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Sample records for hexagonal critical experiments

  1. Experiment and numerical modeling of asymmetrically initiated hexagonal prism warhead

    Directory of Open Access Journals (Sweden)

    Yuan Li

    2017-01-01

    Full Text Available Traditional fragmentation warheads are usually initiated on the axis, producing a uniform fragment distribution around the warhead, but only little portion of them can be imposed on the targets. The aimable warhead, on the other hand, using the off-axis initiations or the structure deforming, can improve the warhead energy utilization highly. Seeking methods to both enhance the fragment velocity and density has significant value for improving the target damage probability. In this article, a warhead shaped as hexagonal prism was studied using arena experiment and numerical modeling and compared with the traditional cylindrical structure. The fragment velocities and target hit patterns of the two types of warheads under axial initiation and asymmetrical initiation are obtained. It is revealed that for the hexagonal prism warhead, the asymmetrical initiation can enhance the fragment velocities by 27.71% and enhance fragment density by 34.09% compared to the axial initiation. The fragment velocity enhancement is close to that of the cylindrical warhead, but the fragment density enhancement is far above the cylindrical warhead. This indicates that the asymmetrically initiated hexagonal prism warhead is a very effective aimable warhead.

  2. Fabrication Improvement of Cold Forging Hexagonal Nuts by Computational Analysis and Experiment Verification

    Directory of Open Access Journals (Sweden)

    Shao-Yi Hsia

    2015-01-01

    Full Text Available Cold forging has played a critical role in fasteners and has been applied to the automobile industry, construction industry, aerospace industry, and living products so that cold forging presents the opportunities for manufacturing more products. By using computer simulation, this study attempts to analyze the process of creating machine parts, such as hexagonal nuts. The DEFORM-3D forming software is applied to analyze the process at various stages in the computer simulation, and the compression test is also used for the flow stress equation in order to compare the differences between the experimental results and the equation that is built into the computer simulation software. At the same time, the metallography and hardness of experiments are utilized to understand the cold forging characteristics of hexagonal nuts. The research results would benefit machinery businesses to realize the forging load and forming conditions at various stages before the fastener formation. In addition to planning proper die design and production, the quality of the produced hexagonal nuts would be more stable to promote industrial competitiveness.

  3. Theoretical study on critical thickness of heteroepitaxial h-BN on hexagonal crystals

    Science.gov (United States)

    Yu, Jiadong; Wang, Lai; Hao, Zhibiao; Luo, Yi; Sun, Changzheng; Han, Yanjun; Xiong, Bing; Wang, Jian; Li, Hongtao

    2017-06-01

    Hexagonal crystals are suitable underlayer candidates for hexagonal boron nitride (h-BN) heteroepitaxy due to their similar in-plane atomic arrangement. When the thickness of h-BN is beyond a critical value, its accumulated stress resulting from the lattice mismatch can be relaxed by generating dislocation or changing into three-dimensional growth. Here we calculate the evolution of h-BN critical thickness with the growth temperature when it is grown on various frequently-used hexagonal crystals for both cases. The results show that in order to minimize the lattice mismatch, a low growth temperature is preferred when grown on GaN or Si(1 1 1) while on the contrary when grown on 6H-SiC or α-Al2O3. Besides, AlN is the most unique underlayer as its lattice mismatch with h-BN is relatively small (100 nm) growth. Moreover, large area of two-dimensional thin h-BN (5-15 nm) layer can be obtained on GaN, 6H-SiC, Si(1 1 1) or α-Al2O3 except for graphene. On the other hand, calculation indicates that large area of graphene can be grown on h-BN.

  4. Lattice dynamics of hexagonal and cubic InN: Raman-scattering experiments and calculations

    Science.gov (United States)

    Kaczmarczyk, G.; Kaschner, A.; Reich, S.; Hoffmann, A.; Thomsen, C.; As, D. J.; Lima, A. P.; Schikora, D.; Lischka, K.; Averbeck, R.; Riechert, H.

    2000-04-01

    We present results of first- and second-order Raman-scattering experiments on hexagonal and cubic InN covering the acoustic and optical phonon and overtone region. Using a modified valence-force model, we calculated the phonon dispersion curves and the density of states in both InN modifications. The observed Raman shifts agree well the calculated Γ-point frequencies and the corresponding overtone density of states. A tentative assignment to particular phonon branches is given.

  5. Evaluation of Saxton critical experiments

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Hyung Kook; Noh, Jae Man; Jung, Hyung Guk; Kim, Young Il; Kim, Young Jin [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    As a part of International Criticality Safety Benchmark Evaluation Project (ICSBEP), SAXTON critical experiments were reevaluated. The effects of k{sub eff} of the uncertainties in experiment parameters, fuel rod characterization, soluble boron, critical water level, core structure, {sup 241}Am and {sup 241}Pu isotope number densities, random pitch error, duplicated experiment, axial fuel position, model simplification, etc., were evaluated and added in benchmark-model k{sub eff}. In addition to detailed model, the simplified model for Saxton critical experiments was constructed by omitting the top, middle, and bottom grids and ignoring the fuel above water. 6 refs., 1 fig., 3 tabs. (Author)

  6. Critical velocity experiments in space

    Science.gov (United States)

    Torbert, R. B.

    1988-01-01

    Published data from active space experiments designed to demonstrate the Alfven critical-velocity effect are compiled in graphs and compared with the predictions of numerical simulations. It is found that the discrepancies in the ionization yields obtained in shaped-charge releases of alkali metals are related to the macroscopic limits of time and energy in such releases. It is argued that the total ionization yield is an inadequate measure of the critical-velocity effect, and a new criterion based on eta, the efficiency of energy transfer from the recently ionized neutrals to a heated electron population, is proposed: the effect would be verified if eta values of 10 percent or greater were observed.

  7. Verification of HELIOS-MASTER system through benchmark of critical experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ha Yong; Kim, Kyo Yun; Cho, Byung Oh; Lee, Chung Chan; Zee, Sung Quun

    1999-03-01

    HELIOS-MASTER code system is verified through the benchmark of the critical experiments that were performed by RRC Kurchatov Institute with water moderated hexagonally pitched lattices of highly enriched uranium fuel rods (80w/o). We also used the same input by using MCNP code that was described in evaluation report, and compare our results with those of evaluation report. HELIOS developed by Scandpower A/S is a two-dimensional transport program for generation of group cross sections and MASTER developed by KAERI is a three-dimensional nuclear design and analysis code based on the two group diffusion theory. It solves neutronics model with AFEN (Analytic Function Expansion Nodal) method for hexagonal geometry. The results show that HELIOS-MASTER code system is fast and accurate enough so that this code system can be used as nuclear core analysis tool for hexagonal geometry. (author). 4 refs., 4 tabs., 10 figs.

  8. Forced and gravity reflood experiments in hexagonal bundle lattices. Final report; Zwangs- und Schwerkraftflutversuche an hexagonalen Stabbuendelgeometrien; Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Wiehr, K.; Erbacher, F.; Just, W.; Harten, U.; Schmidt, H.

    1993-11-01

    This report describes reflooding experiments in two different fuel rod simulator bundles (FRSB) with hexagonal lattices in different bundle geometries and different pitch over diameter (p/d) ratios. The bundles consist of 16 electrically heated fuel rod simulators with a cosine shaped axial power profile. The tight bundle (p/d=1,06) has steel claddings with integrated helical fins as spacers, whereas the wider bundle (p/d=1,24) is equipped with grid spacers and with Zircaloy claddings typical of a convoy PWR. This report delivers mainly the data base for modelers in order to verify and further develop reflooding codes (e.g. ATHLET, RELAP) for hexagonal fuel lattices. Presently this is of immediate interest for the hexagonal fuel elements of Russian VVER`s and other advanced reactor concepts. The experimental data of a total of 45 experiments (most of them with forced feed and some of them with gravity feed) are stored on data tapes and data discs of the KfK IBM 3090. To find the proper experiments described for calculations, this report contains schematic figures of the test loop, the instrumentation of the bundle and the whole test section. The test parameters are listed in tables. To facilitate the identification of the experiments, the cladding temperatures of the inner 37 fuel rod simulators, the axial cladding temperatures and the total pressure drop of the bundle are plotted. A user description for the experimental data and the corresponding measuring channel list of each experiment enables to find the proper test. In the appendix the material properties to model the rod simulator are given. (orig.) [Deutsch] Dieser Bericht beschreibt Flutexperimente an zwei Brennstabsimulatorbuendeln mit hexagonaler Stabanordnung unterschiedlicher Buendelgeometrie. Die Buendel bestehen aus jeweils 61 Brennstabsimulatoren (BSS) mit einem cosinusfoermigen axialen Leistungsprofil, wobei das sehr enge Buendel (p/d=1,06) mit Stahlhuellen mit integrierten Wendelrippen als

  9. Critical experiments with mixed oxide fuel

    Energy Technology Data Exchange (ETDEWEB)

    Harris, D.R. [Rensselaer Polytechnic Institute, Troy, NY (United States)

    1997-06-01

    This paper very briefly outlines technical considerations in performing critical experiments on weapons-grade plutonium mixed oxide fuel assemblies. The experiments proposed would use weapons-grade plutonium and Er{sub 2}O{sub 3} at various dissolved boron levels, and for specific fuel assemblies such as the ABBCE fuel assembly with five large water holes. Technical considerations described include the core, the measurements, safety, security, radiological matters, and licensing. It is concluded that the experiments are feasible at the Rensselaer Polytechnic Institute Reactor Critical Facility. 9 refs.

  10. What's so critical about Critical Neuroscience? Rethinking experiment, enacting critique.

    Science.gov (United States)

    Fitzgerald, Des; Matusall, Svenja; Skewes, Joshua; Roepstorff, Andreas

    2014-01-01

    In the midst of on-going hype about the power and potency of the new brain sciences, scholars within "Critical Neuroscience" have called for a more nuanced and sceptical neuroscientific knowledge-practice. Drawing especially on the Frankfurt School, they urge neuroscientists towards a more critical approach-one that re-inscribes the objects and practices of neuroscientific knowledge within webs of social, cultural, historical and political-economic contingency. This paper is an attempt to open up the black-box of "critique" within Critical Neuroscience itself. Specifically, we argue that limiting enactments of critique to the invocation of context misses the force of what a highly-stylized and tightly-bound neuroscientific experiment can actually do. We show that, within the neuroscientific experiment itself, the world-excluding and context-denying "rules of the game" may also enact critique, in novel and surprising forms, while remaining formally independent of the workings of society, and culture, and history. To demonstrate this possibility, we analyze the Optimally Interacting Minds (OIM) paradigm, a neuroscientific experiment that used classical psychophysical methods to show that, in some situations, people worked better as a collective, and not as individuals-a claim that works precisely against reactionary tendencies that prioritize individual over collective agency, but that was generated and legitimized entirely within the formal, context-denying conventions of neuroscientific experimentation. At the heart of this paper is a claim that it was precisely the rigors and rules of the experimental game that allowed these scientists to enact some surprisingly critical, and even radical, gestures. We conclude by suggesting that, in the midst of large-scale neuroscientific initiatives, it may be "experiment", and not "context", that forms the meeting-ground between neuro-biological and socio-political research practices.

  11. An Explanation for Saturn's Hexagon

    Science.gov (United States)

    Kohler, Susanna

    2015-08-01

    For over three decades, weve been gathering observations of the mysterious hexagonal cloud pattern encircling Saturns north pole. Now, researchers believe they have a model that can better explain its formation.Fascinating GeometrySaturns northern Hexagon is a cloud band circling Saturns north pole at 78 N, first observed by the Voyager flybys in 198081. This remarkable pattern has now persisted for more than a Saturn year (29.5 Earth years).Eight frames demonstrating the motion within Saturns Hexagon. Click to watch the animation! The view is from a reference frame rotating with Saturn. [NASA/JPL-Caltech/SSI/Hampton University]Observations by Voyager and, more recently, Cassini have helped to identify many key characteristics of this bizarre structure. Two interesting things weve learned are:The Hexagon is associated with an eastward zonal jet moving at more than 200 mph.The cause of the Hexagon is believed to be a jet stream, similar to the ones that we experience on Earth. The path of the jet itself appears to follow the hexagons outline.The Hexagon rotates at roughly the same rate as Saturns overall rotation.While we observe individual storms and cloud patterns moving at different speeds within the Hexagon, the vertices of the Hexagon move at almost exactly the same rotational speed as that of Saturn itself.Attempts to model the formation of the Hexagon with a jet stream have yet to fully reproduce all of the observed features and behavior. But now, a team led by Ral Morales-Juberas of the New Mexico Institute of Mining and Technology believes they have created a model that better matches what we see.Simulating a Meandering JetThe team ran a series of simulations of an eastward, Gaussian-profile jet around Saturns pole. They introduced small perturbations to the jet and demonstrated that, as a result of the perturbations, the jet can meander into a hexagonal shape. With the initial conditions of the teams model, the meandering jet is able to settle into a

  12. A second simulated criticality accident dosimetry experiment

    CERN Document Server

    Adams, N

    1973-01-01

    This experiment was undertaken to facilitate training in criticality dose assessment by UKAEA and BNFL establishments with potential criticality hazards. Personal dosemeters, coins, samples of hair, etc. supplied by the seven participating establishments were attached to a man-phantom filled with a solution of sodium nitrate (simulating 'body-sodium'), and exposed to a burst of radiation from the AWRE pulsed reactor VIPER. The neutron and photon doses were each several hundred rads. Participants made two sets of dose assessments. The first, made solely from the evidence of their routine dosemeters the activation of body-sodium and standard monitoring data, simulated the initial dose assessment that would be made before the circumstances of a real incident were established. The second was made when the position and orientation of the phantom relative to the reactor and the shielding (20 cm of copper) between the reactor core and the phantom were disclosed. Neutron and photon dose assessments for comparison wit...

  13. The Zeus Copper/Uranium Critical Experiment at NCERC

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Rene G. [Los Alamos National Laboratory; Hayes, David K. [Los Alamos National Laboratory; Bounds, John Alan [Los Alamos National Laboratory; Jackman, Kevin R. [Los Alamos National Laboratory; Goda, Joetta M. [Los Alamos National Laboratory

    2012-06-15

    A critical experiment was performed to provide nuclear data in a non-thermal neutron spectrum and to reestablish experimental capability relevant to Stockpile Stewardship and Technical Nuclear Forensic programs. Irradiation foils were placed at specific locations in the Zeus all oralloy critical experiment to obtain fission ratios. These ratios were compared with others from other critical assemblies to assess the degree of softness in the neutron spectrum. This critical experiment was performed at the National Criticality Experiments Research Center (NCERC) in Nevada.

  14. A magnetospheric critical velocity experiment - Particle results

    Science.gov (United States)

    Torbert, R. B.; Newell, P. T.

    1986-01-01

    In March of 1983, a barium injection sounding rocket experiment (The Star of Lima) was conducted to investigate Alfven's critical ionization velocity (CIV) hypothesis in space. Included in the instrumented payload was a particle detection experiment consisting of five retarding potential analyzers. Despite conditions that appeared to be optimal for the critical velocity effect, the particle data, in agreement with optical observations, indicates that a fractional ionization of only approximately .0005 was observed, indicating that the conditions required for the effect to occur are still not well understood. However many of the required phenomena associated with the CIV effect were observed; in particular a superthermal electron population was formed at the expense of ion drift kinetic energy in the presence of intense electrostatic waves near the lower hybrid frequency. The amount of ionization produced is plausibly consistent with the observed electron flux, but could also be accounted for by residual solar UV at the injection point. It is shown based on the data set that one obvious explanation for the low ionization efficiency, namely that the ionizing superthermal electrons may rapidly escape along field lines, can be ruled out.

  15. (abstract) Modeling the Critical Velocity Ionization Experiment Interaction

    Science.gov (United States)

    Wang, J.; Murphy, G.; Biasca, R.

    1993-01-01

    Proper interpretation of critical velocity ionization experiments depends upon understanding the expected results from in-situ or remote sensors. In particular, the 1991 shuttle based CIV experiment had diagnostics.

  16. Hexagon solar power panel

    Science.gov (United States)

    Rubin, Irwin

    1978-01-01

    A solar energy panel comprises a support upon which silicon cells are arrayed. The cells are wafer thin and of two geometrical types, both of the same area and electrical rating, namely hexagon cells and hourglass cells. The hourglass cells are composites of half hexagons. A near perfect nesting relationship of the cells achieves a high density packing whereby optimum energy production per panel area is achieved.

  17. Hexagon solar power panel

    Science.gov (United States)

    Rubin, I. (Inventor)

    1978-01-01

    A solar energy panel support is described upon which silicon cells are arrayed. The cells are wafer thin and of two geometrical types, both of the same area and electrical rating, namely hexagon cells and hourglass cells. The hourglass cells are composites of half hexagons. A near perfect nesting relationship of the cells achieves a high density packing whereby optimum energy production per panel area is achieved.

  18. History of critical experiments at Pajarito Site

    Energy Technology Data Exchange (ETDEWEB)

    Paxton, H.C.

    1983-03-01

    This account describes critical and subcritical assemblies operated remotely at the Pajarito Canyon Site at the Los Alamos National Laboratory. Earliest assemblies, directed exclusively toward the nuclear weapons program, were for safety tests. Other weapon-related assemblies provided neutronic information to check detailed weapon calculations. Topsy, the first of these critical assemblies, was followed by Lady Godiva, Jezebel, Flattop, and ultimately Big Ten. As reactor programs came to Los Alamos, design studies and mockups were tested at Pajarito Site. For example, nearly all 16 Rover reactors intended for Nevada tests were preceded by zero-power mockups and proof tests at Pajarito Site. Expanded interest and capability led to fast-pulse assemblies, culminating in Godiva IV and Skua, and to the Kinglet and Sheba solution assemblies.

  19. Critical phenomena experiments in space. [for fluid phase-equilibrium

    Science.gov (United States)

    Sengers, J. V.; Moldover, M. R.

    1978-01-01

    The paper analyzes several types of critical phenomena in fluids, shows how they are affected by the presence of gravity, and describes how experiments conducted in an orbiting laboratory under low gravity conditions could extend the range of measurements needed to study critical phenomena. Future experiments are proposed. One would be a careful measurement of the dielectric constant in a low gravity environment. Two basic problems that can benefit especially from space experiments are the specific heat near the critical point and the shear viscosity at the gas-liquid critical point.

  20. The impact and applicability of critical experiment evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Brewer, R. [Los Alamos National Lab., NM (United States)

    1997-06-01

    This paper very briefly describes a project to evaluate previously performed critical experiments. The evaluation is intended for use by criticality safety engineers to verify calculations, and may also be used to identify data which need further investigation. The evaluation process is briefly outlined; the accepted benchmark critical experiments will be used as a standard for verification and validation. The end result of the project will be a comprehensive reference document.

  1. Standardized measures of critical thinking. Experience with the California Critical Thinking Tests.

    Science.gov (United States)

    Leppa, C J

    1997-01-01

    Standardized measures of student critical thinking are an attractive option for nursing educators under pressure to demonstrate student higher order thinking skills. One program's experience using the California Critical Thinking Skills Test and the California Critical Thinking Dispositions Inventory illustrates some of the problems of using standardized test and potential solutions.

  2. Des hexagones dans l'Hexagone

    Directory of Open Access Journals (Sweden)

    Sylvie ADAM

    1989-12-01

    Full Text Available L'approche des lieux centraux est plus qu'un simple exercice théorique. Elle peut guider la réflexion sur les problèmes actuels, car elle rend compte de l'héritage historique tout autant que des transformations actuelles. Au niveau 5, la trame de la France du Nord-Est est orientée différemment de celle du reste du pays, mais la taille des hexagones est la même dans les deux cas (126 km. Au niveau 6, seuls quelques grands systèmes métropolitains apparaissent.

  3. Spiritual Experiences of Muslim Critical Care Nurses.

    Science.gov (United States)

    Bakir, Ercan; Samancioglu, Sevgin; Kilic, Serap Parlar

    2017-12-01

    The purpose of this study was to determine the experiences and perceptions of intensive care nurses (ICNs) about spirituality and spiritual care, as well as the effective factors, and increase the sensitivity to the subject. In this study, we examined spiritual experiences, using McSherry et al. (Int J Nurs Stud 39:723-734, 2002) Spirituality and spiritual care rating scale (SSCRS), among 145 ICNs. 44.8% of the nurses stated that they received spiritual care training and 64.1% provided spiritual care to their patients. ICNs had a total score average of 57.62 ± 12.00 in SSCRS. As a consequence, it was determined that intensive care nurses participating in the study had insufficient knowledge about spirituality and spiritual care, but only the nurses with sufficient knowledge provided the spiritual care to their patients.

  4. Implementing NICU critical thinking programs: one unit's experience.

    Science.gov (United States)

    Zimmerman, Denise; Pilcher, Jobeth

    2008-01-01

    Critical thinking is the hallmark of today's nursing practice environment. Nowhere is this more critical than in the high-tech environment of the NICU. Despite the importance of critical thinking in nursing practice, there is limited information on the process of teaching new NICU nurses to think critically. Based on the principles of adult education, orientation and continuing education for NICU nurses should be goal directed, build on the learner's prior experience, and build in opportunities for active participation, reflection, and experiential learning. This article reviews the principles of adult education and their application to the process of teaching critical thinking in the NICU. One unit's experience of critical thinking education is used to provide concrete examples of how NICU education can be transformed from a traditional didactic methodology to a more dynamic experiential approach.

  5. Critical Thinking in Students' Service-Learning Experiences.

    Science.gov (United States)

    Sedlak, Carol A.; Doheny, Margaret O.; Anaya, Ella; Panthofer, Nancy

    2003-01-01

    Sought to describe the growth of 94 nursing students' critical thinking through service-learning experiences. Results revealed two major themes: development of both professional and community perspectives. (EV)

  6. Deconstructing Global Markets through Critical Performative Experiences in Puerto Rico

    Science.gov (United States)

    Medina, Carmen Liliana; Weltsek, Gustave J.

    2013-01-01

    Critical Performative Pedagogies, the idea that "The nature of drama as a once removed creative experience turns non-critical implicit classroom identity formation into explicit identity performance as it asks participants to actively reflect upon how identity is created and engaged within fictional social interactions." (Weltsek and…

  7. Designing Nursing Simulation Clinical Experiences to Promote Critical Inquiry

    Science.gov (United States)

    Beattie, Bev; Koroll, Donna; Price, Susan

    2010-01-01

    The use of high fidelity simulation (HFS) learning opportunities in nursing education has received increased attention in the literature. This article describes the design of a systematic framework used to promote critical inquiry and provide meaningful simulation clinical experiences for second year nursing students. Critical inquiry, as defined…

  8. Attachment Theory in Supervision: A Critical Incident Experience

    Science.gov (United States)

    Pistole, M. Carole; Fitch, Jenelle C.

    2008-01-01

    Critical incident experiences are a powerful source of counselor development (T. M. Skovholt & P. R. McCarthy, 1988a, 1988b) and are relevant to attachment issues. An attachment theory perspective of supervision is presented and applied to a critical incident case scenario. By focusing on the behavioral systems (i.e., attachment, caregiving, and…

  9. Weightless experiments to probe universality of fluid critical behavior.

    Science.gov (United States)

    Lecoutre, C; Guillaument, R; Marre, S; Garrabos, Y; Beysens, D; Hahn, I

    2015-06-01

    Near the critical point of fluids, critical opalescence results in light attenuation, or turbidity increase, that can be used to probe the universality of critical behavior. Turbidity measurements in SF6 under weightlessness conditions on board the International Space Station are performed to appraise such behavior in terms of both temperature and density distances from the critical point. Data are obtained in a temperature range, far (1 K) from and extremely close (a few μK) to the phase transition, unattainable from previous experiments on Earth. Data are analyzed with renormalization-group matching classical-to-critical crossover models of the universal equation of state. It results that the data in the unexplored region, which is a minute deviant from the critical density value, still show adverse effects for testing the true asymptotic nature of the critical point phenomena.

  10. Weightless experiments to probe universality of fluid critical behavior

    Science.gov (United States)

    Lecoutre, C.; Guillaument, R.; Marre, S.; Garrabos, Y.; Beysens, D.; Hahn, I.

    2015-06-01

    Near the critical point of fluids, critical opalescence results in light attenuation, or turbidity increase, that can be used to probe the universality of critical behavior. Turbidity measurements in SF6 under weightlessness conditions on board the International Space Station are performed to appraise such behavior in terms of both temperature and density distances from the critical point. Data are obtained in a temperature range, far (1 K) from and extremely close (a few μ K ) to the phase transition, unattainable from previous experiments on Earth. Data are analyzed with renormalization-group matching classical-to-critical crossover models of the universal equation of state. It results that the data in the unexplored region, which is a minute deviant from the critical density value, still show adverse effects for testing the true asymptotic nature of the critical point phenomena.

  11. Nonlinear Competition Between Small and Large Hexagonal Patterns

    CERN Document Server

    Silber, M; Silber, Mary; Proctor, Michael R.E.

    1998-01-01

    Recent experiments by Kudrolli, Pier and Gollub on surface waves, parametrically excited by two-frequency forcing, show a transition from a small hexagonal standing wave pattern to a large triangular superlattice pattern. We show that generically the small hexagonal and the large triangular wave patterns bifurcate simultaneously from the flat surface state as the forcing amplitude is increased, and that the experimentally-observed transition can be described by considering a low-dimensional degenerate bifurcation problem. In particular, the transition from the small hexagonal pattern to the triangular superlattice pattern can be favored over the ubiquitous hexagons-to-rolls transition.

  12. Medical Education to Enhance Critical Consciousness: Facilitators' Experiences.

    Science.gov (United States)

    Zaidi, Zareen; Vyas, Rashmi; Verstegen, Danielle; Morahan, Page; Dornan, Tim

    2017-11-01

    To analyze educators' experiences of facilitating cultural discussions in two global health professions education programs and what these experiences had taught them about critical consciousness. A multicultural research team conducted in-depth interviews with 16 faculty who had extensive experience facilitating cultural discussions. They analyzed transcripts of the interviews thematically, drawing sensitizing insights from Gramsci's theory of cultural hegemony. Collaboration and conversation helped the team self-consciously examine their positions toward the data set and be critically reflexive. Participant faculty used their prior experience facilitating cultural discussions to create a "safe space" in which learners could develop critical consciousness. During multicultural interactions they recognized and explicitly addressed issues related to power differentials, racism, implicit bias, and gender bias. They noted the need to be "facile in attending to pain" as learners brought up traumatic experiences and other sensitive issues including racism and the impact of power dynamics. They built relationships with learners by juxtaposing and exploring the sometimes-conflicting norms of different cultures. Participants were reflective about their own understanding and tendency to be biased. They aimed to break free of such biases while role modeling how to have the courage to speak up. Experience had given facilitators in multicultural programs an understanding of their responsibility to promote critical consciousness and social justice. How faculty without prior experience or expertise could develop those values and skills is a topic for future research.

  13. Hexagonal Data Base Study.

    Science.gov (United States)

    1983-09-01

    Attribute Data Manegement 0 I GRAM itself has limited attribute data handling capabilities. Such information about nodes as their degree and whether...geographic information . This report presents theresults of an expermental software implementation utilizing hexagonal dat s uctresasapplied to test data... information . The project described in this report was performed to assess the capabilities of the techniques in data representation and handling which have

  14. Hexagonal quartz resonator

    Science.gov (United States)

    Peters, Roswell D. M.

    1982-01-01

    A generally flat, relatively thin AT-cut piezoelectric resonator element structured to minimize the force-frequency effect when mounted and energized in a housing. The resonator is in the form of an equilateral hexagon with the X crystallographic axis of the crystal passing through one set of opposing corners with mounting being effected at an adjacent set of corners respectively .+-.60.degree. away from the X axis which thereby results in a substantially zero frequency shift of the operating frequency.

  15. Hexagonalization of correlation functions

    Energy Technology Data Exchange (ETDEWEB)

    Fleury, Thiago [Instituto de Física Teórica, UNESP - University Estadual Paulista,ICTP South American Institute for Fundamental Research,Rua Dr. Bento Teobaldo Ferraz 271, 01140-070, São Paulo, SP (Brazil); Komatsu, Shota [Perimeter Institute for Theoretical Physics,31 Caroline St N Waterloo, Ontario N2L 2Y5 (Canada)

    2017-01-30

    We propose a nonperturbative framework to study general correlation functions of single-trace operators in N=4 supersymmetric Yang-Mills theory at large N. The basic strategy is to decompose them into fundamental building blocks called the hexagon form factors, which were introduced earlier to study structure constants using integrability. The decomposition is akin to a triangulation of a Riemann surface, and we thus call it hexagonalization. We propose a set of rules to glue the hexagons together based on symmetry, which naturally incorporate the dependence on the conformal and the R-symmetry cross ratios. Our method is conceptually different from the conventional operator product expansion and automatically takes into account multi-trace operators exchanged in OPE channels. To illustrate the idea in simple set-ups, we compute four-point functions of BPS operators of arbitrary lengths and correlation functions of one Konishi operator and three short BPS operators, all at one loop. In all cases, the results are in perfect agreement with the perturbative data. We also suggest that our method can be a useful tool to study conformal integrals, and show it explicitly for the case of ladder integrals.

  16. Jezebel: Reconstructing a Critical Experiment from 60 Years Ago

    Energy Technology Data Exchange (ETDEWEB)

    Favorite, Jeffrey A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-15

    The Jezebel experiment of 1954-1955 was a very small, nearly-spherical, nearly-bare (unreflected), nearly-homogeneous assembly of plutonium alloyed with gallium. This experiment was used to determine the critical mass of spherical, bare, homogeneous Pu-alloy. In 1956, the critical mass of Pu-alloy was determined to be 16.45 ± 0.05 kg. The experiment was reevaluated in 1969 using logbooks from the 1950s and updated nuclear cross sections. The critical mass of Pu-alloy was determined to be 16.57 ± 0.10 kg. In 2013, the 239Pu Jezebel experiment was again reevaluated, this time using detailed geometry and materials models and modern nuclear cross sections in high-fidelity Monte Carlo neutron transport calculations. Documentation from the 1950s was often inconsistent or missing altogether, and assumptions had to be made. The critical mass of Pu-alloy was determined to be 16.624 ± 0.075 kg. Historic documents were subsequently found that validated some of the 2013 assumptions and invalidated others. In 2016, the newly found information was used to once again reevaluate the 239Pu Jezebel experiment. The critical mass of Pu-alloy was determined to be 16.624 ± 0.065 kg. This talk will discuss each of these evaluations, focusing on the calculation of the uncertainty as well as the critical mass. We call attention to the ambiguity, consternation, despair, and euphoria involved in reconstructing the historic Jezebel experiment. This talk is quite accessible for undergraduate students as well as non-majors.

  17. Critical experiments analysis by ABBN-90 constant system

    Energy Technology Data Exchange (ETDEWEB)

    Tsiboulia, A.; Nikolaev, M.N.; Golubev, V. [Institute of Physics and Power Engineering, Obninsk (Russian Federation)] [and others

    1997-06-01

    The ABBN-90 is a new version of the well-known Russian group-constant system ABBN. Included constants were calculated based on files of evaluated nuclear data from the BROND-2, ENDF/B-VI, and JENDL-3 libraries. The ABBN-90 is intended for the calculation of different types of nuclear reactors and radiation shielding. Calculations of criticality safety and reactivity accidents are also provided by using this constant set. Validation of the ABBN-90 set was made by using a computerized bank of evaluated critical experiments. This bank includes the results of experiments conducted in Russia and abroad of compact spherical assemblies with different reflectors, fast critical assemblies, and fuel/water-solution criticalities. This report presents the results of the calculational analysis of the whole collection of critical experiments. All calculations were produced with the ABBN-90 group-constant system. Revealed discrepancies between experimental and calculational results and their possible reasons are discussed. The codes and archives INDECS system is also described. This system includes three computerized banks: LEMEX, which consists of evaluated experiments and their calculational results; LSENS, which consists of sensitivity coefficients; and LUND, which consists of group-constant covariance matrices. The INDECS system permits us to estimate the accuracy of neutronics calculations. A discussion of the reliability of such estimations is finally presented. 16 figs.

