Science.gov

Sample records for impact information diffusion

  1. Optimal Network Modularity for Information Diffusion

    NASA Astrophysics Data System (ADS)

    Nematzadeh, Azadeh; Ferrara, Emilio; Flammini, Alessandro; Ahn, Yong-Yeol

    2014-08-01

    We investigate the impact of community structure on information diffusion with the linear threshold model. Our results demonstrate that modular structure may have counterintuitive effects on information diffusion when social reinforcement is present. We show that strong communities can facilitate global diffusion by enhancing local, intracommunity spreading. Using both analytic approaches and numerical simulations, we demonstrate the existence of an optimal network modularity, where global diffusion requires the minimal number of early adopters.

  2. Information filtering via preferential diffusion

    NASA Astrophysics Data System (ADS)

    Lü, Linyuan; Liu, Weiping

    2011-06-01

    Recommender systems have shown great potential in addressing the information overload problem, namely helping users in finding interesting and relevant objects within a huge information space. Some physical dynamics, including the heat conduction process and mass or energy diffusion on networks, have recently found applications in personalized recommendation. Most of the previous studies focus overwhelmingly on recommendation accuracy as the only important factor, while overlooking the significance of diversity and novelty that indeed provide the vitality of the system. In this paper, we propose a recommendation algorithm based on the preferential diffusion process on a user-object bipartite network. Numerical analyses on two benchmark data sets, MovieLens and Netflix, indicate that our method outperforms the state-of-the-art methods. Specifically, it can not only provide more accurate recommendations, but also generate more diverse and novel recommendations by accurately recommending unpopular objects.

  3. Information filtering via preferential diffusion.

    PubMed

    Lü, Linyuan; Liu, Weiping

    2011-06-01

    Recommender systems have shown great potential in addressing the information overload problem, namely helping users in finding interesting and relevant objects within a huge information space. Some physical dynamics, including the heat conduction process and mass or energy diffusion on networks, have recently found applications in personalized recommendation. Most of the previous studies focus overwhelmingly on recommendation accuracy as the only important factor, while overlooking the significance of diversity and novelty that indeed provide the vitality of the system. In this paper, we propose a recommendation algorithm based on the preferential diffusion process on a user-object bipartite network. Numerical analyses on two benchmark data sets, MovieLens and Netflix, indicate that our method outperforms the state-of-the-art methods. Specifically, it can not only provide more accurate recommendations, but also generate more diverse and novel recommendations by accurately recommending unpopular objects. PMID:21797453

  4. Optimal multi-community network modularity for information diffusion

    NASA Astrophysics Data System (ADS)

    Wu, Jiaocan; Du, Ruping; Zheng, Yingying; Liu, Dong

    2016-02-01

    Studies demonstrate that community structure plays an important role in information spreading recently. In this paper, we investigate the impact of multi-community structure on information diffusion with linear threshold model. We utilize extended GN network that contains four communities and analyze dynamic behaviors of information that spreads on it. And we discover the optimal multi-community network modularity for information diffusion based on the social reinforcement. Results show that, within the appropriate range, multi-community structure will facilitate information diffusion instead of hindering it, which accords with the results derived from two-community network.

  5. Information accumulation system by inheritance and diffusion

    NASA Astrophysics Data System (ADS)

    Shin, J. K.

    2009-09-01

    This paper suggests a new model, called as the IAS (Information Accumulation System), for the description of the dynamic process that people use to accumulate their information (knowledge or opinion) for specific issues. Using the concept of information, both the internal and the external mechanism of the opinion dynamics are treated on a unified frame. The information is quantified as a real number with fixed bounds. New concepts, such as inheritance and differential absorption, are incorporated in IAS in addition to the conventional diffusive interaction between people. Thus, the dynamics of the IAS are governed by following three factors: inheritance rate, diffusivity and absorption rate. The original set of equations was solved with an agent based modeling technique. In addition, the individual equations for each of the agents were assembled and transformed into a set of equations for the ensemble averages, which are greatly reduced in number and can be solved analytically. The example simulations showed interesting results such as the critical behavior with respect to diffusivity, the information polarization out of zero-sum news and the dependence of the solutions on the initial conditions alone. The results were speculated in relation to today’s modern society where the diffusivity of information has been greatly increased through the internet and mobile phones.

  6. Information Diffusion in Facebook-Like Social Networks Under Information Overload

    NASA Astrophysics Data System (ADS)

    Li, Pei; Xing, Kai; Wang, Dapeng; Zhang, Xin; Wang, Hui

    2013-07-01

    Research on social networks has received remarkable attention, since many people use social networks to broadcast information and stay connected with their friends. However, due to the information overload in social networks, it becomes increasingly difficult for users to find useful information. This paper takes Facebook-like social networks into account, and models the process of information diffusion under information overload. The term view scope is introduced to model the user information-processing capability under information overload, and the average number of times a message appears in view scopes after it is generated is proposed to characterize the information diffusion efficiency. Through theoretical analysis, we find that factors such as network structure and view scope number have no impact on the information diffusion efficiency, which is a surprising result. To verify the results, we conduct simulations and provide the simulation results, which are consistent with the theoretical analysis results perfectly.

  7. Exploiting Information Diffusion Feature for Link Prediction in Sina Weibo

    NASA Astrophysics Data System (ADS)

    Li, Dong; Zhang, Yongchao; Xu, Zhiming; Chu, Dianhui; Li, Sheng

    2016-01-01

    The rapid development of online social networks (e.g., Twitter and Facebook) has promoted research related to social networks in which link prediction is a key problem. Although numerous attempts have been made for link prediction based on network structure, node attribute and so on, few of the current studies have considered the impact of information diffusion on link creation and prediction. This paper mainly addresses Sina Weibo, which is the largest microblog platform with Chinese characteristics, and proposes the hypothesis that information diffusion influences link creation and verifies the hypothesis based on real data analysis. We also detect an important feature from the information diffusion process, which is used to promote link prediction performance. Finally, the experimental results on Sina Weibo dataset have demonstrated the effectiveness of our methods.

  8. Exploiting Information Diffusion Feature for Link Prediction in Sina Weibo

    PubMed Central

    Li, Dong; Zhang, Yongchao; Xu, Zhiming; Chu, Dianhui; Li, Sheng

    2016-01-01

    The rapid development of online social networks (e.g., Twitter and Facebook) has promoted research related to social networks in which link prediction is a key problem. Although numerous attempts have been made for link prediction based on network structure, node attribute and so on, few of the current studies have considered the impact of information diffusion on link creation and prediction. This paper mainly addresses Sina Weibo, which is the largest microblog platform with Chinese characteristics, and proposes the hypothesis that information diffusion influences link creation and verifies the hypothesis based on real data analysis. We also detect an important feature from the information diffusion process, which is used to promote link prediction performance. Finally, the experimental results on Sina Weibo dataset have demonstrated the effectiveness of our methods. PMID:26817436

  9. Exploiting Information Diffusion Feature for Link Prediction in Sina Weibo.

    PubMed

    Li, Dong; Zhang, Yongchao; Xu, Zhiming; Chu, Dianhui; Li, Sheng

    2016-01-01

    The rapid development of online social networks (e.g., Twitter and Facebook) has promoted research related to social networks in which link prediction is a key problem. Although numerous attempts have been made for link prediction based on network structure, node attribute and so on, few of the current studies have considered the impact of information diffusion on link creation and prediction. This paper mainly addresses Sina Weibo, which is the largest microblog platform with Chinese characteristics, and proposes the hypothesis that information diffusion influences link creation and verifies the hypothesis based on real data analysis. We also detect an important feature from the information diffusion process, which is used to promote link prediction performance. Finally, the experimental results on Sina Weibo dataset have demonstrated the effectiveness of our methods. PMID:26817436

  10. Diffusion impact on atmospheric moisture transport

    NASA Astrophysics Data System (ADS)

    Moseley, C.; Haerter, J.; Göttel, H.; Hagemann, S.; Jacob, D.

    2009-04-01

    To ensure numerical stability, many global and regional climate models employ numerical diffusion to dampen short wavelength modes. Terrain following sigma diffusion is known to cause unphysical effects near the surface in orographically structured regions. They can be reduced by applying z-diffusion on geopotential height levels. We investigate the effect of the diffusion scheme on atmospheric moisture transport and precipitation formation at different resolutions in the European region. With respect to a better understanding of diffusion in current and future grid-space global models, current day regional models may serve as the appropriate tool for studies of the impact of diffusion schemes: Results can easily be constrained to a small test region and checked against reliable observations, which often are unavailable on a global scale. Special attention is drawn to the Alps - a region of strong topographic gradients and good observational coverage. Our study is further motivated by the appearance of the "summer drying problem" in South Eastern Europe. This too warm and too dry simulation of climate is common to many regional climate models and also to some global climate models, and remains a permanent unsolved problem in the community. We perform a systematic comparison of the two diffusion-schemes with respect to the hydrological cycle. In particular, we investigate how local meteorological quantities - such as the atmospheric moisture in the region east of the Alps - depend on the spatial model resolution. Higher model resolution would lead to a more accurate representation of the topography and entail larger gradients in the Alps. This could lead to consecutively stronger transport of moisture along the slopes in the case of sigma-diffusion with subsequent orographic precipitation, whereas the effect could be qualitatively different in the case of z-diffusion. For our study, we analyse a sequence of simulations of the regional climate model REMO employing

  11. Influence Function Learning in Information Diffusion Networks

    PubMed Central

    Du, Nan; Liang, Yingyu; Balcan, Maria-Florina; Song, Le

    2015-01-01

    Can we learn the influence of a set of people in a social network from cascades of information diffusion? This question is often addressed by a two-stage approach: first learn a diffusion model, and then calculate the influence based on the learned model. Thus, the success of this approach relies heavily on the correctness of the diffusion model which is hard to verify for real world data. In this paper, we exploit the insight that the influence functions in many diffusion models are coverage functions, and propose a novel parameterization of such functions using a convex combination of random basis functions. Moreover, we propose an efficient maximum likelihood based algorithm to learn such functions directly from cascade data, and hence bypass the need to specify a particular diffusion model in advance. We provide both theoretical and empirical analysis for our approach, showing that the proposed approach can provably learn the influence function with low sample complexity, be robust to the unknown diffusion models, and significantly outperform existing approaches in both synthetic and real world data. PMID:25973445

  12. Information diffusion in structured online social networks

    NASA Astrophysics Data System (ADS)

    Li, Pei; Zhang, Yini; Qiao, Fengcai; Wang, Hui

    2015-05-01

    Nowadays, due to the word-of-mouth effect, online social networks have been considered to be efficient approaches to conduct viral marketing, which makes it of great importance to understand the diffusion dynamics in online social networks. However, most research on diffusion dynamics in epidemiology and existing social networks cannot be applied directly to characterize online social networks. In this paper, we propose models to characterize the information diffusion in structured online social networks with push-based forwarding mechanism. We introduce the term user influence to characterize the average number of times that messages are browsed which is incurred by a given type user generating a message, and study the diffusion threshold, above which the user influence of generating a message will approach infinity. We conduct simulations and provide the simulation results, which are consistent with the theoretical analysis results perfectly. These results are of use in understanding the diffusion dynamics in online social networks and also critical for advertisers in viral marketing who want to estimate the user influence before posting an advertisement.

  13. Impacts of suppressing guide on information spreading

    NASA Astrophysics Data System (ADS)

    Xu, Jinghong; Zhang, Lin; Ma, Baojun; Wu, Ye

    2016-02-01

    It is quite common that guides are introduced to suppress the information spreading in modern society for different purposes. In this paper, an agent-based model is established to quantitatively analyze the impacts of suppressing guides on information spreading. We find that the spreading threshold depends on the attractiveness of the information and the topology of the social network with no suppressing guides at all. Usually, one would expect that the existence of suppressing guides in the spreading procedure may result in less diffusion of information within the overall network. However, we find that sometimes the opposite is true: the manipulating nodes of suppressing guides may lead to more extensive information spreading when there are audiences with the reversal mind. These results can provide valuable theoretical references to public opinion guidance on various information, e.g., rumor or news spreading.

  14. Diffusion processes of fragmentary information on scale-free networks

    NASA Astrophysics Data System (ADS)

    Li, Xun; Cao, Lang

    2016-05-01

    Compartmental models of diffusion over contact networks have proven representative of real-life propagation phenomena among interacting individuals. However, there is a broad class of collective spreading mechanisms departing from compartmental representations, including those for diffusive objects capable of fragmentation and transmission unnecessarily as a whole. Here, we consider a continuous-state susceptible-infected-susceptible (SIS) model as an ideal limit-case of diffusion processes of fragmentary information on networks, where individuals possess fractions of the information content and update them by selectively exchanging messages with partners in the vicinity. Specifically, we incorporate local information, such as neighbors' node degrees and carried contents, into the individual partner choice, and examine the roles of a variety of such strategies in the information diffusion process, both qualitatively and quantitatively. Our method provides an effective and flexible route of modulating continuous-state diffusion dynamics on networks and has potential in a wide array of practical applications.

  15. The electronic transfer of information and aerospace knowledge diffusion

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Bishop, Ann P.; Barclay, Rebecca O.; Kennedy, John M.

    1992-01-01

    Increasing reliance on and investment in information technology and electronic networking systems presupposes that computing and information technology will play a motor role in the diffusion of aerospace knowledge. Little is known, however, about actual information technology needs, uses, and problems within the aerospace knowledge diffusion process. The authors state that the potential contributions of information technology to increased productivity and competitiveness will be diminished unless empirically derived knowledge regarding the information-seeking behavior of the members of the social system - those who are producing, transferring, and using scientific and technical information - is incorporated into a new technology policy framework. Research into the use of information technology and electronic networks by U.S. aerospace engineers and scientists, collected as part of a research project designed to study aerospace knowledge diffusion, is presented in support of this assertion.

  16. Correlation between information diffusion and opinion evolution on social media

    NASA Astrophysics Data System (ADS)

    Xiong, Fei; Liu, Yun; Zhang, Zhenjiang

    2014-12-01

    Information diffusion and opinion evolution are often treated as two independent processes. Opinion models assume the topic reaches each agent and agents initially have their own ideas. In fact, the processes of information diffusion and opinion evolution often intertwine with each other. Whether the influence between these two processes plays a role in the system state is unclear. In this paper, we collected more than one million real data from a well-known social platform, and analysed large-scale user diffusion behaviour and opinion formation. We found that user inter-event time follows a two-scaling power-law distribution with two different power exponents. Public opinion stabilizes quickly and evolves toward the direction of convergence, but the consensus state is prevented by a few opponents. We propose a three-state opinion model accompanied by information diffusion. Agents form and exchange their opinions during information diffusion. Conversely, agents' opinions also influence their diffusion actions. Simulations show that the model with a correlation of the two processes produces similar statistical characteristics as empirical results. A fast epidemic process drives individual opinions to converge more obviously. Unlike previous epidemic models, the number of infected agents does not always increase with the update rate, but has a peak with an intermediate value of the rate.

  17. Multi-source information diffusion in online social networks

    NASA Astrophysics Data System (ADS)

    Xiong, Fei; Liu, Yun; Zhang, Hai-Feng

    2015-07-01

    Individual spreading behavior in online social networks is closely related to user activity, tie strength, and other user and network features. The results concentrate on personal spreading decisions; however, whether these features promote the global information diffusion and increase the macroscopic density of infected agents, remains unclear to us. In this paper, we propose a multi-source diffusion model in which agents may create new messages and spread other agents’ messages. Agents receive many messages, and each time they select a certain message preferentially to spread in consideration of different features. Simulation results show the density of infected agents for different messages follows a power-law distribution in both scale-free and small-world networks. Selecting the largest author degree, author activity and tie strength preferentially can advance the overall diffusion process. Weak tie bias is the least effective feature for multiple information diffusion, but it helps to diffuse a single message. Unexpectedly, the bias of interest similarity does not have an apparent effect. Integrated with the influence on individual diffusion behavior, strong tie bias is a significant feature both for local and global diffusion.

  18. Fluid Registration of Diffusion Tensor Images Using Information Theory

    PubMed Central

    Chiang, Ming-Chang; Leow, Alex D.; Klunder, Andrea D.; Dutton, Rebecca A.; Barysheva, Marina; Rose, Stephen E.; McMahon, Katie L.; de Zubicaray, Greig I.; Toga, Arthur W.; Thompson, Paul M.

    2008-01-01

    We apply an information-theoretic cost metric, the symmetrized Kullback-Leibler (sKL) divergence, or J-divergence, to fluid registration of diffusion tensor images. The difference between diffusion tensors is quantified based on the sKL-divergence of their associated probability density functions (PDFs). Three-dimensional DTI data from 34 subjects were fluidly registered to an optimized target image. To allow large image deformations but preserve image topology, we regularized the flow with a large-deformation diffeomorphic mapping based on the kinematics of a Navier-Stokes fluid. A driving force was developed to minimize the J-divergence between the deforming source and target diffusion functions, while reorienting the flowing tensors to preserve fiber topography. In initial experiments, we showed that the sKL-divergence based on full diffusion PDFs is adaptable to higher-order diffusion models, such as high angular resolution diffusion imaging (HARDI). The sKL-divergence was sensitive to subtle differences between two diffusivity profiles, showing promise for nonlinear registration applications and multisubject statistical analysis of HARDI data. PMID:18390342

  19. Discovery of Information Diffusion Process in Social Networks

    NASA Astrophysics Data System (ADS)

    Kim, Kwanho; Jung, Jae-Yoon; Park, Jonghun

    Information diffusion analysis in social networks is of significance since it enables us to deeply understand dynamic social interactions among users. In this paper, we introduce approaches to discovering information diffusion process in social networks based on process mining. Process mining techniques are applied from three perspectives: social network analysis, process discovery and community recognition. We then present experimental results by using a real-life social network data. The proposed techniques are expected to employ as new analytical tools in online social networks such as blog and wikis for company marketers, politicians, news reporters and online writers.

  20. The impact of network characteristics on the diffusion of innovations

    NASA Astrophysics Data System (ADS)

    Peres, Renana

    2014-05-01

    This paper studies the influence of network topology on the speed and reach of new product diffusion. While previous research has focused on comparing network types, this paper explores explicitly the relationship between topology and measurements of diffusion effectiveness. We study simultaneously the effect of three network metrics: the average degree, the relative degree of social hubs (i.e., the ratio of the average degree of highly-connected individuals to the average degree of the entire population), and the clustering coefficient. A novel network-generation procedure based on random graphs with a planted partition is used to generate 160 networks with a wide range of values for these topological metrics. Using an agent-based model, we simulate diffusion on these networks and check the dependence of the net present value (NPV) of the number of adopters over time on the network metrics. We find that the average degree and the relative degree of social hubs have a positive influence on diffusion. This result emphasizes the importance of high network connectivity and strong hubs. The clustering coefficient has a negative impact on diffusion, a finding that contributes to the ongoing controversy on the benefits and disadvantages of transitivity. These results hold for both monopolistic and duopolistic markets, and were also tested on a sample of 12 real networks.

  1. Anomalous Impact in Reaction-Diffusion Financial Models

    NASA Astrophysics Data System (ADS)

    Mastromatteo, I.; Tóth, B.; Bouchaud, J.-P.

    2014-12-01

    We generalize the reaction-diffusion model A +B → /0 in order to study the impact of an excess of A (or B ) at the reaction front. We provide an exact solution of the model, which shows that the linear response breaks down: the average displacement of the reaction front grows as the square root of the imbalance. We argue that this model provides a highly simplified but generic framework to understand the square-root impact of large orders in financial markets.

  2. Extracting spatial information from large aperture exposures of diffuse sources

    NASA Technical Reports Server (NTRS)

    Clarke, J. T.; Moos, H. W.

    1981-01-01

    The spatial properties of large aperture exposures of diffuse emission can be used both to investigate spatial variations in the emission and to filter out camera noise in exposures of weak emission sources. Spatial imaging can be accomplished both parallel and perpendicular to dispersion with a resolution of 5-6 arc sec, and a narrow median filter running perpendicular to dispersion across a diffuse image selectively filters out point source features, such as reseaux marks and fast particle hits. Spatial information derived from observations of solar system objects is presented.

  3. The Diffusion of Research on the Adoption and Diffusion of Information Technology

    NASA Astrophysics Data System (ADS)

    Dwivedi, Yogesh K.; Williams, Michael D.; Lal, Banita

    The considerable level of investigation into information systems and technology acceptance and diffusion to date has witnessed the use of an extensive range of exploratory techniques examining numerous diverse systems and technologies in a myriad of different contexts. The aim of this paper is to provide a comprehensive and systematic review of the literature relating to such adoption and diffusion issues in order to establish the current "state of play" in the domain along a number of dimensions including unit of analysis, research paradigm employed, technology examined, and theoretical models and constructs. Our findings suggest that the positivist paradigm, empirical and quantitative research, the survey method, and TAM theory were used predominantly when investigating the topics of adoption and diffusion of technology. Although the adoption of broad range of technologies has been examined, our results indicate that a number of technologies have so far received relatively little investigative attention.

  4. Information Technology Diffusion in Academic Teaching: An Institutional Perspective

    NASA Astrophysics Data System (ADS)

    Naveh, Gali; Tubin, Dorit; Pliskin, Nava

    Even though diffusion of information and communication technology (ICT) in academic teaching has been fast, the expected benefits in pedagogy and structure have yet to materialize. Rogers' diffusion theory, which focuses on adoption and rejection of innovation, can explain the proliferation of ICT usage in academia, but the lack of ICT-based pedagogical and structural changes are beyond the scope of diffusion theory. The objective of this paper is to broaden the theoretical base for explaining the state of ICT in academia via the alternative conceptual lens of institutional theory, which focuses on the relationship between the organization and its environment. With the institutional theory perspective in mind, we suggest that further pedagogical and structural changes in academic courses should not be expected as a result of ICT implementation in academic teaching.

  5. Maximizing Information Diffusion in the Cyber-physical Integrated Network.

    PubMed

    Lu, Hongliang; Lv, Shaohe; Jiao, Xianlong; Wang, Xiaodong; Liu, Juan

    2015-01-01

    Nowadays, our living environment has been embedded with smart objects, such as smart sensors, smart watches and smart phones. They make cyberspace and physical space integrated by their abundant abilities of sensing, communication and computation, forming a cyber-physical integrated network. In order to maximize information diffusion in such a network, a group of objects are selected as the forwarding points. To optimize the selection, a minimum connected dominating set (CDS) strategy is adopted. However, existing approaches focus on minimizing the size of the CDS, neglecting an important factor: the weight of links. In this paper, we propose a distributed maximizing the probability of information diffusion (DMPID) algorithm in the cyber-physical integrated network. Unlike previous approaches that only consider the size of CDS selection, DMPID also considers the information spread probability that depends on the weight of links. To weaken the effects of excessively-weighted links, we also present an optimization strategy that can properly balance the two factors. The results of extensive simulation show that DMPID can nearly double the information diffusion probability, while keeping a reasonable size of selection with low overhead in different distributed networks. PMID:26569254

  6. Information Filtering via Heterogeneous Diffusion in Online Bipartite Networks

    PubMed Central

    Zhang, Fu-Guo; Zeng, An

    2015-01-01

    The rapid expansion of Internet brings us overwhelming online information, which is impossible for an individual to go through all of it. Therefore, recommender systems were created to help people dig through this abundance of information. In networks composed by users and objects, recommender algorithms based on diffusion have been proven to be one of the best performing methods. Previous works considered the diffusion process from user to object, and from object to user to be equivalent. We show in this work that it is not the case and we improve the quality of the recommendation by taking into account the asymmetrical nature of this process. We apply this idea to modify the state-of-the-art recommendation methods. The simulation results show that the new methods can outperform these existing methods in both recommendation accuracy and diversity. Finally, this modification is checked to be able to improve the recommendation in a realistic case. PMID:26125631

  7. Social Information Transmission in Animals: Lessons from Studies of Diffusion.

    PubMed

    Duboscq, Julie; Romano, Valéria; MacIntosh, Andrew; Sueur, Cédric

    2016-01-01

    The capacity to use information provided by others to guide behavior is a widespread phenomenon in animal societies. A standard paradigm to test if and/or how animals use and transfer social information is through social diffusion experiments, by which researchers observe how information spreads within a group, sometimes by seeding new behavior in the population. In this article, we review the context, methodology and products of such social diffusion experiments. Our major focus is the transmission of information from an individual (or group thereof) to another, and the factors that can enhance or, more interestingly, inhibit it. We therefore also discuss reasons why social transmission sometimes does not occur despite being expected to. We span a full range of mechanisms and processes, from the nature of social information itself and the cognitive abilities of various species, to the idea of social competency and the constraints imposed by the social networks in which animals are embedded. We ultimately aim at a broad reflection on practical and theoretical issues arising when studying how social information spreads within animal groups. PMID:27540368

  8. Social Information Transmission in Animals: Lessons from Studies of Diffusion

    PubMed Central

    Duboscq, Julie; Romano, Valéria; MacIntosh, Andrew; Sueur, Cédric

    2016-01-01

    The capacity to use information provided by others to guide behavior is a widespread phenomenon in animal societies. A standard paradigm to test if and/or how animals use and transfer social information is through social diffusion experiments, by which researchers observe how information spreads within a group, sometimes by seeding new behavior in the population. In this article, we review the context, methodology and products of such social diffusion experiments. Our major focus is the transmission of information from an individual (or group thereof) to another, and the factors that can enhance or, more interestingly, inhibit it. We therefore also discuss reasons why social transmission sometimes does not occur despite being expected to. We span a full range of mechanisms and processes, from the nature of social information itself and the cognitive abilities of various species, to the idea of social competency and the constraints imposed by the social networks in which animals are embedded. We ultimately aim at a broad reflection on practical and theoretical issues arising when studying how social information spreads within animal groups. PMID:27540368

  9. Impact Acceleration Model of Diffuse Traumatic Brain Injury.

    PubMed

    Hellewell, Sarah C; Ziebell, Jenna M; Lifshitz, Jonathan; Morganti-Kossmann, M Cristina

    2016-01-01

    The impact acceleration (I/A) model of traumatic brain injury (TBI) was developed to reliably induce diffuse traumatic axonal injury in rats in the absence of skull fractures and parenchymal focal lesions. This model replicates a pathophysiology that is commonly observed in humans with diffuse axonal injury (DAI) caused by acceleration-deceleration forces. Such injuries are typical consequences of motor vehicle accidents and falls, which do not necessarily require a direct impact to the closed skull. There are several desirable characteristics of the I/A model, including the extensive axonal injury produced in the absence of a focal contusion, the suitability for secondary insult modeling, and the adaptability for mild/moderate injury through alteration of height and/or weight. Furthermore, the trauma device is inexpensive and readily manufactured in any laboratory, and the induction of injury is rapid (~45 min per animal from weighing to post-injury recovery) allowing multiple animal experiments per day. In this chapter, we describe in detail the methodology and materials required to produce the rat model of I/A in the laboratory. We also review current adaptations to the model to alter injury severity, discuss frequent complications and technical issues encountered using this model, and provide recommendations to ensure technically sound injury induction. PMID:27604723

  10. Mechanical vs. informational components of price impact

    NASA Astrophysics Data System (ADS)

    Doyne Farmer, J.; Zamani, N.

    2007-01-01

    We study the problem of what causes prices to change. It is well known that trading impacts prices — orders to buy drive the price up, and orders to sell drive it down. We introduce a means of decomposing the total impact of trading into two components, defining the mechanical impact of a trading order as the change in future prices in the absence of any future changes in decision making, and the informational impact as the remainder of the total impact once mechanical impact is removed. This decomposition is performed using order book data from the London Stock Exchange. The average mechanical impact of a market order decays to zero as a function of time, at an asymptotic rate that is consistent with a power law with an exponent of roughly 1.7. In contrast the average informational impact builds to approach a constant value. Initially the impact is entirely mechanical, and is about half as big as the asymptotic informational impact. The size of the informational impact is positively correlated to mechanical impact. For cases where the mechanical impact is zero for all times, we find that the informational impact is negative, i.e. buy market orders that have no mechanical impact at all generate strong negative price responses.

  11. Suppressing disease spreading by using information diffusion on multiplex networks

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Liu, Quan-Hui; Cai, Shi-Min; Tang, Ming; Braunstein, Lidia A.; Stanley, H. Eugene

    2016-07-01

    Although there is always an interplay between the dynamics of information diffusion and disease spreading, the empirical research on the systemic coevolution mechanisms connecting these two spreading dynamics is still lacking. Here we investigate the coevolution mechanisms and dynamics between information and disease spreading by utilizing real data and a proposed spreading model on multiplex network. Our empirical analysis finds asymmetrical interactions between the information and disease spreading dynamics. Our results obtained from both the theoretical framework and extensive stochastic numerical simulations suggest that an information outbreak can be triggered in a communication network by its own spreading dynamics or by a disease outbreak on a contact network, but that the disease threshold is not affected by information spreading. Our key finding is that there is an optimal information transmission rate that markedly suppresses the disease spreading. We find that the time evolution of the dynamics in the proposed model qualitatively agrees with the real-world spreading processes at the optimal information transmission rate.

  12. Suppressing disease spreading by using information diffusion on multiplex networks.

    PubMed

    Wang, Wei; Liu, Quan-Hui; Cai, Shi-Min; Tang, Ming; Braunstein, Lidia A; Stanley, H Eugene

    2016-01-01

    Although there is always an interplay between the dynamics of information diffusion and disease spreading, the empirical research on the systemic coevolution mechanisms connecting these two spreading dynamics is still lacking. Here we investigate the coevolution mechanisms and dynamics between information and disease spreading by utilizing real data and a proposed spreading model on multiplex network. Our empirical analysis finds asymmetrical interactions between the information and disease spreading dynamics. Our results obtained from both the theoretical framework and extensive stochastic numerical simulations suggest that an information outbreak can be triggered in a communication network by its own spreading dynamics or by a disease outbreak on a contact network, but that the disease threshold is not affected by information spreading. Our key finding is that there is an optimal information transmission rate that markedly suppresses the disease spreading. We find that the time evolution of the dynamics in the proposed model qualitatively agrees with the real-world spreading processes at the optimal information transmission rate. PMID:27380881

  13. Suppressing disease spreading by using information diffusion on multiplex networks

    PubMed Central

    Wang, Wei; Liu, Quan-Hui; Cai, Shi-Min; Tang, Ming; Braunstein, Lidia A.; Stanley, H. Eugene

    2016-01-01

    Although there is always an interplay between the dynamics of information diffusion and disease spreading, the empirical research on the systemic coevolution mechanisms connecting these two spreading dynamics is still lacking. Here we investigate the coevolution mechanisms and dynamics between information and disease spreading by utilizing real data and a proposed spreading model on multiplex network. Our empirical analysis finds asymmetrical interactions between the information and disease spreading dynamics. Our results obtained from both the theoretical framework and extensive stochastic numerical simulations suggest that an information outbreak can be triggered in a communication network by its own spreading dynamics or by a disease outbreak on a contact network, but that the disease threshold is not affected by information spreading. Our key finding is that there is an optimal information transmission rate that markedly suppresses the disease spreading. We find that the time evolution of the dynamics in the proposed model qualitatively agrees with the real-world spreading processes at the optimal information transmission rate. PMID:27380881

  14. Diffused holographic information storage and retrieval using photorefractive optical materials

    NASA Astrophysics Data System (ADS)

    McMillen, Deanna Kay

    Holography offers a tremendous opportunity for dense information storage, theoretically one bit per cubic wavelength of material volume, with rapid retrieval, of up to thousands of pages of information simultaneously. However, many factors prevent the theoretical storage limit from being reached, including dynamic range problems and imperfections in recording materials. This research explores new ways of moving closer to practical holographic information storage and retrieval by altering the recording materials, in this case, photorefractive crystals, and by increasing the current storage capacity while improving the information retrieved. As an experimental example of the techniques developed, the information retrieved is the correlation peak from an optical recognition architecture, but the materials and methods developed are applicable to many other holographic information storage systems. Optical correlators can potentially solve any signal or image recognition problem. Military surveillance, fingerprint identification for law enforcement or employee identification, and video games are but a few examples of applications. A major obstacle keeping optical correlators from being universally accepted is the lack of a high quality, thick (high capacity) holographic recording material that operates with red or infrared wavelengths which are available from inexpensive diode lasers. This research addresses the problems from two positions: find a better material for use with diode lasers, and reduce the requirements placed on the material while maintaining an efficient and effective system. This research found that the solutions are new dopants introduced into photorefractive lithium niobate to improve wavelength sensitivities and the use of a novel inexpensive diffuser that reduces the dynamic range and optical element quality requirements (which reduces the cost) while improving performance. A uniquely doped set of 12 lithium niobate crystals was specified and

  15. Nitrogen diffusion in hafnia and the impact of nitridation on oxygen and hydrogen diffusion: A first-principles study

    NASA Astrophysics Data System (ADS)

    Sathiyanarayanan, Rajesh; Pandey, R. K.; Murali, K. V. R. M.

