with the participants' views of the absolute nature of scientific knowledge. Participants' perceptions of the tentative nature of science teaching provided the basis for the third theme concerning the need for absolutes in practice. The fourth theme drew parallels between participants' views of science and science teaching, with two participants demonstrating a consistency in beliefs about knowledge construction across contexts. This study revealed both personal and contextual factors which impacted how the participants saw science and science teaching. Many of the participants' memories of formal science revolved around the memorization of content and were viewed negatively. All the participants had limited formal training in science. Of the seven participants, only two had chosen to be science teachers at the beginning of their careers. The participants' limited formal experiences with science provided little time for exploration into historical, philosophical, and sociological studies of science, a necessary

  18. Munazza's story: Understanding science teaching and conceptions of the nature of science in Pakistan through a life history study

    NASA Astrophysics Data System (ADS)

    Halai, Nelofer

    In this study I have described and tried to comprehend how a female science teacher understands her practice. Additionally, I have developed some understanding of her understanding of the nature of science. While teaching science, a teacher projects messages about the nature of science that can be captured by observations and interviews. Furthermore, the manner is which a teacher conceptualizes science for teaching, at least in part, depends on personal life experiences. Hence, I have used the life history method to understand Munazza's practice. Munazza is a young female science teacher working in a private, co-educational school for children from middle income families in Karachi, Pakistan. Her stories are central to the study, and I have represented them using a number of narrative devices. I have woven in my own stories too, to illustrate my perspective as a researcher. The data includes 13 life history interviews and many informal conversations with Munazza, observations of science teaching in classes seven and eight, and interviews with other science teachers and administrative staff of the school. Munazza's personal biography and experiences of school and undergraduate courses has influenced the way she teaches. It has also influenced the way she does not teach. She was not inspired by her science teachers, so she has tried not to teach the way she was taught science. Contextual factors, her conception of preparation for teaching as preparation for subject content and the tension that she faces in balancing care and control in her classroom are some factors that influence her teaching. Munazza believes that science is a stable, superior and value-free way of knowing. In trying to understand the natural world, observations come first, which give reliable information about the world leading inductively to a "theory". Hence, she relies a great deal on demonstrations in the class where students "see" for themselves and abstract the scientific concept from the

  19. The chemical protecting group concept applied in crosslinking of natural tissues with glutaraldehyde acetals.

    PubMed

    Goissis, G; Yoshioka, S A; Braile, D M; Ramirez, V D

    1998-03-01

    This work describes the results of the controlled crosslinking of collagen matrices by glutaraldehyde based on a double protection strategy, glutaraldehyde acetals and lysine protonation due to the acidic conditions of acetal formation. Materials crosslinked by this approach were characterized by thermal stability comparable to those obtained by conventional procedures with mechanical properties expected for bioprosthesis manufacture and with a higher stability toward collagenase hydrolysis. The integrity of the microfibrillar structure was confirmed by optical and scanning electronic microscopy. The results indicate that the glutaraldehyde acetals procedure may be of potential use for the crosslinking of bovine pericardium used in the manufacture of bioprosthetic devices. Advantages may be related to the production of materials with homogeneous crosslinking distributions, associated with better definition in the nature of the chemical link that they introduce, due to a better distribution of glutaraldehyde within the tissue matrix before the crosslinking reaction is allowed to occur. As a result, materials with improved biological and mechanical properties are expected.

  20. New concept in natural history and management of diabetes mellitus in thalassemia major.

    PubMed

    Chatterjee, Ratna; Bajoria, Rekha

    2009-01-01

    Diabetes Mellitus is a major endocrinopathy, which occurs due transfusional haemosiderosis and is found in 20-30% of adult patients with beta-thalassaemia worldwide, accounting for significant morbidity. It is multifactorial with iron loading being the dominant cause and its management poses a clinical challenge. Diabetes in thalassaemia patients is distinct from type 2 diabetes. It is peculiar in many aspects including its pathophysiology and occurs due to insulin resistance as well as islet cell insufficiency. This article reviews the natural history of diabetes in this presentation with emphasis on prevention monitoring and management. Use of MRI techniques may be useful for future monitoring as well as biochemical monitoring to prevent complications of diabetes. Early intervention with intensified chelation may reverse pancreatic function and structural changes as evident from MRI.

  1. Marginal cost of natural gas in developing countries: concepts and applications

    SciTech Connect

    Mashayekhi, A.

    1983-01-01

    Many developing nations are facing complex questions regarding the best strategy for developing their domestic gas reserves. The World Bank has addressed these questions in studies on the cost and prices of gas and its optimal allocation among different markets. Based on the average incremental method, an estimate of the marginal cost of natural gas in 10 developing countries proved to be $0.61-1.79/1000 CF or $3.59-10.54/bbl of oil equivalent, far below the border prices of competing fuels in these nations. Moreover, the cost of gas is not expected to rise in these countries within the next 20 years while the reserves/production ratios remain high. The sample involves a variety of gas compositions and production conditions among the countries of Bangladesh, Cameroon, Egypt, India, Morocco, Nigeria, Pakistan, Tanzania, Thailand, and Tunisia.

  2. Conception de la nature et manuels de sciences au Quebec, en France et au Senegal

    NASA Astrophysics Data System (ADS)

    Astalos, Monique

    This study examines a view of nature in primary science education at the international level. Currently, in international studies of science programs, this aspect has been rarely considered. A better knowledge of science textbooks would give one a better understanding of the cultural variations between countries, and, would bring more precision to the cultural contexts. The study analyzes a view of nature, particularly the relationships between man and animal found in primary science textbooks in Quebec, France and Senegal. One needs to discern if there are any differences between these countries. The assumptions are based on the primary science textbooks view of nature that essentially takes an anthropocentric view, but with some variations between cultures. This research is primarily exploratory since this phenomena has been studied only minimally. The problem is examined within each country. The types of relationships between man and animal have been identified and the textbooks have been compared with each other. Similarities and differences are then presented between textbooks of the countries under study. This section also includes an interpretation phase of the possible origins of the types of relationships between man and animal in the textbooks concerned. The results enable one to update the different types of relationships between man and animal found in the science textbooks under scrutiny. Nine types of relationships have been identified. They are: (1) naturalistic; (2) ecologistic; (3) humanistic; (4) moralistic; (5) scientific; (6) aesthetic; (7) utilitarian; (8) dominionistic; and (9) negativistic. The absence of certain categories in some textbooks raises questions on the universality of the values suggested by Kellert's typology (1985). The pre-eminence of the "scientific" category suggests a definite relation with this type of textbook, but also with the general anthropocentric trend generally found in science education. The differences found in

  3. Interactions Between Mathematics and Physics: The History of the Concept of Function—Teaching with and About Nature of Mathematics

    NASA Astrophysics Data System (ADS)

    Kjeldsen, Tinne Hoff; Lützen, Jesper

    2015-07-01

    In this paper, we discuss the history of the concept of function and emphasize in particular how problems in physics have led to essential changes in its definition and application in mathematical practices. Euler defined a function as an analytic expression, whereas Dirichlet defined it as a variable that depends in an arbitrary manner on another variable. The change was required when mathematicians discovered that analytic expressions were not sufficient to represent physical phenomena such as the vibration of a string (Euler) and heat conduction (Fourier and Dirichlet). The introduction of generalized functions or distributions is shown to stem partly from the development of new theories of physics such as electrical engineering and quantum mechanics that led to the use of improper functions such as the delta function that demanded a proper foundation. We argue that the development of student understanding of mathematics and its nature is enhanced by embedding mathematical concepts and theories, within an explicit-reflective framework, into a rich historical context emphasizing its interaction with other disciplines such as physics. Students recognize and become engaged with meta-discursive rules governing mathematics. Mathematics teachers can thereby teach inquiry in mathematics as it occurs in the sciences, as mathematical practice aimed at obtaining new mathematical knowledge. We illustrate such a historical teaching and learning of mathematics within an explicit and reflective framework by two examples of student-directed, problem-oriented project work following the Roskilde Model, in which the connection to physics is explicit and provides a learning space where the nature of mathematics and mathematical practices are linked to natural science.

  4. New concept of solute distribution around a diffusive crystal-solution interface of a binary Lennard-Jones mixture from the viewpoint of molecular dynamics.

    PubMed

    Maeda, Kouji; Asakuma, Yusuke; Fukui, Keisuke

    2008-01-28

    Directional crystallization from a binary mixture was performed by pseudo-NpT ensemble molecular dynamics. The initial crystal phase having a face-centered-cubic (fcc) structure grew toward the whole cell according to the temperature gradient in the universal cell. The growing crystal phase was not planar even though the solute molecules grew in two-dimensional coordinates because the solvent molecules disturbed the crystallization of the solute molecules at the diffusive crystal-solution interface. This represented the essential phenomenon of solute distribution during crystallization. Consequently, the growing crystal phase still contained solvent molecules having a liquid structure. The time change of the solute composition in the early phase of crystal growth showed an increase in solute composition as the time step proceeded. The resulting solute composition in this early phase was considered at different temperature gradients in the universal cell and it increased as the temperature of the initial crystal-solution interface increased. A new distribution coefficient model was proposed as a function of the difference between the local solute composition and bulk solute composition in the solution around the crystal-solution interface. The impurity-solvent distribution coefficient could be represented by the new model for faster growth of the lower temperature's initial interface. As regards a better distribution coefficient, there was found to be a very dilute solution phase over the crystal phase. The new variable "distribution rate" instead of the ambiguous variable "growth rate" was considered as a function of temperature gradient in the universal cell.

  5. High-accuracy bench mark solutions to natural convection in a square cavity

    NASA Astrophysics Data System (ADS)

    Saitoh, T.; Hirose, K.

    1989-11-01

    A fourth-order high-accuracy finite difference method is presented for the bouyancy-driven flow in a square cavity with differentially heated vertical walls. The two bench mark solutions against which other solutions can be compared were obtained. The present solution is seemed to be accurate up to fifth decimal. The proposed scheme is stable and convergent for high Rayleigh number, and will be applicable to general problems involving flow and heat transfer, especially in three dimensions.

  6. U.S. natural resources and climate change: concepts and approaches for management adaptation.

    PubMed

    West, Jordan M; Julius, Susan H; Kareiva, Peter; Enquist, Carolyn; Lawler, Joshua J; Petersen, Brian; Johnson, Ayana E; Shaw, M Rebecca

    2009-12-01

    Public lands and waters in the United States traditionally have been managed using frameworks and objectives that were established under an implicit assumption of stable climatic conditions. However, projected climatic changes render this assumption invalid. Here, we summarize general principles for management adaptations that have emerged from a major literature review. These general principles cover many topics including: (1) how to assess climate impacts to ecosystem processes that are key to management goals; (2) using management practices to support ecosystem resilience; (3) converting barriers that may inhibit management responses into opportunities for successful implementation; and (4) promoting flexible decision making that takes into account challenges of scale and thresholds. To date, the literature on management adaptations to climate change has mostly focused on strategies for bolstering the resilience of ecosystems to persist in their current states. Yet in the longer term, it is anticipated that climate change will push certain ecosystems and species beyond their capacity to recover. When managing to support resilience becomes infeasible, adaptation may require more than simply changing management practices--it may require changing management goals and managing transitions to new ecosystem states. After transitions have occurred, management will again support resilience--this time for a new ecosystem state. Thus, successful management of natural resources in the context of climate change will require recognition on the part of managers and decisions makers of the need to cycle between "managing for resilience" and "managing for change."

  7. Improving Students' Understanding of the Connections between the Concepts of Real-Gas Mixtures, Gas Ideal-Solutions, and Perfect-Gas Mixtures

    ERIC Educational Resources Information Center

    Privat, Romain; Jaubert, Jean-Noël; Moine, Edouard

    2016-01-01

    In many textbooks of chemical-engineering thermodynamics, a gas mixture obeying the fundamental law pV[subscript m] = RT is most often called ideal-gas mixture (in some rare cases, the term perfect-gas mixture can be found). These textbooks also define the fundamental concept of ideal solution which in theory, can be applied indifferently to…

  8. Improving Students' Understanding of the Connections between the Concepts of Real-Gas Mixtures, Gas Ideal-Solutions, and Perfect-Gas Mixtures

    ERIC Educational Resources Information Center

    Privat, Romain; Jaubert, Jean-Noël; Moine, Edouard

    2016-01-01

    In many textbooks of chemical-engineering thermodynamics, a gas mixture obeying the fundamental law pV[subscript m] = RT is most often called ideal-gas mixture (in some rare cases, the term perfect-gas mixture can be found). These textbooks also define the fundamental concept of ideal solution which in theory, can be applied indifferently to…

  9. An Analysis of 16-17-Year-Old Students' Understanding of Solution Chemistry Concepts Using a Two-Tier Diagnostic Instrument

    ERIC Educational Resources Information Center

    Adadan, Emine; Savasci, Funda

    2012-01-01

    This study focused on the development of a two-tier multiple-choice diagnostic instrument, which was designed and then progressively modified, and implemented to assess students' understanding of solution chemistry concepts. The results of the study are derived from the responses of 756 Grade 11 students (age 16-17) from 14 different high schools…

  10. Nature-based solutions for urban landscapes under post-industrialization and globalization: Barcelona versus Shanghai.

