WorldWideScience

Sample records for dependent electronic resource

  1. Resource Abundance and Resource Dependence in China

    NARCIS (Netherlands)

    Ji, K.; Magnus, J.R.; Wang, W.

    2010-01-01

    This paper reconsiders the ‘curse of resources’ hypothesis for the case of China, and distinguishes between resource abundance, resource rents, and resource dependence. Resource abundance and resource rents are shown to be approximately equivalent, and their association with resource dependence vari

  2. Selection of Electronic Resources.

    Science.gov (United States)

    Weathers, Barbara

    1998-01-01

    Discusses the impact of electronic resources on collection development; selection of CD-ROMs, (platform, speed, video and sound, networking capability, installation and maintenance); selection of laser disks; and Internet evaluation (accuracy of content, authority, objectivity, currency, technical characteristics). Lists Web sites for evaluating…

  3. Green Supply Chain Collaboration for Fashionable Consumer Electronics Products under Third-Party Power Intervention—A Resource Dependence Perspective

    Directory of Open Access Journals (Sweden)

    Jiuh-Biing Sheu

    2014-05-01

    Full Text Available Under third-party power intervention (TPPI, which increases uncertainty in task environments, complex channel power interplays and restructuring are indispensable among green supply chain members as they move toward sustainable collaborative relationships for increased viability and competitive advantage. From the resource dependence perspective, this work presents a novel conceptual model to investigate the influence of political and social power on channel power restructuring and induced green supply chain collaboration in brander-retailer bidirectional green supply chains of fashionable consumer electronics products (FCEPs. An FCEP refers to the consumer electronics product (e.g., personal computers, mobile phones, computer notebooks, and game consoles with the features of a well-known brand associated, a short product lifecycle, timely and fashionable design fit for market trends, and quick responsiveness to the variations of market demands. The proposed model is tested empirically using questionnaire data obtained from retailers in the FCEP brander-retailer distribution channels. Analytical results reveal that as an extension of political and social power, TPPI positively affects the reciprocal interdependence of dyadic members and reduces power asymmetry, thereby enhancing the collaborative relationship of dyadic members and leading to improved green supply chain performance. Therein, reciprocal interdependence underlying collaborative relationship is the key to reducing the external environmental uncertainties in the TPPI context.

  4. Electronic Resource Management Systems

    Directory of Open Access Journals (Sweden)

    Mark Ellingsen

    2004-10-01

    Full Text Available Computer applications which deal with electronic resource management (ERM are quite a recent development. They have grown out of the need to manage the burgeoning number of electronic resources particularly electronic journals. Typically, in the early years of e-journal acquisition, library staff provided an easy means of accessing these journals by providing an alphabetical list on a web page. Some went as far as categorising the e-journals by subject and then grouping the journals either on a single web page or by using multiple pages. It didn't take long before it was recognised that it would be more efficient to dynamically generate the pages from a database rather than to continually edit the pages manually. Of course, once the descriptive metadata for an electronic journal was held within a database the next logical step was to provide administrative forms whereby that metadata could be manipulated. This in turn led to demands for incorporating more information and more functionality into the developing application.

  5. Electronic Resource Management and Design

    Science.gov (United States)

    Abrams, Kimberly R.

    2015-01-01

    We have now reached a tipping point at which electronic resources comprise more than half of academic library budgets. Because of the increasing work associated with the ever-increasing number of e-resources, there is a trend to distribute work throughout the library even in the presence of an electronic resources department. In 2013, the author…

  6. Electronic Resource Management and Design

    Science.gov (United States)

    Abrams, Kimberly R.

    2015-01-01

    We have now reached a tipping point at which electronic resources comprise more than half of academic library budgets. Because of the increasing work associated with the ever-increasing number of e-resources, there is a trend to distribute work throughout the library even in the presence of an electronic resources department. In 2013, the author…

  7. Analysis on Current Situation and Countermeasure of Domestic Electronic Commerce Logistics in the Internet Age——Based on Resource Dependence Theory

    Directory of Open Access Journals (Sweden)

    Zhang Jiapeng

    2017-01-01

    Full Text Available This paper analyzes the status of electric business logistics in the current Internet era in China, and combines the SWOT analysis with AHP to do the empirical analysis, then puts forward the countermeasure that the electric business logistics resource should be shared based on the resource dependence theory. Through the empirical analysis, it is found that the disadvantages and opportunities of the logistics status are important in the Internet era.The resource sharing strategy based on the resource dependence theory is more scientific. The rational use of Internet technology in electric business logistics industry can achieve “sharing”. It is of great significance for its balanced development, intelligent development and optimization and development.

  8. Managing electronic resources a LITA guide

    CERN Document Server

    Weir, Ryan O

    2012-01-01

    Informative, useful, current, Managing Electronic Resources: A LITA Guide shows how to successfully manage time, resources, and relationships with vendors and staff to ensure personal, professional, and institutional success.

  9. Electronic resource management systems a workflow approach

    CERN Document Server

    Anderson, Elsa K

    2014-01-01

    To get to the bottom of a successful approach to Electronic Resource Management (ERM), Anderson interviewed staff at 11 institutions about their ERM implementations. Among her conclusions, presented in this issue of Library Technology Reports, is that grasping the intricacies of your workflow-analyzing each step to reveal the gaps and problems-at the beginning is crucial to selecting and implementing an ERM. Whether the system will be used to fill a gap, aggregate critical data, or replace a tedious manual process, the best solution for your library depends on factors such as your current soft

  10. Inter-organizational linkages and resource dependence

    Directory of Open Access Journals (Sweden)

    Rod B. McNaughton

    2014-12-01

    Full Text Available Few studies have examined the relationship between inter-industry, inter-corporate ownership (ICO patterns and inter-industry resource exchange patterns. Using data from Statistics Canada, this paper reveals a positive association between the degree of ICO linkages and the degree of input–output dependence among Canadian industry groups. This provides empirical support for the primary assertion of resource dependence theory: that corporations employ ICO linkages to manage their input–output dependence resulting from recurrent resource exchanges. This research differs from extant tests of resource dependence in that it uses data for the population of firms (over a size threshold in Canada and includes all forms of interdependence between enterprises. The findings suggest scenarios in which corporations can adopt ICO linkages to manage resource dependence and reduce transaction costs.

  11. Poverty and resource dependence in rural India

    Energy Technology Data Exchange (ETDEWEB)

    Narain, Urvashi [Resources for the Future,1616 P St. NW, 20036 Washington, DC (United States); Gupta, Shreekant [Department of Economics, Delhi School of Economics, University of Delhi, 110007 Delhi (India); Van ' t Veld, Klaas [University of Wyoming, Department of Economics and Finance, Dept 3985, 1000 E. University Ave, 82071 Laramie, Wyoming (United States)

    2008-05-15

    Previous studies of rural households in developing countries have tended to find that the dependence of these households on common-pool resources declines with income. Our study of households in Jhabua, India, finds a more complex relationship. Using the share of resource income in total long-run or 'permanent' income as our dependence measure - which we argue is more appropriate than the short-run income-based measure commonly used in the literature - we find that for households that collect any resources at all, dependence exhibits a U-shaped relationship with income. That is, the poorest and richest households depend more on resources than households with intermediate incomes. The poorest and richest households are also found to be least likely to collect, however, indicating that resource use at the income extremes is bimodal - either zero or above average. Moreover, the observed trends for resources as a whole are not mirrored in those for individual resources. Dependence on fuelwood and dung declines with income, for example, while dependence on fodder and construction wood increases. These findings suggest that common-pool resources are a productive source of income not just for the poor but also for the rich, and that improvements in the stocks of these resources can potentially form the basis of poverty reduction efforts in these economies. (author)

  12. Electronic Resources Management Project Presentation 2012

    KAUST Repository

    Ramli, Rindra M.

    2012-11-05

    This presentation describes the electronic resources management project undertaken by the KAUST library. The objectives of this project is to migrate information from MS Sharepoint to Millennium ERM module. One of the advantages of this migration is to consolidate all electronic resources into a single and centralized location. This would allow for better information sharing among library staff.

  13. Implementing CORAL: An Electronic Resource Management System

    Science.gov (United States)

    Whitfield, Sharon

    2011-01-01

    A 2010 electronic resource management survey conducted by Maria Collins of North Carolina State University and Jill E. Grogg of University of Alabama Libraries found that the top six electronic resources management priorities included workflow management, communications management, license management, statistics management, administrative…

  14. Implementing CORAL: An Electronic Resource Management System

    Science.gov (United States)

    Whitfield, Sharon

    2011-01-01

    A 2010 electronic resource management survey conducted by Maria Collins of North Carolina State University and Jill E. Grogg of University of Alabama Libraries found that the top six electronic resources management priorities included workflow management, communications management, license management, statistics management, administrative…

  15. Machine scheduling with resource dependent processing times

    NARCIS (Netherlands)

    Grigoriev, A.; Sviridenko, M.; Uetz, Marc Jochen

    We consider machine scheduling on unrelated parallel machines with the objective to minimize the schedule makespan. We assume that, in addition to its machine dependence, the processing time of any job is dependent on the usage of a discrete renewable resource, e.g. workers. A given amount of that

  16. Resource Letter: TE-1: Teaching electronics

    Science.gov (United States)

    Henry, Dennis C.

    2002-01-01

    This Resource Letter examines the evolution, roles, and content of courses in electronics in the undergraduate physics curriculum, and provides a guide to resources for faculty teaching such courses. It concludes with a brief section addressing problems of electromagnetic interference in electronic systems, and provides an introduction to the literature and practice of electromagnetic compatibility. I have included textbooks, reference books, articles, collections of laboratory experiments and projects, sources of equipment and parts, software packages, videos, and websites.

  17. Electronic Resources Management System: Recommendation Report 2017

    KAUST Repository

    Ramli, Rindra M.

    2017-05-01

    This recommendation report provides an overview of the selection process for the new Electronic Resources Management System. The library has decided to move away from Innovative Interfaces Millennium ERM module. The library reviewed 3 system as potential replacements namely: Proquest 360 Resource Manager, Ex Libris Alma and Open Source CORAL ERMS. After comparing and trialling the systems, it was decided to go for Proquest 360 Resource Manager.

  18. Library Training to Promote Electronic Resource Usage

    DEFF Research Database (Denmark)

    Frandsen, Tove Faber; Tibyampansha, Dativa; Ibrahim, Glory

    2017-01-01

    Purpose: Increasing the usage of electronic resources is an issue of concern for many libraries all over the world. Several studies stress the importance of information literacy and instruction in order to increase the usage. Design/methodology/approach: The present article presents the results...

  19. Reviewing the Electronic Resources & Libraries Conference

    Science.gov (United States)

    Tijerina, Bonnie

    2008-01-01

    The third Electronic Resources & Libraries (ER&L) conference gathered at Georgia Institute of Technology's Global Learning and Conference Center in Atlanta, Georgia, March 18-21, 2008. Over 360 attendees, from six countries and from 80% of the United States, represented their libraries and organizations resulting in a diverse and…

  20. Making sense of the electronic resource marketplace: trends in health-related electronic resources.

    Science.gov (United States)

    Blansit, B D; Connor, E

    1999-07-01

    Changes in the practice of medicine and technological developments offer librarians unprecedented opportunities to select and organize electronic resources, use the Web to deliver content throughout the organization, and improve knowledge at the point of need. The confusing array of available products, access routes, and pricing plans makes it difficult to anticipate the needs of users, identify the top resources, budget effectively, make sound collection management decisions, and organize the resources effectively and seamlessly. The electronic resource marketplace requires much vigilance, considerable patience, and continuous evaluation. There are several strategies that librarians can employ to stay ahead of the electronic resource curve, including taking advantage of free trials from publishers; marketing free trials and involving users in evaluating new products; watching and testing products marketed to the clientele; agreeing to beta test new products and services; working with aggregators or republishers; joining vendor advisory boards; benchmarking institutional resources against five to eight competitors; and forming or joining a consortium for group negotiating and purchasing. This article provides a brief snapshot of leading biomedical resources; showcases several libraries that have excelled in identifying, acquiring, and organizing electronic resources; and discusses strategies and trends of potential interest to biomedical librarians, especially those working in hospital settings.

  1. Generalized Orienteering Problem with Resource Dependent Rewards

    Science.gov (United States)

    2013-02-19

    Feb. 2008. [15] G. Laporte and S. Martello. The selective traveling salesman problem . Discrete Applied Math- ematics, 26:193–207, 1990. [16] H. D...the following convex NLP produces the minimum travel distance between them. Problem D δ∗i,j = min t ||(ρi + (t− τi)ui)− (ρj + (t− τj)uj)|| s.t. max...Generalized Orienteering Problem with Resource Dependent Rewards Jesse Pietz, Johannes O. Royset Operations Research Department, Naval Postgraduate

  2. Natural resource dependence, livelihoods and development: perceptions from Kiunga, Kenya.

    OpenAIRE

    Samoilys, M.A.; Kanyange, W.N.

    2008-01-01

    Numerous marine resource management initiatives have been implemented in East Africa over the last 15 years. However, success has been limited if poverty and natural resource health are used as indicators, although the capacity to manage marine resources has improved. This study seeks to map coastal peoples’ perceptions of marine resource use and their dependence on these resources, changes in resource status, and what effect conservation and natural resource management have had on coastal pe...

  3. Electronic Resource Management System. Vernetzung von Lizenzinformationen

    Directory of Open Access Journals (Sweden)

    Michaela Selbach

    2014-12-01

    Full Text Available In den letzten zehn Jahren spielen elektronische Ressourcen im Bereich der Erwerbung eine zunehmend wichtige Rolle: Eindeutig lässt sich hier ein Wandel in den Bibliotheken (fort vom reinen Printbestand zu immer größeren E-Only-Beständen feststellen. Die stetig wachsende Menge an E-Ressourcen und deren Heterogenität stellt Bibliotheken vor die Herausforderung, die E-Ressourcen effizient zu verwalten. Nicht nur Bibliotheken, sondern auch verhandlungsführende Institutionen von Konsortial- und Allianzlizenzen benötigen ein geeignetes Instrument zur Verwaltung von Lizenzinformationen, welches den komplexen Anforderungen moderner E-Ressourcen gerecht wird. Die Deutsche Forschungsgemeinschaft (DFG unterstützt ein Projekt des Hochschulbibliothekszentrums des Landes Nordrhein-Westfalen (hbz, der Universitätsbibliothek Freiburg, der Verbundzentrale des Gemeinsamen Bibliotheksverbundes (GBV und der Universitätsbibliothek Frankfurt, in dem ein bundesweit verfügbares Electronic Ressource Managementsystem (ERMS aufgebaut werden soll. Ein solches ERMS soll auf Basis einer zentralen Knowledge Base eine einheitliche Nutzung von Daten zur Lizenzverwaltung elektronischer Ressourcen auf lokaler, regionaler und nationaler Ebene ermöglichen. Statistische Auswertungen, Rechteverwaltung für alle angeschlossenen Bibliotheken, kooperative Datenpflege sowie ein über standardisierte Schnittstellen geführter Datenaustausch stehen bei der Erarbeitung der Anforderungen ebenso im Fokus wie die Entwicklung eines Daten- und Funktionsmodells. In the last few years the importance of electronic resources in library acquisitions has increased significantly. There has been a shift from mere print holdings to both e- and print combinations and even e-only subscriptions. This shift poses a double challenge for libraries: On the one hand they have to provide their e-resource collections to library users in an appealing way, on the other hand they have to manage these

  4. Utilization of electronic information resources by academic staff at ...

    African Journals Online (AJOL)

    Utilization of electronic information resources by academic staff at Makerere University. ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search ... It examined the academic staff awareness of the resources available, the types ...

  5. Effectiveness Analysis of Electronic Resources at the Hacettepe University

    OpenAIRE

    2011-01-01

    It is important to collect and analyze the usage data of electronic databases and periodicals in order to make policies regarding the composition, improvement and more extensive utilization of electronic resources of libraries. The aim of this study is to investigate how efficiently the full text accessible electronic resources of Hacettepe University Libraries are used. For this purpose the usage data obtained from COUNTER Software regarding the electronic databases to which Hacettepe Univer...

  6. The Study of Analytical Model of Library Electronic Resources Usage-A Case of Medical Electronic Resources

    OpenAIRE

    Chung-Yen Yu; Jiann-Cherng Shieh

    2014-01-01

    With the advents of internet, the importance of electronic resources is growing. Due to the increasing expensiveness of electronic resources, university libraries normally received budgets from parent institutions annually. They necessarily applied effective and systematic methods for decision making in electronic resources purchase or re-subscription. However, there are some difficulties in practices: First of all, libraries are unable to receive user records; second, the COUNTER statistics ...

  7. The Role of the Acquisitions Librarian in Electronic Resources Management

    Science.gov (United States)

    Pomerantz, Sarah B.

    2010-01-01

    With the ongoing shift to electronic formats for library resources, acquisitions librarians, like the rest of the profession, must adapt to the rapidly changing landscape of electronic resources by keeping up with trends and mastering new skills related to digital publishing, technology, and licensing. The author sought to know what roles…

  8. Electronic resources preferred by pediatric hospitalists for clinical care.

    Science.gov (United States)

    Beck, Jimmy B; Tieder, Joel S

    2015-10-01

    There is little research on pediatric hospitalists' use of evidence-based resources. The aim of this study was to determine the electronic resources that pediatric hospitalists prefer. Using a web-based survey, the authors determined hospitalists' preferred electronic resources, as well as their attitudes toward lifelong learning, practice, and experience characteristics. One hundred sixteen hospitalists completed the survey. The most preferred resource for general information, patient handouts, and treatment was UpToDate. Online search engines were ranked second for general information and patient handouts. Pediatric hospitalists tend to utilize less rigorous electronic resources such as UpToDate and Google. These results can set a platform for discussing the quality of resources that pediatric hospitalists use.

  9. Natural Resources and Violent Conflict: Resource Abundance, Dependence and the Onset of Civil Wars

    NARCIS (Netherlands)

    Brunnschweiler, C.N.; Bulte, E.H.

    2009-01-01

    In this paper we examine the claim that natural resources invite civil conflict, and challenge the main stylized facts in this literature. We find that the conventional measure of resource dependence is endogenous with respect to conflict, and that instrumenting for dependence implies that it is no

  10. Unusual distance dependences of electron transfer rates.

    Science.gov (United States)

    Kuss-Petermann, Martin; Wenger, Oliver S

    2016-07-28

    Usually the rates for electron transfer (kET) decrease with increasing donor-acceptor distance, but Marcus theory predicts a regime in which kET is expected to increase when the transfer distance gets longer. Until recently, experimental evidence for such counter-intuitive behavior had been very limited, and consequently this effect is much less well-known than the Gaussian free energy dependence of electron transfer rates leading to the so-called inverted driving-force effect. This article presents the theoretical concepts that lead to the prediction of electron transfer rate maxima at large donor-acceptor distances, and it discusses conditions that are expected to favor experimental observations of such behavior. It continues with a consideration of specific recent examples in which electron transfer rates were observed to increase with increasing donor-acceptor distance, and it closes with a discussion of the importance of this effect in the context of light-to-chemical energy conversion.

  11. Cataloging and Indexing of Electronic Information Resources

    Science.gov (United States)

    2003-04-01

    digital library, but it facilitates the exchange of these objects among digital libraries . METS provides an XML DTD that can point to metadata in other...International Federation of Library Associations and Institutions (IFLA). (2002). Digital Libraries : Metadata Resources. Retrieved May 3, 2002 from the

  12. Adoption and use of electronic information resources by medical ...

    African Journals Online (AJOL)

    ... were analysed with descriptive Statistics(Simple percentage and frequency count). ... for doing assignment, Google search, for personal development, and getting ... major problems encountered when using electronic Information Resources.

  13. Euler European Libraries and Electronic Resources in Mathematical Sciences

    CERN Document Server

    The Euler Project. Karlsruhe

    The European Libraries and Electronic Resources (EULER) Project in Mathematical Sciences provides the EulerService site for searching out "mathematical resources such as books, pre-prints, web-pages, abstracts, proceedings, serials, technical reports preprints) and NetLab (for Internet resources), this outstanding engine is capable of simple, full, and refined searches. It also offers a browse option, which responds to entries in the author, keyword, and title fields. Further information about the Project is provided at the EULER homepage.

  14. Building an electronic resource collection a practical guide

    CERN Document Server

    Lee, Stuart D

    2004-01-01

    This practical book guides information professionals step-by-step through building and managing an electronic resource collection. It outlines the range of electronic products currently available in abstracting and indexing, bibliographic, and other services and then describes how to effectively select, evaluate and purchase them.

  15. Attentional resource allocation in visuotactile processing depends on the task, but optimal visuotactile integration does not depend on attentional resources

    Directory of Open Access Journals (Sweden)

    Basil eWahn

    2016-03-01

    Full Text Available Humans constantly process and integrate sensory input from multiple sensory modalities. However, the amount of input that can be processed is constrained by limited attentional resources. A matter of ongoing debate is whether attentional resources are shared across sensory modalities, and whether multisensory integration is dependent on attentional resources. Previous research suggested that the distribution of attentional resources across sensory modalities depends on the the type of tasks. Here, we tested a novel task combination in a dual task paradigm: Participants performed a self-terminated visual search task and a localization task in either separate sensory modalities (i.e., haptics and vision or both within the visual modality. Tasks considerably interfered. However, participants performed the visual search task faster when the localization task was performed in the tactile modality in comparison to performing both tasks within the visual modality. This finding indicates that tasks performed in separate sensory modalities rely in part on distinct attentional resources. Nevertheless, participants integrated visuotactile information optimally in the localization task even when attentional resources were diverted to the visual search task. Overall, our findings suggest that visual search and tactile localization partly rely on distinct attentional resources, and that optimal visuotactile integration is not dependent on attentional resources.

  16. Spin dependent electron transport in nanostructures

    Science.gov (United States)

    Yanik, Ahmet Ali

    2007-12-01

    with experimental data. For MTJs with embedded magnetic impurity layers, this model is able to capture and explain three distinctive experimental features reported in the literature regarding the dependence of the junction magneto-resistances (JMRs) on (1) barrier thickness, (2) barrier heights and (3) the concentrations of magnetic impurities [5,6,29,46]. Although in this dissertation our treatment was restricted to the electron-impurity spin exchange interactions, the NEGF model presented here allows one to incorporate other spin exchange scattering processes involving nuclear hyperfine, Bir-Aranov-Pikus (electron-hole) and electron-magnon interactions. This model is general and can be used to analyze and design a variety of spintronic devices beyond the large cross-section multilayer devices explored in this work.

  17. Resource use, dependence and vulnerability: community-resource linkages on Alaska's Tongass National Forest

    Science.gov (United States)

    E.T. Mekbeb; R.J. Lilieholm; D.J. Blahna; L.E. Kruger

    2009-01-01

    Understanding how rural communities use and depend upon local natural resources is a critical factor in developing policies to sustain the long-term viability of human and natural systems. Such “community-resource” linkages are particularly important in Alaska, where rural communities – many of them comprised of indigenous Alaskan Natives – are highly dependent upon...

  18. Why and How to Measure the Use of Electronic Resources

    Directory of Open Access Journals (Sweden)

    Jean Bernon

    2008-11-01

    Full Text Available A complete overview of library activity implies a complete and reliable measurement of the use of both electronic resources and printed materials. This measurement is based on three sets of definitions: document types, use types and user types. There is a common model of definitions for printed materials, but a lot of questions and technical issues remain for electronic resources. In 2006 a French national working group studied these questions. It relied on the COUNTER standard, but found it insufficient and pointed out the need for local tools such as web markers and deep analysis of proxy logs. Within the French national consortium COUPERIN, a new working group is testing ERMS, SUSHI standards, Shibboleth authentication, along with COUNTER standards, to improve the counting of the electronic resources use. At this stage this counting is insufficient and its improvement will be a European challenge for the future.

  19. Access to electronic resources by visually impaired people

    Directory of Open Access Journals (Sweden)

    Jenny Craven

    2003-01-01

    Full Text Available Research into access to electronic resources by visually impaired people undertaken by the Centre for Research in Library and Information Management has not only explored the accessibility of websites and levels of awareness in providing websites that adhere to design for all principles, but has sought to enhance understanding of information seeking behaviour of blind and visually impaired people when using digital resources.

  20. The Study of Analytical Model of Library Electronic Resources Usage-A Case of Medical Electronic Resources

    Directory of Open Access Journals (Sweden)

    Chung-Yen Yu

    2014-10-01

    Full Text Available With the advents of internet, the importance of electronic resources is growing. Due to the increasing expensiveness of electronic resources, university libraries normally received budgets from parent institutions annually. They necessarily applied effective and systematic methods for decision making in electronic resources purchase or re-subscription. However, there are some difficulties in practices: First of all, libraries are unable to receive user records; second, the COUNTER statistics does not include details about users and their affiliation. As a result, one cannot conduct advanced user analysis based on the usage of users, institutions, and departments. To overcome the difficulties, this study presents a feasible model to analyze electronic resource usage effectively and flexibly. We set up a proxy server to collect actual usage raw data. By analyzing items in internet browsing records, associated with original library automatic system, this study aims at exploring how to use effective ways to analyze big data of website log data. We also propose the process of how original data to be transformed, cleared, integrated, and demonstrated. This study adopted a medical university library and its subscription of medical electronic resources as a case. Our data analysis includes (1 year of subscription,(2 title of journal, (3 affiliation, (4 subjects, and (5 specific journal requirements, etc. The findings of the study are contributed to obtain further understanding in policy making and user behavior analysis. The integrated data provides multiple applications in informatics research, information behavior, bibliomining, presenting diverse views and extended issues for further discussion.

  1. Vibrationally dependent electron-electron interactions in resonant electron transport through single-molecule junctions

    Science.gov (United States)

    Erpenbeck, A.; Härtle, R.; Bockstedte, M.; Thoss, M.

    2016-03-01

    We investigate the role of electronic-vibrational coupling in resonant electron transport through single-molecule junctions, taking into account that the corresponding coupling strengths may depend on the charge and excitation state of the molecular bridge. Within an effective-model Hamiltonian approach for a molecule with multiple electronic states, this requires to extend the commonly used model and include vibrationally dependent electron-electron interaction. We use Born-Markov master equation methods and consider selected models to exemplify the effect of the additional interaction on the transport characteristics of a single-molecule junction. In particular, we show that it has a significant influence on local cooling and heating mechanisms, it may result in negative differential resistance, and it may cause pronounced asymmetries in the conductance map of a single-molecule junction.

  2. Practical guide to electronic resources in the humanities

    CERN Document Server

    Dubnjakovic, Ana

    2010-01-01

    From full-text article databases to digitized collections of primary source materials, newly emerging electronic resources have radically impacted how research in the humanities is conducted and discovered. This book, covering high-quality, up-to-date electronic resources for the humanities, is an easy-to-use annotated guide for the librarian, student, and scholar alike. It covers online databases, indexes, archives, and many other critical tools in key humanities disciplines including philosophy, religion, languages and literature, and performing and visual arts. Succinct overviews of key eme

  3. Funding and Focus: Resource Dependence in Public Higher Education

    Science.gov (United States)

    Fowles, Jacob

    2014-01-01

    Utilizing resource dependence theory, this study investigates the relationship between institutional reliance on net tuition dollars as a source of revenue and institutional expenditures for education and related activities at public, four-year institutions of higher education in the United States. Drawing on an 11-year panel of university-level…

  4. Discipline, availability of electronic resources and the use of Finnish National Electronic Library - FinELib

    Directory of Open Access Journals (Sweden)

    Sanna Torma

    2004-01-01

    Full Text Available This study elaborated relations between digital library use by university faculty, users' discipline and the availability of key resources in the Finnish National Electronic Library (FinELib, Finnish national digital library, by using nationwide representative survey data. The results show that the perceived availability of key electronic resources by researchers in FinELib was a stronger predictor of the frequency and purpose of use of its services than users' discipline. Regardless of discipline a good perceived provision of central resources led to a more frequent use of FinELib. The satisfaction with the services did not vary with the discipline, but with the perceived availability of resources.

  5. Providing Access to Electronic Information Resources in Further Education

    Science.gov (United States)

    Banwell, Linda; Ray, Kathryn; Coulson, Graham; Urquhart, Christine; Lonsdale, Ray; Armstrong, Chris; Thomas, Rhian; Spink, Sin; Yeoman, Alison; Fenton, Roger; Rowley, Jennifer

    2004-01-01

    This article aims to provide a baseline for future studies on the provision and support for the use of digital or electronic information services (EIS) in further education. The analysis presented is based on a multi-level model of access, which encompasses access to and availability of information and communication technology (ICT) resources,…

  6. ANALYTICAL REVIEW OF ELECTRONIC RESOURCES FOR THE STUDY OF LATIN

    Directory of Open Access Journals (Sweden)

    Olena Yu. Balalaieva

    2014-04-01

    Full Text Available The article investigates the current state of development of e-learning content in the Latin language. It is noted that the introduction of ICT in the educational space has expanded the possibility of studying Latin, opened access to digital libraries resources, made it possible to use scientific and educational potential and teaching Latin best practices of world's leading universities. A review of foreign and Ukrainian information resources and electronic editions for the study of Latin is given. Much attention was paid to the didactic potential of local and online multimedia courses of Latin, electronic textbooks, workbooks of interactive tests and exercises, various dictionaries and software translators, databases and digital libraries. Based on analysis of the world market of educational services and products the main trends in the development of information resources and electronic books are examined. It was found that multimedia courses with interactive exercises or workbooks with interactive tests, online dictionaries and translators are the most widely represented and demanded. The noticeable lagging of Ukrainian education and computer linguistics in quantitative and qualitative measures in this industry is established. The obvious drawback of existing Ukrainian resources and electronic editions for the study of Latin is their noninteractive nature. The prospects of e-learning content in Latin in Ukraine are outlined.

  7. Electronic Commerce Resource Centers. An Industry--University Partnership.

    Science.gov (United States)

    Gulledge, Thomas R.; Sommer, Rainer; Tarimcilar, M. Murat

    1999-01-01

    Electronic Commerce Resource Centers focus on transferring emerging technologies to small businesses through university/industry partnerships. Successful implementation hinges on a strategic operating plan, creation of measurable value for customers, investment in customer-targeted training, and measurement of performance outputs. (SK)

  8. Student Satisfaction with Electronic Library Resources at Wayne State University

    Science.gov (United States)

    Holley, Robert P.; Powell, Ronald R.

    2004-01-01

    This paper reports the results of a survey of student satisfaction with electronic library resources other than the online catalog at Wayne State University. Undertaken in Fall Term 2000 as a class project for a marketing course, a student team designed, administered, and analyzed a survey of a random sample of students. Almost 40% of the…

  9. Electronic Commerce Resource Centers. An Industry--University Partnership.

    Science.gov (United States)

    Gulledge, Thomas R.; Sommer, Rainer; Tarimcilar, M. Murat

    1999-01-01

    Electronic Commerce Resource Centers focus on transferring emerging technologies to small businesses through university/industry partnerships. Successful implementation hinges on a strategic operating plan, creation of measurable value for customers, investment in customer-targeted training, and measurement of performance outputs. (SK)

  10. Technical Communicator: A New Model for the Electronic Resources Librarian?

    Science.gov (United States)

    Hulseberg, Anna

    2016-01-01

    This article explores whether technical communicator is a useful model for electronic resources (ER) librarians. The fields of ER librarianship and technical communication (TC) originated and continue to develop in relation to evolving technologies. A review of the literature reveals four common themes for ER librarianship and TC. While the…

  11. Providing Access to Electronic Information Resources in Further Education

    Science.gov (United States)

    Banwell, Linda; Ray, Kathryn; Coulson, Graham; Urquhart, Christine; Lonsdale, Ray; Armstrong, Chris; Thomas, Rhian; Spink, Sin; Yeoman, Alison; Fenton, Roger; Rowley, Jennifer

    2004-01-01

    This article aims to provide a baseline for future studies on the provision and support for the use of digital or electronic information services (EIS) in further education. The analysis presented is based on a multi-level model of access, which encompasses access to and availability of information and communication technology (ICT) resources,…

  12. Existence of time-dependent density-functional theory for open electronic systems: time-dependent holographic electron density theorem.

    Science.gov (United States)

    Zheng, Xiao; Yam, ChiYung; Wang, Fan; Chen, GuanHua

    2011-08-28

    We present the time-dependent holographic electron density theorem (TD-HEDT), which lays the foundation of time-dependent density-functional theory (TDDFT) for open electronic systems. For any finite electronic system, the TD-HEDT formally establishes a one-to-one correspondence between the electron density inside any finite subsystem and the time-dependent external potential. As a result, any electronic property of an open system in principle can be determined uniquely by the electron density function inside the open region. Implications of the TD-HEDT on the practicality of TDDFT are also discussed.

  13. Evaluating the appropriateness of electronic information resources for learning.

    Science.gov (United States)

    Saparova, Dinara; Nolan, Nathanial S

    2016-01-01

    Current US medical students have begun to rely on electronic information repositories-such as UpToDate, AccessMedicine, and Wikipedia-for their pre-clerkship medical education. However, it is unclear whether these resources are appropriate for this level of learning due to factors involving information quality, level of evidence, and the requisite knowledgebase. This study evaluated appropriateness of electronic information resources from a novel perspective: amount of mental effort learners invest in interactions with these resources and effects of the experienced mental effort on learning. Eighteen first-year medical students read about three unstudied diseases in the above-mentioned resources (a total of fifty-four observations). Their eye movement characteristics (i.e., fixation duration, fixation count, visit duration, and task-evoked pupillary response) were recorded and used as psychophysiological indicators of the experienced mental effort. Post reading, students' learning was assessed with multiple-choice tests. Eye metrics and test results constituted quantitative data analyzed according to the repeated Latin square design. Students' perceptions of interacting with the information resources were also collected. Participants' feedback during semi-structured interviews constituted qualitative data and was reviewed, transcribed, and open coded for emergent themes. Compared to AccessMedicine and Wikipedia, UpToDate was associated with significantly higher values of eye metrics, suggesting learners experienced higher mental effort. No statistically significant difference between the amount of mental effort and learning outcomes was found. More so, descriptive statistical analysis of the knowledge test scores suggested similar levels of learning regardless of the information resource used. Judging by the learning outcomes, all three information resources were found appropriate for learning. UpToDate, however, when used alone, may be less appropriate for first

  14. Parametric dependencies of JET electron temperature profiles

    Energy Technology Data Exchange (ETDEWEB)

    Schunke, B. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Imre, K.; Riedel, K. [New York Univ., NY (United States)

    1994-07-01

    The JET Ohmic, L-Mode and H-Mode electron temperature profiles obtained from the LIDAR Thomson Scattering Diagnostic are parameterized in terms of the normalized flux parameter and a set of the engineering parameters like plasma current, toroidal field, line averages electron density... It is shown that the electron temperature profiles fit a log-additive model well. It is intended to use the same model to predict the profile shape for D-T discharges in JET and in ITER. 2 refs., 5 figs.

  15. Evolution of resource competition between mutually dependent digital organisms.

    Science.gov (United States)

    Johnson, Tyler J; Wilke, Claus O

    2004-01-01

    We study the emergence and dynamics of competing strains of digital organisms in a world with two depletable resources. Consumption of one resource produces the other resource as a by-product, and vice versa. As a consequence, two types of mutually dependent organisms emerge that each prey on the waste product of the other. In the absence of mutations, that is, in a purely ecological setting, the abundances of the two types of organisms display a wide range of different types of oscillations, from regular oscillations with large amplitude to irregular oscillations with amplitudes ranging from small to large. In this regime, time-averaged abundance levels seem to be controlled by the relative fitness of the organisms in the absence of resources. Under mutational pressure, on the other hand, populations evolve that seem to avoid the oscillations of intermediate to large amplitudes. In this case, the relative fitness of the organisms in the presence of resources plays an important role in the time-averaged abundance levels as well.

  16. MODEL OF AN ELECTRONIC EDUCATIONAL RESOURCE OF NEW GENERATION

    Directory of Open Access Journals (Sweden)

    Anatoliy V. Loban

    2016-01-01

    Full Text Available The mathematical structure of the modular architecture of an electronic educational resource (EER of new generation, which allows to decompose the process of studying the subjects of the course at a hierarchically ordered set of data (knowledge and procedures for manipulating them, to determine the roles of participants of process of training of and technology the development and use of EOR in the study procrate.

  17. Effect of Electronic Monitoring on Social Welfare Dependence

    DEFF Research Database (Denmark)

    Andersen, Lars Højsgaard; Andersen, Signe Hald

    2014-01-01

    Research Summary We studied the effect on unemployment social welfare dependence of serving a sentence under elec-tronic monitoring rather than in prison, using Danish registry data and two policy shifts that extended the use of electronic monitoring in Denmark. We found electronic monitoring is ...

  18. Evaluating increased resource use in fibromyalgia using electronic health records

    Directory of Open Access Journals (Sweden)

    Margolis JM

    2016-11-01

    Full Text Available Jay M Margolis,1 Elizabeth T Masters,2 Joseph C Cappelleri,3 David M Smith,1 Steven Faulkner4 1Truven Health Analytics, Life Sciences, Outcomes Research, Bethesda, MD, 2Pfizer Inc, Outcomes & Evidence, New York, NY, 3Pfizer Inc, Statistics, Groton, CT, 4Pfizer Inc, North American Medical Affairs, Medical Outcomes Specialists, St Louis, MO, USA Objective: The management of fibromyalgia (FM, a chronic musculoskeletal disease, remains challenging, and patients with FM are often characterized by high health care resource utilization. This study sought to explore potential drivers of all-cause health care resource utilization and other factors associated with high resource use, using a large electronic health records (EHR database to explore data from patients diagnosed with FM. Methods: This was a retrospective analysis of de-identified EHR data from the Humedica database. Adults (≥18 years with FM were identified based on ≥2 International Classification of Diseases, Ninth Revision codes for FM (729.1 ≥30 days apart between January 1, 2008 and December 31, 2012 and were required to have evidence of ≥12 months continuous care pre- and post-index; first FM diagnosis was the index event; 12-month pre- and post-index reporting periods. Multivariable analysis evaluated relationships between variables and resource utilization. Results: Patients were predominantly female (81.4%, Caucasian (87.7%, with a mean (standard deviation age of 54.4 (14.8 years. The highest health care resource utilization was observed for the categories of “medication orders” and “physician office visits,” with 12-month post-index means of 21.2 (21.5 drug orders/patient and 15.1 (18.1 office visits/patient; the latter accounted for 73.3% of all health care visits. Opioids were the most common prescription medication, 44.3% of all patients. The chance of high resource use was significantly increased (P<0.001 26% among African-Americans vs Caucasians and for patients

  19. Online Electronic Resources and Slovenian Bibliography: a Case Study

    Directory of Open Access Journals (Sweden)

    Daniela Škerget

    2014-09-01

    Full Text Available AbstractConsidering the fact that the number of publications available online only is growing, the question whether to include online electronic resources into the Slovenian bibliography, and if so, in which way, and what are the requirements for the inclusion, is raised. To answer these questions, the research on the growth of the Slovenian online scientific production in comparison with production in printed form was conducted in the case of original scientific articles. Results showed a rapid growth of the number of original scientific articles available online only, which indicates the necessity to form a separate Slovenian bibliography of online resources. The selection criteria for the Slovenian bibliography of online resources are also presented. This kind of bibliography would, along with the informational value, add to the historical value of intellectual production in a given time frame, enriched with a link to the resource preserved in another location (archive, repository, in case of unavailability of the resource on its original location.

  20. Network resource allocation attack detection with long range dependence

    Institute of Scientific and Technical Information of China (English)

    WANG Xin; FANG Bin-xing

    2007-01-01

    The approach of traffic abnormality detection of network resource allocation attack did not have reliable signatures to depict abnormality and identify them. However, it is crucial for us to detect attacks accurately.The technique that we adopted is inspired by long range dependence ideas. We use the number of packet arrivals of a flow in fixed-length time intervals as the signal and attempt to extend traffic invariant "self-similarity".We validate the effectiveness of the approach with simulation and trace analysis.

  1. Resource dependence and institutional elements in nursing home TQM adoption.

    Science.gov (United States)

    Zinn, J S; Weech, R J; Brannon, D

    1998-06-01

    To examine the contextual attributes that influence nursing home TQM adoption, as informed by resource dependence and institutional theories. A survey of licensed nursing home administrators in the Commonwealth of Pennsylvania during 1994-1995, the Medicare and Medicaid Annual Certification Survey (MMACS) data file, and the Area Resource File (ARF). Because the dependent variable (TQM adoption vs. non-adoption) is dichotomous, the model was estimated using logistic regression. Of the 615 facilities that were mailed surveys, 241 (39.2%) returned completed questionnaires. No significant differences were observed between respondents and nonrespondents in size, for-profit status, system membership, registered nurse staffing, cited licensure deficiencies, Medicare census, or Medicaid census. Perceived competition, Medicare's share of total hospital discharges in the market, and facility Medicare census were significant predictors of TQM adoption. Our results provide limited support for the association between some rational adaptive and institutional factors and TQM adoption in nursing homes. Perceived competition and the influence of the Medicare program both at the facility and the market level are associated with TQM adoption. However, other factors associated with TQM adoption in other industries, such as size, are not associated with TQM adoption in the nursing homes in this study.

  2. Journals, Data and Abstracts Make an Integrated Electronic Resource

    Science.gov (United States)

    Boyce, P.

    1996-12-01

    Astronomy now has an integrated, Web-based information resource for research papers, data and bibliographic information. The major scholarly research journals, a comprehensive abstract service and the astronomical data centers are now linked together to provide an information resource which is not available to most other scientific disciplines. As of January, 1997, the Astrophysical Journal joins the ApJ Letters on the Web. Astronomy and Astrophysics Supplements now has a page image version. Elsevier's electronic journal New Astronomy has recently made its appearance. Over forty percent of the new peer-reviewed, astronomical literature is now available electronically. The main Astronomy and Astrophysics journal, the Astronomical Journal and others will be available by 1998, at which point ninety percent of the literature will be available electronically, a figure not approached by any other scientific discipline. With so many different sources, one of the challenges has been to integrate the on-line, peer-reviewed literature into a resource which serves the astronomical community in a unified and coherent manner. Following the lead of the AAS, the major publishers have chosen to rely upon the NASA-supported Astrophysics Data System (ADS) and the astronomical data centers to provide the means by which the various separate journals can interoperate. The data centers and the ADS have developed unique identification codes for journal articles. By adopting the existing standard "bibcodes" and integrating them into their WWW links, each of the major astronomical journals are able to link to the abstracts of most of the referenced articles. Since the ADS also serves as an on-line repository for page images of the past twenty years of the major astronomical journals, the full text of many of the referenced articles are available, too. The articles in the ADS have recently been linked through their references, both forward and backward in time. With the "bibcode" providing

  3. Analysis of Human Resources Management Strategy in China Electronic Commerce Enterprises

    Science.gov (United States)

    Shao, Fang

    The paper discussed electronic-commerce's influence on enterprise human resources management, proposed and proved the human resources management strategy which electronic commerce enterprise should adopt from recruitment strategy to training strategy, keeping talent strategy and other ways.

  4. Resources

    Science.gov (United States)

    ... resources Alzheimer's - resources Anorexia nervosa - resources Arthritis - resources Asthma and allergy - resources Autism - resources Blindness - resources BPH - resources Breastfeeding - resources Bulimia - resources Burns - resources Cancer - resources Cerebral ...

  5. Discipline, Availability of Electronic Resources and the Use of Finnish National Electronic Library-- FinELib

    Science.gov (United States)

    Törmä, Sanna; Vakkari, Pertti

    2004-01-01

    This study elaborated relations between digital library use by university faculty, users' discipline and the availability of key resources in the Finnish National Electronic Library (FinELib), Finnish national digital library, by using nationwide representative survey data. The results show that the perceived availability of key electronic…

  6. Temperature dependence of electron attachment to methylene chloride

    Science.gov (United States)

    Pinnaduwage, L. A.; Tav, C.; McCorkle, D. L.; Ding, W. X.

    1999-05-01

    Temperature dependence of dissociative electron attachment to methylene chloride in the electron energy range of 0-10 eV was studied in a high-temperature electron swarm apparatus. The measurements were made using N2 and Ar as buffer gases. From the measured electron attachment rate constants, the electron attachment cross sections at 300, 400, and 500 K were determined using an unfolding technique. The maximum electron attachment cross sections at 300, 400, and 500 K were ≈3.1×10-18, ≈8.2×10-18, and ≈1.7×10-17 cm2, and occurred at electron energies of ≈0.8, ≈0.65, and ≈0.55 eV, respectively. The increase in electron attachment to methylene chloride with temperature is attributed to the increase in the vibrational energy of the molecule.

  7. End-of-life resource recovery from emerging electronic products

    DEFF Research Database (Denmark)

    Parajuly, Keshav; Habib, Komal; Cimpan, Ciprian

    2016-01-01

    of emerging electronic product, in order to understand the recovery fate of different materials and its linkage to product design. Ten different brands of RVC were dismantled and their material composition and design profiles were studied. Another 125 RVCs (349 kg) were used for an experimental trial......Integrating product design with appropriate end-of-life (EoL) processing is widely recognized to have huge potentials in improving resource recovery from electronic products. In this study, we investigate both the product characteristics and EoL processing of robotic vacuum cleaner (RVC), as a case...... at a conventional ‘shred-and-separate’ type preprocessing plant in Denmark. A detailed material flow analysis was performed throughout the recycling chain. The results show a mismatch between product design and EoL processing, and the lack of practical implementation of ‘Design for EoL’ thinking. In the best...

  8. Electronic Resources and Mission Creep: Reorganizing the Library for the Twenty-First Century

    Science.gov (United States)

    Stachokas, George

    2009-01-01

    The position of electronic resources librarian was created to serve as a specialist in the negotiation of license agreements for electronic resources, but mission creep has added more functions to the routine work of electronic resources such as cataloging, gathering information for collection development, and technical support. As electronic…

  9. Effects of Electronic Information Resources Skills Training for Lecturers on Pedagogical Practices and Research Productivity

    Science.gov (United States)

    Bhukuvhani, Crispen; Chiparausha, Blessing; Zuvalinyenga, Dorcas

    2012-01-01

    Lecturers use various electronic resources at different frequencies. The university library's information literacy skills workshops and seminars are the main sources of knowledge of accessing electronic resources. The use of electronic resources can be said to have positively affected lecturers' pedagogical practices and their work in general. The…

  10. Temperature dependence of electronic heat capacity in Holstein model

    CERN Document Server

    Fialko, N S; Lakhno, V D

    2015-01-01

    The dynamics of charge migration was modeled to calculate temperature dependencies of its thermodynamic equilibrium values such as energy and electronic heat capacity in homogeneous adenine fragments. The energy varies from nearly polaron one at T~0 to midpoint of the conductivity band at high temperatures. The peak on the graph of electronic heat capacity is observed at the polaron decay temperature.

  11. Vertical Interplay among Scale-dependent Environmental and Resource Regimes

    Directory of Open Access Journals (Sweden)

    Oran Young

    2006-06-01

    Full Text Available Environmental and resource regimes, operating at different levels of social organization, vary in terms of factors such as the sources of actor behavior, the knowledge available to actors, the operation of compliance mechanisms, the use of policy instruments, and the nature of the broader social setting. Cross-level interactions among scale-dependent regimes can result in patterns of dominance, separation, merger, negotiated agreement, or system change. The mechanisms that determine which of these patterns will occur include authority/power differentials, limits of decentralization, dueling discourses, cognitive transitions, and blocking coalitions. Recurrent linkages or syndromes occur in this realm, e.g., limitations of authority and power regularly produce negotiated agreements in such forms as comanagement arrangements. The consequences of these interactions are often far-reaching as measured in terms of ecological sustainability, social welfare/efficiency, cultural values, and robustness.

  12. Comparing Public and Private Institutions That Have and Have Not Implemented Enterprise Resource Planning (ERP) Systems: A Resource Dependence Perspective

    Science.gov (United States)

    Sendhil, Geetha R.

    2012-01-01

    The purpose of this national study was to utilize quantitative methods to examine institutional characteristics, financial resource variables, personnel variables, and customer variables of public and private institutions that have and have not implemented enterprise resource planning (ERP) systems, from a resource dependence perspective.…

  13. Comparing Public and Private Institutions That Have and Have Not Implemented Enterprise Resource Planning (ERP) Systems: A Resource Dependence Perspective

    Science.gov (United States)

    Sendhil, Geetha R.

    2012-01-01

    The purpose of this national study was to utilize quantitative methods to examine institutional characteristics, financial resource variables, personnel variables, and customer variables of public and private institutions that have and have not implemented enterprise resource planning (ERP) systems, from a resource dependence perspective.…

  14. Effect of Electronic Monitoring on Social Welfare Dependence

    DEFF Research Database (Denmark)

    Andersen, Lars Højsgaard; Andersen, Signe Hald

    2014-01-01

    is less harmful than imprisonment, at least for younger offenders, whereas it does not leave older offenders worse off than imprisonment. Policy Implications As the United States moves towards noncustodial alternatives to imprisonment, it makes sense for policy makers to direct their attention...... the use of electronic monitoring in the United States could be accelerated.......Research Summary We studied the effect on unemployment social welfare dependence of serving a sentence under elec-tronic monitoring rather than in prison, using Danish registry data and two policy shifts that extended the use of electronic monitoring in Denmark. We found electronic monitoring...

  15. Electronic Document Management: A Human Resource Management Case Study

    Directory of Open Access Journals (Sweden)

    Thomas Groenewald

    2004-11-01

    Full Text Available This case study serve as exemplar regarding what can go wrong with the implementation of an electronic document management system. Knowledge agility and knowledge as capital, is outlined against the backdrop of the information society and knowledge economy. The importance of electronic document management and control is sketched thereafter. The literature review is concluded with the impact of human resource management on knowledge agility, which includes references to the learning organisation and complexity theory. The intervention methodology, comprising three phases, follows next. The results of the three phases are presented thereafter. Partial success has been achieved with improving the human efficacy of electronic document management, however the client opted to discontinue the system in use. Opsomming Die gevalle studie dien as voorbeeld van wat kan verkeerd loop met die implementering van ’n elektroniese dokumentbestuur sisteem. Teen die agtergrond van die inligtingsgemeenskap en kennishuishouding word kennissoepelheid en kennis as kapitaal bespreek. Die literatuurstudie word afgesluit met die inpak van menslikehulpbronbestuur op kennissoepelheid, wat ook die verwysings na die leerorganisasie en kompleksietydsteorie insluit. Die metodologie van die intervensie, wat uit drie fases bestaan, volg daarna. Die resultate van die drie fases word vervolgens aangebied. Slegs gedeelte welslae is behaal met die verbetering van die menslike doeltreffendheid ten opsigte van elektroniese dokumentbestuur. Die klient besluit egter om nie voort te gaan om die huidige sisteem te gebruik nie.

  16. Density-mediated, context-dependent consumer-resource interactions between ants and extrafloral nectar plants.

    Science.gov (United States)

    Chamberlain, Scott A; Holland, J Nathaniel

    2008-05-01

    Interspecific interactions are often mediated by the interplay between resource supply and consumer density. The supply of a resource and a consumer's density response to it may in turn yield context-dependent use of other resources. Such consumer-resource interactions occur not only for predator-prey and competitive interactions, but for mutualistic ones as well. For example, consumer-resource interactions between ants and extrafloral nectar (EFN) plants are often mutualistic, as EFN resources attract and reward ants which protect plants from herbivory. Yet, ants also commonly exploit floral resources, leading to antagonistic consumer-resource interactions by disrupting pollination and plant reproduction. EFN resources associated with mutualistic ant-plant interactions may also mediate antagonistic ant-flower interactions through the aggregative density response of ants on plants, which could either exacerbate ant-flower interactions or alternatively satiate and distract ants from floral resources. In this study, we examined how EFN resources mediate the density response of ants on senita cacti in the Sonoran Desert and their context-dependent use of floral resources. Removal of EFN resources reduced the aggregative density of ants on plants, both on hourly and daily time scales. Yet, the increased aggregative ant density on plants with EFN resources decreased rather than increased ant use of floral resources, including contacts with and time spent in flowers. Behavioral assays showed no confounding effect of floral deterrents on ant-flower interactions. Thus, ant use of floral resources depends on the supply of EFN resources, which mediates the potential for both mutualistic and antagonistic interactions by increasing the aggregative density of ants protecting plants, while concurrently distracting ants from floral resources. Nevertheless, only certain years and populations of study showed an increase in plant reproduction through herbivore protection or ant

  17. Does spacecraft potential depend on the ambient electron density?

    Science.gov (United States)

    Lai, S. T.; Martinez-Sanchez, M.; Cahoy, K.; Thomsen, M. F.; Shprits, Y.; Lohmeyer, W. Q.; Wong, F.

    2014-12-01

    In a Maxwellian space plasma model, the onset of spacecraft charging at geosynchronous altitudes is due to the ambient electron, ambient ions, and secondary electrons. By using current balance, one can show that the onset of spacecraft charging depends not on the ambient electron density but instead on the critical temperature of the ambient electrons. If the ambient plasma deviates significantly from equilibrium, a non-Maxwellian electron distribution results. For a kappa distribution, the onset of spacecraft charging remains independent of ambient electron density. However, for double Maxwellian distributions, the densities do have a role in the onset of spacecraft charging. For a dielectric spacecraft in sunlight, the trapping of photoelectrons on the sunlit side enhances the local electron density. Using the coordinated environmental satellite data from the Los Alamos National Laboratory geosynchronous satellites, we have obtained results that confirm that the observed spacecraft potential is independent of the ambient electron density during eclipse and that in sunlight charging the low-energy population around the sunlit side of the spacecraft is enhanced by photoelectrons trapped inside the potential barrier.

  18. Impact-parameter-dependent electronic stopping of swift ions

    NARCIS (Netherlands)

    Schinner, A.; Sigmund, P.

    2010-01-01

    A computational scheme has been developed to estimate the mean electronic energy loss of an incident swift ion on an atomic target as a function of the impact parameter between the moving nuclei. The theoretical basis is binary stopping theory. In order to extract impact-parameter dependencies it wa

  19. Electronic Safety Resource Tools -- Supporting Hydrogen and Fuel Cell Commercialization

    Energy Technology Data Exchange (ETDEWEB)

    Barilo, Nick F.

    2014-09-29

    The Pacific Northwest National Laboratory (PNNL) Hydrogen Safety Program conducted a planning session in Los Angeles, CA on April 1, 2014 to consider what electronic safety tools would benefit the next phase of hydrogen and fuel cell commercialization. A diverse, 20-person team led by an experienced facilitator considered the question as it applied to the eight most relevant user groups. The results and subsequent evaluation activities revealed several possible resource tools that could greatly benefit users. The tool identified as having the greatest potential for impact is a hydrogen safety portal, which can be the central location for integrating and disseminating safety information (including most of the tools identified in this report). Such a tool can provide credible and reliable information from a trustworthy source. Other impactful tools identified include a codes and standards wizard to guide users through a series of questions relating to application and specific features of the requirements; a scenario-based virtual reality training for first responders; peer networking tools to bring users from focused groups together to discuss and collaborate on hydrogen safety issues; and a focused tool for training inspectors. Table ES.1 provides results of the planning session, including proposed new tools and changes to existing tools.

  20. Controlling user access to electronic resources without password

    Science.gov (United States)

    Smith, Fred Hewitt

    2015-06-16

    Described herein are devices and techniques for remotely controlling user access to a restricted computer resource. The process includes pre-determining an association of the restricted computer resource and computer-resource-proximal environmental information. Indicia of user-proximal environmental information are received from a user requesting access to the restricted computer resource. Received indicia of user-proximal environmental information are compared to associated computer-resource-proximal environmental information. User access to the restricted computer resource is selectively granted responsive to a favorable comparison in which the user-proximal environmental information is sufficiently similar to the computer-resource proximal environmental information. In at least some embodiments, the process further includes comparing user-supplied biometric measure and comparing it with a predetermined association of at least one biometric measure of an authorized user. Access to the restricted computer resource is granted in response to a favorable comparison.

  1. Intensity dependence of electron gas kinetics in a laser corona

    Directory of Open Access Journals (Sweden)

    Mašek Martin

    2013-11-01

    Full Text Available In various experimental situations relevant to the laser fusion, such as plasma near the light entrance holes of hohlraum in the indirect drive experiments or more recently in the shock ignition direct drive a relatively long underdense plasma of corona type is encountered, which is subject to an intense nanosecond laser beam. The plasma is only weakly collisional and thus in the electron phase space a complicated kinetic evolution is going on, which is taking the electron gas fairly far from the thermal equilibrium and contributes to its unstable behaviour. These phenomena impede the absorption and thermalization of the incoming laser energy, create groups of fast electrons and also may lead to a non-linear reflection of the heating laser beam. One of the key processes leading to the electron acceleration is the stimulated Raman scattering (SRS in its non-linear phase. The SRS in the presence of electron-ion collisions requires a certain threshold intensity above which the mentioned non-dissipative phenomena can occur and develop to the stage, where they may become unpleasant for the fusion experiments. To assess this intensity limit a computational model has been developed based on the Vlasov-Maxwell kinetics describing such a plasma in 1D geometry. At a relatively high intensity of 1016 W/cm2 a number of non-linear phenomena are predicted by the code such as a saturation of Landau damping, which is then translated in an unfavourable time dependence of the reflected light intensity and formation of accelerated electron groups due to the electron trapping. The purpose of the present contribution is to map the intensity dependence of this non-linear development with the aim of assessing its weight in fusion relevant situations.

  2. The Internet School of Medicine: use of electronic resources by medical trainees and the reliability of those resources.

    Science.gov (United States)

    Egle, Jonathan P; Smeenge, David M; Kassem, Kamal M; Mittal, Vijay K

    2015-01-01

    Electronic sources of medical information are plentiful, and numerous studies have demonstrated the use of the Internet by patients and the variable reliability of these sources. Studies have investigated neither the use of web-based resources by residents, nor the reliability of the information available on these websites. A web-based survey was distributed to surgical residents in Michigan and third- and fourth-year medical students at an American allopathic and osteopathic medical school and a Caribbean allopathic school regarding their preferred sources of medical information in various situations. A set of 254 queries simulating those faced by medical trainees on rounds, on a written examination, or during patient care was developed. The top 5 electronic resources cited by the trainees were evaluated for their ability to answer these questions accurately, using standard textbooks as the point of reference. The respondents reported a wide variety of overall preferred resources. Most of the 73 responding medical trainees favored textbooks or board review books for prolonged studying, but electronic resources are frequently used for quick studying, clinical decision-making questions, and medication queries. The most commonly used electronic resources were UpToDate, Google, Medscape, Wikipedia, and Epocrates. UpToDate and Epocrates had the highest percentage of correct answers (47%) and Wikipedia had the lowest (26%). Epocrates also had the highest percentage of wrong answers (30%), whereas Google had the lowest percentage (18%). All resources had a significant number of questions that they were unable to answer. Though hardcopy books have not been completely replaced by electronic resources, more than half of medical students and nearly half of residents prefer web-based sources of information. For quick questions and studying, both groups prefer Internet sources. However, the most commonly used electronic resources fail to answer clinical queries more than half

  3. Pressure Dependent Electronic Properties of Organic Semiconductors from First Principles

    Science.gov (United States)

    Knuth, Franz; Carbogno, Christian; Blum, Volker; Scheffler, Matthias

    2015-03-01

    The electronic properties of organic semiconductors typically exhibit a significant dependence on the strain, stress, and pressure. In this contribution, we present the theoretical background, assessment of approximations, and results of electronic and transport properties in the framework of density-functional theory. Our implementation considers the analytical strain derivatives (stress tensor) including the contributions that stem from (a) van-der-Waals interactions and (b) the Fock-exchange in hybrid functionals. We validate our approach by investigating the geometric and electronic changes that occur in polyacetylene and anthracene under hydrostatic pressure. We show that the fraction of exact exchange included in the calculations is critical - and non-trivial to choose - for a correct description of these systems. Furthermore, we point out trends for the electrical conductivity under pressure and identify the dominant charge carriers and transport directions.

