The oxygen enhancement ratio for single- and double-strand breaks induced by tritium incorporated in DNA of cultured human T1 cells. Impact of the transmutation effect.

Science.gov (United States)

Tisljar-Lentulis, G; Henneberg, P; Feinendegen, L E; Commerford, S L

1983-04-01

The effect of oxygen, expressed as the oxygen enhancement ratio (OER), on the number of single-strand breaks (SSB) and double-strand breaks (DSB) induced in DNA by the radioactive decay of tritium was measured in human T1 cells whose DNA had been labeled with tritium at carbon atom number 6 of thymidine. Decays were accumulated in vivo under aerobic conditions at 0-1 degrees C and at -196 degrees C and in a nitrogen atmosphere at 0-1 degrees C. The number of SSB and DSB produced was analyzed by sucrose gradient centrifugation. For each tritium decay there were 0.25 DSB in cells exposed to air at 0-1 degrees C and 0.07 in cells kept under nitrogen, indicating an OER of 3.6, a value expected for such low-LET radiation. However, for each tritium decay there were 1.25 SSB in cells exposed to air at 0-1 degrees C and 0.76 in cells kept under nitrogen indicating an OER of only 1.7. The corresponding values for 60Co gamma radiation, expressed as SSB per 100 eV absorbed energy, were 4.5 and 1.0, giving an OER of 4.5. The low OER value found for SSB induced by tritium decay can be explained if 31% of the total SSB produced in air result from transmutation by a mechanism which does not produce DSB and is unaffected by oxygen.

A Framework to Integrate Public, Dynamic Metrics Into an OER Platform

Directory of Open Access Journals (Sweden)

Jaclyn Zetta Cohen

2014-04-01

Full Text Available The usage metrics for open educational resources (OER are often either hidden behind an authentication system or shared intermittently in static, aggregated format at the repository level. This paper discusses the first year of University of Michigan’s project to share its OER usage data dynamically, publicly, to synthesize it across different levels within the repository hierarchies, and to aggregate in a method inclusive of content hosted on third-party platforms. The authors analyze their user research with a target audience of faculty authors, multimedia specialists, librarians, and communications specialists. Next, they explore a stratified technical design that allows the dynamic sharing of metrics down to the level of individual resources. The authors conclude that this framework enables sustainable feedback to OER creators, helps to build positive relationships with creators of OER, and allows the institution to move toward sharing OER on a larger scale.

Establishing a Framework on OER Practices for ICT Competence of Disabled Citizens

Science.gov (United States)

Altinay, Zehra; Ossiannilsson, Ebba; Kalaç, Mustafa Ozhan; Basari, Gülsün; Aktepebasi, Ali; Altinay, Fahriye

2016-01-01

The research encapsulates the framework on potential contributions of OER practices for supporting the ICT competence for disabled adult learners in building equal opportunities within the society. The study underlined the developing OER policy and framework to focus on digital citizenship competency for disabled adult learners. OER practices can…

The VLAB OER Experience: Modeling Potential-Adopter Student Acceptance

Science.gov (United States)

Raman, Raghu; Achuthan, Krishnashree; Nedungadi, Prema; Diwakar, Shyam; Bose, Ranjan

2014-01-01

Virtual Labs (VLAB) is a multi-institutional Open Educational Resources (OER) initiative, exclusively focused on lab experiments for engineering education. This project envisages building a large OER repository, containing over 1650 virtual experiments mapped to the engineering curriculum. The introduction of VLAB is a paradigm shift in an…

Pedagogical Framing of OER--The Case of Language Teaching

Science.gov (United States)

Bradley, Linda; Vigmo, Sylvi

2016-01-01

This study investigates what characterises teachers' pedagogical design of OER [Open Educational Resources], and potential affordances and constraints in pedagogical design in an open education practice, when contributing to a Swedish repository Lektion.se. The teachers' framing of the OER shared on the repository included the analyses of a…

Operating Experience Review(OER) and development of Issues Tracking System(ITS) for Jordan Research and Training Reactor(JRTR)

International Nuclear Information System (INIS)

Kim, Yong Jun; Lee, Hyun Chul

2011-01-01

The operation of the Jordan Research and Training Reactor which Korean consortium designs will start in March 2015. Though the power level of JRTR is different from the one of HANARO, a Korean research reactor, experience and expertise gained from the successful operation of the multipurpose research reactor, HANARO, would be applied for the design of JRTR because the basic operation principles of two reactors are almost same. From the point of human factors view, Operating Experience Review (OER) has the accurate purpose of reflecting accumulated knowledge to a new design and this activity are required to perform in the beginning stage of the control room designs in nuclear facilities. OER is to identify human factors engineering (HFE) issues related to safety. The issues from operating experience provide a basis for improving the plant design in a timely way. Identified issues are reported to an issues tracking system (ITS) so as to manage and resolve issues. HFE related safety issues are to be extracted from OER. The purpose of this paper is to present the scope and methods of OER for the JRTR design. In addition, a new ITS is proposed. The ITS is effective for issue management and has simplified states for issue development and small numbers of steps for issue control

Aktuelles aus der "Fallambulanz Urheberrecht" der OER Community

Directory of Open Access Journals (Sweden)

Angelika Güttl-Strahlhofer

2014-12-01

Full Text Available Im Sommersemester 2014 öffnete die Fallambulanz Urheberrecht der OER Community (Open Educational Resources der Virtuellen Pädagogischen Hochschule (VPH ihre Pforten und behandelte – von LehrerInnen eingelieferte – "PatientInnen" ... Die OER Community wird auch 2015 für alle LehrerInnen offen sein und ist dazu da, die Herausforderungen des Urheberrechts im LehrerInnenberuf wahrzunehmen und gemeinschaftlich Lösungswege zu erarbeiten. Es folgt eine kurze Zusammenfassung der wichtigsten Erkenntnisse der einzelnen Fälle. Für die ausführlicheren Fallbeschreibungen siehe http://www.virtuelle-ph.at/mod/page/view.php?id=50897 oder auch den Diskussionsverlauf im Forum. Neben den Fällen sind noch zwei Werkstattberichte (Bilder-/Musikschwerpunkt und eine OER-Basisinformation ("Tücken freier Bilder" als Ergebnisse der Lernakitvitäten im Sommersemester 2014 beigefügt.

The Tidewater Z-Degree and the INTRO Model for Sustaining OER Adoption

Science.gov (United States)

Wiley, David; Williams, Linda; DeMarte, Daniel; Hilton, John

2016-01-01

A growing body of research confirms the financial and academic benefits that accrue to students whose faculty adopt open educational resources, or OER. While there are no content licensing costs associated with using OER, there are several real costs that must be incurred by an institution that chooses to support its faculty in adopting OER. The…

Policy Recommendations : Enhancement of Cultural and Linguistic Variety through OER

NARCIS (Netherlands)

Bijlsma, M.; Titlestad, Gard; Creelman, Alastair

2016-01-01

Kleinere talen (Engels: Lesser UsedLanguages, LUL) vormen het middelpunt van het LangOER-project. In het kader van LangOER gaat het bij zulke ‘kleinere talen’ om bedreigde talen, regionale en minderheidstalen (ca. 10% van de Europese bevolking) en kleine nationale talen. Open leermiddelen (Open

Librarians and OER: Cultivating a Community of Practice to Be More Effective Advocates

Science.gov (United States)

Smith, Brenda; Lee, Leva

2017-01-01

As the costs of scholarly and educational publications skyrocket, open educational resources (OER) are becoming an important way to provide content and enhance the teaching and learning experience. Librarians have a key role to play in developing, advocating, and managing OER. For many librarians, however, championing OERs means adding an…

Institutional and technological barriers to the use of open educational resources (OERs) in physiology and medical education.

Science.gov (United States)

Hassall, Christopher; Lewis, David I

2017-03-01

Open educational resources (OERs) are becoming increasingly common as a tool in education, particularly in medical and biomedical education. However, three key barriers have been identified to their use: 1) lack of awareness of OERs, 2) lack of motivation to use OERs, and 3) lack of training in the use of OERs. Here, we explore these three barriers with teachers of medical and biomedical science to establish how best to enhance the use of OERs to improve pedagogical outcomes. An online survey was completed by 209 educators, many of whom (68.4%) reported using OERs in their teaching and almost all (99.5%) showing awareness of at least one OER. The results suggest that key problems that prevent educators from adopting OERs in their teaching include suitability for particular classes, time, and copyright. Most (81.8%) educators were somewhat, very, or extremely comfortable with OERs so there is no innate motivational barrier to adoption. A lack of training was reported by 13.9% of respondents, and 40% of respondents stated that there was little or no support from their institutions. OER users were no more comfortable with technology or better supported by departments but tended to be aware of a greater number of sources of OERs. Our study illustrates key opportunities for the expansion of OER use in physiology and medical teaching: increased breadth of awareness, increased institutional support (including time, training, and copyright support), and greater sharing of diverse OERs to suit the range of teaching challenges faced by staff in different subdisciplines. Copyright © 2017 the American Physiological Society.

Guidelines for Leveraging University Didactics Centers to Support OER Uptake in German-Speaking Europe

Science.gov (United States)

Ebner, M.; Schön, S.; Kumar, S.

2016-01-01

Although less well established than in other parts of the world, higher education institutions in German-speaking countries have seen a marked increase in the number of open educational resource (OER) initiatives and in government-supported OER funding in recent years. OER implementation, however, brings with it a unique set of challenges in…

A Survey of the Awareness, Offering, and Adoption of OERs and MOOCs in Japan

Science.gov (United States)

Shigeta, Katsusuke; Koizumi, Mitsuyo; Sakai, Hiroyuki; Tsuji, Yasuhiro; Inaba, Rieko; Hiraoka, Naoshi

2017-01-01

Awareness about Open Educational Resources (OERs) and the purposes for offering and adopting OERs and Massive Open Online Courses (MOOCs) were analyzed using a detailed survey of higher education across Japan, which was conducted in 2015. A comparison with a similar study conducted in 2013 revealed that awareness of OERs has increased slightly and…

Acceptance and Usability of OER in Indian Higher Education: An Investigation Using UTAUT Model

Science.gov (United States)

Padhi, Nayantara

2018-01-01

In the global movement towards open knowledge society, open educational resources (OER) have become a prominent contributor as a medium of education, research and training. In India, the phenomenon of OER is still in nascent stage. Although the country has been massively investing on growth and usage of ICT, it still requires acceptance of OER as…

A Framework to Integrate Public, Dynamic Metrics into an OER Platform

Science.gov (United States)

Cohen, Jaclyn Zetta; Omollo, Kathleen Ludewig; Malicke, Dave

2014-01-01

The usage metrics for open educational resources (OER) are often either hidden behind an authentication system or shared intermittently in static, aggregated format at the repository level. This paper discusses the first year of University of Michigan's project to share its OER usage data dynamically, publicly, to synthesize it across different…

Theoretical analysis of the dose dependence of the oxygen enhancement ratio and its relevance for clinical applications

International Nuclear Information System (INIS)

Wenzl, Tatiana; Wilkens, Jan J

2011-01-01

The increased resistance of hypoxic cells to ionizing radiation is usually believed to be the primary reason for treatment failure in tumors with oxygen-deficient areas. This oxygen effect can be expressed quantitatively by the oxygen enhancement ratio (OER). Here we investigate theoretically the dependence of the OER on the applied local dose for different types of ionizing irradiation and discuss its importance for clinical applications in radiotherapy for two scenarios: small dose variations during hypoxia-based dose painting and larger dose changes introduced by altered fractionation schemes. Using the widespread Alper-Howard-Flanders and standard linear-quadratic (LQ) models, OER calculations are performed for T1 human kidney and V79 Chinese hamster cells for various dose levels and various hypoxic oxygen partial pressures (pO2) between 0.01 and 20 mmHg as present in clinical situations in vivo. Our work comprises the analysis for both low linear energy transfer (LET) treatment with photons or protons and high-LET treatment with heavy ions. A detailed analysis of experimental data from the literature with respect to the dose dependence of the oxygen effect is performed, revealing controversial opinions whether the OER increases, decreases or stays constant with dose. The behavior of the OER with dose per fraction depends primarily on the ratios of the LQ parameters alpha and beta under hypoxic and aerobic conditions, which themselves depend on LET, pO2 and the cell or tissue type. According to our calculations, the OER variations with dose in vivo for low-LET treatments are moderate, with changes in the OER up to 11% for dose painting (1 or 3 Gy per fraction compared to 2 Gy) and up to 22% in hyper-/hypofractionation (0.5 or 20 Gy per fraction compared to 2 Gy) for oxygen tensions between 0.2 and 20 mmHg typically measured clinically in hypoxic tumors. For extremely hypoxic cells (0.01 mmHg), the dose dependence of the OER becomes more pronounced (up to 36

Designing Continuing Professional Development MOOCs to promote the adoption of OER and OEP

Directory of Open Access Journals (Sweden)

Shironica Priyanthi Karunanayaka

2018-04-01

Full Text Available There is growing interest in the adoption of open educational resources (OER and open educational practices (OEP in a variety of contexts. Continuing professional development (CPD among practitioners in the effective adoption of OER and OEP is critical in this scenario. Massive open online courses (MOOCs, which also grew as part of the open education movement, provide a feasible means for this purpose. MOOCs are considered a ‘disruptive innovation’ in making free and open learning opportunities accessible to large numbers. Yet, the design of an effective massive online course that is as robust as a great online course with smaller student numbers where good principles of teaching and learning are maintained, is very challenging. Most contemporary MOOCs tend to have a content-driven focus of knowledge transmission, deviating from its original focus of knowledge generation. With the intention of providing learning experiences to promote learner engagement with OER, rather than presenting content about OER, we designed four CPD MOOCs to support the integration of OER and adoption OEP by practitioners based on a scenario-based learning (SBL approach. This paper presents the analysis and design phases of this process, discussing the challenges faced and innovative strategies adopted in our pursuit to answer the question, “How best to design effective MOOCs on OER and OEP for continuing professional development of practitioners?”

Clinical oxygen enhancement ratio of tumors in carbon ion radiotherapy: the influence of local oxygenation changes

DEFF Research Database (Denmark)

Antonovic, Laura; Lindblom, Emely; Dasu, Alexandru

2014-01-01

, using the repairable–conditionally repairable (RCR) damage model with parameters for human salivary gland tumor cells. The clinical oxygen enhancement ratio (OER) was defined as the ratio of doses required for a tumor control probability of 50% for hypoxic and well-oxygenated tumors. The resulting OER...... was well above unity for all fractionations. For the hypoxic tumor, the tumor control probability was considerably higher if LOCs were assumed, rather than static oxygenation. The beneficial effect of LOCs increased with the number of fractions. However, for very low fraction doses, the improvement related...... to LOCs did not compensate for the increase in total dose required for tumor control. In conclusion, our results suggest that hypoxia can influence the outcome of carbon ion radiotherapy because of the non-negligible oxygen effect at the low LETs in the SOBP. However, if LOCs occur, a relatively high...

Developing and Deploying OERs in Sub-Saharan Africa: Building on the Present

Science.gov (United States)

Wright, Clayton R.; Reju, Sunday A.

2012-01-01

Open educational resources (OERs) have the potential to reduce costs, improve quality, and increase access to educational opportunities. OER development and deployment is one path that could contribute to achieving education for all. This article builds on existing information and communication technology (ICT) implementation plans in Africa and…

Determination of the oxygen enhancement ratio (OER) of human colon tumor cells in vitro after chronic exposure to the differentiation-inducing agents n-methylformamide (NMF) and sodium butyrate (NAB)

International Nuclear Information System (INIS)

Hallows, K.; Bliven, S.; Leith, J.T.

1987-01-01

The authors previously showed that both rodent and human tumor cells in either exponentially growing or plateau phase cultures can be sensitized to X-irradiation by chronic exposure to NMF or NAB. This effect is particularly evident in the low dose region of the survival curve as noted by a significant increase in the term of the linear-quadratic equation or by a significant decrease in the D/sub q/ value using single-hit, multitarget nomenclature. However, these agents are operationally distinct, as these changes are accompanied by inhibition of sublethal damage recovery (SLDR) after NAB treatment, while no effect on SLDR is seen with NMF treatment. As they think that the use of differentiation-inducing agent such as NMF or NAB may be useful in combining modality therapy of solid tumors, the authors extended their previous studies to note if any change in the OER accompanying this observed radiosensitization of oxic cells could be found. Tumor cells were grown in either 170mM NMF or 2 mM NAB and were irradiated with 250 kVp x-rays. Data is presented

Needs for and Utilization of OER in Distance Education: A Chinese Survey

Science.gov (United States)

Chen, Qing; Panda, Santosh

2013-01-01

The recent developments within open educational resources (OERs) and open licensing have generated considerable interest among distance educators since open and distance learning is supposed to be the largest consumer/user of and contributor to OER. In China, given the policy of development and use of elaborate courses, conversion of radio and…

Study of gamma radiation induced damages and variation of oxygen enhancement ratio with radiation dose using Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Nairy, R.K.; Yerol Narayana; Bhat, N.N.; Anjaria, K.B.; Sreedevi, B.; Sapra, B.K.

2014-01-01

In the present study, an attempt has been made to quantify Oxygen Enhancement Ratio (OER) and variation of OER as a function of dose with experimental and theoretical formulations using Saccharomyces cerevisiae D7, X2180 and rad 52. The study confirms that, the variation of OER with dose depends upon type of cell and repair proficiency of cells. A theoretical model has been formulated to estimate OER values. With the help of this model, OER value for any dose can be calculated in the exponential region of the survival curve without actually extending the experiment in that dose region. (author)

Wikiwijs: An unexpected journey and the lessons learned towards OER

Directory of Open Access Journals (Sweden)

Robert Schuwer

2014-04-01

Full Text Available The Dutch Ministry of Education, Culture and Science has funded a five years program to encourage the use, creation and sharing of Open Educational Resources (OER by teachers from various types of education. This program is known as Wikiwijs. Ultimo 2013, the program has come to an end. As some of the assumptions at the start of Wikiwijs proved to work out in unexpected ways the lessons learned could fuel the next steps in developing Wikiwijs. Besides, other national initiatives on opening up education may also benefit from the lessons learned reported here. The main conclusion from five years Wikiwijs was that to accomplish mainstreaming OER, the Wikiwijs program should go along with other interventions that are more oriented toward prescriptive policies and regulations. In particular: the Dutch government should be more directive in persuading executive boards and teachers on schools to adopt OER as an important part of educational reform and the acquisition of 21st century skills.

Embracing openness: the challenges of OER in Latin American education

Directory of Open Access Journals (Sweden)

Nadia Paola Mireles Torres

2013-01-01

Full Text Available The Open Educational Resources (OER movement and the Open Access began only over a decade ago. During this period, the progress of the Open Educational Resources movement took place in developed countries for the most part. Recently, new projects have begun to emerge with a strong emphasis on open education. Yet, the concept of openness in education is a very innovative one, and it has not been embraced by many. In some regions, such as Latin America, OER is still in its early stages and faces many challenges that need to be addressed. Some of these challenges include awareness raising and capacity development. But there is a bigger challenge to face: embracing openness as a core value and an institutional strategy. In this paper, we offer a brief overview of the meaning of the term “open” in education and we analyze the challenges facing the OER in Latin American countries.

Open Access Scholarly Publications as OER

Science.gov (United States)

Anderson, Terry

2013-01-01

This paper presents the rationale, common practices, challenges, and some personal anecdotes from a journal editor on the production, use, and re-use of peer-reviewed scholarly articles as open educational resources (OER). The scholarly and professional discourse related to open educational resources has largely focused on open learning objects,…

Learning from TESS-India's Approach to OER Localisation across Multiple Indian States

Science.gov (United States)

Perryman, Leigh-Anne; Hemmings-Buckler, Alison; Seal, Tim

2014-01-01

Arguably, the benefits of open educational resources (OER) are greatest in low- and middle-income countries, where they have the potential to increase access to learning for those who may otherwise be excluded. However, for OER to be truly useful to educators and learners they need to be adapted to suit the contexts in which they are to be…

From OER to OEP: Shifting Practitioner Perspectives and Practices with Innovative Learning Experience Design

Directory of Open Access Journals (Sweden)

Shironica Priyanthi Karunanayaka

2015-11-01

Full Text Available Like any other educational resource, the integration of OER in teaching and learning requires careful thought and support for the teaching staff. The Faculty of Education at the Open University of Sri Lanka approached this challenge with the help of a professional development course on OER-based e-Learning. ​Modules in the course ​​incorporated the use of authentic learning scenarios with learning tasks that facilitated capacity building in a collaborative manner. This paper reports the impact of this course in shifting their perspectives and practices in relation to open educational practices. ​In addition to a much richer grasp of conceptual knowledge and skills related to searching, identifying, evaluating and integrating OER, participants developed competencies in designing, developing and implementation of an OER-based e-Learning course.

Radiobiological studies with a series of human cell lines of varying glutathione content

Energy Technology Data Exchange (ETDEWEB)

Astor, M.B. (Columbia Univ., New York (USA). Radiological Research Lab.)

1984-08-01

The effect of decreased levels of intracellular glutathione (GSH) on the radiosensitivity of aerated and hypoxic cells was studied using human skin fibroblasts obtained from patients affected with the inborn error of metabolism, 5-oxoprolinuria. The oxygen enhancement ratios (OER) were determined for four cell lines obtained from a single family, SR and SUR (heterozygous parents) and GM3877 and GM3878 (affected homozygous siblings). Glutathione values ranged from 7.4 to 130% of control values. Only GM3877 with a GSH value 7.4% of control exhibited a reduced OER of 1.9 compared with a control value of 3. These results suggest that a reduction in OER is observed only when GSH levels reach extremely low values.

Mainstreaming use of Open Educational Resources (OER in an African context

Directory of Open Access Journals (Sweden)

Tony John Mays

2017-12-01

Full Text Available The study derives from a multi-year project implemented by OER Africa. The project sought to understand how OER might be used as a catalyst for pedagogical transformation in African universities. Within a non-determinist and interpretivist theoretical framework and an over-arching project methodology of participatory action research, the study made use of an analytical autoethnographic approach to capture and analyse data and to make recommendations. The approach was informed primarily by hermeneutics and systems thinking and involved multiple in-country engagements and the triangulation of information derived from document review, observation and iterative focus group discussions and individual interviews. The key finding of this study is the suggestion that engagement with OER is unlikely to move from being an individual to an institutional focus unless such engagement is aligned with the overall vision, mission and business model of the university.

The effects of cellular glutathione elevation on the oxygen enhancement ratio

International Nuclear Information System (INIS)

Mitchell, J.B.; Russo, A.

1984-01-01

It has recently been demonstrated for Chinese hamster and human A549 cells that depletion of cellular glutathione (GSH) by buthionine sulfoximine sensitizes both aerated and hypoxic cells to X-rays. While the extent of sensitization was minimal for both conditions, there was no overall reduction in the oxygen enhancement ratio (OER). The authors have investigated the effect of cellular GSH elevation on the OER by treating cells for 2 hours with 10 mM L-2-oxothiazolidine-4-carboxylate (OTZ) or face 24 hours with 0.06 mM cobalt chloride (CoCl/sub 2/) in complete medium. These treatments resulted in cellular concentrations of GSH to approximately 150-250% for OTZ and 150-300% for CoCl/sub 2/ when compared to controls. X-ray survival curves were determined following these treatments for aerated and hypoxic conditions. Hypoxia was induced by metabolic utilization of oxygen at high cell densities (10/sup 8//ml) in glass syringes. For both methods of GSH elevation, there was no protection observed for either aerated or hypoxic cells and consequently no change in the OER when compared to controls. These data are discussed in the context of the radical-scavenging hypothesis involving chemical repair following X-rays of compounds such as GSH

Radiobiological studies with a series of human cell lines of varying glutathione content

International Nuclear Information System (INIS)

Astor, M.B.

1984-01-01

The effect of decreased levels of intracellular glutathione (GSH) on the radiosensitivity of aerated and hypoxic cells was studied using human skin fibroblasts obtained from patients affected with the inborn error of metabolism, 5-oxoprolinuria. The oxygen enhancement ratios (OER) were determined for four cell lines obtained from a single family, SR and SUR (heterozygous parents) and GM3877 and GM3878 (affected homozygous siblings). Glutathione values ranged from 7.4 to 130% of control values. Only GM3877 with a GSH value 7.4% of control exhibited a reduced OER of 1.9 compared with a control value of 3. These results suggest that a reduction in OER is observed only when GSH levels reach extremely low values. (author)

Oxygen enhancement ratios for glutathione-deficient human fibroblasts determined from the frequency of radiation induced micronuclei

International Nuclear Information System (INIS)

Midander, J.

1982-01-01

The yield of micronuclei (MN) was determined to study the radiosensitizing effect of oxygen on three human fibroblast strains, characterized by genetically defined differences in their glutathione (GSH) level. Cells were irradiated in paired experiments with x-ray doses of 2.66 and 6.65 gy in their exponential growth phase in a monolayer under oxic and anoxic conditions. Results indicated a reduced oxygen effect for the GSH deficient cells, the reduction of o.e.r. being most pronounced in the case of GSHsup(-/-) cells, when it was close to unity. The o.e.r. value was intermediate for the GSHsup(+/-) in comparison with the two other cell strains. It is concluded that the data indicate a correlation between the cellular content of GSH and the oxygen enhancement of the formation of micronuclei after irradiation. (U.K.)

A new visual navigation system for exploring biomedical Open Educational Resource (OER) videos.

Science.gov (United States)

Zhao, Baoquan; Xu, Songhua; Lin, Shujin; Luo, Xiaonan; Duan, Lian

2016-04-01

Biomedical videos as open educational resources (OERs) are increasingly proliferating on the Internet. Unfortunately, seeking personally valuable content from among the vast corpus of quality yet diverse OER videos is nontrivial due to limitations of today's keyword- and content-based video retrieval techniques. To address this need, this study introduces a novel visual navigation system that facilitates users' information seeking from biomedical OER videos in mass quantity by interactively offering visual and textual navigational clues that are both semantically revealing and user-friendly. The authors collected and processed around 25 000 YouTube videos, which collectively last for a total length of about 4000 h, in the broad field of biomedical sciences for our experiment. For each video, its semantic clues are first extracted automatically through computationally analyzing audio and visual signals, as well as text either accompanying or embedded in the video. These extracted clues are subsequently stored in a metadata database and indexed by a high-performance text search engine. During the online retrieval stage, the system renders video search results as dynamic web pages using a JavaScript library that allows users to interactively and intuitively explore video content both efficiently and effectively.ResultsThe authors produced a prototype implementation of the proposed system, which is publicly accessible athttps://patentq.njit.edu/oer To examine the overall advantage of the proposed system for exploring biomedical OER videos, the authors further conducted a user study of a modest scale. The study results encouragingly demonstrate the functional effectiveness and user-friendliness of the new system for facilitating information seeking from and content exploration among massive biomedical OER videos. Using the proposed tool, users can efficiently and effectively find videos of interest, precisely locate video segments delivering personally valuable

Mobile Devices and Apps as Accelerators for OER

NARCIS (Netherlands)

De Vries, Fred; Thuss, Frank

2013-01-01

De Vries, F., & Thuss, F. (2013). Mobile Devices and Apps as accelerators for OER. In R. Jacobi, H. Jelgerhuis, & N. Van der Woert (Eds.), Trendreport Open Educational Resources 2013 (pp. 49-52). Utrecht: SURF Foundation - Special Interest Group Open Educational Resources SURF.

From OER to Open Education: Perceptions of Student Teachers after Creating Digital Stories with Creative Common Resources

OpenAIRE

Gemma Tur; Santos Urbina; Juan Moreno

2016-01-01

The current study explores the perceptions of three groups of student teachers in Spain after having used open licensed resources to construct their storytelling artifacts as OER. The theoretical framework briefly reviews the concept of Open Education and OER and the affordance and drawbacks previously observed in research. Data is obtained through a survey that enables the observation of students’ tendency to adapt OER, Open Educational Practices and the Open Movement. The results reveal a g...

Lernort Öffentliche Bibliothek und Open Eductional Resources (OER – Zusammenbringen, was zusammen gehört

Directory of Open Access Journals (Sweden)

Gabriele Fahrenkrog

2016-03-01

Full Text Available Mit den Veränderungen durch die Digitalisierung im Bildungsbereich, hin zu orts- und zeitunabhängigen Verfügbarkeit von Inhalten, zu Kollaboration und Partizipation in Lehr- und Lernkontexten, verändern sich auch die Anforderungen an den Lernort Bibliothek. Öffentliche Bibliotheken bieten Zugang zu Lehr- und Lernmaterialien und unterstützen Menschen in allen Belangen zu Aus- und Weiterbildung. Obwohl es sich bei OER (Open Educational Resources um Bildungsmedien handelt, haben sie bislang nicht den Weg in Öffentliche Bibliotheken gefunden. Es wird dargelegt, welche Gründe für ein Engagement von Bibliotheken mit OER spricht und aufgezeigt, was Öffentliche Bibliotheken mit bereits vorhandenen Kompetenzen und vorhandener Infrastruktur konkret unternehmen können, um  für das Thema OER zu sensibilisieren, OER zu vermitteln und dazu anzuregen, aktiv freie Bildungsmaterialen zu erstellen und weiter zu bearbeiten.

RBEOER: a FORTRAN program for the computation of RBEs, OERs, survival ratios, and the effects of fractionation using the theory of dual radiation action

International Nuclear Information System (INIS)

Zaider, M.; Dicello, J.F.

1978-05-01

The computer code RBEOER calculates RBEs, OERs and survival curves as a function of the dose delivered to a biological system and the temporal distribution of the dose (fractionation). The method of calculation is based on the theory of dual radiation action. The basic formalism and the input parameters are described. A sample output is presented

OER as Online Edutainment Resources: A Critical Look at Open Content, Branded Content, and How Both Affect the OER Movement

Science.gov (United States)

Moe, Rolin

2015-01-01

Despite a rise in awareness and production of open education resources (OER) over the past decade, mainstream media outlets continue to define open in economic terms of consumer cost and not in theoretical terms of remix or appropriation. This period in the "open access" debate has coincided with a proliferation of free-of-charge video…

75 FR 82377 - NOAA's Office of Ocean Exploration and Research (OER) Strategic Plan FY 2011-FY 2015

Science.gov (United States)

2010-12-30

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration (NOAA) NOAA's Office of... Administration (NOAA), Commerce. ACTION: Notice of availability and request for public comment. SUMMARY: NOAA's...: Yvette Jefferson. Mail: NOAA Office of Ocean Exploration and Research (OER), ATTN: OER Plan Comments...

Oxygen enhancement ratios in synchronous HeLa cells exposed to low-LET radiation

International Nuclear Information System (INIS)

Sapozink, M.D.

1977-01-01

HeLa cells were synchronized by the mitotic selection method and rendered hypoxic by coincubation with an excess of heavily irradiated, but metabolically active, feeder cells. An oxygen enhancement ratio (OER) of about 3 was obtained in interphase HeLa cells irradiated with x or gamma rays. A significantly lower OER was obtained with cells in, or close to, mitosis. The significance of this decrease in the oxygen effect in mitotic cells is discussed

76 FR 26254 - NOAA's Office of Ocean Exploration and Research (OER) Strategic Plan FY 2011-FY 2015

Science.gov (United States)

2011-05-06

..., and transitions the new knowledge and capabilities to the rest of NOAA, and the national and... management decisions to be made from relatively uninformed and incomplete knowledge. NOAA formed OER to..., and physical, chemical and biological characteristics. Data and observations resulting from OER...

BRAIN Journal - From OER to Open Education: Perceptions of Student Teachers after Creating Digital Stories with Creative Common Resources

OpenAIRE

Gemma Tur; Santos Urbina; Juan Moreno

2016-01-01

ABSTRACT The current study explores the perceptions of three groups of student teachers in Spain after having used open licensed resources to construct their storytelling artifacts as OER. The theoretical framework briefly reviews the concept of Open Education and OER and the affordance and drawbacks previously observed in research. Data is obtained through a survey that enables the observation of students’ tendency to adapt OER, Open Educational Practices and the Open Movement. The resul...

Innovative and high quality education through Open Education and OER

OpenAIRE

Stracke, Christian M.

2017-01-01

Online presentation and webinar by Stracke, C. M. (2017, 18 December) on "Innovative and high quality education through Open Education and OER" for the Belt and Road Open Education Learning Week by the Beijing Normal University, China.

Towards Development of OER Derived Custom-Built Open Textbooks: A Baseline Survey of University Teachers at the University of the South Pacific

Directory of Open Access Journals (Sweden)

Deepak Prasad

2014-09-01

Full Text Available Textbook prices have soared over the years, with several studies revealing many university students are finding it difficult to afford textbooks. Fortunately, two innovations – open educational resources (OER and open textbooks – hold the potential to increase textbook affordability. Experts, though, have stated the obvious: that students can save money through open textbooks only if teachers are willing to develop and use them. Considering both the high price of textbooks and the benefits offered by OER and open textbooks, the aim of this study was to assess the University of the South Pacific (USP teachers’ willingness towards development of custom-built OER derived open textbooks for their courses with a focus on providing a foundation for strategies to promote open textbook development at USP. This paper reports the findings of an online survey of 39 USP teachers. The results show that 17 teachers were willing to develop OER derived custom-built open textbooks for their courses. Besides this, there are findings relating to six important areas: teachers’ motivation to develop open textbooks; the frequency of more than one prescribed textbook per course; teachers’ awareness of the costs of the prescribed textbooks; the average cost of prescribed textbooks in a course; teachers’ awareness and utilization of OER and open textbooks; and teachers’ perceived barriers to using OER and types of challenges they encounter while using OER. These findings have been discussed in relation to research studies on OER and open textbooks.

Vastly Enhanced BiVO4 Photocatalytic OER Performance by NiCoO2 as Cocatalyst

KAUST Repository

Palaniselvam, Thangavelu

2017-08-07

Here, a simple and efficient preparation of NiCoO nanoparticle modified nanoporous bismuth vanadate (BiVO) thin film and its application in photoelectrocatalytic (PEC) oxygen evolution reaction (OER) is demonstrated. The role of NiCoO in the composite electrode (BiVO/NiCoO) is twofold: OER cocatalyst and band structure modifier. It improves surface reaction kinetics for PEC OER and enhances charge separation efficiency simultaneously, which is believed to be a determining factor for the unprecedentedly high PEC OER performance of this BiVO/NiCoO nanocomposite. The photocurrent density of 3.6 mA cm at 1.23 V versus RHE in 0.1 m potassium phosphate buffered (pH = 7) electrolyte by BiVO/NiCoO is three times that of BiVO and significantly higher than most literature values. The BiVO/NiCoO nanocomposite shows/possess a high charge separation efficiency (η) of ≈72% as compared to only 23% for pure nanoporous BiVO at 1.23 V versus RHE, which demonstrates convincing role of NiCoO in the composite electrode. Both the excellent photocurrent density and great operational stability of this BiVO/NiCoO nanocomposite makes it a promising photocatalytic material for practical applications.

OER Use in Intermediate Language Instruction: A Case Study

Science.gov (United States)

Godwin-Jones, Robert

2017-01-01

This paper reports on a case study in the experimental use of Open Educational Resources (OERs) in intermediate level language instruction. The resources come from three sources: the instructor, the students, and open content repositories. The objective of this action research project was to provide student-centered learning materials, enhance…

From OER to Open Education: Perceptions of Student Teachers after Creating Digital Stories with Creative Common Resources

Directory of Open Access Journals (Sweden)

Gemma Tur

2016-06-01

Full Text Available The current study explores the perceptions of three groups of student teachers in Spain after having used open licensed resources to construct their storytelling artifacts as OER. The theoretical framework briefly reviews the concept of Open Education and OER and the affordance and drawbacks previously observed in research. Data is obtained through a survey that enables the observation of students’ tendency to adapt OER, Open Educational Practices and the Open Movement. The results reveal a general positive impact on student perceptions, although nuances and challenges are observed. The part containing the discussion and conclusions suggests some implications of this current step of research for future implementation in Teacher Education and related research.

Oxygen enhancement ratio for negative pi mesons

International Nuclear Information System (INIS)

Hall, E.J.; Astor, M.

1979-01-01

Experiments were performed at the Los Alamos Meson Physics Facility (LAMPF) to determine the oxygen enhancement ratio (OER) for the clinically used beam of negative pi mesons. V79 Chinese hamster cells, cultured in vitro, were used as the biological test system; hypoxia was produced by metabolic depletion as a result of sealing 2 million cells in 1 ml glass ampules. The Bragg peak of the pion depth dose curve was spread out to cover 10 cm by using a dynamic range shifter. Cells were irradiated at the center of the spead out Bragg peak, where the dose/rate was 0.1 Gy/min over a 6 x 6 cm field. The OER obtained was 2.2, compared with 3.8 obtained for γ rays under the same conditions

Open Education, OER & MOOCs for entrepreneurship: To share or not to share

NARCIS (Netherlands)

Stracke, Christian M.

2016-01-01

Invited Speech at the Conference Skills and competences on female entrepreneurship, Athens, Greece, by Stracke, C. M. (2016, 6 July): "Open Education, OER & MOOCs for entrepreneurship: To share or not to share"

Wikiwijs: An unexpected journey and the lessons learned towards OER

NARCIS (Netherlands)

Schuwer, Robert; Kreijns, Karel; Vermeulen, Marjan

2018-01-01

The Dutch Ministry of Education, Culture and Science has funded a five years program to encourage the use, creation and sharing of Open Educational Resources (OER) by teachers from various types of education. This program is known as Wikiwijs. Ultimo 2013, the program has come to an end. As some of

Education for All Revisited: On Concepts of Sharing in the Open Educational Resources (OER Movement

Directory of Open Access Journals (Sweden)

Theo Hug

2014-11-01

Full Text Available  Relationships between the private and public sphere in education have been discussed repeatedly and in various ways. However, the role of media and media dynamics is widely underestimated in this context. It is only recently, since the digital turn, that the focus of the debates has changed. In the past few years, manifold initiatives have aimed at opening up education on various levels using digital communications technologies and Creative Commons licenses. Additionally, massive open online courses (moocs have been developed. Today, OER (Open Educational Resources is used widely as an umbrella term for free content creation initiatives: OER Commons (http://www.oercommons.org/, Open Courseware (OCW, OER repositories, OCW search facilities, University OCW initiatives, and related activities. Shared resource sites such as Connexions (http://cnx.org, WikiEducator (http://wikieducator.org, and Curriki (www.curriki.org have an increasing number of visitors and contributors.On one hand, the motif of ‘education for all’ is once again appearing in related debates and practices. On the other hand, notions of sharing play a crucial role in open content and open education strategies. This purpose of this paper isthreefold: It starts with an outline of selected understandings of sharing in educational contexts; it then addresses their relevance for OER development through examining contrasting and relational conceptual dimensions. Lastly, the contribution aims to sketch different forms of sharing related to media forms.

OER and the Value of Openness: Implications for the Knowledge Economy

Science.gov (United States)

Bernstein, Samantha

2015-01-01

The knowledge economy is marked by recent trends in technological advancement, globalisation and increasing knowledge intensity. Through new technologies like Open Educational Resources (OER), knowledge can be freely accessed by individuals around the world, blurring traditional notions of ownership and prompting a social transformation manifested…

Measurements of Relative Biological Effectiveness and Oxygen Enhancement Ratio of Fast Neutrons of Different Energies

Energy Technology Data Exchange (ETDEWEB)

Barendsen, G. W.; Broerse, J. J. [Radiobiological Institute of the Health Research Council TNO, Rijswijk (ZH) (Netherlands)

1968-03-15

Impairment of the reproductive capacity of cultured cells of human kidney origin (T-l{sub g} cells) has been measured by the Puck cloning technique. From the dose-survival curves obtained in these experiments by irradiation of cells in equilibrium with air and nitrogen, respectively, the relative biological effectiveness (RBE) and the oxygen enhancement ratios (OER) were determined for different beams of fast neutrons. Monoenergetic neutrons of 3 and 15 MeV energy, fission spectrum fast neutrons (mean energy about 1.5 MeV), neutrons produced by bombarding Be with cyclotron-accelerated 16 MeV deuterons (mean energy about 6 MeV) and neutrons produced by bombarding Be with cyclotron- accelerated 20 MeV {sup 3}He ions (mean energy about 10 MeV) have been compared with 250 kVp X-rays as a standard reference. The RBE for 50% cell survival varies from 4.7 for fission-spectrum fast neutrons to 2.7 for 15 MeV monoenergetic neutrons. The OER is not strongly dependent on the neutron energy for the various beams investigated. For the neutrons with the highest and lowest energies used OER values of 1.6 {+-} 0.2 and 1.5 {+-} 0.1 were measured. An interpretation of these data on the basis of the shapes of the LET spectra is proposed and an approximate verification of this hypothesis is provided from measurements in which secondary particle equilibrium was either provided for or deliberately eliminated. (author)

Online Training of Teachers Using OER: Promises and Potential Strategies

Science.gov (United States)

Misra, Pradeep Kumar

2014-01-01

Teacher education nowadays needs a change in vision and action to cater to the demands of changing societies. Reforms, improvements, and new approaches in teacher education are an immediate need. Online training of teachers using OER has emerged as a new approach in this direction. This approach is based on the assumption that online training will…

BOOK REVIEW OPEN EDUCATION: FROM OERs to MOOCs

Directory of Open Access Journals (Sweden)

Nil GOKSEL CANBEK

2017-04-01

Full Text Available The specific focus of this edited book is to point out the core policies, initiatives and international practices of Distance Education in connection with open and free accessed resources. The book aims to provide a roadmap for the existing and possible opportunities for new technologies and educational paradigms within the scope of lifelong learning. Concisely, the book addresses Open Education through the potential of Open Educational Resources (OER and the new trends of Massive Open Online Courses (MOOCs.

Open Access and OER in Latin America: A survey of the policy landscape in Chile, Colombia and Uruguay

OpenAIRE

Toledo, Amalia

2017-01-01

This chapter presents an overview of the mechanisms (funding, policy, legislative and procedural) adopted by Latin American governments with respect to Open Access and Open Educational Resources (OER) initiatives in the higher education sector. It addresses three questions: How do the higher education systems of Chile, Colombia and Uruguay operate and fund their activities in general? How do existing policies and processes incorporating Open Access and/or OER influence student access to learn...

An Investigation of Faculty Perspectives on Barriers, Incentives, and Benefits of the OER Movement in Turkey

Directory of Open Access Journals (Sweden)

Engin Kursun

2014-12-01

Full Text Available The purpose of this survey study is to investigate faculty’s perceptions of the main incentives, barriers, and benefits to publishing their course materials for free within the open educational resources (OER movement. Data were collected from an online survey of 1,637 faculty from 56 universities in Turkey. Results showed that even though the majority of the participants’ perceptions of OER benefits and their attitudes toward publishing their course materials were positive, legal issues were perceived as an obstacle to effective application. Intellectual property protection mechanisms were perceived as the most important incentive to facilitate their contribution.

Research on the NPP human factors engineering operating experience review

International Nuclear Information System (INIS)

Ren Xiangchen; Miao Hongxing; Ning Zhonghe

2006-01-01

This paper addresses the importance of the human factors engineering (HFE) for the design of nuclear power plant (NPP), especially for the design of human-machine interface in the NPP. It also summarizes the scope and content of the NPP HFE. The function, scope, content and process of the NPP human factors engineering operating experience review (OER) are mainly focused on, and significantly discussed. Finally, it briefly introduces the situation of the studies on the OER in China. (authors)

OER in the Mobile Era: Content Repositories’ Features for Mobile Devices and Future Trends

NARCIS (Netherlands)

Tabuenca, Bernardo; Drachsler, Hendrik; Ternier, Stefaan; Specht, Marcus

2012-01-01

Tabuenca, B., Drachsler, H., Ternier, S., & Specht, M. (2012, December). OER in the Mobile Era: Content Repositories’ Features for Mobile Devices and Future Trends. Europe eleaning papers, [Special issue] Mobile learning 2012.

Oxygen enhancement ratio as a function of neutron energy with mammalian cells in culture

International Nuclear Information System (INIS)

Rini, F.J.; Hall, E.J.; Marino, S.A.

1979-01-01

Chinese hamster cells (V79) in culture under oxic and hypoxic conditions were irradiated with several neutron beams spanning a wide energy range to determine the oxygen enhancement ratio (OER). Eight essentially monoenergetic neutron beams, ranging from 0.22 to 13.6 MeV and a 0.11-MeV neutron spectrum, were produced at the Radiological Research Accelerator Facility (RARAF) at Brookhaven National Laboratory. Additional experiments were performed at the Naval Research Laboratory, Washington, DC, where neutrons are produced for radiotherapy by bombarding a beryllium target with 35-MeV deuterons. This beam has a broad energy spectrum with a mean energy of about 15 MeV. A maximum OER of about 1.9 was observed for 13.6-MeV neutrons. The OER values of the monoenergetic neutrons decreased with energy, plateaued at about 1.45 for the energy range from 0.22 to 2.0 MeV and increased slightly to about 1.55 for lower energy spectrum. In the light of microdosimetric data obtained for the neutron beams at RARAF, the OER appears to depend primarily on the intermediate-LET secondaries produced by neutrons in tissue, such as protons, while in contrast high LET-secondaries, such as α-particles and recoil ions, play a minor role. The studies using the NRL neutron beam resulted in a lower OER of about 1.67 as compared to the monoenergetic 13.6-MeV beam. This is a consequence of the fact that more of the dose is deposited by intermediate LET secondaries for the NRL neutron beam

Localizing OER in Afghanistan: Developing a Multilingual Digital Library for Afghan Teachers

Science.gov (United States)

Oates, Lauryn; Hashimi, Jamshid

2016-01-01

The Darakht-e Danesh ("knowledge tree") Online Library is the first open educational resource (OER) initiative in Afghanistan, established to enhance teacher subject-area knowledge, access and use of learning materials, and to foster more diverse teaching methodologies in order to improve learning outcomes in Afghan classrooms. This…

Open Access Scholarly Publications as OER

Directory of Open Access Journals (Sweden)

Terry Anderson

2013-06-01

Full Text Available This paper presents the rationale, common practices, challenges, and some personal anecdotes from a journal editor on the production, use, and re-use of peer-reviewed scholarly articles as open educational resources (OER. The scholarly and professional discourse related to open educational resources has largely focused on open learning objects, courseware, and textbooks. However, especially in graduate education, articles published in scholarly journals are often a major component of the course content in formal education. In addition, open access journal articles are critical to expanding access to knowledge by scholars in the developing world and in fostering citizen science, by which everyone has access to the latest academic information and research results. In this article, I highlight some of the challenges, economic models, and evidence for quality of open access journal content and look at new affordances provided by the Net for enhanced functionality, access, and distribution.In the 17 years since I graduated with a doctorate degree, the climate and acceptance of open access publishing has almost reversed itself. I recall a conversation with my PhD supervisor in which he argued that publishing online was not a viable option as the product would not have permanency, scholarly recognition, or the prestige of a paper publication. His comments reflect the confusion between online resources and those described as open access, but as well illustrate the change in academic acceptance and use of open access products during the past decade. The evolution from paper to online production and consumption is a disruptive technology in which much lower cost and increased accessibility of online work opens the product to a completely new group of potential users. In the case of OER these consumers are primarily students, but certainly access to scholars from all parts of the globe and the availability to support citizen science (Silvertown, 2009

Framework for the Development of OER-Based Learning Materials in ODL Environment

Science.gov (United States)

Teng, Khor Ean; Hung, Chung Sheng

2013-01-01

This paper describes the framework for the development of OER-based learning materials "TCC121/05 Programming Fundamentals with Java" for ODL learners in Wawasan Open University (WOU) using three main development phases mainly: creation, evaluation and production phases. The proposed framework has further been tested on ODL learners to…

The Role of OER Localisation in Building a Knowledge Partnership for Development: Insights from the TESSA and TESS-India Teacher Education Projects

Science.gov (United States)

Buckler, Alison; Perryman, Leigh-Anne; Seal, Tim

2014-01-01

Open educational resources (OER) continue to support the needs of educators and learners globally. However, it is clear that to maximise their potential more focus is needed on reuse and repurposing. Accordingly, adapting OER for local contexts remains one of the greatest challenges of the open education movement, with little written about how to…

Novel Co3O4 Nanoparticles/Nitrogen-Doped Carbon Composites with Extraordinary Catalytic Activity for Oxygen Evolution Reaction (OER)

Science.gov (United States)

Yang, Xiaobing; Chen, Juan; Chen, Yuqing; Feng, Pingjing; Lai, Huixian; Li, Jintang; Luo, Xuetao

2018-03-01

Herein, Co3O4 nanoparticles/nitrogen-doped carbon (Co3O4/NPC) composites with different structures were prepared via a facile method. Structure control was achieved by the rational morphology design of ZIF-67 precursors, which were then pyrolyzed in air to obtain Co3O4/NPC composites. When applied as catalysts for the oxygen evolution reaction (OER), the M-Co3O4/NPC composites derived from the flower-like ZIF-67 showed superior catalytic activities than those derived from the rhombic dodecahedron and hollow spherical ZIF-67. The former M-Co3O4/NPC composite displayed a small over-potential of 0.3 V, low onset potential of 1.41 V, small Tafel slope of 83 mV dec-1, and a desirable stability. (94.7% OER activity was retained after 10 h.) The excellent performance of the flower-like M-Co3O4/NPC composite in the OER was attributed to its favorable structure. [Figure not available: see fulltext.

Vastly Enhanced BiVO4 Photocatalytic OER Performance by NiCoO2 as Cocatalyst

KAUST Repository

Palaniselvam, Thangavelu; Shi, Le; Mettela, Gangaiah; Anjum, Dalavar H.; Li, Renyan; Katuri, Krishna; Saikaly, Pascal; Wang, Peng

2017-01-01

Here, a simple and efficient preparation of NiCoO nanoparticle modified nanoporous bismuth vanadate (BiVO) thin film and its application in photoelectrocatalytic (PEC) oxygen evolution reaction (OER) is demonstrated. The role of Ni

Open Access and OER in Latin America: A survey of the policy landscape in Chile, Colombia and Uruguay (Advance online publication)

OpenAIRE

Toledo, Amalia

2017-01-01

This chapter presents an overview of the mechanisms (funding, policy, legislative and procedural) adopted by Latin American governments with respect to Open Access and Open Educational Resources (OER) initiatives in the higher education sector. It addresses three questions: How do the higher education systems of Chile, Colombia and Uruguay operate and fund their activities in general? How do existing policies and processes incorporating Open Access and/or OER influence student access to learn...

Human Factors Engineering (HFE) insights for advanced reactors based upon operating experience

International Nuclear Information System (INIS)

Higgins, J.; Nasta, K.

1997-01-01

The NRC Human Factors Engineering Program Review Model (HFE PRM, NUREG-0711) was developed to support a design process review for advanced reactor design certification under 10CFR52. The HFE PRM defines ten fundamental elements of a human factors engineering program. An Operating Experience Review (OER) is one of these elements. The main purpose of an OER is to identify potential safety issues from operating plant experience and ensure that they are addressed in a new design. Broad-based experience reviews have typically been performed in the past by reactor designers. For the HFE PRM the intent is to have a more focussed OER that concentrates on HFE issues or experience that would be relevant to the human-system interface (HSI) design process for new advanced reactors. This document provides a detailed list of HFE-relevant operating experience pertinent to the HSI design process for advanced nuclear power plants. This document is intended to be used by NRC reviewers as part of the HFE PRM review process in determining the completeness of an OER performed by an applicant for advanced reactor design certification. 49 refs

Variation of oxygen enhancement ratio with radiation dose studies using 8 MeV electron beam

International Nuclear Information System (INIS)

Yerol, Narayana; Nairy, Rajesha K.; Sanjeev, Ganesh

2014-01-01

The radiobiological effects can be modified by physical, chemical and biological factors. Oxygen is one of the best known modifiers, and the biological effects are greater in the presence of oxygen. Failure to achieve complete response following radiotherapy of large tumors is attributed to the presence of radio-resistant hypoxic cells; therefore clarifying the mechanism of the oxygen effect is important. In the present study, an attempt was made to quantify Oxygen Enhancement Ratio (OER) and variation of OER as a function of dose with experimental and theoretical formulations using Saccharomyces cerevisiae D7, X2180 and rad 52 and 8 MeV electron beam from Microtron accelerator. The single cell stationary-phase cultures were obtained by growing the cells in Yeast extract: Peptone: Dextrose (YEPD) (1%:2%:2%) medium for several generations in stationary phase to a density of approximately 3 x 10 8 cells mL -1 . Cells were washed thrice by centrifugation and re-suspended to a cell concentration of 1 x 10 8 cells mL -1 in a sterile polypropylene vial for irradiation. Hypoxic conditions were achieved by incubating the samples in air tight vials at 30℃ for 30 min prior to irradiation. For euoxic samples, a cell suspension of 1 x 10 6 cells mL -1 was prepared and was thoroughly aerated by mixing before irradiation. Treated and untreated samples were suitably diluted and plated in quadruplicate on YEPD agar medium. Plates were incubated for 2-3 days at 30℃ in dark and normal atmospheric conditions and the colonies were counted. The study confirmed that, the variation of OER with dose depends upon type of cell and repair proficiency of cells. For repair proficient cells OER value has been found to increase with dose, while remain constant for repair deficient cell lines. A theoretical model has been formulated to estimate OER values. The OER value varies from 1.51 to 2.53 for D7, 2.02 to 2.98 for X2180, and 2.58 for rad 52. (author)

U.S. Army Officer Perceptions of the New OER (DA Form 67-8).

Science.gov (United States)

1982-12-01

67-8. B. BACKGROUND The U.S. Army Officer Evaluation Reporting System (OERS) is the product of many years’of research and development. It is part of...Professional Study, Air War College, Maxwell AFB, AL, April 1975. Currey, Cecil B., Self-Destruction The Disintergration and Decay of the United States Army

75 FR 15686 - NOAA'S Office of Ocean Exploration and Research (OER) Strategic Plan FY 2011-FY 2015

Science.gov (United States)

2010-03-30

...-01] NOAA'S Office of Ocean Exploration and Research (OER) Strategic Plan FY 2011-FY 2015 AGENCY... and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of availability and request for public comment. [[Page 15687

Spot Scanning and Passive Scattering Proton Therapy: Relative Biological Effectiveness and Oxygen Enhancement Ratio in Cultured Cells.

Science.gov (United States)

Iwata, Hiromitsu; Ogino, Hiroyuki; Hashimoto, Shingo; Yamada, Maho; Shibata, Hiroki; Yasui, Keisuke; Toshito, Toshiyuki; Omachi, Chihiro; Tatekawa, Kotoha; Manabe, Yoshihiko; Mizoe, Jun-etsu; Shibamoto, Yuta

2016-05-01

To determine the relative biological effectiveness (RBE), oxygen enhancement ratio (OER), and contribution of the indirect effect of spot scanning proton beams, passive scattering proton beams, or both in cultured cells in comparison with clinically used photons. The RBE of passive scattering proton beams at the center of the spread-out Bragg peak (SOBP) was determined from dose-survival curves in 4 cell lines using 6-MV X rays as controls. Survival of 2 cell lines after spot scanning and passive scattering proton irradiation was then compared. Biological effects at the distal end region of the SOBP were also investigated. The OER of passive scattering proton beams and 6 MX X rays were investigated in 2 cell lines. The RBE and OER values were estimated at a 10% cell survival level. The maximum degree of protection of radiation effects by dimethyl sulfoxide was determined to estimate the contribution of the indirect effect against DNA damage. All experiments comparing protons and X rays were made under the same biological conditions. The RBE values of passive scattering proton beams in the 4 cell lines examined were 1.01 to 1.22 (average, 1.14) and were almost identical to those of spot scanning beams. Biological effects increased at the distal end of the SOBP. In the 2 cell lines examined, the OER was 2.74 (95% confidence interval, 2.56-2.80) and 3.08 (2.84-3.11), respectively, for X rays, and 2.39 (2.38-2.43) and 2.72 (2.69-2.75), respectively, for protons (Pcells between X rays and protons). The maximum degree of protection was significantly higher for X rays than for proton beams (P<.05). The RBE values of spot scanning and passive scattering proton beams were almost identical. The OER was lower for protons than for X rays. The lower contribution of the indirect effect may partly account for the lower OER of protons. Copyright © 2016 Elsevier Inc. All rights reserved.

User-Oriented Quality for OER: Understanding Teachers' Views on Re-Use, Quality, and Trust

Science.gov (United States)

Clements, K. I.; Pawlowski, J. M.

2012-01-01

We analysed how teachers as users of open educational resources (OER) repositories act in the re-use process and how they perceive quality. Based on a quantitative empirical study, we also surveyed which quality requirements users have and how they would contribute to the quality process. Trust in resources, organizations, and technologies seem to…

An Empirical Investigation of the Emergent Issues around OER Adoption in Sub-Saharan Africa

Science.gov (United States)

Ngimwa, Pauline; Wilson, Tina

2012-01-01

In the past few years, Africa has joined the rest of the world as an active participant in the Open Educational Resource (OER) movement with a number of home-grown and externally driven initiatives. These have the potential to make an immense contribution to teaching and learning in Sub-Saharan Africa (SSA). However, certain barriers prevent full…

Rethinking OER and their Use : Open Education as Bildung

Directory of Open Access Journals (Sweden)

Markus Deimann

2013-07-01

Full Text Available Despite the recent increases of interest in open education, notably in massive open online courses (MOOCs (Fini, 2009, it has been continuously asserted that this form of social knowledge production lacks a philosophical or theoretical foundation (Vandenberg, 1975. Similar accusations have been made with respect to distance education, such as being slow to engage with critical debates in theory and research (Evans & Nation, 1992. In a similar vein, Danaher, Wyer, and Bartlett (1998 claim that researchers in open and distance learning tend to draw on too narrow a range of theoretical resources in their research. Given the considerable rise of open education over recent years, these critical appraisals urge us to expand theoretical approaches and refine our understanding of evolving pedagogical and technological relations (cf. Bell, 2011. In this paper, we contribute to debates surrounding open education and open educational resources by introducing the concept of Bildung (self-cultivation, self-realization as a powerful reflective tool and framework for approaching open education. We will elaborate on the potentials of Bildung by reviewing the history of the concept and exploring the extent to which Bildung can provide open education with a theoretical framework. Our focus is not exclusively on open educational resources (OER: We follow other commentators (Mackey & Jacobson, 2011, p. 62; cf. Weller, 2011 who argue that ‘openness’ in education necessarily shifts the focus from content (OER to practices (OEP that are necessary for the use of that content.We also argue that the beliefs and values associated with Bildung – including autonomy, critical reflection, inclusivity, and embracing the potential for self-development – are suitable for providing a theoretical framework for open education as well as providing a critical lens through which to assess contemporary models of education (e.g., Liessmann, 2006.

Open Education and OER - A guide and call to action for policy makers

OpenAIRE

Deepwell, Maren; Weller, Martin; Campbell, Lorna; Wilson, Joe

2017-01-01

Executive Summary ALT has produced this call to action to highlight to education policy makers and professionals how Open Education and OER can expand inclusive and equitable access to education and lifelong learning, widen participation, and create new opportunities for the next generation of teachers and learners, preparing them to become fully engaged digital citizens. Open Education can also promote knowledge transfer while enhancing quality and sustainability, supporting social inclu...

Understanding Social OER Environments--A Quantitative Study on Factors Influencing the Motivation to Share and Collaborate

Science.gov (United States)

Pirkkalainen, Henri; Jokinen, Jussi P. P.; Pawlowski, Jan M.

2014-01-01

Social software environments are increasingly used for open education: teachers and learners share and collaborate in these environments. While there are various possibilities for the inclusion of such social functionalities for OER, many organizational, individual and technological challenges can hinder the motivation of teachers to share and…

Small interfering RNA targeting HIF-1{alpha} reduces hypoxia-dependent transcription and radiosensitizes hypoxic HT 1080 human fibrosarcoma cells in vitro

Energy Technology Data Exchange (ETDEWEB)

Staab, Adrian [Wuerzburg Univ. (Germany). Dept. of Radiation Oncology; Paul Scherrer Institute (PSI), Villigen (Switzerland); Fleischer, Markus [Wuerzburg Univ. (Germany). Dept. of Radiation Oncology; Wuerzburg Univ. (Germany). Medical Clinic II; Loeffler, Juergen; Einsele, Herrmann [Wuerzburg Univ. (Germany). Medical Clinic II; Said, Harun M.; Katzer, Astrid; Flentje, Michael [Wuerzburg Univ. (Germany). Dept. of Radiation Oncology; Plathow, Christian [Freiburg Univ. (Germany). Dept. of Nuclear Medicine; Vordermark, Dirk [Wuerzburg Univ. (Germany). Dept. of Radiation Oncology; Halle-Wittenberg Univ. (Germany). Dept. of Radiation Oncology

2011-04-15

Background: Hypoxia inducible factor-1 has been identified as a potential target to overcome hypoxia-induced radioresistance The aim of the present study was to investigate whether selective HIF-1 inhibition via small interfering RNA (siRNA) targeting hypoxia-inducible factor 1{alpha} (HIF-1{alpha}) affects hypoxia-induced radioresistance in HT 1080 human fibrosarcoma cells. Material and Methods: HIF-1{alpha} expression in HT 1080 human fibrosarcoma cells in vitro was silenced using HIF-1{alpha} siRNA sequence primers. Quantitative real-time polymerase chain reaction assay was performed to quantify the mRNA expression of HIF-1{alpha}. HIF-1{alpha} protein levels were studied by Western blotting at 20% (air) or after 12 hours at 0.1% O{sub 2} (hypoxia). Cells were assayed for clonogenic survival after irradiation with 2, 5, or 10 Gy, under normoxic or hypoxic conditions in the presence of HIF-1{alpha}-targeted or control siRNA sequences. A modified oxygen enhancement ratio (OER') was calculated as the ratio of the doses to achieve the same survival at 0.1% O{sub 2} as at ambient oxygen tensions. OER' was obtained at cell survival levels of 50%, 37%, and 10%. Results: HIF-1{alpha}-targeted siRNA enhanced radiation treatment efficacy under severely hypoxic conditions compared to tumor cells treated with scrambled control siRNA. OER was reduced on all survival levels after treatment with HIF-1{alpha}-targeted siRNA, suggesting that inhibition of HIF-1 activation by using HIF-1{alpha}-targeted siRNA increases radiosensitivity of hypoxic tumor cells in vitro. Conclusion: Inhibition of HIF-1 activation by using HIF-1{alpha}-targeted siRNA clearly acts synergistically with radiotherapy and increase radiosensitivity of hypoxic cells in vitro. (orig.)

