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Sample records for nanotubes hidden roles

  1. Insight: Exploring Hidden Roles in Collaborative Play

    Directory of Open Access Journals (Sweden)

    Tricia Shi

    2015-06-01

    Full Text Available This paper looks into interaction modes between players in co-located, collaborative games. In particular, hidden traitor games, in which one or more players is secretly working against the group mission, has the effect of increasing paranoia and distrust between players, so this paper looks into the opposite of a hidden traitor – a hidden benefactor. Rather than sabotaging the group mission, the hidden benefactor would help the group achieve the end goal while still having a reason to stay hidden. The paper explores what games with such a role can look like and how the role changes player interactions. Finally, the paper addresses the divide between video game and board game interaction modes; hidden roles are not common within video games, but they are of growing prevalence in board games. This fact, combined with the exploration of hidden benefactors, reveals that hidden roles is a mechanic that video games should develop into in order to match board games’ complexity of player interaction modes.

  2. Hidden Costs and the Role of Modularity

    DEFF Research Database (Denmark)

    Larsen, Marcus M.

    2013-01-01

    that the inability to effectively estimate the costs of implementing an activity in a foreign location has a negative impact on the process performance of that activity. Performance is deterred as operations are likely to be disrupted by opportunity costs and managerial responses. However, this relationship......This paper addresses estimation errors in strategic decision-making processes due to hidden costs. While previous research has investigated the antecedents of hidden costs, this paper investigates performance consequences. Using unique data on 221 offshoring implementations, it is argued...... is mitigated by the degree of modularity in the activity as it reduces the need for costly coordination in offshoring. This paper contributes to research on offshoring and strategic decision-making by emphasizing the importance of organizational design and of estimating the costs of internal organizational...

  3. The Hidden Roles of the School Librarian

    Science.gov (United States)

    Novotny, Rebecca Maria

    2017-01-01

    Purpose: The purpose of this mixed methods study was to define the roles of school librarians as perceived by librarians and principals in regard to the ALA/AASL Standards for the Initial Preparation of School Librarians (2010). This study was designed to explore the perceptions of librarians and principals on the role of the librarian in the…

  4. Combating hidden hunger: the role of international agencies.

    Science.gov (United States)

    Dalmiya, Nita; Schultink, Werner

    2003-12-01

    The importance of micronutrient deficiencies or "hidden hunger" was clearly emphasized by the inclusion of specific goals on iron, vitamin A, and iodine deficiency at the 1990 World Summit for Children and other major international nutrition conferences. Significant progress has since been made toward eliminating vitamin A and iodine deficiencies, with less progress made toward reducing the burden of iron-deficiency anemia. The role of international agencies, such as the World Health Organization, United Nations Children's Fund, Food and Agricultural Organization, and World Bank in assisting countries to make progress toward the World Summit for Children goals has been very important. International agencies have played a critical role in advocating for and raising awareness of these issues at the international, regional, and national levels among policymakers and the general population. Using a rights-based approach, UNICEF and other agencies have been instrumental in elevating to the highest political level the discussion of every child's right to adequate nutrition. International agencies have also been very supportive at the national level in providing technical guidance for programs, including monitoring and evaluation. These agencies have played a critical role in engaging the cooperation of other partners, including bilateral donors, non-governmental organizations, and the private sector for micronutrient programs. Furthermore, international agencies provide financial and material support for micronutrient programs. In the future, such agencies must continue to be heavily involved in programs to achieve the newly confirmed goals for 2010. The present paper focuses on the role of international agencies in combating micronutrient deficiencies, drawing on the lessons learned over the last decade. The first section of the paper summarizes the progress achieved since 1990, and the second section describes the specific role of international agencies in contributing

  5. Organising Water: The Hidden Role of Intermediary Work

    Directory of Open Access Journals (Sweden)

    Timothy Moss

    2009-02-01

    Full Text Available The increasingly complex challenges of making water management more sustainable require a critical and detailed understanding of the social organisation of water. This paper examines the hitherto neglected role that 'intermediary' organisations play in reshaping the relations between the provision and use of water and sanitation services. In response to new regulatory, environmental, social, and commercial pressures the relationships between water utilities, consumers, and regulators are changing, creating openings for both new and existing organisations to take on intermediary functions. Drawing on recent EU-funded research we provide the first systematic analysis of intermediary organisations in the European water sector, examining the contexts of their emergence, the ways they work, the functions they perform, and the impacts they can have. With a combination of conceptual and empirical analysis we substantiate and elaborate the case for appreciating the often hidden work of intermediaries. We caution, however, against over-simplistic conclusions on harnessing this potential, highlighting instead the need to reframe perspectives on how water is organised to contemplate actor constellations and interactions beyond the common triad of provider, consumer, and regulator.

  6. Correction to: The hidden therapist: evidence for a central role of music in psychedelic therapy.

    Science.gov (United States)

    Kaelen, Mendel; Giribaldi, Bruna; Raine, Jordan; Evans, Lisa; Timmermann, Christopher; Rodriguez, Natalie; Roseman, Leor; Feilding, Amanda; Nutt, David; Carhart-Harris, Robin

    2018-05-01

    The article The hidden therapist: evidence for a central role of music in psychedelic therapy, written by Mendel Kaelen, Bruna Giribaldi, Jordan Raine, Lisa Evans, Christopher Timmerman, Natalie Rodriguez, Leor Roseman, Amanda Feilding, David Nutt, Robin Carhart-Harris, was originally published electronically on the publisher's internet portal.

  7. The role of food and nutrition system approaches in tackling hidden hunger.

    Science.gov (United States)

    Burchi, Francesco; Fanzo, Jessica; Frison, Emile

    2011-02-01

    One of the World's greatest challenges is to secure sufficient and healthy food for all, and to do so in an environmentally sustainable manner. This review explores the interrelationships of food, health, and environment, and their role in addressing chronic micronutrient deficiencies, also known as "hidden hunger", affecting over two billion people worldwide. While the complexity and underlying determinants of undernutrition have been well-understood for decades, the scaling of food and nutrition system approaches that combine sustainable agriculture aimed at improved diet diversity and livelihoods have been limited in their development and implementation. However, an integrated system approach to reduce hidden hunger could potentially serve as a sustainable opportunity.

  8. Bokanmeldelse: "Fooled by randomness : the hidden role of chance in the markets and in life" / Nassim Nicholas Taleb

    OpenAIRE

    Sommervoll, Dag Einar

    2007-01-01

    Artikkelen er gjengitt med tillatelse fra Samfunnsøkonomenes Forening. Bokanmeldelse av: Taleb, Nassim Nicholas (2005) "Fooled by randomness : the hidden role of chance in the markets and in life", New York: Random House.

  9. The Role of Food and Nutrition System Approaches in Tackling Hidden Hunger

    Directory of Open Access Journals (Sweden)

    Emile Frison

    2011-01-01

    Full Text Available One of the World’s greatest challenges is to secure sufficient and healthy food for all, and to do so in an environmentally sustainable manner. This review explores the interrelationships of food, health, and environment, and their role in addressing chronic micronutrient deficiencies, also known as “hidden hunger”, affecting over two billion people worldwide. While the complexity and underlying determinants of undernutrition have been well-understood for decades, the scaling of food and nutrition system approaches that combine sustainable agriculture aimed at improved diet diversity and livelihoods have been limited in their development and implementation. However, an integrated system approach to reduce hidden hunger could potentially serve as a sustainable opportunity.

  10. The role of defects in the design of space elevator cable: From nanotube to megatube

    Energy Technology Data Exchange (ETDEWEB)

    Pugno, Nicola M. [Department of Structural Engineering and Geotechnics, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin (Italy)], E-mail: nicola.pugno@polito.it

    2007-09-15

    Researchers are claiming that the feasibility of space elevator cable is now realistic, thanks to carbon nanotube technology, proposing its realization within a decade. However, the current view of basing the design of the megacable on the theoretical strength of a single carbon nanotube is naive, as has recently been emphasized. In this paper the role of thermodynamically unavoidable atomistic defects with different size and shape is quantified on brittle fracture, fatigue and elasticity, for nanotubes and nanotube bundles. Nonasymptotic regimes, elastic plasticity, rough cracks, finite domains and size effects are also discussed. The results are compared with atomistic simulations and nanotensile tests of carbon nanotubes. Key simple formulas for the design of a flaw-tolerant space elevator megacable are reported, suggesting that it would need a taper ratio (for uniform stress) of about two orders of magnitude larger than currently proposed.

  11. Sociology of Hidden Curriculum

    Directory of Open Access Journals (Sweden)

    Alireza Moradi

    2017-06-01

    Full Text Available This paper reviews the concept of hidden curriculum in the sociological theories and wants to explain sociological aspects of formation of hidden curriculum. The main question concentrates on the theoretical approaches in which hidden curriculum is explained sociologically.For this purpose it was applied qualitative research methodology. The relevant data include various sociological concepts and theories of hidden curriculum collected by the documentary method. The study showed a set of rules, procedures, relationships and social structure of education have decisive role in the formation of hidden curriculum. A hidden curriculum reinforces by existed inequalities among learners (based on their social classes or statues. There is, in fact, a balance between the learner's "knowledge receptions" with their "inequality proportion".The hidden curriculum studies from different major sociological theories such as Functionalism, Marxism and critical theory, Symbolic internationalism and Feminism. According to the functionalist perspective a hidden curriculum has a social function because it transmits social values. Marxists and critical thinkers correlate between hidden curriculum and the totality of social structure. They depicts that curriculum prepares learners for the exploitation in the work markets. Symbolic internationalism rejects absolute hegemony of hidden curriculum on education and looks to the socialization as a result of interaction between learner and instructor. Feminism theory also considers hidden curriculum as a vehicle which legitimates gender stereotypes.

  12. Role-modelling and the hidden curriculum: New graduate nurses' professional socialisation.

    Science.gov (United States)

    Hunter, Kiri; Cook, Catherine

    2018-05-12

    To explore new graduate nurses' experiences of professional socialisation by registered nurses in hospital-based practice settings, and identify strategies that support professional identity development. Professionalism is reinforced and stabilised in the clinical environment through the 'hidden curriculum', with major learning coming from practice role-models. New graduates observe attitudes, behaviours, decision-making and skills, and gain feedback from registered nurses, which they translate into their own practice. Professional socialisation occurs through encounters with desirable and undesirable role-modelling; both are significant in professional identity formation. Qualitative descriptive design. Data collection was undertaken through semi-structured interviews with five new graduate nurse participants. A general inductive approach guided analysis. The meaningful descriptions gained provided insight into their experiences. Three main themes identified from the data include: 'Lessons from the wilderness'; 'Life in the wild'; and 'Belonging to a wolf pack'. The data set highlighted the major transitional process from student identity to registered nurse. New graduates' rethinking of beliefs and professional nursing identities were influenced by organisational pressures and experienced nurses role-modelling practices contrary to professional values. Despite encountering a range of professional behaviours, attitudes and dilemmas, new graduates were capable of moral agency and critical thinking. However, they rapidly acculturated and described compromises to cope. To promote high morale and a sense of belonging, a concerted effort is required by all nurses to facilitate the socialisation process to encourage self-authorship. A well-developed professional identity enhances nursing as a profession, contributing towards better healthcare delivery and outcomes. It is critically important how professional values are learnt within the culture of nursing. Tensions in

  13. Role of contact bonding on electronic transport in metal-carbon nanotube-metal systems

    International Nuclear Information System (INIS)

    Deretzis, I; La Magna, A

    2006-01-01

    We have investigated the effects of the interfacial bond arrangement on the electronic transport features of metal-nanotube-metal systems. The transport properties of finite, defect-free armchair and zigzag single-walled carbon nanotubes attached to Au(111) metallic contacts have been calculated by means of the non-equilibrium Green functional formalism with the tight-binding and the extended Hueckel Hamiltonians. Our calculations show that the electrode material is not the only factor which rules contact transparency. Indeed, for the same electrode, but changing nanotube helicities, we have observed an overall complex behaviour of the transmission spectra due to band mixing and interference. A comparison of the two models shows that the tight-binding approach fails to give a satisfactory representation of the transmission function when a more accurate description of the C-C and Au-C chemical bonds has to be considered. We have furthermore examined the effect of interface geometry variance on conduction and found that the contact-nanotube distance has a significant impact, while the contact-nanotube symmetry plays a marginal, yet evident role

  14. Hidden Liquidity

    OpenAIRE

    Cebiroglu, Gökhan; Horst, Ulrich

    2012-01-01

    We cross-sectionally analyze the presence of aggregated hidden depth and trade volume in the S&P 500 and identify its key determinants. We find that the spread is the main predictor for a stock’s hidden dimension, both in terms of traded and posted liquidity. Our findings moreover suggest that large hidden orders are associated with larger transaction costs, higher price impact and increased volatility. In particular, as large hidden orders fail to attract (latent) liquidity to the market, hi...

  15. The hidden challenges in role transitions and how leadership coaching can help new leaders find solid ground.

    Science.gov (United States)

    Weinstock, Beth

    2011-01-01

    Leadership coaching is becoming an increasingly important intervention that helps individual nurse executives and managers develop and use the best of their strengths, gifts, and talents. As the need for leadership in nursing becomes urgent and brave souls move into the positions of greater authority and potential impact, they will face challenges as they move up in rank. This article identifies the hidden and often-overlooked challenges that are faced by new leaders as they transition into roles of increased responsibility, and it demonstrates how leadership coaching can help new leaders make successful transitions. As the current health care crisis creates opportunity for new leaders, those who opt for promotions and lateral shifts encounter both expected and surprising challenges. The expected challenges include mastering new content skills, learning new organizational structures, and getting to know new teams. The less obvious stressors include issues of self-esteem, assertiveness, self-consciousness, self-criticism, perfectionism, new boundaries, changing identities, and finding one's own leadership style. These important issues are often kept out of conscious awareness and overlooked at great cost to the individual leader and her institution. Leadership coaching can provide support and practical strategies for managing and overcoming these hidden challenges.

  16. A possible role of the dipole moment of the catalyst droplet in nanotube growth, alignment, chirality, and characteristics

    International Nuclear Information System (INIS)

    Mohammad, S Noor

    2012-01-01

    Why vapor species land on the surface of the nanoparticle seed for nanotube synthesis is a vital question. An investigation has been carried out to find an answer to it. For this, a model of the dipole moment has been developed. A bimetallic alloy (non-alloy, solid solution) exhibiting the shape of a cap has been assumed to function as the nanoparticle seed. Various features of the dipole moment have been examined. The influence of the dipole moment on nanotube synthesis, alignment, chirality, and characteristics has also been studied. Available experiments on the synthesis of carbon nanotubes employing bimetallic catalysts have been compared with the results from calculations. Close correspondence between the two demonstrates that the catalysts may exhibit a dipole moment and have a crucial role in nanotube synthesis and characteristics. The dipole moment has also been employed to determine why some nanotubes grow vertically, while others are bent. Calculated results appear to explain the basic causes for this. These results suggest that the electric field resulting from the dipole moment of catalysts may be important for the vertical alignment of nanotubes. They may attest to the validity of the model and to the existence of a dipole moment in seeds. Although considered for nanotube syntheses, the results may be applicable to other nanomaterials (nanotubes, nanowires, nanodots). (paper)

  17. Reviews and syntheses: Hidden forests, the role of vegetated coastal habitats in the ocean carbon budget

    Science.gov (United States)

    Duarte, Carlos M.

    2017-01-01

    Vegetated coastal habitats, including seagrass and macroalgal beds, mangrove forests and salt marshes, form highly productive ecosystems, but their contribution to the global carbon budget remains overlooked, and these forests remain hidden in representations of the global carbon budget. Despite being confined to a narrow belt around the shoreline of the world's oceans, where they cover less than 7 million km2, vegetated coastal habitats support about 1 to 10 % of the global marine net primary production and generate a large organic carbon surplus of about 40 % of their net primary production (NPP), which is either buried in sediments within these habitats or exported away. Large, 10-fold uncertainties in the area covered by vegetated coastal habitats, along with variability about carbon flux estimates, result in a 10-fold bracket around the estimates of their contribution to organic carbon sequestration in sediments and the deep sea from 73 to 866 Tg C yr-1, representing between 3 % and 1/3 of oceanic CO2 uptake. Up to 1/2 of this carbon sequestration occurs in sink reservoirs (sediments or the deep sea) beyond these habitats. The organic carbon exported that does not reach depositional sites subsidizes the metabolism of heterotrophic organisms. In addition to a significant contribution to organic carbon production and sequestration, vegetated coastal habitats contribute as much to carbonate accumulation as coral reefs do. While globally relevant, the magnitude of global carbon fluxes supported by salt-marsh, mangrove, seagrass and macroalgal habitats is declining due to rapid habitat loss, contributing to loss of CO2 sequestration, storage capacity and carbon subsidies. Incorporating the carbon fluxes' vegetated coastal habitats' support into depictions of the carbon budget of the global ocean and its perturbations will improve current representations of the carbon budget of the global ocean.

  18. Families and health-care professionals' perspectives and expectations of family-centred care: hidden expectations and unclear roles.

    Science.gov (United States)

    Coyne, Imelda

    2015-10-01

    Family-centred care (FCC) is viewed as a pivotal concept in the provision of high-quality nursing care for children and their families, yet implementation continues to be problematic worldwide. This research investigated how FCC was enacted from families and nurses' perspectives. Descriptive qualitative approach using elements of analysis from grounded theory method. Data were collected though individual interviews with 18 children aged 7-16 years, their parents (n = 18) and 18 nurses from two children's hospital and one children's unit in a large general hospital in Ireland. Four key themes were identified: expectations; relying on parents' help; working out roles; and barriers to FCC. Nurses wholeheartedly endorsed FCC because of the benefits for families and their reliance on parents' contribution to the workload. There was minimal evidence of collaboration or negotiation of roles which resulted in parents feeling stressed or abandoned. Nurses cited busy workload, under-staffing and inappropriate documentation as key factors which resulted in over-reliance on parents and hindered their efforts to negotiate and work alongside parents. Families are willing to help in their child's care but they require clear guidance, information and support from nurses. Hidden expectations and unclear roles are stressful for families. Nurses need skills training, adequate resources and managerial support to meet families' needs appropriately, to establish true collaboration and to deliver optimal family-centred care. © 2013 John Wiley & Sons Ltd.

  19. The Role of Multi-wall Carbon Nanotubes on Fracture Mechanism of Epoxy Nanocomposite

    Directory of Open Access Journals (Sweden)

    M. Hooshiar Sadegian

    2008-12-01

    Full Text Available In order to investigate the role of multi-wall carbon nanotubes (MWCNTs on fracture mechanism of epoxy nanocomposites, a series of tensile standard specimens reinforced with different carbon nanotube contents (0, 0.3, 0.6 and 1 wt% were produced. The fracture surfaces of the produced nanocomposites were evaluated using scanning electron microscope (SEM. The results show that the surface fracture of epoxy nanocomposites comprised of three regions, i.e. mirror, transition and final propagation zones. The extension of all zones depends strongly on curing agent as well asMWCNTs content. The mirror zone is disappeared as curing agent and MWCNTs content increases, while the transition zone depends on the nucleation rate of secondary microcrack. The pattern of final propagation zone becomes coarser as MWCNTs are added to epoxy system.

  20. Role of adsorbed surfactant in the reaction of aryl diazonium salts with single-walled carbon nanotubes.

    Science.gov (United States)

    Hilmer, Andrew J; McNicholas, Thomas P; Lin, Shangchao; Zhang, Jingqing; Wang, Qing Hua; Mendenhall, Jonathan D; Song, Changsik; Heller, Daniel A; Barone, Paul W; Blankschtein, Daniel; Strano, Michael S

    2012-01-17

    Because covalent chemistry can diminish the optical and electronic properties of single-walled carbon nanotubes (SWCNTs), there is significant interest in developing methods of controllably functionalizing the nanotube sidewall. To date, most attempts at obtaining such control have focused on reaction stoichiometry or strength of oxidative treatment. Here, we examine the role of surfactants in the chemical modification of single-walled carbon nanotubes with aryl diazonium salts. The adsorbed surfactant layer is shown to affect the diazonium derivatization of carbon nanotubes in several ways, including electrostatic attraction or repulsion, steric exclusion, and direct chemical modification of the diazonium reactant. Electrostatic effects are most pronounced in the cases of anionic sodium dodecyl sulfate and cationic cetyltrimethylammonium bromide, where differences in surfactant charge can significantly affect the ability of the diazonium ion to access the SWCNT surface. For bile salt surfactants, with the exception of sodium cholate, we find that the surfactant wraps tightly enough such that exclusion effects are dominant. Here, sodium taurocholate exhibits almost no reactivity under the explored reaction conditions, while for sodium deoxycholate and sodium taurodeoxycholate, we show that the greatest extent of reaction is observed among a small population of nanotube species, with diameters between 0.88 and 0.92 nm. The anomalous reaction of nanotubes in this diameter range seems to imply that the surfactant is less effective at coating these species, resulting in a reduced surface coverage on the nanotube. Contrary to the other bile salts studied, sodium cholate enables high selectivity toward metallic species and small band gap semiconductors, which is attributed to surfactant-diazonium coupling to form highly reactive diazoesters. Further, it is found that the rigidity of anionic surfactants can significantly influence the ability of the surfactant layer to

  1. Implicit bias against sexual minorities in medicine: cycles of professional influence and the role of the hidden curriculum.

    Science.gov (United States)

    Fallin-Bennett, Keisa

    2015-05-01

    Despite many recent advances in rights for sexual and gender minorities in the United States, bias against lesbian, gay, bisexual, and transgender (LGBT) people still exists. In this Commentary, the author briefly reviews disparities with regard to LGBT health, in both health care and medical education, and discusses the implications of Burke and colleagues’ study of implicit and explicit biases against lesbian and gay people among heterosexual first-year medical students, published in this issue of Academic Medicine. Emphasis is placed on the ways in which physicians’ implicit bias against LGBT people can create a cycle that perpetuates a professional climate reinforcing the bias. The hidden curriculum in academic health centers is discussed as both a cause of this cycle and as a starting point for a research and intervention agenda. The findings from Burke and colleagues’ study, as well as other evidence, support raising awareness of LGBT discrimination, increasing exposure to LGBT individuals as colleagues and role models in academic health centers, and modifying medical education curricula as methods to break the cycle of implicit bias in medicine.

  2. The role of the gas species on the formation of carbon nanotubes during thermal chemical vapour deposition

    International Nuclear Information System (INIS)

    Ohashi, Fumitaka; Chen, Guan Yow; Stolojan, Vlad; Silva, S Ravi P

    2008-01-01

    In this paper, we investigate the several roles that hydrogen plays in the catalytic growth of carbon nanotubes from the point of view of gas species, catalyst activation and subsequent interaction with the carbon nanotubes. Carbon nanotubes and nanofibres were grown by thermal chemical vapour deposition, using methane and a mixture of hydrogen and helium, for a range of growth temperatures and pre-treatment procedures. Long, straight carbon nanotubes were obtained at 900 deg. C, and although the growth yield increases with the growth temperature, the growth shifts from nanotubes to nanofibres. By introducing a helium purge as part of the pre-treatment procedure, we change the gas chemistry by altering the hydrogen concentration in the initial reaction stage. This simple change in the process resulted in a clear difference in the yield and the structure of the carbon nanofibres produced. We find that the hydrogen concentration in the initial reaction stage significantly affects the morphology of carbon fibres. Although hydrogen keeps the catalyst activated and increases the yield, it prevents the formation of graphitic nanotubes.

  3. The Hidden Roles That Management Partners Play In Accountable Care Organizations.

    Science.gov (United States)

    Lewis, Valerie A; D'Aunno, Thomas; Murray, Genevra F; Shortell, Stephen M; Colla, Carrie H

    2018-02-01

    Accountable care organizations (ACOs) are often discussed and promoted as driven by physicians, hospitals, and other health care providers. However, because of the flexible nature of ACO contracts, management organizations may also become partners in ACOs. We used data from 2013-15 on 276 ACOs from the National Survey of Accountable Care Organizations to understand the prevalence of nonprovider management partners' involvement in ACOs, the services these partners provide, and the structure of ACOs that have such partners. We found that 37 percent of ACOs reported having a management partner, and two-thirds of these ACOs reported that the partner shared in the financial risks or rewards. Among ACOs with partners, 94 percent had data services provided by the partner, 87 percent received administrative services, 68 percent received educational services, and 66 percent received care coordination services. Half received all four of these services from their partner. ACOs with partners were more heavily primary care than other ACOs. ACOs with and without partners had similar performance on costs and quality in Medicare ACO programs. Our findings suggest that management partners play a central role in many ACOs, perhaps supplying smaller and physician-run ACOs with services or expertise perceived as necessary for ACO success.

  4. Hidden keys to survival: the type, density, pattern and functional role of emperor penguin body feathers.

    Science.gov (United States)

    Williams, Cassondra L; Hagelin, Julie C; Kooyman, Gerald L

    2015-10-22

    Antarctic penguins survive some of the harshest conditions on the planet. Emperor penguins breed on the sea ice where temperatures drop below -40°C and forage in -1.8°C waters. Their ability to maintain 38°C body temperature in these conditions is due in large part to their feathered coat. Penguins have been reported to have the highest contour feather density of any bird, and both filoplumes and plumules (downy feathers) are reported absent in penguins. In studies modelling the heat transfer properties and the potential biomimetic applications of penguin plumage design, the insulative properties of penguin plumage have been attributed to the single afterfeather attached to contour feathers. This attribution of the afterfeather as the sole insulation component has been repeated in subsequent studies. Our results demonstrate the presence of both plumules and filoplumes in the penguin body plumage. The downy plumules are four times denser than afterfeathers and play a key, previously overlooked role in penguin survival. Our study also does not support the report that emperor penguins have the highest contour feather density. © 2015 The Author(s).

  5. The hidden therapist: evidence for a central role of music in psychedelic therapy.

    Science.gov (United States)

    Kaelen, Mendel; Giribaldi, Bruna; Raine, Jordan; Evans, Lisa; Timmerman, Christopher; Rodriguez, Natalie; Roseman, Leor; Feilding, Amanda; Nutt, David; Carhart-Harris, Robin

    2018-02-01

    Recent studies have supported the safety and efficacy of psychedelic therapy for mood disorders and addiction. Music is considered an important component in the treatment model, but little empirical research has been done to examine the magnitude and nature of its therapeutic role. The present study assessed the influence of music on the acute experience and clinical outcomes of psychedelic therapy. Semi-structured interviews inquired about the different ways in which music influenced the experience of 19 patients undergoing psychedelic therapy with psilocybin for treatment-resistant depression. Interpretative phenomenological analysis was applied to the interview data to identify salient themes. In addition, ratings were given for each patient for the extent to which they expressed "liking," "resonance" (the music being experienced as "harmonious" with the emotional state of the listener), and "openness" (acceptance of the music-evoked experience). Analyses of the interviews revealed that the music had both "welcome" and "unwelcome" influences on patients' subjective experiences. Welcome influences included the evocation of personally meaningful and therapeutically useful emotion and mental imagery, a sense of guidance, openness, and the promotion of calm and a sense of safety. Conversely, unwelcome influences included the evocation of unpleasant emotion and imagery, a sense of being misguided and resistance. Correlation analyses showed that patients' experience of the music was associated with the occurrence of "mystical experiences" and "insightfulness." Crucially, the nature of the music experience was significantly predictive of reductions in depression 1 week after psilocybin, whereas general drug intensity was not. This study indicates that music plays a central therapeutic function in psychedelic therapy.

  6. The role of linked phospholipids in the rubber-filler interaction in carbon nanotube (CNT) filler natural rubber (NR) composites

    NARCIS (Netherlands)

    Le, H.H.; Abhijeet, S.; Ilish, S.; Klehm, J.; Henning, S.; Beiner, M.; Sarkawi, S.S.; Dierkes, Wilma K.; Das, A.; Fischer, D.; Stöckelhuber, K.-W.; Wiessner, S.; Khatiwada, S.P.; Adhikari, R.; Pham, T.; Heinrich, G.; Radusch, H.-J.

    2014-01-01

    The aim of the present work is to evidence the role of the linked phospholipids of natural rubber (NR) in the rubber-carbon nanotube (CNT) interactions in rubber composites. Three rubbers namely NR, deproteinized NR (DPNR) and a synthetic rubber isoprene (IR) were used as matrix for CNTs. The

  7. Role of inter-tube coupling and quantum interference on electrical transport in carbon nanotube junctions

    Science.gov (United States)

    Tripathy, Srijeet; Bhattacharyya, Tarun Kanti

    2016-09-01

    Due to excellent transport properties, Carbon nanotubes (CNTs) show a lot of promise in sensor and interconnect technology. However, recent studies indicate that the conductance in CNT/CNT junctions are strongly affected by the morphology and orientation between the tubes. For proper utilization of such junctions in the development of CNT based technology, it is essential to study the electronic properties of such junctions. This work presents a theoretical study of the electrical transport properties of metallic Carbon nanotube homo-junctions. The study focuses on discerning the role of inter-tube interactions, quantum interference and scattering on the transport properties on junctions between identical tubes. The electronic structure and transport calculations are conducted with an Extended Hückel Theory-Non Equilibrium Green's Function based model. The calculations indicate conductance to be varying with a changing crossing angle, with maximum conductance corresponding to lattice registry, i.e. parallel configuration between the two tubes. Further calculations for such parallel configurations indicate onset of short and long range oscillations in conductance with respect to changing overlap length. These oscillations are attributed to inter-tube coupling effects owing to changing π orbital overlap, carrier scattering and quantum interference of the incident, transmitted and reflected waves at the inter-tube junction.

  8. Role of carbon nanotubes (CNTs) in improving wear properties of polypropylene (PP) in dry sliding condition

    International Nuclear Information System (INIS)

    Ashok Gandhi, R.; Palanikumar, K.; Ragunath, B.K.; Paulo Davim, J.

    2013-01-01

    Highlights: ► Role of carbon nanotubes (CNTs) on wear behaviour of polypropylene (PP) is evaluated. ► Effect of applied pressure and composition against a steel counter face is investigated. ► Microstructure and worn surfaces of samples are observed by scanning electron microscope. ► The wear phenomenon has been discussed based on wear losses and worn surfaces. ► The coefficient of friction (μ) and sliding time for PP and PP/CNT blend is investigated. - Abstract: Polymers are widely used for sliding couples against metals and other materials. Polypropylene is a polymer used in variety of applications includes packaging, laboratory equipments, automotive components, etc. Polypropylene is often desirable automotive material due to its low cost, colorability, chemical resistance and UV stability. In addition the range of potential polypropylene uses is nearly unlimited through the use of modifiers, additives and fillers. In the present work, the sliding wear of polypropylene (PP) and carbon nanotube (CNT) blends are evaluated as a function of applied load and composition against a steel counter face in dry condition. The addition of CNT in PP in wear performance is investigated and presented in detail. Microstructure and worn surfaces of samples were observed by scanning electron microscope. The wear phenomenon has been discussed based on wear losses and worn surfaces

  9. Random walks in nanotube composites: Improved algorithms and the role of thermal boundary resistance

    International Nuclear Information System (INIS)

    Duong, Hai M.; Papavassiliou, Dimitrios V.; Lee, Lloyd L.; Mullen, Kieran J.

    2005-01-01

    Random walk simulations of thermal walkers are used to study the effect of interfacial resistance on heat flow in randomly dispersed carbon nanotube composites. The adopted algorithm effectively makes the thermal conductivity of the nanotubes themselves infinite. The probability that a walker colliding with a matrix-nanotube interface reflects back into the matrix phase or crosses into the carbon nanotube phase is determined by the thermal boundary (Kapitza) resistance. The use of 'cold' and 'hot' walkers produces a steady state temperature profile that allows accurate determination of the thermal conductivity. The effects of the carbon nanotube orientation, aspect ratio, volume fraction, and Kapitza resistance on the composite effective conductivity are quantified

  10. Hidden loss

    DEFF Research Database (Denmark)

    Kieffer-Kristensen, Rikke; Johansen, Karen Lise Gaardsvig

    2013-01-01

    to participate. RESULTS: All children were affected by their parents' ABI and the altered family situation. The children's expressions led the authors to identify six themes, including fear of losing the parent, distress and estrangement, chores and responsibilities, hidden loss, coping and support. The main......PRIMARY OBJECTIVE: The purpose of this study was to listen to and learn from children showing high levels of post-traumatic stress symptoms after parental acquired brain injury (ABI), in order to achieve an in-depth understanding of the difficulties the children face in their everyday lives...... finding indicates that the children experienced numerous losses, many of which were often suppressed or neglected by the children to protect the ill parents. CONCLUSIONS: The findings indicated that the children seemed to make a special effort to hide their feelings of loss and grief in order to protect...

  11. The Hidden Costs of Offshoring

    DEFF Research Database (Denmark)

    Møller Larsen, Marcus; Manning, Stephan; Pedersen, Torben

    2011-01-01

    of offshoring. Specifically, we propose that hidden costs can be explained by the combination of increasing structural, operational and social complexity of offshoring activities. In addition, we suggest that firm orientation towards organizational design as part of an offshoring strategy and offshoring......This study seeks to explain hidden costs of offshoring, i.e. unexpected costs resulting from the relocation of business tasks and activities outside the home country. We develop a model that highlights the role of complexity, design orientation and experience in explaining hidden costs...... experience moderate the relationship between complexity and hidden costs negatively i.e. reduces the cost generating impact of complexity. We develop three hypotheses and test them on comprehensive data from the Offshoring Research Network (ORN). In general, we find support for our hypotheses. A key result...

  12. Detection of a periodic structure hidden in random background: the role of signal amplitude in the matched filter detection method

    International Nuclear Information System (INIS)

    Vani, V C; Chatterjee, S

    2010-01-01

    The matched filter method for detecting a periodic structure on a surface hidden behind randomness is known to detect up to (r 0 /Λ)≥0.11, where r 0 is the coherence length of light on scattering from the rough part and Λ is the wavelength of the periodic part of the surface-the above limit being much lower than what is allowed by conventional detection methods. The primary goal of this technique is the detection and characterization of the periodic structure hidden behind randomness without the use of any complicated experimental or computational procedures. This paper examines this detection procedure for various values of the amplitude a of the periodic part beginning from a=0 to small finite values of a. We thus address the importance of the following quantities: '(a/λ)', which scales the amplitude of the periodic part with the wavelength of light, and (r 0 /Λ), in determining the detectability of the intensity peaks.

  13. Hidden role of Maxwell superalgebras in the free differential algebras of D = 4 and D = 11 supergravity

    Science.gov (United States)

    Ravera, Lucrezia

    2018-03-01

    The purpose of this paper is to show that the so-called Maxwell superalgebra in four dimensions, which naturally involves the presence of a nilpotent fermionic generator, can be interpreted as a hidden superalgebra underlying N=1, {D}=4 supergravity extended to include a 2-form gauge potential associated to a 2-index antisymmetric tensor. In this scenario, the theory is appropriately discussed in the context of Free Differential Algebras (an extension of the Maurer-Cartan equations to involve higher-degree differential forms). The study is then extended to the Free Differential Algebra describing D = 11 supergravity, showing that, also in this case, there exists a super-Maxwell algebra underlying the theory. The same extra spinors dual to the nilpotent fermionic generators whose presence is crucial for writing a supersymmetric extension of the Maxwell algebras, both in the D = 4 and in the D = 11 case, turn out to be fundamental ingredients also to reproduce the D = 4 and D = 11 Free Differential Algebras on ordinary superspace, whose basis is given by the supervielbein. The analysis of the gauge structure of the supersymmetric Free Differential Algebras is carried on taking into account the gauge transformations from the hidden supergroup-manifold associated with the Maxwell superalgebras.

  14. The role of 'hidden' community volunteers in community-based health service delivery platforms: examples from sub-Saharan Africa.

    Science.gov (United States)

    Leon, Natalie; Sanders, David; Van Damme, Wim; Besada, Donela; Daviaud, Emmanuelle; Oliphant, Nicholas P; Berzal, Rocio; Mason, John; Doherty, Tanya

    2015-01-01

    Community-based research on child survival in sub-Saharan Africa has focussed on the increased provision of curative health services by a formalised cadre of lay community health workers (CHWs), but we have identified a particular configuration, that deserves closer scrutiny. We identified a two-tiered CHW system, with the first tier being the lessor known or 'hidden' community/village level volunteers and the second tier being formal, paid CHWs, in Ethiopia, Mali, and Niger. Whilst the disease-focussed tasks of the formal CHW tier may be more amenable to classic epidemiological surveillance, we postulate that understanding the relationship between formalised CHWs and volunteer cadres, in terms of scope, location of practice and ratio to population, would be important for a comprehensive evaluation of child survival in these countries. We report on the findings from our joint qualitative and quantitative investigations, highlighting the need to recognise the 'hidden' contribution of volunteers. We need to better characterize the volunteers' interaction with community-based and primary care services and to better understand ways to improve the volunteer systems with the right type of investments. This is particularly important for considering the models for scale-up of CHWs in sub-Saharan Africa.

  15. The role of the iron catalyst in the toxicity of multi-walled carbon nanotubes (MWCNTs).

    Science.gov (United States)

    Visalli, Giuseppa; Facciolà, Alessio; Iannazzo, Daniela; Piperno, Anna; Pistone, Alessandro; Di Pietro, Angela

    2017-09-01

    This study aimed to investigate the role of iron, used as a catalyst, in the biological response to pristine and functionalized multi-walled carbon nanotubes (p/fMWCNTs) with an iron content of 2.5-2.8%. Preliminarily, we assessed the pro-oxidant activity of MWCNTs-associated iron by an abiotic test. To evaluate iron bioavailability, we measured intracellular redox-active iron in A549 cells exposed to both MWCNT suspensions and to the cell medium preconditioned by MWCNTs, in order to assess the iron dissolution rate under physiological conditions. Moreover, in exposed cells, we detected ROS levels, 8-oxo-dG and mitochondrial function. The results clearly highlighted that MWCNTs- associated iron was not redox-active and that iron leakage did not occur under physiological conditions, including the oxidative burst of specialized cells. Despite this, in MWCNTs exposed cells, higher level of intracellular redox-active iron was measured in comparison to control and a significant time-dependent ROS increase was observed (P<0.01). Higher levels of 8-oxo-dG, a marker of oxidative DNA damage, and decreased mitochondrial function, confirmed the oxidative stress induced by MWCNTs. Based on the results we believe that oxidative damage could be attributable to the release of endogenous redox-active iron. This was due to the damage of acidic vacuolar compartment caused by endocytosis-mediated MWCNT internalization. Copyright © 2017 Elsevier GmbH. All rights reserved.

  16. The role of the substrate surface morphology and water in growth of vertically aligned single-walled carbon nanotubes.

    Science.gov (United States)

    Pint, Cary; Pheasant, Sean; Nicholas, Nolan; Horton, Charles; Hauge, Robert

    2008-11-01

    Growth of high quality, vertically aligned single-walled carbon nanotubes (carpets) is achieved using a rapid insertion hot filament chemical vapor deposition (HF-CVD) technique. The effect of the substrate morphology on growth is explored by comparing carpets grown on epitaxially polished MgO substrates to those grown on "as-cut", macroscopically rough MgO substrates. Depending on the substrate morphology, we observe differences in both the overall carpet morphology as well as the diameter distribution of nanotubes grown in the carpet based on optical measurements. In addition, we explore the role of water in the growth of carpets on MgO and the conventional Al2O3 coated Si substrates. We find that the addition of a small amount of water is beneficial to the growth rates of the SWNT carpets, enhancing the growth rates by up to eight times.

  17. Role of interfacial effects in carbon nanotube/epoxy nanocomposite behavior.

    Science.gov (United States)

    Pécastaings, G; Delhaès, P; Derré, A; Saadaoui, H; Carmona, F; Cui, S

    2004-09-01

    The interfacial effects are critical to understand the nanocomposite behavior based on polymer matrices. These effects are dependent upon the morphology of carbon nanotubes, the type of used polymer and the processing technique. Indeed, we show that the different parameters, as the eventual surfactant use, the ultrasonic treatment and shear mixing have to be carefully examined, in particular, for nanotube dispersion and their possible alignment. A series of multiwalled nanotubes (MWNT) have been mixed with a regular epoxy resin under a controlled way to prepare nanocomposites. The influence of nanotube content is examined through helium bulk density, glass transition temperature of the matrix and direct current electrical conductivity measurements. These results, including the value of the percolation threshold, are analyzed in relationship with the mesostructural organization of these nanotubes, which is observed by standard and conductive probe atomic force microscopy (AFM) measurements. The wrapping effect of the organic matrix along the nanotubes is evidenced and analyzed to get a better understanding of the final composite characteristics, in particular, for eventually reinforcing the matrix without covalent bonding.

  18. Role of intertube interactions in double- and triple-walled carbon nanotubes.

    Science.gov (United States)

    Hirschmann, Thomas Ch; Araujo, Paulo T; Muramatsu, Hiroyuki; Rodriguez-Nieva, Joaquin F; Seifert, Max; Nielsch, Kornelius; Kim, Yoong Ahm; Dresselhaus, Mildred S

    2014-02-25

    Resonant Raman spectroscopy studies are performed to access information about the intertube interactions and wall-to-wall distances in double- and triple-walled carbon nanotubes. Here, we explain how the surroundings of the nanotubes in a multiwalled system influence their radial breathing modes. Of particular interest, the innermost tubes in double- and triple-walled carbon nanotube systems are shown to be significantly shielded from environmental interactions, except for those coming from the intertube interaction with their own respective host tubes. From a comparison of the Raman results for bundled as well as individual fullerene-peapod-derived double- and triple-walled carbon nanotubes, we observe that metallic innermost tubes, when compared to their semiconducting counterparts, clearly show weaker intertube interactions. Additionally, we discuss a correlation between the wall-to-wall distances and the frequency upshifts of the radial breathing modes observed for the innermost tubes in individual double- and triple-walled carbon nanotubes. All results allow us to contemplate fundamental properties related to DWNTs and TWNTs, as for example diameter- and chirality-dependent intertube interactions. We also discuss differences in fullerene-peapod-derived and chemical vapor deposition grown double- and triple-walled systems with the focus on mechanical coupling and interference effects.

  19. Hidden variables and locality in quantum theory

    International Nuclear Information System (INIS)

    Shiva, Vandana.

    1978-12-01

    The status of hidden variables in quantum theory has been debated since the 1920s. The author examines the no-hidden-variable theories of von Neumann, Kochen, Specker and Bell, and finds that they all share one basic assumption: averaging over the hidden variables should reproduce the quantum mechanical probabilities. Von Neumann also makes a linearity assumption, Kochen and Specker require the preservation of certain functional relations between magnitudes, and Bell proposes a locality condition. It has been assumed that the extrastatistical requirements are needed to serve as criteria of success for the introduction of hidden variables because the statistical condition is trivially satisfied, and that Bell's result is based on a locality condition that is physically motivated. The author shows that the requirement of weak locality, which is not physically motivated, is enough to give Bell's result. The proof of Bell's inequality works equally well for any pair of commuting magnitudes satisfying a condition called the degeneracy principle. None of the no-hidden-variable proofs apply to a class of hidden variable theories that are not phase-space reconstructions of quantum mechanics. The author discusses one of these theories, the Bohm-Bub theory, and finds that hidden variable theories that re all the quantum statistics, for single and sequential measurements, must introduce a randomization process for the hidden variables after each measurement. The philosophical significance of this theory lies in the role it can play in solving the conceptual puzzles posed by quantum theory

  20. Beneficial role of carbon nanotubes on mustard plant growth: an agricultural prospect

    Science.gov (United States)

    Mondal, Anindita; Basu, Ruma; Das, Sukhen; Nandy, Papiya

    2011-10-01

    Nowadays an increasing application of nanotechnology in different fields has arisen an extensive debate about the effect of the engineered nanoparticles on environment . Phytotoxicity of nanoparticles has come into limelight in the last few years. However, very few studies have been done so far on the beneficial aspects of nanoparticles on plants. In this article, we report the beneficial effect of multi-walled carbon nanotubes (MWCNTs) having diameter of 30 nm on Brassica juncea (mustard) seeds. Measurements of germination rate, T 50 (time taken for 50% germination), shoot and root growth have shown encouraging results using low concentration of oxidized MWCNT (OMWCNT) treated seeds as compared to non-oxidized as well as high concentration OMWCNT treated seeds. For toxicity study we measured the germination index and relative root elongation, while conductivity test and infra-red spectra were also performed to study the overall effect of oxidized and non-oxidized nanotubes on mustard seeds and seedlings.

  1. Beneficial role of carbon nanotubes on mustard plant growth: an agricultural prospect

    International Nuclear Information System (INIS)

    Mondal, Anindita; Basu, Ruma; Das, Sukhen; Nandy, Papiya

    2011-01-01

    Nowadays an increasing application of nanotechnology in different fields has arisen an extensive debate about the effect of the engineered nanoparticles on environment. Phytotoxicity of nanoparticles has come into limelight in the last few years. However, very few studies have been done so far on the beneficial aspects of nanoparticles on plants. In this article, we report the beneficial effect of multi-walled carbon nanotubes (MWCNTs) having diameter of ∼30 nm on Brassica juncea (mustard) seeds. Measurements of germination rate, T 50 (time taken for 50% germination), shoot and root growth have shown encouraging results using low concentration of oxidized MWCNT (OMWCNT) treated seeds as compared to non-oxidized as well as high concentration OMWCNT treated seeds. For toxicity study we measured the germination index and relative root elongation, while conductivity test and infra-red spectra were also performed to study the overall effect of oxidized and non-oxidized nanotubes on mustard seeds and seedlings.

  2. POVMs and hidden variables

    International Nuclear Information System (INIS)

    Stairs, Allen

    2007-01-01

    Recent results by Paul Busch and Adan Cabello claim to show that by appealing to POVMs, non-contextual hidden variables can be ruled out in two dimensions. While the results of Busch and Cabello are mathematically correct, interpretive problems render them problematic as no hidden variable proofs

  3. Partially Hidden Markov Models

    DEFF Research Database (Denmark)

    Forchhammer, Søren Otto; Rissanen, Jorma

    1996-01-01

    Partially Hidden Markov Models (PHMM) are introduced. They differ from the ordinary HMM's in that both the transition probabilities of the hidden states and the output probabilities are conditioned on past observations. As an illustration they are applied to black and white image compression where...

  4. Effect of carbon nanotube functionalization on mechanical and thermal properties of cross-linked epoxy-carbon nanotube nanocomposites: role of strengthening the interfacial interactions.

    Science.gov (United States)

    Khare, Ketan S; Khabaz, Fardin; Khare, Rajesh

    2014-05-14

    We have used amido-amine functionalized carbon nanotubes (CNTs) that form covalent bonds with cross-linked epoxy matrices to elucidate the role of the matrix-filler interphase in the enhancement of mechanical and thermal properties in these nanocomposites. For the base case of nanocomposites of cross-linked epoxy and pristine single-walled CNTs, our previous work (Khare, K. S.; Khare, R. J. Phys. Chem. B 2013, 117, 7444-7454) has shown that weak matrix-filler interactions cause the interphase region in the nanocomposite to be more compressible. Furthermore, because of the weak matrix-filler interactions, the nanocomposite containing dispersed pristine CNTs has a glass transition temperature (Tg) that is ∼66 K lower than the neat polymer. In this work, we demonstrate that in spite of the presence of stiff CNTs in the nanocomposite, the Young's modulus of the nanocomposite containing dispersed pristine CNTs is virtually unchanged compared to the neat cross-linked epoxy. This observation suggests that the compressibility of the matrix-filler interphase interferes with the ability of the CNTs to reinforce the matrix. Furthermore, when the compressibility of the interphase is reduced by the use of amido-amine functionalized CNTs, the mechanical reinforcement due to the filler is more effective, resulting in a ∼50% increase in the Young's modulus compared to the neat cross-linked epoxy. Correspondingly, the functionalization of the CNTs also led to a recovery in the Tg making it effectively the same as the neat polymer and also resulted in a ∼12% increase in the thermal conductivity of the nanocomposite containing functionalized CNTs compared to that containing pristine CNTs. These results demonstrate that the functionalization of the CNTs facilitates the transfer of both mechanical load and thermal energy across the matrix-filler interface.

  5. Ultralow-Carbon Nanotube-Toughened Epoxy: The Critical Role of a Double-Layer Interface.

    Science.gov (United States)

    Liu, Jingwei; Chen, Chao; Feng, Yuezhan; Liao, Yonggui; Ye, Yunsheng; Xie, Xiaolin; Mai, Yiu-Wing

    2018-01-10

    Understanding the chemistry and structure of interfaces within epoxy resins is important for studying the mechanical properties of nanofiller-filled nanocomposites as well as for developing high-performance polymer nanocomposites. Despite the intensive efforts to construct nanofiller/matrix interfaces, few studies have demonstrated an enhanced stress-transferring efficiency while avoiding unfavorable deformation due to undesirable interface fractures. Here, we report an optimized method to prepare epoxy-based nanocomposites whose interfaces are chemically modulated by poly(glycidyl methacrylate)-block-poly(hexyl methacrylate) (PGMA-b-PHMA)-functionalized multiwalled carbon nanotubes (bc@fMWNTs) and also offer a fundamental explanation of crack growth behavior and the toughening mechanism of the resulting nanocomposites. The presence of block copolymers on the surface of the MWNT results in a promising double-layered interface, in which (1) the outer-layered PGMA segment provides good dispersion in and strong interface bonding with the epoxy matrix, which enhances load transfer efficiency and debonding stress, and (2) the interlayered rubbery PHMA segment around the MWNT provides the maximum removable space for nanotubes as well as triggering cavitation while promoting local plastic matrix deformation, for example, shear banding to dissipate fracture energy. An outstanding toughening effect is achieved with only a 0.05 wt % carbon nanotube loading with the bc@fMWNT, that is, needing only a 20-times lower loading to obtain improvements in fracture toughness comparable to epoxy-based nanocomposites. The enhancements of their corresponding ultimate mode-I fracture toughnesses and fracture energies are 4 times higher than those of pristine MWNT-filled epoxy. These results demonstrate that a MWNT/epoxy interface could be optimized by changing the component structure of grafted modifiers, thereby facilitating the transfer of both mechanical load and energy dissipation

  6. Interaction between Palladium Nanoparticles and Surface-Modified Carbon Nanotubes: Role of Surface Functionalities

    DEFF Research Database (Denmark)

    Zhang, Bingsen; Shao, Lidong; Zhang, Wei

    2014-01-01

    degrees C. We focus on probing the effects of oxygen and nitrogen-containing functional groups on supported palladium nanoparticles (NPs) in the model catalytic system. The stability of palladium NPs supported on CNTs depends strongly on the surface properties of CNTs. Moreover, the oxygen...... feature, instability, and subtle response of the components upon application of an external field. Herein, we use insitu TEM, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy techniques to record the interaction in palladium on carbon nanotubes (CNTs) from room temperature to 600...

  7. Thermophoretic transport of water nanodroplets confined in carbon nanotubes: the role of friction

    DEFF Research Database (Denmark)

    Oyarzua, Elton; Walther, Jens Honore; Zambrano, Harvey

    The development of efficient nanofluidic devices requires driving mechanisms that provide controlled transport of fluids through nanoconduits. Temperature gradients have been proposed as a mechanism to drive particles, fullerenes and nanodroplets inside carbon nanotubes (CNTs). In this work, molecular...... dynamics (MD) simulations are conducted to study thermophoresis of water nanodroplets inside CNTs. To gain insight into the interplay between the thermophoretic force acting on the droplet and the retarding liquid-solid friction, sets of constrained and unconstrained MD simulations are conducted...

  8. Hidden gauge symmetry

    International Nuclear Information System (INIS)

    O'Raifeartaigh, L.

    1979-01-01

    This review describes the principles of hidden gauge symmetry and of its application to the fundamental interactions. The emphasis is on the structure of the theory rather than on the technical details and, in order to emphasise the structure, gauge symmetry and hidden symmetry are first treated as independent phenomena before being combined into a single (hidden gauge symmetric) theory. The main application of the theory is to the weak and electromagnetic interactions of the elementary particles, and although models are used for comparison with experiment and for illustration, emphasis is placed on those features of the application which are model-independent. (author)

  9. Relationship between stress and pain in work-related upper extremity disorders: the hidden role of chronic multisymptom illnesses.

    Science.gov (United States)

    Clauw, Daniel J; Williams, David A

    2002-05-01

    Pain and fatigue are commonly associated with work-related upper extremity disorders. Occasionally these symptoms persist beyond a reasonable healing period. One potential explanation for prolonged symptom expression is the concurrent development of a stress-mediated illness or CMI (Chronic Multi-Symptom Illness). In such a scenario, the chronic regional pain and other symptoms that the individual is experiencing would be attributable to the CMI rather than to tissue damage or a biomechanical dysfunction of the upper-extremity. This article critically reviews the case definitions of the new class of CMI disorders and evaluates the existing evidence supporting centrally mediated physiological changes (e.g., sensory hypervigilance, dysautonomia) that manifest as symptoms of pain and fatigue in some individuals experiencing chronic stressors. While explanations for prolonged pain and fatigue have historically focused on mechanisms involving peripheral pathology or psychiatric explanations, ample evidences support the role of altered Central Nervous System function in accounting for symptom manifestation in CMI. A model is presented that unites seemingly disparate findings across numerous investigations and provides a framework for understanding how genetics, triggering events, stressors, and early life events can affect CNS activity. Resultant symptom expression (e.g., pain and fatigue) from central dysregulation would be expected to occur in a subset of individuals in the population, including a subset of individuals with work-related upper extremity disorders. Thus when symptoms such as pain and fatigue persist beyond a reasonable period, consideration of CMI and associated assessment and interventions focused on central mechanisms may be worthwhile.

  10. SPATIALLY RESOLVED KINEMATICS OF THE CENTRAL REGIONS OF M83: HIDDEN MASS SIGNATURES AND THE ROLE OF SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Piqueras Lopez, J.; Colina, L. [Centro de Astrobiologia, INTA-CSIC (Spain); Davies, R.; Orban de Xivry, G., E-mail: piqueraslj@cab.inta-csic.es [Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, 85741 Garching (Germany)

    2012-06-10

    The barred grand-design spiral M83 (NGC 5236) is one of the most studied galaxies given its proximity, orientation, and particular complexity. Nonetheless, many aspects of the central regions remain controversial, conveying our limited understanding of the inner gas and stellar kinematics, and ultimately of the nucleus evolution. In this work, we present AO VLT-SINFONI data of its central {approx}235 Multiplication-Sign 140 pc with an unprecedented spatial resolution of {approx}0.2 arcsec, corresponding to {approx}4 pc. We have focused our study on the distribution and kinematics of the stars and the ionized and molecular gas by studying the Pa{alpha} and Br{gamma} emission in detail, the H{sub 2} 1-0S(1) line at 2.122 {mu}m, and the [Fe II] line at 1.644 {mu}m, together with the CO absorption bands at 2.293 {mu}m and 2.323 {mu}m. Our results reveal a complex situation where the gas and stellar kinematics are totally unrelated. Supernova explosions play an important role in shaping the gas kinematics, dominated by shocks and inflows at scales of tens of parsecs that make them unsuitable to derive general dynamical properties. We propose that the location of the nucleus of M83 is unlikely to be related to the off-center 'optical nucleus'. The study of the stellar kinematics reveals that the optical nucleus is a gravitationally bound massive star cluster with M{sub dyn} = (1.1 {+-} 0.4) Multiplication-Sign 10{sup 7} M{sub Sun }, formed by a past starburst. The kinematic and photometric analysis of the cluster yield that the stellar content of the cluster is well described by an intermediate age population of log T(yr) = 8.0 {+-} 0.4, with a mass of M* {approx_equal} (7.8 {+-} 2.4) Multiplication-Sign 10{sup 6} M{sub Sun }.

  11. The hidden universe

    International Nuclear Information System (INIS)

    Disney, M.

    1985-01-01

    Astronomer Disney has followed a somewhat different tack than that of most popular books on cosmology by concentrating on the notion of hidden (as in not directly observable by its own radiation) matter in the universe

  12. Locating Hidden Servers

    National Research Council Canada - National Science Library

    Oeverlier, Lasse; Syverson, Paul F

    2006-01-01

    .... Announced properties include server resistance to distributed DoS. Both the EFF and Reporters Without Borders have issued guides that describe using hidden services via Tor to protect the safety of dissidents as well as to resist censorship...

  13. Hidden charged dark matter

    International Nuclear Information System (INIS)

    Feng, Jonathan L.; Kaplinghat, Manoj; Tu, Huitzu; Yu, Hai-Bo

    2009-01-01

    Can dark matter be stabilized by charge conservation, just as the electron is in the standard model? We examine the possibility that dark matter is hidden, that is, neutral under all standard model gauge interactions, but charged under an exact (\\rm U)(1) gauge symmetry of the hidden sector. Such candidates are predicted in WIMPless models, supersymmetric models in which hidden dark matter has the desired thermal relic density for a wide range of masses. Hidden charged dark matter has many novel properties not shared by neutral dark matter: (1) bound state formation and Sommerfeld-enhanced annihilation after chemical freeze out may reduce its relic density, (2) similar effects greatly enhance dark matter annihilation in protohalos at redshifts of z ∼ 30, (3) Compton scattering off hidden photons delays kinetic decoupling, suppressing small scale structure, and (4) Rutherford scattering makes such dark matter self-interacting and collisional, potentially impacting properties of the Bullet Cluster and the observed morphology of galactic halos. We analyze all of these effects in a WIMPless model in which the hidden sector is a simplified version of the minimal supersymmetric standard model and the dark matter is a hidden sector stau. We find that charged hidden dark matter is viable and consistent with the correct relic density for reasonable model parameters and dark matter masses in the range 1 GeV ∼ X ∼< 10 TeV. At the same time, in the preferred range of parameters, this model predicts cores in the dark matter halos of small galaxies and other halo properties that may be within the reach of future observations. These models therefore provide a viable and well-motivated framework for collisional dark matter with Sommerfeld enhancement, with novel implications for astrophysics and dark matter searches

  14. Interaction of molecular oxygen with single wall nanotubes: Role of surfactant contamination

    International Nuclear Information System (INIS)

    Larciprete, R.; Goldoni, A.; Lizzit, S.