  4. Reductant-dependent electron distribution among redox sites of laccase

    DEFF Research Database (Denmark)

    Farver, O; Goldberg, M; Wherland, S

    1978-01-01

    chemical and thermodynamic properties. The distribution of electron equivalents among the redox sites was found to be reductant dependent. When the data for titration by various reductants of the type 3 site were plotted against those of the type 1 site according to the Nernst formalism, the slope n varied...... from 2.0 to 1.0. The redox potential of the reductant's first oxidation step is qualitatively correlated with the value of n and is suggested as the factor that modulates the electron distribution. Such a behavior implies a nonequilibrium situation. A very good simulation of the data was provided...... by an analysis assuming a formally variable cooperativity between the two type 3 copper ions. This apparent variability is suggested to result from a process whereby sufficiently strong reductants induce a transition of the type 3 site from a cooperative two-electron acceptor to a pair of independent one...

  5. Temperature dependent electronic correlation effects in GdN

    OpenAIRE

    Sharma, A; Nolting, W.

    2006-01-01

    We investigate temperature dependent electronic correlation effects in the conduction bands of Gadolinium Nitride (GdN) based on the combination of many body analysis of the multi-band Kondo lattice model and the first principles TB-LMTO bandstructure calculations. The physical properties like the quasi-particle density of states (Q-DOS), spectral density (SD) and quasi-particle bandstructure (Q-BS) are calculated and discussed. The results can be compared with spin and angle resolved inverse...

  6. RESOURCE DEPENDENCE, KNOWLEDGE CREATION, AND GROWTH: REVISITING THE NATURAL RESOURCE CURSE

    OpenAIRE

    Heinz Welsch

    2008-01-01

    Several explanations have been put forward for the phenomenon - referred to as ¡®curse of natural resources¡¯ - that resource-rich countries tend to display low rates of economic growth. This paper studies an R&D-related explanation, using an endogenous growth model with natural resources and R&D-based technological change. For suitable values of preference parameters, the model predicts that knowledge creation as well as capital formation are inversely related to natural-resource intensity, ...

  7. Orientational dependence of electronic stopping of molecule and cluster ions

    Science.gov (United States)

    Jensen, J.; Mikkelsen, H. H.; Sigmund, P.

    1994-04-01

    The electronic energy deposited by a fast molecule or cluster penetrating through matter is estimated on the basis of a multipole expansion of the Coulomb interaction between the projectile and the target electrons. The treatment is directed at distant collisions, and the primary purpose has been to gain an impression of the dependence of the electronic energy loss on the orientation of the projectile relative to the beam direction. With this qualitative goal in mind, and considering that the total charge of a moving cluster can be quite high, we chose Bohr's classical-oscillator model of the target atom as the theoretical basis. The energy loss versus impact parameter consists of the familiar monopole term which applies to a point charge, plus a number of multipole terms, the leading one of which is found to be a monopole-quadrupole term. In the energy loss averaged over all orientations, that term vanishes, and the leading nonvanishing term then becomes the quadrupole-quadrupole term which reflects the properties of expressions in the literature based on Bethe theory. It is concluded that for anisotropic molecules, the directional dependence of electronic energy loss is more pronounced than what could be expected from published proximity factors. Explicit examples refer to a diatomic molecule.

  8. Survival and growth of epiphytic ferns depend on resource sharing

    Directory of Open Access Journals (Sweden)

    Hua-Zheng eLu

    2016-03-01

    Full Text Available Locally available resources can be shared within clonal plant systems through physiological integration, thus enhancing their survival and growth. Most epiphytes exhibit clonal growth habit, but few studies have tested effects of physiological integration (resource sharing on survival and growth of epiphytes and whether such effects vary with species. We conducted two experiments, one on individuals (single ramets and another on groups (several ramets within a plot, with severed and intact rhizome treatments (without and with physiological integration on two dominant epiphytic ferns (Polypodiodes subamoena and Lepisorus scolopendrium in a subtropical montane moist forest in Southwest China. Rhizome severing (preventing integration significantly reduced ramet survival in the individual experiment and number of surviving ramets in the group experiment, and it also decreased biomass of both species in both experiments. However, the magnitude of such integration effects did not vary significantly between the two species. We conclude that resource sharing may be a general strategy for clonal epiphytes to adapt to forest canopies where resources are limited and heterogeneously distributed in space and time.

  9. Survival and Growth of Epiphytic Ferns Depend on Resource Sharing.

    Science.gov (United States)

    Lu, Hua-Zheng; Song, Liang; Liu, Wen-Yao; Xu, Xing-Liang; Hu, Yue-Hua; Shi, Xian-Meng; Li, Su; Ma, Wen-Zhang; Chang, Yan-Fen; Fan, Ze-Xin; Lu, Shu-Gang; Wu, Yi; Yu, Fei-Hai

    2016-01-01

    Locally available resources can be shared within clonal plant systems through physiological integration, thus enhancing their survival and growth. Most epiphytes exhibit clonal growth habit, but few studies have tested effects of physiological integration (resource sharing) on survival and growth of epiphytes and whether such effects vary with species. We conducted two experiments, one on individuals (single ramets) and another on groups (several ramets within a plot), with severed and intact rhizome treatments (without and with physiological integration) on two dominant epiphytic ferns (Polypodiodes subamoena and Lepisorus scolopendrium) in a subtropical montane moist forest in Southwest China. Rhizome severing (preventing integration) significantly reduced ramet survival in the individual experiment and number of surviving ramets in the group experiment, and it also decreased biomass of both species in both experiments. However, the magnitude of such integration effects did not vary significantly between the two species. We conclude that resource sharing may be a general strategy for clonal epiphytes to adapt to forest canopies where resources are limited and heterogeneously distributed in space and time.

  10. Developing Humanities Collections in the Digital Age: Exploring Humanities Faculty Engagement with Electronic and Print Resources

    Science.gov (United States)

    Kachaluba, Sarah Buck; Brady, Jessica Evans; Critten, Jessica

    2014-01-01

    This article is based on quantitative and qualitative research examining humanities scholars' understandings of the advantages and disadvantages of print versus electronic information resources. It explores how humanities' faculty members at Florida State University (FSU) use print and electronic resources, as well as how they perceive these…

  11. Developing Humanities Collections in the Digital Age: Exploring Humanities Faculty Engagement with Electronic and Print Resources

    Science.gov (United States)

    Kachaluba, Sarah Buck; Brady, Jessica Evans; Critten, Jessica

    2014-01-01

    This article is based on quantitative and qualitative research examining humanities scholars' understandings of the advantages and disadvantages of print versus electronic information resources. It explores how humanities' faculty members at Florida State University (FSU) use print and electronic resources, as well as how they perceive these…

  12. Electronic resource management practical perspectives in a new technical services model

    CERN Document Server

    Elguindi, Anne

    2012-01-01

    A significant shift is taking place in libraries, with the purchase of e-resources accounting for the bulk of materials spending. Electronic Resource Management makes the case that technical services workflows need to make a corresponding shift toward e-centric models and highlights the increasing variety of e-formats that are forcing new developments in the field.Six chapters cover key topics, including: technical services models, both past and emerging; staffing and workflow in electronic resource management; implementation and transformation of electronic resource management systems; the ro

  13. Determining the functional form of density dependence: deductive approaches for consumer-resource systems having a single resource.

    Science.gov (United States)

    Abrams, Peter A

    2009-09-01

    Consumer-resource models are used to deduce the functional form of density dependence in the consumer population. A general approach to determining the form of consumer density dependence is proposed; this involves determining the equilibrium (or average) population size for a series of different harvest rates. The relationship between a consumer's mortality and its equilibrium population size is explored for several one-consumer/one-resource models. The shape of density dependence in the resource and the shape of the numerical and functional responses all tend to be "inherited" by the consumer's density dependence. Consumer-resource models suggest that density dependence will very often have both concave and convex segments, something that is impossible under the commonly used theta-logistic model. A range of consumer-resource models predicts that consumer population size often declines at a decelerating rate with mortality at low mortality rates, is insensitive to or increases with mortality over a wide range of intermediate mortalities, and declines at a rapidly accelerating rate with increased mortality when mortality is high. This has important implications for management and conservation of natural populations.

  14. LP rounding and an almost harmonic algorithm for scheduling with resource dependent processing times

    NARCIS (Netherlands)

    Grigoriev, A.; Sviridenko, M.; Uetz, M.J.; DÍaz, J.; Jansen, K.; Rolim, J.D.P.; Zwick, U.

    2006-01-01

    We consider a scheduling problem on unrelated parallel machines with the objective to minimize the makespan. In addition to its machine dependence, the processing time of any job is dependent on the usage of a scarce renewable resource, e.g. workers. A given amount of that resource can be distribute

  15. Density-dependent electron transport and precise modeling of GaN high electron mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Bajaj, Sanyam, E-mail: bajaj.10@osu.edu; Shoron, Omor F.; Park, Pil Sung; Krishnamoorthy, Sriram; Akyol, Fatih; Hung, Ting-Hsiang [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Reza, Shahed; Chumbes, Eduardo M. [Raytheon Integrated Defense Systems, Andover, Massachusetts 01810 (United States); Khurgin, Jacob [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Rajan, Siddharth [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Material Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2015-10-12

    We report on the direct measurement of two-dimensional sheet charge density dependence of electron transport in AlGaN/GaN high electron mobility transistors (HEMTs). Pulsed IV measurements established increasing electron velocities with decreasing sheet charge densities, resulting in saturation velocity of 1.9 × 10{sup 7 }cm/s at a low sheet charge density of 7.8 × 10{sup 11 }cm{sup −2}. An optical phonon emission-based electron velocity model for GaN is also presented. It accommodates stimulated longitudinal optical (LO) phonon emission which clamps the electron velocity with strong electron-phonon interaction and long LO phonon lifetime in GaN. A comparison with the measured density-dependent saturation velocity shows that it captures the dependence rather well. Finally, the experimental result is applied in TCAD-based device simulator to predict DC and small signal characteristics of a reported GaN HEMT. Good agreement between the simulated and reported experimental results validated the measurement presented in this report and established accurate modeling of GaN HEMTs.

  16. Strategic Planning for Electronic Resources Management: A Case Study at Gustavus Adolphus College

    Science.gov (United States)

    Hulseberg, Anna; Monson, Sarah

    2009-01-01

    Electronic resources, the tools we use to manage them, and the needs and expectations of our users are constantly evolving; at the same time, the roles, responsibilities, and workflow of the library staff who manage e-resources are also in flux. Recognizing a need to be more intentional and proactive about how we manage e-resources, the…

  17. Strategic Planning for Electronic Resources Management: A Case Study at Gustavus Adolphus College

    Science.gov (United States)

    Hulseberg, Anna; Monson, Sarah

    2009-01-01

    Electronic resources, the tools we use to manage them, and the needs and expectations of our users are constantly evolving; at the same time, the roles, responsibilities, and workflow of the library staff who manage e-resources are also in flux. Recognizing a need to be more intentional and proactive about how we manage e-resources, the…

  18. The Relevancy of Graduate Curriculum to Human Resource Professionals' Electronic Communication.

    Science.gov (United States)

    Hoell, Robert C.; Henry, Gordon O.

    2003-01-01

    Electronic communications of human resource professionals and the content of 23 university human resource management courses were categorized using the Human Resource Certification Institute's body of knowledge. Differences between proportion of topics discussed and topics covered in curricula suggest some topics are over- or undertaught.…

  19. Bias-dependent oscillatory electron transport of monatomic sulfur chains

    KAUST Repository

    Yu, Jing-Xin

    2012-01-01

    The bias-dependent oscillatory electron transport of monatomic sulfur chains sandwiched between gold electrodes is investigated with density functional theory and non-equilibrium Green\\'s function method. At zero bias, in contrast to the typical odd-even oscillations observed in most metallic chains, we find that the conductance oscillates with a period of four atoms. However, as the bias voltage is increased the current displays a two-atom periodicity. This emerges gradually, first for the longer chains and then, at voltages larger than 0.7 V, for lengths. The oscillatory behaviors are analyzed by the density of states and the energy-dependent and bias-dependent transmission coefficients. © 2012 American Institute of Physics.

  20. Temperature dependence of the electronic structure of semiconductors and insulators

    Energy Technology Data Exchange (ETDEWEB)

    Poncé, S., E-mail: samuel.pon@gmail.com; Gillet, Y.; Laflamme Janssen, J.; Gonze, X. [European Theoretical Spectroscopy Facility and Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Chemin des étoiles 8, bte L07.03.01, B-1348 Louvain-la-neuve (Belgium); Marini, A. [Consiglio Nazionale delle Ricerche (CNR), Via Salaria Km 29.3, CP 10, 00016 Monterotondo Stazione (Italy); Verstraete, M. [European Theoretical Spectroscopy Facility and Physique des matériaux et nanostructures, Université de Liège, Allée du 6 Août 17, B-4000 Liège (Belgium)

    2015-09-14

    The renormalization of electronic eigenenergies due to electron-phonon coupling (temperature dependence and zero-point motion effect) is sizable in many materials with light atoms. This effect, often neglected in ab initio calculations, can be computed using the perturbation-based Allen-Heine-Cardona theory in the adiabatic or non-adiabatic harmonic approximation. After a short description of the recent progresses in this field and a brief overview of the theory, we focus on the issue of phonon wavevector sampling convergence, until now poorly understood. Indeed, the renormalization is obtained numerically through a slowly converging q-point integration. For non-zero Born effective charges, we show that a divergence appears in the electron-phonon matrix elements at q → Γ, leading to a divergence of the adiabatic renormalization at band extrema. This problem is exacerbated by the slow convergence of Born effective charges with electronic wavevector sampling, which leaves residual Born effective charges in ab initio calculations on materials that are physically devoid of such charges. Here, we propose a solution that improves this convergence. However, for materials where Born effective charges are physically non-zero, the divergence of the renormalization indicates a breakdown of the adiabatic harmonic approximation, which we assess here by switching to the non-adiabatic harmonic approximation. Also, we study the convergence behavior of the renormalization and develop reliable extrapolation schemes to obtain the converged results. Finally, the adiabatic and non-adiabatic theories, with corrections for the slow Born effective charge convergence problem (and the associated divergence) are applied to the study of five semiconductors and insulators: α-AlN, β-AlN, BN, diamond, and silicon. For these five materials, we present the zero-point renormalization, temperature dependence, phonon-induced lifetime broadening, and the renormalized electronic band structure.

  1. Dependent Narcissism, Organizational Learning, and Human Resource Development

    Science.gov (United States)

    Godkin, Lynn; Allcorn, Seth

    2009-01-01

    Narcissistic leadership can benefit organizational performance. Aberrant narcissism can destroy the psychosocial health of groups, limiting performance. This article examines Dependent Organizational Disorder, a common form of narcissism, which infects leadership, thwarts performance, and interrupts organizational learning. Dependent…

  2. Dependent Narcissism, Organizational Learning, and Human Resource Development

    Science.gov (United States)

    Godkin, Lynn; Allcorn, Seth

    2009-01-01

    Narcissistic leadership can benefit organizational performance. Aberrant narcissism can destroy the psychosocial health of groups, limiting performance. This article examines Dependent Organizational Disorder, a common form of narcissism, which infects leadership, thwarts performance, and interrupts organizational learning. Dependent…

  3. Shape-Dependent Single-Electron Levels for Au Nanoparticles

    Directory of Open Access Journals (Sweden)

    Georgios D. Barmparis

    2016-04-01

    Full Text Available The shape of metal nanoparticles has a crucial role in their performance in heterogeneous catalysis as well as photocatalysis. We propose a method of determining the shape of nanoparticles based on measurements of single-electron quantum levels. We first consider nanoparticles in two shapes of high symmetry: cube and sphere. We then focus on Au nanoparticles in three characteristic shapes that can be found in metal/inorganic or metal/organic compounds routinely used in catalysis and photocatalysis. We describe the methodology we use to solve the Schrödinger equation for arbitrary nanoparticle shape. The method gives results that agree well with analytical solutions for the high-symmetry shapes. When we apply our method in realistic gold nanoparticle models, which are obtained from Wulff construction based on first principles calculations, the single-electron levels and their density of states exhibit distinct shape-dependent features. Results for clean-surface nanoparticles are closer to those for cubic particles, while CO-covered nanoparticles have energy levels close to those of a sphere. Thiolate-covered nanoparticles with multifaceted polyhedral shape have distinct levels that are in between those for sphere and cube. We discuss how shape-dependent electronic structure features could be identified in experiments and thus guide catalyst design.

  4. Dependability in electronic systems mitigation of hardware failures, soft errors, and electro-magnetic disturbances

    CERN Document Server

    Kanekawa, Nobuyasu; Suga, Takashi; Uematsu, Yutaka

    2011-01-01

    Dependability in Electronic Systems presents practical applications for dependable electronic systems, such as train control, automotive control systems and network servers/routers. Readers will find an overview of dependability, enabling them to select the best choice for maximum results.

  5. 2015 Utilization of Electronic Information Resources in Ramat ...

    African Journals Online (AJOL)

    intensely powerful and has permeated all segments and ... Web (WWW) and the internet to make information more accessible. On the other ... access points on the campus and computer literacy is till .... resources are often faster to consult than.

  6. Remote Electronic Resources and the OPAC: Illustrated by the Unisa Library Experience.

    Science.gov (United States)

    Van der Merwe, Ina; Van Eeden, Welna; Hartzer, Sandra

    This paper describes the Unisa (University of South Africa) Library's experience with cataloging remote electronic resources, including electronic journals, electronic text files, online databases, digital images, Unisa campus Web sites, and mailing list discussions. The first section discusses the decision to add bibliographic references for…

  7. Natural Resource Dependency and Decentralized Conservation Within Kanchenjunga Conservation Area Project, Nepal

    Science.gov (United States)

    Parker, Pete; Thapa, Brijesh

    2012-02-01

    Kanchenjunga Conservation Area Project (KCAP) in Nepal is among the first protected areas in the world to institute a completely decentralized system of conservation and development. Proponents of decentralized conservation claim that it increases management efficiency, enhances the responsiveness to local needs, and promotes greater equity among local residents. This study assessed local equity by evaluating the levels of dependencies on natural resources among households and the factors affecting that dependency. Data were collected via detailed surveys among 205 randomly selected households within the KCAP. Natural resource dependency was evaluated by comparing the ratio of total household income to income derived from access to natural resources. Economic, social, and access-related variables were employed to determine potential significant predictors of dependency. Overall, households were heavily dependent on natural resources for their income, especially households at higher elevations and those with more adult members. The households that received remittances were most able to supplement their income and, therefore, drastically reduced their reliance on the access to natural resources. Socio-economic variables, such as land holdings, education, caste, and ethnicity, failed to predict dependency. Household participation in KCAP-sponsored training programs also failed to affect household dependency; however, fewer than 20% of the households had any form of direct contact with KCAP personnel within the past year. The success of the KCAP as a decentralized conservation program is contingent on project capacity-building via social mobilization, training programs, and participatory inclusion in decision making to help alleviate the dependency on natural resources.

  8. Controlling user access to electronic resources without password

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Fred Hewitt

    2017-08-22

    Described herein are devices and techniques for remotely controlling user access to a restricted computer resource. The process includes obtaining an image from a communication device of a user. An individual and a landmark are identified within the image. Determinations are made that the individual is the user and that the landmark is a predetermined landmark. Access to a restricted computing resource is granted based on the determining that the individual is the user and that the landmark is the predetermined landmark. Other embodiments are disclosed.

  9. Discovering Tradeoffs, Vulnerabilities, and Dependencies within Water Resources Systems

    Science.gov (United States)

    Reed, P. M.

    2015-12-01

    There is a growing recognition and interest in using emerging computational tools for discovering the tradeoffs that emerge across complex combinations infrastructure options, adaptive operations, and sign posts. As a field concerned with "deep uncertainties", it is logically consistent to include a more direct acknowledgement that our choices for dealing with computationally demanding simulations, advanced search algorithms, and sensitivity analysis tools are themselves subject to failures that could adversely bias our understanding of how systems' vulnerabilities change with proposed actions. Balancing simplicity versus complexity in our computational frameworks is nontrivial given that we are often exploring high impact irreversible decisions. It is not always clear that accepted models even encompass important failure modes. Moreover as they become more complex and computationally demanding the benefits and consequences of simplifications are often untested. This presentation discusses our efforts to address these challenges through our "many-objective robust decision making" (MORDM) framework for the design and management water resources systems. The MORDM framework has four core components: (1) elicited problem conception and formulation, (2) parallel many-objective search, (3) interactive visual analytics, and (4) negotiated selection of robust alternatives. Problem conception and formulation is the process of abstracting a practical design problem into a mathematical representation. We build on the emerging work in visual analytics to exploit interactive visualization of both the design space and the objective space in multiple heterogeneous linked views that permit exploration and discovery. Many-objective search produces tradeoff solutions from potentially competing problem formulations that can each consider up to ten conflicting objectives based on current computational search capabilities. Negotiated design selection uses interactive visualization

  10. Ferromagnetism and temperature-dependent electronic structure in metallic films

    CERN Document Server

    Herrmann, T

    1999-01-01

    reduced at the surface compared to the inner layers. This observation clearly contradicts the well-known Stoner picture of band magnetism and can be explained in terms of general arguments which are based on exact results in the limit of strong Coulomb interaction. The magnetic behavior of the Hubbard films can be analyzed in detail by inspecting the local quasi particle density of states as well as the wave vector dependent spectral density. The electronic structure is found to be strongly spin-, layer-, and temperature-dependent. The last part of this work is concerned about the temperature-driven reorientation transition in thin metallic films. For the description of the magnetic anisotropy in thin films the dipole interaction as well as the spin-orbit interaction have to be included in the model. By calculating the temperature-dependence of the magnetic anisotropy energy it is found that both types of temperature-driven reorientation transitions, from out-of-plane to in-plane (''Fe-type'') and from in-pla...

  11. Towards a methodology for identifying path dependence in the evolution of human resources practices

    Directory of Open Access Journals (Sweden)

    M. Rosario Perello-Marin

    2010-06-01

    Full Text Available The path dependence approach seems to be well suited for analyzing certain decisions in human resources management. Within this paper, we will try to establish a framework for the application of an evolution model in human resources practices by using cladistics.

  12. An Evaluation of Electronic Product Design Education Using Hypermedia-Resourced Learning Environments

    Science.gov (United States)

    Page, Tom; Thorsteinsson, Gisli

    2006-01-01

    The work outlined here provides a comprehensive report and formative observations of the development and implementation of hypermedia resources for learning and teaching used in conjunction with a managed learning environment (MLE). These resources are used to enhance teaching and learning of an electronics module in product design at final year…

  13. A Study on Developing Evaluation Criteria for Electronic Resources in Evaluation Indicators of Libraries

    Science.gov (United States)

    Noh, Younghee

    2010-01-01

    This study aimed to improve the current state of electronic resource evaluation in libraries. While the use of Web DB, e-book, e-journal, and other e-resources such as CD-ROM, DVD, and micro materials is increasing in libraries, their use is not comprehensively factored into the general evaluation of libraries and may diminish the reliability of…

  14. Managing Selection for Electronic Resources: Kent State University Develops a New System to Automate Selection

    Science.gov (United States)

    Downey, Kay

    2012-01-01

    Kent State University has developed a centralized system that manages the communication and work related to the review and selection of commercially available electronic resources. It is an automated system that tracks the review process, provides selectors with price and trial information, and compiles reviewers' feedback about the resource. It…

  15. Electronic specific heat of anisotropic superconductors and its doping dependence

    Energy Technology Data Exchange (ETDEWEB)

    Perez, L.A. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico (UNAM), A.P. 20-364, 01000, Mexico D.F. (Mexico)]. E-mail: lperez@fisica.unam.mx; Millan, J.S. [Facultad de Ingenieria, Universidad Autonoma del Carmen, 24180, Cd. del Carmen, Campeche (Mexico); Dominguez, B.C. [Facultad de Ingenieria, Universidad Autonoma del Carmen, 24180, Cd. del Carmen, Campeche (Mexico); Intituto de Fisica ' Manuel Sandoval Vallarta' , 78290, San Luis Potosi, S.L.P. (Mexico); Wang, C. [Instituto de Investigaciones en Materiales, UNAM, A.P. 70-360, 04510, Mexico D.F. (Mexico)

    2007-03-15

    The specific heat of electrons in p- and d-symmetry superconducting states (C{sub S}) is comparatively studied within the BCS framework. This study is performed on a square lattice described by a generalized Hubbard model, in which correlated-hopping interactions are included in addition to the repulsive Coulomb ones. The temperature dependences of C{sub S} show a power law behavior, instead of the exponential behavior found in the s channel, and for a given gap amplitude the number of nodes in the gap enhances C{sub S} in the low temperature regime. Moreover, the normalized discontinuity of C{sub S} at the critical temperature (T{sub c}) is smaller than the BCS analytical result of 1.43 for a wide range of electron densities. Finally, the results show that the single-particle van Hove singularity determines the location of the maximum gap, and then the position of the maximum discontinuity of the specific heat at T{sub c}.

  16. A Note on Two-Agent Scheduling with Resource Dependent Release Times on a Single Machine

    Directory of Open Access Journals (Sweden)

    Peng Liu

    2015-01-01

    Full Text Available We consider a scheduling problem in which both resource dependent release times and two agents exist simultaneously. Two agents share a common single machine, and each agent wants to minimize a cost function dependent on its own jobs. The release time of each A-agent’s job is related to the amount of resource consumed. The objective is to find a schedule for the problem of minimizing A-agent’s total amount of resource consumption with a constraint on B-agent’s makespan. The optimal properties and the optimal polynomial time algorithm are proposed to solve the scheduling problem.

  17. Where Do Electronic Books Fit in the College Research Arsenal of Resources?

    Science.gov (United States)

    Barbier, Patricia

    2007-01-01

    Student use of electronic books has become an accepted supplement to traditional resources. Student use and satisfaction was monitored through an online course discussion board. Increased use of electronic books indicate this service is an accepted supplement to the print book collection.

  18. Where Do Electronic Books Fit in the College Research Arsenal of Resources?

    Science.gov (United States)

    Barbier, Patricia

    2007-01-01

    Student use of electronic books has become an accepted supplement to traditional resources. Student use and satisfaction was monitored through an online course discussion board. Increased use of electronic books indicate this service is an accepted supplement to the print book collection.

  19. Overpotential-induced lability of the electronic overlap factor in long-range electrochemical electron transfer: charge and distance dependence

    DEFF Research Database (Denmark)

    Kornyshev, A. A.; Kuznetsov, A. M.; Nielsen, Jens Ulrik;

    2000-01-01

    Long-distance electrochemical electron transfer exhibits approximately exponential dependence on the electron transfer distance. On the basis of a jellium model of the metal surface we show that the slope of the logarithm of the current vs. the transfer distance also depends strongly...

  20. MULER: Building an Electronic Resource Management (ERM Solution at York University

    Directory of Open Access Journals (Sweden)

    Aaron August Lupton

    2012-01-01

    Full Text Available Many university libraries now utilize an Electronic Resource Management (ERM system to assist with operations related to electronic resources. An ERM is a relational database containing information such as suppliers, costs, holdings, and renewal dates for electronic resources, both at the database and title levels. While commercial ERM products are widely available, some institutions are custom building their own ERM in- house. This article describes how York University in Toronto, Canada, did just that by building a system called Managing University Library Electronic Resources (MULER. The article details the background and history of how electronic resources were managed pre-MULER; why a new ERM was needed; the planning process; the current and innovative functions of MULER, including integration of MULER data into York University Libraries search and discovery layer, Vufind; subject tagging in MULER; new functions to be added; and lessons learned from the project. Positive and negative implications of choosing an in-house project over paying for a commercial product are also discussed.

  1. Industrial symbiosis as a countermeasure for resource dependent city: a case study of Guiyang, China

    DEFF Research Database (Denmark)

    Li, Hong; Dong, Liang; Ren, Jingzheng

    2015-01-01

    of sustainability and economy transition solutions become more and more important. Under this condition, this study aims to conduct a comprehensive review on the major projects for a more sustainable future in China's national resource dependent cities and propose a countermeasure for the sustainability transition...... based on the industrial symbiosis concept. Firstly, an investigation on the panoramic view, challenges, transiting policies of China's resource dependent cities' project has been carried out. Subsequently, Guiyang city in Guizhou province of China, as a typical resource dependent city, has been chosen...... as example of industrial and regional symbiosis focusing on the integration and symbiosis of coal, electricity, aluminum, phosphor chemical, iron/steel industry and urban. Then, a quantitative assessment on the environmental benefits has been conducted based on material flow analysis approach. Results...

  2. The National Site Licensing of Electronic Resources: An Institutional Perspective

    Directory of Open Access Journals (Sweden)

    Xiaohua Zhu

    2011-06-01

    Full Text Available While academic libraries in most countries are struggling to negotiate with publishers and vendors individually or collaboratively via consortia, a few countries have experimented with a different model, national site licensing (NSL. Because NSL often involves government and large-scale collaboration, it has the potential to solve many problems in the complex licensing world. However, not many nations have adopted it. This study uses historical research approach and the comparative case study research method to explore the seemingly low level of adoption. The cases include the Canadian National Site Licensing Project (CNSLP, the United Kingdom’s National Electronic Site Licensing Initiative (NESLI, and the United States, which has not adopted NSL. The theoretical framework guiding the research design and data collection is W. Richard Scott’s institutional theory, which utilizes three supporting pillars—regulative, normative, and cultural-cognitive—to analyze institutional processes. In this study, the regulative pillar and the normative pillar of NSL adoption— an institutional construction and change—are examined. Data were collected from monographs, research articles, government documents, and relevant websites. Based on the analysis of these cases, a preliminary model is proposed for the adoption of NSL. The factors that support a country’s adoption of NSL include the need for new institutions, a centralized educational policy-making system and funding system, supportive political trends, and the tradition of cooperation. The factors that may prevent a country from adopting NSL include decentralized educational policy and funding, diversity and the large number of institutions, the concern for the “Big Deal,” and the concern for monopoly.

  3. Analytical Study of Usage of Electronic Information Resources at Pharmacopoeial Libraries in India

    Directory of Open Access Journals (Sweden)

    Sunil Tyagi

    2014-02-01

    Full Text Available The objective of this study is to know the rate and purpose of the use of e-resource by the scientists at pharmacopoeial libraries in India. Among other things, this study examined the preferences of the scientists toward printed books and journals, electronic information resources, and pattern of using e-resources. Non-probability sampling specially accidental and purposive technique was applied in the collection of primary data through administration of user questionnaire. The sample respondents chosen for the study consists of principle scientific officer, senior scientific officer, scientific officer, and scientific assistant of different division of the laboratories, namely, research and development, pharmaceutical chemistry, pharmacovigilance, pharmacology, pharmacogonosy, and microbiology. The findings of the study reveal the personal experiences and perceptions they have had on practice and research activity using e-resource. The major findings indicate that of the total anticipated participants, 78% indicated that they perceived the ability to use computer for electronic information resources. The data analysis shows that all the scientists belonging to the pharmacopoeial libraries used electronic information resources to address issues relating to drug indexes and compendia, monographs, drugs obtained through online databases, e-journals, and the Internet sources—especially polices by regulatory agencies, contacts, drug promotional literature, and standards.

  4. Connecting knowledge resources to the veterinary electronic health record: opportunities for learning at point of care.

    Science.gov (United States)

    Alpi, Kristine M; Burnett, Heidi A; Bryant, Sheila J; Anderson, Katherine M

    2011-01-01

    Electronic health records (EHRs) provide clinical learning opportunities through quick and contextual linkage of patient signalment, symptom, and diagnosis data with knowledge resources covering tests, drugs, conditions, procedures, and client instructions. This paper introduces the EHR standards for linkage and the partners-practitioners, content publishers, and software developers-necessary to leverage this possibility in veterinary medicine. The efforts of the American Animal Hospital Association (AAHA) Electronic Health Records Task Force to partner with veterinary practice management systems to improve the use of controlled vocabulary is a first step in the development of standards for sharing knowledge at the point of care. The Veterinary Medical Libraries Section (VMLS) of the Medical Library Association's Task Force on Connecting the Veterinary Health Record to Information Resources compiled a list of resources of potential use at point of care. Resource details were drawn from product Web sites and organized by a metric used to evaluate medical point-of-care resources. Additional information was gathered from questions sent by e-mail and follow-up interviews with two practitioners, a hospital network, two software developers, and three publishers. Veterinarians with electronic records use a variety of information resources that are not linked to their software. Systems lack the infrastructure to use the Infobutton standard that has been gaining popularity in human EHRs. While some veterinary knowledge resources are digital, publisher sites and responses do not indicate a Web-based linkage of veterinary resources with EHRs. In order to facilitate lifelong learning and evidence-based practice, veterinarians and educators of future practitioners must demonstrate to veterinary practice software developers and publishers a clinically-based need to connect knowledge resources to veterinary EHRs.

  5. Improving access to information – defining core electronic resources for research and wellbeing

    Directory of Open Access Journals (Sweden)

    Kristiina Hormia-Poutanen

    2007-11-01

    Full Text Available Research and innovation are listed as the key success factors for the future development of Finnish prosperity and the Finnish economy. The Finnish libraries have developed a scenario to support this vision. University, polytechnic and research institute libraries as well as public libraries have defined the core electronic resources necessary to improve access to information in Finland. The primary aim of this work has been to provide information and justification for central funding for electronic resources to support the national goals. The secondary aim is to help with the reallocation of existing central funds to better support access to information.

  6. Dependence of geosynchronous relativistic electron enhancements on geomagnetic parameters

    CERN Document Server

    Dmitriev, A V

    2014-01-01

    Relativistic electron fluxes observed in geosynchronous orbit by GOES-8 in 1997 to 2000 were considered as a complex function of geomagnetic indices PC, Kp, and Dst as well as parameters of the magnetosphere size, subsolar Rs and terminator Rf magnetopause distances. A geosynchronous relativistic electron enhancement (GREE) is determined as daily maximal electron flux exceeding the upper root mean square deviation (RMSD) threshold of about 1500 (cm2s sr)-1. Comparison analysis of the GREE dynamics and geomagnetic conditions on the rising phase of current solar cycle revealed suppression of the relativistic electron enhancements by substantially increased strong geomagnetic activity in the solar maximum. Statistical consideration of a relationship between the GREEs and the geomagnetic parameters showed that the most important parameters controlling the geosynchronous relativistic electron enhancements were 4-day averaged Kp index, PC index and magnetopause termination distance Rf delayed respectively on 3 and ...

  7. Elektronik Bilgi Kaynaklarının Seçimi / Selection of Electronic Information Resources

    Directory of Open Access Journals (Sweden)

    Pınar Al

    2003-04-01

    Full Text Available For many years, library users have used only from the printed media in order to get the information that they have needed. Today with the widespread use of the Web and the addition of electronic information resources to library collections, the use of information in the electronic environment as well as in printed media is started to be used. In time, such types of information resources as, electronic journals, electronic books, electronic encyclopedias, electronic dictionaries and electronic theses have been added to library collections. In this study, selection criteria that can be used for electronic information resources are discussed and suggestions are provided for libraries that try to select electronic information resources for their collections.

  8. Preferred Psychological Internet Resources for Addressing Anxiety Disorders, Parenting Problems, Eating Disorders, and Chemical Dependency.

    Science.gov (United States)

    Morse, Laura; Doran, Matt; Simonin, Danielle; Smith, Allyson; Maloney, Colleen; Wright, Cara; Underwood, Michelle; Hoppel, Andrea; O'Donnell, Shannon; Chambliss, Catherine

    Although the Internet offers information about psychological problems and support resources for behavioral health problems, the quality of this information varies widely. So as to offer guidance in this area, preferred sites pertaining to anxiety disorders, parenting problems, eating disorders, and chemical dependency were analyzed. A total of 365…

  9. High Power Distance Enhances Employees' Preference for Likable Managers: A Resource Dependency Perspective

    Science.gov (United States)

    Wei, Cong; Sun, Xiaomin; Liu, Jia; Zhou, Chunfang; Xue, Gang

    2017-01-01

    Is a manager's likability important from an employee's perspective? Research results in this field are scant and inconsistent. The current study explored employees' response to managers' likability and the moderating effect of power distance at both the cultural and individual levels. In study 1, following the countercultural priming experimental paradigm proposed by Van den Bos et al. (2013), 121 college students from China (a high power distance culture) and 99 college students from Denmark (a low power distance culture) were randomly assigned to either a countercultural (experimental) condition or a control condition. All participants were required to complete a manager selection task using the zero-acquaintance paradigm to measure their preference for likable managers. The results confirmed the moderating role of power distance at the cultural level. Study 2 further explored the moderating effect of power distance orientation at the individual level, as well as the boundary condition of the degree of resource dependence from the employee's perspective. One hundred and three Chinese participants with work experience were randomly assigned to either the subordinate perspective (high resource dependence) or the HR department perspective (low resource dependence) condition and completed the same task as in study 1. The results suggested that high power distance-oriented participants demonstrate stronger preference for likable manager candidates than do low power distance-oriented participants. In addition, these findings hold only when employees expect a high resource dependence relation with the manager. Theoretical and practical implications of the research findings and future research directions were discussed. PMID:28119654

  10. Managing Resource Dependence Difficulties in African Higher Education: The Case of Multiple Exchange Relationships

    Science.gov (United States)

    Wangenge-Ouma, Gerald

    2011-01-01

    The paper has a twofold structure and focus. The first part is an examination of the funding challenges facing African universities resulting mainly from public finance difficulties, and the second part is a case study of how some Kenyan and South African public universities have attempted to mitigate resource dependence difficulties through…

  11. An Emergy-Based Hybrid Method for Assessing Sustainability of the Resource-Dependent Region

    Directory of Open Access Journals (Sweden)

    Lulu Qu

    2017-01-01

    Full Text Available As the natural resources are getting exhausted, the concept of sustainable development of regions has received increasing attention, especially for resource-dependent cities. In this paper, an innovative method based on emergy analysis and the Human Impact Population Affluence Technology (IPAT model is developed to analyze the quantitative relationship of economic growth, energy consumption and its overall sustainability level. Taiyuan, a traditional, resource-dependent city in China, is selected as the case study region. The main results show that the total emergy of Taiyuan increased from 9.023 × 1023 sej in 2007 to 9.116 × 1023 sej in 2014, with a 38% decline in non-renewable emergy and an increase of imported emergy up to 125%. The regional emergy money ratio (EMB was reduced by 48% from 5.31 × 1013 sej/$ in 2007 to 2.74 × 1013 sej/$ in 2014, indicating that the increasing speed of consuming resources and energy was faster than the increase of GDP, and that Taiyuan’s money purchasing power declined. The lower emergy sustainability index (ESI indicates that Taiyuan was explored and produced large quantities of mineral resources, which puts more stress on the environment as a consequence, and that this is not sustainable in the long run. The IPAT analysis demonstrates that Taiyuan sticks to the efforts of energy conservation and environmental protection. In order to promote regional sustainable development, it is necessary to have an integrated effort. Policy insights suggest that resourceful regions should improve energy and resource efficiency, optimize energy and resourceful structure and carry out extensive public participation.

  12. Using Electronic Information Resources Centers by Faculty Members at University Education: Competencies, Needs and Challenges

    Science.gov (United States)

    Abouelenein, Yousri

    2017-01-01

    This study aimed at investigating the factual situation of electronic information resources centers to faculty members at university education. Competencies that faculty members should possess regarding this issue were determined. Also their needs for (scientific research skills and teaching) were assessed. In addition, problems that hinder their…

  13. Localising versus standardising electronic human resource management: complexities and tensions between HRM and IT departments

    NARCIS (Netherlands)

    Tate, Mary; Furtmueller, E.; Wilderom, C.P.M.

    2013-01-01

    In this paper, we provide an analysis of the complexities involved during global e-HRM (Electronic Human Resource Management) implementation. We present findings from a case study on the challenge of global integration versus local responsiveness of e-HRM systems. We take a local site lens, analysin

  14. Use of Electronic Information Resources among Research Scholars in the Islamia University of Bahawalpur, Pakistan

    Science.gov (United States)

    Amjad, Anam; Ahmed, Shamshad; Bin Naeem, Salman

    2013-01-01

    This study examined the use of electronic resources among academic scholars of The Islamia University of Bahawalpur (IUB), Punjab, Pakistan. A quantitative survey was found most convenient and useful for this study. The total population of the study was 169 research students in IUB. The response rate was 79% and 133 utilizable responses were coded…

  15. The Acquisition and Management of Electronic Resources: Can Use Justify Cost?

    Science.gov (United States)

    Koehn, Shona L.; Hawamdeh, Suliman

    2010-01-01

    As library collections increasingly become digital, libraries are faced with many challenges regarding the acquisition and management of electronic resources. Some of these challenges include copyright and fair use, the first-sale doctrine, licensing versus ownership, digital preservation, long-term archiving, and, most important, the issue of…

  16. 电子资源的编目策略%Cataloging Strategies of Electronic Resources

    Institute of Scientific and Technical Information of China (English)

    王亚林

    2012-01-01

    Compared with traditional paper resources, electronic resources have following characteristics which determine different cataloging strategies from paper resources. These characteristics are huge quantity, updating rapidly, coexistence of a variety of manifestations. The source data of electronic resources is usually provided by the database agent. The cataloging of electronic resources is based on the Chapter IX of Anglo-American Cataloging Rules, Library of Congress Rule Interpretations and rules of Cooperative Online Serials. There are two major cataloging methods for electronic resources abroad, they are single record approach and separate record approach. Peking University Library chooses the latter method and batches cataloging automatically using the source data.%电子资源吲传统纸质资源相比,具有数量大、更新快、多种载体表现并行等特点,且大部分出版机构能够提供数据源数据。这些特点决定了.电子资源应采取与纸质文献不同的编目策略。电子资源编日的主要依据是《英美编日条例》的第9章、美国《国会图书馆条例解释》及全美期刊合作编目计划的规定。对于电子资源的编目,国外有单一记录编目法和分散记录编目法。北京大学图书馆采用后者,同时利用数据源数据批舒自动编目。

  17. Evolution Stages of Oasis Economy and Its Dependence on Natural Resources in Tarim River Basin

    Institute of Scientific and Technical Information of China (English)

    QIAO Xuning; YANG Degang; ZHANG Xinhuan

    2009-01-01

    This paper examines spatio-temporal characteristics of an oasis economy and its relationship with water and mineral resources in the Turim River Basin from 1965 to 2005. A spatial autocorrelation model, the center of gravity model, and index system of the regional central city are used to probe the evolution laws of spatial structure of oasis economy. The study finds that: 1) The economic centre of gravity, whose variation track during this period follows linear rote law, was moving from headstream to middle reaches of the Tarim River. 2) Positive spatial autocorrelation which showed a waving and ascending trend of regional economy was significant and the neighbor effect of regional economic growth was strengthened continuously. 3) The regional economic centre was located in Hotan City before 1980, moved to Aksu City during the 1980s and to Korla City after 1990. We conclude that above all, during the recent four decades the evolution of the oasis economy in this region has gone through three stages: a traditional agriculture stage (before 1980), oasis agriculture and agricultural product processing stage (1980-1990) and oasis energy industry stage (after 1990). Furthermore, the dependence degree of the oasis economy on natural resources in different stages are studied by using dominance index, regression model, and grey relation method, which shows that an oasis economy highly depends on water resources in the oasis agriculture and agricultural product processing stage while it depends more on mineral resources such as oil and natural gas during the oasis energy industry stage.

  18. Power resource management and low-power remote wireless RF electronics

    Science.gov (United States)

    Jannson, Tomasz; Forrester, Thomas; Degrood, Kevin; Lee, Kang; Gans, Eric; Walter, Kevin

    2009-05-01

    Battery power resource management becomes a critical issue in the case of self-powered remote wireless RF electronics, where the basic parameter is time of system operation before battery recharging or battery replacement. In such cases, very often related to physical protection against antitampering (AT), proper theoretical modeling of a battery driven power supply in the context of a given digital electronic system is of utmost importance. Such modeling should include various types of batteries (primary and secondary), various self-discharge processes in different temperatures, and even energy harvesting, the latter to supply power for long-term content, low-power electronic subsystems. In this paper we analyze simple modeling of resource power management, including variations of all of these parameters and energy harvesting.

  19. Energy Dependence of SEP Electron and Proton Onset Times

    CERN Document Server

    Xie, Hong; Gopalswamy, Nat; Cyr, Orville St

    2016-01-01

    We study the large solar energetic particle (SEP) events that were detected by GOES in the $>$ 10 MeV energy channel during December 2006 to March 2014. We derive and compare solar particle release (SPR) times for the 0.25--10.4 MeV electrons and 10--100 MeV protons for the 28 SEP events. In the study, the electron SPR times are derived with the time-shifting analysis (TSA) and the proton SPR times are derived using both the TSA and the velocity dispersion analysis (VDA). Electron anisotropies are computed to evaluate the amount of scattering for the events under study. Our main results include: 1)near-relativistic electrons and high-energy protons are released at the same time within 8 min for most (16 of 23) SEP events. 2)There exists a good correlation between electron and proton acceleration, peak intensity and intensity time profiles. 3) The TSA SPR times for 90.5 MeV and 57.4 MeV protons have maximum errors of 6 min and 10 min compared to the proton VDA release times, respectively, while the maximum err...

  20. Temperature dependence of the electronic gaps of semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Cardona, M.; Kremer, R.K.

    2014-11-28

    Understanding the temperature dependence of the direct and indirect gaps is indispensable for optimizing the applications of semiconductors. Experimentally, this temperature dependence can be very precisely determined by ellipsometry, by absorption or by luminescence spectroscopy. We have re-analyzed the temperature dependence of the direct and indirect gaps of some prominent tetrahedral semiconductors and improved available fits by applying a simple modified approach which uses statistical factors and the knowledge of prominent transverse-acoustic and transverse-optical bands in the measured or calculated phonon density of states of the semiconductors under consideration. - Highlights: • Re-analysis of the temperature dependence of the gaps of tetrahedral semiconductors • Modeling of the temperature dependence of the gaps of tetrahedral semiconductors • Simplified modeling using statistical factors and prominent phonon bands.

  1. Spatially dependent electron-positron pair creation rate

    Science.gov (United States)

    Lv, Q. Z.; Unger, J.; Li, Y. T.; Su, Q.; Grobe, R.

    2016-11-01

    The vacuum breakdown process in an inhomogeneous supercritical electric field of finite extension is examined. By probing the electron-positron pair creation zone with incoming electrons that have controlled velocities, we can address the fundamental question of where the electrons are being created from the vacuum. In contrast to what one might expect, the spatial regions of most likely pair creation are not necessarily those where the electric-field strength is largest. In fact, the creation regions are determined solely by energetic considerations and particles can therefore be created in spatial regions where the local field strength is far below the Schwinger threshold. These predictions are also supported independently by spatial probability densities obtained by extrapolation as well as by classical and quantum-mechanical analysis.

  2. Electronic density of states in sequence dependent DNA molecules

    Science.gov (United States)

    de Oliveira, B. P. W.; Albuquerque, E. L.; Vasconcelos, M. S.

    2006-09-01

    We report in this work a numerical study of the electronic density of states (DOS) in π-stacked arrays of DNA single-strand segments made up from the nucleotides guanine G, adenine A, cytosine C and thymine T, forming a Rudin-Shapiro (RS) as well as a Fibonacci (FB) polyGC quasiperiodic sequences. Both structures are constructed starting from a G nucleotide as seed and following their respective inflation rules. Our theoretical method uses Dyson's equation together with a transfer-matrix treatment, within an electronic tight-binding Hamiltonian model, suitable to describe the DNA segments modelled by the quasiperiodic chains. We compared the DOS spectra found for the quasiperiodic structure to those using a sequence of natural DNA, as part of the human chromosome Ch22, with a remarkable concordance, as far as the RS structure is concerned. The electronic spectrum shows several peaks, corresponding to localized states, as well as a striking self-similar aspect.

  3. Identifying and evaluating electronic learning resources for use in adult-gerontology nurse practitioner education.

    Science.gov (United States)

    Thompson, Hilaire J; Belza, Basia; Baker, Margaret; Christianson, Phyllis; Doorenbos, Ardith; Nguyen, Huong

    2014-01-01

    Enhancing existing curricula to meet newly published adult-gerontology advanced practice registered nurse (APRN) competencies in an efficient manner presents a challenge to nurse educators. Incorporating shared, published electronic learning resources (ELRs) in existing or new courses may be appropriate in order to assist students in achieving competencies. The purposes of this project were to (a) identify relevant available ELR for use in enhancing geriatric APRN education and (b) to evaluate the educational utility of identified ELRs based on established criteria. A multilevel search strategy was used. Two independent team members reviewed identified ELR against established criteria to ensure utility. Only resources meeting all criteria were retained. Resources were found for each of the competency areas and included formats such as podcasts, Web casts, case studies, and teaching videos. In many cases, resources were identified using supplemental strategies and not through traditional search or search of existing geriatric repositories. Resources identified have been useful to advanced practice educators in improving lecture and seminar content in a particular topic area and providing students and preceptors with additional self-learning resources. Addressing sustainability within geriatric APRN education is critical for sharing of best practices among educators and for sustainability of teaching and related resources. © 2014.

  4. The links between resource dependency and attitude of commercial fishers to coral reef conservation in the Red Sea.

    Science.gov (United States)

    Marshall, Nadine A; Marshall, Paul A; Abdulla, Ameer; Rouphael, Tony

    2010-06-01

    The imperative to further constrain extractive uses of natural resources will strengthen as resources degrade through over-use or exposure to climate changes. Here, we explore an approach to increase the support for marine conservation among coral reef fishers. We explore the proposition that resource dependency in the Egyptian Red Sea can act as a barrier to conservation. We administered face-to-face surveys to 49% of the fishing industry to: (i) identify the level of compliance to the local marine protected area (MPA), (ii) assess the level of dependency on marine resources in the region and (iii) examine the relationship between resource dependency and conservation attitudes. Only 11.4% of fishers were aware of the MPA. Fishers were mostly limited in their social flexibility and livelihood options. Results suggest that resource dependency is highly and negatively correlated with conservation attitudes suggesting that management efforts need to seriously focus on reducing dependency if conservation goals are to be met.

  5. Sequence dependence of electron-induced DNA strand breakage revealed by DNA nanoarrays

    DEFF Research Database (Denmark)

    Keller, Adrian; Rackwitz, Jenny; Cauët, Emilie

    2014-01-01

    The electronic structure of DNA is determined by its nucleotide sequence, which is for instance exploited in molecular electronics. Here we demonstrate that also the DNA strand breakage induced by low-energy electrons (18 eV) depends on the nucleotide sequence. To determine the absolute cross...

  6. Library Electronic Resource Sharing Among Liberal Arts Colleges: ACS Palladian Alliance Project

    Directory of Open Access Journals (Sweden)

    Wenxian Zhang

    1997-03-01

    Full Text Available 無Effective electronic resource sharing is critical to library information services of the 1990s. Explosion of data and increased cost of information force libraries to work together, and technological advancements present the library service profession a platform for resource sharing. The Palladian Alliance Project of the Associated Colleges of the South is designed to provides ACS member institutions an effective means to enhance information access for their faculty and students, and achieve significant cost containment in the years to come.

  7. Structure dependent spin selectivity in electron transport through oligopeptides

    Science.gov (United States)

    Kiran, Vankayala; Cohen, Sidney R.; Naaman, Ron

    2017-03-01

    The chiral-induced spin selectivity (CISS) effect entails spin-selective electron transmission through chiral molecules. In the present study, the spin filtering ability of chiral, helical oligopeptide monolayers of two different lengths is demonstrated using magnetic conductive probe atomic force microscopy. Spin-specific nanoscale electron transport studies elucidate that the spin polarization is higher for 14-mer oligopeptides than that of the 10-mer. We also show that the spin filtering ability can be tuned by changing the tip-loading force applied on the molecules. The spin selectivity decreases with increasing applied force, an effect attributed to the increased ratio of radius to pitch of the helix upon compression and increased tilt angles between the molecular axis and the surface normal. The method applied here provides new insights into the parameters controlling the CISS effect.

  8. Shape-Dependent Single-Electron Levels for Au Nanoparticles

    OpenAIRE

    Barmparis, Georgios D.; Georgios Kopidakis; Remediakis, Ioannis N.

    2016-01-01

    The shape of metal nanoparticles has a crucial role in their performance in heterogeneous catalysis as well as photocatalysis. We propose a method of determining the shape of nanoparticles based on measurements of single-electron quantum levels. We first consider nanoparticles in two shapes of high symmetry: cube and sphere. We then focus on Au nanoparticles in three characteristic shapes that can be found in metal/inorganic or metal/organic compounds routinely used in catalysis and photocata...

  9. Availability, Level of Use and Constraints to Use of Electronic Resources by Law Lecturers in Public Universities in Nigeria

    Science.gov (United States)

    Amusa, Oyintola Isiaka; Atinmo, Morayo

    2016-01-01

    (Purpose) This study surveyed the level of availability, use and constraints to use of electronic resources among law lecturers in Nigeria. (Methodology) Five hundred and fifty-two law lecturers were surveyed and four hundred and forty-two responded. (Results) Data analysis revealed that the level of availability of electronic resources for the…

  10. Using Context Dependent Semantic Similarity to Browse Information Resources: an Application for the Industrial Design

    CERN Document Server

    Albertoni, Riccardo

    2010-01-01

    This paper deals with the semantic interpretation of information resources (e.g., images, videos, 3D models). We present a case study of an approach based on semantic and context dependent similarity applied to the industrial design. Different application contexts are considered and modelled to browse a repository of 3D digital objects according to different perspectives. The paper briefly summarises the basic concepts behind the semantic similarity approach and illustrates its application and results.

  11. Resource Dependence Relationship between Grass-roots Government and Farmers’ Specialized Cooperatives

    Institute of Scientific and Technical Information of China (English)

    Xuebin SHEN; Yi CAI

    2016-01-01

    Based on theories of resource dependence and government functions,this paper analyzed benefit interaction between grass-roots government and farmers’ specialized cooperatives in Hubei Province. It was intended to make clear the path dependence relationship between grassroots government and farmers’ specialized cooperatives and find out problems in between. Besides,from the perspective of grass-roots government and farmers’ specialized cooperatives,it came up with corresponding recommendations,to promote constant improvement of farmers’ specialized cooperatives,and help them to become key forces of leading farmers to get rich,pull agricultural economic development,and promote new socialist countryside construction.

  12. Resource CoAllocation for Scheduling Tasks with Dependencies, in Grid

    CERN Document Server

    Moise, Diana; Pop, Florin; Cristea, Valentin

    2011-01-01

    Scheduling applications on wide-area distributed systems is useful for obtaining quick and reliable results in an efficient manner. Optimized scheduling algorithms are fundamentally important in order to achieve optimized resources utilization. The existing and potential applications include many fields of activity like satellite image processing and medicine. The paper proposes a scheduling algorithm for tasks with dependencies in Grid environments. CoAllocation represents a strategy that provides a schedule for task with dependencies, having as main purpose the efficiency of the schedule, in terms of load balancing and minimum time for the execution of the tasks.

  13. A consumer-resource approach to the density-dependent population dynamics of mutualism.

    Science.gov (United States)

    Holland, J Nathaniel; DeAngelis, Donald L

    2010-05-01

    Like predation and competition, mutualism is now recognized as a consumer-resource (C-R) interaction, including, in particular, bi-directional (e.g., coral, plant-mycorrhizae) and uni-directional (e.g., ant-plant defense, plant-pollinator) C-R mutualisms. Here, we develop general theory for the density-dependent population dynamics of mutualism based on the C-R mechanism of interspecific interaction. To test the influence of C-R interactions on the dynamics and stability of bi- and uni-directional C-R mutualisms, we developed simple models that link consumer functional response of one mutualistic species with the resources supplied by another. Phase-plane analyses show that the ecological dynamics of C-R mutualisms are stable in general. Most transient behavior leads to an equilibrium of mutualistic coexistence, at which both species densities are greater than in the absence of interactions. However, due to the basic nature of C-R interactions, certain density-dependent conditions can lead to C-R dynamics characteristic of predator-prey interactions, in which one species overexploits and causes the other to go extinct. Consistent with empirical phenomena, these results suggest that the C-R interaction can provide a broad mechanism for understanding density-dependent population dynamics of mutualism. By unifying predation, competition, and mutualism under the common ecological framework of consumer-resource theory, we may also gain a better understanding of the universal features of interspecific interactions in general.

  14. A consumer-resource approach to the density-dependent population dynamics of mutualism

    Science.gov (United States)

    Holland, J. Nathaniel; DeAngelis, Donald L.

    2010-01-01

    Like predation and competition, mutualism is now recognized as a consumer resource (C-R) interaction, including, in particular, bi-directional (e.g., coral, plant- mycorrhizae) and uni-directional (e.g., ant-plant defense, plant-pollinator) C-R mutualisms. Here, we develop general theory for the density-dependent population dynamics of mutualism based on the C-R mechanism of interspecific interaction. To test the influence of C-R interactions on the dynamics and stability of bi- and uni-directional C-R mutualisms, we developed simple models that link consumer functional response of one mutualistic species with the resources supplied by another. Phase-plane analyses show that the ecological dynamics of C-R mutualisms are stable in general. Most transient behavior leads to an equilibrium of mutualistic coexistence, at which both species densities are greater than in the absence of interactions. However, due to the basic nature of C-R interactions, certain density-dependent conditions can lead to C-R dynamics characteristic of predator-prey interactions, in which one species overexploits and causes the other to go extinct. Consistent with empirical phenomena, these results suggest that the C-R interaction can provide a broad mechanism for understanding density-dependent population dynamics of mutualism. By unifying predation, competition, and mutualism under the common ecological framework of consumer-resource theory, we may also gain a better understanding of the universal features of interspecific interactions in general.

  15. Doping-dependent magnetization plateaus of a coupled spin-electron chain: exact results

    Science.gov (United States)

    Strečka, Jozef; Čisárová, Jana

    2016-10-01

    A coupled spin-electron chain composed of localized Ising spins and mobile electrons is exactly solved in an external magnetic field within the transfer-matrix method. The ground-state phase diagram involves in total seven different ground states, which differ in the number of mobile electrons per unit cell and the respective spin arrangements. A rigorous analysis of the low-temperature magnetization process reveals doping-dependent magnetization plateaus, which may be tuned through the density of mobile electrons. It is demonstrated that the fractional value of the electron density is responsible for an enhanced magnetocaloric effect due to an annealed bond disorder of the mobile electrons.

  16. Resource-mediated condition dependence in sexually dichromatic butterfly wing coloration.

    Science.gov (United States)

    Kemp, Darrell J

    2008-09-01

    Theory predicts that traits subject to strong sexual selection should evolve to be more exaggerated and developmentally integrated than nonsexual traits, thus leading to heightened condition dependence. Until recently, however, efforts to evaluate this prediction have suffered from either a purely correlational (nonmanipulative) approach, or from using manipulations of doubtful ecological relevance. Here I address these issues by integrating observation and manipulation to study condition- and sex-related color variation in a butterfly. The focal species, Eurema hecabe (Pieridae), possesses three sexually homologous and morphogenetically discrete dorsal wing color elements-coherently scattered ultraviolet (UV), pteridine yellow, and melaninic black. The UV is most strongly sexually selected, and is also the only color element with restricted distribution across female wings. Condition dependence and sexual dichromatism were pervasive, characterizing all color traits except the melanic black, and acting such that low condition males resembled high condition females. Although female coloration tended to exhibit greater phenotypic variation, size-scaled UV was more variable and condition dependent in males. Importantly, manipulation of larval resources was sufficient to closely reconstruct the extent and patterns of field-observed phenotypic variation in condition, and color trait expression, which implicates larval resource acquisition as a primary driver of condition dependence. These results support theories regarding phenotypic variation in sexually selected traits.