Small interfering RNA targeting HIF-1α reduces hypoxia-dependent transcription and radiosensitizes hypoxic HT 1080 human fibrosarcoma cells in vitro

International Nuclear Information System (INIS)

Staab, Adrian; Fleischer, Markus; Wuerzburg Univ.; Loeffler, Juergen; Einsele, Herrmann; Said, Harun M.; Katzer, Astrid; Flentje, Michael; Plathow, Christian; Vordermark, Dirk; Halle-Wittenberg Univ.

2011-01-01

Background: Hypoxia inducible factor-1 has been identified as a potential target to overcome hypoxia-induced radioresistance The aim of the present study was to investigate whether selective HIF-1 inhibition via small interfering RNA (siRNA) targeting hypoxia-inducible factor 1α (HIF-1α) affects hypoxia-induced radioresistance in HT 1080 human fibrosarcoma cells. Material and Methods: HIF-1α expression in HT 1080 human fibrosarcoma cells in vitro was silenced using HIF-1α siRNA sequence primers. Quantitative real-time polymerase chain reaction assay was performed to quantify the mRNA expression of HIF-1α. HIF-1α protein levels were studied by Western blotting at 20% (air) or after 12 hours at 0.1% O 2 (hypoxia). Cells were assayed for clonogenic survival after irradiation with 2, 5, or 10 Gy, under normoxic or hypoxic conditions in the presence of HIF-1α-targeted or control siRNA sequences. A modified oxygen enhancement ratio (OER') was calculated as the ratio of the doses to achieve the same survival at 0.1% O 2 as at ambient oxygen tensions. OER' was obtained at cell survival levels of 50%, 37%, and 10%. Results: HIF-1α-targeted siRNA enhanced radiation treatment efficacy under severely hypoxic conditions compared to tumor cells treated with scrambled control siRNA. OER was reduced on all survival levels after treatment with HIF-1α-targeted siRNA, suggesting that inhibition of HIF-1 activation by using HIF-1α-targeted siRNA increases radiosensitivity of hypoxic tumor cells in vitro. Conclusion: Inhibition of HIF-1 activation by using HIF-1α-targeted siRNA clearly acts synergistically with radiotherapy and increase radiosensitivity of hypoxic cells in vitro. (orig.)

ANALISIS PENGARUH LDR, NPL DAN OPERATIONAL EFFICIENCY RATIO TERHADAP RETURN ON ASSETS PADA BANK DEVISA DI INDONESIA PERIODE 2010-2012

Directory of Open Access Journals (Sweden)

Hamidah Hamidah

2014-04-01

Full Text Available This research is performed on order to test analysis the influence of the Loan to Deposit Ratio (LDR, Non Performing Loan (NPL and Operational Efficiency Ratio (OER toward Return On Asset (ROA On Foreign Exchange Banks In Indonesia Period 2010-2012. Methodology research as the sample used purposive sampling, sample was accrued from foreign banks in Indonesia. Data analysis with multi linear regression of ordinary least square and hypotheses test used t-statistic and F statistic, a classic assumption examination to test the hypotheses.Based on normality test, multicolinearity test, heterosskedasticity test and auto correlation test were not found variables that deviate from the classical assumptions, this indicate that the available data has fulfill the condition to use multi linear regression model. This result of research show that variable LDR and NPL partially have positive influence but not significant toward ROA. Variable OERpartially have negative significant influence toward ROA. Variable LDR, NPL and OER simultaneously have significant influence toward ROA.

A spatio-temporal simulation model of the response of solid tumours to radiotherapy in vivo: parametric validation concerning oxygen enhancement ratio and cell cycle duration

International Nuclear Information System (INIS)

Antipas, Vassilis P; Stamatakos, Georgios S; Uzunoglu, Nikolaos K; Dionysiou, Dimitra D; Dale, Roger G

2004-01-01

Advanced bio-simulation methods are expected to substantially improve radiotherapy treatment planning. To this end a novel spatio-temporal patient-specific simulation model of the in vivo response of malignant tumours to radiotherapy schemes has been recently developed by our group. This paper discusses recent improvements to the model: an optimized algorithm leading to conformal shrinkage of the tumour as a response to radiotherapy, the introduction of the oxygen enhancement ratio (OER), a realistic initial cell phase distribution and finally an advanced imaging-based algorithm simulating the neovascularization field. A parametric study of the influence of the cell cycle duration T c , OER, OER β for the beta LQ parameter on tumour growth, shrinkage and response to irradiation under two different fractionation schemes has been made. The model has been applied to two glioblastoma multiforme (GBM) cases, one with wild type (wt) and another one with mutated (mt) p53 gene. Furthermore, the model has been applied to a hypothetical GBM tumour with α and β values corresponding to those of generic radiosensitive tumours. According to the model predictions, a whole tumour with shorter T c tends to repopulate faster, as is to be expected. Furthermore, a higher OER value for the dormant cells leads to a more radioresistant whole tumour. A small variation of the OER β value does not seem to play a major role in the tumour response. Accelerated fractionation proved to be superior to the standard scheme for the whole range of the OER values considered. Finally, the tumour with mt p53 was shown to be more radioresistant compared to the tumour with wt p53. Although all simulation predictions agree at least qualitatively with the clinical experience and literature, a long-term clinical adaptation and quantitative validation procedure is in progress

Exogenous wild type p53 gene affects radiosensitivity of human lung adenocarcinoma cell line under hypoxia

International Nuclear Information System (INIS)

Wang Jianhua; Wang Feng; Liu Yongping; Zhang Yaping; Ni Yan; Li Shirong

2008-01-01

Objective: To evaluate the effect of exogenous wild type p53 (wtp53) gene on radiosensitivity of human lung adenocarcinoma cell line under hypoxia. Methods: Human lung adenocarcinoma cell line A549 was transfected with adenovirus carrying recombinant exogenous wtp53. Four irradiation groups were studied: normal cell (Group A), wtp53 transfected cell (Group B), normal cell under hypoxia (Group C) and wtp53 transfected cell under hypoxia(Group D). Cells were irradiated with 9 MeV electron beams. Cellular survival fraction was analyzed. Multi-target single-hit model was used to plot the survival curve. D 0 , D q , oxygen enhancement ratio (OER), sensitizing enhancement ratio (SER) and other parameters were used to evaluate the effects of wtp53 gene on radiosensitivity of A549. The cell apoptotic rate of each group was examined by flow cytometry. Results: OER was 1.75 and 0.81 before and after wtp53 transfection. SER was 1.77 in oxic circumstance and 3.84 under hypoxia. The cell apoptotic rate of Group A and B was lower than Group C and D (F=7.92, P=0.048), with Group A lower than B and Group C lower than D (F=82.50, P=0.001). But Group B and D were similar(t=2.04, P=0.111). Conclusions: Hypoxia can increase the radiation resistance of lung adenocarcinoma cell line A549. The wtp53 can promote apoptosis and improve tumor radiosensitivity, especially under hypoxia. (authors)

Calcium isotope ratios in animal and human bone

Science.gov (United States)

Reynard, L. M.; Henderson, G. M.; Hedges, R. E. M.

2010-07-01

Calcium isotopes in tissues are thought to be influenced by an individual's diet, reflecting parameters such as trophic level and dairy consumption, but this has not been carefully assessed. We report the calcium isotope ratios (δ 44/42Ca) of modern and archaeological animal and human bone ( n = 216). Modern sheep raised at the same location show 0.14 ± 0.08‰ higher δ 44/42Ca in females than in males, which we attribute to lactation by the ewes. In the archaeological bone samples the calcium isotope ratios of the herbivorous fauna vary by location. At a single site, the archaeological fauna do not show a trophic level effect. Humans have lower δ 44/42Ca than the mean site fauna by 0.22 ± 0.22‰, and the humans have a greater δ 44/42Ca range than the animals. No effect of sex or age on the calcium isotope ratios was found, and intra-individual skeletal δ 44/42Ca variability is negligible. We rule out dairy consumption as the main cause of the lower human δ 44/42Ca, based on results from sites pre-dating animal domestication and dairy availability, and suggest instead that individual physiology and calcium intake may be important in determining bone calcium isotope ratios.

ANALISIS PENGARUH LDR, NPL DAN OPERATIONAL EFFICIENCY RATIO TERHADAP RETURN ON ASSETS PADA BANK DEVISA DI INDONESIA PERIODE 2010-2012

OpenAIRE

Hamidah Hamidah; Goldan Merion Siallagan; Umi Mardiyati

2014-01-01

This research is performed on order to test analysis the influence of the Loan to Deposit Ratio (LDR), Non Performing Loan (NPL) and Operational Efficiency Ratio (OER) toward Return On Asset (ROA) On Foreign Exchange Banks In Indonesia Period 2010-2012. Methodology research as the sample used purposive sampling, samplewas accured fromforeign banks in Indonesia. Data analysis with multi liniearregression of ordinary least square and hypotheses test used t-statistic and Fstatistic, a classic as...

An Architecture Based on Linked Data Technologies for the Integration and Reuse of OER in MOOCs Context

Science.gov (United States)

Piedra, Nelson; Chicaiza, Janneth Alexandra; López, Jorge; Tovar, Edmundo

2014-01-01

The Linked Data initiative is considered as one of the most effective alternatives for creating global shared information spaces, it has become an interesting approach for discovering and enriching open educational resources data, as well as achieving semantic interoperability and re-use between multiple OER repositories. The notion of Linked Data…

Development of Refractory Ceramics for The Oxygen Evolution Reaction (OER) Electrocatalyst Support for Water Electrolysis at elevated temperatures

DEFF Research Database (Denmark)

Nikiforov, Aleksey; Prag, Carsten Brorson; Polonsky, J.

2012-01-01

Commercial TaC and Si3N4 powders were tested as possible electrocatalyst support materials for the Oxygen Evolution Reaction (OER) for PEM water electrolysers, operating at elevated temperatures. TaC and Si3N4 were characterised by thermogravimmetric and differential thermal analysis...

Reduced repair of potentially lethal radiation damage in glutathione synthetase-deficient human fibroblasts after X-irradiation

International Nuclear Information System (INIS)

Midander, J.; Revesz, L.; Deschavanne, P.J.; Debieu, D.; Malaise, E.P.

1986-01-01

Using a human fibroblast strain deficient in glutathione synthetase and a related proficient control strain, the role of glutathione (GSH) in repair of potentially lethal damage (PLD) has been investigated in determining survival by plating cells immediately or 24 h after irradiation. After oxic or hypoxic irradiation, both cell strains repair radiation-induced damage. However, under hypoxic conditions, the proficient cells repair PLD as well as under oxic conditions while the deficient cells repair less PLD after irradiation under hypoxic than under oxic conditions. Therefore, the oxygen enhancement ratio (o.e.r.) for proficient cells is similar whether the cells are plated immediately or 24 h later (2.0 and 2.13, respectively). In contrast, the o.e.r. for deficient cells is lower when the cells are plated 24 h after irradiation than when they are plated immediately thereafter (1.16 as compared to 1.55). The results indicate that GSH is involved in PLD repair and, in particular, in the repair of damage induced by radiation delivered under hypoxic conditions. (author)

OERs in Context--Case Study of Innovation and Sustainability of Educational Practices at the University of Mauritius

Science.gov (United States)

Issack, Santally Mohammad

2011-01-01

Over the recent years, there has been a growing interest in Open Educational Resources (OER). A similar trend was observed about a decade ago in the concept of Learning Objects, which inevitably faded without really making an impact in real-world educational contexts. A number of repositories were created that contain thousands of learning…

Re-Purposing an OER for the Online Language Course: A Case Study of "Deutsch Interaktiv" by the Deutsche Welle

Science.gov (United States)

Dixon, Edward M.; Hondo, Junko

2014-01-01

This paper will describe pedagogical approaches for re-purposing an open educational resource (OER) designed and produced by the Deutsche Welle. This free online program, "Deutsch Interaktiv," consists of authentic digital videos, slideshows and audio texts and gives a contemporary overview of the culture and language in Germany, Austria…

Tumour control in ion beam radiotherapy with different ions in the presence of hypoxia: an oxygen enhancement ratio model based on the microdosimetric kinetic model

Science.gov (United States)

Strigari, L.; Torriani, F.; Manganaro, L.; Inaniwa, T.; Dalmasso, F.; Cirio, R.; Attili, A.

2018-03-01

Few attempts have been made to include the oxygen enhancement ratio (OER) in treatment planning for ion beam therapy, and systematic studies to evaluate the impact of hypoxia in treatment with the beam of different ion species are sorely needed. The radiobiological models used to quantify the OER in such studies are mainly based on the dose-averaged LET estimates, and do not explicitly distinguish between the ion species and fractionation schemes. In this study, a new type of OER modelling, based on the microdosimetric kinetic model, taking into account the specificity of the different ions, LET spectra, tissues and fractionation schemes, has been developed. The model has been benchmarked with published in vitro data, HSG, V79 and CHO cells in aerobic and hypoxic conditions, for different ion irradiation. The model has been included in the simulation of treatments for a clinical case (brain tumour) using proton, lithium, helium, carbon and oxygen ion beams. A study of the tumour control probability (TCP) as a function of oxygen partial pressure, dose per fraction and primary ion type has been performed. The modelled OER depends on both the LET and ion type, also showing a decrease for an increased dose per fraction with a slope that depends on the LET and ion type, in good agreement with the experimental data. In the investigated clinical case, a significant increase in TCP has been found upon increasing the ion charge. Higher OER variations as a function of dose per fraction have also been found for low-LET ions (up to 15% varying from 2 to 8 Gy(RBE) for protons). This model could be exploited in the identification of treatment condition optimality in the presence of hypoxia, including fractionation and primary particle selection.

Exercise capacity in the Bidirectional Glenn physiology: Coupling cardiac index, ventricular function and oxygen extraction ratio.

Science.gov (United States)

Vallecilla, Carolina; Khiabani, Reza H; Trusty, Phillip; Sandoval, Néstor; Fogel, Mark; Briceño, Juan Carlos; Yoganathan, Ajit P

2015-07-16

In Bi-directional Glenn (BDG) physiology, the superior systemic circulation and pulmonary circulation are in series. Consequently, only blood from the superior vena cava is oxygenated in the lungs. Oxygenated blood then travels to the ventricle where it is mixed with blood returning from the lower body. Therefore, incremental changes in oxygen extraction ratio (OER) could compromise exercise tolerance. In this study, the effect of exercise on the hemodynamic and ventricular performance of BDG physiology was investigated using clinical patient data as inputs for a lumped parameter model coupled with oxygenation equations. Changes in cardiac index, Qp/Qs, systemic pressure, oxygen extraction ratio and ventricular/vascular coupling ratio were calculated for three different exercise levels. The patient cohort (n=29) was sub-grouped by age and pulmonary vascular resistance (PVR) at rest. It was observed that the changes in exercise tolerance are significant in both comparisons, but most significant when sub-grouped by PVR at rest. Results showed that patients over 2 years old with high PVR are above or close to the upper tolerable limit of OER (0.32) at baseline. Patients with high PVR at rest had very poor exercise tolerance while patients with low PVR at rest could tolerate low exercise conditions. In general, ventricular function of SV patients is too poor to increase CI and fulfill exercise requirements. The presented mathematical model provides a framework to estimate the hemodynamic performance of BDG patients at different exercise levels according to patient specific data. Published by Elsevier Ltd.

Herzberg, Hygiene and the Motivation to Reuse: Towards a Three-Factor Theory to Explain Motivation to Share and Use OER

Science.gov (United States)

Pegler, Chris

2012-01-01

The list of barriers and enablers that influence the use of open educational resources (OER) is extensive. Factors and influences relating to reuse may have been noted within projects, operating within a short time span, or within specific conditions which limit generalizability. Evidence of reuse in practice has often emerged as isolated examples…

Aspects of OER and RBE relevant to neutron therapy

International Nuclear Information System (INIS)

Field, S.B.; Hornsey, S.

1979-01-01

This chapter contains information concerning the mechanisms involved in neutron radiotherapy. Early studies on the attempts of using neutrons in radiotherapy are described. The rationale for fast neutron therapy is discussed as well as the relationships between OER and LET. Tissue responses include: repopulation of surviving cells; repair of sublethal damage; and slow repair. These mechanisms are considered separately. The relationships between RBE and dose per fraction for damage to skin, intestine, esophagus, lungs, hemopoietic tissue, and nerve tissue are discussed. Factors governing the effects of fractionation of dose in neutron radiotherapy are presented. Observations on mammalian cells and tissues show a general reduction in RBE with increasing neutron energy. The benefits of using mixed treatments, part with neutrons and the remainder with photons, are discussed. Problems with this approach include uncertainties of how the combination will effect normal tissue, how it effects slow repair, or its potentially lethal damage. Tumor response, as compared with x rays, to single and multiple doses of radiation is described. Clinical results are given

The Human Rights Key: An innovative tool for teaching health and ...

African Journals Online (AJOL)

I propose the Human Rights Key as a useful visual communication tool to guide students in connecting their classroom learning with the reality of local, regional and international health and human rights issues. As an OER with a Creative Commons licence, the Key is available online for both educators and students to use ...

Measurement of oxygen enhancement ratio for sub-lethal region using saccharomyces cerevisiae

International Nuclear Information System (INIS)

Nairy, Rajesha K.; Anjaria, K.B.; Bhat, Nagesh N.; Chaurasia, Rajesh K.; Balakrishnan, Sreedevi; Yerol, Narayana

2013-01-01

Oxygen is one of the best known modifiers of radiation sensitivity and the biological effects is greater in the presence of oxygen, and significant modifying effect will be observed only for low LET radiations. The reduced oxygen availability is sensed which trigger homeostatic responses, which impact on virtually all areas of biology and medicine. Failure to achieve complete response following radiotherapy of large tumors is attributed to the presence of radio-resistant hypoxic cells, therefore clarifying the mechanism of the oxygen effect is important. In the present study, a mutant type diploid yeast strain, Saccharomyces cerevisiae D7 was used to study Oxygen Enhancement Ratio (OER) using 60 Co gamma radiation. Cells were washed thrice by centrifugation (2000 g for 5 min) and re-suspended to a cell concentration of 1x108 cells mL-1 in a sterile polypropylene vial for irradiation (sub-lethal dose range, 0-100 Gy). Hypoxic conditions were achieved by incubating the cells in airtight vials at 30℃ for 30 min prior to irradiation. The gene conversion and back mutation analysis were carried out according to the standard protocol. Gene conversion is the radio-sensitive biological endpoint, that can be studied in Saccharomyces cerevisiae D7 yeast cells at trp locus in tryptophan (Trp- medium) deficient medium. The dose response relation at euoxic and hypoxic condition in sub-lethal doses are found to be linear and is represented by Y (Euoxic) = (6.54±0.102) D with R2=0.999 and for hypoxic condition Y(Hypoxic) = (3.346±0.033) D with R2=0.996. The OER can be calculated by dividing the euoxic slope with hypoxic slope, and is 1.95. Back mutation, which is a result of reversion of Isoleucine auxotrophs to prototrophs gives very good information at sub-lethal doses. The dose response relation between back mutated cells and radiation doses at Euoxic and hypoxic condition can be represented as Y(Euoxic) = (2.85±0.126) D with R2= 0.976 and for hypoxic condition Y

Determination of Relative Biological Efficacy (RBE) and Oxygen Enhancement Ratio (OER) for the entire negative and positive pion beam profile using Vicia faba roots and Drosophila embryos as biological model systems

International Nuclear Information System (INIS)

Baarli, J.; Bianchi, M.; Keusch, F.; Mindek, G.; Sullivan, A.H.

As an introduction to preclinical studies, pilot studies of pion beams are planned with relatively simple biological model systems that can be quickly evaluated and that yield indicative data for further action. Inhibition of growth was studied in Vicia faba roots, a biological system excellently suited for RBE and OER studies. For comparison there are already results from a low-intensity pion irradiation. A second system used Drosophila embryos 1 and 4 hours old, which are especially well suited for LET studies. The unambiguous criterion will be failure to slip out of the oolemma. The smallness of the objects (their beam sensitivity) will make it possible to determine empirically the peak region and to determine Gain factors; furthermore, the known dependency of RBE on the development stage promises highly informative results

Towards Development of OER Derived Custom-Built Open Textbooks: A Baseline Survey of University Teachers at the University of the South Pacific

Science.gov (United States)

Prasad, Deepak; Usagawa, Tsuyoshi

2014-01-01

Textbook prices have soared over the years, with several studies revealing many university students are finding it difficult to afford textbooks. Fortunately, two innovations--open educational resources (OER) and open textbooks--hold the potential to increase textbook affordability. Experts, though, have stated the obvious: that students can save…

The human heart: application of the golden ratio and angle.

Science.gov (United States)

Henein, Michael Y; Zhao, Ying; Nicoll, Rachel; Sun, Lin; Khir, Ashraf W; Franklin, Karl; Lindqvist, Per

2011-08-04

The golden ratio, or golden mean, of 1.618 is a proportion known since antiquity to be the most aesthetically pleasing and has been used repeatedly in art and architecture. Both the golden ratio and the allied golden angle of 137.5° have been found within the proportions and angles of the human body and plants. In the human heart we found many applications of the golden ratio and angle, in addition to those previously described. In healthy hearts, vertical and transverse dimensions accord with the golden ratio, irrespective of different absolute dimensions due to ethnicity. In mild heart failure, the ratio of 1.618 was maintained but in end-stage heart failure the ratio significantly reduced. Similarly, in healthy ventricles mitral annulus dimensions accorded with the golden ratio, while in dilated cardiomyopathy and mitral regurgitation patients the ratio had significantly reduced. In healthy patients, both the angles between the mid-luminal axes of the pulmonary trunk and the ascending aorta continuation and between the outflow tract axis and continuation of the inflow tract axis of the right ventricle approximate to the golden angle, although in severe pulmonary hypertension, the angle is significantly increased. Hence the overall cardiac and ventricular dimensions in a normal heart are consistent with the golden ratio and angle, representing optimum pump structure and function efficiency, whereas there is significant deviation in the disease state. These findings could have anatomical, functional and prognostic value as markers of early deviation from normality. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Getting past nature as a guide to the human sex ratio.

Science.gov (United States)

Murphy, Timothy F

2013-05-01

Sex selection of children by pre-conception and post-conception techniques remains morally controversial and even illegal in some jurisdictions. Among other things, some critics fear that sex selection will distort the sex ratio, making opposite-sex relationships more difficult to secure, while other critics worry that sex selection will tilt some nations toward military aggression. The human sex ratio varies depending on how one estimates it; there is certainly no one-to-one correspondence between males and females either at birth or across the human lifespan. Complications about who qualifies as 'male' and 'female' complicate judgments about the ratio even further. Even a judiciously estimated sex ratio does not have, however, the kind of normative status that requires society to refrain from antenatal sex selection. Some societies exhibit lopsided sex ratios as a consequence of social policies and practices, and pragmatic estimates of social needs are a better guide to what the sex ratio should be, as against looking to 'nature'. The natural sex ratio cannot be a sound moral basis for prohibiting parents from selecting the sex of their children, since it ultimately lacks any normative meaning for social choices. © 2011 Blackwell Publishing Ltd.

XPS and STEM study of the interface formation between ultra-thin Ru and Ir OER catalyst layers and perylene red support whiskers

Directory of Open Access Journals (Sweden)

Atanasoska Ljiljana L.

2013-01-01

Full Text Available The interface formation between nano-structured perylene red (PR whiskers and oxygen evolution reaction (OER catalysts ruthenium and iridium has been studied systematically by XPS and STEM. The OER catalyst over-layers with thicknesses ranging from ~0.1 to ~50 nm were vapor deposited onto PR ex-situ. STEM images demonstrate that, with increasing thickness, Ru and Ir transform from amorphous clusters to crystalline nanoparticles, which agglomerate with increased over-layer thickness. XPS data show a strong interaction between Ru and PR. Ir also interacts with PR although not to the extent seen for Ru. At low coverages, the entire Ru deposit is in the reacted state while a small portion of the deposited Ir remains metallic. Ru and Ir bonding occur at the PR carbonyl sites as evidenced by the attenuation of carbonyl photoemission and the emergence of new peak assigned to C-O single bond. The curve fitting analysis and the derived stoichiometry indicates the formation of metallo-organic bonds. The co-existence of oxide bonds is also apparent.

Sex ratio at birth and mortality rates are negatively related in humans.

Directory of Open Access Journals (Sweden)

Madhukar Shivajirao Dama

Full Text Available Evolutionary theory posits that resource availability and parental investment ability could signal offspring sex selection, in order to maximize reproductive returns. Non-human studies have provided evidence for this phenomenon, and maternal condition around the time of conception has been identified as most important factor that influence offspring sex selection. However, studies on humans have reported inconsistent results, mostly due to use of disparate measures as indicators of maternal condition. In the present study, the cross-cultural differences in human natal sex ratio were analyzed with respect to indirect measures of condition namely, life expectancy and mortality rate. Multiple regression modeling suggested that mortality rates have distinct predictive power independent of cross-cultural differences in fertility, wealth and latitude that were earlier shown to predict sex ratio at birth. These findings suggest that sex ratio variation in humans may relate to differences in parental and environmental conditions.

The potential pitfalls of studying adult sex ratios at aggregate levels in humans.

Science.gov (United States)

Pollet, Thomas V; Stoevenbelt, Andrea H; Kuppens, Toon

2017-09-19

Human adult sex ratios have been studied extensively across the biological and social sciences. While several studies have examined adult sex ratio effects in a multilevel perspective, many studies have focused on effects at an aggregated level only. In this paper, we review some key issues relating to such analyses. We address not only nation-level analyses, but also aggregation at lower levels, to investigate whether these issues extend to lower levels of aggregation. We illustrate these issues with novel databases covering a broad range of variables. Specifically, we discuss distributional issues with aggregated measures of adult sex ratio, significance testing, and statistical non-independence when using aggregate data. Firstly, we show that there are severe distributional issues with national adult sex ratio, such as extreme cases. Secondly, we demonstrate that many 'meaningless' variables are significantly correlated with adult sex ratio (e.g. the max. elevation level correlates with sex ratio at US state level). Finally, we re-examine associations between adult sex ratios and teenage fertility and find no robust evidence for an association at the aggregate level. Our review highlights the potential issues of using aggregate data on adult sex ratios to test hypotheses from an evolutionary perspective in humans.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'. © 2017 The Author(s).

Reduced oxygen enhancement ratio at low doses

International Nuclear Information System (INIS)

Palcic, B.; Skarsgard, L.D.

1984-01-01

The oxygen depletion rate in cell suspensions was measured using a Clark electrode. It was found that under experimental conditions used in this laboratory for hypoxic irradiations, the oxygen levels before the start of irradiation are always below 0.1μm, the levels which could give any significant enhancement to radiation inactivation by x-rays. The measured O/sub 2/ depletion rates were comparable to those reported in the literature. Chinese hamster cells (CHO) were made hypoxic by gas exchange, combined with metabolic consumption of oxygen by cells at 37 0 C. Full survival curves were determined in the dose range 0 to 3Gy using the low dose survival assay. The results confirmed the authors' earlier finding that the OER decreases at low doses. The authors therefore believe that the dose-dependent OER is a true radiobiological phenomenon and not an artifact of the experimental method used in the low dose survival assay

Cloning of a cDNA encoding chitotriosidase, a human chitinase produced by macrophages

NARCIS (Netherlands)

Boot, R. G.; Renkema, G. H.; Strijland, A.; van Zonneveld, A. J.; Aerts, J. M.

1995-01-01

We have recently observed that chitotriosidase, a chitinolytic enzyme, is secreted by activated human macrophages and is markedly elevated in plasma of Gaucher disease patients (Hollak, C. E. M., van Weely, S., van Oers, M. H. J., and Aerts, J. M. F. G. (1994) J. Clin. Invest. 93, 1288-1292). Here,

Postmortem study of stable carbon isotope ratios in human cerebellar DNA: preliminary results

International Nuclear Information System (INIS)

Slatkin, D.N.; Irsa, A.P.; Friedman, L.

1978-01-01

It is observed that 13 C/ 12 C ratios in tissue specimens removed postmortem in the United States and Canada are significantly different from corresponding ratios in European specimens. On the basis of this information, measurements of carbon isotope ratios in DNA isolated from cerebella of native-born and European-born North Americans are in progress with the goal of estimating the average lifetime rate of DNA turnover in human neurons. Preliminary results from twenty postmortem examinations are consistent with the hypothesis that a significant proportion of human cerebellar DNA is renewed during the lifetime of an individual

Reduction in OER with LET: evidence supporting the ''oxygen-in-the-track'' hypothesis

International Nuclear Information System (INIS)

Bryant, P.E.

1976-01-01

To account for the reduction in OER with increasing LET which is observed for a wide variety of cell systems. Neary (1965) invoked the hypothesis that molecular oxygen is generated within the particle tracks of the more densely ionizing radiations. With the proviso that the product generated may be a species other than oxygen, but with similar sensitizing properties, produced by different qualities of radiation in two different organisms: the alga Chlamydomonas reinhardii and the bacterium Shigella flexneri were calculated. These effective concentrations should be the same for any given quality if the formation of the product is a function only of physico-chemical events occurring within the tracks of particles, and is independent of the biological material in which energy deposition is taking place. A prerequisite for the calculation of effective amounts of oxygen in tracks of ionizing particles is a knowledge of how radiosentivity varies with oxygen concentration at low LET

Developing a Pedagogy of Mutuality in a Capability Approach: Teachers' Experiences of Using the Open Educational Resources (OER) of the Teacher Education in Sub-Saharan Africa (TESSA) Programme

Science.gov (United States)

Murphy, Patricia; Wolfenden, Freda

2013-01-01

The TESSA (teacher education in sub Saharan Africa) programme aims to improve teacher education at scale by developing open educational resources (OER) that allow sustainable and locally managed pedagogical change in higher education institutions and schools. The article offers a sociocultural theoretical rationale for the pedagogy of mutuality…

Analysis of PLEs' Implementation under OER Design as a Productive Teaching-Learning Strategy in Higher Education. A Case Study at Universidad Nacional de Educación a Distancia

Science.gov (United States)

Vázquez-Cano, Esteban; Martín-Monje, Elena; Castrillo de Larreta-Azelain, María Dolores

2016-01-01

This paper shows some research which analysed the didactic functionality of Personal Learning Environments (PLEs) and Open Educational Resources (OERs). They were created by students from the Master's Degree in Information and Communication Technologies applied to language teaching and processing, at Universidad Nacional de Educación a Distancia…

The potential pitfalls of studying adult sex ratios at aggregate levels in humans

NARCIS (Netherlands)

Pollet, Thomas V.; Stoevenbelt, Andrea H.; Kuppens, Toon

2017-01-01

Human adult sex ratios have been studied extensively across the biological and social sciences. While several studies have examined adult sex ratio effects in a multilevel perspective, many studies have focused on effects at an aggregated level only. In this paper, we review some key issues relating

Toxicity of 125-I in cultured cells and tumour bearing mice. Part of a coordinated programme on radiation biology of Auger emitters and their therapeutic applications

International Nuclear Information System (INIS)

Tisljar-Lentulis, G.

1980-09-01

To clarify the mechanism of induction of cell killing by Auger phenomena in DNA, the oxygen effect on cell killing and strand-breaks from decay of DNA bound 125 I was studied in human kidney T cells and compared with effects of 3 H incorporated in DNA. Oxygen enhancement ratios (OER) for 60 Co γ-rays, 3 H-TdR, 3 H-IUdR and 125 I-UdR changed 1.2 to 4.5 for SSBs, 1.4 to 3.9 for DSBs, and 1.0 to 2.8 for survival, respectively. The most conspicuous results were the OER for SSBs induced by 3 H-TdR which amounts to only about 1.6. It can be considered to be an effect of the transmutation from 3 H to 3 He. In addition, for both strand breaks and cell survival after incorporation of 125 I-UdR, OER-values of virtually 1 were found. This means that 125 I-UdR incorporated in human kidney T-cells does not show any oxygen effect for survival. The high radiobiological effectiveness may be caused by the emission of the high number of low energy electrons causing a high density of ionization in the immediate neighbourhood of the decay

Paternal effects on the human sex ratio at birth: evidence from interracial crosses.

Science.gov (United States)

Khoury, M J; Erickson, J D; James, L M

1984-01-01

The effects of interracial crossing on the human sex ratio at birth were investigated using United States birth-certificate data for 1972-1979. The sex ratio was 1.059 for approximately 14 million singleton infants born to white couples, 1.033 for 2 million born to black couples, and 1.024 for 64,000 born to American Indian couples. Paternal and maternal race influences on the observed racial differences in sex ratio were analyzed using additional data on approximately 97,000 singleton infants born to white-black couples and 60,000 born to white-Indian couples. After adjustment for mother's race, white fathers had significantly more male offspring than did black fathers (ratio of sex ratios [RSR] = 1.027) and Indian fathers (RSR = 1.022). On the other hand, after adjustment for father's race, white mothers did not have more male offspring than did black mothers (RSR = 0.998) or Indian mothers (RSR = 1.009). The paternal-race effect persisted after adjustment for parental ages, education, birth order, and maternal marital status. The study shows that the observed racial differences in the sex ratio at birth are due to the effects of father's race and not the mother's. The study points to paternal determinants of the human sex ratio at fertilization and/or of the prenatal differential sex survival. PMID:6496474

Concentrations of trace elements in human tissues and relation of ratios of mutual metals to the human health

International Nuclear Information System (INIS)

Ling-wei, X.; Shao-xian, L.; Xiao-juan, Z.

1989-01-01

According to the experimental results, the concentrations and concentrations in order, of trace elements in human tissues among Changsha's People in China are reported. The authors particularly present that the ratios of mutual metals (M/N) in normal physiological tissues and fluids are very important factors which indicate the metabolic situations of trace elements in the body and as the indices which evaluate the situation of human health. (M and N mean the concentrations of different trace elements in the tissues or fluids, respectively.) Up to now, it is still an interesting field to study the functions of trace elements for the human health. There are previously some reports about the concentrations of trace elements in normal physiological tissues/ or organs and fluids of human body. These provide very valuable data for biological medicine. In the study presented atomic absorption method was adopted in order to determine the concentrations of Zn, Cu, Mn, Ni, Pb and Cd in human tissues (liver, spleen, kidney, bone, lung, pancreas, heart and artery and muscle) at autopsy. The authors suggest that trace elements, are contained in the body in an aproportional way, in normal physiological tissues and fluids, and the ratios may directly indicate metabolic situation of trace elements in the body which further reveal the mystery of trace elements for human health. Therefore, the ratios M/N as an indicator of health is more proper than that only using concentrations of trace elements. Schroeder (1973) reported that incidence of heart disease is related to the imbalance of ration Zn/Cd and Zn/Cu rather than the concentrations of Zn, Cd, Cu, and the intellectual development also depends on the proper proportion among copper, cadmium, lead, zinc in the body

Biometrics from the carbon isotope ratio analysis of amino acids in human hair.

Science.gov (United States)

Jackson, Glen P; An, Yan; Konstantynova, Kateryna I; Rashaid, Ayat H B

2015-01-01

This study compares and contrasts the ability to classify individuals into different grouping factors through either bulk isotope ratio analysis or amino-acid-specific isotope ratio analysis of human hair. Using LC-IRMS, we measured the isotope ratios of 14 amino acids in hair proteins independently, and leucine/isoleucine as a co-eluting pair, to provide 15 variables for classification. Multivariate analysis confirmed that the essential amino acids and non-essential amino acids were mostly independent variables in the classification rules, thereby enabling the separation of dietary factors of isotope intake from intrinsic or phenotypic factors of isotope fractionation. Multivariate analysis revealed at least two potential sources of non-dietary factors influencing the carbon isotope ratio values of the amino acids in human hair: body mass index (BMI) and age. These results provide evidence that compound-specific isotope ratio analysis has the potential to go beyond region-of-origin or geospatial movements of individuals-obtainable through bulk isotope measurements-to the provision of physical and characteristic traits about the individuals, such as age and BMI. Further development and refinement, for example to genetic, metabolic, disease and hormonal factors could ultimately be of great assistance in forensic and clinical casework. Copyright © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

Use of 14CO2 ratios in metabolic assessment of human spermatozoa

International Nuclear Information System (INIS)

Holleran, A.L.; Mendez, C.M.; Kelleher, J.K.; Naz, R.K.

1987-01-01

Comparison of 14 CO 2 production for [1- 14 C], [2- 14 C] and [3- 14 C] pyruvate indicates the metabolic fate of pyruvate. Assuming that all pyruvate oxidized enters the TCA cycle via pyruvate dehydrogenase, the ratio of steady state 14 CO 2 production, [2- 14 C] pyruvate: [3- 14 C] pyruvate, determines the probability that specific citrate carbons will complete a turn of the TCA cycle. Comparing this probability and the 14 CO 2 production from [1- 14 C] pyruvate estimates the flux pyruvate to products derived from acetate that do not enter the TCA cycle. Data was collected for human sperm metabolizing glutamine and pyruvate over a four-hour period. The ratio of 14 CO 2 production, [2- 14 C] pyruvate: [3- 14 C] pyruvate even when correction was made for the fact that not all carbon derived from [2- 14 C] pyruvate that enters the TCA cycle is converted to CO 2 . 14 CO 2 production from [U- 14 C] glutamine was linear for glutamine concentration below 0.5 mM. In conclusion, CO 2 ratios methods are applicable in metabolic analysis of small samples of human sperm where metabolite measurements are impractical

Cell sensitivity to irradiation and DNA repair processes

International Nuclear Information System (INIS)

Kozubek, S.; Krasavin, E.A.

1984-01-01

A new model of oxygen effect realisation is proposed for E.coli cells. The model explains differencies in oxygen enhancement ratio (OER) between wild type cells and repair deficient mutants. These differencies are logically linked to corresponding defects in repair systems. A quantitative analysis has been performed. The dependence of OER and cell sensitivity on the properties of cultivation medium is considered, too. Decreasing OER and increasing sensitivity in poor conditions are explained as the consequence of the shift of repair capacity from slow to fast repair system

Abnormal X : autosome ratio, but normal X chromosome inactivation in human triploid cultures

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Norwood Thomas H

2006-07-01

Full Text Available Abstract Background X chromosome inactivation (XCI is that aspect of mammalian dosage compensation that brings about equivalence of X-linked gene expression between females and males by inactivating one of the two X chromosomes (Xi in normal female cells, leaving them with a single active X (Xa as in male cells. In cells with more than two X's, but a diploid autosomal complement, all X's but one, Xa, are inactivated. This phenomenon is commonly thought to suggest 1 that normal development requires a ratio of one Xa per diploid autosomal set, and 2 that an early event in XCI is the marking of one X to be active, with remaining X's becoming inactivated by default. Results Triploids provide a test of these ideas because the ratio of one Xa per diploid autosomal set cannot be achieved, yet this abnormal ratio should not necessarily affect the one-Xa choice mechanism for XCI. Previous studies of XCI patterns in murine triploids support the single-Xa model, but human triploids mostly have two-Xa cells, whether they are XXX or XXY. The XCI patterns we observe in fibroblast cultures from different XXX human triploids suggest that the two-Xa pattern of XCI is selected for, and may have resulted from rare segregation errors or Xi reactivation. Conclusion The initial X inactivation pattern in human triploids, therefore, is likely to resemble the pattern that predominates in murine triploids, i.e., a single Xa, with the remaining X's inactive. Furthermore, our studies of XIST RNA accumulation and promoter methylation suggest that the basic features of XCI are normal in triploids despite the abnormal X:autosome ratio.

Radiation biophysical studies with mammalian cells and a modulated carbon ion beam

International Nuclear Information System (INIS)

Chapman, J.D.; Blakely, E.A.; Smith, K.C.; Urtasun, R.C.; Lyman, J.T.; Tobias, C.A.

1978-01-01

Chinese hamster (V-79) and human kidney (T-1) cells were irradiated in stirred suspensions placed at various positions in the plateau and extended Bragg peak of a 400-MeV/amu carbon ion beam. The range of the ions was modulated by a lead (translational) ridge filter and a brass (spiral) ridge filter designed to produce extended peaks of approximately 4 and 10 cm, respectively. Stationary-phase and G 1 -phase populations of Chinese hamster cells were found to have different absolute radiosensitivities which, in turn, were different from that of asynchronous human kidney cells. The increase in relative biological effectiveness (RBE) observed as carbon ions were slowed down and stopped in water was similar for the three cell populations at doses greater than 400 rad. At lower doses the RBE was greater for the hamster cell populations than for the human kidney cells. The gain in RBE (at the 50% survival level) between the plateaus and the middle region of the extended peaks was approximately 2.0 and 1.7 for the 4- and 10-cm extended peaks, respectively. Oxygen enhancement ratios (OER) were determined at the 10% survival levels with stationary-phase populations of hamster cells. Values of 2.8, 2.65, and 1.65 were obtained for the OER of 220-kV x rays, plateau carbon, and the middle region of the 4-cm carbon peak, respectively. Across the 10-cm carbon peak the OER was found to vary between values of 2.4 to 1.55 from the proximal to distal positions

Neutron activation analysis of calcium/phosphorus ratio in rib bone of healthy humans

International Nuclear Information System (INIS)

Tzaphlidou, Margaret; Zaichick, Vladimir

2002-01-01

The Ca/P ratio was estimated in intact rib bone samples from healthy humans, 37 women and 45 men, aged from 15 to 55 years using instrumental neutron activation analysis. No statistically significant differences (p>0.05) age- or sex-related differences in the Ca/P ratio were observed. The mean value (M±SD) for the investigated parameter for the whole group studied, 2.33±0.34, was within a very wide range of published data and close to the median value

Oxygen as a product of water radiolysis in high-LET tracks. II. Radiobiological implications

International Nuclear Information System (INIS)

Baverstock, K.F.; Burns, W.G.

1981-01-01

Consideration is given to the possibility that molecular oxygen generated in the tracks of energetic heavy ions is responsible for the reduction in oxygen enhancement ratio (OER) with increasing linear energy transfer (LET) observed for the loss of reproductive capacity caused by radiation in many cellular organisms. Yields of oxygen relationship of OER to LET for two organisms, Chlamydomonas reinhardii and Shigella flexneri, using a simple diffusion kinetic model for radiobiological action which takes account of the diffusion of oxygen after its formation. The results of these calculations show that the model accounts well for the shape of the OER vs. LET relationship

Effects of oxygen on intrinsic radiation sensitivity: A test of the relationship between aerobic and hypoxic linear-quadratic (LQ) model parameters

International Nuclear Information System (INIS)

Carlson, David J.; Stewart, Robert D.; Semenenko, Vladimir A.

2006-01-01

The poor treatment prognosis for tumors with high levels of hypoxia is usually attributed to the decreased sensitivity of hypoxic cells to ionizing radiation. Mechanistic considerations suggest that linear quadratic (LQ) survival model radiosensitivity parameters for hypoxic (H) and aerobic (A) cells are related by α H =α A /oxygen enhancement ratio (OER) and (α/β) H =OER(α/β) A . The OER parameter may be interpreted as the ratio of the dose to the hypoxic cells to the dose to the aerobic cells required to produce the same number of DSBs per cell. The validity of these expressions is tested against survival data for mammalian cells irradiated in vitro with low- and high-LET radiation. Estimates of hypoxic and aerobic radiosensitivity parameters are derived from independent and simultaneous least-squares fits to the survival data. An external bootstrap procedure is used to test whether independent fits to the survival data give significantly better predictions than simultaneous fits to the aerobic and hypoxic data. For low-LET radiation, estimates of the OER derived from the in vitro data are between 2.3 and 3.3 for extreme levels of hypoxia. The estimated range for the OER is similar to the oxygen enhancement ratios reported in the literature for the initial yield of DSBs. The half-time for sublethal damage repair was found to be independent of oxygen concentration. Analysis of patient survival data for cervix cancer suggests an average OER less than or equal to 1.5, which corresponds to a pO 2 of 5 mm Hg (0.66%) in the in vitro experiments. Because the OER derived from the cervix cancer data is averaged over cells at all oxygen levels, cells irradiated in vivo under extreme levels of hypoxia (<0.5 mm Hg) may have an OER substantially higher than 1.5. The reported analyses of in vitro data, as well as mechanistic considerations, provide strong support for the expressions relating hypoxic and aerobic radiosensitivity parameters. The formulas are also useful

PENGARUH RASIO KESEHATAN BANK TERHADAP KINERJA KEUANGAN BANK SYARIAH PERIODE 2010-2013

Directory of Open Access Journals (Sweden)

Iwan Fakhruddin

2015-09-01

Full Text Available The research was aimed to analyze the effect of risk base bank ratio to the financial performance of syariah bank listed in Central Bank of Indonesia. The population covered all syariah Bank and the sample was 11 syariah Bank. Then, the data analyze through double regression. The research showed that Capital Adequacy Ratio (CAR, Non Performing Ratio (NPF, Operational efficiency Ratio (OER, Financing to Deposit Ratio (FDR, Quality of Productive Active (KAP effected simultaneously to Return of Asset (ROA. CAR variable had positive and significant effects to ROA. NPF contributed negative and significant effects to ROA. OER comprised negative and significant effect to ROA. FDR had positive and significant effect to ROA. KAP got negative and significant effect to ROA.

Abnormal sex ratios in human populations: causes and consequences.

Science.gov (United States)

Hesketh, Therese; Xing, Zhu Wei

2006-09-05

In the absence of manipulation, both the sex ratio at birth and the population sex ratio are remarkably constant in human populations. Small alterations do occur naturally; for example, a small excess of male births has been reported to occur during and after war. The tradition of son preference, however, has distorted these natural sex ratios in large parts of Asia and North Africa. This son preference is manifest in sex-selective abortion and in discrimination in care practices for girls, both of which lead to higher female mortality. Differential gender mortality has been a documented problem for decades and led to reports in the early 1990s of 100 million "missing women" across the developing world. Since that time, improved health care and conditions for women have resulted in reductions in female mortality, but these advances have now been offset by a huge increase in the use of sex-selective abortion, which became available in the mid-1980s. Largely as a result of this practice, there are now an estimated 80 million missing females in India and China alone. The large cohorts of "surplus" males now reaching adulthood are predominantly of low socioeconomic class, and concerns have been expressed that their lack of marriageability, and consequent marginalization in society, may lead to antisocial behavior and violence, threatening societal stability and security. Measures to reduce sex selection must include strict enforcement of existing legislation, the ensuring of equal rights for women, and public awareness campaigns about the dangers of gender imbalance.

Radiation killing of E. coli K1060: role of membrane fluidity, hypothermia and local anaesthetics

International Nuclear Information System (INIS)

Yatvin, M.B.; Schmitz, B.J.; Dennis, W.H.

1980-01-01

The enhancement of killing by γ irradiation, which is seen when E. coliK1060 are cooled below the transition temperature of their membrane lipids, is blocked by procaine-HCl. These data are consistent with the hypothesis that increased killing associated with irradiation at 0 0 C is the result of membrane microviscosity increases, since procaine is known to fluidize membranes. A cooling enhancement ratio (c.e.r.) is defined as the ratio of radiation D 0 at 22 0 C to its value at 0 0 C. The c.e.r. for oxygen-bubbled cells is 1.5 and for nitrogen-bubbled cells is 2.1. In the presence of 25mM procaine the respective c.e.r. values are 1.08 and 1.29. The oxygen enhancement ratio (o.e.r.) at 22 0 C is 3.43 and at 0 0 C is 2.45. The addition of procaine does not change the o.e.r. Thus, the temperature effect on o.e.r. does not appear to be related to membrane fluidity. (author)

Screening Test for Shed Skin Cells by Measuring the Ratio of Human DNA to Staphylococcus epidermidis DNA.

Science.gov (United States)

Nakanishi, Hiroaki; Ohmori, Takeshi; Hara, Masaaki; Takahashi, Shirushi; Kurosu, Akira; Takada, Aya; Saito, Kazuyuki

2016-05-01

A novel screening method for shed skin cells by detecting Staphylococcus epidermidis (S. epidermidis), which is a resident bacterium on skin, was developed. Staphylococcus epidermidis was detected using real-time PCR. Staphylococcus epidermidis was detected in all 20 human skin surface samples. Although not present in blood and urine samples, S. epidermidis was detected in 6 of 20 saliva samples, and 5 of 18 semen samples. The ratio of human DNA to S. epidermidisDNA was significantly smaller in human skin surface samples than in saliva and semen samples in which S. epidermidis was detected. Therefore, although skin cells could not be identified by detecting only S. epidermidis, they could be distinguished by measuring the S. epidermidis to human DNA ratio. This method could be applied to casework touch samples, which suggests that it is useful for screening whether skin cells and human DNA are present on potential evidentiary touch samples. © 2016 American Academy of Forensic Sciences.

MOOC, OER e l’approccio “flipped classroom”: due case study di transizione in ambito scolastico e aziendale

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Susanna Sancassani

2014-08-01

Full Text Available La portata innovativa dei MOOC non esaurisce la sua rilevanza nell’ambito dei processi di apprendimento che si svolgono in rete. Uno dei principali obiettivi che ha mosso grandi università quali Stanford o MIT ad impegnarsi prima nello sviluppo di OER (Open Educational Resources e poi nei MOOC, è stato quello di trovare modalità che consentissero di migliorare la qualità didattica face-to-face riducendone i costi. In questa prospettiva i materiali didattici online stanno ora consentendo di sperimentare la metodologia delle “flipped classroom” in cui le dinamiche didattiche in aula sono basate su un’elevata interattività con i docenti e tra i pari. Nell’articolo si analizzano due progetti inseriti in differenti contesti, quello scolastico e quello aziendale, basati su un approccio “flipped”. I risultati in termini di efficacia appaiono confortanti, ma ancora più promettenti sono i riflessi sulla sostenibilità dei processi e sui livelli di motivazione di docenti e studenti.

The intent to exercise influences the cerebral O(2)/carbohydrate uptake ratio in humans

DEFF Research Database (Denmark)

Dalsgaard, Mads K; Ide, Kojiro; Cai, Yan

2002-01-01

During and after maximal exercise there is a 15-30 % decrease in the metabolic uptake ratio (O(2)/[glucose + 1/2 lactate]) and a net lactate uptake by the human brain. This study evaluated if this cerebral metabolic uptake ratio is influenced by the intent to exercise, and whether a change could......, the a-v difference for the amino acids and glycerol did not change significantly, and there was only a minimal increase in the a-v difference for free fatty acids after maximal exercise. After maximal exercise the metabolic uptake ratio of the brain decreased from 6.1 +/- 0.5 (mean +/- S.E.M.) at rest.......2) in the early recovery (n = 10; P brain are increased out of proportion to O(2) when the brain is activated by exhaustive exercise, and that such metabolic changes are influenced by the will to exercise. We speculate that the uptake ratio...

Role of oxygen in enhancement in repair of radiation injuries in Tribolium

International Nuclear Information System (INIS)

Ng, M.C.

1977-01-01

The oxygen enhancement ratio (OER) was determined for various biological responses in Tribolium confusum McGill Black. The biological responses included acute lethality of the adults and larvae; sexual sterilization of the male and female adults; fecundity of the females and hatchability of their eggs as well as the competitiveness of the males. The OER for acute lethality for the male and female adults was found to be 2.25-2.38, regardless of the type of inert gas used to achieve anaerobiosis. Acute lethality for the larvae showed an OER of 2.79. The OER for male and female sexual sterilization was 2.35 and 3.37 respectively. With irradiation carried out in oxygen, the results suggested that at the tissue level of the adults and the male reproductive organ, there is a certain degree of hypoxia. Sexual sterilization of the males by radiation is attributed to the induction of dominant lethal mutation in the sperms, and that of the females involves a combination of dominant lethals and decreased egg production. The OER for egg hatchability at a hatchability level of 50% of the control for irradiated females was 4.0, a surprisingly higher value than that of any other biological responses studied. The OER for fecundity of irradiated females and for male competitiveness were roughly estimated to be 2.8 and 2.3-2.7 respectively. Since the OER for male sexual sterilization is basically the same as that for acute lethality for adults, it is expected that the competitiveness, which depends on the amount of somatic damage by radiation, will not be protected to a much greater extent by anaerobic irradiation than sterilization. It is clearly demonstrated that OER values are specific for the particular end point scored. Even within the same organism, different OER can be obtained with different biological responses

Positron emission tomography in minor ischemic stroke using oxygen-15 steady-state technique

International Nuclear Information System (INIS)

Pozzilli, C.; Itoh, M.; Matsuzawa, T.; Fukuda, H.; Abe, Y.; Sato, T.; Takeda, S.; Ido, T.

1987-01-01

A study with positron emission tomography (PET) was performed on 10 patients with ischemic stroke and mild disability. The patients underwent cerebral angiography, x-ray computed tomography (CT) scan and regional cerebral measurements of CBF, CMRO2, oxygen extraction ratio (OER), and cerebral blood volume (CBV). Only minor arterial involvement was detected by angiography. In all patients, PET images of functional defects were more extensive than the corresponding CT hypodensity, and there were statistically significant reductions in CBF, CMRO2, and CBF/CBV ratio as compared with control subjects. Half of the regions analyzed in the affected hemisphere demonstrated a disruption of the normal coupling between CBF and CMRO2 as reflected by OER values significantly higher or lower than those of the corresponding region of the contralateral hemisphere. The pathophysiological pattern of high OER combined with a reduction in CBF proportionally greater than the reduction in CMRO2 was particularly indicative of regional chronic hemodynamic compromise in these patients

Hypoxic cell radiosensitization by moderate hyperthermia and glucose deprivation

International Nuclear Information System (INIS)

Kim, J.H.; Kim, S.H.; Hahn, E.W.

1983-01-01

Cell culture studies were carried out to determine whether moderate hyperthermia reduces the oxygen enhancement ratio of cells under well-defined cultural conditions. Using asynchronously growing HeLa cells, the OER of cells with and without glucose was determined following exposure of cells to moderate hyperthermia, 40.5omicronC for 1 hr, immediately after X irradiation. The OER of cells with 5 mM glucose was 3.2, whereas the OER of glucose-deprived cells was reduced to 2.0. The pH of the cell culture medium was kept at 7.4 throughtout the experiments. The present finding may provide a clue toward further enhancing the radiosensitization of hypoxic cells by heat

Hypoxic cell radiosensitization by moderate hyperthermia and glucose deprivation

International Nuclear Information System (INIS)

Kim, J.H.; Kim, S.H.; Hahn, E.W.

1983-01-01

Cell culture studies were carried out to determine whether moderate hyperthermia reduces the oxygen enhancement ratio of cells under well-defined cultural conditions. Using asynchronously growing HeLa cells, the OER of cells with and without glucose was determined following exposure of cells to moderate hyperthermia, 40.5 degrees C for 1 hr, immediately after X irradiation. The OER of cells with 5 mM glucose was 3.2, whereas the OER of glucose-deprived cells was reduced to 2.0. The pH of the cell culture medium was kept at 7.4 throughout the experiments. The present finding may provide a clue toward further enhancing the radiosensitization of hypoxic cells by heat

Enantiomeric ratios as an indicator of exposure processes for persistent pollutants in human placentas

DEFF Research Database (Denmark)

Shen, Heqing; Virtanen, H E; Main, Katharina M

2006-01-01

The enantiomeric ratios (ER) of alpha-HCH and o,p'-DDT ((+)-isomer concentration/(-)-isomer concentration) and o,p'-DDD (first eluting enantiomer/second enantiomer) were investigated in 112 human placentas from Finnish boys collected 1997-2001. Both o,p'-DDD and alpha-HCH showed changes in their ER...

Survival of V79 cells after low doses of X-rays

International Nuclear Information System (INIS)

Watts, M.E.; Fowler, J.F.; Hodgkiss, R.J.; Jones, N.R.

1984-01-01

Doses of X-rays of the order 1-3 Gy are used in clinical multifraction regimes. Reduction in oxygen enhancement ratios (OER) and sensitizer enhancement ratios have been reported for CHO cells. The errors in determining low levels of cell kill are largely influenced by sampling and dilution errors. The authors have aimed to reduce these errors by increasing the sample size and reducing dilutions. To further assess the uncertainties involved in these experiments the data were pooled from three independent series of experiments. Asynchronous log phase Chinese hamster lung fibroblast cells have been irradiated attached to glass Petri dishes in Eagle's MEM + 10% fcs at a dose rate of 0.61 Gy min/sup -1/ under air + 5% CO/sub 2/ or nitrogen + 5% CO/sub 2/ at 18 0 C. Survival in the range 10/sup -1/ to 5 x 10/sup -3/ surviving fraction (SF) was identical at 0.61 Gy min/sup -1/ and 3.93 Gy min/sup -1/. Many previous experiments have given an OER = 3.1 at 10/sup -2/-10/sup -3/ survival. Least squares fit to the linear quadratic function log S = -(αD + βD/sup 2/) gave an OER≅3.2 at SF = 10/sup -2/. Below 6 Gy air dose (>0.2 SF) OER was reduced, but was still ≅ 2.4 at 2 Gy. The linear quadratic function gave an OER for a ≅ 1.5 (the limiting low-dose OER) and √β≅3.2

Partial oxidation of municipal sludge with activited carbon catalyst in supercritical water

International Nuclear Information System (INIS)

Guo Yang; Wang Shuzhong; Gong Yanmeng; Xu Donghai; Tang Xingying; Ma Honghe

2010-01-01

The partial oxidation (POX) characteristics of municipal sludge in supercritical water (SCW) were investigated by using batch reactor. Effects of reaction parameters such as oxidant equivalent ratio (OER), reaction time and temperature were investigated. Activated carbon (AC) could effectively improve the mole fraction of H 2 in gas product at low OER. However, high OER (greater than 0.3) not only led to the combustion reaction of CO and H 2 , but also caused corrosion of reactor inner wall. Hydrogenation and polymerization of the intermediate products are possible reasons for the relative low COD removal rate in our tests. Metal oxide leached from the reactor inner wall and the main components of the granular sludge were deposited in the AC catalyst. Reaction time had more significant effect on BET surface area of AC than OER had. Long reaction time led to the methanation reaction following hydrolysis and oxidation reaction of AC in SCW in the presence of oxygen. Correspondingly, the possible reaction mechanisms were proposed.

Resistance of hypoxic cells to ionizing radiation is influenced by homologous recombination status

International Nuclear Information System (INIS)

Sprong, Debbie; Janssen, Hilde L.; Vens, Conchita; Begg, Adrian C.

2006-01-01

Purpose: To determine the role of DNA repair in hypoxic radioresistance. Methods and Materials: Chinese hamster cell lines with mutations in homologous recombination (XRCC2, XRCC3, BRAC2, RAD51C) or nonhomologous end-joining (DNA-PKcs) genes were irradiated under normoxic (20% oxygen) and hypoxic (<0.1% oxygen) conditions, and the oxygen enhancement ratio (OER) was calculated. In addition, Fanconi anemia fibroblasts (complementation groups C and G) were compared with fibroblasts from nonsyndrome patients. RAD51 foci were studied using immunofluorescence. Results: All hamster cell lines deficient in homologous recombination showed a decrease in OER (1.5-2.0 vs. 2.6-3.0 for wild-types). In contrast, the OER for the DNA-PKcs-deficient line was comparable to wild-type controls. The two Fanconi anemia cell strains also showed a significant reduction in OER. The OER for RAD51 foci formation at late times after irradiation was considerably lower than that for survival in wild-type cells. Conclusion: Homologous recombination plays an important role in determining hypoxic cell radiosensitivity. Lower OERs have also been reported in cells deficient in XPF and ERCC1, which, similar to homologous recombination genes, are known to play a role in cross-link repair. Because Fanconi anemia cells are also sensitive to cross-linking agents, this strengthens the notion that the capacity to repair cross-links determines hypoxic radiosensitivity

Generalizable, Electroless, Template-Assisted Synthesis and Electrocatalytic Mechanistic Understanding of Perovskite LaNiO3 Nanorods as Viable, Supportless Oxygen Evolution Reaction Catalysts in Alkaline Media.

Science.gov (United States)

McBean, Coray L; Liu, Haiqing; Scofield, Megan E; Li, Luyao; Wang, Lei; Bernstein, Ashley; Wong, Stanislaus S

2017-07-26

The oxygen evolution reaction (OER) is a key reaction for water electrolysis cells and air-powered battery applications. However, conventional metal oxide catalysts, used for high-performing OER, tend to incorporate comparatively expensive and less abundant precious metals such as Ru and Ir, and, moreover, suffer from poor stability. To attempt to mitigate for all of these issues, we have prepared one-dimensional (1D) OER-active perovskite nanorods using a unique, simple, generalizable, and robust method. Significantly, our work demonstrates the feasibility of a novel electroless, seedless, surfactant-free, wet solution-based protocol for fabricating "high aspect ratio" LaNiO 3 and LaMnO 3 nanostructures. As the main focus of our demonstration of principle, we prepared as-synthesized LaNiO 3 rods and correlated the various temperatures at which these materials were annealed with their resulting OER performance. We observed generally better OER performance for samples prepared with lower annealing temperatures. Specifically, when annealed at 600 °C, in the absence of a conventional conductive carbon support, our as-synthesized LaNiO 3 rods not only evinced (i) a reasonable level of activity toward OER but also displayed (ii) an improved stability, as demonstrated by chronoamperometric measurements, especially when compared with a control sample of commercially available (and more expensive) RuO 2 .

Modal Damping Ratio and Optimal Elastic Moduli of Human Body Segments for Anthropometric Vibratory Model of Standing Subjects.