    2015-01-01

    Using first-principles simulations, we have computed incorporation energies and diffusion barriers of ammonia, the nitrogen molecule and atomic nitrogen in monoclinic hafnia (m-HfO2). Our calculations show that ammonia is likely to dissociate into an NH2 molecular unit, whereas the nitrogen molecule remains as a molecule either in the interstitial space or at an oxygen lattice site. The lowest energy pathway for the diffusion of atomic nitrogen interstitials consists of the hopping of the nitrogen interstitial between neighboring three-coordinated lattice oxygen atoms that share a single Hf atom, and the barrier for such hops is determined by a switching mechanism. The substitutional nitrogen atom shows a preference for diffusion through the doubly positive oxygen vacancy-mediated mechanism. Furthermore, we have investigated the impact of nitrogen atoms on the diffusion barriers of oxygen and hydrogen interstitials in m-HfO2. Our results show that nitrogen incorporation has a significant impact on the barriers for oxygen and hydrogen diffusion: nitrogen atoms attract oxygen and hydrogen interstitials diffusing in the vicinity, thereby slowing down (reducing) their diffusion (diffusion length).

  16. Nitrogen diffusion in hafnia and the impact of nitridation on oxygen and hydrogen diffusion: A first-principles study

    SciTech Connect

    Sathiyanarayanan, Rajesh E-mail: rajesh.sathiyanarayanan@gmail.com; Pandey, R. K.; Murali, K. V. R. M.

    2015-01-21

    Using first-principles simulations, we have computed incorporation energies and diffusion barriers of ammonia, the nitrogen molecule and atomic nitrogen in monoclinic hafnia (m-HfO{sub 2}). Our calculations show that ammonia is likely to dissociate into an NH{sub 2} molecular unit, whereas the nitrogen molecule remains as a molecule either in the interstitial space or at an oxygen lattice site. The lowest energy pathway for the diffusion of atomic nitrogen interstitials consists of the hopping of the nitrogen interstitial between neighboring three-coordinated lattice oxygen atoms that share a single Hf atom, and the barrier for such hops is determined by a switching mechanism. The substitutional nitrogen atom shows a preference for diffusion through the doubly positive oxygen vacancy-mediated mechanism. Furthermore, we have investigated the impact of nitrogen atoms on the diffusion barriers of oxygen and hydrogen interstitials in m-HfO{sub 2}. Our results show that nitrogen incorporation has a significant impact on the barriers for oxygen and hydrogen diffusion: nitrogen atoms attract oxygen and hydrogen interstitials diffusing in the vicinity, thereby slowing down (reducing) their diffusion (diffusion length)

  17. NASA/DoD Aerospace Knowledge Diffusion Research Project. Paper 30: The electronic transfer of information and aerospace knowledge diffusion

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Bishop, Ann P.; Barclay, Rebecca O.; Kennedy, John M.

    1992-01-01

    Increasing reliance on and investment in information technology and electronic networking systems presupposes that computing and information technology will play a major role in the diffusion of aerospace knowledge. Little is known, however, about actual information technology needs, uses, and problems within the aerospace knowledge diffusion process. The authors state that the potential contributions of information technology to increased productivity and competitiveness will be diminished unless empirically derived knowledge regarding the information-seeking behavior of the members of the social system - those who are producing, transferring, and using scientific and technical information - is incorporated into a new technology policy framework. Research into the use of information technology and electronic networks by U.S. aerospace engineers and scientists, collected as part of a research project designed to study aerospace knowledge diffusion, is presented in support of this assertion.

  18. Modeling of Information Diffusion in Twitter-Like Social Networks under Information Overload

    PubMed Central

    Li, Wei

    2014-01-01

    Due to the existence of information overload in social networks, it becomes increasingly difficult for users to find useful information according to their interests. This paper takes Twitter-like social networks into account and proposes models to characterize the process of information diffusion under information overload. Users are classified into different types according to their in-degrees and out-degrees, and user behaviors are generalized into two categories: generating and forwarding. View scope is introduced to model the user information-processing capability under information overload, and the average number of times a message appears in view scopes after it is generated by a given type user is adopted to characterize the information diffusion efficiency, which is calculated theoretically. To verify the accuracy of theoretical analysis results, we conduct simulations and provide the simulation results, which are consistent with the theoretical analysis results perfectly. These results are of importance to understand the diffusion dynamics in social networks, and this analysis framework can be extended to consider more realistic situations. PMID:24795541

  19. A diffusive information preservation method for small Knudsen number flows

    NASA Astrophysics Data System (ADS)

    Fei, Fei; Fan, Jing

    2013-06-01

    The direct simulation Monte Carlo (DSMC) method is a powerful particle-based method for modeling gas flows. It works well for relatively large Knudsen (Kn) numbers, typically larger than 0.01, but quickly becomes computationally intensive as Kn decreases due to its time step and cell size limitations. An alternative approach was proposed to relax or remove these limitations, based on replacing pairwise collisions with a stochastic model corresponding to the Fokker-Planck equation [J. Comput. Phys., 229, 1077 (2010); J. Fluid Mech., 680, 574 (2011)]. Similar to the DSMC method, the downside of that approach suffers from computationally statistical noise. To solve the problem, a diffusion-based information preservation (D-IP) method has been developed. The main idea is to track the motion of a simulated molecule from the diffusive standpoint, and obtain the flow velocity and temperature through sampling and averaging the IP quantities. To validate the idea and the corresponding model, several benchmark problems with Kn ˜ 10-3-10-4 have been investigated. It is shown that the IP calculations are not only accurate, but also efficient because they make possible using a time step and cell size over an order of magnitude larger than the mean collision time and mean free path, respectively.

  20. A diffusive information preservation method for small Knudsen number flows

    SciTech Connect

    Fei, Fei; Fan, Jing

    2013-06-15

    The direct simulation Monte Carlo (DSMC) method is a powerful particle-based method for modeling gas flows. It works well for relatively large Knudsen (Kn) numbers, typically larger than 0.01, but quickly becomes computationally intensive as Kn decreases due to its time step and cell size limitations. An alternative approach was proposed to relax or remove these limitations, based on replacing pairwise collisions with a stochastic model corresponding to the Fokker–Planck equation [J. Comput. Phys., 229, 1077 (2010); J. Fluid Mech., 680, 574 (2011)]. Similar to the DSMC method, the downside of that approach suffers from computationally statistical noise. To solve the problem, a diffusion-based information preservation (D-IP) method has been developed. The main idea is to track the motion of a simulated molecule from the diffusive standpoint, and obtain the flow velocity and temperature through sampling and averaging the IP quantities. To validate the idea and the corresponding model, several benchmark problems with Kn ∼ 10{sup −3}–10{sup −4} have been investigated. It is shown that the IP calculations are not only accurate, but also efficient because they make possible using a time step and cell size over an order of magnitude larger than the mean collision time and mean free path, respectively.

  1. Information filtering by similarity-preferential diffusion processes

    NASA Astrophysics Data System (ADS)

    Zeng, An; Vidmer, Alexandre; Medo, Matúš; Zhang, Yi-Cheng

    2014-03-01

    Recommender systems provide a promising way to address the information overload problem which is common in online systems. Based on past user preferences, a recommender system can find items that are likely to be relevant to a given user. Two classical physical processes, mass diffusion and heat conduction, have been used to design recommendation algorithms and a hybrid process based on them has been shown to provide accurate and diverse recommendation results. We modify both processes as well as their hybrid by introducing a parameter which can be used to enhance or suppress the weight of users who are most similar to the target user for whom the recommendation is done. Evaluation on two benchmark data sets demonstrates that both recommendation accuracy and diversity are improved for a wide range of parameter values. Threefold validation indicates that the achieved results are robust and the new recommendation methods are thus applicable in practice.

  2. Engaging farmers to inform future diffuse pollution policy in England

    NASA Astrophysics Data System (ADS)

    Vrain, Emilie; Lovett, Andrew; Nobel, Lister; Grant, Fiona; Blundell, Paul; Cleasby, Will

    2013-04-01

    Stakeholder knowledge and engagement is increasingly seen as a necessary ingredient for catchment management. Whilst many agricultural management options remain voluntary, the implementation of diffuse pollution mitigation measures will only be effective with the cooperation of stakeholders. Anthony et al. (2009) and Zhang et al. (2012) state the need for more information on the realistic farmer uptake of methods to enhance analyses of the potential for pollution mitigation. A study engaging farmers to understand current agricultural practices and their attitudes towards mitigation measures has formed part of the Demonstration Test Catchment (DTC) programme in England. Interviews with over seventy farmers were conducted during 2012 in three contrasting areas of the UK: the grassland dominated Eden catchment in the North West of England; the arable dominated Wensum catchment in East Anglia and the mixed farming of the Hampshire Avon catchment in southern England. Results from the farmer survey provide a baseline regarding current agricultural practices and give insight regarding attitudes to the adoption of other mitigation measures in the future. Opinions were obtained on eighty different measures taken from a recent guide to possible measures prepared for the UK government (Newell-Price et al., 2011). Analyses have been conducted examining how current use and attitudes towards future adoption of measures varies according to different characteristics of farm businesses. These findings will be of benefit to researchers, policy makers and farm advisers, particularly aiding decision making with respect to strategies for future implementation of programmes of measures. References. Anthony, S.G. et al., 2009. Quantitative assessment of scenarios for managing trade-off between the economic performance of agriculture and the environment and between different environmental media. Available at: http://randd.defra.gov.uk/Default

  3. Fisher statistics for analysis of diffusion tensor directional information.

    PubMed

    Hutchinson, Elizabeth B; Rutecki, Paul A; Alexander, Andrew L; Sutula, Thomas P

    2012-04-30

    A statistical approach is presented for the quantitative analysis of diffusion tensor imaging (DTI) directional information using Fisher statistics, which were originally developed for the analysis of vectors in the field of paleomagnetism. In this framework, descriptive and inferential statistics have been formulated based on the Fisher probability density function, a spherical analogue of the normal distribution. The Fisher approach was evaluated for investigation of rat brain DTI maps to characterize tissue orientation in the corpus callosum, fornix, and hilus of the dorsal hippocampal dentate gyrus, and to compare directional properties in these regions following status epilepticus (SE) or traumatic brain injury (TBI) with values in healthy brains. Direction vectors were determined for each region of interest (ROI) for each brain sample and Fisher statistics were applied to calculate the mean direction vector and variance parameters in the corpus callosum, fornix, and dentate gyrus of normal rats and rats that experienced TBI or SE. Hypothesis testing was performed by calculation of Watson's F-statistic and associated p-value giving the likelihood that grouped observations were from the same directional distribution. In the fornix and midline corpus callosum, no directional differences were detected between groups, however in the hilus, significant (p<0.0005) differences were found that robustly confirmed observations that were suggested by visual inspection of directionally encoded color DTI maps. The Fisher approach is a potentially useful analysis tool that may extend the current capabilities of DTI investigation by providing a means of statistical comparison of tissue structural orientation. PMID:22342971

  4. Diffusion of Electronic Medical Record Based Public Hospital Information Systems

    PubMed Central

    Cho, Kyoung Won; Kim, Seong Min; An, Chang-Ho

    2015-01-01

    Objectives This study was conducted to evaluate the adoption behavior of a newly developed Electronic Medical Record (EMR)-based information system (IS) at three public hospitals in Korea with a focus on doctors and nurses. Methods User satisfaction scores from four performance layers were analyzed before and two times after the newly develop system was introduced to evaluate the adoption process of the IS with Rogers' diffusion theory. Results The 'intention to use' scores, the most important indicator for determining whether or not to adopt the IS in Rogers' confirmation stage for doctors, were very high in the third survey (4.21). In addition, the scores for 'reduced medication errors', which is the key indicator for evaluating the success of the IS, increased in the third survey for both doctors and nurses. The factors influencing 'intention to use' with a high odds ratio (>1.5) were the 'frequency of attendance of user training sessions', 'mandatory use of system', 'reduced medication errors', and 'reduced medical record documentation time' for both doctors and nurses. Conclusions These findings show that the new EMR-based IS was well accepted by doctors. Both doctors and nurses also positively considered the effects of the new IS on their clinical environments. PMID:26279954

  5. Impact of osmotic stress on protein diffusion in Lactococcus lactis.

    PubMed

    Mika, Jacek T; Schavemaker, Paul E; Krasnikov, Victor; Poolman, Bert

    2014-11-01

    We measured translational diffusion of proteins in the cytoplasm and plasma membrane of the Gram-positive bacterium Lactococcus lactis and probed the effect of osmotic upshift. For cells in standard growth medium the diffusion coefficients for cytosolic proteins (27 and 582 kDa) and 12-transmembrane helix membrane proteins are similar to those in Escherichia coli. The translational diffusion of GFP in L. lactis drops by two orders of magnitude when the medium osmolality is increased by ∼ 1.9 Osm, and the decrease in mobility is partly reversed in the presence of osmoprotectants. We find a large spread in diffusion coefficients over the full population of cells but a smaller spread if only sister cells are compared. While in general the diffusion coefficients we measure under normal osmotic conditions in L. lactis are similar to those reported in E. coli, the decrease in translational diffusion upon osmotic challenge in L. lactis is smaller than in E. coli. An even more striking difference is that in L. lactis the GFP diffusion coefficient drops much more rapidly with volume than in E. coli. We discuss these findings in the light of differences in turgor, cell volume, crowding and cytoplasmic structure of Gram-positive and Gram-negative bacteria. PMID:25244659

  6. Sharing Health Information and Influencing Behavioral Intentions: The Role of Health Literacy, Information Overload, and the Internet in the Diffusion of Healthy Heart Information.

    PubMed

    Crook, Brittani; Stephens, Keri K; Pastorek, Angie E; Mackert, Michael; Donovan, Erin E

    2016-01-01

    Low health literacy remains an extremely common and problematic issue, given that individuals with lower health literacy are more likely to experience health challenges and negative health outcomes. In this study, we use the first three stages of the innovation-decision process found in the theory of diffusion of innovations (Rogers, 2003). We incorporate health literacy into a model explaining how perceived health knowledge, information sharing, attitudes, and behavior are related. Results show that health information sharing explains 33% of the variance in behavioral intentions, indicating that the communicative practice of sharing information can positively impact health outcomes. Further, individuals with high health literacy tend to share less information about heart health than those with lower health literacy. Findings also reveal that perceived heart-health knowledge operates differently than health literacy to predict health outcomes. PMID:25668744

  7. Structural limitations of learning in a crowd: communication vulnerability and information diffusion in MOOCs.

    PubMed

    Gillani, Nabeel; Yasseri, Taha; Eynon, Rebecca; Hjorth, Isis

    2014-01-01

    Massive Open Online Courses (MOOCs) bring together a global crowd of thousands of learners for several weeks or months. In theory, the openness and scale of MOOCs can promote iterative dialogue that facilitates group cognition and knowledge construction. Using data from two successive instances of a popular business strategy MOOC, we filter observed communication patterns to arrive at the "significant" interaction networks between learners and use complex network analysis to explore the vulnerability and information diffusion potential of the discussion forums. We find that different discussion topics and pedagogical practices promote varying levels of 1) "significant" peer-to-peer engagement, 2) participant inclusiveness in dialogue, and ultimately, 3) modularity, which impacts information diffusion to prevent a truly "global" exchange of knowledge and learning. These results indicate the structural limitations of large-scale crowd-based learning and highlight the different ways that learners in MOOCs leverage, and learn within, social contexts. We conclude by exploring how these insights may inspire new developments in online education. PMID:25244925

  8. Structural limitations of learning in a crowd: communication vulnerability and information diffusion in MOOCs

    NASA Astrophysics Data System (ADS)

    Gillani, Nabeel; Yasseri, Taha; Eynon, Rebecca; Hjorth, Isis

    2014-09-01

    Massive Open Online Courses (MOOCs) bring together a global crowd of thousands of learners for several weeks or months. In theory, the openness and scale of MOOCs can promote iterative dialogue that facilitates group cognition and knowledge construction. Using data from two successive instances of a popular business strategy MOOC, we filter observed communication patterns to arrive at the ``significant'' interaction networks between learners and use complex network analysis to explore the vulnerability and information diffusion potential of the discussion forums. We find that different discussion topics and pedagogical practices promote varying levels of 1) ``significant'' peer-to-peer engagement, 2) participant inclusiveness in dialogue, and ultimately, 3) modularity, which impacts information diffusion to prevent a truly ``global'' exchange of knowledge and learning. These results indicate the structural limitations of large-scale crowd-based learning and highlight the different ways that learners in MOOCs leverage, and learn within, social contexts. We conclude by exploring how these insights may inspire new developments in online education.

  9. Aesthetical Information Impact of a Literary Text.

    ERIC Educational Resources Information Center

    Malik, M. F.

    The aim of this study was to explore the aesthetic impact of a literary text on the human mind and to extend the knowledge on how and when the information from a book enters the human brain, and if and when it starts to be processed and, possibly, memorized. Readers' responses to aesthetic texts were measured through a series of biometric…

  10. An Evaluation of Project Information Packages (PIPs) as Used for the Diffusion of Bilingual Projects. Volume III: A Prototype Guide to Measuring Achievement Level and Program Impact on Achievement in Bilingual Projects.

    ERIC Educational Resources Information Center

    Horst, D. P.; And Others

    This report describes an evaluation of Project Information Packages (PIPs), sets of manuals and other materials intended to help a school district adopt and implement an exemplary education project. Four PIPs were evaluated in a field test, each PIP describing a different bilingual project. It was concluded that the awareness materials produced…

  11. Cellular Automata with network incubation in information technology diffusion

    NASA Astrophysics Data System (ADS)

    Guseo, Renato; Guidolin, Mariangela

    2010-06-01

    Innovation diffusion of network goods determines direct network externalities that depress sales for long periods and delay full benefits. We model this effect through a multiplicative dynamic market potential driven by a latent individual threshold embedded in a special Cellular Automata representation. The corresponding mean field approximation of its aggregate version is a Riccati equation with a closed form solution. This allows the detection of a change-point time separating an incubation period from a subsequent take-off due to a collective threshold (critical mass). Weighted nonlinear least squares are the main inferential methodology. An application is analysed with reference to USA fax machine diffusion.

  12. How reliable is online diffusion of medical information targeting patients and families?

    PubMed Central

    Xavier-Elsas, Pedro; Bastos, Sandra Epifânio; Gaspar-Elsas, Maria Ignez C

    2015-01-01

    AIM: To determine whether online diffusion of the “Ten Warning Signs of Primary Immunodeficiency Diseases (PID)’’ adheres to accepted scientific standards. METHODS: We analyzed how reproducible is online diffusion of a unique instrument, the “Ten Warning Signs of PID”, created by the Jeffrey Modell Foundation (JMF), by Google-assisted searches among highly visited sites from professional, academic and scientific organizations; governmental agencies; and patient support/advocacy organizations. We examined the diffusion, consistency of use and adequate referencing of this instrument. Where applicable, variant versions of the instrument were examined for changes in factual content that would have practical impact on physicians or on patients and their families. RESULTS: Among the first 100 sites identified by Google search, 85 faithfully reproduced the JMF model, and correctly referenced to its source. By contrast, the other 15 also referenced the JMF source but presented one or more changes in content relative to their purported model and therefore represent uncontrolled variants, of unknown origin. Discrepancies identified in the latter included changes in factual content of the original JMF list (C), as well as removal (R) and introduction (I) of novel signs (Table 2), all made without reference to any scientific publications that might account for the drastic changes in factual content. Factual changes include changes in the number of infectious episodes considered necessary to raise suspicion of PID, as well as the inclusion of various medical conditions not mentioned in the original. Together, these changes will affect the way physicians use the instrument to consult or to inform patients, and the way patients and families think about the need for specialist consultation in view of a possible PID diagnosis. CONCLUSION: The retrieved adaptations and variants, which significantly depart from the original instrument, raise concerns about standards for

  13. NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 19: Computer and information technology and aerospace knowledge diffusion

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Kennedy, John M.; Barclay, Rebecca O.; Bishop, Ann P.

    1992-01-01

    To remain a world leader in aerospace, the US must improve and maintain the professional competency of its engineers and scientists, increase the research and development (R&D) knowledge base, improve productivity, and maximize the integration of recent technological developments into the R&D process. How well these objectives are met, and at what cost, depends on a variety of factors, but largely on the ability of US aerospace engineers and scientists to acquire and process the results of federally funded R&D. The Federal Government's commitment to high speed computing and networking systems presupposes that computer and information technology will play a major role in the aerospace knowledge diffusion process. However, we know little about information technology needs, uses, and problems within the aerospace knowledge diffusion process. The use of computer and information technology by US aerospace engineers and scientists in academia, government, and industry is reported.

  14. Seconds After Impact: Insights from Diffusion Between Lechatelierite and Host Glass in Tektites and Experiments

    NASA Astrophysics Data System (ADS)

    Macris, C. A.; Badro, J.; Asimow, P. D.; Eiler, J. M.; Stolper, E. D.

    2014-09-01

    This study exploits the presence of lechatelierites in tektites to extract information about their thermal histories by investigating chemical diffusion between molten silica inclusions and surrounding felsic melt in natural tektites and experiments.

  15. Does Collocation Inform the Impact of Collaboration?

    PubMed Central

    Lee, Kyungjoon; Brownstein, John S.; Mills, Richard G.; Kohane, Isaac S.

    2010-01-01

    Background It has been shown that large interdisciplinary teams working across geography are more likely to be impactful. We asked whether the physical proximity of collaborators remained a strong predictor of the scientific impact of their research as measured by citations of the resulting publications. Methodology/Principal Findings Articles published by Harvard investigators from 1993 to 2003 with at least two authors were identified in the domain of biomedical science. Each collaboration was geocoded to the precise three-dimensional location of its authors. Physical distances between any two coauthors were calculated and associated with corresponding citations. Relationship between distance of coauthors and citations for four author relationships (first-last, first-middle, last-middle, and middle-middle) were investigated at different spatial scales. At all sizes of collaborations (from two authors to dozens of authors), geographical proximity between first and last author is highly informative of impact at the microscale (i.e. within building) and beyond. The mean citation for first-last author relationship decreased as the distance between them increased in less than one km range as well as in the three categorized ranges (in the same building, same city, or different city). Such a trend was not seen in other three author relationships. Conclusions/Significance Despite the positive impact of emerging communication technologies on scientific research, our results provide striking evidence for the role of physical proximity as a predictor of the impact of collaborations. PMID:21179507

  16. Impact of molecular diffusion on the CO2 distribution and the temperature in the mesosphere

    NASA Astrophysics Data System (ADS)

    Chabrillat, Simon; Kockarts, Gaston; Fonteyn, Dominique; Brasseur, Guy

    2002-08-01

    Modelling the energy budget in the mesosphere and lower thermosphere requires a precise evaluation of CO2 distribution in this region. This distribution is primarily determined by competition between vertical eddy diffusion and molecular diffusion. A simple algorithm is proposed to take into account both processes, at all altitudes. Using the SOCRATES bi-dimensional model of the middle atmosphere, we show that molecular diffusion has a direct impact on CO2 vertical distribution down to approximately 80 km altitude, i.e. well into the mesosphere and below the turbopause altitude. A sensitivity study with regard to different aeronomical processes shows that molecular diffusion has the deepest influence in the mesospheric polar night region. Our model shows that molecular diffusion of CO2 is responsible for a polar night mesopause 12 K warmer than if this process was neglected. Hence, dynamical models should take this process in account across the whole mesospheric altitude range.

  17. Astrocytic Gliotransmitter: Diffusion Dynamics and Induction of Information Processing on Tripartite Synapses

    NASA Astrophysics Data System (ADS)

    Li, Jia-Jia; Du, Meng-Meng; Wang, Rong; Lei, Jin-Zhi; Wu, Ying

    Astrocytes have important functions in the central nervous system (CNS) and are significant in our understanding of the neuronal network. Astrocytes modulate neuronal firings at both single cell level of tripartite synapses and the neuron-glial network level. Astrocytes release adenosine triphosphate (ATP) and glutamate into the neuron-glial network. These gliotransmitters diffuse over the network to form long distance signals to regulate neuron firings. In this paper, we study a neuron-glial network model that includes a diffusion of astrocytic ATP and glutamate to investigate how long distance diffusion of the gliotransmitters affects the information processing in a neuronal network. We find that gliotransmitters diffusion can compensate for the failure of information processing of interneuron network firings induced by defectively coupled synapses. Moreover, we find that calcium waves in astrocyte network and firings in interneuron network are both sensitive to the glutamate diffusion rate and feedback intensities of astrocytes on interneurons.

  18. The free boundary problem describing information diffusion in online social networks

    NASA Astrophysics Data System (ADS)

    Lei, Chengxia; Lin, Zhigui; Wang, Haiyan

    In this paper we consider a free boundary problem for a reaction-diffusion logistic equation with a time-dependent growth rate. Such a problem arises in the modeling of information diffusion in online social networks, with the free boundary representing the spreading front of news among users. We present several sharp thresholds for information diffusion that either lasts forever or suspends in finite time. In the former case, we give the asymptotic spreading speed which is determined by a corresponding elliptic equation.

  19. Argon diffusion in Apollo 16 impact glass spherules: Implications for 40Ar/39Ar dating of lunar impact events

    NASA Astrophysics Data System (ADS)

    Gombosi, David J.; Baldwin, Suzanne L.; Watson, E. Bruce; Swindle, Timothy D.; Delano, John W.; Roberge, Wayne G.

    2015-01-01

    The 40Ar/39Ar technique applied to impact glass has been used to date both terrestrial and lunar impact events. The ability to utilize the 40Ar/39Ar technique rests on the assumption that impact glasses are closed to the loss of daughter product, 40Ar∗, after formation. Diffusion experiments were performed on three Apollo 16 lunar impact glasses and yielded activation energies for 39Ar of ∼17 to 20 kcal mol-1 and log10(D0/a2) values of -5.2 to -6.0 s-1. The resulting diffusion coefficients are interpreted as minimum values and the Apollo 16 glass is probably some of the least retentive of lunar glasses, as the degree of non-bridging oxygen is at one end of the range in lunar glasses. At temperatures below the glass transition temperature (i.e., ∼660 °C), the data can be explained by volume diffusion from a single diffusion domain. Modeling shows that Apollo 16 composition glass could lose significant quantities of radiogenic argon (40Ar∗) (∼90-100% over 20-40 Myr assuming a diffusion domain size (a) of 75 μm) due to diurnal temperature variations on the lunar surface, although 40Ar∗ loss is highly sensitive to exposure duration and effective diffusion domain size. Modeling shows that loss from transient thermal events (e.g., heating to ∼200 °C for 102 yr duration) can also cause partial resetting of apparent 40Ar/39Ar ages. In small (a = 75 μm) glasses a maximum of 50-60% of 40Ar∗ is lost over 4 Ga when buried to depths corresponding to temperatures of -15 °C. Results indicate that caution should be exercised in interpreting lunar impact glass 40Ar/39Ar ages, as the assumption of closed system behavior may have been violated, particularly in glasses with low fractions of non-bridging oxygen.

  20. How multiple social networks affect user awareness: The information diffusion process in multiplex networks

    NASA Astrophysics Data System (ADS)

    Li, Weihua; Tang, Shaoting; Fang, Wenyi; Guo, Quantong; Zhang, Xiao; Zheng, Zhiming

    2015-10-01

    The information diffusion process in single complex networks has been extensively studied, especially for modeling the spreading activities in online social networks. However, individuals usually use multiple social networks at the same time, and can share the information they have learned from one social network to another. This phenomenon gives rise to a new diffusion process on multiplex networks with more than one network layer. In this paper we account for this multiplex network spreading by proposing a model of information diffusion in two-layer multiplex networks. We develop a theoretical framework using bond percolation and cascading failure to describe the intralayer and interlayer diffusion. This allows us to obtain analytical solutions for the fraction of informed individuals as a function of transmissibility T and the interlayer transmission rate θ . Simulation results show that interaction between layers can greatly enhance the information diffusion process. And explosive diffusion can occur even if the transmissibility of the focal layer is under the critical threshold, due to interlayer transmission.

  1. Assessment of diffuse transmission and reflection modes in near-infrared quantification, part 2: DIFFuse reflection information depth.

    PubMed

    Saeed, Muhanned; Probst, Leila; Betz, Gabriele

    2011-03-01

    Near-infrared spectroscopy offers tremendous advantages for pharmaceutical manufacturing as a fast and nondestructive method of quantitative and qualitative analysis. Content uniformity (end-product analytics) and process analytics are two important applications of the method. Diffuse reflection (DR) information depth (vertical sampling span) assessment is of equal importance in content prediction applications and to understand the effect of inhomogeneities in the sample. Three experiments were conducted: (a) 0.5 to 10.0 mm incremental thickness MCC tablets with constant porosity, (b) MCC/phenylbutazone (PBZ) double-layered (DL) tablets (PBZ layer 0%-100% in 0.5 mm steps), and (c) Comparison of placebo and 30% caffeine tablet cores with incremental film coating (film thickness of 0-0.35 mm). Incremental thickness and cluster analysis of DL tablets showed that DR information depth was <0.5 mm, whereas the data fitting from incremental coating showed that signal drop reached 50% at 0.05 to 0.07 mm, depending on the wavenumber and 90% signal drop (10% information content) can be seen between 0.20 and 0.25 mm without extrapolation. These results mean that DR mode for pharmaceutical tablets obtains spectral information from the very surface, and radiation is barely reflected back from beyond thin-film coatings, making it less useful than diffuse transmission mode for core content analysis, especially for thick-coated, multilayer, multicore, or highly inhomogeneous tablets. PMID:20862671

  2. Epidemic model for information diffusion in web forums: experiments in marketing exchange and political dialog.

    PubMed

    Woo, Jiyoung; Chen, Hsinchun

    2016-01-01

    As social media has become more prevalent, its influence on business, politics, and society has become significant. Due to easy access and interaction between large numbers of users, information diffuses in an epidemic style on the web. Understanding the mechanisms of information diffusion through these new publication methods is important for political and marketing purposes. Among social media, web forums, where people in online communities disseminate and receive information, provide a good environment for examining information diffusion. In this paper, we model topic diffusion in web forums using the epidemiology model, the susceptible-infected-recovered (SIR) model, frequently used in previous research to analyze both disease outbreaks and knowledge diffusion. The model was evaluated on a large longitudinal dataset from the web forum of a major retail company and from a general political discussion forum. The fitting results showed that the SIR model is a plausible model to describe the diffusion process of a topic. This research shows that epidemic models can expand their application areas to topic discussion on the web, particularly social media such as web forums. PMID:26839759

  3. Coupled information diffusion--pest dynamics models predict delayed benefits of farmer cooperation in pest management programs.

    PubMed

    Rebaudo, François; Dangles, Olivier

    2011-10-01

    Worldwide, the theory and practice of agricultural extension system have been dominated for almost half a century by Rogers' "diffusion of innovation theory". In particular, the success of integrated pest management (IPM) extension programs depends on the effectiveness of IPM information diffusion from trained farmers to other farmers, an important assumption which underpins funding from development organizations. Here we developed an innovative approach through an agent-based model (ABM) combining social (diffusion theory) and biological (pest population dynamics) models to study the role of cooperation among small-scale farmers to share IPM information for controlling an invasive pest. The model was implemented with field data, including learning processes and control efficiency, from large scale surveys in the Ecuadorian Andes. Our results predict that although cooperation had short-term costs for individual farmers, it paid in the long run as it decreased pest infestation at the community scale. However, the slow learning process placed restrictions on the knowledge that could be generated within farmer communities over time, giving rise to natural lags in IPM diffusion and applications. We further showed that if individuals learn from others about the benefits of early prevention of new pests, then educational effort may have a sustainable long-run impact. Consistent with models of information diffusion theory, our results demonstrate how an integrated approach combining ecological and social systems would help better predict the success of IPM programs. This approach has potential beyond pest management as it could be applied to any resource management program seeking to spread innovations across populations. PMID:22022258

  4. NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 8: The role of the information intermediary in the diffusion of aerospace knowledge

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Kennedy, John M.; Barclay, Rebecca O.