  17. An examination of scale-dependent resource use by Eastern Hognose snakes in southcentral New Hampshire.

    Energy Technology Data Exchange (ETDEWEB)

    LaGory, K. E.; Walston, L. J.; Goulet, C; Van Lonkhuyzen, R. A.; Najjar, S.; Andrews, C.; Environmental Science Division; Univ. of New Hampshire; U.S. Air Force

    2009-11-01

    The decline of many snake populations is attributable to habitat loss, and knowledge of habitat use is critical to their conservation. Resource characteristics (e.g., relative availability of different habitat types, soils, and slopes) within a landscape are scale-dependent and may not be equal across multiple spatial scales. Thus, it is important to identify the relevant spatial scales at which resource selection occurs. We conducted a radiotelemetry study of eastern hognose snake (Heterodon platirhinos) home range size and resource use at different hierarchical spatial scales. We present the results for 8 snakes radiotracked during a 2-year study at New Boston Air Force Station (NBAFS) in southern New Hampshire, USA, where the species is listed by the state as endangered. Mean home range size (minimum convex polygon) at NBAFS (51.7 {+-} 14.7 ha) was similar to that reported in other parts of the species range. Radiotracked snakes exhibited different patterns of resource use at different spatial scales. At the landscape scale (selection of locations within the landscape), snakes overutilized old-field and forest edge habitats and underutilized forested habitats and wetlands relative to availability. At this scale, snakes also overutilized areas containing sandy loam soils and areas with lower slope (mean slope = 5.2% at snake locations vs. 6.7% at random locations). We failed to detect some of these patterns of resource use at the home range scale (i.e., within the home range). Our ability to detect resource selection by the snakes only at the landscape scale is likely the result of greater heterogeneity in macrohabitat features at the broader landscape scale. From a management perspective, future studies of habitat selection for rare species should include measurement of available habitat at spatial scales larger than the home range. We suggest that the maintenance of open early successional habitats as a component of forested landscapes will be critical for the

  18. Temperature dependence of Hall electron density of GaN-based heterostructures

    Institute of Scientific and Technical Information of China (English)

    Zhang Jin-Feng; Zhang Jin-Cheng; Hao Yue

    2004-01-01

    The theoretic calculation and analysis of the temperature dependence of Hall electron density of a sample AlGaN/GaN heterostructure has been carried out in the temperature range from 77 to 300K. The densities of the twodimensional electron gas and the bulk electrons are solved by self-consistent calculation of one-dimensional Schrodinger and Poisson equations at different temperatures, which allow for the variation of energy gap and structure strain, and are used for evaluation of the temperature dependence of Hall electron density. The calculated Hall electron density agrees with the measured one quite well with the appropriate bulk mobility data. Analysis revealed that for the temper ature range considered, even in the heterostructures with a small bulk conductance the factors that determine the Hall mobility and electron density could be of different sources, and not just the two-dimensional electron gas as generally supposed.

  19. Electron mean free path dependence of the vortex surface impedance

    Science.gov (United States)

    Checchin, M.; Martinello, M.; Grassellino, A.; Romanenko, A.; Zasadzinski, J. F.

    2017-03-01

    In the present study the radio-frequency complex response of trapped vortices in superconductors is calculated and compared to experimental data previously published. The motion equation for a magnetic flux line is solved assuming a bi-dimensional and mean-free-path-dependent Lorentzian-shaped pinning potential. The resulting surface resistance shows the unprecedented bell-shaped trend as a function of the mean-free-path observed in our previous experimental work. We demonstrate that such bell-shaped trend of the surface resistance as a function of the mean-free-path may be described as the interplay of the two limiting regimes of the surface resistance, for low and large mean-free-path values: pinning and flux-flow regimes respectively. Since the possibility of defining the pinning potential at different locations from the surface and with different strengths, we discuss how the surface resistance is affected by different configurations of pinning sites. By tackling the frequency dependence of the surface resistance, we also demonstrate that the separation between pinning- and flux-flow-dominated regimes cannot be determined only by the depinning frequency. The dissipation regime can be tuned either by acting on the frequency or on the mean-free-path value.

  20. Potential resource and toxicity impacts from metals in waste electronic devices.

    Science.gov (United States)

    Woo, Seung H; Lee, Dae Sung; Lim, Seong-Rin

    2016-04-01

    As a result of the continuous release of new electronic devices, existing electronic devices are quickly made obsolete and rapidly become electronic waste (e-waste). Because e-waste contains a variety of metals, information about those metals with the potential for substantial environmental impact should be provided to manufacturers, recyclers, and disposers to proactively reduce this impact. This study assesses the resource and toxicity (i.e., cancer, noncancer, and ecotoxicity) potentials of various heavy metals commonly found in e-waste from laptop computers, liquid-crystal display (LCD) monitors, LCD TVs, plasma TVs, color cathode ray tube (CRT) TVs, and cell phones and then evaluates such potentials using life cycle impact-based methods. Resource potentials derive primarily from Cu, Sb, Ag, and Pb. Toxicity potentials derive primarily from Pb, Ni, and Hg for cancer toxicity; from Pb, Hg, Zn, and As for noncancer toxicity; and from Cu, Pb, Hg, and Zn for ecotoxicity. Therefore, managing these heavy metals should be a high priority in the design, recycling, and disposal stages of electronic devices.

  1. DFPT approach to the temperature dependence of electronic band energies

    Science.gov (United States)

    Boulanger, Paul; Cote, Michel; Gonze, Xavier

    2010-03-01

    The energy bands of semiconductors exhibit significant shifts and broadening with temperature at constant volume. This is an effect of the direct renormalization of band energies due to electron-phonon interactions. In search of an efficient linear response DFT approach to this effect, beyond semi-empirical approximation or frozen- phonon DFT, we have implemented formulas derived by Allen and Heine [J. Phys. C 9, 2305 (1976)] inside the ABINIT package. We have found that such formulas need a great number of bands, O(1000), to properly converge the thermal corrections of deep potential well atoms, i.e. elements of the first row. This leads to heavy computational costs even for simple systems like diamond. The DFPT formalism can be used to circumvent entirely the need for conduction bands by computing the first-order wave-functions using the self-consistent Sternheimer equation. We will compare the results of both formalism demonstrating that the DFPT approach reproduces the correct converged results of the formulas of Allen and Heine.

  2. Model of e-learning with electronic educational resources of new generation

    Directory of Open Access Journals (Sweden)

    A. V. Loban

    2017-01-01

    Full Text Available Purpose of the article: improving of scientific and methodical base of the theory of the е-learning of variability. Methods used: conceptual and logical modeling of the е-learning of variability process with electronic educational resource of new generation and system analysis of the interconnection of the studied subject area, methods, didactics approaches and information and communication technologies means. Results: the formalization complex model of the е-learning of variability with electronic educational resource of new generation is developed, conditionally decomposed into three basic components: the formalization model of the course in the form of the thesaurusclassifier (“Author of e-resource”, the model of learning as management (“Coordination. Consultation. Control”, the learning model with the thesaurus-classifier (“Student”. Model “Author of e-resource” allows the student to achieve completeness, high degree of didactic elaboration and structuring of the studied material in triples of variants: modules of education information, practical task and control tasks; the result of the student’s (author’s of e-resource activity is the thesaurus-classifier. Model of learning as management is based on the principle of personal orientation of learning in computer environment and determines the logic of interaction between the lecturer and the student when determining the triple of variants individually for each student; organization of a dialogue between the lecturer and the student for consulting purposes; personal control of the student’s success (report generation and iterative search for the concept of the class assignment in the thesaurus-classifier before acquiring the required level of training. Model “Student” makes it possible to concretize the learning tasks in relation to the personality of the student and to the training level achieved; the assumption of the lecturer about the level of training of a

  3. Dependent-Chance Goal Programming for Water Resources Management under Uncertainty

    Directory of Open Access Journals (Sweden)

    Haiying Guo

    2016-01-01

    Full Text Available Without sufficient data, consulting experts is a good way to quantify unknown parameters in water resources management which will result in human uncertainty. The aim of this paper is to introduce a new tool-uncertainty theory to deal with such uncertainty which is treated as uncertain variable with uncertainty distribution. And a dependent-chance goal programming (DCGP model is provided for water resources management under such circumstance. In the model uncertain measure is used to measure possibility that an event will occur which is maximized by minimizing the deviation (positive or negative deviation from target of objective event under a given priority structure. In the end, the developed model is applied to a numerical example to illustrate the effectiveness of the model. The result obtained contributes to the desired water-allocation schemes for decision-markers.

  4. Dependencies of Europe's economy on water resources outside its borders and its vulnerability to weather extremes

    Science.gov (United States)

    Chico Zamanillo, Daniel; Chapagain, Ashok; Ercin, Ertug

    2017-04-01

    Europe's economy is dependent on water resources elsewhere in the world since many of the goods consumed in the EU are not produced domestically, but abroad. Reliance on food, energy and goods produced in regions outside of the EU may impose water related risks on different economic sectors within the EU due to vulnerability of water resources used in their production to hydrological extremes and climate change. IMPREX project addresses this economic dependency and water resources vulnerability to hydrological extremes and climate change under WP12 "Water Economy". This study presents the results of the first task of WP12, mapping current dependencies of European economy on water resources outside its borders and their vulnerability to drought and water scarcity. In our assessment, we have used water footprint, which is a measure of the appropriation of freshwater resources for human activities, and is comprised of three components - green (consumption of rainfall), blue (consumption of surface and groundwater) and grey (refers to water pollution). We first calculated virtual water import, the amount of water consumed in producing products imported to the EU, and we identified key products - those making up the largest virtual water inflows to the EU. After mapping the dependencies, we assessed water scarcity and drought severity in producing locations. Coupling this with the water footprint enabled us to map the EU's external water dependencies and to identify when and where vulnerabilities may lie, in terms of blue water scarcity and drought. Overall, external green water resources account for 41% of the total green water footprint of the EU's economy. Soybean, cocoa, coffee, oil palm, sunflower, maize and olives are identified as key products from the perspective of green virtual water import to the EU. Soybean is the crop with the largest virtual water import volume to the EU with imports coming from Argentina, Brazil and USA. Europe relies on soybean import to

  5. Electronic Coupling Dependence of Ultrafast Interfacial Electron Transfer on Nanocrystalline Thin Films and Single Crystal

    Energy Technology Data Exchange (ETDEWEB)

    Lian, Tianquan

    2014-04-22

    The long-term goal of the proposed research is to understand electron transfer dynamics in nanoparticle/liquid interface. This knowledge is essential to many semiconductor nanoparticle based devices, including photocatalytic waste degradation and dye sensitized solar cells.

  6. Time-dependent restricted active space Configuration Interaction for the photoionization of many-electron atoms

    CERN Document Server

    Hochstuhl, David

    2012-01-01

    We introduce the time-dependent restricted active space Configuration Interaction method to solve the time-dependent Schr\\"odinger equation for many-electron atoms, and particularly apply it to the treatment of photoionization processes in atoms. The method is presented in a very general formulation and incorporates a wide range of commonly used approximation schemes, like the single-active electron approximation, time-dependent Configuration Interaction with single-excitations, or the time-dependent R-matrix method. We proof the applicability of the method by calculating the photoionization cross sections of Helium and Beryllium.

  7. [Use of internet and electronic resources among Spanish intensivist physicians. First national survey].

    Science.gov (United States)

    Gómez-Tello, V; Latour-Pérez, J; Añón Elizalde, J M; Palencia-Herrejón, E; Díaz-Alersi, R; De Lucas-García, N

    2006-01-01

    Estimate knowledge and use habits of different electronic resources in a sample of Spanish intensivists: Internet, E-mail, distribution lists, and use of portable electronic devices. Self-applied questionnaire. A 50-question questionnaire was distributed among Spanish intensivists through the hospital marketing delegates of a pharmaceutical company and of electronic forums. A total of 682 questionnaires were analyzed (participation: 74%). Ninety six percent of those surveyed used Internet individually: 67% admitted training gap. Internet was the second source of clinical consultations most used (61%), slightly behind consultation to colleagues (65%). The pages consulted most were bibliographic databases (65%) and electronic professional journals (63%), with limited use of Evidence Based Medicine pages (19%). Ninety percent of those surveyed used e-mail regularly in the practice of their profession, although 25% admitted that were not aware of its possibilities. The use of E-mail decreased significantly with increase in age. A total of 62% of the intensivists used distribution lists. Of the rest, 42% were not aware of its existence and 32% admitted they had insufficient training to handle them. Twenty percent of those surveyed had portable electronic devices and 64% considered it useful, basically due to its rapid consultation at bedside. Female gender was a negative predictive factor of its use (OR 0.35; 95% CI 0.2-0.63; p=0.0002). A large majority of the Spanish intensivists use Internet and E-mail. E-mail lists and use of portable devices are still underused resources. There are important gaps in training and infrequent use of essential pages. There are specific groups that require directed educational policies.

  8. Review of material recovery from used electric and electronic equipment-alternative options for resource conservation.

    Science.gov (United States)

    Friege, Henning

    2012-09-01

    For waste from electric and electronic equipment, the WEEE Directive stipulates the separate collection of electric and electronic waste. As to new electric and electronic devices, the Restriction of Hazardous Substances (RoHS) Directive bans the use of certain chemicals dangerous for man and environment. From the implementation of the WEEE directive, many unsolved problems have been documented: poor collection success, emission of dangerous substances during collection and recycling, irretrievable loss of valuable metals among others. As to RoHS, data from the literature show a satisfying success. The problems identified in the process can be reduced to some basic dilemmas at the borders between waste management, product policy and chemical safety. The objectives of the WEEE Directive and the specific targets for use and recycling of appliances are not consistent. There is no focus on scarce resources. Extended producer responsibility is not sufficient to guarantee sustainable waste management. Waste management reaches its limits due to problems of implementation but also due to physical laws. A holistic approach is necessary looking at all branch points and sinks in the stream of used products and waste from electric and electronic equipment. This may be done with respect to the general rules for sustainable management of material streams covering the three dimensions of sustainable policy. The relationships between the players in the field of electric and electronic devices have to be taken into account. Most of the problems identified in the implementation process will not be solved by the current amendment of the WEEE Directive.

  9. Simulation of energy-dependent electron diffusion processes in the Earth's outer radiation belt

    Science.gov (United States)

    Ma, Q.; Li, W.; Thorne, R. M.; Nishimura, Y.; Zhang, X.-J.; Reeves, G. D.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Henderson, M. G.; Spence, H. E.; Baker, D. N.; Blake, J. B.; Fennell, J. F.; Angelopoulos, V.

    2016-05-01

    The radial and local diffusion processes induced by various plasma waves govern the highly energetic electron dynamics in the Earth's radiation belts, causing distinct characteristics in electron distributions at various energies. In this study, we present our simulation results of the energetic electron evolution during a geomagnetic storm using the University of California, Los Angeles 3-D diffusion code. Following the plasma sheet electron injections, the electrons at different energy bands detected by the Magnetic Electron Ion Spectrometer (MagEIS) and Relativistic Electron Proton Telescope (REPT) instruments on board the Van Allen Probes exhibit a rapid enhancement followed by a slow diffusive movement in differential energy fluxes, and the radial extent to which electrons can penetrate into depends on energy with closer penetration toward the Earth at lower energies than higher energies. We incorporate radial diffusion, local acceleration, and loss processes due to whistler mode wave observations to perform a 3-D diffusion simulation. Our simulation results demonstrate that chorus waves cause electron flux increase by more than 1 order of magnitude during the first 18 h, and the subsequent radial extents of the energetic electrons during the storm recovery phase are determined by the coupled radial diffusion and the pitch angle scattering by EMIC waves and plasmaspheric hiss. The radial diffusion caused by ULF waves and local plasma wave scattering are energy dependent, which lead to the observed electron flux variations with energy dependences. This study suggests that plasma wave distributions in the inner magnetosphere are crucial for the energy-dependent intrusions of several hundred keV to several MeV electrons.

  10. Secondary electron yield of Cu technical surfaces: Dependence on electron irradiation

    Science.gov (United States)

    Larciprete, R.; Grosso, D. R.; Commisso, M.; Flammini, R.; Cimino, R.

    2013-01-01

    The secondary emission yield (SEY) properties of colaminated Cu samples for LHC beam screens are correlated to the surface chemical composition determined by x-ray photoelectron spectroscopy. The surface of the as-received samples is characterized by the presence of significant quantities of contaminating adsorbates and by the maximum of the SEY curve (δmax⁡) being as high as 2.1. After extended electron scrubbing at kinetic energy of 10 and 500 eV, the δmax⁡ value drops to the ultimate values of 1.35 and 1.1, respectively. In both cases the surface oxidized phases are significantly reduced, whereas only in the sample scrubbed at 500 eV the formation of a graphitic-like C layer is observed. We find that the electron scrubbing of technical Cu surfaces can be described as occurring in two steps: the first step consists in the electron-induced desorption of weakly bound contaminants that occurs indifferently at 10 and at 500 eV and corresponds to a partial decrease of δmax⁡; the second step, activated by more energetic electrons and becoming evident at high doses, increases the number of graphitic-like C-C bonds via the dissociation of adsorbates already contaminating the as-received surface or accumulating on this surface during irradiation. Our results demonstrate how the kinetic energy of impinging electrons is a crucial parameter when conditioning the surfaces of Cu and other metals by means of electron-induced chemical processing.

  11. Aufwand und Nutzen des Electronic Resource Management Systems RMS an der UB Kassel

    Directory of Open Access Journals (Sweden)

    Tobias Pohlmann

    2016-03-01

    The university library of Kassel therefore uses SemperTool’s web-based electronic resource management system RMS. This paper presents the functionality of this system and makes an estimate of the expenditure of work necessary to enter all relevant information about licensed databases, e-book and e-journal packages with the corresponding individual resources. It also describes existing and projected tools for analysis and evaluation, which are decisive for the usefulness of such a system, and concludes with the satisfaction reached at the university library of Kassel. These experiences may help other libraries to decide whether or not to introduce RMS or a comparable system.

  12. Examining the ‘’Natural Resource Curse’’ and the Impact of Various Forms of Capital in Small Tourism and Natural Resource-Dependent Economies

    Directory of Open Access Journals (Sweden)

    Petar Kurecic

    2017-02-01

    Full Text Available The problem of the relevance of human and natural capital, as well as the potential adverse effect of natural capital on economic growth, has gained increased attention in development economics. The aim of this paper is to assess, theoretically and empirically, the relevance of several forms of capital on economic growth in certain small economies that are dependent upon tourism or natural resources. The empirical framework is based on Impulse Response Functions obtained from Vector Autoregressive models in which we focus on the model where economic growth is the dependent variable for ten small economies that are dependent upon either tourism or natural resources. We find that there is evidence of the “natural resource curse”, especially in the economies that have a strong dependence on resources that are easily substitutable and whose prices constantly fluctuate. We further find that in the majority of observed cases, the type of capital these small economies are most dependent on for their economic growth causes negative impulses in the majority of the observed periods. Therefore, the main policy recommendation should be to assure that even these small economies should strive towards further diversification and avoid dependence on only one segment of their economy.

  13. ELECTRONIC EDUCATIONAL RESOURCES FOR ONLINE SUPPORT OF MODERN CHEMISTRY CLASSES IN SPECIALIZED SCHOOL

    Directory of Open Access Journals (Sweden)

    Maria D. Tukalo

    2013-09-01

    Full Text Available This article contains material of some modern electronic educational resources that can be used via the Internet to support the modern chemistry classes in specialized school. It was drawn attention to the educational chemical experiments as means of knowledge; simulated key motivational characteristics to enhance students interest for learning subjects, their cognitive and practical activity in the formation of self-reliance and self-creative; commented forecasts for creating of conditions to enhance the creative potential of students in a modern learning environment.

  14. Bias dependence of synergistic radiation effects induced by electrons and protons on silicon bipolar junction transistors

    Science.gov (United States)

    Liu, Chaoming; Li, Xingji; Yang, Jianqun; Ma, Guoliang; Xiao, Liyi

    2015-06-01

    Bias dependence on synergistic radiation effects caused by 110 keV electrons and 170 keV protons on the current gain of 3DG130 NPN bipolar junction transistors (BJTs) is studied in this paper. Experimental results indicate that the influence induced by 170 keV protons is always enhancement effect during the sequential irradiation. However, the influence induced by 110 keV electrons on the BJT under various bias cases is different during the sequential irradiation. The transition fluence of 110 keV electrons is dependent on the bias case on the emitter-base junction of BJT.

  15. Diameter-dependent electronic transport properties of Au-catalyst/Ge-nanowire Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Picraux, S Thomas [Los Alamos National Laboratory; Leonard, Francois [SNL; Swartzentruber, Brian S [SNL; Talin, A Alee [SNL

    2008-01-01

    We present electronic transport measurements in individual Au-catalyst/Ge-nanowire interfaces demonstrating the presence of a Schottky barrier. Surprisingly, the small-bias conductance density increases with decreasing diameter. Theoretical calculations suggest that this effect arises because electron-hole recombination in the depletion region is the dominant charge transport mechanism, with a diameter dependence of both the depletion width and the electron-hole recombination time. The recombination time is dominated by surface contributions and depends linearly on the nanowire diameter.

  16. Solution of time-dependent Boltzmann equation for electrons in non-thermal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Trunec, D; Bonaventura, Z; Necas, D [Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic)

    2006-06-21

    The time development of the electron distribution function and electron macroscopic parameters was studied by solving the time-dependent Boltzmann equation for low temperature plasma. A new technique for solving the time-dependent Boltzmann equation was developed. This technique is based on a multi-term approximation of the electron distribution function expansion in Legendre polynomials. The results for electron relaxation in Reid's ramp model and argon plasma are presented. The effect of negative mobility was studied and is discussed for argon plasma. Finally, the time-dependent Boltzmann equation was solved for pulsed microwave discharge in nitrogen. The accuracy of all results was confirmed by the Monte Carlo simulation.

  17. Spin-dependent electron scattering at graphene edges on Ni(111).

    Science.gov (United States)

    Garcia-Lekue, A; Balashov, T; Olle, M; Ceballos, G; Arnau, A; Gambardella, P; Sanchez-Portal, D; Mugarza, A

    2014-02-14

    We investigate the scattering of surface electrons by the edges of graphene islands grown on Ni(111). By combining local tunneling spectroscopy and ab initio electronic structure calculations we find that the hybridization between graphene and Ni states results in strongly reflecting graphene edges. Quantum interference patterns formed around the islands reveal a spin-dependent scattering of the Shockley bands of Ni, which we attribute to their distinct coupling to bulk states. Moreover, we find a strong dependence of the scattering amplitude on the atomic structure of the edges, depending on the orbital character and energy of the surface states.

  18. Teachers' Link to Electronic Resources in the Library Media Center: A Local Study of Awareness, Knowledge, and Influence

    Science.gov (United States)

    Williams, Teresa D.; Grimble, Bonnie J.; Irwin, Marilyn

    2004-01-01

    High school students often use online databases and the Internet in the school library media center (SLMC) to complete teachers' assignments. This case study used a survey to assess teachers' awareness of electronic resources, and to determine whether their directions influence student use of these resources in the SLMC. Participants were teachers…

  19. Impact of Knowledge Resources Linked to an Electronic Health Record on Frequency of Unnecessary Tests and Treatments

    Science.gov (United States)

    Goodman, Kenneth; Grad, Roland; Pluye, Pierre; Nowacki, Amy; Hickner, John

    2012-01-01

    Introduction: Electronic knowledge resources have the potential to rapidly provide answers to clinicians' questions. We sought to determine clinicians' reasons for searching these resources, the rate of finding relevant information, and the perceived clinical impact of the information they retrieved. Methods: We asked general internists, family…

  20. Time-dependent density functional theory study on direction-dependent electron and hole transfer processes in molecular systems.

    Science.gov (United States)

    Partovi-Azar, Pouya; Kaghazchi, Payam

    2017-04-15

    We report on real-time time-dependent density functional theory calculations on direction-dependent electron and hole transfer processes in molecular systems. As a model system, we focus on α-sulfur. It is shown that time scale of the electron transfer process from a negatively charged S8 molecule to a neighboring neutral monomer is comparable to that of a strong infrared-active molecular vibrations of the dimer with one negatively charged monomer. This results in a strong coupling between the electrons and the nuclei motion which eventually leads to S8 ring opening before the electron transfer process is completed. The open-ring structure is found to be stable. The similar infrared-active peak in the case of hole transfer, however, is shown to be very weak and hence no significant scattering by the nuclei is possible. The presented approach to study the charge transfer processes in sulfur has direct applications in the increasingly growing research field of charge transport in molecular systems. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  1. Reducing Clinical Trial Monitoring Resource Allocation and Costs Through Remote Access to Electronic Medical Records

    Science.gov (United States)

    Uren, Shannon C.; Kirkman, Mitchell B.; Dalton, Brad S.; Zalcberg, John R.

    2013-01-01

    Purpose: With electronic medical records (eMRs), the option now exists for clinical trial monitors to perform source data verification (SDV) remotely. We report on a feasibility study of remote access to eMRs for SDV and the potential advantages of such a process in terms of resource allocation and cost. Methods: The Clinical Trials Unit at the Peter MacCallum Cancer Centre, in collaboration with Novartis Pharmaceuticals Australia, conducted a 6-month feasibility study of remote SDV. A Novartis monitor was granted dedicated software and restricted remote access to the eMR portal of the cancer center, thereby providing an avenue through which perform SDV. Results: Six monitoring visits were conducted during the study period, four of which were performed remotely. The ability to conduct two thirds of the monitoring visits remotely in this complex phase III study resulted in an overall cost saving to Novartis. Similarly, remote monitoring eased the strain on internal resources, particularly monitoring space and hospital computer terminal access, at the cancer center. Conclusion: Remote access to patient eMRs for SDV is feasible and is potentially an avenue through which resources can be more efficiently used. Although this feasibility study involved limited numbers, there is no limit to scaling these processes to any number of patients enrolled onto large clinical trials. PMID:23633977

  2. [Electron transfer between globular proteins. Dependence of the rate of transfer on distance].

    Science.gov (United States)

    Lakhno, V D; Chuev, G N; Ustinin, M N; Komarov, V M

    1998-01-01

    Based on the assumption that electron transfer between globular proteins occurs by a collective excitation of polaron type, the dependence of the rate of this process on the distance between the donor and acceptor centers with regard to their detailed electron structure was calculated. The electron structure of the heme was calculated by the quantum-chemical MNDO-PM3 method. The results were compared with experimental data on interprotein and intraglobular electron transfer. It is shown that, in the framework of this model, the electron transfer is not exponential and does not require a particular transfer pathway since the whole protein macromolecule is involved in the formation of the electron excited state.

  3. Artificial neural network prediction model for geosynchronous electron fluxes: Dependence on satellite position and particle energy

    Science.gov (United States)

    Shin, Dae-Kyu; Lee, Dae-Young; Kim, Kyung-Chan; Hwang, Junga; Kim, Jaehun

    2016-04-01

    Geosynchronous satellites are often exposed to energetic electrons, the flux of which varies often to a large extent. Since the electrons can cause irreparable damage to the satellites, efforts to develop electron flux prediction models have long been made until recently. In this study, we adopt a neural network scheme to construct a prediction model for the geosynchronous electron flux in a wide energy range (40 keV to >2 MeV) and at a high time resolution (as based on 5 min resolution data). As the model inputs, we take the solar wind variables, geomagnetic indices, and geosynchronous electron fluxes themselves. We also take into account the magnetic local time (MLT) dependence of the geosynchronous electron fluxes. We use the electron data from two geosynchronous satellites, GOES 13 and 15, and apply the same neural network scheme separately to each of the GOES satellite data. We focus on the dependence of prediction capability on satellite's magnetic latitude and MLT as well as particle energy. Our model prediction works less efficiently for magnetic latitudes more away from the equator (thus for GOES 13 than for GOES 15) and for MLTs nearer to midnight than noon. The magnetic latitude dependence is most significant for an intermediate energy range (a few hundreds of keV), and the MLT dependence is largest for the lowest energy (40 keV). We interpret this based on degree of variance in the electron fluxes, which depends on magnetic latitude and MLT at geosynchronous orbit as well as particle energy. We demonstrate how substorms affect the flux variance.

  4. Electron energy dependence of characteristics of fluorescent plates for ultrahigh-voltage electron microscopes.

    Science.gov (United States)

    Nishi, R; Yoshida, K; Takaoka, A; Katsuta, T

    1996-03-01

    The characteristics of fluorescent plates for high energy electron beams (0.5-2.0 MeV) are examined. The thickness and the optical transparency of plates strongly affect the luminous broadening and intensity. The spatial luminous broadening in fluorescent plates is measured and is simply represented by the rise width of a knife edge image. When the thickness is much smaller than the range of incident electrons, the rise width is 1/4-1/5 of the thickness in the case of YAG single crystal plates that are transparent for light, while the rise width is nearly equal to the thickness for the packed P22 powder plates that are opaque for light. To suppress the luminous broadening under 50 microm, the thickness of YAG plates has to be thinner than 250 microm in the energy region around 2 MeV. Under the same condition of the rise width, the luminous intensity of YAG plates is twice as high as that of the P22 plates.

  5. Time-dependent tunneling of spin-polarized electrons in coupled quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, H; Luis, D [Departamento de Fisica Basica, Universidad de La Laguna, 38204 La Laguna, Tenerife (Spain)], E-mail: hcruz@ull.es

    2008-02-15

    We have solved the in-plane momentum-dependent effective-mass nonlinear Schroedinger equation for a spin-polarized electron wave packet in a InAs double quantum well system with an interlayer voltage. Considering a time-dependent Hartree potential, we have calculated the spin-polarized nonlinear electron dynamics between both quantum wells at different in-plane momentum values and applied bias. The spin-splitting caused by the Rashba effect is combined with the level matching between the spin dependent resonant tunneling levels making possible the observed local spin density oscillations which depend on the applied bias value. The filtering efficiency has been studied using time-dependent calculations.

  6. Electronic theses and dissertations: a review of this valuable resource for nurse scholars worldwide.

    Science.gov (United States)

    Goodfellow, L M

    2009-06-01

    A worldwide repository of electronic theses and dissertations (ETDs) could provide worldwide access to the most up-to-date research generated by masters and doctoral students. Until that international repository is established, it is possible to access some of these valuable knowledge resources. ETDs provide a technologically advanced medium with endless multimedia capabilities that far exceed the print and bound copies of theses and dissertations housed traditionally in individual university libraries. CURRENT USE: A growing trend exists for universities worldwide to require graduate students to submit theses or dissertations as electronic documents. However, nurse scholars underutilize ETDs, as evidenced by perusing bibliographic citation lists in many of the research journals. ETDs can be searched for and retrieved through several digital resources such as the Networked Digital Library of Theses and Dissertations (http://www.ndltd.org), ProQuest Dissertations and Theses (http://www.umi.com), the Australasian Digital Theses Program (http://adt.caul.edu.au/) and through individual university web sites and online catalogues. An international repository of ETDs benefits the community of nurse scholars in many ways. The ability to access recent graduate students' research electronically from anywhere in the world is advantageous. For scholars residing in developing countries, access to these ETDs may prove to be even more valuable. In some cases, ETDs are not available for worldwide access and can only be accessed through the university library from which the student graduated. Public access to university library ETD collections is not always permitted. Nurse scholars from both developing and developed countries could benefit from ETDs.

  7. A preliminary categorization of end-of-life electrical and electronic equipment as secondary metal resources.

    Science.gov (United States)

    Oguchi, Masahiro; Murakami, Shinsuke; Sakanakura, Hirofumi; Kida, Akiko; Kameya, Takashi

    2011-01-01

    End-of-life electrical and electronic equipment (EEE) has recently received attention as a secondary source of metals. This study examined characteristics of end-of-life EEE as secondary metal resources to consider efficient collection and metal recovery systems according to the specific metals and types of EEE. We constructed an analogy between natural resource development and metal recovery from end-of-life EEE and found that metal content and total annual amount of metal contained in each type of end-of-life EEE should be considered in secondary resource development, as well as the collectability of the end-of-life products. We then categorized 21 EEE types into five groups and discussed their potential as secondary metal resources. Refrigerators, washing machines, air conditioners, and CRT TVs were evaluated as the most important sources of common metals, and personal computers, mobile phones, and video games were evaluated as the most important sources of precious metals. Several types of small digital equipment were also identified as important sources of precious metals; however, mid-size information and communication technology (ICT) equipment (e.g., printers and fax machines) and audio/video equipment were shown to be more important as a source of a variety of less common metals. The physical collectability of each type of EEE was roughly characterized by unit size and number of end-of-life products generated annually. Current collection systems in Japan were examined and potentially appropriate collection methods were suggested for equipment types that currently have no specific collection systems in Japan, particularly for video games, notebook computers, and mid-size ICT and audio/video equipment.

  8. From Millennium ERM to Proquest 360 Resource Manager: Implementing a new Electronic Resources Management System ERMS in an International Graduate Research University in Saudi Arabia

    KAUST Repository

    Ramli, Rindra M.

    2017-05-17

    An overview of the Recommendation Study and the subsequent Implementation of a new Electronic Resources Management system ERMS in an international graduate research university in the Kingdom of Saudi Arabia. It covers the timeline, deliverables and challenges as well as lessons learnt by the Project Team.

  9. Leidt het fenomeen Open Educational Resources tot nieuwe didactische modellen? “It depends"

    OpenAIRE

    Didderen, Wim; Verjans, Steven

    2012-01-01

    Didderen, W., & Verjans, S. (2012). Leidt het fenomeen Open Educational Resources tot nieuwe didactische modellen? “It depends”. In R. Jacobi, & N. van der Woert (Eds.), Trendrapport Open Educational Resources 2012 (pp. 9-15). Utrecht: SURF Foundation - Special Interest Group Open Educational Resources. Retrieved from https://www.surfspace.nl/artikel/697-trendrapport-open-educational-resources/.

  10. Electron mean free path from angle-dependent photoelectron spectroscopy of aerosol particles

    CERN Document Server

    Goldmann, Maximilian; West, Adam H C; Yoder, Bruce L; Signorell, Ruth

    2015-01-01

    We propose angle-resolved photoelectron spectroscopy of aerosol particles as an alternative way to determine the electron mean free path of low energy electrons in solid and liquid materials. The mean free path is obtained from fits of simulated photoemission images to experimental ones over a broad range of different aerosol particle sizes. The principal advantage of the aerosol approach is twofold. Firstly, aerosol photoemission studies can be performed for many different materials, including liquids. Secondly, the size-dependent anisotropy of the photoelectrons can be exploited in addition to size-dependent changes in their kinetic energy. These finite size effects depend in different ways on the mean free path and thus provide more information on the mean free path than corresponding liquid jet, thin film, or bulk data. The present contribution is a proof of principle employing a simple model for the photoemission of electrons and preliminary experimental data for potassium chloride aerosol particles.

  11. Kinetic Energy Release in Fragmentation Processes following Electron Emission: A time dependent approach

    CERN Document Server

    Chiang, Ying-Chih; Meyer, Hans-Dieter; Cederbaum, Lorenz S

    2012-01-01

    A time-dependent approach for the kinetic energy release (KER) spectrum is developed for a fragmentation of a diatomic molecule after an electronic decay process, e.g. Auger process. It allows one to simulate the time-resolved spectra and provides more insight into the molecular dynamics than the time-independent approach. Detailed analysis of the time-resolved emitted electron and KER spectra sheds light on the interrelation between wave packet dynamics and spectra.

  12. Energetic Constraints on H-2-Dependent Terminal Electron Accepting Processes in Anoxic Environments

    DEFF Research Database (Denmark)

    Heimann, Axel Colin; Jakobsen, Rasmus; Blodau, C.

    2010-01-01

    Microbially mediated terminal electron accepting processes (TEAPs) to a large extent control the fate of redox reactive elements and associated reactions in anoxic soils, sediments, and aquifers. This review focuses on thermodynamic controls and regulation of H-2-dependent TEAPs, case studies...... illustrating this concept and the quantitative description of thermodynamic controls in modeling. Other electron transfer processes are considered where appropriate. The work reviewed shows that thermodynamics and microbial kinetics are connected near thermodynamic equilibrium. Free energy thresholds...

  13. Z-dependence of thick-target bremsstrahlung produced by monoenergetic low-energy electrons

    Science.gov (United States)

    Czarnecki, S.; Short, A.; Williams, S.

    2016-07-01

    The dependence of thick-target bremsstrahlung emitted by low-energy beams of monoenergetic electrons on the atomic number of the target material has been investigated experimentally for incident electron energies of 4.25 keV and 5.00 keV using thick aluminum, copper, silver, tungsten, and gold targets. Experimental data suggest that the intensity of the thick-target bremsstrahlung emitted is more strongly dependent on the atomic number of the target material for photons with energies that are approximately equal to the energy of the incident electrons than at lower energies, and also that the dependence of thick-target bremsstrahlung on the atomic number of the target material is stronger for incident electrons of higher energies than for incident electrons of lower energies. The results of the experiments are compared to the results of simulations performed using the PENELOPE program (which is commonly used in medical physics) and to thin-target bremsstrahlung theory, as well. Comparisons suggest that the experimental dependence of thick-target bremsstrahlung on the atomic number of the target material may be slightly stronger than the results of the PENELOPE code suggest.

  14. Attosecond electronic and nuclear quantum photodynamics of ozone: time-dependent Dyson orbitals and dipole

    CERN Document Server

    Perveaux, A; Lasorne, B; Gatti, F; Robb, M A; Halász, G J; Vibók, Á

    2014-01-01

    A nonadiabatic scheme for the description of the coupled electron and nuclear motions in the ozone molecule was proposed recently. An initial coherent nonstationary state was prepared as a superposition of the ground state and the excited Hartley band. In this situation neither the electrons nor the nuclei are in a stationary state. The multiconfiguration time dependent Hartree method was used to solve the coupled nuclear quantum dynamics in the framework of the adiabatic separation of the time-dependent Schr\\"odinger equation. The resulting wave packet shows an oscillation of the electron density between the two chemical bonds. As a first step for probing the electronic motion we computed the time-dependent molecular dipole and the Dyson orbitals. The latter play an important role in the explanation of the photoelectron angular distribution. Calculations of the Dyson orbitals are presented both for the time-independent as well as the time-dependent situations. We limited our description of the electronic mot...

  15. pH-dependent regulation of electron transport and ATP synthesis in chloroplasts.

    Science.gov (United States)

    Tikhonov, Alexander N

    2013-10-01

    This review is focused on pH-dependent mechanisms of regulation of photosynthetic electron transport and ATP synthesis in chloroplasts. The light-induced acidification of the thylakoid lumen is known to decelerate the plastoquinol oxidation by the cytochrome b 6 f complex, thus impeding the electron flow between photosystem II and photosystem I. Acidification of the lumen also triggers the dissipation of excess energy in the light-harvesting antenna of photosystem II, thereby protecting the photosynthetic apparatus against a solar stress. After brief description of structural and functional organization of the chloroplast electron transport chain, our attention is focused on the nature of the rate-limiting step of electron transfer between photosystem II and photosystem I. In the context of pH-dependent mechanism of photosynthetic control in chloroplasts, the mechanisms of plastoquinol oxidation by the cytochrome b 6 f complex have been considered. The light-induced alkalization of stroma is another factor of pH-dependent regulation of electron transport in chloroplasts. Alkalization of stroma induces activation of the Bassham-Benson-Calvin cycle reactions, thereby promoting efflux of electrons from photosystem I to NADP(+). The mechanisms of the light-induced activation of ATP synthase are briefly considered.

  16. First-principles Theory of the Momentum-dependent Local Ansatz for Correlated Electron System

    Science.gov (United States)

    Chandra, Sumal; Kakehashi, Yoshiro

    The momentum-dependent local-ansatz (MLA) wavefunction describes well correlated electrons in solids in both the weak and strong interaction regimes. In order to apply the theory to the realistic system, we have extended the MLA to the first-principles version using the tight-binding LDA+U Hamiltonian. We demonstrate for the paramagnetic Fe that the first-principles MLA can describe a reasonable correlation energy gain and suppression of charge fluctuations due to electron correlations. Furthermore, we show that the MLA yields a distinct momentum dependence of the momentum distribution, and thus improves the Gutzwiller wavefunction.

  17. Spin dependent transport of hot electrons through ultrathin epitaxial metallic films

    Energy Technology Data Exchange (ETDEWEB)

    Heindl, Emanuel

    2010-06-23

    In this work relaxation and transport of hot electrons in thin single crystalline metallic films is investigated by Ballistic Electron Emission Microscopy. The electron mean free paths are determined in an energy interval of 1 to 2 eV above the Fermi level. While fcc Au-films appear to be quite transmissive for hot electrons, the scattering lengths are much shorter for the ferromagnetic alloy FeCo revealing, furthermore, a strong spin asymmetry in hot electron transport. Additional information is gained from temperature dependent studies in combination with golden rule approaches in order to disentangle the impact of several relaxation and transport properties. It is found that bcc Fe-films are much less effective in spin filtering than films made of the FeCo-alloy. (orig.)

  18. Energy and charge dependence of the rate of electron-ion recombination in cold magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Gao, H.; Schuch, R.; Zong, W.; Justiniano, E.; DeWitt, D.R.; Lebius, H.; Spies, W. [Stockholm Univ., Atomic Physics Dept., Stockholm (Sweden)

    1997-07-28

    We have measured electron-ion recombination rates for bare ions of D{sup +}, He{sup 2+}, N{sup 7+}, Ne{sup 10+} and Si{sup 14+} in a storage ring. For the multi-charged ions an unexpected energy dependence was found, showing a strong increase of the measured rates over the calculated radiative recombination rate for electron beam detuning energies below the electron beam transverse temperature. The measured enhanced rates increase approximately as Z{sup 2.8} with the charge state Z. A comparison of these rates with theoretical predictions for collisional-radiative recombination in the cold magnetized electron plasma, in particular three-body recombination including radiative de-excitation of electrons in Rydberg levels, is made. (author).

  19. Electronic tracking of human resource skills and knowledge, just in time training, manageable due diligence

    Energy Technology Data Exchange (ETDEWEB)

    Kolodziej, M.A. [Quick Test International Inc., (Canada). Canadian Technology Human Resource Board; Baker, O. [KeySpan Energy Canada, Calgary, AB (Canada)

    2001-06-01

    KeySpan Energy Canada is in the process of obtaining recognition of various occupational profiles including pipeline operators, inspectors, and field and plant operators from various certifying organizations. The process of allowing individuals to obtain certification is recognized by Canadian Technology Human Resources Board as a step towards national standards for technologists and technicians. Proven competency is a must for workers in todays oil industry in response to increasingly stringent government safety regulations, environmental concerns and high public scrutiny. Quick Test international Inc. has developed a management tool in collaboration with end users at KeySpan Energy Canada. It is an electronic, Internet based competency tool for tracking personal competencies and maintaining continued competency. Response to the tool has been favourable. 2 refs., 4 figs.

  20. [HYGIENIC REGULATION OF THE USE OF ELECTRONIC EDUCATIONAL RESOURCES IN THE MODERN SCHOOL].

    Science.gov (United States)

    Stepanova, M I; Aleksandrova, I E; Sazanyuk, Z I; Voronova, B Z; Lashneva, L P; Shumkova, T V; Berezina, N O

    2015-01-01

    We studied the effect of academic studies with the use a notebook computer and interactive whiteboard on the functional state of an organism of schoolchildren. Using a complex of hygienic and physiological methods of the study we established that regulation of the computer activity of students must take into account not only duration but its intensity either. Design features of a notebook computer were shown both to impede keeping the optimal working posture in primary school children and increase the risk offormation of disorders of vision and musculoskeletal system. There were established the activating influence of the interactive whiteboard on performance activities and favorable dynamics of indices of the functional state of the organism of students under keeping optimal density of the academic study and the duration of its use. There are determined safety regulations of the work of schoolchildren with electronic resources in the educational process.

  1. Medical Image Resource Center--making electronic teaching files from PACS.

    Science.gov (United States)

    Lim, C C Tchoyoson; Yang, Guo Liang; Nowinski, Wieslaw L; Hui, Francis

    2003-12-01

    A picture archive and communications system (PACS) is a rich source of images and data suitable for creating electronic teaching files (ETF). However, the potential for PACS to support nonclinical applications has not been fully realized: at present there is no mechanism for PACS to identify and store teaching files; neither is there a standardized method for sharing such teaching images. The Medical Image Resource Center (MIRC) is a new central image repository that defines standards for data exchange among different centers. We developed an ETF server that retrieves digital imaging and communication in medicine (DICOM) images from PACS, and enables users to create teaching files that conform to the new MIRC schema. We test-populated our ETF server with illustrative images from the clinical case load of the National Neuroscience Institute, Singapore. Together, PACS and MIRC have the potential to benefit radiology teaching and research.

  2. Electronic Human Resource Management (e-HRM of Hotel Business in Phuket

    Directory of Open Access Journals (Sweden)

    Kitimaporn Choochote

    2015-04-01

    Full Text Available This research aims to study the pattern of the electronic human resources management (e-HRM of the hotel business in Phuket. The study is conducted with the implementation of field data and in-depth interview of hotels’ HR managers. In consequence, the study reveals that the hotel business has applied the use of the e-HRM varying in job recruitment (15 percent, employee engagement (55 percent, organizational file structure (10 percent, idea and creativity exchanges (38 percent and assessment system (6 percent. However, considered as 100 percent, the hotel business has not prepared to apply the use of the e-HRM in salary system, learning and training program, welfare allocation and career development.

  3. Time-dependent theoretical treatments of the dynamics of electrons and nuclei in molecular systems

    Science.gov (United States)

    Deumens, E.; Diz, A.; Longo, R.; Öhrn, Y.

    1994-07-01

    An overview is presented of methods for time-dependent treatments of molecules as systems of electrons and nuclei. The theoretical details of these methods are reviewed and contrasted in the light of a recently developed time-dependent method called electron-nuclear dynamics. Electron-nuclear dynamics (END) is a formulation of the complete dynamics of electrons and nuclei of a molecular system that eliminates the necessity of constructing potential-energy surfaces. Because of its general formulation, it encompasses many aspects found in other formulations and can serve as a didactic device for clarifying many of the principles and approximations relevant in time-dependent treatments of molecular systems. The END equations are derived from the time-dependent variational principle applied to a chosen family of efficiently parametrized approximate state vectors. A detailed analysis of the END equations is given for the case of a single-determinantal state for the electrons and a classical treatment of the nuclei. The approach leads to a simple formulation of the fully nonlinear time-dependent Hartree-Fock theory including nuclear dynamics. The nonlinear END equations with the ab initio Coulomb Hamiltonian have been implemented at this level of theory in a computer program, ENDyne, and have been shown feasible for the study of small molecular systems. Implementation of the Austin Model 1 semiempirical Hamiltonian is discussed as a route to large molecular systems. The linearized END equations at this level of theory are shown to lead to the random-phase approximation for the coupled system of electrons and nuclei. The qualitative features of the general nonlinear solution are analyzed using the results of the linearized equations as a first approximation. Some specific applications of END are presented, and the comparison with experiment and other theoretical approaches is discussed.

  4. Using mobile electronic devices to deliver educational resources in developing countries.

    Science.gov (United States)

    Mazal, Jonathan Robert; Ludwig, Rebecca

    2015-01-01

    Developing countries have far fewer trained radiography professionals than developed countries, which exacerbates the limited access to imaging services. The lack of trained radiographers reflects, in part, limited availability of radiographer-specific educational resources. Historically, organizations that provided such resources in the developing world faced challenges related to the limited stock of current materials as well as expenses associated with shipping and delivery. Four mobile electronic devices (MEDs) were loaded with educational content (e-books, PDFs, and digital applications) spanning major radiography topics. The MEDs were distributed to 4 imaging departments in Ghana, India, Nepal, and Nigeria based on evidence of need for radiography-specific resources, as revealed by survey responses. A cost comparison of postal delivery vs digital delivery of educational content was performed. The effectiveness of delivering additional content via Wi-Fi transmission also was evaluated. Feedback was solicited on users' experience with the MEDs as a delivery tool for educational content. An initial average per e-book expense of $30.05, which included the cost of the device, was calculated for the MED delivery method compared with $15.56 for postal delivery of printed materials. The cost of the MED delivery method was reduced to an average of $10.05 for subsequent e-book deliveries. Additional content was successfully delivered via Wi-Fi transmission to all recipients during the 3-month follow-up period. Overall user feedback on the experience was positive, and ideas for enhancing the MED-based method were identified. Using MEDs to deliver radiography-specific educational content appears to be more cost effective than postal delivery of printed materials on a long-term basis. MEDs are more efficient for providing updates to educational materials. Customization of content to department needs, and using projector devices could enhance the usefulness of MEDs for

  5. Orbital-dependent Electron-Hole Interaction in Graphene and Associated Multi-Layer Structures

    Science.gov (United States)

    Deng, Tianqi; Su, Haibin

    2015-11-01

    We develop an orbital-dependent potential to describe electron-hole interaction in materials with structural 2D character, i.e. quasi-2D materials. The modulated orbital-dependent potentials are also constructed with non-local screening, multi-layer screening, and finite gap due to the coupling with substrates. We apply the excitonic Hamiltonian in coordinate-space with developed effective electron-hole interacting potentials to compute excitons’ binding strength at M (π band) and Γ (σ band) points in graphene and its associated multi-layer forms. The orbital-dependent potential provides a range-separated property for regulating both long- and short-range interactions. This accounts for the existence of the resonant π exciton in single- and bi-layer graphenes. The remarkable strong electron-hole interaction in σ orbitals plays a decisive role in the existence of σ exciton in graphene stack at room temperature. The interplay between gap-opening and screening from substrates shed a light on the weak dependence of σ exciton binding energy on the thickness of graphene stacks. Moreover, the analysis of non-hydrogenic exciton spectrum in quasi-2D systems clearly demonstrates the remarkable comparable contribution of orbital dependent potential with respect to non-local screening process. The understanding of orbital-dependent potential developed in this work is potentially applicable for a wide range of materials with low dimension.

  6. 2D Spin-Dependent Diffraction of Electrons From Periodical Chains of Nanomagnets

    Directory of Open Access Journals (Sweden)

    Teshome Senbeta

    2012-03-01

    Full Text Available The scattering of the unpolarized beams of electrons by nanomagnets in the vicinity of some scattering angles leads to complete spin polarized electrons. This result is obtained with the help of the perturbation theory. The dipole-dipole interaction between the magnetic moment of the nanomagnet and the magnetic moment of electron is treated as perturbation. This interaction is not spherically symmetric. Rather it depends on the electron spin variables. It in turn results in spinor character of the scattering amplitudes. Due to the smallness of the magnetic interactions, the scattering length of this process is very small to be proved experimentally. To enhance the relevant scattering lengths, we considered the diffraction of unpolarized beams of electrons by linear chains of nanomagnets. By tuning the distance between the scatterers it is possible to obtain the diffraction maximum of the scattered electrons at scattering angles which corresponds to complete spin polarization of electrons. It is shown that the total differential scattering length is proportional to N2 (N is a number of scatterers. Even small number of nanomagnets in the chain helps to obtain experimentally visible enhancement of spin polarization of the scattered electrons.

  7. Exploration of ultra-fast electron dynamics using time-dependent R-matrix theory

    Science.gov (United States)

    van der Hart, Hugo; Rey, Hector; Hassouneh, Ola; Brown, Andrew

    2014-05-01

    When an atom is subjected to an intense laser field, the full atomic response can involve a collective response involving several electrons. This collective response will be affected by electron-electron repulsion, coupling the overall electron dynamics. In order to investigate this dynamics for a multi-electron system from first principles, we have developed time-dependent R-matrix theory. The theory applies the basic principles of R-matrix theory, in which all interactions between all electrons are taken into account close to the nucleus, but exchange interactions are neglected when one electron has become distanced from the parent atom. In this contribution, we will explain the basic principles of this theory and demonstrate its application to ultra-fast dynamics in C+, and harmonic generation in singly ionised noble-gas atoms. Both studies demonstrate that it is important to go beyond the single-active-electron approximation. This research has been supported by EPSRC UK, and by the EU Initial Training Network CORINF.

  8. Plastics disassembly versus bulk recycling: engineering design for end-of-life electronics resource recovery.

    Science.gov (United States)

    Rios, Pedro; Stuart, Julie Ann; Grant, Ed

    2003-12-01

    Annual plastic flows through the business and consumer electronics manufacturing supply chain include nearly 3 billion lb of high-value engineering plastics derived from petroleum. The recovery of resource value from this stream presents critical challenges in areas of materials identification and recycling process design that demand new green engineering technologies applied together with life cycle assessment and ecological supply chain analysis to create viable plastics-to-plastics supply cycles. The sustainable recovery of potentially high-value engineering plastics streams requires that recyclers either avoid mixing plastic parts or purify later by separating smaller plastic pieces created in volume reduction (shredding) steps. Identification and separation constitute significant barriers in the plastics-to-plastics recycling value proposition. In the present work, we develop a model that accepts randomly arriving electronic products to study scenarios by which a recycler might identify and separate high-value engineering plastics as well as metals. Using discrete eventsimulation,we compare current mixed plastics recovery with spectrochemical plastic resin identification and subsequent sorting. Our results show that limited disassembly with whole-part identification can produce substantial yields in separated streams of recovered engineering thermoplastics. We find that disassembly with identification does not constitute a bottleneck, but rather, with relatively few workers, can be configured to pull the process and thus decrease maximum staging space requirements.

  9. Density-dependent electron scattering in photoexcited GaAs in strongly diffusive regime

    DEFF Research Database (Denmark)

    Mics, Zoltán; D’Angio, Andrea; Jensen, Søren A.;

    2013-01-01

    In a series of systematic optical pump–terahertz probe experiments, we study the density-dependent electron scattering rate in photoexcited GaAs in the regime of strong carrier diffusion. The terahertz frequency-resolved transient sheet conductivity spectra are perfectly described by the Drude...

  10. Altitude Dependence of Nightside Martian Suprathermal Electron Depletions as Revealed by MAVEN Observations

    Science.gov (United States)

    Steckiewicz, M.; Mazelle, C. X.; Garnier, P.; Andre, N.; Penou, E.; Beth, A.; Sauvaud, J. A.; Toublanc, D.; Mitchell, D. L.; McFadden, J. P.; Luhmann, J. G.; Lillis, R. J.; Connerney, J. E. P.; Espley, J. R.; Andersson, L.; Halekas, J. S.; Jakosky, B. M.

    2015-12-01

    The MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft is providing new detailed observations of the Martian ionosphere thanks to its unique orbital coverage and its sophisticated instrument suite. From November 16 2014 to February 28 2015 its periapsis sampled the nightside Northern latitudes of Mars from 30° to 75° down to 125 km altitude above regions with and without significant crustal magnetic sources. On almost each periapsis in the nightside ionosphere suprathermal electron depletions were detected. A simple but robust criterion based on data recorded by the Solar Wind Electron Analyzer (SWEA) was implemented in order to detect all these electron depletions. This resulted in a dataset of 1742 depletions identified on 457 orbits among the 494 orbits where data were available during the time period under study. A statistical analysis reveals that the main ion and electron populations within the depletions are surprisingly constant in time and altitude. Absorption by CO2 is the main loss process for suprathermal electrons and electrons strongly peaked around 6 eV are resulting from this interaction. The observation of depletions appears however highly dependent on altitude. Depletions are mainly located above strong crustal magnetic sources above 170 km whereas the depletions observed for the first time below 170 km are globally scattered onto the Martian surface with no particular dependence on crustal fields. These results will be supplemented with new MAVEN data obtained above the southern hemisphere and will be contrasted with similar observations obtained from previous missions.

  11. Time-dependent density functional theory for many-electron systems interacting with cavity photons.

    Science.gov (United States)

    Tokatly, I V

    2013-06-07

    Time-dependent (current) density functional theory for many-electron systems strongly coupled to quantized electromagnetic modes of a microcavity is proposed. It is shown that the electron-photon wave function is a unique functional of the electronic (current) density and the expectation values of photonic coordinates. The Kohn-Sham system is constructed, which allows us to calculate the above basic variables by solving self-consistent equations for noninteracting particles. We suggest possible approximations for the exchange-correlation potentials and discuss implications of this approach for the theory of open quantum systems. In particular we show that it naturally leads to time-dependent density functional theory for systems coupled to the Caldeira-Leggett bath.

  12. Time-dependent density-functional theory for open electronic systems

    Institute of Scientific and Technical Information of China (English)

    ZHENG Xiao; WANG RuLin

    2014-01-01

    Time-dependent density-functional theory(TDDFT)has been successfully applied to predict excited-state properties of isolated and periodic systems.However,it cannot address a system coupled to an environment or whose number of electrons is not conserved.To tackle these problems,TDDFT needs to be extended to accommodate open systems.This paper provides a comprehensive account of the recent developments of TDDFT for open systems(TDDFT-OS),including both theoretical and practical aspects.The practicality and accuracy of a latest TDDFT-OS method is demonstrated with two numerical examples:the time-dependent electron transport through a series of quasi-one-dimensional atomic chains,and the real-time electronic dynamics on a two-dimensional graphene surface.The advancement of TDDFT-OS may lead to promising applications in various fields of chemistry,including energy conversion and heterogeneous catalysis.

  13. SAGES: a suite of freely-available software tools for electronic disease surveillance in resource-limited settings.

    Directory of Open Access Journals (Sweden)

    Sheri L Lewis

    Full Text Available Public health surveillance is undergoing a revolution driven by advances in the field of information technology. Many countries have experienced vast improvements in the collection, ingestion, analysis, visualization, and dissemination of public health data. Resource-limited countries have lagged behind due to challenges in information technology infrastructure, public health resources, and the costs of proprietary software. The Suite for Automated Global Electronic bioSurveillance (SAGES is a collection of modular, flexible, freely-available software tools for electronic disease surveillance in resource-limited settings. One or more SAGES tools may be used in concert with existing surveillance applications or the SAGES tools may be used en masse for an end-to-end biosurveillance capability. This flexibility allows for the development of an inexpensive, customized, and sustainable disease surveillance system. The ability to rapidly assess anomalous disease activity may lead to more efficient use of limited resources and better compliance with World Health Organization International Health Regulations.

  14. Time-dependent radiolytic yields at room temperature and temperature-dependent absorption spectra of the solvated electrons in polyols

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900, 970, and 1000 mol-1·m2 for 1,2-ethanediol (12ED), 1,2-propanediol (12PD), and 1,3-propanediol (13PD), respectively. These values are two-third or three-fourth of the value usually reported in the published report.Picosecond pulse radiolysis studies have aided in depicting the radiolytic yield of the solvated electron in these solvents as a function of time from picosecond to microsecond. The radiolytic yield in these viscous solvents is found to be strongly different from that of the water solution. The temperature dependent absorption spectra of the solvated electron in 12ED, 12PD, and 13PD have been also investigated. In all the three solvents, the optical spectra shift to the red with increasing temperature. While the shape of the spectra does not change in 13PD, a widening on the blue side of the absorption band is observed in 12ED and 12PD at elevated temperatures.