    PubMed

    Fan, Peilei; Ouyang, Zutao; Basnou, Corina; Pino, Joan; Park, Hogeun; Chen, Jiquan

    2017-07-01

    Using Barcelona and Shanghai as case studies, we examined the nature-based solutions (NBS) in urban settings-specifically within cities experiencing post-industrialization and globalization. Our specific research questions are: (1) What are the spatiotemporal changes in urban built-up land and green space in Barcelona and Shanghai? (2) What are the relationships between economic development, exemplified by post-industrialization, globalization, and urban green space? Urban land use and green space change were evaluated using data derived from a variety of sources, including satellite images, landscape matrix indicators, and a land conversion matrix. The relationships between economic development, globalization, and environmental quality were analyzed through partial least squares structural equation modeling based on secondary statistical data. Both Barcelona and Shanghai have undergone rapid urbanization, with urban expansion in Barcelona beginning in the 1960s-1970s and in Shanghai in the last decade. While Barcelona's urban green space and green space per capita began declining between the 1950s and 1990s, they increased slightly over the past two decades. Shanghai, however, has consistently and significantly improved urban green space and green space per capita over the past six decades, especially since the economic reform in 1978. Economic development has a direct and significant influence on urban green space for both cities and post-industrialization had served as the main driving force for urban landscape change in Barcelona and Shanghai. Based on secondary statistical and qualitative data from on-site observations and interviews with local experts, we highlighted the institution's role in NBS planning. Furthermore, aspiration to become a global or globalizing city motivated both cities to use NBS planning as a place-making tool to attract global investment, which is reflected in various governing policies and regulations. The cities' effort to achieve a

  11. Aqueous photochemical degradation of BDE-153 in solutions with natural dissolved organic matter.

    PubMed

    Wang, Huili; Wang, Mei; Wang, Hui; Gao, Jiajia; Dahlgren, Randy A; Yu, Qing; Wang, Xuedong

    2016-07-01

    The compound 2,2',4,4',5,5'-hexabrominated diphenyl ether (BDE-153) is an intermediate photolytic product in the degradation of highly brominated diphenyl ethers to lower brominated forms. Herein, we report the effects of two natural organic matter (NOM) sources, Suwannee River fulvic acid (SRFA) and Pony Lake fulvic acid (PLFA), on BDE-153 photolysis in water. The rate constant (k) and half-life of BDE-153 was 2.26 × 10(-2) min(-1) and 30.72 min under UV-Vis irradiation (direct photolysis at λ > 290 nm). The k value for BDE-153 decreased markedly in the presence of NOM with a larger decrease in the presence of PLFA than SRFA. Electron spin resonance (ESR) demonstrated generation of free radicals in the photolytic process that mainly involved (1)O2 and OH. The biomolecular k values for reaction of (1)O2 and OH with BDE-153 were 3.65 × 10(6) and 7.70 × 10(8) M(-1) s(-1), respectively. The contribution of OH (28.7-31.0%) to the indirect photolysis of BDE-153 was higher than for (1)O2 (12.9-14.9%). The photolytic rate of BDE-153 in oxygen-rich (aerated) solution was much slower than in oxygen-poor (nitrogen-sparged) conditions, demonstrating that (3)NOM* is a more effective reagent for degradation of BDE-153 than (1)O2. Addition of sorbic acid (a (3)NOM* quencher) significantly reduced the photolytic rate of BDE-153 confirming the important role of (3)NOM* in indirect photolysis. In the presence of NOM, BDE-153 indirect photolysis was facilitated mainly by reaction with (3)NOM* and OH. To the best of our knowledge, this is the first comprehensive investigation of indirect photolysis of BDE-153 in water containing NOM. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. The nature of aqueous solutions: insights into multiple facets of chemistry and biochemistry from freezing-point depressions.

    PubMed

    Zavitsas, Andreas A

    2010-05-25

    Contrary to current widely held beliefs, many concentrated aqueous solutions of electrolytes and nonelectrolytes behave ideally. For both, the same simple equation yields mole fractions of water that are equal to the theoretical activities of water. No empirical activity coefficients or ad hoc parameters are needed. Thermodynamic hydration numbers and the number of particles produced per mole of solute are found by searching freezing-point depression measurements, as if asking the water, "How much available water solvent is left and how many solute particles are there?" The results answer questions currently under debate: Do solutes alter the nature of water outside their immediate surroundings? What is the number of ion pairs formed by various electrolytes and what affects extents of their formation? What are some factors that cause precipitation of proteins, latexes, and so forth from aqueous solutions upon addition of other solutes (Hofmeister series)? Which nonelectrolytes form aggregates in water and what are the implications? Why do different solutes affect viscosity differently? How do ion-selective channels in cell membranes function at the molecular level?

  13. Dynamics of water solutions of natural polysaccharides by fast field cycling nmr relaxometry

    NASA Astrophysics Data System (ADS)

    Prusova, Alena; Conte, Pellegrino; Kucerik, Jiri; de Pasquale, Claudio; Alonzo, Giuseppe

    2010-05-01

    second hydration shell contains water molecules, also recognized as partly-bound (PBW), which are not directly interacting with the hyaluronan chains but with BW. Finally, water molecules, which dynamics is resembling that of the pure and undisturbed water, are indicated either as a bulk water or free water (FW). As hyaluronan concentration is increased the third FW hydration shell is lost and all water molecules are affected by the presence of hyaluronan molecules. This work showed the great potential of FFC-NMR relaxometry in revealing water nature in polysaccharide solutions and the possibility for future applications on complex biological systems. Acknowledgements A.P. gratefully acknowledges a bilateral Erasmus project between Brno University of Technology and University of Palermo which provided grant sustainment for working in Italy. Ministry of Education of the Czech Republic, project MSM 0021630501 is also acknwledged. This work was partially funded by Ce.R.T.A. s.c.r.l. (Centri Regionali per le Tecnologie Alimentari; Italy). Authors kindly acknowledge Dr. Vladimír Velebný (CPN company, Dolní Dobrouč, Czech Republic) for providing of hyaluronan sample.

  14. Evolution of ion emission yield of alloys with the nature of the solute. 2: Interpretation

    NASA Technical Reports Server (NTRS)

    Blaise, G.; Slodzian, G.

    1977-01-01

    Solid solutions of transition elements in copper, nickel, cobalt, iron, and aluminum matrices were analyzed by observing secondary ion emissions under bombardment with 6.2-keV argon ions. Enchancement of the production of solute-element ions was observed. An ion emission model is proposed according to which the ion yield is governed by the probability of an atom leaving the metal in a preionized state. The energy distribution of the valence electrons of the solute atoms is the bases of the probability calculation.

  15. Considering Hans-Georg Gadamer's philosophical hermeneutics as a referent for student understanding of nature-of-science concepts

    NASA Astrophysics Data System (ADS)

    Rashford, Jared M.

    The purpose of this study is to examine philosophical hermeneutics as a referent for student understanding of Nature-of-Science (NOS) concepts. Rather than focus on a prescriptive set of canons used in addressing NOS pedagogy in K-12 schools, this study seeks to explicate a descriptive set of principles based on Hans-Georg Gadamer's theory of interpretation that has the potential for developing dispositions necessary for understanding. Central among these are the concepts of fore-structure, prejudice, temporal distance, and history of effect, all of which constitute part of the whole of the hermeneutic circle as envisaged by Gadamer. As such, Gadamer's hermeneutics is contrasted with Cartesian epistemology and its primacy of method, the Enlightenment's prejudice against prejudice, the modernist/progressive tendency to consider all situations as problems to be solved by relegating all forms of knowledge to techne, and the subjective nature of interpretation inherent in a hermeneutics of suspicion. The implication of such a conceptual analysis for NOS pedagogy is that student understanding is considered not so much as a cognitive outcome dependent on a series of mental functions but rather as an ontological characteristic of Dasein (being-human) that situates learning in the interchange between interpreter and text. In addition, the philosophical foundations implicit in addressing student understanding of NOS found in many curricular reform efforts and pedagogical practices in science education are questioned. Gadamer's hermeneutics affords science education a viable philosophical framework within which to consider student understanding of the development of scientific knowledge and the scientific enterprise.

  16. [Considerations on the concepts of nature, space, and morphology in Alexander von Humboldt and on the genesis of modern physical geography].

    PubMed

    Vitte, Antonio Carlos; Silveira, Roberison Wittgenstein Dias da

    2010-01-01

    The article discusses how Alexander von Humboldt developed the concepts of nature, space, and morphology in his works and impacted the shaping of modern physical geography. Influenced by Kant's ideas in Critique of judgment and also by the writings of Goethe and Schelling, Humboldt devised a new interpretation and representation of nature on Earth's surface, wherein the concept of space is essential to explaining natural phenomena. Modern physical geography is grounded in a complex interweaving of aesthetic and instrumental influences fashioned by Humboldt, with the principle of connection playing an important role in the artistic and scientific development of the notion of a geographic landscape.

  17. Neonatal and obstetric outcomes of in vitro fertilization (IVF) and natural conception at a Chinese reproductive unit.

    PubMed

    Liu, J; Linara, E; Zhao, W; Ma, H; Ahuja, K; Wang, J

    2015-01-01

    In vitro fertilization (lVF) has been associated with an increased risk of preterm delivery, caesarean delivery, low and very low birth-weight infants. The authors investigated the possible high risks of adverse health outcomes in infants conceived using IVF and intracytoplasmic sperm injection (ICSI). The present study includes 443 infants born to 424 women who conceived naturally and 694 infants born to 536 women that had IVF or ICSI. The study was conducted in the Department of Obstetrics at the Yu Huang Ding Hospital from 2008 to 2009. The main outcome measures were:gestational age, birth weight, mode of delivery, multiple pregnancy rates, and baby gender. The results showed significant differences between the neonatal and obstetric outcomes of IVF/ICSI and natural conception pregnancies. When referred to singletons only, there were no major differences seen in the neonatal and obstetric outcomes between the IVF and the control group.When the IVF group was divided into two sub-groups according to the patient's age (< 35 and > or = 35 years), there was no statistically significant difference between the two groups in the observed outcomes.

  18. Natural conception following total fertilization failure with intracytoplasmic sperm injection in a couple with unexplained infertility: a case report.

    PubMed

    Codreanu, Dorina; Coricovac, Anca; Mirzan, Luminita; Dracea, Laura; Marinescu, B; Boleac, I

    2013-01-01

    With the introduction of intracytoplasmic sperm injection (ICSI), couples with severe male factor infertility have been able to achieve fertilization and clinical pregnancy rates comparable to other in vitro fertilization patients. However, despite the utilization of microsurgical sperm injection techniques, failure of fertilization still occurs in a few patients. How such fertilization failure after ICSI might impact later ICSI treatments is less understood. We report a case of total fertilization failure after ICSI using sperm from a normozoospermic husband of a patient with unexplained infertility. Six months after the cancelled cycle, the couple conceived naturally. Unfortunately, it was an ectopic pregnancy, which required laparoscopy and surgical removal of the right fallopian tube. This case shows that a failed ICSI cycle, therefore, does not imply a hopeless prognosis for future ICSI treatment. Moreover, in cases with unexplained ICSI failure, natural conception can subsequently occur. The aim of this study is two-fold: to discuss a rare case of a spontaneous pregnancy after total fertilization failure with ICSI and to develop counseling material for patients and doctors who are faced with such a rare situation. To our knowledge, this is the first report of a case of spontaneous pregnancy after total fertilization failure with ICSI.

  19. Changing Preservice Science Teachers' Views of Nature of Science: Why Some Conceptions May be More Easily Altered than Others

    NASA Astrophysics Data System (ADS)

    Mesci, Gunkut; Schwartz, Renee'S.

    2017-04-01

    The purpose of this study was to assess preservice teachers' views of Nature of Science (NOS), identify aspects that were challenging for conceptual change, and explore reasons why. This study particularly focused on why and how some concepts of NOS may be more easily altered than others. Fourteen preservice science teachers enrolled in a NOS and Science Inquiry course participated in this study. Data were collected by using a pre/post format with the Views of Nature of Science questionnaire (VNOS-270), the Views of Scientific Inquiry questionnaire (VOSI-270), follow-up interviews, and classroom artifacts. The results indicated that most students initially held naïve views about certain aspects of NOS like tentativeness and subjectivity. By the end of the semester, almost all students dramatically improved their understanding about almost all aspects of NOS. However, several students still struggled with certain aspects like the differences between scientific theory and law, tentativeness, and socio-cultural embeddedness. Results suggested that instructional, motivational, and socio-cultural factors may influence if and how students changed their views about targeted NOS aspects. Students thought that classroom activities, discussions, and readings were most helpful to improve their views about NOS. The findings from the research have the potential to translate as practical advice for teachers, science educators, and future researchers.

  20. Changing Preservice Science Teachers' Views of Nature of Science: Why Some Conceptions May be More Easily Altered than Others

    NASA Astrophysics Data System (ADS)

    Mesci, Gunkut; Schwartz, Renee'S.

    2016-02-01

    The purpose of this study was to assess preservice teachers' views of Nature of Science (NOS), identify aspects that were challenging for conceptual change, and explore reasons why. This study particularly focused on why and how some concepts of NOS may be more easily altered than others. Fourteen preservice science teachers enrolled in a NOS and Science Inquiry course participated in this study. Data were collected by using a pre/post format with the Views of Nature of Science questionnaire (VNOS-270), the Views of Scientific Inquiry questionnaire (VOSI-270), follow-up interviews, and classroom artifacts. The results indicated that most students initially held naïve views about certain aspects of NOS like tentativeness and subjectivity. By the end of the semester, almost all students dramatically improved their understanding about almost all aspects of NOS. However, several students still struggled with certain aspects like the differences between scientific theory and law, tentativeness, and socio-cultural embeddedness. Results suggested that instructional, motivational, and socio-cultural factors may influence if and how students changed their views about targeted NOS aspects. Students thought that classroom activities, discussions, and readings were most helpful to improve their views about NOS. The findings from the research have the potential to translate as practical advice for teachers, science educators, and future researchers.

  1. Development of a model to predict the adsorption of lead from solution on a natural streambed sediment

    USGS Publications Warehouse

    Brown, David Wayne; Hem, John David

    1984-01-01

    Adsorption of solutes by solid mineral surfaces commonly influences the dissolved ionic composition of natural waters. A model based on electrical double-layer theory has been developed which appears to be capable of characterizing the surface chemical behavior of a natural fine-grained sediment containing mostly quartz and feldspar. This variable surface charge-variable surface potential (VSC-VSP) model differs from others in being capable of evaluating more closely the effect of total metal ion activity on the pH-dependent change in electrical potential at the solid surface. The model was tested using 10-4 molar solutions of lead and a silt-size fraction of sediment from the bed of Colma Creek, a small stream in urban northern San Mateo County, California. The average deviation of measured percent adsorption and values calculated from the model was 6.6 adsorption percent from pH 2.0 to pH 7.0.

  2. Darwinian agriculture: when can humans find solutions beyond the reach of natural selection?

    PubMed

    Denison, R Ford; Kiers, E Toby; West, Stuart A

    2003-06-01

    Progress in genetic improvement of crop yield potential has slowed since 1985. Simultaneously, more sustainable management of agricultural ecosystems is needed. A better understanding of natural selection can help solve both problems. We illustrate this point with two specific examples. First, the genetic legacy of crop plants has been refined by millions of years of natural selection, often driven by competition among plants. We therefore suggest that most simple, tradeoff-free options to increase competitiveness (e.g., increased gene expression, or minor modifications of existing plant genes) have already been tested by natural selection. Further genetic improvement of crop yield potential over the next decade will mainly involve tradeoffs, either between fitness in past versus present environments, or between individual competitiveness and the collective performance of plant communities. Eventually, we may develop the ability to predict the consequences of genetic alterations so radical that they have not yet been tested by natural selection. Second, natural selection acts mainly at the level of genes, individuals, and family groups, rather than ecosystems as a whole. Consequently, there is no reason to expect the structure of natural ecosystems (diversity, spatial, or temporal patterns) to be a reliable blueprint for agricultural ecosystems. Natural ecosystems are nonetheless an important source of information that could be used to improve agriculture.