    1990-01-01

    The United States aerospace industry is experiencing profound changes created by a combination of domestic actions and circumstances such as airline deregulation. Other changes result from external trends such as emerging foreign competition. These circumstances intensify the need to understand the production, transfer, and utilization of knowledge as a precursor to the rapid diffusion of technology. Presented here is a conceptual framework for understanding the diffusion of technology. A conceptual framework is given for understanding the diffusion of aerospace knowledge. The framework focuses on the information channels and members of the social system associated with the aerospace knowledge diffusion process, placing particular emphasis on aerospace librarians as information intermediaries.

  5. The Diffusion of Information Technology in the Human Services: Implications for Social Work Education

    ERIC Educational Resources Information Center

    Fitch, Dale

    2005-01-01

    The spread and utilization of information technology in the human services is examined using innovation diffusion theory. This examination is contextualized within the values basis of social work. Literature from the human services, the business sector, and the social sciences regarding the role of information technology is used to promote a…

  6. Information diffusion, Facebook clusters, and the simplicial model of social aggregation: a computational simulation of simplicial diffusers for community health interventions.

    PubMed

    Kee, Kerk F; Sparks, Lisa; Struppa, Daniele C; Mannucci, Mirco A; Damiano, Alberto

    2016-01-01

    By integrating the simplicial model of social aggregation with existing research on opinion leadership and diffusion networks, this article introduces the constructs of simplicial diffusers (mathematically defined as nodes embedded in simplexes; a simplex is a socially bonded cluster) and simplicial diffusing sets (mathematically defined as minimal covers of a simplicial complex; a simplicial complex is a social aggregation in which socially bonded clusters are embedded) to propose a strategic approach for information diffusion of cancer screenings as a health intervention on Facebook for community cancer prevention and control. This approach is novel in its incorporation of interpersonally bonded clusters, culturally distinct subgroups, and different united social entities that coexist within a larger community into a computational simulation to select sets of simplicial diffusers with the highest degree of information diffusion for health intervention dissemination. The unique contributions of the article also include seven propositions and five algorithmic steps for computationally modeling the simplicial model with Facebook data. PMID:26362453

  7. Impact of Moisture Content and Grain Size on Hydrocarbon Diffusion in Porous Media

    NASA Astrophysics Data System (ADS)

    McLain, A. A.; Ho, C. K.

    2001-12-01

    Diffusion of hydrocarbon vapors in porous media can play an important role in our ability to characterize subsurface contaminants such as trichloroethylene (TCE). For example, traditional monitoring methods often rely on direct sampling of contaminated soils or vapor. These samples may be influenced by the diffusion of vapors away from the contaminant source term, such as non-aqueous-phase TCE liquid. In addition, diffusion of hydrocarbon vapors can also impact the migration and dispersion of the contaminant in the subsurface. Therefore, understanding the diffusion rates and vapor transport processes of hydrocarbons in variably-saturated, heterogeneous porous media will assist in the characterization and detection of these subsurface contaminants. The purpose of this study was to investigate the impact of soil heterogeneity and water-moisture content on the diffusion processes for TCE. A one-dimensional column experiment was used to monitor the rates of vapor diffusion through sand. Experiments were performed with different average water-moisture contents and different grain sizes. On one end of the column, a reservoir cap is used to encase the TCE, providing a constant vapor boundary condition while sealing the end. The other end of the column contains a novel microchemical sensor. The sensor employs a polymer-absorption resistor (chemiresistor) that reversibly swells and increases in resistance when exposed to hydrocarbons. Once calibrated, the chemiresistors can be used to passively monitor vapor concentrations. This unique method allows the detection of in-situ vapor concentrations without disturbing the local environment. Results are presented in the form of vapor-concentration breakthrough curves as detected by the sensor. The shape of the breakthrough curve is dependent on several key parameters, including the length of the column and parameters (e.g., water-moisture content and grain-size) that affect the effective diffusion coefficient of TCE in air

  8. Organizational Factors that Influence Information Technology Diffusion in Academic Health Sciences Centers

    PubMed Central

    Ash, Joan

    1997-01-01

    Abstract Objective: To identify the organizational factors which influence the diffusion of end user online literature searching, the computer-based patient record, and electronic mail systems in academic health sciences centers in the United States. Design: A total of 1335 individuals working in informatics and library areas at 67 academic health sciences centers in the U.S. were surveyed. Multivariate techniques were used to evaluate the relationship between the set of six organizational factors and two measures of innovation diffusion. Measurements: A Guttman-like scale was developed to measure infusion, or depth or sophistication, of each of the three innovations at each institution. Diffusion was measured by a question previously developed for another study. Six independent variables were measured via five formerly developed scales and one new one. Results: The overall response rate was 41%. The set of organizational variables produced significant results in the diffusion of each of the three innovations, with individual variables influencing diffusion to varying degrees. The same set produced significant results in relation to infusion only for online searching. There was little or no correlation between infusion and diffusion for each innovation. Conclusion: Organizational attributes are important predictors for diffusion of information technology innovations. Individual variables differ in their effect on each innovation. The set of attributes seems less able to predict infusion. It is recommended that both infusion and diffusion be measured in future studies because there is little relation between them. It is further recommended that individuals charged with implementing information technology in the health sciences receive training in managing organizational issues. PMID:9067876

  9. 40Ar/39Ar ages of lunar impact glasses: Relationships among Ar diffusivity, chemical composition, shape, and size

    NASA Astrophysics Data System (ADS)

    Zellner, N. E. B.; Delano, J. W.

    2015-07-01

    Lunar impact glasses, which are quenched melts produced during cratering events on the Moon, have the potential to provide not only compositional information about both the local and regional geology of the Moon but also information about the impact flux over time. We present in this paper the results of 73 new 40Ar/39Ar analyses of well-characterized, inclusion-free lunar impact glasses and demonstrate that size, shape, chemical composition, fraction of radiogenic 40Ar retained, and cosmic ray exposure (CRE) ages are important for 40Ar/39Ar investigations of these samples. Specifically, analyses of lunar impact glasses from the Apollo 14, 16, and 17 landing sites indicate that retention of radiogenic 40Ar is a strong function of post-formation thermal history in the lunar regolith, size, and chemical composition. This is because the Ar diffusion coefficient (at a constant temperature) is estimated to decrease by ∼3-4 orders of magnitude with an increasing fraction of non-bridging oxygens, X(NBO), over the compositional range of most lunar impact glasses with compositions from feldspathic to basaltic. Based on these relationships, lunar impact glasses with compositions and sizes sufficient to have retained ∼90% of their radiogenic Ar during 750 Ma of cosmic ray exposure at time-integrated temperatures of up to 290 K have been identified and are likely to have yielded reliable 40Ar/39Ar ages of formation. Additionally, ∼50% of the identified impact glass spheres have formation ages of ⩽500 Ma, while ∼75% of the identified lunar impact glass shards and spheres have ages of formation ⩽2000 Ma. Higher thermal stresses in lunar impact glasses quenched from hyperliquidus temperatures are considered the likely cause of poor survival of impact glass spheres, as well as the decreasing frequency of lunar impact glasses in general with increasing age. The observed age-frequency distribution of lunar impact glasses may reflect two processes: (i) diminished

  10. Aesthetical Information Impact of Artworks on the Human Mind.

    ERIC Educational Resources Information Center

    Malik, M. F.

    The major areas of concern in this paper are the information and aesthetical impacts of artwork on the human mind, and the modes, structures, and media of artwork which influence the formulation of aesthetical impact. The analysis of aesthetical information impact follows current discoveries in the disciplines of biocybernetics, system and…

  11. The Impact of Biofilms on the Process of Back Diffusion From a Contaminated Rock Matrix

    NASA Astrophysics Data System (ADS)

    Yungwirth, G. A.; Novakowski, K. S.; Ross, N.

    2005-12-01

    are based on a cylindrical coordinate system where one equation was developed for the rock and another for the biofilm. The solution was found using the Laplace Transform method. Preliminary results show substantial biofilm growth, confirming that the method of biofilm stimulation is viable. Preliminary analysis of data from the diffusion experiments shows the impact of biofilm presence on back diffusion to be profound.

  12. Impact of radial and angular sampling on multiple shells acquisition in diffusion MRI.

    PubMed

    Merlet, Sylvain; Caruyer, Emmanuel; Deriche, Rachid

    2011-01-01

    We evaluate the impact of radial and angular sampling on multiple shells (MS) acquisition in diffusion MRI. The validation of our results is based on a new and efficient method to accurately reconstruct the Ensemble Average Propagator (EAP) in term of the Spherical Polar Fourier (SPF) basis from very few diffusion weighted magnetic resonance images (DW-MRI). This approach nicely exploits the duality between SPF and a closely related basis in which one can respectively represent the EAP and the diffusion signal using the same coefficients. We efficiently combine this relation to the recent acquisition and reconstruction technique called Compressed Sensing (CS). Based on results of multi-tensors models reconstruction, we show how to construct a robust acquisition scheme for both neural fibre orientation detection and attenuation signal/EAP reconstruction. PMID:21995020

  13. Impact of Information Entropy on Teaching Effectiveness

    ERIC Educational Resources Information Center

    Wang, Zhi-guo

    2007-01-01

    Information entropy refers to the process in which information is sent out from the information source, transmitted through information channel and acquired by information sink, while the teaching process is the one of transmitting teaching information from teachers and teaching material to students. How to improve teaching effectiveness is…

  14. Codimension-Two Bifurcation, Chaos and Control in a Discrete-Time Information Diffusion Model

    NASA Astrophysics Data System (ADS)

    Ren, Jingli; Yu, Liping

    2016-07-01

    In this paper, we present a discrete model to illustrate how two pieces of information interact with online social networks and investigate the dynamics of discrete-time information diffusion model in three types: reverse type, intervention type and mutualistic type. It is found that the model has orbits with period 2, 4, 6, 8, 12, 16, 20, 30, quasiperiodic orbit, and undergoes heteroclinic bifurcation near 1:2 point, a homoclinic structure near 1:3 resonance point and an invariant cycle bifurcated by period 4 orbit near 1:4 resonance point. Moreover, in order to regulate information diffusion process and information security, we give two control strategies, the hybrid control method and the feedback controller of polynomial functions, to control chaos, flip bifurcation, 1:2, 1:3 and 1:4 resonances, respectively, in the two-dimensional discrete system.

  15. The Diffusion of Health Information: Medicine Hucksters Can Teach Us Something.

    ERIC Educational Resources Information Center

    Simoni, Joseph J.; Ball, Richard A.

    During 1974, the role and effectiveness of the Mexican medicine huckster were examined within the context of a specified information diffusion process. Seventy-five hucksters were observed at work in three states of Mexico (Oaxaca, Michoacan, and Mexico) and in the Federal District (Mexico City area). Twenty-five sales pitches were recorded and…

  16. Spatial and Social Diffusion of Information and Influence: Models and Algorithms

    ERIC Educational Resources Information Center

    Doo, Myungcheol

    2012-01-01

    In this dissertation research, we argue that spatial alarms and activity-based social networks are two fundamentally new types of information and influence diffusion channels. Such new channels have the potential of enriching our professional experiences and our personal life quality in many unprecedented ways. First, we develop an activity driven…

  17. NASA/DoD aerospace knowledge diffusion research project. VIII - The role of the information intermediary in the diffusion of aerospace knowledge

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Kennedy, John M.; Barclay, Rebecca O.

    1990-01-01

    The U.S. aerospace industry is experiencing profound changes created by a combination of domestic actions and circumstances such as airline deregulation. Other changes result from external trends such as emerging foreign competition. These circumstances intensify the need to understand the production, transfer, and utilization of knowledge as a precursor to the rapid diffusion of technology. This article presents a conceptual framework for understanding the diffusion of aerospace knowledge. The framework focuses on the information channels and members of the social system associated with the aerospace knowledge diffusion process, placing particular emphasis on aerospace librarians as information intermediaries.

  18. Modeling bee swarming behavior through diffusion adaptation with asymmetric information sharing

    NASA Astrophysics Data System (ADS)

    Li, Jinchao; Sayed, Ali H.

    2012-12-01

    Honeybees swarm when they move to a new site for their hive. During the process of swarming, their behavior can be analyzed by classifying them as informed bees or uninformed bees, where the informed bees have some information about the destination while the uninformed bees follow the informed bees. The swarm's movement can be viewed as a network of mobile nodes with asymmetric information exchange about their destination. In these networks, adaptive and mobile agents share information on the fly and adapt their estimates in response to local measurements and data shared with neighbors. Diffusion adaptation is used to model the adaptation process in the presence of asymmetric nodes and noisy data. The simulations indicate that the models are able to emulate the swarming behavior of bees under varied conditions such as a small number of informed bees, sharing of target location, sharing of target direction, and noisy measurements.

  19. Impact and Roles of Drug Information in Drug Education

    ERIC Educational Resources Information Center

    Goodstadt, Michael S.

    1975-01-01

    Evidence is presented elucidating the role of knowledge about drugs in facilitating or impeding drug use. The issues considered include (1) the role of drug information in previous "education" programs, (2) the source and uses of drug information, (3) the impact of this information, and (4) the alternative roles for drug information. (Author)

  20. Maximizing Information Diffusion in the Cyber-physical Integrated Network †

    PubMed Central

    Lu, Hongliang; Lv, Shaohe; Jiao, Xianlong; Wang, Xiaodong; Liu, Juan

    2015-01-01

    Nowadays, our living environment has been embedded with smart objects, such as smart sensors, smart watches and smart phones. They make cyberspace and physical space integrated by their abundant abilities of sensing, communication and computation, forming a cyber-physical integrated network. In order to maximize information diffusion in such a network, a group of objects are selected as the forwarding points. To optimize the selection, a minimum connected dominating set (CDS) strategy is adopted. However, existing approaches focus on minimizing the size of the CDS, neglecting an important factor: the weight of links. In this paper, we propose a distributed maximizing the probability of information diffusion (DMPID) algorithm in the cyber-physical integrated network. Unlike previous approaches that only consider the size of CDS selection, DMPID also considers the information spread probability that depends on the weight of links. To weaken the effects of excessively-weighted links, we also present an optimization strategy that can properly balance the two factors. The results of extensive simulation show that DMPID can nearly double the information diffusion probability, while keeping a reasonable size of selection with low overhead in different distributed networks. PMID:26569254

  1. Impact of information technology on medicine

    SciTech Connect

    Shine, K.I.

    1996-12-31

    Although the health sciences will benefit from many of the advances in information technology that are applied to a wide variety of research areas, information technology is of particular importance to health care delivery. Developments of computerized patient records will enhance the efficiency effectiveness, and distribution of health care. As managed care programs develop, population-based information will be of increasing importance to health care providers and to the public health community. The capacity to transmit this information. 3 refs.

  2. Impacts by point and diffuse micropollutant sources on the stream water quality at catchment scale

    NASA Astrophysics Data System (ADS)

    Petersen, M. F.; Eriksson, E.; Binning, P. J.; Bjerg, P. L.

    2012-04-01

    The water quality of surface waters is threatened by multiple anthropogenic pollutants and the large variety of pollutants challenges the monitoring and assessment of the water quality. The aim of this study was to characterize and quantify both point and diffuse sources of micropollutants impacting the water quality of a stream at catchment scale. Grindsted stream in western Jutland, Denmark was used as a study site. The stream passes both urban and agricultural areas and is impacted by severe groundwater contamination in Grindsted city. Along a 12 km reach of Grindsted stream, the potential pollution sources were identified including a pharmaceutical factory site with a contaminated old drainage ditch, two waste deposits, a wastewater treatment plant, overflow structures, fish farms, industrial discharges and diffuse agricultural and urban sources. Six water samples were collected along the stream and analyzed for general water quality parameters, inorganic constituents, pesticides, sulfonamides, chlorinated solvents, BTEXs, and paracetamol and ibuprofen. The latter two groups were not detected. The general water quality showed typical conditions for a stream in western Jutland. Minor impacts by releases of organic matter and nutrients were found after the fish farms and the waste water treatment plant. Nickel was found at concentrations 5.8 - 8.8 μg/l. Nine pesticides and metabolites of both agricultural and urban use were detected along the stream; among these were the two most frequently detected and some rarely detected pesticides in Danish water courses. The concentrations were generally consistent with other findings in Danish streams and in the range 0.01 - 0.09 μg/l; except for metribuzin-diketo that showed high concentrations up to 0.74 μg/l. The groundwater contamination at the pharmaceutical factory site, the drainage ditch and the waste deposits is similar in composition containing among others sulfonamides and chlorinated solvents (including vinyl

  3. Impact of Information Technology in Academia

    ERIC Educational Resources Information Center

    Ranjan, Jayanthi

    2008-01-01

    Purpose--The purpose of this paper is to study the provisions of information technology IT for development of academic resources and examines the effect of IT in academic institutions for sharing information. Design/methodology/approach--The paper examines the role of IT in sharing information in academic institutions and explores the IT…

  4. The impact of gradient strength on in vivo diffusion MRI estimates of axon diameter

    PubMed Central

    Huang, Susie Y.; Nummenmaa, Aapo; Witzel, Thomas; Duval, Tanguy; Cohen-Adad, Julien; Wald, Lawrence L.; McNab, Jennifer A.

    2014-01-01

    Diffusion magnetic resonance imaging (MRI) methods for axon diameter mapping benefit from higher maximum gradient strengths than are currently available on commercial human scanners. Using a dedicated high-gradient 3 T human MRI scanner with a maximum gradient strength of 300 mT/m, we systematically studied the effect of gradient strength on in vivo axon diameter and density estimates in the human corpus callosum. Pulsed gradient spin echo experiments were performed in a single scan session lasting approximately 2 h on each of three human subjects. The data were then divided into subsets with maximum gradient strengths of 77, 145, 212, and 293 mT/m and diffusion times encompassing short (16 and 25 ms) and long (60 and 94 ms) diffusion time regimes. A three-compartment model of intra-axonal diffusion, extra-axonal diffusion, and free diffusion in cerebrospinal fluid was fitted to the data using a Markov chain Monte Carlo approach. For the acquisition parameters, model, and fitting routine used in our study, it was found that higher maximum gradient strengths decreased the mean axon diameter estimates by two to three fold and decreased the uncertainty in axon diameter estimates by more than half across the corpus callosum. The exclusive use of longer diffusion times resulted in axon diameter estimates that were up to two times larger than those obtained with shorter diffusion times. Axon diameter and density maps appeared less noisy and showed improved contrast between different regions of the corpus callosum with higher maximum gradient strength. Known differences in axon diameter and density between the genu, body, and splenium of the corpus callosum were preserved and became more reproducible at higher maximum gradient strengths. Our results suggest that an optimal q-space sampling scheme for estimating in vivo axon diameters should incorporate the highest possible gradient strength. The improvement in axon diameter and density estimates that we demonstrate from

  5. Replacement of chlorofluorocarbons at the DOE gaseous diffusion plants: An assessment of global impacts

    SciTech Connect

    Socolof, M.L.; McCold, L.N.; Saylor, R.E.

    1997-01-01

    Three gaseous diffusion plants (GDPs) for enriching uranium maintain a large inventory of chlorofluorocarbon-114 (CFC-114) as a coolant. To address the continued use of CFC-114, an ozone-depleting substance, the US Department of Energy (DOE) considered introducing perfluorocarbons (PFCs) by the end of 1995. These PFCs would not contribute to stratospheric ozone depletion but would be larger contributors to global warming than would CFC-114. The paper reports the results of an assessment of the global impacts of four alternatives for modifying GDP coolant system operations over a three-year period beginning in 1996. The overall contribution of GDP coolant releases to impacts on ozone depletion and global warming were quantified by parameters referred to as ozone-depletion impact and global-warming impact. The analysis showed that these parameters could be used as surrogates for predicting global impacts to all resources and could provide a framework for assessing environmental impacts of a permanent coolant replacement, eliminating the need for subsequent resource-specific analyses.

  6. Improvement of MODIS RSB calibration by minimizing the Earthshine impact on solar diffuser observations

    NASA Astrophysics Data System (ADS)

    Xie, X.; Xiong, X.; Wolfe, R.; Lyapustin, A.

    2006-08-01

    The MODerate Resolution Imaging Spectroraiometer (MODIS) reflective solar bands (RSB) are calibrated on-orbit using solar illuminations reflected from its onboard solar diffuser (SD) plate. The specified calibration uncertainty requirements for MODIS RSB are +/-2% in reflectance and +/-5% in radiance at their typical top of atmosphere (TOA) radiances. The onboard SD bi-directional reflectance factor (BRF) was characterized pre-launch by the instrument vendor using reference samples traceable to NIST reflectance standard. The SD on-orbit degradation is monitored using a solar diffuser stability monitor (SDSM). One of contributors to the RSB calibration uncertainty is the earthshine (ES) illumination on the SD plate during SD calibration. This effect was estimated pre-launch by the instrument vendor to be of 0.5% for all RSB bands. Analyses of on-orbit observations show that some of the SD calibration data sets have indeed been contaminated due to extra ES illumination and the degree of ES impact on the SD calibration is spectrally dependent and varies with geo-location and atmospheric conditions (ground surface type and cloudiness). This paper illustrates the observed ES impacts on the MODIS RSB calibration quality and compare them with the effects derived from an ES model based on the viewing geometry of MODIS SD aperture door and likelihood atmospheric conditions. It also describes an approach developed to minimize the ES impact on MODIS RSB calibration.

  7. Impact of Information Needs on Organizational Design.

    ERIC Educational Resources Information Center

    Burke, M. E.; Tulett, Karen

    1999-01-01

    Discusses the contingency approach to organizational design, information processing as a critical contingent of design, and use of organismic and mechanistic structures within an independent merchant bank. Proposes that a more appropriate model is needed which takes into account the changing nature of information processing and is flexible enough…

  8. The Information Impact: Ensuring New Product Winners.

    ERIC Educational Resources Information Center

    Trubkin, Loene

    Despite investment in new research tools and techniques, the product development success rate has not improved within the last 25 years. One way to increase the success rate is to have the right information at each stage of the process. Today, a relatively new method of gathering information--online access to electronic files called…

  9. An information diffusion model based on retweeting mechanism for online social media

    NASA Astrophysics Data System (ADS)

    Xiong, Fei; Liu, Yun; Zhang, Zhen-jiang; Zhu, Jiang; Zhang, Ying

    2012-06-01

    To characterize information propagation on online microblogs, we propose a diffusion model (SCIR) which contains four possible states: Susceptible, contacted, infected and refractory. Agents that read the information but have not decided to spread it, stay in the contacted state. They may become infected or refractory, and both the infected and refractory state are stable. Results show during the evolution process, more contacted agents appear in scale-free networks than in regular lattices. The degree based density of infected agents increases with the degree monotonously, but larger average network degree doesn't always mean less relaxation time.

  10. Replacement of chlorofluorocarbons (CFCs) at the DOE gaseous diffusion plants: An assessment of global impacts

    SciTech Connect

    Socolof, M.L.; Saylor, R.E.; McCold, L.N.

    1994-06-01

    The US Department of Energy (DOE) formerly operated two gaseous diffusion plants (GDPs) for enriching uranium and maintained a third shutdown GDP. These plants maintain a large inventory of dichlorotetrafluorethane (CFC-114), a cholorofluorocarbon (CFC), as a coolant. The paper evaluates the global impacts of four alternatives to modify GDP coolant system operations for a three-year period beginning in 1996. Interim modification of GDP coolant system operations has the potential to reduce stratospheric ozone depletion from GDP coolant releases while a permanent solution is studied.

  11. Positioning Education in the Information Society: The Transnational Diffusion of the Information and Communication Technology Curriculum

    ERIC Educational Resources Information Center

    Ham, Seung-Hwan; Cha, Yun-Kyung

    2009-01-01

    One of the most distinctive qualities that characterize present-day society is the social fact that people are shifting to the information age. In recent years, they have witnessed remarkable developments in information and communication technology (ICT), in which microelectronics, computers, and telecommunications have converged. Transnational…

  12. Digital Media and Education: Cognitive Impact of Information Visualization.

    ERIC Educational Resources Information Center

    Kraidy, Ute

    2002-01-01

    Argues that like other technological innovations, the rise of the digital information age is contributing to shape people's mode of cognition. Reviews the use of computers in teaching and learning in terms of their impact on our ability to process parallel data, access information in a non-linear order, and visualize information. (Author/LRW)

  13. Impact of imperfect information on network attack

    NASA Astrophysics Data System (ADS)

    Melchionna, Andrew; Caloca, Jesus; Squires, Shane; Antonsen, Thomas M.; Ott, Edward; Girvan, Michelle

    2015-03-01

    This paper explores the effectiveness of network attack when the attacker has imperfect information about the network. For Erdős-Rényi networks, we observe that dynamical importance and betweenness centrality-based attacks are surprisingly robust to the presence of a moderate amount of imperfect information and are more effective compared with simpler degree-based attacks even at moderate levels of network information error. In contrast, for scale-free networks the effectiveness of attack is much less degraded by a moderate level of information error. Furthermore, in the Erdős-Rényi case the effectiveness of network attack is much more degraded by missing links as compared with the same number of false links.

  14. Impact of imperfect information on network attack.

    PubMed

    Melchionna, Andrew; Caloca, Jesus; Squires, Shane; Antonsen, Thomas M; Ott, Edward; Girvan, Michelle

    2015-03-01

    This paper explores the effectiveness of network attack when the attacker has imperfect information about the network. For Erdős-Rényi networks, we observe that dynamical importance and betweenness centrality-based attacks are surprisingly robust to the presence of a moderate amount of imperfect information and are more effective compared with simpler degree-based attacks even at moderate levels of network information error. In contrast, for scale-free networks the effectiveness of attack is much less degraded by a moderate level of information error. Furthermore, in the Erdős-Rényi case the effectiveness of network attack is much more degraded by missing links as compared with the same number of false links. PMID:25871157

  15. Visualising Astronomy: Using Impact to Inform

    NASA Astrophysics Data System (ADS)

    Wyatt, R.

    2013-04-01

    Pop culture has visualised asteroids in a way that has made a far greater impact in the public domain than the outreach community can ever hope to achieve. Films such as Meteor (1979), Armageddon (1997) and Deep Impact (1997) may score poorly on scientific accuracy, but they have influenced our collective consciousness. (Perhaps in a fit of pre-millennial anxiety, the late 1990s saw a host of films featuring an asteroid or comet on a collision course with Earth1.) In addition to the destruction of Earth's cities, the Millennium Falcon dodging giant tumbling boulders in The Empire Strikes Back has probably influenced more people's mental image of an asteroid belt than any other single visual.

  16. Impact of diffuse mortality in a terrestrial biosphere model: stress, succession, and disease (Invited)

    NASA Astrophysics Data System (ADS)

    Dietze, M.

    2013-12-01

    Small changes in background mortality rate can have large impacts on forest composition, structure, and biogeochemical cycles. Despite this high sensitivity, the effects of mortality are absent from most ecosystem models and poorly constrained in the few models that explicitly represent mortality. Herein we explore the representation and uncertainties in diffuse mortality in the Ecosystem Demography model, a height- and successionally-structured terrestrial biosphere model. Modeled mortality is based on contributions from density independent effects, carbon balance effects, and frost effects. We also introduce a novel conceptual model for the representation of both diffuse (endemic) and epidemic forest pests and pathogens in earth system models. The sensitivity of forest mortality rates and carbon balance to different environmental factors is explored for eastern US forests and compared to national Forest Inventory and Analysis patterns. Specifically we assess the impacts of temperature, precipitation, CO2, elevation, slope, aspect, soil texture, lateral hydrology, successional status, tree size, and competitive interactions. Mortality was found to have the highest sensitivity to successional status, tree size, elevation, temperature, and CO2. Modeled sensitivity shows a strong correspondence with mortality patterns from forest inventory data. We also explore the dynamics of our conceptual disease model to represent forest responses to different disease classes, including phloem feeders, defoliators, cankers & wilts, stem rot, and root rot

  17. Impact of the emulsification-diffusion method on the development of pharmaceutical nanoparticles.

    PubMed

    Quintanar-Guerrero, David; Zambrano-Zaragoza, María de la Luz; Gutierrez-Cortez, Elsa; Mendoza-Munoz, Nestor

    2012-12-01

    Nanotechnology is having a profound impact in many scientific fields and it has become one of the most important and exciting discipline. Like all technological advances, nanotechnology has its own scientific basis with a broad interdisciplinary effect. Perhaps, we are witnessing an exponential growth of nanotechnology, reflection of this is the important increase in the number of patents, scientific papers and specialized "nano" meetings and journals. The impact in the pharmaceutical area is related to the use of colloidal drug delivery systems as carriers for bioactive agents, in particular, the nanoparticle technology. The term nanoparticles designates solid submicronic particles formed of acceptable materials (e.g. polymers, lipids, etc.) containing an active substance. It includes both nanospheres (matricial systems) and nanocapsules (membrane systems). The knowledge of the nanoparticle preparation methods is a key issue for the formulator involved with drug-delivery research and development. In general, the methods based on preformed polymers, in particular biodegradable polymers, are preferred due to their easy implementation and lower potential toxicity. One of the most widely used methods to prepare polymeric nanoparticles is emulsification-diffusion. This method has been discussed in some reviews that compile research works but has a small number of patents. In this review, the emulsification-diffusion method is discussed from a technological point of view in order to show the operating conditions and formulation variables from data extracted of recent patents and experimental works. The main idea is to provide the reader with a general guide for formulators to make decisions about the usefulness of this method to develop specific nanoparticulate systems. The first part of this review provides an overview of the emulsification-diffusion method to prepare polymeric nanoparticles, while the second part evaluates the influence of preparative variables on the

  18. Impacts of Geospatial Information for Decision Making

    NASA Astrophysics Data System (ADS)

    Pearlman, F.; Coote, A.; Friedl, L.; Stewart, M.

    2012-12-01

    Geospatial information contributes to decisions by both societal and individual decision-makers. More effective use of this information is essential as issues are increasingly complex and consequences can be critical for future economic and social development. To address this, a workshop brought together analysts, communicators, officials, and researchers from academia, government, non-governmental organizations, and the private sector. A range of policy issues, management needs, and resource requirements were discussed and a wide array of analyses, geospatial data, methods of analysis, and metrics were presented for assessing and communicating the value of geospatial information. It is clear that there are many opportunities for integrating science and engineering disciplines with the social sciences for addressing societal issues that would benefit from using geospatial information and earth observations. However, these collaborations must have outcomes that can be easily communicated to decision makers. This generally requires either succinct quantitative statements of value based on rigorous models and/or user testimonials of actual applications that save real money. An outcome of the workshop is to pursue the development of a community of practice or society that encompasses a wide range of scientific, social, management, and communication disciplines and fosters collaboration across specialties, helping to build trust across social and science aspects. A resource base is also necessary. This presentation will address approaches for creating a shared knowledge database, containing a glossary of terms, reference materials and examples of case studies and the potential applications for benefit analyses.

  19. The Impact of Information Technology on Information Science: Implications for Courses in the U.K.

    ERIC Educational Resources Information Center

    Oppenheim, Charles

    1983-01-01

    This essay discusses technological developments that are likely to have an impact on information science in next few years: microcomputers, satellite telecommunications, graphic information, online developments. Implications for the information profession, implications for information science courses, educational practice in 2001, and information…

  20. Impacts of intense inward and outward ULF wave radial diffusion on the Van Allen belts

    NASA Astrophysics Data System (ADS)

    Mann, Ian; Ozeke, Louis; Rae, I. Jonathan; Murphy, Kyle

    2016-07-01

    During geomagnetic storms, the power in ultra-low frequency (ULF) waves can be orders of magnitude larger than that predicted by statistics determined from an entire solar cycle. This is especially true during the main phase and early recovery phase. These periods of enhanced storm-time ULF wave power can have significant impacts on the morphology and structure of the Van Allen belts. Either fast inward or outward radial diffusion can result, depending on the profiles of the electron phase space density and the outer boundary condition at the edge of the belts. Small changes in the time sequence of powerful ULF waves, and the time sequence of any magnetopause shadowing or the recovery of plamasheet sources relative to the ULF wave occurrence, have a remarkable impact on the resulting structure of the belts. The overall impact of the enhanced ULF wave power is profound, but the response can be very different depending on the available source flux in the plasmasheet. We review these impacts by examining ultra-relativistic electron dynamics during seemingly different storms during the Van Allen Probe era, including during the Baker et al. third radiation belt, and show the observed behaviour can be largely explained by differences in the time sequence of events described above.