  15. Effective electron displacements: A tool for time-dependent density functional theory computational spectroscopy

    Science.gov (United States)

    Guido, Ciro A.; Cortona, Pietro; Adamo, Carlo

    2014-03-01

    We extend our previous definition of the metric Δr for electronic excitations in the framework of the time-dependent density functional theory [C. A. Guido, P. Cortona, B. Mennucci, and C. Adamo, J. Chem. Theory Comput. 9, 3118 (2013)], by including a measure of the difference of electronic position variances in passing from occupied to virtual orbitals. This new definition, called Γ, permits applications in those situations where the Δr-index is not helpful: transitions in centrosymmetric systems and Rydberg excitations. The Γ-metric is then extended by using the Natural Transition Orbitals, thus providing an intuitive picture of how locally the electron density changes during the electronic transitions. Furthermore, the Γ values give insight about the functional performances in reproducing different type of transitions, and allow one to define a "confidence radius" for GGA and hybrid functionals.

  16. Momentum and Doping Dependence of Spin Excitations in Electron-Doped Cuprate Superconductors

    Science.gov (United States)

    Jing, Pengfei; Zhao, Huaisong; Kuang, Lülin; Lan, Yu; Feng, Shiping

    2017-01-01

    Superconductivity in copper oxides emerges on doping holes or electrons into their Mott-insulating parent compounds. The spin excitations are thought to be the mediating glue for the pairing in superconductivity. Here the momentum and doping dependence of the dynamical spin response in the electron-doped cuprate superconductors is studied based on the kinetic-energy-driven superconducting mechanism. It is shown that the dispersion of the low-energy spin excitations changes strongly upon electron doping; however, the hour-glass-shaped dispersion of the low-energy spin excitations appeared in the hole-doped case is absent on the electron-doped side due to the electron-hole asymmetry. In particular, the commensurate resonance appears in the superconducting state with the resonance energy that correlates with the dome-shaped doping dependence of the superconducting gap. Moreover, the spectral weight and dispersion of the high-energy spin excitations in the superconducting state are comparable with those in the corresponding normal state, indicating that the high-energy spin excitations do not play an important part in the pair formation.

  17. pH-dependent electron transfer reaction and direct bioelectrocatalysis of the quinohemoprotein pyranose dehydrogenase

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Kouta [Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); Matsumura, Hirotoshi; Ishida, Takuya [Department of Biomaterial Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657 (Japan); Yoshida, Makoto [Department of Environmental and Natural Resource Science, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509 (Japan); Igarashi, Kiyohiko; Samejima, Masahiro [Department of Biomaterial Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657 (Japan); Ohno, Hiroyuki [Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); Nakamura, Nobuhumi, E-mail: nobu1@cc.tuat.ac.jp [Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan)

    2016-08-26

    A pyranose dehydrogenase from Coprinopsis cinerea (CcPDH) is an extracellular quinohemoeprotein, which consists a b-type cytochrome domain, a pyrroloquinoline-quinone (PQQ) domain, and a family 1-type carbohydrate-binding module. The electron transfer reaction of CcPDH was studied using some electron acceptors and a carbon electrode at various pH levels. Phenazine methosulfate (PMS) reacted directly at the PQQ domain, whereas cytochrome c (cyt c) reacted via the cytochrome domain of intact CcPDH. Thus, electrons are transferred from reduced PQQ in the catalytic domain of CcPDH to heme b in the N-terminal cytochrome domain, which acts as a built-in mediator and transfers electron to a heterogenous electron transfer protein. The optimal pH values of the PMS reduction (pH 6.5) and the cyt c reduction (pH 8.5) differ. The catalytic currents for the oxidation of L-fucose were observed within a range of pH 4.5 to 11. Bioelectrocatalysis of CcPDH based on direct electron transfer demonstrated that the pH profile of the biocatalytic current was similar to the reduction activity of cyt c characters. - Highlights: • pH dependencies of activity were different for the reduction of cyt c and DCPIP. • DET-based bioelectrocatalysis of CcPDH was observed. • The similar pH-dependent profile was found with cyt c and electrode. • The present results suggested that IET reaction of CcPDH shows pH dependence.

  18. Electron kinetics dependence on gas pressure in laser-induced oxygen plasma experiment: Theoretical analysis

    Science.gov (United States)

    Gamal, Yosr E. E.-D.; Abdellatif, Galila

    2017-08-01

    A study is performed to investigate the dependency of threshold intensity on gas pressure observed in the measurements of the breakdown of molecular oxygen that carried out by Phuoc (2000) [1]. In this experiment, the breakdown was induced by 532 nm laser radiation of pulse width 5.5 ns and spot size of 8.5 μm, in oxygen over a wide pressure range (190-3000 Torr). The analysis aimed to explore the electron kinetic reliance on gas pressure for the separate contribution of each of the gain and loss processes encountered in this study. The investigation is based on an electron cascade model applied previously in Gamal and Omar (2001) [2] and Gaabour et al. (2013) [3]. This model solves numerically a differential equation designates the time evolution of the electron energy distribution, and a set of rate equations that describe the change of excited states population. The numerical examination of the electron energy distribution function and its parameters revealed that photo-ionization of the excited molecules plays a significant role in enhancing the electron density growth rate over the whole tested gas pressure range. This process is off set by diffusion of electrons out of the focal volume in the low-pressure regime. At atmospheric pressure electron, collisional processes dominate and act mainly to populate the excited states. Hence photo-ionization becomes efficient and compete with the encountered loss processes (electron diffusion, vibrational excitation of the ground state molecules as well as two body attachments). At high pressures ( 3000 Torr) three body attachments are found to be the primary cause of losses which deplete the electron density and hence results in the slow decrease of the threshold intensity.

  19. Temperature Dependence of Polarizability and Dispersion in Three, Two and One Dimensional Electron Gases

    Institute of Scientific and Technical Information of China (English)

    YAN Baorong; KONG Linghua; LV Jianhong; HU Xiwei

    2009-01-01

    Both temperature dependence of polarizability and plasmon dispersion in unmagnetized metal (or semiconductor) electron gases are investigated in this paper.It is obtained that,with a continuous variation of temperature in a large region,the polarizability and dispersion change non-monotonously.The static polarizability x(q,ω=0,μ,T) and dispersion ωp(q,T) for finite T in three,two and one dimensional electron gases are calculated numerically.In addition,dispersion relation ω(q) at a definite temperature (T≠0) is similar to that at T=0.

  20. Electric field dependence of the electron mobility in bulk wurtzite ZnO

    Indian Academy of Sciences (India)

    K Alfaramawi

    2014-12-01

    The electric field dependence of the electron mobility in bulk wurtzite zinc oxide (ZnO) material is studied. The low-field electron mobility is calculated as a function of doping concentration and lattice temperature. The results show that above nearly 50 K the electrical conduction is governed by activation through the bulk material and the conduction is then influenced by both lattice and impurity scattering mechanisms. The high-field characteristics are also considered. The transition between the low-field and high-field regions is specified. The negative differential mobility for bulk ZnO at room temperature is observed at electric fields above 280 kV/cm.

  1. Gafchromic EBT3 film dosimetry in electron beams - energy dependence and improved film read-out.

    Science.gov (United States)

    Sipilä, Petri; Ojala, Jarkko; Kaijaluoto, Sampsa; Jokelainen, Ilkka; Kosunen, Antti

    2016-01-01

    For megavoltage photon radiation, the fundamental dosimetry characteristics of Gafchromic EBT3 film were determined in 60Co gamma ray beam with addition of experimental and Monte Carlo (MC)-simulated energy dependence of the film for 6 MV photon beam and 6 MeV, 9 MeV, 12 MeV, and 16 MeV electron beams in water phantom. For the film read-out, two phase correction of scanner sensitivity was applied: a matrix correction for scanning area and dose-dependent correction by iterative procedure. With these corrections, the uniformity of response can be improved to be within ± 50 pixel values (PVs). To improve the read-out accuracy, a procedure with flipped film orientations was established. With the method, scanner uniformity can be improved further and dust particles, scratches and/or dirt on scan-ner glass can be detected and eliminated. Responses from red and green channels were averaged for read-out, which decreased the effect of noise present in values from separate channels. Since the signal level with the blue channel is considerably lower than with other channels, the signal variation due to different perturbation effects increases the noise level so that the blue channel is not recommended to be used for dose determination. However, the blue channel can be used for the detection of emulsion thickness variations for film quality evaluations with unexposed films. With electron beams ranging from 6 MeV to 16 MeV and at reference measurement conditions in water, the energy dependence of the EBT3 film is uniform within 0.5%, with uncertainties close to 1.6% (k = 2). Including 6 MV photon beam and the electron beams mentioned, the energy dependence is within 1.1%. No notable differences were found between the experimental and MC-simulated responses, indicating negligible change in intrinsic energy dependence of the EBT3 film for 6 MV photon beam and 6 MeV-16 MeV electron beams. Based on the dosimetric characteristics of the EBT3 film, the read-out procedure established

  2. Size-dependent crystalline fluctuation and growth mechanism of bismuth nanoparticles under electron beam irradiation

    Science.gov (United States)

    Wu, Sujuan; Jiang, Yi; Hu, Lijun; Sun, Jianguo; Wan, Piaopiao; Sun, Lidong

    2016-06-01

    Advanced nanofabrication requires accurate tailoring of various nanostructures with the assistance of electron or ion beam irradiation. However, evolution of the nanostructures under the beam irradiation significantly affects the fabrication process. It is thus of paramount importance to study the evolution behaviors and growth mechanism of the nanostructures. In this study, bismuth nanoparticles were selected to investigate crystalline fluctuation under electron beam irradiation via transmission electron microscopy. The results disclose size-dependent crystalline fluctuation of the nanoparticles. The particles exhibit crystalline and non-crystalline features for sizes of above 15 and below 4 nm, respectively, while a mixture of the two states is observed with sizes in between. The crystalline fluctuation facilitates the growth process of the particles when a crystalline particle is in contact with another non-crystalline one. This is promising for applications in nanofabrication where high quality interfaces are desired between two joining parts.Advanced nanofabrication requires accurate tailoring of various nanostructures with the assistance of electron or ion beam irradiation. However, evolution of the nanostructures under the beam irradiation significantly affects the fabrication process. It is thus of paramount importance to study the evolution behaviors and growth mechanism of the nanostructures. In this study, bismuth nanoparticles were selected to investigate crystalline fluctuation under electron beam irradiation via transmission electron microscopy. The results disclose size-dependent crystalline fluctuation of the nanoparticles. The particles exhibit crystalline and non-crystalline features for sizes of above 15 and below 4 nm, respectively, while a mixture of the two states is observed with sizes in between. The crystalline fluctuation facilitates the growth process of the particles when a crystalline particle is in contact with another non

  3. Spin-dependent electron transport through a magnetic resonant tunneling diode

    Science.gov (United States)

    Havu, P.; Tuomisto, N.; Väänänen, R.; Puska, M. J.; Nieminen, R. M.

    2005-06-01

    Electron-transport properties in nanostructures can be modeled, for example, by using the semiclassical Wigner formalism or the quantum-mechanical Green’s function formalism. We compare the performance and the results of these methods in the case of magnetic resonant-tunneling diodes. We have implemented the two methods within the self-consistent spin-density-functional theory. Our numerical implementation of the Wigner formalism is based on the finite-difference scheme whereas for the Green’s function formalism the finite-element method is used. As a specific application, we consider the device studied by Slobodskyy [Phys. Rev. Lett. 90, 246601 (2003)] and analyze their experimental results. The Wigner and Green’s function formalisms give similar electron densities and potentials but, surprisingly, the former method requires much more computer resources in order to obtain numerically accurate results for currents. Both of the formalisms can be used to model magnetic resonant tunneling diode structures.

  4. Credibility and legitimacy in policy-driven innovation networks: Resource dependencies and expectations in Dutch electric vehicle subsidies

    NARCIS (Netherlands)

    Van Rijnsoever, F.J.; Welle, L.; Bakker, S.

    2012-01-01

    The aim of this paper is to empirically examine the influence of different types of credibility on the legitimacy to grant individual actors within consortia an innovation subsidy. Theorizing from the resource dependence view and the sociology of expectations, we hypothesize that four types of credi

  5. Credibility and legitimacy in policy-driven innovation networks: resource dependencies and expectations in Dutch electric vehicle subsidies

    NARCIS (Netherlands)

    van Rijnsoever, F.J.; Welle, L.; Bakker, S.

    2014-01-01

    The aim of this paper is to empirically examine the influence of credibility on the likelihood to grant consortia of collaborating actors an innovation subsidy. Theorizing from the viewpoint of resource dependence theory and the sociology of expectations, we hypothesize that four types of credibilit

  6. Leidt het fenomeen Open Educational Resources tot nieuwe didactische modellen? “It depends"

    NARCIS (Netherlands)

    Didderen, Wim; Verjans, Steven

    2012-01-01

    Didderen, W., & Verjans, S. (2012). Leidt het fenomeen Open Educational Resources tot nieuwe didactische modellen? “It depends”. In R. Jacobi, & N. van der Woert (Eds.), Trendrapport Open Educational Resources 2012 (pp. 9-15). Utrecht: SURF Foundation - Special Interest Group Open Educational Resour

  7. Production and Resource Scheduling in Mass Customization with Dependent Setup Consideration

    DEFF Research Database (Denmark)

    Nielsen, Izabela Ewa; Bocewicz, G.; Do, Ngoc Anh Dung

    2014-01-01

    Mass customization has been implemented in services and manufactures to increase the competitiveness of companies. In a manufacturing company, the procedure for production and resource scheduling has to be changed to adapt to mass customization. A good production and resource scheduling will cont...

  8. Density dependence of electron mobility in the accumulation mode for fully depleted SOI films

    Energy Technology Data Exchange (ETDEWEB)

    Naumova, O. V., E-mail: naumova@isp.nsc.ru; Zaitseva, E. G.; Fomin, B. I.; Ilnitsky, M. A.; Popov, V. P. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

    2015-10-15

    The electron mobility µ{sub eff} in the accumulation mode is investigated for undepleted and fully depleted double-gate n{sup +}–n–n{sup +} silicon-on-insulator (SOI) metal–oxide–semiconductor field-effect transistors (MOSFET). To determine the range of possible values of the mobility and the dominant scattering mechanisms in thin-film structures, it is proposed that the field dependence of the mobility µ{sub eff} be replaced with the dependence on the density N{sub e} of induced charge carriers. It is shown that the dependences µ{sub eff}(N{sub e}) can be approximated by the power functions µ{sub eff}(N{sub e}) ∝ N{sub e}{sup -n}, where the exponent n is determined by the chargecarrier scattering mechanism as in the mobility field dependence. The values of the exponent n in the dependences µ{sub eff}(N{sub e}) are determined when the SOI-film mode near one of its surfaces varies from inversion to accumulation. The obtained results are explained from the viewpoint of the electron-density redistribution over the SOI-film thickness and changes in the scattering mechanisms.

  9. Impact of Electronic Resources and Usage in Academic Libraries in Ghana: Evidence from Koforidua Polytechnic & All Nations University College, Ghana

    Science.gov (United States)

    Akussah, Maxwell; Asante, Edward; Adu-Sarkodee, Rosemary

    2015-01-01

    The study investigates the relationship between impact of electronic resources and its usage in academic libraries in Ghana: evidence from Koforidua Polytechnic & All Nations University College, Ghana. The study was a quantitative approach using questionnaire to gather data and information. A valid response rate of 58.5% was assumed. SPSS…

  10. Utilization of Electronic Information Resources by Undergraduate Students of University of Ibadan: A Case Study of Social Sciences and Education

    Science.gov (United States)

    Owolabi, Sola; Idowu, Oluwafemi A.; Okocha, Foluke; Ogundare, Atinuke Omotayo

    2016-01-01

    The study evaluated utilization of electronic information resources by undergraduates in the Faculties of Education and the Social Sciences in University of Ibadan. The study adopted a descriptive survey design with a study population of 1872 undergraduates in the Faculties of Education and the Social Sciences in University of Ibadan, from which a…

  11. Constraints on exotic spin-dependent interactions between electrons from helium fine-structure spectroscopy

    Science.gov (United States)

    Ficek, Filip; Kimball, Derek F. Jackson; Kozlov, Mikhail G.; Leefer, Nathan; Pustelny, Szymon; Budker, Dmitry

    2017-03-01

    Agreement between theoretical calculations of atomic structure and spectroscopic measurements is used to constrain possible contribution of exotic spin-dependent interactions between electrons to the energy differences between states in helium-4. In particular, constraints on dipole-dipole interactions associated with the exchange of pseudoscalar bosons (such as axions or axion-like particles) with masses 10-2≲m ≲104eV are improved by a factor of ˜100 . The first atomic-scale constraints on several exotic velocity-dependent dipole-dipole interactions are established as well.

  12. Constraints on exotic spin-dependent interactions between electrons from helium fine-structure spectroscopy

    CERN Document Server

    Ficek, Filip; Kozlov, Mikhail; Leefer, Nathan; Pustelny, Szymon; Budker, Dmitry

    2016-01-01

    Agreement between theoretical calculations of atomic structure and spectroscopic measurements is used to constrain possible contribution of exotic spin-dependent interactions between electrons to the energy differences between states in helium-4. In particular, constraints on dipole-dipole interactions associated with the exchange of pseudoscalar bosons (such as axions or axion-like particles, ALPs) with masses $10^{-2}~{\\rm eV} \\lesssim m \\lesssim 10^{4}~{\\rm eV}$ are improved by a factor of $\\sim 100$. The first atomic-scale constraints on several exotic velocity-dependent dipole-dipole interactions are established as well.

  13. Temperature Dependence of Electron Spin Relaxation of 2,2-diphenyl-1-picrylhydrazyl in Polystyrene

    Science.gov (United States)

    Meyer, Virginia; Eaton, Sandra S.; Eaton, Gareth R.

    2012-01-01

    The electron spin relaxation rates for the stable radical DPPH (2,2-diphenyl-1-picrylhydrazyl) doped into polystyrene were studied by inversion recovery and electron spin echo at X-band and Q-band between 20 and 295 K. At low concentration (340 μM, 0.01%) spin-lattice relaxation was dominated by the Raman process and a local mode. At high concentration (140 mM, 5%) relaxation is orders of magnitude faster than at the lower concentration, and 1/T1 is approximately linearly dependent on temperature. Spin lattice relaxation rates are similar at X-band and Q-band. The temperature dependence of spin echo dephasing was faster at about 140 K than at higher or lower temperatures, which is attributed to a wagging motion of the phenyl groups. PMID:23565040

  14. Localized operator partitioning method for electronic excitation energies in the time-dependent density functional formalism

    CERN Document Server

    Nagesh, Jayashree; Brumer, Paul; Izmaylov, Artur F

    2016-01-01

    We extend the localized operator partitioning method (LOPM) [J. Nagesh, A.F. Izmaylov, and P. Brumer, J. Chem. Phys. 142, 084114 (2015)] to the time-dependent density functional theory (TD-DFT) framework to partition molecular electronic energies of excited states in a rigorous manner. A molecular fragment is defined as a collection of atoms using Stratman-Scuseria-Frisch atomic partitioning. A numerically efficient scheme for evaluating the fragment excitation energy is derived employing a resolution of the identity to preserve standard one- and two-electron integrals in the final expressions. The utility of this partitioning approach is demonstrated by examining several excited states of two bichromophoric compounds: 9-((1-naphthyl)-methyl)-anthracene and 4-((2-naphthyl)-methyl)-benzaldehyde. The LOPM is found to provide nontrivial insights into the nature of electronic energy localization that are not accessible using simple density difference analysis.

  15. Angular dependence, blackness and polarization effects in integral conversion electron Mössbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sajti, Sz., E-mail: sajti.szilard@wigner.mta.hu; Tanczikó, F.; Deák, L.; Nagy, D.L.; Bottyán, L.

    2015-01-01

    General expressions of the electron yield in {sup 57}Fe integral conversion electron Mössbauer spectroscopy were derived depending on the glancing angle of the γ photons, on the source polarization and on the isotopic abundance of the source and the absorber (blackness effects) using an exponential escape function of the electrons originating from all Mössbauer-resonance-related processes. The present approach provides a firm theoretical basis to determine the alignment and direction of magnetization in the absorber. The intensity formulae were justified by least squares fits of α-{sup 57}Fe spectral intensities measured in linearly and elliptically polarized source and absorber geometries. The fits reproduce the experimentally set angles with high accuracy. Limits of the current approach and its relation to other, less complete treatments in the literature are discussed.

  16. Towards a Quantitative Analysis of the Temperature Dependence of Electron Attachment Processes

    Science.gov (United States)

    2016-06-24

    chemical methods . All other molecular parameters needed in the modeling followed from quantum-chemical calculations done at the University of New Mexico ...of experimental observables such as pressure and temperature dependences of electron attachment rate constants and product branching ratios. Likewise... method for the treatment of such complicated kinetic processes was developed which will find application in many areas of chemical kinetics such as

  17. Electron-Positron Pair Production in Space- or Time-Dependent Electric Fields

    CERN Document Server

    Kleinert, Hagen; Xue, She-Sheng

    2008-01-01

    Treating the production of electron and positron pairs by a strong electric field from the vacuum as a quantum tunneling process we derive, in semiclassical approximation, a general expression for the pair production rate in a $z$-dependent electric field $E(z)$ pointing in the $z$-direction. We also allow for a smoothly varying magnetic field parallel to $E(z)$. The result is applied to a confined field $E(z)\

  18. Correlated electron dynamics and memory in time-dependent density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Thiele, Mark

    2009-07-28

    Time-dependent density functional theory (TDDFT) is an exact reformulation of the time-dependent many-electron Schroedinger equation, where the problem of many interacting electrons is mapped onto the Kohn-Sham system of noninteracting particles which reproduces the exact electronic density. In the Kohn-Sham system all non-classical many-body effects are incorporated in the exchange-correlation potential which is in general unknown and needs to be approximated. It is the goal of this thesis to investigate the connection between memory effects and correlated electron dynamics in strong and weak fields. To this end one-dimensional two-electron singlet systems are studied. At the same time these systems include the onedimensional helium atom model, which is an established system to investigate the crucial effects of correlated electron dynamics in external fields. The studies presented in this thesis show that memory effects are negligible for typical strong field processes. Here the approximation of the spatial nonlocality is of primary importance. For the photoabsorption spectra on the other hand the neglect of memory effects leads to qualitative and quantitative errors, which are shown to be connected to transitions of double excitation character. To develop a better understanding of the conditions under which memory effects become important quantum fluid dynamics has been found to be especially suitable. It represents a further exact reformulation of the quantum mechanic many-body problem which is based on hydrodynamic quantities such as density and velocity. Memory effects are shown to be important whenever the velocity field develops strong gradients and dissipative effects contribute. (orig.)

  19. Path dependence and path creation in strategic Human Resource Management: a comparative study of power generators in the Latrobe Valley, Victoria, Australia

    OpenAIRE

    Webber, Gwendoline Ernesta

    2017-01-01

    Since the early 1990s, the resource based view of the firm has been the dominant theoretical approach to strategic human resource management (SHRM). Proponents of the resource based view argue that organisations can achieve sustained competitive advantage from owning resources that are rare, valuable, inimitable and non-substitutable. Although theorists suggest resource inimitability is due in part to its 'path dependence', few SHRM studies have examined this phenomenon. Thi...

  20. Energetic dependency on the oil reserve- resources of crude oil in the world

    Directory of Open Access Journals (Sweden)

    Marína Sidorová

    2006-10-01

    Full Text Available Crude oil belongs to the most important energy resources nowadays., However its reserves are the smallest in comparison with other energy resources as coal, gas or uranium. The world oil consumption continuously increases and within 20-year period there could be about one third. So, the consumption of combustibles will probably increase and the reserves will decrease. Promising are new resources or a better utilization of primary sources. It´s a question of a short time when world scientists should think about this indisputably worldwide problem and would provide an equivalent substitution with an available ecological solution.

  1. Persistence in ratio-dependent models of consumer-resource dynamics

    Directory of Open Access Journals (Sweden)

    Claude Lobry

    2007-02-01

    Full Text Available In a recent work Cantrell, Cosner and Ruan show that intraspecific interference is responsible for coexistence of many consumers for one resource with a logistic like growth rate. Recently, we have established a similar result for the case of a chemostat using a rather different technique. In the present note, we complement these two works to the case of an unknown nonlinear growth rate for the resource satisfying mild assumptions.

  2. Dielectric-dependent Density Functionals for Accurate Electronic Structure Calculations of Molecules and Solids

    Science.gov (United States)

    Skone, Jonathan; Govoni, Marco; Galli, Giulia

    Dielectric-dependent hybrid [DDH] functionals have recently been shown to yield highly accurate energy gaps and dielectric constants for a wide variety of solids, at a computational cost considerably less than standard GW calculations. The fraction of exact exchange included in the definition of DDH functionals depends (self-consistently) on the dielectric constant of the material. In the present talk we introduce a range-separated (RS) version of DDH functionals where short and long-range components are matched using material dependent, non-empirical parameters. Comparing with state of the art GW calculations and experiment, we show that such RS hybrids yield accurate electronic properties of both molecules and solids, including energy gaps, photoelectron spectra and absolute ionization potentials. This work was supported by NSF-CCI Grant Number NSF-CHE-0802907 and DOE-BES.

  3. The dependence of the electronic conductivity of carbon molecular sieve electrodes on their charging states.

    Science.gov (United States)

    Pollak, Elad; Genish, Isaschar; Salitra, Gregory; Soffer, Abraham; Klein, Lior; Aurbach, Doron

    2006-04-13

    The dependence of the electronic conductivity of activated carbon electrodes on their potential in electrolyte solutions was examined. Kapton polymer films underwent carbonization (1000 degrees C), followed by a mild oxidation process (CO(2) at 900 degrees C) for various periods of time, to obtain carbons of different pore structures. A specially designed cell was assembled in order to measure the conductivity of carbon electrodes at different potentials in solutions. When the carbon electrodes possessed molecular sieving properties, a remarkable dependence of their conductivity on their charging state was observed. Aqueous electrolyte solutions containing ions of different sizes were used in order to demonstrate this phenomenon. As the average pore size of the activated carbons was larger, their molecular sieving ability was lower, and the dependence of their conductivity on their charging state regained its classical form. This behavior is discussed herein.

  4. Human resource requirements for quality-assured electronic data capture of the tuberculosis case register

    Directory of Open Access Journals (Sweden)

    Hoa Nguyen B

    2012-01-01

    Full Text Available Abstract Background The tuberculosis case register is the data source for the reports submitted by basic management units to the national tuberculosis program. Our objective was to measure the data entry time required to complete and double-enter one record, and to estimate the time for the correction of errors in the captured information from tuberculosis case registers in Cambodia and Viet Nam. This should assist in quantifying the additional requirements in human resources for national programs moving towards electronic recording and reporting. Methods Data from a representative sample of tuberculosis case registers from Cambodia and Viet Nam were double-entered and discordances resolved by rechecking the original case register. Computer-generated data entry time recorded the time elapsed between opening of a new record and saving it to disk. Results The dataset comprised 22,732 double-entered records of 11,366 patients (37.1% from Cambodia and 62.9% from Viet Nam. The mean data entry times per record were 97.5 (95% CI: 96.2-98.8 and 66.2 (95% CI: 59.5-73.0 seconds with medians of 90 and 31 s respectively in Cambodia and in Viet Nam. The percentage of records with an error was 6.0% and 39.0% respectively in Cambodia and Viet Nam. Data entry time was inversely associated with error frequency. We estimate that approximately 118-person-hours were required to produce 1,000 validated records. Conclusions This study quantifies differences between two countries for data entry time for the tuberculosis case register and frequencies of data entry errors and suggests that higher data entry speed is partially offset by requiring revisiting more records for corrections.

  5. Use and Cost of Electronic Resources in Central Library of Ferdowsi University Based on E-metrics

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Davarpanah

    2012-07-01

    Full Text Available The purpose of this study was to investigate the usage of electronic journals in Ferdowsi University, Iran based on e-metrics. The paper also aimed to emphasize the analysis of cost-benefit and the correlation between the journal impact factors and the usage data. In this study experiences of Ferdowsi University library on licensing and usage of electronic resources was evaluated by providing a cost-benefit analysis based on the cost and usage statistics of electronic resources. Vendor-provided data were also compared with local usage data. The usage data were collected by tracking web-based access locally, and by collecting vender-provided usage data. The data sources were one-year of vendor-supplied e-resource usage data such as Ebsco, Elsevier, Proquest, Emerald, Oxford and Springer and local usage data collected from the Ferdowsi university web server. The study found that actual usage values differ for vendor-provided data and local usage data. Elsevier has got the highest usage degree in searches, sessions and downloads. Statistics also showed that a small number of journals satisfy significant amount of use while the majority of journals were used less frequent and some were never used at all. The users preferred the PDF rather than HTML format. The data in subject profile suggested that the provided e-resources were best suited to certain subjects. There was no correlation between IF and electronic journal use. Monitoring the usage of e-resources gained increasing importance for acquisition policy and budget decisions. The article provided information about local metrics for the six surveyed vendors/publishers, e.g. usage trends, requests per package, cost per use as related to the scientific specialty of the university.

  6. Resource-dependent antagonistic coevolution leads to a new paradox of enrichment.

    Science.gov (United States)

    Zhang, Quan-Guo; Buckling, Angus

    2016-05-01

    The classical, ecological, paradox of enrichment describes a phenomenon that resource enrichment destabilizes predator-prey systems by exacerbating population oscillations. Here we suggest a new, evolutionary, paradox of enrichment. Resource enrichment can lead to more asymmetrical predator-prey coevolution (i.e., extremely high levels of prey defenses against predators) that decreases predator abundances and increases predator extinction risk. A major reason for this is that high resource availability can reduce fitness costs associated with prey defenses. In our experiments with a bacterium and its lytic phage, nutrient-balanced resource enrichment led to patterns in population demography and coevolutionary dynamics consistent with this coevolution-based paradox of enrichment; in particular, phage population extinction events were observed under nutrient-rich, not nutrient-poor, conditions. Consistent with ecological studies, carbon-biased resource enrichment (with carbon availability disproportionately increased relative to other nutrients) did not destabilize dynamics, and the asymmetry of coevolution was not altered in this context. Our work highlights the importance of integrating ecological and evolutionary thinking for studies of the consequences of nutrient pollution and other types of environmental changes.

  7. Domain-dependent electronic structure and optical absorption property in hybrid organic-inorganic perovskite.

    Science.gov (United States)

    Meng, Xiang; Zhang, Ruifeng; Fu, Zhongheng; Zhang, Qianfan

    2016-10-05

    Hybrid organic-inorganic perovskites, represented by materials in the CH3NH3PbI3 series, have become one of the most promising materials for solar cells with a high power conversion efficiency and low cost. The ordered Pb-I cage in such hybrid perovskites can induce the polarized cations to form a variety of polarization domains with long-range order, which will lead to the formation of specific atomic conformations or metastable crystalline phases, unique electronic band structures and optical absorption properties. Such domain-dependent characteristics play a critical role in the phase transition and service stability of such solar cells, and also open up the opportunity of tuning their electronic structure. In the present study, we systematically investigate the band structures and optical absorption properties of different electronically ordered domains in CH3NH3PbI3. By comparing different perovskites containing various cations, we have clarified the important influence of cation polarization on domain-dependent properties. Our results provide not only a possible pathway for the manipulation of band structure by applying an external field, but also a novel scheme for improving the performance and stability of hybrid perovskites.

  8. Polarization dependence in inelastic scattering of electrons by hydrogen atoms in a circularly polarized laser field

    Science.gov (United States)

    Buică, Gabriela

    2017-01-01

    We theoretically study the influence of laser polarization in inelastic scattering of electrons by hydrogen atoms in the presence of a circularly polarized laser field in the domain of field strengths below 107 V/cm and high projectile energies. A semi-perturbative approach is used in which the interaction of the projectile electrons with the laser field is described by Gordon-Volkov wave functions, while the interaction of the hydrogen atom with the laser field is described by first-order time-dependent perturbation theory. A closed analytical solution is derived in laser-assisted inelastic electron-hydrogen scattering for the 1 s → nl excitation cross section which is valid for both circular and linear polarizations. For the excitation of the n=2 levels simple analytical expressions of differential cross section are derived for laser-assisted inelastic scattering in the perturbative domain, and the differential cross sections by the circularly and linearly polarized laser fields and their ratios for one- and two-photon absorption are calculated as a function of the scattering angle. Detailed numerical results for the angular dependence and the resonance structure of the differential cross sections are discussed for the 1 s → 4 l excitations of hydrogen in a circularly polarized laser field.

  9. Proton-coupled electron transfers: pH-dependent driving forces? Fundamentals and artifacts.

    Science.gov (United States)

    Bonin, Julien; Costentin, Cyrille; Robert, Marc; Routier, Mathilde; Savéant, Jean-Michel

    2013-09-25

    Besides its own interest, tryptophan oxidation by photogenerated Ru complexes is one of the several examples where concerted proton-electron transfer (CPET) to water as proton acceptor endowed with a pH-dependent driving force has been invoked to explain the data. Since this notion is contrary to the very basic principles of chemical physics, it was interesting to attempt uncovering the source of this contradiction with an easily accessible substrate. Careful examination of the oxidation of the tryptophan (ethyl ester derivative) bearing a NH3(+)/NH2 group showed that there is no trace of such an unconventional H2O-CPET with a pH-dependent driving force. The reaction mechanism simply consists, with both the NH3(+) acid and NH2 basic forms of the tryptophan derivative, in a rate-determining electron-transfer step followed by deprotonation steps. The same is true with the ethyl ester-methyl amide derivative of tryptophan, whose behavior is even simpler since the molecule does not bear an acid-base group. No such unconventional H2O-CPET was found with phenol, another easily accessible substrate. It may thus be inferred that the same applies to less easily available systems in which electron transfer occurs intramolecularly. These observations help to rid the road of such artificial obstacles and improve present models of H2O-CPET reactions, a landmark towards the understanding of the role of water chains in natural systems.

  10. Temperature dependence of band gaps in semiconductors: electron-phonon interaction

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, Reinhard K.; Cardona, M.; Lauck, R. [MPI for Solid State Research, Stuttgart (Germany); Bhosale, J.; Ramdas, A.K. [Physics Dept., Purdue University, West Lafayette, IN (United States); Burger, A. [Fisk University, Dept. of Life and Physical Sciences, Nashville, TN (United States); Munoz, A. [MALTA Consolider Team, Dept. de Fisica Fundamental II, Universidad de La Laguna, Tenerife (Spain); Instituto de Materiales y Nanotecnologia, Universidad de La Laguna, Tenerife (Spain); Romero, A.H. [CINVESTAV, Dept. de Materiales, Unidad Queretaro, Mexico (Mexico); MPI fuer Mikrostrukturphysik, Halle an der Saale (Germany)

    2013-07-01

    We investigate the temperature dependence of the energy gap of several semiconductors with chalcopyrite structure and re-examine literature data and analyze own high-resolution reflectivity spectra in view of our new ab initio calculations of their phonon properties. This analysis leads us to distinguish between materials with d-electrons in the valence band (e.g. CuGaS{sub 2}, AgGaS{sub 2}) and those without d-electrons (e.g. ZnSnAs{sub 2}). The former exhibit a rather peculiar non-monotonic temperature dependence of the energy gap which, so far, has resisted cogent theoretical description. We demonstrate it can well be fitted by including two Bose-Einstein oscillators with weights of opposite sign leading to an increase at low-T and a decrease at higher T's. We find that the energy of the former correlates well with characteristic peaks in the phonon density of states associated with low-energy vibrations of the d-electron constituents.

  11. Resonant Spin-Flavor Conversion of Supernova Neutrinos: Dependence on Electron Mole Fraction

    CERN Document Server

    Yoshida, T; Kimura, K; Yokomakura, H; Kawagoe, S; Kajino, T

    2009-01-01

    Detailed dependence of resonant spin-flavor (RSF) conversion of supernova neutrinos on electron mole fraction Ye is investigated. Supernova explosion forms a hot-bubble and neutrino-driven wind region of which electron mole fraction exceeds 0.5 in several seconds after the core collapse. When a higher resonance of the RSF conversion is located in the innermost region, flavor change of the neutrinos strongly depends on the sign of 1-2Ye. At an adiabatic high RSF resonance the flavor conversion of bar{nu}_e -> nu_{mu,tau} occurs in Ye 0.5 and inverted mass hierarchy. In other cases of Ye values and mass hierarchies, the conversion of nu_e -> bar{nu}_{mu,tau} occurs. The final bar{nu}_e spectrum is evaluated in the cases of Ye 0.5 taking account of the RSF conversion. Based on the obtained result, time variation of the event number ratios of low bar{nu}_e energy to high bar{nu}_e energy is discussed. In normal mass hierarchy, an enhancement of the event ratio should be seen in the period when the electron frac...

  12. Scale Dependence of Female Ungulate Reproductive Success in Relation to Nutritional Condition, Resource Selection and Multi-Predator Avoidance.

    Directory of Open Access Journals (Sweden)

    Jared F Duquette

    Full Text Available Female ungulate reproductive success is dependent on the survival of their young, and affected by maternal resource selection, predator avoidance, and nutritional condition. However, potential hierarchical effects of these factors on reproductive success are largely unknown, especially in multi-predator landscapes. We expanded on previous research of neonatal white-tailed deer (Odocoileus virginianus daily survival within home ranges to assess if resource use, integrated risk of 4 mammalian predators, maternal nutrition, winter severity, hiding cover, or interactions among these variables best explained landscape scale variation in daily or seasonal survival during the post-partum period. We hypothesized that reproductive success would be limited greater by predation risk at coarser spatiotemporal scales, but habitat use at finer scales. An additive model of daily non-ideal resource use and maternal nutrition explained the most (69% variation in survival; though 65% of this variation was related to maternal nutrition. Strong support of maternal nutrition across spatiotemporal scales did not fully support our hypothesis, but suggested reproductive success was related to dam behaviors directed at increasing nutritional condition. These behaviors were especially important following severe winters, when dams produced smaller fawns with less probability of survival. To increase nutritional condition and decrease wolf (Canis lupus predation risk, dams appeared to place fawns in isolated deciduous forest patches near roads. However, this resource selection represented non-ideal resources for fawns, which had greater predation risk that led to additive mortalities beyond those related to resources alone. Although the reproductive strategy of dams resulted in greater predation of fawns from alternative predators, it likely improved the life-long reproductive success of dams, as many were late-aged (>10 years old and could have produced multiple litters

  13. Quantum electrodynamical time-dependent density functional theory for many-electron systems on a lattice

    Science.gov (United States)

    Farzanehpour, Mehdi; Tokatly, Ilya; Nano-Bio Spectroscopy Group; ETSF Scientific Development Centre Team

    2015-03-01

    We present a rigorous formulation of the time-dependent density functional theory for interacting lattice electrons strongly coupled to cavity photons. We start with an example of one particle on a Hubbard dimer coupled to a single photonic mode, which is equivalent to the single mode spin-boson model or the quantum Rabi model. For this system we prove that the electron-photon wave function is a unique functional of the electronic density and the expectation value of the photonic coordinate, provided the initial state and the density satisfy a set of well defined conditions. Then we generalize the formalism to many interacting electrons on a lattice coupled to multiple photonic modes and prove the general mapping theorem. We also show that for a system evolving from the ground state of a lattice Hamiltonian any density with a continuous second time derivative is locally v-representable. Spanish Ministry of Economy and Competitiveness (Grant No. FIS2013-46159-C3-1-P), Grupos Consolidados UPV/EHU del Gobierno Vasco (Grant No. IT578-13), COST Actions CM1204 (XLIC) and MP1306 (EUSpec).

  14. Phase dependent structural and electronic properties of lanthanum orthophosphate (LaPO4)

    Science.gov (United States)

    Neupane, M. R.; Garrett, G. A.; Rudin, S.; Andzelm, J. W.

    2016-05-01

    We study the phase-dependent structural and electronic properties of bulk LaPO4, using density functional theory (DFT). The applicability of conventional semi-local and hybrid functionals in predicting structural and electronic properties of monoclinic and hexagonal LaPO4 is evaluated by comparing results to available experimental data. The monoclinic LaPO4 was found to be more stable than the hexagonal phase in ambient conditions with a small energy difference, suggesting a possibility of a phase transition. Both the phases in the bulk form are found to be diamagnetic with indirect energy gaps. These results are consistent with available experimental results. In the monoclinic phase, the hybrid functionals predict indirect band gap at about 8 eV. Furthermore, the calculated indirect-direct transition energy offset (ΔE) in the hexagonal phase was three times lower than the monoclinic phase. Our calculations based on hybrid functionals also reveal that the states near the conduction band edge in the hexagonal LaPO4 are strongly hybridized between La and PO4 states. By analyzing the band dispersion around the band edges, we show that the hexagonal phase has lighter electron effective mass, as compared to the monoclinic phase. With a larger energy gap, smaller ΔE, and smaller electron effective mass, the hexagonal LaPO4 might be a promising candidate material as an n-type transparent oxide.

  15. Role of acoustic phonons in frequency dependent electronic thermal conductivity of graphene

    Science.gov (United States)

    Bhalla, Pankaj

    2017-03-01

    We study the effect of the electron-phonon interaction on the finite frequency dependent electronic thermal conductivity of two dimensional graphene. We calculate it for various acoustic phonons present in graphene and characterized by different dispersion relations using the memory function approach. It is found that the electronic thermal conductivity κe (T) in the zero frequency limit follows different power law for the longitudinal/transverse and the flexural acoustic phonons. For the longitudinal/transverse phonons, κe (T) ∼T-1 at the low temperature and saturates at the high temperature. These signatures qualitatively agree with the results calculated by solving the Boltzmann equation analytically and numerically. Similarly, for the flexural phonons, we find that κe (T) shows T 1 / 2 law at the low temperature and then saturates at the high temperature. In the finite frequency regime, we observe that the real part of the electronic thermal conductivity, Re [κe (ω , T) ] follows ω-2 behavior at the low frequency and becomes frequency independent at the high frequency.

  16. Excitation energies with time-dependent density matrix functional theory: Singlet two-electron systems.

    Science.gov (United States)

    Giesbertz, K J H; Pernal, K; Gritsenko, O V; Baerends, E J

    2009-03-21

    Time-dependent density functional theory in its current adiabatic implementations exhibits three striking failures: (a) Totally wrong behavior of the excited state surface along a bond-breaking coordinate, (b) lack of doubly excited configurations, affecting again excited state surfaces, and (c) much too low charge transfer excitation energies. We address these problems with time-dependent density matrix functional theory (TDDMFT). For two-electron systems the exact exchange-correlation functional is known in DMFT, hence exact response equations can be formulated. This affords a study of the performance of TDDMFT in the TDDFT failure cases mentioned (which are all strikingly exhibited by prototype two-electron systems such as dissociating H(2) and HeH(+)). At the same time, adiabatic approximations, which will eventually be necessary, can be tested without being obscured by approximations in the functional. We find the following: (a) In the fully nonadiabatic (omega-dependent, exact) formulation of linear response TDDMFT, it can be shown that linear response (LR)-TDDMFT is able to provide exact excitation energies, in particular, the first order (linear response) formulation does not prohibit the correct representation of doubly excited states; (b) within previously formulated simple adiabatic approximations the bonding-to-antibonding excited state surface as well as charge transfer excitations are described without problems, but not the double excitations; (c) an adiabatic approximation is formulated in which also the double excitations are fully accounted for.

  17. Doping and strain dependence of the electronic band structure in Ge and GeSn alloys

    Science.gov (United States)

    Xu, Chi; Gallagher, James; Senaratne, Charutha; Brown, Christopher; Fernando, Nalin; Zollner, Stefan; Kouvetakis, John; Menendez, Jose

    2015-03-01

    A systematic study of the effect of dopants and strain on the electronic structure of Ge and GeSn alloys is presented. Samples were grown by UHV-CVD on Ge-buffered Si using Ge3H8 and SnD4 as the sources of Ge and Sn, and B2H6/P(GeH3)3 as dopants. High-energy critical points in the joint-density of electronic states were studied using spectroscopic ellipsometry, which yields detailed information on the strain and doping dependence of the so-called E1, E1 +Δ1 , E0' and E2 transitions. The corresponding dependencies of the lowest direct band gap E0 and the fundamental indirect band gap Eindwere studied via room-T photoluminescence spectroscopy. Of particular interest for this work were the determination of deformation potentials, band gap renormalization effects, Burstein-Moss shifts due to the presence of carriers at band minima, and the dependence of other critical point parameters, such as amplitudes and phase angles, on the doping concentration. The selective blocking of transitions due to high doping makes it possible to investigate the precise k-space location of critical points. These studies are complemented with detailed band-structure calculations within a full-zone k-dot- p approach. Supported by AFOSR under DOD AFOSR FA9550-12-1-0208 and DOD AFOSR FA9550-13-1-0022.

  18. Effects of temperature and electron effective mass on bias-dependent tunnelling magnetoresistance

    Institute of Scientific and Technical Information of China (English)

    Li Fei-Fei; Li Zheng-Zhong; Xiao Ming-Wen

    2005-01-01

    In this paper, we study the effects of temperature and electron effective mass within the barrier on the bias dependence and sign-change behaviour of the tunnelling magnetoresistance (TMR) in ferromagnetic junctions. A significant decrease of the tunnelling magnetoresistance with increasing temperature is obtained, in accordance with the experiments. In addition to the height of barrier potential (φ) discussed in our previous papers, the electron effective mass (mB) within the barrier region is found to be another important factor that physically controls the sign-change behaviour of the TMR. The critical voltage (Vc) at which TMR changes sign will increase with φ and decrease with mB. Furthermore, both the zero-bias TMR and Vc will decrease if the temperature rises. These results would be of practical use for experimental investigations.

  19. Stacking-dependent electronic property of trilayer graphene epitaxially grown on Ru(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Que, Yande; Xiao, Wende, E-mail: wdxiao@iphy.ac.cn, E-mail: hjgao@iphy.ac.cn; Chen, Hui; Wang, Dongfei; Du, Shixuan; Gao, Hong-Jun, E-mail: wdxiao@iphy.ac.cn, E-mail: hjgao@iphy.ac.cn [Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-12-28

    The growth, atomic structure, and electronic property of trilayer graphene (TLG) on Ru(0001) were studied by low temperature scanning tunneling microscopy and spectroscopy in combined with tight-binding approximation (TBA) calculations. TLG on Ru(0001) shows a flat surface with a hexagonal lattice due to the screening effect of the bottom two layers and the AB-stacking in the top two layers. The coexistence of AA- and AB-stacking in the bottom two layers leads to three different stacking orders of TLG, namely, ABA-, ABC-, and ABB-stacking. STS measurements combined with TBA calculations reveal that the density of states of TLG with ABC- and ABB-stacking is characterized by one and two sharp peaks near to the Fermi level, respectively, in contrast to the V-shaped feature of TLG with ABA-stacking. Our work demonstrates that TLG on Ru(0001) might be an ideal platform for exploring stacking-dependent electronic properties of graphene.

  20. Distinguishing electronic and vibronic coherence in 2D spectra by their temperature dependence

    CERN Document Server

    Perlík, Václav; Šanda, František; Hauer, Jürgen

    2013-01-01

    Long-lived oscillations in 2D spectra of chlorophylls are at the heart of an ongoing debate. Their physical origin is either a multi-pigment effect, such as excitonic coherence, or primarily stems from localized vibrations. In the present work, we analyze distinguishing characteristics of relative phase difference measured between diagonal- and cross-peak oscillations. While direct discrimination between the two scenarios is obscured when peaks overlap, their sensitivity to temperature provides a stronger argument. We show that vibrational (vibronic) oscillations change relative phase with temperature, while electronic oscillations are only weakly dependent. This highlights that studies of relative phase difference as a function of temperature provide a clear and easily accessible method to distinguish between vibrational and electronic coherences.

  1. Coral cavity sponges depend on reef-derived food resources: stable isotope and fatty acid constraints

    NARCIS (Netherlands)

    van Duyl, F.C.; Moodley, L.; Nieuwland, G.; van IJzerloo, L.; van Soest, R.W.M.; Houtekamer, M.; Meesters, E.H.; Middelburg, J.J.

    2011-01-01

    The diet of cavity sponges on the narrow fringing reefs of Curaçao, Caribbean was studied. The origin and resources of the bulk food of these sponges, i.e., dissolved organic matter (DOM), were identified using stable carbon and nitrogen isotopes and fatty acid biomarkers. We found that phytoplankto

  2. Coral cavity sponges depend on reef-derived food resources: stable isotope and fatty acid constraints

    NARCIS (Netherlands)

    van Duyl, F.C.; Moodley, L.; Nieuwland, G.; van Ijzerloo, L.; van Soest, R.W.M.; Houtekamer, M.; Meesters, E.H.; Middelburg, J.J.

    2011-01-01

    The diet of cavity sponges on the narrow fringing reefs of Cura double dagger ao, Caribbean was studied. The origin and resources of the bulk food of these sponges, i.e., dissolved organic matter (DOM), were identified using stable carbon and nitrogen isotopes and fatty acid biomarkers. We found tha

  3. Coral cavity sponges depend on reef-derived food resources: stable isotope and fatty acid constraints

    NARCIS (Netherlands)

    Duyl, F.C. van; Moodley, L.; Nieuwland, G.; IJzerloo, L. van; Soest, R.W.M. van; Houtekamer, M.; Meesters, E.H.; Middelburg, J.J.

    2011-01-01

    The diet of cavity sponges on the narrow fringing reefs of Curac¸ao, Caribbean was studied. The origin and resources of the bulk food of these sponges, i.e., dissolved organic matter (DOM), were identified using stable carbon and nitrogen isotopes and fatty acid biomarkers. We found that phytoplankt

  4. Selfish mothers indeed! Resource-dependent conflict over extended parental care in free-ranging dogs.

    Science.gov (United States)

    Paul, Manabi; Majumder, Sreejani Sen; Nandi, Anjan K; Bhadra, Anindita

    2015-12-01

    Parent-offspring conflict (POC) theory provides an interesting premise for understanding social dynamics in facultatively social species. In free-ranging dogs, mothers increase conflict over extended parental care with their pups beyond the weaning stage. In this study, we investigated whether resource quality affects POC in the dogs that typically live in a highly competitive environment as scavengers. We built a theoretical model to predict the alternative options available to the mother in the context of food sharing with her pups when protein-rich food (meat) is provided, as compared to carbohydrate-rich food (biscuits). We fit the mothers' response from experimental data to the model and show that the mothers choose a selfish strategy, which can in turn ensure higher lifetime reproductive success, while depriving the current litter access to better resources. These results have interesting implications for understanding the social dynamics of the dogs, and the emergence of facultative sociality in a species that evolved from strongly social ancestors. We speculate that the tendency of increased conflict in resource-rich conditions might have driven the process of domestication in the ancestors of dogs which defected from their groups in favour of richer resources around human settlements.

  5. Foreign Dependence of Aluminum Resources has Difficulty to be Reduced Significantly

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>Insufficient resource guarantee ability has long been a bottleneck restricting the development of nonferrous metal industry, and aluminum is no exception. According to data from the China Nonferrous Metal Industry Association, during the "Eleventh Five Year" period China’s bauxite import volume presented a spiral upward trend. In 2010 China’s bauxite import volume

  6. Coral cavity sponges depend on reef-derived food resources: stable isotope and fatty acid constraints

    NARCIS (Netherlands)

    Duyl, F.C. van; Moodley, L.; Nieuwland, G.; IJzerloo, L. van; Soest, R.W.M. van; Houtekamer, M.; Meesters, E.H.; Middelburg, J.J.

    2011-01-01

    The diet of cavity sponges on the narrow fringing reefs of Curac¸ao, Caribbean was studied. The origin and resources of the bulk food of these sponges, i.e., dissolved organic matter (DOM), were identified using stable carbon and nitrogen isotopes and fatty acid biomarkers. We found that

  7. Coral cavity sponges depend on reef-derived food resources: stable isotope and fatty acid constraints

    NARCIS (Netherlands)

    van Duyl, F.C.; Moodley, L.; Nieuwland, G.; van Ijzerloo, L.; van Soest, R.W.M.; Houtekamer, M.; Meesters, E.H.; Middelburg, J.J.

    2011-01-01

    The diet of cavity sponges on the narrow fringing reefs of Cura double dagger ao, Caribbean was studied. The origin and resources of the bulk food of these sponges, i.e., dissolved organic matter (DOM), were identified using stable carbon and nitrogen isotopes and fatty acid biomarkers. We found

  8. Coral cavity sponges depend on reef-derived food resources: stable isotope and fatty acid constraints

    NARCIS (Netherlands)

    van Duyl, F.C.; Moodley, L.; Nieuwland, G.; van IJzerloo, L.; van Soest, R.W.M.; Houtekamer, M.; Meesters, E.H.; Middelburg, J.J.

    2011-01-01

    The diet of cavity sponges on the narrow fringing reefs of Curaçao, Caribbean was studied. The origin and resources of the bulk food of these sponges, i.e., dissolved organic matter (DOM), were identified using stable carbon and nitrogen isotopes and fatty acid biomarkers. We found that

  9. Intensity dependent waiting time for strong electron trapping events in speckle stimulated raman scatter

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Harvey [Los Alamos National Laboratory; Daughton, W [Los Alamos National Laboratory; Yin, L [Los Alamos National Laboratory

    2009-01-01

    The onset of Stimulated Raman scatter from an intense laser speckle is the simplest experimentally realizable laser-plasma-interaction environment. Despite this data and recent 3D particle simulations, the controlling mechanism at the onset of backscatter in the kinetic regime when strong electron trapping in the daughter Langmuir wave is a dominant nonlinearity is not understood. This paper explores the consequences of assuming that onset is controlled by large thermal fluctuations. A super exponential dependence of mean reflectivity on speckle intensity in the onset regime is predicted.

  10. Hot-electron-assisted femtochemistry at surfaces: A time-dependent density functional theory approach

    DEFF Research Database (Denmark)

    Gavnholt, Jeppe; Rubio, Angel; Olsen, Thomas;

    2009-01-01

    Using time-evolution time-dependent density functional theory (TDDFT) within the adiabatic local-density approximation, we study the interactions between single electrons and molecular resonances at surfaces. Our system is a nitrogen molecule adsorbed on a ruthenium surface. The surface is modeled...... resonance and the lowering of the resonance energy due to an image charge effect. Finally we apply the TDDFT procedure to only consider the decay of molecular excitations and find that it agrees quite well with the width of the projected density of Kohn-Sham states....

  11. Scintillation yield and time dependence from electronic and nuclear recoils in liquid neon

    CERN Document Server

    Lippincott, W H; Gastler, D; Kearns, E; McKinsey, D N; Nikkel, J A

    2011-01-01

    We have performed measurements of scintillation light in liquid neon, observing a signal yield in our detector as high as (3.5 $\\pm$ 0.4) photoelectrons/keV. We measure pulse shape discrimination efficiency between electronic and nuclear recoils in liquid neon from 50 and 300 keV nuclear recoil energy. We also measure the \\leff\\, parameter in liquid neon between 30 and 370 keV nuclear recoil energy, observing an average \\leff$=0.24$ above 50 keV. We observe a dependence of the scintillation time distribution and signal yield on the pressure and temperature of the liquid neon.

  12. Alignment dependent ultrafast electron-nuclear dynamics in high-order harmonic generation

    CERN Document Server

    Li, Mu-Zi; Bian, Xue-Bin

    2016-01-01

    We investigated the high-order harmonic generation (HHG) process of diatomic molecular ion $\\mathrm{H}_2^+$ in non-Born-Oppenheimer approximations. The corresponding three-dimensional time-dependent Schr\\"odinger equation is solved with arbitrary alignment angles. It is found that the nuclear motion can lead to spectral modulation of HHG. Redshifts are unique in molecular HHG which decrease with the increase of alignment angles of the molecules and are sensitive to the initial vibrational states. It can be used to extract the ultrafast electron-nuclear dynamics and image molecular structure.

  13. Superconductivity without dependence on valence electron density in Zn doped YBCO systems

    Institute of Scientific and Technical Information of China (English)

    Li Ping-Lin; Wang Yong-Yong; Tian Yong-Tao; Wang Jing; Niu Xiao-Li; Wang Jun-Xi; Wang Dan-Dan; Wang Xiao-Xia

    2008-01-01

    This paper reports that the YBa2Cu3-xZnxO7-δ(x=0-0.4)samples are researched by means of x-ray diffraction,calculations of binding energy,the positron experiments and variations of oxygen content.The results of simulated calculations,positron experiments and variations of oxygen content support the existence of cluster effect.Moreover,it is concluded that the cluster effect is an important factor on suppression of high-Tc cuprate superconductivity and the Tc does not depend on the density of valence electron directly.

  14. Temperature and relative humidity dependence of radiochromic film dosimeter response to gamma electron radiation

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Puhl, J.M.; Miller, A.

    1995-01-01

    on some earlier studies, their response functions have been reported to be dependent on the temperature and relative humidity during irradiation. The present study investigates differences in response over practical ranges of temperature, relative humidity, dose, and for different recent batches of films...... of both types. It is observed that for each new batch of film to be used for radiation processing, the effects of such parameters on response to both gamma rays and electrons should be investigated. It is also suggested that the films should be packaged under controlled atmospheric conditions (relative...

  15. Intensity dependent waiting time for strong electron trapping events in speckle stimulated raman scatter

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Harvey [Los Alamos National Laboratory; Daughton, W [Los Alamos National Laboratory; Yin, L [Los Alamos National Laboratory

    2009-01-01

    The onset of Stimulated Raman scatter from an intense laser speckle is the simplest experimentally realizable laser-plasma-interaction environment. Despite this data and recent 3D particle simulations, the controlling mechanism at the onset of backscatter in the kinetic regime when strong electron trapping in the daughter Langmuir wave is a dominant nonlinearity is not understood. This paper explores the consequences of assuming that onset is controlled by large thermal fluctuations. A super exponential dependence of mean reflectivity on speckle intensity in the onset regime is predicted.

  16. Use and User Perception of Electronic Information Resources: A Case Study of Siva Institute of Frontier Technology, India

    Directory of Open Access Journals (Sweden)

    Velmurugan Chandran

    2013-12-01

    Full Text Available The present study aims to explore the use and user perception of electronic resources in Siva Institute of Frontier Technology, India. A total number of 123 users were taken into account for the study through a questionnaire-based survey method. A well-structured questionnaire was designed and distributed to the selected 200 students and staff members. 123 copies of the questionnaires were returned dully filled in and the overall response rate was 61.50 percent. The questionnaire contained both open- and close-ended questions. The collected data were classified, analyzed, and tabulated by using simple statistical methods. This study covers the impact of electronic resources on students and faculty in their academic pursuit.

  17. Modeling molecule-plasmon interactions using quantized radiation fields within time-dependent electronic structure theory

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Daniel R.; DePrince, A. Eugene, E-mail: deprince@chem.fsu.edu [Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390 (United States)

    2015-12-07

    We present a combined cavity quantum electrodynamics/ab initio electronic structure approach for simulating plasmon-molecule interactions in the time domain. The simple Jaynes-Cummings-type model Hamiltonian typically utilized in such simulations is replaced with one in which the molecular component of the coupled system is treated in a fully ab initio way, resulting in a computationally efficient description of general plasmon-molecule interactions. Mutual polarization effects are easily incorporated within a standard ground-state Hartree-Fock computation, and time-dependent simulations carry the same formal computational scaling as real-time time-dependent Hartree-Fock theory. As a proof of principle, we apply this generalized method to the emergence of a Fano-like resonance in coupled molecule-plasmon systems; this feature is quite sensitive to the nanoparticle-molecule separation and the orientation of the molecule relative to the polarization of the external electric field.

  18. Electron radiation effects on time-dependent dielectric breakdown in SiO2 films

    Science.gov (United States)

    Li, S. P.; Maserjian, J.