  18. Validation of KENO V.a Comparison with Critical Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, W.C.

    1999-01-01

    Section 1 of this report documents the validation of KENO V.a against 258 critical experiments. Experiments considered were primarily high or low enriched uranium systems. The results indicate that the KENO V.a Monte Carlo Criticality Program accurately calculates a broad range of critical experiments. A substantial number of the calculations showed a positive or negative bias in excess of 1 1/2% in k-effective (k{sub eff}). Classes of criticals which show a bias include 3% enriched green blocks, highly enriched uranyl fluoride slab arrays, and highly enriched uranyl nitrate arrays. If these biases are properly taken into account, the KENO V.a code can be used with confidence for the design and criticality safety analysis of uranium-containing systems. Section 2 of this report documents the results of investigation into the cause of the bias observed in Sect. 1. The results of this study indicate that the bias seen in Sect. 1 is caused by code bias, cross-section bias, reporting bias, and modeling bias. There is evidence that many of the experiments used in this validation and in previous validations are not adequately documented. The uncertainty in the experimental parameters overshadows bias caused by the code and cross sections and prohibits code validation to better than about 1% in k{sub eff}.

  19. Experiences of critical incidents among female and male firefighters.

    Science.gov (United States)

    Jacobsson, Ann; Backteman-Erlanson, Susann; Brulin, Christine; Hörnsten, Åsa

    2015-04-01

    A critical incident is defined as an event stressful enough to overwhelm the usually effective coping skills of an individual. Firefighters are frequently exposed to critical incidents that might have consequences for individuals and their performance in organization. The aim of this study was to describe experiences of critical incidents among female and male Swedish firefighters. In all 180 participants (16 women, 164 men) who had been involved in up to 25 critical incidents during the last year responded to a survey describing critical incidents experienced in the past year. A qualitative content analysis identified several areas for improvement in firefighters' working conditions. Female firefighters were terse in describing their experiences, while the men described their experiences of critical events more vividly. The critical incidents described by the firefighters concerned such overwhelming situations as traffic accidents, huge fires, and other fatal incidents such as drownings and suicides. Risk of delay due to lack of equipment training and lack of medical education was mentioned. Lack of resources and organizational problems was mentioned as causing risks of failure. Several firefighters expressed frustration over being assaulted and threatened, or exposed to other kinds of violence. Not knowing how close, physically or mentally, one can get to people during ongoing rescue can lead to unsuccessful operations. Gender patterns should always be taken into account, making it possible for all firefighters to express and reflect on existentially tough experiences. Education needs to focus more on medical and mental health issues. Firefighters were sometimes exposed to the difficult challenge of violence and assault during rescue operations. The complexity of this problem needs to be highlighted, not only in firefighter organizations, but also in society in general. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Enhancing critical thinking in the preceptorship experience in nursing education.

    Science.gov (United States)

    Myrick, Florence; Yonge, Olive

    2004-02-01

    To date no research has been conducted to examine the process used in the preceptorship experience to enhance critical thinking at the graduate level. This study provides data that could revitalize the preceptor/learner relationship and in turn influence future preceptorship programmes in graduate nursing education. The purpose of this study was to examine the preceptorship experience and its role in the enhancement of critical thinking in graduate nursing education. A grounded theory approach was employed, through semi-structured, tape-recorded interviews. Overall, 45 interviews were completed with graduate nursing students ranging in age from 26 to 53 years, and master's and doctorally prepared preceptors who ranged in age from 47 to 58 years. In addition, a journal of personal reflections was kept by each of the researchers. Analysis of data included the process of open coding, theoretical coding, selective coding, reduction and comparison. Data revealed that a process, designated The Relational Process, occurred in the preceptorship experience to enhance the critical thinking ability of graduate nursing students. This process was found to be a complex, ongoing interpersonal dynamic between the graduate student and assigned preceptor. The relational process that emerged from this study indicates that specific preceptor behaviours are pivotal to the enhancement of critical thinking of graduate nursing students and ultimately impact on the success or failure of the preceptorship experience.

  1. Implementation and Critical Assessment of the Flipped Classroom Experience

    Science.gov (United States)

    Scheg, Abigail G., Ed.

    2015-01-01

    In the past decade, traditional classroom teaching models have been transformed in order to better promote active learning and learner engagement. "Implementation and Critical Assessment of the Flipped Classroom Experience" seeks to capture the momentum of non-traditional teaching methods and provide a necessary resource for individuals…

  2. Hexagonal graphene quantum dots

    KAUST Repository

    Ghosh, Sumit

    2016-12-05

    We study hexagonal graphene quantum dots, using density functional theory, to obtain a quantitative description of the electronic properties and their size dependence, considering disk and ring geometries with both armchair and zigzag edges. We show that the electronic properties of quantum dots with armchair edges are more sensitive to structural details than those with zigzag edges. As functions of the inner and outer radii, we find in the case of armchair edges that the size of the band gap follows distinct branches, while in the case of zigzag edges it changes monotonically. This behaviour is further analyzed by studying the ground state wave function and explained in terms of its localisation.

  3. Educational reactor-physics experiments with the critical assemble TCA

    Energy Technology Data Exchange (ETDEWEB)

    Tsutsui, Hiroaki; Okubo, Masaaki; Igashira, Masayuki [Tokyo Inst. of Tech. (Japan); Horiki, Oichiro; Suzaki, Takenori

    1997-10-01

    The Tank-Type Critical Assembly (TCA) of Japan Atomic Energy Research Institute is research equipment for light water reactor physics. In the present report, the lectures given to the graduate students of Tokyo Institute of Technology who participated in the educational experiment course held on 26-30 August at TCA are rearranged to provide useful information for those who will implement educational basic experiments with TCA in the future. This report describes the principles, procedures, and data analyses for (1) Critical approach and Exponential experiment, (2) Measurement of neutron flux distribution, (3) Measurement of power distribution, (4) Measurement of fuel rod worth distribution, and (5) Measurement of safety plate worth by the rod drop method. (author)

  4. Study the Postbuckling of Hexagonal Piezoelectric Nanowires with Surface Effect

    Directory of Open Access Journals (Sweden)

    O. Rahmani

    2014-04-01

    Full Text Available Piezoelectric nanobeams having circular, rectangular and hexagonal cross-sections are synthesized and used in various Nano structures; however, piezoelectric nanobeams with hexagonal cross-sections have not been studied in detail. In particular, the physical mechanisms of the surface effect and the role of surface stress, surface elasticity and surface piezoelectricity have not been discussed thoroughly. The present study investigated post-buckling behavior of piezoelectric nanobeams by examining surface effects. The energy method was applied to post-buckling of hexagonal nanobeams and the critical buckling voltage and amplitude are derived analytically from bulk and surface material properties and geometric factors.

  5. Critical ionization velocity interaction in the CRIT I rocket experiment

    Science.gov (United States)

    Brenning, N.; Faelthammar, C.-G.; Marklund, G.; Haerendel, G.; Kelley, M.; Pfaff, R.

    1990-01-01

    In the rocket experiment CRIT I, launched from Wallops Island on May 13, 1986, two identical Barium-shaped charges were fired from distances of 1.3 km and 3.6 km towards the main experiment payload, which was separated from a sub-payload by a couple of km along the magnetic field. The relevance of earlier proposed mechanisms for electron heating in ionospheric critical velocity experiments is investigated in the light of the CRIT I results. It is concluded that both the 'homogeneous' and the 'ionizing front' models can be applied, in different parts of the stream. It is also possible that a third, entirely different, mechanism may contribute to the electron heating. This mechanism involves direct energization of electrons in the magnetic-field-aligned component of the dc electric field.

  6. Patient Experience: A Critical Indicator of Healthcare Performance.

    Science.gov (United States)

    Guler, Pamela H

    2017-01-01

    Patient experience has become a critical differentiator for healthcare organizations, and it will only grow in importance as transparency and consumerism dominate the healthcare landscape. Creating and sustaining a consistently exceptional experience that promotes patient engagement and the best outcomes is far more than just "satisfying" patients, going well beyond amenities that may be provided.Perception of care experience is often shaped by methods we use to address the biopsychosocial needs of patients. Building relationships and communicating well with our patients and families are primary approaches. In a complex healthcare situation, patients may not fully understand or remember the highly clinical nature of treatment. However, they always remember how we made them feel, how we communicated with them as a team, and what interactions they experienced while in our care.Patients who are fully informed and feel connected to their caregivers are often less anxious than those who are disengaged. Informed and engaged patients are enabled to participate in their healthcare. Organizations that focus on developing an accountable culture-one that inspires caregivers to communicate in a way that connects to patients' mind, body, and spirit while leveraging standard, evidence-based patient experience practices-find that patients' perception of care, or "the patient experience," is vastly improved.Adventist Health System has embarked on a journey to patient experience excellence with a commitment to whole-person care and standard patient experience practice across the system. Recognized with several national awards, we continue to strengthen our approach toward bringing all of our campuses and patient settings to sustained high-level performance. We have found that a combination of strong, accountable leadership; a focus on employee culture; engagement of physicians; standardized patient experience practices and education; and meaningful use of patient feedback are top

  7. Sensitivity analysis of critical experiments with evaluated nuclear data libraries

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, D.; Kosaka, S. [Tepco Systems Corporation, Nuclear Engineering Dept., Tokyo (Japan)

    2008-07-01

    Criticality benchmark testing was performed with evaluated nuclear data libraries for thermal, low-enriched uranium fuel rod applications. C/E values for k{sub eff} were calculated with the continuous-energy Monte Carlo code MVP2 and its libraries generated from Endf/B-VI.8, Endf/B-VII.0, JENDL-3.3 and JEFF-3.1. Subsequently, the observed k{sub eff} discrepancies between libraries were decomposed to specify the source of difference in the nuclear data libraries using sensitivity analysis technique. The obtained sensitivity profiles are also utilized to estimate the adequacy of cold critical experiments to the boiling water reactor under hot operating condition. (authors)

  8. CIV experiments on ATLAS-1. [Critical Ionization Velocity

    Science.gov (United States)

    Marshall, J. A.; Burch, J. L.; Choueiri, E. Y.; Kawashima, N.

    1993-01-01

    A test of the Critical Ionization Velocity (CIV) theory was made with neutral xenon releases from the Space Experiments with Particle Accelerators hollow cathode plasma contactor onboard the Shuttle Orbiter Atlantis during the ATLAS-1 mission. The gas velocity perpendicular to the Earth's magnetic field was essentially the orbital velocity (7.5 km/s), and thus it exceeded the CIV for xenon. The releases were observed with onboard instrumentation. A factor of 60 enhancement was seen in the Langmuir probe current. Calculations confirmed that release conditions generally satisfied criteria for CIV and predicted a maximum factor of 20 increase in plasma density. Thus, CIV effects were likely to have occurred during the ATLAS-I experiments.

  9. Experiments for IFR fuel criticality in ZPPR-21

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, D N; Smith, D M; Grasseschi, G L; Goin, R W; Steinhauer, J A; Collins, P J; Carpenter, S G

    1991-01-01

    A series of six criticality benchmark cores was built in ZPPR-21 between June and September 1990 to provide data for validating criticality calculations for systems likely to arise in the IFR fuel processing operations. The assemblies were graphite reflected and had core compositions containing different mixtures of Pu/U/Zr fuel. No previous data existed for cores of this type. Analysis of the data was done, in full detail, with an automated input processor using the VIM Monte Carlo code and ENDF/B-V.2 data. Since the validated method of criticality calculations at ANL is the KENO code and data, a second set of calculations, using a simplified model in RZ geometry was made with both VIM and KENO. An RZ model is specified together with geometrical corrections from the VIM calculations. This enables simple calculations to be made and corrections applied within the statistical uncertainty limits. The full description of the experiments is provided to enable calculations to be made in detail with KENO or any other code. 13 refs., 16 figs., 13 tabs.

  10. Star of Condor - A strontium critical velocity experiment, Peru, 1983

    Science.gov (United States)

    Wescott, E. M.; Stenbaek-Nielsen, H. C.; Hallinan, T.; Foeppl, H.; Valenzuela, A.

    1986-01-01

    'Star of Condor' was a critical velocity experiment using Sr vapor produced in a radial shaped charge, which was carried to 571.11 km altitude on a Taurus-Tomahawk rocket launched from Punto Lobos, Peru, and detonated in the plane of the magnetic field lines so that all ranges of pitch angles from parallel to B to perpendicular to B were covered. Sr has a critical velocity of 3.3 km/s, and from observation, 42.5 percent of the neutral Sr gas had a velocity component perpendicular to B exceeding that value. No Sr ion emissions were detected shortly after the burst with usual TV integration times. However, about 10 min after the detonation a faint field-aligned streak was discovered with long TV integration times. The brightness is estimated as 5 R, which, combined with the streak geometry, implies an ion production of 2.4 x 10 to the 19th ions. This is only 0.0036 percent ionization of the Sr vapor. All the ions could easily have been produced by thermal ionization from the original detonation thermal distribution. The breakup of the Sr gas into small bloblike structures may have allowed the high-energy electrons to escape before an ionization cascade could be produced. For whatever reason, the Alfven mechanism proposed for space plasmas in the absence of laboratory walls did not produce an ionization cascade in the experiment.

  11. Designing Critical Experiments in Support of Full Burnup Credit

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Don [ORNL; Roberts, Jeremy A [ORNL

    2008-01-01

    Burnup credit is the process of accounting for the negative reactivity due to fuel burnup and generation of parasitic absorbers over fuel assembly lifetime. For years, the fresh fuel assumption was used as a simple bound in criticality work for used fuel storage and transportation. More recently, major actinides have been included [1]. However, even this yields a highly conservative estimate in criticality calculations. Because of the numerous economical benefits including all available negative reactivity (i.e., full burnup credit) could provide [2], it is advantageous to work toward full burnup credit. Unfortunately, comparatively little work has been done to include non-major actinides and other fission products (FP) in burnup credit analyses due in part to insufficient experimental data for validation of codes and nuclear data. The Burnup Credit Criticality Experiment (BUCCX) at Sandia National Laboratory was a set of experiments with {sup 103}Rh that have relevance for burnup credit [3]. This work uses TSUNAMI-3D to investigate and adjust a BUCCX model to match isotope-specific, energy-dependent k{sub eff} sensitivity profiles to those of a representative high-capacity cask model (GBC-32) [4] for each FP of interest. The isotopes considered are {sup 149}Sm, {sup 143}Nd, {sup 103}Rh, {sup 133}Cs, {sup 155}Gd, {sup 152}Sm, {sup 99}Tc, {sup 145}Nd, {sup 153}Eu, {sup 147}Sm, {sup 109}Ag, {sup 95}Mo, {sup 150}Sm, {sup 101}Ru, and {sup 151}Eu. The goal is to understand the biases and bias uncertainties inherent in nuclear data, and ultimately, to apply these in support of full burnup credit.

  12. SR90, strontium shaped-charge critical ionization velocity experiment

    Science.gov (United States)

    Wescott, Eugene M.; Stenbaek-Nielsen, Hans; Swift, Daniel W.; Valenzuela, Arnoldo; Rees, David

    1990-01-01

    In May 1986 an experiment was performed to test Alfven's critical ionization velocity (CIV) effect in free space, using the first high explosive shaped charge with a conical liner of strontium metal. The release, made at 540 km altitude at dawn twilight, was aimed at 48 deg to B. The background electron density was 1.5 x 10(exp 4) cu cm. A faint field-aligned Sr(+) ion streak with tip velocity of 2.6 km/s was observed from two optical sites. Using two calibration methods, it was calculated that between 4.5 x 10(exp 20) and 2 x 10(exp 21) ions were visible. An ionization time constant of 1920 s was calculated for Sr from the solar UV spectrum and ionization cross section which combined with a computer simulation of the injection predicts 1.7 x 10(exp 21) solar UV ions in the low-velocity part of the ion streak. Thus all the observed ions are from solar UV ionization of the slow (less than critical) velocity portion of the neutral jet. The observed neutral Sr velocity distribution and computer simulations indicate that 2 x 10(exp 21) solar UV ions would have been created from the fast (greater than critical) part of the jet. They would have been more diffuse, and were not observed. Using this fact it was estimated that any CIV ions created were less than 10(exp 21). It was concluded that future Sr CIV free space experiments should be conducted below the UV shadow height and in much larger background plasma density.

  13. ESADA Plutonium Program Critical Experiments: Power Distribution Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Akkurt, H.

    2001-06-12

    In 1967, a series of critical experiments were conducted at the Westinghouse Reactor Evaluation Center (WREC) using mixed-oxide (MOX) PuO{sub 2}-UO{sub 2} and/or UO{sub 2} fuels in various lattices and configurations. These experiments were performed under the joint sponsorship of Empire State Atomic Development Associates (ESADA) plutonium program and Westinghouse. The purpose of these experiments was to develop experimental data useful in validating analytical methods used in the design of plutonium-bearing replacement fuel for water reactors. Three different fuel types were used during the experimental program: two MOX fuels and a low-enriched UO{sub 2} fuel. The MOX fuels were distinguished by their {sup 240}Pu content: 8 wt % {sup 240}Pu and 24 wt % {sup 240}Pu. Both MOX fuels contained 2.0 wt % PuO{sub 2} in natural UO{sub 2}. The UO{sub 2} fuel with 2.72 wt % enrichment was used for comparison with the plutonium data and for use in multiregion experiments.

  14. A critical analysis of undergraduate students' cultural immersion experiences.

    Science.gov (United States)

    Harrowing, J N; Gregory, D M; O'Sullivan, P S; Lee, B; Doolittle, L

    2012-12-01

    This paper is concerned with the impact of an international health promotion experience on the understanding of culture among university students. Such immersion experiences are often cited as a strategy to prepare nurses for culturally appropriate practice. We describe students' epistemic movements over time with respect to cultural perspectives prior to, during and after a field study in Malawi. Data were collected at three time points from students in undergraduate nursing (n = 14) and non-nursing (n = 8) programs at a Canadian university. Two essays narrating participants' understanding of culture were submitted by consenting class members. A subgroup of nine participants (four nursing students, five from other disciplines) completed a third narrative following a subsequent field study course in Malawi. Using narrative analysis, themes and structures in the participants' writing were identified and located within a constructivist or essentialist paradigm of cultural understanding. Overwhelmingly, students' narratives were initially portrayed and informed by an essentialist understanding of culture. Later narratives demonstrated varying degrees of epistemic movement towards more constructivist viewpoints. Narratives that initially exhibited constructivist characteristics tended to display strengthened convictions in that paradigm. We challenge the claim that an international immersion experience immediately transforms participants into cultural experts; our evidence suggests that students experienced existential growth, but their understanding of culture did not change as a result of their brief stay in a different cultural context. Cultural immersion is a phenomenon that requires more critical analysis and systematic investigation to determine how such experiences contribute to learning about culture among nursing students. © 2012 The Authors. International Nursing Review © 2012 International Council of Nurses.

  15. ARCHITECTURAL CRITICISM IN PRACTICE: FROM AFFECTIVE TO EFFECTIVE EXPERIENCE

    Directory of Open Access Journals (Sweden)

    Aaron T. Davis

    2012-07-01

    Full Text Available “Although many artists and architects privilege phenomenological experience, they often offer the near-reverse: ‘experience’ handed back to us as ‘atmosphere’ or ‘affect’ - that is as environments that confuse the actual with the virtual, or feelings that  are hardly our own yet interpolate us nonetheless. In the guise of our activation, some work even tends to subdue us, for the more it opts for special effects, the less it engages us as active viewers.“ (Foster, 2011 The article that follows chronicles the evolution of the respective sub-fields of endeavor from the unique perspectives of the authors and their cumulative involvements and experiences. Its main purpose is to  begin to bridge the gap between the affective and  effective goals of architectural criticism (Attoe, 1989. In other words, the attempt will be made to connect  the perceived vs. measured quality of the designed and built environment, including visual-aesthetic quality. The result is an entirely new form of criticism that is instructive as both a tool to professionals and an explication of the built environment to the layperson beyond aesthetic platitudes. Because of its cumulative nature, the2-part literature review is not intended to be exhaustive since that can be gleaned from a sample of authoritative publications on the evolution of: 1. Architectural Criticism: On Architecture: Collected Reflections on a Century of Change by Huxtable (Walker, 2010, Why Architecture Matters by Goldberger (Yale University Press, 2003, and After the End of Art: Contemporary Art and the Pale of History by Danto (Princeton University Press, 1997; 2. Post-Occupancy Evaluation/Building Performance Evaluation: Enhancing Building Performance by Mallory-Hill, Preiser and Watson (Wiley, 2012; Learning From Our Buildings: A State-ofthe-Practice Summary of Post-Occupancy Evaluation by Federal Facilities Council (National Academy Press, 2001; and, Building Evaluation Techniques by

  16. Experiences of Vulnerable Residential Customer Subpopulations with Critical Peak Pricing

    Energy Technology Data Exchange (ETDEWEB)

    Cappers, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Spurlock, C. Anna [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Todd, Annika [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Jin, Ling [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-04-13

    DOE decided to co-fund ten utilities to undertake eleven experimentally-designed Consumer Behavior Studies (CBS) that proposed to examine a wide range of the topics of interest to the electric utility industry. Each chosen utility was to design, implement and evaluate their own study in order to address questions of interest both to itself and to its applicable regulatory authority, whose approval was generally necessary for the study to proceed. The DOE Office of Energy Delivery and Electricity Reliability (OE), however, did set guidelines, both in the FOA and subsequently during the contracting period, for what would constitute an acceptable study under the Grant. To assist in ensuring these guidelines were adhered to, OE requested that LBNL act as project manager for these Consumer Behavior Studies to achieve consistency of experimental design and adherence to data collection and reporting protocols across the ten utilities. As part of its role, LBNL formed technical advisory groups (TAG) to separately assist each of the utilities by providing technical assistance in all aspects of the design, implementation and evaluation of their studies. LBNL was also given a unique opportunity to perform a comprehensive, cross-study analysis that uses the customer-level interval meter and demographic data made available by these utilities due to SGIG-imposed reporting requirements, in order to analyze critical policy issues associated with AMI-enabled rates and control/information technology. LBNL will publish the results of these analyses in a series of research reports, of which this is one, that attempt to address critical policy issues relating to a variety of topics including customer acceptance, retention and load response to time-based rates and various forms of enabling control and information technologies. This report extends the existing empirical literature on the experiences of low-income customers exposed to critical peak pricing, and provides the first glimpses

  17. Quantitative TEM analysis of a hexagonal mesoporous silicate structure.

    Science.gov (United States)

    Hudson, S; Tanner, D A; Redington, W; Magner, E; Hodnett, K; Nakahara, S

    2006-08-07

    TEM analysis of mesoporous materials is generally undertaken to give qualitative results. Accurate quantitative analysis is demonstrated in this study. A systematic image analysis of a powder form of a hexagonal mesoporous material known as KIT-6 is conducted using a transmission electron microscope (TEM). Three types of image contrast typically appear in this material (a hexagonal honeycomb structure, wide and narrow parallel lines). The honeycomb face is used to characterise this material in terms of a conventional 2-D hexagonal structure and the d-spacings for the (100) and (110) planes are experimentally measured in varying focus conditions. A tilting experiment is conducted to determine how the angle of tilt affects the line spacing and their visibility. Tilting has very little effect on the line spacing, whereas it affects the visibility of both the wide and narrow lines by limiting an angle range of visibility. The hexagonal lattice structure parameter determined by TEM method is found to be approximately 7% lower than that calculated by low-angle X-ray diffraction. Thus we conclude that TEM data can be used to determine the geometry and dimensions of hexagonal mesoporous silica materials, with a small error in the hexagonal lattice parameter.

  18. Enabling software defined networking experiments in networked critical infrastructures

    Directory of Open Access Journals (Sweden)

    Béla Genge

    2014-05-01

    Full Text Available Nowadays, the fact that Networked Critical Infrastructures (NCI, e.g., power plants, water plants, oil and gas distribution infrastructures, and electricity grids, are targeted by significant cyber threats is well known. Nevertheless, recent research has shown that specific characteristics of NCI can be exploited in the enabling of more efficient mitigation techniques, while novel techniques from the field of IP networks can bring significant advantages. In this paper we explore the interconnection of NCI communication infrastructures with Software Defined Networking (SDN-enabled network topologies. SDN provides the means to create virtual networking services and to implement global networking decisions. It relies on OpenFlow to enable communication with remote devices and has been recently categorized as the “Next Big Technology”, which will revolutionize the way decisions are implemented in switches and routers. Therefore, the paper documents the first steps towards enabling an SDN-NCI and presents the impact of a Denial of Service experiment over traffic resulting from an XBee sensor network which is routed across an emulated SDN network.

  19. The experiences of qualified critical care nurses regarding students working in critical care units

    OpenAIRE

    2015-01-01

    M.Cur. (Nursing Science (Critical Care)) Qualified critical care nurses are under internal and external stresses in the workplace, relating to role conflict, role ambiguity, increased workloads, the need for rapid decision making and the speedy delivery of care. However, having inexperienced students in critical care units put responsibility and additional stress on the qualified critical care nurses within the units. This may result in some of these qualified nurses not being willing to h...

  20. Direct numerical simulation of turbulence and heat transfer in a hexagonal shaped duct

    Science.gov (United States)

    Marin, Oana; Obabko, Aleks; Schlatter, Philipp

    2014-11-01

    Flows in hexagonal shapes frequently occur in nuclear reactor applications, and are also present in honeycomb-shaped settling chambers for e.g. wind tunnels. Whereas wall-bounded turbulence has been studied comprehensively in two-dimensional channels, and to a lesser degree also in square and rectangular ducts and triangles, only very limited data for hexagonal ducts is available, including resistance correlations and mean profiles. Here, we use resolved spectral-element simulations to compute velocity and temperature in fully-developed (periodic) hexagonal duct flow. The Reynolds number, based on the fixed flow rate and the hydraulic diameter, ranges between 2000 and 20000. The temperature assumes constant wall flux or constant wall temperature. First DNS results are focused on the mean characteristics such a head loss, Nusselt number, and critical Reynolds number for sustained turbulence. Profiles, both for mean and fluctuating quantities, are extracted and discussed in the context of square ducts and pipes. Comparisons to existing experiments, RANS and empirical correlations are supplied as well. The results show a complicated and fine-scale pattern of the in-plane secondary flow, which clearly affects the momentum and temperature distribution throughout the cross section.

  1. Examining the Immigrant Experience: Helping Teachers Develop as Critical Educators

    Science.gov (United States)

    DeMulder, Elizabeth K.; Stribling, Stacia M.; Day, Monimalika

    2014-01-01

    The purpose of this qualitative case study was to examine ways that a multicultural perspective using critical literacy practices engaged practicing teachers to rethink and re-vision oppressive hegemonic structures and attitudes regarding immigrant students and their families and helped them to develop as critical educators. In the context of a…

  2. Critical Pedagogy: EFL Teachers' Views, Experience and Academic Degrees

    Science.gov (United States)

    Mahmoodarabi, Mahsa; Khodabakhsh, Mohammad Reza

    2015-01-01

    Although critical pedagogy has brought about positive changes in the field of education by shifting from traditional pedagogy to emancipatory pedagogy, not much attention has been paid to the factors affecting teachers' beliefs of critical pedagogy and only few studies have been conducted to design reliable and valid instruments to study EFL…

  3. Whispering gallery modes in deformed hexagonal resonators

    Energy Technology Data Exchange (ETDEWEB)

    Grundmann, Marius; Dietrich, Christof P. [Universitaet Leipzig, Fakultaet fuer Physik und Geowissenschaften, Institut fuer Experimentelle Physik II, Linnestr. 5, 04103 Leipzig (Germany)

    2012-05-15

    Optical resonances in polygonal resonators are due to whispering gallery modes (WGM). We investigate WGM in regular and deformed hexagonal ZnO microwire resonators. Four types of geometries are investigated: regular hexagonal and dodecagonal cross sections, hexagonal cross section elongated for one pair of facets and hexagonal cross section deformed by bending (uniaxial stress). Experimental data on mode energies and angular dispersion are correlated with model calculations and Poincare surfaces of section. Hexagonal ({phi} = 60 ), square ({phi} = 45 ), triangular ({phi} = 30 ), and Fabry-Perot modes ({phi} = 0 ) are observed in the various investigated geometries, {phi} being the angle of incidence at the facets with respect to the normal direction. Hexagonal WGMs (green, 6-WGM), triangular (red, 3-WGM), and double-triangular (blue, D3-WGM) rays in regular hexagons, elongated hexagons and hexagons deformed by bending. Triangular WGMs are stable modes in all three resonators. Hexagonal modes are not stable in the bent hexagon. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Comparison of electron bands of hexagonal and cubic diamond

    Science.gov (United States)

    Salehpour, M. R.; Satpathy, S.

    1990-02-01

    Using the local-density-theory and the linear-muffin-tin-orbitals method, we calculate the electron band structures of hexagonal (lonsdaleite) and cubic diamond. Even though the arrangement of atoms is very similar between the two crystal structures, we find significant differences in the electron bands, especially in the conduction bands. In particular, including estimated corrections on top of the local-density results, we find the lowest theoretical gap of hexagonal diamond to be 4.5 eV, i.e., a remarkable 1.1-eV drop as compared to that of cubic diamond. The lowest gap in the hexagonal structure is still indirect as in the cubic structure, but the gap is now from Γ to K. The reduction of the band gap should be observable in optical-absorption or reflectivity experiments.

  5. Band gaps in incommensurable graphene on hexagonal boron nitride

    NARCIS (Netherlands)

    Bokdam, Menno; Amlaki, T.; Brocks, G.; Kelly, Paul J.

    2014-01-01

    Devising ways of opening a band gap in graphene to make charge-carrier masses finite is essential for many applications. Recent experiments with graphene on hexagonal boron nitride (h -BN) offer tantalizing hints that the weak interaction with the substrate is sufficient to open a gap, in

  6. Effects of Diversity Experiences on Critical Thinking Skills: Who Benefits?

    Science.gov (United States)

    Loes, Chad; Pascarella, Ernest; Umbach, Paul

    2012-01-01

    This study analyzed data from the Wabash National Study of Liberal Arts Education to estimate the unique effects of exposure to classroom diversity and involvement in interactional diversity on growth in critical thinking skills during the first year of college. Net of important confounding influences, neither classroom nor interactional diversity…

  7. Utilization of the BARC critical facility for ADS related experiments

    Indian Academy of Sciences (India)

    The paper discusses the basic design of the critical facility, whose main purpose is the physics validation of AHWR. Apart from moderator level control, the facility will have shutdown systems based on shutoff rods and multiple ranges of neutron detection systems. In addition, it will have a flux mapping system based on 25 ...

  8. Critical and Creative Thinking Nexus: Learning Experiences of Doctoral Students

    Science.gov (United States)

    Brodin, Eva M.