  1. Man-made black holes and Big Bangs: Diffusion and integration of scientific information into everyday thinking.

    PubMed

    Courvoisier, Nelly; Clémence, Alain; Green, Eva G T

    2013-04-01

    Drawing on Social Representations Theory, this study investigates focalisation and anchoring during the diffusion of information concerning the Large Hadron Collider (LHC), the particle accelerator at the European Organisation for Nuclear Research (CERN). We hypothesised that people focus on striking elements of the message, abandoning others, that the nature of the initial information affects diffusion of information, and that information is anchored in prior attitudes toward CERN and science. A serial reproduction experiment with two generations and four chains of reproduction diffusing controversial versus descriptive information about the LHC shows a reduction of information through generations, the persistence of terminology regarding the controversy and a decrease of other elements for participants exposed to polemical information. Concerning anchoring, positive attitudes toward CERN and science increase the use of expert terminology unrelated to the controversy. This research highlights the relevance of a social representational approach in the public understanding of science. PMID:23833055

  2. Evaluating the Impact of a Special Library and Information Service

    ERIC Educational Resources Information Center

    Botha, Erika; Erasmus, Rene; van Deventer, Martie

    2009-01-01

    The mere fact that a library service is being used does not mean that the service makes a difference or has a positive impact on the user. This has significant implications for Special Library and Information Services (SL&IS) that have to constantly prove that they add value. Because of the difficulty of measuring impact effectively, the majority…

  3. Diffusion of Impact Innovations to University Professors. A Final Report to the Exxon Education Foundation.

    ERIC Educational Resources Information Center

    Rogers, Everett M.; And Others

    Using four IMPACT innovations as examples (EXPER SIM, Guided Design, TIPS, and Student-to-Student Counseling), this study attempts to define the nature of technological and social changes in university teaching. Data were gathered in three phases: (1) a questionnaire was mailed to individuals who requested information; (2) the adopters of…

  4. Positional information and reaction-diffusion: two big ideas in developmental biology combine.

    PubMed

    Green, Jeremy B A; Sharpe, James

    2015-04-01

    One of the most fundamental questions in biology is that of biological pattern: how do the structures and shapes of organisms arise? Undoubtedly, the two most influential ideas in this area are those of Alan Turing's 'reaction-diffusion' and Lewis Wolpert's 'positional information'. Much has been written about these two concepts but some confusion still remains, in particular about the relationship between them. Here, we address this relationship and propose a scheme of three distinct ways in which these two ideas work together to shape biological form. PMID:25804733

  5. Information Technology and Aerospace Knowledge Diffusion: Exploring the Intermediary-End User Interface in a Policy Framework.

    ERIC Educational Resources Information Center

    Pinelli, Thomas E.; And Others

    1992-01-01

    Discusses U.S. technology policy and the transfer of scientific and technical information (STI). Results of a study of knowledge diffusion in the aerospace industry are reported, including data on aerospace information intermediaries, use of computer and information technologies, and the use of NASA (National Aeronautics and Space Administration)…

  6. NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 23: Information technology and aerospace knowledge diffusion: Exploring the intermediary-end user interface in a policy framework

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Barclay, Rebecca O.; Bishop, Ann P.; Kennedy, John M.

    1992-01-01

    Federal attempts to stimulate technological innovation have been unsuccessful because of the application of an inappropriate policy framework that lacks conceptual and empirical knowledge of the process of technological innovation and fails to acknowledge the relationship between knowled reproduction, transfer, and use as equally important components of the process of knowledge diffusion. It is argued that the potential contributions of high-speed computing and networking systems will be diminished unless empirically derived knowledge about the information-seeking behavior of the members of the social system is incorporated into a new policy framework. Findings from the NASA/DoD Aerospace Knowledge Diffusion Research Project are presented in support of this assertion.

  7. NASA/DoD Aerospace Knowledge Diffusion Research Project. XXIII - Information technology and aerospace knowledge diffusion: Exploring the intermediary-end user interface in a policy framework

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Barclay, Rebecca O.; Bishop, Ann P.; Kennedy, John M.

    1992-01-01

    Federal attempts to stimulate technological innovation have been unsuccessful because of the application of an inappropriate policy framework that lacks conceptual and empirical knowledge of the process of technological innovation and fails to acknowledge the relationship between knowledge production, transfer, and use as equally important components of the process of knowledge diffusion. This article argues that the potential contributions of high-speed computing and networking systems will be diminished unless empirically derived knowledge about the information-seeking behavior of members of the social system is incorporated into a new policy framework. Findings from the NASA/DoD Aerospace Knowledge Diffusion Research Project are presented in support of this assertion.

  8. Clinical impact of molecular features in diffuse large B-cell lymphoma and follicular lymphoma.

    PubMed

    Pon, Julia R; Marra, Marco A

    2016-01-14

    Our understanding of the pathogenesis and heterogeneity of diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) has been dramatically enhanced by recent attempts to profile molecular features of these lymphomas. In this article, we discuss ways in which testing for molecular features may impact DLBCL and FL management if clinical trials are designed to incorporate such tests. Specifically, we discuss how distinguishing lymphomas on the basis of cell-of-origin subtypes or the presence of other molecular features is prognostically and therapeutically significant. Conversely, we discuss how the molecular similarities of DLBCL and FL have provided insight into the potential of both DLBCL and FL cases to respond to agents targeting alterations they have in common. Through these examples, we demonstrate how the translation of our understanding of cancer biology into improvements in patient outcomes depends on analyzing the molecular correlates of treatment outcomes in clinical trials and in routinely treated patients. PMID:26447189

  9. Role of propagation thresholds in sentiment-based model of opinion evolution with information diffusion

    NASA Astrophysics Data System (ADS)

    Si, Xia-Meng; Wang, Wen-Dong; Ma, Yan

    2016-06-01

    The degree of sentiment is the key factor for internet users in determining their propagating behaviors, i.e. whether participating in a discussion and whether withdrawing from a discussion. For this end, we introduce two sentiment-based propagation thresholds (i.e. infected threshold and refractory threshold) and propose an interacting model based on the Bayesian updating rules. Our model describe the phenomena that few internet users change their decisions and that someone has drop out of discussion about the topic when some others are just aware of it. Numerical simulations show that, large infected threshold restrains information diffusion but favors the lessening of extremism, while large refractory threshold facilitates decision interaction but promotes the extremism. Making netizens calm down and propagate information sanely can restrain the prevailing of extremism about rumors.

  10. Impact of Horizontal Diffusion on T21, T42, and T63 Singular Vectors.

    NASA Astrophysics Data System (ADS)

    Buizza, Roberto

    1998-03-01

    The (linear) time evolution of singular vectors computed with a primitive equation model following a 36-h evolving trajectory is analyzed at horizontal triangular spectral truncations T21, T42, and T63.First, for each resolution, the impact of horizontal diffusion on the singular vectors characteristics (amplification factors, total energy spectra) is analyzed. Forecast error and singular vectors computed with different horizontal diffusion damping times are compared to assess whether, at each resolution, forecast error projection onto the first 10 most unstable singular vectors is maximized for specific values. Results suggest that better projections are obtained with horizontal diffusion damping times on the smallest scale (on divergence) of 3 h at T42 and T63 resolution, and of 12 h at T21.Then amplification factors, geographical locations, total energy vertical distributions, and spectra of T21, T42, and T63 singular vectors computed, respectively, with 12-, 3-, and 3-h damping time on the smallest scale are analyzed. The ratio among the singular vector amplification factors at T21:T42:T63 resolution is shown to be approximately 1:1.5:2.5. The geographical location and the total energy vertical distribution of T21, T42, and T63 singular vectors are quite similar. By contrast, total energy spectra differ substantially. Forecast error projection onto singular vectors is shown to be slightly larger if higher-resolution singular vectors are used. It is argued that the impact of horizontal resolution on the forecast error projection is marginal because of the lack of physical processes in the forward and adjoint tangent model versions. Moreover, the fact that forecast error projections onto the leading 10 singular vectors are rather small could be seen as an indication that more singular vectors are needed to capture the growing components of forecast error.Finally, singular vectors and forecast errors are compared to quantify the relevance of the singular vectors

  11. NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 48: Valuing information in an interactive environment

    NASA Technical Reports Server (NTRS)

    Brinberg, Herbert R.; Pinelli, Thomas E.; Barclay, Rebecca O.

    1995-01-01

    Consideration effort has been devoted over the past 30 years to developing methods and means of assessing the value of information. Two approaches - value in exchange and value in use - dominate; however, neither approach enjoys much practical application because validation schema for decision-making is missing. The approaches fail to measure objectively the real costs of acquiring information and the real benefits that information will yield. Moreover, these approaches collectively fail to provide economic justification to build and/or continue to support an information product or service. In addition, the impact of Cyberspace adds a new dimension to the problem. A new paradigm is required to make economic sense in this revolutionary information environment. In previous work, the authors explored the various approaches to measuring the value of information and concluded that, in large measure, these methods were unworkable concepts and constructs. Instead, they proposed several axioms for valuing information. Most particularly they concluded that the 'value of information cannot be measured in the absence of a specific task, objective, or goal.' This paper builds on those axioms and describes under which circumstances information can be measured in objective and actionable terms. This paper also proposes a methodology for undertaking such measures and validating the results.

  12. Toward an Effective Strategy for the Diffusion and Use of Clinical Information Systems

    PubMed Central

    Davidson, Stephen M.; Heineke, Janelle

    2007-01-01

    The full impact of IT in health care has not been realized because of the failure to recognize that (1) the path from availability of applications to the anticipated benefits passes through a series of steps; and (2) progress can be stopped at any one of those steps. As a result, strategies for diffusion, adoption, and use have been incomplete and have produced disappointing results. In this paper, we present a comprehensive framework for identifying factors that affect the spread, use, and effects of IT in the U.S. health care sector. The framework can be used by researchers to focus their efforts on unanswered questions, by practitioners considering IT adoption, and by policymakers searching for ways to spread IT throughout the system. PMID:17329727

  13. The Internet's impact on policy evaluation: information compression and credibility.

    PubMed

    Bozeman, Barry

    2004-04-01

    As with all media, the Internet structures and frames information, rewarding some information search and decision behaviors while punishing others and, thereby, strongly influences evaluation research results and possibilities. Now that the Internet is for many evaluators the information medium of choice, the impacts of the medium on evaluation deserve careful attention. The objective of this article is to lay groundwork for a theory of the impact of the Internet on evaluation and policy analysis. Questions addressed include the following: (a) What is the impact of the Internet on the evaluator's professional role, work norms, and work habits? (b) Does the use of the Internet affect who is an evaluator or the meaning of professional evaluation? and (c) How does evaluation via Internet affect the technical quality and credibility of evaluation? A key thesis is that the Internet compresses information in the sense that it is not always easy to distinguish among information resources and, especially, the authority of the information provider and the nature of the knowledge warrant. On one hand, the Internet's information compression seems to hold potential for the democratization of evaluation. On the other hand, the diminished ability to make quality distinctions about evaluation-relevant information may undercut the legitimacy of evaluation. PMID:15030618

  14. An appraisal of the impact of compositional and ripening parameters on CO2 diffusivity in semi-hard cheese.

    PubMed

    Acerbi, F; Guillard, V; Guillaume, C; Saubanere, M; Gontard, N

    2016-03-01

    This study focuses on CO2 diffusivity, which is one of the most important factors impacting eye growth in semi-hard cheese, but yet has scarcely been investigated in literature. The effect of compositional and ripening parameters on experimental CO2 diffusivity in semi-hard cheese was studied. CO2 diffusivity in semi-hard cheese showed a complex relationship with temperature in the range 4-25°C, represented by a quadratic curve with the highest diffusivity at 13°C. Salt was found to impact CO2 diffusivity, with a decrease of about 60% for 0-2.7% w/w salt addition, which may be ascribed to viscosity increase of the cheese matrix and "salting in" effect of protein. CO2 diffusivity was found to increase with moisture content from 39% to 42% w/w, then it decreased from 42% to 48% w/w. Inevitable changes in protein content of the three cheese variants may be responsible for the complex behaviour observed. PMID:26471669

  15. Domestication and early agriculture in the Mediterranean Basin: Origins, diffusion, and impact

    PubMed Central

    Zeder, Melinda A.

    2008-01-01

    The past decade has witnessed a quantum leap in our understanding of the origins, diffusion, and impact of early agriculture in the Mediterranean Basin. In large measure these advances are attributable to new methods for documenting domestication in plants and animals. The initial steps toward plant and animal domestication in the Eastern Mediterranean can now be pushed back to the 12th millennium cal B.P. Evidence for herd management and crop cultivation appears at least 1,000 years earlier than the morphological changes traditionally used to document domestication. Different species seem to have been domesticated in different parts of the Fertile Crescent, with genetic analyses detecting multiple domestic lineages for each species. Recent evidence suggests that the expansion of domesticates and agricultural economies across the Mediterranean was accomplished by several waves of seafaring colonists who established coastal farming enclaves around the Mediterranean Basin. This process also involved the adoption of domesticates and domestic technologies by indigenous populations and the local domestication of some endemic species. Human environmental impacts are seen in the complete replacement of endemic island faunas by imported mainland fauna and in today's anthropogenic, but threatened, Mediterranean landscapes where sustainable agricultural practices have helped maintain high biodiversity since the Neolithic. PMID:18697943

  16. Evaluation of mobility impacts of advanced information systems

    SciTech Connect

    Peeta, S.; Poonuru, K.; Sinha, K.

    2000-06-01

    Advanced technologies under the aegis of advanced traveler information systems and advanced traffic management systems are being employed to address the debilitating traffic congestion problem. Broadly identified under the label intelligent transportation systems (ITS), they focus on enhancing the efficiency of the existing roadway utilization. Though ITS has transitioned from the conceptual framework stage to the operational test phase that analyzes real-world feasibility, studies that systematically quantify the multidimensional real-world impacts of these technologies in terms of mobility, safety, and air quality, are lacking. This paper proposes a simulation-based framework to address the mobility impacts of these technologies through the provision of information to travelers. The information provision technologies are labeled as advanced information systems (AIS), and include pretrip information, en route information, variable message signs, and combinations thereof. The primary focus of the paper is to evaluate alternative AIS technologies using the heavily traveled Borman Expressway corridor in northwestern Indiana as a case study. Simulation results provide insights into the mobility impacts of AIS technologies, and contrast the effectiveness of alternative information provision sources and strategies.

  17. U.S. Scientific and Technical Information Policy in the Context of a Diffusion-Oriented National Technology Policy.

    ERIC Educational Resources Information Center

    Branscomb, Lewis M.

    1992-01-01

    Discusses U.S. science and technical information (STI) policy since the 1960s and the recent move toward a diffusion-oriented STI policy. Highlights include reasons why STI is important to national competitiveness, the National Research and Education Network as an information infrastructure, and creation of a committee to coordinate STI policy…

  18. Toward reliable retrieval of functional information of papillary dermis using spatially resolved diffuse reflectance spectroscopy.

    PubMed

    Chen, Yu-Wen; Guo, Jun-Yen; Tzeng, Shih-Yu; Chou, Ting-Chun; Lin, Ming-Jen; Huang, Lynn Ling-Huei; Yang, Chao-Chun; Hsu, Chao-Kai; Tseng, Sheng-Hao

    2016-02-01

    Spatially resolved diffuse reflectance spectroscopy (SRDRS) has been employed to quantify tissue optical properties and its interrogation volume is majorly controlled by the source-to-detector separations (SDSs). To noninvasively quantify properties of dermis, a SRDRS setup that includes SDS shorter than 1 mm is required. It will be demonstrated in this study that Monte Carlo simulations employing the Henyey-Greenstein phase function cannot always precisely predict experimentally measured diffuse reflectance at such short SDSs, and we speculated this could be caused by the non-negligible backward light scattering at short SDSs that cannot be properly modeled by the Henyey-Greenstein phase function. To accurately recover the optical properties and functional information of dermis using SRDRS, we proposed the use of the modified two-layer (MTL) geometry. Monte Carlo simulations and phantom experiment results revealed that the MTL probing geometry was capable of faithfully recovering the optical properties of upper dermis. The capability of the MTL geometry in probing the upper dermis properties was further verified through a swine study, and it was found that the measurement results were reasonably linked to histological findings. Finally, the MTL probe was utilized to study psoriatic lesions. Our results showed that the MTL probe was sensitive to the physiological condition of tissue volumes within the papillary dermis and could be used in studying the physiology of psoriasis. PMID:26977361

  19. Toward reliable retrieval of functional information of papillary dermis using spatially resolved diffuse reflectance spectroscopy

    PubMed Central

    Chen, Yu-Wen; Guo, Jun-Yen; Tzeng, Shih-Yu; Chou, Ting-Chun; Lin, Ming-Jen; Huang, Lynn Ling-Huei; Yang, Chao-Chun; Hsu, Chao-Kai; Tseng, Sheng-Hao

    2016-01-01

    Spatially resolved diffuse reflectance spectroscopy (SRDRS) has been employed to quantify tissue optical properties and its interrogation volume is majorly controlled by the source-to-detector separations (SDSs). To noninvasively quantify properties of dermis, a SRDRS setup that includes SDS shorter than 1 mm is required. It will be demonstrated in this study that Monte Carlo simulations employing the Henyey-Greenstein phase function cannot always precisely predict experimentally measured diffuse reflectance at such short SDSs, and we speculated this could be caused by the non-negligible backward light scattering at short SDSs that cannot be properly modeled by the Henyey-Greenstein phase function. To accurately recover the optical properties and functional information of dermis using SRDRS, we proposed the use of the modified two-layer (MTL) geometry. Monte Carlo simulations and phantom experiment results revealed that the MTL probing geometry was capable of faithfully recovering the optical properties of upper dermis. The capability of the MTL geometry in probing the upper dermis properties was further verified through a swine study, and it was found that the measurement results were reasonably linked to histological findings. Finally, the MTL probe was utilized to study psoriatic lesions. Our results showed that the MTL probe was sensitive to the physiological condition of tissue volumes within the papillary dermis and could be used in studying the physiology of psoriasis. PMID:26977361

  20. Impact of Changes in Diffuse Radiation on the Global Land Carbon Sink, 1901-2100

    NASA Astrophysics Data System (ADS)

    Mercado, L.; Bellouin, N.; Sitch, S.; Boucher, O.; Huntingford, C.; Wild, M.; Cox, P. M.

    2009-04-01

    Recent observational and theoretical studies have shown that changes in surface radiation that lead to increasing diffuse surface irradiance, enhance plant photosynthesis (Gu et al., 2003, Niyogi et al., 2004, Oliveira et al., 2007, Roderick et al., 2001). Solar radiation reaching the land surface has changed over the industrial era due to aerosols emitted from volcanoes and various anthropogenic sources (Kvalevag and Myhre, 2007). Such changes in total surface radiation are accompanied by changes in direct and diffuse surface solar radiation. Current global climate-carbon models do include the effects of changes in total surface radiation on the land biosphere but neglect the positive effects of increasing diffuse fraction on plant photosynthesis. In this study we estimate for the first time, the impact of variations in diffuse fraction on the land carbon sink using a global model (Mercado et al., 2007) modified to account for the effects of variations in both direct and diffuse radiation on canopy photosynthesis. We use meteorological forcing from the Climate Research Unit Data set. Additionally short wave and photosynthetic active radiation are reconstructed from the Hadley centre climate model, which accounts for the scattering and absorption of light by tropospheric and stratospheric aerosols and change in cloud properties due to indirect aerosol effects. References Gu L.H., Baldocchi D.D., Wofsy S.C., Munger J.W., Michalsky J.J., Urbanski S.P. & Boden T.A. (2003) Response of a deciduous forest to the Mount Pinatubo eruption: Enhanced photosynthesis. Science, 299, 2035-2038. M. M. Kvalevag and G. Myhre, J. Clim. 20, 4874 (2007). Mercado L.M., Huntingford C., Gash J.H.C., Cox P.M. & Jogireddy V. (2007) Improving the representation of radiation interception and photosynthesis for climate model applications. Tellus Series B-Chemical and Physical Meteorology, 59, 553-565. Niyogi D., Chang H.I., Saxena V.K., Holt T., Alapaty K., Booker F., Chen F., Davis K

  1. Office Automation and Information Technology Trends--Their Impact on Libraries and Information Center Management.

    ERIC Educational Resources Information Center

    Mason, Robert M.

    1986-01-01

    Reviews recent research on the rate of implementation and impacts of office automation (i.e., expanding microcomputer use, expert systems, electronic publishing) and outlines how these impacts may lead to changes in roles and services of libraries and information professionals. (Author/MBR)

  2. The Impact of Diffuse Ionized Gas on Emission-line Ratios and Gas Metallicity Measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Yan, Renbin; MaNGA Team

    2016-01-01

    Diffuse Ionized Gas (DIG) is prevalent in star-forming galaxies. Using a sample of galaxies observed by MaNGA, we demonstrate how DIG in star-forming galaxies impact the measurements of emission line ratios, hence the gas-phase metallicity measurements and the interpretation of diagnostic diagrams. We demonstrate that emission line surface brightness (SB) is a reasonably good proxy to separate HII regions from regions dominated by diffuse ionized gas. For spatially-adjacent regions or regions at the same radius, many line ratios change systematically with emission line surface brightness, reflecting a gradual increase of dominance by DIG towards low SB. DIG could significantly bias the measurement of gas metallicity and metallicity gradient. Because DIG tend to have a higher temperature than HII regions, at fixed metallicity DIG displays lower [NII]/[OII] ratios. DIG also show lower [OIII]/[OII] ratios than HII regions, due to extended partially-ionized regions that enhance all low-ionization lines ([NII], [SII], [OII], [OI]). The contamination by DIG is responsible for a substantial portion of the scatter in metallicity measurements. At different surface brightness, line ratios and line ratio gradients can differ systematically. As DIG fraction could change with radius, it can affect the metallicity gradient measurements in systematic ways. The three commonly used strong-line metallicity indicators, R23, [NII]/[OII], O3N2, are all affected in different ways. To make robust metallicity gradient measurements, one has to properly isolate HII regions and correct for DIG contamination. In line ratio diagnostic diagrams, contamination by DIG moves HII regions towards composite or LINER-like regions.

  3. Impact of implanted phosphorus on the diffusivity of boron and its applicability to silicon solar cells

    NASA Astrophysics Data System (ADS)

    Schrof, Julian; Müller, Ralph; Reedy, Robert C.; Benick, Jan; Hermle, Martin

    2015-07-01

    Boron diffusivity reduction in extrinsically doped silicon was investigated in the context of a process combination consisting of BBr3 furnace diffusion and preceding Phosphorus ion implantation. The implantation of Phosphorus leads to a substantial blocking of Boron during the subsequent Boron diffusion. First, the influences of ion implantation induced point defects as well as the initial P doping on B diffusivity were studied independently. Here, it was found that not the defects created during ion implantation but the P doping itself results in the observed B diffusion retardation. The influence of the initial P concentration was investigated in more detail by varying the P implantation dose. A secondary ion mass spectrometry (SIMS) analysis of the BSG layer after the B diffusion revealed that the B diffusion retardation is not due to potential P content in the BSG layer but rather caused by the n-type doping of the crystalline silicon itself. Based on the observations the B diffusion retardation was classified into three groups: (i) no reduction of B diffusivity, (ii) reduced B diffusivity, and (iii) blocking of the B diffusion. The retardation of B diffusion can well be explained by the phosphorus doping level resulting in a Fermi level shift and pairing of B and P ions, both reducing the B diffusivity. Besides these main influences, there are probably additional transient phenomena responsible for the blocking of boron. Those might be an interstitial transport mechanism caused by P diffusion that reduces interstitial concentration at the surface or the silicon/BSG interface shift due to oxidation during the BBr3 diffusion process. Lifetime measurements revealed that the residual (non-blocked) B leads to an increased dark saturation current density in the P doped region. Nevertheless, electrical quality is on a high level and was further increased by reducing the B dose as well as by removing the first few nanometers of the silicon surface after the BBr3

  4. Impact of implanted phosphorus on the diffusivity of boron and its applicability to silicon solar cells

    SciTech Connect

    Schrof, Julian Müller, Ralph; Benick, Jan; Hermle, Martin; Reedy, Robert C.

    2015-07-28

    Boron diffusivity reduction in extrinsically doped silicon was investigated in the context of a process combination consisting of BBr{sub 3} furnace diffusion and preceding Phosphorus ion implantation. The implantation of Phosphorus leads to a substantial blocking of Boron during the subsequent Boron diffusion. First, the influences of ion implantation induced point defects as well as the initial P doping on B diffusivity were studied independently. Here, it was found that not the defects created during ion implantation but the P doping itself results in the observed B diffusion retardation. The influence of the initial P concentration was investigated in more detail by varying the P implantation dose. A secondary ion mass spectrometry (SIMS) analysis of the BSG layer after the B diffusion revealed that the B diffusion retardation is not due to potential P content in the BSG layer but rather caused by the n-type doping of the crystalline silicon itself. Based on the observations the B diffusion retardation was classified into three groups: (i) no reduction of B diffusivity, (ii) reduced B diffusivity, and (iii) blocking of the B diffusion. The retardation of B diffusion can well be explained by the phosphorus doping level resulting in a Fermi level shift and pairing of B and P ions, both reducing the B diffusivity. Besides these main influences, there are probably additional transient phenomena responsible for the blocking of boron. Those might be an interstitial transport mechanism caused by P diffusion that reduces interstitial concentration at the surface or the silicon/BSG interface shift due to oxidation during the BBr{sub 3} diffusion process. Lifetime measurements revealed that the residual (non-blocked) B leads to an increased dark saturation current density in the P doped region. Nevertheless, electrical quality is on a high level and was further increased by reducing the B dose as well as by removing the first few nanometers of the silicon surface after

  5. Information-based ranking of 10 compartment models of diffusion-weighted signal attenuation in fixed prostate tissue.

    PubMed

    Liang, Sisi; Panagiotaki, Eleftheria; Bongers, Andre; Shi, Peng; Sved, Paul; Watson, Geoffrey; Bourne, Roger

    2016-05-01

    This study compares the theoretical information content of single- and multi-compartment models of diffusion-weighted signal attenuation in prostate tissue. Diffusion-weighted imaging (DWI) was performed at 9.4 T with multiple diffusion times and an extended range of b values in four whole formalin-fixed prostates. Ten models, including different combinations of isotropic, anisotropic and restricted components, were tested. Models were ranked using the Akaike information criterion. In all four prostates, two-component models, comprising an anisotropic Gaussian component and an isotropic restricted component, ranked highest in the majority of voxels. Single-component models, whether isotropic (apparent diffusion coefficient, ADC) or anisotropic (diffusion tensor imaging, DTI), consistently ranked lower than multi-component models. Model ranking trends were independent of voxel size and maximum b value in the range tested (1.6-16 mm(3) and 3000-10 000 s/mm(2) ). This study characterizes the two major water components previously identified by biexponential models and shows that models incorporating both anisotropic and restricted components provide more information-rich descriptions of DWI signals in prostate tissue than single- or multi-component anisotropic models and models that do not account for restricted diffusion. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26999065

  6. Impact of Training Bolivian Farmers on Integrated Pest Management and Diffusion of Knowledge to Neighboring Farmers.

    PubMed

    Jørs, Erik; Konradsen, Flemming; Huici, Omar; Morant, Rafael C; Volk, Julie; Lander, Flemming

    2016-01-01

    Teaching farmers integrated pest management (IPM) in farmer field schools (FFS) has led to reduced pesticide use and safer handling. This article evaluates the long-term impact of training farmers on IPM and the diffusion of knowledge from trained farmers to neighboring farmers, a subject of importance to justify training costs and to promote a healthy and sustainable agriculture. Training on IPM of farmers took place from 2002 to 2004 in their villages in La Paz County, Bolivia, whereas dissemination of knowledge from trained farmer to neighboring farmer took place until 2009. To evaluate the impact of the intervention, self-reported knowledge and practice on pesticide handling and IPM among trained farmers (n = 23) and their neighboring farmers (n = 47) were analyzed in a follow-up study and compared in a cross-sectional analysis with a control group of farmers (n = 138) introduced in 2009. Variables were analyzed using χ(2) test and analysis of variance (ANOVA). Trained farmers improved and performed significantly better in all tested variables than their neighboring farmers, although the latter also improved their performance from 2002 to 2009. Including a control group showed an increasing trend in all variables, with the control farmers having the poorest performance and trained farmers the best. The same was seen in an aggregated variable where trained farmers had a mean score of 16.55 (95% confidence interval [CI]: 15.45-17.65), neighboring farmers a mean score of 11.97 (95% CI: 10.56-13.38), and control farmers a mean score of 9.18 (95% CI: 8.55-9.80). Controlling for age and living altitude did not change these results. Trained farmers and their neighboring farmers improved and maintained knowledge and practice on IPM and pesticide handling. Diffusion of knowledge from trained farmers might explain the better performance of the neighboring farmers compared with the control farmers. Dissemination of knowledge can contribute to justify the cost and

  7. NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 5: Aerospace librarians and technical information specialists as information intermediaries: A report of phase 2 activities of the NASA/DOD Aerospace Knowledge Diffusion Research Project

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Kennedy, John M.

    1990-01-01

    The objective of the NASA/DOD Aerospace Knowledge Diffusion Research Project is to provide descriptive and analytical data regarding the flow of scientific and technical information (STI) at the individual, organizational, national, and international levels, placing emphasis on the systems used to diffuse the results of federally funded aerospace STI. An overview of project assumptions, objectives, and design is presented and preliminary results of the phase 2 aerospace library survey are summarized. Phase 2 addressed aerospace knowledge transfer and use within the larger social system and focused on the flow of aerospace STI in government and industry and the role of the information intermediary in knowledge transfer.

  8. 41 CFR 60-3.4 - Information on impact.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 41 Public Contracts and Property Management 1 2012-07-01 2009-07-01 true Information on impact. 60-3.4 Section 60-3.4 Public Contracts and Property Management Other Provisions Relating to Public... employment practices, (2) where the weight of court decisions or administrative interpretations hold that...

  9. 41 CFR 60-3.4 - Information on impact.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 41 Public Contracts and Property Management 1 2014-07-01 2014-07-01 false Information on impact. 60-3.4 Section 60-3.4 Public Contracts and Property Management Other Provisions Relating to Public... employment practices, (2) where the weight of court decisions or administrative interpretations hold that...

  10. Impact of adding foreign genomic information on Mexican Holstein imputation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The impact of adding US and Canada genomic information to the imputation of Mexican Holstein genotypes was measured by comparing 3 scenarios: 1) 2,018 Mexican genotyped animals; 2) animals from scenario 1 plus 886 related North American animals; and 3) animals from scenario 1 and all North American ...

  11. Aging and the Impact of Irrelevant Information on Social Judgments

    PubMed Central

    Hess, Thomas M.; Smith, Brian T.