  3. Natural solutal convection in magnetic fluids: First-order phase transition aspect

    NASA Astrophysics Data System (ADS)

    Ivanov, Aleksey S.

    2016-10-01

    Concentration stratification of magnetic fluids under the action of external magnetic field can disturb mechanical equilibrium in the system and cause intensive solutal convection. The current paper is devoted to the study of free solutal convection in magnetic fluids undergoing first-order phase transition. Simulation of solutal convection in OpenFOAM package makes it possible to compare numeric results with physical experiment observations. The numeric simulation of convective hydrodynamic flows was carried out in the framework of several theories of first-order phase transition in ferrocolloids. The numerical results are compared with experimental observations in order to choose the theory which predicts most accurately the concentration stratification in magnetic fluids undergoing magneto-controllable first-order phase transition.

  4. Evaluating the potential of multi-purpose nature based solutions in peri-urban landscapes - a preliminary assessment

    NASA Astrophysics Data System (ADS)

    Geris, Josie; Wilkinson, Mark; Stutter, Marc; Guenther, Daniel; Soulsby, Chris

    2016-04-01

    Many communities across the world face the increasing challenge of balancing water quantity and quality protection and improvement with accommodating new growth and urban development. Urbanisation is typically associated with detrimental changes in water quality, sediment delivery, and effects on water storage and flow pathways (e.g. increases in flooding). Current mitigation solutions are typically based on isolated design strategies used at specific small scale sites and for storm water only. More holistic catchment scale approaches are urgently required to effectively manage the amount of water flows and protect the raw water quality in peri-urban landscapes. This project aims to provide a better understanding of the connectivity between natural and managed flow pathways, storage, and biogeochemical processes in the peri-urban landscape to eventually aid a more integrated water quantity and quality control design. For an actively urbanising catchment in NE Scotland we seek to understand the spatio-temporal character of the natural flow pathways and associated water quality, and how these may be used to support the design of nature based solutions during urbanisation. We present preliminary findings from a dense and multiscale monitoring network that includes hydrometric, tracer (stable water isotopes) and water quality (turbidity (sediment), nitrate, phosphate) data during a range of contrasting hydroclimatological conditions and at different stages of the development of urban infrastructure. These demonstrate a highly variable nature, both temporally and spatially, with water quality dynamics out of sync with storm responses and depending on management practices. This highlights potential difficulties for managing water quantity and quality simultaneously at the catchment scale, and suggests that a treatment train approach may be required. Well-designed nature based solutions that tackle both water quantity and quality issues will require adaptability and a

  5. Synthesis of hydrochloric acid solution for total mercury determination in natural waters.

    PubMed

    Patel-Sorrentino, Nathalie; Benaim, Jean-Yves; Cossa, Daniel; Lucas, Yves

    2011-01-01

    Total mercury (Hg(T)) determination requires the addition of concentrated hydrochloric acid solution (≥10 mol L(-1) HCl) in relatively high amounts to preserve the samples and to prepare reagent solutions. A method for the preparation of concentrated HCl with Hg(T) concentration of lower than 5 ng L(-1) is described in this article. It is based on the well-known chemical reaction: 2 NH(4)Cl + H(2)SO(4) → (NH(4))(2)SO(4) + 2 HCl. This method is validated thanks to the US Environmental Protection Agency method 1631 and standard reference materials BCR-579 (mercury in coastal seawater).

  6. The nature of enhanced linear and nonlinear optical effects in fullerene solutions

    SciTech Connect

    Sheka, E. F. Razbirin, B. S. Starukhin, A. N.; Nelson, D. K.; Degunov, M. Yu.; Lyubovskaya, R. N.; Troshin, P. A.

    2009-05-15

    The 'blue' emission from fullerene C{sub 60} and its derivatives in frozen toluene solution is discovered and analyzed in the framework of the electromagnetic theory of enhanced optical effects. It is shown that the emission, combining enhanced spectra of Raman scattering and one-photon luminescence, is due to clustering of fullerene molecules in solution. Photoexcitation of charge-transfer excitons in clusters provides the polarization required for the enhancement. A direct relationship is established between the observed phenomenon and nonlinear optical properties of the medium. Empirical and computational tests are proposed to select matrices with various nonlinear optical properties.

  7. A Hypermedia Environment To Explore and Negotiate Students' Conceptions: Animation of the Solution Process of Table Salt.

    ERIC Educational Resources Information Center

    Ebenezer, Jazlin V.

    2001-01-01

    Describes the characteristics and values of hypermedia for learning chemistry. Reports on how a hypermedia environment was used to explore a group of 11th grade chemistry students' conceptions of table salt dissolving in water. Indicates that a hypermedia environment can be used to explore, negotiate, and assess students' conceptions of…

  8. A Comparison of Numerical and Analytical Radiative-Transfer Solutions for Plane Albedo of Natural Waters

    EPA Science Inventory

    Three numerical algorithms were compared to provide a solution of a radiative transfer equation (RTE) for plane albedo (hemispherical reflectance) in semi-infinite one-dimensional plane-parallel layer. Algorithms were based on the invariant imbedding method and two different var...

  9. A Comparison of Numerical and Analytical Radiative-Transfer Solutions for Plane Albedo in Natural Waters

    EPA Science Inventory

    Several numerical and analytical solutions of the radiative transfer equation (RTE) for plane albedo were compared for solar light reflection by sea water. The study incorporated the simplest case, that being a semi-infinite one-dimensional plane-parallel absorbing and scattering...

  10. ON THE DOUBLE NATURED SOLUTIONS OF THE TWO-TEMPERATURE EXTERNAL SOFT PHOTON COMPTONIZED ACCRETION DISKS

    SciTech Connect

    Meirelles Filho, Cesar

    2009-08-01

    We have analyzed pair production in the innermost region of a two-temperature external soft photon Comptonized accretion disk. We have shown that, if the viscosity parameter is greater than a critical value {alpha}{sub c}, the solution to the disk equation is double valued: one, advection dominated, and the other, radiation dominated. When {alpha} {<=} {alpha}{sub c}, the accretion rate has to satisfy m-dot{sub 1}{<=}m-dot{<=}m-dot{sub c} in order to have two steady-state solutions. It is shown that these critical parameters m-dot{sub 1}, m-dot{sub c} are functions of r, {alpha}, and {theta}{sub e}, and {alpha}{sub c} is a function of r and {theta}{sub e}. Depending on the combination of the parameters, the advection-dominated solution may not be physically consistent. It is also shown that the electronic temperature is maximum at the onset of the thermal instability, from which results this inner region. These solutions are stable against perturbations in the electron temperature and in the density of pairs.

  11. A Comparison of Numerical and Analytical Radiative-Transfer Solutions for Plane Albedo in Natural Waters

    EPA Science Inventory

    Several numerical and analytical solutions of the radiative transfer equation (RTE) for plane albedo were compared for solar light reflection by sea water. The study incorporated the simplest case, that being a semi-infinite one-dimensional plane-parallel absorbing and scattering...

  12. Controlling Solute Transport Processes in Soils by using Dual-Porosity Characteristics of Natural Soils

    NASA Astrophysics Data System (ADS)

    Mori, Y.; Higashi, N.

    2009-12-01

    Soils are notorious for their heterogeneity, and macropores conduct solutions by bypassing the surrounding soils, sometimes wasting the applied fertilizer or remediation chemicals. It would be beneficial in agriculture or environmental engineering fields if solute transport in soils were controlled with relatively simple techniques. In this study, the solute transport process was controlled using dual-characteristics of the soil pore system. Specifically convection and dispersion were controlled by changing the structure-dependent flow regime. Soil samples with/without artificial small macropores (diameter = 1mm) and undisturbed soil samples were prepared, and solute transport experiments were conducted, in which a variety of breakthrough curves (BTC) was obtained by changing flow rate (from 1 to 0.1 of saturated conductivity) and saturation (saturation to -3kPa). The results for the artificial macropore system showed that completely different BTCs were obtained with small suction differences, namely saturation and -3kPa. At saturation, the BTC showed a bi-modal distribution typical for soils with macropores. At a slightly unsaturated condition of -3kPa, however, the BTC showed a normal distribution quite similar to that of a repacked soil column. The results for undisturbed soil showed that the BTC gradually transitioned from a bi-modal to normal distribution, with the suction changing from saturation to only -3kPa. These results suggest that effective use of fertilizer or remediation chemicals are possible with a relatively simple and inexpensive technique, even when macropore networks are present.

  13. A Comparison of Numerical and Analytical Radiative-Transfer Solutions for Plane Albedo of Natural Waters

    EPA Science Inventory

    Three numerical algorithms were compared to provide a solution of a radiative transfer equation (RTE) for plane albedo (hemispherical reflectance) in semi-infinite one-dimensional plane-parallel layer. Algorithms were based on the invariant imbedding method and two different var...

  14. Altered DNA methylation and expression of PLAGL1 in cord blood from assisted reproductive technology pregnancies compared with natural conceptions.

    PubMed

    Vincent, Rebecca N; Gooding, Luke D; Louie, Kenny; Chan Wong, Edgar; Ma, Sai

    2016-09-01

    To investigate DNA methylation and expression of imprinted genes and an imprinted gene network (IGN) in neonates conceived via assisted reproductive technology (ART). Case control. Research institution. Two hundred sixty-four cases of cord blood and/or placental villi from neonates (101 IVF, 81 ICSI, 82 naturally conceived). Placentas were obtained at birth for biopsy and cord blood extraction. DNA methylation and expression of imprinted genes. DNA methylation at the PLAGL1 differentially methylated region (DMR) was significantly higher in IVF cord blood (48.0%) compared with controls (46.0%). No differences were found in DNA methylation between conception modes for KvDMR1 and LINE-1 in cord blood and placenta as well as PLAGL1 and PEG10 in placenta villi. PLAGL1 expression was lower in both IVF and ICSI cord blood groups than in controls (relative quantification of 0.65, 0.74, 0.89, respectively). Analyzing the expression of 3 genes in a PLAGL1 regulated IGN revealed different expression between conception modes and a significant correlation to PLAGL1 expression in only one (KCNQ1OT1). Our results suggest a stability of DNA methylation at imprinted DMRs; however, we show PLAGL1 methylation/expression to be altered after ART. As PLAGL1 expression correlated with only one of the three IGN genes in cord blood, we propose there is a more complex mechanism of regulating the IGN that may involve other genes and epigenetic modifications in this tissue. Further research investigating IGN-implicated genes in various neonatal tissues is warranted to elucidate the full effects ART-induced alterations to PLAGL1 and the IGN may have on fetal growth/development. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  15. Natural cork agglomerate employed as an environmentally friendly solution for quiet sandwich composites.

    PubMed

    Sargianis, James; Kim, Hyung-ick; Suhr, Jonghwan

    2012-01-01

    Carbon fiber-synthetic foam core sandwich composites are widely used for many structural applications due to their superior mechanical performance and low weight. Unfortunately these structures typically have very poor acoustic performance. There is increasingly growing demand in mitigating this noise issue in sandwich composite structures. This study shows that marrying carbon fiber composites with natural cork in a sandwich structure provides a synergistic effect yielding a noise-free sandwich composite structure without the sacrifice of mechanical performance or weight. Moreover the cork-core sandwich composites boast a 250% improvement in damping performance, providing increased durability and lifetime operation. Additionally as the world seeks environmentally friendly materials, the harvesting of cork is a natural, renewable process which reduces subsequent carbon footprints. Such a transition from synthetic foam cores to natural cork cores could provide unprecedented improvements in acoustic and vibrational performance in applications such as aircraft cabins or wind turbine blades.

  16. Natural Cork Agglomerate Employed as an Environmentally Friendly Solution for Quiet Sandwich Composites

    PubMed Central

    Sargianis, James; Kim, Hyung-ick; Suhr, Jonghwan

    2012-01-01

    Carbon fiber-synthetic foam core sandwich composites are widely used for many structural applications due to their superior mechanical performance and low weight. Unfortunately these structures typically have very poor acoustic performance. There is increasingly growing demand in mitigating this noise issue in sandwich composite structures. This study shows that marrying carbon fiber composites with natural cork in a sandwich structure provides a synergistic effect yielding a noise-free sandwich composite structure without the sacrifice of mechanical performance or weight. Moreover the cork-core sandwich composites boast a 250% improvement in damping performance, providing increased durability and lifetime operation. Additionally as the world seeks environmentally friendly materials, the harvesting of cork is a natural, renewable process which reduces subsequent carbon footprints. Such a transition from synthetic foam cores to natural cork cores could provide unprecedented improvements in acoustic and vibrational performance in applications such as aircraft cabins or wind turbine blades. PMID:22574250

  17. Experimental study of natural pyrochlore and niobium oxide solubility in Alkaline hydrothermal solutions

    NASA Astrophysics Data System (ADS)

    Korzhinskaya, V. S.; Kotova, N. P.; Shapovalov, Yu. B.

    2017-07-01

    The concentration and temperature dependences of pyrochlore and Nb oxide solubility in Na2CO3 and Na2CO3 + NaF aqueous solutions with concentrations from 0.01 to 2.0 m at 300-550°C and 50 and 100 MPa (the Co-CoO buffer) are studied. It is established that the Nb equilibrium content in the solution increases at 550°C and 100 MPa with an increase in mNa2CO3 and reaches the value of 10-4 m. The Nb2O5 solubility almost does not change as the concentration of Na2CO3 increases and is found within 10-6 to 10-5.5 m.

  18. On the Nature of Singularities in Cosmological Solutions of Einstein's Equations

    NASA Astrophysics Data System (ADS)

    Isenberg, James

    2014-03-01

    The Hawking-Penrose theorems tell us that cosmological solutions of Einstein's equations are generally singular, in the sense of the incompleteness of causal geodesics (the paths of physical observers). These singularities might be marked by the blowup of curvature and therefore crushing tidal forces, or by the breakdown of physical determinism. Penrose has conjectured (in his ``Strong Cosmic Censorship Conjecture'') that it is generically unbounded curvature that causes singularities, rather than causal breakdown. The verification that BKL behavior (marked by the domination of time derivatives over space derivatives) is generically present in a family of solutions has proven to be a useful tool for studying Strong Cosmic Censorship in that family. We discuss what is known about BKL behavior and Strong Cosmic Censorship in families of solutions defined by varying degrees of isometry, and discuss new results which we believe will extend this knowledge and provide new support for Strong Cosmic Censorship. This research has been supported by the NSF under grant PHY 1306441.