    2016-01-01

    Critical and creative thinking constitute important learning outcomes at doctoral level across the world. While the literature on doctoral education illuminates this matter through the lens of experienced senior researchers, the doctoral students' own perspective is missing. Based upon interviews with 14 doctoral students from four disciplines at…

  9. Learning to Think Critically: A Visual Art Experiment

    Science.gov (United States)

    Bowen, Daniel H.; Greene, Jay P.; Kisida, Brian

    2014-01-01

    This article examines whether exposure to the arts has an effect on the ability of students to engage in critical thinking. We conduct a randomized controlled trial involving 3,811 students who were assigned by lottery to participate in a School Visit Program at the newly opened Crystal Bridges Museum of American Art. Students who participated in…

  10. Critical care clinical experience for novice students: reinforcing basic nursing skills.

    Science.gov (United States)

    Ballard, Pamela; Trowbridge, Connie

    2004-01-01

    To better match students' learning priorities with their practicum experiences and to facilitate skills learning, undergraduate faculty devised the innovative strategy of incorporating a critical care rotation into the first semester of students' clinical experience. The authors describe the basics of this previously untested critical care clinical experience and the essential planning steps prior to implementation, including faculty approval, hospital administrative and nurse manager approval, preceptor identification and education, means of evaluating and grading the students, and evaluation of the overall experience.

  11. Experiences and perceptions of music therapy in critical illness.

    Science.gov (United States)

    Stubbs, Tina

    To gain insight into patients' and nurses' perception of the benefits of music therapy during critical illness. The patients received music therapy on two prescribed occasions for 30 minutes each day. Unstructured interviews were conducted with five patients and four nurses and analysed according to Burnard's framework (1991). Patients can and do recall listening to music, even when they have been sedated and ventilated. They related to the music that they were listening to and some experienced imagery concerning the music. The nurses found it useful as an aid to wean patients off the ventilator, helping to keep them calm and focused. The study concluded that music is useful not only for relaxing patients but also in some cases 'relocating' them from the critical care area to the place where they would normally be listening to the music.

  12. Critical Incidents in the Experiences of Japanese Returnees

    Science.gov (United States)

    Ford, Keith

    2009-01-01

    In this study, I explore the experiences of five Japanese returnees ("kikokushijo"). The participants recorded taped monologues or wrote narratives reflecting on their time spent living abroad and of returning to Japan. These retrospective life stories revealed four prominent themes of conflict: group orientation; bullying and…

  13. Criticality: the experience of developing an interactive educational tool based on board games.

    Science.gov (United States)

    Gibson, Vanessa; Douglas, Margaret

    2013-12-01

    Critical care services have seen many changes over recent years prompted by the seminal paper by the Department of Health (2000) Comprehensive critical care: A review of adult critical care services. This led to the expansion of critical care services with the resultant recruitment of large numbers of nurses new to critical care. Northumbria and other Universities within the UK were commissioned to provide formal education to critical care nurses and developed Foundations in Acute and Critical Care Module to provide nurses new to critical care, or from other acute clinical settings, with the knowledge and skills to manage this complex group of patients. The aim of this paper is to share the authors' experience of developing "Criticality" a board game designed to formatively assess learning amongst critical care nurses following a formal taught module in a Higher Education Institution (HEI) and prior to the summative assessment. Author experience suggests that Criticality is a useful revision tool and also fun and interactive which helped the students to identify strengths and weaknesses in their knowledge base and thus direct their revision prior to summative assessment. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Monte Carlo calculations of the REBUS critical experiment for validation of burn-up credit

    Energy Technology Data Exchange (ETDEWEB)

    Hennebach, M.; Kuhl, H. [WTI GmbH, Julich (Germany)

    2008-07-01

    The REBUS experiment is a valuable benchmark for the validation of Monte Carlo criticality codes within the context of burn-up credit. It investigates the difference in reactivity worth of unirradiated fuel rods and of fuel rods irradiated in a PWR. This paper presents results of criticality calculations for this experiment with the Monte Carlo codes MCNP and SCALE/KENO. The results show that even the comparatively small reactivity loss of about 2000 pcm measured in this experiment can be calculated within an accuracy of 6 per cent. A detailed comparison of measured and calculated core characteristics (fission rate and flux distributions) shows good agreement, which indicates an adequately detailed model geometry for criticality calculations. The slight underestimation (500 pcm) of absolute k(eff) values is not out of the typical range for criticality benchmark experiments.

  15. Analysis of fresh fuel critical experiments appropriate for burnup credit validation

    Energy Technology Data Exchange (ETDEWEB)

    DeHart, M.D.; Bowman, S.M.

    1995-10-01

    The ANS/ANS-8.1 standard requires that calculational methods used in determining criticality safety limits for applications outside reactors be validated by comparison with appropriate critical experiments. This report provides a detailed description of 34 fresh fuel critical experiments and their analyses using the SCALE-4.2 code system and the 27-group ENDF/B-IV cross-section library. The 34 critical experiments were selected based on geometry, material, and neutron interaction characteristics that are applicable to a transportation cask loaded with pressurized-water-reactor spent fuel. These 34 experiments are a representative subset of a much larger data base of low-enriched uranium and mixed-oxide critical experiments. A statistical approach is described and used to obtain an estimate of the bias and uncertainty in the calculational methods and to predict a confidence limit for a calculated neutron multiplication factor. The SCALE-4.2 results for a superset of approximately 100 criticals are included in uncertainty analyses, but descriptions of the individual criticals are not included.

  16. Simulated and Virtual Science Laboratory Experiments: Improving Critical Thinking and Higher-Order Learning Skills

    Science.gov (United States)

    Simon, Nicole A.

    2013-01-01

    Virtual laboratory experiments using interactive computer simulations are not being employed as viable alternatives to laboratory science curriculum at extensive enough rates within higher education. Rote traditional lab experiments are currently the norm and are not addressing inquiry, Critical Thinking, and cognition throughout the laboratory…

  17. Bronze-mean hexagonal quasicrystal

    Science.gov (United States)

    Dotera, Tomonari; Bekku, Shinichi; Ziherl, Primož

    2017-10-01

    The most striking feature of conventional quasicrystals is their non-traditional symmetry characterized by icosahedral, dodecagonal, decagonal or octagonal axes. The symmetry and the aperiodicity of these materials stem from an irrational ratio of two or more length scales controlling their structure, the best-known examples being the Penrose and the Ammann-Beenker tiling as two-dimensional models related to the golden and the silver mean, respectively. Surprisingly, no other metallic-mean tilings have been discovered so far. Here we propose a self-similar bronze-mean hexagonal pattern, which may be viewed as a projection of a higher-dimensional periodic lattice with a Koch-like snowflake projection window. We use numerical simulations to demonstrate that a disordered variant of this quasicrystal can be materialized in soft polymeric colloidal particles with a core-shell architecture. Moreover, by varying the geometry of the pattern we generate a continuous sequence of structures, which provide an alternative interpretation of quasicrystalline approximants observed in several metal-silicon alloys.

  18. Proceedings of the workshop on integral experiment covariance data for critical safety validation

    Energy Technology Data Exchange (ETDEWEB)

    Stuke, Maik (ed.)

    2016-04-15

    For some time, attempts to quantify the statistical dependencies of critical experiments and to account for them properly in validation procedures were discussed in the literature by various groups. Besides the development of suitable methods especially the quality and modeling issues of the freely available experimental data are in the focus of current discussions, carried out for example in the Expert Group on Uncertainty Analysis for Criticality Safety Assessment (UACSA) of the OECD-NEA Nuclear Science Committee. The same committee compiles and publishes also the freely available experimental data in the International Handbook of Evaluated Criticality Safety Benchmark Experiments. Most of these experiments were performed as series and might share parts of experimental setups leading to correlated results. The quality of the determination of these correlations and the underlying covariance data depend strongly on the quality of the documentation of experiments.

  19. FOEHN: The critical experiment for the Franco-German High Flux Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Scharmer, K.; Eckert, H. G. [Kernforschungszentrum Karlsruhe GmbH (Germany)

    1991-01-01

    A critical experiment for the Franco-German High Flux Reactor was carried out in the French reactor EOLE (CEN Cadarache). The purpose of the experiment was to check the calculation methods in a realistic geometry and to measure effects that can only be calculated imprecisely (e.g. beam hole effects). The structure of the experiment and the measurement and calculation methods are described. A detailed comparison between theoretical and experimental results was performed. 30 refs., 105 figs.

  20. Discovery of Superconductivity in Hard Hexagonal ε-NbN.

    Science.gov (United States)

    Zou, Yongtao; Qi, Xintong; Zhang, Cheng; Ma, Shuailing; Zhang, Wei; Li, Ying; Chen, Ting; Wang, Xuebing; Chen, Zhiqiang; Welch, David; Zhu, Pinwen; Liu, Bingbing; Li, Qiang; Cui, Tian; Li, Baosheng

    2016-02-29

    Since the discovery of superconductivity in boron-doped diamond with a critical temperature (TC) near 4 K, great interest has been attracted in hard superconductors such as transition-metal nitrides and carbides. Here we report the new discovery of superconductivity in polycrystalline hexagonal ε-NbN synthesized at high pressure and high temperature. Direct magnetization and electrical resistivity measurements demonstrate that the superconductivity in bulk polycrystalline hexagonal ε-NbN is below ∼11.6 K, which is significantly higher than that for boron-doped diamond. The nature of superconductivity in hexagonal ε-NbN and the physical mechanism for the relatively lower TC have been addressed by the weaker bonding in the Nb-N network, the co-planarity of Nb-N layer as well as its relatively weaker electron-phonon coupling, as compared with the cubic δ-NbN counterpart. Moreover, the newly discovered ε-NbN superconductor remains stable at pressures up to ∼20 GPa and is significantly harder than cubic δ-NbN; it is as hard as sapphire, ultra-incompressible and has a high shear rigidity of 201 GPa to rival hard/superhard material γ-B (∼227 GPa). This exploration opens a new class of highly desirable materials combining the outstanding mechanical/elastic properties with superconductivity, which may be particularly attractive for its technological and engineering applications in extreme environments.

  1. Health consumers' experiences in Australian critical care units: postgraduate nurse education implications.

    Science.gov (United States)

    Gill, Fenella J; Leslie, Gavin D; Grech, Carol; Latour, Jos M

    2013-01-01

    To explore critical care patients and families experiences and seek their input into nurses' postgraduate educational preparation and practice. There is an inconsistency in the expected standard of practice to 'qualify' Australian critical care nurses. There has also been a lack of health consumer input in the development of postgraduate course curriculum and content. Following institutional ethics committee approval, purposive sampling was used to select participants for focus groups and individual interviews who had experienced intensive care or coronary care. Seventeen participants provided data which created two main thematic categories; the role of the critical care nurse and; minimum practice standards for postgraduate critical care course graduates. Both physical patient care and socio-emotional support of patients and family were identified as important for the critical care nurse role. The level of socio-emotional support provided by nurses was reported to be inconsistent. Components of socio-emotional support included communication, people skills, facilitating family presence and advocacy. These components were reflected in participants' concepts of minimum practice standards for postgraduate critical care course graduates; talking and listening skills, relating to and dealing with stressed people, individualizing care and patient and family advocacy. Health consumers' views emphasize that socio-emotional skills and behaviours need to be explicitly described in postgraduate critical care nursing course curricula and instruments developed to consistently assess these core competencies. © 2013 The Authors. Nursing in Critical Care © 2013 British Association of Critical Care Nurses.

  2. Simulated and Virtual Science Laboratory Experiments: Improving Critical Thinking and Higher-Order Learning Skills

    Science.gov (United States)

    Simon, Nicole A.

    Virtual laboratory experiments using interactive computer simulations are not being employed as viable alternatives to laboratory science curriculum at extensive enough rates within higher education. Rote traditional lab experiments are currently the norm and are not addressing inquiry, Critical Thinking, and cognition throughout the laboratory experience, linking with educational technologies (Pyatt & Sims, 2007; 2011; Trundle & Bell, 2010). A causal-comparative quantitative study was conducted with 150 learners enrolled at a two-year community college, to determine the effects of simulation laboratory experiments on Higher-Order Learning, Critical Thinking Skills, and Cognitive Load. The treatment population used simulated experiments, while the non-treatment sections performed traditional expository experiments. A comparison was made using the Revised Two-Factor Study Process survey, Motivated Strategies for Learning Questionnaire, and the Scientific Attitude Inventory survey, using a Repeated Measures ANOVA test for treatment or non-treatment. A main effect of simulated laboratory experiments was found for both Higher-Order Learning, [F (1, 148) = 30.32,p = 0.00, eta2 = 0.12] and Critical Thinking Skills, [F (1, 148) = 14.64,p = 0.00, eta 2 = 0.17] such that simulations showed greater increases than traditional experiments. Post-lab treatment group self-reports indicated increased marginal means (+4.86) in Higher-Order Learning and Critical Thinking Skills, compared to the non-treatment group (+4.71). Simulations also improved the scientific skills and mastery of basic scientific subject matter. It is recommended that additional research recognize that learners' Critical Thinking Skills change due to different instructional methodologies that occur throughout a semester.

  3. Experiment of Critical Swimming Speed of Fingerling Masu Salmon (Oncorhynchus masou masou) Using River Water

    Science.gov (United States)

    Izumi, Mattashi; Kato, Koh

    The authors conducted a field swimming experiment using cultured masu salmon (Oncorhynchus masou masou) fingerlings in order to study their critical swimming speed during their release into the river in the Iwaki River diversion weir. The experimental equipment was a small, rectangular cross-section channel, which was installed in a local riverbed at the fishway. The experiment was conducted using an average cross-sectional water flow velocity of 17 to 92 cm·s-1, and using masu salmon fingerlings from 4.8 to 7.1 cm in the length. River water temperature was between 13.7 and 20.6 °C. The critical swimming speed measured over 60 minutes was between 16 and 41 cm·s-1 and a positive correlation was found between the critical swimming speed and body length. The critical swimming speed measured by body length (BL) was 3.5 to 6.9 times (that is, the distance travelled per second based on body length), and the mean critical swimming speed was 5.5 (with a standard deviation of 1.1). Results showed that water temperature differences in the experiment had no significant effect on the critical swimming speed measured over 60 minutes.

  4. A short review of critical experiments performed at the Kurchatov Institute

    Energy Technology Data Exchange (ETDEWEB)

    Gagarinski, A.Yu.; Glushkov, Y.S.; Ponomarev-Stepnoi, N.N. [Kurchatov Institute (Russian Federation)

    1997-06-01

    Since the 1950s, the Institute of Atomic Energy (now the Russian Research Center Kurchatov Institute) has investigated nuclear reactors intended for various purposes. A summary of the present state of these assemblies is given in an attachment to the paper. A second attachment provides a brief description of critical experiments for small nuclear power systems intended for decentralized power generation. The critical assemblies for these experiments were moderated by water and zirconium hydride, and fuel elements ranged in enrichment from 5% to 95% uranium 235. 7 refs.

  5. Competing atomic processes in Ba and Sr injection critical velocity experiments

    Science.gov (United States)

    Newell, P. T.; Torbert, R. B.

    1985-01-01

    The critical ionization velocity effect requires a superthermal electron population to ionize through collisional impact. Such superthermal electrons can however lose energy to competing atomic processes, as well as to ionization, thus limiting the efficiency of the effect. Considering Ba and Sr magnetospheric injection experiments designed to test the CIV theory, it is found that in both cases roughly 60 percent of the superthermal electron energy is lost on exciting line radiation. Moreover, energy loss to background neutral oxygen places a strict limit on the injected cloud densities for which critical velocity effects are possible; a finding which explains the consistently negative results in radial injection experiments.

  6. Validation of neutron data for Pb and Bi using critical experiments

    Energy Technology Data Exchange (ETDEWEB)

    Tsiboulia, Anatoli; Khomyakov, Yuri; Koscheev, Vladimir; Kochetkov, Anatoli; Matveenko, Igor; Mikhailova, Irina; Semenov, Mikhail [State Scientific Center of the Russian Federation, Inst. for Physics and Power Engineering (IPPE), Obninsk (Russian Federation); Lopatkin, A.V.; Smirnov, V.S. [R and D and Designing Institute for Power Technology (NIKIET), Moscow (Russian Federation)

    2002-08-01

    A series of critical assemblies at the BFS (Obninsk fast assembly) facility was created for the validation of the neutron data for Pb and Bi in fast reactor spectrum. It is planned to continue the experiments in the nearest future. The analysis of the experiments has shown that the use of neutron data from files of various national libraries results in significant differences in the calculated values of basic neutronic characteristics. (author)

  7. GROWTH OF THE INTERNATIONAL CRITICALITY SAFETY AND REACTOR PHYSICS EXPERIMENT EVALUATION PROJECTS

    Energy Technology Data Exchange (ETDEWEB)

    J. Blair Briggs; John D. Bess; Jim Gulliford

    2011-09-01

    Since the International Conference on Nuclear Criticality Safety (ICNC) 2007, the International Criticality Safety Benchmark Evaluation Project (ICSBEP) and the International Reactor Physics Experiment Evaluation Project (IRPhEP) have continued to expand their efforts and broaden their scope. Eighteen countries participated on the ICSBEP in 2007. Now, there are 20, with recent contributions from Sweden and Argentina. The IRPhEP has also expanded from eight contributing countries in 2007 to 16 in 2011. Since ICNC 2007, the contents of the 'International Handbook of Evaluated Criticality Safety Benchmark Experiments1' have increased from 442 evaluations (38000 pages), containing benchmark specifications for 3955 critical or subcritical configurations to 516 evaluations (nearly 55000 pages), containing benchmark specifications for 4405 critical or subcritical configurations in the 2010 Edition of the ICSBEP Handbook. The contents of the Handbook have also increased from 21 to 24 criticality-alarm-placement/shielding configurations with multiple dose points for each, and from 20 to 200 configurations categorized as fundamental physics measurements relevant to criticality safety applications. Approximately 25 new evaluations and 150 additional configurations are expected to be added to the 2011 edition of the Handbook. Since ICNC 2007, the contents of the 'International Handbook of Evaluated Reactor Physics Benchmark Experiments2' have increased from 16 different experimental series that were performed at 12 different reactor facilities to 53 experimental series that were performed at 30 different reactor facilities in the 2011 edition of the Handbook. Considerable effort has also been made to improve the functionality of the searchable database, DICE (Database for the International Criticality Benchmark Evaluation Project) and verify the accuracy of the data contained therein. DICE will be discussed in separate papers at ICNC 2011. The status of the

  8. Interrogating Students' Perceptions of Their Online Learning Experiences with Brookfield's Critical Incident Questionnaire

    Science.gov (United States)

    Phelan, Liam

    2012-01-01

    This article discusses whether the very act of accessing online students' experiences of teaching may itself foster students' sense of belonging to a learning community. The article reports and reflects on the application of Brookfield's critical incident questionnaire (CIQ) in postgraduate courses delivered online in 2008-2010 through the…

  9. Critical Race Theory, Disability Microaggressions and Latina/o Student Experiences in Special Education

    Science.gov (United States)

    Dávila, Brianne

    2015-01-01

    This research draws upon critical race theory (CRT) to explore the experiences of Latina/o students in special education. It seeks to extend the theoretical construct of racial microaggressions and illustrate the additional layer of disability as I present data that are particular to the context of special education and the assigned label of…

  10. Development of Critical Thinking through Aesthetic Experience: The Case of Students of an Educational Department

    Science.gov (United States)

    Raikou, Natassa

    2016-01-01

    This article addresses an application performed in tertiary education--a department of pedagogical and educational sciences--of a contemporary method, Transformative Learning through Aesthetic Experience. The method is based on the use of art and aims to reinforce and promote the development of critical thinking within educational settings.…

  11. A Critical Review of Seligman's Laboratory Experiments on Learned Helplessness and Depression in Humans

    Science.gov (United States)

    Costello, Charles G.

    1978-01-01

    Six laboratory experiments on learned helplessness and depression in humans reported by Seligman and his colleagues were critically reviewed. A number of methodological and conceptual problems were discussed. Suggests that it is important for psychologists to scrutinize psychological theories in order to assess their conceptual clarity and…

  12. The Impact of Simulation-Based Learning Experience on Critical Thinking Acquisition

    Science.gov (United States)

    Rome, Candice

    2012-01-01

    The purpose of this comparative experimental project was to compare the impact of simulation-based learning experiences to traditional clinical rotations on critical thinking acquisition of associate nursing students within a maternal-child course. Innovative pedagogies have been integrated in nursing programs to augment inadequate clinical…

  13. How Do Virtual World Experiences Bring about Learning? A Critical Review of Theories

    Science.gov (United States)

    Loke, Swee-Kin

    2015-01-01

    While students do learn real-world knowledge and skills in virtual worlds, educators have yet to adequately theorise how students' virtual world experiences bring about this learning. This paper critically reviewed theories currently used to underpin empirical work in virtual worlds for education. In particular, it evaluated how applicable these…

  14. Nuclear criticality safety experiments, calculations, and analyses: 1958 to 1982. Volume 1. Lookup tables

    Energy Technology Data Exchange (ETDEWEB)

    Koponen, B.L.; Hampel, V.E.

    1982-10-21

    This compilation contains 688 complete summaries of papers on nuclear criticality safety as presented at meetings of the American Nuclear Society (ANS). The selected papers contain criticality parameters for fissile materials derived from experiments and calculations, as well as criticality safety analyses for fissile material processing, transport, and storage. The compilation was developed as a component of the Nuclear Criticality Information System (NCIS) now under development at the Lawrence Livermore National Laboratory. The compilation is presented in two volumes: Volume 1 contains a directory to the ANS Transaction volume and page number where each summary was originally published, the author concordance, and the subject concordance derived from the keyphrases in titles. Volume 2 contains - in chronological order - the full-text summaries, reproduced here by permission of the American Nuclear Society from their Transactions, volumes 1-41.

  15. Critical features revealed in acoustic and electromagnetic emissions during fracture experiments on LiF

    Science.gov (United States)

    Potirakis, S. M.; Mastrogiannis, D.

    2017-11-01

    Acoustic emissions (AE) and electromagnetic emissions (EME) are produced during the fracture of solids permitting the monitoring of fracture processes and the study of fracture dynamics. In the literature there have been reported many attempts to connect the AE originating from the fracture of materials with the notion of criticality. Although there is an extended study of the AE during the fracture of a material and its relevance with the notion of criticality, this is not the case for the EME. In order to further investigate the possible critical behavior of fracture processes through AE and EME, we proceed here to the analysis of AE and EME time series using the recently proposed method of natural time (NT). We focus on the analysis of simultaneously acquired AE and EME time series, recorded during fracture experiments on LiF (non-irradiated and irradiated) specimens. The natural time analysis indicates that criticality is reached by both fracture-induced emissions, reflecting the critical behavior of the associated fracture processes. Moreover, it is found that both non-irradiated and irradiated LiF specimens exhibit similar behavior: the AE reach criticality earlier than EME, while EME reach criticality just before the global fracture.

  16. Evaluation of Fission Product Critical Experiments and Associated Biases for Burnup Credit Validation

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Don [ORNL; Rearden, Bradley T [ORNL; Reed, Davis Allan [ORNL

    2010-01-01

    One of the challenges associated with implementation of burnup credit is the validation of criticality calculations used in the safety evaluation; in particular the availability and use of applicable critical experiment data. The purpose of the validation is to quantify the relationship between reality and calculated results. Validation and determination of bias and bias uncertainty require the identification of sets of critical experiments that are similar to the criticality safety models. A principal challenge for crediting fission products (FP) in a burnup credit safety evaluation is the limited availability of relevant FP critical experiments for bias and bias uncertainty determination. This paper provides an evaluation of the available critical experiments that include FPs, along with bounding, burnup-dependent estimates of FP biases generated by combining energy dependent sensitivity data for a typical burnup credit application with the nuclear data uncertainty information distributed with SCALE 6. A method for determining separate bias and bias uncertainty values for individual FPs and illustrative results is presented. Finally, a FP bias calculation method based on data adjustment techniques and reactivity sensitivity coefficients calculated with the SCALE sensitivity/uncertainty tools and some typical results is presented. Using the methods described in this paper, the cross-section bias for a representative high-capacity spent fuel cask associated with the ENDF/B-VII nuclear data for 16 most important stable or near stable FPs is predicted to be no greater than 2% of the total worth of the 16 FPs, or less than 0.13 % k/k.

  17. Experiences of a critical reflection program for mid-career nurses.

    Science.gov (United States)

    Oyamada, Kyoko

    2012-06-01

    The aim of the present study was to describe the experiences of Japanese nurses who participated in a critical reflection program for mid-career nurses. Critical reflection is one method that is appropriate for the professional development of mid-career nurses. However, its implementation is difficult because of the need for educational resources. Of the numerous reports on critical reflection outcomes, few delineate the underlying process and none relates to Japanese nurses. A program was developed, based on Mezirow's transformation theory, to facilitate nurses' critical reflection. The program was implemented at three hospitals in Japan with 14 mid-career nurses. The data-collection period was from 2006 to 2007. The grounded theory approach was used to describe the results. Two participants experienced a transformation in their frame of reference after undergoing critical reflection during the program. One participant's viewpoint began to change and the other's "habit of mind" (social norms and personality characteristics that provide one with a general orientation) changed. Both participants met the conditions that were necessary for transformation, such as having an open attitude toward change, and compared to the other participants, their critical reflection progressed markedly on the worksheets that were designed to promote critical reflection. The process of change in the frame of reference that was experienced by the two participants followed eight of the ten phases of Mezirow's transformation theory. The characteristics of the experiences of the two participants who underwent changes in their frame of reference were described and discussed. The conditions for such transformation and the effects of critical reflection on the participants were consistent with those reported by previous studies. © 2011 The Author. Japan Journal of Nursing Science © 2011 Japan Academy of Nursing Science.

  18. Overview of Experiments for Physics of Fast Reactors from the International Handbooks of Evaluated Criticality Safety Benchmark Experiments and Evaluated Reactor Physics Benchmark Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Bess, J. D.; Briggs, J. B.; Gulliford, J.; Ivanova, T.; Rozhikhin, E. V.; Semenov, M. Yu.; Tsibulya, A. M.; Koscheev, V. N.

    2017-07-01

    Overview of Experiments to Study the Physics of Fast Reactors Represented in the International Directories of Critical and Reactor Experiments John D. Bess Idaho National Laboratory Jim Gulliford, Tatiana Ivanova Nuclear Energy Agency of the Organisation for Economic Cooperation and Development E.V.Rozhikhin, M.Yu.Sem?nov, A.M.Tsibulya Institute of Physics and Power Engineering The study the physics of fast reactors traditionally used the experiments presented in the manual labor of the Working Group on Evaluation of sections CSEWG (ENDF-202) issued by the Brookhaven National Laboratory in 1974. This handbook presents simplified homogeneous model experiments with relevant experimental data, as amended. The Nuclear Energy Agency of the Organization for Economic Cooperation and Development coordinates the activities of two international projects on the collection, evaluation and documentation of experimental data - the International Project on the assessment of critical experiments (1994) and the International Project on the assessment of reactor experiments (since 2005). The result of the activities of these projects are replenished every year, an international directory of critical (ICSBEP Handbook) and reactor (IRPhEP Handbook) experiments. The handbooks present detailed models of experiments with minimal amendments. Such models are of particular interest in terms of the settlements modern programs. The directories contain a large number of experiments which are suitable for the study of physics of fast reactors. Many of these experiments were performed at specialized critical stands, such as BFS (Russia), ZPR and ZPPR (USA), the ZEBRA (UK) and the experimental reactor JOYO (Japan), FFTF (USA). Other experiments, such as compact metal assembly, is also of interest in terms of the physics of fast reactors, they have been carried out on the universal critical stands in Russian institutes (VNIITF and VNIIEF) and the US (LANL, LLNL, and others.). Also worth mentioning

  19. Consolidated fuel reprocessing program: Criticality experiments with fast test reactor fuel pins in an organic moderator

    Energy Technology Data Exchange (ETDEWEB)

    Bierman, S.R.

    1986-12-01

    The results obtained in a series of criticality experiments performed as part of a joint program on criticality data development between the United States Department of Energy and the Power Reactor and Nuclear Fuel Development Corporation of Japan are presented in this report along with a complete description of the experiments. The experiments involved lattices of Fast Test Reactor (FTR) fuel pins in an organic moderator mixture similar to that used in the solvent extraction stage of fuel reprocessing. The experiments are designed to provide data for direct comparison with previously performed experimental measurements with water moderated lattices of FTR fuel pins. The same lattice arrangements and FTR fuel pin types are used in these organic moderated experimental assemblies as were used in the water moderated experiments. The organic moderator is a mixture of 38 wt % tributylphosphate in a normal paraffin hydrocarbon mixture of C{sub 11}H{sub 24} to C{sub 15}H{sub 32} molecules. Critical sizes of 1054.8, 599.2, 301.8, 199.5 and 165.3 fuel pins were obtained respectively for organic moderated lattices having 0.761 cm, 0.968 cm, 1.242 cm, 1.537 cm and 1.935 cm square lattice pitches as compared to 1046.9, 571.9, 293.9, 199.7 and 165.1 fuel pins for the same lattices water moderated.

  20. The Experience of African Students Studying Nursing in the United States in Relation to Their Use of Critical Thinking

    Science.gov (United States)

    Tyson, Donald Lee

    2012-01-01

    This qualitative study explores the critical thinking experiences of African nursing students enrolled in several universities in the U.S. Using a semi-structured interview approach, twelve African students discussed their experiences using and learning a western critical thinking approach, as well as described their educational experiences in…

  1. Nuclear criticality experiments from 1943 to 1978: an annotated bibliography. Volume 1. Main listing

    Energy Technology Data Exchange (ETDEWEB)

    Koponen, B.L.; Wilcox, T.P.; Hampel, V.E.

    1979-04-24

    The bibliography contains 1067 citations from the literature of critical and near-critical nuclear experiments. It provides an up-to-date index to reports containing useful data for many types of criticality studies. Most of the reports can provide specifications for relatively simple critical configurations necessary for validating nuclear constants and calculational techniques. The reports of more than 1143 experimentors at 38 international facilities since 1943 are cross-referenced. The collection contains the prototypes of many different designs of nuclear reactors and studies performed to insure the safe use of fissile materials in chemical processing plants, storage facilities, and transportation containers. The bibliography has three volumes. Volume 1 contains the main listing of citations with abstracts. Volume 2 is a set of indexes organized by report number, publication date, experimental facility, and author name. Volume 3 provides a subject index, concorded on the significant keyphrases derived from titles, and an index of keyterms derived from titles, and an index of keyterms extracted from titles and abstracts. The bibliography was printed by computer as a selection from a computerized system at Lawrence Livermore Laboratory contaning information and data on criticality experiments.

  2. Diamagnetism in zigzag hexagonal graphene rings

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ning, E-mail: xuning79530@126.com [Department of Physics, Yancheng Institute of Technology, Yancheng 224051 (China); Chen, Qiao [Department of Physics, Hunan Institute of Engineering, Xiangtan 411104 (China); Tian, Hongyu [Department of Physics, Yancheng Institute of Technology, Yancheng 224051 (China); Wang, Baolin [Department of Physics, Nanjing Normal University, Nanjing 210023 (China); Ding, Jianwen [Department of Physics, Xiangtan University, Xiangtan 411105 (China)

    2016-03-06

    Highlights: • Hexagonal graphene rings possess unusually large diamagnetic moments. • The magnetic-field-driven carriers flow clockwise and anticlockwise along the inner and outer edge of rings. • The value of magnetic moment is almost proportional to the number of atoms of rings. - Abstract: The electronic structure and magnetic response of hexagonal graphene rings have been studied within the tight-binding formalism. The calculations show that hexagonal graphene rings possess unusually large diamagnetic moments in the presence of a perpendicular magnetic field. The magnetic-field-driven carriers flow clockwise and anticlockwise along the inner and outer edge of rings owing to quantum Hall effect. The value of magnetic moment is almost proportional to the number of atoms of rings, due to more conduction electrons participating in magnetic moment forming process. Additionally, we find the diamagnetic moment shows a relative weak dependence on the temperature.