Science.gov (United States)

Gupta, Manoj; Gupta, T C

2017-10-01

The present study aims to accurately estimate inertial, physical, and dynamic parameters of human body vibratory model consistent with physical structure of the human body that also replicates its dynamic response. A 13 degree-of-freedom (DOF) lumped parameter model for standing person subjected to support excitation is established. Model parameters are determined from anthropometric measurements, uniform mass density, elastic modulus of individual body segments, and modal damping ratios. Elastic moduli of ellipsoidal body segments are initially estimated by comparing stiffness of spring elements, calculated from a detailed scheme, and values available in literature for same. These values are further optimized by minimizing difference between theoretically calculated platform-to-head transmissibility ratio (TR) and experimental measurements. Modal damping ratios are estimated from experimental transmissibility response using two dominant peaks in the frequency range of 0-25 Hz. From comparison between dynamic response determined form modal analysis and experimental results, a set of elastic moduli for different segments of human body and a novel scheme to determine modal damping ratios from TR plots, are established. Acceptable match between transmissibility values calculated from the vibratory model and experimental measurements for 50th percentile U.S. male, except at very low frequencies, establishes the human body model developed. Also, reasonable agreement obtained between theoretical response curve and experimental response envelop for average Indian male, affirms the technique used for constructing vibratory model of a standing person. Present work attempts to develop effective technique for constructing subject specific damped vibratory model based on its physical measurements.

NETWORKED LEARNING AS A PROCESS OF IDENTIFICATION IN THE INTERSECTION OF COLLABORATIVE KNOWLEDGE BUILDING - FOSTERING CREATIVITY, AWARENESS AND RE-USE OF OER

DEFF Research Database (Denmark)

Østergaard, Rina; Sorensen, Elsebeth Korsgaard

2011-01-01

goals. In relation to objectives of competencies, attention is given to creative, innovative and action-oriented types. This paper addresses the role of OER in design of innovative, networked learning processes in diverse educational contexts of higher education, continuing education and in relation......Within professional education a recent shift has taken place. Professional education has moved from specialized education and update of professional knowledge, over competence-based education, to, recently, education with goals such as creativity, innovation, entrepreneur- and entrepreneurship....... OECDs Centre for Educational Research and Innovation (CERI) reveals this tendency. The core idea here is that education, in a very goal-directed way, supports initiatives, which – in turn – results in added-value to society. As such, the educational shift may be interpreted as related to societal change...

Lethal Effect of Thermal Neutrons on Hypoxic Elirlich Ascites Tumour Cells in vitro

OpenAIRE

MITSUHIKO, AKABOSHI; KENICHI, KAWAI; HIROTOSHI, MAKI; Research Reactor Institute, Kyoto University; Research Reactor Institute, Kyoto University; Research Reactor Institute, Kyoto University

1985-01-01

Ehrlich ascites tumour cells were irradiated in vitro with thermal neutrons under aerobic and hypoxic conditions, and the survival of their reproductive capacity was assayed in vivo. Only a slight hypoxic protection was observed for thermal neutron irradiation with an oxygen enhancement ratio (OER) of 1.2, as compared with OER of 3.3 for ^Co-γ-rays. Absorbed dose of thermal neutrons was calculated by assuming that the energies of recoiled nuclei were completely absorbed within a cell nucleus....

MO-Co@N-Doped Carbon (M = Zn or Co): Vital Roles of Inactive Zn and Highly Efficient Activity toward Oxygen Reduction/Evolution Reactions for Rechargeable Zn-Air Battery

Energy Technology Data Exchange (ETDEWEB)

Chen, Biaohua [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 P. R. China; Beijing Key Laboratory of Energy Environmental Catalysis, Beijing University of Chemical Technology, Beijing 100029 P. R. China; He, Xiaobo [Changzhou Institute of Advanced Materials, Beijing University of Chemical Technology, Changzhou 213164 P. R. China; Yin, Fengxiang [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 P. R. China; Beijing Key Laboratory of Energy Environmental Catalysis, Beijing University of Chemical Technology, Beijing 100029 P. R. China; Changzhou Institute of Advanced Materials, Beijing University of Chemical Technology, Changzhou 213164 P. R. China; Wang, Hao [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 P. R. China; Beijing Key Laboratory of Energy Environmental Catalysis, Beijing University of Chemical Technology, Beijing 100029 P. R. China; Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Liu, Di-Jia [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Shi, Ruixing [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 P. R. China; Chen, Jinnan [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 P. R. China; Yin, Hongwei [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 P. R. China

2017-06-14

A highly efficient bifunctional oxygen catalyst is required for practical applications of fuel cells and metal-air batteries, as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are their core electrode reactions. Here, the MO-Co@ N-doped carbon (NC, M = Zn or Co) is developed as a highly active ORR/OER bifunctional catalyst via pyrolysis of a bimetal metal-organic framework containing Zn and Co, i.e., precursor (CoZn). The vital roles of inactive Zn in developing highly active bifunctional oxygen catalysts are unraveled. When the precursors include Zn, the surface contents of pyridinic N for ORR and the surface contents of Co-N-x and Co3+/Co2+ ratios for OER are enhanced, while the high specific surface areas, high porosity, and high electrochemical active surface areas are also achieved. Furthermore, the synergistic effects between Zn-based and Co-based species can promote the well growth of multiwalled carbon nanotubes (MWCNTs) at high pyrolysis temperatures (>= 700 degrees C), which is favorable for charge transfer. The optimized CoZn-NC-700 shows the highly bifunctional ORR/OER activity and the excellent durability during the ORR/OER processes, even better than 20 wt% Pt/C (for ORR) and IrO2 (for OER). CoZn-NC-700 also exhibits the prominent Zn-air battery performance and even outperforms the mixture of 20 wt% Pt/C and IrO2.

The use of interval ratios in consonance perception by rats (Rattus norvegicus) and humans (Homo sapiens).

Science.gov (United States)

Crespo-Bojorque, Paola; Toro, Juan M

2015-02-01

Traditionally, physical features in musical chords have been proposed to be at the root of consonance perception. Alternatively, recent studies suggest that different types of experience modulate some perceptual foundations for musical sounds. The present study tested whether the mechanisms involved in the perception of consonance are present in an animal with no extensive experience with harmonic stimuli and a relatively limited vocal repertoire. In Experiment 1, rats were trained to discriminate consonant from dissonant chords and tested to explore whether they could generalize such discrimination to novel chords. In Experiment 2, we tested if rats could discriminate between chords differing only in their interval ratios and generalize them to different octaves. To contrast the observed pattern of results, human adults were tested with the same stimuli in Experiment 3. Rats successfully discriminated across chords in both experiments, but they did not generalize to novel items in either Experiment 1 or Experiment 2. On the contrary, humans not only discriminated among both consonance-dissonance categories, and among sets of interval ratios, they also generalized their responses to novel items. These results suggest that experience with harmonic sounds may be required for the construction of categories among stimuli varying in frequency ratios. However, the discriminative capacity observed in rats suggests that at least some components of auditory processing needed to distinguish chords based on their interval ratios are shared across species. PsycINFO Database Record (c) 2015 APA, all rights reserved.

A reduced cerebral metabolic ratio in exercise reflects metabolism and not accumulation of lactate within the human brain

DEFF Research Database (Denmark)

Dalsgaard, Mads K; Quistorff, Bjørn; Danielsen, Else R

2003-01-01

During maximal exercise lactate taken up by the human brain contributes to reduce the cerebral metabolic ratio, O(2)/(glucose + 1/2 lactate), but it is not known whether the lactate is metabolized or if it accumulates in a distribution volume. In one experiment the cerebral arterio-venous differe......During maximal exercise lactate taken up by the human brain contributes to reduce the cerebral metabolic ratio, O(2)/(glucose + 1/2 lactate), but it is not known whether the lactate is metabolized or if it accumulates in a distribution volume. In one experiment the cerebral arterio......-venous differences (AV) for O(2), glucose (glc) and lactate (lac) were evaluated in nine healthy subjects at rest and during and after exercise to exhaustion. The cerebrospinal fluid (CSF) was drained through a lumbar puncture immediately after exercise, while control values were obtained from six other healthy.......0 to 0.9 +/- 0.1 mM (P ratio from 6.0 +/- 0.3 to 2.8 +/- 0.2 (P

Rational Design of Cobalt-Iron Selenides for Highly Efficient Electrochemical Water Oxidation.

Science.gov (United States)

Zhang, Jun-Ye; Lv, Lin; Tian, Yifan; Li, Zhishan; Ao, Xiang; Lan, Yucheng; Jiang, Jianjun; Wang, Chundong

2017-10-04

Exploring active, stable, earth-abundant, low-cost, and high-efficiency electrocatalysts is highly desired for large-scale industrial applications toward the low-carbon economy. In this study, we apply a versatile selenizing technology to synthesize Se-enriched Co 1-x Fe x Se 2 catalysts on nickel foams for oxygen evolution reactions (OERs) and disclose the relationship between the electronic structures of Co 1-x Fe x Se 2 (via regulating the atom ratio of Co/Fe) and their OER performance. Owing to the fact that the electron configuration of the Co 1-x Fe x Se 2 compounds can be tuned by the incorporated Fe species (electron transfer and lattice distortion), the catalytic activity can be adjusted according to the Co/Fe ratios in the catalyst. Moreover, the morphology of Co 1-x Fe x Se 2 is also verified to strongly depend on the Co/Fe ratios, and the thinner Co 0.4 Fe 0.6 Se 2 nanosheets are obtained upon selenization treatment, in which it allows more active sites to be exposed to the electrolyte, in turn promoting the OER performance. The Co 0.4 Fe 0.6 Se 2 nanosheets not only exhibit superior OER performance with a low overpotential of 217 mV at 10 mA cm -2 and a small Tafel slope of 41 mV dec -1 but also possess ultrahigh durability with a dinky degeneration of 4.4% even after 72 h fierce water oxidation test in alkaline solution, which outperforms the commercial RuO 2 catalyst. As expected, the Co 0.4 Fe 0.6 Se 2 nanosheets have shown great prospects for practical applications toward water oxidation.

Intake to Production Ratio

DEFF Research Database (Denmark)

Nazaroff, William; Weschler, Charles J.; Little, John C.

2012-01-01

BACKGROUND: Limited data are available to assess human exposure to thousands of chemicals currently in commerce. Information that relates human intake of a chemical to its production and use can help inform understanding of mechanisms and pathways that control exposure and support efforts...... to protect public health.OBJECTIVES: We introduce the intake-to-production ratio (IPR) as an economy-wide quantitative indicator of the extent to which chemical production results in human exposure.METHODS: The IPR was evaluated as the ratio of two terms: aggregate rate of chemical uptake in a human......(n-butyl) phthalate, 1,040 ppm for para-dichlorobenzene, 6,800 ppm for di(isobutyl) phthalate, 7,700 ppm for diethyl phthalate, and 8,000-24,000 ppm (range) for triclosan.CONCLUSION: The IPR is well suited as an aggregate metric of exposure intensity for characterizing population-level exposure to synthesized...

Oxygen effect of E.coli K-12 with different repair genotype at the bombardment by neutrons and γ-rays

International Nuclear Information System (INIS)

Komova, O.V.; Golovacheva, E.V.

1986-01-01

It is shown that the value of oxygen enhancement ratio (OER) depends essentually on repair possibilities of cells E.coli K-12 at 137 Cs - γ-irradiation. It increases in a range of investigated strains rec A - uvr A - → rec A - → wild type → pol A - . These differences disappear under action of fast neutron fission spectra with 0.75 MeV mean energy. OER values for all strains have been reduced in this case, and double mutant rec A - uvr A - practically has not any oxygen effects

Effects of HIF-1 inhibition by chetomin on hypoxia-related transcription and radiosensitivity in HT 1080 human fibrosarcoma cells

International Nuclear Information System (INIS)

Staab, Adrian; Einsele, Hermann; Flentje, Michael; Vordermark, Dirk; Loeffler, Jürgen; Said, Harun M; Diehlmann, Désirée; Katzer, Astrid; Beyer, Melanie; Fleischer, Markus; Schwab, Franz; Baier, Kurt

2007-01-01

Hypoxia-inducible factor-1 (HIF-1) overexpression has been linked to tumor progression and poor prognosis. We investigated whether targeting of HIF-1 using chetomin, a disrupter of the interaction of HIF-1 with the transcriptional coactivator p300, influences the radiosensitivity of hypoxic HT 1080 human fibrosarcoma cells. Optimal dose of chetomin was determined by EGFP-HRE gene reporter assay in stably transfected HT 1080 cells. Cells were assayed for expression of the hypoxia-inducible genes carbonic anhydrase 9 (CA9) and vascular endothelial growth factor (VEGF) by RT-PCR and for clonogenic survival after irradiation with 2, 5 or 10 Gy, under normoxic or hypoxic (0.1% O 2 , 12 h) conditions in the presence or absence of chetomin (150 nM, 12 h, pre-treatment of 4 h). Chetomin treatment significantly reduced CA9 and VEGF mRNA expression in hypoxic cells to 44.4 ± 7.2% and 39.6 ± 16.0%, respectively, of untreated hypoxic controls. Chetomin clearly reduced the modified oxygen enhancement ratio (OER') compared to untreated cells, from 2.02 to 1.27, from 1.86 to 1.22 and from 1.49 to 1.06 at the 50%, 37% and 10% clonogenic survival levels, respectively. HIF-1 inhibition by chetomin effectively reduces hypoxia-dependent transcription and radiosensitizes hypoxic HT 1080 human fibrosarcoma cells in vitro

Determination of calcium, phosphorus, and the calcium/phosphorus ratio in cortical bone from the human femoral neck by neutron activation analysis

International Nuclear Information System (INIS)

Zaichick, Vladimir; Tzaphlidou, Margaret

2002-01-01

Concentrations of Ca and P as well as the Ca/P ratio were estimated in intact cortical bone samples from the femoral neck of healthy humans, 33 women and 45 men, aged from 15 to 55 yr using instrumental neutron activation analysis. Mean values (M±SD) for the investigated parameters (on dry weight basis) were: 23.0±3.9%, 10.7±2.4% and 2.17±0.31, respectively. No statistically significant differences of the above parameters were observed related either to age or sex. The mean values for Ca, P and Ca/P ratio were within a very wide range of published data and close to their median. The individual variation for the Ca/P ratio in cortical bone from the healthy human femoral neck was lower than those for Ca and P separately. This means that specificity of Ca/P ratio is better than those of Ca and P concentrations are and may be more reliable for diagnosis of bone disorders

Operating experience review in development of SMART MMIS

International Nuclear Information System (INIS)

Suh, S. M.; Jang, G. S.; Lee, J. G.; Park, G. O.; Ko, J. H.

2004-01-01

We have developed HFE(Human Factors Engineering) program plan for the purpose of implementing man-machine interface system in SMART plant systematically. Elements of the plan are compatible to those of NUREG-0711, Rev.1, and OER(Operating Experience Review) is one of them. The main purpose of conducting an OER as part of HFE review is to identify HFE-related safety issues. If identified, design alternatives are carefully reviewed and selected as the way of resolution for those issues. The performing model of OER is described in this paper, showing a series of works must be done to identify and resolve HFE-related issues within the scope of SMART HFE works. Then two key issues and design alternatives resolving them are presented for examples

Bio-field array: a dielectrophoretic electromagnetic toroidal excitation to restore and maintain the golden ratio in human erythrocytes.

Science.gov (United States)

Purnell, Marcy C; Butawan, Matthew B A; Ramsey, Risa D

2018-06-01

Erythrocytes must maintain a biconcave discoid shape in order to efficiently deliver oxygen (O 2 ) molecules and to recycle carbon dioxide (CO 2 ) molecules. The erythrocyte is a small toroidal dielectrophoretic (DEP) electromagnetic field (EMF) driven cell that maintains its zeta potential (ζ) with a dielectric constant (ԑ) between a negatively charged plasma membrane surface and the positively charged adjacent Stern layer. Here, we propose that zeta potential is also driven by both ferroelectric influences (chloride ion) and ferromagnetic influences (serum iron driven). The Golden Ratio, a function of Phi φ, offers a geometrical mathematical measure within the distinct and desired curvature of the red blood cell that is governed by this zeta potential and is required for the efficient recycling of CO 2 in our bodies. The Bio-Field Array (BFA) shows potential to both drive/fuel the zeta potential and restore the Golden Ratio in human erythrocytes thereby leading to more efficient recycling of CO 2 . Live Blood Analyses and serum CO 2 levels from twenty human subjects that participated in immersion therapy sessions with the BFA for 2 weeks (six sessions) were analyzed. Live Blood Analyses (LBA) and serum blood analyses performed before and after the BFA immersion therapy sessions in the BFA pilot study participants showed reversal of erythrocyte rheological alterations (per RBC metric; P = 0.00000075), a morphological return to the Golden Ratio and a significant decrease in serum CO 2 (P = 0.017) in these participants. Immersion therapy sessions with the BFA show potential to modulate zeta potential, restore this newly defined Golden Ratio and reduce rheological alterations in human erythrocytes. © 2018 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Reoxygenation of human coronary smooth muscle cells suppresses HIF-1{alpha} gene expression and augments radiation-induced growth delay and apoptosis

Energy Technology Data Exchange (ETDEWEB)

Grumann, T.; Arab, A.; Bode, C.; Hehrlein, C. [Dept. of Cardiology, Univ. Clinic of Freiburg (Germany); Guttenberger, R. [Dept. of Radiotherapy, Univ. Clinic of Freiburg (Germany)

2006-01-01

Background and Purpose: Catheter-based coronary brachytherapy with {beta}- and {gamma}-radiation is an evidence-based method to prevent restenosis after percutaneous transluminal coronary angioplasty (PTCA) and stent implantation, but the outcome may be PTCA are hypoxic. A lack of oxygen decreases the effect of low LET (linear energy transfer) irradiation. The authors assumed that reoxygenation of hypoxic human coronary smooth muscle cells (HCSMCs) improves the results of coronary brachytherapy. The expression of hypoxia-inducible factor 1{alpha} (HIF-1{alpha}) gene, and the rates of growth and apoptosis of hypoxic and reoxygenated HCSMCs after {gamma}-iradiation were therefore analyzed. Material and Methods: An in vitro model of megacolonies of HCSMCs was developed. After exposure to chronic hypoxia the HCSMCs were irradiated with graded doses of 2, 4, 8, and 16 Gy using a {sup 60}Co source either under hypoxia (pO{sub 2}<3 mmHg) or after reoxygenation (pO{sub 2}{approx}150 mmHg). RT-PCR (reverse transcription-polymerase chain reaction) analysis was used to quantify HIF-1{alpha} gene expression and the growth of HCSMC megacolonies was measured serially. The oxygen enhancement ratio (OER) was calculate from the specific growth delay. Apoptosis of HCSMCs was quantified by counting cells with specific DNA strand breaks using the TUNEL assy. Results: HIF-1{alpha} gene expression was markedly suppressed in reoxygenated cells versus hypoxic cells 30 min after {gamma}-irradiation at all radiation doses (158{+-}46% vs. 1,675{+-}1,211%; p<0.01). Apoptosis was markedly increased in reoxygenated HCSMCs. The OER was 1.8(95% CI[confidence interval]1.3-2.4). Therefore, reoxygenated HCSMCs require 44% less radiation dose to achieve the equivalent biological radiation effect compared to hypoxic HCSMCs. Conclusion: Reoxygenation of coronary smooth muscle cells should be considered an option to increase efficacy of coronary brachytherapy. This could be used to reduce radiation dose

Influence of variable oxygen concentration on the response of cells to heat or x irradiation

International Nuclear Information System (INIS)

Gerweck, L.E.; Richards, B.; Jennings, M.

1981-01-01

The influence of oxygen concentration on the lethal response of cells exposed to 43 0 C hyperthermia was determined and compared to the response of cells exposed to radiation under equivalent culturing and environmental conditions. Chinese hamster ovary (CHO) cells were heated or irradiated 0.5 h after induction of hypoxia and then reoxygenated following treatment. The oxygen enhancement ratio (OER) for heat or radiation was determined at the 1% survival level from least-squares fit of survival curves. A maximum OER of 3.1 +- 0.2 was observed in the 20 to 95% oxygen concentration range. The OER for heat, however, was 1.0 +- 0.1 irrespective of the gas-phase oxygen concentration. These results show that the lethal effects of heat are not influenced by the oxygen concentration at the time of treatment in CHO cells exposed to 43 0 C hyperthermia

Statistical validity of using ratio variables in human kinetics research.

Science.gov (United States)

Liu, Yuanlong; Schutz, Robert W

2003-09-01

The purposes of this study were to investigate the validity of the simple ratio and three alternative deflation models and examine how the variation of the numerator and denominator variables affects the reliability of a ratio variable. A simple ratio and three alternative deflation models were fitted to four empirical data sets, and common criteria were applied to determine the best model for deflation. Intraclass correlation was used to examine the component effect on the reliability of a ratio variable. The results indicate that the validity, of a deflation model depends on the statistical characteristics of the particular component variables used, and an optimal deflation model for all ratio variables may not exist. Therefore, it is recommended that different models be fitted to each empirical data set to determine the best deflation model. It was found that the reliability of a simple ratio is affected by the coefficients of variation and the within- and between-trial correlations between the numerator and denominator variables. It was recommended that researchers should compute the reliability of the derived ratio scores and not assume that strong reliabilities in the numerator and denominator measures automatically lead to high reliability in the ratio measures.

Analyzing the mechanisms of cell killing by ionizing radiation in monolayer, spheroids and xenografted tumours

International Nuclear Information System (INIS)

Horas, J.A.; Olguín, O.R.; Rizzotto, M.G.

2017-01-01

A relationship between oxygen enhancement ratio (OER) and parameters of Linear Quadratic (LQ) model in hypoxic and aerobic conditions in several cell lines grown as monolayer, spheroids and transplanted tumors (xenograft) is tested. By considering this relationship, the two mechanisms of cell death by radiation appear. Surviving Fraction (SF) fits are compared in both oxygenation conditions by using the LQ. The data are obtained from literature. The existence of such mechanisms and their implications in the different systems studied is shown. The validity of one or other mechanism in each case is determined and the OER dependence with dose. (authors) [es

Operating experience review for the AP1000 plant

International Nuclear Information System (INIS)

Chaney, T. E.; Lipner, M. H.

2006-01-01

Westinghouse is performing an update to the Operating Experience Review (OER) Report for the AP1000 project to account for operating experience since December 1996. Significant Operating Experience Reports, Significant Event Reports, Significant Event Notifications, Operations and Maintenance Reminders, Topical Reports, Event Analysis Reports and Licensee Event Reports were researched for pertinent input to the update. As a part of the OER, Westinghouse has also conducted operator interviews and observations during simulated plant operations and after operating events. The main purpose of the OER is to identify Human Factors Engineering (HFE) related safety issues from existing operating plant experience and to ensure that these issues are addressed in the new design. The issues and lessons learned regarding operating experience provide a basis for improving the plant design. (authors)

User Experience for Disabled Users in Open Educational Resources Websites

Directory of Open Access Journals (Sweden)

Rosa Navarrete

2015-11-01

Full Text Available Open Educational Resources (OER are digital materials for teaching-learning purpose released under an open license that are available through websites. In the last decade, some governments have encouraged the development and using of OER in order to contribute to the achievement of the right to education for everyone, a fundamental right included in The Universal Declaration of Human Rights. Besides, inclusion of people with disabilities is a global concern that need to be addressed in all living aspects including education.In this research we address the user experience in OER websites —considering the perspective of users with disabilities— in order to recognize possible barriers in web design. The conformance criteria considered for this reviewing are mandatory aspects of user experience in relation to Web accessibility and Web usability.

User Experience for Disabled Users in Open Educational Resources Websites

Directory of Open Access Journals (Sweden)

Rosa Navarrete

2015-11-01

Full Text Available Open Educational Resources (OER are digital materials for teaching-learning purpose released under an open license that are available through websites. In the last decade, some governments have encouraged the development and using of OER in order to contribute to the achievement of the right to education for everyone, a fundamental right included in The Universal Declaration of Human Rights. Besides, inclusion of people with disabilities is a global concern that need to be addressed in all living aspects including education. In this research we address the user experience in OER websites —considering the perspective of users with disabilities— in order to recognize possible barriers in web design. The conformance criteria considered for this reviewing are mandatory aspects of user experience in relation to Web accessibility and Web usability.

Dietary heterogeneity among Western industrialized countries reflected in the stable isotope ratios of human hair.

Science.gov (United States)

Valenzuela, Luciano O; Chesson, Lesley A; Bowen, Gabriel J; Cerling, Thure E; Ehleringer, James R

2012-01-01

Although the globalization of food production is often assumed to result in a homogenization of consumption patterns with a convergence towards a Western style diet, the resources used to make global food products may still be locally produced (glocalization). Stable isotope ratios of human hair can quantify the extent to which residents of industrialized nations have converged on a standardized diet or whether there is persistent heterogeneity and glocalization among countries as a result of different dietary patterns and the use of local food products. Here we report isotopic differences among carbon, nitrogen and sulfur isotope ratios of human hair collected in thirteen Western European countries and in the USA. European hair samples had significantly lower δ(13)C values (-22.7 to -18.3‰), and significantly higher δ(15)N (7.8 to 10.3‰) and δ(34)S (4.8 to 8.3‰) values than samples from the USA (δ(13)C: -21.9 to -15.0‰, δ(15)N: 6.7 to 9.9‰, δ(34)S: -1.2 to 9.9‰). Within Europe, we detected differences in hair δ(13)C and δ(34)S values among countries and covariation of isotope ratios with latitude and longitude. This geographic structuring of isotopic data suggests heterogeneity in the food resources used by citizens of industrialized nations and supports the presence of different dietary patterns within Western Europe despite globalization trends. Here we showed the potential of stable isotope analysis as a population-wide tool for dietary screening, particularly as a complement of dietary surveys, that can provide additional information on assimilated macronutrients and independent verification of data obtained by those self-reporting instruments.

Dietary heterogeneity among Western industrialized countries reflected in the stable isotope ratios of human hair.

Directory of Open Access Journals (Sweden)

Luciano O Valenzuela

Full Text Available Although the globalization of food production is often assumed to result in a homogenization of consumption patterns with a convergence towards a Western style diet, the resources used to make global food products may still be locally produced (glocalization. Stable isotope ratios of human hair can quantify the extent to which residents of industrialized nations have converged on a standardized diet or whether there is persistent heterogeneity and glocalization among countries as a result of different dietary patterns and the use of local food products. Here we report isotopic differences among carbon, nitrogen and sulfur isotope ratios of human hair collected in thirteen Western European countries and in the USA. European hair samples had significantly lower δ(13C values (-22.7 to -18.3‰, and significantly higher δ(15N (7.8 to 10.3‰ and δ(34S (4.8 to 8.3‰ values than samples from the USA (δ(13C: -21.9 to -15.0‰, δ(15N: 6.7 to 9.9‰, δ(34S: -1.2 to 9.9‰. Within Europe, we detected differences in hair δ(13C and δ(34S values among countries and covariation of isotope ratios with latitude and longitude. This geographic structuring of isotopic data suggests heterogeneity in the food resources used by citizens of industrialized nations and supports the presence of different dietary patterns within Western Europe despite globalization trends. Here we showed the potential of stable isotope analysis as a population-wide tool for dietary screening, particularly as a complement of dietary surveys, that can provide additional information on assimilated macronutrients and independent verification of data obtained by those self-reporting instruments.

Absolute Quantification of Human Milk Caseins and the Whey/Casein Ratio during the First Year of Lactation.

Science.gov (United States)

Liao, Yalin; Weber, Darren; Xu, Wei; Durbin-Johnson, Blythe P; Phinney, Brett S; Lönnerdal, Bo

2017-11-03

Whey proteins and caseins in breast milk provide bioactivities and also have different amino acid composition. Accurate determination of these two major protein classes provides a better understanding of human milk composition and function, and further aids in developing improved infant formulas based on bovine whey proteins and caseins. In this study, we implemented a LC-MS/MS quantitative analysis based on iBAQ label-free quantitation, to estimate absolute concentrations of α-casein, β-casein, and κ-casein in human milk samples (n = 88) collected between day 1 and day 360 postpartum. Total protein concentration ranged from 2.03 to 17.52 with a mean of 9.37 ± 3.65 g/L. Casein subunits ranged from 0.04 to 1.68 g/L (α-), 0.04 to 4.42 g/L (β-), and 0.10 to 1.72 g/L (α-), with β-casein having the highest average concentration among the three subunits. Calculated whey/casein ratio ranged from 45:55 to 97:3. Linear regression analyses show significant decreases in total protein, β-casein, κ-casein, total casein, and a significant increase of whey/casein ratio during the course of lactation. Our study presents a novel and accurate quantitative analysis of human milk casein content, demonstrating a lower casein content than earlier believed, which has implications for improved infants formulas.

Characterisation of the Metabolites of 1,8-Cineole Transferred into Human Milk: Concentrations and Ratio of Enantiomers

Science.gov (United States)

Kirsch, Frauke; Buettner, Andrea

2013-01-01

1,8-Cineole is a widely distributed odorant that also shows physiological effects, but whose human metabolism has hitherto not been extensively investigated. The aim of the present study was, thus, to characterise the metabolites of 1,8-cineole, identified previously in human milk, after the oral intake of 100 mg of this substance. Special emphasis was placed on the enantiomeric composition of the metabolites since these data may provide important insights into potential biotransformation pathways, as well as potential biological activities of these substances, for example on the breastfed child. The volatile fraction of the human milk samples was therefore isolated via Solvent Assisted Flavour Evaporation (SAFE) and subjected to gas chromatography-mass spectrometry (GC-MS). The absolute concentrations of each metabolite were determined by matrix calibration with an internal standard, and the ratios of enantiomers were analysed on chiral capillaries. The concentrations varied over a broad range, from traces in the upper ng/kg region up to 40 µg/kg milk, with the exception of the main metabolite α2-hydroxy-1,8-cineole that showed concentrations of 100–250 µg/kg. Also, large inter- and intra-individual variations were recorded for the enantiomers, with nearly enantiomerically pure α2-hydroxy- and 3-oxo-1,8-cineole, while all other metabolites showed ratios of ~30:70 to 80:20. PMID:24957890

[The diagnostic value of human chorionic gonadotrophin ratio compared to single measurements of S-human chorionic gonadotrophin on the outcome of pregnancy of unknown location].

Science.gov (United States)

Majeed, Huda Galib; Lyngsø, Julie; Bor, Pinar

2014-10-13

Pregnancy of unknown location is defined by a positive pregnancy test, without visualizing of the intrauterine or extrauterine pregnancy by transvaginal sonography. We present the advantages of using human chorionic gonadotrophin (hCG) ratio instead of single measurements of S-hCG for predicting the outcomes of pregnancies of unknown location.

The Cellular Composition and Glia-Neuron Ratio in the Spinal Cord of a Human and a Nonhuman Primate: Comparison With Other Species and Brain Regions.

Science.gov (United States)

Bahney, Jami; von Bartheld, Christopher S

2018-04-01

The cellular composition of brains shows largely conserved, gradual evolutionary trends between species. In the primate spinal cord, however, the glia-neuron ratio was reported to be greatly increased over that in the rodent spinal cord. Here, we re-examined the cellular composition of the spinal cord of one human and one nonhuman primate species by employing two different counting methods, the isotropic fractionator and stereology. We also determined whether segmental differences in cellular composition, possibly reflecting increased fine motor control of the upper extremities, may explain a sharply increased glia-neuron ratio in primates. In the cynomolgus monkey spinal cord, the isotropic fractionator and stereology yielded 206-275 million cells, of which 13.3-25.1% were neurons (28-69 million). Stereological estimates yielded 21.1% endothelial cells and 65.5% glial cells (glia-neuron ratio of 4.9-5.6). In human spinal cords, the isotropic fractionator and stereology generated estimates of 1.5-1.7 billion cells and 197-222 million neurons (13.4% neurons, 12.2% endothelial cells, 74.8% glial cells), and a glia-neuron ratio of 5.6-7.1, with estimates of neuron numbers in the human spinal cord based on morphological criteria. The non-neuronal to neuron ratios in human and cynomolgus monkey spinal cords were 6.5 and 3.2, respectively, suggesting that previous reports overestimated this ratio. We did not find significant segmental differences in the cellular composition between cervical, thoracic and lumbar levels. When compared with brain regions, the spinal cord showed gradual increases of the glia-neuron ratio with increasing brain mass, similar to the cerebral cortex and the brainstem. Anat Rec, 301:697-710, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Ternary mixed metal Fe-doped NiCo2O4 nanowires as efficient electrocatalysts for oxygen evolution reaction

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Yan, Kai-Li; Shang, Xiao; Li, Zhen; Dong, Bin; Li, Xiao; Gao, Wen-Kun; Chi, Jing-Qi; Chai, Yong-Ming; Liu, Chen-Guang

2017-09-01

Designing mixed metal oxides with unique nanostructures as efficient electrocatalysts for water electrolysis has been an attractive approach for the storage of renewable energies. The ternary mixed metal spinel oxides FexNi1-xCo2O4 (x = 0, 0.1, 0.25, 0.5, 0.75, 0.9, 1) have been synthesized by a facile hydrothermal approach and calcination treatment using nickel foam as substrate. Fe/Ni ratios have been proved to affect the nanostructures of FexNi1-xCo2O, which imply different intrinsic activity for oxygen evolution reaction (OER). SEM images show that Fe0.5Ni0.5Co2O4 has the uniform nanowires morphology with about 30 nm of the diameter and 200-300 nm of the length. The OER measurements show that Fe0.5Ni0.5Co2O4 exhibits the better electrocatalytic performances with lower overpotential of 350 mV at J = 10 mA cm-2. In addition, the smaller Tafel slope of 27 mV dec-1 than other samples with different Fe/Ni ratios for Fe0.5Ni0.5Co2O4 is obtained. The improved OER activity of Fe0.5Ni0.5Co2O4 may be attributed to the synergistic effects from ternary mixed metals especially Fe-doping and the uniform nanowires supported on NF. Therefore, synthesizing Fe-doped multi-metal oxides with novel nanostructures may be a promising strategy for excellent OER electrocatalysts and it also provides a facile way for the fabrication of high-activity ternary mixed metal oxides electrocatalysts.

Survival curves of irradiated glutathione-deficient human fibroblasts: indication of a reduced enhancement of radiosensitivity by oxygen and misonidazole

International Nuclear Information System (INIS)

Midander, J.; Deschavanne, P.J.; Malaise, E.P.; Revesz, L.

1982-01-01

Fibroblasts derived from a patient with 5-oxoprolinuria are genetically deficient in glutathione synthetase. This deficiency causes a dramatic decrease in intracellular glutathione (GSH) level. The radiosensitivity of GSH deficient cells (GSH) was studied in vitro using colony forming ability as an endpoint. Cells with normal GSH level, obtained from the healthy brother of the patient, were used as controls. When irradiated in 95% air-5% CO 2 , GSH - cells are slightly but significantly more radiosensitive than GSH + controls (dose modifying factor (DMF) of 1.2). When irradiated in argon, the survival curve of GSH - cells indicates an oxygen enhancement ratio (OER) of 1.5 when compared to the curve obtained in oxic conditions. The OER of control cells in the same conditions is 2.9. In comparison to results obtained in air, 100% oxygen moderately increases the radiosensitivity of GSH + cells (DMF 1,23), while it has a very low effect on GSH - cells (DMF 1.06). These results suggest that intracellular GSH plays an essential protective role in hypoxia, its effect is reduced in air and practically disappears in 100% oxygen. When cells are incubated with 8 mM misonidazole 2 hours before irradiation, the drug has a much greater sensitizing effect on GSH + cells (DMF 2.33) than on GSH - cells (DMF 1.55). The results demonstrate that intracellular GSH level plays a major role in the response of hypoxic cells, irradiated either alone or in the presence of misonidazole

Boron nitride nanotube-mediated stimulation modulates F/G-actin ratio and mechanical properties of human dermal fibroblasts

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Ricotti, Leonardo; das Neves, Ricardo Pires; Ciofani, Gianni; Canale, Claudio; Nitti, Simone; Mattoli, Virgilio; Mazzolai, Barbara; Ferreira, Lino; Menciassi, Arianna

2014-02-01

F/G-actin ratio modulation is known to have an important role in many cell functions and in the regulation of specific cell behaviors. Several attempts have been made in the latest decades to finely control actin production and polymerization, in order to promote certain cell responses. In this paper we demonstrate the possibility of modulating F/G-actin ratio and mechanical properties of normal human dermal fibroblasts by using boron nitride nanotubes dispersed in the culture medium and by stimulating them with ultrasound transducers. Increasing concentrations of nanotubes were tested with the cells, without any evidence of cytotoxicity up to 10 μg/ml concentration of nanoparticles. Cells treated with nanoparticles and ultrasound stimulation showed a significantly higher F/G-actin ratio in comparison with the controls, as well as a higher Young's modulus. Assessment of Cdc42 activity revealed that actin nucleation/polymerization pathways, involving Rho GTPases, are probably influenced by nanotube-mediated stimulation, but they do not play a primary role in the significant increase of F/G-actin ratio of treated cells, such effect being mainly due to actin overexpression.

The role of thiols in cellular response to radiation and drugs

International Nuclear Information System (INIS)

Biaglow, J.E.; Varnes, M.E.; Clark, E.P.; Epp, E.R.

1983-01-01

Cellular nonprotein thiols (NPSH) consist of glutathione (GSH) and other low molecular weight species such as cysteine, cysteamine, and coenzyme A. GSH is usually less than the total cellular NPSH, and with thiol reactive agents, such as diethyl maleate (DEM), its rate of depletion is in part dependent upon the cellular capacity for its resynthesis. If resynthesis is blocked by buthionine-S,R-sulfoximine(BSO), the NPSH, including GSH, is depleted more rapidly, Cellular thiol depletion by diamide, N-ethylmaleimide, and BSO may render oxygenated cells more sensitive to radiation. These cells may or may not show a reduction in the oxygen enhancement ratio (OER). Human A549 lung carcinoma cells depleted of their NPSH either by prolonged culture or by BSO treatment do not show a reduced OER but do show increased aerobic responses to radiation. Some nitroheterocyclic radiosensitizing drugs also deplete cellular thiols under aerobic conditions. Such reactivity may be the reason that they show anomalous radiation sensitization (i.e., better than predicted on the basis of electron affinity). Other nitrocompounds, such as misonidazole, are activated under hypoxic conditions to radical intermediates. When cellular thiols are depleted peroxide is formed. Under hypoxic conditions thiols are depleted because metabolically reduced intermediates react with GSH instead of oxygen. Thiol depletion, under hypoxic conditions, may be the reason that misonidazole and other nitrocompounds show an extra enhancement ratio with hypoxic cells. Thiol depletion by DEM or BSO alters the radiation response of hypoxic cells to misonidazole

Role of thiols in cellular response to radiation and drugs. Symposium: thiols

International Nuclear Information System (INIS)

Biaglow, J.E.; Varnes, M.E.; Clark, E.P.; Epp, E.R.

1983-01-01

Cellular nonprotein thiols (NPSH) consist of glutathione (GSH) and other low molecular weight species such as cysteine, cysteamine, and coenzyme. A GSH is usually less than the total cellular NPSH, and with thiol reactive agents, such as diethyl maleate (DEM), its rate of depletion is in part dependent upon the cellular capacity for its resynthesis. If resynthesis is blocked by buthionine-S,R-sulfoximine(BSO), the NPSH, including GSH, is depleted more rapidly, Cellular thiol depletion by diamide, N-ethylmaleimide, and BSO may render oxygenated cells more sensitive to radiation. These cells may or may not show a reduction in the oxygen enhancement ratio (OER). Human A549 lung carcinoma cells depleted of their NPSH either by prolonged culture or by BSO treatment do not show a reduced OER but do show increased aerobic responses to radiation. Other nitrocompounds, such as misonidazole, are activated under hypoxic conditions to radical intermediates. When cellular thiols are depleted peroxide is formed. Under hypoxic conditions thiols are depleted because metabolically reduced intermediates react with GSH instead of oxygen. Thiol depletion, under hypoxic conditions, may be the reason that misonidazole and other nitrocompounds show an extra enhancement ratio with hypoxic cells. Thiol depletion by DEM or BSO alters the radiation response of hypoxic cells to misonidazole. In conclusion, we propose an altered thiol model which includes a mechanism for thiol involvement in the aerobic radiation response of cells

Oxygenated hemoglobin diffuse reflectance ratio for in vitro detection of human gastric pre-cancer

Science.gov (United States)

Li, L. Q.; Wei, H. J.; Guo, Z. Y.; Yang, H. Q.; Wu, G. Y.; Xie, S. S.; Zhong, H. Q.; Li, X. Y.; Zhao, Q. L.; Guo, X.

2010-07-01

Oxygenated hemoglobin diffuse reflectance (DR) ratio (R540/R575) method based on DR spectral signatures is used for early diagnosis of malignant lesions of human gastric epithelial tissues in vitro. The DR spectra for four different kinds of gastric epithelial tissues were measured using a spectrometer with an integrating sphere detector in the spectral range from 400 to 650 nm. The results of measurement showed that the average DR spectral intensity for the epithelial tissues of normal stomach is higher than that for the epithelial tissues of chronic and malignant stomach and that for the epithelial tissues of chronic gastric ulcer is higher than that for the epithelial tissues of malignant stomach. The average DR spectra for four different kinds of gastric epithelial tissues show dips at 542 and 577 nm owing to absorption from oxygenated Hemoglobin (HbO2). The differences in the mean R540/R575 ratios of HbO2 bands are 6.84% between the epithelial tissues of normal stomach and chronic gastric ulcer, 14.7% between the epithelial tissues of normal stomach and poorly differentiated gastric adenocarcinoma and 22.6% between the epithelial tissues of normal stomach and undifferentiated gastric adenocarcinoma. It is evident from results that there were significant differences in the mean R540/R575 ratios of HbO2 bands for four different kinds of gastric epithelial tissues in vitro ( P < 0.01).

Human sex ratio at amniocentesis and at birth in Taiwan

Directory of Open Access Journals (Sweden)

I-Wen Lee

2012-12-01

Conclusions: The results showed that sex ratio was already skewed toward male at midtrimester. Our data imply that artificial sex selection, if it were present, might have already emerged prior to the timing of amniocentesis. However, more large nationwide studies on sex ratios in Taiwan are warranted.

Role of insulin-like growth factor-I receptor (IGF-IR) in survival kinetics and radioresistance of mouse embryo fibroblasts in a hypoxic environment

International Nuclear Information System (INIS)

Okochi, Kiyoshi

2002-01-01

The role of insulin-like growth factor-I receptor (IGF-IR) in survival kinetics and radioresistance of fibroblasts in a severely hypoxic environment (partial oxygen pressure of less than 3 mmHg) was analyzed, in both low and high cell-density conditions. Mouse embryonic fibroblasts R(-), with a targeted disruption of the IGF-IR gene, and R(+) cells, derived from R(-) cells stably transfected with a plasmid containing a human IGF-IR cDNA, were used for this purpose. Survival time in hypoxia was longer in R(+) cells than R(-) cells, which correlated with highly elevated expression of caspase 3-like activity in R(-) cells, but not with HIF-Iα expression. Under euoxia, R(+) cells were more radioresistant, by a factor of 1.9, than R(-) cells. Under hypoxia, R(+) cells became more radioresistant, with an oxygen-enhancement ratio (OER) of 2.7, than R(-) cells, with an OER of 1.5, in a low cell density. However, unexpected hyper-radiosensitivity in hypoxia was observed for both R(+) and R(-) cells in a high cell density, which further increased with incubation time in hypoxia following X-irradiation. The hyper-radiosensitivity was more pronounced for R(-) cells. The result thus implies that IGF-IR may be an important target molecule for radioresistant tumors in radiotherapy. (author)

Do Strontium Isotope Ratios of Animal Bone and Teeth Really Reflect the Isotope Ratios of its birth- and growth-places?

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Minami, M.; Goto, A.; Suzuki, K.; Kato, T.; Watanabe, K.; Hasegawa, T.

2007-12-01

Strontium enters the human body through the food chain as nutrients pass from bedrock through soil and water to plants and animals. Strontium substitutes for calcium in the hydroxyapatite mineral of skeletal tissue, and is stored there. 87Sr/86Sr ratios in an individual's bone and teeth could directly reflect the isotopic ratios found in the plants and animals that she or he consumed, which reflect the isotope ratios found in the soil and bedrock of that geologic region. Therefore, 87Sr/86Sr ratios of human skeletons could be useful tools for assessing human residential mobility in prehistory, and many studies on them have been often made. In this study, to evaluate whether the 87Sr/86Sr ratio of a bone or teeth really reflects the isotopic ratios of its birth and growth places, several bone and teeth samples were measured for 87Sr/86Sr ratios, compared with 87Sr/86Sr ratios of geological samples in their growth-places. Bone and teeth samples were leached with 5% acetic acid. After drying, samples were ashed in a muffle furnace at 825°C for 8h, and then digested in nitric acid, followed by cation exchange chromatography with 2.4M hydrochloric acid. 87Sr/86Sr ratios were measured using a thermal ionization mass Spectrometer (VG Sector 54) or an inductively coupled plasma mass spectrometer (Finnigan ELEMENT2). A modern boar bone collected at Asuke, Toyota City, Aichi prefecture, Japan showed a 87Sr/86Sr of 0.71001±0.00002 (2 σ), while stream sediments in the Asuke area showed around 0.710 (Asahara et al., 2006). The 87Sr/86Sr ratio of a modern black bass bone collected from Lake Biwa, Shiga prefecture, Japan was 0.71215±0.00002, while those of surface water in Lake Biwa was 0.71233±0.00002. The similar 87Sr/86Sr ratios between bone and its provenance geology could indicate that the 87Sr/86Sr ratios of bones reflect the isotopic ratios of the birth- and growth-places. The more results of modern and fossil skeletons will be shown in our presentation.

The human operational sex ratio: effects of marriage, concealed ovulation, and menopause on mate competition.

Science.gov (United States)

Marlowe, Frank W; Berbesque, J Colette

2012-12-01

Among mammals, male-male competition for sexual access to females frequently involves fighting. Larger body size gives males an advantage in fighting, which explains why males tend to be larger than females in many species, including anthropoid primates. Mitani et al. derived a formula to measure the operational sex ratio (OSR) to reflect the degree of male-male competition using the number of reproductively available males to females who are cycling and capable of conceiving. The OSR should predict the degree of sexual dimorphism in body mass-at least if male-male competition involves much fighting or threatening. Here, we use hunter-gatherer demographic data and the Mitani et al. formula to calculate the human OSR. We show that humans have a much lower degree of body mass sexual dimorphism than is predicted by our OSR. We suggest this is because human competition rarely involves fighting. In human hunter-gatherer societies, differences in the ages of marriage have an impact on competition in that the age of males at first marriage is younger when there is a lower percentage of married men with two or more wives, and older when there is a higher percentage of married men with two or more wives. We discuss the implications of this for females, along with the effects of two key life history traits that influence the OSR, concealed ovulation and menopause. While menopause decreases the number of reproductively available females to males and thus increases male-male competition, concealed ovulation decreases male-male competition. Finally, we discuss the importance of mostly monogamous mate bonds in human evolution. Copyright © 2012 Elsevier Ltd. All rights reserved.

A Rigid Mid-Lift-to-Drag Ratio Approach to Human Mars Entry, Descent, and Landing

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Cerimele, Christopher J.; Robertson, Edward A.; Sostaric, Ronald R.; Campbell, Charles H.; Robinson, Phil; Matz, Daniel A.; Johnson, Breanna J.; Stachowiak, Susan J.; Garcia, Joseph A.; Bowles, Jeffrey V.;

Dependence of the Ce(iii)/Ce(iv) ratio on intracellular localization in ceria nanoparticles internalized by human cells

KAUST Repository

Ferraro, Daniela

2017-01-09

CeO2 nanoparticles (CNPs) have been investigated as promising antioxidant agents with significant activity in the therapy of diseases involving free radicals or oxidative stress. However, the exact mechanism responsible for CNP activity has not been completely elucidated. In particular, in situ evidence of modification of the oxidative state of CNPs in human cells and their evolution during cell internalization and subsequent intracellular distribution has never been presented. In this study we investigated modification of the Ce(iii)/Ce(iv) ratio following internalization in human cells by X-ray absorption near edge spectroscopy (XANES). From this analysis on cell pellets, we observed that CNPs incubated for 24 h showed a significant increase in Ce(iii). By coupling on individual cells synchrotron micro-X-ray fluorescence (μXRF) with micro-XANES (μXANES) we demonstrated that the Ce(iii)/Ce(iv) ratio is also dependent on CNP intracellular localization. The regions with the highest CNP concentrations, suggested to be endolysosomes by transmission electron microscopy, were characterized by Ce atoms in the Ce(iv) oxidation state, while a higher Ce(iii) content was observed in regions surrounding these areas. These observations suggest that the interaction of CNPs with cells involves a complex mechanism in which different cellular areas play different roles.

Dependence of the Ce(iii)/Ce(iv) ratio on intracellular localization in ceria nanoparticles internalized by human cells

KAUST Repository

Ferraro, Daniela; Tredici, Ilenia G.; Ghigna, Paolo; Castillio-Michel, Hiram; Falqui, Andrea; Di Benedetto, Cristiano; Alberti, Giancarla; Ricci, Vittorio; Anselmi-Tamburini, Umberto; Sommi, Patrizia

2017-01-01

CeO2 nanoparticles (CNPs) have been investigated as promising antioxidant agents with significant activity in the therapy of diseases involving free radicals or oxidative stress. However, the exact mechanism responsible for CNP activity has not been completely elucidated. In particular, in situ evidence of modification of the oxidative state of CNPs in human cells and their evolution during cell internalization and subsequent intracellular distribution has never been presented. In this study we investigated modification of the Ce(iii)/Ce(iv) ratio following internalization in human cells by X-ray absorption near edge spectroscopy (XANES). From this analysis on cell pellets, we observed that CNPs incubated for 24 h showed a significant increase in Ce(iii). By coupling on individual cells synchrotron micro-X-ray fluorescence (μXRF) with micro-XANES (μXANES) we demonstrated that the Ce(iii)/Ce(iv) ratio is also dependent on CNP intracellular localization. The regions with the highest CNP concentrations, suggested to be endolysosomes by transmission electron microscopy, were characterized by Ce atoms in the Ce(iv) oxidation state, while a higher Ce(iii) content was observed in regions surrounding these areas. These observations suggest that the interaction of CNPs with cells involves a complex mechanism in which different cellular areas play different roles.

Asthma Medication Ratio Predicts Emergency Depart...

Data.gov (United States)

U.S. Department of Health & Human Services — According to findings reported in Asthma Medication Ratio Predicts Emergency Department Visits and Hospitalizations in Children with Asthma, published in Volume 3,...

The Best of Two Open Worlds at the National Open University of Nigeria

Directory of Open Access Journals (Sweden)

Jane-frances Obiageli Agbu

2016-05-01

Full Text Available It will be wise for educational institutions, from primary to tertiary level, globally, to reflect on their position and profile with respect to the new concepts of Open Educational Resources (OER and Massive Open Online Courses (MOOCs. Responses will be diverse of course but the potential is so manifest that many institutions probably will consider the benefits to outweigh the barriers. The National Open University of Nigeria (NOUN has decided to combine its ‘classical’ openness with the new digital openness by fully embracing the OER approach and converting its complete course base into OER. Step-by-step, NOUN is currently implementing its strategy towards becoming an OER-based Open University with a special niche for MOOCs. During a launch event in December 2015, the first 40 OER-based courses were presented as well as the first 3 OER-based MOOCs. This paper therefore presents NOUN’s OER strategy with insight on lessons learned. To the authors’ knowledge NOUN is the first Open University in the world with such a full-fledged OER (& MOOCs implementation route.

Human semen quality and the secondary sex ratio.

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Bae, Jisuk; Kim, Sungduk; Chen, Zhen; Eisenberg, Michael L; Buck Louis, Germaine M

2017-01-01

The aim of this study was to evaluate the association between semen quality and the secondary sex ratio (SSR), defined as the ratio of male to female live births. Our study cohort comprised 227 male partners who were enrolled prior to conception in Michigan and Texas between 2005 and 2009, and prospectively followed through delivery of a singleton birth. The male partners provided a baseline and a follow-up semen sample a month apart. Semen analysis was conducted to assess 27 parameters including five general characteristics, six sperm head measures, 14 morphology measures, and two sperm chromatin stability assay measures. Modified Poisson regression models with a robust error variance were used to estimate the relative risk (RR) and 95% confidence interval (95% CI) of a male birth for each semen parameter, after adjusting for potential confounders. Of the 27 semen parameters, only the percentage of bicephalic sperm was significantly associated with the SSR (2 nd vs 1 st quartile, RR, 0.65, 95% CI, 0.45-0.95, P = 0.03; 4 th vs 1 st quartile, RR, 0.61, 95% CI, 0.38-1.00, P semen quality is associated with offspring sex determination.

Fostering the Exploitation of Open Educational Resources

Directory of Open Access Journals (Sweden)

Thomas Richter

2014-07-01

Full Text Available The central concept behind Open Educational Resources (OER is opening up the access to educational resources for stakeholders who are not the usual target user group. This concept must be perceived as innovative because it describes a general economic and social paradigm shift: Education, which formerly was limited to a specific group of learners, now, is promoted as a public good. However, despite very good intentions, internationally agreed quality standards, and the availability of the required technological infrastructure, the critical threshold is not yet met. Due to several reasons, the usefulness of OER is often limited to the originally targeted context. Questions arise if the existing quality standards for Technology Enhanced Learning (TEL actually meet the specific requirements within the OER value chain, if the existing quality standards are applicable to OER in a meaningful way, and under which conditions related standards generally could support the exploitation of OER.We analyze quality standards for TEL and contrast the life cycle model of commercial learning resources against the life cycle model of OER. We investigate special demands on quality from the context of OER and, taking the former results into account, derive emergent quality criteria for OER. The paper concludes with recommendations for the design of OER and a future standard development.

CD4/CD8 Ratio and KT Ratio Predict Yellow Fever Vaccine Immunogenicity in HIV-Infected Patients.

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Avelino-Silva, Vivian I; Miyaji, Karina T; Hunt, Peter W; Huang, Yong; Simoes, Marisol; Lima, Sheila B; Freire, Marcos S; Caiaffa-Filho, Helio H; Hong, Marisa A; Costa, Dayane Alves; Dias, Juliana Zanatta C; Cerqueira, Natalia B; Nishiya, Anna Shoko; Sabino, Ester Cerdeira; Sartori, Ana M; Kallas, Esper G

2016-12-01

HIV-infected individuals have deficient responses to Yellow Fever vaccine (YFV) and may be at higher risk for adverse events (AE). Chronic immune activation-characterized by low CD4/CD8 ratio or high indoleamine 2,3-dioxygenase-1 (IDO) activity-may influence vaccine response in this population. We prospectively assessed AE, viremia by the YFV virus and YF-specific neutralizing antibodies (NAb) in HIV-infected (CD4>350) and -uninfected adults through 1 year after vaccination. The effect of HIV status on initial antibody response to YFV was measured during the first 3 months following vaccination, while the effect on persistence of antibody response was measured one year following vaccination. We explored CD4/CD8 ratio, IDO activity (plasma kynurenine/tryptophan [KT] ratio) and viremia by Human Pegivirus as potential predictors of NAb response to YFV among HIV-infected participants with linear mixed models. 12 HIV-infected and 45-uninfected participants were included in the final analysis. HIV was not significantly associated with AE, YFV viremia or NAb titers through the first 3 months following vaccination. However, HIV-infected participants had 0.32 times the NAb titers observed for HIV-uninfected participants at 1 year following YFV (95% CI 0.13 to 0.83, p = 0.021), independent of sex, age and prior vaccination. In HIV-infected participants, each 10% increase in CD4/CD8 ratio predicted a mean 21% higher post-baseline YFV Nab titer (p = 0.024). Similarly, each 10% increase in KT ratio predicted a mean 21% lower post-baseline YFV Nab titer (p = 0.009). Viremia by Human Pegivirus was not significantly associated with NAb titers. HIV infection appears to decrease the durability of NAb responses to YFV, an effect that may be predicted by lower CD4/CD8 ratio or higher KT ratio.

CD4/CD8 Ratio and KT Ratio Predict Yellow Fever Vaccine Immunogenicity in HIV-Infected Patients

Science.gov (United States)

Hunt, Peter W.; Huang, Yong; Simoes, Marisol; Lima, Sheila B.; Freire, Marcos S.; Caiaffa-Filho, Helio H.; Hong, Marisa A.; Costa, Dayane Alves; Dias, Juliana Zanatta C.; Cerqueira, Natalia B.; Nishiya, Anna Shoko; Sabino, Ester Cerdeira; Sartori, Ana M.; Kallas, Esper G.

2016-01-01

Background HIV-infected individuals have deficient responses to Yellow Fever vaccine (YFV) and may be at higher risk for adverse events (AE). Chronic immune activation–characterized by low CD4/CD8 ratio or high indoleamine 2,3-dioxygenase-1 (IDO) activity—may influence vaccine response in this population. Methods We prospectively assessed AE, viremia by the YFV virus and YF-specific neutralizing antibodies (NAb) in HIV-infected (CD4>350) and -uninfected adults through 1 year after vaccination. The effect of HIV status on initial antibody response to YFV was measured during the first 3 months following vaccination, while the effect on persistence of antibody response was measured one year following vaccination. We explored CD4/CD8 ratio, IDO activity (plasma kynurenine/tryptophan [KT] ratio) and viremia by Human Pegivirus as potential predictors of NAb response to YFV among HIV-infected participants with linear mixed models. Results 12 HIV-infected and 45-uninfected participants were included in the final analysis. HIV was not significantly associated with AE, YFV viremia or NAb titers through the first 3 months following vaccination. However, HIV–infected participants had 0.32 times the NAb titers observed for HIV-uninfected participants at 1 year following YFV (95% CI 0.13 to 0.83, p = 0.021), independent of sex, age and prior vaccination. In HIV-infected participants, each 10% increase in CD4/CD8 ratio predicted a mean 21% higher post-baseline YFV Nab titer (p = 0.024). Similarly, each 10% increase in KT ratio predicted a mean 21% lower post-baseline YFV Nab titer (p = 0.009). Viremia by Human Pegivirus was not significantly associated with NAb titers. Conclusions HIV infection appears to decrease the durability of NAb responses to YFV, an effect that may be predicted by lower CD4/CD8 ratio or higher KT ratio. PMID:27941965

Neutron irradiation of bacteria in the presence and absence of secondary charged-particle equilibrium

International Nuclear Information System (INIS)

Lunec, J.; Cramp, W.A.; Hornsey, S.

1980-01-01

The survival rate of Shigella flexneri has been measured for irradiation with 7-MeV neutrons in the presence and absence of secondary charged-particle equilibrium. The data were analyzed to assess the separate response of the cells to the knock-on proton and α-particle plus heavy-recoil components. A detailed consideration of the frequency of α-particle and heavy-recoil traversals of the cell has been made to explain our results, and in addition we have applied this approach to analyze the earlier results obtained with mammalian cells. We conclude that of the secondary charged-particles produced by the Hammersmith neutron beam, the highest LET particles, the heavy-recoil nuclei, contribute a minor proportion of damage to bacteria but form a major contribution of damage in mammalian cells. The reduction in oxygen enhancement ratio (OER) with neutrons compared with low LET radiation for mammalian cells is due almost entirely to the influence of the heavy recoils and the contribution of the α-particle and knock-on protons to the reduction of the OER is relatively minor. For Shigella flexneri the α particles and heavy recoils make approximately equal contributions to the reduction in OER

The spatial patterns of water management practices are reflected in the strontium isotope ratios of human hair

Science.gov (United States)

Tipple, B. J.; Valenzuela, L. O.; Ehleringer, J.

2012-12-01

Element concentrations and isotopes of human tissues are commonly used to understand how emissions and processes within urban ecosystems affect health. Thus, it is important to understand how these elements are incorporated and flow through the urban environment and are ultimately incorporated into human tissues. Here, we designed an experiment to identify the relative importance of strontium (Sr) sources (bedrock, dust, food, and water) to hair Sr isotope ratios (87Sr/86Sr). To understand the contribution of Sr to human hair, we collected hair from individuals living in Salt Lake City, Utah. In addition to sample location, we compiled information regarding age, sex, ethnicity, and dietary habits. We found a significant association between 87Sr/86Sr value of hair and collection location. There were no significant relationships between 87Sr/86Sr value of hair and age, ethnicity, or sex. We had not predicted a relationship between 87Sr/86Sr values and collection location, because of the close proximities of sites to one another (all within an 8-km radius). We found that tap water 87Sr/86Sr values across the Salt Lake Valley varied with water management practice and this variation corresponded to hair 87Sr/86Sr value. These data suggest an additional geographically controlled source of Sr may be an important contributor to the 87Sr/86Sr value of hair. These findings suggest that local water is an important source of Sr in human hair and that hair is a sensitive temporal carrier of this environmental information. These observations have important implications to future studies of humans with regard to urban ecology, human health, forensic sciences, and anthropology.

Conceptual Framework for Parametrically Measuring the Desirability of Open Educational Resources using D-Index

Directory of Open Access Journals (Sweden)

S. Raviraja

2012-04-01

Full Text Available Open educational resources (OER are a global phenomenon that is fast gaining credibility in many academic circles as a possible solution for bridging the knowledge divide. With increased funding and advocacy from governmental and nongovernmental organisations paired with generous philanthropy, many OER repositories, which host a vast array of resources, have mushroomed over the years. As the inkling towards an open approach to education grows, many academics are contributing to these OER repositories, making them expand exponentially in volume. However, despite the volume of available OER, the uptake of the use and reuse of OER still remains slow. One of the major limitations inhibiting the wider adoption of OER is the inability of current search mechanisms to effectively locate OER that are most suitable for use and reuse within a given scenario. This is mainly due to the lack of a parametric measure that could be used by search technologies to autonomously identify desirable resources. As a possible solution to this limitation, this concept paper introduces a parametric measure of desirability of OER named the D-index, which can aid search mechanisms in better identifying resources suitable for use and reuse.