    2003-01-01

    The interaction of molecular oxygen with single wall nanotubes in the form of a commercial bucky paper was investigated by high resolution photoemission spectroscopy. Sodium contamination was found in the sample, which was completely removed only after prolonged heating at 1250 K. The C 1s core level spectrum measured on the sample annealed to 1020 K dramatically changed upon exposure to molecular oxygen. On the contrary, when exposing the Na-free SWNTs to several KL of O 2 , the sample remained oxygen free and no modification in the C 1s core level was observed. Therefore the observed sensitivity of the sample to O 2 was due to a Na mediated oxidation, determining a charge transfer from the C tubes to the Na-O complex

  15. Compatibilizing role of carbon nanotubes in poly(vinyl alcohol)/starch blend

    KAUST Repository

    Jose, Jobin Vinodh

    2014-10-03

    Polymer nanocomposites based on poly(vinyl alcohol)/starch blend and carbon nanotubes (CNT) were prepared by solution mixing, followed by casting. Glycerol was used as a plasticizer and added in the starch dispersion. The uniform dispersion of CNT in water before mixing with PVA/starch blend, was achieved by using an Ultrasonicator probe. The composites were characterized by measurement of tensile properties, thermal analysis, FE-SEM, TEM, XRD studies, and water uptake. It was observed that the decrease in tensile strength, modulus, and elongation at break on addition of starch into PVA can be arrested by incorporation of CNT. The strong physical bonding such as hydrogen bonding among the hydroxyl groups of polymer components and oxygen containing groups on CNT surface resulted in a more tortuous path for the water to follow, lowering of water uptake. Thermal analysis and spectroscopic images showed an increase in blend homogeneity in the presence of CNT.

  16. Synthesis of carbon nanotubes bridging metal electrodes

    International Nuclear Information System (INIS)

    Kotlar, M.; Vojs, M.; Marton, M.; Vesel, M.; Redhammer, R.

    2012-01-01

    In our work we demonstrate growth of carbon nanotubes that can conductively bridge the metal electrodes. The role of different catalysts was examined. Interdigitated metal electrodes are made from copper and we are using bimetal Al/Ni as catalyst for growth of carbon nanotubes. We are using this catalyst composition for growth of the single-walled carbon nanotube network. (authors)

  17. Search for Hidden Particles

    CERN Multimedia

    Solovev, V

    The SHiP Experiment is a new general-purpose fixed target facility at the SPS to search for hidden particles as predicted by a very large number of recently elaborated models of Hidden Sectors which are capable of accommodating dark matter, neutrino oscillations, and the origin of the full baryon asymmetry in the Universe. Specifically, the experiment is aimed at searching for very weakly interacting long lived particles including Heavy Neutral Leptons - right-handed partners of the active neutrinos; light supersymmetric particles - sgoldstinos, etc.; scalar, axion and vector portals to the hidden sector. The high intensity of the SPS and in particular the large production of charm mesons with the 400 GeV beam allow accessing a wide variety of light long-lived exotic particles of such models and of SUSY. Moreover, the facility is ideally suited to study the interactions of tau neutrinos.

  18. Toward Small-Diameter Carbon Nanotubes Synthesized from Captured Carbon Dioxide: Critical Role of Catalyst Coarsening.

    Science.gov (United States)

    Douglas, Anna; Carter, Rachel; Li, Mengya; Pint, Cary L

    2018-05-23

    Small-diameter carbon nanotubes (CNTs) often require increased sophistication and control in synthesis processes, but exhibit improved physical properties and greater economic value over their larger-diameter counterparts. Here, we study mechanisms controlling the electrochemical synthesis of CNTs from the capture and conversion of ambient CO 2 in molten salts and leverage this understanding to achieve the smallest-diameter CNTs ever reported in the literature from sustainable electrochemical synthesis routes, including some few-walled CNTs. Here, Fe catalyst layers are deposited at different thicknesses onto stainless steel to produce cathodes, and atomic layer deposition of Al 2 O 3 is performed on Ni to produce a corrosion-resistant anode. Our findings indicate a correlation between the CNT diameter and Fe metal layer thickness following electrochemical catalyst reduction at the cathode-molten salt interface. Further, catalyst coarsening during long duration synthesis experiments leads to a 2× increase in average diameters from 3 to 60 min durations, with CNTs produced after 3 min exhibiting a tight diameter distribution centered near ∼10 nm. Energy consumption analysis for the conversion of CO 2 into CNTs demonstrates energy input costs much lower than the value of CNTs-a concept that strictly requires and motivates small-diameter CNTs-and is more favorable compared to other costly CO 2 conversion techniques that produce lower-value materials and products.

  19. The significant role of carboxylated carbonaceous fragments in the electrochemistry of carbon nanotubes.

    Science.gov (United States)

    Ma, Xiao; Jia, Li; Zhang, Lu; Zhu, Liande

    2014-04-01

    Carbon nanotubes (CNTs) have been widely employed as electrode materials in diverse branches of electrochemistry, which are claimed to display dramatically improved electrochemical behaviour compared to the conventional carbon materials. But a series of recent publications have demonstrated that the electrocatalysis of CNTs might be due to the presence of some impurities, such as metallic catalysts, nanographitic particles and amorphous carbon. For this reason, CNTs are usually purified or treated with nitric acid or nitric and sulphuric acid prior to their versatile applications. However, the strong acidic and oxidative conditions are so aggressive that serious erosion of the tube structures has inevitably taken place, which creates defects on the sidewalls and gives rise to numerous molecular byproducts, commonly referred as carboxylated carbonaceous fragments (CCFs). The adsorption of CCFs on CNTs greatly alters the surface conditions of CNTs which may significantly impact on their electrochemical properties. To this end, we wish to disclose whether the electrocatalysis of the nitric acid purified CNTs is affected by the adsorption of the CCFs. Ascorbic acid (AA) and β-nicotinamide adenine dinucleotide (NADH) as selected as the targeting benchmarks that are known to be insensitive to the presence of metallic impurities, which may guarantee the preclusion of the promoting contributions from the metallic catalysts resident in CNTs. We have demonstrated that the electrocatalytic activities of the CNTs are actually dominated by the adsorbed CCFs generated during the acidic pre-treatment. After removal of the CCFs by base rinse, the electrocatalytic properties of CNTs are greatly deteriorated and degraded to the level similar to the conventional graphite powder. We believe this finding is particularly meaningful to uncover the mysterious electrocatalysis of CNTs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. The hidden values

    DEFF Research Database (Denmark)

    Rasmussen, Birgitte; Jensen, Karsten Klint

    “The Hidden Values - Transparency in Decision-Making Processes Dealing with Hazardous Activities”. The report seeks to shed light on what is needed to create a transparent framework for political and administrative decisions on the use of GMOs and chemical products. It is our hope that the report...

  1. Tunneling Nanotubes and Gap Junctions–Their Role in Long-Range Intercellular Communication during Development, Health, and Disease Conditions

    Directory of Open Access Journals (Sweden)

    Jennifer Ariazi

    2017-10-01

    Full Text Available Cell-to-cell communication is essential for the organization, coordination, and development of cellular networks and multi-cellular systems. Intercellular communication is mediated by soluble factors (including growth factors, neurotransmitters, and cytokines/chemokines, gap junctions, exosomes and recently described tunneling nanotubes (TNTs. It is unknown whether a combination of these communication mechanisms such as TNTs and gap junctions may be important, but further research is required. TNTs are long cytoplasmic bridges that enable long-range, directed communication between connected cells. The proposed functions of TNTs are diverse and not well understood but have been shown to include the cell-to-cell transfer of vesicles, organelles, electrical stimuli and small molecules. However, the exact role of TNTs and gap junctions for intercellular communication and their impact on disease is still uncertain and thus, the subject of much debate. The combined data from numerous laboratories indicate that some TNT mediate a long-range gap junctional communication to coordinate metabolism and signaling, in relation to infectious, genetic, metabolic, cancer, and age-related diseases. This review aims to describe the current knowledge, challenges and future perspectives to characterize and explore this new intercellular communication system and to design TNT-based therapeutic strategies.

  2. Use of high energy ball milling to study the role of graphene nanoplatelets and carbon nanotubes reinforced magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Rashad, Muhammad, E-mail: rashadphy87@gmail.com [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Pan, Fusheng, E-mail: fspan@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing, Chongqing 401123 (China); Zhang, Jianyue [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Asif, Muhammad [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

    2015-10-15

    Graphene nanoplatelets (few layer graphene) and carbon nanotubes were used as reinforcement fillers to enhance the mechanical properties of AZ31 magnesium alloy through high energy ball milling, sintering, and hot extrusion techniques. Experimental results revealed that tensile fracture strain of AZ31 magnesium alloy was enhanced by +49.6% with 0.3 wt.% graphene nanoplatelets compared to −8.3% regression for 0.3 wt.% carbon nanotubes. The tensile strength of AZ31 magnesium alloy was decreased (−11.2%) with graphene nanoplatelets addition, while increased (+7.7%) with carbon nanotubes addition. Unlike tensile test, compression tests showed different trend. The compression strength of carbon nanotubes-AZ31 composite was +51.2% greater than AZ31 magnesium alloy as compared to +0.6% increase for graphene nanoplatelets. The compressive fracture strain of carbon nanotubes-AZ31 composite was decreased (−14.1%) while no significant change in fracture strain of graphene nanoplatelets-AZ31 composite was observed. The X-ray diffraction results revealed that addition of reinforcement particles weaken the basal textures which affect the composite's yield asymmetry. Microstructure evaluation revealed the absence of intermetallic phase formation between reinforcements and matrix. The carbon reinforcements in AZ31 magnesium alloy dissolve and isolate β phases throughout the matrix. The increased fracture strain and mechanical strength of graphene nanoplatelets and carbon nanotubes-AZ31 composites are attributed to large specific surface area of graphene nanoplatelets and stiffer nature of carbon nanotubes respectively. - Highlights: • Powder metallurgy method was used to fabricate magnesium composites. • The AZ31-carbon materials composite were blended using ball milling. • The reinforcement particles weaken the basal texture which affects yield asymmetry of composites. • AZ31-graphene nanoplatelets composite exhibited impressive increase in tensile elongation

  3. Use of high energy ball milling to study the role of graphene nanoplatelets and carbon nanotubes reinforced magnesium alloy

    International Nuclear Information System (INIS)

    Rashad, Muhammad; Pan, Fusheng; Zhang, Jianyue; Asif, Muhammad

    2015-01-01

    Graphene nanoplatelets (few layer graphene) and carbon nanotubes were used as reinforcement fillers to enhance the mechanical properties of AZ31 magnesium alloy through high energy ball milling, sintering, and hot extrusion techniques. Experimental results revealed that tensile fracture strain of AZ31 magnesium alloy was enhanced by +49.6% with 0.3 wt.% graphene nanoplatelets compared to −8.3% regression for 0.3 wt.% carbon nanotubes. The tensile strength of AZ31 magnesium alloy was decreased (−11.2%) with graphene nanoplatelets addition, while increased (+7.7%) with carbon nanotubes addition. Unlike tensile test, compression tests showed different trend. The compression strength of carbon nanotubes-AZ31 composite was +51.2% greater than AZ31 magnesium alloy as compared to +0.6% increase for graphene nanoplatelets. The compressive fracture strain of carbon nanotubes-AZ31 composite was decreased (−14.1%) while no significant change in fracture strain of graphene nanoplatelets-AZ31 composite was observed. The X-ray diffraction results revealed that addition of reinforcement particles weaken the basal textures which affect the composite's yield asymmetry. Microstructure evaluation revealed the absence of intermetallic phase formation between reinforcements and matrix. The carbon reinforcements in AZ31 magnesium alloy dissolve and isolate β phases throughout the matrix. The increased fracture strain and mechanical strength of graphene nanoplatelets and carbon nanotubes-AZ31 composites are attributed to large specific surface area of graphene nanoplatelets and stiffer nature of carbon nanotubes respectively. - Highlights: • Powder metallurgy method was used to fabricate magnesium composites. • The AZ31-carbon materials composite were blended using ball milling. • The reinforcement particles weaken the basal texture which affects yield asymmetry of composites. • AZ31-graphene nanoplatelets composite exhibited impressive increase in tensile elongation

  4. Hidden neural networks

    DEFF Research Database (Denmark)

    Krogh, Anders Stærmose; Riis, Søren Kamaric

    1999-01-01

    A general framework for hybrids of hidden Markov models (HMMs) and neural networks (NNs) called hidden neural networks (HNNs) is described. The article begins by reviewing standard HMMs and estimation by conditional maximum likelihood, which is used by the HNN. In the HNN, the usual HMM probability...... parameters are replaced by the outputs of state-specific neural networks. As opposed to many other hybrids, the HNN is normalized globally and therefore has a valid probabilistic interpretation. All parameters in the HNN are estimated simultaneously according to the discriminative conditional maximum...... likelihood criterion. The HNN can be viewed as an undirected probabilistic independence network (a graphical model), where the neural networks provide a compact representation of the clique functions. An evaluation of the HNN on the task of recognizing broad phoneme classes in the TIMIT database shows clear...

  5. A hidden history

    OpenAIRE

    Peppers, Emily

    2008-01-01

    The Cultural Collections Audit project began at the University of Edinburgh in 2004, searching for hidden treasures in its 'distributed heritage collections' across the university. The objects and collections recorded in the Audit ranged widely from fine art and furniture to historical scientific and teaching equipment and personalia relating to key figures in the university's long tradition of academic excellence. This information was gathered in order to create a central database of informa...

  6. Distinguishing Hidden Markov Chains

    OpenAIRE

    Kiefer, Stefan; Sistla, A. Prasad

    2015-01-01

    Hidden Markov Chains (HMCs) are commonly used mathematical models of probabilistic systems. They are employed in various fields such as speech recognition, signal processing, and biological sequence analysis. We consider the problem of distinguishing two given HMCs based on an observation sequence that one of the HMCs generates. More precisely, given two HMCs and an observation sequence, a distinguishing algorithm is expected to identify the HMC that generates the observation sequence. Two HM...

  7. Coupling of Hidden Sector

    OpenAIRE

    Królikowski, Wojciech

    2016-01-01

    A hypothetic Hidden Sector of the Universe, consisting of sterile fer\\-mions (``sterinos'') and sterile mediating bosons (``sterons'') of mass dimension 1 (not 2!) --- the last described by an antisymmetric tensor field --- requires to exist also a scalar isovector and scalar isoscalar in order to be able to construct electroweak invariant coupling (before spontaneously breaking its symmetry). The introduced scalar isoscalar might be a resonant source for the diphoton excess of 750 GeV, sugge...

  8. … To be hidden does not mean to be merely revealed – Part 1 Artistic research on hidden curriculum

    Directory of Open Access Journals (Sweden)

    Annette Krause

    2015-09-01

    Full Text Available This text revisits the long-term project Hidden Curriculum, initiated by Annette Krauss. The project addresses unquestioned routines, hierarchies of knowledge (part 1, and the role of the body in learning processes (part 2 from the perspective of secondary/high school education (in the research on a hidden curriculum. A deeper analysis of educational studies on the phenomenon of ‘hidden curriculum’ in relation to the feminist and critical pedagogies of bell hooks, Paulo Freire, and Jacques Rancière brings forward important insights generated through the artistic research within hidden curriculum. The aim of this text is to address academic canons, corporeality, and investigate everyday norms through revisiting the framework, results, and processes of the collaborative research into hidden curriculum with secondary high school students.

  9. Critical role of surface chemical modifications induced by length shortening on multi-walled carbon nanotubes-induced toxicity

    Directory of Open Access Journals (Sweden)

    Bussy Cyrill

    2012-11-01

    Full Text Available Abstract Given the increasing use of carbon nanotubes (CNT in composite materials and their possible expansion to new areas such as nanomedicine which will both lead to higher human exposure, a better understanding of their potential to cause adverse effects on human health is needed. Like other nanomaterials, the biological reactivity and toxicity of CNT were shown to depend on various physicochemical characteristics, and length has been suggested to play a critical role. We therefore designed a comprehensive study that aimed at comparing the effects on murine macrophages of two samples of multi-walled CNT (MWCNT specifically synthesized following a similar production process (aerosol-assisted CVD, and used a soft ultrasonic treatment in water to modify the length of one of them. We showed that modification of the length of MWCNT leads, unavoidably, to accompanying structural (i.e. defects and chemical (i.e. oxidation modifications that affect both surface and residual catalyst iron nanoparticle content of CNT. The biological response of murine macrophages to the two different MWCNT samples was evaluated in terms of cell viability, pro-inflammatory cytokines secretion and oxidative stress. We showed that structural defects and oxidation both induced by the length reduction process are at least as responsible as the length reduction itself for the enhanced pro-inflammatory and pro-oxidative response observed with short (oxidized compared to long (pristine MWCNT. In conclusion, our results stress that surface properties should be considered, alongside the length, as essential parameters in CNT-induced inflammation, especially when dealing with a safe design of CNT, for application in nanomedicine for example.

  10. Sociocultural Dimension of Hidden Content in a Professional Language Curriculum

    Directory of Open Access Journals (Sweden)

    Ekaterina E. Shishlova

    2017-12-01

    Full Text Available Introduction: studying curriculum as a pedagogical problem has traditionally been reduced to the analysis of its explicit content, set in official educational documents. However, a much less studied hidden content plays a significant role in education. So, what is the role of the hidden curriculum during professional language training? The purpose of the article is to determine the potential impact of hidden curriculum on students’ conceptual worldview. Comparing the worldview presented in textbooks with students’ one has allowed us to estimate the rate of influence of hidden curr iculum. Materials and Methods: the methodological basis of the work is the cultural concept of personalityoriented education. The methodology for studying the role of hidden curriculum includes four stages: at the first stage, the authors set the criteria for selecting textbooks for analysis and do the selection; at the second stage, the authors select sociocultural concepts for analysis; at the third stage, the scheme of analysis is designed and the analysis of textbooks is done; at the fourth stage, the authors identify the potential influence of hidden curriculum on students’ conceptual worldview. Results: the structure of hidden curriculum has been determined and the scheme for analysing its subject component has been developed. The authors have identified a significant influence of hidden curriculum on students’ worldview, which represents the scientific novelty of the article. Discussion and Conclusions: the article gives the definition of a hidden curriculum which is new for Russian pedagogy and presents a methodology for its analysis in EFL textbooks. That analysis is recommended to be conducted when selecting teaching materials both i n languages and other humanities.

  11. Hidden gauge structure of supersymmetric free differential algebras

    Energy Technology Data Exchange (ETDEWEB)

    Andrianopoli, Laura [DISAT, Politecnico di Torino,Corso Duca degli Abruzzi 24, I-10129 Turin (Italy); INFN - Sezione di Torino,Torino (Italy); D’Auria, Riccardo [DISAT, Politecnico di Torino,Corso Duca degli Abruzzi 24, I-10129 Turin (Italy); Ravera, Lucrezia [DISAT, Politecnico di Torino,Corso Duca degli Abruzzi 24, I-10129 Turin (Italy); INFN - Sezione di Torino,Torino (Italy)

    2016-08-16

    The aim of this paper is to clarify the role of the nilpotent fermionic generator Q{sup ′} introduced in http://dx.doi.org/10.1016/0550-3213(82)90376-5 and appearing in the hidden supergroup underlying the free differential algebra (FDA) of D=11 supergravity. We give a physical explanation of its role by looking at the gauge properties of the theory. We find that its presence is necessary, in order that the extra 1-forms of the hidden supergroup give rise to the correct gauge transformations of the p-forms of the FDA. This interpretation is actually valid for any supergravity containing antisymmetric tensor fields, and any supersymmetric FDA can always be traded for a hidden Lie superalgebra containing extra fermionic nilpotent generators. As an interesting example we construct the hidden superalgebra associated with the FDA of N=2, D=7 supergravity. In this case we are able to parametrize the mutually non local 2- and 3-form B{sup (2)} and B{sup (3)} in terms of hidden 1-forms and find that supersymmetry and gauge invariance require in general the presence of two nilpotent fermionic generators in the hidden algebra. We propose that our approach, where all the invariances of the FDA are expressed as Lie derivatives of the p-forms in the hidden supergroup manifold, could be an appropriate framework to discuss theories defined in enlarged versions of superspace recently considered in the literature, such us double field theory and its generalizations.

  12. Localization of hidden Chua's attractors

    International Nuclear Information System (INIS)

    Leonov, G.A.; Kuznetsov, N.V.; Vagaitsev, V.I.

    2011-01-01

    The classical attractors of Lorenz, Rossler, Chua, Chen, and other widely-known attractors are those excited from unstable equilibria. From computational point of view this allows one to use numerical method, in which after transient process a trajectory, started from a point of unstable manifold in the neighborhood of equilibrium, reaches an attractor and identifies it. However there are attractors of another type: hidden attractors, a basin of attraction of which does not contain neighborhoods of equilibria. In the present Letter for localization of hidden attractors of Chua's circuit it is suggested to use a special analytical-numerical algorithm. -- Highlights: → There are hidden attractors: basin doesn't contain neighborhoods of equilibria. → Hidden attractors cannot be reached by trajectory from neighborhoods of equilibria. → We suggested special procedure for localization of hidden attractors. → We discovered hidden attractor in Chua's system, L. Chua in his work didn't expect this.

  13. Effect of carbon nanotube dispersion on glass transition in cross-linked epoxy-carbon nanotube nanocomposites: role of interfacial interactions.

    Science.gov (United States)

    Khare, Ketan S; Khare, Rajesh

    2013-06-20

    We have used atomistic molecular simulations to study the effect of nanofiller dispersion on the glass transition behavior of cross-linked epoxy-carbon nanotube (CNT) nanocomposites. Specific chemical interactions at the interface of CNTs and cross-linked epoxy create an interphase region, whose impact on the properties of their nanocomposites increases with an increasing extent of dispersion. To investigate this aspect, we have compared the volumetric, structural, and dynamical properties of three systems: neat cross-linked epoxy, cross-linked epoxy nanocomposite containing dispersed CNTs, and cross-linked epoxy nanocomposite containing aggregated CNTs. We find that the nanocomposite containing dispersed CNTs shows a depression in the glass transition temperature (Tg) by ~66 K as compared to the neat cross-linked epoxy, whereas such a large depression is absent in the nanocomposite containing aggregated CNTs. Our results suggest that the poor interfacial interactions between the CNTs and the cross-linked epoxy matrix lead to a more compressible interphase region between the CNTs and the bulk matrix. An analysis of the resulting dynamic heterogeneity shows that the probability of percolation of immobile domains becomes unity near the Tg calculated from volumetric properties. Our observations also lend support to the conceptual analogy between polymer nanocomposites and the nanoconfinement of polymer thin films.

  14. Hidden symmetries in five-dimensional supergravity

    International Nuclear Information System (INIS)

    Poessel, M.

    2003-05-01

    This thesis is concerned with the study of hidden symmetries in supergravity, which play an important role in the present picture of supergravity and string theory. Concretely, the appearance of a hidden G 2(+2) /SO(4) symmetry is studied in the dimensional reduction of d=5, N=2 supergravity to three dimensions - a parallel model to the more famous E 8(+8) /SO(16) case in eleven-dimensional supergravity. Extending previous partial results for the bosonic part, I give a derivation that includes fermionic terms. This sheds new light on the appearance of the local hidden symmetry SO(4) in the reduction, and shows up an unusual feature which follows from an analysis of the R-symmetry associated with N=4 supergravity and of the supersymmetry variations, and which has no parallel in the eleven-dimensional case: The emergence of an additional SO(3) as part of the enhanced local symmetry, invisible in the dimensional reduction of the gravitino, and corresponding to the fact that, of the SO(4) used in the coset model, only the diagonal SO(3) is visible immediately upon dimensional reduction. The uncovering of the hidden symmetries proceeds via the construction of the proper coset gravity in three dimensions, and matching it with the Lagrangian obtained from the reduction. (orig.)

  15. Hidden Liquidity: Determinants and Impact

    OpenAIRE

    Gökhan Cebiroglu; Ulrich Horst

    2012-01-01

    We cross-sectionally analyze the presence of aggregated hidden depth and trade volume in the S&P 500 and identify its key determinants. We find that the spread is the main predictor for a stock’s hidden dimension, both in terms of traded and posted liquidity. Our findings moreover suggest that large hidden orders are associated with larger transaction costs, higher price impact and increased volatility. In particular, as large hidden orders fail to attract (latent) liquidity to the market, ...

  16. Role of the Material Electrodes on Resistive Behaviour of Carbon Nanotube-Based Gas Sensors for H2S Detection

    Directory of Open Access Journals (Sweden)

    M. Lucci

    2012-01-01

    Full Text Available Miniaturized gas-sensing devices that use single-walled carbon nanotubes as active material have been fabricated using two different electrode materials, namely, Au/Cr and NbN. The resistive sensors have been assembled aligning by dielectrophoresis the nanotube bundles between 40 μm spaced Au/Cr or NbN multifinger electrodes. The sensing devices have been tested for detection of the H2S gas, in the concentration range 10–100 ppm, using N2 as carrier gas. No resistance changes were detected using sensor fabricated with NbN electrodes, whereas the response of the sensor fabricated with Au/Cr electrodes was characterized by an increase of the resistance upon gas exposure. The main performances of this sensor are a detection limit for H2S of 10 ppm and a recovery time of few minutes. The present study suggests that the mechanism involved in H2S gas detection is not a direct charge transfer between molecules and nanotubes. The hypothesis is that detection occurs through passivation of the Au surfaces by H2S molecules and modification of the contact resistance at the Au/nanotube interface.

  17. Hidden Risk Factors for Women

    Science.gov (United States)

    ... A.S.T. Quiz Hidden Stroke Risk Factors for Women Updated:Nov 22,2016 Excerpted from "What Women Need To Know About The Hidden Risk Factors ... 2012) This year, more than 100,000 U.S. women under 65 will have a stroke. Stroke is ...

  18. Higgs Portal into Hidden Sectors

    CERN Multimedia

    CERN. Geneva

    2007-01-01

    Several attractive theoretical ideas suggest the existence of one or more 'hidden sectors' consisting of standard model singlet fields, some of which may not be too heavy. There is a profound reason to think that the Higgs sector might provide the first access to these hidden sectors. This scenario could affect Higgs phenomenology in drastic ways.

  19. Hidden attractors in dynamical systems

    Science.gov (United States)

    Dudkowski, Dawid; Jafari, Sajad; Kapitaniak, Tomasz; Kuznetsov, Nikolay V.; Leonov, Gennady A.; Prasad, Awadhesh

    2016-06-01

    Complex dynamical systems, ranging from the climate, ecosystems to financial markets and engineering applications typically have many coexisting attractors. This property of the system is called multistability. The final state, i.e., the attractor on which the multistable system evolves strongly depends on the initial conditions. Additionally, such systems are very sensitive towards noise and system parameters so a sudden shift to a contrasting regime may occur. To understand the dynamics of these systems one has to identify all possible attractors and their basins of attraction. Recently, it has been shown that multistability is connected with the occurrence of unpredictable attractors which have been called hidden attractors. The basins of attraction of the hidden attractors do not touch unstable fixed points (if exists) and are located far away from such points. Numerical localization of the hidden attractors is not straightforward since there are no transient processes leading to them from the neighborhoods of unstable fixed points and one has to use the special analytical-numerical procedures. From the viewpoint of applications, the identification of hidden attractors is the major issue. The knowledge about the emergence and properties of hidden attractors can increase the likelihood that the system will remain on the most desirable attractor and reduce the risk of the sudden jump to undesired behavior. We review the most representative examples of hidden attractors, discuss their theoretical properties and experimental observations. We also describe numerical methods which allow identification of the hidden attractors.

  20. Nanotube cathodes.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-11-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  1. Nanotube cathodes

    International Nuclear Information System (INIS)

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-01-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  2. Quantum transport in carbon nanotubes

    DEFF Research Database (Denmark)

    Laird, Edward A.; Kuemmeth, Ferdinand; Steele, Gary A.

    2015-01-01

    Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries, enabled by sophisticated fabrication, have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin...... blockade. This can be exploited to read out spin and valley qubits, and to measure the decay of these states through coupling to nuclear spins and phonons. A second unique property of carbon nanotubes is that the combination of valley freedom and electron-electron interactions in one dimension strongly...... and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and from valley freedom. We focus on the interplay between the two...

  3. Facile Synthesis of Ternary Boron Carbonitride Nanotubes

    Directory of Open Access Journals (Sweden)

    Luo Lijie

    2009-01-01

    Full Text Available Abstract In this study, a novel and facile approach for the synthesis of ternary boron carbonitride (B–C–N nanotubes was reported. Growth occurred by heating simple starting materials of boron powder, zinc oxide powder, and ethanol absolute at 1150 °C under a mixture gas flow of nitrogen and hydrogen. As substrate, commercial stainless steel foil with a typical thickness of 0.05 mm played an additional role of catalyst during the growth of nanotubes. The nanotubes were characterized by SEM, TEM, EDX, and EELS. The results indicate that the synthesized B–C–N nanotubes exhibit a bamboo-like morphology and B, C, and N elements are homogeneously distributed in the nanotubes. A catalyzed vapor–liquid–solid (VLS mechanism was proposed for the growth of the nanotubes.

  4. Variational Infinite Hidden Conditional Random Fields

    NARCIS (Netherlands)

    Bousmalis, Konstantinos; Zafeiriou, Stefanos; Morency, Louis-Philippe; Pantic, Maja; Ghahramani, Zoubin

    2015-01-01

    Hidden conditional random fields (HCRFs) are discriminative latent variable models which have been shown to successfully learn the hidden structure of a given classification problem. An Infinite hidden conditional random field is a hidden conditional random field with a countably infinite number of

  5. Managing Hidden Costs of Offshoring

    DEFF Research Database (Denmark)

    Larsen, Marcus M.; Pedersen, Torben

    2014-01-01

    This chapter investigates the concept of the ‘hidden costs’ of offshoring, i.e. unexpected offshoring costs exceeding the initially expected costs. Due to the highly undefined nature of these costs, we position our analysis towards the strategic responses of firms’ realisation of hidden costs....... In this regard, we argue that a major response to the hidden costs of offshoring is the identification and utilisation of strategic mechanisms in the organisational design to eventually achieving system integration in a globally dispersed and disaggregated organisation. This is heavily moderated by a learning......-by-doing process, where hidden costs motivate firms and their employees to search for new and better knowledge on how to successfully manage the organisation. We illustrate this thesis based on the case of the LEGO Group....

  6. Child Abuse: The Hidden Bruises

    Science.gov (United States)

    ... for Families - Vietnamese Spanish Facts for Families Guide Child Abuse - The Hidden Bruises No. 5; Updated November 2014 The statistics on physical child abuse are alarming. It is estimated hundreds of thousands ...

  7. Hidden Statistics of Schroedinger Equation

    Science.gov (United States)

    Zak, Michail

    2011-01-01

    Work was carried out in determination of the mathematical origin of randomness in quantum mechanics and creating a hidden statistics of Schr dinger equation; i.e., to expose the transitional stochastic process as a "bridge" to the quantum world. The governing equations of hidden statistics would preserve such properties of quantum physics as superposition, entanglement, and direct-product decomposability while allowing one to measure its state variables using classical methods.

  8. Hidden Curriculum: An Analytical Definition

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Andarvazh

    2018-03-01

    Full Text Available Background: The concept of hidden curriculum was first used by Philip Jackson in 1968, and Hafferty brought this concept to the medical education. Many of the subjects that medical students learn are attributed to this curriculum. So far several definitions have been presented for the hidden curriculum, which on the one hand made this concept richer, and on the other hand, led to confusion and ambiguity.This paper tries to provide a clear and comprehensive definition of it.Methods: In this study, concept analysis of McKenna method was used. Using keywords and searching in the databases, 561 English and 26 Persian references related to the concept was found, then by limitingthe research scope, 125 abstracts and by finding more relevant references, 55 articles were fully studied.Results: After analyzing the definitions by McKenna method, the hidden curriculum is defined as follows: The hidden curriculum is a hidden, powerful, intrinsic in organizational structure and culture and sometimes contradictory message, conveyed implicitly and tacitly in the learning environment by structural and human factors and its contents includes cultural habits and customs, norms, values, belief systems, attitudes, skills, desires and behavioral and social expectations can have a positive or negative effect, unplanned, neither planners nor teachers, nor learners are aware of it. The ultimate consequence of the hidden curriculum includes reproducing the existing class structure, socialization, and familiarizing learners for transmission and joining the professional world.Conclusion: Based on the concept analysis, we arrived at an analytical definition of the hidden curriculum that could be useful for further studies in this area.Keywords: CONCEPT ANALYSIS, HIDDEN CURRICULUM, MCKENNA’S METHOD

  9. Nanotube phonon waveguide

    Science.gov (United States)

    Chang, Chih-Wei; Zettl, Alexander K.

    2013-10-29

    Disclosed are methods and devices in which certain types of nanotubes (e.g., carbon nanotubes and boron nitride nanotubes conduct heat with high efficiency and are therefore useful in electronic-type devices.

  10. Role of direct covalent bonding in enhanced heat dissipation property of flexible graphene oxide–carbon nanotube hybrid film

    International Nuclear Information System (INIS)

    Hwang, Yongseon; Kim, Myeongjin; Kim, Jooheon

    2013-01-01

    The thermal conductivity of graphene oxide/multiwalled carbon nanotube (GO/MWCNT) hybrid films with and without covalent bonding is examined in this study. To fabricate chemically bonded GO/MWCNT hybrid films, chlorinated GO and amino-functionalized MWCNTs are bonded covalently. The mixtures of surface modified GO and MWCNT were filtered and then subjected to hot pressing to fabricate stacked films. Examination of these chemically bonded hybrid films reveal that chlorine-doped GO exhibits enhanced electrical properties because it creates hole charge carriers by attracting the electrons in GO towards chlorine. Enhanced electrical conductivity and low sheet resistance are observed also with increasing MWCNT loadings. On comparing the through-plane thermal properties, the chemically bonded hybrid films were found to exhibit higher thermal conductivity than do the physically bonded hybrid films because of the synergetic interaction of functional groups in GO and MWCNTs in the former films. However, excess addition of MWCNTs to the films leads to an increasing phonon scattering density and a decreased thermal conductivity. - Highlights: • Graphene oxide/carbon nanotube (GO/CNT) films are bonded covalently. • GO/CNT hybrid films are prepared through filtering and hot-pressing method. • Chemically bonded hybrid films exhibit enhanced electrical and thermal properties. • Enhanced thermal conductivity is explained according to increasing CNT contents

  11. A role of nanotube dangling pyrrole and oxygen functions in the electrochemical synthesis of polypyrrole/MWCNTs hybrid materials

    International Nuclear Information System (INIS)

    Krukiewicz, Katarzyna; Herman, Artur P.; Turczyn, Roman; Szymańska, Katarzyna; Koziol, Krzysztof K.K.; Boncel, Sławomir; Zak, Jerzy K.

    2014-01-01

    Highlights: • The effect of MWCNT functionalization on properties of PPy composites was explained. • The behavior of pristine, pyrrole-modified and oxidized MWCNT was explained. • Functionalization of MWCNT improved their dispersibility and processability. • Different mechanisms of (f-)MWCNT incorporation into PPy composites were explained. • Orientation of growing PPy chains was tailored through the addition of (f-)MWCNT. - Abstract: The effect of the functionalization of multi-walled carbon nanotubes (MWCNTs) on the process of electrochemical co-deposition of MWCNTs and polypyrrole (PPy), as well as the morphology of obtained composites have been demonstrated. As the nanotube components of the hybrids, three types of MWCNT were used, namely c-CVD derived (pristine) MWCNTs, their oxidized counterparts MWCNT-Ox and pyrrole-modified MWCNT-Py. The stability of pristine and functionalized MWCNTs (f-MWCNT) dispersions in tetrahydrofuran and water was studied together with the description of the process of formation PPy/(f-)MWCNT hybrid materials via electrochemical co-deposition. The structural and morphological properties of the hybrids were characterized by Raman spectroscopy, scanning electron microscopy and atomic force microscopy revealing substantial differences among hybrid materials in their surface morphology and the influence of MWCNT functionalization on the orientation of growing PPy chains

  12. A role of nanotube dangling pyrrole and oxygen functions in the electrochemical synthesis of polypyrrole/MWCNTs hybrid materials

    Energy Technology Data Exchange (ETDEWEB)

    Krukiewicz, Katarzyna, E-mail: katarzyna.krukiewicz@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland); Herman, Artur P., E-mail: artur.herman@polsl.pl [Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology, Silesian University of Technology, Krzywoustego 4, Gliwice 44-100 (Poland); Turczyn, Roman, E-mail: roman.turczyn@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland); Szymańska, Katarzyna, E-mail: katarzyna.szymanska@polsl.pl [Department of Chemical and Process Engineering, Silesian University of Technology, Strzody 7, 44-100 Gliwice (Poland); Koziol, Krzysztof K.K., E-mail: kk292@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Boncel, Sławomir, E-mail: slawomir.boncel@polsl.pl [Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology, Silesian University of Technology, Krzywoustego 4, Gliwice 44-100 (Poland); Zak, Jerzy K., E-mail: jerzy.zak@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland)

    2014-10-30

    Highlights: • The effect of MWCNT functionalization on properties of PPy composites was explained. • The behavior of pristine, pyrrole-modified and oxidized MWCNT was explained. • Functionalization of MWCNT improved their dispersibility and processability. • Different mechanisms of (f-)MWCNT incorporation into PPy composites were explained. • Orientation of growing PPy chains was tailored through the addition of (f-)MWCNT. - Abstract: The effect of the functionalization of multi-walled carbon nanotubes (MWCNTs) on the process of electrochemical co-deposition of MWCNTs and polypyrrole (PPy), as well as the morphology of obtained composites have been demonstrated. As the nanotube components of the hybrids, three types of MWCNT were used, namely c-CVD derived (pristine) MWCNTs, their oxidized counterparts MWCNT-Ox and pyrrole-modified MWCNT-Py. The stability of pristine and functionalized MWCNTs (f-MWCNT) dispersions in tetrahydrofuran and water was studied together with the description of the process of formation PPy/(f-)MWCNT hybrid materials via electrochemical co-deposition. The structural and morphological properties of the hybrids were characterized by Raman spectroscopy, scanning electron microscopy and atomic force microscopy revealing substantial differences among hybrid materials in their surface morphology and the influence of MWCNT functionalization on the orientation of growing PPy chains.

  13. Self-rolling of an aluminosilicate sheet into a single walled imogolite nanotube: The role of the hydroxyl arrangement

    Energy Technology Data Exchange (ETDEWEB)

    González, R. I.; Rogan, J.; Valdivia, J. A.; Munoz, F.; Valencia, F.; Ramírez, M.; Kiwi, M. [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, 7800024 (Chile); Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Avda. Ecuador 3493, Santiago, 9170124 (Chile); Ramírez, R. [Facultad de Física, Universidad Católica de Chile, Casilla 306, Santiago, 7820436 (Chile); Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Avda. Ecuador 3493, Santiago, 9170124 (Chile)

    2015-12-31

    Imogolite is an inorganic nanotube, that forms naturally in weathered volcanic ashes, and it can be synthesized in nearly monodisperse diameters. However, long after its successful synthesis, the details of the way it is achieved are not fully understood. Here we elaborate on a model of its synthesis, which starts with a planar aluminosilicate sheet that is allowed to evolve freely, by means of classical molecular dynamics, until it achieves its minimum energy configuration. The minimal structures that the system thus adopts are tubular, scrolled, and more complex conformations, depending mainly on temperature as a driving force. Here we focus on the effect that the arrangement of the hydroxyl groups in the inner wall of the nanotube have on the minimal nanotubular configurations that we obtain are monodispersed in diameter, and quite similar to both from the those of weathered natural volcanic ashes, and to the ones that are synthesized in the laboratory. In this contribution we expand on the atomic mechanisms behind those behaviors.

  14. Synthesis of Carbon Nanotubes and Nanospheres from Coconut Fibre and the Role of Synthesis Temperature on Their Growth

    Science.gov (United States)

    Adewumi, Gloria A.; Inambao, Freddie; Eloka-Eboka, Andrew; Revaprasadu, Neerish

    2018-04-01

    Carbon nanotubes (CNT) and carbon nanospheres were successfully synthesized from coconut fibre-activated carbon. The biomass was first carbonized then physically activated, followed by treatment using ethanol vapor at 700°C to 1100°C at 100°C intervals. The effect of synthesis temperature on the formation of the nanomaterials was studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectrometry, x-ray diffraction (XRD), Fourier transform infrared microscopy (FTIR) and thermogravimetric analysis. SEM analysis revealed that nanospheres were formed at higher temperatures of 1000°C and 1100°C, while lower temperatures of 800°C and 900°C favored the growth of CNT. At 700°C, however, no tubes or spheres were formed. TEM and FTIR were used to observe spectral features, such as the peak positions, intensity and bandwidth, which are linked to some structural properties of the samples investigated. All these observations provided facts on the nanosphere and nanotube dimensions, vibrational modes and the degree of purity of the obtained samples. The TEM results show spheres of diameter in the range 50 nm to 250 nm while the tubes had diameters between 50 nm to 100 nm. XRD analysis reveals the materials synthesized are amorphous in nature with a hexagonal graphite structure.

  15. Self-rolling of an aluminosilicate sheet into a single walled imogolite nanotube: The role of the hydroxyl arrangement

    International Nuclear Information System (INIS)

    González, R. I.; Rogan, J.; Valdivia, J. A.; Munoz, F.; Valencia, F.; Ramírez, M.; Kiwi, M.; Ramírez, R.

    2015-01-01

    Imogolite is an inorganic nanotube, that forms naturally in weathered volcanic ashes, and it can be synthesized in nearly monodisperse diameters. However, long after its successful synthesis, the details of the way it is achieved are not fully understood. Here we elaborate on a model of its synthesis, which starts with a planar aluminosilicate sheet that is allowed to evolve freely, by means of classical molecular dynamics, until it achieves its minimum energy configuration. The minimal structures that the system thus adopts are tubular, scrolled, and more complex conformations, depending mainly on temperature as a driving force. Here we focus on the effect that the arrangement of the hydroxyl groups in the inner wall of the nanotube have on the minimal nanotubular configurations that we obtain are monodispersed in diameter, and quite similar to both from the those of weathered natural volcanic ashes, and to the ones that are synthesized in the laboratory. In this contribution we expand on the atomic mechanisms behind those behaviors

  16. Hidden in plain sight: the formal, informal, and hidden curricula of a psychiatry clerkship.

    Science.gov (United States)

    Wear, Delese; Skillicorn, Jodie

    2009-04-01

    To examine perceptions of the formal, informal, and hidden curricula in psychiatry as they are observed and experienced by (1) attending physicians who have teaching responsibilities for residents and medical students, (2) residents who are taught by those same physicians and who have teaching responsibilities for medical students, and (3) medical students who are taught by attendings and residents during their psychiatry rotation. From June to November 2007, the authors conducted focus groups with attendings, residents, and students in one midwestern academic setting. The sessions were audiotaped, transcribed, and analyzed for themes surrounding the formal, informal, and hidden curricula. All three groups offered a similar belief that the knowledge, skills, and values of the formal curriculum focused on building relationships. Similarly, all three suggested that elements of the informal and hidden curricula were expressed primarily as the values arising from attendings' role modeling, as the nature and amount of time attendings spend with patients, and as attendings' advice arising from experience and intuition versus "textbook learning." Whereas students and residents offered negative values arising from the informal and hidden curricula, attendings did not, offering instead the more positive values they intended to encourage through the informal and hidden curricula. The process described here has great potential in local settings across all disciplines. Asking teachers and learners in any setting to think about how they experience the educational environment and what sense they make of all curricular efforts can provide a reality check for educators and a values check for learners as they critically reflect on the meanings of what they are learning.

  17. Hidden ion population: Revisited

    International Nuclear Information System (INIS)

    Olsen, R.C.; Chappell, C.R.; Gallagher, D.L.; Green, J.L.; Gurnett, D.A.

    1985-01-01

    Satellite potentials in the outer plasmasphere range from near zero to +5 to +10 V. Under such conditions ion measurements may not include the low energy core of the plasma population. In eclipse, the photoelectron current drops to zero, and the spacecraft potential can drop to near zero volts. In regions where the ambient plasma density is below 100 cm -3 , previously unobserved portions of the ambient plasma distribution function can become visible in eclipse. A survey of the data obtained from the retarding ion mass spectrometer (RIMS) on Dynamics Explorer 1 shows that the RIMS detector generally measured the isotropic background in both sunlight and eclipse in the plasma-sphere. Absolute density measurements for the ''hidden'' ion population are obtained for the first time using the plasma wave instrument observations of the upper hybrid resonance. Agreement in total density is found in sunlight and eclipse measurements at densities above 80 cm -3 . In eclipse, agreement is found at densities as low as 20 cm -3 . The isotropic plasma composition is primarily H + , with approx.10% He + , and 0.1 to 1.0% O + . A low energy field-aligned ion population appears in eclipse measurements outside the plasmasphere, which is obscured in sunlight. These field-aligned ions can be interpreted as field-aligned flows with densities of a few particles per cubic centimeter, flowing at 5-20 km/s. The problem in measuring these field-aligned flows in sunlight is the masking of the high energy tail of the field-aligned distribution by the isotropic background. Effective measurement of the core of the magnetospheric plasma distribution awaits satellites with active means of controlling the satellite potential

  18. Stargate of the Hidden Multiverse

    Directory of Open Access Journals (Sweden)

    Alexander Antonov

    2016-02-01

    Full Text Available Concept of Monoverse, which corresponds to the existing broad interpretation of the second postulate of the special theory of relativity, is not consistent with the modern astrophysical reality — existence of the dark matter and the dark energy, the total mass-energy of which is ten times greater than the mass-energy of the visible universe (which has been considered as the entire universe until very recent . This concept does not allow to explain their rather unusual properties — invisibility and lack of baryon content — which would seem to even destroy the very modern understanding of the term ‘matter’. However, all numerous alternative concepts of Multiverses, which have been proposed until today, are unable to explain these properties of the dark matter and dark energy. This article describes a new concept: the concept of the hidden Multiverse and hidden Supermultiverse, which mutual invisibility of parallel universes is explained by the physical reality of imaginary numbers. This concept completely explains the phenomenon of the dark matter and the dark energy. Moreover, it is shown that the dark matter and the dark energy are the experimental evidence for the existence of the hidden Multiverse. Described structure of the hidden Multiverse is fully consistent with the data obtained by the space stations WMAP and Planck. An extremely important property of the hidden Multiverse is an actual possibility of its permeation through stargate located on the Earth.

  19. The role of carbon nanotubes in promoting the properties of carbon black-filled natural rubber/butadiene rubber composites

    Directory of Open Access Journals (Sweden)

    Jiangshan Gao

    Full Text Available 80/20 natural rubber (NR/butadiene rubber (BR blends in which the carbon black (CB was replaced partially by multi-walled carbon nanotubes (MWCNTs according to the ratios m (CNTs: m (decreasing amount of CB = 1: X (X was varied from 1 to 6, was prepared by blending of internal mixer and the two-roll mill at the mill opening of 0.5 mm for 10 times. SEM and TEM were used to investigate the filler networks and the good dispersion of fillers. The compounds containing 5 phr CNTs/27.5 phr CB exhibited the best abrasion resistance which was increased by 12.69% compared that without CNTs. 3D morphology images of wear surfaces and tensile fracture surfaces being similar to the layered map of the geography, which match the abrasion resistance and tensile properties, were observed by 3D measuring laser microscope. The uncured blend with 5 phr CNTs/35 phr CB showed the shortest cure time, the highest modulus and level of crosslink density. Significant improvement in mechanical properties were achieved by incorporating 5 phr CNTs and 35 phr CB, and the tear strength, 100% and 300% modulus of the vulcanizate were enhanced by 36.36%, 61.29% and 31.63% compared with the composite with 0 phr CNTs/40 phr CB, respectively. Additionally, compared with the composite without CNTs, the thermal conductivity of the composites with 5 phr CNTs/35 phr CB is increased by an average of 6.15% at three different temperatures. These considerable reinforcements resulted from the synergistic effect of CNTs and CB. Keywords: Synergistic effect, Carbon nanotubes, DIN abrasion, Mechanical properties, Thermal conductivity, 3D measuring laser microscope

  20. Hidden photons in connection to dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Andreas, Sarah; Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Goodsell, Mark D. [CPhT, Ecole Polytechnique, Palaiseau (France)

    2013-06-15

    Light extra U(1) gauge bosons, so called hidden photons, which reside in a hidden sector have attracted much attention since they are a well motivated feature of many scenarios beyond the Standard Model and furthermore could mediate the interaction with hidden sector dark matter.We review limits on hidden photons from past electron beam dump experiments including two new limits from such experiments at KEK and Orsay. In addition, we study the possibility of having dark matter in the hidden sector. A simple toy model and different supersymmetric realisations are shown to provide viable dark matter candidates in the hidden sector that are in agreement with recent direct detection limits.

  1. Hidden photons in connection to dark matter

    International Nuclear Information System (INIS)

    Andreas, Sarah; Ringwald, Andreas; Goodsell, Mark D.

    2013-06-01

    Light extra U(1) gauge bosons, so called hidden photons, which reside in a hidden sector have attracted much attention since they are a well motivated feature of many scenarios beyond the Standard Model and furthermore could mediate the interaction with hidden sector dark matter.We review limits on hidden photons from past electron beam dump experiments including two new limits from such experiments at KEK and Orsay. In addition, we study the possibility of having dark matter in the hidden sector. A simple toy model and different supersymmetric realisations are shown to provide viable dark matter candidates in the hidden sector that are in agreement with recent direct detection limits.

  2. Hidden worlds in quantum physics

    CERN Document Server

    Gouesbet, Gérard

    2014-01-01

    The past decade has witnessed a resurgence in research and interest in the areas of quantum computation and entanglement. This new book addresses the hidden worlds or variables of quantum physics. Author Gérard Gouesbet studied and worked with a former student of Louis de Broglie, a pioneer of quantum physics. His presentation emphasizes the history and philosophical foundations of physics, areas that will interest lay readers as well as professionals and advanced undergraduate and graduate students of quantum physics. The introduction is succeeded by chapters offering background on relevant concepts in classical and quantum mechanics, a brief history of causal theories, and examinations of the double solution, pilot wave, and other hidden-variables theories. Additional topics include proofs of possibility and impossibility, contextuality, non-locality, classification of hidden-variables theories, and stochastic quantum mechanics. The final section discusses how to gain a genuine understanding of quantum mec...

  3. Detecting hidden particles with MATHUSLA

    Science.gov (United States)

    Evans, Jared A.

    2018-03-01

    A hidden sector containing light long-lived particles provides a well-motivated place to find new physics. The recently proposed MATHUSLA experiment has the potential to be extremely sensitive to light particles originating from rare meson decays in the very long lifetime region. In this work, we illustrate this strength with the specific example of a light scalar mixed with the standard model-like Higgs boson, a model where MATHUSLA can further probe unexplored parameter space from exotic Higgs decays. Design augmentations should be considered in order to maximize the ability of MATHUSLA to discover very light hidden sector particles.

  4. Carbon nanotube composite materials

    Science.gov (United States)

    O'Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

    2015-03-24

    A material consisting essentially of a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes dissolved in a solvent. Un-functionalized carbon nanotube concentrations up to 30 wt % and hydroxylated carbon nanotube concentrations up to 40 wt % can be used with even small concentrations of each (less than 2 wt %) useful in producing enhanced conductivity properties of formed thin films.

  5. Hidden Crises and Communication: An Interactional Analysis of Hidden Crises

    NARCIS (Netherlands)

    dr. Annette Klarenbeek

    2011-01-01

    In this paper I describe the ways in which the communication discipline can make a hidden crisis transparent. For this purpose I examine the concept of crisis entrepreneurship from a communication point of view. Using discourse analysis, I analyse the discursive practices of crisis entrepreneurs in

  6. Hidden Crises and Communication : An Interactional Analysis of Hidden Crises

    NARCIS (Netherlands)

    dr. Annette Klarenbeek

    2011-01-01

    In this paper I describe the ways in which the communication discipline can make a hidden crisis transparent. For this purpose I examine the concept of crisis entrepreneurship from a communication point of view. Using discourse analysis, I analyse the discursive practices of crisis entrepreneurs in

  7. A study of junction effect transistors and their roles in carbon nanotube field emission cathodes in compact pulsed power applications

    Science.gov (United States)

    Shui, Qiong

    This thesis is focusing on a study of junction effect transistors (JFETs) in compact pulsed power applications. Pulsed power usually requires switches with high hold-off voltage, high current, low forward voltage drop, and fast switching speed. 4H-SiC, with a bandgap of 3.26 eV (The bandgap of Si is 1.12eV) and other physical and electrical superior properties, has gained much attention in high power, high temperature and high frequency applications. One topic of this thesis is to evaluate if 4H-SiC JFETs have a potential to replace gas phase switches to make pulsed power system compact and portable. Some other pulsed power applications require cathodes of providing stable, uniform, high electron-beam current. So the other topic of this research is to evaluate if Si JFET-controlled carbon nanotube field emitter cold cathode will provide the necessary e-beam source. In the topic of "4H-SiC JFETs", it focuses on the design and simulation of a novel 4H-SiC normally-off VJFET with high breakdown voltage using the 2-D simulator ATLAS. To ensure realistic simulations, we utilized reasonable physical models and the established parameters as the input into these models. The influence of key design parameters were investigated which would extend pulsed power limitations. After optimizing the key design parameters, with a 50-mum drift region, the predicted breakdown voltage for the VJFET is above 8kV at a leakage current of 1x10-5A/cm2 . The specific on-state resistance is 35 mO·cm 2 at VGS = 2.7 V, and the switching speed is several ns. The simulation results suggest that the 4H-SiC VJFET is a potential candidate for improving switching performance in repetitive pulsed power applications. To evaluate the 4H-SiC VJFETs in pulsed power circuits, we extracted some circuit model parameters from the simulated I-V curves. Those parameters are necessary for circuit simulation program such as SPICE. This method could be used as a test bench without fabricating the devices to

  8. Quantum transport in carbon nanotubes

    NARCIS (Netherlands)

    Laird, E.A.; Kuemmeth, F.; Steele, G.A.; Grove-Rasmussen, K.; Nygard, J.; Flensberg, K.; Kouwenhoven, L.P.

    2015-01-01

    Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin and valley degrees of freedom. This

  9. Probing the role of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) -coated multiwalled carbon nanotubes in the thermal and mechanical properties of polycarbonate nanocomposites

    KAUST Repository

    Zhou, Jian

    2014-03-05

    The role played by multiwalled carbon nanotubes (MWCNTs) coated with poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) in the thermal and mechanical properties of polycarbonate (PC) nanocomposites was analyzed. We used differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) to demonstrate that the glass transition temperature of polycarbonate nanocomposites decreased whereas the storage modulus of the samples increased by including PEDOT/PSS-coated MWCNTs. These results indicated that PEDOT/PSS acts as an antiplasticizer. We attributed the enhancement of the storage modulus to the strong hydrogen bonding between PSS and the PC matrix and the reduction of the free volume in the PC matrix due to the shrinkage of PEDOT/PSS upon heating. We also investigated changes in the thermal conductivity and thermal degradation behavior of the nanocomposites. The results indicated that PEDOT/PSS did not play a significant role in improving the thermal conductivity and thermal stability of PC nanocomposites. The relative improvements in the conductivity and thermal stability of the samples that contained PEDOT/PSS were attributed to the better dispersion of the MWCNTs in the PC matrix. © 2014 American Chemical Society.

  10. Entry deterrence and hidden competition

    NARCIS (Netherlands)

    Lavrutich, Maria; Huisman, Kuno; Kort, Peter

    This paper studies strategic investment behavior of firms facing an uncertain demand in a duopoly setting. Firms choose both investment timing and the capacity level while facing additional uncertainty about market participants, which is introduced via the concept of hidden competition. We focus on

  11. Adaptive Partially Hidden Markov Models

    DEFF Research Database (Denmark)

    Forchhammer, Søren Otto; Rasmussen, Tage

    1996-01-01

    Partially Hidden Markov Models (PHMM) have recently been introduced. The transition and emission probabilities are conditioned on the past. In this report, the PHMM is extended with a multiple token version. The different versions of the PHMM are applied to bi-level image coding....

  12. The Hidden Dimensions of Databases.

    Science.gov (United States)

    Jacso, Peter

    1994-01-01

    Discusses methods of evaluating commercial online databases and provides examples that illustrate their hidden dimensions. Topics addressed include size, including the number of records or the number of titles; the number of years covered; and the frequency of updates. Comparisons of Readers' Guide Abstracts and Magazine Article Summaries are…

  13. Role of solution chemistry on the trapping of radionuclide Th(IV) using titanate nanotubes as an efficient adsorbent

    International Nuclear Information System (INIS)

    Guodong Sheng; Chinese Academy of Sciences, Hefei; Baowei Hu

    2013-01-01

    Titanate nanotubes (TNTs) have attracted great interest in multidisciplinary study since their discovery. The adsorption of thorium [Th(IV)] onto TNTs in the absence and presence of humic acid (HA)/fulvic acid (FA) was studied by batch technique. The influence of pH from 2.0 to 10.0, ionic strength from 0.001 to 0.1 mol L -1 NaClO 4 , and coexisting electrolyte cations (Li + , Na + , K + ) and anions (ClO 4 - , NO 3 - , Cl - ) on the adsorption of Th(IV) onto TNTs was tested. The adsorption isotherms of Th(IV) was determined at pH 3.0 and analyzed with Langmuir and Freundlich adsorption models, respectively. The results demonstrated that the adsorption of Th(IV) onto TNTs increases steeply with increasing pH from 2.0 to 4.0. Generally, HA/FA was showed to enhance Th(IV) adsorption onto TNTs at low pH values, but to reduce Th(IV) adsorption onto TNTs at high pH values. The adsorption of Th(IV) onto TNTs was also dependent on coexisting electrolyte ions in aqueous solution under our experimental conditions. The adsorption of Th(IV) onto TNTs is exothermic and spontaneous. The findings indicating that TNTs can be used as a promising candidate for the enrichment and solidification of Th(IV) or its analogue actinides from large volume solution in real work. (author)

  14. Dispersant affects the cellular influences of single-wall carbon nanotube: the role of CNT as carrier of dispersants.

    Science.gov (United States)

    Horie, Masanori; Stowe, Mayumi; Tabei, Miki; Kato, Haruhisa; Nakamura, Ayako; Endoh, Shigehisa; Morimoto, Yasuo; Fujita, Katsuhide

    2013-06-01

    The application of carbon nanotube (CNT) as a functional material to engineering and life sciences is advanced. In order to evaluate the cytotoxicity of CNT in vitro, some chemical and biological reagents are used for dispersants. In the present study, the cellular influences of six kinds of chemical or biological reagents used as dispersants were examined. Pluronic F-127, Pluronic F-68, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), pulmonary surfactant preparation Surfacten®, bovine serum albumin (BSA) and Tween 80 were used in the preparation of CNT-medium dispersants. The influences of each reagent on cell viability in human lung carcinoma A549 cells were small. However, Pluronic F-127, DPPC, Surfacten® and Tween 80 induced an increase of intracellular reactive oxygen species (ROS) level. Next, CNT-medium dispersions were prepared, using each reagent as a dispersant and applied to A549 cells. The cellular influences depended on the kind of dispersant. Cells exposed to CNT dispersion including Pluronic® F-127, Surfacten®, DPPC and Tween 80 showed LDH release to the culture supernatant. Induction of intracellular ROS level was observed in cells exposed to CNT dispersion including each reagent except BSA. These results suggest that the adsorbed dispersant reagents on the surface of the CNT affect its cellular influences, particularly the induction of oxidative stress.