  3. Diamagnetism in zigzag hexagonal graphene rings

    Science.gov (United States)

    Xu, Ning; Chen, Qiao; Tian, Hongyu; Wang, Baolin; Ding, Jianwen

    2016-03-01

    The electronic structure and magnetic response of hexagonal graphene rings have been studied within the tight-binding formalism. The calculations show that hexagonal graphene rings possess unusually large diamagnetic moments in the presence of a perpendicular magnetic field. The magnetic-field-driven carriers flow clockwise and anticlockwise along the inner and outer edge of rings owing to quantum Hall effect. The value of magnetic moment is almost proportional to the number of atoms of rings, due to more conduction electrons participating in magnetic moment forming process. Additionally, we find the diamagnetic moment shows a relative weak dependence on the temperature.

  4. Evaluation of the French Haut Taux de Combustion (HTC) Critical Experiment Data

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Don [ORNL; Hollenbach, Karla Riggle [ORNL; Fox, Patricia B [ORNL

    2008-09-01

    In the 1980s, a series of critical experiments referred to as the Haut Taux de Combustion (HTC) experiments was conducted by the Institut de Radioprotection et de Surete Nucleaire (IRSN) at the experimental criticality facility in Valduc, France. The plutonium-to- uranium ratio and the isotopic compositions of both the uranium and plutonium used in the simulated fuel rods were designed to be similar to what would be found in a typical pressurized-water reactor fuel assembly that initially had an enrichment of 4.5 wt% {sup 235}U and was burned to 37,500 MWd/MTU. The fuel material also includes {sup 241}Am, which is present due to the decay of {sup 241}Pu. The HTC experiments include configurations designed to simulate fuel handling activities, pool storage, and transport in casks constructed of thick lead or steel. Rights of use for the HTC experiment data were purchased under an agreement that limits release of the information. Consequently, a detailed and complete description of the experiments is not presented in this report. This report discusses evaluation of the four HTC data reports, modeling of the experiments, sensitivity and uncertainty analysis, and upper subcritical limit (USL) calculation. The report also presents some conclusions and recommendations concerning use of the HTC experiment data for burnup credit applications. The similarity of the HTC experiments with PWR spent nuclear fuel has been quantified using sensitivity/uncertainty analysis, confirming that the HTC experiments are significantly more applicable to the validation of burnup credit calculations than other available mixed-oxide (MOX) experiments. The HTC experiments were designed and executed with a high level of rigor, resulting in experimental uncertainties that are lower than many of the earlier MOX experiments. The HTC data reports, together with information provided in this report, provide sufficient data to allow for either detailed or simplified computational models to be

  5. The challenges of caring in a technological environment: critical care nurses' experiences.

    Science.gov (United States)

    McGrath, Mary

    2008-04-01

    This paper presents and discusses the findings from a phenomenological study which illuminated the lived experiences of experienced critical care nurses caring within a technological environment. While nursing practice is interwoven with technology, much of the literature in this area is speculative. Moreover, there is a debate as to whether and how 'high tech' and 'high touch' are reconcilable; this orientation is referred to as the optimism vs. pessimism debate. On a personal level, the motivation for this study came from the author's 13 years' experience in the critical care area. Following ethical approval, 10 experienced nurses from two cardiothoracic critical care units in Ireland participated in the study. A Heideggerian phenomenological methodology was used. Data collection consisted of unstructured interviews. A method of data analysis described by Walters was used. The findings provide research-based evidence to illuminate further the optimistic/pessimistic debate on technology in nursing. While the study demonstrates that the debate is far from resolved, it reveals a new finding: life-saving technology that supports the lives of critically ill patients can bring experienced nurses very close to their patients/families. The three main themes that emerged: 'alien environment', 'pulling together' and 'sharing the journey' were linked by a common thread of caring. Experienced critical care nurses are able to transcend the obtrusive nature of technology to deliver expert caring to their patients. However, the journey to proficiency in technology is very demanding and novice nurses have difficulty in caring with technology. Relevance to clinical practice. It is recommended that more emphasis be placed on supporting, assisting and educating inexperienced nurses in the critical care area and that the use of technology in nursing be given serious consideration.

  6. Criticality experiments with low enriched UO/sub 2/ fuel rods in water containing dissolved gadolinium

    Energy Technology Data Exchange (ETDEWEB)

    Bierman, S.R.; Murphy, E.S.; Clayton, E.D.; Keay, R.T.

    1984-02-01

    The results obtained in a criticality experiments program performed for British Nuclear Fuels, Ltd. (BNFL) under contract with the United States Department of Energy (USDOE) are presented in this report along with a complete description of the experiments. The experiments involved low enriched UO/sub 2/ and PuO/sub 2/-UO/sub 2/ fuel rods in water containing dissolved gadolinium, and are in direct support of BNFL plans to use soluble compounds of the neutron poison gadolinium as a primary criticality safeguard in the reprocessing of low enriched nuclear fuels. The experiments were designed primarily to provide data for validating a calculation method being developed for BNFL design and safety assessments, and to obtain data for the use of gadolinium as a neutron poison in nuclear chemical plant operations - particularly fuel dissolution. The experiments program covers a wide range of neutron moderation (near optimum to very under-moderated) and a wide range of gadolinium concentration (zero to about 2.5 g Gd/l). The measurements provide critical and subcritical k/sub eff/ data (1 greater than or equal to k/sub eff/ greater than or equal to 0.87) on fuel-water assemblies of UO/sub 2/ rods at two enrichments (2.35 wt % and 4.31 wt % /sup 235/U) and on mixed fuel-water assemblies of UO/sub 2/ and PuO/sub 2/-UO/sub 2/ rods containing 4.31 wt % /sup 235/U and 2 wt % PuO/sub 2/ in natural UO/sub 2/ respectively. Critical size of the lattices was determined with water containing no gadolinium and with water containing dissolved gadolinium nitrate. Pulsed neutron source measurements were performed to determine subcritical k/sub eff/ values as additional amounts of gadolinium were successively dissolved in the water of each critical assembly. Fission rate measurements in /sup 235/U using solid state track recorders were made in each of the three unpoisoned critical assemblies, and in the near-optimum moderated and the close-packed poisoned assemblies of this fuel.

  7. Knowledge, Skills and Experience Managing Tracheostomy Emergencies: A Survey of Critical Care Medicine trainees

    LENUS (Irish Health Repository)

    Nizam, AA

    2016-10-01

    Since the development of percutaneous tracheostomy, the number of tracheostomy patients on hospital wards has increased. Problems associated with adequate tracheostomy care on the wards are well documented, particularly the management of tracheostomy-related emergencies. A survey was conducted among non-consultant hospital doctors (NCHDs) starting their Critical Care Medicine training rotation in a university affiliated teaching hospital to determine their basic knowledge and skills in dealing with tracheostomy emergencies. Trainees who had received specific tracheostomy training or who had previous experience of dealing with tracheostomy emergencies were more confident in dealing with such emergencies compared to trainees without such training or experience. Only a minority of trainees were aware of local hospital guidelines regarding tracheostomy care. Our results highlight the importance of increased awareness of tracheostomy emergencies and the importance of specific training for Anaesthesia and Critical Care Medicine trainees.

  8. How Do Pharmacists Develop into Advanced Level Practitioners? Learning from the Experiences of Critical Care Pharmacists.

    Science.gov (United States)

    Seneviratne, Ruth E; Bradbury, Helen; Bourne, Richard S

    2017-07-07

    The national UK standards for critical care highlight the need for clinical pharmacists to practise at an advanced level (equivalent to Royal Pharmaceutical Society, Great Britain, Faculty Advanced Stage II (MFRPSII)) and above. Currently the UK is unable to meet the workforce capacity requirements set out in the national standards in terms of numbers of pharmacist working at advanced level and above. The aim of this study was to identify the strategies, barriers and challenges to achieving Advanced Level Practice (ALP) by learning from the experiences of advanced level critical care pharmacists within the UK. Eight participants were recruited to complete semi-structured interviews on their views and experiences of ALP. The interviews were analysed thematically and three overarching themes were identified; support, work-based learning and reflective practice. The results of this study highlight that to increase the number of MFRPSII level practitioners within critical care support for their ALP development is required. This support involves developing face-to-face access to expert critical care pharmacists within a national training programme. Additionally, chief pharmacists need to implement drivers including in house mentorship and peer review programmes and the need to align job descriptions and appraisals to the Royal Pharmaceutical Society, Great Britain, Advanced Practice Framework (APF).

  9. Critical experiments analyses by using 70 energy group library based on ENDF/B-VI

    Energy Technology Data Exchange (ETDEWEB)

    Tahara, Yoshihisa; Matsumoto, Hideki [Mitsubishi Heavy Industries Ltd., Yokohama (Japan). Nuclear Energy Systems Engineering Center; Huria, H.C.; Ouisloumen, M.

    1998-03-01

    The newly developed 70-group library has been validated by comparing kinf from a continuous energy Monte-Carlo code MCNP and two dimensional spectrum calculation code PHOENIX-CP. The code employs Discrete Angular Flux Method based on Collision Probability. The library has been also validated against a large number of critical experiments and numerical benchmarks for assemblies with MOX and Gd fuels. (author)

  10. In pursuit of critical literacy: Understanding experiences of exclusion for adult literacy learners

    OpenAIRE

    Howard, Margaret; Logan, Anna

    2012-01-01

    This paper explores exclusion and equality through critical theory, in the context of adult literacy provision in Ireland, by investigating the sites of exclusion that exist for a group of five male adult literacy learners. A summary review of literacy theories, exclusion and equality is provided framing the reporting of data from this collaborative action research study. Focus groups and visual methods were used to gather qualitative data relating to incidents, attitudes and experiences of e...

  11. A double concern: Grandmothers' experiences when a small grandchild is critically ill

    DEFF Research Database (Denmark)

    Hall, Elisabeth

    2004-01-01

    Grandmothers play an active part in family health and illness, but so far they are peripheral in both nursing and nursing research. This article addresses grandmothers' lived experiences when a small grandchild is critically ill. A convenience sample of 7 grandmothers was interviewed once....... With the use of the methodology of Van Manen, (1990), the essence of the phenomenon was found to be a "double concern," a worry and loving care that encompassed both parents and grandchildren. Although the findings have limitations, they constitute a systematic and thematic description of Danish grandmothers......' experiences and therefore add to a family-oriented body of knowledge in pediatric nursing....

  12. Experience-Dependent Equilibration of AMPAR-Mediated Synaptic Transmission during the Critical Period

    Directory of Open Access Journals (Sweden)

    Kyung-Seok Han

    2017-01-01

    Full Text Available Experience-dependent synapse refinement is essential for functional optimization of neural circuits. However, how sensory experience sculpts excitatory synaptic transmission is poorly understood. Here, we show that despite substantial remodeling of synaptic connectivity, AMPAR-mediated synaptic transmission remains at equilibrium during the critical period in the mouse primary visual cortex. The maintenance of this equilibrium requires neurogranin (Ng, a postsynaptic calmodulin-binding protein important for synaptic plasticity. With normal visual experience, loss of Ng decreased AMPAR-positive synapse numbers, prevented AMPAR-silent synapse maturation, and increased spine elimination. Importantly, visual deprivation halted synapse loss caused by loss of Ng, revealing that Ng coordinates experience-dependent AMPAR-silent synapse conversion to AMPAR-active synapses and synapse elimination. Loss of Ng also led to sensitized long-term synaptic depression (LTD and impaired visually guided behavior. Our synaptic interrogation reveals that experience-dependent coordination of AMPAR-silent synapse conversion and synapse elimination hinges upon Ng-dependent mechanisms for constructive synaptic refinement during the critical period.

  13. IT Teachers’ Experience of Teaching–Learning Strategies to Promote Critical Thinking

    Directory of Open Access Journals (Sweden)

    Roxanne Bailey

    2015-06-01

    Full Text Available Information Technology (IT high school learners are constantly struggling to cope with the challenges of succeeding in the subject. IT teachers, therefore, need to be empowered to utilize appropriate teaching–learning strategies to improve IT learners’ success in the subject. By promoting critical thinking skills, IT learners have the opportunity to achieve greater success in the most difficult part of the curriculum, which is programming. Participating IT teachers received once-off face-to-face professional development where some teachers received professional development in critical thinking strategies while other IT teachers received professional development in critical thinking strategies infused into pair programming. To determine how teachers experience these suggested strategies, teachers participated in initial interviews as well as follow-up interviews after they had implemented the suggested strategies. From the interviews, it became evident that teachers felt that their learners benefited from the strategies. Teachers in the pair programming infusing critical thinking strategies focused more on the pair programming implementation than on the totality of pair programming infused with critical thinking. Although teachers were initially willing to change their ways, they were not always willing to implement new teaching–learning strategies.

  14. Intrinsic ferromagnetism in hexagonal boron nitride nanosheets.

    Science.gov (United States)

    Si, M S; Gao, Daqiang; Yang, Dezheng; Peng, Yong; Zhang, Z Y; Xue, Desheng; Liu, Yushen; Deng, Xiaohui; Zhang, G P

    2014-05-28

    Understanding the mechanism of ferromagnetism in hexagonal boron nitride nanosheets, which possess only s and p electrons in comparison with normal ferromagnets based on localized d or f electrons, is a current challenge. In this work, we report an experimental finding that the ferromagnetic coupling is an intrinsic property of hexagonal boron nitride nanosheets, which has never been reported before. Moreover, we further confirm it from ab initio calculations. We show that the measured ferromagnetism should be attributed to the localized π states at edges, where the electron-electron interaction plays the role in this ferromagnetic ordering. More importantly, we demonstrate such edge-induced ferromagnetism causes a high Curie temperature well above room temperature. Our systematical work, including experimental measurements and theoretical confirmation, proves that such unusual room temperature ferromagnetism in hexagonal boron nitride nanosheets is edge-dependent, similar to widely reported graphene-based materials. It is believed that this work will open new perspectives for hexagonal boron nitride spintronic devices.

  15. Hexagonal metal modifications and thin film ferromagnetism

    NARCIS (Netherlands)

    Hueger, E.; Wormeester, Herbert; Bauer, E.

    1999-01-01

    Epitaxial strain-stabilized hexagonal modifications can occur in many metal films grown on (100) surfaces of cubic crystals and can have a strong influence on their magnetic properties. The necessary conditions for the formation of hcp crystals, identification criteria, examples and implications for

  16. Direct hydrothermal synthesis of metal intercalated hexagonal ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 115; Issue 5-6. Direct hydrothermal synthesis of metal intercalated hexagonal molybdates, M x + Mo 6 − x / 3 O 18 − x (OH) x . y H2O (M = Li, Rb, Cs, NH4). S Upreti A Ramanan. Volume 115 Issue 5-6 October-December 2003 pp 411-417 ...

  17. Recalled peer relationship experiences and current levels of self-criticism and self-reassurance.

    Science.gov (United States)

    Kopala-Sibley, Daniel C; Zuroff, David C; Leybman, Michelle J; Hope, Nora

    2013-03-01

    Numerous studies have shown that personality factors may increase or decrease individuals' vulnerability to depression, but little research has examined the role of peer relationships in the development of these factors. Accordingly, this study examined the role of recalled parenting and peer experiences in the development of self-criticism and self-reassurance. It was hypothesized that, controlling for recalled parenting behaviours, specific recalled experiences of peer relationships would be related to current levels of specific forms of self-criticism and self-reassurance. Hypotheses were tested using a retrospective design in which participants were asked to recall experiences of parenting and peer relationships during early adolescence. This age was chosen as early adolescence has been shown to be a critical time for the development of vulnerability to depression. A total of 103 female and 97 male young adults completed measures of recalled parenting, overt and relational victimization and prosocial behaviour by peers, and current levels of self-criticism and self-reassurance. Hierarchical regression analyses showed that parents and peers independently contributed to the development of self-criticism and self-reassurance. Specifically, controlling for parental care and control, overt victimization predicted self-hating self-criticism, relational victimization predicted inadequacy self-criticism, and prosocial behaviour predicted self-reassurance. As well, prosocial behaviour buffered the effect of overt victimization on self-reassurance. Findings highlight the importance of peers in the development of personality risk and resiliency factors for depression, and suggest avenues for interventions to prevent the development of depressive vulnerabilities in youth. The nature of a patient's personality vulnerability to depression may be better understood through a consideration of the patient's relationships with their peers as well as with parents during

  18. Critical success factors for positive user experience in hotel websites:applying Herzberg’s two factor theory for user experience modeling

    OpenAIRE

    Sambhanthan, Arunasalam; Good, Alice

    2013-01-01

    This research presents the development of a critical success factor matrix for increasing positive user experience of hotel websites based upon user ratings. Firstly, a number of critical success factors for web usability have been identified through the initial literature review. Secondly, hotel websites were surveyed in terms of critical success factors identified through the literature review. Thirdly, Herzberg’s motivation theory has been applied to the user rating and the critical succ...

  19. Experiences of health professionals with nutritional support of critically ill patients in tertiary hospitals in Malawi.

    Science.gov (United States)

    Bunyani, A; Mtimuni, B; Kalimbira, A; Kamalo, P

    2015-03-01

    Nutritional support is a recognized determinant of outcome in critically ill patients. Development of critical care services in low-income countries has not been accompanied by certain appropriate ancillary services and interventions, such as adequate nutritional support. This study was designed to investigate the experiences of health professionals who have provided nutritional supportive care to critically ill patients admitted to two major central hospitals in Malawi, with the aim of identifying the common practices in nutritional support in these settings. A cross-sectional study in which 50 health professionals working in intensive care and high dependency units, admitting both adult and pediatric patients, were interviewed using a semi-structured questionnaire. Data were coded and then analyzed using SPSS version 16.0. Responses between the two hospitals were compared using Fisher's exact test. There was no difference in the composition of respondents from the two hospitals. About 60% of respondents had had experience with nutritional supplementation in their patients-mainly enteral. The most commonly used formulations were the "ready-to-use therapeutic feeds," followed by modified milk. A high percentage of respondents (40%) reported having used dextrose solution as the sole nutritional supplement. Lack of in-service training, nonexistent nutrition protocols pertaining to acutely and critically ill patients, and a lack of clinical nutritionists were the major challenges identified. Knowledge of nutrient supplementation was poor among the respondents. The use of ready-to-use therapeutic feeds was quite common, although there is no evidence of its effectiveness in care of acutely critically ill patients. There is a need to establish nutritional support teams in these tertiary hospitals. Clinical nutritionists would ideally help train and play leadership roles in such teams, who would be responsible for assessing patients for their nutritional needs, and

  20. Nurturing a lexical legacy: reading experience is critical for the development of word reading skill

    Science.gov (United States)

    Nation, Kate

    2017-01-01

    The scientific study of reading has taught us much about the beginnings of reading in childhood, with clear evidence that the gateway to reading opens when children are able to decode, or `sound out' written words. Similarly, there is a large evidence base charting the cognitive processes that characterise skilled word recognition in adults. Less understood is how children develop word reading expertise. Once basic reading skills are in place, what factors are critical for children to move from novice to expert? This paper outlines the role of reading experience in this transition. Encountering individual words in text provides opportunities for children to refine their knowledge about how spelling represents spoken language. Alongside this, however, reading experience provides much more than repeated exposure to individual words in isolation. According to the lexical legacy perspective, outlined in this paper, experiencing words in diverse and meaningful language environments is critical for the development of word reading skill. At its heart is the idea that reading provides exposure to words in many different contexts, episodes and experiences which, over time, sum to a rich and nuanced database about their lexical history within an individual's experience. These rich and diverse encounters bring about local variation at the word level: a lexical legacy that is measurable during word reading behaviour, even in skilled adults.

  1. Modelling of CANDU-SCWR unit cell with DRAGON: from cartesian to hexagonal geometry

    Energy Technology Data Exchange (ETDEWEB)

    Bejaoui, N.; Marleau, G. [Ecole Polytechnique de Montreal, Institute of Nuclear Engineering, Montreal, QC (Canada)

    2014-07-01

    A new hexagonal model of the Canadian supercritical water-cooled reactor unit cell geometry is compared with the Cartesian model in DRAGON. This hexagonal model is considered for a compact core since further savings in the construction costs can be achieved by a reduction in the heavy water inventory in the core while still satisfying the constraints on the mechanical size of the pressure tube header. In our study, we investigate two options: using a reduced lattice pitch while preserving the same pressure tube; and increasing the outer radius of the pressure tube while using an hexagonal cell that has the same 2-D volume as the original Cartesian model. Preliminary results indicate that the effective multiplication factor of the equivalent hexagonal unit cell is slightly lower than of the original Cartesian cell (0.15 mk). Reducing the lattice pitch of the hexagonal cell to that of the Cartesian cell decreases further the reactivity (20 mk) but reduces the moderator volume by more than 20 %. Other options for reducing the moderator volume that consists in increasing the outer radius of the pressure tube are analyzed, including replacing the moderator by super critical light water coolant or other structure material. (author)

  2. Charge exchange contamination of CRIT-II barium CIV experiment. [critical ionization velocity in ionosphere

    Science.gov (United States)

    Swenson, G. R.; Mende, S. B.; Meyerott, R. E.; Rairden, R. L.

    1991-01-01

    Experiments have been recently performed which attempted to confirm critical ionization velocity (CIV) ionization by deploying chemicals at high velocity in the ionosphere. Specifically, the CRIT-II rocket performed a barium release in the ionosphere, where observations of Ba(+) resonant emissions following the release are believed to have resulted from the CIV process. Calculations are presented which suggest a significant fraction (if not all) of the Ba(+) observed likely resulted from charge exchange with the thermosphere ions and not through CIV processes. The results presented here are pertinent to other CIV experiments performed in the ionosphere. It is recommended that laboratory measurements should be made of the charge exchange cross section between O(+) and Ba as well as other metal vapors used in CIV experiments.

  3. A critical exploration of how English language learners experience nursing education.

    Science.gov (United States)

    Mulready-Shick, N

    2013-01-01

    With nursing education reform calling for greater numbers of graduates from diverse backgrounds, this study explored the experiences of students who identified as English language learners (ELs). Educators may view students from underrepresented groups at the margins of nursing education. Minimal research on the experiences of students identifying as ELs exists. Interpretive phenomenological and critical methodologies were used to explore students' lived experiences in the nursing classroom. Academic progress involved additional time and effort dedicated to learning English and the languages of health care and nursing. Traditional and monocultural pedagogical practices, representing acts of power and dominance, thwarted learning. Yet students made progress despite less effective pedagogical practices and socioeconomic realities. This inquiry began with one notion of identity, "English-learners," but evolved to students' perceptions of "being-in-the-world," wholeness, and future endeavors. This study counters the dominant view that students without a greater command of English are not ready for the rigors of nursing education.

  4. Nutritional care after critical illness: a qualitative study of patients' experiences.

    Science.gov (United States)

    Merriweather, J L; Salisbury, L G; Walsh, T S; Smith, P

    2016-04-01

    The present qualitative study aimed to explore the factors influencing nutritional recovery in patients after critical illness and to develop a model of care to improve current management of nutrition for this patient group. Patients were recruited into the study on discharge from a general intensive care unit (ICU) of a large teaching hospital in central Scotland. Semi-structured interviews were carried out after discharge from the ICU, weekly for the duration of their ward stay, and at 3 months post ICU discharge. Observations of ward practice were undertaken thrice weekly for the duration of the ward stay. Seventeen patients were recruited into the study and, using a grounded theory approach, 'inter-related system breakdowns during the nutritional recovery process' emerged as the overarching core category that influenced patients' experiences of eating after critical illness. This encompassed the categories, 'experiencing a dysfunctional body', 'experiencing socio-cultural changes in relation to eating' and 'encountering nutritional care delivery failures'. The findings from the present study provide a unique contribution to knowledge by offering important insights into patients' experiences of eating after critical illness. The study has identified numerous nutritional problems and raises questions about the efficacy of current nutritional management in this patient group. Adopting a more individualised approach to nutritional care could ameliorate the nutritional issues experienced by post ICU patients. This will be evaluated in future work. © 2014 The British Dietetic Association Ltd.

  5. 'Visual' parsing can be taught quickly without visual experience during critical periods.

    Science.gov (United States)

    Reich, Lior; Amedi, Amir

    2015-10-20

    Cases of invasive sight-restoration in congenital blind adults demonstrated that acquiring visual abilities is extremely challenging, presumably because visual-experience during critical-periods is crucial for learning visual-unique concepts (e.g. size constancy). Visual rehabilitation can also be achieved using sensory-substitution-devices (SSDs) which convey visual information non-invasively through sounds. We tested whether one critical concept--visual parsing, which is highly-impaired in sight-restored patients--can be learned using SSD. To this end, congenitally blind adults participated in a unique, relatively short (~70 hours), SSD-'vision' training. Following this, participants successfully parsed 2D and 3D visual objects. Control individuals naïve to SSDs demonstrated that while some aspects of parsing with SSD are intuitive, the blind's success could not be attributed to auditory processing alone. Furthermore, we had a unique opportunity to compare the SSD-users' abilities to those reported for sight-restored patients who performed similar tasks visually, and who had months of eyesight. Intriguingly, the SSD-users outperformed the patients on most criteria tested. These suggest that with adequate training and technologies, key high-order visual features can be quickly acquired in adulthood, and lack of visual-experience during critical-periods can be somewhat compensated for. Practically, these highlight the potential of SSDs as standalone-aids or combined with invasive restoration approaches.

  6. Evaluation of undergraduate clinical learning experiences in the subject of pediatric dentistry using critical incident technique.

    Science.gov (United States)

    Vyawahare, S; Banda, N R; Choubey, S; Parvekar, P; Barodiya, A; Dutta, S

    2013-01-01

    In pediatric dentistry, the experiences of dental students may help dental educators better prepare graduates to treat the children. Research suggests that student's perceptions should be considered in any discussion of their education, but there has been no systematic examination of India's undergraduate dental students learning experiences. This qualitative investigation aimed to gather and analyze information about experiences in pediatric dentistry from the students' viewpoint using critical incident technique (CIT). The sample group for this investigation came from all 240 3rd and 4th year dental students from all the four dental colleges in Indore. Using CIT, participants were asked to describe at least one positive and one negative experience in detail. They described 308 positive and 359 negative experiences related to the pediatric dentistry clinic. Analysis of the data resulted in the identification of four key factors related to their experiences: 1) The instructor; 2) the patient; 3) the learning process; and 4) the learning environment. The CIT is a useful data collection and analysis technique that provides rich, useful data and has many potential uses in dental education.

  7. Non-solar UV produced ions observed optically from the 'Crit I' critical velocity ionization experiment

    Science.gov (United States)

    Stenbaek-Nielsen, H. C.; Wescott, E. M.; Rees, D.; Valenzuela, A.; Brenning, N.

    1990-01-01

    A critical velocity ionization experiment was carried out with a heavily instrumented rocket launched from Wallops Island on May 13, 1986. Two neutral barium beams were created by explosive shaped charges released from the rocket and detonated at 48 deg to B at altitudes near 400 km and below the solar UV cutoff. Critical velocity ionization was expected to form a detectable ion jet along the release field line, but, instead, an ion cloud of fairly uniform intensity was observed stretching from the release field line across to where the neutral barium jet reached sunlight. The process creating these ions must have been present from the time of the release; the efficiency is estimated to be equivalent to an ionization time constant of 1800 sec. This ionization is most likely from collisions between the neutral barium jet and the ambient atmospheric oxygen, and, if so, the cross section for collisional ionization is 9 x 10 to the -18th sq cm.

  8. Long-Term Soil Experiments: A Key to Managing Earth's Rapidly Changing Critical Zones

    Science.gov (United States)

    Richter, D., Jr.

    2014-12-01

    In a few decades, managers of Earth's Critical Zones (biota, humans, land, and water) will be challenged to double food and fiber production and diminish adverse effects of management on the wider environment. To meet these challenges, an array of scientific approaches is being used to increase understanding of Critical Zone functioning and evolution, and one amongst these approaches needs to be long-term soil field studies to move us beyond black boxing the belowground Critical Zone, i.e., to further understanding of processes driving changes in the soil environment. Long-term soil experiments (LTSEs) provide direct observations of soil change and functioning across time scales of decades, data critical for biological, biogeochemical, and environmental assessments of sustainability; for predictions of soil fertility, productivity, and soil-environment interactions; and for developing models at a wide range of temporal and spatial scales. Unfortunately, LTSEs globally are not in a good state, and they take years to mature, are vulnerable to loss, and even today remain to be fully inventoried. Of the 250 LTSEs in a web-based network, results demonstrate that soils and belowground Critical Zones are highly dynamic and responsive to human management. The objective of this study is to review the contemporary state of LTSEs and consider how they contribute to three open questions: (1) can soils sustain a doubling of food production in the coming decades without further impinging on the wider environment, (2) how do soils interact with the global C cycle, and (3) how can soil management establish greater control over nutrient cycling. While LTSEs produce significant data and perspectives for all three questions, there is on-going need and opportunity for reviews of the long-term soil-research base, for establishment of an efficiently run network of LTSEs aimed at sustainability and improving management control over C and nutrient cycling, and for research teams that

  9. Critical experiments on single-unit spherical plutonium geometries reflected and moderated by oil

    Energy Technology Data Exchange (ETDEWEB)

    Rothe, R.E.

    1997-05-01

    Experimental critical configurations are reported for several dozen spherical and hemispherical single-unit assemblies of plutonium metal. Most were solid but many were hollow-centered, thick, shell-like geometries. All were constructed of nested plutonium (mostly {sup 2139}Pu) metal hemispherical shells. Three kinds of critical configurations are reported. Two required interpolation and/or extrapolation of data to obtain the critical mass because reflector conditions were essentially infinite. The first finds the plutonium essentially fully reflected by a hydrogen-rich oil; the second is essentially unreflected. The third kind reports the critical oil reflector height above a large plutonium metal assembly of accurately known mass (no interpolation required) when that mass was too great to permit full oil reflection. Some configurations had thicknesses of mild steel just outside the plutonium metal, separating it from the oil. These experiments were performed at the Rocky Flats Critical Mass Laboratory in the late 1960s. They have not been published in a form suitable for benchmark-quality comparisons against state-of-the-art computational techniques until this paper. The age of the data and other factors lead to some difficulty in reconstructing aspects of the program and may, in turn, decrease confidence in certain details. Whenever this is true, the point is acknowledged. The plutonium metal was alpha-phase {sup 239}Pu containing 5.9 wt-% {sup 240}Pu. All assemblies were formed by nesting 1.667-mm-thick (nominal) bare plutonium metal hemispherical shells, also called hemishells, until the desired configuration was achieved. Very small tolerance gaps machined into radial dimensions reduced the effective density a small amount in all cases. Steel components were also nested hemispherical shells; but these were nominally 3.333-mm thick. Oil was used as the reflector because of its chemical compatibility with plutonium metal.