    2014-01-01

    We conducted two experiments to specifically examine whether older adults are more susceptible to the negative impact of irrelevant evaluative information when making social judgments. Young (ages 20 – 44), middle-aged (ages 45 – 63), and older (ages 65 – 85) adults were presented with descriptions of people consisting of positive and negative traits that varied in relevance to specific occupations. They were asked to either form a general impression based on these traits or to evaluate the person’s fitness for the specified occupation. In both studies, evaluative content of the descriptions (i.e., the number of positive minus number of negative traits) was a significant predictor of subjective evaluations. Of prime importance, adults of all ages were similarly able to selectively process relevant versus irrelevant information when occupational fitness evaluations required them to focus on a subset of information in the descriptions. Participants also adjusted the specific types of information used in making judgments, with the relative importance of agentic traits and negative information being greater when making occupation evaluations than when forming impressions. The results suggest that age differences in the processing evaluative information are minimal, and that the availability of well-established knowledge structures can help older adults effectively control the impact of irrelevant evaluative information when making social inferences. PMID:25244474

  12. Aging and the impact of irrelevant information on social judgments.

    PubMed

    Hess, Thomas M; Smith, Brian T

    2014-09-01

    We conducted 2 experiments to specifically examine whether older adults are more susceptible to the negative impact of irrelevant evaluative information when making social judgments. Young (ages 20-44), middle-aged (ages 45-63), and older (ages 65-85) adults were presented with descriptions of people consisting of positive and negative traits that varied in relevance to specific occupations. They were asked to either form a general impression based on these traits or to evaluate the person's fitness for the specified occupation. In both studies, evaluative content of the descriptions (i.e., the number of positive minus number of negative traits) was a significant predictor of subjective evaluations. Of prime importance, adults of all ages were similarly able to selectively process relevant versus irrelevant information when occupational fitness evaluations required them to focus on a subset of information in the descriptions. Participants also adjusted the specific types of information used in making judgments, with the relative importance of agentic traits and negative information being greater when making occupation evaluations than when forming impressions. The results suggest that age differences in the processing evaluative information are minimal, and that the availability of well-established knowledge structures can help older adults effectively control the impact of irrelevant evaluative information when making social inferences. PMID:25244474

  13. Impact of compression on gas transport in non-woven gas diffusion layers of high temperature polymer electrolyte fuel cells

    NASA Astrophysics Data System (ADS)

    Froning, Dieter; Yu, Junliang; Gaiselmann, Gerd; Reimer, Uwe; Manke, Ingo; Schmidt, Volker; Lehnert, Werner

    2016-06-01

    Gas transport in non-woven gas diffusion layers of a high-temperature polymer electrolyte fuel cell was calculated with the Lattice Boltzmann method. The underlying micro structure was taken from two sources. A real micro structure was analyzed in the synchrotron under the impact of a compression mask mimicking the channel/rib structure of a flow field. Furthermore a stochastic geometry model based on synchrotron X-ray tomography studies was applied. The effect of compression is included in the stochastic model. Gas transport in these micro structures was simulated and the impact of compression was analyzed. Fiber bundles overlaying the micro structure were identified which affect the homogeneity of the gas flow. There are significant deviations between the impact of compression on effective material properties for this type of gas diffusion layers and the Kozeny-Carman equation.

  14. Modeling cross L shell impacts of magnetopause shadowing and ULF wave radial diffusion in the Van Allen belts

    NASA Astrophysics Data System (ADS)

    Ozeke, Louis G.; Mann, Ian R.; Turner, Drew L.; Murphy, Kyle R.; Degeling, Alex W.; Rae, I. Jonathan; Milling, David K.

    2014-10-01

    We present simulations of the outer electron radiation belt using a new ULF wave-driven radial diffusion model, including empirical representations of loss due to chorus and plasmaspheric hiss. With an outer boundary condition constrained by in situ electron flux observations, we focus on the impacts of magnetopause shadowing and outward radial diffusion in the heart of the radiation belt. Third invariant conserving solutions are combined to simulate the L shell and time dependence of the differential flux at a fixed energy. Results for the geomagnetically quiet year of 2008 demonstrate not only remarkable cross L shell impacts from magnetopause shadowing but also excellent agreement with the in situ observations even though no internal acceleration source is included in the model. Our model demonstrates powerful utility for capturing the cross-L impacts of magnetopause shadowing with significant prospects for improved space weather forecasting. The potential role of the plasmasphere in creating a third belt is also discussed.

  15. The Performance of Direct Disk Diffusion for Community Acquired Bacteremia due to Gram-Negative Bacilli and Its Impact on Physician Treatment Decisions.

    PubMed

    Daley, Peter; Comerford, Adam; Umali, Jurgienne; Penney, Carla

    2016-01-01

    Background. Direct disk diffusion susceptibility testing provides faster results than standard microtitre susceptibility. The direct result may impact patient outcome in sepsis if it is accurate and if physicians use the information to promptly and appropriately change antibiotic treatment. Objective. To compare the performance of direct disk diffusion with standard susceptibility and to consider physician decisions in response to these early results, for community acquired bacteremia with Gram-negative Bacilli. Methods. Retrospective observational study of all positive blood cultures with Gram-negative Bacilli, collected over one year. Physician antibiotic treatment decisions were assessed by an infectious diseases physician based on information available to the physician at the time of the decision. Results. 89 bottles growing Gram-negative Bacilli were included in the analysis. Direct disk diffusion agreement with standard susceptibility varied widely. In 47 cases (52.8%), the physician should have changed to a narrower spectrum but did not, in 18 cases (20.2%), the physician correctly narrowed from appropriate broad coverage, and in 8 cases (9.0%), the empiric therapy was correct. Discussion. Because inoculum is not standardized, direct susceptibility results do not agree with standard susceptibility results for all drugs. Physicians do not act on direct susceptibility results. Conclusion. Direct susceptibility should be discontinued in clinical microbiology laboratories. PMID:27366172

  16. Prognostic impact of concurrent MYC and BCL6 rearrangements and expression in de novo diffuse large B-cell lymphoma

    PubMed Central

    Deng, Lijuan; Wang, Xiaoxiao; Manyam, Ganiraju C.; Visco, Carlo; Montes-Moreno, Santiago; Zhang, Li; Dybkær, Karen; Chiu, April; Orazi, Attilio; Zu, Youli; Bhagat, Govind; Richards, Kristy L.; Hsi, Eric D.; Choi, William W.L.; van Krieken, J. Han; Huh, Jooryung; Ponzoni, Maurilio; Ferreri, Andrés J.M.; Parsons, Ben M.; Møller, Michael B.; Piris, Miguel A.; Winter, Jane N.; Medeiros, L. Jeffrey; Hu, Shimin; Young, Ken H.

    2016-01-01

    Double-hit B-cell lymphoma is a common designation for a group of tumors characterized by concurrent translocations of MYC and BCL2, BCL6, or other genes. The prognosis of concurrent MYC and BCL6 translocations is not well known. In this study, we assessed rearrangements and expression of MYC, BCL2 and BCL6 in 898 patients with de novo diffuse large B-cell lymphoma treated with standard chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisone plus rituximab). Neither BCL6 translocation alone (more frequent in activated B-cell like diffuse large B-cell lymphoma) nor in combination with MYC translocation (observed in 2.0% of diffuse large B-cell lymphoma) predicted poorer survival in diffuse large B-cell lymphoma patients. Diffuse large B-cell lymphoma patients with MYC/BCL6 co-expression did have significantly poorer survival, however, MYC/BCL6 co-expression had no effect on prognosis in the absence of MYC/BCL2 co-expression, and had no additive impact in MYC+/BCL2+ cases. The isolated MYC+/BCL6+/BCL2− subset, more frequent in germinal center B-cell like diffuse large B-cell lymphoma, had significantly better survival compared with the isolated MYC+/BCL2+/BCL6− subset (more frequent in activated B-cell like diffuse large B-cell lymphoma). In summary, diffuse large B-cell lymphoma patients with either MYC/BCL6 rearrangements or MYC/BCL6 co-expression did not always have poorer prognosis; MYC expression levels should be evaluated simultaneously; and double-hit B-cell lymphoma needs to be refined based on the specific genetic abnormalities present in these tumors. PMID:26573234

  17. Surface diffusion of molecular glasses: Material dependence and impact on physical stability

    NASA Astrophysics Data System (ADS)

    Ruan, Shigang; Zhang, Wei; Yu, Lian

    Surface diffusion coefficients have been measured for molecular glasses tris-naphthylbenzene (TNB) and PMMA oligomers by surface grating decay. Surface diffusion on TNB is vastly faster than bulk diffusion, by a factor of 107 at Tg, while the process is very slow on PMMA. Along with the previous results on o - terphenyl, nifedipine, indomethacin, and polystyrene oligomers, we find that surface diffusion slows down with increasing molecular size and intermolecular forces, whereas bulk diffusion has a weaker material dependence. The molecular glasses studied show fast crystal growth on the free surface. A general correlation is observed between the coefficient of surface diffusion and the velocity of surface crystal growth, indicating surface crystallization is supported by surface mobility. (Zhu, L., et al. Phys. Rev. Lett. 106 (2011): 256103; Zhang, W., et al. J. Phys. Chem. B 119 (2015): 5071-5078) Nsf.

  18. Impact of information technology on human resources in healthcare.

    PubMed

    Anvari, Mehran

    2007-01-01

    Incorporation of advances in information communications technology (ICT) into the workplace has had a major impact in human resource utilization in sectors of the economy where it has occurred in a substantial manner, such as manufacturing and financial services. While some benefits of ICT have been realized in healthcare, the full impact of its benefits will only be realized if it is incorporated in a systematic form, rather than in the current patchy and uneven manner seen around the province and across the country to date. PMID:18027453

  19. 78 FR 57135 - Agency Information Collection Activities; Comment Request; Impact Aid Program Application for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-17

    ... Agency Information Collection Activities; Comment Request; Impact Aid Program Application for Section... the Department assess the impact of its information collection requirements and minimize the public's... respondents, including through the use of information technology. Please note that written comments...

  20. The Impact of Information on Doctors' Attitudes Toward Generic Drugs.

    PubMed

    Tsaprantzi, Aggeliki V; Kostagiolas, Petros; Platis, Charalampos; Aggelidis, Vassilios P; Niakas, Dimitris

    2016-01-01

    The objective of this study is to assess the impact of information on doctors' attitudes and perceptions toward generics. A cross-sectional survey based on a specially designed 21-item questionnaire was conducted. The survey involved doctors of different specialties working in a public hospital in Greece. The analysis includes descriptive and inferential statistics, reliability and validity tests, as well as structural equation modeling to evaluate the causal model. Statistical analysis was accomplished by using SPSS 20 and Amos 20. A total of 134 questionnaires out of 162 were received, providing a response rate of 82.71%. A number of significant associations were found between information and perceptions about generic medicines with demographic characteristics. It seems that the provision of quality information on generic drugs influences doctors' attitudes and prescription practices toward generic drugs. This is not a static process but a rather dynamic issue involving information provision policies for strengthening the proper doctors' attitudes toward generic drugs. PMID:27033564

  1. Beyond Economy: Impact of National Cultural Values on Nationwide Broadband Internet Diffusion

    ERIC Educational Resources Information Center

    Joo, Sung-Hee

    2010-01-01

    This study examines how the non-conventional factors of national cultural values and government involvement affect the diffusion of broadband Internet technologies in various nations around the world. An innovative element of the study was the examination of the influence patterns at different stages of diffusion, which was measured by the number…

  2. Effect of dissolved oxygen manipulation on diffusive emissions from NAPL-impacted low permeability soil layers.

    PubMed

    Clifton, Lisa M; Dahlen, Paul R; Johnson, Paul C

    2014-05-01

    Aquifer physical model experiments were performed to investigate if diffusive emissions from nonaqueous phase liquid (NAPL)-impacted low-permeability layers into groundwater moving through adjacent NAPL-free high-permeability layers can be reduced by creating an aerobic biotreatment zone at the interface between the two, and if over time that leads to reduced emissions after treatment ceases. Experiments were performed in two 1.2-m long × 1.2-m high × 5.4 cm wide stainless steel tanks; each with a high-permeability sand layer overlying a low-permeability crushed granite layer containing a NAPL mixture of indane and benzene. Each tank was water-saturated with horizontal flow primarily through the sand layer. The influent water was initially deoxygenated and the emissions and concentration distributions were allowed to reach near-steady conditions. The influent dissolved oxygen (DO) level was increased stepwise to 6.5-8.5 mg/L and 17-20 mg/L, and then decreased back to deoxygenated conditions. Each condition was maintained for at least 45 days. Relative to the near-steady benzene emission at the initial deoxygenated condition, the emission was reduced by about 70% when the DO was 6.5-8.5 mg/L, 90% when the DO was 17-20 mg/L, and ultimately 60% when returning to low DO conditions. While the reductions were substantial during treatment, longer-term reductions after 120 d of elevated DO treatment, relative to an untreated condition predicted by theory, were low: 29% and 6% in Tank 1 and Tank 2, respectively. Results show a 1-2 month lag between the end of DO delivery and rebound to the final near-steady emissions level. This observation has implications for post-treatment performance monitoring sampling at field sites. PMID:24716993

  3. Evaluation of the impact of atmospheric ozone and aerosols on the horizontal global/diffuse UV Index at Livorno (Italy)

    NASA Astrophysics Data System (ADS)

    Scaglione, Daniele; Giulietti, Danilo; Morelli, Marco

    2016-08-01

    A study was conducted at Livorno (Italy) to evaluate the impact of atmospheric aerosols and ozone on the solar UV radiation and its diffuse component at ground in clear sky conditions. Solar UV radiation has been quantified in terms of UV Index (UVI), following the ISO 17166:1999/CIE S007/E-1998 international standard. UVI has been calculated by exploiting the libRadtran radiative transfer modelling software as a function of both the Aerosols Optical Depth (AOD) and the Total Ozone Column (TOC). In particular AOD and TOC values have been remotely sensed by the Ozone Monitoring Instrument (OMI) on board the NASA's EOS (Earth Observing System) satellites constellation. An experimental confirmation was also obtained by exploiting global UVI ground-based measurements from the 26/9/14 to 12/8/15 and diffuse UVI ground-based measurements from the 17/5/15 to 12/8/15. For every considered value of Solar Zenith Angle (SZA) and atmospheric condition, estimates and measurements confirm that the diffuse component contributes for more than 50% on the global UV radiation. Therefore an exposure of human skin also to diffuse solar UV radiation can be potentially harmful for health and need to be accurately monitored, e.g. by exploiting innovative applications such as a mobile app with a satellite-based UV dosimeter that has been developed. Global and diffuse UVI variations due to the atmosphere are primarily caused by the TOC variations (typically cyclic): the maximum TOC variation detected by OMI in the area under study leads to a corresponding variation in global and diffuse UVI of about 50%. Aerosols in the area concerned, mainly of maritime nature, have instead weaker effects causing a maximum variation of the global and diffuse UVI respectively of 9% and 35% with an SZA of 20° and respectively of 13% and 10% with an SZA of 60°.

  4. Determination of partition and diffusion coefficients of formaldehyde in selected building materials and impact of relative humidity.

    PubMed

    Xu, Jing; Zhang, Jianshun S; Liu, Xiaoyu; Gao, Zhi

    2012-06-01

    The partition and effective diffusion coefficients of formaldehyde were measured for three materials (conventional gypsum wallboard, "green" gypsum wallboard, and "green" carpet) under three relative humidity (RH) conditions (20%, 50%, and 70% RH). The "green" materials contained recycled materials and were friendly to environment. A dynamic dual-chamber test method was used. Results showed that a higher relative humidity led to a larger effective diffusion coefficient for two kinds of wallboards and carpet. The carpet was also found to be very permeable resulting in an effective diffusion coefficient at the same order of magnitude with the formaldehyde diffusion coefficient in air. The partition coefficient (K(ma)) of formaldehyde in conventional wallboard was 1.52 times larger at 50% RH than at 20% RH, whereas it decreased slightly from 50% to 70% RH, presumably due to the combined effects of water solubility of formaldehyde and micro-pore blocking by condensed moisture at the high RH level. The partition coefficient of formaldehyde increased slightly with the increase of relative humidity in "green" wallboard and "green" carpet. At the same relative humidity level, the "green" wallboard had larger partition coefficient and effective diffusion coefficient than the conventional wallboard, presumably due to the micro-pore structure differences between the two materials. The data generated could be used to assess the sorption effects of formaldehyde on building materials and to evaluate its impact on the formaldehyde concentration in buildings. PMID:22788105

  5. Impact of Molecular Organization on Exciton Diffusion in Photosensitive Single-Crystal Halogenated Perylenediimides Charge Transfer Interfaces.

    PubMed

    Pinto, Rui M; Gouveia, Wilson; Maçôas, Ermelinda M S; Santos, Isabel C; Raja, Sebastian; Baleizão, Carlos; Alves, Helena

    2015-12-23

    The efficiency of organic photodetectors and optoelectronic devices is strongly limited by exciton diffusion, in particular for acceptor materials. Although mechanisms for exciton diffusion are well established, their correlation to molecular organization in real systems has received far less attention. In this report, organic single-crystals interfaces were probed with wavelength-dependent photocurrent spectroscopy and their crystal structure resolved using X-ray diffraction. All systems present a dynamic photoresponse, faster than 500 ms, up to 650 nm. A relationship between molecular organization and favorable exciton diffusion in substituted butyl-perylenediimides (PDIB) is established. This is demonstrated by a set of PDIBs with different intra- and interstack distances and short contacts and their impact on photoresponse. Given the short packing distances between PDIs cores along the same stacking direction (3.4-3.7 Å), and across parallel stacks (2.5 Å), singlet exciton in these PDIBs can follow both Förster and Dexter exciton diffusion, with the Dexter-type mechanism assuming special relevance for interstack exciton diffusion. Yet, the response is maximized in substituted PDIBs, where a 2D percolation network is formed through strong interstack contacts, allowing for PDIBs primary excitons to reach with great efficiency the splitting interface with crystalline rubrene. The importance of short contacts and molecular distances, which is often overlooked as a parameter to consider and optimize when choosing materials for excitonic devices, is emphasized. PMID:26599347

  6. Identifying the main paths of information diffusion in online social networks

    NASA Astrophysics Data System (ADS)

    Zhu, Hengmin; Yin, Xicheng; Ma, Jing; Hu, Wei

    2016-06-01

    Recently, an increasing number of researches on relationship strength show that there are some socially active links in online social networks. Furthermore, it is likely that there exist main paths which play the most significant role in the process of information diffusion. Although much of previous work has focused on the pathway of a specific event, there are hardly any scholars that have extracted the main paths. To identify the main paths of online social networks, we proposed a method which measures the weights of links based on historical interaction records. The influence of node based on forwarding amount is quantified and top-ranked nodes are selected as the influential users. The path importance is evaluated by calculating the probability that a message would spread via this path. We applied our method to a real-world network and found interesting insights. Each influential user can access another one via a short main path and the distribution of main paths shows significant community effect.

  7. Anatomically Informed Metrics for Connectivity-based Cortical Parcellation from Diffusion MRI

    PubMed Central

    Tungaraza, Rosalia L.; Mehta, Sonya H.; Haynor, David R.; Grabowski, Thomas J.

    2015-01-01

    Connectivity information derived from diffusion MRI can be used to parcellate the cerebral cortex into anatomically and functionally meaningful subdivisions. Acquisition and processing parameters can significantly affect parcellation results, and there is no consensus on best practice protocols. We propose a novel approach for evaluating parcellation based on measuring the degree to which parcellation conforms to known principles of brain organization, specifically cortical field homogeneity and inter-hemispheric homology. The proposed metrics are well behaved on morphologically-generated whole-brain parcels, where they correctly identify contralateral homologies, and give higher scores to anatomically versus arbitrarily generated parcellations. The measures show that individual cortical fields have characteristic connectivity profiles that are compact and separable, and that the topological arrangement of such fields is strongly conserved between hemispheres and individuals. The proposed metrics can be used to evaluate the quality of parcellations at the subject and group levels, and to improve acquisition and data processing for connectivity-based cortical parcellation. PMID:26080389

  8. The diffusion of autism spectrum disorder in Costa Rica: Evidence of information spread or environmental effects?

    PubMed

    Schelly, David; Jiménez González, Patricia; Solís, Pedro J

    2015-09-01

    In the U.S., children with autism spectrum disorder (ASD) have been found to live in spatial clusters. Studies have suggested that the clustering is caused by social or environmental factors, but determining the cause of the clustering is difficult in the U.S. setting because of unmeasured variation in healthcare access and diagnostic practices. The present study explores the diffusion of ASD in a small setting in which the diagnosis is not widely publicised and there is no variation in healthcare access or diagnostic practices. Costa Rica provides universal healthcare and only has one diagnosing clinic for young children, and the diagnosis is relatively new and little known among clinicians and parents. In addition, the potential for mercury exposure from the source that has been associated with ASD is absent, and areas with high levels of air pollution are spatially concentrated. Focusing on all young children who underwent an ASD assessment from 2010 to 2013, we identify spatial clusters that suggest a mechanism that does not depend on information about ASD, healthcare access, diagnostic practices, or environmental toxicants. These findings provide details of the "contextual drivers" of the increasing worldwide prevalence of ASD. PMID:26318531

  9. Impact of water boundary layer diffusion on the nitrification rate of submerged biofilter elements from a recirculating aquaculture system.

    PubMed

    Prehn, Jonas; Waul, Christopher K; Pedersen, Lars-Flemming; Arvin, Erik

    2012-07-01

    Total ammonia nitrogen (TAN) removal by microbial nitrification is an essential process in recirculating aquaculture systems (RAS). In order to protect the aquatic environment and fish health, it is important to be able to predict the nitrification rates in RAS's. The aim of this study was to determine the impact of hydraulic film diffusion on the nitrification rate in a submerged biofilter. Using an experimental batch reactor setup with recirculation, active nitrifying biofilter units from a RAS were exposed to a range of hydraulic flow velocities. Corresponding nitrification rates were measured following ammonium chloride, NH₄Cl, spikes and the impact of hydraulic film diffusion was quantified. The nitrification performance of the tested biofilter could be significantly increased by increasing the hydraulic flow velocity in the filter. Area based first order nitrification rate constants ranged from 0.065 m d⁻¹ to 0.192 m d⁻¹ for flow velocities between 2.5 m h⁻¹ and 40 m h⁻¹ (18 °C). This study documents that hydraulic film diffusion may have a significant impact on the nitrification rate in fixed film biofilters with geometry and hydraulic flows corresponding to our experimental RAS biofilters. The results may thus have practical implications in relation to the design, operational strategy of RAS biofilters and how to optimize TAN removal in fixed film biofilter systems. PMID:22507250

  10. Self-diffusion of vibrational states: Impact on the heat transfer in hypersonic flows

    NASA Astrophysics Data System (ADS)

    Josyula, E.; Kustova, E. V.; Vedula, P.

    2014-12-01

    In the present paper, the influence of self-diffusion of vibrationally excited states on the fluid dynamics and surface heat transfer in an axisymmetric Mach 7.2 air flow past a sphere-cone is discussed. Two models for state-to-state transport properties are considered: a simplified model using the Eucken's relation for thermal conductivity and Fick's law for diffusion velocities with the constant Lewis number, and a rigorous kinetic theory based model for the calculation of state-specific thermal conductivity, diffusion and thermal diffusion coefficients. The simplified model is applied for the flowfield simulation to avoid high computational costs. For the application of the accurate kinetic theory approach, a post-processing procedure is used. Inclusion of self-diffusion results in an increase in the surface heat flux of up to 6.5% upstream of a shoulder region. Thermal conductivity is found to be the primary contributor to surface heat flux; the influence of mass and thermal diffusion is found to be negligible. Self-diffusion has a considerably greater influence in decreasing heat flux in the downstream regions far from stagnation point.

  11. Impacts of small-scale variability on the determination of bulk thermal diffusivity in snowpacks

    NASA Astrophysics Data System (ADS)

    Oldroyd, H. J.; Higgins, C. W.; Huwald, H.; Selker, J. S.; Parlange, M. B.

    2012-04-01

    Thermal diffusivity of snow is an important physical property associated with key hydrological phenomena such as snowmelt and heat and water vapor exchange with the atmosphere. These phenomena have broad implications in studies of climate and heat and water budgets on many scales. Furthermore, sub grid scale phenomena may enhance these heat and mass exchanges in the snow pack due to its porous nature. We hypothesize that the heat transfer effects of these small-scale variabilities may be seen as an increased bulk thermal diffusivity of the snow. Direct measurements of snow thermal diffusivity require coupled measurements of thermal conductivity and density, which are nonstationary due to snow metamorphism. Furthermore, thermal conductivity measurements are typically obtained with specialized heating probes or plates and snow density measurements require digging snow pits. Therefore, direct measurements are difficult to obtain with high enough temporal resolution such that direct comparisons with atmospheric conditions can be made. This study uses highly resolved temperature measurements from the Plaine Morte glacier in Switzerland as initial and boundary conditions to numerically solve the 1D heat equation and iteratively optimize for thermal diffusivity. The method uses flux boundary conditions to constrain thermal diffusivity such that spuriously high values in thermal diffusivity are eliminated. Additionally, a t-test ensuring statistical significance between solutions of varied thermal diffusivity results in further constraints on thermal diffusivity that eliminate spuriously low values. The results show that time resolved thermal diffusivity can be determined from easily implemented and inexpensive temperature measurements of seasonal snow with good agreement to widely used parameterizations based on snow density. This high time resolution further affords the ability to explore possible turbulence-induced enhancements to heat and mass transfer in the snow.

  12. MYC protein expression and genetic alterations have prognostic impact in patients with diffuse large B-cell lymphoma treated with immunochemotherapy

    PubMed Central

    Valera, Alexandra; López-Guillermo, Armando; Cardesa-Salzmann, Teresa; Climent, Fina; González-Barca, Eva; Mercadal, Santiago; Espinosa, Íñigo; Novelli, Silvana; Briones, Javier; Mate, José L.; Salamero, Olga; Sancho, Juan M.; Arenillas, Leonor; Serrano, Sergi; Erill, Nadina; Martínez, Daniel; Castillo, Paola; Rovira, Jordina; Martínez, Antonio; Campo, Elias; Colomo, Luis

    2013-01-01

    MYC alterations influence the survival of patients with diffuse large B-cell lymphoma. Most studies have focused on MYC translocations but there is little information regarding the impact of numerical alterations and protein expression. We analyzed the genetic alterations and protein expression of MYC, BCL2, BCL6, and MALT1 in 219 cases of diffuse large B-cell lymphoma. MYC rearrangement occurred as the sole abnormality (MYC single-hit) in 3% of cases, MYC and concurrent BCL2 and/or BCL6 rearrangements (MYC double/triple-hit) in 4%, MYC amplifications in 2% and MYC gains in 19%. MYC single-hit, MYC double/triple-hit and MYC amplifications, but not MYC gains or other gene rearrangements, were associated with unfavorable progression-free survival and overall survival. MYC protein expression, evaluated using computerized image analysis, captured the unfavorable prognosis of MYC translocations/amplifications and identified an additional subset of patients without gene alterations but with similar poor prognosis. Patients with tumors expressing both MYC/BCL2 had the worst prognosis, whereas those with double-negative tumors had the best outcome. High MYC expression was associated with shorter overall survival irrespectively of the International Prognostic Index and BCL2 expression. In conclusion, MYC protein expression identifies a subset of diffuse large B-cell lymphoma with very poor prognosis independently of gene alterations and other prognostic parameters. PMID:23716551

  13. Environmental impacts of modern agricultural technology diffusion in Bangladesh: an analysis of farmers' perceptions and their determinants.

    PubMed

    Rahman, Sanzidur

    2003-06-01

    Farmers' perception of the environmental impacts of modern agricultural technology diffusion and factors determining such awareness were examined using survey data from 21 villages in three agro-ecological regions of Bangladesh. Results reveal that farmers are well aware of the adverse environmental impacts of modern agricultural technology, although their awareness remains confined within visible impacts such as soil fertility, fish catches, and health effects. Their perception of intangible impacts such as, toxicity in water and soils is weak. Level and duration of modern agricultural technology adoption directly influence awareness of its adverse effects. Education and extension contacts also play an important role in raising awareness. Awareness is higher among farmers in developed regions, fertile locations and those with access to off-farm income sources. Promotion of education and strengthening extension services will boost farmers' environmental awareness. Infrastructure development and measures to replenish depleting soil fertility will also play a positive role in raising awareness. PMID:12781758

  14. The impact of post-processing on spinal cord diffusion tensor imaging

    PubMed Central

    Mohammadi, Siawoosh; Freund, Patrick; Feiweier, Thorsten; Curt, Armin; Weiskopf, Nikolaus

    2013-01-01

    Diffusion tensor imaging (DTI) provides information about the microstructure in the brain and spinal cord. While new neuroimaging techniques have significantly advanced the accuracy and sensitivity of DTI of the brain, the quality of spinal cord DTI data has improved less. This is in part due to the small size of the spinal cord (ca. 1 cm diameter) and more severe instrumental (e.g. eddy current) and physiological (e.g. cardiac pulsation) artefacts present in spinal cord DTI. So far, the improvements in image quality and resolution have resulted from cardiac gating and new acquisition approaches (e.g. reduced field-of-view techniques). The use of retrospective correction methods is not well established for spinal cord DTI. The aim of this paper is to develop an improved post-processing pipeline tailored for DTI data of the spinal cord with increased quality. For this purpose, we compared two eddy current and motion correction approaches using three-dimensional affine (3D-affine) and slice-wise registrations. We also introduced a new robust-tensor-fitting method that controls for whole-volume outliers. Although in general 3D-affine registration improves data quality, occasionally it can lead to misregistrations and biassed tensor estimates. The proposed robust tensor fitting reduced misregistration-related bias and yielded more reliable tensor estimates. Overall, the combination of slice-wise motion correction, eddy current correction, and robust tensor fitting yielded the best results. It increased the contrast-to-noise ratio (CNR) in FA maps by about 30% and reduced intra-subject variation in fractional anisotropy (FA) maps by 18%. The higher quality of FA maps allows for a better distinction between grey and white matter without increasing scan time and is compatible with any multi-directional DTI acquisition scheme. PMID:23298752

  15. A new information diffusion modelling technique based on vibrating string equation and its application in natural disaster risk assessment

    NASA Astrophysics Data System (ADS)

    Bai, Cheng-Zu; Zhang, Ren; Hong, Mei; Qian, Long-xia; Wang, Zhengxin

    2015-07-01

    In this paper, to naturally fill the gap in incomplete data, a new algorithm is proposed for estimating the risk of natural disasters based on the information diffusion theory and the equation of the vibrating string. Two experiments are performed with small samples to investigate its effectiveness. Furthermore, to demonstrate the practicality of the new algorithm, it is applied to study the relationship between epicentral intensity and earthquake magnitude, with strong-motion earthquake observations measured in Yunnan Province in China. The regression model, the back-propagation neural network and the conventional information diffusion model are also involved for comparison. All results show that the new algorithm, which can unravel fuzzy information in incomplete data, is better than the main existing methods for risk estimation.

  16. Impact of Thailand universal coverage scheme on the country's health information systems and health information technology.