  15. Depression among current, former, and never smokers from 2005 to 2013: The hidden role of disparities in depression in the ongoing tobacco epidemic.

    Science.gov (United States)

    Goodwin, Renee D; Wall, Melanie M; Garey, Lorra; Zvolensky, Michael J; Dierker, Lisa; Galea, Sandro; Gbedemah, Misato; Weinberger, Andrea H; Williams, Jill M; Hu, Mei-Chen; Hasin, Deborah S

    2017-04-01

    After declining sharply for many years, the prevalence of smoking has remained fairly stable over the past decade. One possible explanation is that there has been an increase in the prevalence of barriers to cessation, like depression, among remaining smokers. To estimate changes in the prevalence of depression among current, former and never smokers in the United States (U.S.) population from 2005 to 2013 overall and by age, gender, and income. Data were drawn from the National Household Survey on Drug Use (NSDUH), an annual cross-sectional study of persons ages 12 and over (N=496,805). The prevalence of past 12-month depression was examined annually among current (past 12-month), former (not past 12-month), and lifetime non-smokers from 2005 to 2013. Data were re-analyzed stratified by age, gender, and household income, and adjusted for demographics. Depression appears to have significantly increased in the United States from 2005 to 2013 among current, former, and never smokers. Depression prevalence increased among current smokers overall, but the increase among former and never smokers was even more prominent. Striking temporal changes emerged by age, gender and income. Specifically, (1) depression increased significantly among current smokers aged 12-17 (from 16% to 22%, p-value=0.0002) and the prevalence was consistently more than twice as high as that of never smokers; (2) depression increased among male smokers (6.19%-7.82%, p-value=0.0099); (3) depression increased significantly among smokers in the highest income group (6.36% to 8.91%, p-value=0.0400). Throughout this period, the prevalence of depression among current smokers was consistently twice as high as among former and never smokers. Public health efforts aimed at decreasing the prevalence of smoking should take depression into account, a common and modifiable barrier whose treatment may help to increase successful smoking cessation. Future work is needed to disentangle the role of smoking and

  16. The Hidden STEM Economy

    Science.gov (United States)

    Rothwell, Jonathan

    2013-01-01

    Workers in STEM (science, technology, engineering, and math) fields play a direct role in driving economic growth. Yet, because of how the STEM economy has been defined, policymakers have mainly focused on supporting workers with at least a bachelor's (BA) degree, overlooking a strong potential workforce of those with less than a BA. This report…

  17. Respiratory Effects of Inhaled Single-Walled Carbon Nanotubes: The Role of Particle Morphology and Iron Content

    Science.gov (United States)

    Madl, Amy Kathleen

    Nanotechnology provides promise for significant advancements in a number of different fields including imaging, electronics, and therapeutics. With worldwide production of carbon nanotubes (CNTs) exceeding over 500 metric tons annually and industry growth expecting to double over the next 5 yr, there are concerns our understanding of the hazards of these nanomaterials may not be keeping pace with market demand. The physicochemical properties of CNTs may delineate the key features that determine either toxicity or biocompatibility and assist in evaluating the potential health risks posed in industrial and consumer product settings. We hypothesized that the iron content and morphology of inhaled single-walled carbon nanotubes (SWCNTs) influences the extent of cellular injury and alters homeostasis in the lung. To address this hypothesis, (1) an aerosol system was developed to deliver carbon-based nanomaterials in a manner of exposure that is physiologically and environmentally relevant (e.g., inhalation), (2) acute (1 d) and subacute (10 d) nose-only inhalation studies to a well-characterized aerosol of iron-containing (FeSWCNT) versus cleaned (iron removed, cSWCNTs) SWCNTs were conducted to evaluate the time-course patterns of possible injury through measurement of markers of cytotoxicity, inflammation, and cellular remodeling/homeostasis, and (3) the effects of SWCNTs were compared to other well-studied materials (e.g. non-fibrous, low-iron content ultrafine carbon black and fibrous, high-iron content, highly persistent, durable and potent carcinogen crocidolite) to offer insights into the relative toxicity of these nanomaterials as well as the possible mechanisms by which the effects occur. Rats (SD) were exposed to either aerosolized SWCNTs (raw FeSWCNT or purified cSWCNT), carbon black (CB), crocidolite, or fresh air via nose-only inhalation. Markers of inflammation and cytotoxicity in lung lavage, mucin in different airway generations, and collagen in the

  18. Atlas of solar hidden photon emission

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Javier [Departamento de Física Teórica, Universidad de Zaragoza,Pedro Cerbuna 12, E-50009, Zaragoza (Spain); Max-Planck-Institut für Physik, Werner-Heisenberg-Institut,Föhringer Ring 6, 80805 München (Germany)

    2015-07-20

    Hidden photons, gauge bosons of a U(1) symmetry of a hidden sector, can constitute the dark matter of the universe and a smoking gun for large volume compactifications of string theory. In the sub-eV mass range, a possible discovery experiment consists on searching the copious flux of these particles emitted from the Sun in a helioscope setup à la Sikivie. In this paper, we compute in great detail the flux of HPs from the Sun, a necessary ingredient for interpreting such experiments. We provide a detailed exposition of transverse photon-HP oscillations in inhomogenous media, with special focus on resonance oscillations, which play a leading role in many cases. The region of the Sun emitting HPs resonantly is a thin spherical shell for which we justify an averaged-emission formula and which implies a distinctive morphology of the angular distribution of HPs on Earth in many cases. Low mass HPs with energies in the visible and IR have resonances very close to the photosphere where the solar plasma is not fully ionised and requires building a detailed model of solar refraction and absorption. We present results for a broad range of HP masses (from 0–1 keV) and energies (from the IR to the X-ray range), the most complete atlas of solar HP emission to date.

  19. Atlas of solar hidden photon emission

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Javier, E-mail: redondo@mpp.mpg.de [Departamento de Física Teórica, Universidad de Zaragoza, Pedro Cerbuna 12, E-50009, Zaragoza, España (Spain)

    2015-07-01

    Hidden photons, gauge bosons of a U(1) symmetry of a hidden sector, can constitute the dark matter of the universe and a smoking gun for large volume compactifications of string theory. In the sub-eV mass range, a possible discovery experiment consists on searching the copious flux of these particles emitted from the Sun in a helioscope setup à la Sikivie. In this paper, we compute in great detail the flux of HPs from the Sun, a necessary ingredient for interpreting such experiments. We provide a detailed exposition of transverse photon-HP oscillations in inhomogenous media, with special focus on resonance oscillations, which play a leading role in many cases. The region of the Sun emitting HPs resonantly is a thin spherical shell for which we justify an averaged-emission formula and which implies a distinctive morphology of the angular distribution of HPs on Earth in many cases. Low mass HPs with energies in the visible and IR have resonances very close to the photosphere where the solar plasma is not fully ionised and requires building a detailed model of solar refraction and absorption. We present results for a broad range of HP masses (from 0–1 keV) and energies (from the IR to the X-ray range), the most complete atlas of solar HP emission to date.

  20. HIDDEN WAR AGAINST WOMEN

    Directory of Open Access Journals (Sweden)

    Şehriban Şahin Kaya

    2011-01-01

    Full Text Available For the last couple of decades, there has been a dramatic regress in the women’seconomic, social and political positions in Turkey.The number of womenparticipating in job market decreased from 34.1 percent in 1990 to 23.5 percent in2009. Almost 85 percent of the working women are still stuck in traditionalfemale jobs. A diminishing representation of womenin politics and increasingviolence against women have been other features ofthis regression. At the sametime period, a transformation of Turkish media camewith the boom of the numberof commercial TV channels, radio stations, magazines and newspapers. Thisnewly transformed media did manage traditional gender roles to infiltrate thethoughts of women, majority of whom stayed out of job market. The images ofwomen created through the advertisements, TV serials, TV talk shows, andmagazines have been more altruistic family orientedtype than women questingfor equal rights. Today, more and more women watchTV programs, supportcosmetic industry, spend lots of money on clothing, and are very interested intheir body, value traditional gender roles and do not ask for equality. Recently,the scholars began to discuss the rise of conservatism in Turkey withoutaddressing the backward shift in women position invarious spheres of life. Allthese problematical issues mentioned above need tobe considered within asociological framework that should be able to showus the current situation ofwomen in Turkey. This presentation attempts to dothis.

  1. Analysing the hidden curriculum: use of a cultural web.

    Science.gov (United States)

    Mossop, Liz; Dennick, Reg; Hammond, Richard; Robbé, Iain

    2013-02-01

    Major influences on learning about medical professionalism come from the hidden curriculum. These influences can contribute positively or negatively towards the professional enculturation of clinical students. The fact that there is no validated method for identifying the components of the hidden curriculum poses problems for educators considering professionalism. The aim of this study was to analyse whether a cultural web, adapted from a business context, might assist in the identification of elements of the hidden curriculum at a UK veterinary school. A qualitative approach was used. Seven focus groups consisting of three staff groups and four student groups were organised. Questioning was framed using the cultural web, which is a model used by business owners to assess their environment and consider how it affects their employees and customers. The focus group discussions were recorded, transcribed and analysed thematically using a combination of a priori and emergent themes. The cultural web identified elements of the hidden curriculum for both students and staff. These included: core assumptions; routines; rituals; control systems; organisational factors; power structures, and symbols. Discussions occurred about how and where these issues may affect students' professional identity development. The cultural web framework functioned well to help participants identify elements of the hidden curriculum. These aspects aligned broadly with previously described factors such as role models and institutional slang. The influence of these issues on a student's development of a professional identity requires discussion amongst faculty staff, and could be used to develop learning opportunities for students. The framework is promising for the analysis of the hidden curriculum and could be developed as an instrument for implementation in other clinical teaching environments. © Blackwell Publishing Ltd 2013.

  2. Hidden supersymmetry and large N

    International Nuclear Information System (INIS)

    Alfaro, J.

    1988-01-01

    In this paper we present a new method to deal with the leading order in the large-N expansion of a quantum field theory. The method uses explicitly the hidden supersymmetry that is present in the path-integral formulation of a stochastic process. In addition to this we derive a new relation that is valid in the leading order of the large-N expansion of the hermitian-matrix model for any spacetime dimension. (orig.)

  3. Nanotubes and nanowires

    Indian Academy of Sciences (India)

    Unknown

    junction nanotubes by the pyrolysis of appropriate organic precursors. ... By making use of carbon nanotubes, nanowires of metals, metal ..... The use of activated carbon in place of ..... required for the complete removal of the carbon template.

  4. Carbon nanotube nanoelectrode arrays

    Science.gov (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  5. ESO's Hidden Treasures Brought to Light

    Science.gov (United States)

    2011-01-01

    Adam Kiil. 19. NGC 2467 - number 2 by Josh Barrington. 20. Haffner 18 and 19 by Javier Fuentes. Igor Chekalin, winner of the trip to Paranal, says: "It was a great experience and pleasure to work with such amazing data. As an amateur astrophotographer, this was the most difficult processing and post-processing job I have ever done. My participation in the Hidden Treasures competition gave me a range of challenges, from installing new software to studying techniques and even operating systems that I did not know before." The success of the ESO's Hidden Treasures 2010 competition and the enthusiasm of the skilled participants made it easy to decide to run a follow-up to the competition. Stay tuned and check www.eso.org for news about ESO's Hidden Treasures 2011. More information ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and VISTA, the world's largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".

  6. Hidden particle production at the ILC

    International Nuclear Information System (INIS)

    Fujii, Keisuke; Itoh, Hideo; Okada, Nobuchika; Hano, Hitoshi; Yoshioka, Tamaki

    2008-01-01

    In a class of new physics models, the new physics sector is completely or partly hidden, namely, a singlet under the standard model (SM) gauge group. Hidden fields included in such new physics models communicate with the standard model sector through higher-dimensional operators. If a cutoff lies in the TeV range, such hidden fields can be produced at future colliders. We consider a scalar field as an example of the hidden fields. Collider phenomenology on this hidden scalar is similar to that of the SM Higgs boson, but there are several features quite different from those of the Higgs boson. We investigate productions of the hidden scalar at the International Linear Collider (ILC) and study the feasibility of its measurements, in particular, how well the ILC distinguishes the scalar from the Higgs boson, through realistic Monte Carlo simulations.

  7. New Insight into Carbon Nanotube Electronic Structure Selectivity

    Energy Technology Data Exchange (ETDEWEB)

    Sumpter, Bobby G [ORNL; Meunier, Vincent [ORNL; Jiang, Deen [ORNL

    2009-01-01

    The fundamental role of aryl diazonium salts for post synthesis selectivity of carbon nanotubes is investigated using extensive electronic structure calculations. The resulting understanding for diazonium salt based selective separation of conducting and semiconducting carbon nanotubes shows how the primary contributions come from the interplay between the intrinsic electronic structure of the carbon nanotubes and that of the anion of the salt. We demonstrate how the electronic transport properties change upon the formation of charge transfer complexes and upon their conversion into covalently attached functional groups. Our results are found to correlate well with experiments and provide for the first time an atomistic description for diazonium salt based chemical separation of carbon nanotubes

  8. The role of catalytic nanoparticle pretreatment on the growth of vertically aligned carbon nanotubes by hot-filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Hwan; Gohier, Aurélien; Bourée, Jean Eric; Châtelet, Marc; Cojocaru, Costel-Sorin, E-mail: costel-sorin.cojocaru@polytechnique.edu

    2015-01-30

    The effect of atomic hydrogen assisted pre-treatment on the growth of vertically aligned carbon nanotubes using hot-filament chemical vapor deposition was investigated. Iron nanoparticle catalysts were formed on an aluminum oxide support layer by spraying of iron chloride salt solutions as catalyst precursor. It is found that pre-treatment time and process temperature tune the density as well as the shape and the structure of the grown carbon nanotubes. An optimum pre-treatment time can be found for the growth of long and well aligned carbon nanotubes, densely packed to each other. To provide insight on this behavior, the iron catalytic nanoparticles formed after the atomic hydrogen assisted pre-treatment were analyzed by atomic force microscopy. The relations between the size and the density of the as-formed catalyst and the as-grown carbon nanotube's structure and density are discussed. - Highlights: • Effect of the atomic hydrogen assisted pre-treatment on the growth of VACNT using hot-filament CVD. • Pre-treatment time and process temperature tune the density, the shape and the structure of the CNTs. • Correlations between size and density of the as-formed catalyst and the CNT’s structure and density. • Carbon nanotubes synthesized at low temperature down to 500 °C using spayed iron chloride salts. • Density of the CNT carpet adjusted by catalytic nanoparticle engineering.

  9. Hidden measurements, hidden variables and the volume representation of transition probabilities

    OpenAIRE

    Oliynyk, Todd A.

    2005-01-01

    We construct, for any finite dimension $n$, a new hidden measurement model for quantum mechanics based on representing quantum transition probabilities by the volume of regions in projective Hilbert space. For $n=2$ our model is equivalent to the Aerts sphere model and serves as a generalization of it for dimensions $n \\geq 3$. We also show how to construct a hidden variables scheme based on hidden measurements and we discuss how joint distributions arise in our hidden variables scheme and th...

  10. Phytotoxicity of multi-walled carbon nanotubes on red spinach (Amaranthus tricolor L) and the role of ascorbic acid as an antioxidant

    International Nuclear Information System (INIS)

    Begum, Parvin; Fugetsu, Bunshi

    2012-01-01

    Highlights: ► MWNTs are selected for study of the systemic toxicity and the potential influence on red spinach. ► Microscopic observation revealed some adverse effects on root and leaf. ► Cell damage were detected on 15 days after the exposure to MWNTs. ► ROS increase ceased once ascorbic acid was added into media. ► Oxidative stress seems to be the key element responsible for causing the toxicity. - Abstract: Carbon nanotubes (CNTs) are a novel nanomaterial with wide potential applications; however the adverse effects of CNTs following environmental exposure have recently received significant attention. Herein, we explore the systemic toxicity and potential influence of 0–1000 mg L −1 the multi-walled CNTs on red spinach. The multi-walled CNTs exposed plants exhibited growth inhibition and cell death after 15 days of hydroponic culture. The multi-walled CNTs had adverse effects on root and leaf morphology, as observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Raman spectroscopy detected the multi-walled CNTs in leaves. Biomarkers of nanoparticle toxicity, reactive oxygen species (ROS), and cell damage in the red spinach were greatly increased 15 days post-exposure to the multi-walled CNTs. These effects were reversed when the multi-walled CNTs were supplemented with ascorbic acid (AsA), suggesting a role of ROS in the multl-walled CNT-induced toxicity and that the primary mechanism of the multi-walled CNTs’ toxicity is oxidative stress.

  11. Phytotoxicity of multi-walled carbon nanotubes on red spinach (Amaranthus tricolor L) and the role of ascorbic acid as an antioxidant

    Energy Technology Data Exchange (ETDEWEB)

    Begum, Parvin [Laboratory of Environmental Medical Chemistry, Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Fugetsu, Bunshi, E-mail: hu@ees.hokudai.ac.jp [Laboratory of Environmental Medical Chemistry, Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer MWNTs are selected for study of the systemic toxicity and the potential influence on red spinach. Black-Right-Pointing-Pointer Microscopic observation revealed some adverse effects on root and leaf. Black-Right-Pointing-Pointer Cell damage were detected on 15 days after the exposure to MWNTs. Black-Right-Pointing-Pointer ROS increase ceased once ascorbic acid was added into media. Black-Right-Pointing-Pointer Oxidative stress seems to be the key element responsible for causing the toxicity. - Abstract: Carbon nanotubes (CNTs) are a novel nanomaterial with wide potential applications; however the adverse effects of CNTs following environmental exposure have recently received significant attention. Herein, we explore the systemic toxicity and potential influence of 0-1000 mg L{sup -1} the multi-walled CNTs on red spinach. The multi-walled CNTs exposed plants exhibited growth inhibition and cell death after 15 days of hydroponic culture. The multi-walled CNTs had adverse effects on root and leaf morphology, as observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Raman spectroscopy detected the multi-walled CNTs in leaves. Biomarkers of nanoparticle toxicity, reactive oxygen species (ROS), and cell damage in the red spinach were greatly increased 15 days post-exposure to the multi-walled CNTs. These effects were reversed when the multi-walled CNTs were supplemented with ascorbic acid (AsA), suggesting a role of ROS in the multl-walled CNT-induced toxicity and that the primary mechanism of the multi-walled CNTs' toxicity is oxidative stress.

  12. Dissipative hidden sector dark matter

    Science.gov (United States)

    Foot, R.; Vagnozzi, S.

    2015-01-01

    A simple way of explaining dark matter without modifying known Standard Model physics is to require the existence of a hidden (dark) sector, which interacts with the visible one predominantly via gravity. We consider a hidden sector containing two stable particles charged under an unbroken U (1 )' gauge symmetry, hence featuring dissipative interactions. The massless gauge field associated with this symmetry, the dark photon, can interact via kinetic mixing with the ordinary photon. In fact, such an interaction of strength ε ˜10-9 appears to be necessary in order to explain galactic structure. We calculate the effect of this new physics on big bang nucleosynthesis and its contribution to the relativistic energy density at hydrogen recombination. We then examine the process of dark recombination, during which neutral dark states are formed, which is important for large-scale structure formation. Galactic structure is considered next, focusing on spiral and irregular galaxies. For these galaxies we modeled the dark matter halo (at the current epoch) as a dissipative plasma of dark matter particles, where the energy lost due to dissipation is compensated by the energy produced from ordinary supernovae (the core-collapse energy is transferred to the hidden sector via kinetic mixing induced processes in the supernova core). We find that such a dynamical halo model can reproduce several observed features of disk galaxies, including the cored density profile and the Tully-Fisher relation. We also discuss how elliptical and dwarf spheroidal galaxies could fit into this picture. Finally, these analyses are combined to set bounds on the parameter space of our model, which can serve as a guideline for future experimental searches.

  13. Identifying hidden sexual bridging communities in Chicago.

    Science.gov (United States)

    Youm, Yoosik; Mackesy-Amiti, Mary Ellen; Williams, Chyvette T; Ouellet, Lawrence J

    2009-07-01

    Bridge populations can play a central role in the spread of human immunodeficiency virus (HIV) by providing transmission links between higher and lower prevalence populations. While social network methods are well suited to the study of bridge populations, analyses tend to focus on dyads (i.e., risk between drug and/or sex partners) and ignore bridges between distinct subpopulations. This study takes initial steps toward moving the analysis of sexual network linkages beyond individual and risk group levels to a community level in which Chicago's 77 community areas are examined as subpopulations for the purpose of identifying potential bridging communities. Of particular interest are "hidden" bridging communities; that is, areas with above-average levels of sexual ties with other areas but whose below-average AIDS prevalence may hide their potential importance for HIV prevention. Data for this analysis came from the first wave of recruiting at the Chicago Sexual Acquisition and Transmission of HIV Cooperative Agreement Program site. Between August 2005 through October 2006, respondent-driven sampling was used to recruit users of heroin, cocaine, or methamphetamine, men who have sex with men regardless of drug use, the sex partners of these two groups, and sex partners of the sex partners. In this cross-sectional study of the sexual transmission of HIV, participants completed a network-focused computer-assisted self-administered interview, which included questions about the geographic locations of sexual contacts with up to six recent partners. Bridging scores for each area were determined using a matrix representing Chicago's 77 community areas and were assessed using two measures: non-redundant ties and flow betweenness. Bridging measures and acquired immunodeficiency syndrome (AIDS) case prevalence rates were plotted for each community area on charts representing four conditions: below-average bridging and AIDS prevalence, below-average bridging and above

  14. Skyrmions with holography and hidden local symmetry

    International Nuclear Information System (INIS)

    Nawa, Kanabu; Hosaka, Atsushi; Suganuma, Hideo

    2009-01-01

    We study baryons as Skyrmions in holographic QCD with D4/D8/D8 multi-D brane system in type IIA superstring theory, and also in the nonlinear sigma model with hidden local symmetry. Comparing these two models, we find that the extra dimension and its nontrivial curvature can largely change the role of (axial) vector mesons for baryons in four-dimensional space-time. In the hidden local symmetry approach, the ρ-meson field as a massive Yang-Mills field has a singular configuration in Skyrmion, which gives a strong repulsion for the baryon as a stabilizer. When the a 1 meson is added in this approach, the stability of Skyrmion is lost by the cancellation of ρ and a 1 contributions. On the contrary, in holographic QCD, the ρ-meson field does not appear as a massive Yang-Mills field due to the extra dimension and its nontrivial curvature. We show that the ρ-meson field has a regular configuration in Skyrmion, which gives a weak attraction for the baryon in holographic QCD. We argue that Skyrmion with π, ρ, and a 1 mesons become stable due to the curved extra dimension and also the presence of the Skyrme term in holographic QCD. From this result, we also discuss the features of our truncated-resonance analysis on baryon properties with π and ρ mesons below the cutoff scale M KK ∼1 GeV in holographic QCD, which is compared with other 5D instanton analysis.

  15. Hidden inventory and safety considerations

    International Nuclear Information System (INIS)

    Anderson, A.R.; James, R.H.; Morgan, F.

    1976-01-01

    Preliminary results are described of the evaluation of residual plutonium in a process line used for the production of experimental fast reactor fuel. Initial attention has been focussed on a selection of work boxes used for processing powders and solutions. Amounts of material measured as ''hidden inventory'' are generally less than 0.1 percent of throughput but in one box containing very complex equipment the amount was exceptionally about 0.5 percent. The total surface area of the box and the installed equipment appears to be the most significant factor in determining the amount of plutonium held-up as ''hidden inventory,'' representing an average of about 4 x 10 -4 g cm -2 . Present results are based on gamma spectrometer measurements but neutron techniques are being developed to overcome some of the inherent uncertainties in the gamma method. It is suggested that the routine use of sample plates of known surface area would be valuable in monitoring the deposition of plutonium in work boxes

  16. Hidden costs of nuclear power

    International Nuclear Information System (INIS)

    England, R.W.

    1979-01-01

    Mr. England contends that these hidden costs add up to a figure much higher than those that appear in the electric utilities' profit and loss account - costs that are borne by Federal taxpayers, by nuclear industry workers, and by all those people who must share their environment with nuclear facilities. Costs he details are additional deaths and illnesses resulting from exposure to radiation, and the use of tax dollars to clean up the lethal garbage produced by those activities. He asserts that careless handling of uranium ore and mill tailings in past years has apparently resulted in serious public health problems in those mining communities. In another example, Mr. England states that the failure to isolate uranium tailings physically from their environment has probably contributed to an acute leukemia rate in Mesa County, Colorado. He mentions much of the technology development for power reactors being done by the Federal government, not by private reactor manufacturers - thus, again, hidden costs that do not show up in electric bills of customers. The back end of the nuclear fuel cycle as a place for Federally subsidized research and development is discussed briefly. 1 figure, 2 tables

  17. The hidden and informal curriculum across the continuum of training: A cross-sectional qualitative study.

    Science.gov (United States)

    Doja, Asif; Bould, M Dylan; Clarkin, Chantalle; Eady, Kaylee; Sutherland, Stephanie; Writer, Hilary

    2016-04-01

    The hidden and informal curricula refer to learning in response to unarticulated processes and constraints, falling outside the formal medical curriculum. The hidden curriculum has been identified as requiring attention across all levels of learning. We sought to assess the knowledge and perceptions of the hidden and informal curricula across the continuum of learning at a single institution. Focus groups were held with undergraduate and postgraduate learners and faculty to explore knowledge and perceptions relating to the hidden and informal curricula. Thematic analysis was conducted both inductively by research team members and deductively using questions structured by the existing literature. Participants highlighted several themes related to the presence of the hidden and informal curricula in medical training and practice, including: the privileging of some specialties over others; the reinforcement of hierarchies within medicine; and a culture of tolerance towards unprofessional behaviors. Participants acknowledged the importance of role modeling in the development of professional identities and discussed the deterioration in idealism that occurs. Common issues pertaining to the hidden curriculum exist across all levels of learners, including faculty. Increased awareness of these issues could allow for the further development of methods to address learning within the hidden curriculum.

  18. The Hidden Reason Behind Children's Misbehavior.

    Science.gov (United States)

    Nystul, Michael S.

    1986-01-01

    Discusses hidden reason theory based on the assumptions that: (1) the nature of people is positive; (2) a child's most basic psychological need is involvement; and (3) a child has four possible choices in life (good somebody, good nobody, bad somebody, or severely mentally ill.) A three step approach for implementing hidden reason theory is…

  19. Hidden neural networks: application to speech recognition

    DEFF Research Database (Denmark)

    Riis, Søren Kamaric

    1998-01-01

    We evaluate the hidden neural network HMM/NN hybrid on two speech recognition benchmark tasks; (1) task independent isolated word recognition on the Phonebook database, and (2) recognition of broad phoneme classes in continuous speech from the TIMIT database. It is shown how hidden neural networks...

  20. Hidden supersymmetry and Fermion number fractionalization

    International Nuclear Information System (INIS)

    Akhoury, R.

    1985-01-01

    This paper discusses how a hidden supersymmetry of the underlying field theories can be used to interpret and to calculate fermion number fractionalization in different dimensions. This is made possible by relating it to a corresponding Witten index of the hidden supersymmetry. The closely related anomalies in odd dimensions are also discussed

  1. Helioscope bounds on hidden sector photons

    International Nuclear Information System (INIS)

    Redondo, J.

    2008-01-01

    The flux of hypothetical ''hidden photons'' from the Sun is computed under the assumption that they interact with normal matter only through kinetic mixing with the ordinary standard model photon. Requiring that the exotic luminosity is smaller than the standard photon luminosity provides limits for the mixing parameter down to χ -14 , depending on the hidden photon mass. Furthermore, it is pointed point out that helioscopes looking for solar axions are also sensitive to hidden photons. The recent results of the CAST collaboration are used to further constrain the mixing parameter χ at low masses (m γ' <1 eV) where the luminosity bound is weaker. In this regime the solar hidden photon ux has a sizable contribution of longitudinally polarized hidden photons of low energy which are invisible for current helioscopes. (orig.)

  2. Significant promotion effect of carbon nanotubes on the electrocatalytic activity of supported Pd NPs for ethanol oxidation reaction of fuel cells: the role of inner tubes.

    Science.gov (United States)

    Zhang, Jin; Cheng, Yi; Lu, Shanfu; Jia, Lichao; Shen, Pei Kang; Jiang, San Ping

    2014-11-18

    The inner tubes of carbon nanotubes (CNTs) have a significant promotion effect on the electrocatalytic activity of Pd nanoparticles (NPs) for the ethanol oxidation of direct alcohol fuel cells (DAFCs) and Pd NPs supported on CNTs with 3-7 walls show a much higher activity as compared to that supported on typical single-walled and multi-walled CNTs.

  3. Proteomic analysis of HIV-1 Nef cellular binding partners reveals a role for exocyst complex proteins in mediating enhancement of intercellular nanotube formation

    Directory of Open Access Journals (Sweden)

    Mukerji Joya

    2012-06-01

    Full Text Available Abstract Background HIV-1 Nef protein contributes to pathogenesis via multiple functions that include enhancement of viral replication and infectivity, alteration of intracellular trafficking, and modulation of cellular signaling pathways. Nef stimulates formation of tunneling nanotubes and virological synapses, and is transferred to bystander cells via these intercellular contacts and secreted microvesicles. Nef associates with and activates Pak2, a kinase that regulates T-cell signaling and actin cytoskeleton dynamics, but how Nef promotes nanotube formation is unknown. Results To identify Nef binding partners involved in Pak2-association dependent Nef functions, we employed tandem mass spectrometry analysis of Nef immunocomplexes from Jurkat cells expressing wild-type Nef or Nef mutants defective for the ability to associate with Pak2 (F85L, F89H, H191F and A72P, A75P in NL4-3. We report that wild-type, but not mutant Nef, was associated with 5 components of the exocyst complex (EXOC1, EXOC2, EXOC3, EXOC4, and EXOC6, an octameric complex that tethers vesicles at the plasma membrane, regulates polarized exocytosis, and recruits membranes and proteins required for nanotube formation. Additionally, Pak2 kinase was associated exclusively with wild-type Nef. Association of EXOC1, EXOC2, EXOC3, and EXOC4 with wild-type, but not mutant Nef, was verified by co-immunoprecipitation assays in Jurkat cells. Furthermore, shRNA-mediated depletion of EXOC2 in Jurkat cells abrogated Nef-mediated enhancement of nanotube formation. Using bioinformatic tools, we visualized protein interaction networks that reveal functional linkages between Nef, the exocyst complex, and the cellular endocytic and exocytic trafficking machinery. Conclusions Exocyst complex proteins are likely a key effector of Nef-mediated enhancement of nanotube formation, and possibly microvesicle secretion. Linkages revealed between Nef and the exocyst complex suggest a new paradigm of

  4. Hidden scale invariance of metals

    DEFF Research Database (Denmark)

    Hummel, Felix; Kresse, Georg; Dyre, Jeppe C.

    2015-01-01

    Density functional theory (DFT) calculations of 58 liquid elements at their triple point show that most metals exhibit near proportionality between the thermal fluctuations of the virial and the potential energy in the isochoric ensemble. This demonstrates a general “hidden” scale invariance...... of metals making the condensed part of the thermodynamic phase diagram effectively one dimensional with respect to structure and dynamics. DFT computed density scaling exponents, related to the Grüneisen parameter, are in good agreement with experimental values for the 16 elements where reliable data were...... available. Hidden scale invariance is demonstrated in detail for magnesium by showing invariance of structure and dynamics. Computed melting curves of period three metals follow curves with invariance (isomorphs). The experimental structure factor of magnesium is predicted by assuming scale invariant...

  5. Hidden Valley Search at ATLAS

    CERN Document Server

    Verducci, M

    2011-01-01

    A number of extensions of the Standard Model result in neutral and weakly-coupled particles that decay to multi hadrons or multi leptons with macroscopic decay lengths. These particles with decay paths that can be comparable with ATLAS detector dimensions represent, from an experimental point of view, a challenge both for the trigger and for the reconstruction capabilities of the ATLAS detector. We will present a set of signature driven triggers for the ATLAS detector that target such displaced decays and evaluate their performances for some benchmark models and describe analysis strategies and limits on the production of such long-lived particles. A first estimation of the Hidden Valley trigger rates has been evaluated with 6 pb-1 of data collected at ATLAS during the data taking of 2010.

  6. High pressure Raman spectroscopy of single-walled carbon nanotubes: Effect of chemical environment on individual nanotubes and the nanotube bundle

    Science.gov (United States)

    Proctor, John E.; Halsall, Matthew P.; Ghandour, Ahmad; Dunstan, David J.

    2006-12-01

    The pressure-induced tangential mode Raman peak shifts for single-walled carbon nanotubes (SWNTs) have been studied using a variety of different solvents as hydrostatic pressure-transmitting media. The variation in the nanotube response to hydrostatic pressure with different pressure transmitting media is evidence that the common solvents used are able to penetrate the interstitial spaces in the nanotube bundle. With hexane, we find the surprising result that the individual nanotubes appear unaffected by hydrostatic pressures (i.e. a flat Raman response) up to 0.7 GPa. Qualitatively similar results have been obtained with butanol. Following the approach of Amer et al. [J. Chem. Phys. 121 (2004) 2752], we speculate that this is due to the inability of SWNTs to adsorb some solvents onto their surface at lower pressures. We also find that the role of cohesive energy density in the solvent nanotube interaction is more complex than previously thought.

  7. Purification of carbon nanotubes via selective heating

    Science.gov (United States)

    Rogers, John A.; Wilson, William L.; Jin, Sung Hun; Dunham, Simon N.; Xie, Xu; Islam, Ahmad; Du, Frank; Huang, Yonggang; Song, Jizhou

    2017-11-21

    The present invention provides methods for purifying a layer of carbon nanotubes comprising providing a precursor layer of substantially aligned carbon nanotubes supported by a substrate, wherein the precursor layer comprises a mixture of first carbon nanotubes and second carbon nanotubes; selectively heating the first carbon nanotubes; and separating the first carbon nanotubes from the second carbon nanotubes, thereby generating a purified layer of carbon nanotubes. Devices benefiting from enhanced electrical properties enabled by the purified layer of carbon nanotubes are also described.

  8. A survey of hidden-variables theories

    CERN Document Server

    Belinfante, F J

    1973-01-01

    A Survey of Hidden-Variables Theories is a three-part book on the hidden-variable theories, referred in this book as """"theories of the first kind"""". Part I reviews the motives in developing different types of hidden-variables theories. The quest for determinism led to theories of the first kind; the quest for theories that look like causal theories when applied to spatially separated systems that interacted in the past led to theories of the second kind. Parts II and III further describe the theories of the first kind and second kind, respectively. This book is written to make the literat

  9. A classification of hidden-variable properties

    International Nuclear Information System (INIS)

    Brandenburger, Adam; Yanofsky, Noson

    2008-01-01

    Hidden variables are extra components added to try to banish counterintuitive features of quantum mechanics. We start with a quantum-mechanical model and describe various properties that can be asked of a hidden-variable model. We present six such properties and a Venn diagram of how they are related. With two existence theorems and three no-go theorems (EPR, Bell and Kochen-Specker), we show which properties of empirically equivalent hidden-variable models are possible and which are not. Formally, our treatment relies only on classical probability models, and physical phenomena are used only to motivate which models to choose

  10. Flow-Regulated Growth of Titanium Dioxide (TiO2 ) Nanotubes in Microfluidics.

    Science.gov (United States)

    Fan, Rong; Chen, Xinye; Wang, Zihao; Custer, David; Wan, Jiandi

    2017-08-01

    Electrochemical anodization of titanium (Ti) in a static, bulk condition is used widely to fabricate self-organized TiO 2 nanotube arrays. Such bulk approaches, however, require extended anodization times to obtain long TiO 2 nanotubes and produce only vertically aligned nanotubes. To date, it remains challenging to develop effective strategies to grow long TiO 2 nanotubes in a short period of time, and to control the nanotube orientation. Here, it is shown that the anodic growth of TiO 2 nanotubes is significantly enhanced (≈16-20 times faster) under flow conditions in microfluidics. Flow not only controls the diameter, length, and crystal orientations of TiO 2 nanotubes, but also regulates the spatial distribution of nanotubes inside microfluidic devices. Strikingly, when a Ti thin film is deposited on silicon substrates and anodized in microfluidics, both vertically and horizontally aligned (relative to the bottom substrate) TiO 2 nanotubes can be produced. The results demonstrate previously unidentified roles of flow in the regulation of growth of TiO 2 nanotubes, and provide powerful approaches to effectively grow long, oriented TiO 2 nanotubes, and construct hierarchical TiO 2 nanotube arrays on silicon-based materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Nickel induced re-structuring of 2D graphene to 1D graphene nanotubes: Role of radical hydrogen in catalyst assisted growth

    Science.gov (United States)

    Krishna, Rahul; Titus, Elby

    2017-12-01

    Here, we demonstrate for the first time the structural evolution of 1D graphene nanotubes (GNTs) by the cutting of two dimensional (2D) graphene oxide (GO) sheet in reducing environment at ambient conditions in presence of Ni metal in acidic environment. We observed that in-situ generated radical hydrogen (Hrad) responsible for cutting of graphene sheets and re-structuring of 2D sheet structure to one 1D nanotubes. Structural evolution of GNTs was confirmed by using of transmission electron microscopy (TEM) technique. The current vs. voltage (I-V) characteristics of GNTs displayed room temperature (RT) negative differential resistance (NDR) effect which is typical in nanowires, suggested the applicability of nanomaterial for various kind of electronics applications such as memory devices and transistors fabrication.

  12. Academic mobbing: hidden health hazard at workplace.

    Science.gov (United States)

    Khoo, Sb

    2010-01-01

    Academic mobbing is a non-violent, sophisticated, 'ganging up' behaviour adopted by academicians to "wear and tear" a colleague down emotionally through unjustified accusation, humiliation, general harassment and emotional abuse. These are directed at the target under a veil of lies and justifications so that they are "hidden" to others and difficult to prove. Bullies use mobbing activities to hide their own weaknesses and incompetence. Targets selected are often intelligent, innovative high achievers, with good integrity and principles. Mobbing activities appear trivial and innocuous on its own but the frequency and pattern of their occurrence over long period of time indicates an aggressive manipulation to "eliminate" the target. Mobbing activities typically progress through five stereotypical phases that begins with an unsolved minor conflict between two workers and ultimately escalates into a senseless mobbing whereby the target is stigmatized and victimized to justify the behaviours of the bullies. The result is always physical, mental, social distress or illness and, most often, expulsion of target from the workplace. Organizations are subjected to great financial loss, loss of key workers and a tarnished public image and reputation. Public awareness, education, effective counselling, establishment of anti-bullying policies and legislations at all levels are necessary to curb academic mobbing. General practitioners (GPs) play an important role in supporting patients subjected to mental and physical health injury caused by workplace bullying and mobbing.

  13. Recent development of carbon nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Yamabe, Tokio [Div. of Molecular Engineering, Kyoto Univ. (Japan); [Inst. for Fundamental Chemistry, Kyoto (Japan)

    1995-03-15

    Recent developments of carbon nanotubes are reviewed. Analytical solutions for the electronic structure of carbon nanotube on the basis of thight-binding approximation are presented and interpreted using the concepts of crystal orbital. The electronic properties of actual carbon nanotubes are presented. The electronic structures of carbon nanotubes in the presence of magnetic fiels are also summerized. (orig.)

  14. UV Photography Shows Hidden Sun Damage

    Science.gov (United States)

    ... mcat1=de12", ]; for (var c = 0; c UV photography shows hidden sun damage A UV photograph gives ... developing skin cancer and prematurely aged skin. Normal photography UV photography 18 months of age: This boy's ...

  15. Coding with partially hidden Markov models

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Rissanen, J.

    1995-01-01

    Partially hidden Markov models (PHMM) are introduced. They are a variation of the hidden Markov models (HMM) combining the power of explicit conditioning on past observations and the power of using hidden states. (P)HMM may be combined with arithmetic coding for lossless data compression. A general...... 2-part coding scheme for given model order but unknown parameters based on PHMM is presented. A forward-backward reestimation of parameters with a redefined backward variable is given for these models and used for estimating the unknown parameters. Proof of convergence of this reestimation is given....... The PHMM structure and the conditions of the convergence proof allows for application of the PHMM to image coding. Relations between the PHMM and hidden Markov models (HMM) are treated. Results of coding bi-level images with the PHMM coding scheme is given. The results indicate that the PHMM can adapt...

  16. Hidden costs, value lost: uninsurance in America

    National Research Council Canada - National Science Library

    Committee on the Consequences of Uninsurance

    2003-01-01

    Hidden Cost, Value Lost , the fifth of a series of six books on the consequences of uninsurance in the United States, illustrates some of the economic and social losses to the country of maintaining...

  17. The hidden epidemic: confronting sexually transmitted diseases

    National Research Council Canada - National Science Library

    Eng, Thomas R; Butler, William T

    .... In addition, STDs increase the risk of HIV transmission. The Hidden Epidemic examines the scope of sexually transmitted infections in the United States and provides a critical assessment of the nation's response to this public health crisis...

  18. Perspective: Disclosing hidden sources of funding.

    Science.gov (United States)

    Resnik, David B

    2009-09-01

    In this article, the author discusses ethical and policy issues related to the disclosure of hidden sources of funding in research. The author argues that authors have an ethical obligation to disclose hidden sources of funding and that journals should adopt policies to enforce this obligation. Journal policies should require disclosure of hidden sources of funding that authors know about and that have a direct relation to their research. To stimulate this discussion, the author describes a recent case: investigators who conducted a lung cancer screening study had received funding from a private foundation that was supported by a tobacco company, but they did not disclose this relationship to the journal. Investigators and journal editors must be prepared to deal with these issues in a manner that promotes honesty, transparency, fairness, and accountability in research. The development of well-defined, reasonable policies pertaining to hidden sources of funding can be a step in this direction.

  19. Petro Rents, Political Institutions, and Hidden Wealth

    DEFF Research Database (Denmark)

    Andersen, Jørgen Juel; Johannesen, Niels; Lassen, David Dreyer

    2017-01-01

    Do political institutions limit rent seeking by politicians? We study the transformation of petroleum rents, almost universally under direct government control, into hidden wealth using unique data on bank deposits in offshore financial centers that specialize in secrecy and asset protection. Our...... rulers is diverted to secret accounts. We find very limited evidence that shocks to other types of income not directly controlled by governments affect hidden wealth....

  20. Hidden charm molecules in a finite volume

    International Nuclear Information System (INIS)

    Albaladejo, M.; Hidalgo-Duque, C.; Nieves, J.; Oset, E.

    2014-01-01

    In the present paper we address the interaction of charmed mesons in hidden charm channels in a finite box. We use the interaction from a recent model based on heavy quark spin symmetry that predicts molecules of hidden charm in the infinite volume. The energy levels in the box are generated within this model, and several methods for the analysis of these levels ("inverse problem") are investigated. (author)

  1. Workplace ageism: discovering hidden bias.

    Science.gov (United States)

    Malinen, Sanna; Johnston, Lucy

    2013-01-01

    BACKGROUND/STUDY CONTEXT: Research largely shows no performance differences between older and younger employees, or that older workers even outperform younger employees, yet negative attitudes towards older workers can underpin discrimination. Unfortunately, traditional "explicit" techniques for assessing attitudes (i.e., self-report measures) have serious drawbacks. Therefore, using an approach that is novel to organizational contexts, the authors supplemented explicit with implicit (indirect) measures of attitudes towards older workers, and examined the malleability of both. This research consists of two studies. The authors measured self-report (explicit) attitudes towards older and younger workers with a survey, and implicit attitudes with a reaction-time-based measure of implicit associations. In addition, to test whether attitudes were malleable, the authors measured attitudes before and after a mental imagery intervention, where the authors asked participants in the experimental group to imagine respected and valued older workers from their surroundings. Negative, stable implicit attitudes towards older workers emerged in two studies. Conversely, explicit attitudes showed no age bias and were more susceptible to change intervention, such that attitudes became more positive towards older workers following the experimental manipulation. This research demonstrates the unconscious nature of bias against older workers, and highlights the utility of implicit attitude measures in the context of the workplace. In the current era of aging workforce and skill shortages, implicit measures may be necessary to illuminate hidden workplace ageism.

  2. Hidden slow pulsars in binaries

    Science.gov (United States)

    Tavani, Marco; Brookshaw, Leigh

    1993-01-01

    The recent discovery of the binary containing the slow pulsar PSR 1718-19 orbiting around a low-mass companion star adds new light on the characteristics of binary pulsars. The properties of the radio eclipses of PSR 1718-19 are the most striking observational characteristics of this system. The surface of the companion star produces a mass outflow which leaves only a small 'window' in orbital phase for the detection of PSR 1718-19 around 400 MHz. At this observing frequency, PSR 1718-19 is clearly observable only for about 1 hr out of the total 6.2 hr orbital period. The aim of this Letter is twofold: (1) to model the hydrodynamical behavior of the eclipsing material from the companion star of PSR 1718-19 and (2) to argue that a population of binary slow pulsars might have escaped detection in pulsar surveys carried out at 400 MHz. The possible existence of a population of partially or totally hidden slow pulsars in binaries will have a strong impact on current theories of binary evolution of neutron stars.

  3. Life imitating art: depictions of the hidden curriculum in medical television programs.

    Science.gov (United States)

    Stanek, Agatha; Clarkin, Chantalle; Bould, M Dylan; Writer, Hilary; Doja, Asif

    2015-09-26

    The hidden curriculum represents influences occurring within the culture of medicine that indirectly alter medical professionals' interactions, beliefs and clinical practices throughout their training. One approach to increase medical student awareness of the hidden curriculum is to provide them with readily available examples of how it is enacted in medicine; as such the purpose of this study was to examine depictions of the hidden curriculum in popular medical television programs. One full season of ER, Grey's Anatomy and Scrubs were selected for review. A summative content analysis was performed to ascertain the presence of depictions of the hidden curriculum, as well as to record the type, frequency and quality of examples. A second reviewer also viewed a random selection of episodes from each series to establish coding reliability. The most prevalent themes across all television programs were: the hierarchical nature of medicine; challenges during transitional stages in medicine; the importance of role modeling; patient dehumanization; faking or overstating one's capabilities; unprofessionalism; the loss of idealism; and difficulties with work-life balance. The hidden curriculum is frequently depicted in popular medical television shows. These examples of the hidden curriculum could serve as a valuable teaching resource in undergraduate medical programs.

  4. Phonon spectra, electronic, and thermodynamic properties of WS2 nanotubes.

    Science.gov (United States)

    Evarestov, Robert A; Bandura, Andrei V; Porsev, Vitaly V; Kovalenko, Alexey V

    2017-11-15

    Hybrid density functional theory calculations are performed for the first time on the phonon dispersion and thermodynamic properties of WS 2 -based single-wall nanotubes. Symmetry analysis is presented for phonon modes in nanotubes using the standard (crystallographic) factorization for line groups. Symmetry and the number of infra-red and Raman active modes in achiral WS 2 nanotubes are given for armchair and zigzag chiralities. It is demonstrated that a number of infrared and Raman active modes is independent on the nanotube diameter. The zone-folding approach is applied to find out an impact of curvature on electron and phonon band structure of nanotubes rolled up from the monolayer. Phonon frequencies obtained both for layers and nanotubes are used to compute the thermal contributions to their thermodynamic functions. The temperature dependences of energy, entropy, and heat capacity of nanotubes are estimated with respect to those of the monolayer. The role of phonons in the stability estimation of nanotubes is discussed based on Helmholtz free energy calculations. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  5. Surfactant-nanotube interactions in water and nanotube separation by diameter: atomistic simulations

    Science.gov (United States)

    Carvalho, E. J. F.; Dos Santos, M. C.

    2010-05-01

    A non-destructive sorting method to separate single-walled carbon nanotubes (SWNTs) by diameter was recently proposed. By this method, SWNTs are suspended in water by surfactant encapsulation and the separation is carried out by ultracentrifugation in a density gradient. SWNTs of different diameters are distributed according to their densities along the centrifuge tube. A mixture of two anionic surfactants, namely sodium dodecylsulfate (SDS) and sodium cholate (SC), presented the best performance in discriminating nanotubes by diameter. Unexpectedly, small diameter nanotubes are found at the low density part of the centrifuge tube. We present molecular dynamics studies of the water-surfactant-SWNT system to investigate the role of surfactants in the sorting process. We found that surfactants can actually be attracted towards the interior of the nanotube cage, depending on the relationship between the surfactant radius of gyration and the nanotube diameter. The dynamics at room temperature showed that, as the amphiphile moves to the hollow cage, water molecules are dragged together, thereby promoting the nanotube filling. The resulting densities of filled SWNT are in agreement with measured densities.

  6. A comparative study for Hydrogen storage in metal decorated graphyne nanotubes and graphyne monolayers

    International Nuclear Information System (INIS)

    Lu, Jinlian; Guo, Yanhua; Zhang, Yun; Tang, Yingru; Cao, Juexian

    2015-01-01

    A comparative study for hydrogen storage in metal decorated graphyne nanotubes and graphyne monolayers has been investigated within the framework of first-principle calculations. Our results show that the binding energies of Li, Ca, Sc, Ti on graphyne nanotubes are stronger than that on graphyne monolayers. Such strong binding would prevent the formation of metal clusters on graphyne nanotubes. From the charge transfer and partial density of states, it is found that the curvature effect of nanotubes plays an important role for the strong binding strength of metal on graphyne nanotubes. And the hydrogen storage capacity is 4.82 wt%, 5.08 wt%, 4.88 wt%, 4.76 wt% for Li, Ca, Sc, Ti decorated graphyne nanotubes that promise a potential material for storing hydrogen. - Graphical abstract: Metal atoms (Li, Ca, Sc and Ti) can strongly bind to graphyne nanotubes to avoid the formation of metal clusters, and a capacity of Ca@graphyne nanotube is 5.08 wt% which is close to the requirement of DOE in 2015. Twenty-four hydrogen molecules absorb to Ti-decorated graphyne nanotube. - Highlights: • The binding strength for metal on graphyne nanotubes is much stronger than that on γ-graphyne monolayer. • Metal atoms can strongly bind to the curving triangle acetylenes rings to avoid the formation of metal clusters. • A capacity of Ca@graphyne nanotube is 5.08 wt% which is close to the requirement of DOE in 2015.

  7. Nanowires and nanotubes of BN, GaN and Si3N4

    International Nuclear Information System (INIS)

    Deepak, F.L.; Gundiah, G.; Govindaraj, A.; Rao, C.N.

    2002-01-01

    Simple methods of synthesizing nanotubes and nanowires of boron nitride, gallium nitride and silicon nitride have been investigated. The nanotubes and nanowires have been examined by electron microscopy and other techniques. In the case of BN, activated carbon or multi-walled carbon nanotubes (MWNTs) was heated with boric acid in the presence of NH 3 . With activated carbon, BN nanowires constitute the primary products, but good yields of BN nanotubes are obtained with MWNTs. Aligned BN nanotubes are obtained when aligned MWNTs are employed as the starting material suggesting templating role of carbon nanotubes. Single crystal gallium nitride nanowires have been obtained by heating carbon nanotubes coated with gallium acetylacetonate in NH 3 vapor at 910 o C. Single walled carbon nanotubes were used as templated to reduce the diameter of the GaN nanowires. The growth direction of the GaN nanowires is nearly perpendicular to the [100] planes and the nanowires exhibit satisfactory photoluminescence spectra. Si 3 N 4 nanowires have been synthesized by heating multi-walled carbon nanotubes with silica gel at 1360 o C in an atmosphere of NH 3 . Si 3 N 4 nanotubes are found occasionally when aligned multi-walled nanotubes are employed as templates. (author)

  8. Probing hidden sector photons through the Higgs window

    International Nuclear Information System (INIS)

    Ahlers, M.

    2008-07-01

    We investigate the possibility that a (light) hidden sector extra photon receives its mass via spontaneous symmetry breaking of a hidden sector Higgs boson, the so-called hidden-Higgs. The hidden-photon can mix with the ordinary photon via a gauge kinetic mixing term. The hidden-Higgs can couple to the Standard Model Higgs via a renormalizable quartic term - sometimes called the Higgs Portal. We discuss the implications of this light hidden-Higgs in the context of laser polarization and light-shining-through-the-wall experiments as well as cosmological, astrophysical, and non-Newtonian force measurements. For hidden-photons receiving their mass from a hidden-Higgs we find in the small mass regime significantly stronger bounds than the bounds on massive hidden sector photons alone. (orig.)

  9. Probing hidden sector photons through the Higgs window

    International Nuclear Information System (INIS)

    Ahlers, Markus; Jaeckel, Joerg; Redondo, Javier; Ringwald, Andreas

    2008-01-01

    We investigate the possibility that a (light) hidden sector extra photon receives its mass via spontaneous symmetry breaking of a hidden sector Higgs boson, the so-called hidden-Higgs. The hidden-photon can mix with the ordinary photon via a gauge kinetic mixing term. The hidden-Higgs can couple to the standard model Higgs via a renormalizable quartic term - sometimes called the Higgs portal. We discuss the implications of this light hidden-Higgs in the context of laser polarization and light-shining-through-the-wall experiments as well as cosmological, astrophysical, and non-Newtonian force measurements. For hidden-photons receiving their mass from a hidden-Higgs, we find in the small mass regime significantly stronger bounds than the bounds on massive hidden sector photons alone.

  10. Nanotube resonator devices

    Science.gov (United States)

    Jensen, Kenneth J; Zettl, Alexander K; Weldon, Jeffrey A

    2014-05-06

    A fully-functional radio receiver fabricated from a single nanotube is being disclosed. Simultaneously, a single nanotube can perform the functions of all major components of a radio: antenna, tunable band-pass filter, amplifier, and demodulator. A DC voltage source, as supplied by a battery, can power the radio. Using carrier waves in the commercially relevant 40-400 MHz range and both frequency and amplitude modulation techniques, successful music and voice reception has been demonstrated. Also disclosed are a radio transmitter and a mass sensor using a nanotube resonator device.

  11. Fitting Hidden Markov Models to Psychological Data

    Directory of Open Access Journals (Sweden)

    Ingmar Visser

    2002-01-01

    Full Text Available Markov models have been used extensively in psychology of learning. Applications of hidden Markov models are rare however. This is partially due to the fact that comprehensive statistics for model selection and model assessment are lacking in the psychological literature. We present model selection and model assessment statistics that are particularly useful in applying hidden Markov models in psychology. These statistics are presented and evaluated by simulation studies for a toy example. We compare AIC, BIC and related criteria and introduce a prediction error measure for assessing goodness-of-fit. In a simulation study, two methods of fitting equality constraints are compared. In two illustrative examples with experimental data we apply selection criteria, fit models with constraints and assess goodness-of-fit. First, data from a concept identification task is analyzed. Hidden Markov models provide a flexible approach to analyzing such data when compared to other modeling methods. Second, a novel application of hidden Markov models in implicit learning is presented. Hidden Markov models are used in this context to quantify knowledge that subjects express in an implicit learning task. This method of analyzing implicit learning data provides a comprehensive approach for addressing important theoretical issues in the field.

  12. Geometric phases and hidden local gauge symmetry

    International Nuclear Information System (INIS)

    Fujikawa, Kazuo

    2005-01-01

    The analysis of geometric phases associated with level crossing is reduced to the familiar diagonalization of the Hamiltonian in the second quantized formulation. A hidden local gauge symmetry, which is associated with the arbitrariness of the phase choice of a complete orthonormal basis set, becomes explicit in this formulation (in particular, in the adiabatic approximation) and specifies physical observables. The choice of a basis set which specifies the coordinate in the functional space is arbitrary in the second quantization, and a subclass of coordinate transformations, which keeps the form of the action invariant, is recognized as the gauge symmetry. We discuss the implications of this hidden local gauge symmetry in detail by analyzing geometric phases for cyclic and noncyclic evolutions. It is shown that the hidden local symmetry provides a basic concept alternative to the notion of holonomy to analyze geometric phases and that the analysis based on the hidden local gauge symmetry leads to results consistent with the general prescription of Pancharatnam. We however note an important difference between the geometric phases for cyclic and noncyclic evolutions. We also explain a basic difference between our hidden local gauge symmetry and a gauge symmetry (or equivalence class) used by Aharonov and Anandan in their definition of generalized geometric phases

  13. The role of healed N-vacancy defective BC2N sheet and nanotube by NO molecule in oxidation of NO and CO gas molecules

    Science.gov (United States)

    Nematollahi, Parisa; Esrafili, Mehdi D.; Neyts, Erik C.

    2018-06-01

    In this study, the healing of N-vacancy boron carbonitride nanosheet (NV-BC2NNS) and nanotube (NV-BC2NNT) by NO molecule is studied by means of density functional theory calculations. Two different N-vacancies are considered in each of these structures in which the vacancy site is surrounded by either three B-atoms (NB) or by two B- and one C-atom (NBC). By means of the healed BC2NNS and BC2NNT as a support, the removal of two toxic gas molecules (NO and CO) are applicable. It should be noted that the obtained energy barriers of both healing and oxidizing processes are significantly lower than those of graphene, carbon nanotubes or boron nitride nanostructures. Also, at the end of the oxidation process, the pure BC2NNS or BC2NNT is obtained without any additional defects. Therefore, by using this method, we can considerably purify the defective BC2NNS/BC2NNT. Moreover, according to the thermochemistry calculations we can further confirm that the healing process of the NV-BC2NNS and NV-BC2NNT by NO are feasible at room temperature. So, we can claim that this study could be very helpful in both purifying the defective BC2NNS/BC2NNT while in the same effort removing toxic NO and CO gases.

  14. Massive hidden photons as lukewarm dark matter

    International Nuclear Information System (INIS)

    Redondo, Javier; Postma, Marieke

    2008-11-01

    We study the possibility that a keV-MeV mass hidden photon (HP), i.e. a hidden sector U(1) gauge boson, accounts for the observed amount of dark matter. We focus on the case where the HP interacts with the standard model sector only through kinetic mixing with the photon. The relic abundance is computed including all relevant plasma effects into the photon's self-energy, which leads to a resonant yield almost independent of the HP mass. The HP can decay into three photons. Moreover, if light enough it can be copiously produced in stars. Including bounds from cosmic photon backgrounds and stellar evolution, we find that the hidden photon can only give a subdominant contribution to the dark matter. This negative conclusion may be avoided if another production mechanism besides kinetic mixing is operative. (orig.)