Surfing the net for public health resources.

Science.gov (United States)

Angell, C; Hemingway, A; Hartwell, H

2011-08-01

To identify public health open educational resources (OER) available online, map the identified OER to The Public Health Skills and Career Framework (PHSCF), and triangulate these findings with public health practitioners. Systematic online search for public health OER. An online search was undertaken using a pre-defined set of search terms and inclusion/exclusion criteria. Public health OER were then mapped against the UK PHSCF. The findings of the search were discussed with public health specialists to determine whether or not they used these resources. A number of public health OER were identified, located on 42 websites from around the world. Mapping against the UK PHSCF demonstrated a lack of coverage in some areas of public health education. It was noted that many of the OER websites identified were not those generally used in practice, and those sites preferred by public health specialists were not identified by the online search. Public health OER are available from a number of providers, frequently universities and government organizations. However, these reflect a relatively small pool of original OER providers. Tagging of websites does not always identify their public health content. In addition, users of public health OER may not use search engines to identify resources but locate them using other means. Copyright © 2011 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Calcium and phosphorus concentrations and the calcium/phosphorus ratio in trabecular bone from the femoral neck of healthy humans as determined by neutron activation analysis

International Nuclear Information System (INIS)

Zaichick, Vladimir; Tzaphlidou, Margaret

2003-01-01

The Ca and P concentrations as well as the Ca/P ratio were estimated in intact trabecular bone samples from the femoral neck of healthy humans, 34 women and 44 men, aged from 15 to 55 years, using instrumental neutron activation analysis. The mean values (M±SD) for the investigated parameters (on a dry-weight basis) were: 12.1±3.0%, 5.94±1.71%, 2.07±0.25 and 10.9±2.5%, 5.30±1.23%, 2.07±0.22 for females and males, respectively. A statistically significant (p≤0.05) decrease of Ca concentration with age was found only for males while the P concentration and the Ca/P ratio were not affected by age. No statistically significant sex-related differences were observed in any of the parameters. The mean values for Ca, P and the Ca/P ratio lay close to the median of the very wide range of published data. The individual variation for the Ca/P ratio in trabecular bone from the healthy human femoral neck was lower than those for Ca and P separately. This suggests that the specificity of the Ca/P ratio is better than that of Ca and P concentrations and may be more reliable for the diagnosis of bone disorders

Evaluation of Patient Migration Patterns and Related Health Care Costs Within a National Medicare Advantage Prescription Drug Plan After Implementation of an Oxycodone HCl Extended-Release Access Restriction.

Science.gov (United States)

Chen, Chi-Chang; De, Ajita P; Sweet, Brian; Wade, Rolin L

2017-08-01

Health plans use formulary restrictions (e.g., prior authorization, step therapy, tier change, nonformulary status) in an effort to control cost and promote quality, safety, and appropriate prescription utilization. Some Medicare payers perceive that the inclusion of certain agents, such as branded oxycodone HCl extended-release tablets (OERs), on their formularies is associated with attracting high-cost members to the plan. To evaluate disenrollment rates, patient migration, and subsequent health care costs among OER users who disenrolled from a national Medicare Advantage Prescription Drug plan (study-MAPD) in the plan year following OER nonformulary restriction. A retrospective, longitudinal cohort study using IMS pharmacy and medical claims data between July 1, 2011, and December 31, 2014, was conducted. In the study-MAPD, adults aged ≥ 18 years who were chronic OER users with ≥ 2 OER claims 6 months before the nonformulary restriction date on January 1, 2013 (index date) and with continuous activity in pharmacy and medical claims for 6 months pre- and post-index were included in the study. Comparison years of 2012 and 2014 prerestriction/postrestriction were selected. All groups were followed for 6 months postindex. Year-to-year disenrollment rates of OER patients and the overall plan, as well as patient characteristics and costs of those who disenrolled from and those who remained with the plan, were measured. Costs were compared using a difference-in-differences approach. This study identified 2,935 eligible OER users from the study-MAPD population after imposing nonformulary restrictions on OERs on January 1, 2013. Mean age was 62.1 years, and 59.8% were female. The mean Charlson Comorbidity Index score was 1.83 for those 1,001 patients with medical claims data. For comparison years 2012 (prerestriction) and 2014 (postrestriction), 2,248 and 2,222 OER patients were identified, respectively. Patient characteristics were similar across patient cohorts in

Ultraviolet action spectra for aerobic and anaerobic inactivation of Escherichia coli strains specifically sensitive and resistant to near ultraviolet radiations

International Nuclear Information System (INIS)

Peak, J.G.; Peak, M.J.; Tuveson, R.W.

1983-01-01

Action spectra for the lethal effects of ultraviolet light (254-434 nm) irradiation delivered under aerobic or anaerobic conditions to Escherichia coli RT2 (specifically sensitive to near-UV radiation; > 320 nm) and E. coli RT4 (near-UV resistant) were prepared. Negligible oxygen dependence was observed for both strains below about 315 nm. The oxygen enhancement ratio (OER) for RT4 increased above this wavelength to the longest wavelength used, whereas for RT2 there was a greater increase in the OER to a large peak at 365 nm, then a progressive decrease at longer wavelengths. The results are consistent with the possibility that the sensitivity of strain RT2 to near-UV radiation may be due to hyperproduction of photosensitizer, operating via photodynamic type reactions involving excited species of oxygen. (author)

Enhanced Differentiation of Human Embryonic Stem Cells Toward Definitive Endoderm on Ultrahigh Aspect Ratio Nanopillars

DEFF Research Database (Denmark)

Rasmussen, Camilla Holzmann; Reynolds, Paul M.; Petersen, Dorthe Roenn

2016-01-01

highlighted that the properties of the physical environment, such as substrate stiffness, affect cellular behavior. Here, mass-produced, injection molded polycarbonate nanopillars are presented, where the surface mechanical properties, i.e., stiffness, can be controlled by the geometric design...... of the ultrahigh aspect ratio nanopillars (stiffness can be reduced by 25.000X). It is found that tall nanopillars, yielding softer surfaces, significantly enhance the induction of defi nitive endoderm cells from pluripotent human embryonic stem cells, resulting in more consistent differentiation of a pure...... population compared to planar control. By contrast, further differentiation toward the pancreatic endoderm is less successful on “soft” pillars when compared to “stiff ” pillars or control, indicating differential cues during the different stages of differentiation. To accompany the mechanical properties...

Effect of different calcium phosphate scaffold ratios on odontogenic differentiation of human dental pulp cells

International Nuclear Information System (INIS)

AbdulQader, Sarah Talib; Kannan, Thirumulu Ponnuraj; Rahman, Ismail Ab; Ismail, Hanafi; Mahmood, Zuliani

2015-01-01

Calcium phosphate (CaP) scaffolds have been widely and successfully used with osteoblast cells for bone tissue regeneration. However, it is necessary to investigate the effects of these scaffolds on odontoblast cells' proliferation and differentiation for dentin tissue regeneration. In this study, three different hydroxyapatite (HA) to beta tricalcium phosphate (β-TCP) ratios of biphasic calcium phosphate (BCP) scaffolds, BCP20, BCP50, and BCP80, with a mean pore size of 300 μm and 65% porosity were prepared from phosphoric acid (H 2 PO 4 ) and calcium carbonate (CaCO 3 ) sintered at 1000 °C for 2 h. The extracts of these scaffolds were assessed with regard to cell viability and differentiation of odontoblasts. The high alkalinity, more calcium, and phosphate ions released that were exhibited by BCP20 decreased the viability of human dental pulp cells (HDPCs) as compared to BCP50 and BCP80. However, the cells cultured with BCP20 extract expressed high alkaline phosphatase activity and high expression level of bone sialoprotein (BSP), dental matrix protein-1 (DMP-1), and dentin sialophosphoprotein (DSPP) genes as compared to that cultured with BCP50 and BCP80 extracts. The results highlighted the effect of different scaffold ratios on the cell microenvironment and demonstrated that BCP20 scaffold can support HDPC differentiation for dentin tissue regeneration. - Highlights: • BCPs of different HA/β-TCP ratios influence cell microenvironment. • BCP20 decreases cell viability of HDPCs as compared to BCP50 and BCP80. • HDPCs cultured with BCP20 express highest ALP activity. • HDPCs cultured with BCP20 up-regulate BSP, DMP-1 and DSPP gene expressions. • BCP20 can support HDPC differentiation for dentin tissue regeneration

Effect of different calcium phosphate scaffold ratios on odontogenic differentiation of human dental pulp cells

Energy Technology Data Exchange (ETDEWEB)

AbdulQader, Sarah Talib [School of Dental Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia); Department of Pedodontic and Preventive Dentistry, College of Dentistry, University of Baghdad, Baghdad (Iraq); Kannan, Thirumulu Ponnuraj, E-mail: kannan@usm.my [School of Dental Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia); Human Genome Centre, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia); Rahman, Ismail Ab [School of Dental Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia); Ismail, Hanafi [School of Materials and Minerals Resource Engineering, Universiti Sains Malaysia, 14300 Penang (Malaysia); Mahmood, Zuliani [School of Dental Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia)

2015-04-01

Calcium phosphate (CaP) scaffolds have been widely and successfully used with osteoblast cells for bone tissue regeneration. However, it is necessary to investigate the effects of these scaffolds on odontoblast cells' proliferation and differentiation for dentin tissue regeneration. In this study, three different hydroxyapatite (HA) to beta tricalcium phosphate (β-TCP) ratios of biphasic calcium phosphate (BCP) scaffolds, BCP20, BCP50, and BCP80, with a mean pore size of 300 μm and 65% porosity were prepared from phosphoric acid (H{sub 2}PO{sub 4}) and calcium carbonate (CaCO{sub 3}) sintered at 1000 °C for 2 h. The extracts of these scaffolds were assessed with regard to cell viability and differentiation of odontoblasts. The high alkalinity, more calcium, and phosphate ions released that were exhibited by BCP20 decreased the viability of human dental pulp cells (HDPCs) as compared to BCP50 and BCP80. However, the cells cultured with BCP20 extract expressed high alkaline phosphatase activity and high expression level of bone sialoprotein (BSP), dental matrix protein-1 (DMP-1), and dentin sialophosphoprotein (DSPP) genes as compared to that cultured with BCP50 and BCP80 extracts. The results highlighted the effect of different scaffold ratios on the cell microenvironment and demonstrated that BCP20 scaffold can support HDPC differentiation for dentin tissue regeneration. - Highlights: • BCPs of different HA/β-TCP ratios influence cell microenvironment. • BCP20 decreases cell viability of HDPCs as compared to BCP50 and BCP80. • HDPCs cultured with BCP20 express highest ALP activity. • HDPCs cultured with BCP20 up-regulate BSP, DMP-1 and DSPP gene expressions. • BCP20 can support HDPC differentiation for dentin tissue regeneration.

Radiosensitization of mammalian cells by misonidazole and oxygen: DNA damage exposed by Micrococcus luteus enzymes

International Nuclear Information System (INIS)

Skov, K.A.; Palcic, B.; Skarsgard, L.D.

1979-01-01

When misonidazole is present during irradiation of hypoxic mammalian cells, an enhancement of single-strand breaks (SSB) in DNA is observed. Oxygen also enhances SSB, presumably in a manner similar to that of misonidazole. The dose-modifying factor (DMF) for 15 mM misonidazole was found to be 3.4, compared to an oxygen enhancement ratio (OER) of 3.5. Another class of DNA damage, namely, sites exposed by an extract of Micrococcus luteus, was examined. Radiation-induced M. luteus extract-sensitive sites (MLS) were also found to be enhanced by the presence of misonidazole or molecular oxygen. The DMF for this damage by 15 mM misonidazole was 1.6 while the OER was 2.5. The ratio of MLS to SSB is approximately 1.25 under hypoxia, 0.9 in the presence of oxygen, and 0.6 in the presence of 15 mM misonidazole under hypoxic conditions. Incubation with misonidazole under conditions which are toxic to mammalian cells (37 0 C, hypoxia), and which result in many SSB, produces no detectable lesions sensitive to the M. luteus extract

Exposure to widespread environmental endocrine disrupting chemicals and human sperm sex ratio

International Nuclear Information System (INIS)

Jurewicz, Joanna; Radwan, Michał; Sobala, Wojciech; Radwan, Paweł; Jakubowski, Lucjusz; Wielgomas, Bartosz; Ligocka, Danuta; Brzeźnicki, Sławomir; Hanke, Wojciech

2016-01-01

In recent years, a trend toward a declining proportion of male births has been noted in several, but not all, industrialized countries. The underlying reason for the drop in the sex ratio is unclear, but one theory states that widespread environmental endocrine disrupting chemicals affecting the male reproductive system in a negative manner could be part of the explanation. The present study was designed to investigate whether the urinary phthalate, pyrethroids and polycyclic aromatic hydrocarbons metabolites concentrations were associated with sperm Y:X ratio. The study population consisted of 194 men aged under 45 years of age who attended infertility clinic in Lodz, Poland for diagnostic purposes with normal semen concentration of 20–300 mln/ml or with slight oligozoospermia (semen concentration of 15–20 mln/ml) (WHO, 1999). The Y:X ratio was assessed by fluorescent in situ hybridization. Urinary concentrations of 1-hydroxypyrene were measured by high performance liquid chromatography, phthalate metabolites were analyzed using a procedure based on the LC-MS/MS methods and metabolites of synthetic pyrethroids were assessed by gas chromatography ion-tap mass spectrometry method. After adjustment for potential confounders (past diseases, age, abstinence, smoking, alcohol consumption, sperm concentration, motility, morphology) 5OH MEHP, CDCCA to TDCCA and 1-OHP was negatively related to Y:X sperm chromosome ratio (p = 0.033, p < 0.001, p = 0.047 respectively). As this is the first study to elucidate the association between the level of metabolites of widespread environmental endocrine disrupting chemicals (phthalates, synthetic pyrethroids, polycyclic aromatic hydrocarbons) on sex chromosome ratio in sperm therefore, these findings require further replication in other populations. - Highlights: • Urinary phthalate metabolites levels were significantly associated with a decrease in Y/X chromosome bearing sperm. • The levels of 1-hydroxypyrene in urine

Sex ratios in the two Germanies: a test of the economic stress hypothesis.

Science.gov (United States)

Catalano, Ralph A

2003-09-01

Literature describing temporal variation in the secondary sex ratio among humans reports an association between population stressors and declines in the odds of male birth. Explanations of this phenomenon draw on reports that stressed females spontaneously abort male more than female fetuses, and that stressed males exhibit reduced sperm motility. This work has led to the argument that population stress induced by a declining economy reduces the human sex ratio. No direct test of this hypothesis appears in the literature. Here, a test is offered based on a comparison of the sex ratio in East and West Germany for the years 1946 to 1999. The theory suggests that the East German sex ratio should be lower in 1991, when East Germany's economy collapsed, than expected from its own history and from the sex ratio in West Germany. The hypothesis is tested using time-series modelling methods. The data support the hypothesis. The sex ratio in East Germany was at its lowest in 1991. This first direct test supports the hypothesis that economic decline reduces the human sex ratio.

Why is digit ratio correlated to sports performance?

Science.gov (United States)

Kim, Tae Beom; Kim, Khae Hawn

2016-12-01

Second to fourth digit ratio is the ratio of second to fourth digit length. It has been known that digit ratio is sexually dimorphic in humans, such that males tend to have lower digit ratio (longer fourth digits relative to second digits) than females. Digit ratio is thought to be a biomarker of the balance between fetal testosterone (FT) and fetal estrogen (FE) in a relatively narrow developmental window at the end of the first trimester of pregnancy. On the contrary, the relationships between digit ratio and levels of sex steroids in adults are not clear. Most correlational studies between digit ratio and adult sex steroids have revealed that this association is statistically not significant. However, for many years, a lot of researches showed negative relationships between digit ratio and sports performance such as rugby, surfing, rowing, sprinting, endurance, and hand grip strength. Here, we discuss possible mechanisms about the relationships between digit ratio and sports performance.

Controlling electrodeposited ultrathin amorphous Fe hydroxides film on V-doped nickel sulfide nanowires as efficient electrocatalyst for water oxidation

Science.gov (United States)

Shang, Xiao; Yan, Kai-Li; Lu, Shan-Shan; Dong, Bin; Gao, Wen-Kun; Chi, Jing-Qi; Liu, Zi-Zhang; Chai, Yong-Ming; Liu, Chen-Guang

2017-09-01

Developing cost-effective electrocatalysts with both high activity and stability remains challenging for oxygen evolution reaction (OER) in water electrolysis. Herein, based on V-doped nickel sulfide nanowire on nickel foam (NiVS/NF), we further conduct controllable electrodeposition of Fe hydroxides film on NiVS/NF (eFe/NiVS/NF) to further improve OER performance and stability. For comparison, ultrafast chemical deposition of Fe hydroxides on NiVS/NF (uFe/NiVS/NF) is also utilized. V-doping of NiVS/NF may introduce more active sites for OER, and nanowire structure can expose abundant active sites and facilitate mass transport. Both of the two depositions generate amorphous Fe hydroxides film covering on the surface of nanowires and lead to enhanced OER activities. Furthermore, electrodeposition strategy realizes uniform Fe hydroxides film on eFe/NiVS/NF confirmed by superior OER activity of eFe/NiVS/NF than uFe/NiVS/NF with relatively enhanced stability. The OER activity of eFe/NiVS/NF depends on various electrodepositon time, and the optimal time (15 s) is obtained with maximum OER activity. Therefore, the controllable electrodeposition of Fe may provide an efficient and simple strategy to enhance the OER properties of electrocatalysts.

13CO2/12CO2 isotope ratio analysis in human breath using a 2 μm diode laser

Science.gov (United States)

Sun, Mingguo; Cao, Zhensong; Liu, Kun; Wang, Guishi; Tan, Tu; Gao, Xiaoming; Chen, Weidong; Yinbo, Huang; Ruizhong, Rao

2015-04-01

The bacterium H. pylori is believed to cause peptic ulcer. H. pylori infection in the human stomach can be diagnosed through a CO2 isotope ratio measure in exhaled breath. A laser spectrometer based on a distributed-feedback semiconductor diode laser at 2 μm is developed to measure the changes of 13CO2/12CO2 isotope ratio in exhaled breath sample with the CO2 concentration of ~4%. It is characterized by a simplified optical layout, in which a single detector and associated electronics are used to probe CO2 spectrum. A new type multi-passes cell with 12 cm long base length , 29 m optical path length in total and 280 cm3 volume is used in this work. The temperature and pressure are well controlled at 301.15 K and 6.66 kPa with fluctuation amplitude of 25 mK and 6.7 Pa, respectively. The best 13δ precision of 0.06o was achieved by using wavelet denoising and Kalman filter. The application of denoising and Kalman filter not only improved the signal to noise ratio, but also shorten the system response time.

Exploration of Open Educational Resources in Non-English Speaking Communities

Directory of Open Access Journals (Sweden)

Cristobal Cobo

2013-06-01

Full Text Available Over the last decade, open educational resources (OER initiatives have created new possibilities for knowledge-sharing practices. This research examines how, where, and when OER are attracting attention in the higher education sector and explores to what extent the OER discussion has moved beyond the English-speaking world. This study analysed English, Spanish, and Portuguese OER queries over a long-term period (2007-2011. The data retrieval was conducted using four online platforms: two academic journal databases (Web of Knowledge and Scopus, one video-sharing Web site (YouTube, and one document-sharing Web site (Scribd. The number (more than 32,860 of search results collected indicate an increasing interest in online OER discussion across languages, particularly outside academic journal databases. Additionally, a widening ‘language gap’ between OER discussions in English and other languages was identified in several platforms. This research reports some of the cultural and language challenges caused by the expansion of the OER discussion and highlights relevant findings in this field.

Exploration of open educational resources in non-English speaking communities

OpenAIRE

Cristobal Cobo

2013-01-01

Over the last decade, open educational resources (OER) initiatives have created new possibilities for knowledge-sharing practices. This research examines how, where, and when OER are attracting attention in the higher education sector and explores to what extent the OER discussion has moved beyond the English-speaking world. This study analysed English, Spanish, and Portuguese OER queries over a long-term period (2007-2011). The data retrieval was conducted using four online platforms: two ac...

Radiographic measurement of the cardiothoracic ratio in pet macaques from Sulawesi, Indonesia

Energy Technology Data Exchange (ETDEWEB)

Schillaci, Michael A. [Department of Social Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4 (Canada)], E-mail: schillaci@utsc.utoronto.ca; Parish, Stephanie [Department of Social Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4 (Canada); Jones-Engel, Lisa [National Primate Research Center, University of Washington, 1705 N.E. Pacific Street, Seattle, WA 98195 (United States)

2009-11-15

The relative size of the heart, as measured by the cardiothoracic ratio, is often used as an index of ventricular hypertrophy-an important measure of myocardial pathophysiology in human primates. Despite its widespread use in human medicine, use of the cardiothoracic ratio in nonhuman primate veterinary medicine has been poorly documented. This report describes the results of our radiographic study of the cardiothoracic ratio in a sample of pet monkeys from Sulawesi, Indonesia. We assessed the effects of age and sex on cardiothoracic ratios, and compared our estimates with those presented in the literature for the Formosan macaque (Macaca cyclopis). Our results indicated a significant difference between the Sulawesi macaque species groupings in cardiothoracic ratios. Sex and age-related differences were not significant. Comparisons of cardiothoracic ratios with published ratios indicated similarity between M. cyclopis and Macaca nigra, but not between M. cyclopis and Macaca tonkeana.

Radiographic measurement of the cardiothoracic ratio in pet macaques from Sulawesi, Indonesia

International Nuclear Information System (INIS)

Schillaci, Michael A.; Parish, Stephanie; Jones-Engel, Lisa

2009-01-01

The relative size of the heart, as measured by the cardiothoracic ratio, is often used as an index of ventricular hypertrophy-an important measure of myocardial pathophysiology in human primates. Despite its widespread use in human medicine, use of the cardiothoracic ratio in nonhuman primate veterinary medicine has been poorly documented. This report describes the results of our radiographic study of the cardiothoracic ratio in a sample of pet monkeys from Sulawesi, Indonesia. We assessed the effects of age and sex on cardiothoracic ratios, and compared our estimates with those presented in the literature for the Formosan macaque (Macaca cyclopis). Our results indicated a significant difference between the Sulawesi macaque species groupings in cardiothoracic ratios. Sex and age-related differences were not significant. Comparisons of cardiothoracic ratios with published ratios indicated similarity between M. cyclopis and Macaca nigra, but not between M. cyclopis and Macaca tonkeana.

Recognizing Multi-user Activities using Wearable Sensors in a Smart Home

DEFF Research Database (Denmark)

Wang, Liang; Gu, Tao; Tao, Xianping

2010-01-01

The advances of wearable sensors and wireless networks oer many opportunities to recognize human activities from sensor readings in pervasive computing. Existing work so far focuses mainly on recognizing activities of a single user in a home environment. However, there are typically multiple inha...

Invited review: sex ratio and rheumatic disease.

Science.gov (United States)

Lockshin, M D

2001-11-01

Human illnesses affect men and women differently. In some cases (diseases of sex organs, diseases resulting from X or Y chromosome mutations), reasons for sex discrepancy are obvious, but in other cases no reason is apparent. Explanations for sex discrepancy of illness occur at different biological levels: molecular (e.g., imprinting, X-inactivation), cellular (sex-specific receptor activity), organ (endocrine influences), whole organism (size, age), and environmental-behavioral, including intrauterine influences. Autoimmunity represents a prototypical class of illness that has high female-to-male (F/M) ratios. Although the F/M ratios in autoimmune diseases are usually attributed to the influence of estrogenic hormones, evidence demonstrates that the attributed ratios are imprecise and that definitions and classifications of autoimmune diseases vary, rendering at least part of the counting imprecise. In addition, many studies on sex discrepancy of human disease fail to distinguish between disease incidence and disease severity. In April 2001, the Institute of Medicine of the National Academy of Sciences published Exploring the Biological Contributions to Human Health: Does Sex Matter? (Wizemann T and Pardue M-L, editors). This minireview summarizes the section of that report that concerns autoimmune and infectious disease. Some thyroid, rheumatic, and hepatic autoimmune diseases have high F/M ratios, whereas others have low. Those that have high ratios occur primarily in young adulthood. Gonadal hormones, if they play a role, likely do so through a threshold or permissive mechanism. Examples of sex differences that could be caused by environmental exposure, X inactivation, imprinting, X or Y chromosome genetic modulators, and intrauterine influences are presented as alternate, theoretical, and largely unexplored explanations for sex differences of incidence. The epidemiology of autoimmune diseases (young, female) suggests that an explanation for sex discrepancy of

Precise isotope ratio and multielement determination in prehistoric and historic human skeletal remains by HR-ICPMS - a novel application to shed light onto anthropological and archaeological questions

International Nuclear Information System (INIS)

Watkins, M.

2000-12-01

The primary aim of the presented work was the analytical setup for fast (including high sample throughput for statistical evaluation), precise and accurate measurement of strontium isotope ratios using HR-ICPMS (high-resolution inductively coupled plasma mass spectrometry) and their application to ancient human skeletal remains from different localities for the reconstruction of migration processes. Soils and plants are in isotopic equilibrium with local source rock and show therefore the same isotopic ratios for strontium (87Sr/86Sr). Dietary strontium incorporation varies for different body materials (teeth, muscle, bone, etc.) and repository periods depend on the different strontium turnover rates. Accordingly, strontium isotope analysis can provide important data for studying human or animal migration and mobility. An important issue will be addressed: the problem of strontium isotope ratio measurement reliability and the problem of post-mortem alterations. Thus a basic part of this interdisciplinary project is dealing with the systematic evaluation of diagenetic changes of the microstructure in human bone samples - including sample uptake and preparation. Different invasive histological techniques will be applied for further clarification. Newly developed chemical methods give us the opportunity to obtain details on ancient population mobility also in skeletal series of extreme fragmentary character, which usually restricts the macro-morphological approach. Since it is evident that strontium in teeth is only incorporated during childhood whereas strontium uptake in bones is constant, an intra-individual comparison of bone and teeth samples will answer the question whether teeth are indeed 'archives of the childhood'. The introduction of an analytical system allowing online matrix separation by High Performance Ion Chromatography (HPIC) and subsequent measurement of strontium isotope ratios by means of HR-ICPMS is presented, optimized and established as method

Precise Isotope ratio and multielement determination in prehistoric and historic human skeletal remains by HR-ICPMS - a novel application to shed light onto anthropological and archaeological questions

International Nuclear Information System (INIS)

Watkins, M.

2000-12-01

The primary aim of the presented work was the analytical setup for fast (including high sample throughput for statistical evaluation), precise and accurate measurement of strontium isotope ratios using HR-ICPMS (high-resolution inductively coupled plasma mass spectrometry) and their application to ancient human skeletal remains from different localities for the reconstruction of migration processes. Soils and plants are in isotopic equilibrium with local source rock and show therefore the same isotopic ratios for strontium (87Sr/86Sr). Dietary strontium incorporation varies for different body materials (teeth, muscle, bone, etc.) and repository periods depend on the different strontium turnover rates. Accordingly, strontium isotope analysis can provide important data for studying human or animal migration and mobility. An important issue will be addressed: the problem of strontium isotope ratio measurement reliability and the problem of post-mortem alterations. Thus a basic part of this interdisciplinary project is dealing with the systematic evaluation of diagenetic changes of the microstructure in human bone samples - including sample uptake and preparation. Different invasive histological techniques will be applied for further clarification. Newly developed chemical methods give us the opportunity to obtain details on ancient population mobility also in skeletal series of extreme fragmentary character, which usually restricts the macro-morphological approach. Since it is evident that strontium in teeth is only incorporated during childhood whereas strontium uptake in bones is constant, an intra-individual comparison of bone and teeth samples will answer the question whether teeth are indeed 'archives of the childhood'. The introduction of an analytical system allowing online matrix separation by High Performance Ion Chromatography (HPIC) and subsequent measurement of strontium isotope ratios by means of HR-ICPMS is presented, optimized and established as method

Coupling between the blood lactate-to-pyruvate ratio and MCA Vmean at the onset of exercise in humans

DEFF Research Database (Denmark)

Rasmussen, Peter; Madsen, Camilla A; Nielsen, Henning B

2009-01-01

Activation-induced increase in cerebral blood flow is coupled to enhanced metabolic activity, maybe with brain tissue redox state and oxygen tension as key modulators. To evaluate this hypothesis at the onset of exercise in humans, blood was sampled at 0.1 to 0.2 Hz from the radial artery and right...... internal jugular vein, while middle cerebral artery mean flow velocity (MCA V(mean)) was recorded. Both the arterial and venous lactate-to-pyruvate ratio increased after 10 s (P capillary...... state and oxygenation as potential modulators of an increase in cerebral blood flow at the onset of exercise....

NOAA Office of Exploration and Research > Education > Overview

Science.gov (United States)

Organization Guiding Documents Organizational Structure Map of Staff and Affiliate Locations Strategic Plan Evaluation Education Overview Home About OER Overview Organization Guiding Documents Organizational Structure The mission of the OER Education Program is to support OER's vision and mission by reaching out in new

Oxygen Evolution at Hematite Surfaces: The Impact of Structure and Oxygen Vacancies on Lowering the Overpotential

NARCIS (Netherlands)

Zhang, X.; Klaver, P.; van Santen, R.; van de Sanden, M. C. M.; Bieberle, A.

2016-01-01

Simulations of the oxygen evolution reaction (OER) are essential for understanding the limitations of water splitting. Most research has focused so far on the OER at flat metal oxide surfaces. The structure sensitivity of the OER has, however, recently been highlighted as a promising research

Derivation of Two Critical Appraisal Scores for Trainees to Evaluate Online Educational Resources: A METRIQ Study

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Teresa M. Chan

2016-09-01

Full Text Available Introduction: Online education resources (OERs, like blogs and podcasts, increasingly augment or replace traditional medical education resources such as textbooks and lectures. Trainees’ ability to evaluate these resources is poor, and few quality assessment aids have been developed to assist them. This study aimed to derive a quality evaluation instrument for this purpose. Methods: We used a three-phase methodology. In Phase 1, a previously derived list of 151 OER quality indicators was reduced to 13 items using data from published consensus-building studies (of medical educators, expert podcasters, and expert bloggers and subsequent evaluation by our team. In Phase 2, these 13 items were converted to seven-point Likert scales used by trainee raters (n=40 to evaluate 39 OERs. The reliability and usability of these 13 rating items was determined using responses from trainee raters, and top items were used to create two OER quality evaluation instruments. In Phase 3, these instruments were compared to an external certification process (the ALiEM AIR certification and the gestalt evaluation of the same 39 blog posts by 20 faculty educators. Results: Two quality-evaluation instruments were derived with fair inter-rater reliability: the METRIQ-8 Score (Inter class correlation coefficient [ICC]=0.30, p<0.001 and the METRIQ-5 Score (ICC=0.22, p<0.001. Both scores, when calculated using the derivation data, correlated with educator gestalt (Pearson’s r=0.35, p=0.03 and r=0.41, p<0.01, respectively and were related to increased odds of receiving an ALiEM AIR certification (odds ratio=1.28, p=0.03; OR=1.5, p=0.004, respectively. Conclusion: Two novel scoring instruments with adequate psychometric properties were derived to assist trainees in evaluating OER quality and correlated favourably with gestalt ratings of online educational resources by faculty educators. Further testing is needed to ensure these instruments are accurate when applied by

Derivation of Two Critical Appraisal Scores for Trainees to Evaluate Online Educational Resources: A METRIQ Study

Science.gov (United States)

Chan, Teresa M.; Thoma, Brent; Krishnan, Keeth; Lin, Michelle; Carpenter, Christopher R.; Astin, Matt; Kulasegaram, Kulamakan

2016-01-01

Introduction Online education resources (OERs), like blogs and podcasts, increasingly augment or replace traditional medical education resources such as textbooks and lectures. Trainees’ ability to evaluate these resources is poor, and few quality assessment aids have been developed to assist them. This study aimed to derive a quality evaluation instrument for this purpose. Methods We used a three-phase methodology. In Phase 1, a previously derived list of 151 OER quality indicators was reduced to 13 items using data from published consensus-building studies (of medical educators, expert podcasters, and expert bloggers) and subsequent evaluation by our team. In Phase 2, these 13 items were converted to seven-point Likert scales used by trainee raters (n=40) to evaluate 39 OERs. The reliability and usability of these 13 rating items was determined using responses from trainee raters, and top items were used to create two OER quality evaluation instruments. In Phase 3, these instruments were compared to an external certification process (the ALiEM AIR certification) and the gestalt evaluation of the same 39 blog posts by 20 faculty educators. Results Two quality-evaluation instruments were derived with fair inter-rater reliability: the METRIQ-8 Score (Inter class correlation coefficient [ICC]=0.30, p<0.001) and the METRIQ-5 Score (ICC=0.22, p<0.001). Both scores, when calculated using the derivation data, correlated with educator gestalt (Pearson’s r=0.35, p=0.03 and r=0.41, p<0.01, respectively) and were related to increased odds of receiving an ALiEM AIR certification (odds ratio=1.28, p=0.03; OR=1.5, p=0.004, respectively). Conclusion Two novel scoring instruments with adequate psychometric properties were derived to assist trainees in evaluating OER quality and correlated favourably with gestalt ratings of online educational resources by faculty educators. Further testing is needed to ensure these instruments are accurate when applied by trainees. PMID

Patterns and Environmental Determinants of Medicinal Plant : Vascular Plant Ratios in Xinjiang, Northwest China

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Zhang, Bengang; Xiao, Peigen; Qi, Yaodong; Zhang, Zhao; Liu, Haitao; Li, Xiaojin; Wang, Guoping; Terwei, André

2016-01-01

With both a full collection of native vascular plant distributions and a full checklist of source plants of the Chinese Materia Medica (CMM), the Uygur Medicine (UM), and the Kazak Medicine (KM) for the Xinjiang region, we defined medicinal plant: vascular plant ratios (simplified as medicinal plant ratios hereafter) as the value of medicinal plant richness divided by vascular plant richness. We aimed to find whether the ratios are constant or change in different environments, which environmental variables determine medicinal plant ratios, and whether the ratios are more influenced by human or by natural environments. Finally, suggestions for medicinal plant conservation were addressed. We found that (1) medicinal plant ratios were not constant, and they were high in the Tarim Basin which was largely covered by desert, while they were relatively low in mountainous areas, especially in the Tianshan Mountains where the general species richness was high; (2) medicinal plant ratios were not significantly influenced by human activities, indicated by human population density distributions, but they were highly correlated with plant species richness and climate, i.e. ratios decreased with plant species richness and MAP, and were related quadratically with MAT; (3) CMM ratio and UM ratio were more influenced by plant richness than by climate, while KM ratio was more influenced by climate. We concluded that the percentages of plants used as medicines were not influenced by distances from human settlements, but were determined by species richness or climate. We suggest that (1), in general, the medicinal plant ratio could be a complementary indicator for medicinal plant conservation planning and (2), for the region of Xinjiang, not only high diversity areas, but also some extreme environments should be considered as compensation for a better protection of medicinal plants. PMID:27391239

Patterns and Environmental Determinants of Medicinal Plant : Vascular Plant Ratios in Xinjiang, Northwest China.

Directory of Open Access Journals (Sweden)

Liping Li

Full Text Available With both a full collection of native vascular plant distributions and a full checklist of source plants of the Chinese Materia Medica (CMM, the Uygur Medicine (UM, and the Kazak Medicine (KM for the Xinjiang region, we defined medicinal plant: vascular plant ratios (simplified as medicinal plant ratios hereafter as the value of medicinal plant richness divided by vascular plant richness. We aimed to find whether the ratios are constant or change in different environments, which environmental variables determine medicinal plant ratios, and whether the ratios are more influenced by human or by natural environments. Finally, suggestions for medicinal plant conservation were addressed. We found that (1 medicinal plant ratios were not constant, and they were high in the Tarim Basin which was largely covered by desert, while they were relatively low in mountainous areas, especially in the Tianshan Mountains where the general species richness was high; (2 medicinal plant ratios were not significantly influenced by human activities, indicated by human population density distributions, but they were highly correlated with plant species richness and climate, i.e. ratios decreased with plant species richness and MAP, and were related quadratically with MAT; (3 CMM ratio and UM ratio were more influenced by plant richness than by climate, while KM ratio was more influenced by climate. We concluded that the percentages of plants used as medicines were not influenced by distances from human settlements, but were determined by species richness or climate. We suggest that (1, in general, the medicinal plant ratio could be a complementary indicator for medicinal plant conservation planning and (2, for the region of Xinjiang, not only high diversity areas, but also some extreme environments should be considered as compensation for a better protection of medicinal plants.

Patterns and Environmental Determinants of Medicinal Plant : Vascular Plant Ratios in Xinjiang, Northwest China.

Science.gov (United States)

Li, Liping; Zhang, Bengang; Xiao, Peigen; Qi, Yaodong; Zhang, Zhao; Liu, Haitao; Li, Xiaojin; Wang, Guoping; Terwei, André

2016-01-01

With both a full collection of native vascular plant distributions and a full checklist of source plants of the Chinese Materia Medica (CMM), the Uygur Medicine (UM), and the Kazak Medicine (KM) for the Xinjiang region, we defined medicinal plant: vascular plant ratios (simplified as medicinal plant ratios hereafter) as the value of medicinal plant richness divided by vascular plant richness. We aimed to find whether the ratios are constant or change in different environments, which environmental variables determine medicinal plant ratios, and whether the ratios are more influenced by human or by natural environments. Finally, suggestions for medicinal plant conservation were addressed. We found that (1) medicinal plant ratios were not constant, and they were high in the Tarim Basin which was largely covered by desert, while they were relatively low in mountainous areas, especially in the Tianshan Mountains where the general species richness was high; (2) medicinal plant ratios were not significantly influenced by human activities, indicated by human population density distributions, but they were highly correlated with plant species richness and climate, i.e. ratios decreased with plant species richness and MAP, and were related quadratically with MAT; (3) CMM ratio and UM ratio were more influenced by plant richness than by climate, while KM ratio was more influenced by climate. We concluded that the percentages of plants used as medicines were not influenced by distances from human settlements, but were determined by species richness or climate. We suggest that (1), in general, the medicinal plant ratio could be a complementary indicator for medicinal plant conservation planning and (2), for the region of Xinjiang, not only high diversity areas, but also some extreme environments should be considered as compensation for a better protection of medicinal plants.

The sex ratio distortion in the human head louse is conserved over time

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Biliński Szczepan M

2004-05-01

Full Text Available Abstract Background At the turn of the 19th century the first observations of a female-biased sex ratio in broods and populations of the head louse, Pediculus humanus capitis, had been reported. A study by Buxton in 1940 on the sex ratio of lice on prisoners in Ceylon is still today the subject of reanalyses. This sex ratio distortion had been detected in ten different countries. In the last sixty years no new data have been collected, especially on scalp infestations under economically and socially more developed conditions. Results Here we report a female bias of head lice in a survey of 480 school children in Argentina. This bias is independent of the intensity of the pediculosis, which makes local mate competition highly unlikely as the source of the aberrant sex ratio; however, other possible adaptive mechanisms cannot be discounted. These lice as well as lice from pupils in Britain were carrying several strains of the endosymbiotic bacterium Wolbachia pipientis, one of the most wide spread intracellular sex ratio distorters. Similar Wolbachia strains are also present in the pig louse, Haematopinus suis, suggesting that this endosymbiont might have a marked influence on the biology of the whole order. The presence of a related obligate nutritional bacterium in lice prevents the investigation of a causal link between sex ratio and endosymbionts. Conclusions Regardless of its origin, this sex ratio distortion in head lice that has been reported world wide, is stable over time and is a remarkable deviation from the stability of frequency-dependent selection of Fisher's sex ratio. A female bias first reported in 1898 is still present over a hundred years and a thousand generations later.

Selenium and mercury molar ratios in saltwater fish from New Jersey: Individual and species variability complicate use in human health fish consumption advisories☆

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Burger, Joanna; Gochfeld, Michael

2014-01-01

Balancing risk versus benefits to humans and other organisms from consuming fish is a national concern in the USA, as well as in many other parts of the world. Protecting public health is both a federal and state responsibility, and states respond by issuing fish consumption advisories, particularly for mercury. Recently it has been emphasized that the protective role of selenium against mercury toxicity depends on their molar ratios, which should be evaluated as an indication of selenium’s protective capacity, and incorporated in risk assessments for fish consumption. However, there is no single “protective” ratio agreed upon. In this paper we examine the selenium:mercury (Se:Hg) molar ratios in a wide range of saltwater fish caught and eaten by recreational fishers along the New Jersey coast. We were particularly interested in interspecific and intraspecific variability, and whether the molar ratios were consistent within a species, allowing for its use in managing risk. The selenium–mercury molar ratio showed significant variation among and within fish species. The molar ratio decreased with the size of the fish species, decreased with the mercury levels, and within a fish species, the selenium:mercury ratio decreased with fish size. As an essential element, selenium undergoes some homeostatic regulation, but it is also highly toxic. Within species, mercury level tends to increase with size, accounting for the negative relationship between size and ratio. This variability may make it difficult to use the selenium:mercury molar ratio in risk assessment, risk management, and risk communication at this time, and more information is needed on how mercury and selenium actually interact and on the relationship between the molar ratios and health outcomes. PMID:22405995

Oxygen evolution reaction in nanoconfined carbon nanotubes

Science.gov (United States)

Li, Ying; Lu, Xuefeng; Li, Yunfang; Zhang, Xueqing

2018-05-01

Improving oxygen electrochemistry through nanoscopic confinement has recently been highlighted as a promising strategy. In-depth understanding the role of confinement is therefore required. In this study, we simulate the oxygen evolution reaction (OER) on iron oxide nanoclusters under confinement of (7,7) and (8,8) armchair carbon nanotubes (CNTs). The free energies of the four proton coupled electron transfer (PCET) steps and the OER overpotentials are calculated. The Fe4O6 nanocluster confined in (7,7) CNT is found to be the most active for OER among the systems considered in this work. This leads to an increase in catalytic efficiency of OER compared to the hematite (110) surface, which was reported recently as an active surface towards OER. The calculated results show that the OER overpotential depends strongly on the magnetic properties of the iron oxide nanocluster. These findings are helpful for experimental design of efficient catalyst for water splitting applications.

Critical Spaces for Critical Times: Global Conversations in Literacy Research as an Open Professional Development and Practices Resource

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Peggy Albers

2015-09-01

Full Text Available This paper reflects an OER (Open Educational Resources critical literacy project, Global Conversations in Literacy Research (GCLR, (www.globalconversationsinliteracy.wordpress.com, now in its fourth year. GCLR annually hosts seven web seminars presented by internationally recognized literacy and education scholars. We outline key dimensions of GCLR not only as an OER but as an open educational practice (OEP (Andrade et al., 2011 that through its design, not only provides open access to scholarship, but also understands the critical nexus among resources, practices and theory. Informed by data from a longitudinal study, this paper situates these dimensions within professional development literature, and outlines GCLR as a critical space designed for critical times, and the importance of intentionality when accessing OER. Like scholars before us, we argue that that availability is not the only consideration when using OER (Andrade et al., 2011; OER must be considered in relation to pedagogical considerations and how OER are used as a critical component to online professional development.

The Organizational Impact of Open Educational Resources

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Sclater, Niall

The open educational resource (OER) movement has been growing rapidly since 2001, stimulated by funding from benefactors such as the Hewlett Foundation and UNESCO, and providing educational content freely to institutions and learners across the world. Individuals and organizations are motivated by a variety of drivers to produce OERs, both altruistic and self-interested. There are parallels with the open source movement, where authors and others combine their efforts to provide a product which they and others can use freely and adapt to their own purposes. There are many different ways in which OER initiatives are organized and an infinite range of possibilities for how the OERs themselves are constituted. If institutions are to develop sustainable OER initiatives, they need to build successful change management initiatives, developing models for the production and quality assurance of OERs, licensing them through appropriate mechanisms such as the Creative Commons, and considering how the resources will be discovered and used by learners.

The LOGIC of National Policies and Strategies for Open Educational Resources

Directory of Open Access Journals (Sweden)

Fred Mulder

2013-06-01

Full Text Available In its first decade (2001-2010 the OER movement has been carried by numerous relevant and successful projects around the globe. These were sometimes large-scale but more often not, and they were primarily initiated by innovating educational institutions and explorative individual experts. What has remained, however, is the quest for a sustainable perspective, in spite of the many attempts in the OER community for clear-cut solutions to the problem of sustainability. This is a major barrier for mainstreaming the OER approach in national educational systems.At the end of the first decade, and more so at the beginning of the second decade (2011-2020, we are witnessing in a few countries emerging efforts to develop and establish a national OER approach. That is required in order to break down the barrier for mainstreaming OER. Making the OER approach sustainable cannot be left to the educational institutions only, but should be facilitated in a national setting.

Multimedia Open Educational Resources in Mathematics for High School Students with Learning Disabilities

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Park, Sanghoon; McLeod, Kenneth

2018-01-01

Open Educational Resources (OER) can offer educators the necessary flexibility for tailoring educational resources to better fit their educational goals. Although the number of OER repositories is growing fast, few studies have been conducted to empirically test the effectiveness of OER integration in the classroom. Furthermore, very little is…

Simplified derivation of stopping power ratio in the human body from dual-energy CT data.

Science.gov (United States)

Saito, Masatoshi; Sagara, Shota

2017-08-01

The main objective of this study is to propose an alternative parameterization for the empirical relation between mean excitation energies (I-value) and effective atomic numbers (Z eff ) of human tissues, and to present a simplified formulation (which we called DEEDZ-SPR) for deriving the stopping power ratio (SPR) from dual-energy (DE) CT data via electron density (ρ e ) and Z eff calibration. We performed a numerical analysis of this DEEDZ-SPR method for the human-body-equivalent tissues of ICRU Report 46, as objects of interest with unknown SPR and ρ e . The attenuation coefficients of these materials were calculated using the XCOM photon cross-sections database. We also applied the DEEDZ-SPR conversion to experimental DECT data available in the literature, which was measured for the tissue-characterization phantom using a dual-source CT scanner at 80 kV and 140 kV/Sn. It was found that the DEEDZ-SPR conversion enables the calculation of SPR simply by means of the weighted subtraction of an electron-density image and a low- or high-kV CT image. The simulated SPRs were in excellent agreement with the reference values over the SPR range from 0.258 (lung) to 3.638 (bone mineral-hydroxyapatite). The relative deviations from the reference SPR were within ±0.6% for all ICRU-46 human tissues, except for the thyroid that presented a -1.1% deviation. The overall root-mean-square error was 0.21%. Application to experimental DECT data confirmed this agreement within the experimental accuracy, which demonstrates the practical feasibility of the method. The DEEDZ-SPR conversion method could facilitate the construction of SPR images as accurately as a recent DECT-based calibration procedure of SPR parameterization based directly on the CT numbers in a DECT data set. © 2017 American Association of Physicists in Medicine.

The ATP/DNA Ratio Is a Better Indicator of Islet Cell Viability Than the ADP/ATP Ratio

Science.gov (United States)

Suszynski, T.M.; Wildey, G.M.; Falde, E.J.; Cline, G.W.; Maynard, K. Stewart; Ko, N.; Sotiris, J.; Naji, A.; Hering, B.J.; Papas, K.K.

2009-01-01

Real-time, accurate assessment of islet viability is critical for avoiding transplantation of nontherapeutic preparations. Measurements of the intracellular ADP/ATP ratio have been recently proposed as useful prospective estimates of islet cell viability and potency. However, dead cells may be rapidly depleted of both ATP and ADP, which would render the ratio incapable of accounting for dead cells. Since the DNA of dead cells is expected to remain stable over prolonged periods of time (days), we hypothesized that use of the ATP/DNA ratio would take into account dead cells and may be a better indicator of islet cell viability than the ADP/ATP ratio. We tested this hypothesis using mixtures of healthy and lethally heat-treated (HT) rat insulinoma cells and human islets. Measurements of ATP/DNA and ADP/ATP from the known mixtures of healthy and HT cells and islets were used to evaluate how well these parameters correlated with viability. The results indicated that ATP and ADP were rapidly (within 1 hour) depleted in HT cells. The fraction of HT cells in a mixture correlated linearly with the ATP/DNA ratio, whereas the ADP/ADP ratio was highly scattered, remaining effectively unchanged. Despite similar limitations in both ADP/ADP and ATP/DNA ratios, in that ATP levels may fluctuate significantly and reversibly with metabolic stress, the results indicated that ATP/DNA was a better measure of islet viability than the ADP/ATP ratio. PMID:18374063

Isotopic ratios of 129I/127I in mammalian thyroid glands in Japan

International Nuclear Information System (INIS)

Seki, R.; Hatano, T.

1994-01-01

The isotopic ratios of 129 I/ 127 I in cattle thyroid glands collected from various areas of Japan were measured by neutron activation analysis with combustion pre-treatment. Pig and human thyroid glands were also analyzed by the same method. The iodine isotopic ratio in cattle thyroid glands in Japan is comparable with that observed in Europe. The isotopic ratio in human thyroid glands in Japan is remarkably lower than that in Europe, which has been reported to be comparable to that of cattle. The isotopic ratio in pig thyroid glands is also lower than that in cattle. (author) 7 refs.; 3 figs.; 5 tabs

OH radicals from the indirect actions of X-rays induce cell lethality and mediate the majority of the oxygen enhancement effect.

Science.gov (United States)

Hirayama, Ryoichi; Ito, Atsushi; Noguchi, Miho; Matsumoto, Yoshitaka; Uzawa, Akiko; Kobashi, Gen; Okayasu, Ryuichi; Furusawa, Yoshiya

2013-11-01

We examined OH radical-mediated indirect actions from X irradiation on cell killing in wild-type Chinese hamster ovary cell lines (CHO and AA8) under oxic and hypoxic conditions, and compared the contribution of direct and indirect actions under both conditions. The contribution of indirect action on cell killing can be estimated from the maximum degree of protection by dimethylsulfoxide, which suppresses indirect action by quenching OH radicals without affecting the direct action of X rays on cell killing. The contributions of indirect action on cell killing of CHO cells were 76% and 50% under oxic and hypoxic conditions, respectively, and those for AA8 cells were 85% and 47%, respectively. Therefore, the indirect action on cell killing was enhanced by oxygen during X irradiation in both cell lines tested. Oxygen enhancement ratios (OERs) at the 10% survival level (D10 or LD90) for CHO and AA8 cells were 2.68 ± 0.15 and 2.76 ± 0.08, respectively. OERs were evaluated separately for indirect and direct actions, which gave the values of 3.75 and 2.01 for CHO, and 4.11 and 1.32 for AA8 cells, respectively. Thus the generally accepted OER value of ∼3 is best understood as the average of the OER values for both indirect and direct actions. These results imply that both indirect and direct actions on cell killing require oxygen for the majority of lethal DNA damage, however, oxygen plays a larger role in indirect than for direct effects. Conversely, the lethal damage induced by the direct action of X rays are less affected by oxygen concentration.

ESRD QIP - Standardized Readmission Ratio - Payment Year 2018

Data.gov (United States)

U.S. Department of Health & Human Services — This dataset includes facility details, performance ratio, measure score, and the state and national average measure scores for the SRR measure included in the PY...

Characteristics of the gait adaptation process due to split-belt treadmill walking under a wide range of right-left speed ratios in humans.

Science.gov (United States)

Yokoyama, Hikaru; Sato, Koji; Ogawa, Tetsuya; Yamamoto, Shin-Ichiro; Nakazawa, Kimitaka; Kawashima, Noritaka

2018-01-01

The adaptability of human bipedal locomotion has been studied using split-belt treadmill walking. Most of previous studies utilized experimental protocol under remarkably different split ratios (e.g. 1:2, 1:3, or 1:4). While, there is limited research with regard to adaptive process under the small speed ratios. It is important to know the nature of adaptive process under ratio smaller than 1:2, because systematic evaluation of the gait adaptation under small to moderate split ratios would enable us to examine relative contribution of two forms of adaptation (reactive feedback and predictive feedforward control) on gait adaptation. We therefore examined a gait behavior due to on split-belt treadmill adaptation under five belt speed difference conditions (from 1:1.2 to 1:2). Gait parameters related to reactive control (stance time) showed quick adjustments immediately after imposing the split-belt walking in all five speed ratios. Meanwhile, parameters related to predictive control (step length and anterior force) showed a clear pattern of adaptation and subsequent aftereffects except for the 1:1.2 adaptation. Additionally, the 1:1.2 ratio was distinguished from other ratios by cluster analysis based on the relationship between the size of adaptation and the aftereffect. Our findings indicate that the reactive feedback control was involved in all the speed ratios tested and that the extent of reaction was proportionally dependent on the speed ratio of the split-belt. On the contrary, predictive feedforward control was necessary when the ratio of the split-belt was greater. These results enable us to consider how a given split-belt training condition would affect the relative contribution of the two strategies on gait adaptation, which must be considered when developing rehabilitation interventions for stroke patients.

Challenges and Instructors’ Intention to Adopt and Use Open Educational Resources in Higher Education in Tanzania

Directory of Open Access Journals (Sweden)

Joel Samson Mtebe

2014-02-01

Full Text Available Higher education in Tanzania like in many other Sub-Saharan countries suffers from unavailability of quality teaching and learning resources due to lack of tradition, competence, and experience to develop such resources. Nevertheless, there are thousands of open educational resources (OER freely available in the public domain that can potentially improve the quality of existing resources or help to develop new courses. The uptake and reuse of these resources in higher learning institutions (HLIs in Tanzania has been very low. The study applied the unified theory of acceptance and use of technology (UTAUT model to elicit instructors’ intention to adopt and use OER in teaching. The paper also investigated challenges that hinder instructors to adopt and use OER. A sample of 104 instructors selected randomly from five HLIs was collected and tested against the research model using regression analysis. The study found effort expectancy had significant positive effect on instructors’ intention to use OER while performance expectancy, facilitating conditions, and social influence did not have significant effect. Challenges that were found to hinder instructors to adopt and use OER are discussed. The findings of this study will help those who are involved in OER implementation to find strategies that will maximize OER adoption and usage in higher education in Tanzania.

Equity Considerations for Open Educational Resources in the Glocalization of Education

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Willems, Julie; Bossu, Carina

2012-01-01

Open educational resources (OER) have become new buzzwords in the glocalization of education. While OER are often espoused as enabling educational equity, the reality is not always the case. Looking only at the positives of new educational methods can mask perpetuating challenges, which makes the open aspect of OER a misnomer. Taking an…

Campus and Online U.S. College Students' Attitudes toward an Open Educational Resource Course Fee: A Pilot Study

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Lindshield, Brian L.; Adhikari, Koushik

2013-01-01

Convincing faculty to accept, create, adapt, and adopt open educational resources (OERs) instead of textbooks for their courses has proven challenging because incentives are lacking. One approach to provide incentive to faculty members is an OER course fee, which could be employed in courses that use OERs approved by the institution for courses…

Making Higher Education More Affordable, One Course Reading at a Time: Academic Libraries as Key Advocates for Open Access Textbooks and Educational Resources

Science.gov (United States)

Okamoto, Karen

2013-01-01

Open access textbooks (OATs) and educational resources (OERs) are being lauded as a viable alternative to costly print textbooks. Some academic libraries are joining the OER movement by creating guides to open repositories. Others are promoting OATs and OERs, reviewing them, and even helping to create them. This article analyzes how academic…

Understanding Learners' Motivation and Learning Strategies in MOOCs

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Alario-Hoyos, Carlos; Estévez-Ayres, Iria; Pérez-Sanagustín, Mar; Delgado Kloos, Carlos; Fernández-Panadero, Carmen

2017-01-01

MOOCs (Massive Open Online Courses) have changed the way in which OER (Open Educational Resources) are bundled by teachers and consumed by learners. MOOCs represent an evolution towards the production and offering of structured quality OER. Many institutions that were initially reluctant to providing OER have, however, joined the MOOC wave.…

Variations in sensitivity of synchronized Chinese hamster cells to oxic and anoxic X-ray exposures

International Nuclear Information System (INIS)

Siracka, E.; Littbrand, B.; Clifton, K.H.; Revesz, L.

1975-01-01

V-79 Chinese hamster cells in monolayer cultures on glass surfaces were synchronized by treatment with hydroxyurea and then exposed at different times to X-rays in air or in oxygen-free argon. Survival determinations indicated that the oxygen enhancement ratio (OER) as expressed by the ratio of the respective D 0 values varied over a narrow range in the different phases of the cell cycle. These changes resulted from cyclic alterations in both aerobic and anaerobic D 0 values, possibly in n values. (author)

Characteristic 8 keV X rays possess radiobiological properties of higher-LET radiation.

Science.gov (United States)

Shridhar, Ravi; Estabrook, William; Yudelev, Mark; Rakowski, Joseph; Burmeister, Jay; Wilson, George D; Joiner, Michael C

2010-03-01

Electronic brachytherapy systems are being developed that can deliver X rays of varying energy depending on the material of a secondary target. A copper target produces characteristic 8 keV X rays. Our aim was to determine whether 8 keV X rays might deliver greater biological effectiveness than megavoltage photons. Cells of the U251 human glioma cell line were used to compare the biological effects of 8 keV X rays and (60)Co gamma rays in terms of relative biological effectiveness (RBE), oxygen enhancement ratio (OER), and DNA damage. The RBE at 50% and 10% survival was 2.6 and 1.9, respectively. At 50% survival, the OER for cells treated with 8 keV X rays was 1.6 compared with 3.0 for (60)Co gamma rays. The numbers of H2AX foci per Gy after treatment with 8 keV X rays and (60)Co gamma rays were similar; however, the size of the foci generated at 8 keV was significantly larger, possibly indicating more complex DNA damage. The mean area of H2AX foci generated by 8 keV X rays was 0.785 microm(2) (95% CI: 0.756-0.814) compared with 0.491 microm(2) (95% CI: 0.462-0.520) for (60)Co gamma rays (P X rays produce two to three times the biological effectiveness of megavoltage photons, with a radiobiological profile similar to higher-LET radiations.

Determination of 240Pu/239Pu isotopic ratios in human tissues collected from areas around the Semipalatinsk Nuclear Test Site by sector-field high resolution ICP-MS.

Science.gov (United States)

Yamamoto, M; Oikawa, S; Sakaguchi, A; Tomita, J; Hoshi, M; Apsalikov, K N

2008-09-01

Information on the 240Pu/239Pu isotope ratios in human tissues for people living around the Semipalatinsk Nuclear Test Site (SNTS) was deduced from 9 sets of soft tissues and bones, and 23 other bone samples obtained by autopsy. Plutonium was radiochemically separated and purified, and plutonium isotopes (239Pu and 240Pu) were determined by sector-field high resolution inductively coupled plasma-mass spectrometry. For most of the tissue samples from the former nine subjects, low 240Pu/239Pu isotope ratios were determined: bone, 0.125 +/- 0.018 (0.113-0.145, n = 4); lungs, 0.063 +/- 0.010 (0.051-0.078, n = 5); and liver, 0.148 +/- 0.026 (0.104-0.189, n = 9). Only 239Pu was detected in the kidney samples; the amount of 240Pu was too small to be measured, probably due to the small size of samples analyzed. The mean 240Pu/239Pu isotope ratio for bone samples from the latter 23 subjects was 0.152 +/- 0.034, ranging from 0.088 to 0.207. A significant difference (a two-tailed Student's t test; 95% significant level, alpha = 0.05) between mean 240Pu/239Pu isotope ratios for the tissue samples and for the global fallout value (0.178 +/- 0.014) indicated that weapons-grade plutonium from the atomic bombs has been incorporated into the human tissues, especially lungs, in the residents living around the SNTS. The present 239,240Pu concentrations in bone, lung, and liver samples were, however, not much different from ranges found for human tissues from other countries that were due solely to global fallout during the 1970's-1980's.

Questions of Quality in Repositories of Open Educational Resources: A Literature Review

Science.gov (United States)

Atenas, Javiera; Havemann, Leo

2014-01-01

Open educational resources (OER) are teaching and learning materials which are freely available and openly licensed. Repositories of OER (ROER) are platforms that host and facilitate access to these resources. ROER should not just be designed to store this content--in keeping with the aims of the OER movement, they should support educators in…

The ultimate intrinsic signal-to-noise ratio of loop- and dipole-like current patterns in a realistic human head model.

Science.gov (United States)

Pfrommer, Andreas; Henning, Anke

2018-03-13

The ultimate intrinsic signal-to-noise ratio (UISNR) represents an upper bound for the achievable SNR of any receive coil. To reach this threshold a complete basis set of equivalent surface currents is required. This study systematically investigated to what extent either loop- or dipole-like current patterns are able to reach the UISNR threshold in a realistic human head model between 1.5 T and 11.7 T. Based on this analysis, we derived guidelines for coil designers to choose the best array element at a given field strength. Moreover, we present ideal current patterns yielding the UISNR in a realistic body model. We distributed generic current patterns on a cylindrical and helmet-shaped surface around a realistic human head model. We excited electromagnetic fields in the human head by using eigenfunctions of the spherical and cylindrical Helmholtz operator. The electromagnetic field problem was solved by a fast volume integral equation solver. At 7 T and above, adding curl-free current patterns to divergence-free current patterns substantially increased the SNR in the human head (locally >20%). This was true for the helmet-shaped and the cylindrical surface. On the cylindrical surface, dipole-like current patterns had high SNR performance in central regions at ultra-high field strength. The UISNR increased superlinearly with B0 in most parts of the cerebrum but only sublinearly in the periphery of the human head. The combination of loop and dipole elements could enhance the SNR performance in the human head at ultra-high field strength. © 2018 International Society for Magnetic Resonance in Medicine.