    1975-01-01

    An experiment testing the effect of ionizing radiation on breakdown characteristics of SiO2 films is presented. Silicon wafers were oxidized and metallized, and a capacitor array was etched into a control sample while the rest were first irradiated with 1 MeV electrons and then etched. Time-dependent dielectric tests were made on all the capacitors, and the average characteristics of 96 capacitors are illustrated graphically. The curves are consistent with the model of holes trapped in the SiO2 film during irradiation leading to a retarding field for positive ion emission and drift toward the interface. It is shown how an externally applied field is reduced by the trapped charge, and that changes in the dielectric breakdown properties of the SiO2 film after irradiation depend on the positive trapped charge near the metal interface.

  19. Layer-dependent anisotropic electronic structure of freestanding quasi-two-dimensional Mo S 2

    KAUST Repository

    Hong, Jinhua

    2016-02-29

    The anisotropy of the electronic transition is a well-known characteristic of low-dimensional transition-metal dichalcogenides, but their layer-thickness dependence has not been properly investigated experimentally until now. Yet, it not only determines the optical properties of these low-dimensional materials, but also holds the key in revealing the underlying character of the electronic states involved. Here we used both angle-resolved electron energy-loss spectroscopy and spectral analysis of angle-integrated spectra to study the evolution of the anisotropic electronic transition involving the low-energy valence electrons in the freestanding MoS2 layers with different thicknesses. We are able to demonstrate that the well-known direct gap at 1.8 eV is only excited by the in-plane polarized field while the out-of-plane polarized optical gap is 2.4 ± 0.2 eV in monolayer MoS2. This contrasts with the much smaller anisotropic response found for the indirect gap in the few-layer MoS2 systems. In addition, we determined that the joint density of states associated with the indirect gap transition in the multilayer systems and the corresponding indirect transition in the monolayer case has a characteristic three-dimensional-like character. We attribute this to the soft-edge behavior of the confining potential and it is an important factor when considering the dynamical screening of the electric field at the relevant excitation energies. Our result provides a logical explanation for the large sensitivity of the indirect transition to thickness variation compared with that for the direct transition, in terms of quantum confinement effect.

  20. On-Line Dependability Enhancement of Multiprocessor SoCs by Resource Management

    NARCIS (Netherlands)

    Braak, ter T.D.; Burgess, S.T.; Hurskainen, H.; Kerkhoff, H.G.; Vermeulen, B.; Zhang, Xiao

    2010-01-01

    This paper describes a new approach towards dependable design of homogeneous multi-processor SoCs in an example satellite-navigation application. First, the NoC dependability is functionally verified via embedded software. Then the Xentium processor tiles are periodically verified via on-line self-t

  1. How Human Resource Professionals Use Electronic Channels to Communicate CSR : A case study focused on Solvay's French industrial sites

    OpenAIRE

    Fournet, Clara; Pauly, Marissa

    2015-01-01

    Corporate Social Responsibility (CSR) has become a large concern for many companies with the rise of globalization. Oftentimes, companies are encouraged to communicate CSR externally, but not internally. This research focuses upon the internal communication of CSR, specifically how Human Resource (HR) professionals use electronic channels to communicate to employees. The scope of this research is focused solely upon HR professionals within Solvay’s French industrial sites, which produce chemi...

  2. Challenges in the implementation of an electronic surveillance system in a resource-limited setting: Alerta, in Peru

    Directory of Open Access Journals (Sweden)

    Soto Giselle

    2008-11-01

    Full Text Available Abstract Background Infectious disease surveillance is a primary public health function in resource-limited settings. In 2003, an electronic disease surveillance system (Alerta was established in the Peruvian Navy with support from the U.S. Naval Medical Research Center Detachment (NMRCD. Many challenges arose during the implementation process, and a variety of solutions were applied. The purpose of this paper is to identify and discuss these issues. Methods This is a retrospective description of the Alerta implementation. After a thoughtful evaluation according to the Centers for Disease Control and Prevention (CDC guidelines, the main challenges to implementation were identified and solutions were devised in the context of a resource-limited setting, Peru. Results After four years of operation, we have identified a number of challenges in implementing and operating this electronic disease surveillance system. These can be divided into the following categories: (1 issues with personnel and stakeholders; (2 issues with resources in a developing setting; (3 issues with processes involved in the collection of data and operation of the system; and (4 issues with organization at the central hub. Some of the challenges are unique to resource-limited settings, but many are applicable for any surveillance system. For each of these challenges, we developed feasible solutions that are discussed. Conclusion There are many challenges to overcome when implementing an electronic disease surveillance system, not only related to technology issues. A comprehensive approach is required for success, including: technical support, personnel management, effective training, and cultural sensitivity in order to assure the effective deployment of an electronic disease surveillance system.

  3. Tracking the Flow of Resources in Electronic Waste - The Case of End-of-Life Computer Hard Disk Drives.

    Science.gov (United States)

    Habib, Komal; Parajuly, Keshav; Wenzel, Henrik

    2015-10-20

    Recovery of resources, in particular, metals, from waste flows is widely seen as a prioritized option to reduce their potential supply constraints in the future. The current waste electrical and electronic equipment (WEEE) treatment system is more focused on bulk metals, where the recycling rate of specialty metals, such as rare earths, is negligible compared to their increasing use in modern products, such as electronics. This study investigates the challenges in recovering these resources in the existing WEEE treatment system. It is illustrated by following the material flows of resources in a conventional WEEE treatment plant in Denmark. Computer hard disk drives (HDDs) containing neodymium-iron-boron (NdFeB) magnets were selected as the case product for this experiment. The resulting output fractions were tracked until their final treatment in order to estimate the recovery potential of rare earth elements (REEs) and other resources contained in HDDs. The results further show that out of the 244 kg of HDDs treated, 212 kg comprising mainly of aluminum and steel can be finally recovered from the metallurgic process. The results further demonstrate the complete loss of REEs in the existing shredding-based WEEE treatment processes. Dismantling and separate processing of NdFeB magnets from their end-use products can be a more preferred option over shredding. However, it remains a technological and logistic challenge for the existing system.

  4. The impact of electronic healthcare associated infection surveillance software on infection prevention resources: A systematic review of the literature.

    Science.gov (United States)

    Russo, Philip L; Shaban, Ramon Z; MacBeth, Deborough; Carter, Abigail; Mitchell, Brett G

    2017-09-08

    Surveillance of healthcare-associated infections is fundamental for infection prevention. The methods and practices for surveillance have evolved as technology becomes more advanced. The availability of electronic surveillance software (ESS) has increased, and yet adoption of ESS is slow. It is argued that ESS deliver savings through automation, particularly in terms of human resourcing and infection prevention (IP) staff time. This paper describes the findings of a systematic review on the impact of ESS on IP resources. A systematic search was conducted of electronic databases Medline and the Cumulative Index to Nursing and Allied Health Literature published between 1st January 2006 and 31(st) December 2016 with analysis using Newcastle-Ottawa Scale. 2832 articles were reviewed of which 16 studies met the inclusion criteria. IP resources were identified as time undertaken on surveillance. A reduction in IP staff time to undertake surveillance was demonstrated in 13 studies. The reduction proportion ranged from 12.5% - 98.4% (mean 73.9%). The remaining three did not allow for any estimation of the effect in terms of IP staff time. None of the studies demonstrated an increase in IP staff time. The results of this review demonstrate that adopting ESS yield considerable dividends in IP staff time relating to data collection and case ascertainment whilst maintaining high levels of sensitivity and specificity. This has the potential to enable reinvestment into other components of IP to maximise efficient use of scare IP resources. Copyright © 2017. Published by Elsevier Ltd.

  5. A revised electronic Hessian for approximate time-dependent density functional theory.

    Science.gov (United States)

    Ziegler, Tom; Seth, Michael; Krykunov, Mykhaylo; Autschbach, Jochen

    2008-11-14

    Time-dependent density functional theory (TD-DFT) at the generalized gradient level of approximation (GGA) has shown systematic errors in the calculated excitation energies. This is especially the case for energies representing electron transitions between two separated regions of space or between orbitals of different spatial extents. It will be shown that these limitations can be attributed to the electronic ground state Hessian G(GGA). Specifically, we shall demonstrate that the Hessian G(GGA) can be used to describe changes in energy due to small perturbations of the electron density (Deltarho), but it should not be applied to one-electron excitations involving the density rearrangement (Deltarho) of a full electron charge. This is in contrast to Hartree-Fock theory where G(HF) has a trust region that is accurate for both small perturbations and one-electron excitations. The large trust radius of G(HF) can be traced back to the complete cancellation of Coulomb and exchange terms in Hartree-Fock (HF) theory representing self-interaction (complete self-interaction cancellation, CSIC). On the other hand, it is shown that the small trust radius for G(GGA) can be attributed to the fact that CSIC is assumed for GGA in the derivation of G(GGA) although GGA (and many other approximate DFT schemes) exhibits incomplete self-interaction cancellation (ISIC). It is further shown that one can derive a new matrix G(R-DFT) with the same trust region as G(HF) by taking terms due to ISIC properly into account. Further, with TD-DFT based on G(R-DFT), energies for state-to-state transitions represented by a one-electron excitation (psi(i)-->psi(a)) are approximately calculated as DeltaE(ai). Here DeltaE(ai) is the energy difference between the ground state Kohn-Sham Slater determinant and the energy of a Kohn-Sham Slater determinant where psi(i) has been replaced by psi(a). We make use of the new Hessian in two numerical applications involving charge-transfer excitations. It is

  6. HELP (INFORMATION ELECTRONIC RESOURCE "CHRONICLE OF ONU: DATES, FACTS, EVENTS": HISTORY OF UNIVERSITY IN INFORMATION SPACE

    Directory of Open Access Journals (Sweden)

    А. М. Гавриленко

    2016-03-01

    Object of research is the help information resource "The chronicle of the Odessa national university of I. I. Mechnikov: dates, facts, events". The main objective of our article – to state the main methodological bases of creation of information resource. One of advantages of information resource is possibility of continuous updating and replenishment by new information. Main objective of creation of this information resource is systematization of material on stories of the Odessa national university of I. I. Mechnikov from the date of his basis to the present, ensuring interactive access to information on the main dates, the most significant events in life of university. The base of research are sources on the history of university, chronology of historical development, formation of infrastructure, cadres and scientific researches. In information resource the main stages of development, functioning and transformation of the Odessa University are analyzed, information on its divisions is collected. For creation of this information resource in Scientific library the method of work was developed, the main selection criteria of data are allocated. This information resource have practical value for all who is interested in history of university, historians, scientists-researchers of history of science and the city of Odessa.

  7. On state-dependant sampling for nonlinear controlled systems sharing limited computational resources

    OpenAIRE

    Alamir, Mazen

    2007-01-01

    21 pages. soumis à la revue "IEEE Transactions on Automatic Control"; International audience; In this paper, a framework for dynamic monitoring of sampling periods for nonlinear controlled systems is proposed. This framework is particularly adapted to the context of controlled systems sharing limited computational resources. The proposed scheme can be used in a cascaded structure with any feedback scheduling design. Illustrative examples are given to assess the efficiency of the proposed fram...

  8. Resource Dependent Radio Allocation For Battlefield Communications - A Data Model Approach

    Directory of Open Access Journals (Sweden)

    Gregor Thomeczek

    2014-10-01

    Full Text Available Network Enabled Capability (NEC and the Land Open Systems Architecture (LOSA are novel approaches to enable interoperability between a heterogeneous collection of assets in the battlefield. These paradigms utilise an underlying network for cooperation between deployed battlefield equipment. NEC and LOSA have great potential to transform military communications and enhance integrated survivability as well as situational awareness, but the Achilles’ heel of NEC and LOSA is the wireless spectrum over which they must communicate. A noisy and dynamic battlefield wireless spectrum as well as an array of heterogeneous wireless communications equipment handling multiple types of data with different Quality of Service (QoS requirements requires a system which manages and allocates these communication resources effectively. This paper presents the High Availability Wireless Communications (HAWC system, a hardware agnostic communications controller middleware to manage any combination of existing and future multiband wireless resources. The system utilises a vehicle’s data model to gather information about available radio resources and enable LOSA by meeting communications data requirements and delivering appropriate QoS to the appropriate traffic in a fleet of vehicles. The functionality of the system is verified by using behavioural simulation on a virtual battlefield.

  9. Influence of soliton distributions on the spin-dependent electronic transport through polyacetylene molecule

    Indian Academy of Sciences (India)

    Ketabi S A; Nakhaee M

    2016-03-01

    In this paper, a detailed numerical study of the role of selected soliton distributions on the spin-dependent transport through {\\it trans}-polyacetylene (PA) molecule is presented. The molecule is attached symmetrically to magnetic semi-infinite three-dimensional electrodes. Based on Su–Schrieffer–Heeger (SSH) Hamiltonian and using a generalized Green’s function formalism, wecalculate the spin-dependent currents, the electronic transmission and tunnelling magnetoresistance (TMR). We found that the presence of a uniform distribution of the soliton centres along the molecular chain reduced the size of the band gap of {\\it trans}-PA molecule. Moreover, a sublattice of the correlated solitons as binary clusters, which are randomly distributed along the chain, can induce extended electronic states in the band gap of the molecule. In this case, the band gap of the molecule is suppressed and at lower voltages, the TMR bandwidth is narrowed. The current–voltage characteristic then shows an ohmic-like behaviour.

  10. Wavevector dependent electron -phonon coupling drives the CDW formation in TbTe3

    Science.gov (United States)

    Rosenkranz, S.; Maschek, M.; Weber, F.; Heid, R.; Said, A. H.; Giraldo-Gallo, P.; Fisher, I. R.

    2015-03-01

    The charge density wave (CDW) transition in the rare-earth tritellurides RTe3 (R =rare earth) is commonly assumed to originate from a textbook Fermi surface nesting instability. Contrary to this weak coupling scenario, our investigation of the soft phonon mode in TbTe3 provides direct evidence that the periodicity of the CDW superstructure in this canonical compound is defined by a strong momentum dependence of the electron-phonon coupling. Our high-resolution inelastic x-ray measurements reveal a renormalization of the soft-phonon energy and a strong broadening of the soft-phonon linewidth over a large part of reciprocal space adjacent to the CDW ordering vector. Our detailed theoretical calculations reproduce these observations very well and show that the position in reciprocal space of the phonon renormalization, and with it the CDW order wavevector, is not related to Fermi surface nesting. Our results demonstrate the importance of strongly momentum dependent electron-phonon coupling in defining the CDW order, which could also be relevant to many other systems. Work supported by U.S. DOE BES-MSE.

  11. The magnetism and spin-dependent electronic transport properties of boron nitride atomic chains.

    Science.gov (United States)

    An, Yipeng; Zhang, Mengjun; Wu, Dapeng; Fu, Zhaoming; Wang, Tianxing; Jiao, Zhaoyong; Wang, Kun

    2016-07-28

    Very recently, boron nitride atomic chains were successively prepared and observed in experiments [O. Cretu et al., ACS Nano 8, 11950 (2015)]. Herein, using a first-principles technique, we study the magnetism and spin-dependent electronic transport properties of three types of BN atomic chains whose magnetic moment is 1 μB for BnNn-1, 2 μB for BnNn, and 3 μB for BnNn+1 type atomic chains, respectively. The spin-dependent electronic transport results demonstrate that the short BnNn+1 chain presents an obvious spin-filtering effect with high spin polarization ratio (>90%) under low bias voltages. Yet, this spin-filtering effect does not occur for long BnNn+1 chains under high bias voltages and other types of BN atomic chains (BnNn-1 and BnNn). The proposed short BnNn+1 chain is predicted to be an effective low-bias spin filters. Moreover, the length-conductance relationships of these BN atomic chains were also studied.

  12. Electron Beam Irradiation Dose Dependently Damages the Bacillus Spore Coat and Spore Membrane

    Directory of Open Access Journals (Sweden)

    S. E. Fiester

    2012-01-01

    Full Text Available Effective control of spore-forming bacilli begs suitable physical or chemical methods. While many spore inactivation techniques have been proven effective, electron beam (EB irradiation has been frequently chosen to eradicate Bacillus spores. Despite its widespread use, there are limited data evaluating the effects of EB irradiation on Bacillus spores. To study this, B. atrophaeus spores were purified, suspended in sterile, distilled water, and irradiated with EB (up to 20 kGy. Irradiated spores were found (1 to contain structural damage as observed by electron microscopy, (2 to have spilled cytoplasmic contents as measured by spectroscopy, (3 to have reduced membrane integrity as determined by fluorescence cytometry, and (4 to have fragmented genomic DNA as measured by gel electrophoresis, all in a dose-dependent manner. Additionally, cytometry data reveal decreased spore size, increased surface alterations, and increased uptake of propidium iodide, with increasing EB dose, suggesting spore coat alterations with membrane damage, prior to loss of spore viability. The present study suggests that EB irradiation of spores in water results in substantial structural damage of the spore coat and inner membrane, and that, along with DNA fragmentation, results in dose-dependent spore inactivation.

  13. The magnetism and spin-dependent electronic transport properties of boron nitride atomic chains

    Science.gov (United States)

    An, Yipeng; Zhang, Mengjun; Wu, Dapeng; Fu, Zhaoming; Wang, Tianxing; Jiao, Zhaoyong; Wang, Kun

    2016-07-01

    Very recently, boron nitride atomic chains were successively prepared and observed in experiments [O. Cretu et al., ACS Nano 8, 11950 (2015)]. Herein, using a first-principles technique, we study the magnetism and spin-dependent electronic transport properties of three types of BN atomic chains whose magnetic moment is 1 μB for BnNn-1, 2 μB for BnNn, and 3 μB for BnNn+1 type atomic chains, respectively. The spin-dependent electronic transport results demonstrate that the short BnNn+1 chain presents an obvious spin-filtering effect with high spin polarization ratio (>90%) under low bias voltages. Yet, this spin-filtering effect does not occur for long BnNn+1 chains under high bias voltages and other types of BN atomic chains (BnNn-1 and BnNn). The proposed short BnNn+1 chain is predicted to be an effective low-bias spin filters. Moreover, the length-conductance relationships of these BN atomic chains were also studied.

  14. The Dose Rate Dependence of the Yield of Trapped Electrons in Crystalline Ice

    DEFF Research Database (Denmark)

    Nilsson, Johan Daniel Göran; Pagsberg, Palle Bjørn

    1980-01-01

    for the experimental dose rate dependence observed at −10° C. The reaction with the protons has a negative temperature coefficient while the reaction with the OH radicals has an activation energy of about 14 kcal mole−1. The mobility of the proton was estimated to be about 3 × 10−4 cm2 V−1 S−1 at −10°C.......The yield of localized excess electrons in crystalline H2O ice has been studied as a function of the dose rate at various temperatures in the range −10 to −40°C. The G value was found to decrease significantly with increasing dose rate. Thus it appears that the localization of electrons takes place...... in competition with other reactions and we propose a simple model where we assume that the mobile electrons can undergo bimolecular bulk reactions with protons and OH radicals. Rate constants of 3.0 × 1015 M−1 S−1 and 1.4 × 1014 M−1 S−1 for the two reactions were required in the model in order to account...

  15. Temperature and detection-wavelength dependence of the electron transfer rates in initial stages of photosynthesis.

    Science.gov (United States)

    Kurzynski, Michal; Chelminiak, Przemyslaw

    2013-10-17

    Unusual temperature behavior, observed in the initial electron transfer stages in the photosynthetic reaction centers of the purple bacteria, and a strong probing pulse wavelength dependence of transfer rates, determined in transient absorption spectroscopy, can easily be explained on assuming that the transfer takes place from dynamically unrelaxed states of protein environment. The transitions from the primary special pair (P) to a single bacteriochlorophyll (B) and next to a bacteriopheophytin (H) are controlled by diffusion down the energy value of underdamped vibrational modes of frequency 200 K, probably determining distances between the succeeding cofactors. The subsequent transition to the quinone A (Q) is controlled by diffusion in the position value of an overdamped conformational mode, probably corresponding to the local polarization. From the fit of available experimental data to simple theoretical formulas, the important physical conclusion arises that the very electronic transitions are fast as compared to the relaxation processes and, in the first approximation, only the latter contribute to the overall times of the initial electron transfer stages in photosynthesis.

  16. Effect of Access to an Electronic Medical Resource on Performance Characteristics of a Certification Examination: A Randomized Controlled Trial.

    Science.gov (United States)

    Lipner, Rebecca S; Brossman, Bradley G; Samonte, Kelli M; Durning, Steven J

    2017-09-05

    Electronic resources are increasingly used in medical practice. Their use during high-stakes certification examinations has been advocated by many experts, but whether doing so would affect the capacity to differentiate between high and low abilities is unknown. To determine the effect of electronic resources on examination performance characteristics. Randomized controlled trial. Medical certification program. 825 physicians initially certified by the American Board of Internal Medicine (ABIM) who passed the Internal Medicine Certification examination or sat for the Internal Medicine Maintenance of Certification (IM-MOC) examination in 2012 to 2015. Participants were randomly assigned to 1 of 4 conditions: closed book using typical or additional time, or open book (that is, UpToDate [Wolters Kluwer]) using typical or additional time. All participants took the same modified version of the IM-MOC examination. Primary outcomes included item difficulty (how easy or difficult the question was), item discrimination (how well the question differentiated between high and low abilities), and average question response time. Secondary outcomes included examination dimensionality (that is, the number of factors measured) and test-taking strategy. Item response theory was used to calculate question characteristics. Analysis of variance compared differences among conditions. Closed-book conditions took significantly less time than open-book conditions (mean, 79.2 seconds [95% CI, 78.5 to 79.9 seconds] vs. 110.3 seconds [CI, 109.2 to 111.4 seconds] per question). Mean discrimination was statistically significantly higher for open-book conditions (0.34 [CI, 0.32 to 0.35] vs. 0.39 [CI, 0.37 to 0.41] per question). A strong single dimension showed that the examination measured the same factor with or without the resource. Only 1 electronic resource was evaluated. Inclusion of an electronic resource with time constraints did not adversely affect test performance and did not change

  17. Understanding intention to use electronic information resources: A theoretical extension of the technology acceptance model (TAM).

    Science.gov (United States)

    Tao, Donghua

    2008-11-06

    This study extended the Technology Acceptance Model (TAM) by examining the roles of two aspects of e-resource characteristics, namely, information quality and system quality, in predicting public health students' intention to use e-resources for completing research paper assignments. Both focus groups and a questionnaire were used to collect data. Descriptive analysis, data screening, and Structural Equation Modeling (SEM) techniques were used for data analysis. The study found that perceived usefulness played a major role in determining students' intention to use e-resources. Perceived usefulness and perceived ease of use fully mediated the impact that information quality and system quality had on behavior intention. The research model enriches the existing technology acceptance literature by extending TAM. Representing two aspects of e-resource characteristics provides greater explanatory information for diagnosing problems of system design, development, and implementation.

  18. Building and Managing Electronic Resources in Digital Era in India with Special Reference to IUCAA and NIV, Pune: A Comparative Case Study

    Science.gov (United States)

    Sahu, H. K.; Singh, S. N.

    2015-04-01

    This paper discusses and presents a comparative case study of two libraries in Pune, India, Inter-University Centre for Astronomy and Astrophysics and Information Centre and Library of National Institute of Virology (Indian Council of Medical Research). It compares how both libraries have managed their e-resource collections, including acquisitions, subscriptions, and consortia arrangements, while also developing a collection of their own resources, including pre-prints and publications, video lectures, and other materials in an institutional repository. This study illustrates how difficult it is to manage electronic resources in a developing country like India, even though electronic resources are used more than print resources. Electronic resource management can be daunting, but with a systematic approach, various problems can be solved, and use of the materials will be enhanced.

  19. Scheduling sampling to maximize information about time dependence in experiments with limited resources

    DEFF Research Database (Denmark)

    Græsbøll, Kaare; Christiansen, Lasse Engbo

    2013-01-01

    Looking for periodicity in sampled data requires that periods (lags) of different length are represented in the sampling plan. We here present a method to assist in planning of temporal studies with sparse resources, which optimizes the number of observed time lags for a fixed amount of samples...... within a fixed time window given a maximum time lag of interest. The method can also optimize the temporal sampling specifically for situations where samples are at risk of being rescheduled due to otherwise unpredictable events such as weather, faulty equipment, etc. The method is based on the framework...

  20. Symmetry breaking in mass-recruiting ants: extent of foraging biases depends on resource quality.

    Science.gov (United States)

    Price, R I'Anson; Grüter, C; Hughes, W O H; Evison, S E F

    2016-01-01

    The communication involved in the foraging behaviour of social insects is integral to their success. Many ant species use trail pheromones to make decisions about where to forage. The strong positive feedback caused by the trail pheromone is thought to create a decision between two or more options. When the two options are of identical quality, this is known as symmetry breaking, and is important because it helps colonies to monopolise food sources in a competitive environment. Symmetry breaking is thought to increase with the quantity of pheromone deposited by ants, but empirical studies exploring the factors affecting symmetry breaking are limited. Here, we tested if (i) greater disparity between two food sources increased the degree to which a higher quality food source is favoured and (ii) if the quality of identical food sources would affect the degree of symmetry breaking that occurs. Using the mass-recruiting Pharaoh ant, Monomorium pharaonis, we carried out binary choice tests to investigate how food quality affects the choice and distribution of colony foraging decisions. We found that colonies could coordinate foraging to exploit food sources of greater quality, and a greater contrast in quality between the food sources created a stronger collective decision. Contrary to prediction, we found that symmetry breaking decreased as the quality of two identical food sources increased. We discuss how stochastic effects might lead to relatively strong differences in the amount of pheromone on alternative routes when food source quality is low. Pheromones used by social insects should guide a colony via positive feedback to distribute colony members at resources in the most adaptive way given the current environment. This study shows that when food resources are of equal quality, Pharaoh ant foragers distribute themselves more evenly if the two food sources are both of high quality compared to if both are of low quality. The results highlight the way in which

  1. Print and Electronic Resources: Usage Statistics at Guru Gobind Singh Indraprastha University Library

    Science.gov (United States)

    Kapoor, Kanta

    2010-01-01

    Purpose: The purpose of this paper is to quantify the use of electronic journals in comparison with the print collections in the Guru Gobind Singh Indraprastha University Library. Design/methodology/approach: A detailed analysis was made of the use of lending services, the Xerox facility and usage of electronic journals such as Science Direct,…

  2. Print and Electronic Resources: Usage Statistics at Guru Gobind Singh Indraprastha University Library

    Science.gov (United States)

    Kapoor, Kanta

    2010-01-01

    Purpose: The purpose of this paper is to quantify the use of electronic journals in comparison with the print collections in the Guru Gobind Singh Indraprastha University Library. Design/methodology/approach: A detailed analysis was made of the use of lending services, the Xerox facility and usage of electronic journals such as Science Direct,…

  3. Universal logarithmic temperature dependence of magnetic susceptibility of one-dimensional electrons at critical values of magnetic field

    OpenAIRE

    Vekua, Temo

    2014-01-01

    We study the leading low temperature dependence of magnetic susceptibility of one-dimensional electrons with fixed total number of particles at the magnetic fields equal to zero temperature critical values where magnetic field induces commensurate-incommensurate quantum phase transitions. For free and repulsively interacting electrons there is only one such critical field corresponding to the transition to the fully polarized state. For attractively interacting electrons besides saturation fi...

  4. Mechanism of Electron Excitation and Emission from a Nanoribbon under Pulsed Laser Irradiation: Time-Dependent First-Principles Study

    Science.gov (United States)

    Miyauchi, Shota; Watanabe, Kazuyuki

    2017-03-01

    A time-dependent density functional theory simulation demonstrated the sequential dynamics of electron excitation and emission from a silicene nanoribbon under a femtosecond laser pulse. The mechanism for the multiphoton absorption processes that are responsible for the kinetic-energy spectra of emitted electrons was elucidated using Kohn-Sham potentials and the decomposition scheme.

  5. An analysis of the temperature dependence of the electron density in CdGeAs sub 2

    CERN Document Server

    Borisenko, S I

    2001-01-01

    Analysis of temperature dependence of electron density in single crystals grown by a new method has been performed. Values of concentration of intrinsic defects and the energy of activation is calculated. It is shown, that the energy of activation has a resonant character, and concentration of intrinsic defects in the investigated range of temperatures 10-500 K considerably exceeds the concentration of electrons

  6. STRONG VELOCITY DEPENDENCE OF ELECTRON-CAPTURE IN COLLISIONS BETWEEN ALIGNED NA-ASTERISK(3P) AND HE-2+

    NARCIS (Netherlands)

    SCHLATMANN, AR; HOEKSTRA, R; MORGENSTERN, R; OLSON, RE; PASCALE, J

    1993-01-01

    By analyzing spectra of emitted photons, we have studied state-selective electron capture in collisions of He2+ on aligned Na*(3p) atoms that span the ''velocity-matching'' energy between projectile and target electron. We find a strong dependence of the capture cross sections on the Na*(3p) orbital

  7. Intention to use and actual use of electronic information resources: further exploring Technology Acceptance Model (TAM).

    Science.gov (United States)

    Tao, Donghua

    2009-11-14

    Following up a previous study that examined public health students' intention to use e-resources for completing research paper assignments, the present study proposed two models to investigate whether or not public health students actually used the e-resources they intended to use and whether or not the determinants of intention to use predict actual use of e-resources. Focus groups and pre- and post-questionnaires were used to collect data. Descriptive analysis, data screening, and Structural Equation Modeling (SEM) techniques were used for data analysis. The study found that the determinants of intention-to-use significantly predict actual use behavior. Direct impact of perceived usefulness and indirect impact of perceived ease of use to both behavior intention and actual behavior indicated the importance of ease of use at the early stage of technology acceptance. Non-significant intention-behavior relationship prompted thoughts on the measurement of actual behavior and multidimensional characteristics of the intention construct.

  8. Coral cavity sponges depend on reef-derived food resources: stable isotope and fatty acid constraints.

    Science.gov (United States)

    van Duyl, Fleur C; Moodley, Leon; Nieuwland, Gerard; van Ijzerloo, Lennart; van Soest, Rob W M; Houtekamer, Marco; Meesters, Erik H; Middelburg, Jack J

    2011-01-01

    The diet of cavity sponges on the narrow fringing reefs of Curaçao, Caribbean was studied. The origin and resources of the bulk food of these sponges, i.e., dissolved organic matter (DOM), were identified using stable carbon and nitrogen isotopes and fatty acid biomarkers. We found that phytoplankton and its derived DOM from the adjacent open sea and from reef overlying water is not the main source of food for most of the sponges examined nor is bacterioplankton. Interestingly, dual stable isotope signatures (δ(13)Corg, δ(15)Norg) and fatty acid biomarkers appoint coral mucus and organic matter derived from crustose coralline algae (CCA) as probable food sources for encrusting sponges. Mucus-derived DOM may contribute up to 66% to the diet of examined sponges based on results of dual isotope mixing model analysis. The contribution of CCA (as purported representative for benthic algae) was smaller with values up to 31%. Together, mucus- and CCA-derived substrates contributed for 48-73% to the diet of sponges. The presence of the exogenous fatty acid 20:4ω6 in sponges, which is abundant in coral mucus of Madracis mirabilis and in CCA, highlights these reef-derived resources as sources of nutrition for DOM feeding cavity sponges. The relatively high concentrations of exogenous 20:4ω6 in all sponges examined supports our hypothesis that the bulk of the food of the cavity sponge community is reef-derived. Our results imply that cavity sponges play an important role in conserving food and energy produced within the reef.

  9. Strong Asymmetric Charge Carrier Dependence in Inelastic Electron Tunneling Spectroscopy of Graphene Phonons.

    Science.gov (United States)

    Natterer, Fabian D; Zhao, Yue; Wyrick, Jonathan; Chan, Yang-Hao; Ruan, Wen-Ying; Chou, Mei-Yin; Watanabe, Kenji; Taniguchi, Takashi; Zhitenev, Nikolai B; Stroscio, Joseph A

    2015-06-19

    The observation of phonons in graphene by inelastic electron tunneling spectroscopy has been met with limited success in previous measurements arising from weak signals and other spectral features which inhibit a clear distinction between phonons and miscellaneous excitations. Utilizing a back-gated graphene device that allows adjusting the global charge carrier density, we introduce an averaging method where individual tunneling spectra at varying charge carrier density are combined into one representative spectrum. This method improves the signal for inelastic transitions while it suppresses dispersive spectral features. We thereby map the total graphene phonon density of states, in good agreement with density functional calculations. Unexpectedly, an abrupt change in the phonon intensity is observed when the graphene charge carrier type is switched through a variation of the back-gate electrode potential. This sudden variation in phonon intensity is asymmetric in the carrier type, depending on the sign of the tunneling bias.

  10. Electronic friction near metal surfaces: a case where molecule-metal couplings depend on nuclear coordinates

    CERN Document Server

    Dou, Wenjie

    2016-01-01

    We derive an explicit form for the electronic friction as felt by a molecule near a metal surface for the general case that molecule-metal couplings depend on nuclear coordinates. Our work generalizes a previous study by von Oppen et al [Beilstein Journal of Nanotechnology, 3, 144, 2012], where we now go beyond the Condon approximation (i.e. molecule-metal couplings are not held constant). Using a non-equilibrium Green's function formalism in the adiabatic limit, we show that fluctuating metal-molecule couplings lead to new frictional damping terms and random forces, plus a correction to the potential of mean force. Numerical tests are performed and compared with a modified classical master equation; our results indicate that violating the Condon approximation can have a large effect on dynamics.

  11. Electronic friction near metal surfaces: A case where molecule-metal couplings depend on nuclear coordinates

    Science.gov (United States)

    Dou, Wenjie; Subotnik, Joseph E.

    2017-03-01

    We derive an explicit form for the electronic friction as felt by a molecule near a metal surface for the general case that molecule-metal couplings depend on nuclear coordinates. Our work generalizes a previous study by von Oppen et al. [Beilstein J. Nanotechnol. 3, 144 (2012)], where we now go beyond the Condon approximation (i.e., molecule-metal couplings are not held constant). Using a non-equilibrium Green's function formalism in the adiabatic limit, we show that fluctuating metal-molecule couplings lead to new frictional damping terms and random forces, plus a correction to the potential of mean force. Numerical tests are performed and compared with a modified classical master equation; our results indicate that violating the Condon approximation can have a large effect on dynamics.

  12. Frequency-dependent polarizabilities and shielding factors for confined one-electron systems

    Science.gov (United States)

    Montgomery, H. E., Jr.; Pupyshev, Vladimir I.

    2017-01-01

    Frequency-dependent dipole polarizabilities and shielding factors are calculated for the ground state of spherically symmetric screened one-electron systems embedded in an impenetrable spherical cavity. Coulomb, Yukawa, Hulthén and exponential cosine-screened Coulomb potentials are considered. In contrast to free systems, Dirichlet boundary conditions introduce a contribution to the shielding factor that results from an integral over the surface of the confining boundary. This is a fundamental difference between free and confined systems and results in unexpected modifications to some of the classic relations for free systems. The methods derived also give a simple expression for the polarizability of the confined harmonic oscillator as an example of extending the methods of this work to potentials beyond the four studied.

  13. Energy Dependence of Near-relativistic Electron Spectrum at Geostationary Orbit during the SEP Events of 2005

    Indian Academy of Sciences (India)

    A. Chandrasekhar Reddy; Jatin Rathod; Girija Rajaram; Radharani Alyana; D. S. Misra; C. G. Patil; M. Y. S. Prasad; A. G. Ananth

    2008-03-01

    In view of the renewed interest in the study of energetic particles in the outer radiation belt of the earth, we feel it will be helpful in looking for the energy dependence of the electron energy spectrum at geostationary orbit. This may give us some insight into how we can safeguard geostationary satellites from functional anomalies of the deep dielectric charging type, which are caused by charge accumulation and subsequent discharge of relativistic electrons. In this study we examine whether there is any energy dependence in relativistic electron enhancements at geosynchronous altitudes during solar energetic proton events of 2005.

  14. Power Dependence of the Electron Mobility Profile in a Hall Thruster

    Science.gov (United States)

    Jorns, Benjamin A.; Hofery, Richard H.; Mikellides, Ioannis G.

    2014-01-01

    The electron mobility profile is estimated in a 4.5 kW commercial Hall thruster as a function of discharge power. Internal measurements of plasma potential and electron temperature are made in the thruster channel with a high-speed translating probe. These measurements are presented for a range of throttling conditions from 150 - 400 V and 0.6 - 4.5 kW. The fluid-based solver, Hall2De, is used in conjunction with these internal plasma parameters to estimate the anomalous collision frequency profile at fixed voltage, 300 V, and three power levels. It is found that the anomalous collision frequency profile does not change significantly upstream of the location of the magnetic field peak but that the extent and magnitude of the anomalous collision frequency downstream of the magnetic peak does change with thruster power. These results are discussed in the context of developing phenomenological models for how the collision frequency profile depends on thruster operating conditions.

  15. Oxygen dependency of one-electron reactions generating ascorbate radicals and hydrogen peroxide from ascorbic acid.

    Science.gov (United States)

    Boatright, William L

    2016-04-01

    The effect of oxygen on the two separate one-electron reactions involved in the oxidation of ascorbic acid was investigated. The rate of ascorbate radical (Asc(-)) formation (and stability) was strongly dependent on the presence of oxygen. A product of ascorbic acid oxidation was measurable levels of hydrogen peroxide, as high as 32.5 μM from 100 μM ascorbic acid. Evidence for a feedback mechanism where hydrogen peroxide generated during the oxidation of ascorbic acid accelerates further oxidation of ascorbic acid is also presented. The second one-electron oxidation reaction of ascorbic acid leading to the disappearance of Asc(-) was also strongly inhibited in samples flushed with argon. In the range of 0.05-1.2 mM ascorbic acid, maximum levels of measurable hydrogen peroxide were achieved with an initial concentration of 0.2 mM ascorbic acid. Hydrogen peroxide generation was greatly diminished at ascorbic acid levels of 0.8 mM or above.

  16. Temperature dependence of gain and excess noise in InAs electron avalanche photodiodes.

    Science.gov (United States)

    Ker, Pin Jern; David, John P R; Tan, Chee Hing

    2012-12-31

    Measurement and analysis of the temperature dependence of avalanche gain and excess noise in InAs electron avalanche photodiodes (eAPDs) at 77 to 250 K are reported. The avalanche gain, initiated by pure electron injection, was found to reduce with decreasing temperature. However no significant change in the excess noise was measured as the temperature was varied. For avalanche gain > 3, the InAs APDs with 3.5 µm i-region show consistently low excess noise factors between 1.45 and 1.6 at temperatures of 77 to 250 K, confirming that the eAPD characteristics are exhibited in the measured range of electric field. As the dark current drops much more rapidly than the avalanche gain and the excess noise remains very low, our results confirmed that improved signal to noise ratio can be obtained in InAs eAPDs by reducing the operating temperature. The lack of hole impact ionization, as confirmed by the very low excess noise and the exponentially rising avalanche gain, suggests that hole impact ionization enhancement due to band "resonance" does not occur in InAs APDs at the reported temperatures.

  17. MendelWeb: An Electronic Science/Math/History Resource for the WWW.

    Science.gov (United States)

    Blumberg, Roger B.

    This paper describes a hypermedia resource, called MendelWeb that integrates elementary biology, discrete mathematics, and the history of science. MendelWeb is constructed from Gregor Menders 1865 paper, "Experiments in Plant Hybridization". An English translation of Mendel's paper, which is considered to mark the birth of classical and…

  18. QR Codes as Finding Aides: Linking Electronic and Print Library Resources

    Science.gov (United States)

    Kane, Danielle; Schneidewind, Jeff

    2011-01-01

    As part of a focused, methodical, and evaluative approach to emerging technologies, QR codes are one of many new technologies being used by the UC Irvine Libraries. QR codes provide simple connections between print and virtual resources. In summer 2010, a small task force began to investigate how QR codes could be used to provide information and…

  19. Electronic resources at the University of Sharjah medical library: an investigation of students' information-seeking behavior.

    Science.gov (United States)

    Boumarafi, Behdja

    2010-10-01

    Electronic information is becoming prevalent worldwide, and its use is growing exponentially as more and more users are recognizing the potential that it offers in terms of access and delivery. However, with the introduction of new tools for e-information searching and retrieval, users have to readjust their information-seeking behavior to cope with the corresponding changes. The University of Sharjah library is steadily increasing its investment in e-resources to offer ubiquitous access to the growing body of literature in areas that interest the community it serves. This study reports the findings of a survey conducted to investigate the information-seeking behavior of medical students at the medical library. Results showed evidence of use of e-resources, but they did not explicitly establish that some of the major problems mentioned by participants did hinder the information searches of the respondents. An extensive literature review sets the background for the study.

  20. Fertility and the environment in a natural resource dependent economy: Evidence from Petén, Guatemala

    Directory of Open Access Journals (Sweden)

    Curtis, Siân L.

    2004-07-01

    Full Text Available This paper examines potential relations between factors related to fertility and the access to and use of natural resources in Petén, Guatemala. The Petén forms the heart of the Selva Maya, the largest lowland humid forest in Mesoamerica. The rapid in-migration of subsistence maize farmers has converted much of the Petén's forests to agricultural fields. Population dynamics have been transformed in that virtually all farm families have arrived since the 1970s and that total fertility rates exceed the national rural mean. Continued migration, exceptionally high fertility, a youthful population, and a large consumer to producer ratio are hypothesized to be related to the dramatic land cover dynamics shaping the landscape of the Petén. An emerging body of literature suggests that environmental factors can affect fertility decision-making and behaviors, especially in natural resource dependent economies like that of the Petén. This paper examines these relationships using data from the 1998/99 Demographic Health Survey in Guatemala. Data on natural resource access and utilization were collected as part of an environment module, in addition to demographic and health information. This dataset, the first ever environmental module of the Demographic Health Survey, provides a unique opportunity to examine possible relationships between fertility and the environment in a tropical agricultural frontier.

  1. Fertility and the environment in a natural resource dependent economy: Evidence from Petén, Guatemala

    Directory of Open Access Journals (Sweden)

    Elizabeth G. Sutherland

    2004-01-01

    Full Text Available This paper examines potential relations between factors related to fertility and the access to and use of natural resources in Petén, Guatemala. The Petén forms the heart of the Selva Maya, the largest lowland humid forest in Mesoamerica. The rapid in-migration of subsistence maize farmers has converted much of the Petén´s forests to agricultural fields. Population dynamics have been transformed in that virtually all farm families have arrived since the 1970s and that total fertility rates exceed the national rural mean. Continued migration, exceptionally high fertility, a youthful population, and a large consumer to producer ratio are hypothesized to be related to the dramatic land cover dynamics shaping the landscape of the Petén. An emerging body of literature suggests that environmental factors can affect fertility decision-making and behaviors, especially in natural resource dependent economies like that of the Petén. This paper examines these relationships using data from the 1998/99 Demographic Health Survey in Guatemala. Data on natural resource access and utilization were collected as part of an environment module, in addition to demographic and health information. This dataset, the first ever environmental module of the Demographic Health Survey, provides a unique opportunity to examine possible relationships between fertility and the environment in a tropical agricultural frontier.

  2. On the Temperature Dependence of the Rate Constant of the Bimolecular Reaction of two Hydrated Electrons

    Directory of Open Access Journals (Sweden)

    S.L. Butarbutar

    2013-08-01

    Full Text Available It has been a longstanding issue in the radiation chemistry of water that, even though H2 is a molecular product, its “escape” yield g(H2 increases with increasing temperature. A main source of H2 is the bimolecular reaction of two hydrated electrons (eaq. The temperature dependence of the rate constant of this reaction (k1, measured under alkaline conditions, reveals that the rate constant drops abruptly above ~150°C. Recently, it has been suggested that this temperature dependence should be regarded as being independent of pH and used in high-temperature modeling of near-neutral water radiolysis. However, when this drop in the eaq self-reaction rate constant is included in low (isolated spurs and high (cylindrical tracks linear energy transfer (LET modeling calculations, g(H2 shows a marked downward discontinuity at ~150°C which is not observed experimentally. The consequences of the presence of this discontinuity in g(H2 for both low and high LET radiation are briefly discussed in this communication. It is concluded that the applicability of the sudden drop in k1 observed at ~150°C in alkaline water to near-neutral water is questionable and that further measurements of the rate constant in pure water are highly desirable.

  3. Intrinsic temperature-dependent evolutions in the electron-boson spectral density obtained from optical data

    Science.gov (United States)

    Hwang, Jungseek

    2016-03-01

    We investigate temperature smearing effects on the electron-boson spectral density function (I2χ(ω)) obtained from optical data using a maximum entropy inversion method. We start with two simple model input I2χ(ω), calculate the optical scattering rates at selected temperatures using the model input spectral density functions and a generalized Allen’s formula, then extract back I2χ(ω) at each temperature from the calculated optical scattering rate using the maximum entropy method (MEM) which has been used for analysis of optical data of high-temperature superconductors including cuprates, and finally compare the resulting I2χ(ω) with the input ones. From this approach we find that the inversion process can recover the input I2χ(ω) almost perfectly when the quality of fits is good enough and also temperature smearing (or thermal broadening) effects appear in the I2χ(ω) when the quality of fits is not good enough. We found that the coupling constant and the logarithmically averaged frequency are robust to the temperature smearing effects and/or the quality of fits. We use these robust properties of the two quantities as criterions to check whether experimental data have intrinsic temperature-dependent evolutions or not. We carefully apply the MEM to two material systems (one optimally doped and the other underdoped cuprates) and conclude that the I2χ(ω) extracted from the optical data contain intrinsic temperature-dependent evolutions.

  4. Measurement of the pressure dependence of air fluorescence emission induced by electrons

    CERN Document Server

    Ave, M; Buonomo, B; Busca, N; Cazon, L; Chemerisov, S D; Conde, M E; Crowell, R A; Di Carlo, P; Di Giulio, C; Doubrava, M; Esposito, A; Facal, P; Franchini, F J; Horandel, J; Hrabovsky, M; Iarlori, M; Kasprzyk, T E; Keilhauer, B; Klages, H; Kleifges, M; Kuhlmann, S; Mazzitelli, G; Nozka, L; Obermeier, A; Palatka, M; Petrera, S; Privitera, P; Rídky, J; Rizi, V; Rodríguez, G; Salamida, F; Schovanek, P; Spinka, H; Strazzeri, E; Ulrich, A; Yusof, Z M; Vacek, V; Valente, P; Verzi, V; Waldenmaier, T

    2007-01-01

    The fluorescence detection of ultra high energy (> 10^18 eV) cosmic rays requires a detailed knowledge of the fluorescence light emission from nitrogen molecules, which are excited by the cosmic ray shower particles along their path in the atmosphere. We have made a precise measurement of the fluorescence light spectrum excited by MeV electrons in dry air. We measured the relative intensities of 34 fluorescence bands in the wavelength range from 284 to 429 nm with a high resolution spectrograph. The pressure dependence of the fluorescence spectrum was also measured from a few hPa up to atmospheric pressure. Relative intensities and collisional quenching reference pressures for bands due to transitions from a common upper level were found in agreement with theoretical expectations. The presence of argon in air was found to have a negligible effect on the fluorescence yield. We estimated that the systematic uncertainty on the cosmic ray shower energy due to the pressure dependence of the fluorescence spectrum i...

  5. Time-dependent restricted-active-space self-consistent-field theory for laser-driven many-electron dynamics

    DEFF Research Database (Denmark)

    Miyagi, Haruhide; Madsen, Lars Bojer

    2013-01-01

    We present the time-dependent restricted-active-space self-consistent-field (TD-RASSCF) theory as a framework for the time-dependent many-electron problem. The theory generalizes the multiconfigurational time-dependent Hartree-Fock (MCTDHF) theory by incorporating the restricted-active-space scheme...... well known in time-independent quantum chemistry. Optimization of the orbitals as well as the expansion coefficients at each time step makes it possible to construct the wave function accurately while using only a relatively small number of electronic configurations. In numerical calculations of high...

  6. State-dependent resource harvesting with lagged information about system states

    Science.gov (United States)

    Johnson, Fred A.; Fackler, Paul L.; Boomer, G Scott; Zimmerman, Guthrie; Williams, Byron K.; Nichols, James; Dorazio, Robert

    2016-01-01

    Markov decision processes (MDPs), which involve a temporal sequence of actions conditioned on the state of the managed system, are increasingly being applied in natural resource management. This study focuses on the modification of a traditional MDP to account for those cases in which an action must be chosen after a significant time lag in observing system state, but just prior to a new observation. In order to calculate an optimal decision policy under these conditions, possible actions must be conditioned on the previous observed system state and action taken. We show how to solve these problems when the state transition structure is known and when it is uncertain. Our focus is on the latter case, and we show how actions must be conditioned not only on the previous system state and action, but on the probabilities associated with alternative models of system dynamics. To demonstrate this framework, we calculated and simulated optimal, adaptive policies for MDPs with lagged states for the problem of deciding annual harvest regulations for mallards (Anas platyrhynchos) in the United States. In this particular example, changes in harvest policy induced by the use of lagged information about system state were sufficient to maintain expected management performance (e.g. population size, harvest) even in the face of an uncertain system state at the time of a decision.

  7. State-Dependent Resource Harvesting with Lagged Information about System States.

    Directory of Open Access Journals (Sweden)

    Fred A Johnson

    Full Text Available Markov decision processes (MDPs, which involve a temporal sequence of actions conditioned on the state of the managed system, are increasingly being applied in natural resource management. This study focuses on the modification of a traditional MDP to account for those cases in which an action must be chosen after a significant time lag in observing system state, but just prior to a new observation. In order to calculate an optimal decision policy under these conditions, possible actions must be conditioned on the previous observed system state and action taken. We show how to solve these problems when the state transition structure is known and when it is uncertain. Our focus is on the latter case, and we show how actions must be conditioned not only on the previous system state and action, but on the probabilities associated with alternative models of system dynamics. To demonstrate this framework, we calculated and simulated optimal, adaptive policies for MDPs with lagged states for the problem of deciding annual harvest regulations for mallards (Anas platyrhynchos in the United States. In this particular example, changes in harvest policy induced by the use of lagged information about system state were sufficient to maintain expected management performance (e.g. population size, harvest even in the face of an uncertain system state at the time of a decision.

  8. Seasonal household income dependency on forest and environmental resources in rural Mozambique

    DEFF Research Database (Denmark)

    Walelign, Solomon Zena; Nielsen, Øystein Juul

    2013-01-01

    Households in agrarian societies engage in variety of income generating activities. These activities are often seasonal and the associated income generated is volatile. Based on an income survey from 2006 in rural Mozambique, this study assesses the seasonal contribution of different income sourc...... practitioners shall give attention to the role of farm and non-farm income opportunities to help households cope with seasonal income short falls. Recognizing the importance of forest and environmental resources to meet subsistence needs is also important....... to total household income. The results indicate that forest and environmental income was the second largest contributor to households’ total income next to crop income, the relative share being 23.7 percent of total income. With regard to seasonal income contributions, wage income and other income sources...... (gold in particular) are important in filling the gap when income from crop production is low, although they do not completely offset the fall. All income sources, including forest and environmental income, were fluctuating significantly between seasons, except for livestock and business income...

  9. 图书馆电子信息资源利用效果评价研究%Study on Utilization Effect Evaluation of Library Electronic Information Resources

    Institute of Scientific and Technical Information of China (English)

    晋晓强; 贺培风; 何忠印

    2012-01-01

    This paper discusses utilization effect of electronic information resources combining with the characteristics of electronic information resources, makes evaluation system of library electronic information resource utilization effect from three aspects : the library, the users and the data providers, hoping for providing valuable reference for the efficient use of library electronic resources.%本文结合电子信息资源的特性对电子信息资源的利用进行初步探讨,从图书馆、用户和数据服务商三个角度构建图书馆电子信息资源利用效果的评价体系,希望能为图书馆电子信息资源的高效利用提供参考。

  10. Dependence of Electron Peak Current on Hollow Cathode Dimensions and Seed Electron Energy in a Pseudospark Discharge (Postprint)

    Science.gov (United States)

    2008-01-18

    backlighted- thyratron BLT.8,18,19 Experiments have shown that the number13 of seed electrons needed to initiate a dis- charge is of the order of...superemissive state. The physical model for the latteraElectronic mail: socetiner@yahoo.com. JOURNAL OF APPLIED PHYSICS 103, 023304 2008 0021-8979/2008/1032...sustained sputtering,23 and is not being modeled here; our attention is focused on the triggering and avalanche processes, which can be identi- fied

  11. Geology and market-dependent significance of rare earth element resources

    Science.gov (United States)

    Simandl, G. J.

    2014-12-01

    China started to produce rare earth elements (REEs) in the 1980s, and since the mid-1990s, it has become the dominant producer. Rare earth element export quotas first introduced by the Chinese government in the early 2000s were severely reduced in 2010 and 2011. This led to strong government-created disparity between prices within China and the rest of the world. Industrialized countries identified several REEs as strategic metals. Because of rapid price increases of REE outside of China, we have witnessed a world-scale REE exploration rush. The REE resources are concentrated in carbonatite-related deposits, peralkaline igneous rocks, pegmatites, monazite ± apatite veins, ion adsorption clays, placers, and some deep ocean sediments. REE could also be derived as a by-product of phosphate fertilizer production, U processing, mining of Ti-Zr-bearing placers, and exploitation of Olympic Dam subtype iron oxide copper gold (IOCG) deposits. Currently, REEs are produced mostly from carbonatite-related deposits, but ion adsorption clay deposits are an important source of heavy REE (HREE). Small quantities of REE are derived from placer deposits and one peralkaline intrusion-related deposit. The ideal REE development targets would be located in a politically stable jurisdiction with a pro-mining disposition such as Canada and Australia. REE grade, HREE/light REE (LREE) ratio of the mineralization, tonnage, mineralogy, and permissive metallurgy are some of the key technical factors that could be used to screen potential development projects. As REEs are considered strategic metals from economic, national security, and environmental points of view, technical and economic parameters alone are unlikely to be used in REE project development decision-making. Recycling of REE is in its infancy and unless legislated, in the short term, it is not expected to contribute significantly to the supply of REE.

  12. Negative density dependence is stronger in resource-rich environments and diversifies communities when stronger for common but not rare species.

    Science.gov (United States)

    LaManna, Joseph A; Walton, Maranda L; Turner, Benjamin L; Myers, Jonathan A

    2016-06-01

    Conspecific negative density dependence is thought to maintain diversity by limiting abundances of common species. Yet the extent to which this mechanism can explain patterns of species diversity across environmental gradients is largely unknown. We examined density-dependent recruitment of seedlings and saplings and changes in local species diversity across a soil-resource gradient for 38 woody-plant species in a temperate forest. At both life stages, the strength of negative density dependence increased with resource availability, becoming relatively stronger for rare species during seedling recruitment, but stronger for common species during sapling recruitment. Moreover, negative density dependence appeared to reduce diversity when stronger for rare than common species, but increase diversity when stronger for common species. Our results suggest that negative density dependence is stronger in resource-rich environments and can either decrease or maintain diversity depending on its relative strength among common and rare species.

  13. Choice of data extraction tools for systematic reviews depends on resources and review complexity.

    Science.gov (United States)

    Elamin, Mohamed B; Flynn, David N; Bassler, Dirk; Briel, Matthias; Alonso-Coello, Pablo; Karanicolas, Paul Jack; Guyatt, Gordon H; Malaga, German; Furukawa, Toshiaki A; Kunz, Regina; Schünemann, Holger; Murad, Mohammad Hassan; Barbui, Corrado; Cipriani, Andrea; Montori, Victor M

    2009-05-01

    To assist investigators planning, coordinating, and conducting systematic reviews in the selection of data-extraction tools for conducting systematic reviews. We constructed an initial table listing available data-collection tools and reflecting our experience with these tools and their performance. An international group of experts iteratively reviewed the table and reflected on the performance of the tools until no new insights and consensus resulted. Several tools are available to manage data in systematic reviews, including paper and pencil, spreadsheets, web-based surveys, electronic databases, and web-based specialized software. Each tool offers benefits and drawbacks: specialized web-based software is well suited in most ways, but is associated with higher setup costs. Other approaches vary in their setup costs and difficulty, training requirements, portability and accessibility, versatility, progress tracking, and the ability to manage, present, store, and retrieve data. Available funding, number and location of reviewers, data needs, and the complexity of the project should govern the selection of a data-extraction tool when conducting systematic reviews.

  14. An Exploratory study on the use of LibAnswers to Resolve, Track and Monitor Electronic Resources Issues: The KAUST Library experience

    KAUST Repository

    Ramli, Rindra M.

    2017-05-03

    An Exploratory study on KAUST library use of LibAnswers in resolving electronic resources questions received in LibAnswers. It describes the findings of the questions received in LibAnswers. The author made suggestions based on the findings to improve the reference services in responding to e-resources questions.

  15. Eavesdropping on Electronic Guidebooks: Observing Learning Resources in Shared Listening Environments.

    Science.gov (United States)

    Woodruff, Allison; Aoki, Paul M.; Grinter, Rebecca E.; Hurst, Amy; Szymanski, Margaret H.; Thornton, James D.

    This paper describes an electronic guidebook, "Sotto Voce," that enables visitors to share audio information by eavesdropping on each others guidebook activity. The first section discusses the design and implementation of the guidebook device, key aspects of its user interface, the design goals for the audio environment, the eavesdropping…

  16. Electronic Resources in a Next-Generation Catalog: The Case of WorldCat Local

    Science.gov (United States)

    Shadle, Steve

    2009-01-01

    In April 2007, the University of Washington Libraries debuted WorldCat Local (WCL), a localized version of the WorldCat database that interoperates with a library's integrated library system and fulfillment services to provide a single-search interface for a library's physical and electronic content. This brief will describe how WCL incorporates a…

  17. Equalizing Access to Electronic Networked Resources: A Model for Rural Libraries in the United States.

    Science.gov (United States)

    Senkevitch, Judith J.; Wolfram, Dietmar

    1994-01-01

    Provides an overview of the current state of networking technology in rural libraries and describes a model for educating rural librarians in accessing electronic networks. Topics discussed include information needs in rural libraries; telecommunications technology access in rural areas; and examples of services to enhance information access.…

  18. Width dependent collisionless electron dynamics in the static fields of the shock ramp, 2, Phase space portrait

    Directory of Open Access Journals (Sweden)

    M. Gedalin

    1997-01-01

    Full Text Available We study numerically in detail the behaviour of electrons in the strongly inhomogeneous static magnetic and electric fields, which are typical for thin quasiperpendicular collisionless shocks. We pay particular attention to the dependence of the final electron velocities on their initial velocities, for different shock widths. Electrons are completely magnetized when the shock is wide, but become demagnetized, and the energies that they acquire rapidly increase with the steepening of the field structure. One of the clear manifestations of the electron demagnetization is the loss of even approximate one-to-one correspondence of the downstream perpendicular velocity to the upstream perpendicular velocity. Electron reflection occurs despite the large cross-shock potential which accelerates electrons along the magnetic field (the regime of complete magnetization or across the shock (strong demagnetization. The reflected ion fraction is sensitive to the potential, magnetic field jump, and ramp width.

  19. Time-dependent quantum many-body systems. Linear response, electronic transport, and reduced density matrices

    Energy Technology Data Exchange (ETDEWEB)

    Appel, H.