  15. Massive hidden photons as lukewarm dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Javier [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Postma, Marieke [Nationaal Inst. voor Kernfysica en Hoge-Energiefysica (NIKHEF), Amsterdam (Netherlands)

    2008-11-15

    We study the possibility that a keV-MeV mass hidden photon (HP), i.e. a hidden sector U(1) gauge boson, accounts for the observed amount of dark matter. We focus on the case where the HP interacts with the standard model sector only through kinetic mixing with the photon. The relic abundance is computed including all relevant plasma effects into the photon's self-energy, which leads to a resonant yield almost independent of the HP mass. The HP can decay into three photons. Moreover, if light enough it can be copiously produced in stars. Including bounds from cosmic photon backgrounds and stellar evolution, we find that the hidden photon can only give a subdominant contribution to the dark matter. This negative conclusion may be avoided if another production mechanism besides kinetic mixing is operative. (orig.)

  16. Religious Tolerance in the Hidden Curriculum

    Directory of Open Access Journals (Sweden)

    Kevin Nobel Kurniawan

    2018-03-01

    Full Text Available Religious intolerance is spreading within the Indonesian institution of education. Previous studies have shown that the growth of intolerance is due to the state’s regulation and pedagogical apparatus. In contrast to the previous studies, I argue that the intolerance is related to hidden curriculum applied by the institution of education.  Normatively, the hidden curriculum contains the value of religious tolerance. However, factually, the author found that there are practices of intolerance, through the formal and informal spheres in the school’s structure, within the hidden curriculum. This article applies a qualitative approach with a mixed method research strategy to analyze data collected from students, teachers, and alumnis through field observation, in-depth interview, and survey.

  17. Hidden treasures - 50 km points of interests

    Science.gov (United States)

    Lommi, Matias; Kortelainen, Jaana

    2015-04-01

    Tampere is third largest city in Finland and a regional centre. During 70's there occurred several communal mergers. Nowadays this local area has both strong and diversed identity - from wilderness and agricultural fields to high density city living. Outside the city center there are interesting geological points unknown for modern city settlers. There is even a local proverb, "Go abroad to Teisko!". That is the area the Hidden Treasures -student project is focused on. Our school Tammerkoski Upper Secondary School (or Gymnasium) has emphasis on visual arts. We are going to offer our art students scientific and artistic experiences and knowledge about the hidden treasures of Teisko area and involve the Teisko inhabitants into this project. Hidden treasures - Precambrian subduction zone and a volcanism belt with dense bed of gold (Au) and arsenic (As), operating goldmines and quarries of minerals and metamorphic slates. - North of subduction zone a homogenic precambrian magmastone area with quarries, products known as Kuru Grey. - Former ashores of post-glasial Lake Näsijärvi and it's sediments enabled the developing agriculture and sustained settlement. Nowadays these ashores have both scenery and biodiversity values. - Old cattle sheds and dairy buildings made of local granite stones related to cultural stonebuilding inheritance. - Local active community of Kapee, about 100 inhabitants. Students will discover information of these "hidden" phenomena, and rendering this information trough Enviromental Art Method. Final form of this project will be published in several artistic and informative geocaches. These caches are achieved by a GPS-based special Hidden Treasures Cycling Route and by a website guiding people to find these hidden points of interests.

  18. The origin of the hidden supersymmetry

    International Nuclear Information System (INIS)

    Jakubsky, Vit; Nieto, Luis-Miguel; Plyushchay, Mikhail S.

    2010-01-01

    The hidden supersymmetry and related tri-supersymmetric structure of the free particle system, the Dirac delta potential problem and the Aharonov-Bohm effect (planar, bound state, and tubule models) are explained by a special nonlocal unitary transformation, which for the usual N=2 supercharges has a nature of Foldy-Wouthuysen transformation. We show that in general case, the bosonized supersymmetry of nonlocal, parity even systems emerges in the same construction, and explain the origin of the unusual N=2 supersymmetry of electron in three-dimensional parity even magnetic field. The observation extends to include the hidden superconformal symmetry.

  19. Signatures of a hidden cosmic microwave background.

    Science.gov (United States)

    Jaeckel, Joerg; Redondo, Javier; Ringwald, Andreas

    2008-09-26

    If there is a light Abelian gauge boson gamma' in the hidden sector its kinetic mixing with the photon can produce a hidden cosmic microwave background (HCMB). For meV masses, resonant oscillations gammagamma' happen after big bang nucleosynthesis (BBN) but before CMB decoupling, increasing the effective number of neutrinos Nnu(eff) and the baryon to photon ratio, and distorting the CMB blackbody spectrum. The agreement between BBN and CMB data provides new constraints. However, including Lyman-alpha data, Nnu(eff) > 3 is preferred. It is tempting to attribute this effect to the HCMB. The interesting parameter range will be tested in upcoming laboratory experiments.

  20. Hidden simplicity of gauge theory amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, J M, E-mail: drummond@lapp.in2p3.f [LAPTH, Universite de Savoie, CNRS, B.P. 110, F-74941 Annecy-le-Vieux, Cedex (France)

    2010-11-07

    These notes were given as lectures at the CERN Winter School on Supergravity, Strings and Gauge Theory 2010. We describe the structure of scattering amplitudes in gauge theories, focussing on the maximally supersymmetric theory to highlight the hidden symmetries which appear. Using the Britto, Cachzo, Feng and Witten (BCFW) recursion relations we solve the tree-level S-matrix in N=4 super Yang-Mills theory and describe how it produces a sum of invariants of a large symmetry algebra. We review amplitudes in the planar theory beyond tree level, describing the connection between amplitudes and Wilson loops, and discuss the implications of the hidden symmetries.

  1. Transparent conducting oxide nanotubes

    Science.gov (United States)

    Alivov, Yahya; Singh, Vivek; Ding, Yuchen; Nagpal, Prashant

    2014-09-01

    Thin film or porous membranes made of hollow, transparent, conducting oxide (TCO) nanotubes, with high chemical stability, functionalized surfaces and large surface areas, can provide an excellent platform for a wide variety of nanostructured photovoltaic, photodetector, photoelectrochemical and photocatalytic devices. While large-bandgap oxide semiconductors offer transparency for incident light (below their nominal bandgap), their low carrier concentration and poor conductivity makes them unsuitable for charge conduction. Moreover, materials with high conductivity have nominally low bandgaps and hence poor light transmittance. Here, we demonstrate thin films and membranes made from TiO2 nanotubes heavily-doped with shallow Niobium (Nb) donors (up to 10%, without phase segregation), using a modified electrochemical anodization process, to fabricate transparent conducting hollow nanotubes. Temperature dependent current-voltage characteristics revealed that TiO2 TCO nanotubes, doped with 10% Nb, show metal-like behavior with resistivity decreasing from 6.5 × 10-4 Ωcm at T = 300 K (compared to 6.5 × 10-1 Ωcm for nominally undoped nanotubes) to 2.2 × 10-4 Ωcm at T = 20 K. Optical properties, studied by reflectance measurements, showed light transmittance up to 90%, within wavelength range 400 nm-1000 nm. Nb doping also improves the field emission properties of TCO nanotubes demonstrating an order of magnitude increase in field-emitter current, compared to undoped samples.

  2. Conducting carbonized polyaniline nanotubes

    International Nuclear Information System (INIS)

    Mentus, Slavko; Ciric-Marjanovic, Gordana; Trchova, Miroslava; Stejskal, Jaroslav

    2009-01-01

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 deg. C min -1 up to a maximum temperature of 800 deg. C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 μm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 μm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm -1 , increased to 0.7 S cm -1 upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  3. Conducting carbonized polyaniline nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mentus, Slavko; Ciric-Marjanovic, Gordana [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade (Serbia); Trchova, Miroslava; Stejskal, Jaroslav [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Square 2, 162 06 Prague 6 (Czech Republic)], E-mail: gordana@ffh.bg.ac.rs

    2009-06-17

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 deg. C min{sup -1} up to a maximum temperature of 800 deg. C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 {mu}m, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 {mu}m, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm{sup -1}, increased to 0.7 S cm{sup -1} upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  4. Carbon nanotube filters

    Science.gov (United States)

    Srivastava, A.; Srivastava, O. N.; Talapatra, S.; Vajtai, R.; Ajayan, P. M.

    2004-09-01

    Over the past decade of nanotube research, a variety of organized nanotube architectures have been fabricated using chemical vapour deposition. The idea of using nanotube structures in separation technology has been proposed, but building macroscopic structures that have controlled geometric shapes, density and dimensions for specific applications still remains a challenge. Here we report the fabrication of freestanding monolithic uniform macroscopic hollow cylinders having radially aligned carbon nanotube walls, with diameters and lengths up to several centimetres. These cylindrical membranes are used as filters to demonstrate their utility in two important settings: the elimination of multiple components of heavy hydrocarbons from petroleum-a crucial step in post-distillation of crude oil-with a single-step filtering process, and the filtration of bacterial contaminants such as Escherichia coli or the nanometre-sized poliovirus (~25 nm) from water. These macro filters can be cleaned for repeated filtration through ultrasonication and autoclaving. The exceptional thermal and mechanical stability of nanotubes, and the high surface area, ease and cost-effective fabrication of the nanotube membranes may allow them to compete with ceramic- and polymer-based separation membranes used commercially.

  5. First-principles modeling of hafnia-based nanotubes.

    Science.gov (United States)

    Evarestov, Robert A; Bandura, Andrei V; Porsev, Vitaly V; Kovalenko, Alexey V

    2017-09-15

    Hybrid density functional theory calculations were performed for the first time on structure, stability, phonon frequencies, and thermodynamic functions of hafnia-based single-wall nanotubes. The nanotubes were rolled up from the thin free layers of cubic and tetragonal phases of HfO 2 . It was shown that the most stable HfO 2 single-wall nanotubes can be obtained from hexagonal (111) layer of the cubic phase. Phonon frequencies have been calculated for different HfO 2 nanolayers and nanotubes to prove the local stability and to find the thermal contributions to their thermodynamic functions. The role of phonons in stability of nanotubes seems to be negligible for the internal energy and noticeable for the Helmholtz free energy. Zone folding approach has been applied to estimate the connection between phonon modes of the layer and nanotubes and to approximate the nanotube thermodynamic properties. It is found that the zone-folding approximation is sufficiently accurate for heat capacity, but less accurate for entropy. The comparison has been done between the properties of TiO 2 , ZrO 2 , and HfO 2 . © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  6. The role of carbon solubility in Fe-C nano-clusters on the growth of small single-walled carbon nanotubes

    Science.gov (United States)

    Curtarolo, Stefano; Awasthy, Neha; Setyawan, Wahyu; Mora, Elena; Tokune, Toshio; Bolton, Kim; Harutyunyan, Avetik

    2008-03-01

    Various diameters of alumina-supported Fe catalysts are used to grow single-walled carbon nanotubes (SWCNTs) with chemical vapor decomposition. We find that the reduction of the catalyst size requires an increase of the minimum temperature necessary for the growth. We address this phenomenon in terms of solubility of C in Fe nanoclusters and, by using first principles calculations, we devise a simple model to predict the behavior of the phases competing for stability in Fe-C nanoclusters at low temperature. We show that, as a function particles size, there are three scenarios compatible with steady state-, limited- and no-growth of SWCNTs, corresponding to unaffected, reduced and no solubility of C in the particles. The result raises previously unknown concerns about the growth feasibility of small and very-long SWCNTs within the current Fe CVD technology, and suggests new strategies in the search of better catalysts. Research supported by Honda R.I. and NSF.

  7. Searching for hidden sectors in multiparticle production at the LHC

    CERN Document Server

    Sanchis-Lozano, Miguel-Angel; Moreno-Picot, Salvador

    2016-01-01

    We study the impact of a hidden sector beyond the Standard Model, e.g. a Hidden Valley model, on factorial moments and cumulants of multiplicity distributions in multiparticle production with a special emphasis on the prospects for LHC results.

  8. Testing string vacua in the lab. From a hidden CMB to dark forces in flux compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Cicoli, Michele; Goodsell, Mark; Ringwald, Andreas [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany). Theory Group; Jaeckel, Joerg [Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenolgy

    2011-03-15

    We perform a detailed analysis of the phenomenological properties of hidden Abelian gauge bosons with a kinetic mixing with the ordinary photon within type IIB flux compactifications. We study the interplay between moduli stabilisation and the Green-Schwarz mechanism that gives mass to the hidden photon paying particular attention to the role of D-terms. We present two generic classes of explicit Calabi-Yau examples with an isotropic and an anisotropic shape of the extra dimensions showing how the last case turns out to be very promising to make contact with current experiments. In fact, anisotropic compactifications lead naturally to a GeV-scale hidden photon (''dark forces'' that can be searched for in beam dump experiments) for an intermediate string scale; or even to an meV-scale hidden photon (which could lead to a ''hidden CMB'' and can be tested by light-shining-through-a-wall experiments) in the case of TeV-scale strings. (orig.)

  9. Compressing the hidden variable space of a qubit

    OpenAIRE

    Montina, Alberto

    2010-01-01

    In previously exhibited hidden variable models of quantum state preparation and measurement, the number of continuous hidden variables describing the actual state of a single realization is never smaller than the quantum state manifold dimension. We introduce a simple model for a qubit whose hidden variable space is one-dimensional, i.e., smaller than the two-dimensional Bloch sphere. The hidden variable probability distributions associated with the quantum states satisfy reasonable criteria ...

  10. … To be hidden does not mean to be merely revealed – Part 2

    Directory of Open Access Journals (Sweden)

    Annette Krause

    2015-12-01

    Full Text Available This text revisits the long-term project Hidden Curriculum (HC, initiated by Annette Krauss, that addresses unquestioned routines, hierarchies of knowledge and the role of the body in learning processes from the perspective of secondary/high school education (in the research on a hidden curriculum. The first part of this text (www.medienimpulse.at/articles/view/848 entailed a deeper analysis of educational studies on the phenomenon of hidden curriculum in relation to the feminist and critical pedagogies of bell hooks, Paulo Freire and Jacques Rancière. The aim of the second part is to address academic canons and corporeality within educational settings and to investigate the physicality of everyday norms through revisiting the framework, results and processes of the collaborative research of the HC project with secondary/high school students.

  11. Hidden Markov Models for Human Genes

    DEFF Research Database (Denmark)

    Baldi, Pierre; Brunak, Søren; Chauvin, Yves

    1997-01-01

    We analyse the sequential structure of human genomic DNA by hidden Markov models. We apply models of widely different design: conventional left-right constructs and models with a built-in periodic architecture. The models are trained on segments of DNA sequences extracted such that they cover com...

  12. The Hidden Cost of Buying a Computer.

    Science.gov (United States)

    Johnson, Michael

    1983-01-01

    In order to process data in a computer, application software must be either developed or purchased. Costs for modifications of the software package and maintenance are often hidden. The decision to buy or develop software packages should be based upon factors of time and maintenance. (MLF)

  13. Discovering hidden sectors with monophoton Z' searches

    International Nuclear Information System (INIS)

    Gershtein, Yuri; Petriello, Frank; Quackenbush, Seth; Zurek, Kathryn M.

    2008-01-01

    In many theories of physics beyond the standard model, from extra dimensions to Hidden Valleys and models of dark matter, Z ' bosons mediate between standard model particles and hidden sector states. We study the feasibility of observing such hidden states through an invisibly decaying Z ' at the LHC. We focus on the process pp→γZ ' →γXX † , where X is any neutral, (quasi-) stable particle, whether a standard model neutrino or a new state. This complements a previous study using pp→ZZ ' →l + l - XX † . Only the Z ' mass and two effective charges are needed to describe this process. If the Z ' decays invisibly only to standard model neutrinos, then these charges are predicted by observation of the Z ' through the Drell-Yan process, allowing discrimination between Z ' decays to standard model ν's and invisible decays to new states. We carefully discuss all backgrounds and systematic errors that affect this search. We find that hidden sector decays of a 1 TeV Z ' can be observed at 5σ significance with 50 fb -1 at the LHC. Observation of a 1.5 TeV state requires super-LHC statistics of 1 ab -1 . Control of the systematic errors, in particular, the parton distribution function uncertainty of the dominant Zγ background, is crucial to maximize the LHC search reach.

  14. Hidden Markov models for labeled sequences

    DEFF Research Database (Denmark)

    Krogh, Anders Stærmose

    1994-01-01

    A hidden Markov model for labeled observations, called a class HMM, is introduced and a maximum likelihood method is developed for estimating the parameters of the model. Instead of training it to model the statistics of the training sequences it is trained to optimize recognition. It resembles MMI...

  15. Carbon nanotube junctions and devices

    NARCIS (Netherlands)

    Postma, H.W.Ch.

    2001-01-01

    In this thesis Postma presents transport experiments performed on individual single-wall carbon nanotubes. Carbon nanotubes are molecules entirely made of carbon atoms. The electronic properties are determined by the exact symmetry of the nanotube lattice, resulting in either metallic or

  16. Nanomechanical cutting of boron nitride nanotubes by atomic force microscopy

    International Nuclear Information System (INIS)

    Zheng, Meng; Chen, Xiaoming; Ke, Changhong; Park, Cheol; Fay, Catharine C; Pugno, Nicola M

    2013-01-01

    The length of nanotubes is a critical structural parameter for the design and manufacture of nanotube-based material systems and devices. High-precision length control of nanotubes by means of mechanical cutting using a scriber has not materialized due to the lack of the knowledge of the appropriate cutting conditions and the tube failure mechanism. In this paper, we present a quantitative nanomechanical study of the cutting of individual boron nitride nanotubes (BNNTs) using atomic force microscopy (AFM) probes. In our nanotube cutting measurements, a nanotube standing still on a flat substrate was laterally scribed by an AFM tip. The tip–tube collision force deformed the tube, and eventually fractured the tube at the collision site by increasing the cutting load. The mechanical response of nanotubes during the tip–tube collision process and the roles of the scribing velocity and the frictional interaction on the tip–tube collision contact in cutting nanotubes were quantitatively investigated by cutting double-walled BNNTs of 2.26–4.28 nm in outer diameter. The fracture strength of BNNTs was also quantified based on the measured collision forces and their structural configurations using contact mechanics theories. Our analysis reports fracture strengths of 9.1–15.5 GPa for the tested BNNTs. The nanomechanical study presented in this paper demonstrates that the AFM-based nanomechanical cutting technique not only enables effective control of the length of nanotubes with high precision, but is also promising as a new nanomechanical testing technique for characterizing the mechanical properties of tubular nanostructures. (paper)

  17. Synthesis of carbon nanotubes and nanotube forests on copper catalyst

    International Nuclear Information System (INIS)

    Kruszka, Bartosz; Terzyk, Artur P; Wiśniewski, Marek; Gauden, Piotr A; Szybowicz, Mirosław

    2014-01-01

    The growth of carbon nanotubes on bulk copper is studied. We show for the first time, that super growth chemical vapor deposition method can be successfully applied for preparation of nanotubes on copper catalyst, and the presence of hydrogen is necessary. Next, different methods of copper surface activation are studied, to improve catalyst efficiency. Among them, applied for the first time for copper catalyst in nanotubes synthesis, sulfuric acid activation is the most promising. Among tested samples the surface modified for 10 min is the most active, causing the growth of vertically aligned carbon nanotube forests. Obtained results have potential importance in application of nanotubes and copper in electronic chips and nanodevices. (paper)

  18. Electron diffraction from carbon nanotubes

    International Nuclear Information System (INIS)

    Qin, L-C

    2006-01-01

    The properties of a carbon nanotube are dependent on its atomic structure. The atomic structure of a carbon nanotube can be defined by specifying its chiral indices (u, v), that specify its perimeter vector (chiral vector), with which the diameter and helicity are also determined. The fine electron beam available in a modern transmission electron microscope (TEM) offers a unique probe to reveal the atomic structure of individual nanotubes. This review covers two aspects related to the use of the electron probe in the TEM for the study of carbon nanotubes: (a) to understand the electron diffraction phenomena for inter-pretation of the electron diffraction patterns of carbon nanotubes and (b) to obtain the chiral indices (u, v), of the carbon nanotubes from the electron diffraction patterns. For a nanotube of a given structure, the electron scattering amplitude from the carbon nanotube is first described analytically in closed form using the helical diffraction theory. From a known structure as given by the chiral indices (u, v), its electron diffraction pattern can be calculated and understood. The reverse problem, i.e. assignment of the chiral indices from an electron diffraction pattern of a carbon nanotube, is approached from the relationship between the electron scattering intensity distribution and the chiral indices (u, v). We show that electron diffraction patterns can provide an accurate and unambiguous assignment of the chiral indices of carbon nanotubes. The chiral indices (u, v) can be read indiscriminately with a high accuracy from the intensity distribution on the principal layer lines in an electron diffraction pattern. The symmetry properties of electron diffraction from carbon nanotubes and the electron diffraction from deformed carbon nanotubes are also discussed in detail. It is shown that 2mm symmetry is always preserved for single-walled carbon nanotubes, but it can break down for multiwalled carbon nanotubes under some special circumstances

  19. Encapsulation of cisplatin as an anti-cancer drug into boron-nitride and carbon nanotubes: Molecular simulation and free energy calculation

    Energy Technology Data Exchange (ETDEWEB)

    Roosta, Sara [Molecular Simulation Research Laboratory, Department of Chemistry, Iran University of Science & Technology, Tehran (Iran, Islamic Republic of); Hashemianzadeh, Seyed Majid, E-mail: hashemianzadeh@iust.ac.ir [Molecular Simulation Research Laboratory, Department of Chemistry, Iran University of Science & Technology, Tehran (Iran, Islamic Republic of); Ketabi, Sepideh, E-mail: sepidehketabi@yahoo.com [Department of Chemistry, East Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2016-10-01

    Encapsulation of cisplatin anticancer drug into the single walled (10, 0) carbon nanotube and (10, 0) boron-nitride nanotube was investigated by quantum mechanical calculations and Monte Carlo Simulation in aqueous solution. Solvation free energies and complexation free energies of the cisplatin@ carbon nanotube and cisplatin@ boron-nitride nanotube complexes was determined as well as radial distribution functions of entitled compounds. Solvation free energies of cisplatin@ carbon nanotube and cisplatin@ boron-nitride nanotube were − 4.128 kcal mol{sup −1} and − 2457.124 kcal mol{sup −1} respectively. The results showed that cisplatin@ boron-nitride nanotube was more soluble species in water. In addition electrostatic contribution of the interaction of boron- nitride nanotube complex and solvent was − 281.937 kcal mol{sup −1} which really more than Van der Waals and so the electrostatic interactions play a distinctive role in the solvation free energies of boron- nitride nanotube compounds. On the other hand electrostatic part of the interaction of carbon nanotube complex and solvent were almost the same as Van der Waals contribution. Complexation free energies were also computed to study the stability of related structures and the free energies were negative (− 374.082 and − 245.766 kcal mol{sup −1}) which confirmed encapsulation of drug into abovementioned nanotubes. However, boron-nitride nanotubes were more appropriate for encapsulation due to their larger solubility in aqueous solution. - Highlights: • Solubility of cisplatin@ boron-nitride nanotube is larger than cisplatin@ carbon nanotube. • Boron- nitride nanotube complexes have larger electrostatic contribution in solvation free energy. • Complexation free energies confirm encapsulation of drug into the nanotubes in aqueous solution. • Boron- nitride nanotubes are appropriate drug delivery systems compared with carbon nanotubes.

  20. Encapsulation of cisplatin as an anti-cancer drug into boron-nitride and carbon nanotubes: Molecular simulation and free energy calculation

    International Nuclear Information System (INIS)

    Roosta, Sara; Hashemianzadeh, Seyed Majid; Ketabi, Sepideh

    2016-01-01

    Encapsulation of cisplatin anticancer drug into the single walled (10, 0) carbon nanotube and (10, 0) boron-nitride nanotube was investigated by quantum mechanical calculations and Monte Carlo Simulation in aqueous solution. Solvation free energies and complexation free energies of the cisplatin@ carbon nanotube and cisplatin@ boron-nitride nanotube complexes was determined as well as radial distribution functions of entitled compounds. Solvation free energies of cisplatin@ carbon nanotube and cisplatin@ boron-nitride nanotube were − 4.128 kcal mol"−"1 and − 2457.124 kcal mol"−"1 respectively. The results showed that cisplatin@ boron-nitride nanotube was more soluble species in water. In addition electrostatic contribution of the interaction of boron- nitride nanotube complex and solvent was − 281.937 kcal mol"−"1 which really more than Van der Waals and so the electrostatic interactions play a distinctive role in the solvation free energies of boron- nitride nanotube compounds. On the other hand electrostatic part of the interaction of carbon nanotube complex and solvent were almost the same as Van der Waals contribution. Complexation free energies were also computed to study the stability of related structures and the free energies were negative (− 374.082 and − 245.766 kcal mol"−"1) which confirmed encapsulation of drug into abovementioned nanotubes. However, boron-nitride nanotubes were more appropriate for encapsulation due to their larger solubility in aqueous solution. - Highlights: • Solubility of cisplatin@ boron-nitride nanotube is larger than cisplatin@ carbon nanotube. • Boron- nitride nanotube complexes have larger electrostatic contribution in solvation free energy. • Complexation free energies confirm encapsulation of drug into the nanotubes in aqueous solution. • Boron- nitride nanotubes are appropriate drug delivery systems compared with carbon nanotubes.

  1. Adhered Supported Carbon Nanotubes

    International Nuclear Information System (INIS)

    Johnson, Dale F.; Craft, Benjamin J.; Jaffe, Stephen M.

    2001-01-01

    Carbon nanotubes (NTs) in excess of 200 μm long are grown by catalytic pyrolysis of hydrocarbon vapors. The nanotubes grow continuously without the typical extinction due to catalyst encapsulation. A woven metal mesh supports the nanotubes creating a metal supported nanotube (MSNT) structure. The 140 μm wide mesh openings are completely filled by 70 nm diameter multiwalled nanotubes (MWNTs). The MWNTs are straight, uniform and highly crystalline. Their wall thickness is about 10 nm (30 graphite layers). The adherent NTs are not removed from the support in a Scotch tape pull test. A 12.5 cm 2 capacitor made from two MSNT structures immersed in 1 M KCl has a capacitance of 0.35 F and an equivalent series resistance of 0.18 Ω. Water flows through the MSNT at a flow velocity of 1 cm/min with a pressure drop of 15 inches of water. With the support removed, the MWNTs naturally form a carbon nanocomposite (CNC) paper with a specific area of 80 m 2 /gm, a bulk density of 0.21 g/cm 3 , an open pore fraction of 0.81, and a resistivity of 0.16 Ω-cm

  2. Hidden Statistics Approach to Quantum Simulations

    Science.gov (United States)

    Zak, Michail

    2010-01-01

    Recent advances in quantum information theory have inspired an explosion of interest in new quantum algorithms for solving hard computational (quantum and non-quantum) problems. The basic principle of quantum computation is that the quantum properties can be used to represent structure data, and that quantum mechanisms can be devised and built to perform operations with this data. Three basic non-classical properties of quantum mechanics superposition, entanglement, and direct-product decomposability were main reasons for optimism about capabilities of quantum computers that promised simultaneous processing of large massifs of highly correlated data. Unfortunately, these advantages of quantum mechanics came with a high price. One major problem is keeping the components of the computer in a coherent state, as the slightest interaction with the external world would cause the system to decohere. That is why the hardware implementation of a quantum computer is still unsolved. The basic idea of this work is to create a new kind of dynamical system that would preserve the main three properties of quantum physics superposition, entanglement, and direct-product decomposability while allowing one to measure its state variables using classical methods. In other words, such a system would reinforce the advantages and minimize limitations of both quantum and classical aspects. Based upon a concept of hidden statistics, a new kind of dynamical system for simulation of Schroedinger equation is proposed. The system represents a modified Madelung version of Schroedinger equation. It preserves superposition, entanglement, and direct-product decomposability while allowing one to measure its state variables using classical methods. Such an optimal combination of characteristics is a perfect match for simulating quantum systems. The model includes a transitional component of quantum potential (that has been overlooked in previous treatment of the Madelung equation). The role of the

  3. Soldering of Nanotubes onto Microelectrodes

    DEFF Research Database (Denmark)

    Madsen, Dorte Nørgaard; Mølhave, Kristian; Mateiu, Ramona Valentina

    2003-01-01

    Suspended bridges of individual multiwalled carbon nanotubes were fabricated inside a scanning electron microscope by soldering the nanotube onto microelectrodes with highly conducting gold-carbon material. By the decomposition of organometallic vapor with the electron beam, metal-containing sold...... bonds were consistently found to be mechanically stronger than the carbon nanotubes.......Suspended bridges of individual multiwalled carbon nanotubes were fabricated inside a scanning electron microscope by soldering the nanotube onto microelectrodes with highly conducting gold-carbon material. By the decomposition of organometallic vapor with the electron beam, metal-containing solder...... bonds were formed at the intersection of the nanotube and the electrodes. Current-voltage curves indicated metallic conduction of the nanotubes, with resistances in the range of 9-29 kOmega. Bridges made entirely of the soldering material exhibited resistances on the order of 100 Omega, and the solder...

  4. Self-Volatilization Approach to Mesoporous Carbon Nanotube/Silver Nanoparticle Hybrids: The Role of Silver in Boosting Li Ion Storage.

    Science.gov (United States)

    Jiang, Hao; Zhang, Haoxuan; Fu, Yao; Guo, Shaojun; Hu, Yanjie; Zhang, Ling; Liu, Yu; Liu, Honglai; Li, Chunzhong

    2016-01-26

    One of the biggest challenging issues of carbon nanomaterials for Li ion batteries (LIBs) is that they show low initial Coulombic efficiency (CE), leading to a limited specific capacity. Herein, we demonstrate a simple template self-volatilization strategy for in situ synthesis of mesoporous carbon nanotube/Ag nanoparticle (NP) hybrids (Ag-MCNTs) to boost the LIBs' performance. The key concept of Ag-MCNTs for enhancing LIBs is that a small trace of Ag NPs on MCNTS can greatly restrict the formation of a thicker solid electrolyte interphase film, which has been well verified by both transmission electron microscopy results and quantum density functional theory calculations, leading to the highest initial CE in all the reported carbon nanomaterials. This uncovered property of Ag NPs from Ag-MCNTs makes them exhibit a very high reversible capacity of 1637 mAh g(-1) after 400 discharge/charge cycles at 100 mA g(-1), approximately 5 times higher than the theoretical value of a graphite anode (372 mAh g(-1)), excellent rate capability, and long cycle life.

  5. Extended abstract of a hidden agenda

    Energy Technology Data Exchange (ETDEWEB)

    Goguen, J.; Malcolm, G. [Oxford Univ. (United Kingdom)

    1996-12-31

    The initial goal of our hidden research programme was both straightforward and ambitious: give a semantics for software engineering, and in particular for the object paradigm, supporting correctness proofs that are as simple and mechanical as possible. This emphasizes proofs rather than models, and thus suggests an equational approach, rather than one based on higher order logic, denotational semantics, or any kind of model, because equational proofs achieve maximal simplicity and mechanization, and yet are fully expressive. We introduce powerful coinduction techniques for proving behavioral properties of complex systems. We make the no doubt outrageous claim that our hidden approach gives simpler proofs than other formalisms; this is because we exploit algebraic structure that most other approaches discard.

  6. Laser experiments explore the hidden sector

    International Nuclear Information System (INIS)

    Ahlers, M.

    2007-11-01

    Recently, the laser experiments BMV and GammeV, searching for light shining through walls, have published data and calculated new limits on the allowed masses and couplings for axion-like particles. In this note we point out that these experiments can serve to constrain a much wider variety of hidden-sector particles such as, e.g., minicharged particles and hidden-sector photons. The new experiments improve the existing bounds from the older BFRT experiment by a factor of two. Moreover, we use the new PVLAS constraints on a possible rotation and ellipticity of light after it has passed through a strong magnetic field to constrain pure minicharged particle models. For masses -7 times the electron electric charge. This is the best laboratory bound and comparable to bounds inferred from the energy spectrum of the cosmic microwave background. (orig.)

  7. Quantum mechanics and hidden superconformal symmetry

    Science.gov (United States)

    Bonezzi, R.; Corradini, O.; Latini, E.; Waldron, A.

    2017-12-01

    Solvability of the ubiquitous quantum harmonic oscillator relies on a spectrum generating osp (1 |2 ) superconformal symmetry. We study the problem of constructing all quantum mechanical models with a hidden osp (1 |2 ) symmetry on a given space of states. This problem stems from interacting higher spin models coupled to gravity. In one dimension, we show that the solution to this problem is the Vasiliev-Plyushchay family of quantum mechanical models with hidden superconformal symmetry obtained by viewing the harmonic oscillator as a one dimensional Dirac system, so that Grassmann parity equals wave function parity. These models—both oscillator and particlelike—realize all possible unitary irreducible representations of osp (1 |2 ).

  8. The Hidden Gifts of Quiet Kids

    Science.gov (United States)

    Trierweiler, Hannah

    2006-01-01

    The author relates that she was an introvert child. It has always taken her time and energy to find her place in a group. As a grown-up, she still needed quiet time to regroup during a busy day. In this article, the author presents an interview with Marti Olsen Laney, author of "The Hidden Gifts of the Introverted Child." During the interview,…

  9. Hidden neuronal correlations in cultured networks

    International Nuclear Information System (INIS)

    Segev, Ronen; Baruchi, Itay; Hulata, Eyal; Ben-Jacob, Eshel

    2004-01-01

    Utilization of a clustering algorithm on neuronal spatiotemporal correlation matrices recorded during a spontaneous activity of in vitro networks revealed the existence of hidden correlations: the sequence of synchronized bursting events (SBEs) is composed of statistically distinguishable subgroups each with its own distinct pattern of interneuron spatiotemporal correlations. These findings hint that each of the SBE subgroups can serve as a template for coding, storage, and retrieval of a specific information

  10. A masking index for quantifying hidden glitches

    OpenAIRE

    Berti-Equille, Laure; Loh, J. M.; Dasu, T.

    2015-01-01

    Data glitches are errors in a dataset. They are complex entities that often span multiple attributes and records. When they co-occur in data, the presence of one type of glitch can hinder the detection of another type of glitch. This phenomenon is called masking. In this paper, we define two important types of masking and propose a novel, statistically rigorous indicator called masking index for quantifying the hidden glitches. We outline four cases of masking: outliers masked by missing valu...

  11. Cold dark matter from the hidden sector

    International Nuclear Information System (INIS)

    Arias, Paola; Pontificia Univ. Catolica de Chile, Santiago

    2012-02-01

    Weakly interacting slim particles (WISPs) such as hidden photons (HP) and axion-like particles (ALPs) have been proposed as cold dark matter candidates. They might be produced non-thermally via the misalignment mechanism, similarly to cold axions. In this talk we review the main processes of thermalisation of HP and we compute the parameter space that may survive as cold dark matter population until today. Our findings are quite encouraging for experimental searches in the laboratory in the near future.

  12. Completing Quantum Mechanics with Quantized Hidden Variables

    OpenAIRE

    van Enk, S. J.

    2015-01-01

    I explore the possibility that a quantum system S may be described completely by the combination of its standard quantum state $|\\psi\\rangle$ and a (hidden) quantum state $|\\phi\\rangle$ (that lives in the same Hilbert space), such that the outcome of any standard projective measurement on the system S is determined once the two quantum states are specified. I construct an algorithm that retrieves the standard quantum-mechanical probabilities, which depend only on $|\\psi\\rangle$, by assuming t...

  13. Cold dark matter from the hidden sector

    Energy Technology Data Exchange (ETDEWEB)

    Arias, Paola [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Pontificia Univ. Catolica de Chile, Santiago (Chile). Facultad de Fisica

    2012-02-15

    Weakly interacting slim particles (WISPs) such as hidden photons (HP) and axion-like particles (ALPs) have been proposed as cold dark matter candidates. They might be produced non-thermally via the misalignment mechanism, similarly to cold axions. In this talk we review the main processes of thermalisation of HP and we compute the parameter space that may survive as cold dark matter population until today. Our findings are quite encouraging for experimental searches in the laboratory in the near future.

  14. Hidden histories: challenges for pedagogy and participation

    OpenAIRE

    Morrice, Linda

    2013-01-01

    Higher Education has become and an increasingly diverse and globalised system in which the binaries between ‘traditional’ and ‘non-traditional’ students, exclusion and inclusion have less resonance and analytical purchase. Drawing on research with refugees Linda will suggest that higher education can be marked simultaneously by belonging and recognition, deficit and exclusion. Complex differences and inequalities remain hidden and unspoken, raising new questions and challenges for pedagogy an...

  15. Hidden sector behind the CKM matrix

    Science.gov (United States)

    Okawa, Shohei; Omura, Yuji

    2017-08-01

    The small quark mixing, described by the Cabibbo-Kobayashi-Maskawa (CKM) matrix in the standard model, may be a clue to reveal new physics around the TeV scale. We consider a simple scenario that extra particles in a hidden sector radiatively mediate the flavor violation to the quark sector around the TeV scale and effectively realize the observed CKM matrix. The lightest particle in the hidden sector, whose contribution to the CKM matrix is expected to be dominant, is a good dark matter (DM) candidate. There are many possible setups to describe this scenario, so that we investigate some universal predictions of this kind of model, focusing on the contribution of DM to the quark mixing and flavor physics. In this scenario, there is an explicit relation between the CKM matrix and flavor violating couplings, such as four-quark couplings, because both are radiatively induced by the particles in the hidden sector. Then, we can explicitly find the DM mass region and the size of Yukawa couplings between the DM and quarks, based on the study of flavor physics and DM physics. In conclusion, we show that DM mass in our scenario is around the TeV scale, and the Yukawa couplings are between O (0.01 ) and O (1 ). The spin-independent DM scattering cross section is estimated as O (10-9) [pb]. An extra colored particle is also predicted at the O (10 ) TeV scale.

  16. The hidden crime: human trafficking.

    Science.gov (United States)

    Clause, Kristen J; Lawler, Kate Byrnes

    2013-01-01

    As the primary contact in the health care system, nurses can play a role in combating this crime and assisting the victims. Assessment for abuse, neglect, trauma, recurrent sexually transmitted infections (STIs) and fear of a controlling partner is critical. Following up on "red flags" and understanding methods of safe questioning can make the difference between slavery and recovery for victims. Nurses must also know the professional referrals in their areas once a potential victim has been identified. This may be a very dangerous undertaking and must be handled by experienced personnel. Referrals to forensic nurses or physicians, domestic violence professionals or law enforcement may be indicated. Initially, a nurse may want to consult with the agency social worker for guidance. Human trafficking is a human rights crime. Unfortunately, it is more prevalent in all types of communities than most people suspect. Nurses can be heroes to the victims through understanding of this crime and vigilance in the assessment and care of all people they encounter in their practices.

  17. High pressure synthesis of amorphous TiO2 nanotubes

    Directory of Open Access Journals (Sweden)

    Quanjun Li

    2015-09-01

    Full Text Available Amorphous TiO2 nanotubes with diameters of 8-10 nm and length of several nanometers were synthesized by high pressure treatment of anatase TiO2 nanotubes. The structural phase transitions of anatase TiO2 nanotubes were investigated by using in-situ high-pressure synchrotron X-ray diffraction (XRD method. The starting anatase structure is stable up to ∼20GPa, and transforms into a high-density amorphous (HDA form at higher pressure. Pressure-modified high- to low-density transition was observed in the amorphous form upon decompression. The pressure-induced amorphization and polyamorphism are in good agreement with the previous results in ultrafine TiO2 nanoparticles and nanoribbons. The relationship between the LDA form and α-PbO2 phase was revealed by high-resolution transmission electron microscopy (HRTEM study. In addition, the bulk modulus (B0 = 158 GPa of the anatase TiO2 nanotubes is smaller than those of the corresponding bulks and nanoparticles (180-240 GPa. We suggest that the unique open-ended nanotube morphology and nanosize play important roles in the high pressure phase transition of TiO2 nanotubes.

  18. Continuous carbon nanotube reinforced composites.

    Science.gov (United States)

    Ci, L; Suhr, J; Pushparaj, V; Zhang, X; Ajayan, P M

    2008-09-01

    Carbon nanotubes are considered short fibers, and polymer composites with nanotube fillers are always analogues of random, short fiber composites. The real structural carbon fiber composites, on the other hand, always contain carbon fiber reinforcements where fibers run continuously through the composite matrix. With the recent optimization in aligned nanotube growth, samples of nanotubes in macroscopic lengths have become available, and this allows the creation of composites that are similar to the continuous fiber composites with individual nanotubes running continuously through the composite body. This allows the proper utilization of the extreme high modulus and strength predicted for nanotubes in structural composites. Here, we fabricate such continuous nanotube polymer composites with continuous nanotube reinforcements and report that under compressive loadings, the nanotube composites can generate more than an order of magnitude improvement in the longitudinal modulus (up to 3,300%) as well as damping capability (up to 2,100%). It is also observed that composites with a random distribution of nanotubes of same length and similar filler fraction provide three times less effective reinforcement in composites.

  19. Cl-Assisted Large Scale Synthesis of Cm-Scale Buckypapers of Fe₃C-Filled Carbon Nanotubes with Pseudo-Capacitor Properties: The Key Role of SBA-16 Catalyst Support as Synthesis Promoter.

    Science.gov (United States)

    Boi, Filippo S; He, Yi; Wen, Jiqiu; Wang, Shanling; Yan, Kai; Zhang, Jingdong; Medranda, Daniel; Borowiec, Joanna; Corrias, Anna

    2017-10-23

    We show a novel chemical vapour deposition (CVD) approach, in which the large-scale fabrication of ferromagnetically-filled cm-scale buckypapers is achieved through the deposition of a mesoporous supported catalyst (SBA-16) on a silicon substrate. We demonstrate that SBA-16 has the crucial role of promoting the growth of carbon nanotubes (CNTs) on a horizontal plane with random orientation rather than in a vertical direction, therefore allowing a facile fabrication of cm-scale CNTs buckypapers free from the onion-crust by-product observed on the buckypaper-surface in previous reports. The morphology and composition of the obtained CNTs-buckypapers are analyzed in detail by scanning electron microscopy (SEM), Energy Dispersive X-ray (EDX), transmission electron microscopy (TEM), high resolution TEM (HRTEM), and thermogravimetric analysis (TGA), while structural analysis is performed by Rietveld Refinement of XRD data. The room temperature magnetic properties of the produced buckypapers are also investigated and reveal the presence of a high coercivity of 650 Oe. Additionally, the electrochemical performances of these buckypapers are demonstrated and reveal a behavior that is compatible with that of a pseudo-capacitor (resistive-capacitor) with better performances than those presented in other previously studied layered-buckypapers of Fe-filled CNTs, obtained by pyrolysis of dichlorobenzene-ferrocene mixtures. These measurements indicate that these materials show promise for applications in energy storage systems as flexible electrodes.

  20. Modifying the electronic and optical properties of carbon nanotubes

    Science.gov (United States)

    Kinder, Jesse M.

    The intrinsic electronic and optical properties of carbon nanotubes make them promising candidates for circuit elements and LEDs in nanoscale devices. However, applied fields and interactions with the environment can modify these intrinsic properties. This dissertation is a theoretical study of perturbations to an ideal carbon nanotube. It illustrates how transport and optical properties of carbon nanotubes can be adversely affected or intentionally modified by the local environment. The dissertation is divided into three parts. Part I analyzes the effect of a transverse electric field on the single-electron energy spectrum of semiconducting carbon nanotubes. Part II analyzes the effect of the local environment on selection rules and decay pathways relevant to dark excitons. Part III is a series of 26 appendices. Two different models for a transverse electric field are introduced in Part I. The first is a uniform field perpendicular to the nanotube axis. This model suggests the field has little effect on the band gap until it exceeds a critical value that can be tuned with strain or a magnetic field. The second model is a transverse field localized to a small region along the nanotube axis. The field creates a pair of exponentially localized bound states but has no effect on the band gap for particle transport. Part II explores the physics of dark excitons in carbon nanotubes. Two model calculations illustrate the effect of the local environment on allowed optical transitions and nonradiative recombination pathways. The first model illustrates the role of inversion symmetry in the optical spectrum. Broken inversion symmetry may explain low-lying peaks in the exciton spectrum of boron nitride nanotubes and localized photoemission around impurities and interfaces in carbon nanotubes. The second model in Part II suggests that free charge carriers can mediate an efficient nonradiative decay process for dark excitons in carbon nanotubes. The appendices in Part III

  1. Revealing hidden covariation detection: evidence for implicit abstraction at study.

    Science.gov (United States)

    Rossnagel, C S

    2001-09-01

    Four experiments in the brain scans paradigm (P. Lewicki, T. Hill, & I. Sasaki, 1989) investigated hidden covariation detection (HCD). In Experiment 1 HCD was found in an implicit- but not in an explicit-instruction group. In Experiment 2 HCD was impaired by nonholistic perception of stimuli but not by divided attention. In Experiment 3 HCD was eliminated by interspersing stimuli that deviated from the critical covariation. In Experiment 4 a transfer procedure was used. HCD was found with dissimilar test stimuli that preserved the covariation but was almost eliminated with similar stimuli that were neutral as to the covariation. Awareness was assessed both by objective and subjective tests in all experiments. Results suggest that HCD is an effect of implicit rule abstraction and that similarity processing plays only a minor role. HCD might be suppressed by intentional search strategies that induce inappropriate aggregation of stimulus information.

  2. Hidden-charm Pentaquark Production at e + e - Colliders

    Science.gov (United States)

    Li, Shi-Yuan; Liu, Yan-Rui; Liu, Yu-Nan; Si, Zong-Guo; Zhang, Xiao-Feng

    2018-03-01

    We study one possible production mechanism for the hidden-charm pentaquark via a color-octet c\\bar{c} pair fragmentation in e + e - collision. The pentaquark production at B factory energy is dominated by {e}+{e}-\\to c\\bar{c}g\\to {P}c+X, while at Z 0 pole energy, there are several partonic processes playing significant role. Our results show that it is possible to search for the direct pentaquark production signal at e + e - colliders, which is important to understand the properties of pentaquark. Supported by National Natural Science Foundation of China under Grant Nos. 11775130, 11775132, 11635009, 11325525 and the Natural Science Foundation of Shandong Province under Grant No. ZR2017MA002

  3. Microwave background constraints on mixing of photons with hidden photons

    International Nuclear Information System (INIS)

    Mirizzi, Alessandro; Redondo, Javier; Sigl, Guenter

    2008-12-01

    Various extensions of the Standard Model predict the existence of hidden photons kinetically mixing with the ordinary photon. This mixing leads to oscillations between photons and hidden photons, analogous to the observed oscillations between different neutrino flavors. In this context, we derive new bounds on the photon-hidden photon mixing parameters using the high precision cosmic microwave background spectral data collected by the Far Infrared Absolute Spectrophotometer instrument on board of the Cosmic Background Explorer. Requiring the distortions of the CMB induced by the photon-hidden photon mixing to be smaller than experimental upper limits, this leads to a bound on the mixing angle χ 0 -7 - 10 -5 for hidden photon masses between 10 -14 eV and 10 -7 eV. This low-mass and low-mixing region of the hidden photon parameter space was previously unconstrained. (orig.)

  4. Microwave background constraints on mixing of photons with hidden photons

    Energy Technology Data Exchange (ETDEWEB)

    Mirizzi, Alessandro [Max-Planck-Institut fuer Physik, Muenchen (Germany); Redondo, Javier [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Sigl, Guenter [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2008-12-15

    Various extensions of the Standard Model predict the existence of hidden photons kinetically mixing with the ordinary photon. This mixing leads to oscillations between photons and hidden photons, analogous to the observed oscillations between different neutrino flavors. In this context, we derive new bounds on the photon-hidden photon mixing parameters using the high precision cosmic microwave background spectral data collected by the Far Infrared Absolute Spectrophotometer instrument on board of the Cosmic Background Explorer. Requiring the distortions of the CMB induced by the photon-hidden photon mixing to be smaller than experimental upper limits, this leads to a bound on the mixing angle {chi}{sub 0} hidden photon masses between 10{sup -14} eV and 10{sup -7} eV. This low-mass and low-mixing region of the hidden photon parameter space was previously unconstrained. (orig.)

  5. The Hidden Curriculum of Veterinary Education: Mediators and Moderators of Its Effects.

    Science.gov (United States)

    Roder, Carrie A; May, Stephen A

    The "hidden curriculum" has long been supposed to have an effect on students' learning during their clinical education, and in particular in shaping their ideas of what it means to be a professional. Despite this, there has been little evidence linking specific changes in professional attitudes to the individual components of the hidden curriculum. This study aimed to recognize those components that led to a change in students' professional attitudes at a UK veterinary school, as well as to identify the attitudes most affected. Observations were made of 11 student groups across five clinical rotations, followed by semi-structured interviews with 23 students at the end of their rotation experience. Data were combined and analyzed thematically, taking both an inductive and deductive approach. Views about the importance of technical competence and communication skills were promoted as a result of students' interaction with the hidden curriculum, and tensions were revealed in relation to their attitudes toward compassion and empathy, autonomy and responsibility, and lifestyle ethic. The assessment processes of rotations and the clinical service organization served to communicate the messages of the hidden curriculum, bringing about changes in student professional attitudes, while student-selected role models and the student rotation groups moderated the effects of these influences.

  6. State-space dimensionality in short-memory hidden-variable theories

    International Nuclear Information System (INIS)

    Montina, Alberto

    2011-01-01

    Recently we have presented a hidden-variable model of measurements for a qubit where the hidden-variable state-space dimension is one-half the quantum-state manifold dimension. The absence of a short memory (Markov) dynamics is the price paid for this dimensional reduction. The conflict between having the Markov property and achieving the dimensional reduction was proved by Montina [A. Montina, Phys. Rev. A 77, 022104 (2008)] using an additional hypothesis of trajectory relaxation. Here we analyze in more detail this hypothesis introducing the concept of invertible process and report a proof that makes clearer the role played by the topology of the hidden-variable space. This is accomplished by requiring suitable properties of regularity of the conditional probability governing the dynamics. In the case of minimal dimension the set of continuous hidden variables is identified with an object living an N-dimensional Hilbert space whose dynamics is described by the Schroedinger equation. A method for generating the economical non-Markovian model for the qubit is also presented.

  7. VISIBLE COSTS AND HIDDEN COSTS IN THE BAKING INDUSTRY

    Directory of Open Access Journals (Sweden)

    Criveanu Maria

    2013-04-01

    Full Text Available Hidden costs are present in the activity of any company, hardly identified in the traditional administrative accounting. The high levels of the hidden costs and their unknown presence have serious consequences on the decisions made by the managers. This paper aims at presenting some aspects related to the hidden costs that occur in the activity of the companies in the baking industry and the possibilities to reduce their level.

  8. Continuum theory for nanotube piezoelectricity.

    Science.gov (United States)

    Michalski, P J; Sai, Na; Mele, E J

    2005-09-09

    We develop and solve a continuum theory for the piezoelectric response of one-dimensional nanotubes and nanowires, and apply the theory to study electromechanical effects in boron-nitride nanotubes. We find that the polarization of a nanotube depends on its aspect ratio, and a dimensionless constant specifying the ratio of the strengths of the elastic and electrostatic interactions. The solutions of the model as these two parameters are varied are discussed. The theory is applied to estimate the electric potential induced along the length of a boron-nitride nanotube in response to a uniaxial stress.

  9. Mechanical properties of carbon nanotubes

    Science.gov (United States)

    Salvetat, J.-P.; Bonard, J.-M.; Thomson, N. H.; Kulik, A. J.; Forró, L.; Benoit, W.; Zuppiroli, L.

    A variety of outstanding experimental results on the elucidation of the elastic properties of carbon nanotubes are fast appearing. These are based mainly on the techniques of high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM) to determine the Young's moduli of single-wall nanotube bundles and multi-walled nanotubes, prepared by a number of methods. These results are confirming the theoretical predictions that carbon nanotubes have high strength plus extraordinary flexibility and resilience. As well as summarising the most notable achievements of theory and experiment in the last few years, this paper explains the properties of nanotubes in the wider context of materials science and highlights the contribution of our research group in this rapidly expanding field. A deeper understanding of the relationship between the structural order of the nanotubes and their mechanical properties will be necessary for the development of carbon-nanotube-based composites. Our research to date illustrates a qualitative relationship between the Young's modulus of a nanotube and the amount of disorder in the atomic structure of the walls. Other exciting results indicate that composites will benefit from the exceptional mechanical properties of carbon nanotubes, but that the major outstanding problem of load transfer efficiency must be overcome before suitable engineering materials can be produced.

  10. Fabricating Copper Nanotubes by Electrodeposition

    Science.gov (United States)

    Yang, E. H.; Ramsey, Christopher; Bae, Youngsam; Choi, Daniel

    2009-01-01

    Copper tubes having diameters between about 100 and about 200 nm have been fabricated by electrodeposition of copper into the pores of alumina nanopore membranes. Copper nanotubes are under consideration as alternatives to copper nanorods and nanowires for applications involving thermal and/or electrical contacts, wherein the greater specific areas of nanotubes could afford lower effective thermal and/or electrical resistivities. Heretofore, copper nanorods and nanowires have been fabricated by a combination of electrodeposition and a conventional expensive lithographic process. The present electrodeposition-based process for fabricating copper nanotubes costs less and enables production of copper nanotubes at greater rate.

  11. Biomineralization of superhydrophilic vertically aligned carbon nanotubes.

    Science.gov (United States)

    Marsi, Teresa Cristina O; Santos, Tiago G; Pacheco-Soares, Cristina; Corat, Evaldo J; Marciano, Fernanda R; Lobo, Anderson O

    2012-03-06

    Vertically aligned carbon nanotubes (VACNT) promise a great role for the study of tissue regeneration. In this paper, we introduce a new biomimetic mineralization routine employing superhydrophilic VACNT films as highly stable template materials. The biomineralization was obtained after VACNT soaking in simulated body fluid solution. Detailed structural analysis reveals that the polycrystalline biological apatites formed due to the -COOH terminations attached to VACNT tips after oxygen plasma etching. Our approach not only provides a novel route for nanostructured materials, but also suggests that COOH termination sites can play a significant role in biomimetic mineralization. These new nanocomposites are very promising as nanobiomaterials due to the excellent human osteoblast adhesion.

  12. Compressing the hidden variable space of a qubit

    International Nuclear Information System (INIS)

    Montina, Alberto

    2011-01-01

    In previously exhibited hidden variable models of quantum state preparation and measurement, the number of continuous hidden variables describing the actual state of single realizations is never smaller than the quantum state manifold dimension. We introduce a simple model for a qubit whose hidden variable space is one-dimensional, i.e., smaller than the two-dimensional Bloch sphere. The hidden variable probability distributions associated with quantum states satisfy reasonable criteria of regularity. Possible generalizations of this shrinking to an N-dimensional Hilbert space are discussed.

  13. Zipf exponent of trajectory distribution in the hidden Markov model

    Science.gov (United States)

    Bochkarev, V. V.; Lerner, E. Yu

    2014-03-01

    This paper is the first step of generalization of the previously obtained full classification of the asymptotic behavior of the probability for Markov chain trajectories for the case of hidden Markov models. The main goal is to study the power (Zipf) and nonpower asymptotics of the frequency list of trajectories of hidden Markov frequencys and to obtain explicit formulae for the exponent of the power asymptotics. We consider several simple classes of hidden Markov models. We prove that the asymptotics for a hidden Markov model and for the corresponding Markov chain can be essentially different.

  14. Zipf exponent of trajectory distribution in the hidden Markov model

    International Nuclear Information System (INIS)

    Bochkarev, V V; Lerner, E Yu

    2014-01-01

    This paper is the first step of generalization of the previously obtained full classification of the asymptotic behavior of the probability for Markov chain trajectories for the case of hidden Markov models. The main goal is to study the power (Zipf) and nonpower asymptotics of the frequency list of trajectories of hidden Markov frequencys and to obtain explicit formulae for the exponent of the power asymptotics. We consider several simple classes of hidden Markov models. We prove that the asymptotics for a hidden Markov model and for the corresponding Markov chain can be essentially different

  15. Hidden acoustic information revealed by intentional nonlinearity

    Science.gov (United States)

    Dowling, David R.

    2017-11-01

    Acoustic waves are omnipresent in modern life and are well described by the linearized equations of fluid dynamics. Once generated, acoustic waves carry and collect information about their source and the environment through which they propagate, respectively, and this information may be retrieved by analyzing recordings of these waves. Because of this, acoustics is the primary means for observation, surveillance, reconnaissance, and remote sensing in otherwise opaque environments, such as the Earth's oceans and crust, and the interior of the human body. For such information-retrieval tasks, acoustic fields are nearly always interrogated within their recorded frequency range or bandwidth. However, this frequency-range restriction is not general; acoustic fields may also carry (hidden) information at frequencies outside their bandwidth. Although such a claim may seem counter intuitive, hidden acoustic-field information can be revealed by re-introducing a marquee trait of fluid dynamics: nonlinearity. In particular, an intentional quadratic nonlinearity - a form of intra-signal heterodyning - can be used to obtain acoustic field information at frequencies outside a recorded acoustic field's bandwidth. This quadratic nonlinearity enables a variety of acoustic remote sensing applications that were long thought to be impossible. In particular, it allows the detrimental effects of sparse recordings and random scattering to be suppressed when the original acoustic field has sufficient bandwidth. In this presentation, the topic is developed heuristically, with a just brief exposition of the relevant mathematics. Hidden acoustic field information is then revealed from simulated and measured acoustic fields in simple and complicated acoustic environments involving frequencies from a few Hertz to more than 100 kHz, and propagation distances from tens of centimeters to hundreds of kilometers. Sponsored by ONR, NAVSEA, and NSF.

  16. Recovering a hidden polarization by ghost polarimetry.

    Science.gov (United States)

    Janassek, Patrick; Blumenstein, Sébastien; Elsäßer, Wolfgang

    2018-02-15

    By exploiting polarization correlations of light from a broadband fiber-based amplified spontaneous emission source we succeed in reconstructing a hidden polarization in a ghost polarimetry experiment in close analogy to ghost imaging and ghost spectroscopy. Thereby, an original linear polarization state in the object arm of a Mach-Zehnder interferometer configuration which has been camouflaged by a subsequent depolarizer is recovered by correlating it with light from a reference beam. The variation of a linear polarizer placed inside the reference beam results in a Malus law type second-order intensity correlation with high contrast, thus measuring a ghost polarigram.