  10. Generation of integral experiment covariance data and their impact on criticality safety validation

    Energy Technology Data Exchange (ETDEWEB)

    Stuke, Maik; Peters, Elisabeth; Sommer, Fabian

    2016-11-15

    The quantification of statistical dependencies in data of critical experiments and how to account for them properly in validation procedures has been discussed in the literature by various groups. However, these subjects are still an active topic in the Expert Group on Uncertainty Analysis for Criticality Safety Assessment (UACSA) of the OECDNEA Nuclear Science Committee. The latter compiles and publishes the freely available experimental data collection, the International Handbook of Evaluated Criticality Safety Benchmark Experiments, ICSBEP. Most of the experiments were performed as series and share parts of experimental setups, consequently leading to correlation effects in the results. The correct consideration of correlated data seems to be inevitable if the experimental data in a validation procedure is limited or one cannot rely on a sufficient number of uncorrelated data sets, e.g. from different laboratories using different setups. The general determination of correlations and the underlying covariance data as well as the consideration of them in a validation procedure is the focus of the following work. We discuss and demonstrate possible effects on calculated k{sub eff}'s, their uncertainties, and the corresponding covariance matrices due to interpretation of evaluated experimental data and its translation into calculation models. The work shows effects of various modeling approaches, varying distribution functions of parameters and compares and discusses results from the applied Monte-Carlo sampling method with available data on correlations. Our findings indicate that for the reliable determination of integral experimental covariance matrices or the correlation coefficients a detailed study of the underlying experimental data, the modeling approach and assumptions made, and the resulting sensitivity analysis seems to be inevitable. Further, a Bayesian method is discussed to include integral experimental covariance data when estimating an

  11. The Qualification Experiences for Safety-critical Software of POSAFE-Q

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jang Yeol; Son, Kwang Seop; Cheon, Se Woo; Lee, Jang Soo; Kwon, Kee Choon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-05-15

    Programmable Logic Controllers (PLC) have been applied to the Reactor Protection System (RPS) and the Engineered Safety Feature (ESF)-Component Control System (CCS) as the major safety system components of nuclear power plants. This paper describes experiences on the qualification of the safety-critical software including the pCOS kernel and system tasks related to a safety-grade PLC, i.e. the works done for the Software Verification and Validation, Software Safety Analysis, Software Quality Assurance, and Software Configuration Management etc.

  12. Nanocrystalline hexagonal diamond formed from glassy carbon

    OpenAIRE

    Shiell, Thomas. B.; McCulloch, Dougal G.; Bradby, Jodie E.; Haberl, Bianca; Boehler, Reinhard; McKenzie, David. R.

    2016-01-01

    Carbon exhibits a large number of allotropes and its phase behaviour is still subject to significant uncertainty and intensive research. The hexagonal form of diamond, also known as lonsdaleite, was discovered in the Canyon Diablo meteorite where its formation was attributed to the extreme conditions experienced during the impact. However, it has recently been claimed that lonsdaleite does not exist as a well-defined material but is instead defective cubic diamond formed under high pressure a...

  13. Epitaxial Hexagonal Ferrites for Millimeter Wave Devices.

    Science.gov (United States)

    1987-02-01

    project, LPE films of strontium hexaferrite (SrFe12019) were grown using PbO-B 20 3 solvent. The solution composition was 7 C 8344TCD/sn...which resulted in improved quality of barium hexaferrite films deposited on gallate spinel substrates (indium substituted magnesium gallium oxide...hexagonal ferrite films obtained by this method were more uniform and more strongly bonded to the substrate than films grown without the intermediary

  14. Sandbox rheometry: Co-evolution of stress and strain in Riedel- and Critical Wedge-experiments

    Science.gov (United States)

    Ritter, Malte C.; Santimano, Tasca; Rosenau, Matthias; Leever, Karen; Oncken, Onno

    2018-01-01

    Analogue sandbox experiments have been used for a long time to understand tectonic processes, because they facilitate detailed measurements of deformation at a spatio-temporal resolution unachievable from natural data. Despite this long history, force measurements to further characterise the mechanical evolution in analogue sandbox experiments have only emerged recently. Combined continuous measurements of forces and deformation in such experiments, an approach here referred to as "sandbox rheometry", are a new tool that may help to better understand work budgets and force balances for tectonic systems and to derive constitutive laws for regional scale deformation. In this article we present an experimental device that facilitates precise measurements of boundary forces and surface deformation at high temporal and spatial resolution. We demonstrate its capabilities in two classical experiments: one of strike-slip deformation (the Riedel set-up) and one of compressional accretionary deformation (the Critical Wedge set-up). In these we are able to directly observe a correlation between strain weakening and strain localisation that had previously only been inferred, namely the coincidence of the maximum localisation rate with the onset of weakening. Additionally, we observe in the compressional experiment a hysteresis of localisation with respect to the mechanical evolution that reflects the internal structural complexity of an accretionary wedge.

  15. Handling of time-critical Conditions Data in the CMS experiment - Experience of the first year of data taking

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    Data management for a wide category of non-event data plays a critical role in the operation of the CMS experiment. The processing chain (data taking-reconstruction-analysis) relies in the prompt availability of specific, time dependent data describing the state of the various detectors and their calibration parameters, which are treated separately from event data. The Condition Database system is the infrastructure established to handle these data and to make sure that they are available to both offline and online workflows. The Condition Data layout is designed such that the payload data (the Condition) is associated to an Interval Of Validity (IOV). The IOV allows accessing selectively the sets corresponding to specific intervals of time, run number or luminosity section. Both payloads and IOVs are stored in a cluster of relational database servers (Oracle) using an object-relational access approach. The strict requirements of security and isolation of the CMS online systems are imposing a redundant archit...

  16. Interpretation of the electric fields measured in an ionospheric critical ionization velocity experiment

    Science.gov (United States)

    Brenning, N.; Faelthammar, C.-G.; Marklund, G.; Haerendel, G.; Kelley, M. C.; Pfaff, R.

    1991-01-01

    The quasi-dc electric fields measured in the CRIT I ionospheric release experiment are studied. In the experiment, two identical barium shaped charges were fired toward a main payload, and three-dimensional measurements of the electric field inside the streams were made. The relevance of proposed mechanisms for electron heating in the critical ionization velocity (CIV) mechanism is addressed. It is concluded that both the 'homogeneous' and the 'ionizing front' models probably are valid, but in different parts of the streams. It is also possible that electrons are directly accelerated by a magnetic field-aligned component of the electric field. The coupling between the ambient ionosphere and the ionized barium stream is more complicated that is usually assumed in CIV theories, with strong magnetic-field-aligned electric fields and probably current limitation as important processes.

  17. Working together: critical care nurses experiences of temporary staffing within Swedish health care: A qualitative study.

    Science.gov (United States)

    Berg Jansson, Anna; Engström, Åsa

    2017-08-01

    The aim of this study is to describe critical care nurses (CCN's) experiences of working with or as temporary agency staff. This explorative qualitative study is based on interviews with five agency CCNs and five regular CCNs, a total of ten interviews, focusing on the interviewees' experiences of daily work and temporary agency staffing. The interviews were analysed manually and thematically following an inductive approach. Four themes that illustrate both similarities and differences between regular and temporary agency CCNs emerged: "working close to patients versus being responsible for everything", "teamwork versus independence", "both groups needed" and "opportunities and challenges". The study findings illustrate the complexity of the working situation for agency and regular staff in terms of the organisation and management of the temporary agency nurses and the opportunities and challenges faced by both groups. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Grid cell hexagonal patterns formed by fast self-organized learning within entorhinal cortex.

    Science.gov (United States)

    Mhatre, Himanshu; Gorchetchnikov, Anatoli; Grossberg, Stephen

    2012-02-01

    Grid cells in the dorsal segment of the medial entorhinal cortex (dMEC) show remarkable hexagonal activity patterns, at multiple spatial scales, during spatial navigation. It has previously been shown how a self-organizing map can convert firing patterns across entorhinal grid cells into hippocampal place cells that are capable of representing much larger spatial scales. Can grid cell firing fields also arise during navigation through learning within a self-organizing map? This article describes a simple and general mathematical property of the trigonometry of spatial navigation which favors hexagonal patterns. The article also develops a neural model that can learn to exploit this trigonometric relationship. This GRIDSmap self-organizing map model converts path integration signals into hexagonal grid cell patterns of multiple scales. GRIDSmap creates only grid cell firing patterns with the observed hexagonal structure, predicts how these hexagonal patterns can be learned from experience, and can process biologically plausible neural input and output signals during navigation. These results support an emerging unified computational framework based on a hierarchy of self-organizing maps for explaining how entorhinal-hippocampal interactions support spatial navigation. Copyright © 2010 Wiley Periodicals, Inc.

  19. Pathways and pipelines: Self-reported critical experiences for expert and novice geologists

    Science.gov (United States)

    LaDue, N.; Pacheco, H. A.

    2011-12-01

    The recruitment and retention of geology students has received attention due to pressure from industry to replenish an aging workforce nearing retirement (Gonzales and Keane, 2010). Thorough, qualitative studies have been conducted using critical incident methodology to understand what experiences cause various groups of people to choose careers in the geosciences or geoscience degree programs (Levine et al., 2007; Houlton, 2010). This study both builds upon earlier studies and provides new insights about capacity building in the geosciences. Individuals who have been successfully pipelined into the geosciences ranging from upper-level undergraduates to decades-long professionals, were selected for an expert-novice study about field mapping. All of the 38 participants have field-mapping experience and were selected to achieve a balance of age, gender and experience in the sample and secondarily based on geographic diversity. Participants were asked how they became interested in geology as the last question of an interview about the other tasks during the study. Participants were surficially probed, in contrast to in-depth interviews conducted using critical incident methods. Remarkably, though the interview question was unstructured and open ended, the three persistent themes that emerged are consistent with previous studies of women geologists (Holmes and O'Connell, 2003), under-represented minorities (Levine et al., 2007), and undergraduate geoscience majors (Houlton, 2010): Role or influence of academic experience, influence of and/or connections with people and connections with Earth. Additionally, individual participant comments are well aligned the proposed framework by Kraft et al. (2011) for engaging geoscience students through the affective domain. We suggest that future studies should examine whether these findings are consistent across geologists from sub-domains that are less field-based and involve primarily modeling, or other computer- and lab

  20. Structural and Oxygen Storage Properties of Hexagonal Manganites

    Science.gov (United States)

    Abughayada, Castro; Dabrowski, Bogdan; Kolesnik, Stan; Chmaissem, Omar; NIU Team

    2013-03-01

    Complex oxides exhibiting superior reversible oxygen absorption/release capacities have been generating a great deal of interest due to their critical role in the development of energy related technologies, such as oxy-fuel and chemical looping combustion. Based on our previous studies of tolerance factor, we have successfully synthesized hexagonal (P63cm) RMnO3+δ manganites (R =Dy, Ho, Y) for which we discovered a large reversible oxygen storage/release capacities (within the range of oxygen content 3.0 - 3.4) at unusually low temperatures near 300 °C which make them excellent candidates for air separation and production of high purity oxygen. Resistivity, structural, magnetic, and thermal expansion properties are correlated with the oxygen content 3 + δ for these compounds. Work supported by NIU Great Journey Assistantship.

  1. Studium lokální struktury hexagonálních feritů metodami NMR

    OpenAIRE

    Kouřil, Karel

    2013-01-01

    Title: Local structure of hexagonal ferrites studied by NMR Author: Karel Kouřil Department/Institute: Department of Low Temperature Physics Supervisor of the doctoral thesis: prof. RNDr. Helena Štěpánková, CSc. Abstract: Hexagonal ferrites of M, W, X and Y structure types were studied by means of NMR, electronic structure calculations and magnetoelectric experi- ments. Presented results deal with cation distribution, localization of ferrous ions, interpretation of NMR spectra of studied mate...

  2. Bereavement coping strategies on the death of the critical ill patients: perceptions and nursing experiences

    Directory of Open Access Journals (Sweden)

    María Gálvez González

    2013-05-01

    Full Text Available Aim. To explore the coping strategies responses that the intensive care unit nurses experiment when facing the death of a critical ill patient.Methods. Qualitative study of a phenomenological nature carried out on 16 professionals throughin-depth interviews. The selection of the participants was intentional and the incorporation was progressive until reaching the data saturation. The analytic scheme, proposed by Taylor- Bogdan, was followed to effectuate the data analysis.Results. The coping strategies identified after the qualitative analysis were grouped according to their frequency of appearance in primary and secondary strategies. Acceptance and distance are resources of primary coping strategies, whereas search for social support, self-confidence, cognitive redefinition, generation of positive emotions, denial and search for spiritual support are secondary coping strategies.Conclusion. Bereavement coping strategies on the death of the critical ill patients is a very complex process which implies that nurses mobilize a large group of emotional resources to achieve adaptation. The strategies of acceptance and distance, as they are described in this study, must be considered adaptative strategies that demonstrate very clearly that caring for critical ill patients represents a significant fight for nurses in a personal and professional sense.

  3. Integrating Critical Pedagogy theory and practice: classroom experiences in Argentinean EFL teacher education

    Directory of Open Access Journals (Sweden)

    Zelmira Álvarez

    2012-10-01

    Full Text Available Argentinean ESL teacher education presupposes an understanding of the past and present world role of English. Thus, the curriculum of the ESL Teacher Education Program at Universidad Nacional de Mar del Plata includes subjects dealing with historical, cultural, and social questions concerning English-cultures worldwide. This paper explains how some of these issues are addressed in activities carried out in the sophomore course Overall Communication. They involve critical and postcolonial analysis of the film Slumdog millionaire (2008 and the story “The free radio” (Rushdie, 1994. Activities aim at making student-teachers aware of their need to critically address concepts related to race, ethnicity, class, religion, education, and language to unveil the political, economic, and social issues underlying the teaching and learning of English. The choice of materials and authors also aims at listening to English-speaking voices other than those stemming from (former imperial centers. Activities involve research and discussions of problematics such as oppression, exclusion, and illiteracy. This paper will analyze sample written productions by students working collaboratively among themselves and cooperatively with their teachers. In short, this is an experience that strives at showing how Critical Pedagogy can become a site for raising questions concerning power and EFL teaching and learning.

  4. The effect of leadership behaviours on followers’ experiences and expectations in a safety-critical industry

    Directory of Open Access Journals (Sweden)

    Christiaan G. Joubert

    2017-04-01

    Full Text Available Background: Motivation for this study was found in concern expressed by civil aviation organisations that specialists in the air navigation services provider sector require appropriate and beneficial organisational leadership to encourage, enable and manage transformation within this highly structured setting. Also, academic research puts emphasis on a need for investigations of the roles, expectations and requirements of followers in the leadership–followership relationship. Followers’ experiences and expectations of leadership behaviours in an air navigation service provider (ANSP organisation were investigated and served as orientation and setting applicable to this study. Aim: The aim of the research was to identify and understand how follower experiences and expectations of leadership behaviours in a safety-critical commercial environment can affect leadership training and growth. The above-mentioned motivated this investigation of leadership traits and behaviours within an explicit context and from a follower’s viewpoint. Setting: The setting for the study was twenty two Air Traffic and Navigation Services Company sites where followers’ experiences and expectations of leadership behaviours in an air navigation service provider (ANSP organisation were investigated and served as orientation and setting applicable to this study. Methods: An ethnographic case study research style was adopted and followed because it allowed for an all-inclusive, holistic narrative report and interpretation. The samples for the quantitative and qualitative components of this study were parallel and methods employed addressed different aspects of the phenomenon, which allowed for a mixed methods research design. A one-way causality in the research design was observed because traits of followers that might influence leaders’ behaviours were excluded. Data were collected by means of a Leader Trait and Behaviour Questionnaire completed by participants

  5. Experiences for Education –What for? Training and inclusion in perspective of Critical Theory

    Directory of Open Access Journals (Sweden)

    Valdelúcia Alves da Costa

    2013-06-01

    Full Text Available This essay discusses possibilities of formative experiences in education and its relation to inclusion, with reference to Critical Theory, with emphasis on the thought ofAdorno (2002; 2000, as to its emancipatory dimension inprocess of training of teachers and their activities in the area of inclusive education. Adorno analyzes the purposes of education as having central question - ‘Education – What for?’, starting from the initial idea about the formative experiences, as marked by resistance actions that are contradictory and dialectically against what is standardized, imposed and regulated and crystallized in class society, under the aegis of the capital. Adorno, to consider education after Auschwitz, says that causes that led to barbarism still exist, as they have to persist in the fundamental conditions that generate this regression. Despite the non-visibility of the current woes in its entirety, social pressure keeps imposing on all individuals, with or without disabilities, and at current stage of civilization, education makes sense only if directed to critical self- reflection and combating prejudice in school and other social organizations. Thus, only effective power against principle of Auschwitz would beautonomy, power to reflection and self-determination of individuals in society in favor of social inclusion and inclusive education.

  6. Nursing care in a high-technological environment: Experiences of critical care nurses.

    Science.gov (United States)

    Tunlind, Adam; Granström, John; Engström, Åsa

    2015-04-01

    Management of technical equipment, such as ventilators, infusion pumps, monitors and dialysis, makes health care in an intensive care setting more complex. Technology can be defined as items, machinery and equipment that are connected to knowledge and management to maximise efficiency. Technology is not only the equipment itself, but also the knowledge of how to use it and the ability to convert it into nursing care. The aim of this study is to describe critical care nurses' experience of performing nursing care in a high technology healthcare environment. Qualitative, personal interviews were conducted during 2012 with eight critical care nurses in the northern part of Sweden. Interview transcripts were analysed using qualitative content analysis. Three themes with six categories emerged. The technology was described as a security that could facilitate nursing care, but also one that could sometimes present obstacles. The importance of using the clinical gaze was highlighted. Nursing care in a high technological environment must be seen as multi-faceted when it comes to how it affects CCNs' experience. The advanced care conducted in an ICU could not function without high-tech equipment, nor could care operate without skilled interpersonal interaction and maintenance of basal nursing. That technology is seen as a major tool and simultaneously as a barrier to patient-centred care. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Clinical accompaniment: the critical care nursing students’ experiences in a private hospital

    Directory of Open Access Journals (Sweden)

    N. Tsele

    2000-09-01

    Full Text Available The quality of clinical accompaniment of the student enrolled for the post-basic diploma in Medical and Surgical Nursing Science: Critical Care Nursing (General is an important dimension of the educational/learning programme. The clinical accompanist/mentor is responsible for ensuring the student’s compliance with the clinical outcomes of the programme in accordance with the requirements laid down by the Nursing Education Institution and the South African Nursing Council. The purpose of this study was to explore and describe the experiences of the students enrolled for a post-basic diploma in Medical and Surgical Nursing Science: Critical Care Nursing (General, in relation to the clinical accompaniment in a private hospital in Gauteng. An exploratory, descriptive and phenomenological research design was utilised and individual interviews were conducted with the ten students in the research hospital. A content analysis was conducted and the results revealed both positive and negative experiences by the students in the internal and external worlds. The recommendations include the formulation of standards for clinical accompaniment of students. the evaluation of the quality of clinical accompaniment of students and empowerment of the organisation, clinical accompanists/mentors and clinicians.

  8. Validation of Cross Sections with Criticality Experiment and Reaction Rates: the Neptunium Case

    CERN Document Server

    Leong, L S; Audouin, L; Berthier, B; Le Naour, C; Stéphan, C; Paradela, C; Tarrío, D; Duran, I

    2014-01-01

    The Np-237 neutron-induced fission cross section has been recently measured in a large energy range (from eV to GeV) at the n\\_TOF facility at CERN. When compared to previous measurements the n\\_TOF fission cross section appears to be higher by 5-7\\% beyond the fission threshold. To check the relevance of the n\\_TOF data, we considered a criticality experiment performed at Los Alamos with a 6 kg sphere of Np-237, surrounded by uranium highly enriched in U-235 so as to approach criticality with fast neutrons. The multiplication factor k(eff) of the calculation is in better agreement with the experiment when we replace the ENDF/B-VII. 0 evaluation of the Np-237 fission cross section by the n\\_TOF data. We also explored the hypothesis of deficiencies of the inelastic cross section in U-235 which has been invoked by some authors to explain the deviation of 750 pcm. The large modification needed to reduce the deviation seems to be incompatible with existing inelastic cross section measurements. Also we show that t...

  9. Critical care nurses' experiences of nursing mothers in an ICU after complicated childbirth.

    Science.gov (United States)

    Engström, Asa; Lindberg, Inger

    2013-09-01

    Providing nursing care for a critically ill obstetric patient or a patient who has just become a mother after a complicated birth can be a challenging experience for critical care nurses (CCNs). These patients have special needs because of the significant alterations in their physiology and anatomy together with the need to consider such specifics as breastfeeding and mother-child bonding. The aim with this study was to describe CCNs' experience of nursing the new mother and her family after a complicated childbirth. The design of the study was qualitative. Data collection was carried out through focus group discussions with 13 CCNs in three focus groups during spring 2012. The data were subjected to qualitative content analysis. The analysis resulted in the formulation of four categories: the mother and her vital functions are prioritized; not being responsible for the child and the father; an environment unsuited to the new family and collaboration with staff in neonatal and maternity delivery wards. When nursing a mother after a complicated birth the CCNs give her and her vital signs high priority. The fathers of the children or partners of the mothers are expected to take on the responsibility of caring for the newborn child and of being the link with the neonatal ward. It is suggested that education about the needs of new families for nursing care would improve the situation and have clinical implications. Whether the intensive care unit is always the best place in which to provide care for mothers and new families is debatable. © 2013 British Association of Critical Care Nurses.

  10. Critical Periods after Stroke Study: Translating animal stroke recovery experiments into a clinical trial

    Directory of Open Access Journals (Sweden)

    Alexander W Dromerick

    2015-04-01

    Full Text Available Introduction: 795,000 Americans will have a stroke this year, and half will have a chronic hemiparesis. Substantial animal literature suggests that the mammalian brain has much potential to recover from acute injury using mechanisms of neuroplasticity, and that these mechanisms can be accessed using training paradigms and neurotransmitter manipulation. However, most of these findings have not been tested or confirmed in the rehabilitation setting, in large part because of the challenges in translating a conceptually straightforward laboratory experiment into a meaningful and rigorous clinical trial in humans. Through presentation of methods for a Phase II trial, we discuss these issues and describe our approach. Methods: In rodents there is compelling evidence for timing effects in rehabilitation; motor training delivered at certain times after stroke may be more effective than the same training delivered earlier or later, suggesting that there is a critical or sensitive period for strongest rehabilitation training effects. If analogous critical/sensitive periods can be identified after human stroke, then existing clinical resources can be better utilized to promote recovery. The Critical Periods after Stroke Study (CPASS is a phase II randomized, controlled trial designed to explore whether such a sensitive period exists. We will randomize 64 persons to receive an additional 20 hours of upper extremity therapy either immediately upon rehab admission, 2-3 months after stroke onset, 6 months after onset, or to an observation-only control group. The primary outcome measure will be the Action Research Arm Test at one year. Blood will be drawn at up to 3 time points for later biomarker studies. Conclusion: CPASS is an example of the translation of rodent motor recovery experiments into the clinical setting; data obtained from this single site randomized controlled trial will be used to finalize the design of a Phase III trial.

  11. Thermal conductivity of hexagonal Si and hexagonal Si nanowires from first-principles

    Science.gov (United States)

    Raya-Moreno, Martí; Aramberri, Hugo; Seijas-Bellido, Juan Antonio; Cartoixà, Xavier; Rurali, Riccardo

    2017-07-01

    We calculate the thermal conductivity, κ, of the recently synthesized hexagonal diamond (lonsdaleite) Si using first-principles calculations and solving the Boltzmann Transport Equation. We find values of κ which are around 40% lower than in the common cubic diamond polytype of Si. The trend is similar for [111] Si nanowires, with reductions of the thermal conductivity that are even larger than in the bulk in some diameter range. The Raman active modes are identified, and the role of mid-frequency optical phonons that arise as a consequence of the reduced symmetry of the hexagonal lattice is discussed. We also show briefly that popular classic potentials used in molecular dynamics might not be suited to describe hexagonal polytypes, discussing the case of the Tersoff potential.

  12. Experiences of fathering a baby admitted to neonatal intensive care: a critical gender analysis.

    Science.gov (United States)

    Deeney, Kathleen; Lohan, Maria; Spence, Dale; Parkes, Jackie

    2012-09-01

    More fathers than ever before attend at the birth of their child and, internationally, there is a palpable pressure on maternity and neonatal services to include and engage with fathers. It is, thus, more important than ever to understand how fathers experience reproductive and neonatal health services and to understand how fathers can be successfully accommodated in these environments alongside their partners. In this paper we advance a theoretical framework for re-thinking fatherhood and health services approaches to fatherhood based on Critical Studies on Men (CSM). We illustrate the importance of this feminist informed theoretical approach to understanding the gendered experiences of fathers in a Neonatal Intensive Care Unit (NICU) setting in Northern Ireland. Using a longitudinal follow-up research design, with two data collection points, a total of 39 in-depth semi-structured interviews was conducted with 21 fathers of infants admitted to the NICU between August 2008 and December 2009. The findings demonstrate: (i) how men are forging new gendered identities around the birth of their baby but, over time, acknowledge women as the primary caregivers; (ii) how social class is a key determinant of men's ability to enact hegemonic forms of 'involved fatherhood' in the NICU, and; (iii) how men also encounter resistance from their partners and health professionals in challenging a gender order which associates women with the competent care of infants. An understanding of these gendered experiences operating at both individual and structural levels is critical to leading change for the inclusion of fathers as equal parents in healthcare settings. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Criticality experiments and benchmarks for cross section evaluation: the neptunium case

    Directory of Open Access Journals (Sweden)

    Duran I.

    2013-03-01

    Full Text Available The 237Np neutron-induced fission cross section has been recently measured in a large energy range (from eV to GeV at the n_TOF facility at CERN. When compared to previous measurement the n_TOF fission cross section appears to be higher by 5-7% beyond the fission threshold. To check the relevance of n_TOF data, we apply a criticality experiment performed at Los Alamos with a 6 kg sphere of 237Np, surrounded by enriched uranium 235U so as to approach criticality with fast neutrons. The multiplication factor ke f f of the calculation is in better agreement with the experiment (the deviation of 750 pcm is reduced to 250 pcm when we replace the ENDF/B-VII.0 evaluation of the 237Np fission cross section by the n_TOF data. We also explore the hypothesis of deficiencies of the inelastic cross section in 235U which has been invoked by some authors to explain the deviation of 750 pcm. With compare to inelastic large distortion calculation, it is incompatible with existing measurements. Also we show that the v of 237Np can hardly be incriminated because of the high accuracy of the existing data. Fission rate ratios or averaged fission cross sections measured in several fast neutron fields seem to give contradictory results on the validation of the 237Np cross section but at least one of the benchmark experiments, where the active deposits have been well calibrated for the number of atoms, favors the n_TOF data set. These outcomes support the hypothesis of a higher fission cross section of 237Np.

  14. A Course in Critical Thinking for PhD Students in Biomolecular Sciences and Biotechnology: Classical Experiments in Biochemistry

    National Research Council Canada - National Science Library

    Carlos B Hirschberg

    2016-01-01

      This essay presents and discusses an eight-session seminar course designed to develop critical thinking skills in doctoral biochemistry students by exposing them to classical experiments in biochemistry. During each...

  15. The Relationship between College Experience at a Historically Black College and Students' Critical Thinking Skills

    Science.gov (United States)

    Little, Irene Pruitt

    2017-01-01

    The purpose of this quantitative correlational study was to examine the relationship between college experience at a HBCU and students' critical thinking skills. The theoretical framework included Astin's theory of involvement and Facione's taxonomy of critical thinking. The research site was a private four-year HBCU in the state of Alabama. The…

  16. TNF-A Levels throughout the Critical Period for Experience-Dependent Plasticity in the Rat Primary Auditory Cortex

    NARCIS (Netherlands)

    Man, WH; Madeira, Caroline; Zhou, Xiaoming; Merzenich, Michael M; Panizzutti, Rogerio

    2015-01-01

    Tumor necrosis factor- alpha (TNF-α) is likely to play a role in brain plasticity. To determine whether TNF-α levels change throughout a critical period of experience-dependent brain plasticity, we assessed these levels in the primary auditory cortex of rats before, during and after the critical

  17. A journey from nuclear criticality methods to high energy density radflow experiments

    Energy Technology Data Exchange (ETDEWEB)

    Urbatsch, Todd James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-11-08

    Los Alamos National Laboratory is a nuclear weapons laboratory supporting our nation's defense. In support of this mission is a high energy-density physics program in which we design and execute experiments to study radiationhydrodynamics phenomena and improve the predictive capability of our largescale multi-physics software codes on our big-iron computers. The Radflow project’s main experimental effort now is to understand why we haven't been able to predict opacities on Sandia National Laboratory's Z-machine. We are modeling an increasing fraction of the Z-machine's dynamic hohlraum to find multi-physics explanations for the experimental results. Further, we are building an entirely different opacity platform on Lawrence Livermore National Laboratory's National Ignition Facility (NIF), which is set to get results early 2017. Will the results match our predictions, match the Z-machine, or give us something entirely different? The new platform brings new challenges such as designing hohlraums and spectrometers. The speaker will recount his history, starting with one-dimensional Monte Carlo nuclear criticality methods in graduate school, radiative transfer methods research and software development for his first 16 years at LANL, and, now, radflow technology and experiments. Who knew that the real world was more than just radiation transport? Experiments aren't easy and they are as saturated with politics as a presidential election, but they sure are fun.

  18. A journey from nuclear criticality methods to high energy density radflow experiments

    Energy Technology Data Exchange (ETDEWEB)

    Urbatsch, Todd James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-05-30

    Los Alamos National Laboratory is a nuclear weapons laboratory supporting our nation's defense. In support of this mission is a high energy-density physics program in which we design and execute experiments to study radiationhydrodynamics phenomena and improve the predictive capability of our largescale multi-physics software codes on our big-iron computers. The Radflow project’s main experimental effort now is to understand why we haven't been able to predict opacities on Sandia National Laboratory's Z-machine. We are modeling an increasing fraction of the Z-machine's dynamic hohlraum to find multi-physics explanations for the experimental results. Further, we are building an entirely different opacity platform on Lawrence Livermore National Laboratory's National Ignition Facility (NIF), which is set to get results early 2017. Will the results match our predictions, match the Z-machine, or give us something entirely different? The new platform brings new challenges such as designing hohlraums and spectrometers. The speaker will recount his history, starting with one-dimensional Monte Carlo nuclear criticality methods in graduate school, radiative transfer methods research and software development for his first 16 years at LANL, and, now, radflow technology and experiments. Who knew that the real world was more than just radiation transport? Experiments aren't easy, but they sure are fun.

  19. The undergraduate premedical experience in the United States: a critical review

    Science.gov (United States)

    Parnami, Sonali; Fuhrel-Forbis, Andrea; Anspach, Renee R.; Crawford, Brett; De Vries, Raymond G.