    PubMed

    Kijsanayotin, Boonchai

    2013-01-01

    Thailand achieved universal healthcare coverage with the implementation of the Universal Coverage Scheme (UCS) in 2001. This study employed qualitative method to explore the impact of the UCS on the country's health information systems (HIS) and health information technology (HIT) development. The results show that health insurance beneficiary registration system helps improve providers' service workflow and country vital statistics. Implementation of casemix financing tool, Thai Diagnosis-Related Groups, has stimulated health providers' HIS and HIT capacity building, data and medical record quality and the adoption of national administrative data standards. The system called "Disease Management Information Systems" aiming at reimbursement for select diseases increased the fragmentation of HIS and increase burden on data management to providers. The financial incentive of outpatient data quality improvement project enhance providers' HIS and HIT investment and also induce data fraudulence tendency. Implementation of UCS has largely brought favorable impact on the country HIS and HIT development. However, the unfavorable effects are also evident. PMID:23920763

  17. Internet chemotherapy information: impact on patients and health professionals

    PubMed Central

    Davies, E; Yeoh, K-W

    2012-01-01

    Background: Reliable information can improve patients' knowledge of chemotherapy. As internet chemotherapy information (ICI) is increasingly viewed as a valuable patient education tool, we investigated the impact of ICI on patient care and analysed health professionals' (HPs') attitudes towards ICI. Methods: The following questionnaires were distributed: (1) self-administered questionnaire randomly given to 261 patients receiving chemotherapy (80% returned); and (2) separate questionnaire given to 58 HPs at the same UK Oncology Centre (83% returned). Results: Just over half of the patient respondents accessed the internet regularly. They were younger, with higher incomes and qualifications. Key search topics included chemotherapy modes of action, symptom management and treatment success, and most considered ICI useful. More than half wanted to discuss ICI with HPs but most did not get the opportunity. Although the majority of HP respondents supported the need for patients to retrieve ICI, most questioned the accuracy of ICI and did not routinely recommend its use. Conclusion: This study has shown that ICI is generally perceived by patients to be a valuable information resource. Given the potential impact of ICI, the following should be addressed in future studies: (1) inequalities in accessing ICI; (2) maintaining the quality of ICI (with clear guidance on recommended websites); (3) bridging the gap between the perception of ICI by patients and HPs; (4) integration of ICI with traditional consultation models. PMID:22262319

  18. Impacts of Diffuse Radiation on Light Use Efficiency across Terrestrial Ecosystems Based on Eddy Covariance Observation in China

    PubMed Central

    Huang, Kun; Wang, Shaoqiang; Zhou, Lei; Wang, Huimin; Zhang, Junhui; Yan, Junhua; Zhao, Liang; Wang, Yanfen; Shi, Peili

    2014-01-01

    Ecosystem light use efficiency (LUE) is a key factor of production models for gross primary production (GPP) predictions. Previous studies revealed that ecosystem LUE could be significantly enhanced by an increase on diffuse radiation. Under large spatial heterogeneity and increasing annual diffuse radiation in China, eddy covariance flux data at 6 sites across different ecosystems from 2003 to 2007 were used to investigate the impacts of diffuse radiation indicated by the cloudiness index (CI) on ecosystem LUE in grassland and forest ecosystems. Our results showed that the ecosystem LUE at the six sites was significantly correlated with the cloudiness variation (0.24≤R2≤0.85), especially at the Changbaishan temperate forest ecosystem (R2 = 0.85). Meanwhile, the CI values appeared more frequently between 0.8 and 1.0 in two subtropical forest ecosystems (Qianyanzhou and Dinghushan) and were much larger than those in temperate ecosystems. Besides, cloudiness thresholds which were favorable for enhancing ecosystem carbon sequestration existed at the three forest sites, respectively. Our research confirmed that the ecosystem LUE at the six sites in China was positively responsive to the diffuse radiation, and the cloudiness index could be used as an environmental regulator for LUE modeling in regional GPP prediction. PMID:25393629

  19. Impact of information and communication technology on child health.

    PubMed

    Woo, Eugenia Hc; White, Peter; Lai, Christopher Wk

    2016-06-01

    This article provides a general framework for understanding the use of information and communication technology in education and discusses the impact of computer usage on students' health and development. Potential beneficial and harmful effects of computer use by children are discussed. Early epidemiological and laboratory studies have indicated that children are at least of similar risk of developing musculoskeletal and vision problems as adults, and musculoskeletal and visual health problems developed in childhood are likely to persist into adulthood. This article, therefore, aims to provide a reflection on the deficits of existing policy and recommendations for child-specific guidelines in computer use. PMID:27333844

  20. Time-dependent modelling of pulsar wind nebulae: study on the impact of the diffusion-loss approximations

    NASA Astrophysics Data System (ADS)

    Martín, Jonatan; Torres, Diego F.; Rea, Nanda

    2012-11-01

    In this work, we present a leptonic, time-dependent model of pulsar wind nebulae (PWNe). The model seeks a solution for the lepton distribution function considering the full time-energy-dependent diffusion-loss equation. The time-dependent lepton population is balanced by injection, energy losses and escape. We include synchrotron, inverse-Compton (IC; with the cosmic-microwave background as well as with IR/optical photon fields), self-synchrotron Compton, and bremsstrahlung processes, all devoid of any radiative approximations. With this model in place we focus on the Crab nebula as an example and present its time-dependent evolution. Afterwards, we analyse the impact of different approximations made at the level of the diffusion-loss equation, as can be found in the literature. Whereas previous models ignored the escape term, e.g. with the diffusion-loss equation becoming advective, others approximated the losses as catastrophic, so that the equation has only time derivatives. Additional approximations are also described and computed. We study what the impact of these approaches is on the determination of the PWN evolution. In particular, we find the time-dependent deviation of the multi-wavelength spectrum and the best-fitting parameters obtained with the complete and the approximate models.

  1. Innovation Value of Information Technology: Impact of Information Technology--Intensity on Innovation Capability and Firm Performance

    ERIC Educational Resources Information Center

    Ramamani, Mahesh Kumar

    2010-01-01

    Though information technology adoptions have been always referred to as innovations in firms, much of the business value literature has concentrated on the tangible and immediately measurable impacts of information technology (IT) adoptions. This study aims to explore the impact of information technology investments on the innovativeness of a…

  2. Spectral Resolution and Coverage Impact on Advanced Sounder Information Content

    NASA Technical Reports Server (NTRS)

    Larar, Allen M.; Liu, Xu; Zhou, Daniel K.; Smith, William L.

    2010-01-01

    Advanced satellite sensors are tasked with improving global measurements of the Earth s atmosphere, clouds, and surface to enable enhancements in weather prediction, climate monitoring capability, and environmental change detection. Achieving such measurement improvements requires instrument system advancements. This presentation focuses on the impact of spectral resolution and coverage changes on remote sensing system information content, with a specific emphasis on thermodynamic state and trace species variables obtainable from advanced atmospheric sounders such as the Infrared Atmospheric Sounding Interferometer (IASI) and Cross-track Infrared Sounder (CrIS) systems on the MetOp and NPP/NPOESS series of satellites. Key words: remote sensing, advanced sounders, information content, IASI, CrIS

  3. The impact of genetic information on policy and clinical practice.

    PubMed

    Abel, Elizabeth; Horner, Sharon D; Tyler, Diane; Innerarity, Sheryl A

    2005-02-01

    This article discusses genetics-related policy issues that have an impact on health care systems, health care providers, and their patients: privacy, mass screening, family screening, and knowledge dissemination. Access, cost, and ethical implications are important discussant points for each of these genetic-related policy issues. Embedded in the issue of privacy are concerns of insurability, confidentiality, and discrimination. The public health policy implications related to mass screening programs include efficacy of the screening tests, availability of primary and secondary interventions, access, costs, and program evaluation. Policy issues for family screening are similar to mass screening, with added concerns about privacy and availability of adequate resources, including health care providers and counselors trained in genetics. Knowledge dissemination is critical to maintaining currency of clinical information and applications of genetic technologies and treatments. As genetic information expands, the need for knowledge dissemination will increase. The importance of advanced practice nurses' involvement in these policy issues is discussed. PMID:16443953

  4. China Refrigerator Information Label: Specification Development and Potential Impact

    SciTech Connect

    Fridley, David; Fridley, David; Zheng, Nina; Zhou, Nan; Aden, Nathaniel; Lin, Jiang; Jianhong, Cheng; Sakamoto, Tomoyuki

    2008-02-01

    In the last five years, China's refrigerator market has grown rapidly, and now urban markets are showing signs of saturation, with ownership rates in urban households reaching 92%. Rural markets continue to grow from a much lower base. As a result of this growth, the Chinese government in 2006 decided to revise the refrigerator standards and its associated efficiency grades for the mandatory energy information label. In the Chinese standards process, the efficiency grades for the information label are tied to the minimum standards. Work on the minimum standards revision began in 2006 and continued through the first half of 2007, when the draft standard was completed under the direction of the China National Institute of Standardization (CNIS). Development of the information label grades required consideration of stakeholder input, continuity with the previous grade classification, ease of implementation, and potential impacts on the market. In this process, CLASP, with the support of METI/IEEJ, collaborated with CNIS to develop the efficiency grades, providing technical input to the process, comment and advice on particular technical issues, and evaluation of the results. After three months of effort and three drafts of the final grade specifications, this work was completed. In addition, in order to effectively evaluate the impact of the label on China's market, CLASP further provided assistance to CNIS to collect data on both the efficiency distribution and product volume distribution of refrigerators on the market. The new information label thresholds to be implemented in 2008 maintain the approach first adopted in 2005 of establishing efficiency levels relative to the minimum standard, but increased the related required efficiency levels by 20% over those established in 2003 and implemented in 2005. The focus of improvement was on the standard refrigerator/freezer (class 5), which constitutes the bulk of the Chinese market. Indeed, the new requirements to

  5. Impact of acute stress on human brain microstructure: An MR diffusion study of earthquake survivors.

    PubMed

    Chen, Long; Lui, Su; Wu, Qi-Zhu; Zhang, Wei; Zhou, Dong; Chen, Hua-Fu; Huang, Xiao-Qi; Kuang, Wei-Hong; Chan, Raymond C; Mechelli, Andrea; Gong, Qi-Yong

    2013-02-01

    A characterization of the impact of natural disasters on the brain of survivors is critical for a better understanding of posttraumatic responses and may inform the development of more effective early interventions. Here we report alterations in white matter microstructure in survivors soon after Wenchuan earthquake in China in 2008. Within 25 days after the Wenchuan earthquake, 44 healthy survivors were recruited and scanned on a 3T MR imaging system. The survivors were divided into two groups according to their self-rating anxiety scale (SAS) score, including the SAS(+) (SAS > 55 after correction) group and "SAS(-)" (SAS < 55 after correction) group. Thrity-two healthy volunteers were also recruited as control group before earthquake. Individual maps of fractional anisotropy (FA) were calculated and voxel-based analysis (VBA) was performed to allow the comparison between survivors and controls using ANCOVAs in SPM2. In addition, a correlation between SAS score and regional FA value was examined using Pearson's correlation analysis in SPSS 11.5. Compared with the healthy cohort, the whole group of 44 survivors showed significantly decreased FA values in the right prefrontal lobe, the parietal lobe, the basal ganglia, and the right parahippocampus. These effects did not appear to depend on self-rating anxiety. For the first time we provide evidence that acute trauma altered cerebral microstructure within the limbic system; furthermore, these alterations are evident shortly after the traumatic event, highlighting the need for early evaluation and intervention for trauma survivors. PMID:22042533

  6. Diffusion in Colocation Contact Networks: The Impact of Nodal Spatiotemporal Dynamics

    PubMed Central

    Thomas, Bryce; Jurdak, Raja; Zhao, Kun; Atkinson, Ian

    2016-01-01

    Temporal contact networks are studied to understand dynamic spreading phenomena such as communicable diseases or information dissemination. To establish how spatiotemporal dynamics of nodes impact spreading potential in colocation contact networks, we propose “inducement-shuffling” null models which break one or more correlations between times, locations and nodes. By reconfiguring the time and/or location of each node’s presence in the network, these models induce alternative sets of colocation events giving rise to contact networks with varying spreading potential. This enables second-order causal reasoning about how correlations in nodes’ spatiotemporal preferences not only lead to a given contact network but ultimately influence the network’s spreading potential. We find the correlation between nodes and times to be the greatest impediment to spreading, while the correlation between times and locations slightly catalyzes spreading. Under each of the presented null models we measure both the number of contacts and infection prevalence as a function of time, with the surprising finding that the two have no direct causality. PMID:27501240

  7. Modeling the impacts of solar radiation partitioning into direct and diffuse fractions for the global water cycle

    NASA Astrophysics Data System (ADS)

    Oliveira, Paulo J. C.; Davin, Edouard L.; Seneviratne, Sonia I.

    2010-05-01

    Incident solar radiation at the Earth's surface affects plant photosynthesis and evapotranspiration, and consequently the global water budget. Observations from 1960-1990's across the Northern Hemisphere suggest that increased aerosol loadings from industrialization led not only to a decline in the intensity of solar radiation at the surface (global dimming), but also to a higher fraction of scattered light, which enhanced plant photosynthesis and the land carbon sink, with probable concurrent impacts on the water cycle. Thus, we used the NCAR Community Land Model (version 3.5) to perform global offline simulations and study the effects of the imposition of changes to radiation partitioning in diffuse and direct fractions on trends in evapotranspiration and runoff. We find that most modeled land surface variables respond to an increased-diffuse simulation where the relative fraction of radiation is changed globally at a high rate of increased diffuse as reported by some observation stations. Increased-diffuse partitioning causes a rise in total ET in all regions, an effect of opposite sign but smaller absolute value than that resulting from global dimming. Evapotranspiration rises by over 0.5 watt/m2 per decade in the tropics, due to increased shaded leaf stomatal conductance, with an opposite effect noted elsewhere due to lower ground evaporation. In the eastern U.S.A. and the Amazon basin, decadal trend anomalies in evapotranspiration for increased-diffuse radiation change reach 25-30% the absolute magnitude of those caused by dimming. Reductions to river runoff are modest nearly everywhere outside the Amazon. Understanding the mechanisms behind the interactions between solar radiation and the various land-surface components will help the development of climate models, improving predictions, in particular regarding changes in terrestrial hydrologic resources.

  8. Spatial Resolution, Grayscale, and Error Diffusion Trade-offs: Impact on Display System Design

    NASA Technical Reports Server (NTRS)

    Gille, Jennifer L. (Principal Investigator)

    1996-01-01

    We examine technology trade-offs related to grayscale resolution, spatial resolution, and error diffusion for tessellated display systems. We present new empirical results from our psychophysical study of these trade-offs and compare them to the predictions of a model of human vision.

  9. The impact of probe size on measurements of diffusion in active microrheology.

    PubMed

    Hoh, Nicholas J; Zia, Roseanna N

    2016-08-21

    We present a framework to elucidate the influence of polydispersity on flow-induced diffusion in active microrheology. A colloidal probe particle is driven through a suspension of hydrodynamically interacting background particles, where the probe may be larger or smaller than the bath particles. The thermodynamic size of the particles may be greater than their hydrodynamic size; the hydrodynamic sizes can be identical with thermodynamic sizes that differ, or vice versa, or a combination of both. The diffusive behavior is set entirely and dually by the proximity with which two particles can approach one another, and by the extent to which this minimum approach distance is occupied by the hydrodynamic size of the forced particle. We find that reducing the size of the probe reduces flow-induced diffusion when hydrodynamic interactions are weak but increases flow-induced diffusion when hydrodynamic interactions are strong-regardless of the strength of external forcing. This behavior owes its origins to a rich evolution of the dominance of hydrodynamic and entropic forces with changes in the relative hydrodynamic and thermodynamic sizes of the particles. PMID:27442485

  10. Impact of Measurement System Characteristics on Advanced Sounder Information Content

    NASA Technical Reports Server (NTRS)

    Larar, Allen M.; Liu, Xu; Zhou, Daniel K.

    2011-01-01

    Advanced satellite sensors are tasked with improving global observations of the Earth's atmosphere, clouds, and surface to enable enhancements in weather prediction, climate monitoring capability, and environmental change detection. Achieving such an improvement in geophysical information inferred from these observations requires optimal usage of data from current systems as well as instrument system enhancements for future sensors. This presentation addresses results of tradeoff studies evaluating the impact of spectral resolution, spectral coverage, instrument noise, and a priori knowledge on remote sensing system information content, with a specific emphasis on thermodynamic state and trace species information obtainable from advanced atmospheric sounders. Particular attention will be devoted toward information achievable from the Atmospheric InfraRed Sounder (AIRS) on the NASA EOS Aqua satellite in orbit since 2002, the Infrared Atmospheric Sounding Interferometer (IASI) aboard MetOp-A since 2006, and the Cross-track Infrared Sounder (CrIS) instrument to fly aboard the NPP and JPSS series of satellites expected to begin in late 2011. While all of these systems cover nearly the same infrared spectral extent, they have very different number of channels, instrument line shapes, coverage continuity, and instrument noise. AIRS is a grating spectrometer having 2378 discrete spectral channels ranging from about 0.4 to 2.2/cm resolution; IASI is a Michelson interferometer with 8461 uniformly-spaced spectral channels of 0.5/cm (apodized) resolution; and CrIS is a Michelson interferometer having 1305 spectral channels of 0.625, 1.250, and 2.50/cm (unapodized) spectral resolution, respectively, over its three continuous but non-overlapping bands. Results of tradeoff studies showing information content sensitivity to assumed measurement system characteristics will be presented.

  11. NASA/DOD Aerospace Knowledge Diffusion Research Project. Report 22: US academic librarians and technical information specialists as information intermediaries: Results of the phase 3 survey

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Barclay, Rebecca O.; Kennedy, John M.

    1994-01-01

    The U.S. government technical report is a primary means by which the results of federally funded research and development (R&D) are transferred to the U.S. aerospace industry. However, little is known about this information product in terms of its actual use, importance, and value in the transfer of federally funded R&D. To help establish a body of knowledge, the U.S. government technical report is being investigated as part of the NASA/DOD Aerospace Knowledge Diffusion Research Project. In this report, we summarize the literature on technical reports and provide a model that depicts the transfer of federally funded aerospace R&D via the U.S. government technical report. We present results from our investigation of aerospace knowledge diffusion vis-a-vis the U.S. government technical report, and present the results of research that investigated aerospace knowledge diffusion vis-a-vis U.S. academic librarians and technical information specialists as information intermediaries.

  12. NASA/DOD Aerospace Knowledge Diffusion Research Project. Report number 21: US aerospace industry librarians and technical information specialists as information intermediaries: Results of the phase 2 survey

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Barclay, Rebecca O.; Kennedy, John M.

    1994-01-01

    The U.S. government technical report is a primary means by which the results of federally funded research and development (R&D) are transferred to the U.S. aerospace industry. However, little is known about this information product in terms of its actual use, importance, and value in the transfer of federally funded R&D. To help establish a body of knowledge, the U.S. government technical report is being investigated as part of the NASA/DoD Aerospace Knowledge Diffusion Research Project. In this report, we summarize the literature on technical reports and provide a model that depicts the transfer of federally funded aerospace R&D via the U.S. government technical report. We present results from our investigation of aerospace knowledge diffusion vis-a-vis the U.S. government technical report, and present the results of research that investigated aerospace knowledge diffusion vis-a-vis U.S. aerospace industry librarians and technical information specialists as information intermediaries.

  13. Impact of Repeated Exposures on Information Spreading in Social Networks.

    PubMed

    Zhou, Cangqi; Zhao, Qianchuan; Lu, Wenbo

    2015-01-01

    Clustered structure of social networks provides the chances of repeated exposures to carriers with similar information. It is commonly believed that the impact of repeated exposures on the spreading of information is nontrivial. Does this effect increase the probability that an individual forwards a message in social networks? If so, to what extent does this effect influence people's decisions on whether or not to spread information? Based on a large-scale microblogging data set, which logs the message spreading processes and users' forwarding activities, we conduct a data-driven analysis to explore the answer to the above questions. The results show that an overwhelming majority of message samples are more probable to be forwarded under repeated exposures, compared to those under only a single exposure. For those message samples that cover various topics, we observe a relatively fixed, topic-independent multiplier of the willingness of spreading when repeated exposures occur, regardless of the differences in network structure. We believe that this finding reflects average people's intrinsic psychological gain under repeated stimuli. Hence, it makes sense that the gain is associated with personal response behavior, rather than network structure. Moreover, we find that the gain is robust against the change of message popularity. This finding supports that there exists a relatively fixed gain brought by repeated exposures. Based on the above findings, we propose a parsimonious model to predict the saturated numbers of forwarding activities of messages. Our work could contribute to better understandings of behavioral psychology and social media analytics. PMID:26465749

  14. Impact of the atomic layer deposition precursors diffusion on solid-state carbon nanotube based supercapacitors performances.

    PubMed

    Fiorentino, Giuseppe; Vollebregt, Sten; Tichelaar, F D; Ishihara, Ryoichi; Sarro, Pasqualina M

    2015-02-13

    A study on the impact of atomic layer deposition (ALD) precursors diffusion on the performance of solid-state miniaturized nanostructure capacitor array is presented. Three-dimensional nanostructured capacitor array based on double conformal coating of multiwalled carbon nanotubes (MWCNTs) bundles is realized using ALD to deposit Al2O3 as dielectric layer and TiN as high aspect-ratio conformal counter-electrode on 2 μm long MWCNT bundles. The devices have a small footprint (from 100 μm(2) to 2500 μm(2)) and are realized using an IC wafer-scale manufacturing process with high reproducibility (≤0.3E-12F deviation). To evaluate the enhancement of the electrode surface, the measured capacitance values are compared to a lumped circuital model. The observed discrepancies are explained with a partial coating of the CNT, that determine a limited use of the available electrode surface area. To analyze the CNT coating effectiveness, the ALD precursors diffusions inside the CNT bundle is studied using a Knudsen diffusion mechanism. PMID:25604841

  15. Impact of Mesophyll Diffusion on Estimated Global Land CO2 Fertilization

    NASA Astrophysics Data System (ADS)

    Sun, Y.; Gu, L.; Dickinson, R. E.

    2014-12-01

    In C3 plants, CO2 concentrations drop considerably along mesophyll diffusion pathways from substomatal cavities to chloroplasts where CO2 assimilation occurs. Global carbon cycle models have not explicitly represented this internal drawdown and so overestimate CO2 available for carboxylation and underestimate photosynthetic responsiveness to atmospheric CO2. An explicit consideration of mesophyll diffusion increases the modeled cumulative CO2 fertilization effect (CFE) for global gross primary production (GPP) from 915 PgC to 1057 PgC for the period of 1901 to 2010. This increase represents a 16% correction large enough to explain the persistent overestimation of growth rates of historical atmospheric CO2 by Earth System Models. Without this correction, the CFE for global GPP is underestimated by 0.05 PgC yr-1ppm-1. This finding implies that the contemporary terrestrial biosphere is more CO2-limited than previously thought.

  16. Impact of mesophyll diffusion on estimated global land CO2 fertilization

    DOE PAGESBeta

    Sun, Ying; Gu, Lianhong; Dickinson, Robert E.; Norby, Richard J.; Pallardy, Stephen G.; Hoffman, Forrest M.

    2014-10-13

    In C3 plants, CO2 concentrations drop considerably along mesophyll diffusion pathways from substomatal cavities to chloroplasts where CO2 assimilation occurs. Global carbon cycle models have not explicitly represented this internal drawdown and so overestimate CO2 available for carboxylation and underestimate photosynthetic responsiveness to atmospheric CO2. An explicit consideration of mesophyll diffusion increases the modeled cumulative CO2 fertilization effect (CFE) for global gross primary production (GPP) from 915 PgC to 1057 PgC for the period of 1901 to 2010. This increase represents a 16% correction, large enough to explain the persistent overestimation of growth rates of historical atmospheric CO2 by Earthmore » System Models. Without this correction, the CFE for global GPP is underestimated by 0.05 PgC yr-1ppm-1. This finding implies that the contemporary terrestrial biosphere is more CO2-limited than previously thought.« less

  17. Atomic diffusion on vicinal surfaces: step roughening impact on step permeability

    NASA Astrophysics Data System (ADS)

    Ranguelov, B.; Michailov, M.

    2014-12-01

    The problem of mass transport in material science for systems with reduced dimensionality holds special academic and technological attention since the fine diffusion control of adatoms could initiate exotic nanoscale patterning at epitaxial interfaces. The present study brings out important details of the atomic diffusion mechanisms on vicinal surfaces, accounting for the subtle competition between an external field imposed on the migrating adatoms and the roughening of the steps bordering the atomic terraces. The computational model reveals a temperature gap for breakdown of step permeability in the vicinity of the step roughening transition and sheds light on recently observed experimental results for atomic step dynamics on Si surfaces. The present study also demonstrates the extended capability of atomistic models in computer simulations to unravel simultaneous effects, to distinguish between them, and finally to assess their specific contribution to experimentally observed complex physical phenomena.

  18. Critical Role of Dynamic Flexibility in Ge-Containing Zeolites: Impact on Diffusion.

    PubMed

    Gutiérrez-Sevillano, Juan José; Calero, Sofía; Hamad, Said; Grau-Crespo, Ricardo; Rey, Fernando; Valencia, Susana; Palomino, Miguel; Balestra, Salvador R G; Ruiz-Salvador, A Rabdel

    2016-07-11

    Incorporation of germanium in zeolites is well known to confer static flexibility to their framework, by stabilizing the formation of small rings. In this work, we show that the flexibility associated to Ge atoms in zeolites goes beyond this static effect, manifesting also a clear dynamic nature, in the sense that it leads to enhanced molecular diffusion. Our study combines experimental and theoretical methods providing evidence for this effect, which has not been described previously, as well as a rationalization for it, based on atomistic grounds. We have used both pure-silica and silico-germanate ITQ-29 (LTA topology) zeolites as a case study. Based on our simulations, we identify the flexibility associated to the pore breathing-like behavior induced by the Ge atoms, as the key factor leading to the enhanced diffusion observed experimentally in Ge-containing zeolites. PMID:27305363

  19. Impact of homogeneous strain on uranium vacancy diffusion in uranium dioxide

    NASA Astrophysics Data System (ADS)

    Goyal, Anuj; Phillpot, Simon R.; Subramanian, Gopinath; Andersson, David A.; Stanek, Chris R.; Uberuaga, Blas P.

    2015-03-01

    We present a detailed mechanism of, and the effect of homogeneous strains on, the migration of uranium vacancies in UO2. Vacancy migration pathways and barriers are identified using density functional theory and the effect of uniform strain fields are accounted for using the dipole tensor approach. We report complex migration pathways and noncubic symmetry associated with the uranium vacancy in UO2 and show that these complexities need to be carefully accounted for to predict the correct diffusion behavior of uranium vacancies. We show that under homogeneous strain fields, only the dipole tensor of the saddle with respect to the minimum is required to correctly predict the change in the energy barrier between the strained and the unstrained case. Diffusivities are computed using kinetic Monte Carlo simulations for both neutral and fully charged state of uranium single and divacancies. We calculate the effect of strain on migration barriers in the temperature range 800-1800 K for both vacancy types. Homogeneous strains as small as 2 % have a considerable effect on diffusivity of both single and divacancies of uranium, with the effect of strain being more pronounced for single vacancies than divacancies. In contrast, the response of a given defect to strain is less sensitive to changes in the charge state of the defect. Further, strain leads to anisotropies in the mobility of the vacancy and the degree of anisotropy is very sensitive to the nature of the applied strain field for strain of equal magnitude. Our results suggest that the influence of strain on vacancy diffusivity will be significantly greater when single vacancies dominate the defect structure, such as sintering, while the effects will be much less substantial under irradiation conditions where divacancies dominate.

  20. Impact of multi-component diffusion in turbulent combustion using direct numerical simulations

    SciTech Connect

    Bruno, Claudio; Sankaran, Vaidyanathan; Kolla, Hemanth; Chen, Jacqueline H.

    2015-08-28

    This study presents the results of DNS of a partially premixed turbulent syngas/air flame at atmospheric pressure. The objective was to assess the importance and possible effects of molecular transport on flame behavior and structure. To this purpose DNS were performed at with two proprietary DNS codes and with three different molecular diffusion transport models: fully multi-component, mixture averaged, and imposing the Lewis number of all species to be unity.

  1. Impact of homogeneous strain on uranium vacancy diffusion in uranium dioxide

    DOE PAGESBeta

    Goyal, Anuj; Phillpot, Simon R.; Subramanian, Gopinath; Andersson, David A.; Stanek, Chris R.; Uberuaga, Blas P.

    2015-03-03

    We present a detailed mechanism of, and the effect of homogeneous strains on, the migration of uranium vacancies in UO2. Vacancy migration pathways and barriers are identified using density functional theory and the effect of uniform strain fields are accounted for using the dipole tensor approach. We report complex migration pathways and noncubic symmetry associated with the uranium vacancy in UO2 and show that these complexities need to be carefully accounted for to predict the correct diffusion behavior of uranium vacancies. We show that under homogeneous strain fields, only the dipole tensor of the saddle with respect to the minimummore » is required to correctly predict the change in the energy barrier between the strained and the unstrained case. Diffusivities are computed using kinetic Monte Carlo simulations for both neutral and fully charged state of uranium single and divacancies. We calculate the effect of strain on migration barriers in the temperature range 800–1800 K for both vacancy types. Homogeneous strains as small as 2% have a considerable effect on diffusivity of both single and divacancies of uranium, with the effect of strain being more pronounced for single vacancies than divacancies. In contrast, the response of a given defect to strain is less sensitive to changes in the charge state of the defect. Further, strain leads to anisotropies in the mobility of the vacancy and the degree of anisotropy is very sensitive to the nature of the applied strain field for strain of equal magnitude. Our results indicate that the influence of strain on vacancy diffusivity will be significantly greater when single vacancies dominate the defect structure, such as sintering, while the effects will be much less substantial under irradiation conditions where divacancies dominate.« less

  2. Impact of homogeneous strain on uranium vacancy diffusion in uranium dioxide

    SciTech Connect

    Goyal, Anuj; Phillpot, Simon R.; Subramanian, Gopinath; Andersson, David A.; Stanek, Chris R.; Uberuaga, Blas P.

    2015-03-03

    We present a detailed mechanism of, and the effect of homogeneous strains on, the migration of uranium vacancies in UO2. Vacancy migration pathways and barriers are identified using density functional theory and the effect of uniform strain fields are accounted for using the dipole tensor approach. We report complex migration pathways and noncubic symmetry associated with the uranium vacancy in UO2 and show that these complexities need to be carefully accounted for to predict the correct diffusion behavior of uranium vacancies. We show that under homogeneous strain fields, only the dipole tensor of the saddle with respect to the minimum is required to correctly predict the change in the energy barrier between the strained and the unstrained case. Diffusivities are computed using kinetic Monte Carlo simulations for both neutral and fully charged state of uranium single and divacancies. We calculate the effect of strain on migration barriers in the temperature range 800–1800 K for both vacancy types. Homogeneous strains as small as 2% have a considerable effect on diffusivity of both single and divacancies of uranium, with the effect of strain being more pronounced for single vacancies than divacancies. In contrast, the response of a given defect to strain is less sensitive to changes in the charge state of the defect. Further, strain leads to anisotropies in the mobility of the vacancy and the degree of anisotropy is very sensitive to the nature of the applied strain field for strain of equal magnitude. Our results indicate that the influence of strain on vacancy diffusivity will be significantly greater when single vacancies dominate the defect structure, such as sintering, while the effects will be much less substantial under irradiation conditions where divacancies dominate.

  3. Impacts of diffusive transport on carbonate mineral formation from magnesium silicate-CO2-water reactions.

    PubMed

    Giammar, Daniel E; Wang, Fei; Guo, Bin; Surface, J Andrew; Peters, Catherine A; Conradi, Mark S; Hayes, Sophia E

    2014-12-16

    Reactions of CO2 with magnesium silicate minerals to precipitate magnesium carbonates can result in stable carbon sequestration. This process can be employed in ex situ reactors or during geologic carbon sequestration in magnesium-rich formations. The reaction of aqueous CO2 with the magnesium silicate mineral forsterite was studied in systems with transport controlled by diffusion. The approach integrated bench-scale experiments, an in situ spectroscopic technique, and reactive transport modeling. Experiments were performed using a tube packed with forsterite and open at one end to a CO2-rich solution. The location and amounts of carbonate minerals that formed were determined by postexperiment characterization of the solids. Complementing this ex situ characterization, (13)C NMR spectroscopy tracked the inorganic carbon transport and speciation in situ. The data were compared with the output of reactive transport simulations that accounted for diffusive transport processes, aqueous speciation, and the forsterite dissolution rate. All three approaches found that the onset of magnesium carbonate precipitation was spatially localized about 1 cm from the opening of the forsterite bed. Magnesite was the dominant reaction product. Geochemical gradients that developed in the diffusion-limited zones led to locally supersaturated conditions at specific locations even while the volume-averaged properties of the system remained undersaturated. PMID:25420634

  4. Impact of Repeated Exposures on Information Spreading in Social Networks

    PubMed Central

    Zhou, Cangqi; Zhao, Qianchuan; Lu, Wenbo

    2015-01-01

    Clustered structure of social networks provides the chances of repeated exposures to carriers with similar information. It is commonly believed that the impact of repeated exposures on the spreading of information is nontrivial. Does this effect increase the probability that an individual forwards a message in social networks? If so, to what extent does this effect influence people’s decisions on whether or not to spread information? Based on a large-scale microblogging data set, which logs the message spreading processes and users’ forwarding activities, we conduct a data-driven analysis to explore the answer to the above questions. The results show that an overwhelming majority of message samples are more probable to be forwarded under repeated exposures, compared to those under only a single exposure. For those message samples that cover various topics, we observe a relatively fixed, topic-independent multiplier of the willingness of spreading when repeated exposures occur, regardless of the differences in network structure. We believe that this finding reflects average people’s intrinsic psychological gain under repeated stimuli. Hence, it makes sense that the gain is associated with personal response behavior, rather than network structure. Moreover, we find that the gain is robust against the change of message popularity. This finding supports that there exists a relatively fixed gain brought by repeated exposures. Based on the above findings, we propose a parsimonious model to predict the saturated numbers of forwarding activities of messages. Our work could contribute to better understandings of behavioral psychology and social media analytics. PMID:26465749

  5. NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 12: The diffusion of federally funded aerospace research and development (R/D) and the information seeking behavior of US aerospace engineers and scientists

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Kennedy, John M.; Barclay, Rebecca O.