  17. Pruning Boltzmann networks and hidden Markov models

    DEFF Research Database (Denmark)

    Pedersen, Morten With; Stork, D.

    1996-01-01

    We present sensitivity-based pruning algorithms for general Boltzmann networks. Central to our methods is the efficient calculation of a second-order approximation to the true weight saliencies in a cross-entropy error. Building upon previous work which shows a formal correspondence between linear...... Boltzmann chains and hidden Markov models (HMMs), we argue that our method can be applied to HMMs as well. We illustrate pruning on Boltzmann zippers, which are equivalent to two HMMs with cross-connection links. We verify that our second-order approximation preserves the rank ordering of weight saliencies...

  18. Hidden Scale Invariance in Condensed Matter

    DEFF Research Database (Denmark)

    Dyre, J. C.

    2014-01-01

    . This means that the phase diagram becomes effectively one-dimensional with regard to several physical properties. Liquids and solids with isomorphs include most or all van der Waals bonded systems and metals, as well as weakly ionic or dipolar systems. On the other hand, systems with directional bonding...... (hydrogen bonds or covalent bonds) or strong Coulomb forces generally do not exhibit hidden scale invariance. The article reviews the theory behind this picture of condensed matter and the evidence for it coming from computer simulations and experiments...

  19. Uncovering the Hidden Costs of Offshoring

    DEFF Research Database (Denmark)

    Larsen, Marcus M.; Manning, Stephan; Pedersen, Torben

    2013-01-01

    This study investigates estimation errors due to hidden costs—the costs of implementation that are neglected in strategic decision-making processes—in the context of services offshoring. Based on data from the Offshoring Research Network, we find that decision makers are more likely to make cost......-estimation errors given increasing configuration and task complexity in captive offshoring and offshore outsourcing, respectively. Moreover, we show that experience and a strong orientation toward organizational design in the offshoring strategy reduce the cost-estimation errors that follow from complexity. Our...

  20. The hidden face of the petroleum

    International Nuclear Information System (INIS)

    Laurent, E.

    2006-02-01

    For the first time, a book reveals what that was hidden to the public opinions: why the petroleum crisis of 1973 what only a manipulation, an arrangement between the OPEC and the petroleum companies, why the data concerning the petroleum reserves are wrong and increased by the producers countries, how Washington used the Saudi petroleum weapon to create the Soviet Union fall, and why from march 2001 maps of the Iraq (where were drawn the future petroleum explorations) were working documents for the vice President Cheney and petroleum managers for the ''secret society''. (A.L.B.)

  1. Evolving the structure of hidden Markov Models

    DEFF Research Database (Denmark)

    won, K. J.; Prugel-Bennett, A.; Krogh, A.

    2006-01-01

    A genetic algorithm (GA) is proposed for finding the structure of hidden Markov Models (HMMs) used for biological sequence analysis. The GA is designed to preserve biologically meaningful building blocks. The search through the space of HMM structures is combined with optimization of the emission...... and transition probabilities using the classic Baum-Welch algorithm. The system is tested on the problem of finding the promoter and coding region of C. jejuni. The resulting HMM has a superior discrimination ability to a handcrafted model that has been published in the literature....

  2. The hidden costs of nuclear power

    International Nuclear Information System (INIS)

    Keough, C.

    1981-01-01

    The two basic hidden costs of nuclear power are public money and public health. Nuclear power appears to be economical because many of the costs of producins electricity in these plants are paid by the federal government. So, like it or not, the citizens are footing the bill with their taxes. Design and development of plants have been paid for with public money, and disposal and cleanup costs will also be paid in this manner. The economic and health costs associated with nuclear accidents are staggering

  3. Genetic Algorithms Principles Towards Hidden Markov Model

    Directory of Open Access Journals (Sweden)

    Nabil M. Hewahi

    2011-10-01

    Full Text Available In this paper we propose a general approach based on Genetic Algorithms (GAs to evolve Hidden Markov Models (HMM. The problem appears when experts assign probability values for HMM, they use only some limited inputs. The assigned probability values might not be accurate to serve in other cases related to the same domain. We introduce an approach based on GAs to find
    out the suitable probability values for the HMM to be mostly correct in more cases than what have been used to assign the probability values.

  4. Detecting Structural Breaks using Hidden Markov Models

    DEFF Research Database (Denmark)

    Ntantamis, Christos

    Testing for structural breaks and identifying their location is essential for econometric modeling. In this paper, a Hidden Markov Model (HMM) approach is used in order to perform these tasks. Breaks are defined as the data points where the underlying Markov Chain switches from one state to another....... The estimation of the HMM is conducted using a variant of the Iterative Conditional Expectation-Generalized Mixture (ICE-GEMI) algorithm proposed by Delignon et al. (1997), that permits analysis of the conditional distributions of economic data and allows for different functional forms across regimes...

  5. Global Update and Trends of Hidden Hunger, 1995-2011: The Hidden Hunger Index

    Science.gov (United States)

    Stevens, Gretchen A.; Ezzati, Majid; Black, Robert E.; Kraemer, Klaus

    2015-01-01

    Background Deficiencies in essential vitamins and minerals–also termed hidden hunger–are pervasive and hold negative consequences for the cognitive and physical development of children. Methods This analysis evaluates the change in hidden hunger over time in the form of one composite indicator–the Hidden Hunger Index (HHI)–using an unweighted average of prevalence estimates from the Nutrition Impact Model Study for anemia due to iron deficiency, vitamin A deficiency, and stunting (used as a proxy indicator for zinc deficiency). Net changes from 1995–2011 and population weighted regional means for various time periods are measured. Findings Globally, hidden hunger improved (-6.7 net change in HHI) from 1995–2011. Africa was the only region to see a deterioration in hidden hunger (+1.9) over the studied time period; East Asia and the Pacific performed exceptionally well (-13.0), while other regions improved only slightly. Improvements in HHI were mostly due to reductions in zinc and vitamin A deficiencies, while anemia due to iron deficiency persisted and even increased. Interpretation This analysis is critical for informing and tracking the impact of policy and programmatic efforts to reduce micronutrient deficiencies, to advance the global nutrition agenda, and to achieve the Millennium Development Goals (MDGs). However, there remains an unmet need to invest in gathering frequent, nationally representative, high-quality micronutrient data as we renew our efforts to scale up nutrition, and as we enter the post-2015 development agenda. Funding Preparation of this manuscript was funded by Sight and Life. There was no funding involved in the study design, data collection, analysis, or decision to publish. PMID:26673631

  6. Global Update and Trends of Hidden Hunger, 1995-2011: The Hidden Hunger Index.

    Directory of Open Access Journals (Sweden)

    Julie C Ruel-Bergeron

    Full Text Available Deficiencies in essential vitamins and minerals-also termed hidden hunger-are pervasive and hold negative consequences for the cognitive and physical development of children.This analysis evaluates the change in hidden hunger over time in the form of one composite indicator-the Hidden Hunger Index (HHI-using an unweighted average of prevalence estimates from the Nutrition Impact Model Study for anemia due to iron deficiency, vitamin A deficiency, and stunting (used as a proxy indicator for zinc deficiency. Net changes from 1995-2011 and population weighted regional means for various time periods are measured.Globally, hidden hunger improved (-6.7 net change in HHI from 1995-2011. Africa was the only region to see a deterioration in hidden hunger (+1.9 over the studied time period; East Asia and the Pacific performed exceptionally well (-13.0, while other regions improved only slightly. Improvements in HHI were mostly due to reductions in zinc and vitamin A deficiencies, while anemia due to iron deficiency persisted and even increased.This analysis is critical for informing and tracking the impact of policy and programmatic efforts to reduce micronutrient deficiencies, to advance the global nutrition agenda, and to achieve the Millennium Development Goals (MDGs. However, there remains an unmet need to invest in gathering frequent, nationally representative, high-quality micronutrient data as we renew our efforts to scale up nutrition, and as we enter the post-2015 development agenda.Preparation of this manuscript was funded by Sight and Life. There was no funding involved in the study design, data collection, analysis, or decision to publish.

  7. Carbon nanotube plane fastener

    Directory of Open Access Journals (Sweden)

    Kaori Hirahara

    2011-12-01

    Full Text Available We report a feature of carbon nanotubes (CNTs that arises when the surfaces of two vertically-aligned CNT brushes are pressed together. Adhesion between the CNTs creates a plane fastener-like device. Observations from scanning electron microscopy and measurements of adhesion properties indicate a device-dependence on CNT density and shape near the tip region. Among other applications, such fasteners have the potential to attach small components onto micron-sized electronic devices.

  8. Carbon nanotube network varactor

    International Nuclear Information System (INIS)

    Generalov, A A; Anoshkin, I V; Lioubtchenko, D V; Räisänen, A V; Erdmanis, M; Ovchinnikov, V; Nasibulin, A G

    2015-01-01

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling. (paper)

  9. Bayesian structural inference for hidden processes

    Science.gov (United States)

    Strelioff, Christopher C.; Crutchfield, James P.

    2014-04-01

    We introduce a Bayesian approach to discovering patterns in structurally complex processes. The proposed method of Bayesian structural inference (BSI) relies on a set of candidate unifilar hidden Markov model (uHMM) topologies for inference of process structure from a data series. We employ a recently developed exact enumeration of topological ɛ-machines. (A sequel then removes the topological restriction.) This subset of the uHMM topologies has the added benefit that inferred models are guaranteed to be ɛ-machines, irrespective of estimated transition probabilities. Properties of ɛ-machines and uHMMs allow for the derivation of analytic expressions for estimating transition probabilities, inferring start states, and comparing the posterior probability of candidate model topologies, despite process internal structure being only indirectly present in data. We demonstrate BSI's effectiveness in estimating a process's randomness, as reflected by the Shannon entropy rate, and its structure, as quantified by the statistical complexity. We also compare using the posterior distribution over candidate models and the single, maximum a posteriori model for point estimation and show that the former more accurately reflects uncertainty in estimated values. We apply BSI to in-class examples of finite- and infinite-order Markov processes, as well to an out-of-class, infinite-state hidden process.

  10. Hidden Markov Model for Stock Selection

    Directory of Open Access Journals (Sweden)

    Nguyet Nguyen

    2015-10-01

    Full Text Available The hidden Markov model (HMM is typically used to predict the hidden regimes of observation data. Therefore, this model finds applications in many different areas, such as speech recognition systems, computational molecular biology and financial market predictions. In this paper, we use HMM for stock selection. We first use HMM to make monthly regime predictions for the four macroeconomic variables: inflation (consumer price index (CPI, industrial production index (INDPRO, stock market index (S&P 500 and market volatility (VIX. At the end of each month, we calibrate HMM’s parameters for each of these economic variables and predict its regimes for the next month. We then look back into historical data to find the time periods for which the four variables had similar regimes with the forecasted regimes. Within those similar periods, we analyze all of the S&P 500 stocks to identify which stock characteristics have been well rewarded during the time periods and assign scores and corresponding weights for each of the stock characteristics. A composite score of each stock is calculated based on the scores and weights of its features. Based on this algorithm, we choose the 50 top ranking stocks to buy. We compare the performances of the portfolio with the benchmark index, S&P 500. With an initial investment of $100 in December 1999, over 15 years, in December 2014, our portfolio had an average gain per annum of 14.9% versus 2.3% for the S&P 500.

  11. Hidden ion population of the magnetosphere

    International Nuclear Information System (INIS)

    Olsen, R.C.

    1982-01-01

    Particle data from two geosynchronous satellites (Applied Technology Satellite 6 and SCATHA) show a normally hidden ion population appearing when the satellites are in the earth's shadow. Ion and electron data show the spacecraft potential dropping from +10 V in sunlight to +4 and +5 V in eclipse at local midnight, in low-energy (T/sub e/ -2 ), isotropic ion population appears which was invisible in sunlight because of the larger positive spacecraft potential. Higher-energy populations generally cover the tails of the hidden ion populations, so they cannot be inferred from daylight data. The isotropic populations appears only in a few percent of the spacecraft eclipse events, appearing only at times of low Kp (2 or less, preceded by a day with Σ Kp< or =20). A low-energy (T = 1--2 eV) field-aligned population often appears with and without the isotropic population, at slightly higher flux levels. These fluxes are visible in sunlight, but again the distribution functions obtained in eclipse differ from those that would be inferred from daylight data. Measurement of the thermal plasma population on a consistent basis, particularly in the plasma sheet, will require some method of controlling the detector potential with respect to the ambient plamsa

  12. Epitope discovery with phylogenetic hidden Markov models.

    LENUS (Irish Health Repository)

    Lacerda, Miguel

    2010-05-01

    Existing methods for the prediction of immunologically active T-cell epitopes are based on the amino acid sequence or structure of pathogen proteins. Additional information regarding the locations of epitopes may be acquired by considering the evolution of viruses in hosts with different immune backgrounds. In particular, immune-dependent evolutionary patterns at sites within or near T-cell epitopes can be used to enhance epitope identification. We have developed a mutation-selection model of T-cell epitope evolution that allows the human leukocyte antigen (HLA) genotype of the host to influence the evolutionary process. This is one of the first examples of the incorporation of environmental parameters into a phylogenetic model and has many other potential applications where the selection pressures exerted on an organism can be related directly to environmental factors. We combine this novel evolutionary model with a hidden Markov model to identify contiguous amino acid positions that appear to evolve under immune pressure in the presence of specific host immune alleles and that therefore represent potential epitopes. This phylogenetic hidden Markov model provides a rigorous probabilistic framework that can be combined with sequence or structural information to improve epitope prediction. As a demonstration, we apply the model to a data set of HIV-1 protein-coding sequences and host HLA genotypes.

  13. Pentaquarks with hidden charm as hadroquarkonia

    Energy Technology Data Exchange (ETDEWEB)

    Eides, Michael I. [University of Kentucky, Department of Physics and Astronomy, Lexington, KY (United States); Petersburg Nuclear Physics Institute, St. Petersburg (Russian Federation); Petrov, Victor Yu. [Petersburg Nuclear Physics Institute, St. Petersburg (Russian Federation); Polyakov, Maxim V. [Petersburg Nuclear Physics Institute, St. Petersburg (Russian Federation); Ruhr-Universitaet Bochum, Institut fuer Theoretische Physik II, Bochum (Germany)

    2018-01-15

    We consider hidden charm pentaquarks as hadroquarkonium states in a QCD inspired approach. Pentaquarks arise naturally as bound states of quarkonia excitations and ordinary baryons. The LHCb P{sub c}(4450) pentaquark is interpreted as a ψ{sup '}-nucleon bound state with spin-parity J{sup P} = 3/2{sup -}. The partial decay width Γ(P{sub c}(4450) → J/ψ + N) ∼ 11 MeV is calculated and turned out to be in agreement with the experimental data for P{sub c}(4450). The P{sub c}(4450) pentaquark is predicted to be a member of one of the two almost degenerate hidden-charm baryon octets with spin-parities J{sup P} = 1/2{sup -}, 3/2{sup -}. The masses and decay widths of the octet pentaquarks are calculated. The widths are small and comparable with the width of the P{sub c}(4450) pentaquark, and the masses of the octet pentaquarks satisfy the Gell-Mann-Okubo relation. Interpretation of pentaquarks as loosely bound Σ{sub c} anti D* and Σ{sub c}{sup *} anti D* deuteronlike states is also considered. We determine quantum numbers of these bound states and calculate their masses in the one-pion exchange scenario. The hadroquarkonium and molecular approaches to exotic hadrons are compared and the relative advantages and drawbacks of each approach are discussed. (orig.)

  14. Low energy theorems of hidden local symmetries

    International Nuclear Information System (INIS)

    Harada, Masayasu; Kugo, Taichiro; Yamawaki, Koichi.

    1994-01-01

    We prove to all orders of the loop expansion the low energy theorems of hidden local symmetries in four-dimensional nonlinear sigma models based on the coset space G/H, with G and H being arbitrary compact groups. Although the models are non-renormalizable, the proof is done in an analogous manner to the renormalization proof of gauge theories and two-dimensional nonlinear sigma models by restricting ourselves to the operators with two derivatives (counting a hidden gauge boson field as one derivative), i.e., with dimension 2, which are the only operators relevant to the low energy limit. Through loop-wise mathematical induction based on the Ward-Takahashi identity for the BRS symmetry, we solve renormalization equation for the effective action up to dimension-2 terms plus terms with the relevant BRS sources. We then show that all the quantum corrections to the dimension-2 operators, including the finite parts as well as the divergent ones, can be entirely absorbed into a re-definition (renormalization) of the parameters and the fields in the dimension-2 part of the tree-level Lagrangian. (author)

  15. Black holes, hidden symmetries, and complete integrability.

    Science.gov (United States)

    Frolov, Valeri P; Krtouš, Pavel; Kubizňák, David

    2017-01-01

    The study of higher-dimensional black holes is a subject which has recently attracted vast interest. Perhaps one of the most surprising discoveries is a realization that the properties of higher-dimensional black holes with the spherical horizon topology and described by the Kerr-NUT-(A)dS metrics are very similar to the properties of the well known four-dimensional Kerr metric. This remarkable result stems from the existence of a single object called the principal tensor. In our review we discuss explicit and hidden symmetries of higher-dimensional Kerr-NUT-(A)dS black hole spacetimes. We start with discussion of the Killing and Killing-Yano objects representing explicit and hidden symmetries. We demonstrate that the principal tensor can be used as a "seed object" which generates all these symmetries. It determines the form of the geometry, as well as guarantees its remarkable properties, such as special algebraic type of the spacetime, complete integrability of geodesic motion, and separability of the Hamilton-Jacobi, Klein-Gordon, and Dirac equations. The review also contains a discussion of different applications of the developed formalism and its possible generalizations.

  16. Increased fibroblast functionality on CNN2-loaded titania nanotubes

    Directory of Open Access Journals (Sweden)

    Wei HB

    2012-02-01

    Full Text Available Hongbo Wei*, Shuyi Wu*, Zhihong Feng, Wei Zhou, Yan Dong, Guofeng Wu, Shizhu Bai, Yimin Zhao Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China *These authors contributed equally to this workAbstract: Infection and epithelial downgrowth are major problems associated with maxillofacial percutaneous implants. These complications are mainly due to the improper closure of the implant–skin interface. Therefore, designing a percutaneous implant that better promotes the formation of a stable soft tissue biologic seal around percutaneous sites is highly desirable. Additionally, the fibroblast has been proven to play an important role in the formation of biologic seals. In this study, titania nanotubes were filled with 11.2 kDa C-terminal CCN2 (connective tissue growth factor fragment, which could exert full CCN2 activity to increase the biological functionality of fibroblasts. This drug delivery system was fabricated on a titanium implant surface. CCN2 was loaded into anodized titania nanotubes using a simplified lyophilization method and the loading efficiency was approximately 80%. Then, the release kinetics of CCN2 from these nanotubes was investigated. Furthermore, the influence of CCN2-loaded titania nanotubes on fibroblast functionality was examined. The results revealed increased fibroblast adhesion at 0.25, 0.5, 1, 2, 4, and 24 hours, increased fibroblast viability over the course of 5 days, as well as enhanced actin cytoskeleton organization on CCN2-loaded titania nanotubes surfaces compared to uncoated, unmodified counterparts. Therefore, the results from this in vitro study demonstrate that CCN2-loaded titania nanotubes have the ability to increase fibroblast functionality and should be further studied as a method of promoting the formation of a stable soft tissue biologic seal around percutaneous sites.Keywords: anodization, titania nanotubes, adhesion, connective

  17. Carbon Nanotube Underwater Acoustic Thermophone

    Science.gov (United States)

    2016-09-23

    nanotubes (unless encapsulated or housed) are quite fragile and are susceptible to disintegration especially if the nanotubes are touched or moved too...The acoustic impedance (defined as the product of material density and sound speed) of the top shell 12 should match the Attorney Docket No. 300009

  18. Effects of doped copper on electrochemical performance of the raw carbon nanotubes anode

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhanhong; Simard, Benoit [SIMS, National Research Council, 100 Sussex Dr., Ottawa, ON (Canada); Li, Zaifeng [ICPET, National Research Council, 1200 Montreal Road, Ottawa, ON (Canada); Wu, Haoqing [Department of Chemistry, Fudan University, Shanghai 200433 (China)

    2003-07-01

    The raw carbon nanotubes pre-doped with copper are used as anode materials for lithium ion batteries. Constant current discharge and charge tests using the raw carbon nanotubes pre-doped with copper as Li{sup +} storage compounds show lower specific capacities than that of the acid-oxidized carbon nanotubes. The acids play an important role; H{sub 2}SO{sub 4} and HNO{sub 3} can easily permeate through the graphene sheets, then they will make the defects or pores in the graphene sheets, and this reaction can make the expansion of the graphite. Meanwhile, Cu{sup 2+} will diffuse into the pores and onto the outer surfaces of the carbon nanotubes. Cu{sup 2+} can be easily turned into Cu at high temperature in the presence of the carbon nanomaterial. So parts of the pores and the surfaces of the carbon nanotubes will be filled with the Cu atom. Once the space positions of the nanotubes were occupied, lithium cannot intercalate into the pores and onto the outer surface of the carbon nanotubes, thus the doped carbon nanotubes will have a low specific capacity.

  19. Tuning porosity and radial mechanical properties of DNA origami nanotubes via crossover design

    Science.gov (United States)

    Ma, Zhipeng; Kawai, Kentaro; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu

    2017-06-01

    DNA origami nanotubes are utilized as structural platforms for the fabrication of various micro/nanosystems for drug delivery, optical or biological sensing, and even nanoscale robots. Their radial structural and mechanical properties, which play a crucial role in the effective use of micro/nanosystems, have not been fully studied. In particular, the effects of crossovers, which are basic structures for rationally assembling double-stranded DNA (dsDNA) helices into a nanotube configuration, have not yet been characterized experimentally. To investigate the effects of crossovers on the porosity and the radial mechanical properties of DNA origami nanotubes, we fabricated a DNA origami nanotube with varied crossover designs along the nanotube axis. The radial geometry of the DNA origami nanotube is experimentally characterized by both atomic force microscopy (AFM) and electron cryomicroscopy (cryo-EM). Moreover, the radial mechanical properties of the DNA origami nanotube including the radial modulus are directly measured by force-distance-based AFM. These measurements reveal that the porosity and the radial modulus of DNA origami nanotubes can be tuned by adjusting the crossover design, which enables the optimal design and construction of DNA origami nanostructures for various applications.

  20. Sonochemical optimization of the conductivity of single wall nanotube networks

    NARCIS (Netherlands)

    Kaempgen, M.; Lebert, M.; Haluska, M.; Nicoloso, N.; Roth, S.

    2008-01-01

    Networks of single-wall carbon nanotubes (SWCNTs) are covalently functionalized with oxygen-containing groups. In lower concentration, these functional groups act as stable dopands improving the conductivity of the SWCNT material. In higher concentration however, their role as defects with a certain

  1. An introduction to hidden Markov models for biological sequences

    DEFF Research Database (Denmark)

    Krogh, Anders Stærmose

    1998-01-01

    A non-matematical tutorial on hidden Markov models (HMMs) plus a description of one of the applications of HMMs: gene finding.......A non-matematical tutorial on hidden Markov models (HMMs) plus a description of one of the applications of HMMs: gene finding....

  2. Asymptotics for Estimating Equations in Hidden Markov Models

    DEFF Research Database (Denmark)

    Hansen, Jørgen Vinsløv; Jensen, Jens Ledet

    Results on asymptotic normality for the maximum likelihood estimate in hidden Markov models are extended in two directions. The stationarity assumption is relaxed, which allows for a covariate process influencing the hidden Markov process. Furthermore a class of estimating equations is considered...

  3. Secret Codes: The Hidden Curriculum of Semantic Web Technologies

    Science.gov (United States)

    Edwards, Richard; Carmichael, Patrick

    2012-01-01

    There is a long tradition in education of examination of the hidden curriculum, those elements which are implicit or tacit to the formal goals of education. This article draws upon that tradition to open up for investigation the hidden curriculum and assumptions about students and knowledge that are embedded in the coding undertaken to facilitate…

  4. Searching for hidden sector in multiparticle production at LHC

    Directory of Open Access Journals (Sweden)

    Miguel-Angel Sanchis-Lozano

    2016-03-01

    Full Text Available We study the impact of a hidden sector beyond the Standard Model, e.g. a Hidden Valley model, on factorial moments and cumulants of multiplicity distributions in multiparticle production with a special emphasis on the prospects for LHC results.

  5. Hidden Agendas in Marriage: Affective and Longitudinal Dimensions.

    Science.gov (United States)

    Krokoff, Lowell J.

    1990-01-01

    Examines how couples' discussions of troublesome problems reveal hidden agendas (issues not directly discussed or explored). Finds disgust and contempt are at the core of both love and respect agendas for husbands and wives. Finds that wives' more than husbands' hidden agendas are directly predictive of how negatively they argue at home. (SR)

  6. Hidden symmetries in minimal five-dimensional supergravity

    International Nuclear Information System (INIS)

    Poessel, Markus; Silva, Sebastian

    2004-01-01

    We study the hidden symmetries arising in the dimensional reduction of d=5, N=2 supergravity to three dimensions. Extending previous partial results for the bosonic part, we give a derivation that includes fermionic terms, shedding light on the appearance of the local hidden symmetry SO(4) in the reduction

  7. Finite-gap twists of carbon nanotubes and an emergent hidden supersymmetry

    Czech Academy of Sciences Publication Activity Database

    Correa, F.; Jakubský, Vít

    2013-01-01

    Roč. 87, č. 8 (2013), 085019 ISSN 1550-7998 R&D Projects: GA AV ČR GPP203/11/P038 Institutional support: RVO:61389005 Keywords : condensed matter * nanostructures * supersymmetry Subject RIV: BE - Theoretical Physics Impact factor: 4.864, year: 2013 http://prd.aps.org/pdf/PRD/v87/i8/e085019

  8. The mechanism of selective molecular capture in carbon nanotube networks.

    Science.gov (United States)

    Wan, Yu; Guan, Jun; Yang, Xudong; Zheng, Quanshui; Xu, Zhiping

    2014-07-28

    Recently, air pollution issues have drawn significant attention to the development of efficient air filters, and one of the most promising materials for this purpose is nanofibers. We explore here the mechanism of selective molecular capture of volatile organic compounds in carbon nanotube networks by performing atomistic simulations. The results are discussed with respect to the two key parameters that define the performance of nanofiltration, i.e. the capture efficiency and flow resistance, which demonstrate the advantages of carbon nanotube networks with high surface-to-volume ratio and atomistically smooth surfaces. We also reveal the important roles of interfacial adhesion and diffusion that govern selective gas transport through the network.

  9. Stability and signatures of biexcitons in carbon nanotubes

    DEFF Research Database (Denmark)

    Pedersen, Thomas Garm; Pedersen, Kjeld; Cornean, Horia Decebal

    2005-01-01

    The linear optical properties of semiconducting carbon nanotubes are dominated by quasi-one-dimensional excitons formed by single electron-hole pairs. Hence, the nonlinear response at high pump levels most likely leads to the formation of exciton complexes involving several electron-hole pairs....... Such complexes would threfore play an important role in e.g. lasing applications. We demonstrate here that the biexciton complex is surprisingly stable for nanotubes in a wide diameter range. Theoretical predictions for the signature of such states in pump-probe spectroscopy are presented....

  10. Synthesis of copper sulfide nanotube in the hydrogel system

    International Nuclear Information System (INIS)

    Tan Changhui; Zhu Yulan; Lu Ran; Xue Pengchong; Bao Chunyan; Liu Xinli; Fei Zhuping; Zhao Yingying

    2005-01-01

    This paper presents a novel method for the preparation of copper sulfide (CuS) nanotubes using hydrogel based on N-lauroylalanine as template under mild condition. The resulting samples are examined by transmission electron microscopy (TEM) FT-IR spectroscopy, X-ray powder diffraction (XRD), UV-vis absorption spectroscopy. It is found that the intermolecular hydrogen bonds play an important role on the formation of the hydrogel and the Cu 2+ coordination gel. The formation process of CuS nanotube is also discussed

  11. Physical removal of metallic carbon nanotubes from nanotube network devices using a thermal and fluidic process

    International Nuclear Information System (INIS)

    Ford, Alexandra C; Shaughnessy, Michael; Wong, Bryan M; Kane, Alexander A; Krafcik, Karen L; Léonard, François; Kuznetsov, Oleksandr V; Billups, W Edward; Hauge, Robert H

    2013-01-01

    Electronic and optoelectronic devices based on thin films of carbon nanotubes are currently limited by the presence of metallic nanotubes. Here we present a novel approach based on nanotube alkyl functionalization to physically remove the metallic nanotubes from such network devices. The process relies on preferential thermal desorption of the alkyls from the semiconducting nanotubes and the subsequent dissolution and selective removal of the metallic nanotubes in chloroform. The approach is versatile and is applied to devices post-fabrication. (paper)

  12. Carbon Nanotubes and Modern Nanoagriculture

    KAUST Repository

    Serag, Maged F.

    2015-01-27

    Since their discovery, carbon nanotubes have been prominent members of the nanomaterial family. Owing to their extraordinary physical, chemical, and mechanical properties, carbon nanotubes have been proven to be a useful tool in the field of plant science. They were frequently perceived to bring about valuable biotechnological and agricultural applications that still remain beyond experimental realization. An increasing number of studies have demonstrated the ability of carbon nanotubes to traverse different plant cell barriers. These studies, also, assessed the toxicity and environmental impacts of these nanomaterials. The knowledge provided by these studies is of practical and fundamental importance for diverse applications including intracellular labeling and imaging, genetic transformation, and for enhancing our knowledge of plant cell biology. Although different types of nanoparticles have been found to activate physiological processes in plants, carbon nanotubes received particular interest. Following addition to germination medium, carbon nanotubes enhanced root growth and elongation of some plants such as onion, cucumber and rye-grass. They, also, modulated the expression of some genes that are essential for cell division and plant development. In addition, multi-walled carbon nanotubes were evidenced to penetrate thick seed coats, stimulate germination, and to enhance growth of young tomato seedlings. Multi-walled carbon nanotubes can penetrate deeply into the root system and further distribute into the leaves and the fruits. In recent studies, carbon nanotubes were reported to be chemically entrapped into the structure of plant tracheary elements. This should activate studies in the fields of plant defense and wood engineering. Although, all of these effects on plant physiology and plant developmental biology have not been fully understood, the valuable findings promises more research activity in the near future toward complete scientific understanding of

  13. Abelian hidden sectors at a GeV

    International Nuclear Information System (INIS)

    Morrissey, David E.; Poland, David; Zurek, Kathryn M.

    2009-01-01

    We discuss mechanisms for naturally generating GeV-scale hidden sectors in the context of weak-scale supersymmetry. Such low mass scales can arise when hidden sectors are more weakly coupled to supersymmetry breaking than the visible sector, as happens when supersymmetry breaking is communicated to the visible sector by gauge interactions under which the hidden sector is uncharged, or if the hidden sector is sequestered from gravity-mediated supersymmetry breaking. We study these mechanisms in detail in the context of gauge and gaugino mediation, and present specific models of Abelian GeV-scale hidden sectors. In particular, we discuss kinetic mixing of a U(1) x gauge force with hypercharge, singlets or bi-fundamentals which couple to both sectors, and additional loop effects. Finally, we investigate the possible relevance of such sectors for dark matter phenomenology, as well as for low- and high-energy collider searches.

  14. Religion, Spirituality, and the Hidden Curriculum: Medical Student and Faculty Reflections.

    Science.gov (United States)

    Balboni, Michael J; Bandini, Julia; Mitchell, Christine; Epstein-Peterson, Zachary D; Amobi, Ada; Cahill, Jonathan; Enzinger, Andrea C; Peteet, John; Balboni, Tracy

    2015-10-01

    Religion and spirituality play an important role in physicians' medical practice, but little research has examined their influence within the socialization of medical trainees and the hidden curriculum. The objective is to explore the role of religion and spirituality as they intersect with aspects of medicine's hidden curriculum. Semiscripted, one-on-one interviews and focus groups (n = 33 respondents) were conducted to assess Harvard Medical School student and faculty experiences of religion/spirituality and the professionalization process during medical training. Using grounded theory, theme extraction was performed with interdisciplinary input (medicine, sociology, and theology), yielding a high inter-rater reliability score (kappa = 0.75). Three domains emerged where religion and spirituality appear as a factor in medical training. First, religion/spirituality may present unique challenges and benefits in relation to the hidden curriculum. Religious/spiritual respondents more often reported to struggle with issues of personal identity, increased self-doubt, and perceived medical knowledge inadequacy. However, religious/spiritual participants less often described relationship conflicts within the medical team, work-life imbalance, and emotional stress arising from patient suffering. Second, religion/spirituality may influence coping strategies during encounters with patient suffering. Religious/spiritual trainees described using prayer, faith, and compassion as means for coping whereas nonreligious/nonspiritual trainees discussed compartmentalization and emotional repression. Third, levels of religion/spirituality appear to fluctuate in relation to medical training, with many trainees experiencing an increase in religiousness/spirituality during training. Religion/spirituality has a largely unstudied but possibly influential role in medical student socialization. Future study is needed to characterize its function within the hidden curriculum. Copyright

  15. Flutter and divergence instability of supported piezoelectric nanotubes conveying fluid

    Science.gov (United States)

    Bahaadini, Reza; Hosseini, Mohammad; Jamali, Behnam

    2018-01-01

    In this paper, divergence and flutter instabilities of supported piezoelectric nanotubes containing flowing fluid are investigated. To take the size effects into account, the nonlocal elasticity theory is implemented in conjunction with the Euler-Bernoulli beam theory incorporating surface stress effects. The Knudsen number is applied to investigate the slip boundary conditions between the flow and wall of nanotube. The nonlocal governing equations of nanotube are obtained using Newtonian method, including the influence of piezoelectric voltage, surface effects, Knudsen number and nonlocal parameter. Applying Galerkin approach to transform resulting equations into a set of eigenvalue equations under the simple-simple (S-S) and clamped-clamped (C-C) boundary conditions. The effects of the piezoelectric voltage, surface effects, Knudsen number, nonlocal parameter and boundary conditions on the divergence and flutter boundaries of nanotubes are discussed. It is observed that the fluid-conveying nanotubes with both ends supported lose their stability by divergence first and then by flutter with increase in fluid velocity. Results indicate the importance of using piezoelectric voltage, nonlocal parameter and Knudsen number in decrease of critical flow velocities of system. Moreover, the surface effects have a significant role on the eigenfrequencies and critical fluid velocity.

  16. Kinetic Study on Channelling of Protons in Metallic Carbon Nanotubes

    International Nuclear Information System (INIS)

    Dan, Zhao; Yuan-Hong, Song; You-Nian, Wang

    2008-01-01

    Based on the kinetic model and the dielectric response theory, a theoretical model is put forward to describe the transport of protons along nanotube axes. With the introduction of electron band structure for different nanotubes like zigzag and armchair nanotubes of metallic properties, the collective excitation of electrons on the cylinders induced by the incident ions is studied, showing several distinct peaks in the curves of the energy loss function. Furthermore, the stopping power and the self-energy are calculated as functions of ion velocities, especially taking into account the influence of damping coefficients. It is conceivable from the results that, in the kinetic formulation, plasmon excitation plays a major role in the stopping. And as the damping increases, the peaks of the stopping power shift to the lower velocities, with the broadening of the plasmon resonance. (condensed matter: structure, mechanical and thermal properties)

  17. Carbon nanotubes: properties, synthesis, purification, and medical applications

    Science.gov (United States)

    2014-01-01

    Current discoveries of different forms of carbon nanostructures have motivated research on their applications in various fields. They hold promise for applications in medicine, gene, and drug delivery areas. Many different production methods for carbon nanotubes (CNTs) have been introduced; functionalization, filling, doping, and chemical modification have been achieved, and characterization, separation, and manipulation of individual CNTs are now possible. Parameters such as structure, surface area, surface charge, size distribution, surface chemistry, and agglomeration state as well as purity of the samples have considerable impact on the reactivity of carbon nanotubes. Otherwise, the strength and flexibility of carbon nanotubes make them of potential use in controlling other nanoscale structures, which suggests they will have a significant role in nanotechnology engineering. PMID:25170330

  18. Carbon nanotubes: properties, synthesis, purification, and medical applications

    Science.gov (United States)

    Eatemadi, Ali; Daraee, Hadis; Karimkhanloo, Hamzeh; Kouhi, Mohammad; Zarghami, Nosratollah; Akbarzadeh, Abolfazl; Abasi, Mozhgan; Hanifehpour, Younes; Joo, Sang Woo

    2014-08-01

    Current discoveries of different forms of carbon nanostructures have motivated research on their applications in various fields. They hold promise for applications in medicine, gene, and drug delivery areas. Many different production methods for carbon nanotubes (CNTs) have been introduced; functionalization, filling, doping, and chemical modification have been achieved, and characterization, separation, and manipulation of individual CNTs are now possible. Parameters such as structure, surface area, surface charge, size distribution, surface chemistry, and agglomeration state as well as purity of the samples have considerable impact on the reactivity of carbon nanotubes. Otherwise, the strength and flexibility of carbon nanotubes make them of potential use in controlling other nanoscale structures, which suggests they will have a significant role in nanotechnology engineering.

  19. Strain-modified RKKY interaction in carbon nanotubes

    DEFF Research Database (Denmark)

    Gorman, P. D.; Duffy, J. M.; Power, Stephen R.

    2015-01-01

    been shown that the interaction range depends on the conformation of the magnetic dopants in both graphene and nanotubes. Here we examine the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in carbon nanotubes in the presence of uniaxial strain for a range of different impurity configurations. We show......For low-dimensionalmetallic structures, such as nanotubes, the exchange coupling between localized magnetic dopants is predicted to decay slowly with separation. The long-range character of this interaction plays a significant role in determining the magnetic order of the system. It has previously...... that strain is capable of amplifying or attenuating the RKKY interaction, significantly increasing certain interaction ranges, and acting as a switch: effectively turning on or off the interaction. We argue that uniaxial strain can be employed to significantly manipulate magnetic interactions in carbon...

  20. Mapping the transition from catalyst-pool to bamboo-like growth-mechanism in vertically-aligned free-standing films of carbon nanotubes filled with Fe3C: The key role of water

    Directory of Open Access Journals (Sweden)

    Filippo S. Boi

    2016-08-01

    Full Text Available The control of carbon nanotube growth has challenged researchers for more than a decade due to the complex parameters-control necessary in the commonly used CVD approaches. Here we show that a direct transition from the catalyst-pool growth mechanism characterized by graphene-caps in the direction of growth to a bamboo-shaped mechanism characterized by the repetition of periodic elongated graphitic compartments is present when controlled quantities of water are added to ferrocene/dichlorobenzene. Our results suggest that water-addition allows enhancing the level of stress accumulated under the graphitic nanotubes-cap.

  1. Mapping the transition from catalyst-pool to bamboo-like growth-mechanism in vertically-aligned free-standing films of carbon nanotubes filled with Fe3C: The key role of water

    Science.gov (United States)

    Boi, Filippo S.; Wang, Shanling; He, Yi

    2016-08-01

    The control of carbon nanotube growth has challenged researchers for more than a decade due to the complex parameters-control necessary in the commonly used CVD approaches. Here we show that a direct transition from the catalyst-pool growth mechanism characterized by graphene-caps in the direction of growth to a bamboo-shaped mechanism characterized by the repetition of periodic elongated graphitic compartments is present when controlled quantities of water are added to ferrocene/dichlorobenzene. Our results suggest that water-addition allows enhancing the level of stress accumulated under the graphitic nanotubes-cap.

  2. Analysis of nanoparticles with an optical sensor based on carbon nanotubes

    Science.gov (United States)

    Stäb, J.; Furin, D.; Fechner, P.; Proll, G.; Soriano-Dotor, L. M.; Ruiz-Palomero, C.; Valcárcel, M.; Gauglitz, G.

    2017-05-01

    Nanomaterials play an important role in science and in every day products. This is due to their varied and specific properties, whereby especially engineered nanoparticles (ENPs) have shown various beneficial properties for a wide range of application in consumables (e.g. cosmetics, drinks, food and food packaging). Silver nanoparticles for instance are hidden in meat packaging materials or in deodorants. Reasons for this can be found in the antibacterial effect of silver, which leads to high applicability in consumer products. However, ENPs are under permanent discussion due to their unforeseen hazards and an unknown disposition in living organisms and the environment. So far, there is a lack of methods, which allows for the fast and effective characterization and quantification of such nanoparticles in complex matrices (e.g. creams, fruit juice), since matrix components can impede a specific detection of the analyte. It was the objective of project INSTANT to address this topic and compose a method to detect nanoparticles as a first step. Therefore, the development of a sensor system with an upstream sample preparation for the characterization and quantification of specific nanoparticles in complex matrices using a label free optical sensor array in combination with novel recognition elements was developed. The promising optical technology iRIfS (imaging reflectometric interference sensor) was used for this purpose. As a recognition element, functionalized carbon nanotubes can be effectively used. Owing to their excellent electronical, mechanical and chemical properties, CNTs have already been used for extracting ENPs from complex matrices as sorbent material by filtration. After successful immobilization of CNTs on microscope glass slides e.g. the detection of stabilized silver nanoparticles extracted by a sample preparation unit using the iRIfS technology was performed.

  3. Unveiling Hidden Social Design: New Roles for Sociologists

    Directory of Open Access Journals (Sweden)

    Popov Lubomir

    2017-06-01

    Full Text Available This paper will help foster a more favourable attitude to professional involvement in social design projects and highlight new areas of professional opportunity for sociologists. To overcome the psychological barriers to design engagement and to foster motivation for social design, the authors discuss a case of social design decision making by non-sociologists. The methodology is informed by Activity Theory and Design Theory, and the approach adopted is based on analyzing current best practices, departing from conventional and customary practices. The authors discuss the Fun Palace, which was an innovative architectural project in the 1960s Great Britain, conceived with a fundamental social aim of providing life-long education and professional retooling to working class people in a relaxed and entertaining environment. The paper highlights the sociological nature of decision making in the planning phase of the project as well as the need for sociological knowledge and skills. The explication of the social design activities in the Fun Palace project can inspire sociological practitioners with ideas about entering into various industries and, in particular, in the design of social organizations and buildings.

  4. Dynamic portfolio optimization across hidden market regimes

    DEFF Research Database (Denmark)

    Nystrup, Peter; Madsen, Henrik; Lindström, Erik

    2017-01-01

    Regime-based asset allocation has been shown to add value over rebalancing to static weights and, in particular, reduce potential drawdowns by reacting to changes in market conditions. The predominant approach in previous studies has been to specify in advance a static decision rule for changing...... the allocation based on the state of financial markets or the economy. In this article, model predictive control (MPC) is used to dynamically optimize a portfolio based on forecasts of the mean and variance of financial returns from a hidden Markov model with time-varying parameters. There are computational...... than a buy-and-hold investment in various major stock market indices. This is after accounting for transaction costs, with a one-day delay in the implementation of allocation changes, and with zero-interest cash as the only alternative to the stock indices. Imposing a trading penalty that reduces...

  5. Supersymmetric leptogenesis with a light hidden sector

    International Nuclear Information System (INIS)

    De Simone, Andrea

    2010-04-01

    Supersymmetric scenarios incorporating thermal leptogenesis as the origin of the observed matter-antimatter asymmetry generically predict abundances of the primordial elements which are in conflict with observations. In this paper we pro- pose a simple way to circumvent this tension and accommodate naturally ther- mal leptogenesis and primordial nucleosynthesis. We postulate the existence of a light hidden sector, coupled very weakly to the Minimal Supersymmetric Standard Model, which opens up new decay channels for the next-to-lightest supersymmetric particle, thus diluting its abundance during nucleosynthesis. We present a general model-independent analysis of this mechanism as well as two concrete realizations, and describe the relevant cosmological and astrophysical bounds and implications for this dark matter scenario. Possible experimental signatures at colliders and in cosmic-ray observations are also discussed. (orig.)

  6. Nuclear scissors modes and hidden angular momenta

    Energy Technology Data Exchange (ETDEWEB)

    Balbutsev, E. B., E-mail: balbuts@theor.jinr.ru; Molodtsova, I. V. [Joint Institute for Nuclear Research (Russian Federation); Schuck, P. [Université Paris-Sud, Institut de Physique Nucléaire, IN2P3–CNRS (France)

    2017-01-15

    The coupled dynamics of low-lying modes and various giant resonances are studied with the help of the Wigner Function Moments method generalized to take into account spin degrees of freedom and pair correlations simultaneously. The method is based on Time-Dependent Hartree–Fock–Bogoliubov equations. The model of the harmonic oscillator including spin–orbit potential plus quadrupole–quadrupole and spin–spin interactions is considered. New low-lying spin-dependent modes are analyzed. Special attention is paid to the scissors modes. A new source of nuclear magnetism, connected with counter-rotation of spins up and down around the symmetry axis (hidden angular momenta), is discovered. Its inclusion into the theory allows one to improve substantially the agreement with experimental data in the description of energies and transition probabilities of scissors modes.

  7. Neuroevolution Mechanism for Hidden Markov Model

    Directory of Open Access Journals (Sweden)

    Nabil M. Hewahi

    2011-12-01

    Full Text Available Hidden Markov Model (HMM is a statistical model based on probabilities. HMM is becoming one of the major models involved in many applications such as natural language
    processing, handwritten recognition, image processing, prediction systems and many more. In this research we are concerned with finding out the best HMM for a certain application domain. We propose a neuroevolution process that is based first on converting the HMM to a neural network, then generating many neural networks at random where each represents a HMM. We proceed by
    applying genetic operators to obtain new set of neural networks where each represents HMMs, and updating the population. Finally select the best neural network based on a fitness function.

  8. Improved hidden Markov model for nosocomial infections.

    Science.gov (United States)

    Khader, Karim; Leecaster, Molly; Greene, Tom; Samore, Matthew; Thomas, Alun

    2014-12-01

    We propose a novel hidden Markov model (HMM) for parameter estimation in hospital transmission models, and show that commonly made simplifying assumptions can lead to severe model misspecification and poor parameter estimates. A standard HMM that embodies two commonly made simplifying assumptions, namely a fixed patient count and binomially distributed detections is compared with a new alternative HMM that does not require these simplifying assumptions. Using simulated data, we demonstrate how each of the simplifying assumptions used by the standard model leads to model misspecification, whereas the alternative model results in accurate parameter estimates. © The Authors 2013. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

  9. The elliptic genus and Hidden symmetry

    International Nuclear Information System (INIS)

    Jaffe, A.

    2001-01-01

    We study the elliptic genus (a partition function) in certain interacting, twist quantum field theories. Without twists, these theories have N=2 supersymmetry. The twists provide a regularization, and also partially break the supersymmetry. In spite of the regularization, one can establish a homotopy of the elliptic genus in a coupling parameter. Our construction relies on a priori estimates and other methods from constructive quantum field theory; this mathematical underpinning allows us to justify evaluating the elliptic genus at one endpoint of the homotopy. We obtain a version of Witten's proposed formula for the elliptic genus in terms of classical theta functions. As a consequence, the elliptic genus has a hidden SL(2,Z) symmetry characteristic of conformal theory, even though the underlying theory is not conformal. (orig.)

  10. Hidden conformal symmetry of extremal black holes

    International Nuclear Information System (INIS)

    Chen Bin; Long Jiang; Zhang Jiaju

    2010-01-01

    We study the hidden conformal symmetry of extremal black holes. We introduce a new set of conformal coordinates to write the SL(2,R) generators. We find that the Laplacian of the scalar field in many extremal black holes, including Kerr(-Newman), Reissner-Nordstrom, warped AdS 3 , and null warped black holes, could be written in terms of the SL(2,R) quadratic Casimir. This suggests that there exist dual conformal field theory (CFT) descriptions of these black holes. From the conformal coordinates, the temperatures of the dual CFTs could be read directly. For the extremal black hole, the Hawking temperature is vanishing. Correspondingly, only the left (right) temperature of the dual CFT is nonvanishing, and the excitations of the other sector are suppressed. In the probe limit, we compute the scattering amplitudes of the scalar off the extremal black holes and find perfect agreement with the CFT prediction.

  11. Exact solution of the hidden Markov processes

    Science.gov (United States)

    Saakian, David B.

    2017-11-01

    We write a master equation for the distributions related to hidden Markov processes (HMPs) and solve it using a functional equation. Thus the solution of HMPs is mapped exactly to the solution of the functional equation. For a general case the latter can be solved only numerically. We derive an exact expression for the entropy of HMPs. Our expression for the entropy is an alternative to the ones given before by the solution of integral equations. The exact solution is possible because actually the model can be considered as a generalized random walk on a one-dimensional strip. While we give the solution for the two second-order matrices, our solution can be easily generalized for the L values of the Markov process and M values of observables: We should be able to solve a system of L functional equations in the space of dimension M -1 .

  12. The mechanisms for filling carbon nanotubes with molten salts: carbon nanotubes as energy landscape filters

    International Nuclear Information System (INIS)

    Bishop, Clare L; Wilson, Mark

    2009-01-01

    The mechanisms for filling carbon nanotubes with molten salts are investigated using molecular dynamics computer simulation. Inorganic nanotubular structures, whose morphologies can be rationalized in terms of the folding, or the removal of sections from, planes of square nets are found to form. The formation mechanisms are found to follow a 'chain-by-chain' motif in which the structures build systematically from charge neutral M-X-M-Xc chains. The formation mechanisms are rationalized in terms of the ion-ion interactions (intra-chain and inter-chain terms). In addition, the mechanisms of filling are discussed in terms of a 'hopping' between basins on the underlying energy landscape. The role of the carbon nanotube as an energy landscape filter is discussed.

  13. Beyond the hidden curriculum: The challenging search for authentic values in medical ethics education

    Directory of Open Access Journals (Sweden)

    Gerald Ssebunnya

    2013-11-01

    Full Text Available Since the practice of medicine is a moral enterprise, medical ethics education aims to produce ‘good’ doctors who are capable of self-reflective discernment of the many values at play in the clinical encounter, and of re-affirming the patient’s human dignity. However, the caring and compassionate physician envisaged as the end-product of medical ethics curricula evidently remains elusive. I argue that this apparent failure of medical ethics education is traceable to a systematic de-emphasis of humanistic values since the pioneering stages of formal medical ethics curricula. The idea of ‘the hidden curriculum’ connotes a distinctive value-laden medical morality that is transmissible through socialisation and role-modelling in the medical school moral ecosystem. Further, the hidden curriculum is hampered by the challenging medical school workload, bad role models, and lack of appropriate evaluation and assessment methods, as well as the lack of consensus in bioethics on the key concept of human dignity. Properly conceived, the dignity of the human person is the ultimate source of human values. Optimising the hidden curriculum, therefore, demands an authentic and comprehensive enquiry into the concept of human dignity, as well as the nature of the human person, the true human good and what constitutes the unitary good of the patient.

  14. Social exclusion, health and hidden homelessness.

    Science.gov (United States)

    Watson, J; Crawley, J; Kane, D

    2016-10-01

    Homelessness and poverty are extreme forms of social exclusion which extend beyond the lack of physical or material needs. The purpose of this study was to explore and expand the concept of social exclusion within the social determinants of health perspective - to understand how the social environment, health behaviours and health status are associated with material and social deprivation. Fundamental qualitative description with tones of focused ethnography. Participants who identified as hidden homeless described their everyday living conditions and how these everyday conditions were impacted and influenced by their social environments, coping/health behaviours and current health status. Research Ethics Board approval was granted and informed consents were obtained from 21 participants prior to the completion of individual interviews. Qualitative content analysis examined the descriptions of men and women experiencing hidden homelessness. Participants described the 'lack of quality social interactions and supports' and their 'daily struggles of street life'. They also shared the 'pain of addiction' and how coping strategies influenced health. Participants were hopeful that their insights would 'better the health of homeless people' by helping shape public policy and funding of community resources that would reduce barriers and improve overall health. Health professionals who understand health behaviours as coping mechanisms for poor quality social environments can provide more comprehensive and holistic care. The findings of this study can be used to support the importance of housing as a key factor in the health and well-being of people experiencing poverty, homelessness and social exclusion; and consequently, reinforces the need for a national housing strategy. Copyright © 2016 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

  15. The hidden curriculum in undergraduate medical education: qualitative study of medical students' perceptions of teaching.

    Science.gov (United States)

    Lempp, Heidi; Seale, Clive

    2004-10-02

    To study medical students' views about the quality of the teaching they receive during their undergraduate training, especially in terms of the hidden curriculum. Semistructured interviews with individual students. One medical school in the United Kingdom. 36 undergraduate medical students, across all stages of their training, selected by random and quota sampling, stratified by sex and ethnicity, with the whole medical school population as a sampling frame. Medical students' experiences and perceptions of the quality of teaching received during their undergraduate training. Students reported many examples of positive role models and effective, approachable teachers, with valued characteristics perceived according to traditional gendered stereotypes. They also described a hierarchical and competitive atmosphere in the medical school, in which haphazard instruction and teaching by humiliation occur, especially during the clinical training years. Following on from the recent reforms of the manifest curriculum, the hidden curriculum now needs attention to produce the necessary fundamental changes in the culture of undergraduate medical education.

  16. Carbon Nanotube Based Molecular Electronics

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1998-01-01

    Carbon nanotubes and the nanotube heterojunctions have recently emerged as excellent candidates for nanoscale molecular electronic device components. Experimental measurements on the conductivity, rectifying behavior and conductivity-chirality correlation have also been made. While quasi-one dimensional simple heterojunctions between nanotubes with different electronic behavior can be generated by introduction of a pair of heptagon-pentagon defects in an otherwise all hexagon graphene sheet. Other complex 3- and 4-point junctions may require other mechanisms. Structural stability as well as local electronic density of states of various nanotube junctions are investigated using a generalized tight-binding molecular dynamics (GDBMD) scheme that incorporates non-orthogonality of the orbitals. The junctions investigated include straight and small angle heterojunctions of various chiralities and diameters; as well as more complex 'T' and 'Y' junctions which do not always obey the usual pentagon-heptagon pair rule. The study of local density of states (LDOS) reveal many interesting features, most prominent among them being the defect-induced states in the gap. The proposed three and four pointjunctions are one of the smallest possible tunnel junctions made entirely of carbon atoms. Furthermore the electronic behavior of the nanotube based device components can be taylored by doping with group III-V elements such as B and N, and BN nanotubes as a wide band gap semiconductor has also been realized in experiments. Structural properties of heteroatomic nanotubes comprising C, B and N will be discussed.

  17. Modeling the Effects of Interfacial Characteristics on Gas Permeation Behavior of Nanotube-Mixed Matrix Membranes.

    Science.gov (United States)

    Chehrazi, Ehsan; Sharif, Alireza; Omidkhah, Mohammadreza; Karimi, Mohammad

    2017-10-25

    Theoretical approaches that accurately predict the gas permeation behavior of nanotube-containing mixed matrix membranes (nanotube-MMMs) are scarce. This is mainly due to ignoring the effects of nanotube/matrix interfacial characteristics in the existing theories. In this paper, based on the analogy of thermal conduction in polymer composites containing nanotubes, we develop a model to describe gas permeation through nanotube-MMMs. Two new parameters, "interfacial thickness" (a int ) and "interfacial permeation resistance" (R int ), are introduced to account for the role of nanotube/matrix interfacial interactions in the proposed model. The obtained values of a int , independent of the nature of the permeate gas, increased by increasing both the nanotubes aspect ratio and polymer-nanotube interfacial strength. An excellent correlation between the values of a int and polymer-nanotube interaction parameters, χ, helped to accurately reproduce the existing experimental data from the literature without the need to resort to any adjustable parameter. The data includes 10 sets of CO 2 /CH 4 permeation, 12 sets of CO 2 /N 2 permeation, 3 sets of CO 2 /O 2 permeation, and 2 sets of CO 2 /H 2 permeation through different nanotube-MMMs. Moreover, the average absolute relative errors between the experimental data and the predicted values of the proposed model are very small (less than 5%) in comparison with those of the existing models in the literature. To the best of our knowledge, this is the first study where such a systematic comparison between model predictions and such extensive experimental data is presented. Finally, the new way of assessing gas permeation data presented in the current work would be a simple alternative to complex approaches that are usually utilized to estimate interfacial thickness in polymer composites.

  18. Adaptive filtering for hidden node detection and tracking in networks.

    Science.gov (United States)

    Hamilton, Franz; Setzer, Beverly; Chavez, Sergio; Tran, Hien; Lloyd, Alun L

    2017-07-01

    The identification of network connectivity from noisy time series is of great interest in the study of network dynamics. This connectivity estimation problem becomes more complicated when we consider the possibility of hidden nodes within the network. These hidden nodes act as unknown drivers on our network and their presence can lead to the identification of false connections, resulting in incorrect network inference. Detecting the parts of the network they are acting on is thus critical. Here, we propose a novel method for hidden node detection based on an adaptive filtering framework with specific application to neuronal networks. We consider the hidden node as a problem of missing variables when model fitting and show that the estimated system noise covariance provided by the adaptive filter can be used to localize the influence of the hidden nodes and distinguish the effects of different hidden nodes. Additionally, we show that the sequential nature of our algorithm allows for tracking changes in the hidden node influence over time.

  19. Tunable synthesis of copper nanotubes

    International Nuclear Information System (INIS)

    Kaniukov, E; Yakimchuk, D; Kozlovsky, A; Shlimas, D; Zdorovets, M; Kadyrzhanov, K

    2016-01-01

    Simple method of tunable synthesis of copper nanotubes based on template synthesis was developed. A comprehensive study of the structural, morphological and electrical characteristics of the obtained nanostructures was carried out. Characterization of structural features was made by methods of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry analysis. Evaluation of wall thickness is made by methods of gas permeability. Electrical conductivity of nanotubes was define in the study of their current-voltage characteristics. The possibility to control of copper nanotubes physical properties by variation of the deposition parameters was shown. (paper)

  20. Multiscale Modeling with Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, A

    2006-02-21

    Technologically important nanomaterials come in all shapes and sizes. They can range from small molecules to complex composites and mixtures. Depending upon the spatial dimensions of the system and properties under investigation computer modeling of such materials can range from equilibrium and nonequilibrium Quantum Mechanics, to force-field-based Molecular Mechanics and kinetic Monte Carlo, to Mesoscale simulation of evolving morphology, to Finite-Element computation of physical properties. This brief review illustrates some of the above modeling techniques through a number of recent applications with carbon nanotubes: nano electromechanical sensors (NEMS), chemical sensors, metal-nanotube contacts, and polymer-nanotube composites.