    2013-01-01

    Objectives To better understand the consequences of the premedical years for the character of (future) physicians by critically reviewing the empirical research done on the undergraduate premedical experience in the United States. Methods We searched ERIC, JSTOR, PubMed, Scopus, ISI Web of Science, and PsycINFO from the earliest available date for empirical, peer-reviewed studies of premedical students in the United States. We then used qualitative methods to uncover overall themes present in this literature. Results The initial literature search identified 1,168 articles, 19 of which were included for review. Reviewed articles were published between 1976 and 2010 with the majority published prior to 1990. Articles covered two broad topics: explaining attrition from the premedical track, and investigating the personality traits and stereotypes of premedical students. Self-selection bias and high attrition rates were among the limitations of the reviewed articles. Conclusions There is very little current research on the premedical experience. Given the importance of the pre-medical years on the process of becoming a medical professional, it is imperative that we do more and better research on how the premedical experience shapes future physicians. PMID:23951400

  20. The undergraduate premedical experience in the United States: a critical review.

    Science.gov (United States)

    Lin, Katherine Y; Parnami, Sonali; Fuhrel-Forbis, Andrea; Anspach, Renee R; Crawford, Brett; De Vries, Raymond G

    2013-01-01

    To better understand the consequences of the premedical years for the character of (future) physicians by critically reviewing the empirical research done on the undergraduate premedical experience in the United States. We searched ERIC, JSTOR, PubMed, Scopus, ISI Web of Science, and PsycINFO from the earliest available date for empirical, peer-reviewed studies of premedical students in the United States. We then used qualitative methods to uncover overall themes present in this literature. The initial literature search identified 1,168 articles, 19 of which were included for review. Reviewed articles were published between 1976 and 2010 with the majority published prior to 1990. Articles covered two broad topics: explaining attrition from the premedical track, and investigating the personality traits and stereotypes of premedical students. Self-selection bias and high attrition rates were among the limitations of the reviewed articles. There is very little current research on the premedical experience. Given the importance of the premedical years on the process of becoming a medical professional, it is imperative that we do more and better research on how the premedical experience shapes future physicians.

  1. Critical Ionization Velocity (CIV) experiment XANI onboard the INTERCOSMOS 24 - ``ACTIVE'' satellite

    Science.gov (United States)

    Bankov, L.; Gousheva, M.; Lefterov, A.; Binev, G.; Vassileva, A.; Potanin, Yu.; Dubinin, E.

    1993-10-01

    Satellite INTERCOSMOS-24 ``ACTIVE'' was launched on September 30 1989, with an initial apogee 2500 km, perigee 530 km and an orbital inclination of 82.2°. Under ``ACTIVE'' project, a wide number of plasma diagnostics instruments were especially designed to study the ionospheric response to high power VLF transmitter emissions, by means of satellite-subsatellite system during this mission. As a separate part of this project, a Critical Ionization Velocity (CIV) experiment called XANI (Xenon ANomalous Ionization) had been carried out to study neutral gas/plasma interaction processes in the ionosphere using neutral Xe gas injection. Seven Xe gas release experiments had been realized at daytime high latitude ionosphere. In this paper an Ion Drift Meter (IDM) and Retarding Potential Analyzer (RPA) data concerning transverse ion drift velocity vector measurements and total ion density variations during gas release experiment are shown. Two examples of the RPA data, taken after the beginning of Xe injection, show some prompt ionization at the ionization front about 30% in comparison with the background ion concentration. Horizontal ion drift of few hundred meters per second, transversal to the satellite velocity vector, had been observed at the ionization front.

  2. Star of Lima - Overview and optical diagnostics of a barium Alfven critical velocity experiment

    Science.gov (United States)

    Wescott, E. M.; Stenbaek-Nielsen, H. C.; Hallinan, T.; Foeppl, H.; Valenzuela, A.

    1986-01-01

    The Alfven critical velocity mechanism for ionization of a neutral gas streaming across the magnetic field has been demonstrated in laboratory experiments. In March 1983, two rocket-borne experiments with Ba and Sr tested the effect in the wall-less laboratory of space from Punto Lobos, Peru, near 430 km altitude. 'Star of Lima' used a conical Ba shaped charge aimed at an instrument payload about 2 km away. Because of rocket overperformance the detonation occurred in partial sunlight, so that less than 21.6 percent of the ionizing UV was present. Particle and field measurements indicate the production of hot electrons and waves in the energy and frequency range that are respectively predicted to produce a cascade of ionization by the Alfven mechanism. However, the ionization fluxes and wave energy density did not reach cascade levels, and optical observations indicate that only 2.5 to 5 x 10 to the 20th Ba ions were produced. A substantial portion and perhaps all of the ionization could have been produced by solar UV. The failure of the Alfven process in this experiment is not well understood.

  3. Wargaming in Both Rectilinear and Hexagonal Spaces

    Science.gov (United States)

    Hoover, Alex

    2012-01-01

    There are two main approaches to managing wargame entity interactions (movement, line of sight, area of effect, etc) freespace and gridded In the freespace approach, the units exist as entities in a continuous volume of (usually) Cartesian 3D space. They move in any direction (based on interaction with "terrain" that occupies the same space) and interact with each other based on references and displacements from their position in that space. In the gridded approach, space is broken up into (usually regular) shaped pieces. Units are considered to occupy the entire volume of one of these pieces, movement, line of sight, and other interactions are based on the relationships among the spaces rather than the absolute positions of the units themselves. Both approaches have advantages and drawbacks. The general issue that this discussion has addressed is that there is no "perfect" approach to implementing a wargaming battlespace. Each of them (and this extends to others not discussed) has different sets of advantages and disadvantages. Nothing will change that basic nature of the various approaches, nor would it be desirable to do so. Along with the advantages, the challenges define the feel of the game and focus the thinking of the players on certain aspects and away from others. The proposed approach to combining square and hexagonal approaches, which we will call the rhombus interface, leverages rhombuses constructed from equilateral triangles into which the hexagon can be decomposed to bridge the gap between the approaches, maintain relative consistency between the two as much as possible, and provide most of the feel of the hexagonal approach.

  4. Method for exfoliation of hexagonal boron nitride

    Science.gov (United States)

    Lin, Yi (Inventor); Connell, John W. (Inventor)

    2012-01-01

    A new method is disclosed for the exfoliation of hexagonal boron nitride into mono- and few-layered nanosheets (or nanoplatelets, nanomesh, nanoribbons). The method does not necessarily require high temperature or vacuum, but uses commercially available h-BN powders (or those derived from these materials, bulk crystals) and only requires wet chemical processing. The method is facile, cost efficient, and scalable. The resultant exfoliated h-BN is dispersible in an organic solvent or water thus amenable for solution processing for unique microelectronic or composite applications.

  5. Analysis of experiments in the Phase III GCFR benchmark critical assembly

    Energy Technology Data Exchange (ETDEWEB)

    Hess, A.L.; Baylor, K.J.

    1980-04-01

    Experiments carried out in the third gas-cooled fast breeder reactor (GCFR) benchmark critical assembly on the Zero Power Reactor-9 at Argonne National Laboratory were analyzed using methods and computer codes employed routinely for design and performance evaluations on power-plant GCFR cores. The program for the Phase III GCFR assembly, with a 1900-liter, three-enrichment zone core, included measurements of reaction-rate profiles in a typical power-flattened design, studies of material reactivity coefficients, reaction ratio and breeding parameter determinations, and comparison of pin with plate fuel loadings. Calculated parameters to compare with all of the measured results were obtained using 10-group cross sections based on ENDF/B-4 and two-dimensional diffusion theory, with adjustments for fuel-cell heterogeneity and void-lattice streaming effects.

  6. Near-critical density target experiments for ion acceleration using high-intensity laser pulses

    Science.gov (United States)

    Kordell, Peter; Campbell, Paul; Maksimchuk, Anatoly; Willingale, Louise; Krushelnick, Karl

    2017-10-01

    The interaction of a short-duration, relativistic intensity laser pulse with a near-critical density plasma can produce a collisionless electrostatic shock capable of accelerating ions. This effect has already been demonstrated using CO2 laser systems (λ = 10 μm) where the specific plasma density profile enabled the acceleration of quasi-monoenergetic ion beams. We will present our experiments using the T-cubed laser system at the University of Michigan (λ = 1.053 μm , 6J, 400fs). Due to the shorter wavelength, typical of most relativistic intensity laser systems, a higher plasma density and shorter scalelengths are required to achieve the conditions for shock ion acceleration. The target design and characterization as well as preliminary experimental results will be presented. This work was supported by the DOE through Grant Number DE-SC0012327.

  7. Analyzing the thermionic reactor critical experiments. [thermal spectrum of uranium 235 core

    Science.gov (United States)

    Niederauer, G. F.

    1973-01-01

    The Thermionic Reactor Critical Experiments (TRCE) consisted of fast spectrum highly enriched U-235 cores reflected by different thicknesses of beryllium or beryllium oxide with a transition zone of stainless steel between the core and reflector. The mixed fast-thermal spectrum at the core reflector interface region poses a difficult neutron transport calculation. Calculations of TRCE using ENDF/B fast spectrum data and GATHER library thermal spectrum data agreed within about 1 percent for the multiplication factor and within 6 to 8 percent for the power peaks. Use of GAM library fast spectrum data yielded larger deviations. The results were obtained from DOT R Theta calculations with leakage cross sections, by region and by group, extracted from DOT RZ calculations. Delineation of the power peaks required extraordinarily fine mesh size at the core reflector interface.

  8. Impediments to User Gains: Experiences from a Critical Participatory Design Project

    DEFF Research Database (Denmark)

    Bossen, Claus; Dindler, Christian; Iversen, Ole Sejer

    2012-01-01

    Actual studies of user gains from involvement in design processes are few, although a concern for users’ gains is a core characteristic of participatory design (PD). We explore the question of user gains through a retrospective evaluation of a critical PD project. We conducted ten qualitative int...... prominent in the research study. Based on these findings, we provide an analysis of impediments for users gains in PD projects: Differences between aims were unresolved, absence of a shared set-up for collaboration and different conceptions of technology.......Actual studies of user gains from involvement in design processes are few, although a concern for users’ gains is a core characteristic of participatory design (PD). We explore the question of user gains through a retrospective evaluation of a critical PD project. We conducted ten qualitative...... interviews with participants in a project aimed at developing technology that fosters engaging museum experiences, and rethinking cultural heritage communication. Despite the use of established PD techniques by experienced PD practitioners, a significant number of frustrations relating to the PD process were...

  9. Optical observations on the CRIT-II Critical Ionization Velocity Experiment

    Science.gov (United States)

    Stenbaek-Nielsen, H. C.; Wescott, E. M.; Haerendel, G.; Valenzuela, A.

    1990-01-01

    A rocket borne Critical Ionization Velocity (CIV0 experiment was carried out from Wallops Island at dusk on May 4, 1989. Two barium shaped charges were released below the solar terminator (to prevent photoionization) at altitudes near 400 km. The ambient ionospheric electron density was 50,000/cu cm. The neutral barium jet was directed upward and at an angle of nominally 45 degrees to B which gives approximately 3 x 10 to the 23rd neutrals with super critical velocity. Ions created by a CIV process in the region of the neutral jet would travel up along B into sunlight where they can be detected optically. Well defined ion clouds (max. brightness 750 R) were observed in both releases. An ionization rate of 0.8 percent/sec (125 sec ionization time constant) can account for the observed ion cloud near the release field line, but the ionization rate falls off with increasing distance from the release. It is concluded that a CIV process was present in the neutral jet out to about 50 km from the release, which is significantly further than allowed by current theories.

  10. Validation of VHTRC calculation benchmark of critical experiment using the MCB code

    Directory of Open Access Journals (Sweden)

    Stanisz Przemysław

    2016-01-01

    Full Text Available The calculation benchmark problem Very High Temperature Reactor Critical (VHTR a pin-in-block type core critical assembly has been investigated with the Monte Carlo Burnup (MCB code in order to validate the latest version of Nuclear Data Library based on ENDF format. Executed benchmark has been made on the basis of VHTR benchmark available from the International Handbook of Evaluated Reactor Physics Benchmark Experiments. This benchmark is useful for verifying the discrepancies in keff values between various libraries and experimental values. This allows to improve accuracy of the neutron transport calculations that may help in designing the high performance commercial VHTRs. Almost all safety parameters depend on the accuracy of neutron transport calculation results that, in turn depend on the accuracy of nuclear data libraries. Thus, evaluation of the libraries applicability to VHTR modelling is one of the important subjects. We compared the numerical experiment results with experimental measurements using two versions of available nuclear data (ENDF-B-VII.1 and JEFF-3.2 prepared for required temperatures. Calculations have been performed with the MCB code which allows to obtain very precise representation of complex VHTR geometry, including the double heterogeneity of a fuel element. In this paper, together with impact of nuclear data, we discuss also the impact of different lattice modelling inside the fuel pins. The discrepancies of keff have been successfully observed and show good agreement with each other and with the experimental data within the 1 σ range of the experimental uncertainty. Because some propagated discrepancies observed, we proposed appropriate corrections in experimental constants which can improve the reactivity coefficient dependency. Obtained results confirm the accuracy of the new Nuclear Data Libraries.

  11. Critical Race Media Projects: Counterstories and Praxis (Re)Claim Chicana/o Experiences

    Science.gov (United States)

    Alemán, Sonya M.; Alemán, Enrique, Jr.

    2016-01-01

    This article maps out two critical race media projects -- a documentary and a Chicana/o-centric student newspaper--developed by Chicana/o scholars seeking to fulfilll the promise of praxis hailed by critical race theorists. Fortified and guided by the quintessential tenets of critical race theory and Latino critical race theory, these critical…

  12. Inserting Stress Analysis of Combined Hexagonal Aluminum Honeycombs

    OpenAIRE

    Xiangcheng Li; Kang Li; Yuliang Lin; Rong Chen; Fangyun Lu

    2016-01-01

    Two kinds of hexagonal aluminum honeycombs are tested to study their out-of-plane crushing behavior. In the tests, honeycomb samples, including single hexagonal aluminum honeycomb (SHAH) samples and two stack-up combined hexagonal aluminum honeycombs (CHAH) samples, are compressed at a fixed quasistatic loading rate. The results show that the inserting process of CHAH can erase the initial peak stress that occurred in SHAH. Meanwhile, energy-absorbing property of combined honeycomb samples is...

  13. Nanocrystalline hexagonal diamond formed from glassy carbon

    Science.gov (United States)

    Shiell, Thomas. B.; McCulloch, Dougal G.; Bradby, Jodie E.; Haberl, Bianca; Boehler, Reinhard; McKenzie, David. R.

    2016-11-01

    Carbon exhibits a large number of allotropes and its phase behaviour is still subject to significant uncertainty and intensive research. The hexagonal form of diamond, also known as lonsdaleite, was discovered in the Canyon Diablo meteorite where its formation was attributed to the extreme conditions experienced during the impact. However, it has recently been claimed that lonsdaleite does not exist as a well-defined material but is instead defective cubic diamond formed under high pressure and high temperature conditions. Here we report the synthesis of almost pure lonsdaleite in a diamond anvil cell at 100 GPa and 400 °C. The nanocrystalline material was recovered at ambient and analysed using diffraction and high resolution electron microscopy. We propose that the transformation is the result of intense radial plastic flow under compression in the diamond anvil cell, which lowers the energy barrier by “locking in” favourable stackings of graphene sheets. This strain induced transformation of the graphitic planes of the precursor to hexagonal diamond is supported by first principles calculations of transformation pathways and explains why the new phase is found in an annular region. Our findings establish that high purity lonsdaleite is readily formed under strain and hence does not require meteoritic impacts.

  14. Thermoelectric properties of hexagonal graphene quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yonghong, E-mail: yhyan@fudan.edu.cn [Department of Physics, Shaoxing University, Shaoxing 312000 (China); Liang, Qi-Feng [Department of Physics, Shaoxing University, Shaoxing 312000 (China); Zhao, Hui [Department of Physics, Tongji University, Shanghai 200092 (China); Wu, Chang-Qin [Department of Physics, Fudan University, Shanghai 200433 (China)

    2012-02-27

    By using the atomistic nonequilibrium Green's function method, we investigate the thermoelectric properties of graphene nanoribbons in the presence of two constrictions (or hexagonal graphene quantum dots). With decreasing widths of the constrictions, the thermal conductance of the nanoribbon can be reduced largely while S{sup 2}G{sub e} (S is the Seebeck coefficient and G{sub e} is the electronic conductance) remains still high as compared with the results of the pristine nanoribbon. Thus, the thermoelectric figure of merit ZT can be enhanced largely. In fact, in the presence of narrowest constrictions the ZT values of the zigzag quantum dots can exceed one at room temperature, while the ZT values of the armchair quantum dots may be close to one, depending on the size of the dot. -- Highlights: ► We study thermoelectric properties of hexagonal graphene quantum dots. ► By point contacts to two leads, the thermal conductance can be reduced greatly while keeping the power factor still high. ► Thermoelectric figure of merit (ZT) can exceed unity.

  15. Creating an Alternate Reality: Critical, Creative, and Empathic Thinking Generated in the "Global Village Playground" Capstone Experience

    Science.gov (United States)

    Dondlinger, Mary Jo; Wilson, Douglas A.

    2012-01-01

    The "Global Village Playground" ("GVP") was a capstone learning experience designed to address institutional assessment needs while providing an integrated and authentic learning experience for students aimed at fostering critical and creative thinking. In the "GVP", students work on simulated and real-world problems as a design team tasked with…

  16. Critical Experiments that Simulated Damp MOX Powders - Do They Meet the Need?

    Energy Technology Data Exchange (ETDEWEB)

    J. Blair Briggs; Dr. Ali Nouri; Dr. Claes Nordborg

    2005-09-01

    The OECD Nuclear Energy Agency (NEA) Working Party on Nuclear Criticality Safety (WPNCS) identified the MOX fuel manufacturing process as an area in which there is a need for additional integral benchmark data. The specific need focused on damp MOX powders. The WPNCS was ultimately asked by the NEA Nuclear Science Committee (NSC) to provide the framework for the selection and performance of new experiments that fill the identified need. A set of criteria was established to enable uniform comparison of experimental proposals with generic MOX application data. Criteria were established for five general characteristics: (1) neutronic parameters, (2) type of experiments, (3) financial aspects, (4) schedule, and (5) other considerations. Proposals were judged most importantly on their ability to match the neutronic parameters of predetermined MOX applications. The neutronic parameters that formed the basis for comparison included core average values (not local values) for flux, fission and capture rate; detailed balance data (fission and capture) for the main isotopes (Actinides, H and O); sensitivity coefficients to important nuclear reactions (fission, capture, elastic and inelastic scatter, nu-bar, mu-bar) for all uranium and plutonium isotopes, hydrogen, and oxygen; sensitivity profiles to the main nuclear reactions for uranium and plutonium isotopes; energy of average lethargy causing fission; and the average fission group energy. The focus of this paper is on the definition of the need; the neutronics criteria established to assess which, if any, of three proposed MOX experimental programs best meet the need; and the actual assessment of the proposed experimental programs.

  17. Comparison of self-assessed competence and experience among critical care nurses.

    Science.gov (United States)

    O'Leary, Jerry

    2012-07-01

    To determine the level of self-assessed nursing competence and the relationship to age and experience in nursing. Nursing competence is a concern for all health-care stakeholders. Methods to measure competence have been evaluated worldwide. There is little agreement about the development or reliable measure of competence. Exploring these relationships can identify strategies for education, retention, professional growth and potentially affect patient outcome measures. The Nurse Competence Scale (NCS) was completed by 101 critical care nurses. Statistical methods were used to analyse the data. The nurses self-assessed level of competence ranged from good to excellent along with an increased frequency of using competencies. Statistically significant relationships were found among the variables. Measurable, significant relationships exist among the variables. The NCS proved to be a valid and reliable instrument to measure competence. Objective and reliable assessment of nursing competence is an important measure for leadership and education. Further studies to identify other factors affecting the nurses' experience and the effect on competence will help to develop and promote supportive strategies. © 2012 Blackwell Publishing Ltd.

  18. Clinical Experiences and Mediational Activities in Urban Teacher Preparation: Learning and Critical Consciousness

    Directory of Open Access Journals (Sweden)

    Craig Willey

    2016-11-01

    Full Text Available In a longitudinal design experiment conducted within an urban teacher preparation program, we employed ethnographic and auto-ethnographic methods to investigate the following questions: 1 In what ways do clinical experiences (CEs support prospective teachers’ (PTs development of knowledge, skills, and dispositions necessary for urban teaching? 2 How is it determined that adjustments need to be made to the design and facilitation of CEs, and what did these adjustments yield in terms of student learning outcomes? The program centers and leverages CEs in order for PTs to connect theory and practice, particularly an awareness of, and skills associated with, equitable teaching practices. In our two-year field-based program, CEs included community explorations, one-on-one and small group work with children, two student teaching practicums, and various school-community events. We describe the process undertaken to maximize the benefits yielded from CEs. After working with three cohorts of PTs for their entire professional training, we found that: 1 focusing attention on the intentional design and assessment of the mediational activities coupled with CEs leads to more nuanced understandings and enactments of culturally relevant teaching among PTs; and 2 CEs afford PTs abundant opportunities to shape complex identities as urban teachers. Specifically, we found that clinical experiences and corresponding mediational activities support PTs’ understanding of families of color, allow them to recognize and address problematic schooling practices, and strengthen PTs’ otherwise fragile critical consciousness. We conclude that strategic interventions can provide clarity for PTs around what has been learned, and what is left to be developed

  19. Jordanian survivors' experiences of recovery from critical illness: a qualitative study.

    Science.gov (United States)

    Abdalrahim, M S; Zeilani, R S

    2014-12-01

    Despite the fact that a lot of patients consider their discharge from hospitals as a positive sign of progress towards regained health, many of them start suffering from physical, psychological and social problems after discharge from intensive care units. This study aims to describe the experiences of Jordanian survivors of critical illnesses 3 months after discharge from a hospital intensive care unit. A descriptive qualitative approach was used to involve 18 Jordanian patients from two hospitals in a major Jordanian city using open-ended interviews. Interview transcripts were analysed using content analysis method. Three main themes have emerged from the data: (1) new meaning of life; (2) different perspectives on the meaning of life, and (3) struggle for role identity. The sample was chosen from one city in Jordan; longitudinal study might help identify the change in patients' experiences over time. Patients described the discharge from the intensive care unit as a means of rescue from death; they began to value their spiritual and religious rituals. Negative traumatic experiences hindered the patients' recovery process. During recovery, patients struggled to resume their power and role in family. This study emphasizes the importance of providing care according to the patient's individual needs, related to their cultural and spiritual milieu; there is a need to develop follow-up services for ICU survivors within a national health policy. Further educational and training programmes in the patient's issues after discharge from hospital are needed. This will definitely help nurses care after this patient group. © 2014 International Council of Nurses.

  20. A validation study of existing neutronics tools against ZPPR-21 and ZPPR-15 critical experiments.

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W.S.; Kim, S.J. (Nuclear Engineering Division)

    2007-09-30

    A study was performed to validate the existing tools for fast reactor neutronics analysis against previous critical experiments. The six benchmark problems for the ZPPR-21 critical experiments phases A through F specified in the Handbook of Evaluated Criticality Safety Benchmark Experiments were analyzed. Analysis was also performed for three loading configurations of the ZPPR-15 Phase A experiments. As-built core models were developed in XYZ geometries using the reactor loading records and drawer master information. Detailed Monte Carlo and deterministic transport calculations were performed, along with various modeling sensitivity analyses. The Monte Carlo simulations were carried out with the VIM code with continuous energy cross sections based on the ENDF/B-V.2 data. For deterministic calculations, region-dependent 230-group cross sections were generated using the ETOE-2/MC-2/SDX code system, again based on the ENDF/B-V.2 data. Plate heterogeneity effects were taken into account by SDX unit cell calculations. Core calculations were performed with the TWODANT discrete ordinate code for the ZPPR-21 benchmarks, and with the DIF3D nodal transport option for the ZPPR-15 experiments. For all six ZPPR-21 configurations where the Pu-239 concentration varies from 0 to 49 w/o and the U-235 concentration accordingly varies from 62 to 0 w/o, the core multiplication factor determined with a 230-group TWODANT calculation agreed with the VIM Monte Carlo solution within 0.20 %{Delta}k, and there was no indication of any systematic bias. The quality of principal cross sections generated with the MC-2 code was comparable to that of VIM cross sections. The overall reactivity effect due to the errors in the 230-group principal cross sections was estimated to be less than 0.05 %{Delta}k. The statistics of the differences between calculated values and specified benchmark experimental values showed similar bias (from -0.28 %{Delta}k to 0.33 %{Delta}k) for MC{sup 2}-2/TWODANT and VIM

  1. Sedation in palliative care – a critical analysis of 7 years experience

    Directory of Open Access Journals (Sweden)

    Andres Inge

    2003-05-01

    Full Text Available Abstract Background The administration of sedatives in terminally ill patients becomes an increasingly feasible medical option in end-of-life care. However, sedation for intractable distress has raised considerable medical and ethical concerns. In our study we provide a critical analysis of seven years experience with the application of sedation in the final phase of life in our palliative care unit. Methods Medical records of 548 patients, who died in the Palliative Care Unit of GK Havelhoehe between 1995–2002, were retrospectively analysed with regard to sedation in the last 48 hrs of life. The parameters of investigation included indication, choice and kind of sedation, prevalence of intolerable symptoms, patients' requests for sedation, state of consciousness and communication abilities during sedation. Critical evaluation included a comparison of the period between 1995–1999 and 2000–2002. Results 14.6% (n = 80 of the patients in palliative care had sedation given by the intravenous route in the last 48 hrs of their life according to internal guidelines. The annual frequency to apply sedation increased continuously from 7% in 1995 to 19% in 2002. Main indications shifted from refractory control of physical symptoms (dyspnoea, gastrointestinal, pain, bleeding and agitated delirium to more psychological distress (panic-stricken fear, severe depression, refractory insomnia and other forms of affective decompensation. Patients' and relatives' requests for sedation in the final phase were significantly more frequent during the period 2000–2002. Conclusion Sedation in the terminal or final phase of life plays an increasing role in the management of intractable physical and psychological distress. Ethical concerns are raised by patients' requests and needs on the one hand, and the physicians' self-understanding on the other hand. Hence, ethically acceptable criteria and guidelines for the decision making are needed with special regard to

  2. instabilité interfaciale d'une couche de ferrofluide sous champ magnétique normal; étude de la transition hexagones - carrés

    OpenAIRE

    Abou, Bérengère

    1998-01-01

    Ferrofluids are colloidal suspensions of monodomain magnetic particles, with an average size of 100 Angstromsin a non-magnetic carrier fluid. When a ferrofluid layer is submitted to a uniform and vertically oriented magnetic field, an interfacial instability emerges in the form of a hexagonal pattern of peaks above a critical value of the magnetic field. On increasing the magnetic field, we observe a smooth transition from the hexagonal pattern to a square pattern, above a second threshold. I...

  3. A Course in Critical Thinking for PhD Students in Biomolecular Sciences and Biotechnology: Classical Experiments in Biochemistry

    OpenAIRE

    Hirschberg, Carlos B.

    2016-01-01

    This essay presents and discusses an eight-session seminar course designed to develop critical thinking skills in doctoral biochemistry students by exposing them to classical experiments in biochemistry. During each 2.5 session, different key topics of the discovery and development of biochemical concepts are discussed. Before each session, students are required to read the one or two classical papers. The size of the seminar course and the seating of the students are critical to make this a ...

  4. Combinatorics of giant hexagonal bilayer hemoglobins.

    Science.gov (United States)

    Hanin, L G; Vinogradov, S N

    2000-01-01

    The paper discusses combinatorial and probabilistic models allowing to characterize various aspects of spacial symmetry and structural heterogeneity of the giant hexagonal bilayer hemoglobins (HBL Hb). Linker-dodecamer configurations of HBL are described for two and four linker types (occurring in the two most studied HBL Hb of Arenicola and Lumbricus, respectively), and the most probable configurations are found. It is shown that, for HBL with marked dodecamers, the number of 'normal-marked' pairs of dodecamers in homological position follows a binomial distribution. The group of symmetries of the dodecamer substructure of HBL is identified with the dihedral group D6. Under natural symmetry assumptions, the total dipole moment of the dodecamer substructure of HBL is shown to be zero. Biological implications of the mathematical findings are discussed.

  5. Structure of grain boundaries in hexagonal materials

    CERN Document Server

    Sarrazit, F

    1998-01-01

    which allows the behaviour of line-defects to be studied in complex interfacial processes. The work presented in this thesis describes experimental and theoretical aspects associated with the structure of grain boundaries in hexagonal materials. It has been found useful to classify grain boundaries as low-angle, special or general on the basis of their structure. High-angle grain boundaries were investigated in tungsten carbide (WC) using conventional electron microscopy techniques, and three examples characteristic of the interfaces observed in this material were studied extensively. Three-dimensionally periodic patterns are proposed as plausible reference configurations, and the Burgers vectors of observed interfacial dislocations were predicted using a theory developed recently. The comparison of experimental observations with theoretical predictions proved to be difficult as contrast simulation techniques require further development for analysis to be completed confidently. Another part of this work invol...

  6. Analysis of the impact of correlated benchmark experiments on the validation of codes for criticality safety analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bock, M.; Stuke, M.; Behler, M. [Gesellschaft fuer Anlagen- und Reaktorsicherheit mbH (GRS), Garching (Germany)

    2013-07-01

    The validation of a code for criticality safety analysis requires the recalculation of benchmark experiments. The selected benchmark experiments are chosen such that they have properties similar to the application case that has to be assessed. A common source of benchmark experiments is the 'International Handbook of Evaluated Criticality Safety Benchmark Experiments' (ICSBEP Handbook) compiled by the 'International Criticality Safety Benchmark Evaluation Project' (ICSBEP). In order to take full advantage of the information provided by the individual benchmark descriptions for the application case, the recommended procedure is to perform an uncertainty analysis. The latter is based on the uncertainties of experimental results included in most of the benchmark descriptions. They can be performed by means of the Monte Carlo sampling technique. The consideration of uncertainties is also being introduced in the supplementary sheet of DIN 25478 'Application of computer codes in the assessment of criticality safety'. However, for a correct treatment of uncertainties taking into account the individual uncertainties of the benchmark experiments is insufficient. In addition, correlations between benchmark experiments have to be handled correctly. For example, these correlations can arise due to different cases of a benchmark experiment sharing the same components like fuel pins or fissile solutions. Thus, manufacturing tolerances of these components (e.g. diameter of the fuel pellets) have to be considered in a consistent manner in all cases of the benchmark experiment. At the 2012 meeting of the Expert Group on 'Uncertainty Analysis for Criticality Safety Assessment' (UACSA) of the OECD/NEA a benchmark proposal was outlined that aimed for the determination of the impact on benchmark correlations on the estimation of the computational bias of the neutron multiplication factor (k{sub eff}). The analysis presented here is based on this

  7. Bandgap engineered graphene and hexagonal boron nitride for ...

    Indian Academy of Sciences (India)

    In this article a double-barrier resonant tunnelling diode (DBRTD) has been modelled by taking advantage of single-layer hexagonal lattice of graphene and hexagonal boron nitride (h-BN). The DBRTD performance and operation are explored by means of a self-consistent solution inside the non-equilibrium Green's ...

  8. Memory Erasure Experiments Indicate a Critical Role of CaMKII in Memory Storage.

    Science.gov (United States)

    Rossetti, Tom; Banerjee, Somdeb; Kim, Chris; Leubner, Megan; Lamar, Casey; Gupta, Pooja; Lee, Bomsol; Neve, Rachael; Lisman, John

    2017-09-27

    The abundant synaptic protein CaMKII is necessary for long-term potentiation (LTP) and memory. However, whether CaMKII is required only during initial processes or whether it also mediates memory storage remains unclear. The most direct test of a storage role is the erasure test. In this test, a putative memory molecule is inhibited after learning. The key prediction is that this should produce persistent memory erasure even after the inhibitory agent is removed. We conducted this test using transient viral (HSV) expression of dominant-negative CaMKII-alpha (K42M) in the hippocampus. This produced persistent erasure of conditioned place avoidance. As an additional test, we found that expression of activated CaMKII (T286D/T305A/T306A) impaired place avoidance, a result not expected if a process other than CaMKII stores memory. Our behavioral results, taken together with prior experiments on LTP, strongly support a critical role of CaMKII in LTP maintenance and memory storage. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Critical Components of a Successful Undergraduate Research Experience in the Geosciences for Minority Students

    Science.gov (United States)

    Liou-Mark, J.; Blake, R.; Chukuigwe, C.