    2007-05-15

    In part I of this work we present a double-pole approximation (DPA) to the response equations of time-dependent density functional theory (TDDFT). The double-pole approximation provides an exact description of systems with two strongly coupled excitations which are isolated from the rest of the spectrum. In contrast to the traditional single-pole approximation of TDDFT the DPA also yields corrections to the Kohn-Sham oscillator strengths. We also demonstrate how to invert the double-pole solution which allows us to predict matrix elements of the exchange-correlation kernel f{sub xc} from experimental input. We attempt some first steps towards a time-dependent generalization of reduced density matrix functional theory (RDMFT). In part II we derive equations of motion for natural orbitals and occupation numbers. Using the equation of motion for the occupation numbers we show that an adiabatic extension of presently known ground-state functionals of static RDMFT always leads to occupation numbers which are constant in time. From the stationary conditions of the equations of motion for the N-body correlations (correlated parts of the N-body matrices) we derive a new class of ground-state functionals which can be used in static RDMFT. Applications are presented for a one-dimensional model system where the time-dependent many-body Schroedinger equation can be propagated numerically. We use optimal control theory to find optimized laser pulses for transitions in a model for atomic Helium. From the numerically exact correlated wavefunction we extract the exact time evolution of natural orbitals and occupation numbers for (i) laser-driven Helium and (ii) electron-ion scattering. Part III of this work considers time-dependent quantum transport within TDDFT. We present an algorithm for the calculation of extended eigenstates of single-particle Hamiltonians which is especially tailored to a finite-difference discretization of the Schroedinger equation. We consider the

  20. Spin Dependent Transport in Si/SiGe Few-Electron Quantum Dots

    Science.gov (United States)

    Simmons, Christie

    2008-03-01

    Si/SiGe quantum dots are of interest for quantum information processing due in large part to the existence of spin zero isotopes of both Si and Ge. We present the results of transport measurements and integrated charge sensing in silicon double and single quantum dots.[1,2] We observe two effects arising from spin dependent transport in a double quantum dot. First, and as expected, for one direction of current flow we observe spin blockade -- the canonical example of spin-to-charge conversion in transport. In addition, when current flow is reversed, we observe a second effect: strong tails of current extend from the sharp triangular regions in which current conventionally is observed. The presence of these tails is explained by a combination of long spin relaxation times and preferential loading of an excited spin state. We also present charge-sensing measurements of single and double quantum dots using an integrated quantum point contact. The charge sensor signal from single electron tunneling is well correlated with conventional transport through the system. When the tunnel barriers are large and transport through the dot is not measurable, charge sensing remains a viable means to track charge transitions and is used to confirm individual-electron occupation in a single quantum dot. Work performed in collaboration with Nakul Shaji, Madhu Thalakulam, Levente J. Klein, H. Luo, Hua Qin, R. H. Blick, D. E. Savage, M. G. Lagally, A. J. Rimberg, R. Joynt, M. Friesen, S. N. Coppersmith, M. A. Eriksson. Work supported by ARO, LPS, NSF and DOE. (1) Shaji, N. et al. e-print arXiv:0708.0794 (2) Simmons, C. B. et al. Appl. Phys. Lett. 91, 213103 (2007).

  1. Preference and Use of Electronic Information and Resources by Blind/Visually Impaired in NCR Libraries in India

    Directory of Open Access Journals (Sweden)

    Shailendra Kumar

    2013-06-01

    Full Text Available This paper aims to determine the preference and use of electronic information and resources by blind/visually impaired users in the leading National Capital Region (NCR libraries of India. Survey methodology has been used as the basic research tool for data collection with the help of questionnaires. The 125 in total users surveyed in all the five libraries were selected randomly on the basis of willingness of the users with experience of working in digital environments to participate in the survey. The survey results were tabulated and analyzed with descriptive statistics methods using Excel software and 'Stata version 11'. The findings reveal that ICT have a positive impact in the lives of people with disabilities as it helps them to work independently and increases the level of confidence among them. The Internet is the most preferred medium of access to information among the majority of blind/visually impaired users. The 'Complexity of content available on the net' is found as the major challenge faced during Internet use by blind users of NCR libraries. 'Audio books on CDs/DVDs and DAISY books' are the most preferred electronic resources among the majority of blind/visually impaired users. This study will help the library professionals and organizations/institutions serving people with disabilities to develop effective library services for blind/visually impaired users in the digital environment on the basis of findings on information usage behavior in the study.

  2. Insight into dopamine-dependent planning deficits in Parkinson's disease: A sharing of cognitive & sensory resources.

    Science.gov (United States)

    Pieruccini-Faria, F; Jones, J A; Almeida, Q J

    2016-03-24

    Cognitive and sensorimotor processes are both needed for successful planning of footsteps during complex gait situations, but the interaction between these factors during motor planning, as well as their response to dopaminergic treatment is poorly understood in Parkinson's disease (PD). In the current study, we evaluated walking and gaze behaviors of individuals with PD while planning an approach toward an obstacle to be stepped over. The obstacle clearance task was completed both ON and OFF dopaminergic medication by individuals with Parkinson's disease (n=20) and compared to healthy age-matched control participants (n=19), as well as with and without an auditory digit monitoring dual task. In this novel protocol of synchronized gaze and gait data collection, each trial was split into an early and late phase prior to the obstacle, providing a unique opportunity to examine dopamine-dependent planning deficits in PD. Interestingly, only patients in the OFF medication state showed greater deceleration in the late phase (i.e., just before the obstacle) (F(1,37)=45.42, pphase) with the additional demands of a dual task (F(2,74)=3.49, p=0.035). Only gait deceleration between approaching phases improved with dopaminergic treatment (F(1,18)=59.20; pplanned for the obstacle more so in the early phase (pphase or condition suggesting that the deceleration and increased variability when approaching an obstacle is the result of a greater demand for online sensory feedback that cannot be compensated for with visual strategies. We conclude that dopamine influences planning by limiting sensorimotor processing capacity, especially in the presence of increased cognitive demand in PD.

  3. Collaboration in electronic resource provision in university libraries: SHEDL, a Scottish case study

    OpenAIRE

    Kidd, T

    2009-01-01

    This case study examines the growth of collaboration among Scottish higher education institutions. Following a summary of the work of the Scottish Confederation of University and Research Libraries (SCURL), more detailed information is provided on collaboration in the fields of acquisition, licensing, selection, and purchasing. Some of the UK background is outlined, relating to NESLi2 in particular, in order to illuminate the options within Scotland. The origins of negotiations on electronic ...

  4. Internet and electronic resources for inflammatory bowel disease: a primer for providers and patients.

    Science.gov (United States)

    Fortinsky, Kyle J; Fournier, Marc R; Benchimol, Eric I

    2012-06-01

    Patients with inflammatory bowel disease (IBD) are increasingly turning to the Internet to research their condition and engage in discourse on their experiences. This has resulted in new dynamics in the relationship between providers and their patients, with misinformation and advertising potentially presenting barriers to the cooperative patient-provider partnership. This article addresses important issues of online IBD-related health information and social media activity, such as quality, reliability, objectivity, and privacy. We reviewed the medical literature on the quality of online information provided to IBD patients, and summarized the most commonly accessed Websites related to IBD. We also assessed the activity on popular social media sites (such as Facebook, Twitter, and YouTube), and evaluated currently available applications for use by IBD patients and providers on mobile phones and tablets. Through our review of the literature and currently available resources, we developed a list of recommended online resources to strengthen patient participation in their care by providing reliable, comprehensive educational material.

  5. Examination of the temperature dependent electronic behavior of GeTe for switching applications

    Science.gov (United States)

    Champlain, James G.; Ruppalt, Laura B.; Guyette, Andrew C.; El-Hinnawy, Nabil; Borodulin, Pavel; Jones, Evan; Young, Robert M.; Nichols, Doyle

    2016-06-01

    The DC and RF electronic behaviors of GeTe-based phase change material switches as a function of temperature, from 25 K to 375 K, have been examined. In its polycrystalline (ON) state, GeTe behaved as a degenerate p-type semiconductor, exhibiting metal-like temperature dependence in the DC regime. This was consistent with the polycrystalline (ON) state RF performance of the switch, which exhibited low resistance S-parameter characteristics. In its amorphous (OFF) state, the GeTe presented significantly greater DC resistance that varied considerably with bias and temperature. At low biases (presence of two regions of localized traps within the bandgap of the amorphous GeTe, located at approximately 0.26-0.27 eV and 0.56-0.57 eV from the valence band. Unlike the polycrystalline state, the high resistance DC behavior of amorphous GeTe does not translate to the RF switch performance; instead, a parasitic capacitance associated with the RF switch geometry dominates OFF state RF transmission.

  6. Substrate-dependent electronic structure and film formation of MAPbI3 perovskites

    Science.gov (United States)

    Olthof, Selina; Meerholz, Klaus

    2017-01-01

    We present investigations on the interface formation between the hybrid perovskite MAPbI3 and various substrates, covering a wide range of work functions. The perovskite films are incrementally evaporated in situ while the electronic structure is evaluated using photoelectron spectroscopy. Our results show that there is an induction period in the growth of the perovskite during which volatile compounds are formed, catalyzed by the substrate. The duration of the induction period depends strongly on the nature of the substrate material, and it can take up to 20–30 nm of formal precursor deposition before the surface is passivated and the perovskite film starts forming. The stoichiometry of the 2–3 nm thin passivation layer deviates from the expected perovskite stoichiometry, being rich in decomposition products of the organic cation. During the regular growth of the perovskite, our measurements show a deviation from the commonly assumed flat band condition, i.e., dipole formation and band bending dominate the interface. Overall, the nature of the substrate not only changes the energetic alignment of the perovskite, it can introduce gap states and influence the film formation and morphology. The possible impact on device performance is discussed.

  7. Thickness dependent electronic structure and morphology of rubrene thin films on metal, semiconductor, and dielectric substrates

    Science.gov (United States)

    Sinha, Sumona; Mukherjee, M.

    2013-08-01

    The evolution of the electronic structure and morphology of rubrene thin films on noble-metal, semiconductor and dielectric substrates have been investigated as a function of thickness of deposited films by using photoelectron spectroscopy and atomic force microscopy. The clean polycrystalline Au and Ag were used as noble-metals, whereas, H passivated and SiO2 coated Si (100) were used as semiconductors and dielectric substrates. Discussion and comparison on interface dipole, energy level alignment, and surface morphology for the four cases are presented. The formation of dipole at metallic interfaces is found to occur due to push back effect. S parameter obtained from the variation of barrier height with the change of work function of the contacting metal indicates moderately weak interaction between rubrene and the metal substrates. The thickness dependent energy level alignment of the physisorbed rubrene films on different substrates is explained by a dielectric model in terms of electrostatic screening of photo-holes or photoemission final state relaxation energy. Films on all the substrates are found to grow following Stranski-Krastnov type growth mode and are more ordered at higher coverage.

  8. Substrate-dependent electronic structure and film formation of MAPbI3 perovskites

    Science.gov (United States)

    Olthof, Selina; Meerholz, Klaus

    2017-01-01

    We present investigations on the interface formation between the hybrid perovskite MAPbI3 and various substrates, covering a wide range of work functions. The perovskite films are incrementally evaporated in situ while the electronic structure is evaluated using photoelectron spectroscopy. Our results show that there is an induction period in the growth of the perovskite during which volatile compounds are formed, catalyzed by the substrate. The duration of the induction period depends strongly on the nature of the substrate material, and it can take up to 20–30 nm of formal precursor deposition before the surface is passivated and the perovskite film starts forming. The stoichiometry of the 2–3 nm thin passivation layer deviates from the expected perovskite stoichiometry, being rich in decomposition products of the organic cation. During the regular growth of the perovskite, our measurements show a deviation from the commonly assumed flat band condition, i.e., dipole formation and band bending dominate the interface. Overall, the nature of the substrate not only changes the energetic alignment of the perovskite, it can introduce gap states and influence the film formation and morphology. The possible impact on device performance is discussed. PMID:28084313

  9. Three-dimensional, time-dependent simulation of a regenerative amplifier free-electron laser

    Science.gov (United States)

    Freund, H. P.; Nguyen, D. C.; Sprangle, P. A.; van der Slot, P. J. M.

    2013-01-01

    Free-electron lasers have been designed to operate over virtually the entire electromagnetic spectrum from microwaves through x rays and in a variety of configurations including amplifiers and oscillators. Oscillators typically operate in the low-gain regime where the full spectral width is (Δω/ω)≈1/Nw and the efficiency η≈1/(2.4Nw). Further, since a low-gain oscillator saturates when the gain compensates for losses in the resonator G=L/(1-L), this implies that the losses must be relatively small and the cavity Q must be relatively large. This imposes problems for high power oscillators because the high Q can result in mirror loading above the damage threshold, and in short-wavelength oscillators because sufficiently low loss resonators may not be possible at x-ray wavelengths. In contrast, regenerative amplifier FELs (RAFELs) employ high-gain wigglers that reach exponential gain and can operate with high loss (i.e., low Q) resonators. As such, RAFELs may be able to function at either high power levels or short wavelengths. In this paper, we describe a three-dimensional, time-dependent simulation of a RAFEL operating at a 2.2-μm wavelength, and show that its behavior differs substantially from that of low-gain oscillators, and is closer to that of self-amplified spontaneous radiation FELs in regard to spectral linewidth and extraction efficiency.

  10. Size dependent electronic and magnetic properties of ultra thin graphene nanoribbons

    Science.gov (United States)

    Kumar, Sandeep; Meenakshi; Sharma, Hitesh

    2016-09-01

    We present the results of systematic investigation into size dependent electronic and magnetic properties of ultra thin graphene nanoribbons (GNRs) of finite and infinite length using spin polarized density functional calculation. The rectangular GNRs with width up to 1.40 nm with finite (2.50 nm) and infinite length were investigated. The ultra thin GNRs are found less stable in comparison to larger GNRs with binding energy increasing with increase in the size. All GNRs have shown finite HOMO-LUMO gap which decreases oscillatory as a function of width. HOMO-LUMO gap in the Finite length armchair GNRs is in range of 0.01-0.36 eV, where as in infinite length GNR the energy gap is in the range of 0.30-1.41 eV. Zigzag GNRs have shown very small HOMO-LUMO gap in the range 50-80 meV. The zigzag GNR have shown opening of energy band gap. However, for N = 8 and 10 layers, GNRs with zigzag edges are found to be ferromagnetic. The edge C atom on zigzag edges contribute magnetic moment of 0.94 {μ }B per C atom with total magnetic moment remaining constant with increase in the width. The energy difference between ferromagnetic and anti-ferromagnetic state decreases sharply with the increase in GNR width suggesting iso-energetic behavior in larger GNRs. The results are consistent with the reported experimental results.

  11. Towards a Mechanistic Understanding of Anaerobic Nitrate Dependent Iron Oxidation: Balancing Electron Uptake and Detoxification

    Directory of Open Access Journals (Sweden)

    Hans Karl Carlson

    2012-02-01

    Full Text Available The anaerobic oxidation of Fe(II by subsurface microorganisms is an important part of biogeochemical cycling in the environment, but the biochemical mechanisms used to couple iron oxidation to nitrate respiration are not well understood. Based on our own work and the evidence available in the literature, we propose a mechanistic model for anaerobic nitrate dependent iron oxidation. We suggest that anaerobic iron oxidizing microorganisms likely exist along a continuum including: 1 bacteria that inadvertently oxidize Fe(II by abiotic or biotic reactions with enzymes or chemical intermediates in their metabolic pathways (e.g. denitrification and suffer from toxicity or energetic penalty, 2 Fe(II tolerant bacteria that gain little or no growth benefit from iron oxidation but can manage the toxic reactions, and 3 bacteria that efficiently accept electrons from Fe(II to gain a growth advantage while preventing or mitigating the toxic reactions. Predictions of the proposed model are highlighted and experimental approaches are discussed.

  12. Seebeck effect in dilute two-dimensional electron systems: temperature dependencies of diffusion and phonon-drag thermoelectric powers

    OpenAIRE

    Liu, S Y; Lei, X. L.; Horing, Norman J. M.

    2011-01-01

    Considering screeening of electron scattering interactions in terms of the finite-temperature STLS theory and solving the linearized Boltzmann equation (with no appeal to a relaxation time approximation), we present a theoretical analysis of the low-temperature Seebeck effect in two-dimensional semiconductors with dilute electron densities. We find that the temperature ($T$) dependencies of the diffusion and phonon-drag thermoelectric powers ($S_d$ and $S_g$) can no longer be described by the...

  13. Temperature-dependent determination of electron heat capacity and electron-phonon coupling factor for Fe0.72Cr0.18Ni0.1

    Science.gov (United States)

    Winter, Jan; Sotrop, Jürgen; Borek, Stephan; Huber, Heinz P.; Minár, Jan

    2016-04-01

    A theoretical approach using ab initio calculations was applied to study the interaction of an ultrashort laser pulse with the metal alloy Fe0.72Cr0.18Ni0.1 (AISI 304). The electronic structure was simulated by taking into account the chemical and magnetic disorder of the alloy by the coherent potential approximation implemented in a fully relativistic Korringa-Kohn-Rostoker formalism in the framework of spin density functional theory. A self-consistent calculation of the electronic structure using the Matsubara technique in the paramagnetic state of Fe0.72Cr0.18Ni0.1 for finite temperatures was applied. Utilizing these predictions we determined the electron heat capacity and the electron-phonon coupling factor of Fe0.72Cr0.18Ni0.1 in dependence on the electron temperature for two-temperature model applications. Compared with pure Fe a maximum deviation of 5% for the electron heat capacity and 25% for the electron-phonon coupling factor was found.

  14. Subject competency of teachers and level of dependence on resource packs to teach levers, gears and pulleys

    Science.gov (United States)

    Jarvis, Tina; Cavendish, Sue

    1994-12-01

    This pilot study set out to ascertain whether the level of dependence on resource material is related to teaching experience, existing understanding in mechanics, and perceived self confidence in science and technology. Details of teaching experience and qualifications were obtained from 11 experienced teachers and 10 initial teacher trainees, and understanding of mechanics was assessed by a written test. Each teacher worked through one commercially produced inservice pack about levers, pulleys or gears, and then prepared a 30 minute session for 4 ten year old children. Videos of the sessions were analysed with respect to the extent to which the pack was the sole focus; the amount of integration with other teaching aids and approaches; and the extent individual children's needs were satisfied. Although science qualifications influenced teacher confidence, they were not accurate predictors of relevant knowledge and teaching competence. As the majority of teachers followed pack instructions closely, the children's needs were not always well matched.

  15. Preference for Print or Electronic Book Depends on User’s Purpose for Consulting

    Directory of Open Access Journals (Sweden)

    Laura Newton Miller

    2014-09-01

    book, 16.7% the e-book, and 58.2% chose both formats. When asked about downloading e-books, 51.1% of respondents would use an e-book only if they could download it to a hand-held device. A majority of the respondents, 81.7%, felt that the library should provide e-readers for checkout if the library purchased e-books instead of print books. When asked which types of books they preferred to read in electronic format in an open-ended question, 22% preferred textbooks, 21% leisure reading, 18% research books, 15% other types, 6% journals, 5% reference books, and 3% anything. Regarding which types of books were preferred in print format, 42% preferred leisure reading, 21% other, 14% all, 11% textbooks, 6% research books, 2% no e-books, 2% journals and 2% reference books. Conclusion – Preference for book format (electronic or print depends on the users’ purpose for reading the text. This will likely change over time, as users gain more familiarity and experience with e-books, and better support is provided from the library

  16. Laser-induced electron emission from a tungsten nanotip: identifying above threshold photoemission using energy-resolved laser power dependencies

    CERN Document Server

    Bionta, M R; Champeaux, J P; Faure, S; Masseboeuf, A; Moretto-Capelle, P; Chatel, B

    2013-01-01

    We present an experiment studying the interaction of a strongly focused 25 fs laser pulse with a tungsten nanotip, investigating the different regimes of laser-induced electron emission. We study the dependence of the electron yield with respect to the static electric field applied to the tip. Photoelectron spectra are recorded using a retarding field spectrometer and peaks separated by the photon energy are observed with a 45 % contrast. They are a clear signature of above threshold photoemission (ATP), and are confirmed by extensive spectrally resolved studies of the laser power dependence. Understanding these mechanisms opens the route to control experiment in the strong-field regime on nanoscale objects.

  17. Radial profile and q dependence of electron heat diffusion measured with ech modulation in RTP

    NARCIS (Netherlands)

    Mantica, P.; Peters, M.; De Luca, F.; DeLauri, A.; Gorini, G.; Hogeweij, G. M. D.; Jacchia, A.; Cardozo, N. J. L.

    1996-01-01

    Perturbative measurements of the electron thermal diffusivity (chi(pert)) in the RTP tokamak are presented. Electron temperature perturbations are induced by on- and off-axis modulated electron cyclotron heating (MECH) and the sawtooth instability. The radial profile of chi(pert) is deduced from the

  18. Projectile- and charge-state-dependent electron yields from ion penetration of solids as a probe of preequilibrium stopping power

    DEFF Research Database (Denmark)

    Rothard, H.; Schou, Jørgen; Groeneveld, K.-O.

    1992-01-01

    Kinetic electron-emission yields gamma from swift ion penetration of solids are proportional to the (electronic) stopping power gamma approximately Beta-S*, if the preequilibrium evolution of the charge and excitation states of the positively charged ions is taken into account. We show...... that the concept of the preequilibrium near-surface stopping S* can be applied successfully to describe the dependence of the ion-induced electron yields on the projectile atomic number Z(P) and on the charge states q(i) of the incoming ions. We discuss the implementation of this concept into Schou's transport...

  19. Facet-dependent trapping and dynamics of excess electrons at anatase TiO2 surfaces and aqueous interfaces

    Science.gov (United States)

    Selcuk, Sencer; Selloni, Annabella

    2016-10-01

    Excess electrons from intrinsic defects, dopants and photoexcitation play a key role in many of the properties of TiO2. Understanding their behaviour is important for improving the performance of TiO2 in energy-related applications. We focus on anatase, the TiO2 polymorph most relevant in photocatalysis and solar energy conversion. Using first-principles simulations, we investigate the states and dynamics of excess electrons from different donors near the most common anatase (101) and (001) surfaces and aqueous interfaces. We find that the behaviour of excess electrons depends strongly on the exposed anatase surface, the environment and the character of the electron donor. Whereas no electron trapping is observed on the (101) surface in vacuo, an excess electron at the aqueous (101) interface can trigger water dissociation and become trapped into a stable surface Ti3+-bridging OH complex. By contrast, electrons avoid the (001) surface, indicating that oxidation reactions are favoured on this surface. Our results provide a bridge between surface science experiments and observations of crystal-face-dependent photocatalysis on anatase, and support the idea that optimization of the ratio between {101} and {001} facets could provide a way to enhance the photocatalytic activity of this material.

  20. Development of a Method for Determining the Dependence of the Electron Mobility on the Longitudinal-Electric Field in MOSFETs

    OpenAIRE

    Roldán, J. B.; F. Gámiz; J. A. López-Villanueva

    1998-01-01

    A new experimental method for determining the dependence of the electron mobility on the longitudinal-electric field has been developed. The development, validation and explanation of this new method has been carefully carried out. We have applied this procedure to standard submicron MOSFETs and after having obtained the mobility dependence on both the transverse- and longitudinal-electric fields we reproduced the experimental output curves. The saturation velocity has also bee...

  1. Granulometric composition study of mineral resources using opto-electronic devices and Elsieve software system

    Directory of Open Access Journals (Sweden)

    Kaminski Stanislaw

    2016-01-01

    Full Text Available The use of mechanical sieves has a great impact on measurement results because occurrence of anisometric particles causes undercounting the average size. Such errors can be avoided by using opto-electronic measuring devices that enable measurement of particles from 10 μm up to a few dozen millimetres in size. The results of measurement of each particle size fraction are summed up proportionally to its weight with the use of Elsieve software system and for every type of material particle-size distribution can be obtained. The software allows further statistical interpretation of the results. Beam of infrared radiation identifies size of particles and counts them precisely. Every particle is represented by an electronic impulse proportional to its size. Measurement of particles in aqueous suspension that replaces the hydrometer method can be carried out by using the IPS L analyser (range from 0.2 to 600 μm. The IPS UA analyser (range from 0.5 to 2000 μm is designed for measurement in the air. An ultrasonic adapter enables performing measurements of moist and aggregated particles from 0.5 to 1000 μm. The construction and software system allow to determine second dimension of the particle, its shape coefficient and specific surface area. The AWK 3D analyser (range from 0.2 to 31.5 mm is devoted to measurement of various powdery materials with subsequent determination of particle shape. The AWK B analyser (range from 1 to 130 mm measures materials of thick granulation and shape of the grains. The presented method of measurement repeatedly accelerates and facilitates study of granulometric composition.

  2. Phase dependence of secondary electron emission at the Cs-Sb-Si (111) interface

    Science.gov (United States)

    Govind, Govind; Kumar, Praveen; Shivaprasad, S. M.

    2009-06-01

    The multi-alkali antimonides adsorption on Si (111) surface has drawn much attention of several surface science studies due to its importance in both, fundamental and technological aspects of night vision devices & photocathodes. We report the formation of alkali metal antimonide ternary interface on Si(111)- 7×7 surface and in-situ characterization by X-ray Photoelectron Spectroscopy (XPS). The results show that Cs adsorption on clean Si(111) surface follows the layer-by-layer (Frank van der Merwe) growth mode at low flux rate, while Sb grows as islands (Volmer-Weber) on Cs/Si surface. The changes in the Si (2p) and Cs (3d) core level spectra show the formation of a ternary interface (Sb/Cs/Si) at room temperature, which is further confirmed by changes in the density of states in the valence band spectra. The temperature controlled desorption of ternary interface, by monitoring the chemical species remnant on the surface after annealing at different temperatures, reveal that the Sb islands desorb at 750° C, which implies a stronger Cs-Si bond to Cs-Sb bond. The work function changes from 3.9 eV to 0.8 eV for Cs adsorption on Si, which further reduces to 0.65 eV after Sb adsorption on the Cs/Si interface. The changes in work function corresponds to the compositional and chemical nature of the interface and thus indicate that the secondary electron emission is an extremely phase dependent phenomena.

  3. 试论图书馆电子资源与纸本资源的协调发展%The coordinated development of library electronic resources and paper resources

    Institute of Scientific and Technical Information of China (English)

    冯雷

    2012-01-01

      纸本资源和电子资源属于公共图书馆文献资源中两个非常重要的资源类型,纸本资源和电子资源的协调发展在图书馆的可持续发展过程中起着非常重要的作用。本文对如何实现图书馆电子资源和纸本资源之间的协调发展进行了探讨,希望能够为图书馆文献资源的管理提供一些参考。%  The paper and electronic resources are two very important types of literature resources of public libraries, the coordinated development of the paper and electronic resources play a very important role in the sustainable development process of the library. This article discusses how to realize the coordinated development of library electronic resources and paper resources, hope to provide some reference for library literature resource management.

  4. Self-focusing of coaxial electromagnetic beams in a plasma with electron temperature dependent electron-ion recombination coefficient

    Science.gov (United States)

    Misra, Shikha; Sodha, M. S.; Mishra, S. K.

    2017-02-01

    An analytical formulation, describing the propagation of multiple coaxial Gaussian electromagnetic (em) beams in a self-formed plasma channel with dominant collisional nonlinearity has been developed; the generation/recombination of high energy plasma particles has been considered as an additional source of plasma non-linearity in addition to Ohmic heating. Well versed paraxial approach in the vicinity of the intensity maximum has been adopted to solve the wave equation and examine the non-linear propagation of em beams while the dielectric function in the presence of the em field is determined from the balance of partial pressure gradient of electron/ion gas with the space charge field and energy balance of plasma particles. On the basis of the analysis the influence of this novel non-linearity on the propagation features like electron temperature, dielectric function and critical curves are derived numerically and graphically presented. The inclusion of this novel nonlinearity results in reduced focusing effect. The three regime characteristic features viz. oscillatory focusing/defocusing and steady divergence of beam propagation have also been worked out.

  5. Information on the spur electron distribution from the temperature dependence of positronium yields in the presence of electron scavengers

    Energy Technology Data Exchange (ETDEWEB)

    Levay, B. [Eoetvoes Lorand Univ., Budapest (Hungary). Dept. of Nuclear Chemistry

    2001-07-01

    Positronium yields [I{sub 3}(C)] were measured as a function of temperature in iso-octane solutions of ethyl-bromide and CCl{sub 4} respectively at different but constant concentrations (C) of the positronium inhibitors. The quantity Q{sub C} = {l_brace}1/I{sub 3}(C) - 1{r_brace} plotted as lnQ{sub C} vs. 1/T resulted in an Arrhenius type straight line. According to a simplified model the slope of the curves corresponds to the activation energy difference between the two main competing reaction pathways in the spur, i.e., solvent recombination/scavenging and positronium formation ({delta}E{sup *}{sub C} = E{sup *}{sub r,C} - E{sup *}{sub Ps}). The slopes were found to be positive ({delta}E{sup *}{sub C} < 0 and E{sup *}{sub Ps} > E{sup *}{sub r,C}), i.e., in the presence of electron scavengers higher activation energy was required for positronium formation then for the solvent recombination process. The negative value of {delta}E{sup *}{sub C} was increasing with increasing inhibitor concentration. This observation can be accounted for by the narrowing of the spatial distribution of the spur electrons caused by the scavengers. (orig.)

  6. DEPENDENCE OF ELECTRON-CAPTURE FROM NA-ASTERISK(3P) ON ORBITAL ALIGNMENT - A KINEMATIC EFFECT

    NARCIS (Netherlands)

    SCHLATMANN, AR; MORGENSTERN, R

    1993-01-01

    Recent experimental data of electron capture into He+(4l) states from SIGMA and PI aligned Na*(3p) orbitals are interpreted. Calculations of the overlap integral of the initial Na*(3p) and the final He+(4l) wavefunctions in momentum space reproduce the velocity dependence of the measured cross secti

  7. Structural vs electronic origin of renormalized band widths in TTF-TCNQ: An angular dependent NEXAFS study

    DEFF Research Database (Denmark)

    Sing, M; Meyer, J; Hoinkis, M

    2007-01-01

    We have performed angle-dependent near-edge x-ray absorption fine structure measurements in the Auger electron yield mode on the correlated quasi-one-dimensional organic conductor tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) in order to determine the orientation of the molecules...

  8. Japanese Resource Dependence.

    Science.gov (United States)

    1982-03-01

    the last five years has gone into the Pacific industrial port complexes at Salina Cruz and Lazaro Cardenas . Every aspect of 138 ...... ........i I...rail, by highway, and by oil pipeline. Lazaro Cardenas , once a jungle town, is now the rapidly growing home of Sumitomo Steel and the Sicartsa tube

  9. Laser-induced electron dynamics including photoionization: A heuristic model within time-dependent configuration interaction theory.

    Science.gov (United States)

    Klinkusch, Stefan; Saalfrank, Peter; Klamroth, Tillmann

    2009-09-21

    We report simulations of laser-pulse driven many-electron dynamics by means of a simple, heuristic extension of the time-dependent configuration interaction singles (TD-CIS) approach. The extension allows for the treatment of ionizing states as nonstationary states with a finite, energy-dependent lifetime to account for above-threshold ionization losses in laser-driven many-electron dynamics. The extended TD-CIS method is applied to the following specific examples: (i) state-to-state transitions in the LiCN molecule which correspond to intramolecular charge transfer, (ii) creation of electronic wave packets in LiCN including wave packet analysis by pump-probe spectroscopy, and, finally, (iii) the effect of ionization on the dynamic polarizability of H(2) when calculated nonperturbatively by TD-CIS.

  10. On the Development of Electronic Resources and Paper Resources%关于电子资源与纸本资源协调发展的思考和建议

    Institute of Scientific and Technical Information of China (English)

    王军武

    2012-01-01

    In recent years, a large number of electronic resources was introduced to the libraries, which has become an im- portant component of library resource system. However, there are also a lot of hot debates about the following issues, such as how to build a traditional paper resources, how to deal with the relationship between paper resources and electronic resources, how to build a library resources development system, etc. These problems also confused many librarians who are building resources in the library. With the combination with the opinions from some experts, research scholars, the paper proposed some guiding principles to deal with the relationship between electronic resources and paper resources. Taking all the aspects into consideration, such as the concepts of the library, the funding of the resources, the policies and structure of the library, cooperative development, the paper also proposes some measures for the development of electronic resources and paper resources.%在复合图书馆环境下,如何协调发展电子资源与纸本资源是图书馆界专家、学者研究和探讨的热点问题,也是许多图书馆工作者在文献资源建设实践中十分困惑的问题。文章结合有关专家、学者的研究成果及图书馆的相关案例,概述了电子资源与纸本资源协调发展应遵循的指导性原则,并从馆藏理念、经费投入、馆藏政策、馆藏结构、合作发展、服务利用等几个方面提出了协调发展电子资源与纸本资源的若干举措。

  11. Experimental evidence on RH-dependent crossover from an electronic to protonic conduction with an oscillatory behaviour

    Science.gov (United States)

    Solanki, Vanaraj; Krupanidhi, S. B.; Nanda, K. K.

    2017-06-01

    An oxide semiconductor changes its resistance with exposure of water molecules and is accepted to be governed by electronic and protonic conduction in low and high humid atmosphere, respectively, without any experimental evidences. Here, we report on the experimental evidence of a relative humidity (RH) dependent crossover, from an electronic to protonic conduction and its oscillatory behaviour in mesoporous SnO2. Interestingly, oscillatory conduction observed in the intermediate humidity range (70%-90% RH) lies in between two monotonic variations that substantiate the competitive adsorption and desorption processes of oxygen species and water molecules. In addition, we have shown that the conduction process can be tuned predominantly electronic or protonic by pre- and post-UV treatment. The conductance increases by 2-3 orders as the conduction changes from pure electronic to protonic, suggesting an insulator-to-metal like transition.

  12. Temperature and electron density dependence of spin relaxation in GaAs/AlGaAs quantum well

    Directory of Open Access Journals (Sweden)

    Han Lifen

    2011-01-01

    Full Text Available Abstract Temperature and carrier density-dependent spin dynamics for GaAs/AlGaAs quantum wells (QWs with different structural symmetries have been studied by using time-resolved Kerr rotation technique. The spin relaxation time is measured to be much longer for the symmetrically designed GaAs QW comparing with the asymmetrical one, indicating the strong influence of Rashba spin-orbit coupling on spin relaxation. D'yakonov-Perel' mechanism has been revealed to be the dominant contribution for spin relaxation in GaAs/AlGaAs QWs. The spin relaxation time exhibits non-monotonic-dependent behavior on both temperature and photo-excited carrier density, revealing the important role of non-monotonic temperature and density dependence of electron-electron Coulomb scattering. Our experimental observations demonstrate good agreement with recently developed spin relaxation theory based on microscopic kinetic spin Bloch equation approach.

  13. Time-dependent restricted-active-space self-consistent-field theory for laser-driven many-electron dynamics

    DEFF Research Database (Denmark)

    Miyagi, Haruhide; Madsen, Lars Bojer

    2013-01-01

    We present the time-dependent restricted-active-space self-consistent-field (TD-RASSCF) theory as a framework for the time-dependent many-electron problem. The theory generalizes the multiconfigurational time-dependent Hartree-Fock (MCTDHF) theory by incorporating the restricted-active-space scheme...... well known in time-independent quantum chemistry. Optimization of the orbitals as well as the expansion coefficients at each time step makes it possible to construct the wave function accurately while using only a relatively small number of electronic configurations. In numerical calculations of high......-order harmonic generation spectra of a one-dimensional model of atomic beryllium interacting with a strong laser pulse, the TD-RASSCF method is reasonably accurate while largely reducing the computational complexity. The TD-RASSCF method has the potential to treat large atoms and molecules beyond the capability...

  14. Examining real-time time-dependent density functional theory nonequilibrium simulations for the calculation of electronic stopping power

    Science.gov (United States)

    Yost, Dillon C.; Yao, Yi; Kanai, Yosuke

    2017-09-01

    In ion irradiation processes, electronic stopping power describes the energy transfer rate from the irradiating ion to the target material's electrons. Due to the scarcity and significant uncertainties in experimental electronic stopping power data for materials beyond simple solids, there has been growing interest in the use of first-principles theory for calculating electronic stopping power. In recent years, advances in high-performance computing have opened the door to fully first-principles nonequilibrium simulations based on real-time time-dependent density functional theory (RT-TDDFT). While it has been demonstrated that the RT-TDDFT approach is capable of predicting electronic stopping power for a wide range of condensed matter systems, there has yet to be an exhaustive examination of the physical and numerical approximations involved and their effects on the calculated stopping power. We discuss the results of such a study for crystalline silicon with protons as irradiating ions. We examine the influences of key approximations in RT-TDDFT nonequilibrium simulations on the calculated electronic stopping power, including approximations related to basis sets, finite size effects, exchange-correlation approximation, pseudopotentials, and more. Finally, we propose a simple and efficient correction scheme to account for the contribution from core-electron excitations to the stopping power, as it was found to be significant for large proton velocities.

  15. Electronic medical record data to identify variables associated with a fibromyalgia diagnosis: importance of health care resource utilization

    Directory of Open Access Journals (Sweden)

    Masters ET

    2015-03-01

    Full Text Available Elizabeth T Masters,1 Jack Mardekian,1 Birol Emir,1 Andrew Clair,1 Max Kuhn,2 Stuart L Silverman,31Pfizer, Inc., New York, NY, 2Pfizer, Inc., Groton, CT, 3Cedars-Sinai Medical Center, Los Angeles, CA, USABackground: Diagnosis of fibromyalgia (FM is often challenging. Identifying factors associated with an FM diagnosis may guide health care providers in implementing appropriate diagnostic and management strategies.Methods: This retrospective study used the de-identified Humedica electronic medical record (EMR database to identify variables associated with an FM diagnosis. Cases (n=4,296 were subjects ≥18 years old with ≥2 International Classification of Diseases, Ninth Revision (ICD-9 codes for FM (729.1 ≥30 days apart during 2012, associated with an integrated delivery network, with ≥1 encounter with a health care provider in 2011 and 2012. Controls without FM (no-FM; n=583,665 did not have the ICD-9 codes for FM. Demographic, clinical, and health care resource utilization variables were extracted from structured EMR data. Univariate analysis identified variables showing significant differences between the cohorts based on odds ratios (ORs.Results: Consistent with FM epidemiology, FM subjects were predominantly female (78.7% vs 64.5%; P<0.0001 and slightly older (mean age 53.3 vs 52.7 years; P=0.0318. Relative to the no-FM cohort, the FM cohort was characterized by a higher prevalence of nearly all evaluated comorbidities; the ORs suggested a higher likelihood of an FM diagnosis (P<0.0001, especially for musculoskeletal and neuropathic pain conditions (OR 3.1 for each condition. Variables potentially associated with an FM diagnosis included higher levels of use of specific health care resources including emergency-room visits, outpatient visits, hospitalizations, and medications. Units used per subject for emergency-room visits, outpatient visits, hospitalizations, and medications were also significantly higher in the FM cohort (P<0

  16. Comparative Analysis for the Urban Metabolic Differences of Two Types of Cities in the Resource-Dependent Region Based on Emergy Theory

    Directory of Open Access Journals (Sweden)

    Chang Liu

    2016-07-01

    Full Text Available Urban metabolism analysis has become a useful and effective tool to explore urban socio-economic processes. In this research, in order to explore the similarities and differences of metabolic characteristics and variation rules of different types of resource-dependent cities, we selected two cities—Taiyuan and Jincheng, the capital and a traditional resource-dependent city of Shanxi province, respectively, as research subjects, we also established an urban metabolic evaluation framework by employing a set of eight emergy-based indicators from socio-economic data from 2007 to 2014, and compared the similarities and discrepancies from the perspectives of metabolic structure, intensity, pressure, and efficiency, and put forward some suggestions for pursuing sustainable development for both cities and pointed out that more types of resource-dependent cities should be incorporated in future research work.

  17. The immediate wound-induced oxidative burst of Saccharina latissima depends on light via photosynthetic electron transport.

    Science.gov (United States)

    McDowell, Ruth E; Amsler, Margaret O; Li, Qian; Lancaster, Jack R; Amsler, Charles D

    2015-06-01

    Reactive oxygen species (ROS) produced by an oxidative burst are an important component of the wound response in algae, vascular plants, and animals. In all taxa, ROS production is usually attributed solely to a defense-related enzyme like NADPH-oxidase (Nox). However, here we show that the initial, wound-induced oxidative burst of the kelp Saccharina latissima depends on light and photosynthetic electron transport. We measured oxygen evolution and ROS production at different light levels and in the presence of a photosynthetic inhibitor, and we used spin trapping and electron paramagnetic resonance as an orthogonal method. Using an in vivo chemical probe, we provide data suggesting that wound-induced ROS production in two distantly related and geographically isolated species of Antarctic macroalgae may be light dependent as well. We propose that electron transport chains are an important and as yet unaddressed component of the wound response, not just for photosynthetic organisms, but for animals via mitochondria as well. This component may have been obscured by the historic use of diphenylene iodonium, which inhibits not only Noxes but also photosynthetic and respiratory electron transport as well. Finally, we anticipate physiological and/or ecological consequences of the light dependence of macroalgal wound-induced ROS since pathogens and grazers do not disappear in the dark.

  18. Temperature dependences of the Hall and magnetoresistance coefficients of vanadium and tantalum single crystals: Anisotropy of electron-phonon scattering

    Energy Technology Data Exchange (ETDEWEB)

    Volkenshtein, N.V.; Veprev, A.G.; Startsev, V.E.; Cherepanov, A.N.; Cherepanov, V.I.

    1985-07-01

    The Hall coefficient R/sub H/(T), transverse magnetoresistance rho/sub c/(T), and the temperature-dependent component rho/sub c/(T) of the impurity electrical resistance are measured as functions of temperature T = 4.2--300 K for vanadium and tantalum single crystals with rho/sub 273.2//rho/sub 4.2/ = 1350 and 500, respectively. The curves R/sub H/(T) have minima at T0 = 33 and 24 K for vanadium and tantalum, respectively, which indicates that the electron-phonon scattering is anisotropic. The anisotropy is caused by ''intersheet'' electron-phonon processes in which the charge carriers are scattered between the open hole surface GAMMAH3h and the closed hole ellipsoids N3h. The curves r/sub H/(T) and rho/sub c/(T) have maxima for T close to T0. The observed extrema have a common physical origin and can be explained by the Kagan-Zhernov-Flerov theory, which postulates that the nonequilibrium part of the electron distribution function is anisotropic. The observed dependence R/sub H/(T) for T>T0 agrees with calculations of R/sub H/(T) for vanadium based on realistic models for the electron and phonon spectra, including the anisotropy for the electron-phonon interaction matrix element.

  19. Survey on User Satisfaction of Electronic Resources in University Libraries%高校图书馆电子资源用户满意度调查

    Institute of Scientific and Technical Information of China (English)

    陈姚竹; 马东

    2011-01-01

    通过分析影响用户对图书馆电子资源利用的因素,以美国顾客满意度指数模型为基础,提出关于各个因素的测量指标,对高校图书馆电子资源用户满意度进行测量。%Through analyzing the influencing factors on utilizing library electronic resources, based on the model of American customer satisfaction index, the paper puts forward corresponding measurement indexes, and then measures the user satisfaction on electronic resources of university library

  20. Temperature Dependence of the Kinetic Energy of the Correlated Electron Plasma by Restricted Path-Integral Molecular Dynamics

    Science.gov (United States)

    Runge, Keith; Deymier, Pierre

    2013-03-01

    Recent progress in orbital-free Density Functional Theory (OF-DFT), particularly with regard to temperature dependent functionals, has promise for the simulation of warm dense matter (WDM) systems. WDM includes systems with densities of an order of magnitude beyond ambient or more and temperatures measured in kilokelvin. A challenge for the development of temperature dependent OF-DFT functionals is the lack of benchmark information with temperature and pressure dependence on simple models under WDM conditions. We present an approach to fill this critical gap using the restricted path-integral molecular dynamics (rPIMD) method. Electrons are described as harmonic necklaces within the discrete path integral representation while quantum exchange takes the form of cross linking between electron necklaces. A molecular dynamics algorithm is used to sample phase space and the fermion sign problem is addressed by restricting the density matrix to positive values. The temperature dependence of kinetic energies for the strongly coupled electron plasma is presented for a number of Wigner-Seitz radii in terms of a fourth order Sommerfeld expansion. Supported by US DoE Grant DE-SC0002139

  1. Electron-pair densities with time-dependent quantum Monte-Carlo

    CERN Document Server

    Christov, Ivan P

    2013-01-01

    In this paper we use sets of de Broglie-Bohm trajectories to describe the quantum correlation effects which take place between the electrons in helium atom due to exchange and Coulomb interactions. A short-range screening of the Coulomb potential is used to modify the repulsion between the same spin electrons in physical space in order to comply with the Pauli's exclusion principle. By calculating the electron-pair density for ortho-helium we found that the shape of the exchange hole can be controlled uniquely by a simple screening parameter. For para-helium the inter-electronic distance, and hence the Coulomb hole, results from the combined action of the Coulomb repulsion and the non-local quantum correlations. In this way a robust and self-interaction-free approach is present to find both the ground state and the time evolution of non-relativistic quantum systems.

  2. Dosimetric dependence of the dimensional characteristics on a lead shield in electron radiotherapy: a Monte Carlo study.

    Science.gov (United States)

    Chow, James C L; Grigorov, G N

    2009-04-29

    This study investigates the dosimetric dependence of the dimension of a lead (Pb) layer for shielding using clinical electron beams with different energies. Monte Carlo simulations were used to generate phase space files of the 4, 9 and 16 MeV electron beams produced by a Varian 21 EX linear accelerator using the EGSnrc-based BEAMnrc code, and validated by measurements using films. Pb layers with different thicknesses (2, 4, 6 and 8 mm) and diameters (2.5, 3, 3.5 and 4 cm) were placed at the center of an electron field on a Solid Water phantom. Beam profiles were determined at the depth of maximum dose (d(m)) using Monte Carlo simulations. The line doses under the Pb layer at d(m) including the penumbra at the edge of the layer and relative dose at the central beam axis (CAX) were studied with varying thickness and diameter of the layer. It is found that 2 mm of Pb layer is adequate to provide 5 half value layer (HVL) attenuation for the 4 MeV electron beams, and the beam profiles at dm under the Pb layer depend on the diameter but the thickness of the Pb. However, for the 9 and 16 MeV electron beams, the relative dose at the CAX and dm depends on both the thickness and diameter of the Pb layer. For 8 mm thickness of Pb, 4 and 5 HVL attenuation of electron beams with energies of 9 and 16 MeV can be achieved at d(m), respectively. Moreover, the beam profile under the Pb layer at dm depends on (1) the penumbra region at the edge of the Pb layer, (2) the beam attenuation varying with the thickness of the Pb layer, (3) the electron side scatter contributing to the CAX under the Pb layer, and (4) the photon contamination produced by the Pb layer. A parameter called "shielding area factor", defined as the ratio of the length between two points of 50% relative doses in the beam profile at dm to the diameter of the Pb layer, is suggested to the radiation oncology staff to predict the required size and thickness of Pb for shielding a target with known dimension at d(m). The

  3. Spin-dependent Breit-Wigner and Fano resonances in photon-assisted electron transport through a semiconductor heterostructure

    Institute of Scientific and Technical Information of China (English)

    Hu Li-Yun; Zhou Bin

    2011-01-01

    We theoretically investigate the electron transmission through a seven-layer semiconductor heterostructure with the Dresselhaus spin-orbit coupling under two applied oscillating fields. Numerical results show that both of the spindependent symmetric Breit-Wigner and the asymmetric Fano resonances appear and that the properties of these two types of resonance peaks are dependent on the amplitude and the relative phases of the two applied oscillating fields.The modulation of the spin-polarization efficiency of transmitted electrons by the relative phase is also discussed.

  4. Dependence levels in users of electronic cigarettes, nicotine gums and tobacco cigarettes

    Science.gov (United States)

    ETTER, Jean-François; EISSENBERG, Thomas

    2016-01-01

    Objective To assess dependence levels in users of e-cigarettes, and compare them with dependence levels in users of nicotine gums and tobacco cigarettes. Design Self-reports from cross-sectional Internet and mail surveys. Comparisons of: a) 766 daily users of nicotine-containing e-cigarettes with 30 daily users of nicotine-free e-cigarettes; b) 911 former smokers who used the e-cigarette daily with 451 former smokers who used the nicotine gum daily (but no e-cigarette); c) 125 daily e-cigarette users who smoked daily (dual users) with two samples of daily smokers who did not use e-cigarettes (2206 enrolled on the Internet and 292 enrolled by mail from the general population of Geneva). We used the Fagerström Test for Nicotine Dependence, the Nicotine Dependence Syndrome Scale, the Cigarette Dependence Scale and versions of these scales adapted for e-cigarettes and nicotine gums. Results Dependence ratings were slightly higher in users of nicotine-containing e-cigarettes than in users of nicotine-free e-cigarettes. In former smokers, long-term (>3 months) users of e-cigarettes were less dependent on e-cigarettes than long-term users of the nicotine gum were dependent on the gum. There were few differences in dependence ratings between short-term (cigarettes. Dependence on e-cigarettes was generally lower in dual users than dependence on tobacco cigarettes in the two other samples of daily smokers. Conclusions Some e-cigarette users were dependent on nicotine-containing e-cigarettes, but these products were less addictive than tobacco cigarettes. E-cigarettes may be as or less addictive than nicotine gums, which themselves are not very addictive. PMID:25561385

  5. Investigation on the energy spectrums of electrons in atmospheric pressure argon plasma jets and their dependences on the applied voltage

    Science.gov (United States)

    Chen, Xinxian; Tan, Zhenyu; Liu, Yadi; Li, Xiaotong; Pan, Jie; Wang, Xiaolong

    2017-08-01

    This work presents a systematical investigation on the spatiotemporal evolution of the energy spectrum of electrons in atmospheric pressure argon plasma jets and its dependence on the applied voltage. The investigations are carried out by means of the numerical simulation based on a particle-in-cell Monte-Carlo collision model. The characteristics of the spatiotemporal evolution of the energy spectrum of electrons (ESE) in the discharge space have been presented, and especially the mechanisms of inducing these characteristics have also been revealed. The present work shows the following conclusions. In the evolution of ESE, there is a characteristic time under each applied voltage. Before the characteristic time, the peak value of ESE decreases, the peak position shifts toward high energy, and the distribution of ESE becomes wider and wider, but the reverse is true after the characteristic time. The formation of these characteristics can be mainly attributed to the transport of electrons toward a low electric field as well as a balance between the energy gained from the electric field including the effect of space charges and the energy loss due to inelastic collisions in the process of electron transport. The characteristic time decreases with the applied voltage. In addition, the average energy of electrons at the characteristic time can be increased by enhancing the applied voltage. The results presented in this work are of importance for regulating and controlling the energy of electrons in the plasma jets applied to plasma medicine.

  6. Development of an electronic medical record based alert for risk of HIV treatment failure in a low-resource setting.

    Directory of Open Access Journals (Sweden)

    Nancy Puttkammer

    Full Text Available BACKGROUND: The adoption of electronic medical record systems in resource-limited settings can help clinicians monitor patients' adherence to HIV antiretroviral therapy (ART and identify patients at risk of future ART failure, allowing resources to be targeted to those most at risk. METHODS: Among adult patients enrolled on ART from 2005-2013 at two large, public-sector hospitals in Haiti, ART failure was assessed after 6-12 months on treatment, based on the World Health Organization's immunologic and clinical criteria. We identified models for predicting ART failure based on ART adherence measures and other patient characteristics. We assessed performance of candidate models using area under the receiver operating curve, and validated results using a randomly-split data sample. The selected prediction model was used to generate a risk score, and its ability to differentiate ART failure risk over a 42-month follow-up period was tested using stratified Kaplan Meier survival curves. RESULTS: Among 923 patients with CD4 results available during the period 6-12 months after ART initiation, 196 (21.2% met ART failure criteria. The pharmacy-based proportion of days covered (PDC measure performed best among five possible ART adherence measures at predicting ART failure. Average PDC during the first 6 months on ART was 79.0% among cases of ART failure and 88.6% among cases of non-failure (p<0.01. When additional information including sex, baseline CD4, and duration of enrollment in HIV care prior to ART initiation were added to PDC, the risk score differentiated between those who did and did not meet failure criteria over 42 months following ART initiation. CONCLUSIONS: Pharmacy data are most useful for new ART adherence alerts within iSanté. Such alerts offer potential to help clinicians identify patients at high risk of ART failure so that they can be targeted with adherence support interventions, before ART failure occurs.

  7. Excitation dependent bidirectional electron transfer in phthalocyanine-functionalised MoS2 nanosheets.

    Science.gov (United States)

    Nguyen, Emily P; Carey, Benjamin J; Harrison, Christopher J; Atkin, Paul; Berean, Kyle J; Della Gaspera, Enrico; Ou, Jian Zhen; Kaner, Richard B; Kalantar-Zadeh, Kourosh; Daeneke, Torben

    2016-09-15

    Two-dimensional (2D) transition metal chalcogenides such as 2D MoS2 are considered prime candidate materials for the design of next generation optoelectronics. Functionalisation of these materials is considered to be a key step in tailoring their properties towards specific applications and unlocking their full potential. Here we present a van der Waals functionalisation strategy for creating MoS2 nanosheets decorated with free base phthalocyanine chromophores. The semiconducting sheets are found to intimately interact with these optoelectronically active chromophores, resulting in an electronic heterostructure that exhibits enhanced optoelectronic properties and exploitable charge transfer. We show that by utilising laterally confined MoS2 nanosheets, the conduction band of the semiconductor could be positioned between the chromophore's S1 and S2 states. Consequently, bidirectional photoinduced electron transfer processes are observed, with excitation of the functionalised nanosheet's semiconductor transition resulting in electron transfer to the phthalocyanine's LUMO, and excitation of the chromophore's S2 state leading to electron injection into the MoS2 conduction band. However, charge transfer from the dye's S1 transition to the MoS2 nanosheet is found to be thermodynamically unfavourable, resulting in intense radiative recombination. These findings may enable controlling and tuning the charge carrier density of semiconducting nanosheets via optical means through the exploitation of photoinduced electron transfer. Furthermore this work provides access to 2D semiconductor-hybrids with tailored absorption profiles and photoluminescence.

  8. Electron transfer capacity dependence of quinone-mediated Fe(III) reduction and current generation by Klebsiella pneumoniae L17.

    Science.gov (United States)

    Li, Xiaomin; Liu, Liang; Liu, Tongxu; Yuan, Tian; Zhang, Wei; Li, Fangbai; Zhou, Shungui; Li, Yongtao

    2013-06-01

    Quinone groups in exogenous electron shuttles can accelerate extracellular electron transfer (EET) from bacteria to insoluble terminal electron acceptors, such as Fe(III) oxides and electrodes, which are important in biogeochemical redox processes and microbial electricity generation. However, the relationship between quinone-mediated EET performance and electron-shuttling properties of the quinones remains incompletely characterized. This study investigates the effects of a series of synthetic quinones (SQs) on goethite reduction and current generation by a fermenting bacterium Klebsiella pneumoniae L17. In addition, the voltammetric behavior and electron transfer capacities (ETCs) of SQ, including electron accepting (EAC) and donating (EDC) capacities, is also examined using electrochemical methods. The results showed that SQ can significantly increase both the Fe(III) reduction rates and current outputs of L17. Each tested SQ reversibly accepted and donated electrons as indicated by the cyclic voltammograms. The EAC and EDC results showed that Carmine and Alizarin had low relative capacities of electron transfer, whereas 9,10-anthraquinone-2,6-disulfonic acid (AQDS), 2-hydroxy-1,4-naphthoquinone (2-HNQ), and 5-hydroxy-1,4-naphthoquinone (5-HNQ) showed stronger relative ETC, and 9,10-anthraquinone-2-carboxylic acid (AQC) and 9,10-anthraquinone-2-sulfonic acid (AQS) had high relative ETC. Enhancement of microbial goethite reduction kinetics and current outputs by SQ had a good linear relationship with their ETC, indicating that the effectiveness of quinone-mediated EET may be strongly dependent on the ETC of the quinones. Therefore, the presence of quinone compounds and fermenting microorganisms may increase the diversity of microbial populations that contribute to element transformation in natural environments. Moreover, ETC determination of different SQ would help to evaluate their performance for microbial EET under anoxic conditions. Copyright © 2013 Elsevier

  9. Size dependence of electron spin dephasing in InGaAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Y. Q.; Puttisong, Y.; Buyanova, I. A.; Chen, W. M. [Department of Physics, Chemistry and Biology, Linköping University, S-581 83 Linköping (Sweden); Yang, X. J.; Subagyo, A.; Sueoka, K.; Murayama, A. [Graduate School of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo 060-0814 (Japan)

    2015-03-02

    We investigate ensemble electron spin dephasing in self-assembled InGaAs/GaAs quantum dots (QDs) of different lateral sizes by employing optical Hanle measurements. Using low excitation power, we are able to obtain a spin dephasing time T{sub 2}{sup *} (in the order of ns) of the resident electron after recombination of negative trions in the QDs. We show that T{sub 2}{sup *} is determined by the hyperfine field arising from the frozen fluctuation of nuclear spins, which scales with the size of QDs following the Merkulov-Efros-Rosen model. This scaling no longer holds in large QDs, most likely due to a breakdown in the lateral electron confinement.

  10. Geometry dependent structural and electronic properties of CdS nanowires: An ab-inito study

    Science.gov (United States)

    Khan, Md Shahzad; Srivastava, Anurag

    2017-01-01

    Cadmium sulphide nanowires in wurtzite hexagonal and triangular shape have been investigated using density functional theory based ab initio approach. Stability of these nanowires increases with enlarging diameter, evaluated in terms of formation energies. The increase in diameter of these geometric nanowires, reduces the bandgap, however increases the electronic charge carrier mobility. Electron difference density contour analysis reveal almost similar distribution of charges over diametrically large triangular and hexagonal nanowires. These observations further verified for almost same effective mass of negative and positive charge carriers along the length of large diameter nanowires and may be considered for their use in solar cells and Gas/chemical sensors.

  11. Directly Characterizing the Relative Strength and Momentum Dependence of Electron-Phonon Coupling Using Resonant Inelastic X-Ray Scattering

    Science.gov (United States)

    Devereaux, T. P.; Shvaika, A. M.; Wu, K.; Wohlfeld, K.; Jia, C. J.; Wang, Y.; Moritz, B.; Chaix, L.; Lee, W.-S.; Shen, Z.-X.; Ghiringhelli, G.; Braicovich, L.

    2016-10-01

    The coupling between lattice and charge degrees of freedom in condensed matter materials is ubiquitous and can often result in interesting properties and ordered phases, including conventional superconductivity, charge-density wave order, and metal-insulator transitions. Angle-resolved photoemission spectroscopy and both neutron and nonresonant x-ray scattering serve as effective probes for determining the behavior of appropriate, individual degrees of freedom—the electronic structure and lattice excitation, or phonon dispersion, respectively. However, each provides less direct information about the mutual coupling between the degrees of freedom, usually through self-energy effects, which tend to renormalize and broaden spectral features precisely where the coupling is strong, impacting one's ability to quantitatively characterize the coupling. Here, we demonstrate that resonant inelastic x-ray scattering, or RIXS, can be an effective tool to directly determine the relative strength and momentum dependence of the electron-phonon coupling in condensed matter systems. Using a diagrammatic approach for an eight-band model of copper oxides, we study the contributions from the lowest-order diagrams to the full RIXS intensity for a realistic scattering geometry, accounting for matrix element effects in the scattering cross section, as well as the momentum dependence of the electron-phonon coupling vertex. A detailed examination of these maps offers a unique perspective into the characteristics of electron-phonon coupling, which complements both neutron and nonresonant x-ray scattering, as well as Raman and infrared conductivity.

  12. Directly Characterizing the Relative Strength and Momentum Dependence of Electron-Phonon Coupling Using Resonant Inelastic X-Ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Devereaux, T.P.; Shvaika, A.M.; Wu, K.; Wohlfeld, K.; Jia, C.J.; Wang, Y.; Moritz, B.; Chaix, L.; Lee, W.-S.; Shen, Z.-X.; Ghiringhelli, G.; Braicovich, L.