  1. Fabrication of titanium dioxide nanotube arrays using organic electrolytes

    Science.gov (United States)

    Yoriya, Sorachon

    This dissertation focuses on fabrication and improvement of morphological features of TiO2 nanotube arrays in the selected organic electrolytes including dimethyl sulfoxide (DMSO; see Chapter 4) and diethylene glycol (DEG; see Chapter 5). Using a polar dimethyl sulfoxide containing hydrofluoric acid, the vertically oriented TiO2 nanotube arrays with well controlled morphologies, i.e. tube lengths ranging from few microns up to 101 microm, pore diameters from 100 nm to 150 nm, and wall thicknesses from 15 nm to 50 nm were achieved. Various anodization variables including fluoride ion concentration, voltage, anodization time, water content, and reuse of the anodized electrolyte could be manipulated under proper conditions to control the nanotube array morphology. Anodization current behaviors associated with evolution of nanotube length were analyzed in order to clarify and better understand the formation mechanism of nanotubes grown in the organic electrolytes. Typically observed for DMSO electrolyte, the behavior that anodization current density gradually decreases with time is a reflection of a constant growth rate of nanotube arrays. Large fluctuation of anodization current was significantly observed probably due to the large change in electrolyte properties during anodization, when anodizing in high conductivity electrolytes such as using high HF concentration and reusing the anodized electrolyte as a second time. It is believed that the electrolyte properties such as conductivity and polarity play important role in affecting ion solvation and interactions in the solution consequently determining the formation of oxide film. Fabrication of the TiO2 nanotube array films was extended to study in the more viscous diethylene glycol (DEG) electrolyte. The arrayed nanotubes achieved from DEG electrolytes containing either HF or NH4 F are fully separated, freely self-standing structure with open pores and a wide variation of tube-to-tube spacing ranging from

  2. Multilayer Neural Networks with Extensively Many Hidden Units

    International Nuclear Information System (INIS)

    Rosen-Zvi, Michal; Engel, Andreas; Kanter, Ido

    2001-01-01

    The information processing abilities of a multilayer neural network with a number of hidden units scaling as the input dimension are studied using statistical mechanics methods. The mapping from the input layer to the hidden units is performed by general symmetric Boolean functions, whereas the hidden layer is connected to the output by either discrete or continuous couplings. Introducing an overlap in the space of Boolean functions as order parameter, the storage capacity is found to scale with the logarithm of the number of implementable Boolean functions. The generalization behavior is smooth for continuous couplings and shows a discontinuous transition to perfect generalization for discrete ones

  3. Update on hidden sectors with dark forces and dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Andreas, Sarah

    2012-11-15

    Recently there has been much interest in hidden sectors, especially in the context of dark matter and ''dark forces'', since they are a common feature of beyond standard model scenarios like string theory and SUSY and additionally exhibit interesting phenomenological aspects. Various laboratory experiments place limits on the so-called hidden photon and continuously further probe and constrain the parameter space; an updated overview is presented here. Furthermore, for several hidden sector models with light dark matter we study the viability with respect to the relic abundance and direct detection experiments.

  4. Hidden photon dark matter search with large metallic mirror

    International Nuclear Information System (INIS)

    Doebrich, Babette; Lindner, Axel; Daumiller, Kai; Engel, Ralph; Roth, Markus; Kowalski, Marek

    2014-10-01

    If Dark Matter is composed of hidden-sector photons that kinetically mix with photons of the visible sector, then Dark Matter has a tiny oscillating electric field component. Its presence would lead to a small amount of visible radiation being emitted from a conducting surface, with the photon frequency given approximately by the mass of the hidden photon. Here, we report on experimental efforts that have started recently to search for such hidden photon Dark Matter in the (sub-)eV regime with a prototype mirror for the Auger fluorescence detector at the Karlsruhe Institute for Technology.

  5. Naturally light hidden photons in LARGE volume string compactifications

    International Nuclear Information System (INIS)

    Goodsell, M.; Jaeckel, J.; Redondo, J.; Ringwald, A.

    2009-09-01

    Extra ''hidden'' U(1) gauge factors are a generic feature of string theory that is of particular phenomenological interest. They can kinetically mix with the Standard Model photon and are thereby accessible to a wide variety of astrophysical and cosmological observations and laboratory experiments. In this paper we investigate the masses and the kinetic mixing of hidden U(1)s in LARGE volume compactifications of string theory. We find that in these scenarios the hidden photons can be naturally light and that their kinetic mixing with the ordinary electromagnetic photon can be of a size interesting for near future experiments and observations. (orig.)

  6. Hidden Area and Mechanical Nonlinearities in Freestanding Graphene

    Science.gov (United States)

    Nicholl, Ryan J. T.; Lavrik, Nickolay V.; Vlassiouk, Ivan; Srijanto, Bernadeta R.; Bolotin, Kirill I.

    2017-06-01

    We investigated the effect of out-of-plane crumpling on the mechanical response of graphene membranes. In our experiments, stress was applied to graphene membranes using pressurized gas while the strain state was monitored through two complementary techniques: interferometric profilometry and Raman spectroscopy. By comparing the data obtained through these two techniques, we determined the geometric hidden area which quantifies the crumpling strength. While the devices with hidden area ˜0 % obeyed linear mechanics with biaxial stiffness 428 ±10 N /m , specimens with hidden area in the range 0.5%-1.0% were found to obey an anomalous nonlinear Hooke's law with an exponent ˜0.1 .

  7. Context Tree Estimation in Variable Length Hidden Markov Models

    OpenAIRE

    Dumont, Thierry

    2011-01-01

    We address the issue of context tree estimation in variable length hidden Markov models. We propose an estimator of the context tree of the hidden Markov process which needs no prior upper bound on the depth of the context tree. We prove that the estimator is strongly consistent. This uses information-theoretic mixture inequalities in the spirit of Finesso and Lorenzo(Consistent estimation of the order for Markov and hidden Markov chains(1990)) and E.Gassiat and S.Boucheron (Optimal error exp...

  8. Local models and hidden nonlocality in Quantum Theory

    OpenAIRE

    Guerini, Leonardo

    2014-01-01

    This Master's thesis has two central subjects: the simulation of correlations generated by local measurements on entangled quantum states by local hidden-variables models and the revelation of hidden nonlocality. We present and detail the Werner's local model and the hidden nonlocality of some Werner states of dimension $d\\geq5$, the Gisin-Degorre's local model for a Werner state of dimension $d=2$ and the local model of Hirsch et al. for mixtures of the singlet state and noise, all of them f...

  9. Suppressing the QCD axion abundance by hidden monopoles

    International Nuclear Information System (INIS)

    Kawasaki, Masahiro

    2015-11-01

    We study the Witten effect of hidden monopoles on the QCD axion dynamics, and show that its abundance as well as isocurvature perturbations can be significantly suppressed if there is a sufficient amount of hidden monopoles. When the hidden monopoles make up a significant fraction of dark matter, the Witten effect suppresses the abundance of axion with the decay constant smaller than 10 12 GeV. The cosmological domain wall problem of the QCD axion can also be avoided, relaxing the upper bound on the decay constant when the Peccei-Quinn symmetry is spontaneously broken after inflation.

  10. Functional materials based on carbon nanotubes: Carbon nanotube actuators and noncovalent carbon nanotube modification

    Science.gov (United States)

    Fifield, Leonard S.

    Carbon nanotubes have attractive inherent properties that encourage the development of new functional materials and devices based on them. The use of single wall carbon nanotubes as electromechanical actuators takes advantage of the high mechanical strength, surface area and electrical conductivity intrinsic to these molecules. The work presented here investigates the mechanisms that have been discovered for actuation of carbon nanotube paper: electrostatic, quantum chemical charge injection, pneumatic and viscoelastic. A home-built apparatus for the measurement of actuation strain is developed and utilized in the investigation. An optical fiber switch, the first demonstrated macro-scale device based on the actuation of carbon nanotubes, is described and its performance evaluated. Also presented here is a new general process designed to modify the surface of carbon nanotubes in a non-covalent, non-destructive way. This method can be used to impart new functionalities to carbon nanotube samples for a variety of applications including sensing, solar energy conversion and chemical separation. The process described involves the achievement of large degrees of graphitic surface coverage with polycyclic aromatic hydrocarbons through the use of supercritical fluids. These molecules are bifunctional agents that anchor a desired chemical group to the aromatic surface of the carbon nanotubes without adversely disrupting the conjugated backbone that gives rise the attractive electronic and physical properties of the nanotubes. Both the nanotube functionalization work and the actuator work presented here emphasize how an understanding and control of nanoscale structure and phenomena can be of vital importance in achieving desired performance for active materials. Opportunities for new devices with improved function over current state-of-the-art can be envisioned and anticipated based on this understanding and control.

  11. Anti-pairing in learning of a neural network with redundant hidden units

    International Nuclear Information System (INIS)

    Kwon, Chulan; Kim, Hyong Kyun

    2005-01-01

    We study the statistical mechanics of learning from examples between the two-layered committee machines with different numbers of hidden units using the replica theory. The number M of hidden units of the student network is larger than the number M T of those of the target network called the teacher. We choose the networks to have binary synaptic weights, ±1, which makes it possible to compare the calculation with the Monte Carlo simulation. We propose an effective teacher as a virtual target network which has the same M hidden units as the student and gives identical outputs with those of the original teacher. This is a way of making a conjecture for a ground state of a thermodynamic system, given by the weights of the effective teacher in our study. We suppose that the weights on M T hidden units of the effective teacher are the same as those of the original teacher while those on M - M T redundant hidden units are composed of anti-pairs, {1, - 1}, with probability 1 - p in the limit p → 0. For p = 0 exact, there are no terms related to the effective teacher in the calculation, for the contributions of anti-pairs to outputs are exactly cancelled. In the limit p → 0, however, we find that the learnt weights of the student are actually equivalent to those of the suggested effective teacher, which is not possible from the calculation for p = 0. p plays the role of a symmetry breaking parameter for anti-pairing ordering, which is analogous to the magnetic field for the Ising model. A first-order phase transition is found to be signalled by breaking of symmetry in permuting hidden units. Above a critical number of examples, the student is shown to learn perfectly the effective teacher. Anti-pairing can be measured by a set of order parameters; zero in the permutation-symmetric phase and nonzero in the permutation symmetry breaking phase. Results from the Monte Carlo simulation are shown to be in good agreement with those from the replica calculation

  12. Morphology and growth of titania nanotubes. Nanostructuring and applications

    Energy Technology Data Exchange (ETDEWEB)

    Albu, Sergiu P.

    2012-10-26

    Self-ordering phenomena during anodic oxidation of metals and the formation of porous oxides have been of a great interest to science and technology for more than 50 years. Particularly, after Masuda et al. demonstrated ideally ordered porous alumina by fine tuning the experimental parameters during aluminum anodization, these structures were increasingly used as a template for the deposition and growth of large varieties of 1D functional materials. For some time, such self-organized oxide structures seemed to be limited to Al{sub 2}O{sub 3}, but in 1999 Zwilling et al. reported self-organized oxide structures (aligned nanotubes) anodically grown on Ti in a dilute fluoride solution. Dilute fluoride electrolytes were then found suitable to grow ordered tubular or porous oxides on a large range of other metals and alloys. Subsequently, the control over the morphology (diameter, length, smoothness of the walls) was strongly improved by continuously optimizing the anodizing conditions. Most research work has been directed towards TiO{sub 2} nanotubes, as TiO{sub 2} with its semiconductive nature makes the nanotubular structures promising for use in solar cells, photocatalysis and sensors, and also its ion insertion properties and its high degree of biocompatibility have attracted wide interest. The experimental optimization of growth parameters led to various semi-quantitative or qualitative models that provide a mechanistic reasoning for the occurrence of self-organization. Although theoretical modeling of self-ordered structures grown anodically on valve metals was increasingly refined, a main source of difficulty remained, namely the multitude of experimental factors which influence the growth of self-ordered nanostructures. The present work represents an attempt to provide a detailed experimental view over the growth of TiO{sub 2} nanotubes in organic electrolytes. The first part is based on describing the methods and set-ups used for growth and characterization of

  13. Carbon nanotube based photocathodes

    International Nuclear Information System (INIS)

    Hudanski, Ludovic; Minoux, Eric; Schnell, Jean-Philippe; Xavier, Stephane; Pribat, Didier; Legagneux, Pierre; Gangloff, Laurent; Teo, Kenneth B K; Robertson, John; Milne, William I

    2008-01-01

    This paper describes a novel photocathode which is an array of vertically aligned multi-walled carbon nanotubes (MWCNTs), each MWCNT being associated with one p-i-n photodiode. Unlike conventional photocathodes, the functions of photon-electron conversion and subsequent electron emission are physically separated. Photon-electron conversion is achieved with p-i-n photodiodes and the electron emission occurs from the MWCNTs. The current modulation is highly efficient as it uses an optically controlled reconfiguration of the electric field at the MWCNT locations. Such devices are compatible with high frequency and very large bandwidth operation and could lead to their application in compact, light and efficient microwave amplifiers for satellite telecommunication. To demonstrate this new photocathode concept, we have fabricated the first carbon nanotube based photocathode using silicon p-i-n photodiodes and MWCNT bunches. Using a green laser, this photocathode delivers 0.5 mA with an internal quantum efficiency of 10% and an I ON /I OFF ratio of 30

  14. Carbon nanotube array actuators

    International Nuclear Information System (INIS)

    Geier, S; Mahrholz, T; Wierach, P; Sinapius, M

    2013-01-01

    Experimental investigations of highly vertically aligned carbon nanotubes (CNTs), also known as CNT-arrays, are the main focus of this paper. The free strain as result of an active material behavior is analyzed via a novel experimental setup. Previous test experiences of papers made of randomly oriented CNTs, also called Bucky-papers, reveal comparably low free strain. The anisotropy of aligned CNTs promises better performance. Via synthesis techniques like chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), highly aligned arrays of multi-walled carbon nanotubes (MWCNTs) are synthesized. Two different types of CNT-arrays are analyzed, morphologically first, and optically tested for their active characteristics afterwards. One type of the analyzed arrays features tube lengths of 750–2000 μm with a large variety of diameters between 20 and 50 nm and a wave-like CNT-shape. The second type features a maximum, almost uniform, length of 12 μm and a constant diameter of 50 nm. Different CNT-lengths and array types are tested due to their active behavior. As result of the presented tests, it is reported that the quality of orientation is the most decisive property for excellent active behavior. Due to their alignment, CNT-arrays feature the opportunity to clarify the actuation mechanism of architectures made of CNTs. (paper)

  15. Proposal of Carbon Nanotube Inductors

    National Research Council Canada - National Science Library

    Tsubaki, K; Nakajima, Y; Hanajiri, T; Yamaguchi, H

    2006-01-01

    The inductors made of carbon Nanotube (CNT) have been proposed. Though the fabrication of the proposed inductor is still challenging and has many problems, merits of the proposed inductor are following...

  16. Noble-Metal Chalcogenide Nanotubes

    Directory of Open Access Journals (Sweden)

    Nourdine Zibouche

    2014-10-01

    Full Text Available We explore the stability and the electronic properties of hypothetical noble-metal chalcogenide nanotubes PtS2, PtSe2, PdS2 and PdSe2 by means of density functional theory calculations. Our findings show that the strain energy decreases inverse quadratically with the tube diameter, as is typical for other nanotubes. Moreover, the strain energy is independent of the tube chirality and converges towards the same value for large diameters. The band-structure calculations show that all noble-metal chalcogenide nanotubes are indirect band gap semiconductors. The corresponding band gaps increase with the nanotube diameter rapidly approaching the respective pristine 2D monolayer limit.

  17. Method for producing carbon nanotubes

    Science.gov (United States)

    Phillips, Jonathan [Santa Fe, NM; Perry, William L [Jemez Springs, NM; Chen, Chun-Ku [Albuquerque, NM

    2006-02-14

    Method for producing carbon nanotubes. Carbon nanotubes were prepared using a low power, atmospheric pressure, microwave-generated plasma torch system. After generating carbon monoxide microwave plasma, a flow of carbon monoxide was directed first through a bed of metal particles/glass beads and then along the outer surface of a ceramic tube located in the plasma. As a flow of argon was introduced into the plasma through the ceramic tube, ropes of entangled carbon nanotubes, attached to the surface of the tube, were produced. Of these, longer ropes formed on the surface portion of the tube located in the center of the plasma. Transmission electron micrographs of individual nanotubes revealed that many were single-walled.

  18. A modal analysis of carbon nanotube using elastic network model

    International Nuclear Information System (INIS)

    Kim, Min Hyeok; Seo, Sang Jae; Lim, Byeong Soo; Choi, Jae Boong; Kim, Moon Ki; Liu, Wing Kam

    2012-01-01

    Although it is widely known that both size and chirality play significant roles in vibration behaviors of single walled carbon nanotubes (SWCNTs), there haven't been yet enough studies specifying the relationship between structure and vibration mode shape of SWCNTs. We have analyzed the chirality and length dependence of SWCNT by using normal mode analysis based elastic network model in which all interatomic interactions of the given SWCNTs structure are represented by a network of linear spring connections. As this method requires relatively short computation time compared to molecular dynamics simulation, we can efficiently analyze vibration behavior of SWCNTs. To ensure the relationship between SWCNT structure and its vibration mode shapes, we simulated more than one hundred SWCNTs having different types of chirality and length. Results indicated that the first two major mode shapes are bending and breathing. The minimum length of nanotube for maintaining the bending mode does not depend on chirality but on its diameter. Our simulations pointed out that there is a critical aspect ratio between diameter and length to determine vibration mode shapes, and it can be empirically formulated as a function of nanotube length and diameter. Therefore, uniformity control is the most important premise in order to utilize vibration features of SWCNTs. It is also expected that the obtained vibration aspect will play an important role in designing nanotube based devices such as resonators and sensors more accurately

  19. High Energy Colliders and Hidden Sectors

    Science.gov (United States)

    Dror, Asaf Jeff

    This thesis explores two dominant frontiers of theoretical physics, high energy colliders and hidden sectors. The Large Hadron Collider (LHC) is just starting to reach its maximum operational capabilities. However, already with the current data, large classes of models are being put under significant pressure. It is crucial to understand whether the (thus far) null results are a consequence of a lack of solution to the hierarchy problem around the weak scale or requires expanding the search strategy employed at the LHC. It is the duty of the current generation of physicists to design new searches to ensure that no stone is left unturned. To this end, we study the sensitivity of the LHC to the couplings in the Standard Model top sector. We find it can significantly improve the measurements on ZtRtR coupling by a novel search strategy, making use of an implied unitarity violation in such models. Analogously, we show that other couplings in the top sector can also be measured with the same technique. Furthermore, we critically analyze a set of anomalies in the LHC data and how they may appear from consistent UV completions. We also propose a technique to measure lifetimes of new colored particles with non-trivial spin. While the high energy frontier will continue to take data, it is likely the only collider of its kind for the next couple decades. On the other hand, low-energy experiments have a promising future with many new proposed experiments to probe the existence of particles well below the weak scale but with small couplings to the Standard Model. In this work we survey the different possibilities, focusingon the constraints as well as possible new hidden sector dynamics. In particular, we show that vector portals which couple to an anomalous current, e.g., baryon number, are significantly constrained from flavor changing meson decays and rare Z decays. Furthermore, we present a new mechanism for dark matter freezeout which depletes the dark sector through an

  20. Alleviating hidden hunger. Approaches that work

    International Nuclear Information System (INIS)

    Kennedy, E.; Mannar, V.; Iyengar, V.

    2003-01-01

    The world has come a long way in understanding the nature, magnitude and range of solutions to micronutrient malnutrition - often called 'hidden hunger'. The most sustainable solutions - that is those that are likely to be maintained in the long term - almost surely will include food-based approaches including diet diversity, food fortification and biofortification. Food fortification and biofortification could be some of the most cost-effective of all public health interventions and thus within the economic reach of even the world's poorest. In order to implement them in a sustainable manner, a combination of technical, operational, economic, behavioural and political factors need to be addressed. In some ways the technological issues are the easiest. Because of attention to research, we now have a variety of ways for both single and multiple micronutrients to reach the target population. We also know what is needed in order to ensure delivery systems. The key factor for continued success in reducing micronutrient malnutrition through fortification is a political commitment at the national and international level and creating effective public-private partnerships at the national level. The payoff for eliminating hidden hunger through nutrient fortification is enormous and few other public health interventions offer such a promising health, nutrition and economic success story. Nuclear and isotopic techniques are valuable tools in helping to meet the multifaceted challenges posed by nutritional disorders affecting the entire human life span (embryonic to elderly). Among the numerous applications available, isotopic techniques are uniquely well suited for targeting and tracking progress in food and nutrition development programmes (See box: How Nutrients are Tracked). These include: use of the stable isotopes of iron (Fe) and zinc (Zn) as a kind of gold standard in studies of their bioavailability from foods; trace element bioavailability and pool sizes for

  1. Underwater Acoustic Carbon Nanotube Thermophone

    Science.gov (United States)

    2016-09-23

    decreases rapidly as the distance from the conductor increases. Based on the rapid production of these temperature waves; the net effect is to produce a...fragile and are susceptible to disintegration especially if the nanotube fibers are touched or moved too quickly. A bare nanotube configuration also has...impedance (defined as the product of material density and sound speed) of the top shell 42 should match the radiation medium for higher efficiency

  2. Gold(I)-Alkanethiolate Nanotubes

    KAUST Repository

    Zhang, Yu Xin; Zeng, Hua Chun

    2009-01-01

    (Figure Presented) A solution approach to assembling Au(I) - alkanethiolates into nanotube structures at room temperature is presented, in which Au(I) cations and alkanethiolate ligands are coordinated into thin platelet forms that then evolve into an open tubular configuration (see figure). The organic-inorganic hybrid nature of the nanotubes, their ability to be modified, and their high stability make them of interest for practical applications. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.

  3. Selective functionalization of carbon nanotubes

    Science.gov (United States)

    Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H. (Inventor); Smalley, Richard E. (Inventor)

    2009-01-01

    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

  4. Carbon nanotubes for coherent spintronics

    DEFF Research Database (Denmark)

    Kuemmeth, Ferdinand; Churchill, H O H; Herring, P K

    2010-01-01

    Carbon nanotubes bridge the molecular and crystalline quantum worlds, and their extraordinary electronic, mechanical and optical properties have attracted enormous attention from a broad scientific community. We review the basic principles of fabricating spin-electronic devices based on individual......, electrically-gated carbon nanotubes, and present experimental efforts to understand their electronic and nuclear spin degrees of freedom, which in the future may enable quantum applications....

  5. Gold(I)-Alkanethiolate Nanotubes

    KAUST Repository

    Zhang, Yu Xin

    2009-12-28

    (Figure Presented) A solution approach to assembling Au(I) - alkanethiolates into nanotube structures at room temperature is presented, in which Au(I) cations and alkanethiolate ligands are coordinated into thin platelet forms that then evolve into an open tubular configuration (see figure). The organic-inorganic hybrid nature of the nanotubes, their ability to be modified, and their high stability make them of interest for practical applications. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.

  6. Inferring topologies of complex networks with hidden variables.

    Science.gov (United States)

    Wu, Xiaoqun; Wang, Weihan; Zheng, Wei Xing

    2012-10-01

    Network topology plays a crucial role in determining a network's intrinsic dynamics and function, thus understanding and modeling the topology of a complex network will lead to greater knowledge of its evolutionary mechanisms and to a better understanding of its behaviors. In the past few years, topology identification of complex networks has received increasing interest and wide attention. Many approaches have been developed for this purpose, including synchronization-based identification, information-theoretic methods, and intelligent optimization algorithms. However, inferring interaction patterns from observed dynamical time series is still challenging, especially in the absence of knowledge of nodal dynamics and in the presence of system noise. The purpose of this work is to present a simple and efficient approach to inferring the topologies of such complex networks. The proposed approach is called "piecewise partial Granger causality." It measures the cause-effect connections of nonlinear time series influenced by hidden variables. One commonly used testing network, two regular networks with a few additional links, and small-world networks are used to evaluate the performance and illustrate the influence of network parameters on the proposed approach. Application to experimental data further demonstrates the validity and robustness of our method.

  7. Representation of Hidden Curriculum in EFL Textbook (Gender Markers

    Directory of Open Access Journals (Sweden)

    Ekaterina E. Shishlova

    2014-01-01

    Full Text Available The article considers the mechanism ofrepresenting the hidden curriculum in the discourse of EFL textbooks, i.e. the transmission ofsociocultural norms and values of native speakers to foreign students. To do this the authors make a brieftheoretical review of this problem and demonstrate the results of the comparative discourse analysis of two popular textbooks, the one of the pre-globalization age and the present-day one. The authors provide evidence for their idea of the dual role, which English plays today being simultaneously a national language of different English-speaking societies and the global lingua franca. The conducted discourse analysis is based on the analysis of semiotic means, which are used to nominate concepts basic to any society and culture. In the article, the authors demonstrate their own plan of analysis by the example of the "gender" concept. The gender concept shows social and cultural conditionality of distinctions in behavior and the identity of men and women. The comparative analysis of gender markers in the discourse of EFL textbooks reveals a global vector of transformation and distribution ofsociocultural values. Authors state that cultural expansion through English teaching is an instrument of smart power. It is suggested using the mechanism of transmission ofsociocultural norms and values, which is analyzed in the research, to create Russian textbooks for foreign students.

  8. Implications of hidden gauged U (1 ) model for B anomalies

    Science.gov (United States)

    Fuyuto, Kaori; Li, Hao-Lin; Yu, Jiang-Hao

    2018-06-01

    We propose a hidden gauged U (1 )H Z' model to explain deviations from the standard model (SM) values in lepton flavor universality known as RK and RD anomalies. The Z' only interacts with the SM fermions via their mixing with vectorlike doublet fermions after the U (1 )H symmetry breaking, which leads to b →s μ μ transition through the Z' at tree level. Moreover, introducing an additional mediator, inert-Higgs doublet, yields b →c τ ν process via charged scalar contribution at tree level. Using flavio package, we scrutinize adequate sizes of the relevant Wilson coefficients to these two processes by taking various flavor observables into account. It is found that significant mixing between the vectorlike and the second generation leptons is needed for the RK anomaly. A possible explanation of the RD anomaly can also be simultaneously addressed in a motivated situation, where a single scalar operator plays a dominant role, by the successful model parameters for the RK anomaly.

  9. Prediction of Annual Rainfall Pattern Using Hidden Markov Model ...

    African Journals Online (AJOL)

    ADOWIE PERE

    Hidden Markov model is very influential in stochastic world because of its ... the earth from the clouds. The usual ... Rainfall modelling and ... Markov Models have become popular tools ... environment sciences, University of Jos, plateau state,.

  10. New limits on hidden photons from past electron beam dumps

    International Nuclear Information System (INIS)

    Andreas, Sarah; Niebuhr, Carsten; Ringwald, Andreas

    2012-09-01

    Hidden sectors with light extra U(1) gauge bosons, so called hidden photons, have recently attracted some attention because they are a common feature of physics beyond the Standard Model like string theory and SUSY and additionally are phenomenologically of great interest regarding recent astrophysical observations. The hidden photon is already constrained by various laboratory experiments and presently searched for in running as well as upcoming experiments. We summarize the current status of limits on hidden photons from past electron beam dump experiments including two new limits from such experiments at KEK and Orsay that have so far not been considered. All our limits take into account the experimental acceptances obtained from Monte Carlo simulations.

  11. Search for hidden particles with the SHiP experiment

    Energy Technology Data Exchange (ETDEWEB)

    Hagner, Caren; Bick, Daniel; Bieschke, Stefan; Ebert, Joachim; Schmidt-Parzefall, Walter [Universitaet Hamburg, Institut fuer Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg (Germany)

    2016-07-01

    Many theories beyond the standard model predict long lived neutral (hidden) particles. There might be a whole Hidden Sector (HS) of weakly interacting particles, which cannot be detected in existing high energy experiments. The SHiP experiment (Search for Hidden Particles) requires a high intensity beam dump, which could be realized by a new facility at the CERN SPS accelerator. New superweakly interacting particles with masses below O(10) GeV could be produced in the beam dump and detected in a general purpose Hidden Sector (HS) detector. In addition there will be a dedicated tau neutrino subdetector. I present the major requirements and technical challenges for the HS detector and discuss how the HS can be accessed through several portals: neutrino portal, scalar portal, vector portal and many more.

  12. Cosmological abundance of the QCD axion coupled to hidden photons

    Science.gov (United States)

    Kitajima, Naoya; Sekiguchi, Toyokazu; Takahashi, Fuminobu

    2018-06-01

    We study the cosmological evolution of the QCD axion coupled to hidden photons. For a moderately strong coupling, the motion of the axion field leads to an explosive production of hidden photons by tachyonic instability. We use lattice simulations to evaluate the cosmological abundance of the QCD axion. In doing so, we incorporate the backreaction of the produced hidden photons on the axion dynamics, which becomes significant in the non-linear regime. We find that the axion abundance is suppressed by at most O (102) for the decay constant fa =1016GeV, compared to the case without the coupling. For a sufficiently large coupling, the motion of the QCD axion becomes strongly damped, and as a result, the axion abundance is enhanced. Our results show that the cosmological upper bound on the axion decay constant can be relaxed by a few hundred for a certain range of the coupling to hidden photons.

  13. Dopamine reward prediction errors reflect hidden state inference across time

    Science.gov (United States)

    Starkweather, Clara Kwon; Babayan, Benedicte M.; Uchida, Naoshige; Gershman, Samuel J.

    2017-01-01

    Midbrain dopamine neurons signal reward prediction error (RPE), or actual minus expected reward. The temporal difference (TD) learning model has been a cornerstone in understanding how dopamine RPEs could drive associative learning. Classically, TD learning imparts value to features that serially track elapsed time relative to observable stimuli. In the real world, however, sensory stimuli provide ambiguous information about the hidden state of the environment, leading to the proposal that TD learning might instead compute a value signal based on an inferred distribution of hidden states (a ‘belief state’). In this work, we asked whether dopaminergic signaling supports a TD learning framework that operates over hidden states. We found that dopamine signaling exhibited a striking difference between two tasks that differed only with respect to whether reward was delivered deterministically. Our results favor an associative learning rule that combines cached values with hidden state inference. PMID:28263301

  14. Optimisation of Hidden Markov Model using Baum–Welch algorithm ...

    Indian Academy of Sciences (India)

    The present work is a part of development of Hidden Markov Model. (HMM) based ... the Himalaya. In this work, HMMs have been developed for forecasting of maximum and minimum ..... data collection teams of Snow and Avalanche Study.

  15. On the LHC sensitivity for non-thermalised hidden sectors

    Science.gov (United States)

    Kahlhoefer, Felix

    2018-04-01

    We show under rather general assumptions that hidden sectors that never reach thermal equilibrium in the early Universe are also inaccessible for the LHC. In other words, any particle that can be produced at the LHC must either have been in thermal equilibrium with the Standard Model at some point or must be produced via the decays of another hidden sector particle that has been in thermal equilibrium. To reach this conclusion, we parametrise the cross section connecting the Standard Model to the hidden sector in a very general way and use methods from linear programming to calculate the largest possible number of LHC events compatible with the requirement of non-thermalisation. We find that even the HL-LHC cannot possibly produce more than a few events with energy above 10 GeV involving states from a non-thermalised hidden sector.

  16. Risk from the frontlines of a hidden epidemic sexuality, masculinities ...

    African Journals Online (AJOL)

    Risk from the frontlines of a hidden epidemic sexuality, masculinities and social pressures ... It frames risk in the context of the dynamics governing sexuality, underlined ... MSM risk and practice, in these contexts, are consequently shaped by ...

  17. New limits on hidden photons from past electron beam dumps

    Energy Technology Data Exchange (ETDEWEB)

    Andreas, Sarah; Niebuhr, Carsten; Ringwald, Andreas

    2012-09-15

    Hidden sectors with light extra U(1) gauge bosons, so called hidden photons, have recently attracted some attention because they are a common feature of physics beyond the Standard Model like string theory and SUSY and additionally are phenomenologically of great interest regarding recent astrophysical observations. The hidden photon is already constrained by various laboratory experiments and presently searched for in running as well as upcoming experiments. We summarize the current status of limits on hidden photons from past electron beam dump experiments including two new limits from such experiments at KEK and Orsay that have so far not been considered. All our limits take into account the experimental acceptances obtained from Monte Carlo simulations.

  18. Two-Stage Hidden Markov Model in Gesture Recognition for Human Robot Interaction

    Directory of Open Access Journals (Sweden)

    Nhan Nguyen-Duc-Thanh

    2012-07-01

    Full Text Available Hidden Markov Model (HMM is very rich in mathematical structure and hence can form the theoretical basis for use in a wide range of applications including gesture representation. Most research in this field, however, uses only HMM for recognizing simple gestures, while HMM can definitely be applied for whole gesture meaning recognition. This is very effectively applicable in Human-Robot Interaction (HRI. In this paper, we introduce an approach for HRI in which not only the human can naturally control the robot by hand gesture, but also the robot can recognize what kind of task it is executing. The main idea behind this method is the 2-stages Hidden Markov Model. The 1st HMM is to recognize the prime command-like gestures. Based on the sequence of prime gestures that are recognized from the 1st stage and which represent the whole action, the 2nd HMM plays a role in task recognition. Another contribution of this paper is that we use the output Mixed Gaussian distribution in HMM to improve the recognition rate. In the experiment, we also complete a comparison of the different number of hidden states and mixture components to obtain the optimal one, and compare to other methods to evaluate this performance.

  19. The hidden curriculum in radiology residency programs: A path to isolation or integration?

    International Nuclear Information System (INIS)

    Van Deven, T.; Hibbert, K.; Faden, L.; Chhem, R.K.

    2013-01-01

    Purpose: In this qualitative case study involving five academic Radiology centres across Canada, the authors seek to identify the hidden curriculum. Methods: A qualitative case study methodology was used for its potential to explore and provide rich descriptions and allow for the in-depth analysis of multiple data sources that include official institutional documents, surveys, observations and interviews (including undergraduate students, postgraduate, radiologists, imaging scientists, residents, faculty and administrators). This study relied on 48 interviews and involved primary data analysis by the core research team, and a secondary analysis by external examiners. Results: The results revealed that in four of the five major centres studied, a hidden curriculum of isolation prevailed, reinforcing an image of the radiologist as an independent operator within an organization dependent upon collaboration for optimal performance. The fifth site exhibited a hidden curriculum of collaboration and support, although the messages received were conflicting when addressing issues around teaching. Conclusions: The authors conclude by noting two possibilities for medical imaging departments to consider that of isolation or that of integration. They examine the implications of each and propose a way forward that situates Radiology as the crossroads of medicine. As such, the need for a new, generative metaphor reasserts the importance of recognizing the role and function of scholarship in teaching and learning contexts across Canada

  20. The hidden curriculum in radiology residency programs: A path to isolation or integration?

    Energy Technology Data Exchange (ETDEWEB)

    Van Deven, T. [Department of Medical Imaging, Schulich School of Medicine and Dentistry (Canada); Hibbert, K., E-mail: khibbert@uwo.ca [Faculty of Education, Schulich School of Medicine and Dentistry (Canada); Faden, L. [Faculty of Education, The University of Western Ontario (Canada); Chhem, R.K. [Institute of History, Philosophy and Ethics of Medicine, Ulm University, Ulm (Germany)

    2013-05-15

    Purpose: In this qualitative case study involving five academic Radiology centres across Canada, the authors seek to identify the hidden curriculum. Methods: A qualitative case study methodology was used for its potential to explore and provide rich descriptions and allow for the in-depth analysis of multiple data sources that include official institutional documents, surveys, observations and interviews (including undergraduate students, postgraduate, radiologists, imaging scientists, residents, faculty and administrators). This study relied on 48 interviews and involved primary data analysis by the core research team, and a secondary analysis by external examiners. Results: The results revealed that in four of the five major centres studied, a hidden curriculum of isolation prevailed, reinforcing an image of the radiologist as an independent operator within an organization dependent upon collaboration for optimal performance. The fifth site exhibited a hidden curriculum of collaboration and support, although the messages received were conflicting when addressing issues around teaching. Conclusions: The authors conclude by noting two possibilities for medical imaging departments to consider that of isolation or that of integration. They examine the implications of each and propose a way forward that situates Radiology as the crossroads of medicine. As such, the need for a new, generative metaphor reasserts the importance of recognizing the role and function of scholarship in teaching and learning contexts across Canada.

  1. Reading Hidden Messages Through Deciphered Manual Alphabets on Classic Artwork

    Science.gov (United States)

    Castronovo, Joseph Anthony, Jr.

    1998-10-01

    Decipherment is the tool used to uncover several types of hand signs that played vital roles in the creation of hidden messages in classic artwork. A 3,100 B.C. bas-relief of The 'Kaph' Telescope, formerly named The Narmer Palette, and Michaelangelo Buonarrotte's Battle of Cascina of 1506 were two key works of art that show certain similarities even though separated by 4,500 years. It is evident that Renaissance humanists provided artists with certain knowledge of the ancients. Results of incorporating a number of minor works of art showed that the competence of ancient Egyptians, Cretans and Australian Aboriginals, to name a few, as astronomers, was underestimated. Some deciphered Indus seals attested to a global understanding of the universe, with Gemini and the star of Thuban at the center of their attention. Certain forms of secrecy had to be undertaken for various reasons throughout the millennia. Three examples are: (1) In Italy, to keep controversial and truthful teachings discreet and hidden, artists embedded them in artwork long before the plight of Galileo Galilei and his discoveries. (2) Among Jewish Kabbalists, a well-known design was obscured in The Arnolfini Wedding painting for fear it would be lost due to persecution. (3) Michaelangelo Buonarrotte indicated several meanings through the hands of The Statue of Moses. They were overlooked by several societies, including the gesticulating culture of Italy, because they oppressed the value of signed languages. Spatial decipherment may testify to a need for the restoration of a spatial writing system for expanded linguistic accessibility. A 21st century model community for sign language residents and employees will benefit visual learners, particularly visual artists and non-phonetic decipherers, to better uncover, understand and perhaps use ancient hand forms to restore ancient knowledge. Moreover, the National Association of Teaching English (NATE) has recently endorsed the addition of two skills

  2. Modification of Hidden Layer Weight in Extreme Learning Machine Using Gain Ratio

    Directory of Open Access Journals (Sweden)

    Anggraeny Fetty Tri

    2016-01-01

    Full Text Available Extreme Learning Machine (ELM is a method of learning feed forward neural network quickly and has a fairly good accuracy. This method is devoted to a feed forward neural network with one hidden layer where the parameters (i.e. weight and bias are adjusted one time randomly at the beginning of the learning process. In neural network, the input layer is connected to all characteristics/features, and the output layer is connected to all classes of species. This research used three datasets from UCI database, which were Iris, Breast Wisconsin, and Dermatology, with each dataset having several features. Each characteristic/feature of the data has a role in the process of classification levels, starting from the most influencing role to non-influencing at all. Gain ratio was used to extract each feature role on each datasets. Gain ratio is a method to extract feature role in order to develop a decision tree structure. In this study, ELM structure has been modified, where the random weights of the hidden layer were adjusted to the level of each feature role in determining the species class, so as to improve the level of training and testing accuracy. The proposed method has higher classification accuracy rate than basic ELM on all three datasets, which were 99%, 96%, and 82%, respectively.

  3. A Novel Method for Decoding Any High-Order Hidden Markov Model

    Directory of Open Access Journals (Sweden)

    Fei Ye

    2014-01-01

    Full Text Available This paper proposes a novel method for decoding any high-order hidden Markov model. First, the high-order hidden Markov model is transformed into an equivalent first-order hidden Markov model by Hadar’s transformation. Next, the optimal state sequence of the equivalent first-order hidden Markov model is recognized by the existing Viterbi algorithm of the first-order hidden Markov model. Finally, the optimal state sequence of the high-order hidden Markov model is inferred from the optimal state sequence of the equivalent first-order hidden Markov model. This method provides a unified algorithm framework for decoding hidden Markov models including the first-order hidden Markov model and any high-order hidden Markov model.

  4. A two particle hidden sector and the oscillations with photons

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, Pedro D. [Universidad de Antofagasta, Departamento de Fisica, Antofagasta (Chile); Arias, Paola; Maldonado, Carlos [Universidad de Santiago de Chile, Departmento de Fisica, Santiago (Chile)

    2018-01-15

    We present a detailed study of the oscillations and optical properties for vacuum, in a model for the dark sector that contains axion-like particles and hidden photons. We provide bounds for the couplings versus the mass, using current results from ALPS-I and PVLAS. We also discuss the challenges for the detection of models with more than one hidden particle in light shining trough wall-like experiments. (orig.)

  5. Rare Z boson decays to a hidden sector

    Science.gov (United States)

    Blinov, Nikita; Izaguirre, Eder; Shuve, Brian

    2018-01-01

    We demonstrate that rare decays of the Standard Model Z boson can be used to discover and characterize the nature of new hidden-sector particles. We propose new searches for these particles in soft, high-multiplicity leptonic final states at the Large Hadron Collider. The proposed searches are sensitive to low-mass particles produced in Z decays, and we argue that these striking signatures can shed light on the hidden-sector couplings and mechanism for mass generation.

  6. Anticipating hidden text salting in emails (extended abstract)

    OpenAIRE

    Lioma, Christina; Moens, Marie-Francine; Gomez, Juan Carlos; De Beer, Jan; Bergholz, Andre; Paass, Gerhard; Horkan, Patrick

    2008-01-01

    Salting is the intentional addition or distortion of content, aimed to evade automatic filtering. Salting is usually found in spam emails. Salting can also be hidden in phishing emails, which aim to steal personal information from users. We present a novel method that detects hidden salting tricks as visual anomalies in text. We solely use these salting tricks to successfully classify emails as phishing (F-measure >90%).

  7. Hidden twelve-dimensional super Poincare symmetry in eleven dimensions

    International Nuclear Information System (INIS)

    Bars, Itzhak; Deliduman, Cemsinan; Pasqua, Andrea; Zumino, Bruno

    2004-01-01

    First, we review a result in our previous paper, of how a ten-dimensional superparticle, taken off-shell, has a hidden eleven-dimensional super Poincare symmetry. Then, we show that the physical sector is defined by three first-class constraints which preserve the full eleven-dimensional symmetry. Applying the same concepts to the eleven-dimensional superparticle, taken off-shell, we discover a hidden twelve-dimensional super Poincare symmetry that governs the theory

  8. Hidden charged dark matter and chiral dark radiation

    Science.gov (United States)

    Ko, P.; Nagata, Natsumi; Tang, Yong

    2017-10-01

    In the light of recent possible tensions in the Hubble constant H0 and the structure growth rate σ8 between the Planck and other measurements, we investigate a hidden-charged dark matter (DM) model where DM interacts with hidden chiral fermions, which are charged under the hidden SU(N) and U(1) gauge interactions. The symmetries in this model assure these fermions to be massless. The DM in this model, which is a Dirac fermion and singlet under the hidden SU(N), is also assumed to be charged under the U(1) gauge symmetry, through which it can interact with the chiral fermions. Below the confinement scale of SU(N), the hidden quark condensate spontaneously breaks the U(1) gauge symmetry such that there remains a discrete symmetry, which accounts for the stability of DM. This condensate also breaks a flavor symmetry in this model and Nambu-Goldstone bosons associated with this flavor symmetry appear below the confinement scale. The hidden U(1) gauge boson and hidden quarks/Nambu-Goldstone bosons are components of dark radiation (DR) above/below the confinement scale. These light fields increase the effective number of neutrinos by δNeff ≃ 0.59 above the confinement scale for N = 2, resolving the tension in the measurements of the Hubble constant by Planck and Hubble Space Telescope if the confinement scale is ≲1 eV. DM and DR continuously scatter with each other via the hidden U(1) gauge interaction, which suppresses the matter power spectrum and results in a smaller structure growth rate. The DM sector couples to the Standard Model sector through the exchange of a real singlet scalar mixing with the Higgs boson, which makes it possible to probe our model in DM direct detection experiments. Variants of this model are also discussed, which may offer alternative ways to investigate this scenario.

  9. The perception of the hidden curriculum on medical education: an exploratory study

    Directory of Open Access Journals (Sweden)

    Murakami Manabu

    2009-12-01

    Full Text Available Abstract Background Major curriculum reform of undergraduate medical education occurred during the past decades in the United Kingdom (UK; however, the effects of the hidden curriculum, which influence the choice of primary care as a career, have not been sufficiently recognized. While Japan, where traditionally few institutions systematically foster primary care physicians and very few have truly embraced family medicine as their guiding discipline, has also experienced meaningful curriculum reform, the effect of the hidden curriculum is not well known. The aim of this study is to identify themes pertaining to the students' perceptions of the hidden curriculum affecting undergraduate medical education in bedside learning in Japan. Methods Semi-structured interviews with thematic content analysis were implemented. Undergraduate year-5 students from a Japanese medical school at a Japanese teaching hospital were recruited. Interview were planned to last between 30 to 60 minutes each, over an 8-month period in 2007. The interviewees' perceptions concerning the quality of teaching in their bedside learning and related experiences were collected and analysed thematically. Results Twenty five medical students (18 males and 7 females, mean age 25 years old consented to participate in the interviews, and seven main themes emerged: "the perception of education as having a low priority," "the prevalence of positive/negative role models," "the persistence of hierarchy and exclusivity," "the existence of gender issues," "an overburdened medical knowledge," "human relationships with colleagues and medical team members," and "first experience from the practical wards and their patients." Conclusions Both similarities and differences were found when comparing the results to those of previous studies in the UK. Some effects of the hidden curriculum in medical education likely exist in common between the UK and Japan, despite the differences in their demographic

  10. Hidden Markov models in automatic speech recognition

    Science.gov (United States)

    Wrzoskowicz, Adam

    1993-11-01

    This article describes a method for constructing an automatic speech recognition system based on hidden Markov models (HMMs). The author discusses the basic concepts of HMM theory and the application of these models to the analysis and recognition of speech signals. The author provides algorithms which make it possible to train the ASR system and recognize signals on the basis of distinct stochastic models of selected speech sound classes. The author describes the specific components of the system and the procedures used to model and recognize speech. The author discusses problems associated with the choice of optimal signal detection and parameterization characteristics and their effect on the performance of the system. The author presents different options for the choice of speech signal segments and their consequences for the ASR process. The author gives special attention to the use of lexical, syntactic, and semantic information for the purpose of improving the quality and efficiency of the system. The author also describes an ASR system developed by the Speech Acoustics Laboratory of the IBPT PAS. The author discusses the results of experiments on the effect of noise on the performance of the ASR system and describes methods of constructing HMM's designed to operate in a noisy environment. The author also describes a language for human-robot communications which was defined as a complex multilevel network from an HMM model of speech sounds geared towards Polish inflections. The author also added mandatory lexical and syntactic rules to the system for its communications vocabulary.

  11. Search algorithms, hidden labour and information control

    Directory of Open Access Journals (Sweden)

    Paško Bilić

    2016-06-01

    Full Text Available The paper examines some of the processes of the closely knit relationship between Google’s ideologies of neutrality and objectivity and global market dominance. Neutrality construction comprises an important element sustaining the company’s economic position and is reflected in constant updates, estimates and changes to utility and relevance of search results. Providing a purely technical solution to these issues proves to be increasingly difficult without a human hand in steering algorithmic solutions. Search relevance fluctuates and shifts through continuous tinkering and tweaking of the search algorithm. The company also uses third parties to hire human raters for performing quality assessments of algorithmic updates and adaptations in linguistically and culturally diverse global markets. The adaptation process contradicts the technical foundations of the company and calculations based on the initial Page Rank algorithm. Annual market reports, Google’s Search Quality Rating Guidelines, and reports from media specialising in search engine optimisation business are analysed. The Search Quality Rating Guidelines document provides a rare glimpse into the internal architecture of search algorithms and the notions of utility and relevance which are presented and structured as neutral and objective. Intertwined layers of ideology, hidden labour of human raters, advertising revenues, market dominance and control are discussed throughout the paper.

  12. Hidden Structural Codes in Protein Intrinsic Disorder.

    Science.gov (United States)

    Borkosky, Silvia S; Camporeale, Gabriela; Chemes, Lucía B; Risso, Marikena; Noval, María Gabriela; Sánchez, Ignacio E; Alonso, Leonardo G; de Prat Gay, Gonzalo

    2017-10-17

    Intrinsic disorder is a major structural category in biology, accounting for more than 30% of coding regions across the domains of life, yet consists of conformational ensembles in equilibrium, a major challenge in protein chemistry. Anciently evolved papillomavirus genomes constitute an unparalleled case for sequence to structure-function correlation in cases in which there are no folded structures. E7, the major transforming oncoprotein of human papillomaviruses, is a paradigmatic example among the intrinsically disordered proteins. Analysis of a large number of sequences of the same viral protein allowed for the identification of a handful of residues with absolute conservation, scattered along the sequence of its N-terminal intrinsically disordered domain, which intriguingly are mostly leucine residues. Mutation of these led to a pronounced increase in both α-helix and β-sheet structural content, reflected by drastic effects on equilibrium propensities and oligomerization kinetics, and uncovers the existence of local structural elements that oppose canonical folding. These folding relays suggest the existence of yet undefined hidden structural codes behind intrinsic disorder in this model protein. Thus, evolution pinpoints conformational hot spots that could have not been identified by direct experimental methods for analyzing or perturbing the equilibrium of an intrinsically disordered protein ensemble.

  13. Dietary phytate, zinc and hidden zinc deficiency.

    Science.gov (United States)

    Sandstead, Harold H; Freeland-Graves, Jeanne H

    2014-10-01

    Epidemiological data suggest at least one in five humans are at risk of zinc deficiency. This is in large part because the phytate in cereals and legumes has not been removed during food preparation. Phytate, a potent indigestible ligand for zinc prevents it's absorption. Without knowledge of the frequency of consumption of foods rich in phytate, and foods rich in bioavailable zinc, the recognition of zinc deficiency early in the illness may be difficult. Plasma zinc is insensitive to early zinc deficiency. Serum ferritin concentration≤20μg/L is a potential indirect biomarker. Early effects of zinc deficiency are chemical, functional and may be "hidden". The clinical problem is illustrated by 2 studies that involved US Mexican-American children, and US premenopausal women. The children were consuming home diets that included traditional foods high in phytate. The premenopausal women were not eating red meat on a regular basis, and their consumption of phytate was mainly from bran breakfast cereals. In both studies the presence of zinc deficiency was proven by functional responses to controlled zinc treatment. In the children lean-mass, reasoning, and immunity were significantly affected. In the women memory, reasoning, and eye-hand coordination were significantly affected. A screening self-administered food frequency questionnaire for office might help caregiver's identify patients at risk of zinc deficiency. Copyright © 2014 Elsevier GmbH. All rights reserved.

  14. Natural inflation with hidden scale invariance

    Directory of Open Access Journals (Sweden)

    Neil D. Barrie

    2016-05-01

    Full Text Available We propose a new class of natural inflation models based on a hidden scale invariance. In a very generic Wilsonian effective field theory with an arbitrary number of scalar fields, which exhibits scale invariance via the dilaton, the potential necessarily contains a flat direction in the classical limit. This flat direction is lifted by small quantum corrections and inflation is realised without need for an unnatural fine-tuning. In the conformal limit, the effective potential becomes linear in the inflaton field, yielding to specific predictions for the spectral index and the tensor-to-scalar ratio, being respectively: ns−1≈−0.025(N⋆60−1 and r≈0.0667(N⋆60−1, where N⋆≈30–65 is a number of efolds during observable inflation. This predictions are in reasonable agreement with cosmological measurements. Further improvement of the accuracy of these measurements may turn out to be critical in falsifying our scenario.

  15. Detecting hidden sources-STUK/HUT team

    Energy Technology Data Exchange (ETDEWEB)

    Nikkinen, M.; Aarnio, P. [Helsinki Univ. of Technology, Espoo (Finland); Honkamaa, T.; Tiilikainen, H. [Finnish Centre for Radiation and Nuclear Safety, Helsinki (Finland)

    1997-12-31

    The task of the team was to locate and to identify hidden sources in a specified area in Padasjoki Auttoinen village. The team used AB-420 helicopter of the Finnish Frontier Guard. The team had two measuring systems: HPGe system (relative efficiency 18%) and 5`x5` NaI system. The team found two sources in real-time and additional two sources after 24 h analysis time. After the locations and characteristics of the sources were announced it was found out that altogether six sources would have been possible to find using the measured data. The total number of sources was ten. The NaI detector was good at detecting and locating the sources and HPGe was most useful in identification and calculation of the activity estimates. The following development should be made: 1) larger detectors are needed, 2) the software has to be improved. (This has been performed after the exercise) and 3) the navigation must be based on DGPS. visual navigation causes easily gaps between the flight lines and some sources may not be detected. (au).

  16. Gauging hidden symmetries in two dimensions

    International Nuclear Information System (INIS)

    Samtleben, Henning; Weidner, Martin

    2007-01-01

    We initiate the systematic construction of gauged matter-coupled supergravity theories in two dimensions. Subgroups of the affine global symmetry group of toroidally compactified supergravity can be gauged by coupling vector fields with minimal couplings and a particular topological term. The gauge groups typically include hidden symmetries that are not among the target-space isometries of the ungauged theory. The gaugings constructed in this paper are described group-theoretically in terms of a constant embedding tensor subject to a number of constraints which parametrizes the different theories and entirely encodes the gauged Lagrangian. The prime example is the bosonic sector of the maximally supersymmetric theory whose ungauged version admits an affine e 9 global symmetry algebra. The various parameters (related to higher-dimensional p-form fluxes, geometric and non-geometric fluxes, etc.) which characterize the possible gaugings, combine into an embedding tensor transforming in the basic representation of e 9 . This yields an infinite-dimensional class of maximally supersymmetric theories in two dimensions. We work out and discuss several examples of higher-dimensional origin which can be systematically analyzed using the different gradings of e 9

  17. Detecting hidden sources-STUK/HUT team

    Energy Technology Data Exchange (ETDEWEB)

    Nikkinen, M; Aarnio, P [Helsinki Univ. of Technology, Espoo (Finland); Honkamaa, T; Tiilikainen, H [Finnish Centre for Radiation and Nuclear Safety, Helsinki (Finland)

    1998-12-31

    The task of the team was to locate and to identify hidden sources in a specified area in Padasjoki Auttoinen village. The team used AB-420 helicopter of the Finnish Frontier Guard. The team had two measuring systems: HPGe system (relative efficiency 18%) and 5`x5` NaI system. The team found two sources in real-time and additional two sources after 24 h analysis time. After the locations and characteristics of the sources were announced it was found out that altogether six sources would have been possible to find using the measured data. The total number of sources was ten. The NaI detector was good at detecting and locating the sources and HPGe was most useful in identification and calculation of the activity estimates. The following development should be made: 1) larger detectors are needed, 2) the software has to be improved. (This has been performed after the exercise) and 3) the navigation must be based on DGPS. visual navigation causes easily gaps between the flight lines and some sources may not be detected. (au).

  18. Polymer nanotube nanocomposites: synthesis, properties, and applications

    National Research Council Canada - National Science Library

    Mittal, Vikas

    2010-01-01

    ... in these commercially important areas of polymer technology. It sums up recent advances in nanotube composite synthesis technology, provides basic introduction to polymer nanotubes nanocomposite technology for the readers new to this field, provides valuable...

  19. Probing Photosensitization by Functionalized Carbon Nanotubes

    Science.gov (United States)

    Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

  20. Structural transformations of carbon chains inside nanotubes

    International Nuclear Information System (INIS)

    Warner, Jamie H.; Ruemmeli, Mark H.; Bachmatiuk, Alicja; Buechner, Bernd

    2010-01-01

    In situ aberration-corrected high-resolution transmission electron microscopy is used to examine the structural transformations of carbon chains that occur in the interior region of carbon nanotubes. We find electron-beam irradiation leads to the formation of two-dimensional carbon structures that are freely mobile inside the nanotube. The inner diameter of the nanotube influences the structural transformations of the carbon chains. As the diameter of the nanotube increases, electron-beam irradiation leads to curling of the chains and eventually the formation of closed looped structures. The closed looped structures evolve into spherical fullerenelike structures that exhibit translational motion inside the nanotubes and also coalesce to form larger nanotube structures. These results demonstrate the use of carbon nanotubes as test tubes for growing small carbon nanotubes within the interior by using only electron-beam irradiation at 80 kV.

  1. Hidden-Sector Dynamics and the Supersymmetric Seesaw

    CERN Document Server

    Campbell, Bruce A; Maybury, David W

    2008-01-01

    In light of recent analyses that have shown that nontrivial hidden-sector dynamics in models of supersymmetry breaking can lead to a significant impact on the predicted low-energy supersymmetric spectrum, we extend these studies to consider hidden-sector effects in extensions of the MSSM to include a seesaw model for neutrino masses. A dynamical hidden sector in an interval of mass scales below the seesaw scale would yield renormalization-group running involving both the anomalous dimension from the hidden sector and the seesaw-extended MSSM renormalization group equations (RGEs). These effects interfere in general, altering the generational mixing of the sleptons, and allowing for a substantial change to the expected level of charged-lepton flavour violation in seesaw-extended MSSM models. These results provide further support for recent theoretical observations that knowledge of the hidden sector is required in order to make concrete low-energy predictions, if the hidden sector is strongly coupled. In parti...

  2. Carbon nanotube biosensors

    Science.gov (United States)

    Tîlmaciu, Carmen-Mihaela; Morris, May C.

    2015-01-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we describe their structural and physical properties, functionalization and cellular uptake, biocompatibility, and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers. PMID:26579509

  3. Functionalization of Carbon Nanotubes

    Science.gov (United States)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2009-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2 or F2 or CnHm) is irradiated to provide a cold plasma of selected target species particles, such as atomic H or F, in a first chamber. The target species particles are d irected toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target species particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec. *Discrimination against non-target species is provided by (i) use of a target species having a lifetime that is much greater than a lifetime of a non-target species and/or (2) use of an applied magnetic field to discriminate between charged particle trajectories for target species and for non-target species.

  4. Carbon Nanotube Electron Gun

    Science.gov (United States)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2013-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  5. Carbon Nanotube Biosensors

    Directory of Open Access Journals (Sweden)

    Carmen-Mihaela eTilmaciu

    2015-10-01

    Full Text Available Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

  6. Carbon Nanotube based Nanotechnolgy

    Science.gov (United States)

    Meyyappan, M.