    2013-12-01

    For the past five years, the New York City College of Technology has administered a successful National Science Foundation (NSF) Research Experience for Undergraduates (REU) program. The program provides rich, substantive, academic and life-transformative STEM educational experiences for students who would otherwise not pursue STEM education altogether or would not pursue STEM education through to the graduate school level. The REU Scholars are provided with an opportunity to conduct intensive satellite and ground-based remote sensing research at the National Oceanic and Atmospheric Administration Cooperative Remote Sensing Science and Technology Center (NOAA-CREST). Candidates for the program are recruited from the City University of New York's twenty-three separate campuses. These students engage in a research experience that spans the summer and the fall and spring semesters. Eighty-four percent (84%) of the program participants are underrepresented minorities in STEM, and they are involved in a plethora of undergraduate research best practice activities that include: training courses in MATLAB programming, Geographic Information Systems, and Remote Sensing; workshops in Research Ethics, Scientific Writing, and Oral and Poster Research Presentations; national, regional, and local conference presentations; graduate school support; and geoscience exposure events at national laboratories, agencies, and research facilities. To enhance their success in the program, the REU Scholars are also provided with a comprehensive series of safety nets that include a multi-tiered mentoring design specifically to address critical issues faced by this diverse population. Since the inception of the REU program in 2008, a total of 61 undergraduate students have finished or are continuing with their research or are pursuing their STEM endeavors. All the REU Scholars conducted individual satellite and ground-based remote sensing research projects that ranged from the study of

  10. Trauma-exposed firefighters: relationships among posttraumatic growth, posttraumatic stress, resource availability, coping and critical incident stress debriefing experience.

    Science.gov (United States)

    Sattler, David N; Boyd, Bill; Kirsch, Julie

    2014-12-01

    This project examines protective factors associated with resilience/posttraumatic growth and risk factors associated with posttraumatic stress among firefighters exposed to critical incidents. The participants were 286 (257 men and 29 women) volunteer and paid firefighters in Whatcom County, Washington. Participants completed an anonymous survey asking about demographics, critical incident exposure, posttraumatic stress symptoms, posttraumatic growth, resource availability, coping, occupational stress and critical incident stress debriefing experience. Most participants had significant critical incident exposure, and about half had attended critical incident stress debriefing sessions. Posttraumatic growth was associated with being female, critical incident exposure, critical incident stress debriefing attendance, posttraumatic stress symptoms (negative association), occupational support, occupation satisfaction, occupational effort, problem-focused coping, emotion-focused coping and personal characteristic resources. Posttraumatic stress symptoms were positively associated with years of firefighting, burnout, occupational effort and disengagement coping and negatively associated with critical incident stress debriefing attendance, posttraumatic growth, social support, internal locus of control, personal characteristic resources, energy resources and condition resources. The findings support conservation of resources stress theory and show that the maintenance and acquisition of resources can offset losses and facilitate resilience/posttraumatic growth. Implications of the findings for enhancing firefighter resources, facilitating resilience and minimizing occupational stressors are discussed. © 2014 John Wiley & Sons, Ltd.

  11. Exploring the Use of Critical Reflective Inquiry With Nursing Students Participating in an International Service-Learning Experience.

    Science.gov (United States)

    Curtin, Alicia J; Martins, Diane C; Schwartz-Barcott, Donna; DiMaria, Lisa Adorno; Ogando, Béliga Milagros Soler

    2015-09-01

    Increasing interest in providing international educational experiences for nursing students has led to a variety of short-term international service-learning experiences. However, the impact of these experiences has not been clearly articulated. In this qualitative descriptive research study, Kim's critical reflective inquiry model was used to help guide students in reflecting on and identifying the impact of an international service-learning program in the Dominican Republic. The model was helpful in promoting in-depth description and reflection on the students' underlying assumptions and values, as well as identifying beginning strategies for emancipation in specific patient care situations. Providing a group process for critical reflection may optimize the perspective transformations in meeting the goals and objectives of the experience. Copyright 2015, SLACK Incorporated.

  12. Results of critical velocity experiments with barium, strontium, and calcium releases from CRRES satellite

    Science.gov (United States)

    Wescott, E. M.; Stenbaek-Nielsen, H. C.; Hampton, D. L.; Delamere, P. A.

    1994-01-01

    As part of the NASA Combined Release and Radiation Effects Satellite (CRRES) chemical release program in September 1990, two Ba and also one each Sr and Ca canisters of a boron-titanium thermite mixture, which vaporizes the element on ignition, were released near perigee after dusk in the South Pacific to study the critical velocity effect proposed by Alfven. The critical velocities of these three elements are 2.7, 3.5, and 5.4 km/s respectively, all well below the orbital velocity of 9.4 km/s. On September 10, 1990, a Sr and Ba pair (G-13, or critical ionization velocity (CIV) I) was released near Rarotonga at approximately 515 km altitude in a background electron density of 3.4 x 10(exp 6)/cu cm. On September 14, 1990, G-14 or CIV II released a Ca and Ba pair west of New Caledonia near 595 km at an electron density of 1.5 x 10(exp 6)/cu cm. Ions of all three elements were observed with low-light level imagers from two aircraft after they had transited up the magnetic field lines into the sunlight. Emissions from the spherically expanding neutral gas shells below the solar terminator, observed with cameras filtered for the Ba(+) ion line at 4554 A and also in unfiltered imagers for approximately 15 s after release, are probably due to excitation by hot electrons created in the CIV process. The ions created clearly lost much of their energy, which we now show can be explained by elastic collisions: Ba(+) + O. Inventories of the observed ions indicate yields of 0.15% and 1.84% for Ba in the first and second experiments, 0.02% for Sr and 0.27% for Ca. Ionization from all the releases continued along the satellite trajectory much longer (greater than 45 s) than expected for a CIV process. The ion production along the satellite track versus time typically shows a rapid rise to a peak in a few seconds followed by an exponential decrease to a level essentially constant rate. The characteristic distances for CIV I and II are 47 and 62 km, respectively. We interpret the

  13. Promotion of critical thinking in e-learning: a qualitative study on the experiences of instructors and students

    Science.gov (United States)

    Gharib, Mitra; Zolfaghari, Mitra; Mojtahedzadeh, Rita; Mohammadi, Aeen; Gharib, Atoosa

    2016-01-01

    Background With the increasing popularity of e-learning programs, educational stakeholders are attempting to promote critical thinking in the virtual education system. This study aimed to explore the experiences of both the instructors and the students about critical thinking promotion within the virtual education system. Methods This qualitative study recruited the instructors and students from four academic disciplines provided by the Virtual School of Tehran University of Medical Sciences (Tehran, Iran). All programs were master’s degree programs and utilized a blended (combination of e-learning and face to face) training. Semistructured interviews with the participants were used to collect data. Results The participants had a variety of experiences about how to promote critical thinking. These experiences were conceptualized in four main themes, namely, instructional design, educational leadership and management, local evidence, and belief systems. Conclusion The present study clarified the factors affecting critical thinking promotion in e-learning. Not only the instructors but also the educational designers and leaders can benefit from our findings to improve the quality of virtual education programs and promote critical thinking. PMID:27217807

  14. Promotion of critical thinking in e-learning: a qualitative study on the experiences of instructors and students.

    Science.gov (United States)

    Gharib, Mitra; Zolfaghari, Mitra; Mojtahedzadeh, Rita; Mohammadi, Aeen; Gharib, Atoosa

    2016-01-01

    With the increasing popularity of e-learning programs, educational stakeholders are attempting to promote critical thinking in the virtual education system. This study aimed to explore the experiences of both the instructors and the students about critical thinking promotion within the virtual education system. This qualitative study recruited the instructors and students from four academic disciplines provided by the Virtual School of Tehran University of Medical Sciences (Tehran, Iran). All programs were master's degree programs and utilized a blended (combination of e-learning and face to face) training. Semistructured interviews with the participants were used to collect data. The participants had a variety of experiences about how to promote critical thinking. These experiences were conceptualized in four main themes, namely, instructional design, educational leadership and management, local evidence, and belief systems. The present study clarified the factors affecting critical thinking promotion in e-learning. Not only the instructors but also the educational designers and leaders can benefit from our findings to improve the quality of virtual education programs and promote critical thinking.

  15. Campus Climate and the Underrepresented Minority Engineering Student Experience: A Critical Race Study

    Science.gov (United States)

    Mayes, Terrance

    In the current technological era, the number of minorities in science, technology, engineering, and mathematics (STEM) is a crucial factor in predetermining the economic growth of the United States. Since the minority population is growing at much faster rates than the non-minority population, the lack of proportionate production of minority engineers poses a threat to the United States' ability to remain a global competitor in technological innovation. Sixty-three per cent (63%) of undergraduate students who enter engineering majors continue on to graduate in that major. The graduation rate, however, for African-American, Hispanic, and Native-American students in engineering is significantly lower at 39%. As this group represents only a small fraction of the annual student enrollment, engineering programs are graduating these minority groups at rates that are greatly disproportionate to United States demographics. Therefore, researchers are thoroughly investigating certain initiatives that promote academic success among underrepresented minority students in engineering. Colleges and universities have attempted to address the growing achievement gap between underrepresented minority and non-minority engineering students, predominately through various deficit-based interventions, focusing on the student's flaws and problems. As the pipeline for minorities in engineering continues to narrow, it begs the question of whether institutions are focusing on the right solutions to the problem. Critical Race Theory scholars argue that colleges and universities must address institutional climate issues around students, such as racism, microaggressions, and marginalization, before members of oppressed groups can truly succeed. This dissertation explored the unique experiences of underrepresented minority engineering students in a predominately White and Asian campus.

  16. Racial Inequality in Critical Thinking Skills: The Role of Academic and Diversity Experiences

    Science.gov (United States)

    Roksa, Josipa; Trolian, Teniell L.; Pascarella, Ernest T.; Kilgo, Cindy A.; Blaich, Charles; Wise, Kathleen S.

    2017-01-01

    While racial inequalities in college entry and completion are well documented, much less is known about racial disparities in the development of general collegiate skills, such as critical thinking. Using data from the Wabash National Study of Liberal Arts Education, we find substantial inequality in the development of critical thinking skills…

  17. Can Educators Make a Difference? Experimenting with, and Experiencing, Democracy in Education. Critical Constructions: Studies on Education and Society

    Science.gov (United States)

    Carr, Paul R., Ed.; Zyngier, David, Ed.; Pruyn, Marc, Ed.

    2012-01-01

    As the title of this book suggests, how one understands, perceives and experiences democracy may have a significant effect on how he/she actually engages in, and with, democracy. Within the educational context, this is a key concern, and forms the basis of the research presented in this volume within a critical, comparative analysis. The Global…

  18. A Course in Critical Thinking for PhD Students in Biomolecular Sciences and Biotechnology: Classical Experiments in Biochemistry

    Science.gov (United States)

    Hirschberg, Carlos B.

    2016-01-01

    This essay presents and discusses an eight-session seminar course designed to develop critical thinking skills in doctoral biochemistry students by exposing them to classical experiments in biochemistry. During each 2.5 session, different key topics of the discovery and development of biochemical concepts are discussed. Before each session,…

  19. Diversity and Collegiate Experiences Affecting Self-Perceived Gains in Critical Thinking: Which Works, and Who Benefits?

    Science.gov (United States)

    Cole, Darnell; Zhou, Ji

    2014-01-01

    This study is grounded in the theoretical and conceptual frameworks that postulate diversity and collegiate experiences as triggers for the cognitive disequilibrium that fosters critical thinking (CT). With the assumption that CT is both a general and a discipline-specific facility, this longitudinal, single-institution study of 447 students…

  20. Hexagon Wilson Loop OPE and Harmonic Polylogarithms

    CERN Document Server

    Papathanasiou, Georgios

    2013-01-01

    A recent, integrability-based conjecture in the framework of the Wilson loop OPE for N=4 SYM theory, predicts the leading OPE contribution for the hexagon MHV remainder function and NMHV ratio function to all loops, in integral form. We prove that these integrals evaluate to a particular basis of harmonic polylogarithms, at any order in the weak coupling expansion. The proof constitutes an algorithm for the direct computation of the integrals, which we employ in order to obtain the full (N)MHV OPE contribution in question up to 6 loops, and certain parts of it up to 12 loops. We attach computer-readable files with our results, as well as an algorithm implementation which may be readily used to generate higher-loop corrections. The feasibility of obtaining the explicit kinematical dependence of the first term in the OPE in principle at arbitrary loop order, offers promise for the suitability of this approach as a non-perturbative description of Wilson loops/scattering amplitudes.

  1. Whole Core Transport Calculation Methodology for a Hexagonal Core

    Energy Technology Data Exchange (ETDEWEB)

    Cho, J. Y.; Kim, K. S.; Lee, C. C.; Zee, S. Q.; Joo, H. G

    2007-07-15

    This report discusses the hexagonal module implemented to the DeCART code and the performance of them. The implemented hexagonal module includes the hexagonal ray tracing and the CMFD acceleration modules. The performance of the implemented hexagonal module is examined for 4 tests of: (1) CMFD acceleration test, (2) the accuracy test of the hexagonal module, (3) the performance test for 2-D NGNP problem and (4) the applicability test for 3-D NGNP problem. The features of the implemented hexagonal modules are: (1) The Modular ray tracing scheme based on a hexagonal assembly and a path linking scheme between the modular rays. (2) Segment generation based on the structure unit. (3) Cell ray approximation: This feature is developed to reduce the memory required to store the segment information. (4) Modified cycle ray scheme that begins the ray tracing at a given surface and finishes if the reflected ray meets the starting surface. This feature is developed to reduce the memory required for the angular flux at the core boundary. (5) Fixed assembly geometry. The pin geometry of the single pin per assembly problem is different from that of the multi-pin problem. The core geometry of a single assembly problem is also different from that of the multi-assembly problem. (6) CMFD module based on unstructured cell. This feature is to deal with the irregular gap cells that are positioned at the assembly boundaries. The examination results of the 4 tests can be summarized as: (1) The CMFD acceleration test shows that the CMFD module speedups about greater than 200 for the core problem. (2) The accuracy test shows that the hexagonal MOC module produces an accurate solution of less than 60 pcm of eigenvalue and less than 2 % of local pin power errors. (3) The performance test for 2-D NGNP problem shows that the implemented hexagonal module works soundly and produces a reasonable solution by cooperating with the existing DeCART library and the other modules. (4) The applicability

  2. Pyramidal Image-Processing Code For Hexagonal Grid

    Science.gov (United States)

    Watson, Andrew B.; Ahumada, Albert J., Jr.

    1990-01-01

    Algorithm based on processing of information on intensities of picture elements arranged in regular hexagonal grid. Called "image pyramid" because image information at each processing level arranged in hexagonal grid having one-seventh number of picture elements of next lower processing level, each picture element derived from hexagonal set of seven nearest-neighbor picture elements in next lower level. At lowest level, fine-resolution of elements of original image. Designed to have some properties of image-coding scheme of primate visual cortex.

  3. Nylon flocked swab severely reduces Hexagon Obti sensibility.

    Science.gov (United States)

    Frippiat, Christophe; De Roy, Gilbert; Fontaine, Louis-Marie; Dognaux, Sophie; Noel, Fabrice; Heudt, Laeticia; Lepot, Laurent

    2015-02-01

    Hexagon Obti immunological blood test and flocked swab are widely used in forensic laboratories. Nevertheless, up to now, no compatibility tests have been published between sampling with the ethylene oxide treated flocked swab and the Hexagon Obti blood detection strip. In this study, we investigated this compatibility. Our work shows that sampling with ethylene oxide treated flocked swab reduces by a factor of at least 100 the detection threshold of blood using the Hexagon Obti immunological test. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  4. Assessment of Zero Power Critical Experiments and Needs for a Fission Surface Power System

    Energy Technology Data Exchange (ETDEWEB)

    Jim R Parry; John Darrell bess; Brad T. Rearden; Gary A. Harms

    2009-06-01

    The National Aeronautics and Space Administration (NASA) is providing funding to the Department of Energy (DOE) to assess, develop, and test nuclear technologies that could provide surface power to a lunar outpost. Sufficient testing of this fission surface power (FSP) system will need to be completed to enable a decision by NASA for flight development. The near-term goal for the FSP work is to conduct the minimum amount of testing needed to validate the system performance within an acceptable risk. This report attempts to assess the current modeling capabilities and quantify any bias associated with the modeling methods for designing the nuclear reactor. The baseline FSP system is a sodium-potassium (NaK) cooled, fast spectrum reactor with 93% 235U enriched HEU-O2 fuel, SS316 cladding, and beryllium reflectors with B4C control drums. The FSP is to produce approximately 40 kWe net power with a lifetime of at least 8 years at full power. A flight-ready FSP is to be ready for launch and deployment by 2020. Existing benchmarks from the International Criticality Safety Benchmark Evaluation Program (ICSBEP) were reviewed and modeled in MCNP. An average bias of less than 0.6% was determined using the ENDF/B-VII cross-section libraries except in the case of subcritical experiments, which exhibited an average bias of approximately 1.5%. The bias increases with increasing reflector worth of the beryllium. The uncertainties and sensitivities in cross section data for the FSP model and ZPPR-20 configurations were assessed using TSUNAMI-3D. The cross-section covariance uncertainty in the FSP model was calculated as 2.09%, which was dominated by the uncertainty in the 235U(n,?) reactions. Global integral indices were generated in TSUNAMI-IP using pre-release SCALE 6 cross-section covariance data. The ZPPR-20 benchmark models exhibit strong similarity with the FSP model. A penalty assessment was performed to determine the degree of which the FSP model could not be characterized

  5. Critical experiments supporting close proximity water storage of power reactor fuel. Technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, M.N.; Hoovler, G.S.; Eng, R.L.; Welfare, F.G.

    1979-07-01

    Close-packed storage of LWR fuel assemblies is needed in order to expand the capacity of existing underwater storage pools. This increased capacity is required to accommodate the large volume of spent fuel produced by prolonged onsite storage. To provide benchmark criticality data in support of this effort, 20 critical assemblies were constructed that simulated a variety of close-packed LWR fuel storage configurations. Criticality calculations using the Monte Carlo KENO-IV code were performed to provide an analytical basis for comparison with the experimental data. Each critical configuration is documented in sufficient detail to permit the use of these data in validating calculational methods according to ANSI Standard N16.9-1975.

  6. A CRITICISM OF MONETARISM : WITH SOME POINTS FROM THE JAPANESE EXPERIENCE

    OpenAIRE

    Braguinsky, Serguey

    1988-01-01

    The paper attempts at unifying the criticism of "classical dichotomy" made by J. A. Schumpeter and J. M. Keynes. Though Schumpeter's vision was that of the developing economy, with money being an important source of that development, while Keynes dealt primarily with an economy in a state of depression, Keynes's criticism is conjectured to presuppose the existence of the Schumpeterian world in the background, because only in this case can money play an active role by linking the past, present...

  7. Critical heat flux experiments in a circular tube with heavy water and light water. (AWBA Development Program)

    Energy Technology Data Exchange (ETDEWEB)

    Williams, C.L.; Beus, S.G.

    1980-05-01

    Experiments were performed to establish the critical heat flux (CHF) characteristics of heavy water and light water. Testing was performed with the up-flow of heavy and of light water within a 0.3744 inch inside diameter circular tube with 72.3 inches of heated length. Comparisons were made between heavy water and light water critical heat flux levels for the same local equilibrium quality at CHF, operating pressure, and nominal mass velocity. Results showed that heavy water CHF values were, on the average, 8 percent below the light water CHF values.

  8. Experiment and Simulation Study on the Special Phase Behavior of Huachang Near-Critical Condensate Gas Reservoir Fluid

    Directory of Open Access Journals (Sweden)

    Dali Hou

    2016-01-01

    Full Text Available Due to the special phase behavior of near-critical fluid, the development approaches of near-critical condensate gas and near-critical volatile oil reservoirs differ from conventional oil and gas reservoirs. In the near-critical region, slightly reduced pressure may result in considerable change in gas and liquid composition since a large amount of gas or retrograde condensate liquid is generated. It is of significance to gain insight into the composition variation of near-critical reservoir during the depletion development. In our study, we performed a series of PVT experiments on a real near-critical gas condensate reservoir fluid. In addition to the experimental studies, a commercial simulator combined with the PREOS model was utilized to study retrograde condensate characteristics and reevaporation mechanism of condensate oil with CO2 injection based on vapor-liquid phase equilibrium thermodynamic theory. The research shows that when reservoir pressure drops below a certain pressure, the variation of retrograde condensate liquid saturation of the residual reservoir fluid exhibits the phase behavior of volatile oil.

  9. Percolation crossing probabilities in hexagons: a numerical study

    Science.gov (United States)

    Flores, S. M.; Ziff, R. M.; Simmons, J. J. H.

    2015-01-01

    In a recent article (Simmons 2013 J. Phys. A: Math. Theor. 46 494015), the last author of this article used c = 0 logarithmic conformal field theory to predict crossing probability formulas for percolation clusters inside a hexagon with free boundary conditions. In the present article, we verify these predictions with high-precision computer simulations for equiangular hexagons with side lengths alternating from short to long. Our simulations generate percolation-cluster perimeters with hull walks on a triangular lattice inside a hexagon. Each sample comprises two hull walks, and the order in which these walks strike the bottom and upper left/right sides of the hexagon determines the crossing configuration of the percolation sample. We compare our numerical results with the predicted crossing probabilities, finding excellent agreement.

  10. Bulk magnetoelectricity in the hexagonal manganites and ferrites

    National Research Council Canada - National Science Library

    Das, Hena; Wysocki, Aleksander L; Geng, Yanan; Wu, Weida; Fennie, Craig J

    2014-01-01

    Improper ferroelectricity (trimerization) in the hexagonal manganites RMnO3 leads to a network of coupled structural and magnetic vortices that induce domain wall magnetoelectricity and magnetization (M...

  11. Origin of band gaps in graphene on hexagonal boron nitride

    National Research Council Canada - National Science Library

    Jung, Jeil; DaSilva, Ashley M; MacDonald, Allan H; Adam, Shaffique

    2015-01-01

    .... Here we address the intriguing energy gaps that are sometimes observed when a graphene sheet is placed on a hexagonal boron nitride substrate, demonstrating that they are produced by an interesting...

  12. Bifurcation theory for hexagonal agglomeration in economic geography

    CERN Document Server

    Ikeda, Kiyohiro

    2014-01-01

    This book contributes to an understanding of how bifurcation theory adapts to the analysis of economic geography. It is easily accessible not only to mathematicians and economists, but also to upper-level undergraduate and graduate students who are interested in nonlinear mathematics. The self-organization of hexagonal agglomeration patterns of industrial regions was first predicted by the central place theory in economic geography based on investigations of southern Germany. The emergence of hexagonal agglomeration in economic geography models was envisaged by Krugman. In this book, after a brief introduction of central place theory and new economic geography, the missing link between them is discovered by elucidating the mechanism of the evolution of bifurcating hexagonal patterns. Pattern formation by such bifurcation is a well-studied topic in nonlinear mathematics, and group-theoretic bifurcation analysis is a well-developed theoretical tool. A finite hexagonal lattice is used to express uniformly distri...

  13. Phonon symmetries in hexagonal boron nitride probed by incoherent light emission

    Science.gov (United States)

    Vuong, T. Q. P.; Cassabois, G.; Valvin, P.; Jacques, V.; Van Der Lee, A.; Zobelli, A.; Watanabe, K.; Taniguchi, T.; Gil, B.

    2017-03-01

    Layered compounds are stacks of weakly bound two-dimensional atomic crystals, with a prototypal hexagonal structure in graphene, transition metal dichalcogenides and boron nitride. This crystalline anisotropy results in vibrational modes with specific symmetries depending on the in-plane or out-of-plane atomic displacements. We show that polarization-resolved photoluminescence measurements in hexagonal boron nitride reflect the phonon symmetries in this layered semiconductor. Experiments performed with a detection on the sample edge, perpendicular to the c-axis, reveal the strong polarization-dependence of the emission lines corresponding to the recombination assisted by the three acoustic phonon modes. We elucidate the dipole orientation of the fundamental indirect exciton. We demonstrate evidence of the so-far missing phonon replica due to the optical out-of-plane phonon mode.

  14. THE TRANSFORM BETWEEN GEOGRAPHIC COORDINATES AND LOCATION CODES OF APERTURE 4 HEXAGONAL GRID SYSTEM

    Directory of Open Access Journals (Sweden)

    R. Wang

    2017-09-01

    Full Text Available Discrete global grid system is a new data model which supports the fusion processing of multi-source geospatial data. In discrete global grid systems, all cell operations can be completed by codes theoretically, but most of current spatial data are in the forms of geographic coordinates and projected coordinates. It is necessary to study the transform between geographic coordinates and grid codes, which will support data entering and getting out of the systems. This paper chooses the icosahedral hexagonal discrete global system as a base, and builds the mapping relationships between the sphere and the icosahedron. Then an encoding scheme of planar aperture 4 hexagonal grid system is designed and applied to the icosahedron. Basing on this, a new algorithm of transforms between geographic coordinates and grid codes is designed. Finally, experiments test the accuracy and efficiency of this algorithm. The efficiency of code addition of HLQT is about 5 times the efficiency of code addition of HQBS.

  15. The Transform Between Geographic Coordinates and Location Codes of Aperture 4 Hexagonal Grid System

    Science.gov (United States)

    Wang, R.; Ben, J.; Li, Y.; Du, L.

    2017-09-01

    Discrete global grid system is a new data model which supports the fusion processing of multi-source geospatial data. In discrete global grid systems, all cell operations can be completed by codes theoretically, but most of current spatial data are in the forms of geographic coordinates and projected coordinates. It is necessary to study the transform between geographic coordinates and grid codes, which will support data entering and getting out of the systems. This paper chooses the icosahedral hexagonal discrete global system as a base, and builds the mapping relationships between the sphere and the icosahedron. Then an encoding scheme of planar aperture 4 hexagonal grid system is designed and applied to the icosahedron. Basing on this, a new algorithm of transforms between geographic coordinates and grid codes is designed. Finally, experiments test the accuracy and efficiency of this algorithm. The efficiency of code addition of HLQT is about 5 times the efficiency of code addition of HQBS.

  16. Learning from experience: constructing critical case reviews for a leadership programme.

    Science.gov (United States)

    Crofts, Linda

    2006-10-01

    A previous paper described the development of a leadership programme for critical care and highlighted that one of the strengths of the programme was the critical case review. This paper sets out in some depth the major theoretical influences in the construction of the case review. Case reviews have been used in education for some time but often have predetermined outcomes. The education approach favoured here was based on action learning, which in itself belongs to the broad church of reflective practice. While reflective practice has been advocated in nursing since 1986 together with the introduction of clinical supervision neither have met with unqualified success in their own right. This paper concludes that while the concept and construction of the critical case review may be new it is in essence no more than a jigsaw of already well-established practices of reflection, clinical supervision and action learning woven into the foundations of clinical risk management and whole systems working.

  17. Coretran/Vipre assembly critical power assessment against Nupec BWR experiments

    Energy Technology Data Exchange (ETDEWEB)

    Aounallah, Y. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    2001-07-01

    This study has been performed, in the framework of the STARS project, to assess CORETRAN-01/VIPRE-02 code capability to predict critical heat flux conditions for BWR fuel assemblies. The assessment is based on comparisons of the code results with the NUPEC steady-state critical power measurements on full-scale assemblies tested under a range of flow conditions. Two assembly types were considered, the standard BWR 8 x 8 and the so-called ''high-burnup'' assembly, similar to GE-10. Code modelling options that have a significant impact on the results have been identified, along with code limitations. (author)

  18. Global Formation of Topological Defects in the Multiferroic Hexagonal Manganites

    Directory of Open Access Journals (Sweden)

    Q. N. Meier

    2017-10-01

    Full Text Available The spontaneous transformations associated with symmetry-breaking phase transitions generate domain structures and defects that may be topological in nature. The formation of these defects can be described according to the Kibble-Zurek mechanism, which provides a generic relation that applies from cosmological to interatomic length scales. Its verification is challenging, however, in particular at the cosmological scale where experiments are impractical. While it has been demonstrated for selected condensed-matter systems, major questions remain regarding, e.g., its degree of universality. Here, we develop a global Kibble-Zurek picture from the condensed-matter level. We show theoretically that a transition between two fluctuation regimes (Ginzburg and mean field can lead to an intermediate region with reversed scaling, and we verify experimentally this behavior for the structural transition in the series of multiferroic hexagonal manganites. Trends across the series allow us to identify additional intrinsic features of the defect formation beyond the original Kibble-Zurek paradigm.

  19. The National Criticality Experiments Research Center at the Device Assembly Facility, Nevada National Security Site: Status and Capabilities, Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    S. Bragg-Sitton; J. Bess; J. Werner

    2011-09-01

    The National Criticality Experiments Research Center (NCERC) was officially opened on August 29, 2011. Located within the Device Assembly Facility (DAF) at the Nevada National Security Site (NNSS), the NCERC has become a consolidation facility within the United States for critical configuration testing, particularly those involving highly enriched uranium (HEU). The DAF is a Department of Energy (DOE) owned facility that is operated by the National Nuclear Security Agency/Nevada Site Office (NNSA/NSO). User laboratories include the Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL). Personnel bring their home lab qualifications and procedures with them to the DAF, such that non-site specific training need not be repeated to conduct work at DAF. The NNSS Management and Operating contractor is National Security Technologies, LLC (NSTec) and the NNSS Safeguards and Security contractor is Wackenhut Services. The complete report provides an overview and status of the available laboratories and test bays at NCERC, available test materials and test support configurations, and test requirements and limitations for performing sub-critical and critical tests. The current summary provides a brief summary of the facility status and the method by which experiments may be introduced to NCERC.