  19. Improving the integration of recreation management with management of other natural resources by applying concepts of scale from ecology.

    PubMed

    Morse, Wayde C; Hall, Troy E; Kruger, Linda E

    2009-03-01

    In this article, we examine how issues of scale affect the integration of recreation management with the management of other natural resources on public lands. We present two theories used to address scale issues in ecology and explore how they can improve the two most widely applied recreation-planning frameworks. The theory of patch dynamics and hierarchy theory are applied to the recreation opportunity spectrum (ROS) and the limits of acceptable change (LAC) recreation-planning frameworks. These frameworks have been widely adopted internationally, and improving their ability to integrate with other aspects of natural resource management has significant social and conservation implications. We propose that incorporating ecologic criteria and scale concepts into these recreation-planning frameworks will improve the foundation for integrated land management by resolving issues of incongruent boundaries, mismatched scales, and multiple-scale analysis. Specifically, we argue that whereas the spatially explicit process of the ROS facilitates integrated decision making, its lack of ecologic criteria, broad extent, and large patch size decrease its usefulness for integration at finer scales. The LAC provides explicit considerations for weighing competing values, but measurement of recreation disturbances within an LAC analysis is often done at too fine a grain and at too narrow an extent for integration with other recreation and resource concerns. We suggest that planners should perform analysis at multiple scales when making management decisions that involve trade-offs among competing values. The United States Forest Service is used as an example to discuss how resource-management agencies can improve this integration.

  20. Monitoring of learning at the category level when learning a natural concept: will task experience improve its resolution?

    PubMed

    Tauber, Sarah K; Dunlosky, John

    2015-02-01

    Researchers have recently begun to investigate people's ability to monitor their learning of natural categories. For concept learning tasks, a learner seeks to accurately monitor learning at the category level - i.e., to accurately judge whether exemplars will be correctly classified into the appropriate category on an upcoming test. Our interest was in whether monitoring resolution at the category level would improve as participants gain task experience across multiple study-test blocks, as well as within each block. In four experiments, exemplar birds (e.g., American Goldfinch, Cassin's Finch) paired with each family name (e.g., Finch) were studied, and participants made a judgment of learning (JOL) for each exemplar. Of most interest, before and after studying the exemplars, participants made category learning judgments (CLJs), which involved predicting the likelihood of correctly classifying novel birds into each family. Tests included exemplars that had been studied or exemplars that had not been studied (novel). This procedure was repeated for either one or two additional blocks. The relative accuracy of CLJs did not improve across blocks even when explicit feedback was provided, whereas item-by-item JOL accuracy improved across blocks. Category level resolution did improve from pre-study to post-study on an initial block, but it did not consistently increase within later blocks. The stable accuracy of CLJs across blocks poses a theoretical and empirical challenge for identifying techniques to improve people's ability to judge their learning of natural categories. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. A natural solution for obesity: bioactives for the prevention and treatment of weight gain. A review.

    PubMed

    Torres-Fuentes, Cristina; Schellekens, Harriët; Dinan, Timothy G; Cryan, John F

    2015-02-01

    Obesity and obesity-related disorders are reaching epidemic proportions worldwide. In this review, we summarize the accumulating studies that have emerged in the last few decades demonstrating that bioactives from different natural sources could potentially have anti-obesity effects. We carried out an extensive search of relevant literature from Pubmed, Web of Knowledge, and other online databases for studies where anti-obesity effects were shown by compounds from natural sources. Appetite suppression, lipid metabolism regulation, and increase of energy expenditure are the main mechanisms by which anti-obesity effects are exerted. Plants represent the most studied natural source of anti-obesity bioactives. Camellia sinensis is the most representative species exerting several anti-obesity effects. Moreover, probiotics (bacteria which bestow health benefit), such as strains of Bifidobacteria and Lactobacillus families, and certain prebiotics (non-viable food components that confers a health benefit on the host associated with modulation of the microbiota effects), such as insulin-type fructans, have also shown capability to combat obesity. Finally, compounds from animal sources, in particular bioactive peptides derived from milk-derived whey and casein protein digestion, high dietary calcium, and omega-3s polyunsaturated fatty acids (n-3 PUFA) present in fish oils, have also shown potential anti-obesity effects. Several anti-obesity effects have been observed in different natural bioactives providing an interesting and potentially safer and more desirable treatment strategy for the development of anti-obesity functional or medical foods.

  2. The Dual Nature of Staffing in the Education Library: Management Issues and Solutions

    ERIC Educational Resources Information Center

    Osa, Justina O.

    2003-01-01

    The dual nature of staffing in the education library, just as in most academic libraries, often constitutes a major source of management problems. The blurring and shifting of tasks for professionals and paraprofessionals, and budgetary constraints do not help the situation. Professionals and paraprofessionals must work in concert and in harmony,…

  3. Biosorption of cadmium (II) from aqueous solutions by natural and modified non-living leaves of Posidonia oceanica.

    PubMed

    Meseguer, Víctor F; Ortuño, Juan F; Aguilar, M Isabel; Pinzón-Bedoya, Martha L; Lloréns, Mercedes; Sáez, José; Pérez-Marín, Ana B

    2016-12-01

    Natural, HCl-treated, and formaldehyde-treated non-living leaves of Posidonia oceanica, a marine plant, were investigated as potential biosorbents to remove Cd(2+) from aqueous solutions. The studied biosorbents were characterized by elemental analysis and Fourier transform infrared spectroscopy (FTIR) and it was observed that the adsorption capacity of the biosorbents strongly depended on the pH, increasing as the pH rises. The adsorption process was fast. The adsorption kinetic was analyzed using five kinetic models: pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion, and Bangham models. The adsorption isotherms were analyzed by the Langmuir, Freundlich, Dubinin-Radushkevich, Sips, Redlich-Peterson, and Toth models. The maximum biosorption capacity was attained by the biosorbent treated with HCl (1.11 mmol g(-1)). The distribution equilibrium constant and the Gibbs free energy change were calculated. The effects of the presence of Na(+), K(+), Mg(2+), and Ca(2+) ions in the solution on Cd(2+) uptake were studied. Results indicate that non-living leaves of P. oceanica, natural or treated, can be considered as effective and low-cost biosorbents for the removal of cadmium from aqueous solutions.

  4. Sorption of vanadium (V) onto natural soil colloids under various solution pH and ionic strength conditions.

    PubMed

    Luo, Xiuhua; Yu, Lin; Wang, Changzhao; Yin, Xianqiang; Mosa, Ahmed; Lv, Jialong; Sun, Huimin

    2017-02-01

    Batch sorption kinetics and isothermal characteristics of V(V) were investigated on three natural soil colloids (manual loessial soil colloid (MSC), aeolian sandy soil colloid (ASC), and cultivated loessial soil colloid (CSC)) under various solution pH and ionic strength (IS) conditions. Colloids were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). AFM micrographs showed CSC with an aggregated shape with larger particle diameter as compared with ASC and MSC. XRD spectra revealed the presence of different minerals in natural soil colloids including biotite, kaolinite, calcite and quartz, which might contribute to sorption process. The sorption ability decreased with increase of colloidal particle size. The sorption was mainly attributed to complexation by active carboxylate and alcohol groups of colloidal components. Sorption kinetics and isotherms of V(V) onto natural soil colloids were best fitted with Pseudo-second-order and Freundlich models. Langmuir model indicated that sorption capacity of MSC and ASC was comparable (285.7 and 238.1 mg g(-1)); however, CSC exhibited the lowest sorption capacity (41.5 mg g(-1)) due to its larger particle diameter and aggregated shape. The maximum V(V) sorption capacity reached plateau values at a solution pH ranged between 5.0 and 9.0 for MSC and ASC, and 6.0-8.0 for CSC. Sorption capacity of V(V) onto natural soil colloids decreased with increasing IS. Based on result of this study we can conclude that sorption of V(V) onto natural soil colloids is pH- and IS-dependent. These findings provide insights on the remediation of vanadium-contaminated soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Nature-based solutions for hydro-meteorological risk reduction and nutrient removal in the Nordic and Arctic regions

    NASA Astrophysics Data System (ADS)

    Bring, Arvid; Kalantari, Zahra

    2017-04-01

    Natural ecological functions provide essential and fundamental benefits to mankind, but can also be actively employed in nature-based solutions to specific challenges in society. For example, water-related ecosystem services have a role in such societal benefits as flood protection, erosion control, and excess nutrient removal. Ecosystem services may be produced and consumed in different locations, and research has recently attempted to formalize this discrepancy in identifying service providing areas (SPAs), service benefitting areas (SBAs), and service connecting areas (SCAs). However, in terms of water-related services, there is a lack of formal evaluation of how SPAs, SBAs, and SCAs are related to hydrological measures such as discharge, flood recurrence, excess nutrient removal, etc. We seek to map SPAs, SBAs and SCAs for a number of key ecosystem services in the Nordic and Arctic region though established ecological definitions (typically, based on land use) and evaluate the findings alongside metrics of hydrological connectivity (river networks), provisioning areas (runoff generating areas), and benefitting areas (river stretches where water flow is moderated). We make use of extensive GIS analysis using both high-resolution land cover data and river network maps. In the end, the results are expected to contribute to identifying how water-related ecosystem services can be employed as nature-based solutions for hydro-meteorological risk reduction and nutrient removal in a changing climate in the Nordic and Arctic regions.

  6. The role of food-security solutions in the protection of natural resources and environment of developing countries.

    PubMed

    Lashgarara, Farhad; Mirdamadi, Seyyed Mehdi; Hosseini, Seyyed Jamal Farajollah; Chizari, Mohammad

    2008-10-01

    The majority of the countries of the world, especially developing countries, face environmental problems. Limitations of basic resources (water and soil) and population growth have been the cause of these environmental problems that countries are confronted with. Developing countries have numerous problems, including destruction of forests, vegetable and animal species, and pollution of the environment. Damage to natural resources and the environment can influence the food-security situation. One of the main millennium development goals (MDGs) is protection of the environment and people's health. This cannot obtained unless there is ensured food security. Food security has been defined as a situation when all people, at all times, have physical and economic access to sufficient, safe, and nutritious food needed to maintain a healthy and active life. At the same time, with ensured food security, we can hope to protect the natural resources and environment. The methodology used is descriptive-analytical, and its main purpose is determining the importance and role of food-security solutions in the reduction of environmental hazards and improvement of natural resources and the environmental situation in developing countries. Therefore, some of the most important food-security solutions that can play an important role in this relation were discussed, including conventional research-based technology, biotechnology, information and communication technologies (ICTs), alternative energy sources, and food irradiation.

  7. Employing inquiry-based computer simulations and embedded scientist videos to teach challenging climate change and nature of science concepts

    NASA Astrophysics Data System (ADS)

    Cohen, Edward Charles

    . The students in the video group had marked improvement compared to the non-video group on questions regarding modeling as a tool for representing objects and processes of science modeling aspects as evident by multiple data sources. The findings from the dissertation have potential impacts on improving Nature of Science (NOS) concepts around modeling by efficiently embedding short authentic scientific videos that can be easily used by many educators. Compared to published assessments by the American Association for the Advancement of Science (AAAS), due to the curriculum interventions both groups scored higher than the average United States middle school student on many NOS and climate content constructs.

  8. Employing Inquiry-Based Computer Simulations and Embedded Scientist Videos To Teach Challenging Climate Change and Nature of Science Concepts

    NASA Astrophysics Data System (ADS)

    Cohen, E.

    2013-12-01

    . The students in the video group had marked improvement compared to the non-video group on questions regarding modeling as a tool for representing objects and processes of science modeling aspects as evident by multiple data sources. The findings from the dissertation have potential impacts on improving Nature of Science (NOS) concepts around modeling by efficiently embedding short authentic scientific videos that can be easily used by many educators. Compared to published assessments by the American Association for the Advancement of Science (AAAS), due to the curriculum interventions both groups scored higher than the average United States middle school student on many NOS and climate content constructs.

  9. The ubiquitous nature of accessory calcite in granitoid rocks: Implications for weathering, solute evolution, and petrogenesis

    USGS Publications Warehouse

    White, A.F.; Schulz, M.S.; Lowenstern, J. B.; Vivit, D.V.; Bullen, T.D.

    2005-01-01

    Calcite is frequently cited as a source of excess Ca, Sr and alkalinity in solutes discharging from silicate terrains yet, no previous effort has been made to assess systematically the overall abundance, composition and petrogenesis of accessory calcite in granitoid rocks. This study addresses this issue by analyzing a worldwide distribution of more than 100 granitoid rocks. Calcite is found to be universally present in a concentration range between 0.028 to 18.8 g kg-1 (mean = 2.52 g kg-1). Calcite occurrences include small to large isolated anhedral grains, fracture and cavity infillings, and sericitized cores of plagioclase. No correlation exists between the amount of calcite present and major rock oxide compositions, including CaO. Ion microprobe analyses of in situ calcite grains indicate relatively low Sr (120 to 660 ppm), negligible Rb and 87Sr/86Sr ratios equal to or higher than those of coexisting plagioclase. Solutes, including Ca and alkalinity produced by batch leaching of the granitoid rocks (5% CO2 in DI water for 75 d at 25??C), are dominated by the dissolution of calcite relative to silicate minerals. The correlation of these parameters with higher calcite concentrations decreases as leachates approach thermodynamic saturation. In longer term column experiments (1.5 yr), reactive calcite becomes exhausted, solute Ca and Sr become controlled by feldspar dissolution and 87Sr/ 86Sr by biotite oxidation. Some accessory calcite in granitoid rocks is related to intrusion into carbonate wall rock or produced by later hydrothermal alteration. However, the ubiquitous occurrence of calcite also suggests formation during late stage (subsolidus) magmatic processes. This conclusion is supported by petrographic observations and 87Sr/86Sr analyses. A review of thermodynamic data indicates that at moderate pressures and reasonable CO2 fugacities, calcite is a stable phase at temperatures of 400 to 700??C. Copyright ?? 2005 Elsevier Ltd.