    2000-10-01

    Carbon nanotube(CNT) was discovered in the early 1990s and is an off-spring of C60(the fullerene or buckyball). CNT, depending on chirality and diameter, can be metallic or semiconductor and thus allows formation of metal-semiconductor and semiconductor-semiconductor junctions. CNT exhibits extraordinary electrical and mechanical properties and offers remarkable potential for revolutionary applications in electronics devices, computing and data storage technology, sensors, composites, storage of hydrogen or lithium for battery development, nanoelectromechanical systems(NEMS), and as tip in scanning probe microscopy(SPM) for imaging and nanolithography. Thus the CNT synthesis, characterization and applications touch upon all disciplines of science and engineering. A common growth method now is based on CVD though surface catalysis is key to synthesis, in contrast to many CVD applications common in microelectronics. A plasma based variation is gaining some attention. This talk will provide an overview of CNT properties, growth methods, applications, and research challenges and opportunities ahead.

  7. Electronics with carbon nanotubes

    International Nuclear Information System (INIS)

    Avouris, P.

    2007-01-01

    From mobile phones and laptops to Xboxes and iPods, it is difficult to think of any aspect of modern life that has not been touched by developments in electronics, computing and communications over the last few decades. Many of these technological advances have arisen from our ability to create ever smaller electronic devices, in particular silicon-based field effect transistors (FETs), which has led to denser, faster and less power-hungry circuits. The problem is that this device miniaturization, or 'scaling', cannot continue forever. Fundamental scientific and technological limitations exist that will make it impossible to build better performing silicon devices below a certain size. This potential show-stopper has inspired a worldwide effort to develop alternative device technologies based on 1D materials or those that exploit the spin, as well as the charge, of electrons. One promising and, in principle, simpler approach is to maintain the operating concept of today's silicon-based FETs but to replace a key component of the device - the semiconducting silicon channel - with 1D nanostructures that have much more versatile electrical-transport properties. Among the different 1D materials that have been developed, those with the most desirable properties are 'single-walled' carbon nanotubes, which were first created in 1993 by Sumio Ijima at the NEC Fundamental Research Laboratory in Tsukuba, Japan, and by Donald Bethune of IBM's Almaden Research Center in California. These materials are hollow tubes made from rolled up sheets of carbon just one atom thick, otherwise known as graphene. In the March issue of Physics World, Phaedon Avouris discusses some of the many properties and applications of carbon nanotubes, which he describes as an 'engineer's dream' because of their exceptionally high strength and heat conduction. (U.K.)

  8. A single hidden layer feedforward network with only one neuron in the hidden layer can approximate any univariate function

    OpenAIRE

    Guliyev , Namig; Ismailov , Vugar

    2016-01-01

    The possibility of approximating a continuous function on a compact subset of the real line by a feedforward single hidden layer neural network with a sigmoidal activation function has been studied in many papers. Such networks can approximate an arbitrary continuous function provided that an unlimited number of neurons in a hidden layer is permitted. In this paper, we consider constructive approximation on any finite interval of $\\mathbb{R}$ by neural networks with only one neuron in the hid...

  9. Dispersions of Carbon nanotubes in Polymer Matrices

    Science.gov (United States)

    Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

    2010-01-01

    Dispersions of carbon nanotubes exhibiting long term stability are based on a polymer matrix having moieties therein which are capable of a donor-acceptor complexation with carbon nanotubes. The carbon nanotubes are introduced into the polymer matrix and separated therein by standard means. Nanocomposites produced from these dispersions are useful in the fabrication of structures, e.g., lightweight aerospace structures.

  10. Computational modelling of the flow of viscous fluids in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Khosravian, N [Computational Physical Sciences Research Laboratory, Department of Nano-Science, Institute for Research in Fundamental Sciences (IPM), PO Box 19395-5531, Tehran (Iran, Islamic Republic of); Rafii-Tabar, H [Computational Physical Sciences Research Laboratory, Department of Nano-Science, Institute for Research in Fundamental Sciences (IPM), PO Box 19395-5531, Tehran (Iran, Islamic Republic of)

    2007-11-21

    Carbon nanotubes will have extensive application in all areas of nano-technology, and in particular in the field of nano-fluidics, wherein they can be used for molecular separation, nano-scale filtering and as nano-pipes for conveying fluids. In the field of nano-medicine, nanotubes can be functionalized with various types of receptors to act as bio-sensors for the detection and elimination of cancer cells, or be used as bypasses and even neural connections. Modelling fluid flow inside nanotubes is a very challenging problem, since there is a complex interplay between the motion of the fluid and the stability of the walls. A critical issue in the design of nano-fluidic devices is the induced vibration of the walls, due to the fluid flow, which can promote structural instability. It has been established that the resonant frequencies depend on the flow velocity. We have studied, for the first time, the flow of viscous fluids through multi-walled carbon nanotubes, using the Euler-Bernoulli classical beam theory to model the nanotube as a continuum structure. Our aim has been to compute the effect of the fluid flow on the structural stability of the nanotubes, without having to consider the details of the fluid-walls interaction. The variations of the resonant frequencies with the flow velocity are obtained for both unembedded nanotubes, and when they are embedded in an elastic medium. It is found that a nanotube conveying a viscous fluid is more stable against vibration-induced buckling than a nanotube conveying a non-viscous fluid, and that the aspect ratio plays the same role in both cases.

  11. Computational modelling of the flow of viscous fluids in carbon nanotubes

    International Nuclear Information System (INIS)

    Khosravian, N; Rafii-Tabar, H

    2007-01-01

    Carbon nanotubes will have extensive application in all areas of nano-technology, and in particular in the field of nano-fluidics, wherein they can be used for molecular separation, nano-scale filtering and as nano-pipes for conveying fluids. In the field of nano-medicine, nanotubes can be functionalized with various types of receptors to act as bio-sensors for the detection and elimination of cancer cells, or be used as bypasses and even neural connections. Modelling fluid flow inside nanotubes is a very challenging problem, since there is a complex interplay between the motion of the fluid and the stability of the walls. A critical issue in the design of nano-fluidic devices is the induced vibration of the walls, due to the fluid flow, which can promote structural instability. It has been established that the resonant frequencies depend on the flow velocity. We have studied, for the first time, the flow of viscous fluids through multi-walled carbon nanotubes, using the Euler-Bernoulli classical beam theory to model the nanotube as a continuum structure. Our aim has been to compute the effect of the fluid flow on the structural stability of the nanotubes, without having to consider the details of the fluid-walls interaction. The variations of the resonant frequencies with the flow velocity are obtained for both unembedded nanotubes, and when they are embedded in an elastic medium. It is found that a nanotube conveying a viscous fluid is more stable against vibration-induced buckling than a nanotube conveying a non-viscous fluid, and that the aspect ratio plays the same role in both cases

  12. Next generation sequencing reveals the hidden diversity of zooplankton assemblages.

    Directory of Open Access Journals (Sweden)

    Penelope K Lindeque

    Full Text Available BACKGROUND: Zooplankton play an important role in our oceans, in biogeochemical cycling and providing a food source for commercially important fish larvae. However, difficulties in correctly identifying zooplankton hinder our understanding of their roles in marine ecosystem functioning, and can prevent detection of long term changes in their community structure. The advent of massively parallel next generation sequencing technology allows DNA sequence data to be recovered directly from whole community samples. Here we assess the ability of such sequencing to quantify richness and diversity of a mixed zooplankton assemblage from a productive time series site in the Western English Channel. METHODOLOGY/PRINCIPLE FINDINGS: Plankton net hauls (200 µm were taken at the Western Channel Observatory station L4 in September 2010 and January 2011. These samples were analysed by microscopy and metagenetic analysis of the 18S nuclear small subunit ribosomal RNA gene using the 454 pyrosequencing platform. Following quality control a total of 419,041 sequences were obtained for all samples. The sequences clustered into 205 operational taxonomic units using a 97% similarity cut-off. Allocation of taxonomy by comparison with the National Centre for Biotechnology Information database identified 135 OTUs to species level, 11 to genus level and 1 to order, <2.5% of sequences were classified as unknowns. By comparison a skilled microscopic analyst was able to routinely enumerate only 58 taxonomic groups. CONCLUSIONS: Metagenetics reveals a previously hidden taxonomic richness, especially for Copepoda and hard-to-identify meroplankton such as Bivalvia, Gastropoda and Polychaeta. It also reveals rare species and parasites. We conclude that Next Generation Sequencing of 18S amplicons is a powerful tool for elucidating the true diversity and species richness of zooplankton communities. While this approach allows for broad diversity assessments of plankton it may

  13. Hidden burden of malaria in Indian women

    Directory of Open Access Journals (Sweden)

    Sharma Vinod P

    2009-12-01

    Full Text Available Abstract Malaria is endemic in India with an estimated 70-100 million cases each year (1.6-1.8 million reported by NVBDCP; of this 50-55% are Plasmodium vivax and 45-50% Plasmodium falciparum. A recent study on malaria in pregnancy reported from undivided Madhya Pradesh state (includes Chhattisgarh state, that an estimated over 220,000 pregnant women contract malaria infection each year. Malaria in pregnancy caused- abortions 34.5%; stillbirths 9%; and maternal deaths 0.45%. Bulk of this tragic outcome can be averted by following the Roll Back Malaria/WHO recommendations of the use of malaria prevention i.e. indoor residual spraying (IRS/insecticide-treated bed nets (ITN preferably long-lasting treated bed nets (LLIN; intermittent preventive therapy (IPT; early diagnosis, prompt and complete treatment using microscopic/malaria rapid diagnostics test (RDT and case management. High incidence in pregnancy has arisen because of malaria surveillance lacking coverage, lack of age and sex wise data, staff shortages, and intermittent preventive treatment (IPT applicable in high transmission states/pockets is not included in the national drug policy- an essential component of fighting malaria in pregnancy in African settings. Inadequate surveillance and gross under-reporting has been highlighted time and again for over three decades. As a result the huge problem of malaria in pregnancy reported occasionally by researchers has remained hidden. Malaria in pregnancy may quicken severity in patients with drug resistant parasites, anaemia, endemic poverty, and malnutrition. There is, therefore, urgent need to streamline malaria control strategies to make a difference in tackling this grim scenario in human health.

  14. Hydrogeophysical investigations at Hidden Dam, Raymond, California

    Science.gov (United States)

    Minsley, Burke J.; Burton, Bethany L.; Ikard, Scott; Powers, Michael H.

    2011-01-01

    Self-potential and direct current resistivity surveys are carried out at the Hidden Dam site in Raymond, California to assess present-day seepage patterns and better understand the hydrogeologic mechanisms that likely influence seepage. Numerical modeling is utilized in conjunction with the geophysical measurements to predict variably-saturated flow through typical two-dimensional dam cross-sections as a function of reservoir elevation. Several different flow scenarios are investigated based on the known hydrogeology, as well as information about typical subsurface structures gained from the resistivity survey. The flow models are also used to simulate the bulk electrical resistivity in the subsurface under varying saturation conditions, as well as the self-potential response using petrophysical relationships and electrokinetic coupling equations.The self-potential survey consists of 512 measurements on the downstream area of the dam, and corroborates known seepage areas on the northwest side of the dam. Two direct-current resistivity profiles, each approximately 2,500 ft (762 m) long, indicate a broad sediment channel under the northwest side of the dam, which may be a significant seepage pathway through the foundation. A focusing of seepage in low-topography areas downstream of the dam is confirmed from the numerical flow simulations, which is also consistent with past observations. Little evidence of seepage is identified from the self-potential data on the southeast side of the dam, also consistent with historical records, though one possible area of focused seepage is identified near the outlet works. Integration of the geophysical surveys, numerical modeling, and observation well data provides a framework for better understanding seepage at the site through a combined hydrogeophysical approach.

  15. 'Hidden messages' emerging from Afrocentric management perspectives

    Directory of Open Access Journals (Sweden)

    H. Van den Heuvel

    2008-12-01

    Full Text Available Purpose: This paper aims to examine how 'African management' discourse has emerged in South Africa. Altogether, it has stimulated debates - sometimes in controversial ways - on 'taboo issues', e.g. relating to 'cultural diversity' and 'ethnicity'. The stimulation of such debates within organisations is probably a more valuable contribution than a static, essentialised 'African identity' that it proclaims. Design/Methodology/Approach: The paper draws on a qualitative research project conducted in South Africa in 2003-2004. Its relevance lies in gaining in-depth insights into ('non-western' local management discourse. It seeks to contribute to the body of knowledge on political and cultural contexts in which South African organizations operate, and how they impact on local management perspectives, and vice versa. Findings: The research findings make clear how and under what circumstances 'African management' discourse has come about in South Africa, and how it could be interpreted. Implications: 'African management' advocates allegedly attempt to revise dominant management thinking and promote 'humane-ness' and participatory decision-making in South African organisations, in search of a contextualised management approach. Amongst others, it has produced new meanings of 'Africanness' and has opened up space for 'hidden messages', resentments and aspirations to become openly articulated. This throws another light on phenomena such as cultural diversity and ethnicity that usually tend to be 'neutralised'. This may turn out to be far healthier for blooming organisational cultures in South Africa than relentlessly hammering on prescribed 'corporate values'. Originality/Value: This paper informs the reader in detail about the emergence and evolvement of 'African management' discourse in South Africa. It is a unique attempt to develop an interpretative viewpoint on this intriguing phenomenon that offers a potentially valuable contribution in reading

  16. Identifying hidden voice and video streams

    Science.gov (United States)

    Fan, Jieyan; Wu, Dapeng; Nucci, Antonio; Keralapura, Ram; Gao, Lixin

    2009-04-01

    Given the rising popularity of voice and video services over the Internet, accurately identifying voice and video traffic that traverse their networks has become a critical task for Internet service providers (ISPs). As the number of proprietary applications that deliver voice and video services to end users increases over time, the search for the one methodology that can accurately detect such services while being application independent still remains open. This problem becomes even more complicated when voice and video service providers like Skype, Microsoft, and Google bundle their voice and video services with other services like file transfer and chat. For example, a bundled Skype session can contain both voice stream and file transfer stream in the same layer-3/layer-4 flow. In this context, traditional techniques to identify voice and video streams do not work. In this paper, we propose a novel self-learning classifier, called VVS-I , that detects the presence of voice and video streams in flows with minimum manual intervention. Our classifier works in two phases: training phase and detection phase. In the training phase, VVS-I first extracts the relevant features, and subsequently constructs a fingerprint of a flow using the power spectral density (PSD) analysis. In the detection phase, it compares the fingerprint of a flow to the existing fingerprints learned during the training phase, and subsequently classifies the flow. Our classifier is not only capable of detecting voice and video streams that are hidden in different flows, but is also capable of detecting different applications (like Skype, MSN, etc.) that generate these voice/video streams. We show that our classifier can achieve close to 100% detection rate while keeping the false positive rate to less that 1%.

  17. Investigation of the interfacial properties of polyurethane/carbon nanotube hybrid composites: A molecular dynamics study

    Science.gov (United States)

    Goclon, Jakub; Panczyk, Tomasz; Winkler, Krzysztof

    2018-03-01

    Considering the varied applications of hybrid polymer/carbon nanotube composites and the constant progress in the synthesis methods of such materials, we report a theoretical study of interfacial layer formation between pristine single-wall carbon nanotubes (SWCNTs) and polyurethane (PU) using molecular dynamic simulations. We vary the SWCNT diameter and the number of PU chains to examine various PU-SWCNT interaction patterns. Our simulations indicate the important role of intra-chain forces in PU. No regular polymeric structures could be identified on the carbon nanotube surface during the simulations. We find that increasing the SWCNT diameter results in stronger polymer binding. However, higher surface loadings of PU lead to stronger interpenetration by the polymeric segments; this effect is more apparent for SWCNTs with small diameters. Our core finding is that the attached PU binds most strongly to the carbon nanotubes with the largest diameters. Polymer dynamics reveal the loose distribution of PU chains in these systems.

  18. Spin-orbit coupling and the static polarizability of single-wall carbon nanotubes

    International Nuclear Information System (INIS)

    Diniz, Ginetom S.; Ulloa, Sergio E.

    2014-01-01

    We calculate the static longitudinal polarizability of single-wall carbon tubes in the long wavelength limit taking into account spin-orbit effects. We use a four-orbital orthogonal tight-binding formalism to describe the electronic states and the random phase approximation to calculate the dielectric function. We study the role of both the Rashba as well as the intrinsic spin-orbit interactions on the longitudinal dielectric response, i.e., when the probing electric field is parallel to the nanotube axis. The spin-orbit interaction modifies the nanotube electronic band dispersions, which may especially result in a small gap opening in otherwise metallic tubes. The bandgap size and state features, the result of competition between Rashba and intrinsic spin-orbit interactions, result in drastic changes in the longitudinal static polarizability of the system. We discuss results for different nanotube types and the dependence on nanotube radius and spin-orbit couplings.

  19. Spin-orbit coupling and the static polarizability of single-wall carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Diniz, Ginetom S., E-mail: ginetom@gmail.com; Ulloa, Sergio E. [Department of Physics and Astronomy and Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701-2979 (United States)

    2014-07-14

    We calculate the static longitudinal polarizability of single-wall carbon tubes in the long wavelength limit taking into account spin-orbit effects. We use a four-orbital orthogonal tight-binding formalism to describe the electronic states and the random phase approximation to calculate the dielectric function. We study the role of both the Rashba as well as the intrinsic spin-orbit interactions on the longitudinal dielectric response, i.e., when the probing electric field is parallel to the nanotube axis. The spin-orbit interaction modifies the nanotube electronic band dispersions, which may especially result in a small gap opening in otherwise metallic tubes. The bandgap size and state features, the result of competition between Rashba and intrinsic spin-orbit interactions, result in drastic changes in the longitudinal static polarizability of the system. We discuss results for different nanotube types and the dependence on nanotube radius and spin-orbit couplings.

  20. Influence of the contact geometry on single-walled carbon nanotube/Si photodetector response

    Science.gov (United States)

    Scagliotti, Mattia; Salvato, Matteo; De Crescenzi, Maurizio; Boscardin, Maurizio; Castrucci, Paola

    2018-03-01

    A systematic study of the optical response of photodetectors based on carbon nanotube/Si heterojunctions is performed by measuring the responsivity, the detectivity and the time response of the devices with different contact configurations. The sensors are obtained by dry transferring single-walled carbon nanotube films on the surface of n-doped Si substrate provided with a multifinger contact geometry. The experimental data show a consistent improvement of the photodetector parameters with the increase of the number of fingers without affecting the carbon nanotube film thickness for increase its optical transmittance as in previous experiments. The role of the electrical resistance of the carbon nanotube film is discussed. The obtained results confirm the method and suggest new perspectives in the use of nanostructured materials as part of semiconducting optical devices.

  1. Recent advances in molecular electronics based on carbon nanotubes.

    Science.gov (United States)

    Bourgoin, Jean-Philippe; Campidelli, Stéphane; Chenevier, Pascale; Derycke, Vincent; Filoramo, Arianna; Goffman, Marcelo F

    2010-01-01

    Carbon nanotubes (CNTs) have exceptional physical properties that make them one of the most promising building blocks for future nanotechnologies. They may in particular play an important role in the development of innovative electronic devices in the fields of flexible electronics, ultra-high sensitivity sensors, high frequency electronics, opto-electronics, energy sources and nano-electromechanical systems (NEMS). Proofs of concept of several high performance devices already exist, usually at the single device level, but there remain many serious scientific issues to be solved before the viability of such routes can be evaluated. In particular, the main concern regards the controlled synthesis and positioning of nanotubes. In our opinion, truly innovative use of these nano-objects will come from: (i) the combination of some of their complementary physical properties, such as combining their electrical and mechanical properties, (ii) the combination of their properties with additional benefits coming from other molecules grafted on the nanotubes, and (iii) the use of chemically- or bio-directed self-assembly processes to allow the efficient combination of several devices into functional arrays or circuits. In this article, we outline the main issues concerning the development of carbon nanotubes based electronics applications and review our recent results in the field.

  2. Increased taxon sampling reveals thousands of hidden orthologs in flatworms

    Science.gov (United States)

    2017-01-01

    Gains and losses shape the gene complement of animal lineages and are a fundamental aspect of genomic evolution. Acquiring a comprehensive view of the evolution of gene repertoires is limited by the intrinsic limitations of common sequence similarity searches and available databases. Thus, a subset of the gene complement of an organism consists of hidden orthologs, i.e., those with no apparent homology to sequenced animal lineages—mistakenly considered new genes—but actually representing rapidly evolving orthologs or undetected paralogs. Here, we describe Leapfrog, a simple automated BLAST pipeline that leverages increased taxon sampling to overcome long evolutionary distances and identify putative hidden orthologs in large transcriptomic databases by transitive homology. As a case study, we used 35 transcriptomes of 29 flatworm lineages to recover 3427 putative hidden orthologs, some unidentified by OrthoFinder and HaMStR, two common orthogroup inference algorithms. Unexpectedly, we do not observe a correlation between the number of putative hidden orthologs in a lineage and its “average” evolutionary rate. Hidden orthologs do not show unusual sequence composition biases that might account for systematic errors in sequence similarity searches. Instead, gene duplication with divergence of one paralog and weak positive selection appear to underlie hidden orthology in Platyhelminthes. By using Leapfrog, we identify key centrosome-related genes and homeodomain classes previously reported as absent in free-living flatworms, e.g., planarians. Altogether, our findings demonstrate that hidden orthologs comprise a significant proportion of the gene repertoire in flatworms, qualifying the impact of gene losses and gains in gene complement evolution. PMID:28400424

  3. Nitrotyrosine adsorption on carbon nanotube: a density functional theory study

    Science.gov (United States)

    Majidi, R.; Karami, A. R.

    2014-05-01

    We have studied the effect of nitrotyrosine on electronic properties of different single-wall carbon nanotubes by density functional theory. Optimal adsorption configurations of nitrotyrosine adsorbed on carbon nanotube have been determined by calculation of adsorption energy. Adsorption energies indicate that nitrotyrosine is chemisorbed on carbon nanotubes. It is found that the nitrotyrosine adsorption modifies the electronic properties of the semiconducting carbon nanotubes significantly and these nanotubes become n-type semiconductors, while the effect of nitrotyrosine on metallic carbon nanotubes is not considerable and these nanotubes remain metallic. Results clarify sensitivity of carbon nanotubes to nitrotyrosine adsorption and suggest the possibility of using carbon nanotubes as biosensor for nitrotyrosine detection.

  4. Theoretical properties of carbon nanotubes

    International Nuclear Information System (INIS)

    Palser, A.H.

    2000-01-01

    Carbon nanotubes are invariably terminated with hemi-fullerene caps. In order to investigate the effect of these caps on the electronic structure, a method is developed to enumerate every hemi-fullerene cap which is commensurate with a given nanotube body. This algorithm is then applied to nanotubes for which I + m ≤ 25. The results of this algorithm are then used to study the effects of caps with different symmetries on the electronic structure of metallic and semi-conducting nanotubes within the Hueckel model. It is found that caps can cause localised and resonance states, although the likelihood of localised states occurring in capped metallic nanotubes is shown to be small. In addition, caps induce a non-uniform charge distribution, in which negative charge tends to accumulate on pentagon vertices. The thesis ends by describing two new density matrix methods for performing linear-scaling electronic-structure calculations within the independent electron approximation. Example calculations demonstrate that these methods provide efficient and robust ways of performing linear-scaling calculations, either grand canonically (at a fixed chemical potential) or canonically (at a fixed electron count). (author)

  5. EDITORIAL: Focus on Carbon Nanotubes

    Science.gov (United States)

    2003-09-01

    The study of carbon nanotubes, since their discovery by Iijima in 1991, has become a full research field with significant contributions from all areas of research in solid-state and molecular physics and also from chemistry. This Focus Issue in New Journal of Physics reflects this active research, and presents articles detailing significant advances in the production of carbon nanotubes, the study of their mechanical and vibrational properties, electronic properties and optical transitions, and electrical and transport properties. Fundamental research, both theoretical and experimental, represents part of this progress. The potential applications of nanotubes will rely on the progress made in understanding their fundamental physics and chemistry, as presented here. We believe this Focus Issue will be an excellent guide for both beginners and experts in the research field of carbon nanotubes. It has been a great pleasure to edit the many excellent contributions from Europe, Japan, and the US, as well from a number of other countries, and to witness the remarkable effort put into the manuscripts by the contributors. We thank all the authors and referees involved in the process. In particular, we would like to express our gratitude to Alexander Bradshaw, who invited us put together this Focus Issue, and to Tim Smith and the New Journal of Physics staff for their extremely efficient handling of the manuscripts. Focus on Carbon Nanotubes Contents Transport theory of carbon nanotube Y junctions R Egger, B Trauzettel, S Chen and F Siano The tubular conical helix of graphitic boron nitride F F Xu, Y Bando and D Golberg Formation pathways for single-wall carbon nanotube multiterminal junctions Inna Ponomareva, Leonid A Chernozatonskii, Antonis N Andriotis and Madhu Menon Synthesis and manipulation of carbon nanotubes J W Seo, E Couteau, P Umek, K Hernadi, P Marcoux, B Lukic, Cs Mikó, M Milas, R Gaál and L Forró Transitional behaviour in the transformation from active end

  6. What Lies Within: Using Radiopharmaceuticals to Reveal and Target Diseases Hidden Inside the Human Body

    International Nuclear Information System (INIS)

    Jawerth, Nicole

    2014-01-01

    The ability to pinpoint the location and size of a cancerous mass hidden inside of a patient’s body was unthinkable less than 100 years ago. Today, with the help of special scanning machines, doctors are able to use radioactive drugs known as radiopharmaceuticals to get a glimpse inside the human body, and these pharmaceuticals can even be used in treating many health conditions. In nuclear medicine, radiopharmaceuticals play an essential role for minimally invasive diagnostic, treatment and care management procedures for many diseases, especially cancer, as well as for relieving pain associated with certain cancers

  7. Metal Nanoparticle Catalysts for Carbon Nanotube Growth

    Science.gov (United States)

    Pierce, Benjamin F.

    2003-01-01

    Work this summer involved and new and unique process for producing the metal nanoparticle catalysts needed for carbon nanotube (CNT) growth. There are many applications attributed to CNT's, and their properties have deemed them to be a hot spot in research today. Many groups have demonstrated the versatility in CNT's by exploring a wide spectrum of roles that these nanotubes are able to fill. A short list of such promising applications are: nanoscaled electronic circuitry, storage media, chemical sensors, microscope enhancement, and coating reinforcement. Different methods have been used to grow these CNT's. Some examples are laser ablation, flame synthesis, or furnace synthesis. Every single approach requires the presence of a metal catalyst (Fe, Co, and Ni are among the best) that is small enough to produce a CNT. Herein lies the uniqueness of this work. Microemulsions (containing inverse micelles) were used to generate these metal particles for subsequent CNT growth. The goal of this summer work was basically to accomplish as much preliminary work as possible. I strived to pinpoint which variable (experimental process, metal product, substrate, method of application, CVD conditions, etc.) was the determining factor in the results. The resulting SEM images were sufficient for the appropriate comparisons to be made. The future work of this project consists of the optimization of the more promising experimental procedures and further exploration onto what exactly dictated the results.

  8. Functionalized carbon nanotubes containing isocyanate groups

    International Nuclear Information System (INIS)

    Zhao Chungui; Ji Lijun; Liu Huiju; Hu Guangjun; Zhang Shimin; Yang Mingshu; Yang Zhenzhong

    2004-01-01

    Functionalized carbon nanotubes containing isocyanate groups can extend the nanotube chemistry, and may promote their many potential applications such as in polymer composites and coatings. This paper describes a facile method to prepare functionalized carbon nanotubes containing highly reactive isocyanate groups on its surface via the reaction between toluene 2,4-diisocyanate and carboxylated carbon nanotubes. Fourier-transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed that reactive isocyanate groups were covalently attached to carbon nanotubes. The content of isocyanate groups were determined by chemical titration and thermogravimetric analysis (TGA)

  9. All carbon nanotubes are not created equal

    International Nuclear Information System (INIS)

    Geohegan, David B.; Puretzky, Alexander A.; Rouleau, Christopher M.

    2010-01-01

    This chapter presents the various factors that enter into consideration when choosing the source of carbon nanotubes for a specific application. Carbon nanotubes are giant molecules made of pure carbon. They have captured the imagination of the scientific community by the unique structure that provides superior physical, chemical, and electrical properties. However, a surprisingly wide disparity exists between the intrinsic properties determined under ideal conditions and the properties that carbon nanotubes exhibit in real world situations. The lack of uniformity in carbon nanotube properties is likely to be the main obstacle holding back the development of carbon nanotube applications. This tutorial addresses the nonuniformity of carbon nanotube properties from the synthesis standpoint. This synthesis-related nonuniformity is on top of the intrinsic chirality distribution that gives the ∼1:2 ratio of metallic to semiconducting nanotubes. From the standpoint of carbon bonding chemistry the variation in the quality and reproducibility of carbon nanotube materials is not unexpected. It is an intrinsic feature that is related to the metastability of carbon structures. The extent to which this effect is manifested in carbon nanotube formation is governed by the type and the kinetics of the carbon nanotube synthesis reaction. Addressing this variation is critical if nanotubes are to live up to the potential already demonstrated by their phenomenal physical properties.

  10. 1/f noise in carbon nanotubes

    International Nuclear Information System (INIS)

    Collins, Philip G.; Fuhrer, M. S.; Zettl, A.

    2000-01-01

    The electrical noise characteristics of single-walled carbon nanotubes have been investigated. For all three cases of individual isolated nanotubes, thin films of interconnected nanotubes, and bulk nanotube mats, anomalously large bias-dependent 1/f noise is found. The noise magnitude greatly exceeds that commonly observed in metal films, carbon resistors, or even carbon fibers with comparable resistances. A single empirical expression describes the noise for all nanotube samples, suggesting a common noise-generating mechanism proportional only to the number of nanotubes in the conductor. We consider likely sources of the fluctuations, and consequences for electronic applications of nanotubes if the excessive noise cannot be suppressed. (c) 2000 American Institute of Physics

  11. Infinite hidden conditional random fields for human behavior analysis.

    Science.gov (United States)

    Bousmalis, Konstantinos; Zafeiriou, Stefanos; Morency, Louis-Philippe; Pantic, Maja

    2013-01-01

    Hidden conditional random fields (HCRFs) are discriminative latent variable models that have been shown to successfully learn the hidden structure of a given classification problem (provided an appropriate validation of the number of hidden states). In this brief, we present the infinite HCRF (iHCRF), which is a nonparametric model based on hierarchical Dirichlet processes and is capable of automatically learning the optimal number of hidden states for a classification task. We show how we learn the model hyperparameters with an effective Markov-chain Monte Carlo sampling technique, and we explain the process that underlines our iHCRF model with the Restaurant Franchise Rating Agencies analogy. We show that the iHCRF is able to converge to a correct number of represented hidden states, and outperforms the best finite HCRFs--chosen via cross-validation--for the difficult tasks of recognizing instances of agreement, disagreement, and pain. Moreover, the iHCRF manages to achieve this performance in significantly less total training, validation, and testing time.

  12. Explore the Buffering Effects of Perceived Hidden Inflation on Survival of Mobile Phone Service Providers in Taiwan

    Directory of Open Access Journals (Sweden)

    Sheng-Wen Liu

    2017-04-01

    Full Text Available The purpose of this study is to examine the moderating role of perceived hidden inflation on the relationships between service quality, brand trust and brand loyalty. All data collected from the target population are analyzed through two-step structural equation modeling (SEM and moderated multiple regression (MMR to examine the hypotheses. 1,050 questionnaires are randomly distributed at 21 telecommunication service stores in Taiwan. Findings indicated that service quality has no direct impact on behavioral loyalty but it has a significant indirect impact on behavioral loyalty through brand trust or attitudinal loyalty. Moreover, findings identify perceived hidden inflation as the moderating role in the service quality–brand trust–brand loyalty chain. Besides the need for empirical confirmation of the hypotheses given, finally, there are several practical implications for service marketers and future research directions for scholars.

  13. Hidden beauty baryon states in the local hidden gauge approach with heavy quark spin symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, C.W.; Oset, E. [Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigacion de Paterna, Departamento de Fisica Teorica and IFIC, Valencia (Spain)

    2013-11-15

    Using a coupled-channel unitary approach, combining the heavy quark spin symmetry and the dynamics of the local hidden gauge, we investigate the meson-baryon interaction with hidden beauty and obtain several new states of N around 11 GeV. We consider the basis of states {eta}{sub b} N, {Upsilon};N, B {Lambda}{sub b}, B {Sigma}{sub b}, B{sup *}{Lambda}{sub b}, B{sup *}{Sigma}{sub b}, B{sup *}{Sigma}{sub b}{sup *} and find four basic bound states which correspond to B {Sigma}{sub b}, B {Sigma}{sub b}{sup *}, B{sup *}{Sigma}{sub b} and B{sup *}{Sigma}{sub b}{sup *}, decaying mostly into {eta}{sub b} N and {Upsilon}N and with a binding energy about 50-130 MeV with respect to the thresholds of the corresponding channel. All of them have isospin I = 1/2, and we find no bound states or resonances in I = 3/2. The B {Sigma}{sub b} state appears in J = 1/2, the B {Sigma}{sub b}{sup *} in J = 3/2, the B{sup *}{Sigma}{sub b} appears nearly degenerate in J = 1/2, 3/2 and the B{sup *}{Sigma}{sub b}{sup *} appears nearly degenerate in J = 1/2, 3/2, 5/2. These states have a width from 2-110 MeV, with conservative estimates of uncertainties, except for the one in J = 5/2 which has zero width since it cannot decay into any of the states of the basis chosen. We make generous estimates of the uncertainties and find that within very large margins these states appear bound. (orig.)

  14. Carbon nanotube computer.

    Science.gov (United States)

    Shulaker, Max M; Hills, Gage; Patil, Nishant; Wei, Hai; Chen, Hong-Yu; Wong, H-S Philip; Mitra, Subhasish

    2013-09-26

    The miniaturization of electronic devices has been the principal driving force behind the semiconductor industry, and has brought about major improvements in computational power and energy efficiency. Although advances with silicon-based electronics continue to be made, alternative technologies are being explored. Digital circuits based on transistors fabricated from carbon nanotubes (CNTs) have the potential to outperform silicon by improving the energy-delay product, a metric of energy efficiency, by more than an order of magnitude. Hence, CNTs are an exciting complement to existing semiconductor technologies. Owing to substantial fundamental imperfections inherent in CNTs, however, only very basic circuit blocks have been demonstrated. Here we show how these imperfections can be overcome, and demonstrate the first computer built entirely using CNT-based transistors. The CNT computer runs an operating system that is capable of multitasking: as a demonstration, we perform counting and integer-sorting simultaneously. In addition, we implement 20 different instructions from the commercial MIPS instruction set to demonstrate the generality of our CNT computer. This experimental demonstration is the most complex carbon-based electronic system yet realized. It is a considerable advance because CNTs are prominent among a variety of emerging technologies that are being considered for the next generation of highly energy-efficient electronic systems.

  15. Growth of uranyl hydroxide nanowires and nanotubes with electrodeposition method

    International Nuclear Information System (INIS)

    Wang Lin; Yuan Liyong; Chai Zhifang; Shi Weiqun

    2013-01-01

    Actinides nanomaterials have great potential applications in fabrication of novel nuclear fuel and spent fuel reprocessing in advanced nuclear energy system. However, the relative research so far still lacks systematic investigation on the synthetic methods for actinides nanomaterials. In this work, we use track-etched membranes as hard templates to synthesize uranium based nanomaterials with novel structures by electrodeposition method. Through electrochemical behavior investigations and subsequent product characterizations such as energy dispersive spectrometer (EDS), fourier transform infrared spectroscopy (FTIR), the chemical composition of deposition products have been confirmed as the uranyl hydroxide. More importantly, accurate control of morphology and structures (nanowires and nanotubes) could be achieved by carefully adjusting the growth parameters such as deposition time and deposition current density. It was found that the preferred morphology of electrodeposition products is nanowire when a low current density was applied, whereas nanotubes could be formed only under conditions of high current density and the short deposition time. The mechanism for the formation of nanowires in track-etched membranes is based on the precipitation of uranyl hydroxide from uranyl nitrate solution, according to the previous researches about obtaining nanostructures of hydroxides from nitrate salt solutions. And we have concluded that the formation of nanotubes is attributed to the hydrogen bubbles generated by water electrolysis under the condition of over-potential electro-reduction. The conveying of hydrogen bubbles plays the role of dynamic template which can prevent the complete filling of uranyl hydroxide in the channels. Additionally, we transform the chemical composition of deposition products from uranyl hydroxide to triuranium octoxide by calcining them at 500 and 800 degree centigrade, respectively, and SEM results show the morphologies of nanowires and

  16. Photodetector based on carbon nanotubes

    Science.gov (United States)

    Pavlov, A.; Kitsyuk, E.; Ryazanov, R.; Timoshenkov, V.; Adamov, Y.

    2015-09-01

    Photodetector based on carbon nanotubes (CNT) was investigated. Sensors were done on quartz and silicon susbtrate. Samples of photodetectors sensors were produced by planar technology. This technology included deposition of first metal layer (Al), lithography for pads formation, etching, and formation of local catalyst area by inverse lithography. Vertically-aligned multi-wall carbon nanotubes were directly synthesized on substrate by PECVD method. I-V analysis and spectrum sensitivity of photodetector were investigated for 0.4 μm - 1.2 μm wavelength. Resistivity of CNT layers over temperature was detected in the range of -20°C to 100°C.

  17. CMOS Integrated Carbon Nanotube Sensor

    International Nuclear Information System (INIS)

    Perez, M. S.; Lerner, B.; Boselli, A.; Lamagna, A.; Obregon, P. D. Pareja; Julian, P. M.; Mandolesi, P. S.; Buffa, F. A.

    2009-01-01

    Recently carbon nanotubes (CNTs) have been gaining their importance as sensors for gases, temperature and chemicals. Advances in fabrication processes simplify the formation of CNT sensor on silicon substrate. We have integrated single wall carbon nanotubes (SWCNTs) with complementary metal oxide semiconductor process (CMOS) to produce a chip sensor system. The sensor prototype was designed and fabricated using a 0.30 um CMOS process. The main advantage is that the device has a voltage amplifier so the electrical measure can be taken and amplified inside the sensor. When the conductance of the SWCNTs varies in response to media changes, this is observed as a variation in the output tension accordingly.

  18. Gauge mediation scenario with hidden sector renormalization in MSSM

    International Nuclear Information System (INIS)

    Arai, Masato; Kawai, Shinsuke; Okada, Nobuchika

    2010-01-01

    We study the hidden sector effects on the mass renormalization of a simplest gauge-mediated supersymmetry breaking scenario. We point out that possible hidden sector contributions render the soft scalar masses smaller, resulting in drastically different sparticle mass spectrum at low energy. In particular, in the 5+5 minimal gauge-mediated supersymmetry breaking with high messenger scale (that is favored by the gravitino cold dark matter scenario), we show that a stau can be the next lightest superparticle for moderate values of hidden sector self-coupling. This provides a very simple theoretical model of long-lived charged next lightest superparticles, which imply distinctive signals in ongoing and upcoming collider experiments.

  19. Gauge mediation scenario with hidden sector renormalization in MSSM

    Science.gov (United States)

    Arai, Masato; Kawai, Shinsuke; Okada, Nobuchika

    2010-02-01

    We study the hidden sector effects on the mass renormalization of a simplest gauge-mediated supersymmetry breaking scenario. We point out that possible hidden sector contributions render the soft scalar masses smaller, resulting in drastically different sparticle mass spectrum at low energy. In particular, in the 5+5¯ minimal gauge-mediated supersymmetry breaking with high messenger scale (that is favored by the gravitino cold dark matter scenario), we show that a stau can be the next lightest superparticle for moderate values of hidden sector self-coupling. This provides a very simple theoretical model of long-lived charged next lightest superparticles, which imply distinctive signals in ongoing and upcoming collider experiments.

  20. Multivariate longitudinal data analysis with mixed effects hidden Markov models.

    Science.gov (United States)

    Raffa, Jesse D; Dubin, Joel A

    2015-09-01

    Multiple longitudinal responses are often collected as a means to capture relevant features of the true outcome of interest, which is often hidden and not directly measurable. We outline an approach which models these multivariate longitudinal responses as generated from a hidden disease process. We propose a class of models which uses a hidden Markov model with separate but correlated random effects between multiple longitudinal responses. This approach was motivated by a smoking cessation clinical trial, where a bivariate longitudinal response involving both a continuous and a binomial response was collected for each participant to monitor smoking behavior. A Bayesian method using Markov chain Monte Carlo is used. Comparison of separate univariate response models to the bivariate response models was undertaken. Our methods are demonstrated on the smoking cessation clinical trial dataset, and properties of our approach are examined through extensive simulation studies. © 2015, The International Biometric Society.

  1. Applications of hidden symmetries to black hole physics

    International Nuclear Information System (INIS)

    Frolov, Valeri

    2011-01-01

    This work is a brief review of applications of hidden symmetries to black hole physics. Symmetry is one of the most important concepts of the science. In physics and mathematics the symmetry allows one to simplify a problem, and often to make it solvable. According to the Noether theorem symmetries are responsible for conservation laws. Besides evident (explicit) spacetime symmetries, responsible for conservation of energy, momentum, and angular momentum of a system, there also exist what is called hidden symmetries, which are connected with higher order in momentum integrals of motion. A remarkable fact is that black holes in four and higher dimensions always possess a set ('tower') of explicit and hidden symmetries which make the equations of motion of particles and light completely integrable. The paper gives a general review of the recently obtained results. The main focus is on understanding why at all black holes have something (symmetry) to hide.

  2. Discovering Hidden Controlling Parameters using Data Analytics and Dimensional Analysis

    Science.gov (United States)

    Del Rosario, Zachary; Lee, Minyong; Iaccarino, Gianluca

    2017-11-01

    Dimensional Analysis is a powerful tool, one which takes a priori information and produces important simplifications. However, if this a priori information - the list of relevant parameters - is missing a relevant quantity, then the conclusions from Dimensional Analysis will be incorrect. In this work, we present novel conclusions in Dimensional Analysis, which provide a means to detect this failure mode of missing or hidden parameters. These results are based on a restated form of the Buckingham Pi theorem that reveals a ridge function structure underlying all dimensionless physical laws. We leverage this structure by constructing a hypothesis test based on sufficient dimension reduction, allowing for an experimental data-driven detection of hidden parameters. Both theory and examples will be presented, using classical turbulent pipe flow as the working example. Keywords: experimental techniques, dimensional analysis, lurking variables, hidden parameters, buckingham pi, data analysis. First author supported by the NSF GRFP under Grant Number DGE-114747.

  3. Supersymmetry, p-brane duality, and hidden spacetime dimensions

    International Nuclear Information System (INIS)

    Bars, I.

    1996-01-01

    A global superalgebra with 32 supercharges and all possible central extensions is studied in order to extract some general properties of duality and hidden dimensions in a theory that treats p-branes democratically. The maximal number of dimensions is 12, with signature (10,2), containing one space and one time dimension that are hidden from the point of view of perturbative ten-dimensional string theory or its compactifications. When the theory is compactified on R d-1,1 circle-times T c+1,1 with d+c+2=12, there are isometry groups that relate to the hidden dimensions as well as to duality. Their combined intersecting classification schemes provide some properties of nonperturbative states and their couplings. copyright 1996 The American Physical Society

  4. QCD sum rule study of hidden-charm pentaquarks

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-10-15

    We study the mass spectra of hidden-charm pentaquarks having spin J = (1)/(2)/(3)/(2)/(5)/(2) and quark contents uudc anti c. We systematically construct all the relevant local hidden-charm pentaquark currents, and we select some of them to perform QCD sum rule analyses. We find that the P{sub c}(4380) and P{sub c}(4450) can be identified as hidden-charm pentaquark states composed of an anti-charmed meson and a charmed baryon. Besides them, we also find (a) the lowest-lying hidden-charm pentaquark state of J{sup P} = 1/2{sup -} has the mass 4.33{sup +0.17}{sub -0.13} GeV, while the one of J{sup P} = 1/2{sup +} is significantly higher, that is, around 4.7-4.9 GeV; (b) the lowest-lying hidden-charm pentaquark state of J{sup P} = 3/2{sup -} has the mass 4.37{sup +0.18}{sub -0.13} GeV, consistent with the P{sub c}(4380) of J{sup P} = 3/2{sup -}, while the one of J{sup P} = 3/2{sup +} is also significantly higher, that is, above 4.6 GeV; (c) the hidden-charm pentaquark state of J{sup P} = 5/2{sup -} has a mass around 4.5-4.6 GeV, slightly larger than the P{sub c}(4450) of J{sup P} = 5/2{sup +}. (orig.)

  5. Carbon nanotubes and methods of making carbon nanotubes

    KAUST Repository

    Basset, Jean-Marie; Zhou, Lu; Saih, Youssef

    2017-01-01

    Embodiments of the present disclosure provide for methods that can be used to produce carbon nanotubes (hereinafter CNT) having an inner diameter about 5-55 nm, methods of tuning the inner diameter of CNTs (e.g., by adjusting reaction pressure

  6. Carbon nanotubes and methods of making carbon nanotubes

    KAUST Repository

    Basset, Jean-Marie

    2017-04-27

    Embodiments of the present disclosure provide for methods that can be used to produce carbon nanotubes (hereinafter CNT) having an inner diameter about 5-55 nm, methods of tuning the inner diameter of CNTs (e.g., by adjusting reaction pressure), CNTs having an inner diameter of greater than 20 nm or more, and the like.

  7. Filled and empty states of carbon nanotubes in water: Dependence ...

    Indian Academy of Sciences (India)

    WINTEC

    We have carried out a series of molecular dynamics simulations of water containing a narrow carbon nanotube ..... tant system containing the nanotube is re-equilibrated for each ... quent production phase of the simulation run, the nanotube is ...

  8. Vertically aligned carbon nanotube field-effect transistors

    KAUST Repository

    Li, Jingqi; Zhao, Chao; Wang, Qingxiao; Zhang, Qiang; Wang, Zhihong; Zhang, Xixiang; Abutaha, Anas I.; Alshareef, Husam N.

    2012-01-01

    Vertically aligned carbon nanotube field-effect transistors (CNTFETs) have been developed using pure semiconducting carbon nanotubes. The source and drain were vertically stacked, separated by a dielectric, and the carbon nanotubes were placed

  9. The Hidden Work of Women in Small Family Firms in Southern Spain

    Directory of Open Access Journals (Sweden)

    Paula Rodríguez-Modroño

    2017-01-01

    Full Text Available Women have historically played an important hidden role in family firms, and a great deal of research is now shedding light on this role. In spite of the more formal nature of female work at the present day, still a considerable volume of women’s contributions in family firms is unregistered and unpaid, even in developed regions. A questionnaire was administered to 396 women working in small and medium-sized family firms located in Andalucia, a southern European region, characterized by familialism and an important informal economy. Our results confirm the persistence of subordinate forms of unpaid family collaboration due to the neutrality assigned to female contributions under the traditional gendered division of work. But also this study shows how some of the women voluntarily embrace subordinate roles as a temporary way to gain professional experience, useful for their future work inside or outside the family firm.

  10. Detecting Hidden Hierarchy of Non Hierarchical Terrorist Networks

    DEFF Research Database (Denmark)

    Memon, Nasrullah

    measures (and combinations of them) to identify key players (important nodes) in terrorist networks. Our recently introduced techniques and algorithms (which are also implemented in the investigative data mining toolkit known as iMiner) will be particularly useful for law enforcement agencies that need...... to analyze terrorist networks and prioritize their targets. Applying recently introduced mathematical methods for constructing the hidden hierarchy of "nonhierarchical" terrorist networks; we present case studies of the terrorist attacks occurred / planned in the past, in order to identify hidden hierarchy...

  11. Low-intensity interference effects and hidden-variable theories

    Energy Technology Data Exchange (ETDEWEB)

    Buonomano, V [Universidade Estadual de Campinas (Brazil). Inst. de Matematica

    1978-05-11

    The double-slit interference experiment and other similar experiments in the low-intensity limit (that is, one photon in the apparatus at a time) are examined in the spirit of Bell's work from the point of view of hidden-variable theories. It is found that there exists a class of hidden-variable theories which disagrees with quantum mechanics for a certain type of interference experiment. A manufactured conceptualization of this class, which is a particle view of interference, is described. An experiment, which appears to be feasible, is proposed to examine this disagreement.

  12. Application of Hidden Markov Models in Biomolecular Simulations.

    Science.gov (United States)

    Shukla, Saurabh; Shamsi, Zahra; Moffett, Alexander S; Selvam, Balaji; Shukla, Diwakar

    2017-01-01

    Hidden Markov models (HMMs) provide a framework to analyze large trajectories of biomolecular simulation datasets. HMMs decompose the conformational space of a biological molecule into finite number of states that interconvert among each other with certain rates. HMMs simplify long timescale trajectories for human comprehension, and allow comparison of simulations with experimental data. In this chapter, we provide an overview of building HMMs for analyzing bimolecular simulation datasets. We demonstrate the procedure for building a Hidden Markov model for Met-enkephalin peptide simulation dataset and compare the timescales of the process.

  13. Enhanced axion-photon coupling in GUT with hidden photon

    Science.gov (United States)

    Daido, Ryuji; Takahashi, Fuminobu; Yokozaki, Norimi

    2018-05-01

    We show that the axion coupling to photons can be enhanced in simple models with a single Peccei-Quinn field, if the gauge coupling unification is realized by a large kinetic mixing χ = O (0.1) between hypercharge and unbroken hidden U(1)H. The key observation is that the U(1)H gauge coupling should be rather strong to induce such large kinetic mixing, leading to enhanced contributions of hidden matter fields to the electromagnetic anomaly. We find that the axion-photon coupling is enhanced by about a factor of 10-100 with respect to the GUT-axion models with E / N = 8 / 3.

  14. Hidden Neural Networks: A Framework for HMM/NN Hybrids

    DEFF Research Database (Denmark)

    Riis, Søren Kamaric; Krogh, Anders Stærmose

    1997-01-01

    This paper presents a general framework for hybrids of hidden Markov models (HMM) and neural networks (NN). In the new framework called hidden neural networks (HNN) the usual HMM probability parameters are replaced by neural network outputs. To ensure a probabilistic interpretation the HNN is nor...... HMMs on TIMIT continuous speech recognition benchmarks. On the task of recognizing five broad phoneme classes an accuracy of 84% is obtained compared to 76% for a standard HMM. Additionally, we report a preliminary result of 69% accuracy on the TIMIT 39 phoneme task...

  15. Search for hidden Higgs decay in ATLAS detector

    International Nuclear Information System (INIS)

    Gabrielli, A.

    2013-01-01

    In this paper, a brief overview of the search for the Higgs boson in Hidden Valley models is given. Hidden Valley models predict Higgs decays to neutral particles, which can be also long lived with decay paths comparable to the LHC detectors dimensions. Decay final states consist of collimated leptons (Lepton Jets). Results are presented of a search for Higgs decays to long lived particles in the ATLAS detector at the LHC, based on 1.92 fb −1 data collected during 2011 at a 7TeV center-of-mass energy.

  16. Detecting Faults By Use Of Hidden Markov Models

    Science.gov (United States)

    Smyth, Padhraic J.

    1995-01-01

    Frequency of false alarms reduced. Faults in complicated dynamic system (e.g., antenna-aiming system, telecommunication network, or human heart) detected automatically by method of automated, continuous monitoring. Obtains time-series data by sampling multiple sensor outputs at discrete intervals of t and processes data via algorithm determining whether system in normal or faulty state. Algorithm implements, among other things, hidden first-order temporal Markov model of states of system. Mathematical model of dynamics of system not needed. Present method is "prior" method mentioned in "Improved Hidden-Markov-Model Method of Detecting Faults" (NPO-18982).

  17. From the solar system fo hidden cosmic structures

    Energy Technology Data Exchange (ETDEWEB)

    Benes, K

    1987-01-01

    The development of experimental astrophysics showed that in the evolution of planets, natural processes of a common nature take place. They include, e.g., radiogenic heat, the production of magmas, volcanic activity, degassing, etc. The solar system is a cosmic formation in an advanced stage of development and it is a realistic assumption that in the Galaxy other hidden planetary systems in various stages of development exist. The views on the possibility of the origination of life in other systems differ; life, however, is seen as a hidden property of cosmic matter. (M.D.).

  18. Enzymatic electrodes nanostructured with functionalized carbon nanotubes for biofuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Nazaruk, E.; Bilewicz, R. [University of Warsaw, Faculty of Chemistry, Warsaw (Poland); Sadowska, K.; Biernat, J.F. [Gdansk University of Technology, Chemical Faculty, Gdansk (Poland); Rogalski, J. [Maria Curie Sklodowska University, Department of Biochemistry, Lublin (Poland); Ginalska, G. [Medical University of Lublin, Department of Biochemistry, Lublin (Poland)

    2010-10-15

    Nanostructured bioelectrodes were designed and assembled into a biofuel cell with no separating membrane. The glassy carbon electrodes were modified with mediator-functionalized carbon nanotubes. Ferrocene (Fc) and 2,2{sup '}-azino-bis (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS) bound chemically to the carbon nanotubes were found useful as mediators of the enzyme catalyzed electrode processes. Glucose oxidase from Aspergillus niger AM-11 and laccase from Cerrena unicolor C-139 were incorporated in a liquid-crystalline matrix-monoolein cubic phase. The carbon nanotubes-nanostructured electrode surface was covered with the cubic phase film containing the enzyme and acted as the catalytic surface for the oxidation of glucose and reduction of oxygen. Thanks to the mediating role of derivatized nanotubes the catalysis was almost ten times more efficient than on the GCE electrodes: catalytic current of glucose oxidation was 1 mA cm{sup -2} and oxygen reduction current exceeded 0.6 mA cm{sup -2}. The open circuit voltage of the biofuel cell was 0.43 V. Application of carbon nanotubes increased the maximum power output of the constructed biofuel cell to 100 {mu}W cm{sup -2} without stirring of the solution which was ca. 100 times more efficient than using the same bioelectrodes without nanotubes on the electrode surface. (orig.)

  19. High pressure synthesis of amorphous TiO{sub 2} nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Quanjun; Liu, Ran; Wang, Tianyi; Xu, Ke; Dong, Qing; Liu, Bo; Liu, Bingbing, E-mail: liubb@jlu.edu.cn [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Liu, Jing [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2015-09-15

    Amorphous TiO{sub 2} nanotubes with diameters of 8-10 nm and length of several nanometers were synthesized by high pressure treatment of anatase TiO{sub 2} nanotubes. The structural phase transitions of anatase TiO{sub 2} nanotubes were investigated by using in-situ high-pressure synchrotron X-ray diffraction (XRD) method. The starting anatase structure is stable up to ∼20GPa, and transforms into a high-density amorphous (HDA) form at higher pressure. Pressure-modified high- to low-density transition was observed in the amorphous form upon decompression. The pressure-induced amorphization and polyamorphism are in good agreement with the previous results in ultrafine TiO{sub 2} nanoparticles and nanoribbons. The relationship between the LDA form and α-PbO{sub 2} phase was revealed by high-resolution transmission electron microscopy (HRTEM) study. In addition, the bulk modulus (B{sub 0} = 158 GPa) of the anatase TiO{sub 2} nanotubes is smaller than those of the corresponding bulks and nanoparticles (180-240 GPa). We suggest that the unique open-ended nanotube morphology and nanosize play important roles in the high pressure phase transition of TiO{sub 2} nanotubes.

  20. Chemically modified carbon nanotubes as material enhanced laser desorption ionisation (MELDI) material in protein profiling

    International Nuclear Information System (INIS)

    Najam-ul-Haq, M.; Rainer, M.; Schwarzenauer, T.; Huck, C.W.; Bonn, G.K.

    2006-01-01

    Biomarkers play a potential role in the early detection and diagnosis of a disease. Our aim is to derivatize carbon nanotubes for exploration of the differences in human body fluids e.g. serum, through matrix assisted laser desorption ionisation/time of flight mass spectrometry (MALDI/TOF-MS) that can be related to disease and subsequently to be employed in the biomarker discovery process. This application we termed as the material enhanced laser desorption ionisation (MELDI). The versatility of this technology is meant to increase the amount of information from biological samples on the protein level, which will have a major impact to serve the cause of diagnostic markers. Serum peptides and proteins are immobilized on derivatized carbon nanotubes, which function as binding material. Protein-loaded suspension is placed on a stainless steel target or buckypaper on aluminum target for direct analysis with MALDI-MS. The elution method to wash the bound proteins from carbon nanotubes was employed to compare with the direct analysis procedure. Elution is carried out by MALDI matrix solution to get them out of the entangled nanotubes, which are difficult to desorb by laser due to the complex nanotube structures. The advantage of these optimized methods compared to the conventional screening methods is the improved sensitivity, selectivity and the short analysis time without prior albumin and immunoglobulin depletion. The comparison of similarly modified diamond and carbon nanotubes exhibit differences in their nature to bind the proteins out of serum due to the differences in their physical characteristics. Infrared (IR) spectroscopy provided hint for the presence of tertiary amine peak at the crucial chemical step of iminodiacetic acid addition to acid chloride functionality on carbon nanotubes. Atomic absorption spectroscopy (AAS) was utilized to quantitatively measure the copper capacity of these derivatized carbon nanotubes which is a direct measure of capacity of

  1. Electrochemical Sensors Based on Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Md. Aminur Rahman

    2009-03-01

    Full Text Available This review focuses on recent contributions in the development of the electrochemical sensors based on carbon nanotubes (CNTs. CNTs have unique mechanical and electronic properties, combined with chemical stability, and behave electrically as a metal or semiconductor, depending on their structure. For sensing applications, CNTs have many advantages such as small size with larger surface area, excellent electron transfer promoting ability when used as electrodes modifier in electrochemical reactions, and easy protein immobilization with retention of its activity for potential biosensors. CNTs play an important role in the performance of electrochemical biosensors, immunosensors, and DNA biosensors. Various methods have been developed for the design of sensors using CNTs in recent years. Herein we summarize the applications of CNTs in the construction of electrochemical sensors and biosensors along with other nanomaterials and conducting polymers.

  2. 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.