    2016-10-25

    The coupling between lattice and charge degrees of freedom in condensed matter materials is ubiquitous and can often result in interesting properties and ordered phases, including conventional superconductivity, charge-density wave order, and metal-insulator transitions. Angle-resolved photoemission spectroscopy and both neutron and nonresonant x-ray scattering serve as effective probes for determining the behavior of appropriate, individual degrees of freedom—the electronic structure and lattice excitation, or phonon dispersion, respectively. However, each provides less direct information about the mutual coupling between the degrees of freedom, usually through self-energy effects, which tend to renormalize and broaden spectral features precisely where the coupling is strong, impacting one’s ability to quantitatively characterize the coupling. Here, we demonstrate that resonant inelastic x-ray scattering, or RIXS, can be an effective tool to directly determine the relative strength and momentum dependence of the electron-phonon coupling in condensed matter systems. Using a diagrammatic approach for an eight-band model of copper oxides, we study the contributions from the lowest-order diagrams to the full RIXS intensity for a realistic scattering geometry, accounting for matrix element effects in the scattering cross section, as well as the momentum dependence of the electron-phonon coupling vertex. A detailed examination of these maps offers a unique perspective into the characteristics of electron-phonon coupling, which complements both neutron and nonresonant x-ray scattering, as well as Raman and infrared conductivity.

  13. Orbital dependent Rashba splitting and electron-phonon coupling of 2D Bi phase on Cu(100) surface

    Energy Technology Data Exchange (ETDEWEB)

    Gargiani, Pierluigi; Lisi, Simone; Betti, Maria Grazia [Dipartimento di Fisica, Università di Roma “La Sapienza,” Piazzale A. Moro 5, I-00185 Roma (Italy); Ibrahimi, Amina Taleb; Bertran, François; Le Fèvre, Patrick [Synchrotron SOLEIL, Saint-Aubin-BP 48, F-91192 Gif sur Yvette (France); Chiodo, Letizia [Center for Life Nano Science - Sapienza, Istituto Italiano di Tecnologia and European Theoretical Spectroscopy Facility (ETSF), Viale Regina Elena 291, I-00161, Roma (Italy)

    2013-11-14

    A monolayer of bismuth deposited on the Cu(100) surface forms a highly ordered c(2×2) reconstructed phase. The low energy single particle excitations of the c(2×2) Bi/Cu(100) present Bi-induced states with a parabolic dispersion in the energy region close to the Fermi level, as observed by angle-resolved photoemission spectroscopy. The electronic state dispersion, the charge density localization, and the spin-orbit coupling have been investigated combining photoemission spectroscopy and density functional theory, unraveling a two-dimensional Bi phase with charge density well localized at the interface. The Bi-induced states present a Rashba splitting, when the charge density is strongly localized in the Bi plane. Furthermore, the temperature dependence of the spectral density close to the Fermi level has been evaluated. Dispersive electronic states offer a large number of decay channels for transitions coupled to phonons and the strength of the electron-phonon coupling for the Bi/Cu(100) system is shown to be stronger than for Bi surfaces and to depend on the electronic state symmetry and localization.

  14. Orientation dependence of the differential cross section in elastic electron scattering from CH{sub 3}I molecules

    Energy Technology Data Exchange (ETDEWEB)

    Volkmer, M.; Meier, C.; Lieschke, J.; Mihill, A.; Fink, M.; Boewering, N. [Fakultaet fuer Physik, Universitaet Bielefeld, D-33501 Bielefeld (Germany)]|[Center for Advanced Microstructures and Devices, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)]|[Physics Department, University of Texas at Austin, Austin, Texas 78712 (United States)

    1996-03-01

    The elastic differential electron cross section of CH{sub 3}I molecules, state selected with an electrostatic hexapole and oriented in an electric field by the linear Stark effect, was measured as a function of the transferred momentum at electron energies of 700, 1000, and 1250 eV. The molecular-state ensemble was oriented with a preferential direction of the molecular symmetry axis parallel or antiparallel to the electron beam. By switching the orientation on and off, the orientation-dependent interference contribution {bar {ital M}}, normalized to the differential cross section of unoriented molecules, was determined, independently of a model, for scattering angles of 4{degree}{endash}15{degree}. The results, which can be divided into pure orientation and alignment parts, display different dependences on the electron energy and the degree of orientation. Model calculations based on the independent atom model (IAM) were carried out for the state mixture present in the scattering region. They reproduce the orientation contributions fairly well, but show some deviations for the stronger alignment contributions. Assuming the validity of the IAM, a Legendre expansion analysis was carried out to extract the leading Legendre moments characterizing the oriented molecular-state ensemble. {copyright} {ital 1996 The American Physical Society.}

  15. Resolution-of-identity stochastic time-dependent configuration interaction for dissipative electron dynamics in strong fields.

    Science.gov (United States)

    Klinkusch, Stefan; Tremblay, Jean Christophe

    2016-05-14

    In this contribution, we introduce a method for simulating dissipative, ultrafast many-electron dynamics in intense laser fields. The method is based on the norm-conserving stochastic unraveling of the dissipative Liouville-von Neumann equation in its Lindblad form. The N-electron wave functions sampling the density matrix are represented in the basis of singly excited configuration state functions. The interaction with an external laser field is treated variationally and the response of the electronic density is included to all orders in this basis. The coupling to an external environment is included via relaxation operators inducing transition between the configuration state functions. Single electron ionization is represented by irreversible transition operators from the ionizing states to an auxiliary continuum state. The method finds its efficiency in the representation of the operators in the interaction picture, where the resolution-of-identity is used to reduce the size of the Hamiltonian eigenstate basis. The zeroth-order eigenstates can be obtained either at the configuration interaction singles level or from a time-dependent density functional theory reference calculation. The latter offers an alternative to explicitly time-dependent density functional theory which has the advantage of remaining strictly valid for strong field excitations while improving the description of the correlation as compared to configuration interaction singles. The method is tested on a well-characterized toy system, the excitation of the low-lying charge transfer state in LiCN.

  16. First principles study of electronic structure dependent optical properties of oxychalcogenides BiOCu Ch ( Ch = S, Se, Te)

    Science.gov (United States)

    Ul Islam, A. K. M. Farid; Helal, M. A.; Liton, M. N. H.; Kamruzzaman, M.; Islam, H. M. Tariqul

    2017-04-01

    The optical properties of BiOCu Ch and their dependency on the electronic structures are investigated using first principles study. Modified Perdew-Burke-Ernzerhof generalized gradient approximation functional for solids are used to optimize lattice parameters. These optimized lattice parameters are used to calculate the electronic energy band, density of state and optical properties. It is observed that the optical constants are dependent on the energy band gap and also on the contribution of Copper and Chalcogen atoms in the formation of electronic band structure. The obtained results reveal that the optical constants are dominated by the inter-band transitions. In the case of higher incident photon energy these materials behave like metal, where optical constants are dominated by the free carriers. The obtained optical band gaps 0.60, 0.56 and 0.55 eV for BiOCuS, BiOCuSe and BiOCuTe, respectively are consistent with available theoretical results. We also calculate the carrier concentration, electrical conductivity, effective mass of the carrier and their temperature dependency using semi-classical BoltzTraP package. Among these three materials BiOCuTe shows higher electrical conductivity. Analyzing their optical properties, we conclude that these materials are useful in the optoelectronic devices such as coating materials, high frequency reflector, infrared radiation detector and emitter and also important to design quantum devices.

  17. First principles study of electronic structure dependent optical properties of oxychalcogenides BiOCuCh (Ch = S, Se, Te)

    Science.gov (United States)

    Ul Islam, A. K. M. Farid; Helal, M. A.; Liton, M. N. H.; Kamruzzaman, M.; Islam, H. M. Tariqul

    2016-11-01

    The optical properties of BiOCuCh and their dependency on the electronic structures are investigated using first principles study. Modified Perdew-Burke-Ernzerhof generalized gradient approximation functional for solids are used to optimize lattice parameters. These optimized lattice parameters are used to calculate the electronic energy band, density of state and optical properties. It is observed that the optical constants are dependent on the energy band gap and also on the contribution of Copper and Chalcogen atoms in the formation of electronic band structure. The obtained results reveal that the optical constants are dominated by the inter-band transitions. In the case of higher incident photon energy these materials behave like metal, where optical constants are dominated by the free carriers. The obtained optical band gaps 0.60, 0.56 and 0.55 eV for BiOCuS, BiOCuSe and BiOCuTe, respectively are consistent with available theoretical results. We also calculate the carrier concentration, electrical conductivity, effective mass of the carrier and their temperature dependency using semi-classical BoltzTraP package. Among these three materials BiOCuTe shows higher electrical conductivity. Analyzing their optical properties, we conclude that these materials are useful in the optoelectronic devices such as coating materials, high frequency reflector, infrared radiation detector and emitter and also important to design quantum devices.

  18. Impact of electric-field dependent dielectric constants on two-dimensional electron gases in complex oxides

    Energy Technology Data Exchange (ETDEWEB)

    Peelaers, H.; Gordon, L.; Steiauf, D.; Janotti, A.; Van de Walle, C. G. [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States); Krishnaswamy, K. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106-9560 (United States); Sarwe, A. [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States); Applied Physics Department, Chalmers Institute of Technology, Gothenburg SE 412-96 (Sweden)

    2015-11-02

    High-density two-dimensional electron gas (2DEG) can be formed at complex oxide interfaces such as SrTiO{sub 3}/GdTiO{sub 3} and SrTiO{sub 3}/LaAlO{sub 3}. The electric field in the vicinity of the interface depends on the dielectric properties of the material as well as on the electron distribution. However, it is known that electric fields can strongly modify the dielectric constant of SrTiO{sub 3} as well as other complex oxides. Solving the electrostatic problem thus requires a self-consistent approach in which the dielectric constant varies according to the local magnitude of the field. We have implemented the field dependence of the dielectric constant in a Schrödinger-Poisson solver in order to study its effect on the electron distribution in a 2DEG. Using the SrTiO{sub 3}/GdTiO{sub 3} interface as an example, we demonstrate that including the field dependence results in the 2DEG being confined closer to the interface compared to assuming a single field-independent value for the dielectric constant. Our conclusions also apply to SrTiO{sub 3}/LaAlO{sub 3} as well as other similar interfaces.

  19. Dependence of Xmax and multiplicity of electron and muon on different high energy interaction models

    Directory of Open Access Journals (Sweden)

    G Rastegarzadeh

    2010-06-01

    Full Text Available Different high energy interaction models are the applied in CORSIKA code to simulate Extensive Air Showers (EAS generated by Cosmic Rays (CR. In this work the effects of QGSJET01, QGSJETII, DPMJET, SIBYLL models on Xmax and multiplicity of secondary electrons and muons at observation level are studied.

  20. A finite element model and electronic analogue of pipeline pressure transients with frequency-dependent friction

    CERN Document Server

    Shu, Jian-Jun

    2014-01-01

    A finite element model and its equivalent electronic analogue circuit of hydraulic transmission lines have been developed. Basic equations are approximated to be a set of ordinary differential equations that can be represented in state space form. The accuracy of the model is demonstrated by comparison with the method of characteristics.

  1. Investigation of point and extended defects in electron irradiated silicon—Dependence on the particle energy

    Energy Technology Data Exchange (ETDEWEB)

    Radu, R.; Pintilie, I.; Nistor, L. C. [National Institute of Materials Physics, Atomistilor 105 bis, Magurele 077125 (Romania); Fretwurst, E.; Lindstroem, G. [Institute for Experimental Physics, University of Hamburg, D-22761 Hamburg (Germany); Makarenko, L. F. [Belarusian State University, Independence Ave. 4, 220030 Minsk (Belarus)

    2015-04-28

    This work is focusing on generation, time evolution, and impact on the electrical performance of silicon diodes impaired by radiation induced active defects. n-type silicon diodes had been irradiated with electrons ranging from 1.5 MeV to 27 MeV. It is shown that the formation of small clusters starts already after irradiation with high fluence of 1.5 MeV electrons. An increase of the introduction rates of both point defects and small clusters with increasing energy is seen, showing saturation for electron energies above ∼15 MeV. The changes in the leakage current at low irradiation fluence-values proved to be determined by the change in the configuration of the tri-vacancy (V{sub 3}). Similar to V{sub 3}, other cluster related defects are showing bistability indicating that they might be associated with larger vacancy clusters. The change of the space charge density with irradiation and with annealing time after irradiation is fully described by accounting for the radiation induced trapping centers. High resolution electron microscopy investigations correlated with the annealing experiments revealed changes in the spatial structure of the defects. Furthermore, it is shown that while the generation of point defects is well described by the classical Non Ionizing Energy Loss (NIEL), the formation of small defect clusters is better described by the “effective NIEL” using results from molecular dynamics simulations.

  2. Menaquinone-dependent succinate dehydrogenase of bacteria catalyzes reversed electron transport driven by the proton potential.

    Science.gov (United States)

    Schirawski, J; Unden, G

    1998-10-01

    Succinate dehydrogenases from bacteria and archaea using menaquinone (MK) as an electron acceptor (succinate/menaquinone oxidoreductases) contain, or are predicted to contain, two heme-B groups in the membrane-anchoring protein(s), located close to opposite sides of the membrane. All succinate/ubiquinone oxidoreductases, however, contain only one heme-B molecule. In Bacillus subtilis and other bacteria that use MK as the respiratory quinone, the succinate oxidase activity (succinate-->O2), and the succinate/menaquinone oxidoreductase activity were specifically inhibited by uncoupler (CCCP, carbonyl cyanide m-chlorophenylhydrazone) or by agents dissipating the membrane potential (valinomycin). Other parts of the respiratory chains were not affected by the agents. Succinate oxidase or succinate/ubiquinone oxidoreductase from bacteria using ubiquinone as an acceptor were not inhibited. We propose that the endergonic electron transport from succinate (Eo' = +30 mV) to MK (Eo' approximately/= -80 mV) in succinate/menaquinone oxidoreductase includes a reversed electron transport across the cytoplasmic membrane from the inner (negative) to the outer (positive) side via the two heme-B groups. The reversed electron transport is driven by the proton or electrical potential, which provides the driving force for MK reduction.

  3. Sequence dependence of electron-induced DNA strand breakage revealed by DNA nanoarrays

    DEFF Research Database (Denmark)

    Keller, Adrian; Rackwitz, Jenny; Cauët, Emilie;

    2014-01-01

    sections for electron induced single strand breaks in specific 13 mer oligonucleotides we used atomic force microscopy analysis of DNA origami based DNA nanoarrays. We investigated the DNA sequences 5'-TT(XYX)3TT with X = A, G, C and Y = T, BrU 5-bromouracil and found absolute strand break cross sections...

  4. Three-dimensional, time-dependent simulation of a regenerative amplifier free-electron laser

    NARCIS (Netherlands)

    Freund, H.P.; Nguyen, D.C.; Sprangle, P.; Slot, van der P.J.M.

    2013-01-01

    Free-electron lasers have been designed to operate over virtually the entire electromagnetic spectrum from microwaves through x rays and in a variety of configurations including amplifiers and oscillators. Oscillators typically operate in the low-gain regime where the full spectral width is ð !=!Þ

  5. Size-Dependent Electron Transfer from Colloidal PbS Nanocrystals to Fullerene

    NARCIS (Netherlands)

    Gocalinska, Agnieszka; Saba, Michele; Quochi, Francesco; Marceddu, Marco; Szendrei, Krisztina; Gao, Jia; Loi, Maria A.; Yarema, Maksym; Seyrkammer, Robert; Heiss, Wolfgang; Mura, Andrea; Bongiovanni, Giovanni; Gocalińska, Agnieszka

    2010-01-01

    We investigate a promising organic/inorganic hybrid composite for solution-processable optoelectronics made by lead sulphide nanoparticles and fullerene derivatives, which combine the sensitivity of PbS to the infrared spectrum with the good electron transport properties of fullerenes. Charge separa

  6. The BRIGHTEN Program: Implementation and Evaluation of a Program to Bridge Resources of an Interdisciplinary Geriatric Health Team via Electronic Networking

    Science.gov (United States)

    Emery, Erin E.; Lapidos, Stan; Eisenstein, Amy R.; Ivan, Iulia I.; Golden, Robyn L.

    2012-01-01

    Purpose: To demonstrate the feasibility of the BRIGHTEN Program (Bridging Resources of an Interdisciplinary Geriatric Health Team via Electronic Networking), an interdisciplinary team intervention for assessing and treating older adults for depression in outpatient primary and specialty medical clinics. The BRIGHTEN team collaborates "virtually"…

  7. The module of methodical support in system of electronic educational resources as the innovative element of the modern maintenance of formation

    Directory of Open Access Journals (Sweden)

    Ольга Николаевна Крылова

    2009-06-01

    Full Text Available The article introduces some results of research, which were devoted to evaluation of tearches' mobility to introduce innovations in the contents of education. The author considers innovative potential of modules of the methodical support for system of electronic educational resources.

  8. Charting a Course through CORAL: Texas A&M University Libraries' Experience Implementing an Open-Source Electronic Resources Management System

    Science.gov (United States)

    Hartnett, Eric; Beh, Eugenia; Resnick, Taryn; Ugaz, Ana; Tabacaru, Simona

    2013-01-01

    In 2010, after two previous unsuccessful attempts at electronic resources management system (ERMS) implementation, Texas A&M University (TAMU) Libraries set out once again to find an ERMS that would fit its needs. After surveying the field, TAMU Libraries selected the University of Notre Dame Hesburgh Libraries-developed, open-source ERMS,…

  9. The BRIGHTEN Program: Implementation and Evaluation of a Program to Bridge Resources of an Interdisciplinary Geriatric Health Team via Electronic Networking

    Science.gov (United States)

    Emery, Erin E.; Lapidos, Stan; Eisenstein, Amy R.; Ivan, Iulia I.; Golden, Robyn L.

    2012-01-01

    Purpose: To demonstrate the feasibility of the BRIGHTEN Program (Bridging Resources of an Interdisciplinary Geriatric Health Team via Electronic Networking), an interdisciplinary team intervention for assessing and treating older adults for depression in outpatient primary and specialty medical clinics. The BRIGHTEN team collaborates "virtually"…

  10. Electronic Information Resources (EIR Adoption in Private University Libraries: The Moderating Effect of Productivity and Relative Advantage on Perceived Usefulness

    Directory of Open Access Journals (Sweden)

    Izuagbe, Roland

    2016-03-01

    Full Text Available The study tested a hybrid model with constructs drawn from the Technology Acceptance Model (TAM and Diffusion of Innovation (DOI theory in order to examine the moderating effect of productivity and relative advantage (RA on perceived usefulness (PU vis-à-vis electronic information resources (EIR adoption in private university libraries in Ogun and Osun States of Nigeria. The descriptive research design was adopted in the study. The population consisted of 61 (55.0% librarians and 50 (45.0% library officers (totaling 116—100% in Babcock University, Bells University, Covenant University, Bowen University, Oduduwa University, and Redeemer's University. Purposive sampling procedure was adopted after which total enumeration was used since the total population is small. The questionnaire was used for data collection. Of the 116 copies of the questionnaire administered, 111 (95.7% were found usable. The instrument was structured based on a 4-point Likert agreement scale of Strongly Agree, Agree, Disagree, and Strongly Disagree. Data were analyzed using descriptive statistics like tables of frequency counts and percentage. The findings revealed that productivity and relative advantage are significant moderators of perceived usefulness of EIR adoption in private university libraries in Ogun and Osun States, Nigeria.

  11. Self-consistent time dependent vibrational and free electron kinetics for CO2 dissociation and ionization in cold plasmas

    Science.gov (United States)

    Capitelli, M.; Colonna, G.; D'Ammando, G.; Pietanza, L. D.

    2017-05-01

    A self-consistent time dependent model, based on the coupling between the Boltzmann equation for free electrons, the non equilibrium vibrational kinetics for the asymmetric mode of CO2 and simplified global models for the dissociation and ionization plasma chemistry, has been applied to conditions which can be met under pulsed microwave (MW), dielectric barrier discharge (DBD) and nanosecond pulsed discharges (NPD). Under MW discharge type conditions, the selected pulse duration generates large concentration of vibrational excited states, which affects the electron energy distribution function (eedf) through the superelastic vibrational collisions. Moreover, in discharge conditions, plateaux appear in the vibrational distribution function (vdf) through the vibrational-vibrational up pumping mechanism, persisting also in the post discharge. In post discharge conditions, also the eedf is characterized by plateaux due to the superelastic collisions between cold electrons and the CO2 electronic state at 10.5 eV. The plateau in vdf increases the dissociation of pure vibrational mechanism (PVM), which can become competitive with the dissociation mechanism induced by electron molecule collisions. The PVM rates increase with the decrease of gas temperature, generating a non-Arrhenius behaviour. The situation completely changes under DBD and NPD type conditions characterized by shorter pulse duration and higher applied E/N values. Under discharge conditions, both vdf and eedf plateaux disappear, reappering in the afterglow.

  12. Conformational changes of the NADPH-dependent cytochrome P450 reductase in the course of electron transfer to cytochromes P450

    DEFF Research Database (Denmark)

    Laursen, Tomas; Jensen, Kenneth; Møller, Birger Lindberg

    2011-01-01

    The NADPH-dependent cytochrome P450 reductase (CPR) is a key electron donor to eucaryotic cytochromes P450 (CYPs). CPR shuttles electrons from NADPH through the FAD and FMN-coenzymes into the iron of the prosthetic heme-group of the CYP. In the course of these electron transfer reactions, CPR...

  13. Spin—Dependent Scattering Effects and Dimensional Crossover in a Quasi—Two—Dimensional Disordered Electron System

    Institute of Scientific and Technical Information of China (English)

    YANGYong-Hong; WANGYong-Gang; 等

    2002-01-01

    Two kinds of spin-dependent scattering effects (magnetic-impurity and spin-orbit scatterings) are investigated theoretically in a quasi-tow-dimensional (quasi-2D) disordered electron system.By making use of the diagrammatic techniques in perturbation theory,we have calculated the dc conductivity and magnetoresistance due to weak-localization effects,the analytical expressions of them are obtained as functions of the interlayer hopping energy and the characteristic times:elastic,inelastic,magnetic and spin-orbit scattering times.The relevant dimensional crossover behavior from 3D to 2D with decreasing the interlayer coupling is discussed,and the condition for the crossover is shown to be dependent on the aforementioned scattering times.At low temperature there exists a spin-dependent-scattering-induced dimensional crossover in this system.

  14. Approximate calculation of electronic energy levels of axially symmetric quantum dot and quantum ring by using energy dependent effective mass

    Institute of Scientific and Technical Information of China (English)

    Liu Yu-Min; Yu Zhong-Yuan

    2009-01-01

    Calculations of electronic structures about the semiconductor quantum dot and the semiconductor quantum ring are presented in this paper. To reduce the calculation costs, for the quantum dot and the quantum ring, their simplified axially symmetric shapes are utilized in our analysis. The energy dependent effective mass is taken into account in solving the Schrodinger equations in the single band effective mass approximation. The calculated results show that the energy dependent effective mass should be considered only for relatively small volume quantum dots or small quantum rings. For large size quantum materials, both the energy dependent effective mass and the parabolic effective mass can give the same results. The energy states and the effective masses of the quantum dot and the quantum ring as a function of geometric parameters are also discussed in detail.

  15. Dependence of Mechanical and Thermal Properties of Thermoplastic Composites on Electron Beam Irradiation

    Science.gov (United States)

    Kim, Sok Won; Park, K.; Lee, S. H.; Kang, J. S.; Kang, K. H.

    2007-06-01

    Since the restrictions for environmental protection being strengthened, thermoplastics reinforced with natural fibers (NF’s), such as jute, kenaf, flax, etc. have appeared as alternatives to chemical plastics for automobile interior materials. In this study, the thermal conductivity, tensile strength, and deformation of several kinds of thermoplastic composites composed of 50% polypropylene (PP) and 50% natural fiber (NF) irradiated by an electron beam (energy: 0.5 MeV, dose: 0 20 kGy) were measured. The length and thickness of PP and NF are 80 ± 10 mm and 40 120 μm, respectively. The results show that the thermal conductivity and the tensile strength changed and became minimum, when the dose of the electron beam was 10 kGy. However, the effect of the dose on the deformation was not clear.

  16. Energy dependent fractal dimension in lateral electron distribution of extensive air showers

    Directory of Open Access Journals (Sweden)

    D. Purmohammad

    2008-12-01

    Full Text Available   Secondary electrons at ground level of simulated extensive air showers have been analyzed using a wavelet transform based technique, in order to investigate the variation of fractal dimensions of the lateral distribution of the electrons with shower energy and primary particle mass number. The fractal dimension is shown to increase with shower energy and seems to saturate to constant values near the core of the shower at higher energies. Using the fractal dimension properties at different core distances, a multi-parameter separation technique is then applied to the data. It has been shown that the technique has good accuracy at high energy, provided the energy of the shower is obtained independently.

  17. Stoichiometric relationship between energy-dependent proton ejection and electron transport in mitochondria.

    Science.gov (United States)

    Brand, M D; Reynafarje, B; Lehninger, A L

    1976-02-01

    The number of protons ejected during electron transport per pair of electrons per energy-conserving site (the H+/site ratio) was measured in rat liver mitochondria by three different methods under conditions in which transmembrane movements of endogenous phosphate were minized or eliminated. (1) In the Ca2+ pulse method, between 3.5 and 4.0 molecules of 3-hydroxybutyrate and 1.75 to 2.0 Ca2+ ions were accumulated per 2 e- per site during Ca2+ induced electron transport in the presence of rotenone, when measured under conditions in which movements of endogenous phosphate were negligible. Since entry of 3-hydroxybutyrate requires its protonation to the free acid these data correspond to an H+/site ratio of 3.5-4.0 (2) In the oxygen pulse method addition of known amounts of oxygen to anaerobic mitochondria in the presence of substrate yielded H+/site ratios of 3.0 when phosphate transport was eliminated by addition of N-ethylmaleimide or by anaerobic washing to remove endogenous phosphate. In the absence of such measures the observed H+/site ratio was 2.0. (3) In the reductant pulse method measurement of the initial steady rates of H+ ejection and oxygen consumption by mitochondria in an aerobic medium after addition of substrate gave H+/site near 4.0 in the presence of N-ethylmaleimide; in the absence of the inhibitor the observed ratio was only 2.0. These and other experiments reported indicate that the values of 2.0 earlier obtained for the H+/site ratio by Mitchell and Moyle [Biochem J. (1967) 105, 1147-1162] and others were underestimates due to the unrecognized masking of H+ ejection by movements of endogenous phosphate. The results presented here show that the H+/site ratio of mitochondrial electron transport is at least 3.0 and may be as high as 4.0.

  18. Pressure dependence of the structure and electronic properties of Sr3Ir2O7

    Science.gov (United States)

    Donnerer, C.; Feng, Z.; Vale, J. G.; Andreev, S. N.; Solovyev, I. V.; Hunter, E. C.; Hanfland, M.; Perry, R. S.; Rønnow, H. M.; McMahon, M. I.; Mazurenko, V. V.; McMorrow, D. F.

    2016-05-01

    We study the structural evolution of Sr3Ir2O7 as a function of pressure using x-ray diffraction. At a pressure of 54 GPa at room temperature, we observe a first-order structural phase transition, associated with a change from tetragonal to monoclinic symmetry and accompanied by a 4% volume collapse. Rietveld refinement of the high-pressure phase reveals a novel modification of the Ruddlesden-Popper structure, which adopts an altered stacking sequence of the perovskite bilayers. As the positions of the oxygen atoms could not be reliably refined from the data, we use density functional theory (local-density approximation+U +spin orbit) to optimize the crystal structure and to elucidate the electronic and magnetic properties of Sr3Ir2O7 at high pressure. In the low-pressure tetragonal phase, we find that the in-plane rotation of the IrO6 octahedra increases with pressure. The calculations further indicate that a bandwidth-driven insulator-metal transition occurs at ˜20 GPa, along with a quenching of the magnetic moment. In the high-pressure monoclinic phase, structural optimization resulted in complex tilting and rotation of the oxygen octahedra and strongly overlapping t2 g and eg bands. The t2 g bandwidth renders both the spin-orbit coupling and electronic correlations ineffectual in opening an electronic gap, resulting in a robust metallic state for the high-pressure phase of Sr3Ir2O7 .

  19. Plasma membrane electron transport in Saccharomyces cerevisiae depends on the presence of mitochondrial respiratory subunits.

    Science.gov (United States)

    Herst, Patries M; Perrone, Gabriel G; Dawes, Ian W; Bircham, Peter W; Berridge, Michael V

    2008-09-01

    Most investigations into plasma membrane electron transport (PMET) in Saccharomyces cerevisiae have focused on the inducible ferric reductase responsible for iron uptake under iron/copper-limiting conditions. In this paper, we describe a PMET system, distinct from ferric reductase, which reduces the cell-impermeable water-soluble tetrazolium dye, 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulphophenyl)-2H-tetrazolium monosodium salt (WST-1), under normal iron/copper conditions. WST-1/1-methoxy-phenazine methosulphate reduction was unaffected by anoxia and relatively insensitive to diphenyleneiodonium. Dye reduction was increased when intracellular NADH levels were high, which, in S. cerevisiae, required deletion of numerous genes associated with NADH recycling. Genome-wide screening of all viable nuclear gene-deletion mutants of S. cerevisiae revealed that, although mitochondrial electron transport per se was not required, the presence of several nuclear and mitochondrially encoded subunits of respiratory complexes III and IV was mandatory for PMET. This suggests some form of interaction between components of mitochondrial and plasma membrane electron transport. In support of this, mitochondrial tubular networks in S. cerevisiae were shown to be located in close proximity to the plasma membrane using confocal microscopy.

  20. Dependence of electronic polarization on octahedral rotations in TbMnO3 from first principles

    Science.gov (United States)

    Malashevich, Andrei; Vanderbilt, David

    2009-12-01

    The electronic contribution to the magnetically induced polarization in orthorhombic TbMnO3 is studied from first principles. We compare the cases in which the spin cycloid, which induces the electric polarization via the spin-orbit interaction, is in either the b-c or a-b plane. We find that the electronic contribution is negligible in the first case, but much larger, and comparable to the lattice-mediated contribution, in the second case. However, we show that this behavior is an artifact of the particular pattern of octahedral rotations characterizing the structurally relaxed Pbnm crystal structure. To do so, we explore how the electronic contribution varies for a structural model of rigidly rotated MnO6 octahedra and demonstrate that it can vary over a wide range, comparable with the lattice-mediated contribution, for both b-c and a-b spirals. We present a phenomenological model that is capable of describing this behavior in terms of sums of symmetry-constrained contributions arising from the displacements of oxygen atoms from the centers of the Mn-Mn bonds.

  1. GENERAL REGULARITIES OF FORMATION OF CRYSTAL STRUCTURES OF ELEMENTS DEPENDING ON ELECTRON STRUCTURE OF ATOMS (OBSHCHILE ZAKONOMERNOSTI OBRAZOVANIYA KRISTALLICHESKIKH STRUKTUR ELEMENTOV V ZAVISIMOSTI OT ELEKTRONNOGO STROENIYA ATOMOV),

    Science.gov (United States)

    A table is given showing the dependence of crystalline structures of elements on the number of electrons in the incompleted electronic subshells of...its atoms. The conclusion is drawn that the types of crystalline structures of the elements depend on the configuration of the outer electronic...subshells acquired by the atoms prior to crystallization. Crystalline structures of elements not governed by the 8 - N rule are determined by one or both

  2. No Evidence of Trade-Off between Farm Efficiency and Resilience: Dependence of Resource-Use Efficiency on Land-Use Diversity

    Science.gov (United States)

    Kahiluoto, Helena; Kaseva, Janne

    2016-01-01

    Efficiency in the use of resources stream-lined for expected conditions could lead to reduced system diversity and consequently endanger resilience. We tested the hypothesis of a trade-off between farm resource-use efficiency and land-use diversity. We applied stochastic frontier production models to assess the dependence of resource-use-efficiency on land-use diversity as illustrated by the Shannon-Weaver index. Total revenue in relation to use of capital, land and labour on the farms in Southern Finland with a size exceeding 30 ha was studied. The data were extracted from the Finnish Profitability Bookkeeping data. Our results indicate that there is either no trade-off or a negligible trade-off of no economic importance. The small dependence of resource-use efficiency on land-use diversity can be positive as well as negative. We conclude that diversification as a strategy to enhance farm resilience does not necessarily constrain resource-use efficiency. PMID:27662475

  3. No Evidence of Trade-Off between Farm Efficiency and Resilience: Dependence of Resource-Use Efficiency on Land-Use Diversity.

    Science.gov (United States)

    Kahiluoto, Helena; Kaseva, Janne

    Efficiency in the use of resources stream-lined for expected conditions could lead to reduced system diversity and consequently endanger resilience. We tested the hypothesis of a trade-off between farm resource-use efficiency and land-use diversity. We applied stochastic frontier production models to assess the dependence of resource-use-efficiency on land-use diversity as illustrated by the Shannon-Weaver index. Total revenue in relation to use of capital, land and labour on the farms in Southern Finland with a size exceeding 30 ha was studied. The data were extracted from the Finnish Profitability Bookkeeping data. Our results indicate that there is either no trade-off or a negligible trade-off of no economic importance. The small dependence of resource-use efficiency on land-use diversity can be positive as well as negative. We conclude that diversification as a strategy to enhance farm resilience does not necessarily constrain resource-use efficiency.

  4. Comparison of Energy Dependence of PAGAT Polymer Gel Dosimeter with Electron and Photon Beams using Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    B. Azadbakht

    2012-02-01

    Full Text Available The purpose of this study was to evaluate dependence of PAGAT polymer gel dosimeter 1/T2 on different electron and photon energies for a standard clinically used 60Co therapy unit and an electa linear accelerator.Using MRI, the formulation to give the maximum change in the transverse relaxation rate R2(1/T2 was determined to be 4.5% N,N'-methylen-bis-acrylamide(bis, 4.5% acrylamid(AA, 5% gelatine, 5 mM tetrakis (hydroxymethyl phosphonium chloride (THPC, 0.01 mM hydroquinone (HQ and 86% HPLC(Water. When the preparation of final polymer gel solution is completed, it is transferred into phantoms and allowed to set by storage in a refrigerator at about 4°C. The optimal post-manufacture irradiation and post imaging times were both determined to be 24 h. The sensitivity of PAGAT polymer gel dosimeter with irradiation of photon and electron beams was represented by the slope of calibration curve in the linear region measured for each modality. The response of PAGAT gel with photon and electron beams is very similar in the lower dose region. The R2-dose response was linear up to 30 Gy and the R2-dose response of the PAGAT polymer gel dosimeter is linear between 10 to 30 Gy. In electron beams the R2-dose response for doses less than 3 Gy is not exact, but in photon beams the R2-dose response for doses less than 2Gy is not exact. Dosimeter energy dependence was studied for electron energies of 4, 12 and 18MeV and photon energies of 1.25, 4, 6 and 18 MV. Evaluation of dosimeters were performed on Siemens Symphony, Germany 1.5T Scanner in the head coil. In this study no trend in polymer-gel dosimeter 1/T2 dependence was found on mean energy for electron and photon beams.

  5. Transverse-momentum-dependent parton distribution/fragmentation functions at an electron-ion collider

    NARCIS (Netherlands)

    Anselmino, M.; Avakian, H.; Boer, Daniël; Bradamante, F.; Burkardt, M.; Chen, J.P.; Cisbani, E.; Contalbrigo, M.; Crabb, D.; Dutta, D.; Gamberg, L.; Gao, H.; Hasch, D.; Huang, J.; Huang, M.; Kang, Z.; Keppel, C.; Laskaris, G.; Liang, Z.-T.; Liu, M.X.; Makins, N.; McKeown, R.D.; Metz, A.; Meziani, Z.-E.; Musch, B.; Peng, J.-C.; Prokudin, A.; Qian, X.; Qiang, Y.; Qiu, J.W.; Rossi, P.; SCHWEITZER, C.; Soffer, J.; Sulkosky, V.; Wang, Ying; Xiao, B.; Ye, Q.; Ye, Q.-J.; Yuan, F.; Zhan, X.; Zhang, Y.; Zheng, W.; Zhou, J.

    2011-01-01

    We present a summary of a recent workshop held at Duke University on Partonic Transverse Momentum in Hadrons: Quark Spin-Orbit Correlations and Quark-Gluon Interactions. The transverse-momentum-dependent parton distribution functions (TMDs), parton-to-hadron fragmentation functions, and multi-parton

  6. Comprehensive z-dependent measurements of electron-beam microbunching using COTR in a saturated SASE FEL

    CERN Document Server

    Lumpkin, Alex H; Lewellen, J W; Berg, W; Biedron, S G; Borland, M; Chae, Y; Erdmann, M; Huang, Z; Kim, K J; Li, Y; Milton, S V; Moog, E; Rule, D W; Sajaev, Vadim; Yang, B X

    2002-01-01

    We report the initial, comprehensive set of z-dependent measurements of electron-beam microbunching using coherent optical transition radiation (Cot) in a saturated self-amplified spontaneous emission (SASE) free-electron laser (FEL) experiment. In this case the FEL was operated near 530 nm using an enhanced facility including a bunch-compressed photocathode gun electron beam, linac, and 21.6 m of undulator length. The longitudinal microbunching was tracked by inserting a metal foil and mirror after each of the nine 2.4-m-long undulators and measuring the visible COTR spectra, intensity, angular, distribution, and spot size. We observed for the first time the z-dependent transition of the COTR spectra from simple lines to complex structure/sidebands near saturation. We also observed the change in the microbunching fraction after saturation, multiple fringes in the COTR interferogram that are consistent with involvement of a smaller core of the e-beam transverse distribution, and the second harmonic content of...

  7. Structural Dependence of Electronic Properties in A-A-D-A-A-Type Organic Solar Cell Material

    Directory of Open Access Journals (Sweden)

    Ram S. Bhatta

    2015-01-01

    Full Text Available Small conjugated molecules (SCMs are promising candidates for organic photovoltaic (OPV devices because of their structural simplicity, well control over synthetic reproducibility, and low purification cost. However, industrial development of SCM-based OPV devices requires improving their performance, which in turn relies on the fundamental understanding of structural dependence of electronic properties of SCMs. Herein, we report the structural and electronic properties of the BCNDTS molecule as a model system for acceptor-acceptor-donor-acceptor-acceptor (A-A-D-A-A type SCMs, using density functional theory (DFT and time-dependent DFT methods. Systematic calculations of two-dimensional potential energy surfaces, molecular electrostatic potential surfaces, ground state frontier molecular orbital energies, and the vertical excitation energies are performed. We found that the lowest energy conformation of the BCNDTS molecule is planar. The planar conformation favors the lowest ground state and the excited state energies as well as the strongest oscillator strength. The present results suggest that SCMs containing central dithienosilole cores connected with 2,1,3-benzothiadiazole groups have potential to be an efficient electron donor for OPV devices.

  8. Electronic and optical properties of families of polycyclic aromatic hydrocarbons: A systematic (time-dependent) density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Malloci, G., E-mail: giuliano.malloci@dsf.unica.it [CNR-IOM and Dipartimento di Fisica, Universita degli Studi di Cagliari, Cittadella Universitaria, Strada Prov. le Monserrato-Sestu Km 0.700, I-09042 Monserrato (Italy); Cappellini, G. [CNR-IOM and Dipartimento di Fisica, Universita degli Studi di Cagliari, Cittadella Universitaria, Strada Prov. le Monserrato-Sestu Km 0.700, I-09042 Monserrato (Italy); INAF-Osservatorio Astronomico di Cagliari-Astrochemistry Group, Strada 54, Localita Poggio dei Pini, I-09012 Capoterra (Italy); Mulas, G. [INAF-Osservatorio Astronomico di Cagliari-Astrochemistry Group, Strada 54, Localita Poggio dei Pini, I-09012 Capoterra (Italy); Mattoni, A. [CNR-IOM and Dipartimento di Fisica, Universita degli Studi di Cagliari, Cittadella Universitaria, Strada Prov. le Monserrato-Sestu Km 0.700, I-09042 Monserrato (Italy)

    2011-06-16

    Graphical abstract: Electronic absorption spectra of the neutral molecules of the four PAH classes considered, as computed using the real-time real-space TD-DFT. Highlights: {yields}We present a systematic comparative study of families of PAHs. {yields} We computed electronic, optical, and transport properties as a function of size. {yields} We considered oligoacenes, phenacenes, circumacenes, and oligorylenes. {yields} Circumacenes have the best transport properties compared to the other classes. {yields} Oligorylenes are much more efficient in absorbing low-energy photons. - Abstract: Homologous classes of polycyclic aromatic hydrocarbons (PAHs) in their crystalline state are among the most promising materials for organic opto-electronics. Following previous works on oligoacenes we present a systematic comparative study of the electronic, optical, and transport properties of oligoacenes, phenacenes, circumacenes, and oligorylenes. Using density functional theory (DFT) and time-dependent DFT we computed: (i) electron affinities and first ionization energies; (ii) quasiparticle correction to the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap; (iii) molecular reorganization energies and (iv) electronic absorption spectra of neutral and {+-}1 charged systems. The excitonic effects are estimated by comparing the optical gap and the quasiparticle corrected HOMO-LUMO energy gap. For each molecular property computed, general trends as a function of molecular size and charge state are discussed. Overall, we find that circumacenes have the best transport properties, displaying a steeper decrease of the molecular reorganization energy at increasing sizes, while oligorylenes are much more efficient in absorbing low-energy photons in comparison to the other classes.

  9. Charge-dependent dissociation of insulin cations via ion/ion electron transfer

    Science.gov (United States)

    Liu, Jian; Gunawardena, Harsha P.; Huang, Teng-Yi; McLuckey, Scott A.

    2008-10-01

    The dissociation reactions of various charge states of insulin cations obtained directly from nano-electrospray were investigated as a result of ion/ion electron transfer from azobenzene anions. Data were collected with and without simultaneous ion trap collisional excitation of the first generation charge-reduced product during the ion/ion reaction period. Neither separation of the two constituent chains nor cleavages within the loop defined by the disulfide bridges were observed under normal electron transfer dissociation (ETD) conditions for any of the charge states studied. However, substantial sequence coverage (exocyclic region: 82.6%; entire protein: 38.8%) outside the ring structure was obtained for insulin +6, while only limited coverage (exocyclic: 43.5%; entire protein: 20.4%) was observed for insulin +5 and no dissociation, aside from low abundance side-chain losses, was noted for insulin +4 and +3 in the normal ETD spectra. When the first generation charge-reduced precursor ions were subjected to collisional activation during the ion/ion reaction period, higher sequence coverages were obtained for both insulin +5 (entire protein: 34.7%) and +4 (entire protein: 20.4%) with backbone cleavages occurring within the loop defined by the disulfide bonds. Dissociation of insulin +3 was not significantly improved by the additional activation. Separation of the two constituent chains resulting from cleavages of both of the two disulfide bridges that link the chains was observed for insulin +6, +5, and +4 when the charge-reduced species were activated. The dissociation of disulfide linkages in this study suggests that as the charge state decreases, disulfide bond cleavages dominate over N-C[alpha] bond cleavages in the electron transfer dissociation process.

  10. Prediction of spin-dependent electronic structure in 3d-transition-metal doped antimonene

    Science.gov (United States)

    Yang, L. F.; Song, Y.; Mi, W. B.; Wang, X. C.

    2016-07-01

    We investigate the geometric structure and electronic and magnetic properties of 3d-transition-metal atom doped antimonene using spin-polarized first-principles calculations. Strong orbital hybridization exhibits between 3d-transition-metal and Sb atoms, where covalent bonds form in antimonene. A spin-polarized semiconducting state appears in Cr-doped antimonene, while half-metallic states appear by doping Ti, V, and Mn. These findings indicate that once combined with doping states, the bands of antimonene systems offer a variety of features. Specific dopants lead to half-metallic characters with high spin polarization that has potential application in spintronics.

  11. First principles study on the spin dependent electronic behavior of Co doped ZnO structures joining the Al electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Caliskan, S., E-mail: scaliskan@fatih.edu.tr; Guner, S.

    2015-01-15

    Highlights: • An atomic configuration joining the electrodes can govern spin resolved transport. • Co position and concentration in ZnO have a crucial effect on electronic behavior. • It is possible to obtain high spin polarization in Al–Co doped ZnO–Al systems. • Al–Co doped ZnO–Al device structures reveal Schottky-like contact at the interface. - Abstract: Employing first principles, Co doped ZnO systems between the Al electrodes were investigated through the Density Functional Theory combined with Non Equilibrium Green’s Function Formalism. Electronic transport properties of these systems, in the presence of spin property, were revealed using substitutional Co atoms in a supercell. Spin resolved electronic behavior was observed to be crucially governed by atomic configuration, defined by doping position and concentration, of the system joining the electrodes. Using this feature, one can manipulate both the electronic transport and magnetic properties of an Al–Co doped ZnO–Al device structure. A nonlinearity was exhibited in current–voltage characteristics for Co doped ZnO systems attached to the Al electrodes, which implies a Schottky-like contact at the interface. The induced magnetic moment and spin polarization in the system, yielding the spin dependent transport, were elucidated.

  12. Electronic and optical properties of families of polycyclic aromatic hydrocarbons: A systematic (time-dependent) density functional theory study

    Science.gov (United States)

    Malloci, G.; Cappellini, G.; Mulas, G.; Mattoni, A.

    2011-06-01

    Homologous classes of polycyclic aromatic hydrocarbons (PAHs) in their crystalline state are among the most promising materials for organic opto-electronics. Following previous works on oligoacenes we present a systematic comparative study of the electronic, optical, and transport properties of oligoacenes, phenacenes, circumacenes, and oligorylenes. Using density functional theory (DFT) and time-dependent DFT we computed: (i) electron affinities and first ionization energies; (ii) quasiparticle correction to the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap; (iii) molecular reorganization energies and (iv) electronic absorption spectra of neutral and ±1 charged systems. The excitonic effects are estimated by comparing the optical gap and the quasiparticle corrected HOMO-LUMO energy gap. For each molecular property computed, general trends as a function of molecular size and charge state are discussed. Overall, we find that circumacenes have the best transport properties, displaying a steeper decrease of the molecular reorganization energy at increasing sizes, while oligorylenes are much more efficient in absorbing low-energy photons in comparison to the other classes.

  13. Time-dependent reduced density matrix functional theory applied to laser-driven, correlated two-electron dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Brics, Martins; Kapoor, Varun; Bauer, Dieter [Institut fuer Physik, Universitaet Rostock, 18051 Rostock (Germany)

    2013-07-01

    Time-dependent density functional theory (TDDFT) with known and practicable exchange-correlation potentials does not capture highly correlated electron dynamics such as single-photon double ionization, autoionization, or nonsequential ionization. Time-dependent reduced density matrix functional theory (TDRDMFT) may remedy these problems. The key ingredients in TDRDMFT are the natural orbitals (NOs), i.e., the eigenfunctions of the one-body reduced density matrix (1-RDM), and the occupation numbers (OCs), i.e., the respective eigenvalues. The two-body reduced density matrix (2-RDM) is then expanded in NOs, and equations of motion for the NOs can be derived. If the expansion coefficients of the 2-RDM were known exactly, the problem at hand would be solved. In practice, approximations have to be made. We study the prospects of TDRDMFT following a top-down approach. We solve the exact two-electron time-dependent Schroedinger equation for a model Helium atom in intense laser fields in order to study highly correlated phenomena such as the population of autoionizing states or single-photon double ionization. From the exact wave function we calculate the exact NOs, OCs, the exact expansion coefficients of the 2-RDM, and the exact potentials in the equations of motion. In that way we can identify how many NOs and which level of approximations are necessary to capture such phenomena.

  14. Young-type interferences using single-electron sources and an atomic-size two-center interferometer: Dependence with interferometer parameters

    Energy Technology Data Exchange (ETDEWEB)

    Fremont, F. [Unite mixte Universite de Caen, CNRS, CEA, Ensicaen, CIMAP, 6 bd du Mal Juin, 14050 Caen Cedex (France)], E-mail: francois.fremont@ensicaen.fr; Suarez, S. [Centro Atomico Bariloche and Instituto Balseiro (Comision Nacional de Energia Atomica and Universidad Nacional de Cuyo), 8400 S.C. de Bariloche, Rio Negro (Argentina); Barrachina, R.O. [Laboratoire de Chimie Physique-Matiere et Rayonnement, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Hajaji, A. [Unite mixte Universite de Caen, CNRS, CEA, Ensicaen, CIMAP, 6 bd du Mal Juin, 14050 Caen Cedex (France); Sisourat, N.; Dubois, A. [Laboratoire de Chimie Physique-Matiere et Rayonnement, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Chesnel, J.-Y. [Unite mixte Universite de Caen, CNRS, CEA, Ensicaen, CIMAP, 6 bd du Mal Juin, 14050 Caen Cedex (France)

    2009-01-15

    We present the realization of a Young-type double-slit experiment, in which single electrons, scattering on two protons, produce interference pattern. The electrons are produced by a Auger effect, following double capture process in low He{sup 2+} + H{sub 2} collisions. Well-defined oscillations are visible in the angular distribution of the electrons emitted towards the receding protons. The presence of these oscillations is a clear demonstration that an electron interferes with itself. We also discuss the dependence of the interference pattern with interference parameters, such as the electron wavelength as well as the distance between the protons when the electron is ejected.

  15. A perspective on nonresonant and resonant electronic response theory for time-dependent molecular properties.

    Science.gov (United States)

    Norman, Patrick

    2011-12-14

    The development of electronic response theory in quantum chemistry has been reviewed, starting from the early 1970's and reaching the current state-of-the-art. The general theory has been applied to the calculation of a large number of spectroscopic parameters over the years, and it has been implemented for the majority of standard electronic structure methods. Two formulations of response theory, the Ehrenfest expectation value and the quasi-energy derivative formulation, have turned into leading alternatives for the derivation of computationally tractable expressions of response functions, and they are here reviewed with an attempt to, as far as possible, leave out technical details. A set of four steps are identified as common in derivations of response functions, and the two formulations are compared along this series of steps. Particular emphasis is given to the situation when the oscillation of the weak external electromagnetic field is in resonance with a transition frequency of the system. The formation of physically sound response functions in resonance regions of the spectrum is discussed in light of the causality condition and the Kramers-Kronig relations, and it is achieved in wave function theory by means of the introduction of relaxation parameters in a manner that mimics what one sees in density matrix theory. As a working example, equations are illustrated by their application to a two-state model for para-nitroaniline including the ground and the lowest charge-transfer state in the electric dipole approximation.

  16. Time-Dependent Electron Acceleration in Blazar Transients: X-Ray Time Lags and Spectral Formation

    CERN Document Server

    Lewis, Tiffany R; Finke, Justin D

    2016-01-01

    Electromagnetic radiation from blazar jets often displays strong variability, extending from radio to $\\gamma$-ray frequencies. In a few cases, this variability has been characterized using Fourier time lags, such as those detected in the X-rays from Mrk~421 using BeppoSAX. The lack of a theoretical framework to interpret the data has motivated us to develop a new model for the formation of the X-ray spectrum and the time lags in blazar jets based on a transport equation including terms describing stochastic Fermi acceleration, synchrotron losses, shock acceleration, adiabatic expansion, and spatial diffusion. We derive the exact solution for the Fourier transform of the electron distribution, and use it to compute the Fourier transform of the synchrotron radiation spectrum and the associated X-ray time lags. The same theoretical framework is also used to compute the peak flare X-ray spectrum, assuming that a steady-state electron distribution is achieved during the peak of the flare. The model parameters are...

  17. MD468: Electron Cloud Reference Fills and Dependence on the Bunch Intensity

    CERN Document Server

    Iadarola, Giovanni; Mether, Lotta; Romano, Annalisa; Rumolo, Giovanni; CERN. Geneva. ATS Department

    2017-01-01

    This note describes a Machine Development session performed to investigate the dependence of e-cloud build-up and instabilities on the bunch population of the circulating beam. Three fills were performed with identical filling schemes and RF settings and with different injected bunch intensities. The fill with the largest intensity has also been used as a reference to assess the scrubbing evolution during 2016.

  18. Temperature dependent behavior of localized and delocalized electrons in nitrogen-doped 6H SiC crystals as studied by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Savchenko, D., E-mail: dariyasavchenko@gmail.com [Institute of Physics AS CR, Prague 182 21 (Czech Republic); National Technical University of Ukraine “Kyiv Polytechnic Institute”, Kyiv 03056 (Ukraine); Kalabukhova, E.; Shanina, B.; Kiselov, V. [V.E. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, Kyiv 03028 (Ukraine); Cichoň, S.; Honolka, J. [Institute of Physics AS CR, Prague 182 21 (Czech Republic); Mokhov, E. [A.F. Ioffe Physical Technical Institute, RAS, St. Petersburg 194021 (Russian Federation); Saint-Petersburg National Research University of Information Technologies, Mechanics and Optics, St. Petersburg 19710 (Russian Federation)

    2016-01-28

    We have studied the temperature behavior of the electron spin resonance (ESR) spectra of nitrogen (N) donors in n-type 6H SiC crystals grown by Lely and sublimation sandwich methods (SSM) with donor concentration of 10{sup 17 }cm{sup −3} at T = 60–150 K. A broad signal in the ESR spectrum was observed at T ≥ 80 K with Lorentzian lineshape and g{sub ||} = 2.0043(3), g{sub ⊥} = 2.0030(3), which was previously assigned in the literature to the N donors in the 1s(E) excited state. Based on the analysis of the ESR lineshape, linewidth and g-tensor we attribute this signal to the conduction electrons (CE). The emergence of the CE ESR signal at T > 80 K was explained by the ionization of electrons from the 1s(A{sub 1}) ground and 1s(E) excited states of N donors to the conduction band while the observed reduction of the hyperfine (hf) splitting for the N{sub k1,k2} donors with the temperature increase is attributed to the motional narrowing effect of the hf splitting. The temperature dependence of CE ESR linewidth is described by an exponential law (Orbach process) with the activation energy corresponding to the energy separation between 1s(A{sub 1}) and 1s(E) energy levels for N residing at quasi-cubic sites (N{sub k1,k2}). The theoretical analysis of the temperature dependence of microwave conductivity measured by the contact-free method shows that due to the different position of the Fermi level in two samples the ionization of free electrons occurs from the energy levels of N{sub k1,k2} donors in Lely grown samples and from the energy level of N{sub h} residing at hexagonal position in 6H SiC grown by SSM.

  19. Spin-dependent electron transmission through ultra-thin magnetic layers: towards highly discriminative, compact spin detectors

    Energy Technology Data Exchange (ETDEWEB)

    Van der Sluijs, A.M.; Drouhin, H.J.; Lampel, G.; Lassailly, Y.; Marliere, C. [Ecole Polytechnique, 91 - Palaiseau (France)

    1994-10-01

    At low energy, a longitudinally spin-polarized electron beam impinges on an ultrathin, self-supported ferromagnetic target, consisting of a 1 nm-thick cobalt film sandwiched between 21 and 2 nm-thick gold layers, and which is magnetized perpendicularly to the surface. The current transmitted by the target depends on the spin of the electrons. Cesium deposition on both sides of the target increases the transmission ratio from about 1 x 10{sup -5} up to 3 x 10{sup -4} and also increases the transmission spin-asymmetry from 15 to about 40%. Such a structure is well suited to the construction of convenient and compact spin-detectors. (authors). 4 figs., 9 refs.

  20. A dependência pela prática de exercícios físicos e o uso de recursos ergogênicos = Physical exercise dependence and the use of ergogenic resources

    Directory of Open Access Journals (Sweden)

    José Luiz Lopes Vieira

    2010-01-01

    Full Text Available Objetivou-se Investigar a ocorrência de dependência por exercícios físicos quanto às características de praticantes de musculação e ginástica em academias, como uso de recursos ergogênicos, sexo e índice de massa corporal. Participaram do estudo 80 sujeitos (27,12 ± 6,60 anos, praticantes de ginástica e/ou musculação em academias, de ambos os sexos. Utilizou-se a Escala de Dependência por Exercícios Físicos, a listagem do tipo de suplemento alimentar utilizado como recurso ergogênico e o Índice de Massa Corporal – IMC (Kg/cm². A análise estatística foi realizada por meio da correlação de Spearman e o teste de Wilcoxon (p The aim of this study is to investigate the occurrence of physical exercise dependence in regards to the characteristics of participants in weight training and exercises at gyms, such as the use ofergogenic resources, gender and body mass index. Eighty subjects (27.12 ± 6.60 years from both genders took part in the study, all of whom practiced gymnastics and/or weight training in gyms. The study utilized the Exercise Dependence Scale, a check list of the kinds of nutritional supplementation used as ergogenic resources, and the Body Mass Index – BMI (Kg cm-². Statistical analysis was performed using Spearman's correlation and the Wilcoxon test (p < 0.05. The results showed that there was no statistically significant difference between physical exercise dependence in men (5.14 ± 1.28 and women (5.60 ± 1.45. The body mass index did not show statistically significant correlation with the scores of dependency, either. However, dependentmen showed high prevalence of use of ergogenic resources (63.63%, p = 0.01, while for dependent women there were no statistically significant results. The body mass index does not relate to the scores of exercise dependence. However, even with a normal BMI, the use of ergogenic resources presents high prevalence among dependent men. As a result, there is evidence that

  1. Revisiting the Z-dependence of the electron density at the nuclei

    CERN Document Server

    Khah, Alireza Marefat

    2015-01-01

    A new formula that relates the electron density at the nucleus of atoms,rho(0,Z), and the atomic number,Z, is proposed. This formula,rho(0,Z)=a(Z-bZ^(0.5))^3, contains two unknown parameters (a,b) that are derived using a least square regression to the ab initio derived rho(0,Z) of Koga dataset from He (Z=2) to Lr (Z=103) atoms (Theor Chim Acta 95, 113 (1997)). In comparison to the well-known formula,rho(0,Z)=aZ^b, used for the same purpose previously, the resulting new formula is capable of reproducing the ab initio rho(0,Z) dataset an order of magnitude more precisely without introducing more regression parameters. This new formula may be used to transform the equations that relate correlation energy of atoms and rho(0,Z) into simpler equations just containing the atomic number as a fundamental property of atoms.

  2. Temperature dependence of Q-band electron paramagnetic resonance spectra of nitrosyl heme proteins

    Energy Technology Data Exchange (ETDEWEB)

    Flores, Marco; Wajnberg, Eliane; Bemski, George

    1997-11-01

    The Q-band (35 GHz) electron paramagnetic resonance (EPR) spectra of nitrosyl hemoglobin (Hb N O) and nitrosyl myoglobin (Mb NO) were studied as a function of temperature between 19 K and 200 K. The spectra of both heme proteins show classes of variations as a function of temperature. The first one has previously been associated with the existence of two paramagnetic species, one with rhombic and the other with axial symmetry. The second one manifests itself in changes in the g-factors and linewidths of each species. These changes are correlated with the conformational substates model and associate the variations of g-values with changes in the angle of the N(his)-Fe-N (NO) bond in the rhombic species and with changes in the distance between Fe and N of the proximal (F8) histidine in the axial species. (author) 24 refs., 6 figs.

  3. Doping Dependent Charge Transfer Gap and Realistic Electronic Model of n-type Cuprate Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, T.

    2010-05-03

    Based on the analysis of the measurement data of angle-resolved photoemission spectroscopy (ARPES) and optics, we show that the charge transfer gap is significantly smaller than the optical one and is reduced by doping in electron doped cuprate superconductors. This leads to a strong charge fluctuation between the Zhang-Rice singlet and the upper Hubbard bands. The basic model for describing this system is a hybridized two-band t-J model. In the symmetric limit where the corresponding intra- and inter-band hopping integrals are equal to each other, this two-band model is equivalent to the Hubbard model with an antiferromagnetic exchange interaction (i.e. the t-U-J model). The mean-field result of the t-U-J model gives a good account for the doping evolution of the Fermi surface and the staggered magnetization.