  10. Simultaneous removal of heavy metals from aqueous solution by natural limestones

    NASA Astrophysics Data System (ADS)

    Sdiri, Ali; Higashi, Teruo

    2013-03-01

    Two natural limestone samples, collected from the Campanian-Maastrichtian limestones, Tunisia, were used as adsorbents for the removal of toxic metals in aqueous systems. The results indicated that high removal efficiency could be achieved by the present natural limestones. Among the metal ions studied, Pb2+ was the most preferably removed cation because of its high affinity to calcite surface. In binary system, the presence of Cu2+ effectively depressed the sorption of Cd2+ and Zn2+. Similarly Cu2+ strongly competed with Pb2+ to limestone surface. In ternary system, the removal further decreased, but considerable amount of Pb2+ and Cu2+ still occurred regardless of the limestone sample. The same behavior was observed in quadruple system, where the selectivity sequence was Pb2+ > Cu2+ > Cd2+ > Zn2+. From these results, it was concluded that the studied limestones have the required technical specifications to be used for the removal of toxic metals from wastewaters.

  11. The nature of the sunspot phenomenon. I - Solutions of the heat transport equation

    NASA Technical Reports Server (NTRS)

    Parker, E. N.

    1974-01-01

    It is pointed out that sunspots represent a disruption in the uniform flow of heat through the convective zone. The basic sunspot structure is, therefore, determined by the energy transport equation. The solutions of this equation for the case of stochastic heat transport are examined. It is concluded that a sunspot is basically a region of enhanced, rather than inhibited, energy transport and emissivity. The heat flow equations are discussed and attention is given to the shallow depth of the sunspot phenomenon. The sunspot is seen as a heat engine of high efficiency which converts most of the heat flux into hydromagnetic waves.

  12. Processing Natural and Reconstituted Silk Solutions Under Equilibrium and Non-Equilibrium Conditions

    DTIC Science & Technology

    1993-01-01

    Liquid Crystals 153,415 (1987). 2. T.G. Ryan , Molecular Crystals and Liquid Crystals 157, 577 (1988). 3. P.J. Collings, Liquid Crystals: Nature’s Delicate... Gosline , M.E. DeMont and M.W. Denny, Endeavour 10, 37 (1986). 2214)1L. Kaplan, S.J. Lombardi, W.S. Muller and S.A. Fossey, in Biomaterials: Novel Materials

  13. Removal of lead from aqueous solutions by using the natural and Fe(III)-modified zeolite

    NASA Astrophysics Data System (ADS)

    Kragović, Milan; Daković, Aleksandra; Sekulić, Živko; Trgo, Marina; Ugrina, Marin; Perić, Jelena; Gatta, G. Diego

    2012-02-01

    In the present study, the sorption of lead by the natural and Fe(III)-modified zeolite (clinoptilolite) is described. The characterization of the natural zeolite-rich rock and the Fe(III)-modified form was performed by chemical analysis, point of the zero charge (pHpzc), X-ray powder diffraction, applying the Rietveld/RIR method for the quantitative phase analysis, and scanning electron microscopy. The effects of sorbents dose and the initial lead concentrations on its sorption by two sorbents were investigated. For both sorbents, it was determined that at lower initial concentrations of lead, ion exchange of inorganic cations in zeolites with lead, together with uptake of hydrogen dominated, while at higher initial lead concentrations beside these processes, chemisorption of lead occurred. Significantly higher sorption of lead was achieved with Fe(III)-modified zeolite. From sorption isotherms, maximum sorbed amounts of lead, under the applied experimental conditions, were 66 mg/g for the natural and 133 mg/g for Fe(III)-modified zeolite. The best fit of experimental data was achieved with the Freundlich model (R2 ≥ 0.94).

  14. Kinetics and mechanism of the degradation of methyl parathion in aqueous hydrogen sulfide solution: investigation of natural organic matter effects.

    PubMed

    Guo, Xiaofen; Jans, Urs

    2006-02-01

    The kinetics of the transformation of methyl parathion have been investigated in aqueous solution containing reduced sulfur species and small concentrations of natural organic matter (NOM) from different sources such as soil, river, and peat. It was shown that NOM mediates the degradation of methyl parathion in aqueous solutions containing hydrogen sulfide. After evaluating and quantifying the effect of the NOM concentration on the degradation kinetics of methyl parathion in the presence of hydrogen sulfide, it was found that the observed pseudo-first-order reaction rate constants (k(obs)) were proportional to NOM concentrations. The influence of pH on the degradation of methyl parathion in the aqueous solutions containing hydrogen sulfide and NOM has been studied. The rate of degradation of methyl parathion was strongly pH dependent. The results indicate k(obs) with a commercially available humic acid has a maximum value at approximately pH 8.3. Two main reaction mechanisms are identified to dominate the degradation of methyl parathion in aqueous solution containing hydrogen sulfide and NOM based on the products aminomethyl parathion and desmethyl methyl parathion. The two mechanisms are nitro-group reduction and nucleophilic attack at the methoxy-carbon. The reduction of the nitro-group is only observed in the presence of NOM. The results of this study form an important base for the evaluation and interpretation of transformation processes of methyl parathion in the environment.

  15. Prevention of degradation of the natural high potency sweetener (2R,4R)-monatin in mock beverage solutions.

    PubMed

    Storkey, Corin; Pattison, David I; Koehler, Jamie A; Gaspard, Dan S; Evans, Jeff C; Hagestuen, Erik D; Davies, Michael J

    2015-04-15

    Exposure of the naturally-occurring sweetener monatin to light and metal ions results in loss of both parent monatin and total indole (monatin plus monatin lactone/lactam) in mock beverage solutions, with an accompanying decrease in sweetness. In this study potential protective strategies to prevent degradation were investigated. Metal ion chelating resin, or the chelators EDTA and desferrioxamine decreased monatin and indole loss for solutions kept either in darkness or exposed to light. Tannic acid and Chinese bayberry extract both afforded protection, but this did not arise from a light filtering effect. Plastics with defined absorbance characteristics provided protection with this being wavelength dependent; yellow transparent PET plastic was most effective. The contribution of these interventions (metal ion removal/binding; antioxidant; light absorption) was additive, with combinations providing the greatest protective effect against monatin and indole loss. These results indicate that it is possible to minimise monatin degradation by appropriate choices of treatments, additives and container.

  16. Synthesis of Mesoporous CaCO3 Powder using Natural Limestone as Ca Ion Source with Solution Mixing Method

    NASA Astrophysics Data System (ADS)

    Arifin, Zaenal; Lailiyah, Qudsiyyatul; Zainuri, Mochamad; Darminto

    2017-05-01

    In this study, the CaCO3 powder has successfully been synthesized by mixing CaCl2 derived from natural limestone and Na2CO3 in the same molar ratio. The mixing process of two solutions was performed by employing the molar contents of 0.25, 0.5, 0.75 and 1 M at varying temperatures of 35, 50 and 80°C. The produced CaCO3 microparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET). The highest content of vaterite phase of the samples is around 96 wt%, resulted from the process using solution of 0.25 M at 35°C. All the samples prepared show mesoporous solids with pore sizes of 3-4 nm and specific surface area of 81-90 m2/g.

  17. True molecular solutions of natural cellulose in the binary ionic liquid-containing solvent mixtures.

    PubMed

    Rein, Dmitry M; Khalfin, Rafail; Szekely, Noemi; Cohen, Yachin

    2014-11-04

    Evidence is presented for the first time of true molecular dissolution of cellulose in binary mixtures of common polar organic solvents with ionic liquid. Cryogenic transmission electron microscopy, small-angle neutron-, X-ray- and static light scattering were used to investigate the structure of cellulose solutions in mixture of dimethyl formamide and 1-ethyl-3-methylimidazolium acetate. Structural information on the dissolved chains (average molecular weight ∼ 5 × 10(4)g/mol; gyration radius ∼ 36 nm, persistence length ∼ 4.5 nm), indicate the absence of significant aggregation of the dissolved chains and the calculated value of the second virial coefficient ∼ 2.45 × 10(-2)mol ml/g(2) indicates that this solvent system is a good solvent for cellulose. More facile dissolution of cellulose could be achieved in solvent mixtures that exhibit the highest electrical conductivity. Highly concentrated cellulose solution in pure ionic liquid (27 wt.%) prepared according to novel method, utilizing the rapid evaporation of a volatile co-solvent in binary solvent mixtures at superheated conditions, shows insignificant cellulose molecular aggregation.

  18. Uranium sorption onto natural sands as a function of sediment characteristics and solution pH

    SciTech Connect

    Rosentreter, J.J.; Quarder, S.H.; Smith, R.W.; McLing, T.

    1996-10-01

    Uranium sorption studies were conducted on twenty-five sandy sediments obtained from Virginia`s Easter Shore Peninsula using batch contact methods. Distribution coefficient (Kd) and sorption isotherms have been determined as function of solution pH. All sediment samples strongly sorbed dissolved uranium species at pH values above 5. Sediments characterized by high iron, aluminum, and surface area, possessed the highest sorption characteristics. Both, Freundlich and Dubinin Radushkevich equations were able to describe the sorption behavior. From the Dubinin-Radushkevich equation, the solution-component-solid surface bounding energy and the sorption capacities, were estimated. Least square regression utilizing sediment characteristics provided an effective statistical method for Kd prediction. Predictions with relative errors of about 30% were obtained using only two sediment variables, such as, iron or aluminum content and surface area. In conclusion, the results support that ion exchange and surface complexation reactions with the ferric and aluminum oxide/oxyhydroxides groups are the predominant sorption mechanisms.

  19. Nature of solute loads in the rivers of the Bengal drainage basin, Bangladesh

    NASA Astrophysics Data System (ADS)

    Datta, Dilip K.; Subramanian, V.

    1997-11-01

    The Bengal drainage basin is geologically one of the youngest and tectonically most active denudation regimes of the world, and encompasses the total lower reaches of the Ganges-Brahmaputra-Meghna (GBM) drainage basin. The GBM river system contributes around 4.5% of the total annual global freshwater flux to the oceans. The solute load of the GBM river system is dominated by the carbonate weathering products of the transport-limited denudation regime. However, in the Meghna basin, which drains a mountainous region, silicate weathering is slightly more predominant, and the solute load tends to be more influenced by the atmospheric contribution. The river system represents about 5% (152×10 6 t yr -1) of the annual global chemical flux to the world's oceans. The chemical denudation rate of the GBM system in the Bengal basin, is one of the world's highest (79-114 t km -2 yr -1), suggesting intensive weathering and erosion in the drainage basin both in Bangladesh as well as in the hinterlands of India and China.

  20. Deproteinized natural rubber film forming polymeric solutions for nicotine transdermal delivery.

    PubMed

    Pichayakorn, Wiwat; Suksaeree, Jirapornchai; Boonme, Prapaporn; Amnuaikit, Thanaporn; Taweepreda, Wirach; Ritthidej, Garnpimol C

    2013-01-01

    Film forming polymeric solutions were prepared from DNRL blended with MC, PVA, or SAG, together with dibutylphthalate or glycerine used as plasticizers. These formulations were easily prepared by simple mixing. In a preliminary step, in situ films were prepared by solvent evaporation in a Petri-dish. Their mechanical and physicochemical properties were determined. The in vitro release and skin permeation of nicotine dissolved in these blended polymers were investigated by a modified Franz diffusion cell. The formulations had a white milky appearance, and were homogeneous and smooth in texture. Their pH was suitable for usage in skin contact. The mechanical property of in situ films depended on the ingredients but all compatible films were in an amorphous phase. The DNRL/PVA was shown to be the most suitable mixture to form completed films. The in vitro release and skin permeation studies demonstrated a biphasic release that provided an initial rapid release followed by a constant release rate that fitted the Higuchi's model. Nicotine loaded DNRL/PVA series were selected for the stability test for 3 months. These formulations needed to be kept at 4°C in tight fitting containers. In conclusion, film forming polymeric solutions could be developed for transdermal nicotine delivery systems.

  1. The impact of solution chemistry of electrolyte on the sorption of pentachlorophenol and phenanthrene by natural hematite nanoparticles.

    PubMed

    Zeng, Fanfeng; He, Yan; Lian, Zhenghua; Xu, Jianming

    2014-01-01

    Hematite nanoparticles (NPs) were studied as a sorbent for hydrophobic organic contaminants (OCs) under natural ambient conditions through specially designed contrasting solution chemistry of electrolyte. Ionizable pentachlorophenol (PCP) and non-ionizable phenanthrene (PHE) were selected as representative OCs. The sorption capacities of PCP and PHE were pH-dependent, and a larger amount of PCP was sorbed at pH values below its pKa (4.75). However, the PHE sorption capacity was higher at relatively high or low pHs (e.g. below 4.0 and above 10.0), possibly due to the larger available surface area of the hematite NPs, caused by the higher values of net charges and charge density. Changes in pH might thus affect the sorption of OCs by hematite NPs, through modification of the surface characteristics of the sorbent and the electronic properties of the sorbate molecules. The influence of different ionic strengths indicated that the amounts of PCP and PHE sorbed by hematite NPs decreased as a concentration function of different types of ions (e.g. Na(+), K(+), Mg(2+) and Ca(2+)), with the underlying mechanism possibly being due to four interactions i.e. hydrogen-bonding, competitive sorption by ions in the ambient solution, screening effects and aggregation effects. The results confirmed that the surface chemistry of hematite NPs, the chemical properties of PCP and PHE, and solution chemistry (e.g. pH and ionic strength) of the electrolyte all played an important role in PCP and PHE sorption by hematite NPs. By comparison of both sorption capacity and ecologic advantages, our results suggested that natural hematite NPs would be more competitive and efficient for PCP and PHE sorption than engineered NPs. This finding increases our knowledge regarding the environmental function of natural NPs (such as hematite NPs) for OC remediation through manipulating their interfacial behavior. © 2013.

  2. Wetlands as large-scale nature-based solutions: status and future challenges for research and management

    NASA Astrophysics Data System (ADS)

    Thorslund, Josefin; Jarsjö, Jerker; Destouni, Georgia

    2017-04-01

    Wetlands are often considered as nature-based solutions that can provide a multitude of services of great social, economic and environmental value to humankind. The services may include recreation, greenhouse gas sequestration, contaminant retention, coastal protection, groundwater level and soil moisture regulation, flood regulation and biodiversity support. Changes in land-use, water use and climate can all impact wetland functions and occur at scales extending well beyond the local scale of an individual wetland. However, in practical applications, management decisions usually regard and focus on individual wetland sites and local conditions. To understand the potential usefulness and services of wetlands as larger-scale nature-based solutions, e.g. for mitigating negative impacts from large-scale change pressures, one needs to understand the combined function multiple wetlands at the relevant large scales. We here systematically investigate if and to what extent research so far has addressed the large-scale dynamics of landscape systems with multiple wetlands, which are likely to be relevant for understanding impacts of regional to global change. Our investigation regards key changes and impacts of relevance for nature-based solutions, such as large-scale nutrient and pollution retention, flow regulation and coastal protection. Although such large-scale knowledge is still limited, evidence suggests that the aggregated functions and effects of multiple wetlands in the landscape can differ considerably from those observed at individual wetlands. Such scale differences may have important implications for wetland function-effect predictability and management under large-scale change pressures and impacts, such as those of climate change.