  3. Hidden Pair of Supermassive Black Holes

    Science.gov (United States)

    Kohler, Susanna

    2015-08-01

    Could a pair of supermassive black holes (SMBHs) be lurking at the center of the galaxy Mrk 231? A recent study finds that this may be the case and the unique spectrum of this galaxy could be the key to discovering more hidden binary SMBH systems.Where Are the Binary Supermassive Black Holes?Its believed that most, if not all, galaxies have an SMBH at their centers. As two galaxies merge, the two SMBHs should evolve into a closely-bound binary system before they eventually merge. Given the abundance of galaxy mergers, we would expect to see the kinematic and visual signatures of these binary SMBHs among observed active galactic nuclei yet such evidence for sub-parsec binary SMBH systems remains scarce and ambiguous. This has led researchers to wonder: is there another way that we might detect these elusive systems?A collaboration led by Chang-Shuo Yan (National Astronomical Observatories, Chinese Academy of Sciences) thinks that there is. The group suggests that these systems might have distinct signatures in their optical-to-UV spectra, and they identify a system that might be just such a candidate: Mrk 231.A Binary CandidateProposed model of Mrk 231. Two supermassive black holes, each with their own mini-disk, orbit each other in the center of a circumbinary disk. The secondary black hole has cleared gap in the circumbinary disk as a result of its orbit around the primary black hole. [Yan et al. 2015]Mrk 231 is a galaxy with a disturbed morphology and tidal tails strong clues that it might be in the final stages of a galactic merger. In addition to these signs, Mrk 231 also has an unusual spectrum for a quasar: its continuum emission displays an unexpected drop in the near-UV band.Yan and her collaborators propose that the odd behavior of Mrk 231s spectrum can be explained if the center of the galaxy houses a pair of SMBHs each with its own mini accretion disk surrounded by a circumbinary accretion disk. As the secondary SMBH orbits the primary SMBH (with a

  4. Nanotubes on Display: How Carbon Nanotubes Can Be Integrated into Electronic Displays

    KAUST Repository

    Opatkiewicz, Justin; LeMieux, Melburne C.; Bao, Zhenan

    2010-01-01

    Random networks of single-walled carbon nanotubes show promise for use in the field of flexible electronics. Nanotube networks have been difficult to utilize because of the mixture of electronic types synthesized when grown. A variety of separation

  5. Hidden markov model for the prediction of transmembrane proteins using MATLAB.

    Science.gov (United States)

    Chaturvedi, Navaneet; Shanker, Sudhanshu; Singh, Vinay Kumar; Sinha, Dhiraj; Pandey, Paras Nath

    2011-01-01

    Since membranous proteins play a key role in drug targeting therefore transmembrane proteins prediction is active and challenging area of biological sciences. Location based prediction of transmembrane proteins are significant for functional annotation of protein sequences. Hidden markov model based method was widely applied for transmembrane topology prediction. Here we have presented a revised and a better understanding model than an existing one for transmembrane protein prediction. Scripting on MATLAB was built and compiled for parameter estimation of model and applied this model on amino acid sequence to know the transmembrane and its adjacent locations. Estimated model of transmembrane topology was based on TMHMM model architecture. Only 7 super states are defined in the given dataset, which were converted to 96 states on the basis of their length in sequence. Accuracy of the prediction of model was observed about 74 %, is a good enough in the area of transmembrane topology prediction. Therefore we have concluded the hidden markov model plays crucial role in transmembrane helices prediction on MATLAB platform and it could also be useful for drug discovery strategy. The database is available for free at bioinfonavneet@gmail.comvinaysingh@bhu.ac.in.

  6. Method for synthesizing carbon nanotubes

    Science.gov (United States)

    Fan, Hongyou

    2012-09-04

    A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.

  7. Carbon nanotube-chalcogenide composite

    Czech Academy of Sciences Publication Activity Database

    Stehlík, Š.; Orava, J.; Kohoutek, T.; Wágner, T.; Frumar, M.; Zima, Vítězslav; Hara, T.; Matsui, Y.; Ueda, K.; Pumera, M.

    2010-01-01

    Roč. 183, č. 1 (2010), s. 144-149 ISSN 0022-4596 R&D Projects: GA ČR GA203/08/0208 Institutional research plan: CEZ:AV0Z40500505 Keywords : carbon nanotubes * chalcogenide glasses * composites Subject RIV: CA - Inorganic Chemistry Impact factor: 2.261, year: 2010

  8. Polyurethane compounds having carbon nanotubes

    NARCIS (Netherlands)

    2010-01-01

    The invention relates to semi-crystalline polyurethane (PUR) compositions filled with carbon nanotubes (CNT) and having improved electrical properties, which can be obtained on the basis of water-based polyurethane/CNT mixtures. The invention further relates to a method for producing polyurethane

  9. Polypyrrole nanotubes: mechanism of formation

    Czech Academy of Sciences Publication Activity Database

    Kopecká, J.; Kopecký, D.; Vrňata, M.; Fitl, P.; Stejskal, Jaroslav; Trchová, Miroslava; Bober, Patrycja; Morávková, Zuzana; Prokeš, J.; Sapurina, I.

    2014-01-01

    Roč. 4, č. 4 (2014), s. 1551-1558 ISSN 2046-2069 R&D Projects: GA ČR(CZ) GA13-08944S Institutional support: RVO:61389013 Keywords : conducting polymer * polypyrrole * nanotubes Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.840, year: 2014

  10. Carbon nanotube: the inside story.

    Science.gov (United States)

    Ando, Yoshinori

    2010-06-01

    Carbon nanotubes (CNTs) were serendipitously discovered as a byproduct of fullerenes by direct current (DC) arc discharge; and today this is the most-wanted material in the nanotechnology research. In this brief review, I begin with the history of the discovery of CNTs and focus on CNTs produced by arc discharge in hydrogen atmosphere, which is little explored outside my laboratory. DC arc discharge evaporation of pure graphite rod in pure hydrogen gas results in multi-walled carbon nanotubes (MWCNTs) of high crystallinity in the cathode deposit. As-grown MWCNTs have very narrow inner diameter. Raman spectra of these MWCNTs show high-intensity G-band, unusual high-frequency radial breathing mode at 570 cm(-1), and a new characteristic peak near 1850 cm(-1). Exciting carbon nanowires (CNWs), consisting of a linear carbon chain in the center of MWCNTs are also produced. Arc evaporation of graphite rod containing metal catalysts results in single-wall carbon nanotubes (SWCNTs) in the whole chamber like macroscopic webs. Two kinds of arc method have been developed to produce SWCNTs: Arc plasma jet (APJ) and Ferrum-Hydrogen (FH) arc methods. Some new purification methods for as-produced SWCNTs are reviewed. Finally, double-walled carbon nanotubes (DWCNTs) are also described.

  11. Synthesis of PbI(2) single-layered inorganic nanotubes encapsulated within carbon nanotubes.

    Science.gov (United States)

    Cabana, Laura; Ballesteros, Belén; Batista, Eudar; Magén, César; Arenal, Raúl; Oró-Solé, Judith; Rurali, Riccardo; Tobias, Gerard

    2014-04-02

    The template assisted growth of single-layered inorganic nanotubes is reported. Single-crystalline lead iodide single-layered nanotubes have been prepared using the inner cavities of carbon nanotubes as hosting templates. The diameter of the resulting inorganic nanotubes is merely dependent on the diameter of the host. This facile method is highly versatile opening up new horizons in the preparation of single-layered nanostructures. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Photoacoustic imaging of hidden dental caries by using a fiber-based probing system

    Science.gov (United States)

    Koyama, Takuya; Kakino, Satoko; Matsuura, Yuji

    2017-04-01

    Photoacoustic method to detect hidden dental caries is proposed. It was found that high frequency ultrasonic waves are generated from hidden carious part when radiating laser light to occlusal surface of model tooth. By making a map of intensity of these high frequency components, photoacoustic images of hidden caries were successfully obtained. A photoacoustic imaging system using a bundle of hollow optical fiber was fabricated for using clinical application, and clear photoacoustic image of hidden caries was also obtained by this system.

  13. Low-scale gravity mediation in warped extra dimension and collider phenomenology on hidden sector

    International Nuclear Information System (INIS)

    Itoh, H.; Okada, N.; Yamashita, T.

    2007-01-01

    We propose a new scenario of gravity-mediated supersymmetry breaking (gravity mediation) in a supersymmetric Randall-Sundrum model, where the gravity mediation takes place at a low scale due to the warped metric. We investigate collider phenomenology involving the hidden sector field, and find a possibility that the hidden sector field can be produced at the LHC and the ILC. The hidden sector may no longer be hidden. (author)

  14. Nanotube devices based crossbar architecture: toward neuromorphic computing

    International Nuclear Information System (INIS)

    Zhao, W S; Gamrat, C; Agnus, G; Derycke, V; Filoramo, A; Bourgoin, J-P

    2010-01-01

    Nanoscale devices such as carbon nanotube and nanowires based transistors, memristors and molecular devices are expected to play an important role in the development of new computing architectures. While their size represents a decisive advantage in terms of integration density, it also raises the critical question of how to efficiently address large numbers of densely integrated nanodevices without the need for complex multi-layer interconnection topologies similar to those used in CMOS technology. Two-terminal programmable devices in crossbar geometry seem particularly attractive, but suffer from severe addressing difficulties due to cross-talk, which implies complex programming procedures. Three-terminal devices can be easily addressed individually, but with limited gain in terms of interconnect integration. We show how optically gated carbon nanotube devices enable efficient individual addressing when arranged in a crossbar geometry with shared gate electrodes. This topology is particularly well suited for parallel programming or learning in the context of neuromorphic computing architectures.

  15. Charge mobility modification of semiconducting carbon nanotubes by intrinsic defects

    International Nuclear Information System (INIS)

    Bai, Hongcun; Ma, Yujia; Ma, Jinsuo; Mei, Jingnan; Tong, Yan; Ji, Yongqiang

    2017-01-01

    Charge carrier mobility is a central transport property in nanoscale electronics. Carbon nanotubes (CNTs) are supposed to have high carrier mobility. The preparation methods of CNTs have been greatly improved, but the defects always exist. This work presented first-principle investigations on the charge carrier mobility of carbon nanotubes containing several intrinsic defects. The charge carrier mobilities of zigzag (10, 0) tubes with Stone–Wales, mono vacant and 5/8/5 defects were studied as an example to explore the role of defects. Most carrier mobilities were decreased, but several values of mobility are unexpectedly increased upon the appearance of the defects. This interesting result is discussed based on the changes of the stretching modulus, the effective mass of the carrier and deformation potential constant induced by the defects. (paper)

  16. Raman spectra of filled carbon nanotubes

    International Nuclear Information System (INIS)

    Bose, S.M.; Behera, S.N.; Sarangi, S.N.; Entel, P.

    2004-01-01

    The Raman spectra of a metallic carbon nanotube filled with atoms or molecules have been investigated theoretically. It is found that there will be a three way splitting of the main Raman lines due to the interaction of the nanotube phonon with the collective excitations (plasmons) of the conduction electrons of the nanotube as well as its coupling with the phonon of the filling material. The positions and relative strengths of these Raman peaks depend on the strength of the electron-phonon interaction, phonon frequency of the filling atom and the strength of interaction of the nanotube phonon and the phonon of the filling atoms. Careful experimental studies of the Raman spectra of filled nanotubes should show these three peaks. It is also shown that in a semiconducting nanotube the Raman line will split into two and should be observed experimentally

  17. Liquid surface model for carbon nanotube energetics

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Mathew, Maneesh; Solov'yov, Andrey V.

    2008-01-01

    an important insight in the energetics and stability of nanotubes of different chirality and might be important for the understanding of nanotube growth process. For the computations we use empirical Brenner and Tersoff potentials and discuss their applicability to the study of carbon nanotubes. From......In the present paper we developed a model for calculating the energy of single-wall carbon nanotubes of arbitrary chirality. This model, which we call as the liquid surface model, predicts the energy of a nanotube with relative error less than 1% once its chirality and the total number of atoms...... the calculated energies we determine the elastic properties of the single-wall carbon nanotubes (Young modulus, curvature constant) and perform a comparison with available experimental measurements and earlier theoretical predictions....

  18. On the hidden maxwell superalgebra underlying D = 4 supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Penafiel, D.M. [Departamento de Fisica, Universidad de Concepcion (Chile); DISAT, Politecnico di Torino (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Torino (Italy); Ravera, L. [DISAT, Politecnico di Torino (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Torino (Italy)

    2017-09-15

    In this work, we expand the hidden AdS-Lorentz superalgebra underlying D = 4 supergravity, reaching a (hidden) Maxwell superalgebra. The latter can be viewed as an extension involving cosmological constant of the superalgebra underlying D = 4 supergravity in flat spacetime. We write the Maurer-Cartan equations in this context and we find some interesting extensions of the antisymmetric 3-form A{sup (3)} appearing in the Free Differential Algebra in Minkowski space. The structure of Free Differential Algebras is obtained by considering the zero curvature equations. We write the parametrization of A{sup (3)} in terms of 1-forms and we rend the topological features of its extensions manifest. We interestingly find out that the structure of these extensions, and consequently the structure of the corresponding boundary contribution dA{sup (3)}, strongly depends on the form of the extra fermionic generator appearing in the hidden Maxwell superalgebra. The model we develop in this work is defined in an enlarged superspace with respect to the ordinary one, and the extra bosonic and fermionic 1-forms required for the closure of the hidden Maxwell superalgebra must be considered as physical fields in this enlarged superspace. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Generalized inequalities for quantum correlations with hidden variables

    International Nuclear Information System (INIS)

    Vinduska, M.

    1991-01-01

    Renowned inequalities for quantum correlations are generalized for the case when quantum system cannot be described with an absolute independent measure of the probability. Such a formulation appears to be suitable for the formulation of the hidden variables theory in terms of non-Euclidean geometry. 10 refs

  20. Hidden conic quadratic representation of some nonconvex quadratic optimization problems

    NARCIS (Netherlands)

    Ben-Tal, A.; den Hertog, D.

    The problem of minimizing a quadratic objective function subject to one or two quadratic constraints is known to have a hidden convexity property, even when the quadratic forms are indefinite. The equivalent convex problem is a semidefinite one, and the equivalence is based on the celebrated

  1. Measurement problem and local hidden variables with entangled photons

    Directory of Open Access Journals (Sweden)

    Muchowski Eugen

    2017-12-01

    Full Text Available It is shown that there is no remote action with polarization measurements of photons in singlet state. A model is presented introducing a hidden parameter which determines the polarizer output. This model is able to explain the polarization measurement results with entangled photons. It is not ruled out by Bell’s Theorem.

  2. The incompatibility between local hidden variable theories and the ...

    Indian Academy of Sciences (India)

    I discuss in detail the result that the Bell's inequalities derived in the context of local hidden variable theories for discrete quantized observables can be satisfied only if a fundamental conservation law is violated on the average. This result shows that such theories are physically nonviable, and makes the demarcating criteria ...

  3. A novel design of hidden web crawler using ontology

    OpenAIRE

    Manvi; Bhatia, Komal Kumar; Dixit, Ashutosh

    2015-01-01

    Deep Web is content hidden behind HTML forms. Since it represents a large portion of the structured, unstructured and dynamic data on the Web, accessing Deep-Web content has been a long challenge for the database community. This paper describes a crawler for accessing Deep-Web using Ontologies. Performance evaluation of the proposed work showed that this new approach has promising results.

  4. Hidden symmetries of the Principal Chiral Model unveiled

    International Nuclear Information System (INIS)

    Devchand, C.; Schiff, J.

    1996-12-01

    By relating the two-dimensional U(N) Principal Chiral Model to a Simple linear system we obtain a free-field parametrization of solutions. Obvious symmetry transformations on the free-field data give symmetries of the model. In this way all known 'hidden symmetries' and Baecklund transformations, as well as a host of new symmetries, arise. (author). 21 refs

  5. A hidden bias in a common calorimeter calibration scheme

    International Nuclear Information System (INIS)

    Lincoln, Don; Morrow, Greg; Kasper, Peter

    1994-01-01

    In this paper, a common calorimeter calibration scheme is explored and a hidden bias found. Since this bias mimics a non-linearity in response in the calorimeter, it must be understood and removed from the calibration before true non-linearities are investigated. The effect and its removal are explored and understood through straightforward calculus and algebra. ((orig.))

  6. Exposing the Hidden-Web Induced by Ajax

    NARCIS (Netherlands)

    Mesbah, A.; Van Deursen, A.

    2008-01-01

    AJAX is a very promising approach for improving rich interactivity and responsiveness of web applications. At the same time, AJAX techniques increase the totality of the hidden web by shattering the metaphor of a web ‘page’ upon which general search engines are based. This paper describes a

  7. Crisis Entrepreneurs and Hidden Crises : Illustrative Examples of Interactional

    NARCIS (Netherlands)

    Prof. Cees van Woerkum; dr. Annette Klarenbeek

    2012-01-01

    We examine the ways in which a hidden crisis can be exposed from a communication point of view. In which way can organisations create general awareness of a crisis and try to understand the dynamic nature of interactions? With the help of discourse analysis, we have examined the interactional

  8. Hidden symmetry of the quantum Calogero-Moser system

    DEFF Research Database (Denmark)

    Kuzentsov, Vadim b

    1996-01-01

    The hidden symmetry of the quantum Calogero-Moser system with an inverse-square potential is algebraically demonstrated making use of Dunkl's operators. We find the underlying algebra explaining the super-integrability phenomenon for this system. Applications to related multi-variable Bessel...... functions are also discussed....

  9. Duality and hidden symmetries in interacting particle systems

    NARCIS (Netherlands)

    Giardinà, C.; Kurchan, J.; Redig, F.H.J.; Vafayi, K.

    2009-01-01

    In the context of Markov processes, both in discrete and continuous setting, we show a general relation between duality functions and symmetries of the generator. If the generator can be written in the form of a Hamiltonian of a quantum spin system, then the "hidden" symmetries are easily derived.

  10. A Constraint Model for Constrained Hidden Markov Models

    DEFF Research Database (Denmark)

    Christiansen, Henning; Have, Christian Theil; Lassen, Ole Torp

    2009-01-01

    A Hidden Markov Model (HMM) is a common statistical model which is widely used for analysis of biological sequence data and other sequential phenomena. In the present paper we extend HMMs with constraints and show how the familiar Viterbi algorithm can be generalized, based on constraint solving ...

  11. Is There Hidden Potential for Rural Population Growth in Sweden?

    Science.gov (United States)

    Niedomysl, Thomas; Amcoff, Jan

    2011-01-01

    Rural depopulation is a concern in many countries, and various policy initiatives have been taken to combat such trends. This article examines whether hidden potential for rural population growth can be found in Sweden. If such potential exists, it implies that the development prospects for many rural areas are not as unpromising as they may seem…

  12. Optimisation of Hidden Markov Model using Baum–Welch algorithm

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 126; Issue 1. Optimisation of Hidden Markov Model using Baum–Welch algorithm for prediction of maximum and minimum temperature over Indian Himalaya. J C Joshi Tankeshwar Kumar Sunita Srivastava Divya Sachdeva. Volume 126 Issue 1 February 2017 ...

  13. Hidden Markov Model for quantitative prediction of snowfall

    Indian Academy of Sciences (India)

    A Hidden Markov Model (HMM) has been developed for prediction of quantitative snowfall in Pir-Panjal and Great Himalayan mountain ranges of Indian Himalaya. The model predicts snowfall for two days in advance using daily recorded nine meteorological variables of past 20 winters from 1992–2012. There are six ...

  14. Light hidden-sector U(1)s in string compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Goodsell, Mark; Ringwald, Andreas

    2010-02-15

    We review the case for light U(1) gauge bosons in the hidden-sector of heterotic and type II string compactifications, present estimates of the size of their kinetic mixing with the visible-sector hypercharge U(1), and discuss their possibly very interesting phenomenological consequences in particle physics and cosmology. (orig.)

  15. Book Review: "Hidden Markov Models for Time Series: An ...

    African Journals Online (AJOL)

    Hidden Markov Models for Time Series: An Introduction using R. by Walter Zucchini and Iain L. MacDonald. Chapman & Hall (CRC Press), 2009. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · http://dx.doi.org/10.4314/saaj.v10i1.61717 · AJOL African Journals Online.

  16. TeraHertz imaging of hidden paint layers on canvas

    NARCIS (Netherlands)

    Adam, A.J.L.; Planken, P.C.M.; Meloni, S.; Dik, J.

    2009-01-01

    We show terahertz reflection images of hidden paint layers in a painting on canvas and compare the results with X-ray Radiography and Infrared Reflectography. Our terahertz measurements show strong reflections from both the canvas/paint interface and from the raw umber/lead white interface,

  17. K­MEANS CLUSTERING FOR HIDDEN MARKOV MODEL

    NARCIS (Netherlands)

    Perrone, M.P.; Connell, S.D.

    2004-01-01

    An unsupervised k­means clustering algorithm for hidden Markov models is described and applied to the task of generating subclass models for individual handwritten character classes. The algorithm is compared to a related clustering method and shown to give a relative change in the error rate of as

  18. EVALUASI HIDDEN CURRICULUM DI SMP NEGERI BOJA, KABUPATEN KENDAL

    Directory of Open Access Journals (Sweden)

    Neni Lestari

    2015-12-01

    Full Text Available This study aimed to evaluate the implementation and impact of Hidden Curriculum, as well as the determinant factors of success and sustainability in SMPN 2 Boja Kendal. This study was an evaluative research using qualitative approach. The data collected by using observation, interviews, and documentation. Data analyzed by collecting and selecting to be deduce. Validity used triangulation data that combined the result of observation, interviews, and documentation. The results of the study were: 1 The activities of hidden curriculum development at SMPN 2 Boja Kendal, namely: flag ceremony, school environmental management, establishing and enforcing discipline, special religious worship, smiles, greetings and courtesies, exemplary, relationship among students and principal, teachers, and staff, school canteen services. 2 The impact of the hidden curriculum development was the changing of school community’s behavior being better, created clean and beautiful school environment, the improvement of public trust to the school toward their kids’ education. Development of the hidden curriculum could establish students good character and an optimal achievement as well as a good school culture. 3 Internal supporting factors including: qualified human resources, the availability of school facilities, school environment was clean and beautiful. External supporting factors occur in the form of endorsement of the parents, school committees and communities in establishing good and virtuous character for the students.

  19. Hidden and generalized conformal symmetry of Kerr–Sen spacetimes

    International Nuclear Information System (INIS)

    Ghezelbash, A M; Siahaan, H M

    2013-01-01

    It is recently conjectured that generic non-extremal Kerr black hole could be holographically dual to a hidden conformal field theory (CFT) in two dimensions. Moreover, it is known that there are two CFT duals (pictures) to describe the charged rotating black holes which correspond to angular momentum J and electric charge Q of the black hole. Furthermore these two pictures can be incorporated by the CFT duals (general picture) that are generated by SL(2,Z) modular group. The general conformal structure can be revealed by looking at charged scalar wave equation in some appropriate values of frequency and charge. In this regard, we consider the wave equation of a charged massless scalar field in the background of Kerr–Sen black hole and show that in the ‘near region’, the wave equation can be reproduced by the Casimir operator of a local SL(2,R) L ×SL(2,R) R hidden conformal symmetry. We find the exact agreement between macroscopic and microscopic physical quantities like entropy and absorption cross section of scalars for Kerr–Sen black hole. We then find an extension of vector fields that in turn yields an extended local family of SL(2,R) L ×SL(2,R) R hidden conformal symmetry, parameterized by one parameter. For some special values of the parameter, we find a copy of SL(2,R) hidden conformal algebra for the charged Gibbons–Maeda–Garfinkle–Horowitz–Strominger black hole in the strong deflection limit. (paper)

  20. Light hidden-sector U(1)s in string compactifications

    International Nuclear Information System (INIS)

    Goodsell, Mark; Ringwald, Andreas

    2010-02-01

    We review the case for light U(1) gauge bosons in the hidden-sector of heterotic and type II string compactifications, present estimates of the size of their kinetic mixing with the visible-sector hypercharge U(1), and discuss their possibly very interesting phenomenological consequences in particle physics and cosmology. (orig.)

  1. Securing Localization With Hidden and Mobile Base Stations

    DEFF Research Database (Denmark)

    Capkun, Srdjan; Srivastava, Mani; Cagalj, Mario

    2006-01-01

    localization based on hidden and mobile base stations. Our approach enables secure localization with a broad spectrum of localization techniques: ultrasonic or radio, based on received signal strength or signal time of flight. Through several examples we show how this approach can be used to secure nodecentric...

  2. Optimal Number of States in Hidden Markov Models and its ...

    African Journals Online (AJOL)

    In this paper, Hidden Markov Model is applied to model human movements as to facilitate an automatic detection of the same. A number of activities were simulated with the help of two persons. The four movements considered are walking, sitting down-getting up, fall while walking and fall while standing. The data is ...

  3. Book review: Troubling possibility, hidden fires and secret drawers ...

    African Journals Online (AJOL)

    Book review: Troubling possibility, hidden fires and secret drawers: Tiyambe Zeleza's smouldering charcoal. H.F. Ross. Abstract. No Abstract. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL.

  4. Charm and Hidden Charm Scalar Resonances in Nuclear Matter

    NARCIS (Netherlands)

    Tolos, Laura; Molina, Raquel; Gamermann, Daniel; Oset, Eulogio

    2009-01-01

    We study the properties of the scalar charm resonances D(s0)(2317) and D(0)(2400), and the theoretical hidden charm state X(3700) in nuclear matter. We find that for the D(s0)(2317) and X(3700) resonances, with negligible and small width at zero density, respectively, the width becomes about 100 MeV

  5. Hidden Markov model for improved ultrasound-based presence detection

    NARCIS (Netherlands)

    Jaramillo Garcia, P.A.; Linnartz, J.P.M.G.

    2015-01-01

    Adaptive lighting systems typically use a presence detector to save energy by switching off lights in unoccupied rooms. However, it is highly annoying when lights are erroneously turned off while a user is present (false negative, FN). This paper focuses on the estimation of presence, using a Hidden

  6. Job Clubs: Getting into the Hidden Labor Market.

    Science.gov (United States)

    Kimeldorf, Martin; Tornow, Janice A.

    1984-01-01

    A job club approach for secondary disabled youth focuses on mastering job seeking skills by behaviorally sequenced steps learned in situational experiences within a self-help group process framework. Students learn to penetrate the hidden job market, to use social networking via the telephone, and to participate successfully in job interviews. (CL)

  7. Unpacking the Hidden Efficacies of Learning in Productive Failure

    Science.gov (United States)

    Hung, David; Chen, Victor; Lim, Seo Hong

    2009-01-01

    This paper describes a framework for learning where learners undergo experimentations with the phenomena at hand according to progressive and staged goals. Bowling is used as a case study in this paper. The premise for experimentations is that learners can experience hidden efficacies, including the formation of "bad habits." A distinction is made…

  8. Thermoelectric generator hidden in a shirt with a fabric radiator

    NARCIS (Netherlands)

    Leonov, V.; Vullers, R.J.M.; Hoof, C.V.

    2012-01-01

    Integration of thermopiles in garments has been performed in this work in different ways. It is shown that textile has a minor effect on power generation, which enables completely hidden and unobtrusive energy harvester. A one-milliwatt thermoelectric generator is then integrated between two layers

  9. B-graph sampling to estimate the size of a hidden population

    NARCIS (Netherlands)

    Spreen, M.; Bogaerts, S.

    2015-01-01

    Link-tracing designs are often used to estimate the size of hidden populations by utilizing the relational links between their members. A major problem in studies of hidden populations is the lack of a convenient sampling frame. The most frequently applied design in studies of hidden populations is

  10. Structure of Carbon Nanotube-dendrimer composite

    OpenAIRE

    Vasumathi, V.; Pramanik, Debabrata; Sood, A. K.; Maiti, Prabal K

    2012-01-01

    Using all atomistic molecular dynamics (MD) simulations we report the microscopic picture of the nanotube-dendrimer complex for PAMAM dendrimer of generation 2 to 4 and carbon nanotube of chirality (6,5). We find compact wrapping conformations of dendrimer onto the nanotube surface for all the three generations of PAMAM dendrimer. The degree of wrapping is more for non-protonated dendrimer compared to the protonated dendrimer. For comparison we also study the interaction of another dendrimer,...

  11. Carbon nanotubes as heat dissipaters in microelectronics

    DEFF Research Database (Denmark)

    Pérez Paz, Alejandro; García-Lastra, Juan María; Markussen, Troels

    2013-01-01

    We review our recent modelling work of carbon nanotubes as potential candidates for heat dissipation in microelectronics cooling. In the first part, we analyze the impact of nanotube defects on their thermal transport properties. In the second part, we investigate the loss of thermal properties...... of nanotubes in presence of an interface with various substances, including air and water. Comparison with previous works is established whenever is possible....

  12. Ordered metal nanotube arrays fabricated by PVD.

    Science.gov (United States)

    Marquez, F; Morant, C; Campo, T; Sanz, J M; Elizalde, E

    2010-02-01

    In this work we report a simple method to fabricate ordered arrays of metal nanotubes. This method is based on the deposition of a metal by PVD onto an anodized aluminum oxide (AAO) template. The dimensions of the synthesized nanotubes depend both on the AAO template and on the deposited metal. In fact, it is observed that the aspect ratios of the nanotubes clearly depend significantly on the metal, ranging from 0.6 (Fe) to at least 3 (Zr).

  13. Baryon states with hidden charm in the extended local hidden gauge approach

    International Nuclear Information System (INIS)

    Uchino, T.; Oset, E.; Liang, Wei-Hong

    2016-01-01

    The s-wave interaction of anti DΛ c , anti DΣ c , anti D * Λ c , anti D * Σ c and anti DΣ c * , anti D * Σ c * , is studied within a unitary coupled channels scheme with the extended local hidden gauge approach. In addition to the Weinberg-Tomozawa term, several additional diagrams via the pion exchange are also taken into account as box potentials. Furthermore, in order to implement the full coupled channels calculation, some of the box potentials which mix the vector-baryon and pseudoscalar-baryon sectors are extended to construct the effective transition potentials. As a result, we have observed six possible states in several angular momenta. Four of them correspond to two pairs of admixture states, two of anti DΣ c - anti D * Σ c with J = 1/2, and two of anti DΣ c * - anti D * Σ c * with J = 3/2. Moreover, we find a anti D * Σ c resonance which couples to the anti DΛ c channel and one spin degenerated bound state of anti D * Σ c * with J = 1/2,5/2. (orig.)

  14. Baryon states with hidden charm in the extended local hidden gauge approach

    Energy Technology Data Exchange (ETDEWEB)

    Uchino, T.; Oset, E. [Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigacion de Paterna, Departamento de Fisica Teorica y IFIC, Valencia (Spain); Liang, Wei-Hong [Guangxi Normal University, Department of Physics, Guilin (China)

    2016-03-15

    The s-wave interaction of anti DΛ{sub c}, anti DΣ{sub c}, anti D{sup *}Λ{sub c}, anti D{sup *}Σ{sub c} and anti DΣ{sub c}{sup *}, anti D{sup *}Σ{sub c}{sup *}, is studied within a unitary coupled channels scheme with the extended local hidden gauge approach. In addition to the Weinberg-Tomozawa term, several additional diagrams via the pion exchange are also taken into account as box potentials. Furthermore, in order to implement the full coupled channels calculation, some of the box potentials which mix the vector-baryon and pseudoscalar-baryon sectors are extended to construct the effective transition potentials. As a result, we have observed six possible states in several angular momenta. Four of them correspond to two pairs of admixture states, two of anti DΣ{sub c} - anti D{sup *}Σ{sub c} with J = 1/2, and two of anti DΣ{sub c}{sup *} - anti D{sup *}Σ{sub c}{sup *} with J = 3/2. Moreover, we find a anti D{sup *}Σ{sub c} resonance which couples to the anti DΛ{sub c} channel and one spin degenerated bound state of anti D{sup *}Σ{sub c}{sup *} with J = 1/2,5/2. (orig.)

  15. Nuclear translocation of Nrf2 and expression of antioxidant defence genes in THP-1 cells exposed to carbon nanotubes.

    Science.gov (United States)

    Brown, David M; Donaldson, Kenneth; Stone, Vicki

    2010-06-01

    Carbon nanotubes have a wide range of applications in various industries and their use is likely to rise in the future. Currently, a major concern is that with the increasing use and production of these materials, there may be increased health risks to exposed workers. Long (> 15 microm) straight nanotubes may undergo frustrated phagocytosis which is likely to result in reduced clearance. We examine here the effects of multiwalled carbon nanotubes of different sizes on monocytic THP-1 cells, with regard to their ability to stimulate increased expression of the HO-1 and GST genes and their ability to produce nuclear translocation of the transcription factor, Nrf2, as well as the release of several pro-inflammatory cytokines and mediators of inflammation. Our results suggest that long (50 microm) carbon nanotubes (62.5 microg/ml for 4 hours) produce increased nuclear translocation of Nrf2 and increased HO-1 gene expression compared with shorter entangled nanotubes. There was no increased gene expression for GST. The long nanotubes (NT1) caused increased release of the proinflammatory cytokine IL-1beta, an effect which was diminished by the antioxidant trolox, suggesting a role of oxidative stress in the upregulation of this cytokine. Tentatively, our study suggests that long carbon nanotubes may exert their effect in THP-1 cells in part via an oxidative stress mechanism.

  16. Carbon nanotubes for biological and biomedical applications

    International Nuclear Information System (INIS)

    Yang Wenrong; Thordarson, Pall; Gooding, J Justin; Ringer, Simon P; Braet, Filip

    2007-01-01

    Ever since the discovery of carbon nanotubes, researchers have been exploring their potential in biological and biomedical applications. The recent expansion and availability of chemical modification and bio-functionalization methods have made it possible to generate a new class of bioactive carbon nanotubes which are conjugated with proteins, carbohydrates, or nucleic acids. The modification of a carbon nanotube on a molecular level using biological molecules is essentially an example of the 'bottom-up' fabrication principle of bionanotechnology. The availability of these biomodified carbon nanotube constructs opens up an entire new and exciting research direction in the field of chemical biology, finally aiming to target and to alter the cell's behaviour at the subcellular or molecular level. This review covers the latest advances of bio-functionalized carbon nanotubes with an emphasis on the development of functional biological nano-interfaces. Topics that are discussed herewith include methods for biomodification of carbon nanotubes, the development of hybrid systems of carbon nanotubes and biomolecules for bioelectronics, and carbon nanotubes as transporters for a specific delivery of peptides and/or genetic material to cells. All of these current research topics aim at translating these biotechnology modified nanotubes into potential novel therapeutic approaches. (topical review)

  17. Quantum conductance of carbon nanotube peapods

    International Nuclear Information System (INIS)

    Yoon, Young-Gui; Mazzoni, Mario S.C.; Louie, Steven G.

    2003-01-01

    We present a first-principles study of the quantum conductance of hybrid nanotube systems consisting of single-walled carbon nanotubes (SWCNTs) encapsulating either an isolated single C60 molecule or a chain of C60 molecules (nanotube peapods). The calculations show a rather weak bonding interaction between the fullerenes and the SWCNTs. The conductance of a (10,10) SWCNT with a single C60 molecule is virtually unaffected at the Fermi level, but exhibits quantized resonant reductions at the molecular levels. The nanotube peapod arrangement gives rise to high density of states for the fullerene highest occupied molecular orbital and lowest unoccupied molecular orbital bands

  18. Glucose oxidase immobilization onto carbon nanotube networking

    International Nuclear Information System (INIS)

    Karachevtsev, V.A.; Glamazda, A.Yu.; Zarudnev, E.S.; Karachevtsev, M.V.; Leontiev, V.S.; Linnik, A.S.; Plokhotnichenko, A.M.; Stepanian, S.G.; Lytvyn, O.S.

    2012-01-01

    The efficient immobilization of GOX onto a carbon nanotube network through the molecular interface formed by PSE is carried out. This conclusion is based on the analysis of AFM images of the network with the adsorbed enzyme, whose globules locate mainly along a nanotube. The band corresponding to the high-frequency component of the G mode in the RR spectrum of the nanotube with adsorbed PSE is downshifted by 0.7 cm -1 relative to this band in the spectrum of pristine nanotubes. The analysis of the intensities of bands assigned to the RBM of nanotubes with adsorbed PSE in comparison with the spectrum of pristine SWNTs revealed the intensity transformation, which can be explained by a change of the resonance condition with variation of the laser energy. Thus, we concluded that PSE molecules create nanohybrids with SWNTs, which ensures the further enzyme immobilization. As the RR spectrum of an SWNT:PSE:GOX film does not essentially differ from SWNT:PSE ones, this indicates that the molecular interface (PSE) isolates the enzyme from nanotubes strongly enough. Our studies on the conductive properties of a single walled carbon nanotube network sprayed onto a quartz substrate from a solution of nanotubes in dichlorobenzene demonstrated that the I(U) dependence has nonlinear character. Most likely, the nonlinearity is related to Schottky barriers, which originate on the contact between nanotubes and the gold electrode, as well as between nanotubes with different conductivities. The deposition of bioorganic compounds (PSE and GOX) on the carbon nanotube network is accompanied by a decrease of their conductivity. Most probably, such a decrease is caused by adsorbed PSE molecules, which induce the appearance of scattering centers for charge carriers on the nanotube surface. The following GOX adsorption has practically no effect on the conductivity of the nanotube network that evidences the reliable isolation of the nanotube surface from the enzyme by means of the molecular

  19. Self-assembly of diphenylalanine backbone homologues and their combination with functionalized carbon nanotubes.

    Science.gov (United States)

    Dinesh, Bhimareddy; Squillaci, Marco A; Ménard-Moyon, Cécilia; Samorì, Paolo; Bianco, Alberto

    2015-10-14

    The integration of carbon nanotubes (CNTs) into organized nanostructures is of great interest for applications in materials science and biomedicine. In this work we studied the self-assembly of β and γ homologues of diphenylalanine peptides under different solvent and pH conditions. We aimed to investigate the role of peptide backbone in tuning the formation of different types of nanostructures alone or in combination with carbon nanotubes. In spite of having the same side chain, β and γ peptides formed distinctively different nanofibers, a clear indication of the role played by the backbone homologation on the self-assembly. The variation of the pH allowed to transform the nanofibers into spherical structures. Moreover, the co-assembly of β and γ peptides with carbon nanotubes covalently functionalized with the same peptide generated unique dendritic assemblies. This comparative study on self-assembly using diphenylalanine backbone homologues and of the co-assembly with CNT covalent conjugates is the first example exploring the capacity of β and γ peptides to adopt precise nanostructures, particularly in combination with carbon nanotubes. The dendritic organization obtained by mixing carbon nanotubes and peptides might find interesting applications in tissue engineering and neuronal interfacing.

  20. Application of Nanoparticles/Nanowires and Carbon Nanotubes for Breast Cancer Research

    National Research Council Canada - National Science Library

    Panchapakesan, Balaji

    2005-01-01

    .... Variety of techniques such as fabrication of single wall carbon nanotubes, functionalization of nanotubes with antibodies, interaction of cells with antibodies on nanotube surfaces, and finally cell...

  1. Hidden photons in beam dump experiments and in connection with dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Andreas, Sarah

    2012-12-15

    Hidden sectors with light extra U(1) gauge bosons, so-called hidden photons, recently received much interest as natural feature of beyond standard model scenarios like string theory and SUSY and because of their possible connection to dark matter. This paper presents limits on hidden photons from past electron beam dump experiments including two new limits from experiments at KEK and Orsay. Additionally, various hidden sector models containing both a hidden photon and a dark matter candidate are discussed with respect to their viability and potential signatures in direct detection.

  2. Hidden photons in beam dump experiments and in connection with dark matter

    International Nuclear Information System (INIS)

    Andreas, Sarah

    2012-12-01

    Hidden sectors with light extra U(1) gauge bosons, so-called hidden photons, recently received much interest as natural feature of beyond standard model scenarios like string theory and SUSY and because of their possible connection to dark matter. This paper presents limits on hidden photons from past electron beam dump experiments including two new limits from experiments at KEK and Orsay. Additionally, various hidden sector models containing both a hidden photon and a dark matter candidate are discussed with respect to their viability and potential signatures in direct detection.

  3. Properties of single-walled carbon nanotube-based aerogels as a function of nanotube loading

    International Nuclear Information System (INIS)

    Worsley, Marcus A.; Pauzauskie, Peter J.; Kucheyev, Sergei O.; Zaug, Joseph M.; Hamza, Alex V.; Satcher, Joe H.; Baumann, Theodore F.

    2009-01-01

    Here, we present the synthesis and characterization of low-density single-walled carbon nanotube-based aerogels (SWNT-CA). Aerogels with varying nanotube loading (0-55 wt.%) and density (20-350 mg cm -3 ) were fabricated and characterized by four-probe method, electron microscopy, Raman spectroscopy and nitrogen porosimetry. Several properties of the SWNT-CAs were highly dependent upon nanotube loading. At nanotube loadings of 55 wt.%, shrinkage of the aerogel monoliths during carbonization and drying was almost completely eliminated. Electrical conductivities are improved by an order of magnitude for the SWNT-CA (55 wt.% nanotubes) compared to those of foams without nanotubes. Surface areas as high as 184 m 2 g -1 were achieved for SWNT-CAs with greater than 20 wt.% nanotube loading.

  4. Zero velocity interval detection based on a continuous hidden Markov model in micro inertial pedestrian navigation

    Science.gov (United States)

    Sun, Wei; Ding, Wei; Yan, Huifang; Duan, Shunli

    2018-06-01

    Shoe-mounted pedestrian navigation systems based on micro inertial sensors rely on zero velocity updates to correct their positioning errors in time, which effectively makes determining the zero velocity interval play a key role during normal walking. However, as walking gaits are complicated, and vary from person to person, it is difficult to detect walking gaits with a fixed threshold method. This paper proposes a pedestrian gait classification method based on a hidden Markov model. Pedestrian gait data are collected with a micro inertial measurement unit installed at the instep. On the basis of analyzing the characteristics of the pedestrian walk, a single direction angular rate gyro output is used to classify gait features. The angular rate data are modeled into a univariate Gaussian mixture model with three components, and a four-state left–right continuous hidden Markov model (CHMM) is designed to classify the normal walking gait. The model parameters are trained and optimized using the Baum–Welch algorithm and then the sliding window Viterbi algorithm is used to decode the gait. Walking data are collected through eight subjects walking along the same route at three different speeds; the leave-one-subject-out cross validation method is conducted to test the model. Experimental results show that the proposed algorithm can accurately detect different walking gaits of zero velocity interval. The location experiment shows that the precision of CHMM-based pedestrian navigation improved by 40% when compared to the angular rate threshold method.

  5. A Hidden Markov Model for Urban-Scale Traffic Estimation Using Floating Car Data.

    Science.gov (United States)

    Wang, Xiaomeng; Peng, Ling; Chi, Tianhe; Li, Mengzhu; Yao, Xiaojing; Shao, Jing

    2015-01-01

    Urban-scale traffic monitoring plays a vital role in reducing traffic congestion. Owing to its low cost and wide coverage, floating car data (FCD) serves as a novel approach to collecting traffic data. However, sparse probe data represents the vast majority of the data available on arterial roads in most urban environments. In order to overcome the problem of data sparseness, this paper proposes a hidden Markov model (HMM)-based traffic estimation model, in which the traffic condition on a road segment is considered as a hidden state that can be estimated according to the conditions of road segments having similar traffic characteristics. An algorithm based on clustering and pattern mining rather than on adjacency relationships is proposed to find clusters with road segments having similar traffic characteristics. A multi-clustering strategy is adopted to achieve a trade-off between clustering accuracy and coverage. Finally, the proposed model is designed and implemented on the basis of a real-time algorithm. Results of experiments based on real FCD confirm the applicability, accuracy, and efficiency of the model. In addition, the results indicate that the model is practicable for traffic estimation on urban arterials and works well even when more than 70% of the probe data are missing.

  6. Snatching at hidden secrets of arcane cytokinins

    International Nuclear Information System (INIS)

    Gajdosova, S.; Kaminek, M.; Hoyerova, K.; Fobrev, P. I.; Klima, P.; Zizkova, E.; Motyka, V.

    2009-01-01

    We provide here up-to-date insight on cZ-type CKs and their metabolic conversion in tobacco. cZ- type CKs, their wide-occurrence in plant kingdom, as well as their affinity to some, but not all, CK receptors indicate their specific physiological function, probably related to certain tissues, developmental stages or environmental conditions. Our data from bioassay proved that cZ-type CKs posses biological activity. Their unique role in plant metabolism, however, still needs to be elucidated. (authors)

  7. Torsional carbon nanotube artificial muscles.

    Science.gov (United States)

    Foroughi, Javad; Spinks, Geoffrey M; Wallace, Gordon G; Oh, Jiyoung; Kozlov, Mikhail E; Fang, Shaoli; Mirfakhrai, Tissaphern; Madden, John D W; Shin, Min Kyoon; Kim, Seon Jeong; Baughman, Ray H

    2011-10-28

    Rotary motors of conventional design can be rather complex and are therefore difficult to miniaturize; previous carbon nanotube artificial muscles provide contraction and bending, but not rotation. We show that an electrolyte-filled twist-spun carbon nanotube yarn, much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions per minute. A hydrostatic actuation mechanism, as seen in muscular hydrostats in nature, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. The use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.

  8. Carbon Nanotubes: Molecular Electronic Components

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1997-01-01

    The carbon Nanotube junctions have recently emerged as excellent candidates for use as the building blocks in the formation of nanoscale molecular electronic networks. While the simple joint of two dissimilar tubes can be generated by the introduction of a pair of heptagon-pentagon defects in an otherwise perfect hexagonal graphene sheet, more complex joints require other mechanisms. In this work we explore structural characteristics of complex 3-point junctions of carbon nanotubes using a generalized tight-binding molecular-dynamics scheme. The study of pi-electron local densities of states (LDOS) of these junctions reveal many interesting features, most prominent among them being the defect-induced states in the gap.

  9. Mechanics of filled carbon nanotubes

    KAUST Repository

    Monteiro, A.O.; Cachim, P.B.; Da Costa, Pedro M. F. J.

    2014-01-01

    The benefits of filling carbon nanotubes (CNTs) with assorted molecular and crystalline substances have been investigated for the past two decades. Amongst the study of new structural phases, defects, chemical reactions and varied types of host-guest interactions, there is one fundamental characterisation aspect of these systems that continues to be overlooked: the mechanical behaviour of filled CNTs. In contrast to their empty counterparts, the mechanics of filled CNTs is a subject where reports appear far and apart, this despite being key to the application of these materials in technological devices. In the following paragraphs, we review the work that has been carried out up to the present on the mechanics of filled CNTs. The studies discussed range from experimental resonant frequency essays performed within electron microscopes to modelling, via molecular dynamics, of three-point bending of nanotubes filled with gases. (C) 2014 Elsevier B.V. All rights reserved.

  10. Mechanics of filled carbon nanotubes

    KAUST Repository

    Monteiro, A.O.

    2014-04-01

    The benefits of filling carbon nanotubes (CNTs) with assorted molecular and crystalline substances have been investigated for the past two decades. Amongst the study of new structural phases, defects, chemical reactions and varied types of host-guest interactions, there is one fundamental characterisation aspect of these systems that continues to be overlooked: the mechanical behaviour of filled CNTs. In contrast to their empty counterparts, the mechanics of filled CNTs is a subject where reports appear far and apart, this despite being key to the application of these materials in technological devices. In the following paragraphs, we review the work that has been carried out up to the present on the mechanics of filled CNTs. The studies discussed range from experimental resonant frequency essays performed within electron microscopes to modelling, via molecular dynamics, of three-point bending of nanotubes filled with gases. (C) 2014 Elsevier B.V. All rights reserved.

  11. Theory of nanotube faraday cage

    Science.gov (United States)

    Roxana Margine, Elena; Nisoli, Cristiano; Kolmogorov, Aleksey; Crespi, Vincent H.

    2003-03-01

    Charge transfer between dopants and double-wall carbon nanotubes is examined theoretically. We model the system as a triple cylindrical capacitor with the dopants forming a shell around the outer wall of the nanotube. The total energy of the system contains three terms: the band structure energies of the inner and outer tube, calculated in a tight-binding model with rigid bands, and the electrostatic energy of the tri-layer distribution. Even for metallic inner and outer tube walls, wherein the diameter dependence of the bandgap does not favor the outer wall, nearly all of the dopant charge resides on the outer layer, a nanometer-scale Faraday cage. The calculated charge distribution is in agreement with recent experimental measurements.

  12. An impossibility theorem for parameter independent hidden variable theories

    Science.gov (United States)

    Leegwater, Gijs

    2016-05-01

    Recently, Roger Colbeck and Renato Renner (C&R) have claimed that '[n]o extension of quantum theory can have improved predictive power' (Colbeck & Renner, 2011, 2012b). If correct, this is a spectacular impossibility theorem for hidden variable theories, which is more general than the theorems of Bell (1964) and Leggett (2003). Also, C&R have used their claim in attempt to prove that a system's quantum-mechanical wave function is in a one-to-one correspondence with its 'ontic' state (Colbeck & Renner, 2012a). C&R's claim essentially means that in any hidden variable theory that is compatible with quantum-mechanical predictions, probabilities of measurement outcomes are independent of these hidden variables. This makes such variables otiose. On closer inspection, however, the generality and validity of the claim can be contested. First, it is based on an assumption called 'Freedom of Choice'. As the name suggests, this assumption involves the independence of an experimenter's choice of measurement settings. But in the way C&R define this assumption, a no-signalling condition is surreptitiously presupposed, making the assumption less innocent than it sounds. When using this definition, any hidden variable theory violating parameter independence, such as Bohmian Mechanics, is immediately shown to be incompatible with quantum-mechanical predictions. Also, the argument of C&R is hard to follow and their mathematical derivation contains several gaps, some of which cannot be closed in the way they suggest. We shall show that these gaps can be filled. The issue with the 'Freedom of Choice' assumption can be circumvented by explicitly assuming parameter independence. This makes the result less general, but better founded. We then obtain an impossibility theorem for hidden variable theories satisfying parameter independence only. As stated above, such hidden variable theories are impossible in the sense that any supplemental variables have no bearing on outcome probabilities

  13. Thermal stability of titanate nanotubes

    Czech Academy of Sciences Publication Activity Database

    Králová, Daniela; Kužel, R.; Kovářová, Jana; Dybal, Jiří; Šlouf, Miroslav

    2009-01-01

    Roč. 16, 2a (2009), s. 41-43 ISSN 1211-5894. [Struktura - Colloquium of Czech and Slovak Crystallographic Association. Hluboká nad Vltavou, 22.06.2009-25.06.2009] R&D Projects: GA ČR GA203/07/0717; GA AV ČR KAN200520704 Institutional research plan: CEZ:AV0Z40500505 Keywords : titanate nanotubes * thermal stability Subject RIV: CD - Macromolecular Chemistry

  14. Oriented nanotube electrodes for lithium ion batteries and supercapacitors

    Science.gov (United States)

    Frank, Arthur J.; Zhu, Kai; Wang, Qing

    2013-03-05

    An electrode having an oriented array of multiple nanotubes is disclosed. Individual nanotubes have a lengthwise inner pore defined by interior tube walls which extends at least partially through the length of the nanotube. The nanotubes of the array may be oriented according to any identifiable pattern. Also disclosed is a device featuring an electrode and methods of fabrication.

  15. Structural properties of water around uncharged and charged carbon nanotubes

    International Nuclear Information System (INIS)

    Dezfoli, Amir Reza Ansari; Mehrabian, Mozaffar Ali; Rafsanjani, Hassan Hashemipour

    2013-01-01

    Studying the structural properties of water molecules around the carbon nanotubes is very important in a wide variety of carbon nanotubes applications. We studied the number of hydrogen bonds, oxygen and hydrogen density distributions, and water orientation around carbon nanotubes. The water density distribution for all carbon nanotubes was observed to have the same feature. In water-carbon nanotubes interface, a high-density region of water molecules exists around carbon nanotubes. The results reveal that the water orientation around carbon nanotubes is roughly dependent on carbon nanotubes surface charge. The water molecules in close distances to carbon nanotubes were found to make an HOH plane nearly perpendicular to the water-carbon nanotubes interface for carbon nanotubes with negative surface charge. For uncharged carbon nanotubes and carbon nanotubes with positive surface charge, the HOH plane was in tangential orientation with water-carbon nanotubes interface. There was also a significant reduction in hydrogen bond of water region around carbon nanotubes as compared with hydrogen bond in bulk water. This reduction was very obvious for carbon nanotubes with positive surface charge. In addition, the calculation of dynamic properties of water molecules in water-CNT interface revealed that there is a direct relation between the number of Hbonds and self-diffusion coefficient of water molecules

  16. Carbon Nanotubes and Graphene Nanoribbons: Potentials for Nanoscale Electrical Interconnects

    Directory of Open Access Journals (Sweden)

    Swastik Kar

    2013-08-01

    Full Text Available Carbon allotropes have generated much interest among different scientific communities due to their peculiar properties and potential applications in a variety of fields. Carbon nanotubes and more recently graphene have shown very interesting electrical properties along with the possibility of being grown and/or deposited at a desired location. In this Review, we will focus our attention on carbon-based nanostructures (in particular, carbon nanotubes and graphene nanoribbons which could play an important role in the technological quest to replace copper/low-k for interconnect applications. We will provide the reader with a number of possible architectures, including single-wall as well as multi-wall carbon nanotubes, arranged in horizontal and vertical arrays, regarded as individual objects as well as bundles. Modification of their functional properties in order to fulfill interconnect applications requirements are also presented. Then, in the second part of the Review, recently discovered graphene and in particular graphene and few-graphene layers nanoribbons are introduced. Different architectures involving nanostructured carbon are presented and discussed in light of interconnect application in terms of length, chirality, edge configuration and more.

  17. Influence of carbon nanotube length on toxicity to zebrafish embryos

    Directory of Open Access Journals (Sweden)

    Cheng J

    2012-07-01

    Full Text Available Jinping Cheng,1,2 Shuk Han Cheng11Department of Biology and Chemistry, City University of Hong Kong, Hong Kong; 2State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, ChinaAbstract: There is currently a large difference of opinion in nanotoxicology studies of nanomaterials. There is concern about why some studies have indicated that there is strong toxicity, while others have not. In this study, the length of carbon nanotubes greatly affected their toxicity in zebrafish embryos. Multiwalled carbon nanotubes (MWCNTs were sonicated in a nitric acid solution for 24 hours and 48 hours. The modified MWCNTs were tested in early developing zebrafish embryo. MWCNTs prepared with the longer sonication time resulted in severe developmental toxicity; however, the shorter sonication time did not induce any obvious toxicity in the tested developing zebrafish embryos. The cellular and molecular changes of the affected zebrafish embryos were studied and the observed phenotypes scored. This study suggests that length plays an important role in the in vivo toxicity of functionalized CNTs. This study will help in furthering the understanding on current differences in toxicity studies of nanomaterials.Keywords: length, carbon nanotubes, sonication, developmental toxicity, zebrafish

  18. Catalyst design for carbon nanotube growth using atomistic modeling

    International Nuclear Information System (INIS)

    Pint, Cary L; Bozzolo, Guillermo; Hauge, Robert

    2008-01-01

    The formation and stability of bimetallic catalyst particles, in the framework of carbon nanotube growth, is studied using the Bozzolo-Ferrante-Smith (BFS) method for alloys. Monte Carlo-Metropolis simulations with the BFS method are utilized in order to predict and study equilibrium configurations for nanoscale catalyst particles which are directly relevant to the catalyst state prior to growth of carbon nanotubes. At the forefront of possible catalyst combinations is the popular Fe-Mo bimetallic catalyst, which we have recently studied experimentally. We explain our experimental results, which indicate that the growth observed is dependent on the order of co-catalyst deposition, in the straightforward interpretation of BFS strain and chemical energy contributions toward the formation of Fe-Mo catalyst prior to growth. We find that the competition between the formation of metastable inner Mo cores and clusters of surface-segregated Mo atoms in Fe-Mo catalyst particles influences catalyst formation, and we investigate the role of Mo concentration and catalyst particle size in this process. Finally, we apply the same modeling approach to other prominent bimetallic catalysts and suggest that this technique can be a powerful tool to understand and manipulate catalyst design for highly efficient carbon nanotube growth

  19. Synthesis and characterization of conducting polyaniline 5-sulfosalicylate nanotubes

    International Nuclear Information System (INIS)

    Janosevic, Aleksandra; Ciric-Marjanovic, Gordana; Marjanovic, Budimir; Holler, Petr; Trchova, Miroslava; Stejskal, Jaroslav

    2008-01-01

    Conducting polyaniline 5-sulfosalicylate nanotubes and nanorods were synthesized by the template-free oxidative polymerization of aniline in aqueous solution of 5-sulfosalicylic acid, using ammonium peroxydisulfate as an oxidant. The effect of the molar ratio of 5-sulfosalicylic acid to aniline on the molecular structure, molecular weight distribution, morphology, and conductivity of polyaniline 5-sulfosalicylate was investigated. The nanotubes, which have a typical outer diameter of 100-250 nm, with an inner diameter of 10-60 nm, and a length extending from 0.4 to 1.5 μm, and the nanorods, with a diameter of 80-110 nm and a length of 0.5-0.7 μm, were observed by scanning and transmission electron microscopies. The presence of branched structures and phenazine units besides the ordinary polyaniline structural features was revealed by infrared and Raman spectroscopies. The stacking of low-molecular-weight substituted phenazines appears to play a major role in the formation of polyaniline nanorods. The precipitation-dissolution of oligoaniline templates as a key element in the formation of polyaniline nanotubes is proposed to explain the crucial influence of the initial pH of the reaction mixture and its decrease during the course of polymerization

  20. Synthesis and characterization of conducting polyaniline 5-sulfosalicylate nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Janosevic, Aleksandra; Ciric-Marjanovic, Gordana [Faculty of Physical Chemistry, University of Belgrade, Studentski Trg 12-16, 11001 Belgrade (Serbia); Marjanovic, Budimir [Centrohem, Vuka Karadzica bb, 22300 Stara Pazova (Serbia); Holler, Petr; Trchova, Miroslava; Stejskal, Jaroslav [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6 (Czech Republic)], E-mail: gordana@ffh.bg.ac.yu

    2008-04-02

    Conducting polyaniline 5-sulfosalicylate nanotubes and nanorods were synthesized by the template-free oxidative polymerization of aniline in aqueous solution of 5-sulfosalicylic acid, using ammonium peroxydisulfate as an oxidant. The effect of the molar ratio of 5-sulfosalicylic acid to aniline on the molecular structure, molecular weight distribution, morphology, and conductivity of polyaniline 5-sulfosalicylate was investigated. The nanotubes, which have a typical outer diameter of 100-250 nm, with an inner diameter of 10-60 nm, and a length extending from 0.4 to 1.5 {mu}m, and the nanorods, with a diameter of 80-110 nm and a length of 0.5-0.7 {mu}m, were observed by scanning and transmission electron microscopies. The presence of branched structures and phenazine units besides the ordinary polyaniline structural features was revealed by infrared and Raman spectroscopies. The stacking of low-molecular-weight substituted phenazines appears to play a major role in the formation of polyaniline nanorods. The precipitation-dissolution of oligoaniline templates as a key element in the formation of polyaniline nanotubes is proposed to explain the crucial influence of the initial pH of the reaction mixture and its decrease during the course of polymerization.