Golden ratio beauty as scientific function

Directory of Open Access Journals (Sweden)

Scott A. Olsen

2018-01-01

Full Text Available Normally when one is considering the golden ratio in the history of ideas, one is often looking at it as an aesthetic principle – usually associated with Greek art, sculpture and mathematics. However, in recent years the prevalence of the golden ratio within a broad range of scientific disciplines has brought its role in the perfection of science to the forefront. I would like to collapse these two areas by proposing a somewhat novel way of looking at the aesthetics of the golden ratio: its pervasive expression in scientific form and function is the basis of the aesthetics in the world. Therefore, science contains the same mathematical beauty as found in artistic expression. The golden ratio guides the Chaos Border of Kolmogorov, Arnold, and Moser (KAM theorem and it can be found hidden in all elementary particles, and even in the proportions of dark matter and energy relative to visible matter and energy. It is evident in the structure and growth functions of plants and animals and it can be found in the physiological functions of humans. It now appears that without the golden ratio, we would not have the form or function of the proton, cell, athlete, horse, species, planet, solar system or galaxy.

Who Are the Open Learners? A Comparative Study Profiling Non-Formal Users of Open Educational Resources

Science.gov (United States)

Farrow, Robert; de los Arcos, Beatriz; Pitt, Rebecca; Weller, Martin

2015-01-01

Open educational resources (OER) have been identified as having the potential to extend opportunities for learning to non-formal learners. However, little research has been conducted into the impact of OER on non-formal learners. This paper presents the results of a systematic survey of more than 3,000 users of open educational resources (OER).…

Elucidating oxygen electrocatalysis with synchrotron X-rays: PEM fuel cells and electrolyzers

DEFF Research Database (Denmark)

Pedersen, Anders Filsøe

In this thesis electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) have been investigated using synchrotron based X-ray diffraction and X-ray absorption spectroscopy methods. The catalysts are based on Pt alloys and RuO2 for ORR and OER, respectively...... stability measurements showed that the in-plane compression relaxes during the first 2000-3000 cycles, explaining the loss of activity primarily in this range of cycling. For OER mass-selected nanoparticles of metallic Ru and thermally oxidized RuO2 were fabricated. Both materials are highly active for OER......, although the metallic Ru nanoparticles exceptionally so. However this comes as a trade-off in stability, as the metallic particles dissolves rapidly at OER conditions. In an in-situ XAS experiment the oxidation state of the nanoparticles were tracked as a function of potential. It was found...

13C/12C ratios in human urine concrementes

International Nuclear Information System (INIS)

Hoefs, J.; Armbruster, T.

1978-01-01

Oxalate, uric acid, and phosphate stones have been analyzed for their carbon isotope composition. The oxalate stones show delta 13 C values between -17.0 and -19.5 pro mille, the uric acid stones between -14.9 and -19.4 pro mille, and the phosphate stones between -13.0 and -23.9 pro mille. It is proposed that endogenic rather than exogenic sources are responsible for the 13 C/ 12 C ratios of the stones. The isotopic composition of the phosphate stones seems to be influenced primarily by bacterial activity. (orig.) [de

The Open Translation MOOC: Creating Online Communities to Transcend Linguistic Barriers

Science.gov (United States)

Beaven, Tita; Comas-Quinn, Anna; Hauck, Mirjam; de los Arcos, Beatriz; Lewis, Timothy

2013-01-01

One of the main barriers to the reuse of Open Educational Resources (OER) is language (OLnet, 2009). OER may be available but in a language that users cannot access, so a preliminary step to reuse is their translation or localization. One of the obvious solutions to the vast effort required to translate OER is to crowd-source the translation, as…

Morphometric analysis of the diameter and g-ratio of the myelinated nerve fibers of the human sciatic nerve during the aging process.

Science.gov (United States)

Ugrenović, Sladjana; Jovanović, Ivan; Vasović, Ljiljana; Kundalić, Braca; Čukuranović, Rade; Stefanović, Vladisav

2016-06-01

Myelinated nerve fibers suffer from different degrees of atrophy with age. The success of subsequent regeneration varies. The aim of this research was to analyze myelinated fibers of the human sciatic nerve during the aging process. Morphometric analysis was performed on 17 cases with an age range from 9 to 93 years. The outer and inner diameter of 100 randomly selected nerve fibers was measured in each of the cases evaluated, and the g-ratio (axonal diameter/outer diameter of the whole nerve fiber) of each was calculated. Scatter plots of the diameters and g-ratios of the analyzed fibers were then analyzed. Nerve fibers of each case were classified into three groups according to the g-ratio values: group I (g-ratio lower than 0.6), group II (g-ratio from 0.6 to 0.7) and group III (g-ratio higher than 0.7). Afterwards, nerve fibers of group II were further classified into small and large subgroups. The percentages of each group of nerve fibers were computed for each case and these values were used for correlational and bivariate linear regression analysis. The percentage of myelinated nerve fibers with large diameter and optimal g-ratio of the sciatic nerve declines significantly with age. This is accompanied by a simultaneous significant increase in the percentage of small myelinated fibers with g-ratio values close to 1 that occupy the upper left quadrant of the scatter plot. It can be concluded that aging of the sciatic nerve is associated with significant atrophy of large myelinated fibers. Additionally, a significant increase in regenerated nerve fibers with thinner myelin sheath is observed with age, which, together with the large myelinated fiber atrophy, might be the cause of the age-related decline in conduction velocity. A better understanding of the changes in aging peripheral nerves might improve interpretation of their pathological changes, as well as comprehension of their regeneration in individuals of different age.

The impact of sex ratio and economic status on local birth rates

OpenAIRE

Chipman, A.; Morrison, E.

2013-01-01

Human mating and reproductive behaviour can vary depending on various mechanisms, including the local sex ratio. Previous research shows that as sex ratios become female-biased, women from economically deprived areas are less likely to delay reproductive opportunities to wait for a high-investing mate but instead begin their reproductive careers sooner. Here, we show that the local sex ratio also has an impact on female fertility schedules. At young ages, a female-biased ratio is associated w...

OERScout Technology Framework: A Novel Approach to Open Educational Resources Search

Directory of Open Access Journals (Sweden)

Ishan Sudeera Abeywardena

2013-09-01

Full Text Available The open educational resources (OER movement has gained momentum in the past few years. With this new drive towards making knowledge open and accessible, a large number of OER repositories have been established and made available online throughout the world. However, the inability of existing search engines such as Google, Yahoo!, and Bing to effectively search for useful OER which are of acceptable academic standard for teaching purposes is a major factor contributing to the slow uptake of the entire movement. As a major step towards solving this issue, this paper proposes OERScout, a technology framework based on text mining solutions. The objectives of our work are to (i develop a technology framework which will parametrically measure the usefulness of an OER for a particular academic purpose based on the openness, accessibility, and relevance attributes; and (ii provide academics with a mechanism to locate OER which are of an acceptable academic standard. From our user tests, we have identified that OERScout is a sound solution for effectively zeroing in on OER which can be readily used for teaching and learning purposes.

A Bibliometric Mapping of Open Educational Resources

Directory of Open Access Journals (Sweden)

Airton Zancanaro

2015-02-01

Full Text Available Open educational resources (OER is a topic that has aroused increasing interest by researchers as a powerful contribution to improve the educational system quality and openness, both in face to face and distance education. The goal of this research is to map publications related to OER, dating from 2002 to 2013, and available through the Web of Science and Scopus scientific databases as well as in the OER Knowledge Cloud open repository. Data were used to explore relevant aspects related to the scientific production in OER, such as: (i number of publications per year; (ii most cited publications; (iii authors with higher number of publications; (iv institutions and countries with more publications and (v most referenced bibliography by the authors. The analysis has included 544 papers, written by 843 authors, from 338 institutions, from 61 different countries. Moreover, the analysis has included the publications referenced and the author’s keywords, considering 6,355 different publications and 929 different keywords. Besides presenting a bibliographic mapping of the research on OER, this paper also intends to contribute to consolidate the idea that OER is a promising field for researchers, in line with the spreading of the Open movement.

The Role of Ru Redox in pH-Dependent Oxygen Evolution on Rutile Ruthenium Dioxide Surfaces

Energy Technology Data Exchange (ETDEWEB)

Stoerzinger, Kelsey A.; Rao, Reshma R.; Wang, Xiao Renshaw; Hong, Wesley T.; Rouleau, Christopher M.; Shao-Horn, Yang

2017-05-01

Rutile RuO₂ is known to exhibit high catalytic activity for the oxygen evolution reaction (OER) and large pseudocapacitance associated with redox of surface Ru, however the mechanistic link between these properties and the role of pH is yet to be understood. Here we report that the OER activities of the (101), (001) and (111) RuO₂ surfaces were found to increase while the potential of a pseudocapacitive feature just prior to OER shifted to lower potentials (“super-Nernstian” shift) with increasing pH on the reversible hydrogen electrode (RHE) scale. This behavior is in contrast to the (100) and (110) surfaces that have pH-independent Ru redox and OER activity. The link in catalytic and pseudocapacitive behavior illustrates the importance of this redox feature in generating active sites, building new mechanistic understanding of the OER.

The financial consequences of too many men: sex ratio effects on saving, borrowing, and spending.

Science.gov (United States)

Griskevicius, Vladas; Tybur, Joshua M; Ackerman, Joshua M; Delton, Andrew W; Robertson, Theresa E; White, Andrew E

2012-01-01

The ratio of males to females in a population is an important factor in determining behavior in animals. We propose that sex ratio also has pervasive effects in humans, such as by influencing economic decisions. Using both historical data and experiments, we examined how sex ratio influences saving, borrowing, and spending in the United States. Findings show that male-biased sex ratios (an abundance of men) lead men to discount the future and desire immediate rewards. Male-biased sex ratios decreased men's desire to save for the future and increased their willingness to incur debt for immediate expenditures. Sex ratio appears to influence behavior by increasing the intensity of same-sex competition for mates. Accordingly, a scarcity of women led people to expect men to spend more money during courtship, such as by paying more for engagement rings. These findings demonstrate experimentally that sex ratio influences human decision making in ways consistent with evolutionary biological theory. Implications for sex ratio effects across cultures are discussed.

High energy physics advisory panel's composite subpanel for the assessment of the status of accelerator physics and technology

International Nuclear Information System (INIS)

1996-05-01

In November 1994, Dr. Martha Krebs, Director of the US Department of Energy (DOE) Office of Energy Research (OER), initiated a broad assessment of the current status and promise of the field of accelerator physics and technology with respect to five OER programs -- High Energy Physics, Nuclear Physics, Basic Energy Sciences, Fusion Energy, and Health and Environmental Research. Dr. Krebs asked the High Energy Physics Advisory Panel (HEPAP) to establish a composite subpanel with representation from the five OER advisory committees and with a balance of membership drawn broadly from both the accelerator community and from those scientific disciplines associated with the OER programs. The Subpanel was also charged to provide recommendations and guidance on appropriate future research and development needs, management issues, and funding requirements. The Subpanel finds that accelerator science and technology is a vital and intellectually exciting field. It has provided essential capabilities for the DOE/OER research programs with an enormous impact on the nation's scientific research, and it has significantly enhanced the nation's biomedical and industrial capabilities. Further progress in this field promises to open new possibilities for the scientific goals of the OER programs and to further benefit the nation. Sustained support of forefront accelerator research and development by the DOE's OER programs and the DOE's predecessor agencies has been responsible for much of this impact on research. This report documents these contributions to the DOE energy research mission and to the nation

Skewed sex ratios and criminal victimization in India.

Science.gov (United States)

South, Scott J; Trent, Katherine; Bose, Sunita

2014-06-01

Although substantial research has explored the causes of India's excessively masculine population sex ratio, few studies have examined the consequences of this surplus of males. We merge individual-level data from the 2004-2005 India Human Development Survey with data from the 2001 India population census to examine the association between the district-level male-to-female sex ratio at ages 15 to 39 and self-reports of victimization by theft, breaking and entering, and assault. Multilevel logistic regression analyses reveal positive and statistically significant albeit substantively modest effects of the district-level sex ratio on all three victimization risks. We also find that higher male-to-female sex ratios are associated with the perception that young unmarried women in the local community are frequently harassed. Household-level indicators of family structure, socioeconomic status, and caste, as well as areal indicators of women's empowerment and collective efficacy, also emerge as significant predictors of self-reported criminal victimization and the perceived harassment of young women. The implications of these findings for India's growing sex ratio imbalance are discussed.

Skewed Sex Ratios and Criminal Victimization in India

Science.gov (United States)

South, Scott J.; Trent, Katherine; Bose, Sunita

2014-01-01

Although substantial research has explored the causes of India’s excessively masculine population sex ratio, few studies have examined the consequences of this surplus of males. We merge individual-level data from the 2004–2005 India Human Development Survey with data from the 2001 India population census to examine the association between the district-level male-to-female sex ratio at ages 15 to 39 and self-reports of victimization by theft, breaking and entering, and assault. Multilevel logistic regression analyses reveal positive and statistically significant albeit substantively modest effects of the district-level sex ratio on all three victimization risks. We also find that higher male-to-female sex ratios are associated with the perception that young unmarried women in the local community are frequently harassed. Household-level indicators of family structure, socioeconomic status, and caste, as well as areal indicators of women’s empowerment and collective efficacy, also emerge as significant predictors of self-reported criminal victimization and the perceived harassment of young women. The implications of these findings for India’s growing sex ratio imbalance are discussed. PMID:24682921

Impact of cigarette smoking on histone (H2B) to protamine ratio in human spermatozoa and its relation to sperm parameters.

Science.gov (United States)

Hamad, M F; Shelko, N; Kartarius, S; Montenarh, M; Hammadeh, M E

2014-09-01

Smoking is strongly associated with abnormalities in histone-to-protamine transition and with alteration of protamine expression in human spermatozoa. A proper protamine to histone ratio is, however, essential for sperm chromatin maturity and DNA integrity. Alterations in these sperm nuclear proteins were observed in infertile men. The present prospective study is aimed at evaluating the possible relationship among smoking, semen quality and the histone-to-protamine transition ratio in mature spermatozoa. Histone H2B and protamine 1 (P1) and 2 (P2) were quantified using acid-urea polyacrylamide gel electrophoresis in the spermatozoa of 35 smokers and 19 non-smokers. Levels of lipid peroxidation marker malondialdehyde (MDA) were measured in seminal plasma by thiobarbituric acid assay. Cotinine concentrations were determined in seminal plasma using an enzyme-linked immunosorbent assay. Histone H2B levels in smokers (292.27 ± 58.24 ng/10(6)) were significantly higher (p = 0.001) than that of non-smokers (109.1 ± 43.70 ng/10(6)), besides, a significant difference (p > 0.0001) was found for the P1 and P2 ratio between smokers (1.71 ± 0.071) and non-smokers (1.05 ± 0.033). The H2B/(H2B+P1 + P2) ratio (0.29 ± 0.71) of smokers were significantly higher (p = sperm count, motility (p = 0.018), vitality (p = 0.009) and membrane integrity (p = 0.0001) than non-smokers. These results reveal that patients who smoke possess a higher proportion of spermatozoa with an alteration of the histone to protamine ratio than patients who do not smoke, and suggest that cigarette smoking may inversely affect male fertility. © 2014 American Society of Andrology and European Academy of Andrology.

Selective breeding for a behavioral trait changes digit ratio.

Directory of Open Access Journals (Sweden)

Reginia H Y Yan

Full Text Available The ratio of the length of the second digit (index finger divided by the fourth digit (ring finger tends to be lower in men than in women. This 2D:4D digit ratio is often used as a proxy for prenatal androgen exposure in studies of human health and behavior. For example, 2D:4D ratio is lower (i.e. more "masculinized" in both men and women of greater physical fitness and/or sporting ability. Lab mice have also shown variation in 2D:4D as a function of uterine environment, and mouse digit ratios seem also to correlate with behavioral traits, including daily activity levels. Selective breeding for increased rates of voluntary exercise (wheel running in four lines of mice has caused correlated increases in aerobic exercise capacity, circulating corticosterone level, and predatory aggression. Here, we show that this selection regime has also increased 2D:4D. This apparent "feminization" in mice is opposite to the relationship seen between 2D:4D and physical fitness in human beings. The present results are difficult to reconcile with the notion that 2D:4D is an effective proxy for prenatal androgen exposure; instead, it may more accurately reflect effects of glucocorticoids, or other factors that regulate any of many genes.

Orientation-Dependent Oxygen Evolution on RuO ₂ without Lattice Exchange

Energy Technology Data Exchange (ETDEWEB)

Stoerzinger, Kelsey A.; Diaz-Morales, Oscar; Kolb, Manuel; Rao, Reshma R.; Frydendal, Rasmus; Qiao, Liang; Wang, Xiao Renshaw; Halck, Niels Bendtsen; Rossmeisl, Jan; Hansen, Heine A.; Vegge, Tejs; Stephens, Ifan E. L.; Koper, Marc T. M.; Shao-Horn, Yang

2017-03-15

RuO2 catalysts exhibit record activities towards the oxygen evolution reaction (OER), which is crucial to enable efficient and sustainable energy storage. Here we examine the RuO2 OER kinetics on rutile (110), (100), (101), and (111) orientations, finding (100) the most active. We assess the potential involvement of lattice oxygen in the OER mechanism with online 3 electrochemical mass spectrometry, which showed no evidence of oxygen exchange on these oriented facets in acidic or basic electrolytes. Similar results were obtained for polyoriented RuO2 films and particles, in contrast to previous work, suggesting lattice oxygen is not exchanged in catalyzing OER on crystalline RuO2 surfaces. This hypothesis is supported by the correlation of activity with the number of active Ru-sites calculated by DFT, where more active facets bind oxygen more weakly. This new understanding of the active sites provides a design strategy to enhance the OER activity of RuO2 nanoparticles by facet engineering.

A father effect explains sex-ratio bias.

Science.gov (United States)

Malo, Aurelio F; Martinez-Pastor, Felipe; Garcia-Gonzalez, Francisco; Garde, Julián; Ballou, Jonathan D; Lacy, Robert C

2017-08-30

Sex ratio allocation has important fitness consequences, and theory predicts that parents should adjust offspring sex ratio in cases where the fitness returns of producing male and female offspring vary. The ability of fathers to bias offspring sex ratios has traditionally been dismissed given the expectation of an equal proportion of X- and Y-chromosome-bearing sperm (CBS) in ejaculates due to segregation of sex chromosomes at meiosis. This expectation has been recently refuted. Here we used Peromyscus leucopus to demonstrate that sex ratio is explained by an exclusive effect of the father, and suggest a likely mechanism by which male-driven sex-ratio bias is attained. We identified a male sperm morphological marker that is associated with the mechanism leading to sex ratio bias; differences among males in the sperm nucleus area (a proxy for the sex chromosome that the sperm contains) explain 22% variation in litter sex ratio. We further show the role played by the sperm nucleus area as a mediator in the relationship between individual genetic variation and sex-ratio bias. Fathers with high levels of genetic variation had ejaculates with a higher proportion of sperm with small nuclei area. This, in turn, led to siring a higher proportion of sons (25% increase in sons per 0.1 decrease in the inbreeding coefficient). Our results reveal a plausible mechanism underlying unexplored male-driven sex-ratio biases. We also discuss why this pattern of paternal bias can be adaptive. This research puts to rest the idea that father contribution to sex ratio variation should be disregarded in vertebrates, and will stimulate research on evolutionary constraints to sex ratios-for example, whether fathers and mothers have divergent, coinciding, or neutral sex allocation interests. Finally, these results offer a potential explanation for those intriguing cases in which there are sex ratio biases, such as in humans. © 2017 The Author(s).

Novel bacterial ratio for predicting fecal age

Energy Technology Data Exchange (ETDEWEB)

Nieman, J.; Brion, G.M. [Univ. of Kentucky, Dept. of Civil Engineering, Lexington, Kentucky (United States)]. E-mail: gbrion@engr.uky.edu

2002-06-15

This study presents an extension of ongoing research into the utility of the ratio of bacterial colonies isolated on membrane filters during the total coliform test using m-Endo broth media for the prediction of fecal age. Analysis of the relative shifts in concentrations of indicator bacterial populations in Kentucky River water quality data collected from the inlet of a local water treatment plant showed a correlation between raw concentrations of atypical colonies (AC) and total coliform colonies (TC) formed on m-Endo membrane filter tests, and fecal age. Visual analysis of plant treatment records showed that low values of the AC/TC ratio were related to periods of high flow, when runoff added fresh fecal material to the river. A more detailed analysis of 2 years of Kentucky River water quality data showed the average AC/TC ratio during months with high river flow (rain) to be 3.4, rising to an average of 27.6 during months with low flow. The average AC/TC ratio during high flow months compared to that found in other studies for raw human sewage (3.9) and the ratio increased to values associated with animal impacted urban runoff (18.9) during low flow months. (author)

Novel bacterial ratio for predicting fecal age

International Nuclear Information System (INIS)

Nieman, J.; Brion, G.M.

2002-01-01

This study presents an extension of ongoing research into the utility of the ratio of bacterial colonies isolated on membrane filters during the total coliform test using m-Endo broth media for the prediction of fecal age. Analysis of the relative shifts in concentrations of indicator bacterial populations in Kentucky River water quality data collected from the inlet of a local water treatment plant showed a correlation between raw concentrations of atypical colonies (AC) and total coliform colonies (TC) formed on m-Endo membrane filter tests, and fecal age. Visual analysis of plant treatment records showed that low values of the AC/TC ratio were related to periods of high flow, when runoff added fresh fecal material to the river. A more detailed analysis of 2 years of Kentucky River water quality data showed the average AC/TC ratio during months with high river flow (rain) to be 3.4, rising to an average of 27.6 during months with low flow. The average AC/TC ratio during high flow months compared to that found in other studies for raw human sewage (3.9) and the ratio increased to values associated with animal impacted urban runoff (18.9) during low flow months. (author)

Dynamic surface self-reconstruction is the key of highly active perovskite nano-electrocatalysts for water splitting

Science.gov (United States)

Fabbri, Emiliana; Nachtegaal, Maarten; Binninger, Tobias; Cheng, Xi; Kim, Bae-Jung; Durst, Julien; Bozza, Francesco; Graule, Thomas; Schäublin, Robin; Wiles, Luke; Pertoso, Morgan; Danilovic, Nemanja; Ayers, Katherine E.; Schmidt, Thomas J.

2017-09-01

The growing need to store increasing amounts of renewable energy has recently triggered substantial R&D efforts towards efficient and stable water electrolysis technologies. The oxygen evolution reaction (OER) occurring at the electrolyser anode is central to the development of a clean, reliable and emission-free hydrogen economy. The development of robust and highly active anode materials for OER is therefore a great challenge and has been the main focus of research. Among potential candidates, perovskites have emerged as promising OER electrocatalysts. In this study, by combining a scalable cutting-edge synthesis method with time-resolved X-ray absorption spectroscopy measurements, we were able to capture the dynamic local electronic and geometric structure during realistic operando conditions for highly active OER perovskite nanocatalysts. Ba0.5Sr0.5Co0.8Fe0.2O3-δ as nano-powder displays unique features that allow a dynamic self-reconstruction of the material’s surface during OER, that is, the growth of a self-assembled metal oxy(hydroxide) active layer. Therefore, besides showing outstanding performance at both the laboratory and industrial scale, we provide a fundamental understanding of the operando OER mechanism for highly active perovskite catalysts. This understanding significantly differs from design principles based on ex situ characterization techniques.

Socioeconomic status influences sex ratios in a Chinese rural population.

Science.gov (United States)

Luo, Liqun; Ding, Rui; Gao, Xiali; Sun, Jingjing; Zhao, Wei

2017-01-01

According to the logic of the Trivers-Willard hypothesis, in a human population, if socioeconomic status is transmitted across generations to some extent, and if sons of high-status parents tend to have higher reproductive success than daughters, while daughters of low-status parents tend to have higher reproductive success than sons, then we should expect that offspring sex ratio is positively associated with socioeconomic status. This study examines whether the assumptions and prediction of this hypothesis apply to a rural population in northern China. Results show that (1) current family socioeconomic status is positively related to family head's father's socioeconomic status in around 1950, (2) low-status family heads have more grandchildren through their daughters than their sons, whereas high- or middle-status family heads have more grandchildren through sons, and (3) as family heads' status increases, they tend to produce a higher offspring sex ratio. Therefore, the assumptions and prediction of the hypothesis are met in the study population. These results are discussed in reference to past studies on sex ratio manipulation among humans.

Metodika tvorby a využití případových studií ve výuce a formou Open Educational Resources (OER

Directory of Open Access Journals (Sweden)

Jana Dlouhá

2016-04-01

Full Text Available Předložená metodika tvorby regionálních případových studií (PS udržitelného rozvoje pro vysokoškolské vzdělávání má za úkol ukázat, jakým způsobem lze ve výuce využít konkrétní případy z praxe a současně jak rozvíjet výzkumné nástroje relevantní pro místní environmentální problematiku a otázky udržitelného rozvoje území; důraz je přitom kladen na regionální kontext a specifika. Publikace výsledků formou otevřených vzdělávacích zdrojů (tzv. Open Educational Resources, OER umožní využít tyto materiály pro regionálně orientované školství i na nižších stupních vzdělávacího systému, pro prezentaci regionálních zvláštností, a může sloužit též pro podporu dialogu o rozvoji území mezi různými společenskými aktéry.

Investigating Perceived Barriers to the Use of Open Educational Resources in Higher Education in Tanzania

Directory of Open Access Journals (Sweden)

Joel S. Mtebe

2014-04-01

Full Text Available The past few years have seen increasingly rapid development and use of open educational resources (OER in higher education institutions (HEIs in developing countries. These resources are believed to be able to widen access, reduce the costs, and improve the quality of education. However, there exist several challenges that hinder the adoption and use of these resources. The majority of challenges mentioned in the literature do not have empirically grounded evidence and they assume Sub-Saharan countries face similar challenges. Nonetheless, despite commonalities that exist amongst these countries, there also exists considerable diversity, and they face different challenges. Accordingly, this study investigated the perceived barriers to the use of OER in 11 HEIs in Tanzania. The empirical data was generated through semi-structured interviews with a random sample of 92 instructors as well as a review of important documents. Findings revealed that lack of access to computers and the Internet, low Internet bandwidth, absence of policies, and lack of skills to create and/or use OER are the main barriers to the use of OER in HEIs in Tanzania. Contrary to findings elsewhere in Africa, the study revealed that lack of trust in others’ resources, lack of interest in creating and/or using OER, and lack of time to find suitable materials were not considered to be barriers. These findings provide a new understanding of the barriers to the use of OER in HEIs and should therefore assist those who are involved in OER implementation to find mitigating strategies that will maximize their usage.

The MRC1/CD68 ratio is positively associated with adipose tissue lipogenesis and with muscle mitochondrial gene expression in humans.

Directory of Open Access Journals (Sweden)

José María Moreno-Navarrete

Full Text Available BACKGROUND: Alternative macrophages (M2 express the cluster differentiation (CD 206 (MCR1 at high levels. Decreased M2 in adipose tissue is known to be associated with obesity and inflammation-related metabolic disturbances. Here we aimed to investigate MCR1 relative to CD68 (total macrophages gene expression in association with adipogenic and mitochondrial genes, which were measured in human visceral [VWAT, n = 147] and subcutaneous adipose tissue [SWAT, n = 76] and in rectus abdominis muscle (n = 23. The effects of surgery-induced weight loss were also longitudinally evaluated (n = 6. RESULTS: MCR1 and CD68 gene expression levels were similar in VWAT and SWAT. A higher proportion of CD206 relative to total CD68 was present in subjects with less body fat and lower fasting glucose concentrations. The ratio MCR1/CD68was positively associated with IRS1gene expression and with the expression of lipogenic genes such as ACACA, FASN and THRSP, even after adjusting for BMI. The ratio MCR1/CD68 in SWAT increased significantly after the surgery-induced weight loss (+44.7%; p = 0.005 in parallel to the expression of adipogenic genes. In addition, SWAT MCR1/CD68ratio was significantly associated with muscle mitochondrial gene expression (PPARGC1A, TFAM and MT-CO3. AT CD206 was confirmed by immunohistochemistry to be specific of macrophages, especially abundant in crown-like structures. CONCLUSION: A decreased ratio MCR1/CD68 is linked to adipose tissue and muscle mitochondrial dysfunction at least at the level of expression of adipogenic and mitochondrial genes.

Human immunodeficiency virus-associated lipodystrophy: an objective definition based on dual-energy x-ray absorptiometry-derived regional fat ratios in a South Asian population.

Science.gov (United States)

Asha, Hesarghatta Shyamasunder; Seshadri, Mandalam Subramaniam; Paul, Thomas Vizhalil; Abraham, Ooriapadickal Cherian; Rupali, Priscilla; Thomas, Nihal

2012-01-01

To develop an objective definition of human immunodeficiency virus (HIV)-associated lipodystrophy by using regional fat mass ratios and to assess the utility of anthropometric and skinfold measurements in the initial screening for lipodystrophy. Male patients between 25 and 50 years old with proven HIV infection (highly active antiretroviral therapy [HAART]-naïve subjects and those receiving successful HAART) were studied and compared with body mass index (BMI)-matched HIV-negative control subjects. Anthropometric variables, body composition, dual-energy x-ray absorptiometry findings, and metabolic variables were compared among the 3 study groups and between those patients with and those without lipodystrophy. Trunk fat/lower limb fat mass ratio >2.28 identified 54.3% of patients with HIV receiving HAART as having lipodystrophy and had the highest odds ratio for predicting metabolic syndrome. The "clinical diagnosis of lipodystrophy" and the "clinical scoring system" had too many false-positive and false-negative results. Triceps skinfold thickness (SFT)/BMI ratio ≤0.49 and abdominal SFT/triceps SFT ratio >1.385 have good sensitivity but poor specificity in identifying lipodystrophy. In comparison with HAART-naïve patients with HIV, those receiving HAART had significantly higher insulin resistance, and a significantly greater proportion had impaired glucose tolerance and dyslipidemia. Among patients receiving HAART, those with lipodystrophy had a greater degree of insulin resistance, higher triglyceride levels, and lower levels of high-density lipoprotein cholesterol. The trunk fat/lower limb fat mass ratio in BMI-matched normal subjects can be used to derive cutoff values to define lipodystrophy objectively in HIV-infected patients. Defining lipodystrophy in this way is better than other methods of identifying those patients with increased cardiovascular risk. Triceps SFT/BMI and abdominal SFT/triceps SFT ratios may be useful as screening tools in resource

N-ethylmaleimide sensitization of x-irradiated hypoxic Chinese hamster cells

International Nuclear Information System (INIS)

Kimler, B.F.; Sinclair, W.K.; Elkind, M.M.

1977-01-01

Chinese hamster cells were x irradiated either aerobically or hypoxically, after flushing with nitrogen plus carbon dioxide. In agreement with earlier data, for asynchronous cells, the oxygen enhancement ratio (OER) was approximately three. If the sulfhydryl-binding agent N-ethylmaleimide (NEM) was present during or immediately after irradiation, the principal effect was a pronounced decrease in the extrapolation number of the survival curve of NEM-treated cells compared to nontreated cells. This was observed with hypoxic as well as aerobic cells and the OER for NEM-treated cells was also about three. For NEM treatments which were essentially nontoxic, NEM acts synergistically with X rays, suggestive of an inhibition by NEM of a cell's ability to repair sublethal damage. For synchronous cells obtained by mitotic selection, a result consistent with the above was obtained; a dose three times as large was necessary to reduce survival to the same level for hypoxic cells as for aerobic cells, whether or not the cells were treated with NEM. Thus the OER was independent of NEM treatment throughout the cell cycle, with the possible exception of mitosis which could not be studied with the methods used. It is concluded that the action of NEM at low concentrations (0.75 μM) is largely independent of oxygen tension. Oxygen acts to produce more damage per unit dose in the cell while NEM sensitizes apparently by preventing the repair of sublethal damage

OERScout Technology Framework: A Novel Approach to Open Educational Resources Search

OpenAIRE

Ishan Sudeera Abeywardena; Chee Seng Chan; Choy Yoong Tham

2013-01-01

The open educational resources (OER) movement has gained momentum in the past few years. With this new drive towards making knowledge open and accessible, a large number of OER repositories have been established and made available online throughout the world. However, the inability of existing search engines such as Google, Yahoo!, and Bing to effectively search for useful OER which are of acceptable academic standard for teaching purposes is a major factor contributing to the slow uptake of ...

Questions of quality in repositories of open educational resources: a literature review

OpenAIRE

Atenas, J.; Havemann, Leo

2014-01-01

Open educational resources (OER) are teaching and learning materials which are freely available and openly licensed. Repositories of OER (ROER) are platforms that host and facilitate access to these resources. ROER should not just be designed to store this content – in keeping with the aims of the OER movement, they should support educators in embracing open educational practices (OEP) such as searching for and retrieving content that they will reuse, adapt or modify as needed, without econom...

Activity and stability trends of perovskite oxides for oxygen evolution catalysis at neutral pH

OpenAIRE

Ling, Chen; Jia, Hongfei; Han, Binghong; Risch, Marcel; Lee, Yueh Lin; Shao-Horn, Yang

2015-01-01

Perovskite oxides (ABO[subscript 3]) have been studied extensively to promote the kinetics of the oxygen evolution reaction (OER) in alkaline electrolytes. However, developing highly active catalysts for OER at near-neutral pH is desirable for many photoelectrochemical/electrochemical devices. In this paper, we systematically studied the activity and stability of well-known perovskite oxides for OER at pH 7. Previous activity descriptors established for perovskite oxides at pH 13, such as hav...

RATIO_TOOL - SOFTWARE FOR COMPUTING IMAGE RATIOS

Science.gov (United States)

Yates, G. L.

1994-01-01

Geological studies analyze spectral data in order to gain information on surface materials. RATIO_TOOL is an interactive program for viewing and analyzing large multispectral image data sets that have been created by an imaging spectrometer. While the standard approach to classification of multispectral data is to match the spectrum for each input pixel against a library of known mineral spectra, RATIO_TOOL uses ratios of spectral bands in order to spot significant areas of interest within a multispectral image. Each image band can be viewed iteratively, or a selected image band of the data set can be requested and displayed. When the image ratios are computed, the result is displayed as a gray scale image. At this point a histogram option helps in viewing the distribution of values. A thresholding option can then be used to segment the ratio image result into two to four classes. The segmented image is then color coded to indicate threshold classes and displayed alongside the gray scale image. RATIO_TOOL is written in C language for Sun series computers running SunOS 4.0 and later. It requires the XView toolkit and the OpenWindows window manager (version 2.0 or 3.0). The XView toolkit is distributed with Open Windows. A color monitor is also required. The standard distribution medium for RATIO_TOOL is a .25 inch streaming magnetic tape cartridge in UNIX tar format. An electronic copy of the documentation is included on the program media. RATIO_TOOL was developed in 1992 and is a copyrighted work with all copyright vested in NASA. Sun, SunOS, and OpenWindows are trademarks of Sun Microsystems, Inc. UNIX is a registered trademark of AT&T Bell Laboratories.

MOF derived Ni/Co/NC catalysts with enhanced properties for oxygen evolution reaction

Science.gov (United States)

Hu, Jiapeng; Chen, Juan; Lin, Hao; Liu, Ruilai; Yang, Xiaobing

2018-03-01

Designing efficient electrocatalysts for oxygen evolution reaction (OER) is very important for renewable energy storage and conversion devices. In this paper, we introduced a new strategy to synthesize Ni doped Co/NC catalysts (NC is the abbreviation of nitrogen-doped graphitic carbon), which were derived from ZIF-67. All catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and oxygen evolution reaction (OER). The results show that Ni was well doped in the Ni/Co/NC catalysts and the doping of Ni has great influence on the OER activity of Ni/Co/NC catalysts. Among these catalysts, 0.50Ni/Co/NC exhibits the highest OER activity. The onset potential of 0.50Ni/Co/NC is 1.47 V, which is superior than the onset potential of Co/NC (1.54 V), 0.25Ni/Co/NC (1.48 V), 1.00Ni/Co/NC (1.53 V). The excellent OER activity of 0.50Ni/Co/NC catalyst makes its potential to be used on renewable energy storage.

Enhanced activity of gold-supported cobalt oxide for the electrochemical evolution of oxygen.

Science.gov (United States)

Yeo, Boon Siang; Bell, Alexis T

2011-04-13

Scanning electron microscopy, linear sweep voltammetry, chronoamperometry, and in situ surface-enhanced Raman spectroscopy were used to investigate the electrochemical oxygen evolution reaction (OER) occurring on cobalt oxide films deposited on Au and other metal substrates. All experiments were carried out in 0.1 M KOH. A remarkable finding is that the turnover frequency for the OER exhibited by ∼0.4 ML of cobalt oxide deposited on Au is 40 times higher than that of bulk cobalt oxide. The activity of small amounts of cobalt oxide deposited on Pt, Pd, Cu, and Co decreased monotonically in the order Au > Pt > Pd > Cu > Co, paralleling the decreasing electronegativity of the substrate metal. Another notable finding is that the OER turnover frequency for ∼0.4 ML of cobalt oxide deposited on Au is nearly three times higher than that for bulk Ir. Raman spectroscopy revealed that the as-deposited cobalt oxide is present as Co(3)O(4) but undergoes progressive oxidation to CoO(OH) with increasing anodic potential. The higher OER activity of cobalt oxide deposited on Au is attributed to an increase in fraction of the Co sites present as Co(IV) cations, a state of cobalt believed to be essential for OER to occur. A hypothesis for how Co(IV) cations contribute to OER is proposed and discussed. © 2011 American Chemical Society

Open Educational Resources: American Ideals, Global Questions

Directory of Open Access Journals (Sweden)

Steven Weiland

2015-09-01

Full Text Available Educational relations between societies and cultures that begin with benevolent intentions can come to be seen as threats to national autonomy and local preferences. Indeed, side by side with the growth since the first years of this century of Open Educational Resources (OER there has been worry about their impact on global educational development. Evaluation and research have lagged behind the steady expansion of access to online resources, leaving estimates of the value of digital innovation to the enthusiasm of OER providers and technology minded educational reformers. The advent of the “Massive Open Online Course” (or MOOC has exacerbated the problem, with attention moving toward a form of OER reflecting the enthusiasm of leading institutions in industrialized nations. The American led movement on behalf of the MOOC requires new questions about the motives, impact, and future of OER. This essay accounts for the history of OER, culminating in the MOOC, including how the latter in particular is an expression of American pedagogical and institutional interests representing belief in the transformative educational powers of the latest communications technologies. Criticism of OER and MOOCs can reflect organizational, operational, and ideological considerations. But it should recognize what they offer when there are few other opportunities for formal learning, and as research demonstrates their uses and impact.

THE USE OF OPEN EDUCATIONAL RESOURCES IN ONLINE LEARNING: A Study of Students’ Perception

Directory of Open Access Journals (Sweden)

Meirani HARSASI

2015-07-01

Full Text Available Universitas Terbuka (UT is Indonesia’s higher education institution which implements distance education system. The term distance implies that learning is not performed face-to-face but there is geographically separation between students and teacher. Therefore, UT must provide many kinds of learning modes and learning support. To facilitate students in their learning process, UT provides an e-learning system named online tutorial. This tutorial is provided for all courses which are designed in 8 sessions of virtual class. Students can learn, discuss, and ask to the teacher via this mode of learning. As the development of methods in e-learning, the use of open educational resources (OER has increasing these days. Learning materials can be taken easily and freely from internet. UT also utilize OER in it’s learning process, especially in e-learning. The aim of this study was to collect data from students about their acceptance of integrating OER into e-learning. The use of OER is perceived by students as something interesting because it’s new for them and can help them to have a better understanding about a topic. The results also showed that video has found as the most interesting OER for students. Other results, limitation and suggestion from students about integrating OER into e-learning also will be discussed in this paper.

Gender Inequality and the Sex Ratio in Three Emerging Economies

OpenAIRE

Prabir C. Bhattacharya

2012-01-01

The aim of this paper is to study inequality and deprivations as reflected in the human sex ratio (commonly defined as the number of males per 100 females). The particular focus is on three emerging economies, viz., Russia, India and China. The paper compares and contrasts the experiences of these countries and discusses policy issues. It is noted that while the feminist perspective on the issues surrounding the sex ratio is important, it would be wrong to view these issues always or exclusiv...

Serial binary interval ratios improve rhythm reproduction

Directory of Open Access Journals (Sweden)

Xiang eWu

2013-08-01

Full Text Available Musical rhythm perception is a natural human ability that involves complex cognitive processes. Rhythm refers to the organization of events in time, and musical rhythms have an underlying hierarchical metrical structure. The metrical structure induces the feeling of a beat and the extent to which a rhythm induces the feeling of a beat is referred to as its metrical strength. Binary ratios are the most frequent interval ratio in musical rhythms. Rhythms with hierarchical binary ratios are better discriminated and reproduced than rhythms with hierarchical non-binary ratios. However, it remains unclear whether a superiority of serial binary over non-binary ratios in rhythm perception and reproduction exists. In addition, how different types of serial ratios influence the metrical strength of rhythms remains to be elucidated. The present study investigated serial binary vs. non-binary ratios in a reproduction task. Rhythms formed with exclusively binary (1:2:4:8, non-binary integer (1:3:5:6, and non-integer (1:2.3:5.3:6.4 ratios were examined within a constant meter. The results showed that the 1:2:4:8 rhythm type was more accurately reproduced than the 1:3:5:6 and 1:2.3:5.3:6.4 rhythm types, and the 1:2.3:5.3:6.4 rhythm type was more accurately reproduced than the 1:3:5:6 rhythm type. Further analyses showed that reproduction performance was better predicted by the distribution pattern of event occurrences within an inter-beat interval, than by the coincidence of events with beats, or the magnitude and complexity of interval ratios. Whereas rhythm theories and empirical data emphasize the role of the coincidence of events with beats in determining metrical strength and predicting rhythm performance, the present results suggest that rhythm processing may be better understood when the distribution pattern of event occurrences is taken into account. These results provide new insights into the mechanisms underlining musical rhythm perception.

Serial binary interval ratios improve rhythm reproduction.

Science.gov (United States)

Wu, Xiang; Westanmo, Anders; Zhou, Liang; Pan, Junhao

2013-01-01

Musical rhythm perception is a natural human ability that involves complex cognitive processes. Rhythm refers to the organization of events in time, and musical rhythms have an underlying hierarchical metrical structure. The metrical structure induces the feeling of a beat and the extent to which a rhythm induces the feeling of a beat is referred to as its metrical strength. Binary ratios are the most frequent interval ratio in musical rhythms. Rhythms with hierarchical binary ratios are better discriminated and reproduced than rhythms with hierarchical non-binary ratios. However, it remains unclear whether a superiority of serial binary over non-binary ratios in rhythm perception and reproduction exists. In addition, how different types of serial ratios influence the metrical strength of rhythms remains to be elucidated. The present study investigated serial binary vs. non-binary ratios in a reproduction task. Rhythms formed with exclusively binary (1:2:4:8), non-binary integer (1:3:5:6), and non-integer (1:2.3:5.3:6.4) ratios were examined within a constant meter. The results showed that the 1:2:4:8 rhythm type was more accurately reproduced than the 1:3:5:6 and 1:2.3:5.3:6.4 rhythm types, and the 1:2.3:5.3:6.4 rhythm type was more accurately reproduced than the 1:3:5:6 rhythm type. Further analyses showed that reproduction performance was better predicted by the distribution pattern of event occurrences within an inter-beat interval, than by the coincidence of events with beats, or the magnitude and complexity of interval ratios. Whereas rhythm theories and empirical data emphasize the role of the coincidence of events with beats in determining metrical strength and predicting rhythm performance, the present results suggest that rhythm processing may be better understood when the distribution pattern of event occurrences is taken into account. These results provide new insights into the mechanisms underlining musical rhythm perception.

Craniometric ratios of microcephaly and LB1, Homo floresiensis, using MRI and endocasts

Science.gov (United States)

Vannucci, Robert C.; Barron, Todd F.; Holloway, Ralph L.

2011-01-01

The designation of Homo floresiensis as a new species derived from an ancient population is controversial, because the type specimen, LB1, might represent a pathological microcephalic modern Homo sapiens. Accordingly, two specific craniometric ratios (relative frontal breadth and cerebellar protrusion) were ascertained in 21 microcephalic infants and children by using MRI. Data on 118 age-equivalent control (normocephalic) subjects were collected for comparative purposes. In addition, the same craniometric ratios were determined on the endocasts of 10 microcephalic individuals, 79 normal controls (anatomically modern humans), and 17 Homo erectus specimens. These ratios were then compared with those of two LB1 endocasts. The findings showed that the calculated cerebral/cerebellar ratios of the LB1 endocast [Falk D, et al. (2007) Proc Natl Acad Sci USA 104:2513–2518] fall outside the range of living normocephalic individuals. The ratios derived from two LB1 endocasts also fall largely outside the range of modern normal human and H. erectus endocasts and within the range of microcephalic endocasts. The findings support but do not prove the contention that LB1 represents a pathological microcephalic Homo sapiens rather than a new species, (i.e., H. floresiensis). PMID:21825126

In-situ confined formation of NiFe layered double hydroxide quantum dots in expanded graphite for active electrocatalytic oxygen evolution

Science.gov (United States)

Guo, Jinxue; Li, Xiaoyan; Sun, Yanfang; Liu, Qingyun; Quan, Zhenlan; Zhang, Xiao

2018-06-01

Development of noble-metal-free catalysts towards highly efficient electrochemical oxygen evolution reaction (OER) is critical but challenging in the renewable energy area. Herein, we firstly embed NiFe LDHs quantum dots (QDs) into expanded graphite (NiFe LDHs/EG) via in-situ confined formation process. The interlayer spacing of EG layers acts as nanoreactors for spatially confined formation of NiFe LDHs QDs. The QDs supply huge catalytic sites for OER. The in-situ decoration endows the strong affinity between QDs with EG, thus inducing fast charge transfer. Based on the aforementioned benefits, the designed catalyst exhibits outstanding OER properties, in terms of small overpotential (220 mV required to generate 10 mA cm-2), low Tafel slope, and good durable stability, making it a promising candidate for inexpensive OER catalyst.

An unstable social environment affects sex ratio in guinea pigs : an adaptive maternal effect?

NARCIS (Netherlands)

Kemme, Kristina; Kaiser, Sylvia; von Engelhardt, Nikolaus; Wewers, Dirk; Groothuis, Ton; Sachser, Norbert

2009-01-01

Evolutionary theory suggests that offspring sex should be adjusted to environmental conditions in order to maximize future reproductive success. In several animal taxa environmental factors indeed affect the secondary sex ratio. In humans, changes in the sex ratio at birth have been associated with

Volatile organic compound mixing ratios above Beijing in November and December 2016

Science.gov (United States)

Acton, William; Shaw, Marvin; Huang, Zhonghui; Wang, Zhaoyi; Wang, Xinming; Zhang, Yanli; Davison, Brian; Langford, Ben; Mullinger, Neil; Nemitz, Eiko; Fu, Pingqing; Squires, Freya; Carpenter, Lucy; Lewis, Alastair; Hewitt, Nick

2017-04-01

Volatile organic compounds (VOCs) are emitted into the atmosphere from vegetation and anthropogenic sources such as fossil fuel combustion, biomass burning and the evaporation of petroleum products. These compounds play an important role in the chemistry of the lower atmosphere through secondary organic aerosol (SOA) formation and facilitating the formation of tropospheric ozone. As well as their indirect impact on human health via the formation of ozone and SOA, some VOCs, including benzene, directly affect human health adversely. Here we report VOC mixing ratios measured in Beijing during a 5 week intensive field campaign from the 7th November to the 10th December 2016. This work was carried out as part of the Sources and Emissions of Air Pollutants in Beijing (AIRPOLL-Beijing) work project within the Air Pollution and Human Health in a Developing Megacity (APHH-Beijing) research programme. APHH is a large multi-institutional study which aims to record the concentrations and identify the sources of urban air pollutants in Beijing, determine exposure, understand their effects on human health, and to identify solutions. VOC mixing ratios were recorded using a Proton Transfer Reaction-Time of Flight-Mass Spectrometer (PTR-ToF-MS, Ionicon Analytik) and a Selected Ion Flow Tube-Mass Spectrometer (SIFT-MS, SYFT Technologies). During the measurement period Beijing was subject to multiple pollution events that alternated with periods of relatively good air quality, allowing the VOCs within the polluted air masses to be identified and quantified. VOCs were sampled at 102 m with additional gradient measurements made at 3, 15, 32 and 64 m providing a vertical profile of VOC mixing ratios. Mixing ratios of methanol, acetonitrile, acetaldehyde, acetone, isoprene and aromatics species will be reported together with a discussion of potential sources. Comparisons will then be drawn with other large cities.

Discriminating the endogenous and exogenous urinary estrogens in human by isotopic ratio mass spectrometry and its potential clinical value.

Science.gov (United States)

Yang, Sheng; Zhang, Dapeng; Xu, Youxuan; Wang, Xiaobing; Liu, Xin; Wang, Shan; Wang, Jingzhu; Wu, Moutian; He, Zhenwen; Zhao, Jian; Yuan, Hong

2013-02-01

Estrogens were prohibited in the food producing animals by European Union (96/22/EC directive) and added to the Report on Carcinogens in United States since 2002. Due to very low concentration in serum or urine (~pg/mL), the method of control its abuse had not been fully developed. The endogenous estrogens were separated from urines of 18 adult men and women. The exogenous estrogens were chemical reference standards and over the counter preparations. Two patients of dysfunctional uterine bleeding (DUB) administered exogenous estradiol and the urines were collected for 72 h. The urinary estrogens were separated by high-performance liquid chromatography (HPLC) and confirmed. The exogenous and exogenous estrogens were analyzed by gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) to determine the (13)C/(12)C ratio (δ(13)C‰). The δ(13)C‰ values of reference standard of E1, E2, and E3 were -29.36±0.72, -27.98±0.35, -27.62±0.51, respectively. The δ(13)C‰ values of the endogenous E1, E2, and E3 were -21.62±1.07, -22.14±0.98, and -21.88±1.16, with Pendogenous and exogenous urinary estrogen in human. Copyright © 2012 Elsevier Inc. All rights reserved.

O uso de recursos educativos abertos (rea: benefícios para alunos e professores. O repositório de acesso aberto de Portugal │ Use of open educational resources (oer: benefits for students and teachers. The Portuguese open access repository

Directory of Open Access Journals (Sweden)

Maria Teresa Ferreira Costa

2012-12-01

Full Text Available Resumo Os Recursos Educativos Abertos (REA têm sido utilizados um pouco por todo o mundo, por Instituições de Ensino Superior, no sentido de abrir o conhecimento a todos que dele necessitam e, muitas vezes, desenvolvendo-se num objectivo de nivelador social. A sua produção assume-se como um procedimento normal por parte dos docentes visando envolver também os alunos, de forma a transformar uma determinada realidade do processo de ensino-aprendizagem numa outra com o objectivo da inclusão. A utilização de materiais pedagógicos digitais livres fornece ao professor a possibilidade de adaptação desses objetos aos mais diversos contextos de aprendizagem conforme os níveis, estilos e necessidades específicas dos alunos. A adopção dos REA, intimamente associada e decorrente do Movimento do Acesso Aberto (AA, no processo de ensino-aprendizagem permite estabelecer uma metodologia diferente, inovadora e tecnologicamente atual, potenciadora do uso das novas tecnologias de informação e comunicação (TIC. Palavras-chave Acesso Aberto, Recursos Educativos Abertos, Processo de Ensino-Aprendizagem, Portugal Abstract Open Educational Resources (OER have been used all over the world by Universities with the purpose of sharing knowledge with those who seek it, and often developing as an objective for social issues. Its production is becoming a common procedure by teachers, in a way to both involve students and to transform a certain reality of the teaching-learning process into a more inclusive one. The use of free digital pedagogical material gives the teacher the possibility of adapting those objects to the many different contexts of the learning process, according to the students’ level, styles and specific needs. The choice for the use of OER, closely associated to the Open Access Movement (OAM, allows establishing an innovative methodology in the teaching-learning process, a technological solution that potentiates the use of the new

Dystonia

Science.gov (United States)

... eRA) Grants Policy OER News About OER Research Contracts Loan Repayment News News Releases News Feed RSS ... of dystonia – based in some cases on the manipulation of the genes linked to the disorder in ...

Temperature dependence of electrocatalytic and photocatalytic oxygen evolution reaction rates using NiFe oxide

KAUST Repository

Nurlaela, Ela; Shinagawa, Tatsuya; Qureshi, Muhammad; Dhawale, Dattatray Sadashiv; Takanabe, Kazuhiro

2016-01-01

The present work compares oxygen evolution reaction (OER) in electrocatalysis and photocatalysis in aqueous solutions using nanostructured NiFeOx as catalysts. The impacts of pH and reaction temperature on the electrocatalytic and photocatalytic OER

Diagnostisk værdi af humant choriongonadotropin-ratio versus enkelte S-humant choriongonadotropin-målinger ved graviditet med ukendt lokalisation

DEFF Research Database (Denmark)

Majeed, Huda Galib; Lyngsø, Julie; Bor, Pinar

2014-01-01

The diagnostic value of human chorionic gonadotrophin ratio compared to single measurements of S-human chorionic gonadotrophin on the outcome of pregnancy of unknown location Pregnancy of unknown location is defined by a positive pregnancy test, without visualizing of the intrauterine or extraute...... or extrauterine pregnancy by transvaginal sonography. We present the advantages of using human chorionic gonadotrophin (hCG) ratio instead of single measurements of S-hCG for predicting the outcomes of pregnancies of unknown location.......The diagnostic value of human chorionic gonadotrophin ratio compared to single measurements of S-human chorionic gonadotrophin on the outcome of pregnancy of unknown location Pregnancy of unknown location is defined by a positive pregnancy test, without visualizing of the intrauterine...

Dosimetry and radiobiology of negative pions and heavy ions

International Nuclear Information System (INIS)

Raju, M.R.

1978-01-01

The depth dose distribution of pion beams has not been found superior to protons. Pion radiation quality at the plateau region is comparable to conventional low-LET radiations, and radiobiology results also indicate RBE values close to unity. In the pion stopping region, the radiation quality increases considerably. Radiobiology data for negative pions at the Bragg peak position clearly indicate the increase in RBE and the reduction in OER. Even at the Bragg peak position, compared to fast neutrons, the average LET of negative pions is lower. Pion radiobiology data have indicated lower RBE values and higher OER values compared to fast neutrons. The radiation quality of fast neutrons is in between that of carbon and neon ions at the peak region and that of neon ions at the plateau is lower than for fast neutrons. The mean LET value for helium ions, even at the distal end of the peak, is lower than for fast neutrons. Dose localization of heavy ions has been found to decrease slowly with increasing charge of the heavy ion. The intercellular contact that protects cells after exposure to low-LET radiations is not detected after exposure to heavy ions. Single and fractionated doses of heavy ions produce dose-response curves for heavy ions having reduced shoulders but similar slopes when compared to gamma rays. Fractionated treatments of heavy ions produce an enhanced effect in the peak region compared to the plateau region and could lead to a substantial gain in therapeutic ratio. The OER for protons was similar to that for x rays. The OER values for negative pions, helium ions, and carbon ions were larger, for neon ions similar, and for argon ions smaller when compared to fast neutrons.Negative pions, helium ions, and carbon ions may be very effective clinically because the radiation quality of these beams is similar to that of the mixed scheme of neutrons and x rays

Analysis of Case-Parent Trios Using a Loglinear Model with Adjustment for Transmission Ratio Distortion

DEFF Research Database (Denmark)

Huang, Lam Opal; Infante-RIvard, Claire; Labbe, Aurélie

2016-01-01

Transmission of the two parental alleles to offspring deviating from the Mendelian ratio is termed Transmission Ratio Distortion (TRD), occurs throughout gametic and embryonic development. TRD has been well-studied in animals, but remains largely unknown in humans. The Transmission Disequilibrium...

Circadian changes in urinary Na + /K + ratio in humans: is there a ...

African Journals Online (AJOL)

Background: There are indications that the renal excretion of Na+ and K+ is affected by the body's circadian rhythm. Aldosterone is known to be the major determinant of urinary Na+/K+ ratio. However, recent reports suggest that the circadian rhythm of K+ excretion does not depend on endogenous aldosterone.

Identifying the Active Surfaces of Electrochemically Tuned LiCoO2 for Oxygen Evolution Reaction

International Nuclear Information System (INIS)

Lu, Zhiyi; Chen, Guangxu; Li, Yanbin; Wang, Haotian; Xie, Jin

2017-01-01

Identification of active sites for catalytic processes has both fundamental and technological implications for rational design of future catalysts. Herein, we study the active surfaces of layered lithium cobalt oxide (LCO) for the oxygen evolution reaction (OER) using the enhancement effect of electrochemical delithiation (De-LCO). Our theoretical results indicate that the most stable (0001) surface has a very large overpotential for OER independent of lithium content. In contrast, edge sites such as the nonpolar (1120) and polar (0112) surfaces are predicted to be highly active and dependent on (de)lithiation. The effect of lithium extraction from LCO on the surfaces and their OER activities can be understood by the increase of Co 4+ sites relative to Co 3+ and by the shift of active oxygen 2p states. Experimentally, it is demonstrated that LCO nanosheets, which dominantly expose the (0001) surface show negligible OER enhancement upon delithiation. However, a noticeable increase in OER activity (~0.1 V in overpotential shift at 10 mA cm –2 ) is observed for the LCO nanoparticles, where the basal plane is greatly diminished to expose the edge sites, consistent with the theoretical simulations. In addition, we find that the OER activity of De-LCO nanosheets can be improved if we adopt an acid etching method on LCO to create more active edge sites, which in turn provides a strong evidence for the theoretical indication.

Coping with unpredictability: Dopaminergic and neurotrophic responses to omission of expected reward in Atlantic salmon (Salmo salar L.)

DEFF Research Database (Denmark)

Vindas, Marco A; Sørensen, Christina; Johansen, Ida

2014-01-01

Comparative studies are imperative for understanding the evolution of adaptive neurobiological processes such as neural plasticity, cognition, and emotion. Previously we have reported that prolonged omission of expected rewards (OER, or 'frustrative nonreward') causes increased aggression....... Subsequently, the expected food reward was delayed for 30 minutes during two out of three meals per day in the OER treatment, while the previously established routine was maintained in control groups. After 8 days there was no effect of OER on baseline brain stem serotonin (5-HT) or dopamine (DA) activity....... Subsequent exposure to acute confinement stress led to increased plasma cortisol and elevated turnover of brain stem DA and 5-HT in all animals. The DA response was potentiated and DA receptor 1 (D1) mRNA abundance was reduced in the OER-exposed fish, indicating a sensitization of the DA system. In addition...

Examining the Reuse of Open Textbooks

Directory of Open Access Journals (Sweden)

John Hilton III

2012-04-01

Full Text Available An important element of open educational resources (OER is the permission to use the materials in new ways, including revising and remixing them. Prior research has shown that the revision and remix rates for OER are relatively low. In this study we examined the extent to which the openly licensed Flat World Knowledge textbooks were being revised and remixed. We found that the levels of revision and remix were similar to those of other OER collections. We discuss the possible significance and implication of these findings.

Iron Is the Active Site in Nickel/Iron Water Oxidation Electrocatalysts

Directory of Open Access Journals (Sweden)

Bryan M. Hunter

2018-04-01

Full Text Available Efficient catalysis of the oxygen-evolution half-reaction (OER is a pivotal requirement for the development of practical solar-driven water splitting devices. Heterogeneous OER electrocatalysts containing first-row transition metal oxides and hydroxides have attracted considerable recent interest, owing in part to the high abundance and low cost of starting materials. Among the best performing OER electrocatalysts are mixed Fe/Ni layered double hydroxides (LDH. A review of the available experimental data leads to the conclusion that iron is the active site for [NiFe]-LDH-catalyzed alkaline water oxidation.

Preparation and Characterization of Nicke-iron Alloy Film as Freestanding Electrode for Oxygen Evolution Reaction

Directory of Open Access Journals (Sweden)

Yao Mengqi

2018-01-01

Full Text Available This work reports the porous nicke-iron alloy film supported on stainless steel mesh as freestanding electrode for enhanced oxygen evolution reaction (OER catalyst prepared from an one step electrodeposition method. Results indicated that the porous nickle-iron alloy film exhibits a low overpotential of 270 mV at 10 mA cm-2 and excellent electroconductibility. The superior OER properties can be attributed to its novel synthetic process, conductive substrate and porous structure. This work will provide a new strategy to fabricate alloy film for OER electrocatalyst.

Omission of expected reward sensitizes the brain dopaminergic system of classically conditioned Atlantic salmon

DEFF Research Database (Denmark)

Vindas, M.A.; Höglund, Erik; Folkedal, O.

in fishes. Here we show that the omission of expected reward (OER) leads to increased aggression towards conspecifics in classically conditioned Atlantic salmon (Salmo salar). Furthermore, in response to an acute stressor, OER fish displayed increased dopaminergic (DA) neurotransmission compared to controls....... There was also a general downregulation of dopamine receptor D1 gene expression in the telencephalon of OER groups, which suggests a coping mechanism in response to unbalanced DA metabolism. These results indicate that animals subjected to unpredictable reward conditions develop a senzitation of the DA...

Kinetics of the oxygen effect in yeast irradiated in dry and wet conditions

International Nuclear Information System (INIS)

Kiefer, J.; Schoepfer, F.; Luggen-Hoelscher, J.

1981-01-01

There are indications that the radiobiological oxygen-effect consists of more than one component: in dry bacterial spores three different classes can be separated depending on exposure- and after-treatment conditions, the dependence of the oxygen-enhancement ratio (OER) on oxygen concentration shows breaks in various systems, and it has been suggested that type O and type N damage are localized in different parts of the cells. These questions were studied in the simple eucaryote Saccharomyces cerevisiae using two approaches: the dependence of OER on oxygen tension was determined both for survivial and mutation induction. Since a forward mutation was used a haploid strain had to be employed in this case. In order to assess whether also in yeast cells more than one component may exist, the techniques originally developed for bacterial spores were adapted for dried diploid yeast cells. The results show that the dependence on oxygen concentration is the same for survival and mutation within error limits, implicating DNA as the main target and that also in our system three classes of oxygen dependent damage exist

The Liquidity Coverage Ratio: the need for further complementary ratios?