  3. Tunable blood compatibility of polysulfobetaine from controllable molecular-weight dependence of zwitterionic nonfouling nature in aqueous solution.

    PubMed

    Shih, Yu-Ju; Chang, Yung

    2010-11-16

    This work describes a tunable blood compatibility of zwitterionic poly(sulfobetaine methacrylate) (polySBMA) polymers at a wide range of high molecular weights from 50 kDa to 300 kDa controlled with a similar polydispersity via homogeneous free-radical polymerization. The control of molecular weights of polySBMA highly regulates the zwitterionic nonfouling nature to resist the adsorption of plasma proteins, the coagulant of human plasma, and the hemolysis of red blood cells. In this study, the upper critical solution temperatures (UCSTs) and hydrodynamic size of prepared polymers are determined to illustrate the correlations between intermolecular zwitterionic associations and blood compatibility of polySBMA suspension in human blood. The polySBMA exhibited clear shifts of UCSTs in the stimuli-responsive control of solution pH and ionic strength, which were strongly associated with the molecular weights of the prepared polymers. Plasma-protein adsorption onto the polySBMA polymers from single-protein solutions and the complex medium of 100% human plasma were measured by dynamic light scattering to determine the nonfouling stability of polySBMA suspension. It was found that the nonfouling nature as well as hydration capability of polySBMA can be effectively controlled via regulated molecular weights of zwitterionic polymers. This work shows that the polySBMA polymer with an optimized molecular weight of about 135 kDa at physiologic temperature is presented high hydration capability to function the best nonfouling character of anticoagulant activity and antihemolytic activity in human blood. The excellent blood compatibility of zwitterionic polySBMA along with their stimuli-responsive phase behavior in aqueous solution suggests their potential for use in blood-contacting targeted delivery and diagnostic applications.

  4. Bridging the Gap between Preservice Early Childhood Teachers' Cultural Values, Perceptions of Values Held by Scientists, and the Relationships of These Values to Conceptions of Nature of Science

    ERIC Educational Resources Information Center

    Akerson, Valarie L.; Buzzelli, Cary A.; Eastwood, Jennifer L.

    2012-01-01

    This study explored preservice teachers' views of their own cultural values, the cultural values they believed scientists hold, and the relationships of these views to their conceptions of nature of science (NOS). Parallel assignments in a foundations of early childhood education and a science methods course required preservice teachers to explore…

  5. An Assessment of Student Knowledge in Fourth, Eighth and Eleventh Grades of Science and Natural Resource Concepts Related to Acidic Deposition.

    ERIC Educational Resources Information Center

    Brody, Michael; And Others

    This study assessed the level of scientific and natural resource knowledge that 4th, 8th, and 11th grade students in Maine possessed concerning acidic deposition. A representative sample of public school students (n=175) was interviewed on 12 concept principles considered critical to a full understanding of the acidic deposition problem. These…

  6. Female and Male Teachers' Pro-Environmental Behaviour, Conceptions and Attitudes Towards Nature and the Environment Do Not Differ: Ecofeminism Put to the Test

    ERIC Educational Resources Information Center

    Mc Ewen, B.; Clément, P.; Gericke, N. M.; Nyberg, E.; Hagman, M.; Landström, J.

    2015-01-01

    Teachers' pro-environmental behaviour, conceptions and attitudes towards nature and the environment were investigated using 47 questions from the BIOHEAD-Citizen questionnaire. The sample included 1,109 pre- and in-service teachers from Sweden and France. Analyses showed only few significant differences between female and male teachers. Forty-one…

  7. The Classroom Practice of a Prospective Secondary Biology Teacher and His Conceptions of the Nature of Science and of Teaching and Learning Science

    ERIC Educational Resources Information Center

    Mellado, Vicente; Bermejo, Maria Luisa; Blanco, Lorenzo J.; Ruiz, Constantino

    2008-01-01

    We describe research carried out with a prospective secondary biology teacher, whom we shall call Miguel. The teacher's conceptions of the nature of science and of learning and teaching science were analyzed and compared with his classroom practice when teaching science lessons. The data gathering procedures were interviews analyzed by means of…

  8. Female and Male Teachers' Pro-Environmental Behaviour, Conceptions and Attitudes Towards Nature and the Environment Do Not Differ: Ecofeminism Put to the Test

    ERIC Educational Resources Information Center

    Mc Ewen, B.; Clément, P.; Gericke, N. M.; Nyberg, E.; Hagman, M.; Landström, J.

    2015-01-01

    Teachers' pro-environmental behaviour, conceptions and attitudes towards nature and the environment were investigated using 47 questions from the BIOHEAD-Citizen questionnaire. The sample included 1,109 pre- and in-service teachers from Sweden and France. Analyses showed only few significant differences between female and male teachers. Forty-one…

  9. Pre-Service Teachers' Developing Conceptions about the Nature and Pedagogy of Mathematical Modeling in the Context of a Mathematical Modeling Course

    ERIC Educational Resources Information Center

    Cetinkaya, Bulent; Kertil, Mahmut; Erbas, Ayhan Kursat; Korkmaz, Himmet; Alacaci, Cengiz; Cakiroglu, Erdinc

    2016-01-01

    Adopting a multitiered design-based research perspective, this study examines pre-service secondary mathematics teachers' developing conceptions about (a) the nature of mathematical modeling in simulations of "real life" problem solving, and (b) pedagogical principles and strategies needed to teach mathematics through modeling. Unlike…

  10. Pre-Service Teachers' Developing Conceptions about the Nature and Pedagogy of Mathematical Modeling in the Context of a Mathematical Modeling Course

    ERIC Educational Resources Information Center

    Cetinkaya, Bulent; Kertil, Mahmut; Erbas, Ayhan Kursat; Korkmaz, Himmet; Alacaci, Cengiz; Cakiroglu, Erdinc

    2016-01-01

    Adopting a multitiered design-based research perspective, this study examines pre-service secondary mathematics teachers' developing conceptions about (a) the nature of mathematical modeling in simulations of "real life" problem solving, and (b) pedagogical principles and strategies needed to teach mathematics through modeling. Unlike…

  11. Focusing on the Classical or Contemporary? Chinese Science Teacher Educators' Conceptions of Nature of Science Content to Be Taught to Pre-Service Science Teachers

    ERIC Educational Resources Information Center

    Wan, Zhi Hong; Wong, Siu Ling; Wei, Bing; Zhan, Ying

    2013-01-01

    Drawing from the phenomenographic perspective, an exploratory study investigated Chinese teacher educators' conceptions of teaching Nature of Science (NOS) to pre-service science teachers through semi-structured interviews. Five key dimensions emerged from the data. This paper focuses on the dimension, "NOS content to be taught to pre-service…

  12. Bridging the Gap between Preservice Early Childhood Teachers' Cultural Values, Perceptions of Values Held by Scientists, and the Relationships of These Values to Conceptions of Nature of Science

    ERIC Educational Resources Information Center

    Akerson, Valarie L.; Buzzelli, Cary A.; Eastwood, Jennifer L.

    2012-01-01

    This study explored preservice teachers' views of their own cultural values, the cultural values they believed scientists hold, and the relationships of these views to their conceptions of nature of science (NOS). Parallel assignments in a foundations of early childhood education and a science methods course required preservice teachers to explore…

  13. Focusing on the Classical or Contemporary? Chinese Science Teacher Educators' Conceptions of Nature of Science Content to Be Taught to Pre-Service Science Teachers

    ERIC Educational Resources Information Center

    Wan, Zhi Hong; Wong, Siu Ling; Wei, Bing; Zhan, Ying

    2013-01-01

    Drawing from the phenomenographic perspective, an exploratory study investigated Chinese teacher educators' conceptions of teaching Nature of Science (NOS) to pre-service science teachers through semi-structured interviews. Five key dimensions emerged from the data. This paper focuses on the dimension, "NOS content to be taught to pre-service…

  14. The characterization of the adsorption of cadmium from aqueous solution using natural fibers treated with nanoparticles

    NASA Astrophysics Data System (ADS)

    Rediske, Nicole M.

    The objective of this research was to characterize natural carbon fibers from coconut husks, both bare and impregnated with metallic nanoparticles, in removing cadmium from aqueous media. The adsorbent load, kinetics, isotherm parameters, removal efficiencies, desorption capacity and possible contaminant removal mechanisms were evaluated. It was found that the fibers treated with metallic nanoparticles performed better than the bare fibers in removing cadmium from water. The ideal conditions were found to be neutral pH with low initial cadmium concentrations. Through the kinetic analyses, the adsorption process was first thought to be pseudo first order with two separate adsorption mechanisms apparent. Upon further analysis, it was seen that the first mechanism does not follow the pseudo first order kinetics model. An increase in calcium and magnesium concentrations was observed as the cadmium concentrations decreases. This increase corresponds with first mechanism. This suggests the cadmium removal in the first mechanism is due to ion exchange. The second mechanism's rate constant was consistently lower than the first mechanisms rate constant by an order of magnitude. This led to the hypothesis that the second mechanism is controlled by van de Waals forces, specifically ion-induced dipole interactions, and physical adsorption. It was also found that the cadmium does not effectively desorb from the wasted fibers in DI water. Keywords: Adsorption; kinetics; pseudo first order; cadmium; metallic nanoparticles; natural fibers; removal efficiencies; ion exchange.

  15. Neuroontology, neurobiological naturalism, and consciousness: A challenge to scientific reduction and a solution

    NASA Astrophysics Data System (ADS)

    Feinberg, Todd E.

    2012-03-01

    One of the great challenges to a science of consciousness is the inability to reduce critical features of consciousness to neural processes. In this paper I identify four neuroontologically irreducible features (NOIF) - referral of neural states, mental unity, qualia, and mental causation - defined as aspects of consciousness in which subjective experience is not wholly reducible to objectively observed or objectively understood neurons (ontological subjectivity). I next analyze the emergent and unique system properties of the neural hierarchy and argue that while the NOIF are indeed ontologically subjective, each of the NOIF individually can be explained by the unique architecture and functional properties of the neural hierarchy that lead to both emergent properties and their irreducibility in a manner that does not violate any known physical laws nor require any new physics or the application of physics to emergence or reduction beyond that normally applied to biology in general. I conclude that consciousness is a neurobiologically unique and local phenomenon that is specific to particular neural systems, a view that is consistent with both ontological subjectivity and biological naturalism. I call this position weakly emergent nonreductive physicalism or neurobiological naturalism.

  16. On closing the gap between philosophical concepts and their usage in scientific practice: A lesson from the debate about natural selection as mechanism.

    PubMed

    Matthews, Lucas J

    2016-02-01

    In addition to theorizing about the role and value of mechanisms in scientific explanation or the causal structure of the world, there is a fundamental task of getting straight what a 'mechanism' is in the first place. Broadly, this paper is about the challenge of application: the challenge of aligning one's philosophical account of a scientific concept with the manner in which that concept is actually used in scientific practice. This paper considers a case study of the challenge of application as it pertains to the concept of a mechanism: the debate about whether natural selection is a mechanism. By making clear what is and is not at stake in this debate, this paper considers various strategies for dealing with the challenge of application and makes a case for definitional pluralism about mechanism concepts. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Removal of Alizarin Violet 3R (anthraquinonic dye) from aqueous solutions by natural coagulants.

    PubMed

    Beltrán-Heredia, J; Sánchez-Martín, J; Delgado-Regalado, A; Jurado-Bustos, C

    2009-10-15

    In this paper the ability of two natural products in removing dyes has been tested. After a preliminary screening for dye removal capacity, a tannin-based coagulant called ACQUAPOL C-1 and a vegetal protein extract derived from Moringa oleifera seed have been fully studied. The influence of several parameters such as pH, temperature or initial dye concentration (IDC) have been tested and the behavior of both coagulants has been compared. pH results to be an interesting variable and dye removal decreases as pH increases. This effect is higher in ACQUAPOL C-1 than in M. oleifera seed extract. Temperature seems not to be so affecting parameter, while IDC appears to be a very important variable in q(c) capacity, which is higher as IDC increases. Langmuir isotherm model fits very well in both cases of ACQUAPOL C-1 and M. oleifera seed extract dye removal.

  18. Solution-mass transfer and grain boundary sliding in mafic shear zones - comparison between experiments and nature

    NASA Astrophysics Data System (ADS)

    Marti, Sina; Heilbronner, Renée; Stünitz, Holger; Plümper, Oliver; Drury, Martyn

    2017-04-01

    Grain size sensitive creep (GSSC) mechanisms are widely recognized to be the most efficient deformation mechanisms in shear zones. With or without initial fracturing and fluid infiltration, the onset of heterogeneous nucleation leading to strong grain size reduction is a frequently described process for the initiation of GSSC. Phase mixing due to reaction and heterogeneous nucleation during GSSC impedes grain growth, sustaining small grain sizes as a prerequisite for GSSC. Here we present rock deformation experiments on 'wet' plagioclase - pyroxene mixtures at T=800°C, P=1.0 and 1.5GPa and strain rates of 2e-5 - 2e-6 1/s, performed with a Griggs-type solid medium deformation apparatus. Microstructural criteria are used to show that both, grain boundary sliding (GBS) and solution-mass transfer processes are active and are interpreted to be the dominant strain accommodating processes. Displacement is localized within shear bands formed by fine-grained ( 300 - 500nm) plagioclase (Pl) and the syn-kinematic reaction products amphibole (Amph), quartz (Qz) and zoisite (Zo). We compare our experiments with a natural case - a sheared mafic pegmatite (P-T during deformation 0.7 - 0.9 GPa, 610 - 710 °C; Getsinger et al., 2013) from Northern Norway. Except for the difference in grain size of the experimental and natural samples, microstructures are strikingly alike. The experimental and natural P- and especially T-conditions are very similar. Consequently, extrapolation from experiments to nature must be made without a significant 'temperature-time' trade-off, which is normally taken advantage of when relating experimental to natural strain rates. We will discuss under which assumptions extrapolation to nature in our case is likely feasible. Syn-kinematic reactions during GBS and solution-mass transport are commonly interpreted to result in an ordered (anticlustered) phase mixture. However, phase mixing in our case is restricted: Mixing is extensive between Pl + Zo + Qz and

  19. Use of Natural-Fiber Bio-Composites in Construction versus Traditional Solutions: Operational and Embodied Energy Assessment.