  4. Electric- and magnetic-field dependence of the electronic and optical properties of phosphorene quantum dots

    Science.gov (United States)

    Li, L. L.; Moldovan, D.; Xu, W.; Peeters, F. M.

    2017-02-01

    Recently, black phosphorus quantum dots were fabricated experimentally. Motivated by these experiments, we theoretically investigate the electronic and optical properties of rectangular phosphorene quantum dots (RPQDs) in the presence of an in-plane electric field and a perpendicular magnetic field. The energy spectra and wave functions of RPQDs are obtained numerically using the tight-binding approach. We find edge states within the band gap of the RPQD which are well separated from the bulk states. In an undoped RPQD and for in-plane polarized light, due to the presence of well-defined edge states, we find three types of optical transitions which are between the bulk states, between the edge and bulk states, and between the edge states. The electric and magnetic fields influence the bulk-to-bulk, edge-to-bulk, and edge-to-edge transitions differently due to the different responses of bulk and edge states to these fields.

  5. Structure-Dependent Electronic and Optical Properties of the Martensitic Alloys TiAu

    Institute of Scientific and Technical Information of China (English)

    朱梓忠; 叶亦英

    2002-01-01

    The atomic and electronic structures together with the optical properties of TiAu in the low-temperature B19 and Bll phases are calculated by using first principles local density functional approaches. Our results show that the Bll structure is more stable than B19 for the TiAu alloy in ordered equiatomic composition (Ti:Au =50:50). At Iow temperatures, the Bll structure should exist as a binary alloy from the energetic consideration.The accurate atomic positions in the unit cell have been given by fully force relaxed calculations. The calculated optical conductivities of B19 and Bll phases show a drastic change in the region of 1.5 to 3.5 e V.

  6. Spin-dependent electron-phonon interaction in SmFeAsO by low-temperature Raman spectroscopy.

    Science.gov (United States)

    Zhang, L; Guan, P F; Feng, D L; Chen, X H; Xie, S S; Chen, M W

    2010-11-03

    The interplay between spin dynamics and lattice vibration has been suggested as an important part of the puzzle of high-temperature superconductivity. Here, we report the strong interaction between spin fluctuation and phonon in SmFeAsO, a parent compound of the iron arsenide family of superconductors, revealed by low-temperature Raman spectroscopy. Anomalous zone-boundary-phonon Raman scattering from spin superstructure was observed at temperatures below the antiferromagnetic ordering point, which offers compelling evidence on spin-dependent electron-phonon coupling in pnictides.

  7. Remarkable Dependence of the Final Charge Separation Efficiency on the Donor-Acceptor Interaction in Photoinduced Electron Transfer.

    Science.gov (United States)

    Higashino, Tomohiro; Yamada, Tomoki; Yamamoto, Masanori; Furube, Akihiro; Tkachenko, Nikolai V; Miura, Taku; Kobori, Yasuhiro; Jono, Ryota; Yamashita, Koichi; Imahori, Hiroshi

    2016-01-11

    The unprecedented dependence of final charge separation efficiency as a function of donor-acceptor interaction in covalently-linked molecules with a rectilinear rigid oligo-p-xylene bridge has been observed. Optimization of the donor-acceptor electronic coupling remarkably inhibits the undesirable rapid decay of the singlet charge-separated state to the ground state, yielding the final long-lived, triplet charge-separated state with circa 100% efficiency. This finding is extremely useful for the rational design of artificial photosynthesis and organic photovoltaic cells toward efficient solar energy conversion.

  8. Benchmarks for electronically excited states: Time-dependent density functional theory and density functional theory based multireference configuration interaction

    DEFF Research Database (Denmark)

    Silva-Junior, Mario R.; Schreiber, Marko; Sauer, Stephan P. A.;

    2008-01-01

    Time-dependent density functional theory (TD-DFT) and DFT-based multireference configuration interaction (DFT/MRCI) calculations are reported for a recently proposed benchmark set of 28 medium-sized organic molecules. Vertical excitation energies, oscillator strengths, and excited-state dipole...... moments are computed using the same geometries (MP2/6-31G*) and basis set (TZVP) as in our previous ab initio benchmark study on electronically excited states. The results from TD-DFT (with the functionals BP86, B3LYP, and BHLYP) and from DFT/MRCI are compared against the previous high-level ab initio...

  9. Carrier-Density-Dependent Electron Spin Relaxation in GaAs/AlGaAs Multi Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    SHOU Qian; WU Yu; LIU Lu-Ning; WEN Jin-Hui; LAI Tian-Shu; LIN Wei-Zhu

    2005-01-01

    @@ The carrier-density-dependent electron spin relaxation processes in GaAs/AlGaAs multi quantum wells are investigated by a femtosecond pump probe experiment. The spin relaxation time presents two distinguishable trends with the increasing excitation density. It increases from 60ps to 70ps with carrier densities from 1 × 1017 cm-3to 5 × 1017 cm-3 and gradually saturates up to ~80ps at 4 × 1018 cm-3. The experimental results are attributed to the combined competition between collision intensification and scattering potential screening and provide a good experimental confirmation for the theoretical D'yakonov-Perel' mechanism descriptions.

  10. Electron-Ion Dynamics with Time-Dependent Density Functional Theory: Towards Predictive Solar Cell Modeling: Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Maitra, Neepa [Hunter College City University of New York, New York, NY (United States)

    2016-07-14

    This project investigates the accuracy of currently-used functionals in time-dependent density functional theory, which is today routinely used to predict and design materials and computationally model processes in solar energy conversion. The rigorously-based electron-ion dynamics method developed here sheds light on traditional methods and overcomes challenges those methods have. The fundamental research undertaken here is important for building reliable and practical methods for materials discovery. The ultimate goal is to use these tools for the computational design of new materials for solar cell devices of high efficiency.

  11. Fingerprints of a size-dependent crossover in the dimensionality of electronic conduction in Au-seeded Ge nanowires

    Directory of Open Access Journals (Sweden)

    Maria Koleśnik-Gray

    2016-11-01

    Full Text Available We studied the electrical transport properties of Au-seeded germanium nanowires with radii ranging from 11 to 80 nm at ambient conditions. We found a non-trivial dependence of the electrical conductivity, mobility and carrier density on the radius size. In particular, two regimes were identified for large (lightly doped and small (stronger doped nanowires in which the charge-carrier drift is dominated by electron-phonon and ionized-impurity scattering, respectively. This goes in hand with the finding that the electrostatic properties for radii below ca. 37 nm have quasi one-dimensional character as reflected by the extracted screening lengths.

  12. Oscillatory electron phonon coupling in Pb/Si(111) deduced by temperature-dependent quantum well states

    Institute of Scientific and Technical Information of China (English)

    Zhang Yan-Feng; Jia Jin-Feng; Han Tie-Zhu; Tang Zhe; Shen Quan-Tong; Guo Yang; Xue Qi-Kun

    2005-01-01

    Photoemission study of atomically flat Pb films with a thickness from 15 to 24 monolayers (ML) have been performed within a temperature range 75-270K. Well-defined quantum well states (QWSs) are observed, which exhibit interesting temperature-dependent behaviours. The peak position of the QWSs shifts towards higher binding energy with increasing substrate temperature, whereas the peak width broadens linearly due to enhanced electron-phonon coupling strength (λ). An oscillatory λ with a period of 2ML is deduced. Preliminary analysis shows that the oscillation can be explained in terms of the interface induced phase variations, and is thus a manifestation of the quantum size effects.

  13. Time-dependent restricted-active-space self-consistent eld theory: Formulation and application to laser-driven many-electron dynamics

    DEFF Research Database (Denmark)

    Miyagi, Haruhide; Madsen, Lars Bojer

    We have developed a new theoretical framework for time-dependent many-electron problems named time-dependent restricted-active-space self-consistent field (TD-RASSCF) theory. The theory generalizes the multicongurational time-dependent Hartree-Fock (MCTDHF) theory by truncating the expansion...

  14. A Study on the Model for Resources Matching of Electronic Bartering%电子易货资源匹配模型研究

    Institute of Scientific and Technical Information of China (English)

    吴剑云; 张嵩

    2012-01-01

    By exchanging idle goods and services, electronic bartering can help enterprises solve dull sale problems, shortage of funds, overstocks and other problems without sufficient cash. Relying on the Internet and the e-commerce platform, electronic bartering removes the traditional bartering limitations, greatly expands the trading object and range, improves the transaction efficiency, and provides additional channels for economic development. How to promote more successful barters among multiple barterers? A key factor is the matching of barter resources. Focusing on the automatic matching of resources in the electronic barter, this paper proposes a network model to help maximize resources matching and provide recommendation information for barter participants, thereby raising the transaction rate and making the barter market prosperous.According to the type and quantity of barter resources, barter market can be divided into two types. In the first type, the supply and demand of the barter market is related to the same type of resources and each barterer owns only one type of resource. In the second type, the supply and demand of the barter market is linked to many types of resources and each barterer owns multiple resources to be exchanged. The first case has been resolved in the relevant document by using the graph theory to solve digraph circuits. This paper is interested in studying the second type of barter. Suppose the barter market has m barterers and n resources. Each barterer owns diverse types of barter resources, and is interested in other types of resources. The barterer a will provide other barterers his own resources only if he gets the resources he needs from the barterer b. Note that each of the bartered resource is regarded as having equal value to any other resources. The main objective is to maximize the number of resources that are bartered.Next, this paper proposes a math model of automatic resources matching by systematically analyzing resource

  15. Probing autoionizing states of molecular oxygen with XUV transient absorption: Electronic symmetry dependent lineshapes and laser induced modification

    CERN Document Server

    Liao, Chen-Ting; Haxton, Daniel J; Rescigno, Thomas N; Lucchese, Robert R; McCurdy, C William; Sandhu, Arvinder

    2016-01-01

    The dynamics of autoionizing Rydberg states of oxygen are studied using attosecond transient absorption technique, where extreme ultraviolet (XUV) initiates molecular polarization and near infrared (NIR) pulse perturbs its evolution. Transient absorption spectra show positive optical density (OD) change in the case of $ns\\sigma_g$ and $nd\\pi_g$ autoionizing states of oxygen and negative OD change for $nd\\sigma_g$ states. Multiconfiguration time-dependent Hartree-Fock (MCTDHF) calculation are used to simulate the transient absorption spectra and their results agree with experimental observations. The time evolution of superexcited states is probed in electronically and vibrationally resolved fashion and we observe the dependence of decay lifetimes on effective quantum number of the Rydberg series. We model the effect of near-infrared (NIR) perturbation on molecular polarization and find that the laser induced phase shift model agrees with the experimental and MCTDHF results, while the laser induced attenuation...

  16. Time-Dependent Simulation of Free-Electron Laser Amplifiers and Oscillators

    CERN Document Server

    Freund, H

    2005-01-01

    Time-dependent FEL simulations use a variety of techniques. Most simulations use a slowly varying envelope approximation (SVEA). One such technique assumes that the envelope varies only in z combined with a field representation as an ensemble of discrete harmonics, which is equivalent to a time-dependent simulation [1] but is computationally prohibitive. A second technique uses an SVEA in both in z and t [2]. The particles and fields are advanced in z using the same process as in steady-state simulations and then the time derivative describing slippage is applied. This is used in wiggler-averaged codes such as GINGER [3] and GENESIS [4]. We describe the inclusion of this technique in the non-wiggler-averaged code MEDUSA [5], which is applied to amplifiers and oscillators. MEDUSA differs from GINGER and GENESIS also in the way the field is treated. GINGER and GENESIS use a field solver and must explicitly propagate the field outside the wiggler oscillators. This is computationally intensive. MEDUSA uses a Gaus...

  17. Spin- and valley-dependent electronic band structure and electronic heat capacity of ferromagnetic silicene in the presence of strain, exchange field and Rashba spin-orbit coupling

    Science.gov (United States)

    Hoi, Bui Dinh; Yarmohammadi, Mohsen; Kazzaz, Houshang Araghi

    2017-10-01

    We studied how the strain, induced exchange field and extrinsic Rashba spin-orbit coupling (RSOC) enhance the electronic band structure (EBS) and electronic heat capacity (EHC) of ferromagnetic silicene in presence of external electric field (EF) by using the Kane-Mele Hamiltonian, Dirac cone approximation and the Green's function approach. Particular attention is paid to investigate the EHC of spin-up and spin-down bands at Dirac K and K‧ points. We have varied the EF, strain, exchange field and RSOC to tune the energy of inter-band transitions and consequently EHC, leading to very promising features for future applications. Evaluation of EF exhibits three phases: Topological insulator (TI), valley-spin polarized metal (VSPM) and band insulator (BI) at given aforementioned parameters. As a new finding, we have found a quantum anomalous Hall phase in BI regime at strong RSOCs. Interestingly, the effective mass of carriers changes with strain, resulting in EHC behaviors. Here, exchange field has the same behavior with EF. Finally, we have confirmed the reported and expected symmetry results for both Dirac points and spins with the study of valley-dependent EHC.

  18. High energy resolution and first time-dependent positron annihilation induced Auger electron spectroscopty

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Jakob

    2010-04-03

    It was the aim of this thesis to improve the existing positron annihilation induced Auger spectrometer at the highly intense positron source NEPOMUC (NEutron induced POsitron source MUniCh) in several ways: Firstly, the measurement time for a single spectrum should be reduced from typically 12 h to roughly 1 h or even less. Secondly, the energy resolution, which amounted to {delta}E/E{approx}10%, should be increased by at least one order of magnitude in order to make high resolution positron annihilation induced Auger spectroscopy (PAES)-measurements of Auger transitions possible and thus deliver more information about the nature of the Auger process. In order to achieve these objectives, the PAES spectrometer was equipped with a new electron energy analyzer. For its ideal operation all other components of the Auger analysis chamber had to be adapted. Particularly the sample manipulation and the positron beam guidance had to be renewed. Simulations with SIMION {sup registered} ensured the optimal positron lens parameters. After the adjustment of the new analyzer and its components, first measurements illustrated the improved performance of the PAES setup: Firstly, the measurement time for short overview measurements was reduced from 3 h to 420 s. The measurement time for more detailed Auger spectra was shortened from 12 h to 80 min. Secondly, even with the reduced measurement time, the signal to noise ratio was also enhanced by one order of magnitude. Finally, the energy resolution was improved to {delta}E/E < 1. The exceptional surface sensitivity and elemental selectivity of PAES was demonstrated in measurements of Pd and Fe, both coated with Cu layers of varying thickness. PAES showed that with 0.96 monolayer of Cu on Fe, more than 55% of the detected Auger electrons stem from Cu. In the case of the Cu coated Pd sample 0.96 monolayer of Cu resulted in a Cu Auger fraction of more than 30% with PAES and less than 5% with electron induced Auger spectroscopy

  19. Strong-field absorption and emission of radiation in two-electron systems calculated with time-dependent natural orbitals

    CERN Document Server

    Brics, M; Bauer, D

    2016-01-01

    Recently introduced time-dependent renormalized-natural-orbital theory (TDRNOT) is based on the equations of motion for the so-called natural orbitals, i.e., the eigenfunctions of the one-body reduced density matrix. Exact TDRNOT can be formulated for any time-dependent two-electron system in either spin configuration. In this paper, the method is tested against high-order harmonic generation (HHG) and Fano profiles in absorption spectra with the help of a numerically exactly solvable one-dimensional model He atom, starting from the spin-singlet ground state. Such benchmarks are challenging because Fano profiles originate from transitions involving autoionizing states, and HHG is a strong-field phenomenon well beyond linear response. TDRNOT with just one natural orbital per spin in the helium spin-singlet case is equivalent to time-dependent Hartree-Fock or time-dependent density functional theory (TDDFT) in exact exchange-only approximation. It is not unexpected that TDDFT fails in reproducing Fano profiles ...

  20. Electronic Structure of Ligated CdSe Clusters: Dependence on DFT Methodology

    Energy Technology Data Exchange (ETDEWEB)

    Albert, VV; Ivanov, SA; Tretiak, S; Kilina, SV

    2011-07-07

    Simulations of ligated semiconductor quantum dots (QDs) and their physical properties, such as morphologies, QD-ligand interactions, electronic structures, and optical transitions, are expected to be very sensitive to computational methodology. We utilize Density Functional Theory (DFT) and systematically study how the choice of density functional, atom-localized basis set, and a solvent affects the physical properties of the Cd{sub 33}Se{sub 33} cluster ligated with a trimethyl phosphine oxide ligand. We have found that qualitative performance of all exchange-correlation (XC) functionals is relatively similar in predicting strong QD-ligand binding energy ({approx}1 eV). Additionally, all functionals predict shorter Cd-Se bond lengths on the QD surface than in its core, revealing the nature and degree of QD surface reconstruction. For proper modeling of geometries and QD-ligand interactions, however, augmentation of even a moderately sized basis set with polarization functions (e.g., LANL2DZ* and 6-31G*) is very important. A polar solvent has very significant implications for the ligand binding energy, decreasing it to 0.2-0.5 eV. However, the solvent model has a minor effect on the optoelectronic properties, resulting in persistent blue shifts up to {approx}0.3 eV of the low-energy optical transitions. For obtaining reasonable energy gaps and optical transition energies, hybrid XC functionals augmented by a long-range Hartree-Fock orbital exchange have to be applied.

  1. Quantum mechanical electronic structure calculation reveals orientation dependence of hydrogen bond energy in proteins.

    Science.gov (United States)

    Mondal, Abhisek; Datta, Saumen

    2017-06-01

    Hydrogen bond plays a unique role in governing macromolecular interactions with exquisite specificity. These interactions govern the fundamental biological processes like protein folding, enzymatic catalysis, molecular recognition. Despite extensive research work, till date there is no proper report available about the hydrogen bond's energy surface with respect to its geometric parameters, directly derived from proteins. Herein, we have deciphered the potential energy landscape of hydrogen bond directly from the macromolecular coordinates obtained from Protein Data Bank using quantum mechanical electronic structure calculations. The findings unravel the hydrogen bonding energies of proteins in parametric space. These data can be used to understand the energies of such directional interactions involved in biological molecules. Quantitative characterization has also been performed using Shannon entropic calculations for atoms participating in hydrogen bond. Collectively, our results constitute an improved way of understanding hydrogen bond energies in case of proteins and complement the knowledge-based potential. Proteins 2017; 85:1046-1055. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  2. Liquid ionization chamber initial recombination dependence on LET for electrons and photons.

    Science.gov (United States)

    Johansson, Erik; Andersson, Jonas; Johansson, Lennart; Tölli, Heikki

    2013-06-21

    The possibility of indirect measurements of linear energy transfer (LET) with a liquid ionization chamber (LIC) has been investigated by studying initial recombination losses at different applied voltages. A linear fit is made to the voltage-signal curve and the intersection point of the fit and the voltage-axis is shown to correlate with LET. The LIC applied voltages were 100-700 V, which corresponds to electric field strengths between 0.3 and 2.0 MV m(-1). Several different photon and electron beams have been studied, and by using MCNPX™ the respective LET spectra have been determined. The beam qualities in this study were found to have a fluence averaged LET between 0.17 and 1.67 keV µm(-1) and a corresponding dose averaged LET between 0.97 and 4.62 keV µm(-1). For the experimental data in this study the linear fit method yields consistent results with respect to Monte Carlo simulated LET values. A calibration curve for LET determination is provided for the LIC used in the present work.

  3. Time dependence of electron and positron fluxes measured with the AMS-02 spectrometer

    CERN Document Server

    Graziani, Maura; Duranti, Matteo

    The electrons (e-) and positrons (e+) are a rare component of Cosmic Rays (CRs) since they constitute respectively only a 1% and 0.1% of cosmic radiation. However, the correct detection of e+- covers a great importance in the astrophysics field since, unlike the hadronic component, they are subjected to strong energy losses through the interaction with Interstellar Medium. As consequence e with energies above GeV that reach the Earth are galactic, with the source inside Kpc and through the study of their primary spectra it is possible to probe the local interstellar medium (LIS) and to indirectly detect new possible sources like pulsar or dark matter. However, these spectra, when measured near Earth, are significantly affected by the solar activity and we have the so-called solar modulation of CRs (SM). The solar activity has a cycle which period is ~11 years, during which it increases reaching a maximum and then decreases again. The intensity of cosmic ray radiation is correlated (or rather anticorrelated...

  4. Temperature-Dependent Electron Transport in Si and Ge Nanoparticle Photovoltaics

    Science.gov (United States)

    Padilla, Derek; Church, Carena; Muthuswamy, Elayaraja; Kauzlarich, Susan; Carter, Sue

    2013-03-01

    We have studied both Si and Ge nanoparticle-based photovoltaic (PV) devices fabricated in a layered structure via spin-coating of the colloidal Si or Ge solution. With the low toxicity and high abundance of these group IV elements, combined with the relatively low costs of manufacturing via solution deposition, large-scale device processing offers high dollar-per-Watt opportunities as efficiencies continue to improve. To that end, we previously reported temperature effects of solution-processed PbS quantum dot (QD) PVs, wherein the capping ligand's thermal properties were shown to have strong effects on device performance. Here we show similar ligand effects in group IV QD devices. Current-voltage (I-V) measurements at temperatures from 100 to 360 K under dark conditions were fit to the ideal diode equation revealing the electron transport mechanism, with fit parameters matching transport models. The illuminated I-V data provide insight into each device's built-in potential, carrier mobility, and activation energy. In addition, modulating the illumination intensity gives the ideality factors of the solar cells. We show how these variations with temperature and light-intensity can be used to increase device performance for future studies.

  5. A backward Monte-Carlo method for time-dependent runaway electron simulations

    Science.gov (United States)

    Zhang, Guannan; del-Castillo-Negrete, Diego

    2017-09-01

    Kinetic descriptions of runaway electrons (REs) are usually based on Fokker-Planck models that determine the probability distribution function of REs in 2-dimensional momentum space. Despite the simplification involved, the Fokker-Planck equation can rarely be solved analytically and direct numerical approaches [e.g., continuum and particle-based Monte Carlo (MC)] can be time consuming, especially in the computation of asymptotic-type observables including the runaway probability, the slowing-down and runaway mean times, and the energy limit probability. Here, we present a novel backward MC approach to these problems based on backward stochastic differential equations that describe the dynamics of the runaway probability by means of the Feynman-Kac theory. The key ingredient of the backward MC algorithm is to place all the particles in a runaway state and simulate them backward from the terminal time to the initial time. As such, our approach can provide much faster convergence than direct MC methods (by significantly reducing the number of particles required to achieve a prescribed accuracy) while at the same time maintaining the advantages of particle-based methods (compared to continuum approaches). The proposed algorithm is unconditionally stable and can be parallelized as easy as the direct MC method, and its extension to dimensions higher than two is straightforward, thus paving the way for conducting large-scale RE simulation.

  6. Temperature dependent electron paramagnetic resonance (EPR) of SrZrO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Santosh K., E-mail: santufrnd@gmail.com [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Pathak, Nimai [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Ghosh, P.S. [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Rajeshwari, B. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Natarajan, V. [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Kadam, R.M. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India)

    2015-10-01

    SrZrO{sub 3} (SZO), a distorted perovskite was synthesized using gel-combustion route employing citric acid as a fuel and ammonium nitrate as oxidizer followed by characterization using X-ray diffraction (XRD) and electron paramagnetic resonance (EPR). Purity of the sample is confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis. Broadening and shift of the resonance field position in EPR spectrum to the lower field was observed as the temperature is lowered; which is the characteristic of ferromagnetic resonance spectra. The value of Curie–Weiss temperature obtained for SZO particles is 8.7 K. The positive sign of the Curie–Weiss temperature indicates that some of the spins are ferromagnetically coupled in this sample. Theoretical investigation using density functional theory (DFT) calculation revealed that Vacancy at zirconium site contribute maximum to the magnetic moment. - Highlights: • Gel-combustion synthesis of SrZrO{sub 3} perovskite at relatively low temperature. • EPR evidence for ferromagnetic resonance. • Positive sign of the Curie–Weiss temperature ~8.7 K. • Defect induced magnetism- Zirconium vacancy induces maximum magnetic moment.

  7. Strain-dependent electronic and magnetic of Co-doped monolayer of WSe2

    Science.gov (United States)

    Wu, Ninghua; Zhao, Xu; Wang, Tianxing

    2016-10-01

    We perform first-principles calculation to investigate electronic and magnetic properties of Co-doped WSe2 monolayer with strains from -10% to 10%. We find that Co can induce magnetic moment about 0.894 μB, the Co-doped WSe2 monolayer is a magnetic semiconductor material without strain. The doped system shows half-metallic properties under tensile strain, and the largest half-metal gap is 0.147 eV at 8% strain. The magnetic moment (0.894 μB) increases slightly from 0% to 6%, and jumps into about 3 μB at 8% and 10%, which presents high-spin state configurations. When we applied compressive strain, the doped system shows a half-metallic feature at -2% strain, and the magnetic moment jumps into 1.623 μB at -4% strain, almost two times as the original moment 0.894 μB at 0% strain. The magnetic moment vanishes at -7% strain. The Co-doped WSe2 can endure strain from -6% to 10%. Strain changes the redistribution of charges and magnetic moment. Our calculation results show that the Co-doped WSe2 monolayer can transform from magnetic semiconductor to half-metallic material under strain.

  8. A Chinese resource curse? The human rights effects of oil export dependence on China versus the United States

    NARCIS (Netherlands)

    Bader, J.; Daxecker, U.

    2015-01-01

    Critiques of China’s ‘oil diplomacy’ center on its alleged disregard for transparency and human rights, yet such claims ignore that the problematic relationship between resource extraction and human rights precedes Chinese market entry. This article explores whether human rights implications are mor

  9. A Chinese resource curse? The human rights effects of oil export dependence on China versus the United States

    NARCIS (Netherlands)

    Bader, J.; Daxecker, U.

    2015-01-01

    Critiques of China’s ‘oil diplomacy’ center on its alleged disregard for transparency and human rights, yet such claims ignore that the problematic relationship between resource extraction and human rights precedes Chinese market entry. This article explores whether human rights implications are

  10. United Nations Office on Drugs and Crime International Network of Drug Dependence Treatment and Rehabilitation Resource Centres: Treatnet

    Science.gov (United States)

    Tomas-Rossello, Juana; Rawson, Richard A.; Zarza, Maria J.; Bellows, Anne; Busse, Anja; Saenz, Elizabeth; Freese, Thomas; Shawkey, Mansour; Carise, Deni; Ali, Robert; Ling, Walter

    2010-01-01

    Key to the dissemination of evidence-based addiction treatments is the exchange of experiences and mutual support among treatment practitioners, as well as the availability of accurate addiction training materials and effective trainers. To address the shortage of such resources, the United Nations Office on Drugs and Crime (UNODC) created…

  11. Pursuing Financial Stability: A Resource Dependence Perspective on Interactions between Pro-Vice Chancellors in a Network of Universities

    Science.gov (United States)

    Pilbeam, Colin

    2012-01-01

    In resource-constrained environments universities increasingly must interact collaboratively and competitively to ensure financial stability. Such interactions are supported by the actions of senior university managers. This study investigated the extent and purpose of the interconnections between members of two groups of pro-vice chancellors…

  12. Splitting of the neutral mechanical plane depends on the length of the multi-layer structure of flexible electronics.

    Science.gov (United States)

    Li, Shuang; Su, Yewang; Li, Rui

    2016-06-01

    Multi-layer structures with soft (compliant) interlayers have been widely used in flexible electronics and photonics as an effective design for reducing interactions among the hard (stiff) layers and thus avoiding the premature failure of an entire device. The analytic model for bending of such a structure has not been well established due to its complex mechanical behaviour. Here, we present a rational analytic model, without any parameter fitting, to study the bending of a multi-layer structure on a cylinder, which is often regarded as an important approach to mechanical reliability testing of flexible electronics and photonics. For the first time, our model quantitatively reveals that, as the key for accurate strain control, the splitting of the neutral mechanical plane depends not only on the relative thickness of the middle layer, but also on the length-to-thickness ratio of the multi-layer structure. The model accurately captures the key quantities, including the axial strains in the top and bottom layers, the shear strain in the middle layer and the locations of the neutral mechanical planes of the top and bottom layers. The effects of the length of the multi-layer and the thickness of the middle layer are elaborated. This work is very useful for the design of multi-layer structure-based flexible electronics and photonics.

  13. k - dependent Jeff=1/2 band splitting and the electron-hole asymmetry in SrIrO3

    Science.gov (United States)

    Singh, Vijeta; Pulikkotil, J. J.

    2017-02-01

    The Ir ion in Srn+1 IrnO 3 n + 1 series of compounds is octahedrally coordinated. However, unlike Sr2IrO4 (n=1) and Sr3Ir2O7 (n=2) which are insulating due to spin-orbit induced Jeff splitting of the t2g bands, SrIrO3 (n= ∞) is conducting. To explore whether such a splitting is relevant in SrIrO3, and if so to what extent, we investigate the electronic structure of orthorhombic SrIrO3 using density functional theory. Calculations reveal that the crystal field split Ir t2 g bands in SrIrO3 are indeed split into Jeff=3/2 and and Jeff=1/2 states. However, the splitting is found to be strongly k - dependent with its magnitude determined by the Ir - O orbital hybridization. Besides, we find that the spin-orbit induced pseudo-gap, into which the Fermi energy is positioned, is composed of both light electron-like and heavy hole-like bands. These features in the band structure of SrIrO3 suggest that variations in the carrier concentration control the electronic transport properties in SrIrO3, which is consistent with the experiments.

  14. ARTICLES: A Surface Femtosecond Two-Photon Photoemission Spectrometer for Excited Electron Dynamics and Time-Dependent Photochemical Kinetics

    Science.gov (United States)

    Ren, Ze-feng; Zhou, Chuan-yao; Ma, Zhi-bo; Xiao, Chun-lei; Mao, Xin-chun; Dai, Dong-xu; LaRue, Jerry; Cooper, Russell; Wodtke, Alec M.; Yang, Xue-ming

    2010-06-01

    A surface femtosecond two-photon photoemission (2PPE) spectrometer devoted to the study of ultrafast excited electron dynamics and photochemical kinetics on metal and metal oxide surfaces has been constructed. Low energy photoelectrons are measured using a hemispherical electron energy analyzer with an imaging detector that allows us to detect the energy and the angular distributions of the photoelectrons simultaneously. A Mach-Zehnder interferometer was built for the time-resolved 2PPE (TR-2PPE) measurement to study ultrafast surface excited electron dynamics, which was demonstrated on the Cu(111) surface. A scheme for measuring time-dependent 2PPE (TD-2PPE) spectra has also been developed for studies of surface photochemistry. This technique has been applied to a preliminary study on the photochemical kinetics on ethanol/TiO2(110). We have also shown that the ultrafast dynamics of photoinduced surface excited resonances can be investigated in a reliable way by combining the TR-2PPE and TD-2PPE techniques.

  15. Splitting of the neutral mechanical plane depends on the length of the multi-layer structure of flexible electronics

    Science.gov (United States)

    Li, Shuang; Su, Yewang; Li, Rui

    2016-06-01

    Multi-layer structures with soft (compliant) interlayers have been widely used in flexible electronics and photonics as an effective design for reducing interactions among the hard (stiff) layers and thus avoiding the premature failure of an entire device. The analytic model for bending of such a structure has not been well established due to its complex mechanical behaviour. Here, we present a rational analytic model, without any parameter fitting, to study the bending of a multi-layer structure on a cylinder, which is often regarded as an important approach to mechanical reliability testing of flexible electronics and photonics. For the first time, our model quantitatively reveals that, as the key for accurate strain control, the splitting of the neutral mechanical plane depends not only on the relative thickness of the middle layer, but also on the length-to-thickness ratio of the multi-layer structure. The model accurately captures the key quantities, including the axial strains in the top and bottom layers, the shear strain in the middle layer and the locations of the neutral mechanical planes of the top and bottom layers. The effects of the length of the multi-layer and the thickness of the middle layer are elaborated. This work is very useful for the design of multi-layer structure-based flexible electronics and photonics.

  16. Electron exchange in conformationally restricted donor-spacer-acceptor dyads: angle dependence and involvement of upper-lying excited States.

    Science.gov (United States)

    Benniston, Andrew C; Harriman, Anthony; Li, Peiyi; Patel, Pritesh V; Sams, Craig A

    2008-01-01

    The rate constant for triplet energy transfer (k(TET)) has been measured in fluid solution for a series of mixed-metal Ru-Os bis(2,2':6',2''-terpyridine) complexes built around a tethered biphenyl-based spacer group. The length of the tether controls the central torsion angle for the spacer, which can be varied systematically from 37 to 130 degrees . At low temperature, but still in fluid solution, the spacer adopts the lowest-energy conformation and k(TET) shows a clear correlation with the torsion angle. A similar relationship holds for the inverse quantum yield for emission from the Ru-terpy donor. Triplet energy transfer is more strongly activated at higher temperature and the kinetic data require analysis in terms of two separate processes. The more weakly activated step involves electron exchange from the first-excited triplet state on the Ru-terpy donor and the size of the activation barrier matches well with that calculated from spectroscopic properties. The pre-exponential factor derived for this process correlates remarkably well with the torsion angle and there is a large disparity in electronic coupling through pi and sigma orbitals on the spacer. The more strongly activated step is attributed to electron exchange from an upper-lying triplet state localized on the Ru-terpy donor. Here, the pre-exponential factor is larger but shows the same dependence on the geometry of the spacer. Strangely, the difference in coupling through pi and sigma orbitals is much less pronounced. Despite internal flexibility around the spacer, k(TET) shows a marked dependence on the torsion angle computed for the lowest-energy conformation.

  17. The Use and Maintenance of University Library Electronic Resources%浅议大学图书馆电子资源的利用与维护

    Institute of Scientific and Technical Information of China (English)

    马鹏飞; 熊豫玲

    2011-01-01

    随着科学技术的飞速发展,高新信息技术的广泛应用,大学图书馆的工作内容和方法也面临新的挑战,为了使用户更好的利用大学图书馆的电子资源,提高电子资源利用率,实现大学图书馆数字化,本文主要从电子资源的利用和维护方面进行探讨。%With the rapid development of science and technology,the extensive application of high-tech information technology, University of content and methods of library work is also facing new challenges in order to make better use of university library users to electronic resources,improve the utilization of electronic resources to achieve the University Library digital,paper, from the use of electronic resources and maintenance were discussed.

  18. Ion Bernstein instability dependence on the proton-to-electron mass ratio: Linear dispersion theory

    Science.gov (United States)

    Min, Kyungguk; Liu, Kaijun

    2016-07-01

    Fast magnetosonic waves, which have as their source ion Bernstein instabilities driven by tenuous ring-like proton velocity distributions, are frequently observed in the inner magnetosphere. One major difficulty in the simulation of these waves is that they are excited in a wide frequency range with discrete harmonic nature and require time-consuming computations. To overcome this difficulty, recent simulation studies assumed a reduced proton-to-electron mass ratio, mp/me, and a reduced light-to-Alfvén speed ratio, c/vA, to reduce the number of unstable modes and, therefore, computational costs. Although these studies argued that the physics of wave-particle interactions would essentially remain the same, detailed investigation of the effect of this reduced system on the excited waves has not been done. In this study, we investigate how the complex frequency, ω = ωr+iγ, of the ion Bernstein modes varies with mp/me for a sufficiently large c/vA (such that ωpe2/Ωe2≡(me/mp)(c/vA)2≫1) using linear dispersion theory assuming two different types of energetic proton velocity distributions, namely, ring and shell. The results show that low- and high-frequency harmonic modes respond differently to the change of mp/me. For the low harmonic modes (i.e., ωr˜Ωp), both ωr/Ωp and γ/Ωp are roughly independent of mp/me, where Ωp is the proton cyclotron frequency. For the high harmonic modes (i.e., Ωp≪ωr≲ωlh, where ωlh is the lower hybrid frequency), γ/ωlh (at fixed ωr/ωlh) stays independent of mp/me when the parallel wave number, k∥, is sufficiently large and becomes inversely proportional to (mp/me)1/4 when k∥ goes to zero. On the other hand, the frequency range of the unstable modes normalized to ωlh remains independent of mp/me, regardless of k∥.

  19. The electron transfer flavoprotein fixABCX gene products from Azospirillum brasilense show a NifA-dependent promoter regulation.

    Science.gov (United States)

    Sperotto, Raul Antonio; Gross, Jeferson; Vedoy, Cleber; Passaglia, Luciane Maria Pereira; Schrank, Irene Silveira

    2004-10-01

    The complete nucleotide sequence of the A. brasilense fixA, fixB, fixC, and fixX genes is reported here. Sequence similarities between the protein sequences deduced from fixABCX genes and many electron transfer flavoproteins (ETFs) have been noted. Comparison of the amino acid sequences of both subunits of ETF with the A. brasilense fixA and fixB gene products exhibits an identity of 30%. The amino acid sequence of the other two genes, fixC and fixX, revealed similarity with the membrane-bound electron transfer flavoprotein ubiquinone oxidoreductase (ETF-QO). Using site-directed mutagenesis, mutations were introduced in the fixA promoter element of the A. brasilense fixABCX operon and chimeric p fixA-lacZ reporter gene fusions were constructed. The activation of the fixA promoter of A. brasilense is dependent upon the presence of the NifA protein being approximately 7 times less active than the A. brasilense nifH promoter. These results indicate that NifA from Klebsiella pneumoniae activates the fix promoter of A. brasilense and provide further evidence in support of the regulatory model of NifA activation in A. brasilense. Although no specific function has been assigned to the fixABCX gene products they are apparently required for symbiotic nitrogen fixation. An electron-transferring capacity in the nitrogen fixation pathway has been suggested for the fix gene products based on sequence homologies to the ETFs and ETF-QO proteins and by the absence of orthologous electron transfer proteins NifJ and NifF in A. brasilense.

  20. Mineral resources

    Digital Repository Service at National Institute of Oceanography (India)

    Valsangkar, A.B.

    (placers), biogenous (ooze, limestone) or chemogenous (phosphorites and polymetallic nodules) type. In recent years, hydrothermal deposits, cobalt crust and methane gas hydrates are considered as frontier resources. Their distribution depends upon proximity...

  1. Positive Perceptions of Access to Online Library Resources Correlates with Quality and Quantity of Scholarly Publications among Finnish Academics. A Review of: Vakkari, Pertti. “Perceived Influence of the Use of Electronic Information Resources on Scholarly Work and Publication Productivity.” Journal of the American Society for Information Science and Technology 59.4 (Feb. 15, 2008: 602-12.

    Directory of Open Access Journals (Sweden)

    Scott Marsalis

    2008-12-01

    Full Text Available Objective – To investigate the relationship between academics’ use of library electronic resources and their opinions regarding how these resources have impacted their work, and to investigate the association between this perceived influence and publication productivity during the previous two years.Design – Two specific questions added to an annual online user-survey questionnaire; additional data mined from surveySetting – Twenty-two Finnish Universities served by FinELib, the Finnish Electronic Library.Subjects – Seven hundred and sixty seven academic staff and full-time doctoral students.Methods – A questionnaire was posted in April 2007 on FinELib’s homepage and advertised on each university library’s mainpage, and focused on respondents’ experience in the previous two years. Participants selected answers either from a list of category choices, or, when measuring perceptions, by rating agreement with statements along a four-point scale. Controlled variables measured were the respondents’ academic position, their discipline, membership in a research group, whether their literature use was discipline-specific or interdisciplinary, and their perception of the availability online of the relevant core literature. The independent variable measured was the scholars’ perception of the impact of the use of electronic library resources on their work. The dependent variable measured was the scholars’ self-reported publications in the two years preceding the survey.Main Results – Participants reported a positive impact on the efficiency of their work, most strongly in areas of ease of access, with lesser impacts in the range of materials available to them and the ease with which they can keep up-to-date in their field. To a lesser extent, the scholars perceived a positive impact on the quality of their work. Upon analysis, the study found that access to online library resources improved scholars’ work by the interconnected

  2. The formation of the angular dependences of the inelastically scattered electrons by their quantum transport near the surface of a solid

    Directory of Open Access Journals (Sweden)

    Vadim V. Korablev

    2016-06-01

    Full Text Available Features of the formation of angular dependences of electrons emitted from a disordered solid and experiencing inelastic scattering have been considered. Such fine details of the dependences are formed by the processes of quantum transport of emitted particles. We took the cases of two-particle and multi-particle inelastic processes. Qualitative and quantitative assessments of the relative contributions of different groups of particles were carried out. The effects related to quantum electron transport were shown to be generally more pronounced in the case of registration of electrons generated inside the solid in the inelastic scattering of particles of the primary beam. This is true both for the electrons generated by ionization processes and Auger electrons. The obtained results point to the possibility of using this effect in applied electron spectroscopy.

  3. EU’S DEPENDENCE ON RUSSIAN ENERGY RESOURCES AND THE NEW ALTERNATIVE OF OIL AND GAS EXPORTING COUNTRIES

    Directory of Open Access Journals (Sweden)

    Sabina STRIMBOVSCHI

    2014-10-01

    Full Text Available In this paper the author tackles the EU-Russia energy relations from the beginning of their cooperation in this field until now. Likewise, the disputes that emerged, along the time, at the EU’s border and vicinity are presented and analyzed, by trying to explain how Russia uses its energy resources as a tool of hard power in its foreign policy. However, taking into consideration the previous gas crises and the policy of Russia toward the Eastern Partnership (EaP states that aim to follow Euro-Atlantic integration, the author treats and highlights the EU’s strategic interest to establish new partnerships with other energy exporting states. In this regard, one of the EaP states that present a huge interest for the EU in order to develop a bilateral energy relation is Azerbaijan, a Caspian state with great oil and gas resources.

  4. Electronic and Optical Properties of Small Hydrogenated Silicon Quantum Dots Using Time-Dependent Density Functional Theory

    Directory of Open Access Journals (Sweden)

    Muhammad Mus-’ab Anas

    2015-01-01

    Full Text Available This paper presents a systematic study of the absorption spectrum of various sizes of small hydrogenated silicon quantum dots of quasi-spherical symmetry using the time-dependent density functional theory (TDDFT. In this study, real-time and real-space implementation of TDDFT involving full propagation of the time-dependent Kohn-Sham equations were used. The experimental results for SiH4 and Si5H12 showed good agreement with other earlier calculations and experimental data. Then these calculations were extended to study larger hydrogenated silicon quantum dots with diameter up to 1.6 nm. It was found that, for small quantum dots, the absorption spectrum is atomic-like while, for relatively larger (1.6 nm structure, it shows bulk-like behavior with continuous plateau with noticeable peak. This paper also studied the absorption coefficient of silicon quantum dots as a function of their size. Precisely, the dependence of dot size on the absorption threshold is elucidated. It was found that the silicon quantum dots exhibit direct transition of electron from HOMO to LUMO states; hence this theoretical contribution can be very valuable in discerning the microscopic processes for the future realization of optoelectronic devices.

  5. Barriers to electronic access and delivery of educational information in resource constrained public schools: a case of Greater Tubatse Municipality

    CSIR Research Space (South Africa)

    Pholotho, T

    2016-05-01

    Full Text Available Information and Communication Technologies (ICTs) are capable of expanding access to quality education, educational resources and provide teachers with new skills. Nevertheless, a majority of rural public schools have limited ICTs, mainly due...

  6. Electronic Grey Literature in Accelerator Science and Its Allied Subjects : Selected Web Resources for Scientists and Engineers

    CERN Document Server

    Rajendiran, P

    2006-01-01

    Grey literature Web resources in the field of accelerator science and its allied subjects are collected for the scientists and engineers of RRCAT (Raja Ramanna Centre for Advanced Technology). For definition purposes the different types of grey literature are described. The Web resources collected and compiled in this article (with an overview and link for each) specifically focus on technical reports, preprints or e-prints, which meet the main information needs of RRCAT users.

  7. 电子资源许可使用的发展与创新%The Development and Innovation of the Use of the Electronic Resource License

    Institute of Scientific and Technical Information of China (English)

    王军

    2012-01-01

      电子资源许可使用在我国发展时间较短,在其建立过程中还存在许可定价、购买模式、馆际互借以及电子资源的长期保存许可方式等难题。电子资源许可使用的发展与创新,需要根据用户需求制定发展战略,建立图书馆的读者监督管理制度和数字化资源服务制度,规范文献编目制度等,以提高电子信息资源与图书馆信息资源的使用效果和广泛的使用需求%  It's been a short time since the use of electronic resource licenses has developed in China; in addition, many problems ap-pear in the establishment process in terms of license pricing, purchase pattern, inter-library loan and long-term preservation ways of electronic resources. In order to develop and innovate the use of the license, libraries should develop strategies in accordance with the users' needs, establish a reader supervision system and a digital resource service system, and normalize the document cataloging sys-tem to enhance the utilization effect and meet the extensive demand for electronic and library information resources.

  8. Near and Above Ionization Electronic Excitations with Non-Hermitian Real-Time Time-Dependent Density Functional Theory

    Energy Technology Data Exchange (ETDEWEB)

    Lopata, Kenneth A.; Govind, Niranjan

    2013-11-12

    We present a real-time time-dependent density functional theory (RT-TDDFT) prescription for capturing near and post-ionization excitations based on non-Hermitian von Neumann density matrix propagation with atom-centered basis sets, tuned range-separated DFT, and a phenomenological imaginary molecular orbital-based absorbing potential to mimic coupling to the continuum. The computed extreme ultraviolet absorption spectra for acetylene (C2H2), water (H2O), and Freon 12 (CF2Cl2) agree well with electron energy loss spectroscopy (EELS) data over the range 0 to 50 eV. The absorbing potential removes spurious high energy finite basis artifacts, yielding correct bound to bound transitions, metastable (autoionizing) resonance states, and consistent overall absorption shapes.

  9. Near and Above Ionization Electronic Excitations with Non-Hermitian Real-Time Time-Dependent Density Functional Theory.

    Science.gov (United States)

    Lopata, Kenneth; Govind, Niranjan

    2013-11-12

    We present a real-time time-dependent density functional theory (RT-TDDFT) prescription for capturing near and post-ionization excitations based on non-Hermitian von Neumann density matrix propagation with atom-centered basis sets, tuned range-separated DFT, and a phenomenological imaginary molecular orbital-based absorbing potential to mimic coupling to the continuum. The computed extreme ultraviolet absorption spectra for acetylene (C2H2), water (H2O), and Freon 12 (CF2Cl2) agree well with electron energy loss spectroscopy (EELS) data over the range of 0-50 eV. The absorbing potential removes spurious high-energy finite basis artifacts, yielding correct bound-to-bound transitions, metastable (autoionizing) resonance states, and consistent overall absorption shapes.

  10. Time-dependent density functional study of the electronic excited states of polycyclic aromatic hydrocarbon radical ions

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, So; Head-Gordon, Martin P; Szczepanski, Jan; Vala, Martin

    2003-06-19

    A uniform, comprehensive theoretical interpretation of spectroscopic data is presented for 53 radical ion species of polycyclic aromatic hydrocarbons (PAHs) with the aid of (Tamm–Dancoff) time-dependent density functional theory (TDDFT). TDDFT is capable of predicting the transition energies to the low-lying excited states of PAH ions with quantitative accuracy (the standard deviation from experimental results being less than 0.3 eV) and their intensity patterns qualitatively correctly. The accuracy is hardly affected by the sizes of PAH ions (azulene through dinaphthocoronene), the types of transitions (Koopmans or satellite transitions), the types of orbi-tals involved (π* ← π, π* ← σ, or σ* ← π transitions), the types of ions (cations or anions), or other geometrical or electronic perturbations (non-planarity, sp3 carbons, or heterocyclic or non-benzenoid rings).

  11. Space charge effect of the time-dependent ultrafast laser excited electron emission from a metal surface

    CERN Document Server

    Liu, Yangjie

    2013-01-01

    A model has been constructed to the study the transition of ultrafast laser excited electron emission from a metallic surface to the space charge limited (SCL) regime. By considering the time-dependent emission process by L. Wu et al. [Phys. Rev. B.78 224112 (2008)], we include the space charge effect which will affect the barrier at the emitting surface. At the high laser field, it is found that space charge effect cannot be ignored and the SCL current emission is reached. The threshold of the laser field to reach the SCL regime is determined. Our calculations agree well with particle-in-cell simulation results. This model is also compared with the classical short pulse SCL current model by A. Valfellset al. [Phys. Plasmas 9, 2377 (2002)].

  12. Three-Dimensional, Time-Dependent Simulation of Free-Electron Lasers with Planar, Helical, and Elliptical Undulators

    CERN Document Server

    Freund, H P; Grimminck, D L A G; Setija, I D; Falgari, P

    2016-01-01

    Free-electron lasers (FELs) have been built ranging in wavelength from long-wavelength oscillators using partial wave guiding through ultraviolet through hard x-ray that are either seeded or start from noise (SASE). In addition, FELs that produce different polarizations of the output radiation ranging from linear through elliptic to circular polarization are currently under study. In this paper, we develop a three-dimensional, time-dependent formulation that is capable of modeling this large variety of FEL configurations including different polarizations. We employ a modal expansion for the optical field, i.e., a Gaussian expansion with variable polarization for free-space propagation. This formulation uses the full Newton-Lorentz force equations to track the particles through the optical and magnetostatic fields. As a result, arbitrary three-dimensional representations for different undulator configurations are implemented, including planar, helical, and elliptical undulators. In particular, we present an an...

  13. Negotiating for Critical Resources.

    Science.gov (United States)

    Bartunek, Frank P.

    1994-01-01

    School districts dependent on outside resources must develop skills for securing educational resources, including competencies in collaborative, creative, and principled resource management. Constructive negotiations between local and provincial levels of government can improve relationships and support the development of collaborative…

  14. Longest-Wavelength Electronic Excitations of Linear Cyanines: The Role of Electron Delocalization and of Approximations in Time-Dependent Density Functional Theory.

    Science.gov (United States)

    Ii, Barry Moore; Autschbach, Jochen

    2013-11-12

    The lowest-energy/longest-wavelength electronic singlet excitation energies of linear cyanine dyes are examined, using time-dependent density functional theory (TDDFT) and selected wave function methods in comparison with literature data. Variations of the bond-length alternation obtained with different optimized structures produce small differences of the excitation energy in the limit of an infinite chain. Hybrid functionals with range-separated exchange are optimally 'tuned', which is shown to minimize the delocalization error (DE) in the cyanine π systems. Much unlike the case of charge-transfer excitations, small DEs are not strongly correlated with better performance. A representative cyanine is analyzed in detail. Compared with accurate benchmark data, TDDFT with 'pure' local functionals gives too high singlet excitation energies for all systems, but DFT-based ΔSCF calculations with a local functional severely underestimates the energies. TDDFT strongly overestimates the difference between singlet and triplet excitation energies. An analysis points to systematically much too small magnitudes of integrals from the DFT components of the exchange-correlation response kernel as the likely culprit. The findings support previous suggestions that the differential correlation energy between the ground and excited state is not correctly produced by TDDFT with most functionals.

  15. Electron dynamics in complex environments with real-time time dependent density functional theory in a QM-MM framework

    Energy Technology Data Exchange (ETDEWEB)

    Morzan, Uriel N.; Ramírez, Francisco F.; Scherlis, Damián A., E-mail: damian@qi.fcen.uba.ar, E-mail: mcgl@qb.ffyb.uba.ar [Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires (C1428EHA) (Argentina); Oviedo, M. Belén; Sánchez, Cristián G. [Departamento de Matemática y Física, Facultad de Ciencias Químicas, INFIQC, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba (Argentina); Lebrero, Mariano C. González, E-mail: damian@qi.fcen.uba.ar, E-mail: mcgl@qb.ffyb.uba.ar [Instituto de Química y Fisicoquímica Biológicas, IQUIFIB, CONICET (Argentina)

    2014-04-28

    This article presents a time dependent density functional theory (TDDFT) implementation to propagate the Kohn-Sham equations in real time, including the effects of a molecular environment through a Quantum-Mechanics Molecular-Mechanics (QM-MM) hamiltonian. The code delivers an all-electron description employing Gaussian basis functions, and incorporates the Amber force-field in the QM-MM treatment. The most expensive parts of the computation, comprising the commutators between the hamiltonian and the density matrix—required to propagate the electron dynamics—, and the evaluation of the exchange-correlation energy, were migrated to the CUDA platform to run on graphics processing units, which remarkably accelerates the performance of the code. The method was validated by reproducing linear-response TDDFT results for the absorption spectra of several molecular species. Two different schemes were tested to propagate the quantum dynamics: (i) a leap-frog Verlet algorithm, and (ii) the Magnus expansion to first-order. These two approaches were confronted, to find that the Magnus scheme is more efficient by a factor of six in small molecules. Interestingly, the presence of iron was found to seriously limitate the length of the integration time step, due to the high frequencies associated with the core-electrons. This highlights the importance of pseudopotentials to alleviate the cost of the propagation of the inner states when heavy nuclei are present. Finally, the methodology was applied to investigate the shifts induced by the chemical environment on the most intense UV absorption bands of two model systems of general relevance: the formamide molecule in water solution, and the carboxy-heme group in Flavohemoglobin. In both cases, shifts of several nanometers are observed, consistently with the available experimental data.

  16. Electron dynamics in complex environments with real-time time dependent density functional theory in a QM-MM framework.

    Science.gov (United States)

    Morzan, Uriel N; Ramírez, Francisco F; Oviedo, M Belén; Sánchez, Cristián G; Scherlis, Damián A; Lebrero, Mariano C González

    2014-04-28

    This article presents a time dependent density functional theory (TDDFT) implementation to propagate the Kohn-Sham equations in real time, including the effects of a molecular environment through a Quantum-Mechanics Molecular-Mechanics (QM-MM) hamiltonian. The code delivers an all-electron description employing Gaussian basis functions, and incorporates the Amber force-field in the QM-MM treatment. The most expensive parts of the computation, comprising the commutators between the hamiltonian and the density matrix-required to propagate the electron dynamics-, and the evaluation of the exchange-correlation energy, were migrated to the CUDA platform to run on graphics processing units, which remarkably accelerates the performance of the code. The method was validated by reproducing linear-response TDDFT results for the absorption spectra of several molecular species. Two different schemes were tested to propagate the quantum dynamics: (i) a leap-frog Verlet algorithm, and (ii) the Magnus expansion to first-order. These two approaches were confronted, to find that the Magnus scheme is more efficient by a factor of six in small molecules. Interestingly, the presence of iron was found to seriously limitate the length of the integration time step, due to the high frequencies associated with the core-electrons. This highlights the importance of pseudopotentials to alleviate the cost of the propagation of the inner states when heavy nuclei are present. Finally, the methodology was applied to investigate the shifts induced by the chemical environment on the most intense UV absorption bands of two model systems of general relevance: the formamide molecule in water solution, and the carboxy-heme group in Flavohemoglobin. In both cases, shifts of several nanometers are observed, consistently with the available experimental data.

  17. Modeling Fast Electron Dynamics with Real-Time Time-Dependent Density Functional Theory: Application to Small Molecules and Chromophores.

    Science.gov (United States)

    Lopata, Kenneth; Govind, Niranjan

    2011-05-10

    The response of matter to external fields forms the basis for a vast wealth of fundamental physical processes ranging from light harvesting to nanoscale electron transport. Accurately modeling ultrafast electron dynamics in excited systems thus offers unparalleled insight but requires an inherently nonlinear time-resolved approach. To this end, an efficient and massively parallel real-time real-space time-dependent density functional theory (RT-TDDFT) implementation in NWChem is presented. The implementation is first validated against linear-response TDDFT and experimental results for a series of molecules subjected to small electric field perturbations. Second, nonlinear excitation of green fluorescent protein is studied, which shows a blue-shift in the spectrum with increasing perturbation, as well as a saturation in absorption. Next, the charge dynamics of optically excited zinc porphyrin is presented in real time and real space, with relevance to charge injection in photovoltaic devices. Finally, intermolecular excitation in an adenine-thymine base pair is studied using the BNL range separated functional [ Baer , R. ; Neuhauser , D. Phys. Rev. Lett. 2005 , 94 , 043002 ], demonstrating the utility of a real-time approach in capturing charge transfer processes.

  18. Substrate Dependent Ad-Atom Migration on Graphene and the Impact on Electron-Beam Sculpting Functional Nanopores.

    Science.gov (United States)

    Freedman, Kevin J; Goyal, Gaurav; Ahn, Chi Won; Kim, Min Jun

    2017-05-10

    The use of atomically thin graphene for molecular sensing has attracted tremendous attention over the years and, in some instances, could displace the use of classical thin films. For nanopore sensing, graphene must be suspended over an aperture so that a single pore can be formed in the free-standing region. Nanopores are typically drilled using an electron beam (e-beam) which is tightly focused until a desired pore size is obtained. E-beam sculpting of graphene however is not just dependent on the ability to displace atoms but also the ability to hinder the migration of ad-atoms on the surface of graphene. Using relatively lower e-beam fluxes from a thermionic electron source, the C-atom knockout rate seems to be comparable to the rate of carbon ad-atom attraction and accumulation at the e-beam/graphene interface (i.e., Rknockout ≈ Raccumulation). Working at this unique regime has allowed the study of carbon ad-atom migration as well as the influence of various substrate materials on e-beam sculpting of graphene. We also show that this information was pivotal to fabricating functional graphene nanopores for studying DNA with increased spatial resolution which is attributed to atomically thin membranes.

  19. Concentration-dependent study of electronic and optical properties of c-Si and c-Si:H

    Energy Technology Data Exchange (ETDEWEB)

    Nunez-Gonzalez, R. [Departamento de Matematicas, Universidad de Sonora, C.P. 83000, Hermosillo, Sonora (Mexico); Posada-Amarillas, A. [Departamento de Investigacion en Fisica, Universidad de Sonora, Apdo. Postal 5-088 C.P. 83190, Hermosillo, Sonora (Mexico); Galvan, D.H.; Reyes-Serrato, A. [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Ensenada, B. C. (Mexico)

    2011-07-15

    Electronic and optical properties of crystalline silicon (c-Si) and hydrogen-doped crystalline silicon (c-Si:H) were calculated using the full-potential linearized augmented plane waves (FLAPWs) method, within the density functional theory (DFT), and the supercell method to model different hydrogen concentrations. Hydrogen was introduced in both bond-centered (BC) and tetrahedral (Td) interstitial sites to find out the most favorable configuration by searching for the lowest energy structure. The Td interstitial site yields the most stable and lowest energy structure. For several hydrogen concentrations we found that the effect of interstitial hydrogen is to introduce electronic states at the silicon band gap, turning it into a metallic system. Analysis of the calculated energy-loss function of doped silicon shows the existence of a plasmon peak at low energy of the loss spectrum, and the position of this plasmon peak is highly dependent on hydrogen concentration into silicon. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Size-dependent electron transfer from PbSe quantum dots to SnO2 monitored by picosecond Terahertz spectroscopy.

    Science.gov (United States)

    Cánovas, Enrique; Moll, Puck; Jensen, Søren A; Gao, Yunan; Houtepen, Arjan J; Siebbeles, Laurens D A; Kinge, Sachin; Bonn, M

    2011-12-14

    We report the direct and unambiguous determination of electron transfer rates and efficiencies from PbSe quantum dots (QDs) to mesoporous SnO2 films. We monitor the time-dependent electron density within the oxide with picosecond time resolution using Terahertz spectroscopy, following optical excitation of the QDs using a femtosecond laser pulse. QD-oxide electron transfer occurs with efficiencies of ∼2% in our samples under 800 nm pumping with a marked dependence on QD size, ranging from ∼100 ps injection times for the smallest, ∼2 nm diameter QDs, to ∼1 ns time scale for ∼7 nm QDs. The size-dependent electron transfer rates are modeled within the framework of Marcus theory and the implications of the results for device design are discussed.