    1991-01-01

    In this paper, the diffusion of federally funded aerospace R&D is explored from the perspective of the information-seeking behavior of U.S. aerospace engineers and scientists. The following three assumptions frame this exploration: (1) knowledge production, transfer, and utilization are equally important components of the aerospace R&D process; (2) the diffusion of knowledge resulting from federally funded aerospace R&D is indispensable for the U.S. to remain a world leader in aerospace; and (3) U.S. government technical reports, produced by NASA and DOD, play an important, but as yet undefined, role in the diffusion of federally funded aerospace R&D. A conceptual model for federally funded aerospace knowledge diffusion, one that emphasizes U.S. goverment technical reports, is presented. Data regarding three research questions concerning the information-seeking behavior of U.S. aerospace engineers and scientists are also presented.

  6. R&D Advancement, Technology Diffusion, and Impact on Evaluation of Public R&D

    SciTech Connect

    Moore, M. C.; Arent, D. J.; Norland, D.

    2005-01-01

    In a 2001 report titled "Research at DOE: Was It Worth It?", a National Research Council (NRC) committee defined a set of simplifying rules to estimate the net economic benefits from technologies supported by the Department of Energy (DOE). This NREL paper evaluates the efficacy of the NRC rules compared to published literature on acceleration of technology introduction into markets, technology diffusion, and infrastructure change. It also offers considerations for revisions of the rules that call for the use of technology and sector-specific data, advanced forecasting techniques, and sensitivity analysis to test the robustness of the methodology.

  7. Diffuse Large B-cell lymphoma: Prognostic markers and their impact on therapy.

    PubMed

    Jamil, Muhammad O; Mehta, Amitkumar

    2016-05-01

    Diffuse large B-cell lymphoma (DLBCL) is the most common type of Non-Hodgkin lymphoma (NHL). DLBCL is clinically, pathologically and molecularly heterogeneous disease. Various clinical, pathological and molecular markers have been developed to characterize the disease. Based on these characterizations, new targeted agents are being investigated to optimize the treatment and improve the outcomes of DLBCL. Enhanced molecular understanding, invention of targeted agents and immunotherapy has opened the doors for improvement in the treatment of DLBCL. In this review, we will discuss various prognostic markers of DLBCL and their potential therapeutic implications. PMID:26808217

  8. 40Ar/39Ar impact ages and time-temperature argon diffusion history of the Bunburra Rockhole anomalous basaltic achondrite

    NASA Astrophysics Data System (ADS)

    Jourdan, Fred; Benedix, Gretchen; Eroglu, Ela.; Bland, Phil. A.; Bouvier, Audrey.

    2014-09-01

    The Bunburra Rockhole meteorite is a brecciated anomalous basaltic achondrite containing coarse-, medium- and fine-grained lithologies. Petrographic observations constrain the limited shock pressure to between ca. 10 GPa and 20 GPa. In this study, we carried out nine 40Ar/39Ar step-heating experiments on distinct single-grain fragments extracted from the coarse and fine lithologies. We obtained six plateau ages and three mini-plateau ages. These ages fall into two internally concordant populations with mean ages of 3640 ± 21 Ma (n = 7; P = 0.53) and 3544 ± 26 Ma (n = 2; P = 0.54), respectively. Based on these results, additional 40Ar/39Ar data of fusion crust fragments, argon diffusion modelling, and petrographic observations, we conclude that the principal components of the Bunburra Rockhole basaltic achondrite are from a melt rock formed at ∼3.64 Ga by a medium to large impact event. The data imply that this impact generated high enough energy to completely melt the basaltic target rock and reset the Ar systematics, but only partially reset the Pb-Pb age. We also conclude that a complete 40Ar∗ resetting of pyroxene and plagioclase at this time could not have been achieved at solid-state conditions. Comparison with a terrestrial analog (Lonar crater) shows that the time-temperature conditions required to melt basaltic target rocks upon impact are relatively easy to achieve. Ar data also suggest that a second medium-size impact event occurred on a neighbouring part of the same target rock at ∼3.54 Ga. Concordant low-temperature step ages of the nine aliquots suggest that, at ∼3.42 Ga, a third smaller impact excavated parts of the ∼3.64 Ga and ∼3.54 Ga melt rocks and brought the fragments together. The lack of significant impact activity after 3.5 Ga, as recorded by the Bunburra Rockhole suggests that (1) either the meteorite was ejected in a small secondary parent body where it resided untouched by large impacts, or (2) it was covered by a porous heat

  9. Impact of mesophyll diffusion on estimated global land CO2 fertilization

    SciTech Connect

    Sun, Ying; Gu, Lianhong; Dickinson, Robert E.; Norby, Richard J.; Pallardy, Stephen G.; Hoffman, Forrest M.

    2014-10-13

    In C3 plants, CO2 concentrations drop considerably along mesophyll diffusion pathways from substomatal cavities to chloroplasts where CO2 assimilation occurs. Global carbon cycle models have not explicitly represented this internal drawdown and so overestimate CO2 available for carboxylation and underestimate photosynthetic responsiveness to atmospheric CO2. An explicit consideration of mesophyll diffusion increases the modeled cumulative CO2 fertilization effect (CFE) for global gross primary production (GPP) from 915 PgC to 1057 PgC for the period of 1901 to 2010. This increase represents a 16% correction, large enough to explain the persistent overestimation of growth rates of historical atmospheric CO2 by Earth System Models. Without this correction, the CFE for global GPP is underestimated by 0.05 PgC yr-1ppm-1. This finding implies that the contemporary terrestrial biosphere is more CO2-limited than previously thought.

  10. Working memory training impacts the mean diffusivity in the dopaminergic system.

    PubMed

    Takeuchi, Hikaru; Taki, Yasuyuki; Nouchi, Rui; Hashizume, Hiroshi; Sekiguchi, Atsushi; Kotozaki, Yuka; Nakagawa, Seishu; Miyauchi, Carlos Makoto; Sassa, Yuko; Kawashima, Ryuta

    2015-11-01

    Dopaminergic transmission plays a critical role in working memory (WM). Mean diffusivity (MD) is a sensitive and unique neuroimaging tool for detecting microstructural differences particularly in the areas of the dopaminergic system. Despite previous investigation of the effects of WM training (WMT) on dopamine receptor binding potentials, the effects of WMT on MD remain unknown. In this study, we investigated these effects in young adult subjects who either underwent WMT or received no intervention for 4 weeks. Before and after the intervention or no-intervention periods, subjects underwent scanning sessions in diffusion-weighted imaging to measure MD. Compared with no intervention, WMT resulted in an increase in MD in the bilateral caudate, right putamen, left dorsolateral prefrontal cortex (DLPFC), right anterior cingulate cortex (ACC), right substantia nigra, and ventral tegmental area. Furthermore, the increase in performance on WMT tasks was significantly positively correlated with the mean increase in MD in the clusters of the left DLPFC and of the right ACC. These results suggest that WMT caused microstructural changes in the regions of the dopaminergic system in a way that is usually interpreted as a reduction in neural components. PMID:25023736

  11. Oscillating gradient diffusion MRI reveals unique microstructural information in normal and hypoxia-ischemia injured mouse brains

    PubMed Central

    Wu, Dan; Martin, Lee J.; Northington, Frances J.; Zhang, Jiangyang

    2014-01-01

    Purpose We investigated whether oscillating gradient diffusion MRI (dMRI) can provide information on brain microstructural changes after formaldehyde fixation and after hypoxic-ischemic (HI) injury beyond that provided by conventional dMRI. Methods Pulsed gradient spin echo (PGSE) and oscillating gradient spin echo (OGSE) dMRI of the adult mouse brain was performed in vivo (50-200 Hz, b = 600 mm2/s), and a similar protocol was applied to neonatal mouse brains at 24 hours after unilateral hypoxia-ischemia. Animals were perfusion fixed with 4% paraformaldehyde for ex vivo dMRI and histology. Results Apparent diffusion coefficients (ADCs) measured in the live adult mouse brain presented tissue-dependent frequency-dependence. In vivo OGSE-ADC maps at high oscillating frequencies (>100Hz) showed clear contrast between the molecular layer and granule cell layer in the adult mouse cerebellum. Formaldehyde fixation significantly altered the temporal diffusion spectra in several brain regions. In neonatal mouse brains with HI injury, in vivo ADC measurements from edema regions showed diminished edema contrasts at 200 Hz compared to the PGSE results. Histology showed severe tissue swelling and necrosis in the edema regions. Conclusion The results demonstrate the unique ability of OGSE-dMRI in delineating tissue microstructures at different spatial scales. PMID:25168861

  12. European information on climate change impacts, vulnerability and adaptation

    NASA Astrophysics Data System (ADS)

    Jol, A.; Isoard, S.

    2010-09-01

    development in 2010 and is likely to manage the system after 2011. The European Commission in its Communication in 2009 on disaster risk prevention also calls for improving and better sharing of data on disasters, disaster risk mapping and disaster risk management, in the context of the EU civil protection mechanism. Such information might also be linked to the planned EU Clearinghouse on climate change adaptation. The activities of EEA on climate change impacts, vulnerability and adaptation (including disaster risk reduction) include indicators of the impacts of climate change; a regularly updated overview of national assessments and adaptation plans on the EEA web site and specific focused reports, e.g. on adaptation to the challenges of changing water resources in the Alps (2009) and on analysis of past trends in natural disasters (due in 2010) and regular expert meetings and workshops with EEA member countries. The ECAC presentation will include the latest developments in the EU Clearinghouse on adaptation and progress in relevant EEA activities.

  13. Social relevance: toward understanding the impact of the individual in an information cascade

    NASA Astrophysics Data System (ADS)

    Hall, Robert T.; White, Joshua S.; Fields, Jeremy

    2016-05-01

    Information Cascades (IC) through a social network occur due to the decision of users to disseminate content. We define this decision process as User Diffusion (UD). IC models typically describe an information cascade by treating a user as a node within a social graph, where a node's reception of an idea is represented by some activation state. The probability of activation then becomes a function of a node's connectedness to other activated nodes as well as, potentially, the history of activation attempts. We enrich this Coarse-Grained User Diffusion (CGUD) model by applying actor type logics to the nodes of the graph. The resulting Fine-Grained User Diffusion (FGUD) model utilizes prior research in actor typing to generate a predictive model regarding the future influence a user will have on an Information Cascade. Furthermore, we introduce a measure of Information Resonance that is used to aid in predictions regarding user behavior.

  14. Wear resistance of diffusion coatings on the working parts of impact-rebound crushers

    SciTech Connect

    Nedzel'skii, M.D.; Katkov, Y.K.

    1984-01-01

    Impact-rebound crushers used in the chemical industry suffer intensive wear of the crusher blades when crushing materials like quartz sand, corundum, and diabase. A special impact-rebound crushers has been made for testing the wear resistance of hardened prototype blades, andi it is described in detail in this paper. Tests were done to determine the most effective methods of surface hardening for the replaceable inserts made of readily available steel and it is found that the carbonitriding of steel gives a hardened layer to increase the wear resistance of the crusher body and rotor surfaces.

  15. The diffusion of maize to the southwestern United States and its impact.

    PubMed

    Merrill, William L; Hard, Robert J; Mabry, Jonathan B; Fritz, Gayle J; Adams, Karen R; Roney, John R; MacWilliams, A C

    2009-12-15

    Our understanding of the initial period of agriculture in the southwestern United States has been transformed by recent discoveries that establish the presence of maize there by 2100 cal. B.C. (calibrated calendrical years before the Christian era) and document the processes by which it was integrated into local foraging economies. Here we review archaeological, paleoecological, linguistic, and genetic data to evaluate the hypothesis that Proto-Uto-Aztecan (PUA) farmers migrating from a homeland in Mesoamerica introduced maize agriculture to the region. We conclude that this hypothesis is untenable and that the available data indicate instead a Great Basin homeland for the PUA, the breakup of this speech community into northern and southern divisions approximately 6900 cal. B.C. and the dispersal of maize agriculture from Mesoamerica to the US Southwest via group-to-group diffusion across a Southern Uto-Aztecan linguistic continuum. PMID:19995985

  16. The diffusion of maize to the southwestern United States and its impact

    PubMed Central

    Merrill, William L.; Hard, Robert J.; Mabry, Jonathan B.; Fritz, Gayle J.; Adams, Karen R.; Roney, John R.; MacWilliams, A. C.

    2009-01-01

    Our understanding of the initial period of agriculture in the southwestern United States has been transformed by recent discoveries that establish the presence of maize there by 2100 cal. B.C. (calibrated calendrical years before the Christian era) and document the processes by which it was integrated into local foraging economies. Here we review archaeological, paleoecological, linguistic, and genetic data to evaluate the hypothesis that Proto-Uto-Aztecan (PUA) farmers migrating from a homeland in Mesoamerica introduced maize agriculture to the region. We conclude that this hypothesis is untenable and that the available data indicate instead a Great Basin homeland for the PUA, the breakup of this speech community into northern and southern divisions ≈6900 cal. B.C. and the dispersal of maize agriculture from Mesoamerica to the US Southwest via group-to-group diffusion across a Southern Uto-Aztecan linguistic continuum. PMID:19995985

  17. Privatization of the gaseous diffusion plants and impacts on nuclear criticality safety administration

    SciTech Connect

    D`Aquila, D.M.; Holliday, R.T.; Dean, J.C.

    1996-12-31

    The Energy Policy Act of 1992 created the United States Enrichment Corporation (USEC) on July 1, 1993. The USEC is a government-owned business that leases those Gaseous Diffusion Plant (GDP) facilities at the Portsmouth, Ohio, and Paducah, Kentucky, sites from the U.S. Department of Energy (DOE) that are required for enriching uranium. Lockheed Martin Utility Services is the operating contractor for the USEC-leased facilities. The DOE has retained use of, and regulation over, some facilities and areas at the Portsmouth and Paducah sites for managing legacy wastes and environmental restoration activities. The USEC is regulated by the DOE, but is currently changing to regulation under the U.S. Nuclear Regulatory Commission (NRC). The USEC is also preparing for privatization of the uranium enrichment enterprise. These changes have significantly affected the nuclear criticality safety (NCS) programs at the sites.

  18. Information geometric analysis of phase transitions in complex patterns: the case of the Gray-Scott reaction–diffusion model

    NASA Astrophysics Data System (ADS)

    Har-Shemesh, Omri; Quax, Rick; Hoekstra, Alfons G.; Sloot, Peter M. A.

    2016-04-01

    The Fisher–Rao metric from information geometry is related to phase transition phenomena in classical statistical mechanics. Several studies propose to extend the use of information geometry to study more general phase transitions in complex systems. However, it is unclear whether the Fisher–Rao metric does indeed detect these more general transitions, especially in the absence of a statistical model. In this paper we study the transitions between patterns in the Gray-Scott reaction–diffusion model using Fisher information. We describe the system by a probability density function that represents the size distribution of blobs in the patterns and compute its Fisher information with respect to changing the two rate parameters of the underlying model. We estimate the distribution non-parametrically so that we do not assume any statistical model. The resulting Fisher map can be interpreted as a phase-map of the different patterns. Lines with high Fisher information can be considered as boundaries between regions of parameter space where patterns with similar characteristics appear. These lines of high Fisher information can be interpreted as phase transitions between complex patterns.

  19. 77 FR 46748 - Notice of Proposed Information Collection Requests; Institute of Education Sciences; Impact...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-06

    ... in response to this notice will be considered public records. Title of Collection: Impact Evaluation... Notice of Proposed Information Collection Requests; Institute of Education Sciences; Impact Evaluation of Teacher and Leader Evaluation Systems SUMMARY: This study provides important implementation and...

  20. 78 FR 2379 - Agency Information Collection Activities; Comment Request; Impact Evaluation of Math Professional...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-11

    ... Agency Information Collection Activities; Comment Request; Impact Evaluation of Math Professional... of Collection: Impact Evaluation of Math Professional Development. OMB Control Number: 1850-NEW. Type..., and teachers for a study of math professional development. The study will provide...

  1. Impact of Information based Classification on Network Epidemics.

    PubMed

    Mishra, Bimal Kumar; Haldar, Kaushik; Sinha, Durgesh Nandini

    2016-01-01

    Formulating mathematical models for accurate approximation of malicious propagation in a network is a difficult process because of our inherent lack of understanding of several underlying physical processes that intrinsically characterize the broader picture. The aim of this paper is to understand the impact of available information in the control of malicious network epidemics. A 1-n-n-1 type differential epidemic model is proposed, where the differentiality allows a symptom based classification. This is the first such attempt to add such a classification into the existing epidemic framework. The model is incorporated into a five class system called the DifEpGoss architecture. Analysis reveals an epidemic threshold, based on which the long-term behavior of the system is analyzed. In this work three real network datasets with 22002, 22469 and 22607 undirected edges respectively, are used. The datasets show that classification based prevention given in the model can have a good role in containing network epidemics. Further simulation based experiments are used with a three category classification of attack and defense strengths, which allows us to consider 27 different possibilities. These experiments further corroborate the utility of the proposed model. The paper concludes with several interesting results. PMID:27329348

  2. The Impact of Health Information Exchange on Health Outcomes

    PubMed Central

    Hincapie, A.; Warholak, T.

    2011-01-01

    Background and Objective Healthcare professionals, industry and policy makers have identified Health Information Exchange (HIE) as a solution to improve patient safety and overall quality of care. The potential benefits of HIE on healthcare have fostered its implementation and adoption in the United States. However,there is a dearth of publications that demonstrate HIE effectiveness. The purpose of this review was to identify and describe evidence of HIE impact on healthcare outcomes. Methods A database search was conducted. The inclusion criteria included original investigations in English that focused on a HIE outcome evaluation. Two independent investigators reviewed the articles. A qualitative coding approach was used to analyze the data. Results Out of 207 abstracts retrieved, five articles met the inclusion criteria. Of these, 3 were randomized controlled trials, 1 involved retrospective review of data, and 1 was a prospective study. We found that HIE benefits on healthcare outcomes are still sparsely evaluated, and that among the measurements used to evaluate HIE healthcare utilization is the most widely used. Conclusions Outcomes evaluation is required to give healthcare providers and policy-makers evidence to incorporate in decision-making processes. This review showed a dearth of HIE outcomes data in the published peer reviewed literature so more research in this area is needed. Future HIE evaluations with different levels of interoperability should incorporate a framework that allows a detailed examination of HIE outcomes that are likely to positively affect care. PMID:23616891

  3. Impact of Information based Classification on Network Epidemics

    NASA Astrophysics Data System (ADS)

    Mishra, Bimal Kumar; Haldar, Kaushik; Sinha, Durgesh Nandini

    2016-06-01

    Formulating mathematical models for accurate approximation of malicious propagation in a network is a difficult process because of our inherent lack of understanding of several underlying physical processes that intrinsically characterize the broader picture. The aim of this paper is to understand the impact of available information in the control of malicious network epidemics. A 1-n-n-1 type differential epidemic model is proposed, where the differentiality allows a symptom based classification. This is the first such attempt to add such a classification into the existing epidemic framework. The model is incorporated into a five class system called the DifEpGoss architecture. Analysis reveals an epidemic threshold, based on which the long-term behavior of the system is analyzed. In this work three real network datasets with 22002, 22469 and 22607 undirected edges respectively, are used. The datasets show that classification based prevention given in the model can have a good role in containing network epidemics. Further simulation based experiments are used with a three category classification of attack and defense strengths, which allows us to consider 27 different possibilities. These experiments further corroborate the utility of the proposed model. The paper concludes with several interesting results.

  4. Impact of Information based Classification on Network Epidemics

    PubMed Central

    Mishra, Bimal Kumar; Haldar, Kaushik; Sinha, Durgesh Nandini

    2016-01-01

    Formulating mathematical models for accurate approximation of malicious propagation in a network is a difficult process because of our inherent lack of understanding of several underlying physical processes that intrinsically characterize the broader picture. The aim of this paper is to understand the impact of available information in the control of malicious network epidemics. A 1-n-n-1 type differential epidemic model is proposed, where the differentiality allows a symptom based classification. This is the first such attempt to add such a classification into the existing epidemic framework. The model is incorporated into a five class system called the DifEpGoss architecture. Analysis reveals an epidemic threshold, based on which the long-term behavior of the system is analyzed. In this work three real network datasets with 22002, 22469 and 22607 undirected edges respectively, are used. The datasets show that classification based prevention given in the model can have a good role in containing network epidemics. Further simulation based experiments are used with a three category classification of attack and defense strengths, which allows us to consider 27 different possibilities. These experiments further corroborate the utility of the proposed model. The paper concludes with several interesting results. PMID:27329348

  5. Final environmental impact assessment of the Paducah Gaseous Diffusion Plant site, Paducah, Kentucky

    SciTech Connect

    Not Available

    1982-08-01

    This document considers: the need for uranium enrichment facilities; site location; plant description; and describes the power generating facilities in light of its existing environment. The impacts from continuing operations are compared with alternatives of shutdown, relocation, and alternative power systems. (PSB)

  6. A more informative estimation procedure for the parameters of a diffusion process

    NASA Astrophysics Data System (ADS)

    Basso, A.; Pianca, P.

    1999-07-01

    The estimation procedures for the parameters of a diffusion process with constant coefficients have mainly focused on volatility. Nevertheless, even if the knowledge of the volatility alone suffices to compute the Black and Scholes option prices, other financial application models assume that the price dynamics follows a log-normal process and requires the knowledge of both parameters. On the other hand, while the usual ML estimator of volatility gives satisfactory results, the estimation of drift is much less accurate; moreover, the drift-estimated value highly depends on the phases of the business cycle included in the sample data. This contribution explicitly imposes a risk aversion or risk neutral assumption into the ML estimation procedure and makes a constrained maximization of the sample likelihood function. The aim is twofold: to obtain estimated values which are consistent with a widely accepted assumption and use the risk aversion constraint in order to improve the accuracy of the estimates.

  7. Diffusion in liquid metal systems. [information on electrical resistivity and thermal conductivity

    NASA Technical Reports Server (NTRS)

    Ukanwa, A. O.

    1975-01-01

    Physical properties of twenty liquid metals are reported; some of the data on such liquid metal properties as density, electrical resistivity, thermal conductivity, and heat capacity are summarized in graphical form. Data on laboratory handling and safety procedure are summarized for each metal; heat-transfer-correlations for liquid metals under various conditions of laminar and turbulent flow are included. Where sufficient data were available, temperature equations of properties were obtained by the method of least-squares fit. All values of properties given are valid in the given liquid phase ranges only. Additional tabular data on some 40 metals are reported in the appendix. Included is a brief description of experiments that were performed to investigate diffusion in liquid indium-gallium systems.

  8. Microstructural parameter estimation in vivo using diffusion MRI and structured prior information

    PubMed Central

    Nagy, Zoltan; Weiskopf, Nikolaus; Alexander, Daniel C.; Clark, Chris A.

    2015-01-01

    Purpose Diffusion MRI has recently been used with detailed models to probe tissue microstructure. Much of this work has been performed ex vivo with powerful scanner hardware, to gain sensitivity to parameters such as axon radius. By contrast, performing microstructure imaging on clinical scanners is extremely challenging. Methods We use an optimized dual spin‐echo diffusion protocol, and a Bayesian fitting approach, to obtain reproducible contrast (histogram overlap of up to 92%) in estimated maps of axon radius index in healthy adults at a modest, widely‐available gradient strength (35 mT m −1). A key innovation is the use of influential priors. Results We demonstrate that our priors can improve precision in axon radius estimates—a 7‐fold reduction in voxelwise coefficient of variation in vivo—without significant bias. Our results may reflect true axon radius differences between white matter regions, but this interpretation should be treated with caution due to the complexity of the tissue relative to our model. Conclusions Some sensitivity to relatively large axons (3–15 μm) may be available at clinical field and gradient strengths. Future applications at higher gradient strength will benefit from the favorable eddy current properties of the dual spin‐echo sequence, and greater precision available with suitable priors. Magn Reson Med, 2015. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Magn Reson Med 75:1787–1796, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance. PMID:25994918

  9. NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 12: The diffusion of federally funded aerospace Research and Development (R&D) and the information seeking behavior of US aerospace engineers and scientists

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Kennedy, John M.; Barclay, Rebecca O.

    1991-01-01

    The present exploration of the diffusion of federally-funded R&D via the information-seeking behavior of scientists and engineers proceeds under three assumptions: (1) that knowledge transfer and utilization is as important as knowledge production; (2) that the diffusion of knowledge obtained through federally-funded R&D is necessary for the maintenance of U.S. preeminence in the aerospace field; and (3) that federally-funded NASA and DoD technical reports play an important, albeit as-yet undefined, role in aerospace R&D diffusion. A conceptual model is presented for the process of knowledge diffusion that stresses the role of U.S. government-funded technical reports.

  10. Impact of one-layer assumption on diffuse reflectance spectroscopy of skin

    NASA Astrophysics Data System (ADS)

    Hennessy, Ricky; Markey, Mia K.; Tunnell, James W.

    2015-02-01

    Diffuse reflectance spectroscopy (DRS) can be used to noninvasively measure skin properties. To extract skin properties from DRS spectra, you need a model that relates the reflectance to the tissue properties. Most models are based on the assumption that skin is homogenous. In reality, skin is composed of multiple layers, and the homogeneity assumption can lead to errors. In this study, we analyze the errors caused by the homogeneity assumption. This is accomplished by creating realistic skin spectra using a computational model, then extracting properties from those spectra using a one-layer model. The extracted parameters are then compared to the parameters used to create the modeled spectra. We used a wavelength range of 400 to 750 nm and a source detector separation of 250 μm. Our results show that use of a one-layer skin model causes underestimation of hemoglobin concentration [Hb] and melanin concentration [mel]. Additionally, the magnitude of the error is dependent on epidermal thickness. The one-layer assumption also causes [Hb] and [mel] to be correlated. Oxygen saturation is overestimated when it is below 50% and underestimated when it is above 50%. We also found that the vessel radius factor used to account for pigment packaging is correlated with epidermal thickness.

  11. Diffuse gamma-ray constraints on dark matter revisited I: the impact of subhalos

    SciTech Connect

    Blanchet, Steve; Lavalle, Julien E-mail: lavalle@in2p3.fr

    2012-11-01

    We make a detailed analysis of the indirect diffuse gamma-ray signals from dark matter annihilation in the Galaxy. We include the prompt emission, as well as the emission from inverse Compton scattering whenever the annihilation products contain light leptons. We consider both the contribution from the smooth dark matter halo and that from substructures. The main parameters for the latter are the mass function index and the minimal subhalo mass. We use recent results from N-body simulations to set the most reasonable range of parameters, and find that the signal can be boosted by a factor ranging from 2 to 15 towards the Galactic poles, slightly more towards the Galactic anticenter, with an important dependence on the subhalo mass index. This uncertainty is however much less than that of the extragalactic signal studied in the literature. We derive upper bounds on the dark matter annihilation cross section using the isotropic gamma-ray emission measured by Fermi-LAT, for two directions in the sky, the Galactic anticenter and the Galactic pole(s). The former represents the lowest irreducible signal from dark matter annihilation, and the latter is robust as the astrophysical background, dominated by the hadronic contribution, is rather well established in that direction. Finally, we show how the knowledge of the minimal subhalo mass, which formally depends on the dark matter particle interactions with normal matter, can be used to derive the mass function index.

  12. 76 FR 43264 - Proposed Information Collection; Comment Request; NIST MEP Client Impact Survey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-20

    ... National Institute of Standards and Technology Proposed Information Collection; Comment Request; NIST MEP Client Impact Survey AGENCY: National Institute of Standards and Technology (NIST), Commerce. ACTION...@nist.gov . SUPPLEMENTARY INFORMATION: I. Abstract Sponsored by the National Institute of Standards...

  13. Integrative analysis of diffusion-weighted MRI and genomic data to inform treatment of glioblastoma.

    PubMed

    Jajamovich, Guido H; Valiathan, Chandni R; Cristescu, Razvan; Somayajula, Sangeetha

    2016-09-01

    Gene expression profiling from glioblastoma (GBM) patients enables characterization of cancer into subtypes that can be predictive of response to therapy. An integrative analysis of imaging and gene expression data can potentially be used to obtain novel biomarkers that are closely associated with the genetic subtype and gene signatures and thus provide a noninvasive approach to stratify GBM patients. In this retrospective study, we analyzed the expression of 12,042 genes for 558 patients from The Cancer Genome Atlas (TCGA). Among these patients, 50 patients had magnetic resonance imaging (MRI) studies including diffusion weighted (DW) MRI in The Cancer Imaging Archive (TCIA). We identified the contrast enhancing region of the tumors using the pre- and post-contrast T1-weighted MRI images and computed the apparent diffusion coefficient (ADC) histograms from the DW-MRI images. Using the gene expression data, we classified patients into four molecular subtypes, determined the number and composition of genes modules using the gap statistic, and computed gene signature scores. We used logistic regression to find significant predictors of GBM subtypes. We compared the predictors for different subtypes using Mann-Whitney U tests. We assessed detection power using area under the receiver operating characteristic (ROC) analysis. We computed Spearman correlations to determine the associations between ADC and each of the gene signatures. We performed gene enrichment analysis using Ingenuity Pathway Analysis (IPA). We adjusted all p values using the Benjamini and Hochberg method. The mean ADC was a significant predictor for the neural subtype. Neural tumors had a significantly lower mean ADC compared to non-neural tumors ([Formula: see text]), with mean ADC of [Formula: see text] and [Formula: see text] for neural and non-neural tumors, respectively. Mean ADC showed an area under the ROC of 0.75 for detecting neural tumors. We found eight gene modules in the GBM cohort. The

  14. Impact of Selection and Demography on the Diffusion of Lactase Persistence

    PubMed Central

    Currat, Mathias; Sanchez-Mazas, Alicia

    2009-01-01

    Background The lactase enzyme allows lactose digestion in fresh milk. Its activity strongly decreases after the weaning phase in most humans, but persists at a high frequency in Europe and some nomadic populations. Two hypotheses are usually proposed to explain the particular distribution of the lactase persistence phenotype. The gene-culture coevolution hypothesis supposes a nutritional advantage of lactose digestion in pastoral populations. The calcium assimilation hypothesis suggests that carriers of the lactase persistence allele(s) (LCT*P) are favoured in high-latitude regions, where sunshine is insufficient to allow accurate vitamin-D synthesis. In this work, we test the validity of these two hypotheses on a large worldwide dataset of lactase persistence frequencies by using several complementary approaches. Methodology We first analyse the distribution of lactase persistence in various continents in relation to geographic variation, pastoralism levels, and the genetic patterns observed for other independent polymorphisms. Then we use computer simulations and a large database of archaeological dates for the introduction of domestication to explore the evolution of these frequencies in Europe according to different demographic scenarios and selection intensities. Conclusions Our results show that gene-culture coevolution is a likely hypothesis in Africa as high LCT*P frequencies are preferentially found in pastoral populations. In Europe, we show that population history played an important role in the diffusion of lactase persistence over the continent. Moreover, selection pressure on lactase persistence has been very high in the North-western part of the continent, by contrast to the South-eastern part where genetic drift alone can explain the observed frequencies. This selection pressure increasing with latitude is highly compatible with the calcium assimilation hypothesis while the gene-culture coevolution hypothesis cannot be ruled out if a positively

  15. Impacts from PCB accumulation on amphibians inhabiting streams flowing from the Paducah Gaseous Diffusion Plant.

    PubMed

    DeGarady, C J; Halbrook, R S

    2003-11-01

    Contamination at the Paducah Gaseous Diffusion Plant (PGDP), Paducah, Kentucky, has been under evaluation for many years. We studied amphibians in selected outfalls (drainage ditches) flowing from the PGDP to determine if PCBs were accumulating in their tissues and how this might affect local populations. We determined relative amphibian species richness and abundance among seven outfalls and three reference streams by listening to their calls during audio surveys. We also captured amphibians from each study site during the summers of 2000 and 2001 and analyzed their carcasses for PCBs (Aroclor 1260 and 34 congeners) and livers for ethoxyresorufin O-deethylase (EROD) activity, a biomarker of PCBs and other organic contamination. Ten species were heard across study sites, and abundance and richness at outfalls were similar to those observed at reference sites. However, there were significant differences in abundance (p = 0.001) and richness (p = 0.048) of amphibians between continuously flowing and intermittent outfalls. There were no significant differences in PCB concentrations (p = 0.113) in amphibians captured from study sites, although Aroclor 1260 concentrations tended to be higher in amphibians collected from one outfall (outfall 12) on the east side of the plant (x = 1260 microg/kg) compared with all other study sites (x = 489 microg/kg). EROD activity measured in the liver was not indicative of Aroclor 1260 concentrations in amphibians at the PGDP, and EROD did not differ by study site, species, age class, or gender. PCB concentrations measured in amphibians at the PGDP were similar to concentrations measured at reference sites and did not appear to negatively affect individual amphibians or abundance and richness. PMID:14708669

  16. Replacement of chlorofluorocarbons (CFCs) at the DOE Gaseous Diffusion Plants: An assessment of global impacts

    SciTech Connect

    Socolof, M.L.; Saylor, R.E.; McCold, L.N.