    PubMed

    Galan-Marin, Carmen; Rivera-Gomez, Carlos; Garcia-Martinez, Antonio

    2016-06-13

    During the last decades natural polymers have become more and more frequent to replace traditional inorganic stabilizers in building materials. The purpose of this research is to establish a comparison between the most conventional building material solutions for load-bearing walls and a type of biomaterial. This comparison will focus on load-bearing walls as used in a widespread type of twentieth century dwelling construction in Europe and still used in developing countries nowadays. To carry out this analysis, the structural and thermal insulation characteristics of different construction solutions are balanced. The tool used for this evaluation is the life cycle assessment throughout the whole lifespan of these buildings. This research aims to examine the environmental performance of each material assessed: fired clay brick masonry walls (BW), concrete block masonry walls (CW), and stabilized soil block masonry walls (SW) stabilized with natural fibers and alginates. These conventional and new materials are evaluated from the point of view of both operational and embodied energy.

  20. Cobalt (II) removal from aqueous solutions by natural hemp fibers: Batch and fixed-bed column studies

    NASA Astrophysics Data System (ADS)

    Tofan, Lavinia; Teodosiu, Carmen; Paduraru, Carmen; Wenkert, Rodica

    2013-11-01

    Natural hemp fibers were explored as sorbent for the removal of Co(II) ions from aqueous solutions in batch and dynamic conditions. The batch Co(II) sorption capacity increased up to pH 5, reached the maximum (7.5-7.8 mg/g) over the initial pH of 4.5-5. As the initial concentration of metal ion increased (in the range of 25-200 mg/L), the cobalt uptake was enhanced, but the Co(II) removal efficiency decreased. The batch sorption of Co(II) on the tested hemp follows a pseudo-second order model, which relies on the assumption that the chemisorptions may be the rate-controlling step. The Langmuir model better described the Co(II) sorption process on the natural hemp fibers in comparison with the Freundlich model. This finding complies with the results of fixed-bed studies which emphasize that the optimal solution for describing the behavior of the investigated hemp bed column is provided by the Thomas model. The sorption capacity of the hemp fibers column (15.44 mg/g) performed better than that of the Co(II)-hemp batch system (13.58 mg/g). The possibility to use hemp fibers as an alternative in the Co(II) wastewater treatment should be studied under pilot scale applications, so as to complete the studies concerning the removal efficiencies with technical and economic factors that influence process scale-up.

  1. Use of Natural-Fiber Bio-Composites in Construction versus Traditional Solutions: Operational and Embodied Energy Assessment

    PubMed Central

    Galan-Marin, Carmen; Rivera-Gomez, Carlos; Garcia-Martinez, Antonio

    2016-01-01

    During the last decades natural polymers have become more and more frequent to replace traditional inorganic stabilizers in building materials. The purpose of this research is to establish a comparison between the most conventional building material solutions for load-bearing walls and a type of biomaterial. This comparison will focus on load-bearing walls as used in a widespread type of twentieth century dwelling construction in Europe and still used in developing countries nowadays. To carry out this analysis, the structural and thermal insulation characteristics of different construction solutions are balanced. The tool used for this evaluation is the life cycle assessment throughout the whole lifespan of these buildings. This research aims to examine the environmental performance of each material assessed: fired clay brick masonry walls (BW), concrete block masonry walls (CW), and stabilized soil block masonry walls (SW) stabilized with natural fibers and alginates. These conventional and new materials are evaluated from the point of view of both operational and embodied energy. PMID:28773586

  2. Structure and pH-induced alterations of recombinant and natural spider silk proteins in solution.

    PubMed

    Leclerc, Jérémie; Lefèvre, Thierry; Pottier, Fabien; Morency, Louis-Philippe; Lapointe-Verreault, Camille; Gagné, Stéphane M; Auger, Michèle

    2012-06-01

    The spinning process of spiders can modulate the mechanical properties of their silk fibers. It is therefore of primary importance to understand what are the key elements of the spider spinning process to develop efficient industrial spinning processes. We have exhaustively investigated the native conformation of major ampullate silk (MaS) proteins by comparing the content of the major ampullate gland of Nephila clavipes, solubilized MaS (SolMaS) fibers and the recombinant proteins rMaSpI and rMaSpII using (1) H solution NMR spectroscopy. The results indicate that the protein secondary structure is basically identical for the recombinant protein rMaSpI, SolMaS proteins, and the proteins in the dope, and corresponds to a disordered protein rich in 3(1) -helices. The data also show that glycine proton chemical shifts of rMaSpI and SolMaS are affected by pH, but that this change is not due to a modification of the secondary structure. Using a combination of NMR and dynamic light scattering, we have found that the spectral alteration of glycine is concomitant to a modification of the hydrodynamical diameter of recombinant and solubilized MaS. This led us to suggest new potential roles for the pH acidification in the spinning process of MaS proteins. Copyright © 2011 Wiley Periodicals, Inc.

  3. Influences of solution chemistry and polymeric natural organic matter on the removal of aquatic pharmaceutical residuals by nanofiltration.

    PubMed

    Zazouli, Mohammad Ali; Susanto, Heru; Nasseri, Simin; Ulbricht, Mathias

    2009-07-01

    This study demonstrates the removal efficiency and the permeate flux behavior during cross-flow nanofiltration (NF) of aqueous solutions of five pharmaceutically active compounds (PhACs). Cephalexin, tetracycline, acetaminophen, indomethacin and amoxicillin were used as models of PhACs, and alginate was selected as model of natural organic matter (NOM). Two commercial composite NF membranes (SR2 and SR3) with different characteristics were used. The highest rejection was observed for tetracycline, i.e., 75-95% for membrane SR 2 and 95-100% for membrane SR 3, while the rejection was least for acetaminophen (32-36% for SR2 and 52-59% for SR3). As the pH of acetaminophen solution was increased (from 6 to 9) the rejection would increase. Changes of ionic content (from 10 to 20mM) lead to increase (from 89 to 93% for SR 3) or decrease (from 100 to 91% for SR2) of cephalexin rejection depending on the membrane used. The permeate flux would decrease with decreasing the pH solution and increasing ionic strength. The addition of alginate in the feed stream decreased the permeate flux, with lower reduction for SR3, and increased the PhAC rejection except for acetaminophen and amoxicillin. Both size and Donnan exclusions seemed to occur, and the effect of Donnan exclusion was more pronounced for the NF membrane having larger effective pore size (SR2).

  4. Feasibility of Topical Applications of Natural High-Concentration Capsaicinoid Solutions in Patients with Peripheral Neuropathic Pain: A Retrospective Analysis

    PubMed Central

    Mouraux, Andre; Deumens, Ronald; Leerink, Marjolein; le Polain de Waroux, Bernard; Joëlle, Quetin-Leclercq

    2016-01-01

    Background. Capsaicin, one of several capsaicinoid compounds, is a potent TRPV1 agonist. Topical application at high concentration (high concentration, >1%) induces a reversible disappearance of epidermal free nerve endings and is used to treat peripheral neuropathic pain (PNP). While the benefit of low-concentration capsaicin remains controversial, the 8%-capsaicin patch (Qutenza®, 2010, Astellas, Netherlands) has shown its effectiveness. This patch is, however, costly and natural high-concentration capsaicinoid solutions may represent a cheaper alternative to pure capsaicin. Methods. In this retrospective study, 149 patients were screened, 132 were included with a diagnosis of neuropathic pain, and eighty-four were retained in the final analyses (median age: 57.5 years [IQR25–75: 44.7–67.1], male/female: 30/54) with PNP who were treated with topical applications of natural high-concentration capsaicinoid solutions (total number of applications: 137). Indications were postsurgical PNP (85.7%) and nonsurgical PNP (14.3%) (posttraumatic, HIV-related, postherpetic, and radicular PNP). Objectives. To assess the feasibility of topical applications of natural high-concentration capsaicinoid solutions for the treatment of PNP. Results. The median treated area was 250 cm2 [IQR25–75: 144–531]. The median amount of capsaicinoids was 55.1 mg [IQR25–75: 28.7–76.5] per plaster and the median concentration was 172.3 μg/cm2 [IQR25–75: 127.6–255.2]. Most patients had local adverse effects on the day of treatment, such as mild to moderate burning pain and erythema. 13.6–19.4% of the patients experienced severe pain or erythema. Following treatment, 62.5% of patients reported a lower pain intensity or a smaller pain surface, and 35% reported a sustained pain relief lasting for at least 4 weeks. Conclusion. Analgesic topical treatment with natural high-concentration capsaicinoid is feasible and may represent a low cost alternative to alleviate PNP in

  5. Adhesion of bacterial pathogens to soil colloidal particles: influences of cell type, natural organic matter, and solution chemistry.

    PubMed

    Zhao, Wenqiang; Walker, Sharon L; Huang, Qiaoyun; Cai, Peng

    2014-04-15

    Bacterial adhesion to granular soil particles is well studied; however, pathogen interactions with naturally occurring colloidal particles (<2 μm) in soil has not been investigated. This study was developed to identify the interaction mechanisms between model bacterial pathogens and soil colloids as a function of cell type, natural organic matter (NOM), and solution chemistry. Specifically, batch adhesion experiments were conducted using NOM-present, NOM-stripped soil colloids, Streptococcus suis SC05 and Escherichia coli WH09 over a wide range of solution pH (4.0-9.0) and ionic strength (IS, 1-100 mM KCl). Cell characterization techniques, Freundlich isotherm, and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory (sphere-sphere model) were utilized to quantitatively determine the interactions between cells and colloids. The adhesion coefficients (Kf) of S. suis SC05 to NOM-present and NOM-stripped soil colloids were significantly higher than E. coli WH09, respectively. Similarly, Kf values of S. suis SC05 and E. coli WH09 adhesion to NOM-stripped soil colloids were greater than those colloids with NOM-present, respectively, suggesting NOM inhibits bacterial adhesion. Cell adhesion to soil colloids declined with increasing pH and enhanced with rising IS (1-50 mM). Interaction energy calculations indicate these adhesion trends can be explained by DLVO-type forces, with S. suis SC05 and E. coli WH09 being weakly adhered in shallow secondary energy minima via polymer bridging and charge heterogeneity. S. suis SC05 adhesion decreased at higher IS 100 mM, which is attributed to the change of hydrophobic effect and steric repulsion resulted from the greater presence of extracellular polymeric substances (EPS) on S. suis SC05 surface as compared to E. coli WH09. Hence, pathogen adhesion to the colloidal material is determined by a combination of DLVO, charge heterogeneity, hydrophobic and polymer interactions as a function of solution chemistry.

  6. Lead removal from aqueous solution by natural and pretreated clinoptilolite: adsorption equilibrium and kinetics.

    PubMed

    Günay, Ahmet; Arslankaya, Ertan; Tosun, Ismail

    2007-07-19

    Adsorption of Pb(II) ions from aqueous solution onto clinoptilolite has been investigated to evaluate the effects of contact time, initial concentration and pretreatment of clinoptilolite on the removal of Pb(II). Experimental data obtained from batch equilibrium tests have been analyzed by four two-parameter (Freundlich, Langmuir, Temkin and Dubinin-Radushkevich), four three-parameter (Redlich-Peterson, Sips, Toth and Khan) isotherm models, and kinetic models including the pseudo-first order, the pseudo-second order and Elovich equations using nonlinear regression technique. Of the two-parameter isotherms, Temkin isotherm was the best to describe the experimental data. Three-parameter isotherms have higher regression coefficients (>0.99) and lower relative errors (<5%) than two-parameter isotherms. The best fitting isotherm was the Sips followed by Toth and Redlich-Peterson isotherm equations. Maximum experimental adsorption capacity was found to be 80.933 and 122.400 mg/g for raw and pretreated clinoptilolite, respectively, for the initial concentration of 400 mg/L. Kinetic parameters; rate constants, equilibrium adsorption capacities and related coefficients for each kinetic model were evaluated according to relative errors and correlation coefficients. Results of the kinetic studies show that best fitted kinetic models are obtained to be in the order: the pseudo-first order, the pseudo-second order and Elovich equations. Using the thermodynamic equilibrium coefficients, Gibbs free energy of the Pb(II)-clinoptilolite system was evaluated. The negative value of change in Gibbs free energy (DeltaG degrees ) indicates that adsorption of Pb(II) on clinoptilolite is spontaneous.

  7. Application of natural zeolite for phosphorus and ammonium removal from aqueous solutions.

    PubMed

    Karapinar, Nuray

    2009-10-30

    Removal of both nutrients ammonium and phosphorus by natural zeolite has been studied in lab scale by using a mechanically stirred batch system (1000 ml). Zeolite, a mean particle size of 13 microm, was used as an adsorbent for the removal of ammonium and then as a seed material for the precipitation of calcium phosphate. A relationship was established between the uptake of ammonium by zeolite and the ratio of initial ammonium concentration to zeolite dosage. Ammonium uptake of zeolite was almost completed within initial 5 min of adsorption period. There is no pronounced effect of zeolite and ammonium, neither positive nor negative on the amount of calcium phosphate precipitation. The extent of the precipitation of phosphate increased with rising pH. It was also observed that when the system was allowed to relax at constant pH (i.e. under relatively low super saturations), a certain lag time was noted to elapse at the onset of the precipitation. At the pH 7.2, the amount of initial fast precipitation within 5 min and total precipitation within 120 min were around 34% and 93%, respectively. Precipitation of calcium phosphate on to ammonium-loaded zeolite was achieved at low super saturations (< pH 7.5) through secondary nucleation and crystal growth, leading to an increase in particle size.

  8. Environmental solutions for the sustainable production of bioactive natural products from the marine sponge Crambe crambe.