OpenAIRE

Ojo, Marianne

2013-01-01

This paper considers components of the Liquidity Coverage Ratio – as well as certain prevailing gaps which may necessitate the introduction of a complementary liquidity ratio. The definitions and objectives accorded to the Liquidity Coverage Ratio (LCR) and Net Stable Funding Ratio (NSFR) highlight the focus which is accorded to time horizons for funding bank operations. A ratio which would focus on the rate of liquidity transformations and which could also serve as a complementary metric gi...

A Multinomial Model of Fertility Choice and Offspring Sex-Ratios in India

OpenAIRE

Rubiana Chamarbagwala; Martin Ranger

2007-01-01

Fertility decline in developing countries may have unexpected demographic consequences. Although lower fertility improves nutrition, health, and human capital investments for surviving children, little is known about the relationship between fertility outcomes and female-male offspring sex-ratios. Particularly in countries with a cultural preference for sons, like India and China, fertility decline may deteriorate the already imbalanced sex-ratios. We use the fertility histories of over 90,00...

Effects of glutathione depletion by buthionine sulfoximine on radiosensitization by oxygen and misonidazole in vitro

International Nuclear Information System (INIS)

Shrieve, D.C.; Denekamp, J.; Minchinton, A.I.

1985-01-01

Buthionine sulfoximine (BSO) has been used to deplete glutathione (GSH) in V79-379A cells in vitro, and the effect on the efficiency of oxygen and misonidazole (MISO) as radiosensitizers has been determined. Treatment with 50 or 500 μM BSO caused a rapid decline in GSH content to less than 5% of control values after 10 hr of exposure. Removal of BSO resulted in a rapid regeneration of GSH after 50 μM BSO, but little regeneration was observed over the subsequent 10-hr period after 500 μM. Cells irradiated in monolayer on glass had an oxygen enhancement ratio (OER) of 3.1. After 10-14 hr pretreatment with 50 μM BSO, washed cells were radiosensitized by GSH depletion at all oxygen tensions tested. The OER was reduced to 2.6, due to greater radiosensitization of hypoxic cells than aerated ones by GSH depletion. In similar experiments performed with MISO, an enhancement ratio of 2.0 could be achieved with 0.2 mM MISO in anoxic BSO-pretreated cells, compared to 2.7 mM MISO in non-BSO-treated cells. These apparent increases in radiosensitizer efficiency in GSH-depleted cells could be explained on the basis of radiosensitization of hypoxic cells by GSH depletion alone. These results are consistent with hypoxic cell radiosensitization by GSH depletion and by MISO or oxygen acting by separate mechanisms

Golden Ratio

Indian Academy of Sciences (India)

Keywords. Fibonacci numbers, golden ratio, Sanskrit prosody, solar panel. Abstract. Our attraction to another body increases if the body is symmetricaland in proportion. If a face or a structure is in proportion,we are more likely to notice it and find it beautiful.The universal ratio of beauty is the 'Golden Ratio', found inmany ...

Water Splitting by Thin Film Metal-Oxo Catalysts

Energy Technology Data Exchange (ETDEWEB)

Nocera, Daniel [Harvard Univ., Cambridge, MA (United States)

2013-03-15

The dropping price of silicon photovoltaics in the United States is causing load defection to solar supply at an accelerated pace. This conversion to solar and, more generally, other renewable energy sources has accordingly turned the energy research focus from generation to one of storage. Truly disruptive improvements in energy storage technologies are limited by energy density. This limitation, however, does not apply to fuels, which possess the energy density needed for large-scale energy storage. The first step of the basic science needed to drive such historic restructuring of the U.S. energy infrastructure begins with the solar-driven generation of hydrogen and oxygen from water. The solar-produced hydrogen may then be combined with carbon dioxide to deliver any number of fuels. Obviously, light does not directly act on water to engender its splitting into its elemental components. Hence, catalysts are needed to drive the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Of these two reactions, the four-electron, four-proton oxidation of OER is the more kinetically challenging reaction, and therefore the development of energy efficient solar fuels processes demands that OER be accomplished at a minimal overpotential. The research completed in this program developed catalysts that drive OER and at the same time meet the important criteria of (1) using non-critical materials that (2) are easy to assemble and (3) accomplish OER under simple conditions. Research was designed to uncover the chemical principles that underlie the self-assembly of metal oxide oxygen evolving catalysts (M-OEC) from the metals of M = Mn, Co, and Ni. For example, a dogma of heterogeneous catalysis of any sort is that “edges” matter in promoting catalytic transformations. We provided a rationale for such dogma by showing that the OER in Co-OEC occurred at a dimensionally reduced dicobalt edge site. Edge site reactivity was clearly revealed analyzing 18O labeled

Golden Ratio

Indian Academy of Sciences (India)

Our attraction to another body increases if the body is symmetricaland in proportion. If a face or a structure is in proportion,we are more likely to notice it and find it beautiful.The universal ratio of beauty is the 'Golden Ratio', found inmany structures. This ratio comes from Fibonacci numbers.In this article, we explore this ...

Ownership of dwelling affects the sex ratio at birth in Uganda.

Directory of Open Access Journals (Sweden)

Bernard Wallner

Full Text Available BACKGROUND: Socio-economic conditions can affect the secondary sex ratio in humans. Mothers under good environmental conditions are predicted to increase the birth rates of sons according to the Trivers-Willard hypothesis (TWH. This study analyzed the effects of ownership and non-ownership of dwellings on the sex ratio at birth (SRB on a Ugandan sample. METHODOLOGY/PRINCIPAL FINDINGS: Our investigation included 438,640 mothers aged between 12 and 54 years. The overall average SRB was 0.5008. Mothers who live in owned dwellings gave increased births to sons (0.5019 compared to those who live in non-owned dwellings (0.458. Multivariate statistics revealed the strongest effects of dwelling ownership when controlling for demographic and social variables such as marital status, type of marriage, mothers' age, mothers' education, parity and others. CONCLUSIONS/SIGNIFICANCE: The results are discussed in the framework of recent plausible models dealing with the adjustment of the sex ratio. We conclude that the aspect of dwelling status could represent an important socio-economic parameter in relation to SRB variations in humans if further studies are able to analyze it between different countries in a comparative way.

Ownership of dwelling affects the sex ratio at birth in Uganda.

Science.gov (United States)

Wallner, Bernard; Fieder, Martin; Seidler, Horst

2012-01-01

Socio-economic conditions can affect the secondary sex ratio in humans. Mothers under good environmental conditions are predicted to increase the birth rates of sons according to the Trivers-Willard hypothesis (TWH). This study analyzed the effects of ownership and non-ownership of dwellings on the sex ratio at birth (SRB) on a Ugandan sample. Our investigation included 438,640 mothers aged between 12 and 54 years. The overall average SRB was 0.5008. Mothers who live in owned dwellings gave increased births to sons (0.5019) compared to those who live in non-owned dwellings (0.458). Multivariate statistics revealed the strongest effects of dwelling ownership when controlling for demographic and social variables such as marital status, type of marriage, mothers' age, mothers' education, parity and others. The results are discussed in the framework of recent plausible models dealing with the adjustment of the sex ratio. We conclude that the aspect of dwelling status could represent an important socio-economic parameter in relation to SRB variations in humans if further studies are able to analyze it between different countries in a comparative way.

Ownership of Dwelling Affects the Sex Ratio at Birth in Uganda

Science.gov (United States)

Wallner, Bernard; Fieder, Martin; Seidler, Horst

2012-01-01

Background Socio-economic conditions can affect the secondary sex ratio in humans. Mothers under good environmental conditions are predicted to increase the birth rates of sons according to the Trivers-Willard hypothesis (TWH). This study analyzed the effects of ownership and non-ownership of dwellings on the sex ratio at birth (SRB) on a Ugandan sample. Methodology/Principal Findings Our investigation included 438,640 mothers aged between 12 and 54 years. The overall average SRB was 0.5008. Mothers who live in owned dwellings gave increased births to sons (0.5019) compared to those who live in non-owned dwellings (0.458). Multivariate statistics revealed the strongest effects of dwelling ownership when controlling for demographic and social variables such as marital status, type of marriage, mothers’ age, mothers’ education, parity and others. Conclusions/Significance The results are discussed in the framework of recent plausible models dealing with the adjustment of the sex ratio. We conclude that the aspect of dwelling status could represent an important socio-economic parameter in relation to SRB variations in humans if further studies are able to analyze it between different countries in a comparative way. PMID:23284697

Golden Ratio

Indian Academy of Sciences (India)

Our attraction to another body increases if the body is sym- metrical and in proportion. If a face or a structure is in pro- portion, we are more likely to notice it and find it beautiful. The universal ratio of beauty is the 'Golden Ratio', found in many structures. This ratio comes from Fibonacci numbers. In this article, we explore this ...

Radiographic measurement of the cardiothoracic ratio in a feral population of long-tailed macaques (Macaca fascicularis)

Energy Technology Data Exchange (ETDEWEB)

Schillaci, Michael A. [Department of Social Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4 (Canada)], E-mail: schillaci@utsc.utoronto.ca; Lischka, Andrea R.; Karamitsos, Anisah A. [Department of Social Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4 (Canada); Engel, Gregory A. [Swedish/Cherry Hill Family Medicine Residency, 550 16th Avenue, Seattle, WA 98122 (United States); Washington National Primate Research Center, University of Washington, Seattle, WA 98195 (United States); Paul, Narinder [Division of Cardiothoracic Imaging, University Health Network, University of Toronto, Toronto, Ontario M5G 2N2 (Canada); Ramoul, Rima [Department of Social Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4 (Canada); Rompis, Aida; Putra, Arta; Wandia, I. Nengah [Fakultas Kedokteran Hewan, Udayana University, Denpasar, Bali 80361 (Indonesia); Jones-Engel, Lisa [Washington National Primate Research Center, University of Washington, Seattle, WA 98195 (United States)

2010-05-15

The cardiothoracic ratio is often used as a proxy measure of cardiovascular pathophysiology in humans but less frequently in nonhuman primates, for whom little published data are available to establish normal values. The present study is the first to examine relative cardiac size in a feral population of primates. This report presents estimates of the cardiothoracic ratio in long-tailed macaques (Macaca fascicularis) from Bali, Indonesia. The mean cardiothoracic ratio for the study sample was 0.55, above the commonly used threshold of 0.50 for identifying an enlarged heart in human medicine. Future research on wild populations of macaques is needed and should include multiple assessments of cardiac function including both radiography and echocardiography.

Radiographic measurement of the cardiothoracic ratio in a feral population of long-tailed macaques (Macaca fascicularis)

International Nuclear Information System (INIS)

Schillaci, Michael A.; Lischka, Andrea R.; Karamitsos, Anisah A.; Engel, Gregory A.; Paul, Narinder; Ramoul, Rima; Rompis, Aida; Putra, Arta; Wandia, I. Nengah; Jones-Engel, Lisa

2010-01-01

The cardiothoracic ratio is often used as a proxy measure of cardiovascular pathophysiology in humans but less frequently in nonhuman primates, for whom little published data are available to establish normal values. The present study is the first to examine relative cardiac size in a feral population of primates. This report presents estimates of the cardiothoracic ratio in long-tailed macaques (Macaca fascicularis) from Bali, Indonesia. The mean cardiothoracic ratio for the study sample was 0.55, above the commonly used threshold of 0.50 for identifying an enlarged heart in human medicine. Future research on wild populations of macaques is needed and should include multiple assessments of cardiac function including both radiography and echocardiography.

Investigating the social configuration of a community to understand how networked learning activities take place: The OERu case study

NARCIS (Netherlands)

Schreurs, Bieke; Van den Beemt, Antoine; Prinsen, Fleur; De Laat, Maarten; Witthaus, Gaby; Conole, Grainne

2015-01-01

Examining how OER (Open Educational Resources) communities come to live, function or learn can support in empowering educators in the use of open educational resources. In this paper we investigate how an OER community functions through its networked learning activities. Networked learning

Complementation of mitochondrial electron transport chain by manipulation of the NAD+/NADH ratio.

Science.gov (United States)

Titov, Denis V; Cracan, Valentin; Goodman, Russell P; Peng, Jun; Grabarek, Zenon; Mootha, Vamsi K

2016-04-08

A decline in electron transport chain (ETC) activity is associated with many human diseases. Although diminished mitochondrial adenosine triphosphate production is recognized as a source of pathology, the contribution of the associated reduction in the ratio of the amount of oxidized nicotinamide adenine dinucleotide (NAD(+)) to that of its reduced form (NADH) is less clear. We used a water-forming NADH oxidase from Lactobacillus brevis (LbNOX) as a genetic tool for inducing a compartment-specific increase of the NAD(+)/NADH ratio in human cells. We used LbNOX to demonstrate the dependence of key metabolic fluxes, gluconeogenesis, and signaling on the cytosolic or mitochondrial NAD(+)/NADH ratios. Expression of LbNOX in the cytosol or mitochondria ameliorated proliferative and metabolic defects caused by an impaired ETC. The results underscore the role of reductive stress in mitochondrial pathogenesis and demonstrate the utility of targeted LbNOX for direct, compartment-specific manipulation of redox state. Copyright © 2016, American Association for the Advancement of Science.

Sex ratios

OpenAIRE

West, Stuart A; Reece, S E; Sheldon, Ben C

2002-01-01

Sex ratio theory attempts to explain variation at all levels (species, population, individual, brood) in the proportion of offspring that are male (the sex ratio). In many cases this work has been extremely successful, providing qualitative and even quantitative explanations of sex ratio variation. However, this is not always the situation, and one of the greatest remaining problems is explaining broad taxonomic patterns. Specifically, why do different organisms show so ...

Use of combined alpha-spectrometry and fission track analysis for the determination of 240Pu/239Pu ratios in human tissue

International Nuclear Information System (INIS)

Love, S.F.; Filby, R.H.; Glover, S.E.; Stuit, D.B.; Kathren, R.L.

1998-01-01

Plutonium and other actinides were determined in human autopsy tissues of occupationally exposed workers who were registrants of the United States Transuranium and Uranium Registries (USTUR). In this study, Pu was purified and isolated from Am, U and Th, after drying and wet-ashing of the tissues, and the addition of 238 Pu as a radiotracer. After electrodeposition onto vanadium planchets, the 239+240 Pu activity was determined by alpha-spectrometry. A fission track method was developed to determine 239 Pu in the presence of 238 Pu and 240 Pu, using Lexan TM polycarbonate detectors. Combining the two techniques allowed the determination of the 240 Pu/ 239 Pu activity and atom ratios. Data from selected USTUR cases are presented. (author)

Sex Ratio Elasticity Influences the Selection of Sex Ratio Strategy

Science.gov (United States)

Wang, Yaqiang; Wang, Ruiwu; Li, Yaotang; (Sam) Ma, Zhanshan

2016-12-01

There are three sex ratio strategies (SRS) in nature—male-biased sex ratio, female-biased sex ratio and, equal sex ratio. It was R. A. Fisher who first explained why most species in nature display a sex ratio of ½. Consequent SRS theories such as Hamilton’s local mate competition (LMC) and Clark’s local resource competition (LRC) separately explained the observed deviations from the seemingly universal 1:1 ratio. However, to the best of our knowledge, there is not yet a unified theory that accounts for the mechanisms of the three SRS. Here, we introduce the price elasticity theory in economics to define sex ratio elasticity (SRE), and present an analytical model that derives three SRSs based on the following assumption: simultaneously existing competitions for both resources A and resources B influence the level of SRE in both sexes differently. Consequently, it is the difference (between two sexes) in the level of their sex ratio elasticity that leads to three different SRS. Our analytical results demonstrate that the elasticity-based model not only reveals a highly plausible mechanism that explains the evolution of SRS in nature, but also offers a novel framework for unifying two major classical theories (i.e., LMC & LRC) in the field of SRS research.

Supporting open education policymaking by higher education institutions in the Netherlands: lessons learned

NARCIS (Netherlands)

Hester Jelgerhuis; Dr. ir. Robert Schuwer; Ben Janssen

2014-01-01

A survey conducted in 2012 among publicly financed higher education institutions in the Netherlands revealed a growing awareness of the strategic relevance of Open Educational Resources (OER) and Open Education. However, hardly any policy or strategy related to OER and Open Education had been

Metal phosphonate coordination networks and frameworks as precursors of electrocatalysts for the hydrogen and oxygen evolution reactions

Science.gov (United States)

Zhang, Rui; El-Refaei, Sayed M.; Russo, Patrícia A.; Pinna, Nicola

2018-05-01

The hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) play key roles in the conversion of energy derived from renewable energy sources into chemical energy. Efficient, robust, and inexpensive electrocatalysts are necessary for driving these reactions at high rates at low overpotentials and minimize energetic losses. Recently, electrocatalysts derived from hybrid metal phosphonate compounds have shown high activity for the HER or OER. We review here the utilization of metal phosphonate coordination networks and metal-organic frameworks as precursors/templates for transition-metal phosphides, phosphates, or oxyhydroxides generated in situ in alkaline solutions, and their electrocatalytic performance in HER or OER.

Radiosensitizers and the oxygen effects in mammalian cells

International Nuclear Information System (INIS)

Millar, B.C.; Fielden, E.M.; Steele, J.J.

1979-01-01

The survival curves for Chinese Hamster cells irradiated under various oxygen tensions have been determined. The variation in OER with oxygen concentration shows two distinct components. Between 1.4 and 7.0 μM the OER is constant with a value of 1.9. Experiments with nitroaromatic radiosensitizers in combination with low concentrations of oxygen show that they can all mimic the 'low concentration' oxygen effect. Of the compounds tested only misonidazole can apparently mimic the 'high concentration' oxygen effect although the full OER cannot be obtained with the authors cell line because of toxicity by the sensitizer. (Auth.)

The Motivation Impact of Open Educational Resources Utilization on Physics Learning Using Quipper School App

Directory of Open Access Journals (Sweden)

Dwi SULISWORO

2017-10-01

Full Text Available The distribution of the education quality in Indonesia is relatively uneven. This affects the quality of secondary school graduates. On the other hand, the national growth of Information Communication Technology usage in Indonesia is very high, including the use of mobile technology. This is an opportunity for the application of OER (Open Educational Resources in learning. This study aims to look at the impact of the application of the concept of blended learning OER to motivate students, especially in learning physics. The LMS used is Quipper School. This research is the quasy experiment using post test only for control group design. ARCS (Attention, Relevance, Confidence, and Satisfaction models used in this study to observe the attention factor, relevance, confidence, and satisfaction. The analysis technique used is the analysis of variance (ANOVA. From this research, it is known that the application of the concept of OER in learning, will increase the motivation on the aspects of attention, relevance, and the confidence of the students. Meanwhile, the aspect of satisfaction on learning tends to be the same between applying the concept of OER when compared to the conventional learning face-to-face in the classroom. These findings indicate a positive impact of the application of the concept of OER in learning to student motivation.

Questions of quality in repositories of open educational resources: a literature review

Directory of Open Access Journals (Sweden)

Javiera Atenas

2014-07-01

Full Text Available Open educational resources (OER are teaching and learning materials which are freely available and openly licensed. Repositories of OER (ROER are platforms that host and facilitate access to these resources. ROER should not just be designed to store this content – in keeping with the aims of the OER movement, they should support educators in embracing open educational practices (OEP such as searching for and retrieving content that they will reuse, adapt or modify as needed, without economic barriers or copyright restrictions. This paper reviews key literature on OER and ROER, in order to understand the roles ROER are said or supposed to fulfil in relation to furthering the aims of the OER movement. Four themes which should shape repository design are identified, and the following 10 quality indicators (QI for ROER effectiveness are discussed: featured resources; user evaluation tools; peer review; authorship of the resources; keywords of the resources; use of standardised metadata; multilingualism of the repositories; inclusion of social media tools; specification of the creative commons license; availability of the source code or original files. These QI form the basis of a method for the evaluation of ROER initiatives which, in concert with considerations of achievability and long-term sustainability, should assist in enhancement and development.

Exploring the kinetic and thermodynamic aspects of four-electron electrochemical reactions: electrocatalysis of oxygen evolution by metal oxides and biological systems.

Science.gov (United States)

Wang, Vincent C-C

2016-08-10

Finding fundamental and general mechanisms for electrochemical reactions, such as the oxygen evolution reaction (OER) from water and reduction of CO2, plays vital roles in developing the desired electrocatalysts for facilitating solar fuel production. Recently, density functional theory (DFT) calculations have shown that there is a universal scaling relation of adsorption energy between key intermediate species, HO(ad) and HOO(ad), on the surface of metal oxides as OER electrocatalysts. In this paper, a kinetic and thermodynamic model for the four-electron electrochemical reaction based on previous OER mechanisms proposed by DFT calculations is developed to further investigate the electrocatalytic properties over a wide range of metal oxides and photosystem II. The OER activity of metal oxides (i.e. electrocatalytic current) calculated from the DFT-calculated equilibrium potentials with kinetic properties, such as the rate constants for interfacial electron transfer and catalytic turnover, can lead to a volcano-shaped trend that agrees with the results observed in experiments. In addition, the kinetic aspects of the impact on the electrocatalysts are evaluated. Finally, comparing the results of metal oxides and photosystem II, and fitting experimental voltammograms give further insights into kinetic and thermodynamic roles. Here, the general guidelines for designing OER electrocatalysts with unified kinetic and thermodynamic properties are presented.

Effect of superoxide dismutase and catalase on radiation-induced inhibition of human lymphocyte blastogenesis

International Nuclear Information System (INIS)

Knox, S.; Misra, H.P.; Rosenblatt, L.S.; Shifrine, M.

1980-01-01

Mitogen-induced lymphocyte blastogenesis was measured following x-irradiation (0 to 400 R) in the presence or absence of SOD, under aerobic or anaerobic conditions. No significant differences were observed between radiation survival curves under these different conditions. SOD had no radioprotective effect, and an o.e.r. of 1.11 was obtained, demonstrating the lack of oxygen dependence of radiation-induced inhibition of lymphocyte blastogenesis. Following x-irradiation at 200 R, neither SOD nor catalase, alone or together, added before or after irradiation, was radioprotective

Effect of semen quality on human sex ratio in in vitro fertilization and intracytoplasmic sperm injection: an analysis of 27,158 singleton infants born after fresh single-embryo transfer.

Science.gov (United States)

Arikawa, Mikiko; Jwa, Seung Chik; Kuwahara, Akira; Irahara, Minoru; Saito, Hidekazu

2016-04-01

To evaluate the effect of semen quality on human sex ratio in in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). Retrospective cohort study. Not applicable. A total of 27,158 singleton infants born between 2007 and 2012 after fresh single-embryo transfer. None. Proportion of male infants among liveborn infants. There were 14,996 infants born after IVF, 12,164 infants born after ICSI with ejaculated sperm, and 646 infants born after ICSI with nonejaculated sperm. The sex ratio of IVF was 53.1% (95% confidence interval [CI], 52.3-53.9); the sex ratio of ICSI with ejaculated and nonejaculated sperm demonstrated as statistically significant reduction (48.2%; 95% CI, 47.3-49.1 and 47.7%; 95% CI, 43.8-51.6, respectively). In IVF, lower sperm motility, including asthenozoospermia (sperm motility ratio compared with normal sperm (51.0%; 95% CI, 48.6-53.3 vs. 53.4%; 95% CI, 52.5-54.3). In ICSI with ejaculated sperm, there was no association between sperm motility and sex ratio. Sperm concentration was not associated with sex ratio in both IVF and ICSI. In IVF, lower sperm motility was associated with a statistically significant reduction in sex ratio; ICSI with either ejaculated or nonejaculated sperm was associated with a statistically significant reduction in sex ratio regardless of semen quality. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Sr/Ca mass ratio determination in bones using fast neutron activation analysis

International Nuclear Information System (INIS)

Hult, Mikael; Fessler, Andreas

1998-01-01

The Sr/Ca mass ratio in human bones reveals information regarding the diet which is of interest in archaeology. By using fast neutron activation analysis this ratio can be measured in a non-destructive manner, which is important when bones are considered too precious to allow for destructive analysis. Simulations and measurements showed that the nuclear reactions 88 Sr(n, 2n) 87m Sr and 44 Ca(n, p) 44 K are highly useful for the purpose

The impact of sex ratio and economic status on local birth rates.

Science.gov (United States)

Chipman, A; Morrison, E

2013-04-23

Human mating and reproductive behaviour can vary depending on various mechanisms, including the local sex ratio. Previous research shows that as sex ratios become female-biased, women from economically deprived areas are less likely to delay reproductive opportunities to wait for a high-investing mate but instead begin their reproductive careers sooner. Here, we show that the local sex ratio also has an impact on female fertility schedules. At young ages, a female-biased ratio is associated with higher birth rates in the poorest areas, whereas the opposite is true for the richest areas. At older ages, a female-biased ratio is associated with higher birth rates in the richest, but not the poorest areas. These patterns suggest that female-female competition encourages poorer women to adopt a fast life-history strategy and give birth early, and richer women to adopt a slow life-history strategy and delay reproduction.

Selenium:Mercury Molar Ratios in Freshwater Fish from Tennessee: Individual, Species, and Geographical Variations have Implications for Management

Science.gov (United States)

Burger, Joanna; Gochfeld, Michael; Jeitner, C.; Donio, M.; Pittfield, T.

2014-01-01

Vertebrates, including humans, can experience adverse effects from mercury consumed in fish. Humans often prefer large predatory fish that bioaccumulate high mercury levels. Recent attention has focused on the role of selenium countering mercury toxicity, but there is little research on the selenium:mercury molar ratios in freshwater fish. We examine selenium:mercury molar ratios in freshwater fish from Tennessee at Poplar Creek which receives ongoing inputs of mercury from the Department of Energy’s Oak Ridge Y-12 facility. Our objective was to determine variation of the ratios within species that might affect the protectiveness of selenium against mercury toxicity. Within species, the ratio was correlated significantly and positively with fish length only for two species. There was great individual variation in the selenium:mercury molar ratio within each species, except striped bass. The lack of a clear relationship between the selenium:mercury molar ratio and fish length, and the intraspecific variation, suggests that it would be difficult to use the molar ratio in predicting either the risk from mercury toxicity or in devising consumption advisories. PMID:22456727

Human permanent teeth are divided into two parts at the cemento-enamel junction in the divine golden ratio.

Science.gov (United States)

Anand, Rahul; Sarode, Sachin C; Sarode, Gargi S; Patil, Shankargouda

2017-01-01

The aim of this study is to find out whether tooth length (crown length + root length) follows the rule of most divine and mysterious phi (ϕ) or the golden ratio. A total of 140 teeth were included in the study. The crown-root ratio was manually calculated using vernier caliper and its approximation to golden ratio or the divine number phi (ϕ) was examined. The average root-crown ratio (R/C) for maxillary central incisor was 1.627 ± 0.04, and of its antagonist, mandibular central incisor was 1.628 ± 0.02. The tooth-root ratio (T/R) for the same was 1.609 ± 0.016 and 1.61 ± 0.008, respectively. Similar values were appreciated for lateral incisors where the R/C ratio in the maxillary and mandibular teeth was 1.632 ± 0.015 and 1.641 ± 0.012 and the T/R ratio was 1.606 ± 0.005 and 1.605 ± 0.005, respectively. On measuring the tooth length in linear fashion from the cusp tip to the root apex, we found that the tooth was divided into two parts at the cemento-enamel junction in the golden ratio. This information can be exploited in restorative and implant dentistry in future.

Opening teaching landscapes: The importance of quality assurance in the delivery of open educational resources

Directory of Open Access Journals (Sweden)

Javiera Atenas

2014-02-01

Full Text Available Scholars are increasingly being asked to share teaching materials, publish in open access journals, network in social media, and reuse open educational resources (OER. The theoretical benefits of Open Educational Practices (OEP have become understood in the academic community but thus far, the use of OER has not been rapidly adopted. We aim to understand the challenges academics face with in attempting to adopt OEP, and identify whether these are related to or stem from the functionalities afforded by current repositories of OER (ROER. By understanding what academics and experts consider good practices, we can develop guidelines for quality in the development of ROER. In this article we present the findings from a study surveying academics using OER and experts who develop and/or work with ROER. We conclude by suggesting a framework to enhance the development and quality of ROER.http://dx.doi.org/10.5944/openpraxis.6.1.81

An investigation of thin-film Ni-Fe oxide catalysts for the electrochemical evolution of oxygen.

Science.gov (United States)

Louie, Mary W; Bell, Alexis T

2013-08-21

A detailed investigation has been carried out of the structure and electrochemical activity of electrodeposited Ni-Fe films for the oxygen evolution reaction (OER) in alkaline electrolytes. Ni-Fe films with a bulk and surface composition of 40% Fe exhibit OER activities that are roughly 2 orders of magnitude higher than that of a freshly deposited Ni film and about 3 orders of magnitude higher than that of an Fe film. The freshly deposited Ni film increases in activity by as much as 20-fold during exposure to the electrolyte (KOH); however, all films containing Fe are stable as deposited. The oxidation of Ni(OH)2 to NiOOH in Ni films occurs at potentials below the onset of the OER. Incorporation of Fe into the film increases the potential at which Ni(OH)2/NiOOH redox occurs and decreases the average oxidation state of Ni in NiOOH. The Tafel slope (40 mV dec(-1)) and reaction order in OH(-) (1) for the mixed Ni-Fe films (containing up to 95% Fe) are the same as those for aged Ni films. In situ Raman spectra acquired in 0.1 M KOH at OER potentials show two bands characteristic of NiOOH. The relative intensities of these bands vary with Fe content, indicating a change in the local environment of Ni-O. Similar changes in the relative intensities of the bands and an increase in OER activity are observed when pure Ni films are aged. These observations suggest that the OER is catalyzed by Ni in Ni-Fe films and that the presence of Fe alters the redox properties of Ni, causing a positive shift in the potential at which Ni(OH)2/NiOOH redox occurs, a decrease in the average oxidation state of the Ni sites, and a concurrent increase in the activity of Ni cations for the OER.

PENGARUH PERUBAHAN RETURN ON ASSETS, PERUBAHAN DEBT TO EQUITY RATIO DAN PERUBAHAN CASH RATIO TERHADAP PERUBAHAN DIVIDEND PAYOUT RATIO

Directory of Open Access Journals (Sweden)

Yuli Soesetio

2008-02-01

Full Text Available Dividend Payout Ratio used to calculate all of revenue that will be accepted by stockholders as cash dividend, usually explained as percentage. This research was conducted to know several factors that affected change of Dividend Payout Ratio and to know the significance level and the correlation between dependent and independent variable. Analysis instrument used was parametric statistic. Based on the result of statistic test,  The Change of Return on Asset (X1, The Change of Debt to Equity Ratio (X2,  were able to explain dependent variable of the change Dividend Payout Ratio, and The Change of CashRatio can’t explain dependent variable of the change Dividend Payout Ratio

Ratio of the dose factors of the isotopes of iodine

International Nuclear Information System (INIS)

Papadopoulos, D.; Thomas, P.

1977-12-01

The ratio of dose factors occurring during inhalation and ingestion to the respective dose factors of I-129 is calculated for the isotopes of I-123 to I-126 and I-129 to I-135. All the dose factors refer to the thyroid as the critical organ. A distinction is made between adults and infants up to 1 year of age. To calculate the ratios only the effective energies and the effective half-lives in the human body and on grass are required. Most of the data have been taken from the literature. The effective energies of I-123 and I-125 have been calculated as examples. (orig.) [de

Cellular and molecular radiobiology of heavy-ion beams

International Nuclear Information System (INIS)

Tobias, C.A.; Blakely, E.A.; Ngo, F.Q.H.; Roots, R.J.; Yang, T.C.H.; Chang, P.Y.; Lommel, L.; Craise, L.M.; Yezzi, M.J.

1982-01-01

Accelerated heavy particles are candidates for use in cancer radiotherapy, and the major goal of our program has been to characterize the biological potential of Bevalac beams for this purpose. Relative biological effectiveness (RBE) values and oxygen enhancement ratio (OER) properties of monoenergetic carbon, neon, and argon beams with initial energies of several hundred MeV/u have been measured as a function of residual range. Bevalac beams with Bragg peaks modified to encompass tumors of various sizes have also been studied using cultured cells in vitro

Electrochemical investigation of surface area effects on PVD Al-Ni as electrocatalyst for alkaline water electrolysis

DEFF Research Database (Denmark)

Kjartansdóttir, Cecilía Kristín; Caspersen, Michael; Egelund, Sune Daaskov

2014-01-01

, additional 40mV are gained. For the OER, smaller roughness values were observed with the same activity trend as for the HER. The electrocatalyst are however found not to be stable in the anodic environment during electrolysis. The corrosion mechanism of a skeletal nickel electrocatalyst during the OER...

NOAA Office of Exploration and Research > Exploration > Systematic

Science.gov (United States)

Vessel (E/V) Nautilus in real-time on Internet 2 and the Internet. A legacy of high quality imagery, high . Contact Information for OER Okeanos Explorer Program: Craig Russell NOAA/OAR/OER 7600 Sand Point Way NE | Disclaimer | Privacy Policy | FOIA | Web Accessibility Statement | Information Quality Copyright NOAA 2013

Conceptual Framework for Parametrically Measuring the Desirability of Open Educational Resources Using D-Index

Science.gov (United States)

Abeywardena, Ishan Sudeera; Tham, Choy Yoong; Raviraja, S.

2012-01-01

Open educational resources (OER) are a global phenomenon that is fast gaining credibility in many academic circles as a possible solution for bridging the knowledge divide. With increased funding and advocacy from governmental and nongovernmental organisations paired with generous philanthropy, many OER repositories, which host a vast array of…

The RISE Framework: Using Learning Analytics to Automatically Identify Open Educational Resources for Continuous Improvement

Science.gov (United States)

Bodily, Robert; Nyland, Rob; Wiley, David

2017-01-01

The RISE (Resource Inspection, Selection, and Enhancement) Framework is a framework supporting the continuous improvement of open educational resources (OER). The framework is an automated process that identifies learning resources that should be evaluated and either eliminated or improved. This is particularly useful in OER contexts where the…

Beyond the top of the volcano? - A unified approach to electrocatalytic oxygen reduction and oxygen evolution

DEFF Research Database (Denmark)

Busch, Michael; Halck, Niels Bendtsen; Kramm, Ulrike I.

2016-01-01

gives rise to a double volcano for ORR and OER, with a region in between, forbidden by the scaling relations. The reversible perfect catalyst for both ORR and OER would fall into this "forbidden region". Previously, we have found that hydrogen acceptor functionality on oxide surfaces can improve...

Gently reduced graphene oxide incorporated into cobalt oxalate rods as bifunctional oxygen electrocatalyst

International Nuclear Information System (INIS)

Phihusut, Doungkamon; Ocon, Joey D.; Jeong, Beomgyun; Kim, Jin Won; Lee, Jae Kwang; Lee, Jaeyoung

2014-01-01

Graphical abstract: - Abstract: Water-oxygen electrochemistry is at the heart of key renewable energy technologies (fuel cells, electrolyzers, and metal-air batteries) due to the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Although much effort has been devoted to the development of improved bifunctional electrocatalysts, an inexpensive, highly active oxygen electrocatalyst, however, remains to be a challenge. In this paper, we present a facile and robust method to create gently reduced graphene oxide incorporated into cobalt oxalate microstructures (CoC 2 O 4 /gRGO) and demonstrate its excellent and stable electrocatalytic activity in both OER and ORR, arising from the inherent properties of the components and their physicochemical interaction. Our synthesis technique also explores a single pot method to partially reduce graphene oxide and form CoC 2 O 4 structures while maintaining the solution processability of reduced graphene oxide. While the OER activity of CoC 2 O 4 /gRGO is exclusively due to CoC 2 O 4 , which transformed into OER-active Co species, the combination with gRGO significantly improves OER stability. On the other hand, CoC 2 O 4 /gRGO exhibits synergistic effect towards ORR, via a quasi-four-electron pathway, leading to a slightly higher ORR limiting current than Pt/C. Remarkably, gRGO offers dual functionality, contributing to ORR activity via the N-functional groups and also enhancing OER stability through the gRGO coating around CoC 2 O 4 structures. Our results suggest a new class of metal-carbon composite that has the potential to be alternative bifunctional catalysts for regenerative fuel cells and metal-air batteries

Coping with unpredictability: dopaminergic and neurotrophic responses to omission of expected reward in Atlantic salmon (Salmo salar L.).

Science.gov (United States)

Vindas, Marco A; Sørensen, Christina; Johansen, Ida B; Folkedal, Ole; Höglund, Erik; Khan, Uniza W; Stien, Lars H; Kristiansen, Tore S; Braastad, Bjarne O; Øverli, Øyvind

2014-01-01

Comparative studies are imperative for understanding the evolution of adaptive neurobiological processes such as neural plasticity, cognition, and emotion. Previously we have reported that prolonged omission of expected rewards (OER, or 'frustrative nonreward') causes increased aggression in Atlantic salmon (Salmo salar). Here we report changes in brain monoaminergic activity and relative abundance of brain derived neurotrophic factor (BDNF) and dopamine receptor mRNA transcripts in the same paradigm. Groups of fish were initially conditioned to associate a flashing light with feeding. Subsequently, the expected food reward was delayed for 30 minutes during two out of three meals per day in the OER treatment, while the previously established routine was maintained in control groups. After 8 days there was no effect of OER on baseline brain stem serotonin (5-HT) or dopamine (DA) activity. Subsequent exposure to acute confinement stress led to increased plasma cortisol and elevated turnover of brain stem DA and 5-HT in all animals. The DA response was potentiated and DA receptor 1 (D1) mRNA abundance was reduced in the OER-exposed fish, indicating a sensitization of the DA system. In addition OER suppressed abundance of BDNF in the telencephalon of non-stressed fish. Regardless of OER treatment, a strong positive correlation between BDNF and D1 mRNA abundance was seen in non-stressed fish. This correlation was disrupted by acute stress, and replaced by a negative correlation between BDNF abundance and plasma cortisol concentration. These observations indicate a conserved link between DA, neurotrophin regulation, and corticosteroid-signaling pathways. The results also emphasize how fish models can be important tools in the study of neural plasticity and responsiveness to environmental unpredictability.

High-speed and high-ratio referential genome compression.

Science.gov (United States)

Liu, Yuansheng; Peng, Hui; Wong, Limsoon; Li, Jinyan

2017-11-01

The rapidly increasing number of genomes generated by high-throughput sequencing platforms and assembly algorithms is accompanied by problems in data storage, compression and communication. Traditional compression algorithms are unable to meet the demand of high compression ratio due to the intrinsic challenging features of DNA sequences such as small alphabet size, frequent repeats and palindromes. Reference-based lossless compression, by which only the differences between two similar genomes are stored, is a promising approach with high compression ratio. We present a high-performance referential genome compression algorithm named HiRGC. It is based on a 2-bit encoding scheme and an advanced greedy-matching search on a hash table. We compare the performance of HiRGC with four state-of-the-art compression methods on a benchmark dataset of eight human genomes. HiRGC takes compress about 21 gigabytes of each set of the seven target genomes into 96-260 megabytes, achieving compression ratios of 217 to 82 times. This performance is at least 1.9 times better than the best competing algorithm on its best case. Our compression speed is also at least 2.9 times faster. HiRGC is stable and robust to deal with different reference genomes. In contrast, the competing methods' performance varies widely on different reference genomes. More experiments on 100 human genomes from the 1000 Genome Project and on genomes of several other species again demonstrate that HiRGC's performance is consistently excellent. The C ++ and Java source codes of our algorithm are freely available for academic and non-commercial use. They can be downloaded from https://github.com/yuansliu/HiRGC. jinyan.li@uts.edu.au. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Tailoring the Activity for Oxygen Evolution Electrocatalysis on Rutile TiO2(110) by Transition-Metal Substitution

DEFF Research Database (Denmark)

Garcia-Mota, Monica; Vojvodic, Aleksandra; Metiu, Horia

2011-01-01

The oxygen evolution reaction (OER) on the rutile M-TiO2(110) (M = V, Nb, Ta, Cr, Mo, W, Mn, Fe, Ru, Ir, Ni) surfaces was investigated by using density functional theory calculations. The stability of different doped TiO2 systems was analyzed. The scaling relationship between the binding energies...... of OER intermediates (HOO* versus HO*) is found to follow essentially the same trend as for undoped oxides. Our theoretical analysis shows a lower overpotential associated with OER on the doped M-TiO2(110) than on the undoped TiO2(110). The theoretical activity of Cr-, Mo-, Mn-, and Ir-doped TiO2...

Topotactic transition of α-Co(OH)2 to β-Co(OH)2 anchored on CoO nanoparticles during electrochemical water oxidation: synergistic electrocatalytic effects.

Science.gov (United States)

Kundu, Sumana; Malik, Bibhudatta; Prabhakaran, Amrutha; Pattanayak, Deepak K; Pillai, Vijayamohanan K

2017-08-29

Herein, we report a single step, anionic surfactant-assisted, low temperature-hydrothermal synthetic strategy of CoO nanoparticles anchored on β-Co(OH) 2 nanosheets which show a low overpotential (295 mV @ 10 mA cm -2 ) for the oxygen evolution reaction (OER). They also demonstrate much better kinetic parameters compared to the state-of-the-art RuO 2 . Interestingly, under the OER operational conditions (in alkaline medium), the topotactic transformation of α-Co(OH) 2 to a stable Brucite-like β-Co(OH) 2 phase leads to a synergistic interaction between the β-Co(OH) 2 sheets on the CoO nanoparticles for enhancing the OER electrocatalytic activity.

BOOK REVIEW OPEN EDUCATIONAL RESOURCES: Policy, Costs and Transformation

Directory of Open Access Journals (Sweden)

Can GULER

2016-10-01

Full Text Available This book presents 15 case studies contributed by researchers and policy makers. The Open Educational Resources (OER implementations are expressed through different point of views. This book focused on three themes: policy, costs and transformation. Policy theme is related to the establishment of priorities for supporting the decisions made by an institution or organization. Costs theme explores the funding of OER, particularly in the sense of cost effectiveness. Transformation theme provides examples that demonstrate how OER can be used in ways that go beyond replication of current teaching and learning models. The editors in the Introduction elaborately describe these three themes.

Carbon-Coated Perovskite BaMnO3 Porous Nanorods with Enhanced Electrocatalytic Perporites for Oxygen Reduction and Oxygen Evolution

International Nuclear Information System (INIS)

Xu, Yujiao; Tsou, Alvin; Fu, Yue; Wang, Jin; Tian, Jing-Hua; Yang, Ruizhi

2015-01-01

A thin carbon layer has been introduced to coat on the perovskite BaMnO 3 nanorods by a facile method, which exhibit significantly enhanced electrocatalytic activity for both the ORR and OER with excellent stability. - Highlights: • A non-rare-earth element based perovskite BaMnO 3 nanorods as an active electrocatalyst for the ORR and OER have been prepared and investigated for the first time. • A thin carbon-coating layer with thickness of approximately 10 nm has been successfully introduced to enhance the electrical conductivity and the electrocatalytic activities of the bare perovskite for both ORR and OER. • The stabilities of bare BaMnO 3 nanorods for both ORR and OER have also been improved dramatically with the help of carbon coating, especially for the OER process. - Abstract: Highly efficient, low-cost catalysts, especially with bifunctional electrocatalytic capabilities for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are vital for the wide commercialization of fuel cells and metal-air batteries. In this study, BaMnO 3 - a non-rare-earth element based perovskite nanorods have been prepared and investigated for the first time, and a thin carbon-coating with a thickness of approximately 10 nm has been successfully introduced to enhance the electrical conductivity of the bare perovskite. Electrochemical tests reveal that bare BaMnO 3 nanorods exhibit very good catalytic activity. More interestingly, a remarkably enhanced ORR activity for the perovskite BaMnO 3 nanorods was observed after coating with a thin layer of carbon, which dominated with a direct four-electron pathway. Meanwhile, the OER process has also been enhanced extraordinarily with the carbon-coating, reaching a maximum of 14.8 mA cm −2 at 1.0 V (vs. Ag/AgCl), which is far superior to both the bare BaMnO 3 nanorods and commercial Pt/C (20 wt%) catalysts. Furthermore, the stabilities of bare BaMnO 3 nanorods for both ORR and OER have also been improved

Early infant adipose deposition is positively associated with the n-6 to n-3 fatty acid ratio in human milk independent of maternal BMI.

Science.gov (United States)

Rudolph, M C; Young, B E; Lemas, D J; Palmer, C E; Hernandez, T L; Barbour, L A; Friedman, J E; Krebs, N F; MacLean, P S

2017-04-01

Excessive infant weight gain in the first 6-month of life is a powerful predictor of childhood obesity and related health risks. In mice, omega-6 fatty acids (FAs) serve as potent ligands driving adipogenesis during early development. The ratio of omega-6 relative to omega-3 (n-6/n-3) FA in human milk (HM) has increased threefold over the last 30 years, but the impact of this shift on infant adipose development remains undetermined. This study investigated how maternal obesity and maternal dietary FA (as reflected in maternal red blood cells (RBCs) composition) influenced HM n-6 and n-3 FAs, and whether the HM n-6/n-3 ratio was associated with changes in infant adipose deposition between 2 weeks and 4 months postpartum. Forty-eight infants from normal weight (NW), overweight (OW) and obese (OB) mothers were exclusively or predominantly breastfed over the first 4 months of lactation. Mid-feed HM and maternal RBC were collected at either transitional (2 weeks) or established (4 months) lactation, along with infant body composition assessed using air-displacement plethysmography. The FA composition of HM and maternal RBC was measured quantitatively by lipid mass spectrometry. In transitional and established HM, docosahexaenoic acid (DHA) was lower (P=0.008; 0.005) and the arachidonic acid (AA)/DHA+eicosapentaenoic acid (EPA) ratio was higher (P=0.05; 0.02) in the OB relative to the NW group. Maternal prepregnancy body mass index (BMI) and AA/DHA+EPA ratios in transitional and established HM were moderately correlated (P=0.018; 0.001). Total infant fat mass was increased in the upper AA/DHA+EPA tertile of established HM relative to the lower tertile (P=0.019). The amount of changes in infant fat mass and percentage of body fat were predicted by AA/EPA+DHA ratios in established HM (P=0.038; 0.010). Perinatal infant exposures to a high AA/EPA+DHA ratio during the first 4 months of life, which is primarily reflective of maternal dietary FA, may significantly contribute to

Accessibility of Open Educational Resources for Distance Education ...

African Journals Online (AJOL)

This paper investigated the accessibility of Open Educational Resources at. The Open University of Tanzania. Specifically, the study looked at staff and students' level of awareness on the types of OER available at OUT Library, access and use trends of OER by academic staff and students, challenges faced in accessing ...

Special Report on the Role of Open Educational Resources in Supporting the Sustainable Development Goal 4: Quality Education Challenges and Opportunities

Science.gov (United States)

McGreal, Rory

2017-01-01

Open Educational Resources (OER) and their offspring, Massive Open Online Courses (MOOCs), are becoming important factors in achieving the "Sustainable Development Goal 4: Quality Education" ("SDG4"). The OER movement is less than 15 years old and is growing rapidly as more and more nations and institutions adopt the view that…

Carbon-Encapsulated Co3O4@CoO@Co Nanocomposites for Multifunctional Applications in Enhanced Long-life Lithium Storage, Supercapacitor and Oxygen Evolution Reaction

International Nuclear Information System (INIS)

Xu, Dongyang; Mu, Congpu; Xiang, Jianyong; Wen, Fusheng; Su, Can; Hao, Chunxue; Hu, Wentao; Tang, Yongfu; Liu, Zhongyuan

2016-01-01

Porous nanostructure composites materials had attracted widely attention due to their potential application in energy storage (Lithium ion batteries (LIBs) and supercapacitor) and electrocatalyst of oxygen evolution reaction (OER). Co 3 O 4 @CoO@Co@C nanocomposites had been successfully synthesized using glucose as carbon source and cobalt nitrate as metalprecurs or of Co 3 O 4 @CoO@Co@C, which has excellent electrochemical performance for LIBs, supercapacitor and OER. Three kinds of morphology samples marked by Co 3 O 4 @CoO@Co@C-2/1, Co 3 O 4 @CoO@Co@C-1/1 and Co 3 O 4 @CoO@Co@C-1/2 are synthesized due to different atomic ratio of cobalt/carbon in precursors. Electrochemical and catalytic performance of Co 3 O 4 @CoO@Co@C-2/1 nanocomposites is more excellent than Co 3 O 4 @CoO@Co@C-1/1 and Co 3 O 4 @CoO@Co@C-1/2. Co 3 O 4 @CoO@Co@C-2/1 shows that discharge capacity can maintain 450 mA h g −1 and coulombic efficiency is nearly 100% during 500 cycles for LIBs. It indicates the excellent cycling stability of Co 3 O 4 @CoO@Co@C-2/1 as electrode for supercapacitor that about 78.3% of initial specific capacitance can be retained after 10000 cycles at current density of 2 A g −1 . Co 3 O 4 @CoO@Co@C-2/1 as catalyst of OER shows excellent electrochemical durability over 15 hours continuous experiment.

ZIF-67 incorporated with carbon derived from pomelo peels: A highly efficient bifunctional catalyst for oxygen reduction/evolution reactions

Energy Technology Data Exchange (ETDEWEB)

Wang, Hao; Yin, Feng-Xiang; Chen, Biao-Hua; He, Xiao-Bo; Lv, Peng-Liang; Ye, Cai-Yun; Liu, Di-Jia

2017-05-01

Developing carbon catalyst materials using natural, abundant and renewable resources as precursors plays an increasingly important role in clean energy generation and environmental protection. In this work, N-doped pomelo-peel-derived carbon (NPC) materials were prepared using a widely available food waste-pomelo peels and melamine. The synthetic NPC exhibits well-defined porosities and a highly doped-N content (e.g. 6.38 at% for NPC-2), therefore affords excellent oxygen reduction reaction (ORR) catalytic activities in alkaline electrolytes. NPC was further integrated with ZIF-67 to form ZIF-67@NPC hybrids through solvothermal reactions. The hybrid catalysts show substantially enhanced ORR catalytic activities comparable to that of commercial 20 wa Pt/C. Furthermore, the catalysts also exhibit excellent oxygen evolution reaction (OER) catalytic activities. Among all prepared ZIF-67@NPC hybrids, the optimal composition with ZIF-67 to NPC ratio of 2:1 exhibits the best ORR and OER bifunctional catalytic performance and the smallest Delta E (E-OER@10 mA cm(-2)-E-ORR@-1 mA cm(-2)) value of 0.79 V. The catalyst also demonstrated desirable 4-electron transfer pathways and superior catalytic stabilities. The Co-N-4 in ZIF-67, electrochemical active surface area, and the strong interactions between ZIF-67 and NPC are attributed as the main contributors to the bifunctional catalytic activities. These factors act synergistically, resulting in substantially enhanced bifunctional catalytic activities and stabilities; consequently, this hybrid catalyst is among the best of the reported bifunctional electrocatalysts and is promising for use in metal-air batteries and fuel cells. (C) 2016 Elsevier B.V. All rights reserved.

Sharpening Sharpe Ratios

OpenAIRE

William N. Goetzmann; Jonathan E. Ingersoll Jr.; Matthew I. Spiegel; Ivo Welch

2002-01-01

It is now well known that the Sharpe ratio and other related reward-to-risk measures may be manipulated with option-like strategies. In this paper we derive the general conditions for achieving the maximum expected Sharpe ratio. We derive static rules for achieving the maximum Sharpe ratio with two or more options, as well as a continuum of derivative contracts. The optimal strategy has a truncated right tail and a fat left tail. We also derive dynamic rules for increasing the Sharpe ratio. O...

Allometric scaling and cell ratios in multi-organ in vitro models of human metabolism

Directory of Open Access Journals (Sweden)

Nadia eUcciferri

2014-12-01

Full Text Available Intelligent in vitro models able to recapitulate the physiological interactions between tissues in the body have enormous potential as they enable detailed studies on specific two-way or higher order tissue communication. These models are the first step towards building an integrated picture of systemic metabolism and signalling in physiological or pathological conditions. However the rational design of in vitro models of cell-cell or cell-tissue interaction is difficult as quite often cell culture experiments are driven by the device used, rather than by design considerations. Indeed very little research has been carried out on in vitro models of metabolism connecting different cell or tissue types in a physiologically and metabolically relevant manner. Here we analyse the physiologic relationship between cells, cell metabolism and exchange in the human body using allometric rules, downscaling them to an organ-on-a plate device. In particular, in order to establish appropriate cell ratios in the system in a rational manner, two different allometric scaling models (Cell Number Scaling Model, CNSM, and Metabolic and Surface Scaling model, MSSM are proposed and applied to a two compartment model of hepatic-vascular metabolic cross-talk. The theoretical scaling studies illustrate that the design and hence relevance of multi-organ models is principally determined by experimental constraints. Two experimentally feasible model configurations are then implemented in a multi-compartment organ-on-a plate device. An analysis of the metabolic response of the two configurations demonstrates that their glucose and lipid balance is quite different, with only one of the two models recapitulating physiological-like homeostasis. In conclusion, not only do cross-talk and physical stimuli play an important role in in vitro models, but the numeric relationship between cells is also crucial to recreate in vitro interactions which can be extrapolated to the in vivo

Allometric Scaling and Cell Ratios in Multi-Organ in vitro Models of Human Metabolism

International Nuclear Information System (INIS)

Ucciferri, Nadia; Sbrana, Tommaso; Ahluwalia, Arti

2014-01-01

Intelligent in vitro models able to recapitulate the physiological interactions between tissues in the body have enormous potential as they enable detailed studies on specific two-way or higher order tissue communication. These models are the first step toward building an integrated picture of systemic metabolism and signaling in physiological or pathological conditions. However, the rational design of in vitro models of cell–cell or cell–tissue interaction is difficult as quite often cell culture experiments are driven by the device used, rather than by design considerations. Indeed, very little research has been carried out on in vitro models of metabolism connecting different cell or tissue types in a physiologically and metabolically relevant manner. Here, we analyze the physiological relationship between cells, cell metabolism, and exchange in the human body using allometric rules, downscaling them to an organ-on-a-plate device. In particular, in order to establish appropriate cell ratios in the system in a rational manner, two different allometric scaling models (cell number scaling model and metabolic and surface scaling model) are proposed and applied to a two compartment model of hepatic-vascular metabolic cross-talk. The theoretical scaling studies illustrate that the design and hence relevance of multi-organ models is principally determined by experimental constraints. Two experimentally feasible model configurations are then implemented in a multi-compartment organ-on-a-plate device. An analysis of the metabolic response of the two configurations demonstrates that their glucose and lipid balance is quite different, with only one of the two models recapitulating physiological-like homeostasis. In conclusion, not only do cross-talk and physical stimuli play an important role in in vitro models, but the numeric relationship between cells is also crucial to recreate in vitro interactions, which can be extrapolated to the in vivo reality.

Allometric Scaling and Cell Ratios in Multi-Organ in vitro Models of Human Metabolism

Energy Technology Data Exchange (ETDEWEB)

Ucciferri, Nadia [CNR Institute of Clinical Physiology, Pisa (Italy); Interdepartmental Research Center “E. Piaggio”, University of Pisa, Pisa (Italy); Sbrana, Tommaso [Interdepartmental Research Center “E. Piaggio”, University of Pisa, Pisa (Italy); Ahluwalia, Arti, E-mail: arti.ahluwalia@unipi.it [CNR Institute of Clinical Physiology, Pisa (Italy); Interdepartmental Research Center “E. Piaggio”, University of Pisa, Pisa (Italy)

2014-12-17

Intelligent in vitro models able to recapitulate the physiological interactions between tissues in the body have enormous potential as they enable detailed studies on specific two-way or higher order tissue communication. These models are the first step toward building an integrated picture of systemic metabolism and signaling in physiological or pathological conditions. However, the rational design of in vitro models of cell–cell or cell–tissue interaction is difficult as quite often cell culture experiments are driven by the device used, rather than by design considerations. Indeed, very little research has been carried out on in vitro models of metabolism connecting different cell or tissue types in a physiologically and metabolically relevant manner. Here, we analyze the physiological relationship between cells, cell metabolism, and exchange in the human body using allometric rules, downscaling them to an organ-on-a-plate device. In particular, in order to establish appropriate cell ratios in the system in a rational manner, two different allometric scaling models (cell number scaling model and metabolic and surface scaling model) are proposed and applied to a two compartment model of hepatic-vascular metabolic cross-talk. The theoretical scaling studies illustrate that the design and hence relevance of multi-organ models is principally determined by experimental constraints. Two experimentally feasible model configurations are then implemented in a multi-compartment organ-on-a-plate device. An analysis of the metabolic response of the two configurations demonstrates that their glucose and lipid balance is quite different, with only one of the two models recapitulating physiological-like homeostasis. In conclusion, not only do cross-talk and physical stimuli play an important role in in vitro models, but the numeric relationship between cells is also crucial to recreate in vitro interactions, which can be extrapolated to the in vivo reality.

Allometric Scaling and Cell Ratios in Multi-Organ in vitro Models of Human Metabolism.

Science.gov (United States)

Ucciferri, Nadia; Sbrana, Tommaso; Ahluwalia, Arti

2014-01-01

Intelligent in vitro models able to recapitulate the physiological interactions between tissues in the body have enormous potential as they enable detailed studies on specific two-way or higher order tissue communication. These models are the first step toward building an integrated picture of systemic metabolism and signaling in physiological or pathological conditions. However, the rational design of in vitro models of cell-cell or cell-tissue interaction is difficult as quite often cell culture experiments are driven by the device used, rather than by design considerations. Indeed, very little research has been carried out on in vitro models of metabolism connecting different cell or tissue types in a physiologically and metabolically relevant manner. Here, we analyze the physiological relationship between cells, cell metabolism, and exchange in the human body using allometric rules, downscaling them to an organ-on-a-plate device. In particular, in order to establish appropriate cell ratios in the system in a rational manner, two different allometric scaling models (cell number scaling model and metabolic and surface scaling model) are proposed and applied to a two compartment model of hepatic-vascular metabolic cross-talk. The theoretical scaling studies illustrate that the design and hence relevance of multi-organ models is principally determined by experimental constraints. Two experimentally feasible model configurations are then implemented in a multi-compartment organ-on-a-plate device. An analysis of the metabolic response of the two configurations demonstrates that their glucose and lipid balance is quite different, with only one of the two models recapitulating physiological-like homeostasis. In conclusion, not only do cross-talk and physical stimuli play an important role in in vitro models, but the numeric relationship between cells is also crucial to recreate in vitro interactions, which can be extrapolated to the in vivo reality.

Open Educational Resources: A Review of Attributes for Adoption in an Online Bachelor's Degree Program

Science.gov (United States)

Neely, Patricia; Tucker, Jan P.; Au, Angela

2016-01-01

As concerns about the skyrocketing costs of a college degree have converged with the increasing availability of open educational resources (OER), higher education administrators are asking faculty and curriculum designers to use OERs to design courses and programs. This case study explores the decision making process and outcomes of an online,…

Die uitbouing van die Bybelse kanon in antieke Judaïsme en die ...

African Journals Online (AJOL)

31 Jul 2015 ... die oer-Christelike boodskap tot by sy Ou Testamentiese wortels, die geskrifte van Israel wat cum grano salis die 'Bybel' van die oer-Christendom geword het en die blywende verwysingspunt van die Christelike boodskap is. Erkenning. Hierdie artikel is vertaal na Afrikaans deur Prof. Jan G. van der Watt.

A Federated Reference Structure for Open Informational Ecosystems

Science.gov (United States)

Heinen, Richard; Kerres, Michael; Scharnberg, Gianna; Blees, Ingo; Rittberger, Marc

2016-01-01

The paper describes the concept of a federated ecosystem for Open Educational Resources (OER) in the German education system. Here, a variety of OER repositories (ROER) (Muuß-Merholz & Schaumburg, 2014) and reference platforms have been established in the recent past. In order to develop this ecosystem, not only are metadata standards…

Open Educational Resources and the Transformation of Education

Science.gov (United States)

Tuomi, Ilkka

2013-01-01

The extremely rapid expansion of open educational resource (OER) initiatives and the millions of learners they attract can be understood as an indicator of an emerging revolution in education and learning. This article describes recent developments in this area and develops conceptual foundations for studies and policies on OER. We describe four…

Radioimmunodetection of human melanoma tumor xenografts with human monoclonal antibodies

International Nuclear Information System (INIS)

Gomibuchi, Makoto; Saxton, R.E.; Lake, R.R.; Katano, Mitsuo; Irie, R.F.

1986-01-01

A human IgM monoclonal antibody has been established that defines a tumor-associated membrane antigen expressed on human melanoma cells. The antigen has been identified as the ganglioside GD2. In this paper, the authors describe the potential usefulness of the human monoclonal antibody for radioimaging. Nude mice bearing tumors derived from a human melanoma cell line were used as a model. Antibody activity was degradated significantly after labeling with 131 I by the use of a modified chloramine-T method. After testing various concentrations, labeled antibody of a specific activity of 2.8μCi/μg produced the best results. Balb/c nude mice bearing a GD2-positive M14 melanoma cell line were injected with 10-30μg of labeled antibody, and its radiolocalization in different organs and in the whole body were evaluated. The best tumor image was obtained on Day 6. The labeled antibody uptake ratio between tumor and muscle was 9.2:1; the ratio between tumor and liver was 1.4:1. These studies represent the first report of experimental tumor imaging with human monoclonal antibody. Human monoclonals will probably prove to be superior reagents for tumor imaging in melanoma patients if the problem of anti-body radiolysis is resolved. (author)

Analysis of root surface properties by fluorescence/Raman intensity ratio.