    1994-12-31

    The US Department of Energy (DOE) operates two uranium enrichment plants. Together, the two plants maintain an inventory of approximately 14 million pounds of a chlorofluorocarbon (CFC), dichlorote-trafluoroethane (CFC-114) as a coolant. Annual operational CFC-114 losses total over 500,000 pounds. In February, 1992, President Bush announced that the US would terminate manufacture and importation of Class 1 ozone depleting substances (including CFC-114) by the end of 1995. To comply with this requirement DOE has considered introducing a replacement coolant by the end of 1995. Two perfluorocarbons (PFCs) - namely, octofluoro-cyclobutane and decafluorobutane - are presently the only known coolants that could meet safety requirements. They would not contribute to stratospheric ozone depletion but contribute to global warming. The paper describes an analysis of the potential global impacts of the proposed replacement of CFC-114 with a PFC. A problem with analyses of global warming and ozone depletion impacts is that even large sources of compounds that contribute to these effects contribute only very small fractions of the total effect. The authors take the position that significant effects to global warming and ozone depletion have already occurred, and that any additional contribution to these effects are contributions to cumulatively significant adverse effects on the environment. The paper describes four alternatives and the extent to which each would contribute to global warming and ozone depletion.

  17. Impacts of the climate change on runoff and diffuse phosphorus load to Lake Balaton (Hungary).

    PubMed

    Kovács, A; Clement, A

    2009-01-01

    The paper outlines a multi-component assessment of the impacts of the climate change on runoff and total phosphorus loads to the large shallow Lake Balaton in Hungary. Present hydrological cycle of the lake catchment has been examined using the rainfall-runoff model WetSpa. Particular phosphorus concentration in runoff was estimated on the basis of the simulated streamflow using an empirical power equation. Dissolved phosphorus concentrations were determined as a function of landuse and soil type of the corresponding sub-catchment. The model was calibrated and validated against daily observations manually at monitoring sites of sixteen inflowing streams around the lake. Runoff stemming from shoreline urban developments was calculated by the urban runoff simulation model SWMM. Phosphorus concentrations in urban runoff were calculated by an empirical relationship derived from field measurements. The model was henceforward run for climate change scenario analysis. Present weather data were modified by the climate change scenarios imported from the results of the CLIME project. The results indicate that the impact of the climate change on runoff and phosphorus load appears in the change of the distribution within a time period rather than in the total volume. However, due to the high uncertainties in climate models, the presented calculations are possible assumptions rather than established statements. PMID:19213995

  18. NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 5: Aerospace librarians and technical information specialists as information intermediaries: A report of phase 2 activities of the NASA/DOD Aerospace Knowledge Diffusion Research Project

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Kennedy, John M.

    1990-01-01

    The flow of U.S. government-funded and foreign scientific and technical information (STI) through libraries and related facilities to users in government and industry is examined, summarizing preliminary results of Phase 2 of the NASA/DOD Aerospace Knowledge Diffusion Research Project (NAKDRP). The design and objectives of NAKDRP are reviewed; the NAKDRP model of STI transfer among producers, STI intermediaries, surrogates (technical report repositories or clearinghouses), and users is explained and illustrated with diagrams; and particular attention is given to the organization and operation of aerospace libraries. In a survey of North American libraries it was found that 25-30 percent of libraries regularly receive technical reports from ESA and the UK; the corresponding figures for Germany and for France, Sweden, and Japan are 18 and 5 percent, respectively. Also included is a series of bar graphs showing the librarians' assessments of the quality and use of NASA Technical Reports.

  19. The diffusion of microfinance.

    PubMed

    Banerjee, Abhijit; Chandrasekhar, Arun G; Duflo, Esther; Jackson, Matthew O

    2013-07-26

    To study the impact of the choice of injection points in the diffusion of a new product in a society, we developed a model of word-of-mouth diffusion and then applied it to data on social networks and participation in a newly available microfinance loan program in 43 Indian villages. Our model allows us to distinguish information passing among neighbors from direct influence of neighbors' participation decisions, as well as information passing by participants versus nonparticipants. The model estimates suggest that participants are seven times as likely to pass information compared to informed nonparticipants, but information passed by nonparticipants still accounts for roughly one-third of eventual participation. An informed household is not more likely to participate if its informed friends participate. We then propose two new measures of how effective a given household would be as an injection point. We show that the centrality of the injection points according to these measures constitutes a strong and significant predictor of eventual village-level participation. PMID:23888042

  20. Assessment of climate change impacts on diffuse nutrient and pesticide fluxes at the watershed scale

    NASA Astrophysics Data System (ADS)

    Arabi, M.; Records, R.; Ahmadi, M.

    2012-12-01

    The study aims to assess the potential impacts of the changing climate on pollutant fluxes including sediment, phosphorus, nitrogen, and atrazine at the watershed scale over the 21st century. Specific objectives are (i) to understand changes in climatic conditions under a comprehensive set of 112 climate projections consistent with Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC-SRES) emission pathways and models; (ii) to fully enumerate and synthesize hydrologic and water quality responses to projected climate scenarios; and (iii) to investigate changes in dissolved and particulate water quality constituents. These objectives were investigated in a predominantly agricultural watershed in the Midwestern United States. The hydrologic model Soil and Water Assessment Tool (SWAT) was utilized to represent processes governing hydrology and water quality within the watershed. The SWAT model was driven with a suite of 112 distinct dynamically downscaled climate projections representing IPCC-SERES low, moderate, and high greenhouse gas emission pathways. Statistical downscaling procedures were used to derive daily climatic values for meteorological stations in the study area from grid-based dynamically downscaled monthly predictions. Predicted changes in hydroclimatic, nutrient, and pesticide fluxes under the 112 distinct simulations were then analyzed by emission pathway ensemble and characterized over early-, mid-, and late-century assessment periods (2015-2034, 2045-2064, and 2080-2099). Clear warming trends were apparent for temperature, while increases in precipitation were insignificant. Stream discharge, sediment yield, and total nutrient yields did not differ significantly between assessment periods, although atrazine yields were predicted to be slightly greater by late-century. However, the proportion of dissolved to total nutrients increased, with nitrate and soluble phosphorus yields increasing significantly between early

  1. Some Probable Technological Trends and Their Impact on an Information Network System. LINCS Project Document Series.

    ERIC Educational Resources Information Center

    Ebersole, Joseph L.

    Improvements in the technology associated with the information sciences will have their primary potential impact on the distribution of costs, information flow level, information availability, and use among information channels. This improvement implied not only a capability to perform a given function, but a lower cost. For example, the trend…

  2. A geographic information system screening tool to tackle diffuse pollution through the use of sustainable drainage systems.

    PubMed

    Todorovic, Zorica; Breton, Neil P

    2014-01-01

    Sustainable drainage systems (SUDS) offer many benefits that traditional solutions do not. Traditional approaches are unable to offer a solution to problems of flood management and water quality. Holistic consideration of the wide range of benefits from SUDS can result in advantages such as improved flood resilience and water quality enhancement through consideration of diffuse pollution sources. Using a geographical information system (GIS) approach, diffuse pollutant sources and opportunities for SUDS are easily identified. Consideration of potential SUDS locations results in source, site and regional controls, leading to improved water quality (to meet Water Framework Directive targets). The paper will discuss two different applications of the tool, the first of which is where the pollutant of interest is known. In this case the outputs of the tool highlight and isolate the areas contributing the pollutants and suggest the adequate SUDS measures to meet the required criteria. The second application is where the tool identifies likely pollutants at a receiving location, and SUDS measures are proposed to reduce pollution with assessed efficiencies. PMID:24845322

  3. The Impact of Internet Information Resources on Research Strategies: A Case Study in Alcohol Policy Analysis.

    ERIC Educational Resources Information Center

    Johnson, Suzanne P.; Anglin, Lise; Kavanagh, Lynn T.; Greenfield, Thomas K.; Giesbrecht, Norman A.

    1999-01-01

    Examines the impact of Internet information resources on the development and adaptation of research strategies based on a study of federal alcohol control policy. Considers how Internet access affects utilization of information services within an organization, and describes measures of utilization and effectiveness for assessing the impact of…

  4. A Potential Value of Familiarity and Experience: Can Informal Fieldwork Have a Lasting Impact upon Literacy?

    ERIC Educational Resources Information Center

    Scott, Graham W.; Boyd, Margaret

    2014-01-01

    This paper demonstrates that an informal field trip can have a lasting impact upon aspects of learning in a primary school context. Specifically, we consider the longer term impact of an informal trip to a rocky shore upon scores achieved in literacy assessments taking place five months after a relevant five months after a fieldwork. Pupils…

  5. Real-Time Diffusion of Information on Twitter and the Financial Markets.

    PubMed

    Tafti, Ali; Zotti, Ryan; Jank, Wolfgang

    2016-01-01

    Do spikes in Twitter chatter about a firm precede unusual stock market trading activity for that firm? If so, Twitter activity may provide useful information about impending financial market activity in real-time. We study the real-time relationship between chatter on Twitter and the stock trading volume of 96 firms listed on the Nasdaq 100, during 193 days of trading in the period from May 21, 2012 to September 18, 2013. We identify observations featuring firm-specific spikes in Twitter activity, and randomly assign each observation to a ten-minute increment matching on the firm and a number of repeating time indicators. We examine the extent that unusual levels of chatter on Twitter about a firm portend an oncoming surge of trading of its stock within the hour, over and above what would normally be expected for the stock for that time of day and day of week. We also compare the findings from our explanatory model to the predictive power of Tweets. Although we find a compelling and potentially informative real-time relationship between Twitter activity and trading volume, our forecasting exercise highlights how difficult it can be to make use of this information for monetary gain. PMID:27504639

  6. Real-Time Diffusion of Information on Twitter and the Financial Markets

    PubMed Central

    Tafti, Ali; Zotti, Ryan; Jank, Wolfgang

    2016-01-01

    Do spikes in Twitter chatter about a firm precede unusual stock market trading activity for that firm? If so, Twitter activity may provide useful information about impending financial market activity in real-time. We study the real-time relationship between chatter on Twitter and the stock trading volume of 96 firms listed on the Nasdaq 100, during 193 days of trading in the period from May 21, 2012 to September 18, 2013. We identify observations featuring firm-specific spikes in Twitter activity, and randomly assign each observation to a ten-minute increment matching on the firm and a number of repeating time indicators. We examine the extent that unusual levels of chatter on Twitter about a firm portend an oncoming surge of trading of its stock within the hour, over and above what would normally be expected for the stock for that time of day and day of week. We also compare the findings from our explanatory model to the predictive power of Tweets. Although we find a compelling and potentially informative real-time relationship between Twitter activity and trading volume, our forecasting exercise highlights how difficult it can be to make use of this information for monetary gain. PMID:27504639

  7. Diffusion of Impact Innovations from 1973-76: Interpersonal Communication Networks Among University Professors. A Report to the Exxon Education Foundation.

    ERIC Educational Resources Information Center

    Agarwala-Rogers, Rekha; And Others

    This report presents the research findings from the second year of a continuing investigation to determine the diffusion patterns to university professors of four specific educational innovations developed by the IMPACT Program. Issues addressed include: (1) creation of a corps of secondary and tertiary receivers, (2) future adoption and…

  8. Impact of diffuse nitrate pollution sources on groundwater quality--some examples from Czechoslovakia

    SciTech Connect

    Benes, V.; Pekny, V.; Skorepa, J.; Vrba, J. )

    1989-11-01

    In several regions of Czechoslovakia with intensive agricultural production, the correlation between the amount of nitrogen fertilizer applied and the nitrate content in groundwater has been recognized. Nitrate pollution of groundwater is considered to be the most serious source of nonpoint pollution in Czechoslovakia. A program of research into the effects of farming activities on groundwater quality in Czechoslovakia is under way on experimental fields (20 to 30 hectares) and, simultaneously, in regions in which shallow, vulnerable aquifers occur. The importance of the soil organic matter's stability for maintaining the groundwater quality is emphasized. Regional investigation of the impact of farming on shallow aquifers in the fluvial deposits of the Elbe River in Bohemia has proved the hydrochemical instability and vertical hydrochemical heterogeneity of these aquifers. The WASTEN deterministic model was used for modeling the transport and transformation of various types of inorganic fertilizers. The input data is based on laboratory and field measurements. Special topics are the verification of model calculations and the time and spatial variability of input data with respect to the unsaturated zone. The research results are being used for making regional and national agro-groundwater managerial schemes more precise, as well as for decision-making.

  9. Impact of diffuse nitrate pollution sources on groundwater quality--some examples from Czechoslovakia.

    PubMed Central

    Benes, V; Pĕkný, V; Skorepa, J; Vrba, J

    1989-01-01

    In several regions of Czechoslovakia with intensive agricultural production, the correlation between the amount of nitrogen fertilizer applied and the nitrate content in groundwater has been recognized. Nitrate pollution of groundwater is considered to be the most serious source of nonpoint pollution in Czechoslovakia. A program of research into the effects of farming activities on groundwater quality in Czechoslovakia is under way on experimental fields (20 to 30 hectares) and, simultaneously, in regions in which shallow, vulnerable aquifers occur. The importance of the soil organic matter's stability for maintaining the groundwater quality is emphasized. Research based on nitrogen and organic carbon balance has shown that the restoration of a soil-groundwater system is a complicated process that usually requires changes in the extent and intensity of agricultural activities and consistent attention to the effects produced by natural conditions. Regional investigation of the impact of farming on shallow aquifers in the fluvial deposits of the Elbe River in Bohemia has proved the hydrochemical instability and vertical hydrochemical heterogeneity of these aquifers. The WASTEN deterministic model was used for modeling the transport and transformation of various types of inorganic fertilizers. The input data is based on laboratory and field measurements. Special topics are the verification of model calculations and the time and spatial variability of input data with respect to the unsaturated zone. The research results are being used for making regional and national agro-groundwater managerial schemes more precise, as well as for decision-making. PMID:2559844

  10. Derivation of particulate directional information from analysis of elliptical impact craters on LDEF

    NASA Technical Reports Server (NTRS)

    Newman, P. J.; Mackay, N.; Deshpande, S. P.; Green, S. F.; Mcdonnell, J. A. M.

    1993-01-01

    The Long Duration Exposure Facility provided a gravity gradient stabilized platform which allowed limited directional information to be derived from particle impact experiments. The morphology of impact craters on semi-infinite materials contains information which may be used to determine the direction of impact much more accurately. We demonstrate the applicability of this technique and present preliminary results of measurements from LDEF and modelling of interplanetary dust and space debris.

  11. Where Are We on the Diffusion Curve? Trends and Drivers of Primary Care Physicians’ Use of Health Information Technology

    PubMed Central

    Audet, Anne-Marie; Squires, David; Doty, Michelle M

    2014-01-01

    Objective To describe trends in primary care physicians’ use of health information technology (HIT) between 2009 and 2012, examine practice characteristics associated with greater HIT capacity in 2012, and explore factors such as delivery system and payment reforms that may affect adoption and functionality. Data We used data from the 2012 and 2009 Commonwealth Fund International Health Policy Surveys of Primary Care Physicians. The data were collected in both years by postal mail between March and July among a nationally representative sample of primary care physicians in the United States. Study Design We compared primary care physicians’ HIT capacity in 2009 and 2012. We employed multivariable logistic regression to analyze whether participating in an integrated delivery system, sharing resources and support with other practices, and being eligible for financial incentives were associated with greater HIT capacity in 2012. Principal Findings Primary care physicians’ HIT capacity has significantly expanded since 2009, although solo practices continue to lag. Practices that are part of an integrated delivery system or share resources with other practices have higher rates of electronic medical record (EMR) adoption, multifunctional HIT, electronic information exchange, and electronic access for patients. Receiving or being eligible for financial incentives is associated with greater adoption of EMRs and information exchange. Conclusions Federal efforts to increase adoption have coincided with a rapid increase in HIT capacity. Delivery system and payment reforms and federally funded extension programs could offer promising pathways for further diffusion. PMID:24358958

  12. The Wasserstein Gradient Flow of the Fisher Information and the Quantum Drift-diffusion Equation

    NASA Astrophysics Data System (ADS)

    Gianazza, Ugo; Savaré, Giuseppe; Toscani, Giuseppe

    2009-10-01

    We prove the global existence of non-negative variational solutions to the “drift diffusion” evolution equation {{partial_t} u+ div left(u{D}left(2 Δ sqrt u/sqrt u-{f}right)right)=0} under variational boundary condition. Despite the lack of a maximum principle for fourth order equations, non-negative solutions can be obtained as a limit of a variational approximation scheme by exploiting the particular structure of this equation, which is the gradient flow of the (perturbed) Fisher information functional {fancyscript F^f(u):=frac 12int left|{D} log uright|^2 {u} dx+int fu dx} with respect to the Kantorovich-Rubinstein-Wasserstein distance between probability measures. We also study long-time behavior of the solutions, proving their exponential decay to the equilibrium state g = e- V characterized by {-Δ V+frac12 left|{D} Vright|^2=f,quad int e^{-V} dx=int u0dx,} when the potential V is uniformly convex: in this case the functional {fancyscript F^f} coincides with the relative Fisher information {fancyscript F^f(u)=frac12fancyscript I(u|g)= int left|{D}log(u/g)right|^2u dx}.

  13. [Diffusing information to promote population policies based on N'Djamena's Plan of Action].

    PubMed

    Gueye, M

    1990-03-01

    From November 28-30, 1989, the Centre D'Etudes et de Recherche sur la Population pour le Developpement (CERPOD) sponsored the Selingue Retreat (SR), outside of Bamako, Mali to discuss the role of population policy development among the 9 Sahelian countries following the adoption of the N'Djamena Program of Action (PAN) the year before. The key questions discussed were: 1) state of the art regarding implementation of population policy development among Sahelian countries; 2) strategies of technical assistance to support CERPOD for population policy development; 3) organizational matters; and 4) evaluation strategies to evaluate population policy development and CERPOD's programs. The SR recommended that due to the lack of an adequate information base for population policy development that collaboration continue between CERPOD and the Futures Group. The new project will begin with a detailed plan of action for Mali and Guinee-Bissau, followed by Niger and Burkina Faso. PMID:12316538

  14. NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 57; US Scientific and Technical Information Policy

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Barclay, Rebecca O.; Kennedy, John M.

    1996-01-01

    In fiscal year 1994, the United States government spent about $68 billion for science and technology. Although there is general agreement among policy makers that the results of this expenditure can be used to enhance technological innovation and improve economic competitiveness, there is no coherent scientific and technical information (STI) policy. The absence of a cohesive policy and STI policy framework means that the transfer and utilization of STI goes uncoordinated. This chapter examines the U.S. government's role in funding science and technology, reviews Federal STI activities and involvement in the transfer and use of STI resulting from federally-funded science and technology, presents issues surrounding the use of federally-funded STI, and offers recommendations for improving the transfer and use of STI.

  15. The Impact of Information on Death Penalty Support, Revisited

    ERIC Educational Resources Information Center

    Lambert, Eric G.; Camp, Scott D.; Clarke, Alan; Jiang, Shanhe

    2011-01-01

    In 1972, former Supreme Court Justice Marshall postulated that the public was uninformed about the death penalty and information would change their support for it. There is some indication that information about the death penalty may change people's level of support. This study re-examines data used by Lambert and Clarke (2001). Using multivariate…

  16. Impacting Student Perceptions about Careers in Information Systems

    ERIC Educational Resources Information Center

    Walstrom, Kent A.; Schambach, Thomas P.

    2012-01-01

    A shortage of graduates prepared to fill the available jobs in Information Systems remains. Previous studies have verified the shortage and attempted to explain why students do not major in Information Technology related fields. Since prior studies identified lack of awareness regarding the discipline as a major reason in ignoring the major, the…

  17. Impact of NDE reliability developments on risk-informed methods

    SciTech Connect

    Walker, S.M.; Ammirato, F.V.

    1996-12-01

    Risk informed inspection procedures are being developed to more effectively and economically manage degradation in plant piping systems. A key element of this process is applying nondestructive examination (NDE) procedures capable of detecting specific damage mechanisms that may be operative in particular locations. Thus, the needs of risk informed analysis are closely coupled with a firm understanding of the capability of NDE.

  18. Informational Technology and Its Impact on American Education.

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. Office of Technology Assessment.

    This study, which examines the extent to which information technology could serve American needs for education and training, documents two basic sets of conclusions: (1) the so-called information revolution is profoundly affecting American education by changing the nature of what needs to be learned, who needs to learn it, who will provide it, and…

  19. The Impact of Social Media on Informal Learning in Museums

    ERIC Educational Resources Information Center

    Russo, Angelina; Watkins, Jerry; Groundwater-Smith, Susan

    2009-01-01

    This paper posits that social networking can take a central role in learning in informal environments such as museums, libraries and galleries. It argues that social media offers young people agency previously unavailable in informal learning environments in order to explore complex responses to and participation with cultural content. The paper…

  20. Societal Impact of Improved Environment and Geospatial Information

    NASA Astrophysics Data System (ADS)

    Pearlman, J.; Andrzejewska, M.; Stonor, T.

    2013-12-01

    Geospatial projects are often dogged by the inability to establish a strong quantitative value proposition and are unable to sustain the attention of senior decision makers. In a tough economic climate, it is particularly important that any project that requires a significant investment can show a clear Return on Investment (ROI). In the case of commerce, benefit can be quantified through increase in sales/profit or reduction of risk. In the case of societal impact, quantification is more challenging. At the Geospatial World Forum (GWF) 2013 in Rotterdam, a number of case studies were presented on social impacts which used differing approaches to impact assessment. Some of the cases discussed projects with community issues and explained alternative means of conflict resolution. However, a comparison of the different case studies was not made at the GWF meeting. This presentation will take the next step and address the commonalities and differences in the approaches.

  1. Additional information for impact response of the restart safety rods

    SciTech Connect

    Yau, W.W.F.

    1991-10-14

    WSRC-RP-91-677 studied the structural response of the safety rods under the conditions of brake failure and accidental release. It was concluded that the maximum impact loading to the safety rod is 6020 pounds based on conservative considerations that energy dissipation attributable to fluid resistance and reactor superstructure flexibility. The staffers of the Defense Nuclear Facility Safety Board reviewed the results and inquired about the extent of conservatism. By request of the RESTART team, I reassessed the impact force due to these conservative assumptions. This memorandum reports these assessments.

  2. Diffusion-Weighted MRI for Nodal Staging of Head and Neck Squamous Cell Carcinoma: Impact on Radiotherapy Planning

    SciTech Connect

    Dirix, Piet; Vandecaveye, Vincent; De Keyzer, Frederik; Op de beeck, Katya; Poorten, Vincent Vander; Delaere, Pierre; Verbeken, Eric; Hermans, Robert; Nuyts, Sandra

    2010-03-01

    Purpose: To evaluate the use of diffusion-weighted magnetic resonance imaging (DW-MRI) for nodal staging and its impact on radiotherapy (RT) planning. Methods and Materials: Twenty-two patients with locally advanced head and neck squamous cell carcinoma underwent contrast-enhanced computed tomography (CT), as well as MRI (with routine and DW sequences) prior to neck dissection. After topographic correlation, lymph nodes were evaluated microscopically with prekeratin immunostaining. Pathology results were correlated with imaging findings and an RT planning study was performed for these surgically treated patients. One set of target volumes was based on conventional imaging only, and another set was based on the corresponding DW-MRI images. A third reference set was contoured based solely on pathology results. Results: A sensitivity of 89% and a specificity of 97% per lymph node were found for DW-MRI. Nodal staging agreement between imaging and pathology was significantly stronger for DW-MRI (kappa = 0.97; 95% confidence interval [CI], 0.84-1.00) than for conventional imaging (kappa = 0.56; 95% CI, 0.16-0.96; p = 0.019, by McNemar's test). For both imaging modalities, the absolute differences between RT volumes and those obtained by pathology were calculated. Using an exact paired Wilcoxon test, the observed difference was significantly larger for conventional imaging than for DW-MRI for nodal gross tumor volume (p = 0.0013), as well as for nodal clinical target volume (p = 0.0415) delineation. Conclusions: These results suggest that DW-MRI is superior to conventional imaging for preradiotherapy nodal staging of head and neck squamous cell carcinoma, and provides a potential impact on organsparing and tumor control.

  3. The impact of health information technology on staffing.

    PubMed

    Goldsack, Jennifer C; Robinson, Edmondo J

    2014-02-01

    Hospitals nationwide must demonstrate meaningful use by 2015 or face fines. For over 20 years, researchers have attempted to assess the impact of electronic record keeping technologies on the quality, safety, and efficiency of care, but results are inconclusive and hospital managers have little evidence on which to base staffing decisions as we hurtle toward the era of the paperless hospital. PMID:24451450

  4. ASM Journals Eliminate Impact Factor Information from Journal Websites.

    PubMed

    Casadevall, Arturo; Bertuzzi, Stefano; Buchmeier, Michael J; Davis, Roger J; Drake, Harold; Fang, Ferric C; Gilbert, Jack; Goldman, Barbara M; Imperiale, Michael J; Matsumura, Philip; McAdam, Alexander J; Pasetti, Marcela F; Sandri-Goldin, Rozanne M; Silhavy, Thomas; Rice, Louis; Young, Jo-Anne H; Shenk, Thomas

    2016-01-01

    Many scientists attempt to publish their work in a journal with the highest possible journal impact factor (IF). Despite widespread condemnation of the use of journal IFs to assess the significance of published work, these numbers continue to be widely misused in publication, hiring, funding, and promotion decisions (1, 2). PMID:27408939

  5. Federal Environmental Impact Statements as an Important Source of Information.

    ERIC Educational Resources Information Center

    Orr, Patricia S.

    1995-01-01

    Examines the background and characteristics of environmental impact statements (EIS), and discusses the sources that provide bibliographic control for EISs. Explores the usefulness of EISs, outlines their legislative basis, describes the EIS process and format, and identifies sources that facilitate access to them. (Author/DGM)

  6. Untangling a crystal storm through time: how do 500 diffusion stopwatches inform our view of Eyjafjallajökull 2010?

    NASA Astrophysics Data System (ADS)

    Pankhurst, M. J.; Morgan, D. J.; Thordarson, T.; Loughlin, S.

    2014-12-01

    A new database of 500+ olivine crystal timescales from samples that encompass the duration of the 2010 Fimmvörðuháls-Eyjafjallajökull eruption is presented. We also integrate new petrologic, thermometric and barometric data to read a 4D narrative of the magmatic processes within this volcanic plumbing system preceding­­- and during- eruption. Using this perspective we can identify and semi-quantify magmatic componentry, detect new magmatic inputs, and 'watch' those crystal chemical populations age. We find that major crystal-liquid disequilibrium events occurred up to several years preceding the eruptions, and inputs fed the plumbing system during the eruption window (days - hours). We place timeframes upon processes including magma-mixing, mush remobilization and erosion, and final-ascent quenching and eruption. Fe-Mg binary diffusion in olivine modelling conducted upon this scale was made possible using new advances -also presented here- in both the gathering and processing of raw data, and extraction of timescale information. We demonstrate that this streamlined workflow can now produce statistically robust timescale data within an integrated petrologic and geochemical context that may be resolved alongside independent geophysical and other remote sensing data into a common dimension - time. Transposing petrologic information (record of past process) and geophysical observation (phenomenological in the present) into a common language is designed to produce new understanding of both active and palaeo- volcanic systems, the implications of which we discuss here using our case study as an example.

  7. Simulations of Diffusive Pb-, Ti- and REE-loss in Terrestrial and Lunar Zircon and Apatite as a Function of Impact Heating During Impact Bombardments

    NASA Astrophysics Data System (ADS)

    Abramov, O.; Mojzsis, S. J.

    2009-12-01

    Ultra-high spatial resolution ion microprobe depth-profiles of pre-3.9 Ga terrestrial zircons from the Jack Hills (Western Australia) have the potential to record a sharply elevated impactor flux to the inner planets at ca. 3.95 Ga termed the Late Heavy Bombardment (LHB). A putative signature of this is in the form of ~3.95 Ga, 2 to 4 μm mantles over the (oldest) igneous zircon cores (up to 4.3 Ga). These minute mantles show Pb-loss (up to 90% discordance) over narrow domains that could be the result of impact heating. Pre-3.9 Ga lunar zircon grains have not yet been depth-profiled, but it is evident from published spot analyses that grain cores preserve original igneous ages albeit with no clear super-imposition of later thermal events. However, the U-Pb systematics of apatites in the same lunar rocks were reset ca. 3.95 Ga. The motivation of this study is to explain the high degree of Pb (and other cation) loss over very short distances (<6 μm) in terrestrial zircons at ~3.9 Ga, the complete resetting of U-Pb isotope systematics of lunar apatites at approximately the same time, and to make predictions in preparation for depth-profile work on lunar samples. To accomplish these goals, we used existing models that simulate the thermal consequences of LHB, as well as established equations for cation diffusion in zircon and apatite. The main thermal model consists of (i) a stochastic cratering model which populates the surface with craters within constraints derived from the lunar cratering record, the size/frequency distribution of the asteroid belt, and dynamical models; (ii) analytical expressions that calculate a temperature field for each model crater; and (iii) three-dimensional thermal models of lunar and terrestrial lithospheres, where craters are allowed to cool by conduction in the subsurface and radiation at the surface. In addition, a high-resolution near-surface model was used to account for additional thermal pulses due to global deposition of hot

  8. The Impact of Variability of Item Parameter Estimators on Test Information Function

    ERIC Educational Resources Information Center

    Zhang, Jinming

    2012-01-01

    The impact of uncertainty about item parameters on test information functions is investigated. The information function of a test is one of the most important tools in item response theory (IRT). Inaccuracy in the estimation of test information can have substantial consequences on data analyses based on IRT. In this article, the major part (called…

  9. Designing-and Redesigning-Information Services for Maximum Impact.

    ERIC Educational Resources Information Center

    Jones, Rebecca; Dysart, Jane

    2002-01-01

    Discusses innovative information services, including new services and the redesign of existing services. Describes the development process, including assessing the market and developing a marketing plan; and explains the implementation process, including monitoring client satisfaction and quality control. (LRW)

  10. Assessing the socioeconomic impact and value of open geospatial information

    USGS Publications Warehouse

    Pearlman, Francoise; Pearlman, Jay; Bernknopf, Richard; Coote, Andrew; Craglia, Massimo; Friedl, Lawrence; Gallo, Jason; Hertzfeld, Henry; Jolly, Claire; Macauley, Molly; Shapiro, Carl; Smart, Alan

    2016-01-01

    The workshop included 68 participants coming from international organizations, the U.S. public and private sectors, nongovernmental organizations, and academia. Participants included policy makers and analysts, financial analysts, economists, information scientists, geospatial practitioners, and other discipline experts.