    PubMed

    Pérez-López, Paula; Ternon, Eva; González-García, Sara; Genta-Jouve, Grégory; Feijoo, Gumersindo; Thomas, Olivier P; Moreira, Ma Teresa

    2014-03-15

    Crambe crambe is a Mediterranean marine sponge known to produce original natural substances belonging to two families of guanidine alkaloids, namely crambescins and crambescidins, which exhibit cytotoxic and antiviral activities. These compounds are therefore considered as potential anticancer drugs. The present study focuses on the environmental assessment of a novel in vivo process for the production of pure crambescin and crambescidin using sponge specimens cultured in aquarium. The assessment was performed following the ISO 14040 standard and extended from the production of the different mass and energy flows to the system to the growth of the sponge in indoor aquarium and further periodic extraction and purification of the bioactive compounds. According to the results, the two stages that have a remarkable contribution to all impact categories are the purification of the bioactive molecules followed by the maintenance of the sponge culture in the aquarium. Among the involved activities, the production of the chemicals (particularly methanol) together with the electricity requirements (especially due to the aquarium lighting) are responsible for up to 90% of the impact in most of the assessed categories. However, the contributions of other stages to the environmental burdens, such as the collection of sponges, considerably depend on the assumptions made during the inventory stage. The simulation of alternative scenarios has led to propose improvement alternatives that may allow significant reductions ranging from 20% to 70%, mainly thanks to the reduction of electricity requirements as well as the partial reuse of methanol. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Adsorption efficiency of natural materials for low-concentration cesium in solution.

    PubMed

    Miura, A; Kubota, T; Hamada, K; Hitomi, T

    2016-01-01

    In this study, several natural materials were investigated in order to clarify their potential use as cesium (Cs) adsorbents in situ. Four materials--carbonized rice hull, beech sawdust, oak sawdust, and charcoal (Japanese cedar)--which were previously shown to have Cs adsorption capabilities, were examined. Cs adsorption experiments were conducted using different initial Cs and adsorbent concentrations. The physical properties, adsorption isotherms, and adsorption processes were then examined, so as to exploit the Cs adsorption characteristics in the field. Based on these findings, carbonized rice hull and beech sawdust were selected as effective Cs adsorbents. It was found that these materials show continuous and stable Cs adsorption rates for different initial Cs concentrations. The adsorption efficiency of these two adsorption materials in combination was considered, and it was shown that the adsorption isotherms for carbonized rice hull and beech sawdust follow the Freundlich model. Furthermore, the beech sawdust adsorption process exhibited better agreement with the calculated values obtained via the adsorption rate model and the adsorption kinetics model than did the carbonized rice hull adsorption.

  10. Solutions for VOC and HAPS control on natural gas fired internal combustion engines

    SciTech Connect

    Marcus, J.Z.; Sleigh, S.; Cotherman, R.

    1996-12-31

    Natural gas fired stationary internal combustion engines (IC engines) emit volatile organic compounds (VOC) and hazardous air pollutants (HAP) as part of their normal operations. VOC and HAP emissions are coming under increased scrutiny with the advent of such Clean Air Act Amendments of 1990 regulations as Title I`s Reasonably Available Control Technology (RACT), Title III`s Maximum Achievable Control Technology (MACT) and Title V`s Operating Permit Program (Title V). In addition, many states are imposing more stringent emission limits on these sources. These emissions may also contribute to the reportable chemicals from the total facility under SARA Title III. Numerous facilities nationwide are interested in reducing these emissions in order to comply with current requirements, to opt out of requirements or to reduce reportable chemicals. This paper will examine the source of these emissions, and discuss combustion control technologies and system operating flexibility, end-of-pipe control technologies, and system tuning opportunities which have the potential to reduce VOC and HAP emissions from IC engines. Data will be presented on potential emission reduction efficiencies achievable using the various control options. 7 refs., 4 tabs.

  11. Technology Solutions Case Study: Improving the Field Performance of Natural Gas Furnaces

    SciTech Connect

    2013-11-01

    The objective of this project is to examine the impact that common installation practices and age-induced equipment degradation may have on the installed performance of natural gas furnaces, as measured by steady-state efficiency and AFUE. PARR identified twelve furnaces of various ages and efficiencies that were operating in residential homes in the Des Moines Iowa metropolitan area and worked with a local HVAC contractor to retrieve them and test them for steady-state efficiency and AFUE in the lab. Prior to removal, system airflow, static pressure, equipment temperature rise, and flue loss measurements were recorded for each furnace. After removal from the field the furnaces were transported to the Gas Technology Institute (GTI) laboratory, where PARR conducted steady-state efficiency and AFUE testing. The test results show that steady-state efficiency in the field was 6.4% lower than that measured for the same furnaces under standard conditions in the lab, which included tuning the furnace input and air flow rate. Comparing AFUE measured under ASHRAE standard conditions with the label value shows no reduction in efficiency for the furnaces in this study over their 15 to 24 years of operation when tuned to standard conditions. Further analysis of the data showed no significant correlation between efficiency change and the age or the rated efficiency of the furnace.

  12. Solution conformations of Zika NS2B-NS3pro and its inhibition by natural products from edible plants.

    PubMed

    Roy, Amrita; Lim, Liangzhong; Srivastava, Shagun; Lu, Yimei; Song, Jianxing

    2017-01-01

    The recent Zika viral (ZIKV) epidemic has been associated with severe neurological pathologies such as neonatal microcephaly and Guillain-Barre syndrome but unfortunately no vaccine or medication is effectively available yet. Zika NS2B-NS3pro is essential for the proteolysis of the viral polyprotein and thereby viral replication. Thus NS2B-NS3pro represents an attractive target for anti-Zika drug discovery/design. Here, we have characterized the solution conformations and catalytic parameters of both linked and unlinked Zika NS2B-NS3pro complexes and found that the unlinked complex manifested well-dispersed NMR spectra. Subsequently with selective isotope-labeling using NMR spectroscopy, we demonstrated that C-terminal residues (R73-K100) of NS2B is highly disordered without any stable tertiary and secondary structures in the Zika NS2B-NS3pro complex in the free state. Upon binding to the well-characterized serine protease inhibitor, bovine pancreatic trypsin inhibitor (BPTI), only the extreme C-terminal residues (L86-K100) remain disordered. Additionally, we have identified five flavonoids and one natural phenol rich in edible plants including fruits and vegetables, which inhibit Zika NS2B-NS3pro in a non-competitive mode, with Ki ranging from 770 nM for Myricetin to 34.02 μM for Apigenin. Molecular docking showed that they all bind to a pocket on the back of the active site and their structure-activity relationship was elucidated. Our study provides valuable insights into the solution conformation of Zika NS2B-NS3pro and further deciphers its susceptibility towards allosteric inhibition by natural products. As these natural product inhibitors fundamentally differ from the currently-known active site inhibitors in terms of both inhibitory mode and chemical scaffold, our finding might open a new avenue for development of better allosteric inhibitors to fight ZIKV infection.

  13. Formulation and solution of the delayed gamma dose rate problem using the concept of effective delayed gamma production cross section

    SciTech Connect

    Liew, S.L.; Ku, L.P.

    1989-06-01

    With appropriate approximations, the delayed gamma dose rate problem can be formulated in terms of the effective delayed gamma production cross section. The coupled neutron-delayed-gamma transport equations then take the same form as the coupled neutron-prompt-gamma transport equations and they can, therefore, be solved directly in the same manner. This eliminates the need for the tedious and error prone flux coupling step in conventional calculations. Mathematical formulation and solution algorithms are derived. The advantages of this method are illustrated by an example of its application in the solution of a practical design problem. 62 refs., 10 figs., 1 tab.

  14. A unifying model for elongational flow of polymer melts and solutions based on the interchain tube pressure concept

    NASA Astrophysics Data System (ADS)

    Wagner, Manfred Hermann; Rolón-Garrido, Víctor Hugo

    2015-04-01

    An extended interchain tube pressure model for polymer melts and concentrated solutions is presented, based on the idea that the pressures exerted by a polymer chain on the walls of an anisotropic confinement are anisotropic (M. Doi and S. F. Edwards, The Theory of Polymer Dynamics, Oxford University Press, New York, 1986). In a tube model with variable tube diameter, chain stretch and tube diameter reduction are related, and at deformation rates larger than the inverse Rouse time τR, the chain is stretched and its confining tube becomes increasingly anisotropic. Tube diameter reduction leads to an interchain pressure in the lateral direction of the tube, which is proportional to the 3rd power of stretch (G. Marrucci and G. Ianniruberto. Macromolecules 37, 3934-3942, 2004). In the extended interchain tube pressure (EIP) model, it is assumed that chain stretch is balanced by interchain tube pressure in the lateral direction, and by a spring force in the longitudinal direction of the tube, which is linear in stretch. The scaling relations established for the relaxation modulus of concentrated solutions of polystyrene in oligomeric styrene (M. H. Wagner, Rheol. Acta 53, 765-777, 2014, M. H. Wagner, J. Non-Newtonian Fluid Mech. http://dx.doi.org/10.1016/j.jnnfm.2014.09.017, 2014) are applied to the solutions of polystyrene (PS) in diethyl phthalate (DEP) investigated by Bhattacharjee et al. (P. K. Bhattacharjee et al., Macromolecules 35, 10131-10148, 2002) and Acharya et al. (M. V. Acharya et al. AIP Conference Proceedings 1027, 391-393, 2008). The scaling relies on the difference ΔTg between the glass-transition temperatures of the melt and the glass-transition temperatures of the solutions. ΔTg can be inferred from the reported zero-shear viscosities, and the BSW spectra of the solutions are obtained from the BSW spectrum of the reference melt with good accuracy. Predictions of the EIP model are compared to the steady-state elongational viscosity data of PS

  15. DETECTING SELECTION IN NATURAL POPULATIONS: MAKING SENSE OF GENOME SCANS AND TOWARDS ALTERNATIVE SOLUTIONS

    PubMed Central

    Haasl, Ryan J.; Payseur, Bret A.

    2016-01-01

    Genomewide scans for natural selection (GWSS) have become increasingly common over the last 15 years due to increased availability of genome-scale genetic data. Here, we report a representative survey of GWSS from 1999 to present and find that (i) between 1999 and 2009, 35 of 49 (71%) GWSS focused on human, while from 2010 to present, only 38 of 83 (46%) of GWSS focused on human, indicating increased focus on nonmodel organisms; (ii) the large majority of GWSS incorporate interpopulation or interspecific comparisons using, for example FST, cross-population extended haplotype homozygosity or the ratio of nonsynonymous to synonymous substitutions; (iii) most GWSS focus on detection of directional selection rather than other modes such as balancing selection; and (iv) in human GWSS, there is a clear shift after 2004 from microsatellite markers to dense SNP data. A survey of GWSS meant to identify loci positively selected in response to severe hypoxic conditions support an approach to GWSS in which a list of a priori candidate genes based on potential selective pressures are used to filter the list of significant hits a posteriori. We also discuss four frequently ignored determinants of genomic heterogeneity that complicate GWSS: mutation, recombination, selection and the genetic architecture of adaptive traits. We recommend that GWSS methodology should better incorporate aspects of genomewide heterogeneity using empirical estimates of relevant parameters and/or realistic, whole-chromosome simulations to improve interpretation of GWSS results. Finally, we argue that knowledge of potential selective agents improves interpretation of GWSS results and that new methods focused on correlations between environmental variables and genetic variation can help automate this approach. PMID:26224644

  16. Removal of natural organic matter (NOM) from an aqueous solution by NaCl and surfactant-modified clinoptilolite.

    PubMed

    Niri, Mehdi Vosoughi; Mahvi, Amir Hosein; Alimohammadi, Mahmoud; Shirmardi, Mohammad; Golastanifar, Hafez; Mohammadi, Mohamma Javad; Naeimabadi, Abolfazl; Khishdost, Maria

    2015-06-01

    Zeolitic tuffs are found in different parts of the world. Iranian zeolite is a low-cost material that can be frequently found in nature. Surfactant-modified zeolite (SMZ) can be used for the adsorption of natural organic matter (NOM) from aqueous solutions. The adsorption study was conducted to evaluate the adsorption capacity of SMZ; furthermore, the effects of contact time, initial pH, and the initial adsorbent dose on the adsorption process were investigated in a batch system. The kinetic studies showed that the adsorption of NOM on SMZ was a gradual process. The optimum initial pH values for the adsorption of NOM on SMZ were in the acidic ranges. The batch kinetic experiments showed that the adsorption followed the pseudo-second-order kinetic model with good correlation coefficients. The equilibrium data were well described by the Langmuir isotherm model. The results show that the natural zeolite being modified with NaCl and hexadecyltrimethylammonium bromide as a cationic surfactant was an appropriate adsorbent for the removal of NOM.

  17. The direct strip casting concept: A low-cost, high-productivity solution for flat products of all steel grades

    SciTech Connect

    Reichelt, W.; Urlau, U.; Burstroem, E.; Nystroem, R.

    1996-12-31

    The Direct Strip Casting concept is characterized by a high degree of flexibility as regards the types of steel to be cast, at the same time guaranteeing a high production rate and low investment costs. It has been planned to cast strips of all steel grades with a thickness of approx. 10 mm. These strips will not be directly transferred to a cold rolling mill but will undergo two or three hot passes before being wound into a coil. A comparison of the economic feasibility of the DSC process with other near net shape casting processes shows that this process is suitable for small as well as large production rates (up to million tpy/strand) because of the low investment and operating costs. Casting and rolling tests performed in a pilot casting machine and in a casting machine for laboratory purposes show potentially that: the crucial element of the DSC process, the belt caster, is sufficiently stable to attain the required final strip geometry already at the time of casting; the hot shaping envisaged in the DSC concept is sufficient to remove a lack of symmetry that may arise during casting; and the rolling passes envisaged in the DSC concept are necessary and yet at the same time adequate for achieving material properties, for example, sufficiently high r-values for deep drawing grades.

  18. Construct Validity: Choosing the Appropriate Factor Analytic Solution for Developing Subscales on a Self-Concept Instrument.

    ERIC Educational Resources Information Center

    Crocker, Linda; Ahmadi, Behrokh

    The subscales of the How I See Myself Scale were originally established by using a principal components analysis on item scores for a sample of 4,217 elementary school children in grades three to six. A re-analysis of the same data using a common factor solution (using test communalities instead of units in the major diagonal of the correlation…

  19. What Makes an Insight Problem? The Roles of Heuristics, Goal Conception, and Solution Recoding in Knowledge-Lean Problems

    ERIC Educational Resources Information Center

    Chronicle, Edward P.; MacGregor, James N.; Ormerod, Thomas C.

    2004-01-01

    Four experiments investigated transformation problems with insight characteristics. In Experiment 1, performance on a version of the 6-coin problem that had a concrete and visualizable solution followed a hill-climbing heuristic. Experiment 2 demonstrated that the difficulty of a version of the problem that potentially required insight for…

  20. Nature of amine-surfactant interactions at the air-solution interface.

    PubMed

    Penfold, J; Thomas, R K; Zhang, X L; Taylor, D J F

    2009-04-07

    significant in the context of understanding the unusual nature of the PEI/surfactant interaction and of using small molecular weight additives rather than much larger molecular weight polymers to manipulate adsorption properties.