Science.gov (United States)

Nakamura, Shino; Ando, Masahiro; Hamaguchi, Hiro-O; Yamamoto, Matsuo

2017-11-01

The aim of this study is to evaluate the existence of residual calculus on root surfaces by determining the fluorescence/Raman intensity ratio. Thirty-two extracted human teeth, partially covered with calculus on the root surface, were evaluated by using a portable Raman spectrophotometer, and a 785-nm, 100-mW laser was applied for fluorescence/Raman excitation. The collected spectra were normalized to the hydroxyapatite Raman band intensity at 960 cm -1 . Raman spectra were recorded from the same point after changing the focal distance of the laser and the target radiating angle. In seven teeth, the condition of calculus, cementum, and dentin were evaluated. In 25 teeth, we determined the fluorescence/Raman intensity ratio following three strokes of debridement. Raman spectra collected from the dentin, cementum, and calculus were different. After normalization, spectra values were constant. The fluorescence/Raman intensity ratio of calculus region showed significant differences compared to the cementum and dentin (p Raman intensity ratio decreased with calculus debridement. For this analysis, the delta value was defined as the difference between the values before and after three strokes, with the final 2 delta values close to zero, indicating a gradual asymptotic curve and the change in intensity ratio approximating that of individual constants. Fluorescence/Raman intensity ratio was effectively used to cancel the angle- and distance-dependent fluctuations of fluorescence collection efficiency during measurement. Changes in the fluorescence/Raman intensity ratio near zero suggested that cementum or dentin was exposed, and calculus removed.

Morphology and Structure Engineering in Nanofiber Reactor: Tubular Hierarchical Integrated Networks Composed of Dual Phase Octahedral CoMn2 O4 /Carbon Nanofibers for Water Oxidation.

Science.gov (United States)

Zhu, Han; Yu, Danni; Zhang, Songge; Chen, Jiawei; Wu, Wenbo; Wan, Meng; Wang, Lina; Zhang, Ming; Du, Mingliang

2017-07-01

1D hollow nanostructures combine the advantages of enhanced surface-to-volume ratio, short transport lengths, and efficient 1D electron transport, which can provide more design ideas for the preparation of highly active oxygen evolution (OER) electrocatalysts. A unique architecture of dual-phase octahedral CoMn 2 O 4 /carbon hollow nanofibers has been prepared via a two-step heat-treatment process including preoxidation treatment and Ostwald ripening process. The hollow and porous structures provide interior void spaces, large exposed surfaces, and high contact areas between the nanofibers and electrolyte and the morphology can be engineered by adjusting the heating conditions. Due to the intimate electrical and chemical coupling between the oxide nanocrystals and integrated carbon, the dual-phase octahedral CoMn 2 O 4 /carbon hollow nanofibers exhibit excellent OER activity with overpotentials of 337 mV at current density of 10 mA cm -2 and Tafel slope of 82 mV dec -1 . This approach will lead to the new perception of design issue for the nanoarchitecture with fine morphology, structures, and excellent electrocatalytic activity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modification of radiation-induced DNA lesions by oxygen

International Nuclear Information System (INIS)

Meyn, R.E.; Jenkins, W.T.

1984-01-01

The efficiency of DNA strand break production by radiation under aerated and hypoxic conditions was determined in CHO cells using the technique of alkaline elution. The resulting oxygen enhancement ratio was surprisingly high, 7.8. When the pH of the elution was increased from 12.1, the normally used pH, to 12.8, a substantial increase in the strand breaks produced in the hypoxic cells was observed, resulting in an OER of 4.8. This difference in susceptibility of DNA strand break detection as a function of pH suggested a difference in the type of lesions produced in DNA when irradiated under aerated and hypoxic conditions. Further experiments to examine the DNA-protein crosslinks produced by radiation suggested that the apparent lower level of strand breaks in hypoxic cells may be due to a higher level of DNA-protein crosslinks produced under hypoxic conditions. Thus, oxygen may not only act by modifying the quantity of radiation-induced DNA lesions but may also cause qualitative changes. If the different types of DNA lesions have different contributions to lethality, the OER for cell survival may represent a complex composite of these changes at the molecular level

Identifying Child-Staff Ratios That Promote Peer Skills in Child Care

Science.gov (United States)

Iluz, Reli; Adi-Japha, Esther; Klein, Pnina S.

2016-01-01

Research Findings: Early child care policy and practice are grounded in a growing understanding of the importance of the first years of life. In earlier studies, associations between child-staff ratios and peer skills yielded inconsistent findings. The current study used data from the National Institute of Child Health and Human Development Study…

Side-specific effect of yolk testosterone elevation on second-to-fourth digit ratio in a wild passerine

Science.gov (United States)

Nagy, Gergely; Blázi, György; Hegyi, Gergely; Török, János

2016-02-01

Second-to-fourth digit ratio is a widely investigated sexually dimorphic morphological trait in human studies and could reliably indicate the prenatal steroid environment. Conducting manipulative experiments to test this hypothesis comes up against ethical limits in humans. However, oviparous tetrapods may be excellent models to experimentally investigate the effects of prenatal steroids on offspring second-to-fourth digit ratio. In this field study, we injected collared flycatcher ( Ficedula albicollis) eggs with physiological doses of testosterone. Fledglings from eggs with elevated yolk testosterone, regardless of their sex, had longer second digits on their left feet than controls, while the fourth digit did not differ between groups. Therefore, second-to-fourth digit ratio was higher in the testosterone-injected group, but only on the left foot. This is the first study which shows experimentally that early testosterone exposure can affect second-to-fourth digit ratio in a wild population of a passerine bird.

Digit ratio predicts sense of direction in women.

Directory of Open Access Journals (Sweden)

Xiaoqian J Chai

Full Text Available The relative length of the second-to-fourth digits (2D:4D has been linked with prenatal androgen in humans. The 2D:4D is sexually dimorphic, with lower values in males than females, and appears to correlate with diverse measures of behavior. However, the relationship between digit ratio and cognition, and spatial cognition in particular, has produced mixed results. In the present study, we hypothesized that spatial tasks separating cue conditions that either favored female or male strategies would examine this structure-function correlation with greater precision. Previous work suggests that males are better in the use of directional cues than females. In the present study, participants learned a target location in a virtual landscape environment, in conditions that contained either all directional (i.e., distant or compass bearing cues, or all positional (i.e., local, small objects cues. After a short delay, participants navigated back to the target location from a novel starting location. Males had higher accuracy in initial search direction than females in environments with all directional cues. Lower digit ratio was correlated with higher accuracy of initial search direction in females in environments with all directional cues. Mental rotation scores did not correlate with digit ratio in either males or females. These results demonstrate for the first time that a sex difference in the use of directional cues, i.e., the sense of direction, is associated with more male-like digit ratio.

Digit ratio predicts sense of direction in women.

Science.gov (United States)

Chai, Xiaoqian J; Jacobs, Lucia F

2012-01-01

The relative length of the second-to-fourth digits (2D:4D) has been linked with prenatal androgen in humans. The 2D:4D is sexually dimorphic, with lower values in males than females, and appears to correlate with diverse measures of behavior. However, the relationship between digit ratio and cognition, and spatial cognition in particular, has produced mixed results. In the present study, we hypothesized that spatial tasks separating cue conditions that either favored female or male strategies would examine this structure-function correlation with greater precision. Previous work suggests that males are better in the use of directional cues than females. In the present study, participants learned a target location in a virtual landscape environment, in conditions that contained either all directional (i.e., distant or compass bearing) cues, or all positional (i.e., local, small objects) cues. After a short delay, participants navigated back to the target location from a novel starting location. Males had higher accuracy in initial search direction than females in environments with all directional cues. Lower digit ratio was correlated with higher accuracy of initial search direction in females in environments with all directional cues. Mental rotation scores did not correlate with digit ratio in either males or females. These results demonstrate for the first time that a sex difference in the use of directional cues, i.e., the sense of direction, is associated with more male-like digit ratio.

Coping with unpredictability: dopaminergic and neurotrophic responses to omission of expected reward in Atlantic salmon (Salmo salar L..

Directory of Open Access Journals (Sweden)

Marco A Vindas

Full Text Available Comparative studies are imperative for understanding the evolution of adaptive neurobiological processes such as neural plasticity, cognition, and emotion. Previously we have reported that prolonged omission of expected rewards (OER, or 'frustrative nonreward' causes increased aggression in Atlantic salmon (Salmo salar. Here we report changes in brain monoaminergic activity and relative abundance of brain derived neurotrophic factor (BDNF and dopamine receptor mRNA transcripts in the same paradigm. Groups of fish were initially conditioned to associate a flashing light with feeding. Subsequently, the expected food reward was delayed for 30 minutes during two out of three meals per day in the OER treatment, while the previously established routine was maintained in control groups. After 8 days there was no effect of OER on baseline brain stem serotonin (5-HT or dopamine (DA activity. Subsequent exposure to acute confinement stress led to increased plasma cortisol and elevated turnover of brain stem DA and 5-HT in all animals. The DA response was potentiated and DA receptor 1 (D1 mRNA abundance was reduced in the OER-exposed fish, indicating a sensitization of the DA system. In addition OER suppressed abundance of BDNF in the telencephalon of non-stressed fish. Regardless of OER treatment, a strong positive correlation between BDNF and D1 mRNA abundance was seen in non-stressed fish. This correlation was disrupted by acute stress, and replaced by a negative correlation between BDNF abundance and plasma cortisol concentration. These observations indicate a conserved link between DA, neurotrophin regulation, and corticosteroid-signaling pathways. The results also emphasize how fish models can be important tools in the study of neural plasticity and responsiveness to environmental unpredictability.

Open Educational Resources in Canada 2015

Science.gov (United States)

McGreal, Rory; Anderson, Terry; Conrad, Dianne

2015-01-01

Canada's important areas of expertise in open educational resources (OER) are beginning to be built upon or replicated more broadly in all education and training sectors. This paper provides an overview of the state of the art in OER initiatives and open higher education in general in Canada, providing insights into what is happening nationally…

There Is No Business Model for Open Educational Resources: A Business Model Approach

Science.gov (United States)

de Langen, Frank

2011-01-01

The economic proverb "There is no such thing such as a free lunch" applies also to open educational resources (OER). In recent years, several authors have used revenue models and business models to analyse the different sources of possible funding for OER. In this article the business models of Osterwalder and Chesbrough are combined…

OERScout Technology Framework: A Novel Approach to Open Educational Resources Search

Science.gov (United States)

Abeywardena, Ishan Sudeera; Chan, Chee Seng; Tham, Choy Yoong

2013-01-01

The open educational resources (OER) movement has gained momentum in the past few years. With this new drive towards making knowledge open and accessible, a large number of OER repositories have been established and made available online throughout the world. However, the inability of existing search engines such as Google, Yahoo!, and Bing to…

Prevalence ratio of HTLV-1 in nursing mothers from the state of Paraiba, Northeastern Brazil.

Science.gov (United States)

Pimenta, Flávia C F; Kashima Haddad, Simone; de Medeiros Filho, João G; Costa, Maria José C; Diniz, Margareth F M; Fernandes, Melina P; de Araújo, Lenisio B; Pombo-de-Oliveira, Maria S

2008-08-01

The human T-cell lymphotropic virus type 1 (HTLV-1) was the first human retrovirus known as a direct causal agent of a malignant disease. The vertical route of HTLV transmission is the most frequent pathway of the virus contamination. This study was performed to determine the prevalence ratio of HTLV-1 infection among nursing women. From January 2004 to January 2005, blood samples from 1033 nursing mothers from Paraíba, Brazil were evaluated for HTLV antibodies by ELISA and HTLV-1 viral particles confirmed by polymerase chain reaction (PCR). HTLV antibodies were detected in 7 women. The overall seroprevalence ratio was 0.68% and HTLV-1 viral sequences were confirmed by PCR in 2 women. These preliminary data suggest that HTLV screening should be introduced as a mandatory test before breastfeeding and breast milk donation in Paraíba, Brazil. Additionally, counseling programs would help reduce the prevalence ratio of HTLV-1 infected individuals in this Brazilian region.

Cations in Octahedral Sites: A Descriptor for Oxygen Electrocatalysis on Transition-Metal Spinels

Energy Technology Data Exchange (ETDEWEB)

Wei, Chao; Feng, Zhenxing; Scherer, Günther G.; Barber, James; Shao-Horn, Yang; Xu, Zhichuan J. (Nanyang); (ICL); (Oregon State U.); (TUM-CREATE); (MIT)

2017-04-10

Exploring efficient and low-cost electrocatalysts for the oxygen-reduction reaction (ORR) and oxygen-evolution reaction (OER) is critical for developing renewable energy technologies such as fuel cells, metal–air batteries, and water electrolyzers. A rational design of a catalyst can be guided by identifying descriptors that determine its activity. Here, a descriptor study on the ORR/OER of spinel oxides is presented. With a series of MnCo2O4, the Mn in octahedral sites is identified as an active site. This finding is then applied to successfully explain the ORR/OER activities of other transition-metal spinels, including MnxCo3-xO4 (x = 2, 2.5, 3), LixMn2O4 (x = 0.7, 1), XCo2O4 (X = Co, Ni, Zn), and XFe2O4 (X = Mn, Co, Ni). A general principle is concluded that the eg occupancy of the active cation in the octahedral site is the activity descriptor for the ORR/OER of spinels, consolidating the role of electron orbital filling in metal oxide catalysis.

MOOCs, Open educational resources and social networking: bridging the gap between informal and formal learning//MOOC, recursos de educación abierto y redes sociales: acortando la distancia entre aprendizaje informal y formal

Directory of Open Access Journals (Sweden)

Niall Sclater

2016-07-01

Full Text Available MOOCs and open educational resources (OER provide a wealth of learning opportunities for people around the globe, many of whom have no access to formal higher education. OER are often difficult to locate and are accessed on their own without support from or dialogue with subject experts and peers. This paper looks at whether it is possible to develop effective learning communities around OER and whether these communities can emerge spontaneously and in a self-organised way without moderation. It examines the complex interplay between formal and informal learning, and examines whether MOOCs are the answer to providing effective interaction and dialogue for those wishing to study at university level for free on the Internet.

MODELING AND FORECASTING THE GROSS ENROLLMENT RATIO IN ROMANIAN PRIMARY SCHOOL

Directory of Open Access Journals (Sweden)

MARINOIU CRISTIAN

2014-06-01

Full Text Available The gross enrollment ratio in primary school is one of the basic indicators used in order to evaluate the proposed objectives of the educational system. Knowing its evolution allows a more rigorous substantiation of the strategies and of the human resources politics not only from the educational field but also from the economic one. In this paper we propose an econometric model in order to describe the gross enrollment ratio in Romanian primary school and we achieve its prediction for the next years, having as a guide the Box-Jenkins’s methodology. The obtained results indicate the continuous decrease of this rate for the next years.

Real-Time Counting People in Crowded Areas by Using Local Empirical Templates and Density Ratios

Science.gov (United States)

Hung, Dao-Huu; Hsu, Gee-Sern; Chung, Sheng-Luen; Saito, Hideo

In this paper, a fast and automated method of counting pedestrians in crowded areas is proposed along with three contributions. We firstly propose Local Empirical Templates (LET), which are able to outline the foregrounds, typically made by single pedestrians in a scene. LET are extracted by clustering foregrounds of single pedestrians with similar features in silhouettes. This process is done automatically for unknown scenes. Secondly, comparing the size of group foreground made by a group of pedestrians to that of appropriate LET captured in the same image patch with the group foreground produces the density ratio. Because of the local scale normalization between sizes, the density ratio appears to have a bound closely related to the number of pedestrians who induce the group foreground. Finally, to extract the bounds of density ratios for groups of different number of pedestrians, we propose a 3D human models based simulation in which camera viewpoints and pedestrians' proximity are easily manipulated. We collect hundreds of typical occluded-people patterns with distinct degrees of human proximity and under a variety of camera viewpoints. Distributions of density ratios with respect to the number of pedestrians are built based on the computed density ratios of these patterns for extracting density ratio bounds. The simulation is performed in the offline learning phase to extract the bounds from the distributions, which are used to count pedestrians in online settings. We reveal that the bounds seem to be invariant to camera viewpoints and humans' proximity. The performance of our proposed method is evaluated with our collected videos and PETS 2009's datasets. For our collected videos with the resolution of 320x240, our method runs in real-time with good accuracy and frame rate of around 30 fps, and consumes a small amount of computing resources. For PETS 2009's datasets, our proposed method achieves competitive results with other methods tested on the same

Tracking the Money for Open Educational Resources in South African Basic Education: What We Don't Know

Science.gov (United States)

Goodier, Sarah

2017-01-01

Limited research has been done to date on the extent of public funding of Open Educational Resources (OER) within basic education (K-12 equivalent) in South Africa. As claims have been made about the potential cost reductions that come with using OER, this study aimed to establish a benchmark of public spending on educational resources, uncover…

Mass Customization of Education by an Institution of HE: What Can We Learn from Industry?

Science.gov (United States)

Schuwer, Robert; Kusters, Rob

2014-01-01

One of the claims the OER movement makes is that availability of (open) digital learning materials improves the quality of education. The promise is the ability to offer educational programs that take into account specific demands of the learner. The question is how to reach a situation where a customized demand can be met using OER with…

Mortality, fertility, and the OY ratio in a model hunter-gatherer system.

Science.gov (United States)

White, Andrew A

2014-06-01

An agent-based model (ABM) is used to explore how the ratio of old to young adults (the OY ratio) in a sample of dead individuals is related to aspects of mortality, fertility, and longevity experienced by the living population from which the sample was drawn. The ABM features representations of rules, behaviors, and constraints that affect person- and household-level decisions about marriage, reproduction, and infant mortality in hunter-gatherer systems. The demographic characteristics of the larger model system emerge through human-level interactions playing out in the context of "global" parameters that can be adjusted to produce a range of mortality and fertility conditions. Model data show a relationship between the OY ratios of living populations (the living OY ratio) and assemblages of dead individuals drawn from those populations (the dead OY ratio) that is consistent with that from empirically known ethnographic hunter-gatherer cases. The dead OY ratio is clearly related to the mean ages, mean adult mortality rates, and mean total fertility rates experienced by living populations in the model. Sample size exerts a strong effect on the accuracy with which the calculated dead OY ratio reflects the actual dead OY ratio of the complete assemblage. These results demonstrate that the dead OY ratio is a potentially useful metric for paleodemographic analysis of changes in mortality and mean age, and suggest that, in general, hunter-gatherer populations with higher mortality, higher fertility, and lower mean ages are characterized by lower dead OY ratios. Copyright © 2014 Wiley Periodicals, Inc.

Mother's occupation and sex ratio at birth

Directory of Open Access Journals (Sweden)

Amiot Volodymyr

2010-05-01

Full Text Available Abstract Background Many women are working outside of the home, occupying a multitude of jobs with varying degrees of responsibilities and levels of psychological stress. We investigated whether different job types in women are associated with child sex at birth, with the hypothesis that women in job types, which are categorized as "high psychological stress" jobs, would be more likely to give birth to a daughter than a son, as females are less vulnerable to unfavourable conditions during conception, pregnancy and after parturition, and are less costly to carry to term. Methods We investigated the effects of mother's age, maternal and paternal job type (and associated psychological stress levels and paternal income on sex ratio at birth. Our analyses were based on 16,384 incidences of birth from a six-year (2000 to 2005 inclusive childbirth dataset from Addenbrooke's Hospital in Cambridge, UK. We obtained a restricted data set from Addenbrooke's hospital with: maternal age, maternal and paternal occupations, and whether or not the child was first-born. Results Women in job types that were categorized as "high stress" were more likely to give birth to daughters, whereas women in job types that were categorized as "low stress" had equal sex ratios or a slight male bias in offspring. We also investigated whether maternal age, and her partner's income could be associated with reversed offspring sex ratio. We found no association between mother's age, her partner's job stress category or partner income on child sex. However, there was an important interaction between job stress category and partner income in some of the analyses. Partner income appears to attenuate the association between maternal job stress and sex ratios at moderate-income levels, and reverse it at high-income levels. Conclusions To our knowledge this is the first report on the association between women's job type stress categories and offspring sex ratio in humans, and the

Sex-ratio biasing towards daughters among lower-ranking co-wives in Rwanda

NARCIS (Netherlands)

Pollet, Thomas V.; Fawcett, Tim W.; Buunk, Abraham P.; Nettle, Daniel

2009-01-01

There is considerable debate as to whether human females bias the sex ratio of their offspring as a function of their own condition. We apply the Trivers-Willard prediction-that mothers in poor condition will overproduce daughters-to a novel measure of condition, namely wife rank within a polygynous

Non-selective beta-adrenergic blockade prevents reduction of the cerebral metabolic ratio during exhaustive exercise in humans

DEFF Research Database (Denmark)

Larsen, T.S.; Rasmussen, P.; Overgaard, M.

2008-01-01

Intense exercise decreases the cerebral metabolic ratio of oxygen to carbohydrates [O(2)/(glucose + (1/2)lactate)], but whether this ratio is influenced by adrenergic stimulation is not known. In eight males, incremental cycle ergometry increased arterial lactate to 15.3 +/- 4.2 mm (mean +/- s.......d.) and the arterial-jugular venous (a-v) difference from -0.02 +/- 0.03 mm at rest to 1.0 +/- 0.5 mm (P cerebral metabolic ratio decreased from 5.5 +/- 1.4 to 3.0 +/- 0.3 (P ... of a non-selective beta-adrenergic (beta(1) + beta(2)) receptor antagonist (propranolol) reduced heart rate (69 +/- 8 to 58 +/- 6 beats min(-1)) and exercise capacity (239 +/- 42 to 209 +/- 31 W; P

Pretargeting vs. direct targeting of human betalox5 islet cells subcutaneously implanted in mice using an anti-human islet cell antibody

International Nuclear Information System (INIS)

Liu Guozheng; Dou Shuping; Akalin, Ali; Rusckowski, Mary; Streeter, Philip R.; Shultz, Leonard D.; Greiner, Dale L.

2012-01-01

Introduction: We previously demonstrated MORF/cMORF pretargeting of human islets and betalox 5 cells (a human beta cell line) transplanted subcutaneously in mice with the anti-human islet antibody, HPi1. We now compare pretargeting with direct targeting in the beta cell transplant model to evaluate the degree to which target/non-target (T/NT) ratios may be improved by pretargeting. Methods: Specific binding of an anti-human islet antibody HPi1 to the beta cells transplanted subcutaneously in mice was examined against a negative control antibody. We then compared pretargeting by MORF-HPi1 plus 111 In-labeled cMORF to direct targeting by 111 In-labeled HPi1. Results: HPi1 binding to betalox5 human cells in the transplant was shown by immunofluorescence. Normal organ 111 In backgrounds by pretargeting were always lower, although target accumulations were similar. More importantly, the transplant to pancreas and liver ratios was, respectively, 26 and 10 by pretargeting as compared to 9 and 0.6 by direct targeting. Conclusions: Pretargeting greatly improves the T/NT ratios, and based on the estimated endocrine to exocrine ratio within a pancreas, pretargeting may be approaching the sensitivity required for successful imaging of human islets within this organ.

Child Labour and Inequality

OpenAIRE

D'Alessandro, Simone; Fioroni, Tamara

2011-01-01

This paper focuses on the evolution of child labour, fertility and human capital in an economy characterized by two type of individuals, low and high skilled workers. This heterogeneity allows for an endogenous analysis of inequality generated by child labour. More specifically, according to empirical evidence, we oer an explanation for the emergence of a vicious cycle between child labour and inequality. The basic intuition behind this result is the interdependence between child labour and f...

Freestanding eggshell membrane-based electrodes for high-performance supercapacitors and oxygen evolution reaction

Science.gov (United States)

Geng, Jing; Wu, Hao; Al-Enizi, Abdullah M.; Elzatahry, Ahmed A.; Zheng, Gengfeng

2015-08-01

A type of freestanding, light-weight eggshell membrane-based electrode is demonstrated for supercapacitors and for oxygen evolution reaction (OER) catalysis. As a widely available daily waste, eggshell membranes have unique porous three-dimensional grid-like fibrous structures with relatively high surface area and abundant macropores, allowing for effective conjugation of carbon nanotubes and growth of NiCo2O4 nanowire arrays, an effective supercapacitor material and OER catalyst. The three-dimensional fibrous eggshell membrane frameworks with carbon nanotubes offer efficient pathways for charge transport, and the macropores between adjacent fibers are fully accessible for electrolytes and bubble evolution. As a supercapacitor, the eggshell membrane/carbon nanotube/NiCo2O4 electrode shows high specific capacitances at current densities from 1 to 20 A g-1, with excellent capacitance retention (>90%) at 10 A g-1 for over 10 000 cycles. When employed as an OER catalyst, this eggshell membrane-based electrode exhibits an OER onset potential of 1.53 V vs. the reversible hydrogen electrode (RHE), and a stable catalytic current density of 20 mA cm-2 at 1.65 V vs. the RHE.A type of freestanding, light-weight eggshell membrane-based electrode is demonstrated for supercapacitors and for oxygen evolution reaction (OER) catalysis. As a widely available daily waste, eggshell membranes have unique porous three-dimensional grid-like fibrous structures with relatively high surface area and abundant macropores, allowing for effective conjugation of carbon nanotubes and growth of NiCo2O4 nanowire arrays, an effective supercapacitor material and OER catalyst. The three-dimensional fibrous eggshell membrane frameworks with carbon nanotubes offer efficient pathways for charge transport, and the macropores between adjacent fibers are fully accessible for electrolytes and bubble evolution. As a supercapacitor, the eggshell membrane/carbon nanotube/NiCo2O4 electrode shows high specific

The Prestudy for Studying Inorganic Nutrient Metabolism in Humans : the Aplication of ICP-MS for Determination of Stable Isotope Ratio of Fe and Zn

International Nuclear Information System (INIS)

Rukihati; Sumadjo

2001-01-01

A method is described for the determination of isotope ratio of Fe and Zn by means of inductively coupled plasma-mass spectrometry (ICP-MS). The mass spectrometer was operated in low resolution mode to provide maximal sensitivity. Typical conditions for operations were: plasma power 0.85 k W, reflected power 56 Fe/ 54 Fe, 57 Fe/ 54 Fe, 58 Fe/ 54 Fe, dan 64 Zn/ 67 Zn, 66 Zn/ 67 Zn, 68 Zn/ 67 Zn, 70 Zn/ 67 Zn measured by ICP-MS showed a good level of agreement with TIMS (thermal ionization mass spectrometry). This method was prepared for studying the absorption and/or metabolism of inorganic nutrients in humans. (author)

Testosterone Administration Moderates Effect of Social Environment on Trust in Women Depending on Second-to-Fourth Digit Ratio.

Science.gov (United States)

Buskens, Vincent; Raub, Werner; van Miltenburg, Nynke; Montoya, Estrella R; van Honk, Jack

2016-06-10

Animal research has established that effects of hormones on social behaviour depend on characteristics of both individual and environment. Insight from research on humans into this interdependence is limited, though. Specifically, hardly any prior testosterone experiments in humans scrutinized the interdependency of testosterone with the social environment. Nonetheless, recent testosterone administration studies in humans repeatedly show that a proxy for individuals' prenatal testosterone-to-estradiol ratio, second-to-fourth digit-ratio (2D:4D ratio), influences effects of testosterone administration on human social behaviour. Here, we systematically vary the characteristics of the social environment and show that, depending on prenatal sex hormone priming, testosterone administration in women moderates the effect of the social environment on trust. We use the economic trust game and compare one-shot games modelling trust problems in relations between strangers with repeated games modelling trust problems in ongoing relations between partners. As expected, subjects are more trustful in repeated than in one-shot games. In subjects prenatally relatively highly primed by testosterone, however, this effect disappears after testosterone administration. We argue that impairments in cognitive empathy may reduce the repeated game effect on trust after testosterone administration in subjects with relatively high prenatal testosterone exposure and propose a neurobiological explanation for this effect.

Non-Fermi Liquids as Highly Active Oxygen Evolution Reaction Catalysts.

Science.gov (United States)

Hirai, Shigeto; Yagi, Shunsuke; Chen, Wei-Tin; Chou, Fang-Cheng; Okazaki, Noriyasu; Ohno, Tomoya; Suzuki, Hisao; Matsuda, Takeshi

2017-10-01

The oxygen evolution reaction (OER) plays a key role in emerging energy conversion technologies such as rechargeable metal-air batteries, and direct solar water splitting. Herein, a remarkably low overpotential of ≈150 mV at 10 mA cm -2 disk in alkaline solutions using one of the non-Fermi liquids, Hg 2 Ru 2 O 7 , is reported. Hg 2 Ru 2 O 7 displays a rapid increase in current density and excellent durability as an OER catalyst. This outstanding catalytic performance is realized through the coexistence of localized d-bands with the metallic state that is unique to non-Fermi liquids. The findings indicate that non-Fermi liquids could greatly improve the design of highly active OER catalysts.

Developing and Using Open Education Resources to Support Teacher Education in Africa

Directory of Open Access Journals (Sweden)

Christopher B. Mugimu

2010-12-01

Full Text Available This article presents findings of action research during the creation and dissemination process of open education resources (OERs to support pre-service and in-service teachers in Uganda and other African countries. It highlights the perceptions of teachers and the authoring team of the impact of their involvement in materials creation and dissemination on their practice and professional growth. It also presents lessons learned during the development and implementation process and the best practices for replicating this outreach program in Uganda and beyond. This article also shares insights into how the OERs can boost or contribute to effective teaching and learning especially in under-resourced school situations in Africa, and also shares experiences on best practices on creating the authoring team of OERs.

A Permselective CeOx Coating Improves the Stability of Oxygen Evolution Electrocatalysts

KAUST Repository

Obata, Keisuke

2017-12-05

Highly active NiFeOx electrocatalysts for the oxygen evolution reaction (OER) suffer gradual deactivation with time due to the loss of Fe species from the active sites into solution during catalysis. Here, we describe the anodic deposition of a CeOx layer that prevents the loss of such Fe species from the OER catalysts, achieving a highly stable performance. The CeOx layer does not affect the OER activity of the catalyst underneath but exhibits unique permselectivity, allowing the permeation of OH- and O2 through while preventing the diffusion of redox ions through the layer to function as a selective O2-evolving electrode. The use of such permselective protective layer provides a new strategy for improving the durability of electrocatalysts.

A Permselective CeOx Coating Improves the Stability of Oxygen Evolution Electrocatalysts

KAUST Repository

Obata, Keisuke; Takanabe, Kazuhiro

2017-01-01

Highly active NiFeOx electrocatalysts for the oxygen evolution reaction (OER) suffer gradual deactivation with time due to the loss of Fe species from the active sites into solution during catalysis. Here, we describe the anodic deposition of a CeOx layer that prevents the loss of such Fe species from the OER catalysts, achieving a highly stable performance. The CeOx layer does not affect the OER activity of the catalyst underneath but exhibits unique permselectivity, allowing the permeation of OH- and O2 through while preventing the diffusion of redox ions through the layer to function as a selective O2-evolving electrode. The use of such permselective protective layer provides a new strategy for improving the durability of electrocatalysts.

Free-standing ternary NiWP film for efficient water oxidation reaction

Science.gov (United States)

Yang, Yunpeng; Zhou, Kuo; Ma, Lili; Liang, Yanqin; Yang, Xianjin; Cui, Zhenduo; Zhu, Shengli; Li, Zhaoyang

2018-03-01

High-efficient catalysts for oxygen evolution reaction (OER) is of great concern in improving energy efficiency for water splitting. Here we report a high-performance OER electrocatalyst of nickel-tungsten-phosphorus (NiWP) film prepared by template method. This free-standing ternary electrocatalyst exhibits a remarkable electrocatalytic activity of OER in alkaline medium due to the synergetic effect among these elements and the good electrical conductivity. The reported NiWP composite catalyst has an overpotential of as low as 0.4 V (vs. RHE) at 30 mA cm-2, better than that of the commercial RuO2 catalyst. Moreover, a small charge transfer resistance of 4.06 Ω and a Tafel slope of 68 mV dec-1 demonstrate the outstanding catalytic activity.

X-Ray Microanalysis of Human Cementum

Science.gov (United States)

Alvarez-Pérez, Marco Antonio; Alvarez-Fregoso, Octavio; Ortiz-López, Jaime; Arzate, Higinio

2005-08-01

An energy dispersive x-ray microanalysis study was performed throughout the total length of cementum on five impacted human teeth. Mineral content of calcium, phosphorous, and magnesium were determined with an electron probe from the cemento-enamel junction to the root apex on the external surface of the cementum. The concentration profiles for calcium, phosphorous, and magnesium were compared by using Ca/P and Mg/Ca atomic percent ratio. Our findings demonstrated that the Ca/P ratio at the cemento-enamel junction showed the highest values (1.8 2.2). However, the area corresponding to the acellular extrinsic fiber cementum (AEFC) usually located on the coronal one-third of the root surface showed a Ca/P media value of 1.65. Nevertheless, on the area representing the fulcrum of the root there is an abrupt change in the Ca/P ratio, which decreases to 1.3. Our results revealed that Mg2+ distribution throughout the length of human cementum reached its maximum Mg/Ca ratio value of 1.3 1.4 at.% around the fulcrum of the root and an average value of 0.03%. A remarkable finding was that the Mg/Ca ratio pattern distribution showed that in the region where the Ca/P ratio showed a decreasing tendency, the Mg/Ca ratio reached its maximum value, showing a negative correlation. In conclusion, this study has established that clear compositional differences exist between AEFC and cellular mixed stratified cementum varieties and adds new knowledge about Mg2+ distribution and suggests its provocative role regulating human cementum metabolism.

MIR hollow waveguide (HWG) isotope ratio analyzer for environmental applications

Science.gov (United States)

Wang, Zhenyou; Zhuang, Yan; Deev, Andrei; Wu, Sheng

2017-05-01

An advanced commercial Mid-InfraRed Isotope Ratio (IR2) analyzer was developed in Arrow Grand Technologies based on hollow waveguide (HWG) as the sample tube. The stable carbon isotope ratio, i.e. δ13C, was obtained by measuring the selected CO2 absorption peaks in the MIR. Combined with a GC and a combustor, it has been successfully employed to measure compound specific δ13C isotope ratios in the field. By using both the 1- pass HWG and 5-path HWG, we are able to measure δ13C isotope ratio at a broad CO2 concentration of 300 ppm-37,500 ppm. Here, we demonstrate its applications in environmental studies. The δ13C isotope ratio and concentration of CO2 exhaled by soil samples was measured in real time with the isotope analyzer. The concentration was found to change with the time. We also convert the Dissolved Inorganic Carbon (DIC) into CO2, and then measure the δ13C isotope ratio with an accuracy of better than 0.3 ‰ (1 σ) with a 6 min test time and 1 ml sample usage. Tap water, NaHCO3 solvent, coca, and even beer were tested. Lastly, the 13C isotope ratio of CO2 exhaled by human beings was obtained <10 seconds after simply blowing the exhaled CO2 into a tube with an accuracy of 0.5‰ (1 σ) without sample preconditioning. In summary, a commercial HWG isotope analyzer was demonstrated to be able to perform environmental and health studies with a high accuracy ( 0.3 ‰/Hz1/2 1 σ), fast sampling rate (up to 10 Hz), low sample consumption ( 1 ml), and broad CO2 concentration range (300 ppm-37,500 ppm).

Effects of the differentiating agents sodium butyrate and N-methylformamide on the oxygen enhancement ratio of human colon tumor cells

International Nuclear Information System (INIS)

Hallows, K.R.; Bliven, S.F.; Leith, J.T.

1988-01-01

We have previously shown that chronic adaptation of human tumor cells to the differentiation-inducing agents N-methylformamide (NMF) and sodium butyrate (NAB) increases the sensitivity of oxic cells to graded single doses of X rays. These studies were carried out to define the sensitivity of hypoxic cells after adaptation. Clone A colon tumor cells were grown for three passages in medium containing 170 mM NMF or 2 mM NAB and irradiated in suspension culture, after gassing with either oxygen (60 min) or ultrapure nitrogen (90 min), and complete survival curves were generated. Using the linear-quadratic equation to describe the data, it was found that NMF and NAB produced increased X-ray killing of hypoxic cells. At the 10% level of survival, the dose-modifying factors were about 1.20 and 1.25 for NMF- and NAB-adapted hypoxic cells, respectively, as compared to hypoxic control cells. However, since both oxic and hypoxic cells exhibited increased sensitivity after NMF and NAB adaptation, there was no major change in the oxygen enhancement ratio

Intracellular thiol levels and radioresistance: Studies with glutathione and glutathione mono ethyl ester

International Nuclear Information System (INIS)

Astor, M.B.; Meister, A.; Anderson, M.E.

1987-01-01

Intracellular thiols such as glutathione (GSH) protect cells against free radicals formed during oxidative metabolism or from exposure to drugs or ionizing radiation. The role of intracellular GSH in the repair of radiation induced free radical damage was studied using GSH or its analog glutathione mono ethyl ester (GEE), which readily penetrates into the cell. Chinese hamster V79 cells with normal GSH levels were afforded equal protection under aerated and hypoxic conditions (DMF = 1.2 OER = 3.7) by both 10 mM GSH and GEE although GEE had raised interacellular GSH levels three-fold. Growth of V79 cells in cysteine free media resulted in undetectable levels of GSH and OER of 2.2 with no change in aerated survival. Restoration of intracellular GSH by 10 mM GEE resulted in an increase of the OER from 2.2. to 3.8 (DMF = 1.7). Only 14% of the intracellular GSH needs to be repleted to give an OER of 3.0. These experiments provide evidence that thiols do play a role in the oxygen effect and are present at levels in excess of what is necessary for maximal radioprotection

Freestanding eggshell membrane-based electrodes for high-performance supercapacitors and oxygen evolution reaction.

Science.gov (United States)

Geng, Jing; Wu, Hao; Al-Enizi, Abdullah M; Elzatahry, Ahmed A; Zheng, Gengfeng

2015-09-14

A type of freestanding, light-weight eggshell membrane-based electrode is demonstrated for supercapacitors and for oxygen evolution reaction (OER) catalysis. As a widely available daily waste, eggshell membranes have unique porous three-dimensional grid-like fibrous structures with relatively high surface area and abundant macropores, allowing for effective conjugation of carbon nanotubes and growth of NiCo2O4 nanowire arrays, an effective supercapacitor material and OER catalyst. The three-dimensional fibrous eggshell membrane frameworks with carbon nanotubes offer efficient pathways for charge transport, and the macropores between adjacent fibers are fully accessible for electrolytes and bubble evolution. As a supercapacitor, the eggshell membrane/carbon nanotube/NiCo2O4 electrode shows high specific capacitances at current densities from 1 to 20 A g(-1), with excellent capacitance retention (>90%) at 10 A g(-1) for over 10,000 cycles. When employed as an OER catalyst, this eggshell membrane-based electrode exhibits an OER onset potential of 1.53 V vs. the reversible hydrogen electrode (RHE), and a stable catalytic current density of 20 mA cm(-2) at 1.65 V vs. the RHE.

Ultrafine and highly disordered Ni 2 Fe 1 nanofoams enabled highly efficient oxygen evolution reaction in alkaline electrolyte

Energy Technology Data Exchange (ETDEWEB)

Fu, Shaofang; Song, Junhua; Zhu, Chengzhou; Xu, Gui-Liang; Amine, Khalil; Sun, Chengjun; Li, Xiaolin; Engelhard, Mark H.; Du, Dan; Lin, Yuehe

2018-02-01

Nickel iron hydroxides are the most promising non-noble electrocatalysts for oxygen evolution reaction (OER) in alkaline media. By in situ reduction of metal precursors, compositionally controlled three-dimensional (3D) NixFeyB nanofoams (NFs) are synthesized with high surface area and uniformly distributed bimetallic networks. The resultant ultrafine amorphous Ni2Fe1B NFs exhibit extraordinary electrocatalytic performance toward OER and overall water splitting in alkaline media. At a potential as low as 1.42 V (vs. RHE), Ni2Fe1B NFs can deliver a current density of 10 mA/cm2 and show negligible activity loss after 12 hours’ stability test. Even at large current flux of 100 mA/cm2, an ultralow overpotential of 0.27 V is achieved, which is about 0.18 V more negative than benchmark RuO2. Both ex-situ Mӧssbauer spectroscopy and X-ray Absorption Spectroscopy (XAS) reveal a phase separation and transformation for the Ni2Fe1B catalyst during OER process. The evolution of oxidation state and disordered structure of Ni2Fe1B might be a key to the high catalytic performance for OER.

Financial Key Ratios

OpenAIRE

Tănase Alin-Eliodor

2014-01-01

This article focuses on computing techniques starting from trial balance data regarding financial key ratios. There are presented activity, liquidity, solvency and profitability financial key ratios. It is presented a computing methodology in three steps based on a trial balance.

In Operando Self-Healing of Perovskite Electrocatalysts: A Case Study of SrCoO3 for the Oxygen Evolution Reaction

KAUST Repository

Tahini, Hassan A.; Tan, Xin; Schwingenschlö gl, Udo; Smith, Sean C.

2017-01-01

Perovskites are promising catalysts for oxygen evolution reactions (OER); among them, SrCoO3 is one of the best for these reactions. We study the O* intermediates and the role of surface oxygen vacancies of SrCoO3 during OER. A self-healing mechanism is proposed in which O* are incorporated into the surface to recover the redox capabilities of the material.

In Operando Self-Healing of Perovskite Electrocatalysts: A Case Study of SrCoO3 for the Oxygen Evolution Reaction

KAUST Repository

Tahini, Hassan A.

2017-01-24

Perovskites are promising catalysts for oxygen evolution reactions (OER); among them, SrCoO3 is one of the best for these reactions. We study the O* intermediates and the role of surface oxygen vacancies of SrCoO3 during OER. A self-healing mechanism is proposed in which O* are incorporated into the surface to recover the redox capabilities of the material.

Highly acid-durable carbon coated Co3O4 nanoarrays as efficient oxygen evolution electrocatalysts

KAUST Repository

Yang, Xiulin; Li, Henan; Lu, Ang-Yu; Min, Shixiong; Idriss, Zacharie; Hedhili, Mohamed N.; Huang, Kuo-Wei; Idriss, Hicham; Li, Lain-Jong

2016-01-01

Most oxygen evolution reaction (OER) electrocatalysts are not stable in corrosive acids. Even the expensive RuO2 or IrO2, the most acid-resistant oxides, can be dissolved at an oxidative potential. Herein, we realize that the failures of OER catalysts are mostly caused by the weak interface between catalysts and the substrates. Hence, the study of the interface structure between catalysts and substrates is critical. In this work, we observe that the cheap OER catalysts Co3O4 can be more durable than the state-of-the-art RuO2 if the interface quality is good enough. The Co3O4 nanosheets deposited on carbon paper (Co3O4/CP) is prepared by electroplating of Co-species and followed by a two-step calcination process. The 1st step occurs in vacuum in order to maintain the surface integrity of the carbon paper and converts Co-species to Co(II)O. The 2nd step is a calcination in ambient conditions which enables the complete transformation of Co(II)O to Co3O4 without degrading the mechanical strength of the Co3O4-CP interface. Equally important, an in situ formation of a layer of amorphous carbon on top of Co3O4 further enhances the OER catalyst stability. Therefore, these key advances make the Co3O4 catalyst highly active toward the OER in 0.5 M H2SO4 with a small overpotential (370 mV), to reach 10 mA/cm2. The observed long lifetime for 86.8 h at a constant current density of 100 mA/cm2, is among the best of the reported in literature so far, even longer than the state-of-art RuO2 on CP. Overall, our study provides a new insight and methodology for the construction of a high-performance and high stability OER electrocatalysts in corrosive acidic environments.

Highly acid-durable carbon coated Co3O4 nanoarrays as efficient oxygen evolution electrocatalysts

KAUST Repository

Yang, Xiulin

2016-04-21

Most oxygen evolution reaction (OER) electrocatalysts are not stable in corrosive acids. Even the expensive RuO2 or IrO2, the most acid-resistant oxides, can be dissolved at an oxidative potential. Herein, we realize that the failures of OER catalysts are mostly caused by the weak interface between catalysts and the substrates. Hence, the study of the interface structure between catalysts and substrates is critical. In this work, we observe that the cheap OER catalysts Co3O4 can be more durable than the state-of-the-art RuO2 if the interface quality is good enough. The Co3O4 nanosheets deposited on carbon paper (Co3O4/CP) is prepared by electroplating of Co-species and followed by a two-step calcination process. The 1st step occurs in vacuum in order to maintain the surface integrity of the carbon paper and converts Co-species to Co(II)O. The 2nd step is a calcination in ambient conditions which enables the complete transformation of Co(II)O to Co3O4 without degrading the mechanical strength of the Co3O4-CP interface. Equally important, an in situ formation of a layer of amorphous carbon on top of Co3O4 further enhances the OER catalyst stability. Therefore, these key advances make the Co3O4 catalyst highly active toward the OER in 0.5 M H2SO4 with a small overpotential (370 mV), to reach 10 mA/cm2. The observed long lifetime for 86.8 h at a constant current density of 100 mA/cm2, is among the best of the reported in literature so far, even longer than the state-of-art RuO2 on CP. Overall, our study provides a new insight and methodology for the construction of a high-performance and high stability OER electrocatalysts in corrosive acidic environments.

Nitrogen and sulfur co-doped graphene/carbon nanotube as metal-free electrocatalyst for oxygen evolution reaction: the enhanced performance by sulfur doping

International Nuclear Information System (INIS)

Zhao, Jujiao; Liu, Yanming; Quan, Xie; Chen, Shuo; Zhao, Huimin; Yu, Hongtao

2016-01-01

Highlights: • Metal-free 3D architecture N,S co-doped GR/CNT is prepared by a one-step method. • N,S co-doped GR/CNT exhibits good activity and stability for OER. • S doping is indicated beneficial for OER performance of metal-free catalysts. • The catalytic kinetics is highly correlated with the content of C-S-C structure. • 3D architecture composed of GR and CNT also contributes to the OER activity. - Abstract: Highly active metal-free electrocatalysts consisting of earth-abundant elements for oxygen evolution reaction (OER) are extremely desired for renewable energy technologies. Here we prepare the nitrogen and sulfur co-doped graphene/carbon nanotube (NS-GR/CNT) with 3D architecture by one-step hydrothermal method, which presents good performance for OER. The as-prepared NS-GR/CNT exhibits more negative onset potential and lower Tafel slope (0.56 V, 103 mV decade"−"1 vs. S.C.E. in 0.1 M KOH) compared to single N doped graphene/carbon nanotube (0.65 V, 285 mV decade"−"1), which indicates S doping can significantly enhance the OER performance. The X-ray photoelectron spectroscopy reveals that the thiophene-like S (C-S-C) is the dominant S species in all the S doped samples. NS-GR/CNT with C-S-C content of 0.26% has the Tafel slope of 151 mV decade"−"1 while the value for NS-GR/CNT with C-S-C content of 1.09% is 103 mV decade"−"1. The decreased Tafel slope demonstrates the catalytic kinetics are highly correlated with the content of C-S-C. Density functional theory calculations suggest that C-S-C may improve the catalytic kinetics by facilitating the adsorption of the OH"− intermediate. Besides, the 3D architecture composed of graphene and CNTs also contributes to the good performance and chronoamperometric measurement demonstrates the good durability of NS-GR/CNTs.

Are natural scientists more masculine than humanists? The association patterns between 2D:4D ratio and field of study.

Science.gov (United States)

Kainz, Sarah; Weitzer, Jacob; Zingale, Stefania; Köllner, Johanna; Albrecht, Cornelia; Gaidora, Angelika; Rudorfer, Marie-Theres; Nürnberger, Anna; Kirchengast, Sylvia

2018-06-11

Natural sciences are still considered as typical male fields, while humanities are interpreted as typical female topics. Economic, social but also biological factors are discussed to influence the choice of study field. In the present study, the impact of prenatal sex hormone exposure - estimated by 2D:4D ratio - on the choice of study field was analyzed. Two hundred Viennese students between the ages 18 and 28 years were enrolled. Lengths of the index finger and the ring finger were measured directly from the hand of the participants. 2D:4D ratios were calculated. Male and female students differed significantly in 2D:4D ratio. As expected, female students showed significantly higher 2D:4D ratios than their male counterparts ( p < 0.001). Male scientists and male humanists differed significantly in 2D:4D ratio. The 2D:4D of male humanists was significantly higher than that of scientists ( p = 0.037). Female scientists and female humanists however, did not differ significantly in 2D:4D ratio. Both showed a typical female 2D:4D ratio. This was also true of male humanists. Consequently low prenatal androgen exposure may be associated with the choice of humanities among male students.

Toxicity ratios: Their use and abuse in predicting the risk from induced cancer

International Nuclear Information System (INIS)

Mays, C.W.; Taylor, G.N.; Lloyd, R.D.

1986-01-01

The toxicity ratio concept assumes the validity of certain relationships. In some examples for bone sarcoma induction, the approximate toxicity of 239 Pu in man can be calculated algebraically from the observed toxicity in the radium-dial painters and the ratio of 239 Pu/ 226 Ra toxicities in suitable laboratory mammals. In a species highly susceptible to bone sarcoma induction, the risk coefficients for both 239 Pu and 226 Ra are elevated, but the toxicity ratio of 239 Pu to 226 Ra tends to be similar to the ratio in resistant species. Among the tested species the toxicity ratio of 239 Pu to 226 Ra ranged from 6 to 22 (a fourfold range), whereas their relative sensitivities to 239 Pu varied by a factor of 150. The toxicity ratio approach can also be used to estimate the actinide risk to man from liver cancer, by comparing to the Thorotrast patients; from lung cancer, by comparing to the uranium miners and the atomic-bomb survivors; and from neutron-induced cancers, by comparing to cancers induced by gamma rays. The toxicity ratio can be used to predict the risk to man from a specific type of cancer that has been reliably induced by a reference radiation in humans and that can be induced by both the reference and the investigated radiation in suitable laboratory animals. 26 refs., 3 figs., 1 tab

Free-standing, flexible β-Ni(OH)2/electrochemically-exfoliated graphene film electrode for efficient oxygen evolution

Science.gov (United States)

Wang, Lanlan; Zhang, Jian; Jiang, Weitao; Zhao, Hong; Liu, Hongzhong

2018-03-01

The oxidation of water into molecular oxygen (oxygen evolution reaction, OER) is a pivotal reaction in many energy conversion devices. The high cost of IrO2, however, seriously hinder its large-scale applications in water oxidation. Here, we have at first reported a free-standing and flexible film electrode consisting of 2D β-Ni(OH)2/electrochemically-exfoliated graphene hybrid nanosheets (NiG-2), which is synthesized by a solvothermal reaction and an assembly process. The as-obtained NiG-2 film electrode exhibited an excellent electrocatalytic OER activity with an extremely low OER onset overpotential of ∼250 mV in a 1 M KOH aqueous solution, which is lower than these of the commercial Ir/C (370 mV at 10 mA cm-2) catalyst.

Standardized morbidity ratio for leptospirosis mapping in Malaysia

Science.gov (United States)

Awang, Aznida Che; Samat, Nor Azah

2017-05-01

Leptospirosis is a worldwide zoonotic disease that affects human health in many parts of the world including Malaysia. Leptospirosis is a disease caused by the infection of pathogenic Leptospira genus called Spirochaetes. Leptospirosis can be transmitted directly or indirectly from rats to human. The human infection is usually caused by human contact with urine or tissues of infected animal. This disease can be spread through mucus membrane such as mouth, nose and eyes, ingestion of contaminated food and water and also exposed injured skin to contaminated water or soil. There is still no vaccine currently available for the prevention or treatment of leptospirosis disease but this disease can be treated if it is diagnosed early. Therefore, the aim of this study is to estimate the relative risk for leptospirosis disease based initially on the most common statistic used in the study of disease mapping called Standardized Morbidity Ratio (SMR). We then apply SMR to leptospirosis data obtained in Malaysia. The results show that the states of Melaka have very high risk areas. The states of Kedah, Terengganu and Kelantan are identified as high risk areas. The states of Perak, Perlis, Sabah and Sarawak showed medium risk areas. This is followed by low risk by other states except Pahang, Johor and Labuan with very low risk areas. In conclusion, SMR method is the best method for mapping leptospirosis because by referring to the relative risk maps, the states that deserve closer look and disease prevention can be identified.

Stable isotope ratios in hair and teeth reflect biologic rhythms.

Directory of Open Access Journals (Sweden)

Otto Appenzeller

Full Text Available Biologic rhythms give insight into normal physiology and disease. They can be used as biomarkers for neuronal degenerations. We present a diverse data set to show that hair and teeth contain an extended record of biologic rhythms, and that analysis of these tissues could yield signals of neurodegenerations. We examined hair from mummified humans from South America, extinct mammals and modern animals and people, both healthy and diseased, and teeth of hominins. We also monitored heart-rate variability, a measure of a biologic rhythm, in some living subjects and analyzed it using power spectra. The samples were examined to determine variations in stable isotope ratios along the length of the hair and across growth-lines of the enamel in teeth. We found recurring circa-annual periods of slow and fast rhythms in hydrogen isotope ratios in hair and carbon and oxygen isotope ratios in teeth. The power spectra contained slow and fast frequency power, matching, in terms of normalized frequency, the spectra of heart rate variability found in our living subjects. Analysis of the power spectra of hydrogen isotope ratios in hair from a patient with neurodegeneration revealed the same spectral features seen in the patient's heart-rate variability. Our study shows that spectral analysis of stable isotope ratios in readily available tissues such as hair could become a powerful diagnostic tool when effective treatments and neuroprotective drugs for neurodegenerative diseases become available. It also suggests that similar analyses of archaeological specimens could give insight into the physiology of ancient people and animals.

Effect of filling ratio on premixed methane/air explosion in an open-end pipe

Directory of Open Access Journals (Sweden)

Chang Guo

2016-06-01

Full Text Available The propagation characteristics of premixed methane/air explosion under different filling ratios (20%, 30%, 40%, 50%, 60%, and 100% were studied using an experimental system. The results indicate that the peak overpressure showed a decreasing trend at the initial stage but then showed an increasing trend until reaching its maximum value under different filling ratios. As the explosion propagated to the open end, the overpressure showed a downtrend. At this point, the flame speed initially increased along the pipe but then dropped dramatically. In addition, the explosion overpressure and flame speed increased with the increase of filling ratio. However, when the filling ratio reached 50%, the explosion overpressure and flame speed tended to be stable and the increase was not obvious. These results will be of great importance in evaluating the explosive damage to equipment and human personnel working in coal mines or other chemical industries.

Improved assessment of multiple sclerosis lesion segmentation agreement via detection and outline error estimates

Directory of Open Access Journals (Sweden)

Wack David S

2012-07-01

Full Text Available Abstract Background Presented is the method “Detection and Outline Error Estimates” (DOEE for assessing rater agreement in the delineation of multiple sclerosis (MS lesions. The DOEE method divides operator or rater assessment into two parts: 1 Detection Error (DE -- rater agreement in detecting the same regions to mark, and 2 Outline Error (OE -- agreement of the raters in outlining of the same lesion. Methods DE, OE and Similarity Index (SI values were calculated for two raters tested on a set of 17 fluid-attenuated inversion-recovery (FLAIR images of patients with MS. DE, OE, and SI values were tested for dependence with mean total area (MTA of the raters' Region of Interests (ROIs. Results When correlated with MTA, neither DE (ρ = .056, p=.83 nor the ratio of OE to MTA (ρ = .23, p=.37, referred to as Outline Error Rate (OER, exhibited significant correlation. In contrast, SI is found to be strongly correlated with MTA (ρ = .75, p  Conclusions The DE and OER indices are proposed as a better method than SI for comparing rater agreement of ROIs, which also provide specific information for raters to improve their agreement.

An Experimental Study of Muscle Coordination and Function during Human Locomotion

Directory of Open Access Journals (Sweden)

Hirai Hiroaki

2011-12-01

Full Text Available How humans solve the ill-posed problem of motor control is still a mystery. In this paper, we attempt to decompose human walking and running as the main movements of a leg into units of motor function. We introduce the key concept of “A-A ratio,” defined as the ratio of an extensor muscle’s electromyography (EMG signal to the sum of agonist and antagonist muscles’ EMG signals. Human walking and running are then decomposed into two units of motor function by applying Principal Component Analysis (PCA to the A-A ratio dataset. The kinematic meanings of these units are also experimentally shown by using a human-like musculoskeletal leg robot.

Correlation between the neutrophil-lymphocyte count ratio and bacterial infection in patient with human immunodeficiency virus

Science.gov (United States)

Kusnadi, D.; Liwang, M. N. I.; Katu, S.; Mubin, A. H.; Halim, R.

2018-03-01

Parameters for starting antibiotic therapy such as CRP andleukocytosis are considered non-specific. Previous studies have shown the Neutrophil-Lymphocyte Count Ratio (NLCR) can serve as the basis of bacterial infection, the level of infection, and the basis of antibiotic therapy. Compared with the Procalcitonin parameter, this NLCR is rapid, an inexpensive and requires no additional sampling. To determine the correlation between The Neutrophil-LymphocyteCount Ratio to bacterial infection in HIV patients. This study was a cross-sectional observational approach to HIV subject at Wahidin Sudirohusodo and Hasanuddin University Hospital. The subjects performed routine blood, microbiology test,and blood Procalcitonin levels tests. Then performed NLCR calculations based on routine blood results. The subjects then grouped the presence or absence of bacterial infection.In 146 study subjects, there were 78 (53.4%) with bacterial infections and 68 (46.6%) without bacterial infection as controls. Subjects with bacterial infections had higher total neutrophils (84.83) compared with non-bacterial infections. Subjects with bacterial infections had total lymphocytes with an average of 8.51 lower than non-bacterial infections. Subjects with bacterial infections had higher NLCR values with an average of 12.80. The Neutrophil-Lymphocyte Count Ratio can become a marker of bacterial infection in HIV patients.

The Emergy of Money Ratio of the United States from 1990 to 2007

Science.gov (United States)

The emergy to money ratio of a system is a key index used in emergy evaluations, because it represents the buying power of money and it can be used as an estimator of the average value of human service. Since both the material and energy inputs to societies and the money circulat...

Mid-Lift-to-Drag Ratio Rigid Vehicle Control System Design and Simulation for Human Mars Entry

Science.gov (United States)

Johnson, Breanna J.; Cerimele, Christopher J.; Stachowiak, Susan J.; Sostaric, Ronald R.; Matz, Daniel A.; Lu, Ping

2018-01-01

The Mid-Lift-to-Drag Ratio Rigid Vehicle (MRV) is a proposed candidate in the NASA Evolvable Mars Campaign's (EMC) Pathfinder Entry, Descent, and Landing (EDL) architecture study. The purpose of the study is to design a mission and vehicle capable of transporting a 20mt payload to the surface of Mars. The MRV is unique in its rigid, asymmetrical lifting-body shape which enables a higher lift-to-drag ratio (L/D) than the typical robotic Mars entry capsule vehicles that carry much less mass. This paper presents the formulation and six-degree-of-freedom (6DOF) performance of the MRV's control system, which uses both aerosurfaces and a propulsive reaction control system (RCS) to affect longitudinal and lateral directional behavior.

The complex dynamics of wishful thinking: the critical positivity ratio.

Science.gov (United States)

Brown, Nicholas J L; Sokal, Alan D; Friedman, Harris L

2013-12-01

We examine critically the claims made by Fredrickson and Losada (2005) concerning the construct known as the "positivity ratio." We find no theoretical or empirical justification for the use of differential equations drawn from fluid dynamics, a subfield of physics, to describe changes in human emotions over time; furthermore, we demonstrate that the purported application of these equations contains numerous fundamental conceptual and mathematical errors. The lack of relevance of these equations and their incorrect application lead us to conclude that Fredrickson and Losada's claim to have demonstrated the existence of a critical minimum positivity ratio of 2.9013 is entirely unfounded. More generally, we urge future researchers to exercise caution in the use of advanced mathematical tools, such as nonlinear dynamics, and in particular to verify that the elementary conditions for their valid application have been met. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Selenium: Mercury Molar Ratios in Freshwater Fish in the Columbia River Basin: Potential Applications for Specific Fish Consumption Advisories.

Science.gov (United States)

Cusack, Leanne K; Eagles-Smith, Collin; Harding, Anna K; Kile, Molly; Stone, Dave

2017-07-01

Fish provide a valuable source of beneficial nutrients and are an excellent source of low fat protein. However, fish are also the primary source of methylmercury exposure in humans. Selenium often co-occurs with mercury and there is some evidence that selenium can protect against mercury toxicity yet States issue fish consumption advisories based solely on the risks that methylmercury pose to human health. Recently, it has been suggested the selenium: mercury molar ratio be considered in risk management. In order for agencies to utilize the ratio to set consumption guidelines, it is important to evaluate the variability in selenium and mercury in different fish species. We examined 10 different freshwater fish species found within the Columbia River Basin in order to determine the inter- and intra-specific variability in the selenium: mercury molar ratios and the selenium health benefit values. We found significant variation in selenium: mercury molar ratios. The mean molar ratios for each species were all above 1:1, ranging from 3.42:1 in Walleye to 27.2:1 in Chinook salmon. There was a positive correlation between both mercury and selenium with length for each fish species apart from yellow perch and rainbow trout. All species had health benefit values greater than 2. We observed considerable variability in selenium: mercury molar ratios within fish species collected in the Columbia River Basin. Although incorporating selenium: mercury molar ratios into fish consumption holds the potential for refining advisories and assessing the risk of methylmercury exposure, the current understanding of how these ratios apply is insufficient, and further understanding of drivers of variability in the ratios is needed.

Selenium: Mercury molar ratios in freshwater fish in the Columbia River Basin: Potential applications for specific fish consumption advisories

Science.gov (United States)

Cusack, Leanne K.; Eagles-Smith, Collin A.; Harding, Anna K.; Kile, Molly; Stone, Dave

2017-01-01

Fish provide a valuable source of beneficial nutrients and are an excellent source of low fat protein. However, fish are also the primary source of methylmercury exposure in humans. Selenium often co-occurs with mercury and there is some evidence that selenium can protect against mercury toxicity yet States issue fish consumption advisories based solely on the risks that methylmercury pose to human health. Recently, it has been suggested the selenium: mercury molar ratio be considered in risk management. In order for agencies to utilize the ratio to set consumption guidelines, it is important to evaluate the variability in selenium and mercury in different fish species. We examined 10 different freshwater fish species found within the Columbia River Basin in order to determine the inter- and intra-specific variability in the selenium: mercury molar ratios and the selenium health benefit values. We found significant variation in selenium: mercury molar ratios. The mean molar ratios for each species were all above 1:1, ranging from 3.42:1 in Walleye to 27.2:1 in Chinook salmon. There was a positive correlation between both mercury and selenium with length for each fish species apart from yellow perch and rainbow trout. All species had health benefit values greater than 2. We observed considerable variability in selenium: mercury molar ratios within fish species collected in the Columbia River Basin. Although incorporating selenium: mercury molar ratios into fish consumption holds the potential for refining advisories and assessing the risk of methylmercury exposure, the current understanding of how these ratios apply is insufficient, and further understanding of drivers of variability in the ratios is needed.

Nitrogen–doped graphitized carbon shell encapsulated NiFe nanoparticles: A highly durable oxygen evolution catalyst

Energy Technology Data Exchange (ETDEWEB)

Du, Lei; Luo, Langli; Feng, Zhenxing; Engelhard, Mark; Xie, Xiaohong; Han, Binghong; Sun, Junming; Zhang, Jianghao; Yin, Geping; Wang, Chongmin; Wang, Yong; Shao, Yuyan

2017-09-01

Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhanced reaction kinetics but are limited by their scarce resource. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides etc. are their low electronic conductivity and poor durability. Here, we report OER catalysts of NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells derived from bimetallic metal–organic frameworks (MOFs) precursors. The optimal OER catalyst shows excellent activity (360 mV overpotential at 10 mA cm–2GEO) and durability (no obvious degradation after 20 000 cycles). The electron-donation from Fe and tuned electronic structure of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity. We further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by chemical state of precursors. Severe metal particle growth probably caused by oxidation of carbon shells and encapsulated nanoparticles is believed to the main mechanism for activity degradation in these catalysts.

Amorphous NiFe-OH/NiFeP Electrocatalyst Fabricated at Low Temperature for Water Oxidation Applications

KAUST Repository

Liang, Hanfeng

2017-04-11

Water splitting driven by electricity or sunlight is one of the most promising ways to address the global terawatt energy needs of future societies; however, its large-scale application is limited by the sluggish kinetics of the oxygen evolution reaction (OER). NiFe-based compounds, mainly oxides and hydroxides, are well-known OER catalysts and have been intensively studied; however, the utilization of the synergistic effect between two different NiFe-based materials to further boost the OER performance has not been achieved to date. Here, we report the rapid conversion of NiFe double hydroxide into metallic NiFeP using PH3 plasma treatment and further construction of amorphous NiFe hydroxide/NiFeP/Ni foam as efficient and stable oxygen-evolving anodes. The strong electronic interactions between NiFe hydroxide and NiFeP significantly lower the adsorption energy of H2O on the hybrid and thus lead to enhanced OER performance. As a result, the hybrid catalyst can deliver a geometrical current density of 300 mA cm–2 at an extremely low overpotential (258 mV, after ohmic-drop correction), along with a small Tafel slope of 39 mV decade–1 and outstanding long-term durability in alkaline media.

Boosting Bifunctional Oxygen Electrocatalysis with 3D Graphene Aerogel-Supported Ni/MnO Particles.

Science.gov (United States)

Fu, Gengtao; Yan, Xiaoxiao; Chen, Yifan; Xu, Lin; Sun, Dongmei; Lee, Jong-Min; Tang, Yawen

2018-02-01

Electrocatalysts for oxygen-reduction and oxygen-evolution reactions (ORR and OER) are crucial for metal-air batteries, where more costly Pt- and Ir/Ru-based materials are the benchmark catalysts for ORR and OER, respectively. Herein, for the first time Ni is combined with MnO species, and a 3D porous graphene aerogel-supported Ni/MnO (Ni-MnO/rGO aerogel) bifunctional catalyst is prepared via a facile and scalable hydrogel route. The synthetic strategy depends on the formation of a graphene oxide (GO) crosslinked poly(vinyl alcohol) hydrogel that allows for the efficient capture of highly active Ni/MnO particles after pyrolysis. Remarkably, the resulting Ni-MnO/rGO aerogels exhibit superior bifunctional catalytic performance for both ORR and OER in an alkaline electrolyte, which can compete with the previously reported bifunctional electrocatalysts. The MnO mainly contributes to the high activity for the ORR, while metallic Ni is responsible for the excellent OER activity. Moreover, such bifunctional catalyst can endow the homemade Zn-air battery with better power density, specific capacity, and cycling stability than mixed Pt/C + RuO 2 catalysts, demonstrating its potential feasibility in practical application of rechargeable metal-air batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Open educational resources: staff attitudes and awareness

Directory of Open Access Journals (Sweden)

Vivien Rolfe

2012-02-01

Full Text Available Attitudes are changing in education globally to promote the open sharing of educational courses and resources. The aim of this study was to explore staff awareness and attitudes toward ‘open educational resources’ (OER as a benchmark for monitoring future progress. Faculty staff (n=6 were invited to participate in semi-structured interviews which facilitated the development of a questionnaire. Staff respondents (n=50 were not familiar with the term OER but had a clear notion of what it meant. They were familiar with open content repositories within the university but not externally. A culture of borrowing and sharing of resources exists between close colleagues, but not further a field, and whilst staff would obtain resources from the Internet they were reticent to place materials there. Drivers for mobilising resources included a strong belief in open education, the ability of OER to enhance individual and institutional reputations, and economic factors. Barriers to OER included confusion over copyright and lack of IT support. To conclude, there is a positive collegiate culture within the faculty, and overcoming the lack of awareness and dismantling the barriers to sharing will help advance the open educational practices, benefiting both faculty staff and the global community.

Co@Co3O4 nanoparticle embedded nitrogen-doped carbon architectures as efficient bicatalysts for oxygen reduction and evolution reactions

Science.gov (United States)

Qi, Chunling; Zhang, Li; Xu, Guancheng; Sun, Zhipeng; Zhao, Aihua; Jia, Dianzeng

2018-01-01

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play crucial roles in efficient energy conversion and storage solutions. Here, Co@Co3O4 nanoparticle embedded nitrogen-doped carbon architectures (denoted as Co@Co3O4/NCs) are prepared via a simple two-step and in situ approach by carbonization and subsequent oxidation of Co-MOF containing high contents of carbon and nitrogen. When evaluated as electrocatalyst towards both ORR and OER in a KOH electrolyte solution, the as-fabricated Co@Co3O4/NC-2 exhibits similar ORR catalytic activity to the commercial Pt/C catalyst, but superior stability and good methanol tolerance. Furthermore, the as-fabricated catalysts also show promising catalytic activity for OER. The effective catalytic activities originate from the synergistic effects between well wrapped Co@Co3O4 nanoparticles and nitrogen doped carbon structures.

Efficient oxygen electrocatalysis on special active sites

DEFF Research Database (Denmark)

Halck, Niels Bendtsen

throughout this thesis to understand these local structure effects and their influence on surface reactions. The concept of these special active sites is used to explain how oxygen evolution reaction (OER) catalysts can have activities beyond the limits of what was previously thought possible. The concept...... stored in these bonds in an eco-friendly fashion in fuel cells. This thesis explores catalysts for oxygen electrocatalysis and how carefully designed local structures on catalysts surfaces termed special active sites can influence the activity. Density functional theory has been used as a method...... is used to explain the increase in activity observed for the OER catalyst ruthenium dioxide when it is mixed with nickel or cobalt. Manganese and cobalt oxides when in the vicinity of gold also display an increase in OER activity which can be explained by locally created special active sites. Density...

A permselective CeO{sub x} coating to improve the stability of oxygen evolution electrocatalysts

Energy Technology Data Exchange (ETDEWEB)

Obata, Keisuke; Takanabe, Kazuhiro [King Abdullah University of Science and Technology (KAUST), KAUST Catalysis Center (KCC) and Physical Sciences and Engineering Division PSE, Thuwal (Saudi Arabia)

2018-02-05

Highly active NiFeO{sub x} electrocatalysts for the oxygen evolution reaction (OER) suffer gradual deactivation with time owing to the loss of Fe species from the active sites into solution during catalysis. The anodic deposition of a CeO{sub x} layer prevents the loss of such Fe species from the OER catalysts, achieving a highly stable performance. The CeO{sub x} layer does not affect the OER activity of the catalyst underneath but exhibits unique permselectivity, allowing the permeation of OH{sup -} and O{sub 2} through while preventing the diffusion of redox ions through the layer to function as a selective O{sub 2}-evolving electrode. The use of such a permselective protective layer provides a new strategy for improving the durability of electrocatalysts. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Involving the users remotely: an exploratory study using asynchronous usability testing

Directory of Open Access Journals (Sweden)

Beth Filar Williams

2015-02-01

Full Text Available Open Educational Resources (OER are increasingly used in the higher education landscape as a solution for a variety of copyright, publishing and cost-prohibiting issues. While OERs are becoming more common, reports of usability tests that evaluate how well learners can use them to accomplish their learning tasks have lagged behind. Because both the researchers and the learners in this study use resources and tools remotely, asynchronous usability testing of a prototype OER and MOOC online guide was conducted with an exploratory group of users to determine the guide’s ease of use for two distinct groups of users: Educators and Learners. In this article, we share the background and context of this usability project, suggest best methods for asynchronous remote usability testing, and share challenges and insights of the process and results of the testing

Tau mRNA 3'UTR-to-CDS ratio is increased in Alzheimer disease.

Science.gov (United States)

García-Escudero, Vega; Gargini, Ricardo; Martín-Maestro, Patricia; García, Esther; García-Escudero, Ramón; Avila, Jesús

2017-08-10

Neurons frequently show an imbalance in expression of the 3' untranslated region (3'UTR) relative to the coding DNA sequence (CDS) region of mature messenger RNAs (mRNA). The ratio varies among different cells or parts of the brain. The Map2 protein levels per cell depend on the 3'UTR-to-CDS ratio rather than the total mRNA amount, which suggests powerful regulation of protein expression by 3'UTR sequences. Here we found that MAPT (the microtubule-associated protein tau gene) 3'UTR levels are particularly high with respect to other genes; indeed, the 3'UTR-to-CDS ratio of MAPT is balanced in healthy brain in mouse and human. The tau protein accumulates in Alzheimer diseased brain. We nonetheless observed that the levels of RNA encoding MAPT/tau were diminished in these patients' brains. To explain this apparently contradictory result, we studied MAPT mRNA stoichiometry in coding and non-coding regions, and found that the 3'UTR-to-CDS ratio was higher in the hippocampus of Alzheimer disease patients, with higher tau protein but lower total mRNA levels. Our data indicate that changes in the 3'UTR-to-CDS ratio have a regulatory role in the disease. Future research should thus consider not only mRNA levels, but also the ratios between coding and non-coding regions. Copyright © 2017 Elsevier B.V. All rights reserved.

Ratio dependence in small number discrimination is affected by the experimental procedure

Directory of Open Access Journals (Sweden)

Christian eAgrillo

2015-10-01

Full Text Available Adults, infants and some non-human animals share an approximate number system (ANS to estimate numerical quantities, and are supposed to share a second, ‘object-tracking’, system (OTS that supports the precise representation of a small number of items (up to 3 or 4. In relative numerosity judgments, accuracy depends on the ratio of the two numerosities (Weber’s Law, for numerosities > 4 (the typical ANS range, while for numerosities ≤ 4 (OTS range there is usually no ratio effect. However, recent studies have found evidence for ratio effects for small numerosities, challenging the idea that the OTS might be involved for small number discrimination. Here we tested the hypothesis that the lack of ratio effect in the numbers 1-4 is largely dependent on the type of stimulus presentation.We investigated relative numerosity judgments in college students using three different procedures: a simultaneous presentation of intermingled and separate groups of dots in separate experiments, and a further experiment with sequential presentation. As predicted, in the large number range, ratio dependence was observed in all tasks. By contrast, in the small number range, ratio insensitivity was found in one task (sequential presentation. In a fourth experiment, we showed that the presence of intermingled distractors elicited a ratio effect, while easily distinguishable distractors did not. As the different ratio sensitivity for small and large numbers has been often interpreted in terms of the activation of the OTS and ANS, our results suggest that numbers 1-4 may be represented by both numerical systems and that the experimental context, such as the presence/absence of task-irrelevant items in the visual field, would determine which system is activated.

Aspect ratio has no effect on genotoxicity of multi-wall carbon nanotubes.

Science.gov (United States)

Kim, Jin Sik; Lee, Kyu; Lee, Young Hee; Cho, Hyun Sun; Kim, Ki Heon; Choi, Kyung Hee; Lee, Sang Hee; Song, Kyung Seuk; Kang, Chang Soo; Yu, Il Je

2011-07-01

Carbon nanotubes (CNTs) have specific physico-chemical and electrical properties that are useful for telecommunications, medicine, materials, manufacturing processes and the environmental and energy sectors. Yet, despite their many advantages, it is also important to determine whether CNTs may represent a hazard to the environment and human health. Like asbestos, the aspect ratio (length:diameter) and metal components of CNTs are known to have an effect on the toxicity of carbon nanotubes. Thus, to evaluate the toxic potential of CNTs in relation to their aspect ratio and metal contamination, in vivo and in vitro genotoxicity tests were conducted using high-aspect-ratio (diameter: 10-15 nm, length: ~10 μm) and low-aspect-ratio multi-wall carbon nanotubes (MWCNTs, diameter: 10-15 nm, length: ~150 nm) according to OECD test guidelines 471 (bacterial reverse mutation test), 473 (in vitro chromosome aberration test), and 474 (in vivo micronuclei test) with a good laboratory practice system. To determine the treatment concentration for all the tests, a solubility and dispersive test was performed, and a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) solution found to be more suitable than distilled water. Neither the high- nor the low-aspect-ratio MWCNTs induced any genotoxicity in a bacterial reverse mutation test (~1,000 μg/plate), in vitro chromosome aberration test (without S9: ~6.25 μg/ml, with S9: ~50 μg/ml), or in vivo micronuclei test (~50 mg/kg). However, the high-aspect-ratio MWCNTs were found to be more toxic than the low-aspect-ratio MWCNTs. Thus, while high-aspect-ratio MWCNTs do not induce direct genotoxicity or metabolic activation-mediated genotoxicity, genotoxicity could still be induced indirectly through oxidative stress or inflammation.

Innovative Applications : Open Educational Resources and Mobile Resources Repository for the Instruction of Educational Researchers in Mexico

OpenAIRE

Mortera-Gutierrez, Fernando J.

2010-01-01

The movement of Open Educational Resources (OER) is one of the most important trends that are helping education through the Internet worldwide. "Tecnológico de Monterrey" (http://tecvirtual.itesm.mx/) in Mexico, with other Mexican higher education institutions, is creating an Internet/web based repository of OERs and Mobile Resources for the instruction and development of educational researchers at undergraduate, Master's and Doctoral level. There is a lack of open educational resources and m...

Stable carbon isotope ratio profiling of illicit testosterone preparations--domestic and international seizures.

Science.gov (United States)

Brooker, Lance; Cawley, Adam; Drury, Jason; Edey, Claire; Hasick, Nicole; Goebel, Catrin

2014-10-01

Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) is now established as a robust and mature analytical technique for the doping control of endogenous anabolic androgenic steroids in human sport. It relies on the assumption that the carbon isotope ratios of naturally produced steroids are significantly different to synthetically manufactured testosterone or testosterone prohormones used in commercial medical or dietary supplement products. Recent publications in this journal have highlighted the existence of black market testosterone preparations with carbon isotope ratios within the range reported for endogenous steroids (i.e. δ(13) C ≥ -25.8 ‰). In this study, we set out to profile domestic and international law enforcement seizures of illicit testosterone products to monitor the prevalence of 'enriched' substrates--which if administered to human subjects would be considered problematic for the use of current GC-C-IRMS methodologies for the doping control of testosterone in sport. The distribution of δ(13) C values for this illicit testosterone sample population (n = 283) ranged from -23.4 ‰ to -32.9 ‰ with mean and median of -28.6 ‰--comparable to previous work. However, only 13 out of 283 testosterone samples (4.6 %) were found to display δ(13) C values ≥ -25.8 ‰, confirming that in the vast majority of cases of illicit testosterone administration, current GC-C-IRMS doping control procedures would be capable of confirming misuse. Copyright © 2014 John Wiley & Sons, Ltd.

VVER-1000 dominance ratio

International Nuclear Information System (INIS)

Gorodkov, S.

2009-01-01

Dominance ratio, or more precisely, its closeness to unity, is important characteristic of large reactor. It allows evaluate beforehand the number of source iterations required in deterministic calculations of power spatial distribution. Or the minimal number of histories to be modeled for achievement of statistical error level desired in large core Monte Carlo calculations. In this work relatively simple approach for dominance ratio evaluation is proposed. It essentially uses core symmetry. Dependence of dominance ratio on neutron flux spatial distribution is demonstrated. (author)

WWER-1000 dominance ratio

International Nuclear Information System (INIS)

Gorodkov, S.S.

2009-01-01

Dominance ratio, or more precisely, its closeness to unity, is important characteristic of large reactor. It allows evaluate beforehand the number of source iterations required in deterministic calculations of power spatial distribution. Or the minimal number of histories to be modeled for achievement of statistical error level desired in large core Monte Carlo calculations. In this work relatively simple approach for dominance ratio evaluation is proposed. It essentially uses core symmetry. Dependence of dominance ratio on neutron flux spatial distribution is demonstrated. (Authors)

The Stiles-Crawford Effect: spot-size ratio departure in retinitis pigmentosa

Science.gov (United States)

Sharma, Nachieketa K.; Lakshminarayanan, Vasudevan

2016-04-01

The Stiles-Crawford effect of the first kind is the retina's compensative response to loss of luminance efficiency for oblique stimulation manifested as the spot-size ratio departure from the perfect power coupling for a normal human eye. In a retinitis pigmentosa eye (RP), the normal cone photoreceptor morphology is affected due to foveal cone loss and disrupted cone mosaic spatial arrangement with reduction in directional sensitivity. We show that the flattened Stiles-Crawford function (SCF) in a RP eye is due to a different spot-size ratio departure profile, that is, for the same loss of luminance efficiency, a RP eye has a smaller departure from perfect power coupling compared to a normal eye. Again, the difference in spot-size ratio departure increases from the centre towards the periphery, having zero value for axial entry and maximum value for maximum peripheral entry indicating dispersal of photoreceptor alignment which prevents the retina to go for a bigger compensative response as it lacks both in number and appropriate cone morphology to tackle the loss of luminance efficiency for oblique stimulation. The slope of departure profile also testifies to the flattened SCF for a RP eye. Moreover, the discrepancy in spot-size ratio departure between a normal and a RP eye is shown to have a direct bearing on the Stiles-Crawford diminution of visibility.

Global N Cycle: Fluxes and N2O Mixing Ratios Originating from Human Activity

Data.gov (United States)

National Aeronautics and Space Administration — Nitrogen is a major nutrient in terrestrial ecosystems and an important catalyst in tropospheric photochemistry. Over the last century human activities have...

Global N Cycle: Fluxes and N2O Mixing Ratios Originating from Human Activity

Data.gov (United States)

National Aeronautics and Space Administration — ABSTRACT: Nitrogen is a major nutrient in terrestrial ecosystems and an important catalyst in tropospheric photochemistry. Over the last century human activities...

When do particle ratios freeze out in relativistic heavy ion collisions?

Science.gov (United States)

Humanic, Thomas; Bellwied, Rene

1999-10-01

The systematics of CERN SPS data for transverse mass distributions have been shown to imply that thermal equilibrium is achieved at freeze out in these collisions. This conclusion is based on the observation that for p+p, S+S, and Pb+Pb collisions freeze out occurs at a single temperature for all particle species measured if one assumes a certain uniform expansion velocity after hadronization for each colliding system [1]. A recent final- state rescattering calculation for SPS Pb+Pb collisions has shown that these systematics can be described as a consequence of particle rescattering where the system is assumed initially (i.e. at hadronization) to have a common temperature for all particles and no initial expansion velocity [2]. In addition to kinetic observables, it is equally interesting to investigate the time dependence of particle abundances through particle ratios in such a calculation. Two questions immediately arise: 1) is chemical equilibrium established in these collisions, and 2) when does chemical freeze out occur with respect to thermal freeze out for different particle ratios? How rescattering influences particle ratios is clearly of interest if one would like to deduce information about the hadronization stage of the collision from particle ratios measured at freeze out. For the present work we will show results for strange and non-strange particle ratios within the context of a version of the dynamic transport code used in Ref. [2]. [1] NA44 colaboration, I.G. Bearden et al., Phys. Rev. Lett. 78,2080(1997), [2] T. J. Humanic, Phys. Rev. C 57,866(1998)

INFLUENCE OF SCALE RATIO, ASPECT RATIO, AND PLANFORM ON THE PERFORMANCE OF SUPERCAVITATING HYDROFOILS.

Science.gov (United States)

performance of supercavitating hydrofoils. No appreciable scale effect was found for scale ratios up to 3 in the fully-cavitating flow region. The...overall performance of the hydrofoil by increasing the aspect ratio above 3, and (2) moderate taper ratio seems to be advantageous in view of the overall performance of supercavitating hydrofoils. (Author)

75 FR 74863 - Health Insurance Issuers Implementing Medical Loss Ratio (MLR) Requirements Under the Patient...

Science.gov (United States)

2010-12-01

... Part III Department of Health and Human Services 45 CFR Part 158 Health Insurance Issuers... 0950-AA06 Health Insurance Issuers Implementing Medical Loss Ratio (MLR) Requirements Under the Patient... health insurance issuers under the Public Health Service Act, as added by the Patient Protection and...

Large Aspect Ratio Tokamak Study

International Nuclear Information System (INIS)

Reid, R.L.; Holmes, J.A.; Houlberg, W.A.; Peng, Y.K.M.; Strickler, D.J.; Brown, T.G.; Wiseman, G.W.

1980-06-01

The Large Aspect Ratio Tokamak Study (LARTS) at Oak Ridge National Laboratory (ORNL) investigated the potential for producing a viable longburn tokamak reactor by enhancing the volt-second capability of the ohmic heating transformer through the use of high aspect ratio designs. The plasma physics, engineering, and economic implications of high aspect ratio tokamaks were assessed in the context of extended burn operation. Using a one-dimensional transport code plasma startup and burn parameters were addressed. The pulsed electrical power requirements for the poloidal field system, which have a major impact on reactor economics, were minimized by optimizing the startup and shutdown portions of the tokamak cycle. A representative large aspect ratio tokamak with an aspect ratio of 8 was found to achieve a burn time of 3.5 h at capital cost only approx. 25% greater than that of a moderate aspect ratio design tokamak

Mesoporous Ruthenium/Ruthenium Oxide Thin Films: Active Electrocatalysts for the Oxygen Evolution Reaction

DEFF Research Database (Denmark)

Kibsgaard, Jakob; Hellstern, Thomas R.; Choi, Shin-Jung

2017-01-01

We report the first synthesis of a fully contiguous large area supported thin film of highly ordered mesoporous Ru and RuO2 and investigate the electrocatalytic properties towards the oxygen evolution reaction (OER). We find that the nanoscale porous network of these catalysts provides significant...... enhancements in geometric OER activity without any loss in specific activity. This work demonstrates a strategy for engineering materials at the nanoscale that can simultaneously decrease precious metal loading and increase electrode activity....

Oxygen evolution reaction catalysis

Energy Technology Data Exchange (ETDEWEB)

Haber, Joel A.; Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Jones, Ryan J.; Guevarra, Dan W.; Shinde, Aniketa A.

2016-09-06

An Oxygen Evolution Reaction (OER) catalyst includes a metal oxide that includes oxygen, cerium, and one or more second metals. In some instances, the cerium is 10 to 80 molar % of the metals in the metal oxide and/or the catalyst includes two or more second metals. The OER catalyst can be included in or on an electrode. The electrode can be arranged in an oxygen evolution system such that the Oxygen Evolution Reaction occurs at the electrode.

Modified Carbon Nanomaterials as Active Electrocatalysts

OpenAIRE

Tavakkoli, Mohammad

2017-01-01

Water splitting (WS) has attracted increasing attention for producing highly pure hydrogen and oxygen. WS is also a promising technique to store intermittent electrical energy from renewable resources such as solar and wind energy in the form of H2 fuel. WS consists of two half-reactions: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). For HER, efficient non-precious catalysts are required to replace the rare and expensive Pt-based catalysts. For OER, more efficient low...

Word Class Ratios and Genres in Written Japanese: Revisiting the Modifier Verb Ratio

Directory of Open Access Journals (Sweden)

Bor HODOŠČEK

2011-10-01

Full Text Available This paper explores the variability of genres in the Balanced Corpus of Contemporary Written Japanese using the modifier-verb ratio proposed by Kabashima and Jukaku (1965. Using bagplots to quantifying the relation between noun and modifier-verb ratios, as well as some summary statistics obtain from them, we attempt to classify genres according to Kabashima and Jugaku (1965. Our initial analysis confirms previous research results, while at the same time uncovering some contradictions in the ratios of the genre of magazines.

Lunar cycles at mating do not influence sex ratio at birth in horses.

Science.gov (United States)

Aguilar, J J; Cuervo-Arango, J; Santa Juliana, L

2015-02-01

It is scientifically demonstrated that lunar cycles have important effects on several biological events. Controversy exists about the lunar influence on human and animal parturition. In addition, in the horse industry, especially in Polo Horse breeders of Argentina and around the world there is a higher demand for female offspring than for males. The objective of this study was to determine whether there is a significant association between the lunar phase at the time of mating and the sex ratio at birth in horses. The Argentinean Stud Book provided information related to all matings registered for Thoroughbred and Arab horses between 2003 and 2011. Statistical associations were tested between dates of matings at different lunar phases or days and sex ratio at birth. A total of 65.535 gestations were studied. Overall, sex ratio at birth resulted in 33.396 fillies (50.96%) and 32.139 colts (49.04%). The percentages of males and females at birth were not statistically different amongst the different lunar phases or days. We can strongly conclude that managing the breeding dates in relation to lunar cycles in order to manipulate the sex ratio of the offspring is not a viable option in horses.

Controlling the Interfacial Environment in the Electrosynthesis of MnOx Nanostructures for High-Performance Oxygen Reduction/Evolution Electrocatalysis.

Science.gov (United States)

Hosseini-Benhangi, Pooya; Kung, Chun Haow; Alfantazi, Akram; Gyenge, Elöd L

2017-08-16

High-performance, nonprecious metal bifunctional electrocatalysts for the oxygen reduction and evolution reactions (ORR and OER, respectively) are of great importance for rechargeable metal-air batteries and regenerative fuel cells. A comprehensive study based on statistical design of experiments is presented to investigate and optimize the surfactant-assisted structure and the resultant bifunctional ORR/OER activity of anodically deposited manganese oxide (MnO x ) catalysts. Three classes of surfactants are studied: anionic (sodium dodecyl sulfate, SDS), non-ionic (t-octylphenoxypolyethoxyethanol, Triton X-100), and cationic (cetyltrimethylammonium bromide, CTAB). The adsorption of surfactants has two main effects: increased deposition current density due to higher Mn 2+ and Mn 3+ concentrations at the outer Helmholtz plane (Frumkin effect on the electrodeposition kinetics) and templating of the MnO x nanostructure. CTAB produces MnO x with nanoneedle (1D) morphology, whereas nanospherical- and nanopetal-like morphologies are obtained with SDS and Triton, respectively. The bifunctional performance is assessed based on three criteria: OER/ORR onset potential window (defined at 2 and -2 mA cm -2 ) and separately the ORR and OER mass activities. The best compromise among these three criteria is obtained either with Triton X-100 deposited catalyst composed of MnOOH and Mn 3 O 4 or SDS deposited catalyst containing a combination of α- and β-MnO 2 , MnOOH, and Mn 3 O 4 .The interaction effects among the deposition variables (surfactant type and concentration, anode potential, Mn 2+ concentration, and temperature) reveal the optimal strategy for high-activity bifunctional MnO x catalyst synthesis. Mass activities for OER and ORR up to 49 A g -1 (at 1556 mV RHE ) and -1.36 A g -1 (at 656 mV RHE ) are obtained, respectively.

Establishing efficient cobalt based catalytic sites for oxygen evolution on a Ta3N5 photocatalyst

KAUST Repository

Nurlaela, Ela; Ould-Chikh, Samy; Llorens, Isabelle; Hazemann, Jean-louis; Takanabe, Kazuhiro

2015-01-01

In a photocatalytic suspension system with a powder semiconductor, the interface between the photocatalyst semiconductor and catalyst should be constructed to minimize resistance for charge transfer of excited carriers. This study demonstrates an in-depth understanding of pretreatment effects on the photocatalytic O2 evolution reaction (OER) activity of visible-light-responsive Ta3N5 decorated with CoOx nanoparticles. The CoOx/Ta3N5 sample was synthesized by impregnation followed by sequential heat treat-ments under NH3 flow and air flow at various temperatures. Various characterization techniques, including X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), and X-ray photoelectron spec-troscopy (XPS), were used to clarify the state and role of cobalt. No improvement in photocatalytic activity for OER over the bare Ta3N5 was observed for the as-impregnated CoOx/Ta3N5, likely because of insufficient contact between CoOx and Ta3N5. When the sample was treated in NH3 at high temperature, a substantial improvement in the photocatalytic activity was observed. After NH3 treatment at 700 °C, the Co0-CoOx core-shell agglomerated cobalt structure was identified by XAS and STEM. No metallic cobalt species was evident after the photocatalytic OER, indicating that the metallic cobalt itself is not essential for the reaction. Accordingly, mild oxidation (200 °C) of the NH3-treated CoOx/Ta3N5 sample enhanced photocatalytic OER activity. Oxidation at higher temperatures drastically eliminated the photocatalytic activity, most likely because of unfavorable Ta3N5 oxidation. These results suggest that the intimate contact between cobalt species and Ta3N5 facilitated at high temperature is beneficial to enhancing hole transport and that the cobalt oxide provides electrocatalytic sites for OER.

Electro-catalytic activity of Ni–Co-based catalysts for oxygen evolution reaction

Energy Technology Data Exchange (ETDEWEB)

Ju, Hua [School of Urban Rail Transportation, Soochow University, Suzhou 215006 (China); Li, Zhihu [College of Physics, Optoelectronics and Energy, Soochow University, Moye Rd. 688, Suzhou 215006 (China); Xu, Yanhui, E-mail: xuyanhui@suda.edu.cn [College of Physics, Optoelectronics and Energy, Soochow University, Moye Rd. 688, Suzhou 215006 (China)

2015-04-15

Graphical abstract: The electro-catalytic activity of different electro-catalysts with a porous electrode structure was compared considering the real electrode area that was evaluated by cyclic measurement. - Highlights: • Ni–Co-based electro-catalysts for OER have been studied and compared. • The real electrode area is calculated and used for assessing the electro-catalysts. • Exchange current and reaction rate constant are estimated. • Ni is more useful for OER reaction than Co. - Abstract: In the present work, Ni–Co-based electrocatalysts (Ni/Co = 0:6, 1:5, 2:4, 3:3, 4:2, 5:1 and 6:0) have been studied for oxygen evolution reaction. The phase structure has been analyzed by X-ray diffraction technique. Based on the XRD and SEM results, it is believed that the synthesized products are poorly crystallized. To exclude the disturbance of electrode preparation technology on the evaluation of electro-catalytic activity, the real electrode surface area is calculated based on the cyclic voltammetry data, assumed that the specific surface capacitance is 60 μF cm{sup −2} for metal oxide electrode. The real electrode area data are used to calculate the current density. The reaction rate constant of OER at different electrodes is also estimated based on basic reaction kinetic equations. It is found that the exchange current is 0.05–0.47 mA cm{sup −2} (the real surface area), and the reaction rate constant has an order of magnitude of 10{sup −7}–10{sup −6} cm s{sup −1}. The influence of the electrode potential on OER rate has been also studied by electrochemical impedance spectroscopy (EIS) technique. Our investigation has shown that the nickel element has more contribution than the cobalt; the nickel oxide has the best electro-catalytic activity toward OER.

Establishing efficient cobalt based catalytic sites for oxygen evolution on a Ta3N5 photocatalyst

KAUST Repository

Nurlaela, Ela

2015-08-05

In a photocatalytic suspension system with a powder semiconductor, the interface between the photocatalyst semiconductor and catalyst should be constructed to minimize resistance for charge transfer of excited carriers. This study demonstrates an in-depth understanding of pretreatment effects on the photocatalytic O2 evolution reaction (OER) activity of visible-light-responsive Ta3N5 decorated with CoOx nanoparticles. The CoOx/Ta3N5 sample was synthesized by impregnation followed by sequential heat treat-ments under NH3 flow and air flow at various temperatures. Various characterization techniques, including X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), and X-ray photoelectron spec-troscopy (XPS), were used to clarify the state and role of cobalt. No improvement in photocatalytic activity for OER over the bare Ta3N5 was observed for the as-impregnated CoOx/Ta3N5, likely because of insufficient contact between CoOx and Ta3N5. When the sample was treated in NH3 at high temperature, a substantial improvement in the photocatalytic activity was observed. After NH3 treatment at 700 °C, the Co0-CoOx core-shell agglomerated cobalt structure was identified by XAS and STEM. No metallic cobalt species was evident after the photocatalytic OER, indicating that the metallic cobalt itself is not essential for the reaction. Accordingly, mild oxidation (200 °C) of the NH3-treated CoOx/Ta3N5 sample enhanced photocatalytic OER activity. Oxidation at higher temperatures drastically eliminated the photocatalytic activity, most likely because of unfavorable Ta3N5 oxidation. These results suggest that the intimate contact between cobalt species and Ta3N5 facilitated at high temperature is beneficial to enhancing hole transport and that the cobalt oxide provides electrocatalytic sites for OER.

Structure Effects of 2D Materials on α-Nickel Hydroxide for Oxygen Evolution Reaction.

Science.gov (United States)

Luan, Chenglong; Liu, Guangli; Liu, Yujie; Yu, Lei; Wang, Yao; Xiao, Yun; Qiao, Hongyan; Dai, Xiaoping; Zhang, Xin

2018-04-24

To engineer low-cost, high-efficiency, and stable oxygen evolution reaction (OER) catalysts, structure effects should be primarily understood. Focusing on this, we systematically investigated the relationship between structures of materials and their OER performances by taking four 2D α-Ni(OH) 2 as model materials, including layer-stacked bud-like Ni(OH) 2 -NB, flower-like Ni(OH) 2 -NF, and petal-like Ni(OH) 2 -NP as well as the ultralarge sheet-like Ni(OH) 2 -NS. For the first three (layer-stacking) catalysts, with the decrease of stacked layers, their accessible surface areas, abilities to adsorb OH - , diffusion properties, and the intrinsic activities of active sites increase, which accounts for their steadily enhanced activity. As expected, Ni(OH) 2 -NP shows the lowest overpotential (260 mV at 10 mA cm -2 ) and Tafel slope (78.6 mV dec -1 ) with a robust stability over 10 h among the samples, which also outperforms the benchmark IrO 2 (360 mV and 115.8 mV dec -1 ) catalyst. Interestingly, Ni(OH) 2 -NS relative to Ni(OH) 2 -NP exhibits even faster substance diffusion due to the sheet-like structure, but shows inferior OER activity, which is mainly because the Ni(OH) 2 -NP with a smaller size possesses more active boundary sites (higher reactivity of active sites) than Ni(OH) 2 -NS, considering the adsorption properties and accessible surface areas of the two samples are quite similar. By comparing the different structures and their OER behaviors of four α-Ni(OH) 2 samples, our work may shed some light on the structure effect of 2D materials and accelerate the development of efficient OER catalysts.

Ventilation and ventilation/perfusion ratios

International Nuclear Information System (INIS)

Valind, S.O.

1989-01-01

The thesis is based on five different papers. The labelling of specific tracer compounds with positron emitting radionuclides enables a range of structural, physiological and biochemical parameters in the lung to be measured non-invasively, using positron emission tomography. This concept affords a unique opportunity for in vivo studies of different expressions of pulmonary pathophysiology at the regional level. The present thesis describes the application of positron emission tomography to the measurements of ventilation and ventilation/perfusion ratios using inert gas tracers, neon-19 and nitrogen-13 respectively. The validity of the methods applied was investigated with respect to the transport of inert gas tracers in the human lung. Both ventilation and the ventilation/perfusion ratio may be obtained with errors less than 10 % in the normal lung. In disease, however, errors may increase in those instances where the regional ventilation is very low or the intra-regional gas flow distribution is markedly nonuniform. A 2-3 fold increase in ventilation was demonstrated in normal nonsmoking subjects going from ventral to dorsal regions in the supine posture. These large regional differences could be well explained by the intrinsic elastic properties of lung tissue, considering the gravitational gradient in transpulmonary pressure. In asymptomatic smokers substantial regional ventilatroy abnormalities were found whilst the regional gas volume was similar in smokers and nonsmokers. The uncoupling between ventilation and gas volume probably reflects inflammatory changes in the airways. The regional differences in dV/dt/dQ/dt were relatively small and blood flow was largely matched to ventilation in the supine posture. However, small regions of lung with very low ventilation, unmatched by blood flow commonly exists in the most dependent parts of the lung in both smokers and nonsmokers. (29 illustrations, 7 tables, 113 references)

Increased sex ratio in Russia and Cuba after Chernobyl: a radiological hypothesis.

Science.gov (United States)

Scherb, Hagen; Kusmierz, Ralf; Voigt, Kristina

2013-08-15

The ratio of male to female offspring at birth may be a simple and non-invasive way to monitor the reproductive health of a population. Except in societies where selective abortion skews the sex ratio, approximately 105 boys are born for every 100 girls. Generally, the human sex ratio at birth is remarkably constant in large populations. After the Chernobyl nuclear power plant accident in April 1986, a long lasting significant elevation in the sex ratio has been found in Russia, i.e. more boys or fewer girls compared to expectation were born. Recently, also for Cuba an escalated sex ratio from 1987 onward has been documented and discussed in the scientific literature. By the end of the eighties of the last century in Cuba as much as about 60% of the food imports were provided by the former Soviet Union. Due to its difficult economic situation, Cuba had neither the necessary insight nor the political strength to circumvent the detrimental genetic effects of imported radioactively contaminated foodstuffs after Chernobyl. We propose that the long term stable sex ratio increase in Cuba is essentially due to ionizing radiation. A synoptic trend analysis of Russian and Cuban annual sex ratios discloses upward jumps in 1987. The estimated jump height from 1986 to 1987 in Russia measures 0.51% with a 95% confidence interval (0.28, 0.75), p value Cuba the estimated jump height measures 2.99% (2.39, 3.60), p value Cuba and by radiological analyses of remains in Cuba for Cs-137 and Sr-90. If the evidence for the hypothesis is strengthened, there is potential to learn about genetic radiation risks and to prevent similar effects in present and future exposure situations.

The association between living through a prolonged economic depression and the male:female birth ratio--a longitudinal study from Cuba, 1960-2008.

Science.gov (United States)

Venero Fernández, Silvia Josefina; Medina, Ramon Suárez; Britton, John; Fogarty, Andrew W

2011-12-15

The Trivers-Willard hypothesis suggests that populations respond to scarcity by decreasing the ratio of males to females at livebirth. Cuba experienced an extreme economic depression in the 1990s called the "special period." Using time-series analysis, the authors studied the impact of this event on the male:female sex ratio at birth in Cuba from 1960 to 2008. From 1990 to 1993, the per capita gross domestic product in Cuba decreased by 36%. By use of a definition of the special period from 1991 to 1998, there was a prolonged increase in the male:female ratio of livebirths during this period of economic depression (P Cuba, contrary to the Trivers-Willard hypothesis, the human population responded to conditions of scarcity by increasing the ratio of males to females at livebirth. These data may be relevant in the modeling of demographic projections in countries that experience prolonged economic depression and in understanding adaptive human reproductive responses to environmental change.

Identifying Malignant Pleural Effusion by A Cancer Ratio (Serum LDH: Pleural Fluid ADA Ratio).

Science.gov (United States)

Verma, Akash; Abisheganaden, John; Light, R W

2016-02-01

We studied the diagnostic potential of serum lactate dehydrogenase (LDH) in malignant pleural effusion. Retrospective analysis of patients hospitalized with exudative pleural effusion in 2013. Serum LDH and serum LDH: pleural fluid ADA ratio was significantly higher in cancer patients presenting with exudative pleural effusion. In multivariate logistic regression analysis, pleural fluid ADA was negatively correlated 0.62 (0.45-0.85, p = 0.003) with malignancy, whereas serum LDH 1.02 (1.0-1.03, p = 0.004) and serum LDH: pleural fluid ADA ratio 0.94 (0.99-1.0, p = 0.04) was correlated positively with malignant pleural effusion. For serum LDH: pleural fluid ADA ratio, a cut-off level of >20 showed sensitivity, specificity of 0.98 (95 % CI 0.92-0.99) and 0.94 (95 % CI 0.83-0.98), respectively. The positive likelihood ratio was 32.6 (95 % CI 10.7-99.6), while the negative likelihood ratio at this cut-off was 0.03 (95 % CI 0.01-0.15). Higher serum LDH and serum LDH: pleural fluid ADA ratio in patients presenting with exudative pleural effusion can distinguish between malignant and non-malignant effusion on the first day of hospitalization. The cut-off level for serum LDH: pleural fluid ADA ratio of >20 is highly predictive of malignancy in patients with exudative pleural effusion (whether lymphocytic or neutrophilic) with high sensitivity and specificity.

Display characterization by eye: contrast ratio and discrimination throughout the grayscale

Science.gov (United States)

Gille, Jennifer; Arend, Larry; Larimer, James O.

2004-06-01

We have measured the ability of observers to estimate the contrast ratio (maximum white luminance / minimum black or gray) of various displays and to assess luminous discrimination over the tonescale of the display. This was done using only the computer itself and easily-distributed devices such as neutral density filters. The ultimate goal of this work is to see how much of the characterization of a display can be performed by the ordinary user in situ, in a manner that takes advantage of the unique abilities of the human visual system and measures visually important aspects of the display. We discuss the relationship among contrast ratio, tone scale, display transfer function and room lighting. These results may contribute to the development of applications that allow optimization of displays for the situated viewer / display system without instrumentation and without indirect inferences from laboratory to workplace.

Fe/Ni-N-CNFs electrochemical catalyst for oxygen reduction reaction/oxygen evolution reaction in alkaline media

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhuang [MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001 (China); Li, Mian [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Fan, Liquan; Han, Jianan [MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xiong, Yueping, E-mail: ypxiong@hit.edu.cn [MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001 (China)

2017-04-15

Highlights: • Novel Fe/Ni-N-CNFs electrocatalysts are prepared by electrospinning technique. • The Fe1Ni1-N-CNFs catalyst exhibits the excellent ORR and OER catalytic activity. • Synergy of Fe/Ni alloy is responsible for the excellent catalytic performance. - Abstract: The novel of iron, nickel and nitrogen doped carbon nanofibers (Fe/Ni-N-CNFs) as bifunctional electrocatalysts are prepared by electrospinning technique. In alkaline media, the Fe/Ni-N-CNFs catalysts (especially for Fe1Ni1-N-CNFs) exhibit remarkable electrocatalytic performances of oxygen reduction reaction (ORR)/oxygen evolution reaction (OER). For ORR catalytic activity, Fe1Ni1-N-CNFs catalyst offers a higher onset potential of 0.903 V, a similar four-electron reaction pathway, and excellent stability. For OER catalytic activity, Fe1Ni1-N-CNFs catalyst possesses a lower onset potential of 1.528 V and a smaller charge transfer resistance of 48.14 Ω. The unparalleled catalytic activity of ORR and OER for the Fe1Ni1-N-CNFs is attributed to the 3D porous cross-linked microstructures of carbon nanofibers with Fe/Ni alloy, N dopant, and abundant M-N{sub x} and NiOOH as catalytic active sites. Thus, Fe1Ni1-N-CNFs catalyst can be acted as one of the efficient and inexpensive catalysts of metal-air batteries.

3D structured Mo-doped Ni3S2 nanosheets as efficient dual-electrocatalyst for overall water splitting

Science.gov (United States)

Wu, Chengrong; Liu, Bitao; Wang, Jun; Su, Yongyao; Yan, Hengqing; Ng, Chuntan; Li, Cheng; Wei, Jumeng

2018-05-01

Searching for a cost-effective, high efficient and stable bifunctional electrocatalyst for overall water-splitting is critical to renewable energy systems. In this study, three-dimensional (3D) curved nanosheets of Mo-doped Ni3S2 grown on nickel foam were successfully synthesized via a one-step hydrothermal process. The hydrogen-evolution reaction (HER) and the oxygen-evolution reaction (OER) in alkaline environment of this 3D catalyst are investigated in detail. The results show that it possesses lower overpotential, high current densities and small Tafel slopes both in OER and HER. For HER, the catalysts show excellent electrochemical performance, demonstrating a low over-potential of 212 mV at 10 mA cm-2 with a large decrease of 127 mV compared to the undoped Ni3S2. And it also shows a lower overpotential of 260 mV at 10 mA cm-2 which decreases 30 mV for OER. In addition, it is only need 1.67 V for the overall water splitting at 10 mA cm-2 which is 70 mV. It found that the Mo element would change the morphology of Ni3S2 and induce much more active sites for HER and OER. The as-prepared Mo-doped Ni3S2 bi-functional electrocatalyst could act as the promising electrode materials for water splitting.

The response of human and rodent cells to hyperthermia

International Nuclear Information System (INIS)

Roizin-Towle, L.; Pirro, J.P.

1991-01-01

Inherent cellular radiosensitivity in vitro has been shown to be a good predictor of human tumor response in vivo. In contrast, the importance of the intrinsic thermosensitivity of normal and neoplastic human cells as a factor in the responsiveness of human tumors to adjuvant hyperthermia has never been analyzed systematically. A comparison of thermal sensitivity and thermo-radiosensitization in four rodent and eight human-derived cell lines was made in vitro. Arrhenius plots indicated that the rodent cells were more sensitive to heat killing than the human, and the break-point was 0.5 degrees C higher for the human than rodent cells. The relationship between thermal sensitivity and the interaction of heat with X rays at low doses was documented by thermal enhancement ratios (TER's). Cells received either a 1 hr exposure to 43 degrees C or a 20 minute treatment at 45 degrees C before exposure to 300 kVp X rays. Thermal enhancement ratios ranged from 1.0 to 2.7 for human cells heated at 43 degrees C and from 2.1 to 5.3 for heat exposures at 45 degrees C. Thermal enhancement ratios for rodent cells were generally 2 to 3 times higher than for human cells, because of the fact that the greater thermosensitivity of rodent cells results in a greater enhancement of radiation damage. Intrinsic thermosensitivity of human cells has relevance to the concept of thermal dose; intrinsic thermo-radiosensitization of a range of different tumor cells is useful in documenting the interactive effects of radiation combined with heat

Isotopic ratio based source apportionment of children's blood lead around coking plant area.

Science.gov (United States)

Cao, Suzhen; Duan, Xiaoli; Zhao, Xiuge; Wang, Beibei; Ma, Jin; Fan, Delong; Sun, Chengye; He, Bin; Wei, Fusheng; Jiang, Guibin

2014-12-01

Lead exposure in the environment is a major hazard affecting human health, particularly for children. The blood lead levels in the local children living around the largest coking area in China were measured, and the source of blood lead and the main pathways of lead exposure were investigated based on lead isotopic ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb) in blood and in a variety of media, including food, airborne particulate matter, soil, dust and drinking water. The children's blood lead level was 5.25 (1.59 to 34.36 as range) μg dL(-1), lower than the threshold in the current criteria of China defined by the US Centers for Disease Control (10 μg dL(-1)). The isotopic ratios in the blood were 2.111±0.018 for (208)Pb/(206)Pb and 0.864±0.005 for (207)Pb/(206)Pb, similar to those of vegetables, wheat, drinking water, airborne particulate matter, but different from those of vehicle emission and soil/dust, suggesting that the formers were the main pathway of lead exposure among the children. The exposure pathway analysis based on the isotopic ratios and the human health risk assessment showed that dietary intake of food and drinking water contributed 93.67% of total exposed lead. The study further indicated that the coal used in the coking plant is the dominant pollution source of lead in children's blood. Copyright © 2014 Elsevier Ltd. All rights reserved.

Temperature and air-fuel ratio dependent specific heat ratio functions for lean burned and unburned mixture

International Nuclear Information System (INIS)

Ceviz, M.A.; Kaymaz, I.

2005-01-01

The most important thermodynamic property used in heat release calculations for engines is the specific heat ratio. The functions proposed in the literature for the specific heat ratio are temperature dependent and apply at or near stoichiometric air-fuel ratios. However, the specific heat ratio is also influenced by the gas composition in the engine cylinder and especially becomes important for lean combustion engines. In this study, temperature and air-fuel ratio dependent specific heat ratio functions were derived to minimize the error by using an equilibrium combustion model for burned and unburned mixtures separately. After the error analysis between the equilibrium combustion model and the derived functions is presented, the results of the global specific heat ratio function, as varying with mass fraction burned, were compared with the proposed functions in the literature. The results of the study showed that the derived functions are more feasible at lean operating conditions of a spark ignition engine

Massive Open Online Courses (MOOC) for Teaching Portuguese for Foreigners: A Case Study

OpenAIRE

ZANCANARO, Airton; DOMINGUES, Maria Jose Carvalho de Souza

2018-01-01

Education is experiencing a period of change and the traditional models of education adopted by universities need to go through innovative processes to democratize knowledge, attract new learners and optimize resources. The use of Open Educational Resources (OERs) and Massive Open Online Courses (MOOC) can contribute to such changes. However, studies on the reuse of OERs and language courses in the MOOC format are still scarce. To this end, the aims of this study are (a) to verify whether the...

Investigating supported or unsupported individual and group work in open forums in an open educational resources repository

OpenAIRE

Wilson, Tina

2008-01-01

Open Educational Resources (OERs) can play a part in advancing the lifelong learning and social inclusion agendas (Geser, 2007). The focal point of this paper is on how learners of different ages will be encouraged to adopt OERs by their teachers and facilitators. The discussion starts by looking at how the facilitators will support their learners in an open arena. This is followed by the facilitators approach to individual and group work in an open access environment. The discourse then move...

Poisson's ratio of fiber-reinforced composites

Science.gov (United States)

Christiansson, Henrik; Helsing, Johan

1996-05-01

Poisson's ratio flow diagrams, that is, the Poisson's ratio versus the fiber fraction, are obtained numerically for hexagonal arrays of elastic circular fibers in an elastic matrix. High numerical accuracy is achieved through the use of an interface integral equation method. Questions concerning fixed point theorems and the validity of existing asymptotic relations are investigated and partially resolved. Our findings for the transverse effective Poisson's ratio, together with earlier results for random systems by other authors, make it possible to formulate a general statement for Poisson's ratio flow diagrams: For composites with circular fibers and where the phase Poisson's ratios are equal to 1/3, the system with the lowest stiffness ratio has the highest Poisson's ratio. For other choices of the elastic moduli for the phases, no simple statement can be made.

Detecting isotopic ratio outliers

Science.gov (United States)

Bayne, C. K.; Smith, D. H.

An alternative method is proposed for improving isotopic ratio estimates. This method mathematically models pulse-count data and uses iterative reweighted Poisson regression to estimate model parameters to calculate the isotopic ratios. This computer-oriented approach provides theoretically better methods than conventional techniques to establish error limits and to identify outliers.

Detecting isotopic ratio outliers

International Nuclear Information System (INIS)

Bayne, C.K.; Smith, D.H.

1986-01-01

An alternative method is proposed for improving isotopic ratio estimates. This method mathematically models pulse-count data and uses iterative reweighted Poisson regression to estimate model parameters to calculate the isotopic ratios. This computer-oriented approach provides theoretically better methods than conventional techniques to establish error limits and to identify outliers

Libre learning: OER and equality

CSIR Research Space (South Africa)

Tucker, K

2007-09-01

Full Text Available This presentation discusses open education resources, educational projects in rural areas, enabling communities to empower themselves with knowledge etc. The MobilED (mobile education) initiative is aimed at designing learning and teaching...

Arcjet nozzle area ratio effects

Science.gov (United States)

Curran, Francis M.; Sarmiento, Charles J.; Birkner, Bjorn W.; Kwasny, James

1990-01-01

An experimental investigation was conducted to determine the effect of nozzle area ratio on the operating characteristics and performance of a low power dc arcjet thruster. Conical thoriated tungsten nozzle inserts were tested in a modular laboratory arcjet thruster run on hydrogen/nitrogen mixtures simulating the decomposition products of hydrazine. The converging and diverging sides of the inserts had half angles of 30 and 20 degrees, respectively, similar to a flight type unit currently under development. The length of the diverging side was varied to change the area ratio. The nozzle inserts were run over a wide range of specific power. Current, voltage, mass flow rate, and thrust were monitored to provide accurate comparisons between tests. While small differences in performance were observed between the two nozzle inserts, it was determined that for each nozzle insert, arcjet performance improved with increasing nozzle area ratio to the highest area ratio tested and that the losses become very pronounced for area ratios below 50. These trends are somewhat different than those obtained in previous experimental and analytical studies of low Re number nozzles. It appears that arcjet performance can be enhanced via area ratio optimization.

Arcjet Nozzle Area Ratio Effects

Science.gov (United States)

Curran, Francis M.; Sarmiento, Charles J.; Birkner, Bjorn W.; Kwasny, James

1990-01-01

An experimental investigation was conducted to determine the effect of nozzle area ratio on the operating characteristics and performance of a low power dc arcjet thruster. Conical thoriated tungsten nozzle inserts were tested in a modular laboratory arcjet thruster run on hydrogen/nitrogen mixtures simulating the decomposition products of hydrazine. The converging and diverging sides of the inserts had half angles of 30 and 20 degrees, respectively, similar to a flight type unit currently under development. The length of the diverging side was varied to change the area ratio. The nozzle inserts were run over a wide range of specific power. Current, voltage, mass flow rate, and thrust were monitored to provide accurate comparisons between tests. While small differences in performance were observed between the two nozzle inserts, it was determined that for each nozzle insert, arcjet performance improved with increasing nozzle area ratio to the highest area ratio tested and that the losses become very pronounced for area ratios below 50. These trends are somewhat different than those obtained in previous experimental and analytical studies of low Re number nozzles. It appears that arcjet performance can be enhanced via area ratio optimization.

Electrocatalytic performance evaluation of cobalt hydroxide and cobalt oxide thin films for oxygen evolution reaction

Science.gov (United States)

Babar, P. T.; Lokhande, A. C.; Pawar, B. S.; Gang, M. G.; Jo, Eunjin; Go, Changsik; Suryawanshi, M. P.; Pawar, S. M.; Kim, Jin Hyeok

2018-01-01

The development of an inexpensive, stable, and highly active electrocatalyst for oxygen evolution reaction (OER) is essential for the practical application of water splitting. Herein, we have synthesized an electrodeposited cobalt hydroxide on nickel foam and subsequently annealed in an air atmosphere at 400 °C for 2 h. In-depth characterization of all the films using X-ray diffraction (XRD), X-ray photoelectron emission spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) techniques, which reveals major changes for their structural, morphological, compositional and electrochemical properties, respectively. The cobalt hydroxide nanosheet film shows high catalytic activity with 290 mV overpotential at 10 mA cm-2 and 91 mV dec-1 Tafel slope and robust stability (24 h) for OER in 1 M KOH electrolyte compared to cobalt oxide (340 mV). The better OER activity of cobalt hydroxide in comparison to cobalt oxide originated from high active sites, enhanced surface, and charge transport capability.

Electrolyte engineering toward efficient water splitting at mild pH

KAUST Repository

Shinagawa, Tatsuya; Ng, Marcus Tze-Kiat; Takanabe, Kazuhiro

2017-01-01

The development of processes for the conversion of H2O/CO2 driven by electricity generated in renewable manners is essential to achieve sustainable energy and chemical cycles, in which the electrocatalytic oxygen evolution reaction (OER) is one of the bottlenecks. In this contribution, the influences of the electrolyte molarity and identity on OER at alkaline to neutral pH were investigated at an appreciable current density of ~10 mA cm-2, revealing (1) the clear boundary of reactant switching between H2O/OH- due to the diffusion limitation of OH- and (2) the substantial contribution of the mass transport of the buffered species in buffered mild pH conditions. These findings propose a strategy of electrolyte engineering: tuning the electrolyte properties to maximize the mass-transport flux. The concept was successfully demonstrated for OER as well as overall water electrolysis in buffered mild pH conditions, shedding light on the development of practical solar fuel production systems.

Collaborative design of Open Educational Practices: An Assets based approach

Directory of Open Access Journals (Sweden)

Kate Helen Miller

2018-04-01

Full Text Available This paper outlines a collaborative approach to the design of open educational resources (OER with community stakeholders so they can be shared with other community practitioners openly, online and repurposed for other contexts. We view curriculum not as something that educationalists provide but rather something that emerges as learners engage with an educational context. We draw on a Project consisting of a partnership between five European Institutions of Higher Education and a range of community stakeholder groups. The partnership will develop a suite of OER for community workers who are implementing assets based approaches in different contexts. We argue that these approaches are negotiated in that one cannot decide how they might operate in a given context without engaging in deliberative discussion. The challenge for us as open education practitioners is how to turn those deliberations into OER and to highlight the important pedagogical aspect of the design process.

Electrolyte engineering toward efficient water splitting at mild pH

KAUST Repository

Shinagawa, Tatsuya

2017-08-28

The development of processes for the conversion of H2O/CO2 driven by electricity generated in renewable manners is essential to achieve sustainable energy and chemical cycles, in which the electrocatalytic oxygen evolution reaction (OER) is one of the bottlenecks. In this contribution, the influences of the electrolyte molarity and identity on OER at alkaline to neutral pH were investigated at an appreciable current density of ~10 mA cm-2, revealing (1) the clear boundary of reactant switching between H2O/OH- due to the diffusion limitation of OH- and (2) the substantial contribution of the mass transport of the buffered species in buffered mild pH conditions. These findings propose a strategy of electrolyte engineering: tuning the electrolyte properties to maximize the mass-transport flux. The concept was successfully demonstrated for OER as well as overall water electrolysis in buffered mild pH conditions, shedding light on the development of practical solar fuel production systems.

Deriving aerosol scattering ratio using range-resolved lidar ratio

Indian Academy of Sciences (India)

2014-02-13

Feb 13, 2014 ... ratio (LDR) are used to suggest the type of aerosols. The altitude-dependent ... to the station and the experimentally measured lidar data. The 'model ... The integrated aerosol extinction profile with altitude-dependent S and k.

Development, optimisation, and application of ICP-SFMS methods for the measurement of isotope ratios

International Nuclear Information System (INIS)

Stuerup, S.

2000-07-01

The measurement of isotopic composition and isotope ratios in biological and environmental samples requires sensitive, precise, and accurate analytical techniques. The analytical techniques used are traditionally based on mass spectrometry, among these techniques is the ICP-SFMS technique, which became commercially available in the mid 1990s. This technique is characterised by high sensitivity, low background, and the ability to separate analyte signals from spectral interferences. These features are beneficial for the measurement of isotope ratios and enable the measurement of isotope ratios of elements, which it has not previously been possible to measure due to either spectral interferences or poor sensitivity. The overall purpose of the project was to investigate the potential of the single detector ICP-SFMS technique for the measurement of isotope ratios in biological and environmental samples. One part of the work has focused on the fundamental aspects of the ICP-SFMS technique with special emphasize on the features important to the measurement of isotope ratios, while another part has focused on the development, optimisation and application of specific methods for the measurement of isotope ratios of elements of nutritional interest and radionuclides. The fundamental aspects of the ICP-SFMS technique were investigated theoretically and experimentally by the measurement of isotope ratios applying different experimental conditions. It was demonstrated that isotope ratios could be measured reliably using ICP-SFMS by educated choice of acquisition parameters, scanning mode, mass discrimination correction, and by eliminating the influence of detector dead time. Applying the knowledge gained through the fundamental study, ICP-SFMS methods for the measurement of isotope ratios of calcium, zinc, molybdenum and iron in human samples and a method for the measurement of plutonium isotope ratios and ultratrace levels of plutonium and neptunium in environmental samples

Signal-to-noise ratio and MR tissue parameters in human brain imaging at 3, 7, and 9.4 tesla using current receive coil arrays.

Science.gov (United States)

Pohmann, Rolf; Speck, Oliver; Scheffler, Klaus

2016-02-01

Relaxation times, transmit homogeneity, signal-to-noise ratio (SNR) and parallel imaging g-factor were determined in the human brain at 3T, 7T, and 9.4T, using standard, tight-fitting coil arrays. The same human subjects were scanned at all three field strengths, using identical sequence parameters and similar 31- or 32-channel receive coil arrays. The SNR of three-dimensional (3D) gradient echo images was determined using a multiple replica approach and corrected with measured flip angle and T2 (*) distributions and the T1 of white matter to obtain the intrinsic SNR. The g-factor maps were derived from 3D gradient echo images with several GRAPPA accelerations. As expected, T1 values increased, T2 (*) decreased and the B1 -homogeneity deteriorated with increasing field. The SNR showed a distinctly supralinear increase with field strength by a factor of 3.10 ± 0.20 from 3T to 7T, and 1.76 ± 0.13 from 7T to 9.4T over the entire cerebrum. The g-factors did not show the expected decrease, indicating a dominating role of coil design. In standard experimental conditions, SNR increased supralinearly with field strength (SNR ∼ B0 (1.65) ). To take full advantage of this gain, the deteriorating B1 -homogeneity and the decreasing T2 (*) have to be overcome. © 2015 Wiley Periodicals, Inc.