  20. Reconceptualizing Self and Other through Critical Media Engagement. Experiences and Reflections of English Learners and Teacher

    Science.gov (United States)

    Huang, Shin-ying

    2015-01-01

    This research explores how critical media literacy transforms ways of engaging with media texts and expands the understanding and practice of literacy. In this qualitative teacher inquiry, even though the teacher researcher had envisioned for the students an identity as academic-language learners who engage with competing ideologies of masculinity…

  1. Critical and Social Literacy Practices from the Scottish Adult Literacy Experience: Resisting Deficit Approaches to Learning

    Science.gov (United States)

    Crowther, Jim; Tett, Lyn

    2011-01-01

    Scotland provides an interesting context for studying adult literacy in that it is one of the few countries that explicitly acknowledge the idea of literacy as a social practice. By drawing on two initiatives we illustrate literacy learning derived from a mixture of social practice and critical literacy perspectives. Together they provide insights…

  2. Voice, Identity, and the Organizing of Student Experience: Managing Pedagogical Dilemmas in Critical Classroom Discussions

    Science.gov (United States)

    Yannuzzi, Thomas J.; Martin, Daniela

    2014-01-01

    The current paper explores the discursive complexities of teaching and learning in inclusive, critically oriented classrooms. It argues that to accomplish the ontological goals of higher learning, we need to focus on the construction of student voice, or the ability to be considered in and have influence on teaching and learning. The paper further…

  3. Does the Community College Experience Affect Critical Thinking and Moral Reasoning?

    Science.gov (United States)

    Rykiel, Joan Devlin

    2000-01-01

    Assesses the net effects of community college attendance on moral reasoning and critical thinking skills, examining the conditional effects of age and off-campus employment on the two dependent measures. Finds that sophomores scored significantly higher than freshmen on both measures, and that students with longer work schedule hours had…

  4. New Graduate Nurses' Perceived Definition of Critical Thinking during Their First Nursing Experience

    Science.gov (United States)

    Kaddoura, Mahmoud

    2013-01-01

    Critical thinking (CT) is a flourishing concept that has been developing throughout the fields of both nursing education and practice. In fact, every person thinks in his or her own way that is varied among individuals; it is the nature of human mankind to do so. Nevertheless, much of our thinking might be subjective, indefinite, limited,…

  5. Measuring the coefficient of restitution and more: a simple experiment to promote students’ critical thinking and autonomous work

    Science.gov (United States)

    González, Manuel Á.; González, Miguel Á.; Vegas, Jesús; Llamas, César

    2017-09-01

    A simple experiment on the determination of the coefficient of restitution of different materials is taken as the basis of an extendable work that can be done by students in an autonomous way. On the whole, the work described in this paper would involve concepts of kinematics, materials science, air drag and buoyancy, and would help students to think of physics as a whole subject instead of a set of, more or less, isolated parts. The experiment can be done either in teaching laboratories or as an autonomous work by students at home. Students’ smartphones and cheap balls of different materials are the only experimental materials required to do the experiment. The proposed work also permits the students to analyse the limitations of a physical model used in the experiment by analysing the approximations considered in it, and then enhancing their critical thinking.

  6. Comparative study on neutron data in integral experiments of MYRRHA mockup critical cores in the VENUS-F reactor

    Science.gov (United States)

    Krása, Antonín; Kochetkov, Anatoly; Baeten, Peter; Vittiglio, Guido; Wagemans, Jan; Bécares, Vicente

    2017-09-01

    VENUS-F is a fast, zero-power reactor with 30% wt. metallic uranium fuel and solid lead as coolant simulator. It serves as a mockup of the MYRRHA reactor core. This paper describes integral experiments performed in two critical VENUS-F core configurations (with and without graphite reflector). Discrepancies between experiments and Monte Carlo calculations (MCNP5) of keff, fission rate spatial distribution and reactivity effects (lead void and fuel Doppler) depending on a nuclear data library used (JENDL-4.0, ENDF-B-VII.1, JEFF-3.1.2, 3.2, 3.3T2) are presented.

  7. Comparative study on neutron data in integral experiments of MYRRHA mockup critical cores in the VENUS-F reactor

    Directory of Open Access Journals (Sweden)

    Krása Antonín

    2017-01-01

    Full Text Available VENUS-F is a fast, zero-power reactor with 30% wt. metallic uranium fuel and solid lead as coolant simulator. It serves as a mockup of the MYRRHA reactor core. This paper describes integral experiments performed in two critical VENUS-F core configurations (with and without graphite reflector. Discrepancies between experiments and Monte Carlo calculations (MCNP5 of keff, fission rate spatial distribution and reactivity effects (lead void and fuel Doppler depending on a nuclear data library used (JENDL-4.0, ENDF-B-VII.1, JEFF-3.1.2, 3.2, 3.3T2 are presented.

  8. HBCUs as Critical Context for Identity Work: Reflections, Experiences, and Lessons Learned

    Science.gov (United States)

    Greenfield, Derek F.; Innouvong, Tony; Aglugub, Richard Jay; Yusuf, Ismail A.

    2015-01-01

    Using narratives from a diverse group of students and staff in terms of race and religion, this chapter gives voice to these individuals' experiences with issues of diversity and inclusion at an HBCU. This chapter also discusses how these experiences helped to facilitate the authors' racial and cultural identity development.

  9. Effects of Diversity Experiences on Critical Thinking Skills over 4 Years of College

    Science.gov (United States)

    Pascarella, Ernest T.; Martin, Georgianna L.; Hanson, Jana M.; Trolian, Teniell L.; Gillig, Benjamin; Blaich, Charles

    2014-01-01

    The benefits of student engagement in diversity experiences on a range of college outcomes have been well documented. However, the potential influence of involvement in diversity experiences during college on the cognitive and intellectual outcomes of post-secondary education is only beginning to be understood. Gurin et al. (2002) made a…

  10. The extended family of hexagonal molybdenum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Hartl, Monika [Los Alamos National Laboratory; Daemen, Luke [Los Alamos National Laboratory; Lunk, J H [NON LANL; Hartl, H [NON LANL; Frisk, A T [NON LANL; Shendervich, I [NON LANL; Mauder, D [NON LANL; Feist, M [NON LANL; Eckelt, R [NON LANL

    2009-01-01

    Over the last 40 years, a large number of isostructural compounds in the system MoO{sub 3}-NH{sub 3}-H{sub 2}O have been published. The reported molecular formulae of 'hexagonal molybdenum oxide' (HEMO) varied from MoO{sub 3}, MoO{sub 3} {center_dot} 0.33NH{sub 3}, MoO{sub 3} {center_dot} nH{sub 2}O (0.09 {le} n {le} 0.69) to MoO{sub 3} {center_dot} mNH{sub 3} {center_dot} nH{sub 2}O (0.09 {le} m {le} 0.20; 0.18 {le} n {le} 0.60). Samples, prepared by the acidification route, were investigated using thermal analysis coupled on-line to a mass spectrometer for evolved gas analysis; X-ray powder diffraction; Fourier Transform Infrared, Raman and Magic-Angle-Spinning {sup 1}H-NMR spectroscopy; Incoherent Inelastic Neutron Scattering. The X-ray study of a selected monocrystal confirmed the presence of the well-known framework of edge-sharing MoO{sub 6} octahedra: Space group P6{sub 3}/m, a = 10.527(1), c =3.7245(7) {angstrom}, {gamma} = 120{sup o}. The structure of the synthesized samples can best be described by the structural formula (NH{sub 4})[Mo{sub x}{open_square}{sub 1/2+p/2}(O{sub 3x + 1/2-p/2})(OH){sub p}] {center_dot} yH{sub 2}O (x 5.9-7.1; p {approx} 0.1; y = 1.2-2.6), which is consistent with the existence of one vacancy for 12-15 molybdenum sites. The 'chimie douce' reaction of MoO{sub 3} {center_dot} 0.155NH{sub 3} {center_dot} 0.440H{sub 2}O with a 1:1 mixture of NO/NO{sub 2} at 100 C resulted in the synthesis of MoO{sub 3} {center_dot} 0.539H{sub 2}O. Tailored nano-sized molybdenum powders can be produced using HEMO as precursor.

  11. Professorial Views of the Use of Diversity Experiences to Develop Students' Critical Thinking Skills in the Pakistani College Context

    Science.gov (United States)

    Tahir, Khazima

    2017-01-01

    This study explored the interplay of diversity experiences and critical thinking of Pakistani college students and determined how the classroom experience supported and exposed students to diversity and critical thinking. The researcher conducted teachers' interviews to gather data in a college in Pakistan. Teachers were asked to respond to a…

  12. Abdominal compartment syndrome among critically ill surgical and traumatised patients: experience at Pims, Islamabad.

    Science.gov (United States)

    Saaiq, Muhammad; Aslam Shah, Syed; Khaliq, Tanwir

    2009-01-01

    Raised intra-abdominal pressure (IAP) accompanied by evidence of organ dysfunction constitutes abdominal compartment syndrome (ACS). The ACS is now becoming an increasingly recognised fatal entity in the critically ill surgical and traumatized patients receiving critical care. The objectives were to determine the frequency of abdominal compartment syndrome (ACS) in critically ill surgical and traumatised patients and to identify the risk factors associated with its development in our patients. This descriptive study was conducted at Department of Surgery, Pakistan Institute of Medical Sciences (PIMS), Islamabad from July 2004 to February 2005. Two hundred critically ill adult surgical and traumatised patients who needed catheterisation were included in the study. Patients who had cardiac tamponade, tension pneumothorax, status asthmaticus, bladder outflow obstruction, pre-existing end organ failure and those not consenting to participate in the study were excluded. Diagnosis of the underlying surgical condition was made by history, physical examination and necessary investigations. The main diagnostic tool employed for detecting ACS was the measurement of intra-cystic pressure (ICP) which was taken as an indirect measure of intra-abdominal pressure (IAP). It was measured four hourly by employing simple fluid column manometry method. Blood pressure, pulse rate, temperature, respiratory rate and urine output were recorded 4 hourly. Arterial blood gases (ABGs) and renal function tests (RFTs) were performed daily. ACS was diagnosed on the basis of raised IAP of >10 mmHg coupled with evidence of one or more end organ failure. A variety of risk factors that lead to ACS were studied among the patients. Out of 200 patients, six had ACS. The overall frequency was thus 3%. The M:F was 2:1. Most of the patients were in the age range of 31-40 years. Severe peritonitis, severe gut oedema, SIRS and tense ascites were recognised as statistically significant risk factors for the

  13. Synthesis of Phase Pure Hexagonal YFeO3 Perovskite as Efficient Visible Light Active Photocatalyst

    Directory of Open Access Journals (Sweden)

    Mohammed Ismael

    2017-11-01

    Full Text Available Hexagonal perovskite YFeO3 was synthesized by a complex-assisted sol-gel technique allowing crystallization at calcination temperatures below 700 °C. As determined by diffuse reflectance spectroscopy (DRS and Tauc plots, the hexagonal YFeO3 exhibits a lower optical band gap (1.81 eV than the orthorhombic structure (about 2.1 eV or even higher being typically obtained at elevated temperatures (>700 °C, and thus enables higher visible light photocatalysis activity. Structure and morphology of the synthesized YFeO3 perovskites were analyzed by powder X-ray diffraction (XRD and nitrogen adsorption, proving that significantly smaller crystallite sizes and higher surface areas are obtained for YFeO3 with a hexagonal phase. The photocatalytic activity of the different YFeO3 phases was deduced via the degradation of the model pollutants methyl orange and 4-chlorophenol. Experiments under illumination with light of different wavelengths, in the presence of different trapping elements, as well as photoelectrochemical tests allow conclusions regarding band positions of YFeO3 and the photocatalytic degradation mechanism. X-ray photoelectron spectroscopy indicates that a very thin layer of Y2O3 might support the photocatalysis by improving the separation of photogenerated charge carriers.

  14. Gender and the experience of moral distress in critical care nurses.

    Science.gov (United States)

    O'Connell, Christopher B

    2015-02-01

    Nursing practice is complex, as nurses are challenged by increasingly intricate moral and ethical judgments. Inadequately studied in underrepresented groups in nursing, moral distress is a serious problem internationally for healthcare professionals with deleterious effects to patients, nurses, and organizations. Moral distress among nurses has been shown to contribute to decreased job satisfaction and increased turnover, withdrawal from patients, physical and psychological symptoms, and intent to leave current position or to leave the profession altogether. Do significant gender differences exist in the moral distress scores of critical care nurses? This study utilized a quantitative, descriptive methodology to explore moral distress levels in a sample of critical care nurses to determine whether gender differences exist in their mean moral distress scores. Participants (n = 31) were critical care nurses from an American Internet nursing community who completed the Moral Distress Scale-Revised online over a 5-day period in July 2013. Institutional review board review approved the study, and accessing and completing the survey implied informed consent. The results revealed a statistically significant gender difference in the mean moral distress scores of participants. Females reported statistically significantly higher moral distress scores than did males. Overall, the moral distress scores for both groups were relatively low. The findings of a gender difference have not previously been reported in the literature. However, other findings are consistent with previous studies on moral distress. Although the results of this study are not generalizable, they do suggest the need for continuing research on moral distress in underrepresented groups in nursing, including cultural and ethnic groups. © The Author(s) 2014.

  15. Critical opacity: a possible explanation of the fast thermalization times seen in BNL RHIC experiments.

    Science.gov (United States)

    Gastineau, F; Blanquier, E; Aichelin, J

    2005-07-29

    The Nambu-Jona-Lasinio Lagrangian offers an explication of the seemingly contradictory observations that (a) the energy loss in the entrance channel of heavy ion reactions is not sufficient to thermalize the system and that (b) the observed hadron cross sections are in almost perfect agreement with hydrodynamical calculations. According to this scenario, a critical opacity develops close to the chiral phase transition which equilibrates and hadronizes the expanding system very effectively. It creates as well radial flow and, if the system is not isotropic, finite upsilon2 values.

  16. Critical Criminology and Legal Culture Punitive: Reflections and Restorative Experience Hopelessness Times

    Directory of Open Access Journals (Sweden)

    Ivone Fernandes Morcilo Lixa

    2016-10-01

    Full Text Available Since a decolonizing pespective critic it announces the end of the great civilizing modern project and the criminological thinking seems to be immobilized and useless. A civilizing wreck that raises the fear in its many versions. In between the desperation, the Restorative Justice points to a new democratic and participative project. Going towards to the perception of this practice by the actors of the punitive system in the County of Blumenau - SC - realized studies show resistance to the possibility of going beyond a punitive colonized culture that still insist on legitimizing a selecive and perverse model.

  17. Inserting Stress Analysis of Combined Hexagonal Aluminum Honeycombs

    Directory of Open Access Journals (Sweden)

    Xiangcheng Li

    2016-01-01

    Full Text Available Two kinds of hexagonal aluminum honeycombs are tested to study their out-of-plane crushing behavior. In the tests, honeycomb samples, including single hexagonal aluminum honeycomb (SHAH samples and two stack-up combined hexagonal aluminum honeycombs (CHAH samples, are compressed at a fixed quasistatic loading rate. The results show that the inserting process of CHAH can erase the initial peak stress that occurred in SHAH. Meanwhile, energy-absorbing property of combined honeycomb samples is more beneficial than the one of single honeycomb sample with the same thickness if the two types of honeycomb samples are completely crushed. Then, the applicability of the existing theoretical model for single hexagonal honeycomb is discussed, and an area equivalent method is proposed to calculate the crushing stress for nearly regular hexagonal honeycombs. Furthermore, a semiempirical formula is proposed to calculate the inserting plateau stress of two stack-up CHAH, in which structural parameters and mechanics properties of base material are concerned. The results show that the predicted stresses of three kinds of two stack-up combined honeycombs are in good agreement with the experimental data. Based on this study, stress-displacement curve of aluminum honeycombs can be designed in detail, which is very beneficial to optimize the energy-absorbing structures in engineering fields.

  18. Impact of advanced practice providers (nurse practitioners and physician assistants) on surgical residents' critical care experience.

    Science.gov (United States)

    Kahn, Steven A; Davis, Sarah A; Banes, Caroline T; Dennis, Bradley M; May, Addison K; Gunter, Oliver D

    2015-11-01

    Teaching hospitals often employ advanced practice providers (nurse practitioners and physician assistants or APPs) to counteract residents' work-hour restrictions. With increased utilization of APPs in labor-intense areas, such as intensive care units (ICUs), APPs may have an impact on resident education and experience. No studies have investigated the direct role an APP plays on the training experience of a surgical resident in the ICU. An institutional review board-approved survey was emailed to residents in Accreditation Council for Graduate Medical Education-accredited general surgery programs. Surveys asked about demographics, residency and/or ICU characteristics, and the effects of APPs on patient care, workflow, and educational experience. Regression analysis determined predictors of resident perception. A total of 354 of 1178 residents responded to the survey (30%). Some residents felt that nurses calling APPs preferentially for patient-care issues interfered with education (17%) and residents' ability to follow patients (12%) and was associated with overall detrimental effects to ICU experience on regression (odds ratio, 3.7; confidence interval, 1.5-9.1). Most residents reported positive effects of APPs, such as reduced resident workload (79.8%), teaching protocols and/or guidelines (60.3%), enhanced patient care (60.3%), and enhanced communication (50.5%). When asked how APPs affected their overall ICU experience, 48.4% reported positive effects, 20.6% reported "no effect," and 31% reported detrimental effects. Only a minority of residents perceived that APPs detract from training, particularly those who felt excluded when nurses preferentially contact APPs with patient-care issues. APPs have the potential to enhance training and ICU experience, as reflected in many of the responses. Strategies to maintain direct nurse and resident communication might preserve residents' perception of the educational value of APPs. Copyright © 2015 Elsevier Inc. All

  19. Dogs’ recognition of human selfish and generous attitudes requires little but critical experience with people

    OpenAIRE

    Carballo, Fabricio; Freidin, Esteban; Emma B Casanave; Bentosela, Mariana

    2017-01-01

    There is some dispute regarding the role of experience in the development of dogs´ socio-cognitive abilities in their interaction with people. We sought to provide new evidence to this debate by comparing dogs with contrasting levels of experience with humans, in a task involving the discrimination of human generous and selfish attitudes. To this end, we compared the performance of adult family dogs against that of adult shelter dogs and puppies living in people´s homes. In training trials, t...

  20. Below the knee PTA in critical limb ischemia results after 12 months: Single center experience

    Energy Technology Data Exchange (ETDEWEB)

    Balzer, Joern O., E-mail: balzerjo@t-online.d [Dept. for Radiology and Nuclear medicine, Catholic Clinic Mainz, An der Goldgrube 11, Mainz 55131 (Germany); Khan, Verena [Dept. of Diagnostic and Interventional Radiology, Clinic Nurnberg North (Germany); Thalhammer, Axel; Vogl, Thomas J.; Lehnert, Thomas [Dept. of Diagnostic and Interventional Radiology, Univ. Clinic, Johann Wolfgang Goethe-University Frankfurt/Main (Germany)

    2010-07-15

    Purpose: Evaluation of angioplasty with bare metal stents in infrapopliteal occlusions or severe stenoses in patients with critical limb ischemia. Material and methods: Percutaneous stent angioplasty was performed in 58 limbs in 47 patients with critical limb ischemia (CLI) in Rutherford stage 4-6. Lesions with up to 5 cm in length with at least one patent vessel below the obstruction were treated. 121 bare metal stents (diameter of 2.5-4 mm; length of 18-38 mm) were implanted. Follow-up examinations were performed up to 12 months postinterventionally using clinical examination, ABI calculation, and color-coded duplex sonography. Patency rates were calculated on the basis of the Kaplan-Meier analysis. Results: Technical success was achieved in 100%. Minor complications (hematoma, distal emboli, vessel dissection) were documented in 5.17% (n = 3) limbs, respectively. The 3-month, 6-month, and 1-year primary patency rate was 93.0%, 78.9% and 66.7%, respectively. 86.9% of the lesions healed postinterventionally. The cumulative limb salvage rate was 96.6%. Conclusion: Stent angioplasty in infrapopliteal arteries is a safe and effective technique for the treatment of patients with CLI. By consequent clinical monitoring high secondary patency rates can be achieved. The use of a bare metal stent seems to result in high limb salvage, primary and secondary patency rates in the mid-term follow-up.

  1. Experience of critical incident stress among ambulance service staff and relationship to psychological symptoms.

    Science.gov (United States)

    Gallagher, Sharon; McGilloway, Sinéad

    2009-01-01

    This two-stage study was undertaken to assess the extent and nature of Critical Incident Stress (CIS) amongst frontline staff in a large ambulance service in Ireland. In Stage One, 63% (112/180) of participants completed a Screening Questionnaire and the GHQ-12. In Stage Two, 27 participants, who had experienced a critical incident (CI) during the previous year completed several measures to assess PTSD symptomatology, burnout, health-related Quality of Life, and dispositional optimism. Eighty-one per cent (80/94) of the Stage One group reported that their health had been affected by a CI; 42% (44/106) were identified as 'cases' on the GHQ-12. Stage Two results indicated that 12 participants had PTSD symptoms while this entire group showed moderate levels of emotional exhaustion and depersonalization, despite experiencing high levels of personal accomplishment and optimism. The findings suggest a high prevalence of CIS among ambulance personnel in Ireland and a significant impact on overall health and wellbeing. This has important implications for the effective management of CIS and suggests an important role for occupational health and organizational psychologists in providing routine support to ambulance service staff andpossibly other emergency services personnel.

  2. Temperature dependence of the critical current of the superconducting microladder in zero magnetic field: Theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Fink, H.J. (Department of Electrical Engineering and Computer Science, University of California, Davis, Davis, California 95616 (USA)); Buisson, O.; Pannetier, B. (Centre de Recherches sur les Tres Basses Temperature, Centre National de la Recherche Scientifique, Boite Postale 166X, 38042 Grenoble CEDEX, France (FR))

    1991-05-01

    The largest supercurrent which can be injected into a superconducting microladder was calculated as a function of nodal spacing {ital scrL} and temperature for zero magnetic flux using (i) exact solutions of the Ginzburg-Landau equation in terms of Jacobian elliptic functions and (ii) approximate solutions in terms of hyperbolic functions. The agreement is good for {ital scrL}/{xi}({ital T}){lt}3, where {xi}({ital T}) is the temperature-dependent coherence length. Since solution (ii) is much simpler than solution (i), it is of considerable value when calculating critical currents of micronets with nodal spacings comparable to {xi}({ital T}). We find that the temperature-dependent critical current deviates significantly from the classical 3/2 power law of the Ginzburg-Landau theory. Preliminary experiments on a submicrometer ladder confirm such deviations.

  3. A Critical Reflection: Foster Care Youth Experiences at a Four Year Postsecondary Institution

    Science.gov (United States)

    Greer, Renada D.

    2016-01-01

    Foster care youth face significant challenges to postsecondary educational success, especially while enrolled at four-year institutions. Foster care youth are absent of family support that their non-foster peers receive throughout the college experience. Without family support, foster care youth encounter greater challenges to persevere through…

  4. Low-Frequency Surface Backscattering Strengths Measured in the Critical Sea Test Experiments

    Science.gov (United States)

    2017-01-19

    simultaneously (via harmonics of the bubble pulse) (Urick, 1983). The CST SUS SSS experiments, processing, and results are documented in Ogden...series curves were obtained for individual shots and temporally aligned with respect to the shot- detonation time, and then linearly averaged to produce

  5. The MOX core critical experiments for LWRs and the analysis based on JENDL-3.2

    Energy Technology Data Exchange (ETDEWEB)

    Umano, Takuya [Nuclear Engineering Laboratory, Toshiba Corporation, Kawasaki, Kanagawa (Japan); Maruyama, Hiromi; Sasaki, Makoto; Tatsumi, Masahiro; Yamamoto, Toru; Matsu-ura, Hirofumi

    1999-03-01

    NUPEC and CEA have launched an extensive experimental program called MISTRAL to study highly moderated MOX cores for the advanced LWRs. The analyses with using SRAC system and MVP with JENDL-3.2 library are progressing on the experiments of the MISTRAL and the former EPICURE programs. Various comparisons have been made between calculation results and measurement values. (author)

  6. Momentum and Energy Transfer in an Ionospheric Critical Ionization Velocity Experiment

    DEFF Research Database (Denmark)

    Bolin, O.; Brenning, N.; Swenson, C. M.

    1995-01-01

    We present new data from the subpayload of the GRIT II ionospheric active injection experiment. The analysis made possible by these data provides a good understanding of the momentum transfer between the injected ions and the ambient ionosphere. It resolves the conflict between the two competing ...

  7. Ameloblastoma of the jaws: a critical reappraisal based on a 40-years single institution experience

    NARCIS (Netherlands)

    Hertog, D.; van der Waal, I.

    2010-01-01

    The 40-years of experience in a single institution with the treatment of previously untreated ameloblastoma have been reported, followed by a management protocol. Retrospectively, 25 consecutive patients treated between 1969 and 2009 have been analyzed. In 11 patients, a preoperative diagnosis of

  8. A Course in Critical Thinking for PhD Students in Biomolecular Sciences and Biotechnology: Classical Experiments in Biochemistry

    Directory of Open Access Journals (Sweden)

    Carlos B. Hirschberg

    2016-03-01

    Full Text Available This essay presents and discusses an eight-session seminar course designed to develop critical thinking skills in doctoral biochemistry students by exposing them to classical experiments in biochemistry. During each 2.5 session, different key topics of the discovery and development of biochemical concepts are discussed. Before each session, students are required to read the one or two classical papers. The size of the seminar course and the seating of the students are critical to make this a highly interactive environment for all students to participate in the critique and re-designing of key experiments, including control experiments, which helped formulate these classical concepts. Final student evaluation of the course’s goals has two equal components: Course participation and a final take home exam due two weeks after the course is completed. Together with the take home exam students are also required to write an evaluation of the course, preferably no longer than half a page. Students’ comments of the course have been uniformly positive. The author notes the sooner students are exposed to this manner of thinking, the better they will be equipped to choose an appropriate mentor and contribute creatively to attempt to solve the scientific problem of their PhD thesis.

  9. Kinematic dynamo action in square and hexagonal patterns.

    Science.gov (United States)

    Favier, B; Proctor, M R E

    2013-11-01

    We consider kinematic dynamo action in rapidly rotating Boussinesq convection just above onset. The velocity is constrained to have either a square or a hexagonal pattern. For the square pattern, large-scale dynamo action is observed at onset, with most of the magnetic energy being contained in the horizontally averaged component. As the magnetic Reynolds number increases, small-scale dynamo action becomes possible, reducing the overall growth rate of the dynamo. For the hexagonal pattern, the breaking of symmetry between up and down flows results in an effective pumping velocity. For intermediate rotation rates, this additional effect can prevent the growth of any mean-field dynamo, so that only a small-scale dynamo is eventually possible at large enough magnetic Reynolds number. For very large rotation rates, this pumping term becomes negligible, and the dynamo properties of square and hexagonal patterns are qualitatively similar. These results hold for both perfectly conducting and infinite magnetic permeability boundary conditions.

  10. Hexagonal Array Structure for 2d Nde Applications

    Science.gov (United States)

    Dziewierz, J.; Ramadas, S. N.; Gachagan, A.; O'Leary, R. L.

    2010-02-01

    This paper describes a combination of simulation and experimentation to evaluate the advantages offered by utilizing a hexagonal shaped array element in a 2D NDE array structure. The active material is a 1-3 connectivity piezoelectric composite structure incorporating triangular shaped pillars—each hexagonal array element comprising six triangular pillars. A combination of PZFlex, COMSOL and Matlab has been used to simulate the behavior of this device microstructure, for operation around 2.25 MHz, with unimodal behavior and low levels of mechanical cross-coupling predicted. Furthermore, the application of hexagonal array elements enables the array aperture to increase by approximately 30%, compared to a conventional orthogonal array matrix and hence will provide enhanced volumetric coverage and SNR. Prototype array configurations demonstrate good corroboration of the theoretically predicted mechanical cross-coupling between adjacent array elements (˜23 dB).

  11. Kinematic dynamo action in square and hexagonal patterns

    CERN Document Server

    Favier, B

    2013-01-01

    We consider kinematic dynamo action in rapidly rotating Boussinesq convection just above onset. The velocity is constrained to have either a square or a hexagonal pattern. For the square pattern, large-scale dynamo action is observed at onset, with most of the magnetic energy being contained in the horizontally-averaged component. As the magnetic Reynolds number increases, small-scale dynamo action becomes possible, reducing the overall growth rate of the dynamo. For the hexagonal pattern, the breaking of symmetry between up and down flows results in an effective pumping velocity. For intermediate rotation rates, this additional effect can prevent the growth of any mean-field dynamo, so that only a small-scale dynamo is eventually possible at large enough magnetic Reynolds number. For very large rotation rates, this pumping term becomes negligible, and the dynamo properties of square and hexagonal patterns are qualitatively similar. These results hold for both perfectly conducting and infinite magnetic permea...

  12. Additive Manufacturing of Dense Hexagonal Boron Nitride Objects

    Energy Technology Data Exchange (ETDEWEB)

    Marquez Rossy, Andres E [ORNL; Armstrong, Beth L [ORNL; Elliott, Amy M [ORNL; Lara-Curzio, Edgar [ORNL

    2017-05-12

    The feasibility of manufacturing hexagonal boron nitride objects via additive manufacturing techniques was investigated. It was demonstrated that it is possible to hot-extrude thermoplastic filaments containing uniformly distributed boron nitride particles with a volume concentration as high as 60% and that these thermoplastic filaments can be used as feedstock for 3D-printing objects using a fused deposition system. Objects 3D-printed by fused deposition were subsequently sintered at high temperature to obtain dense ceramic products. In a parallel study the behavior of hexagonal boron nitride in aqueous solutions was investigated. It was shown that the addition of a cationic dispersant to an azeotrope enabled the formulation of slurries with a volume concentration of boron nitride as high as 33%. Although these slurries exhibited complex rheological behavior, the results from this study are encouraging and provide a pathway for manufacturing hexagonal boron nitride objects via robocasting.

  13. Hexagon functions and the three-loop remainder function

    CERN Document Server

    Dixon, Lance J.; von Hippel, Matt; Pennington, Jeffrey

    2013-01-01

    We present the three-loop remainder function, which describes the scattering of six gluons in the maximally-helicity-violating configuration in planar N=4 super-Yang-Mills theory, as a function of the three dual conformal cross ratios. The result can be expressed in terms of multiple Goncharov polylogarithms. We also employ a more restricted class of "hexagon functions" which have the correct branch cuts and certain other restrictions on their symbols. We classify all the hexagon functions through transcendental weight five, using the coproduct for their Hopf algebra iteratively, which amounts to a set of first-order differential equations. The three-loop remainder function is a particular weight-six hexagon function, whose symbol was determined previously. The differential equations can be integrated numerically for generic values of the cross ratios, or analytically in certain kinematics limits, including the near-collinear and multi-Regge limits. These limits allow us to impose constraints from the operato...

  14. Studying the old masters of nursing: A critical student experience for developing nursing identity.

    Science.gov (United States)

    Kelly, Jacinta; Watson, Roger; Watson, James; Needham, Malachi; Driscoll, Laura O

    2017-09-01

    In the past professional identity in nursing was inculcated in students alongside institutional pride. A strong sense of professional identity is key to staff retention and recruitment and key to the delivery of quality nursing care. With the wholesale transfer of pre-registration nursing education to the third level sector, however, the reality is that students now divide their affiliations between university and healthcare institutions and professional identity development may be stymied. For this reason, there is need to explore alternative means of developing professional identity. Exposure to nursing history may counteract this tendency. Based on adult nursing students' reflections of a visit to the Florence Nightingale Museum, we discuss the potential of this activity in aiding development of critical professional identity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. From Memory Impairment to Posttraumatic Stress Disorder-Like Phenotypes: The Critical Role of an Unpredictable Second Traumatic Experience.

    Science.gov (United States)

    Finsterwald, Charles; Steinmetz, Adam B; Travaglia, Alessio; Alberini, Cristina M

    2015-12-02

    Arousal and stress critically regulate memory formation and retention. Increasing levels of stress produce an inverted U-shaped effect on cognitive performance, including the retention of explicit memories, and experiencing a severe stress during a traumatic event may lead to posttraumatic stress disorder (PTSD). The molecular mechanisms underlying the impairing effect of a severe stress on memory and the key contribution of traumatic experiences toward the development of PTSD are still unknown. Here, using increasing footshock intensities in an inhibitory avoidance paradigm, we reproduced the inverted U-shaped curve of memory performance in rats. We then show that the inverted U profile of memory performance correlates with an inverted U profile of corticosterone level in the circulation and of brain-derived neurotrophic factor, phosphorylated tropomyosin-receptor kinase B, and methyl CpG binding protein in the dorsal hippocampus. Furthermore, training with the highest footshock intensity (traumatic experience) led to a significant elevation of hippocampal glucocorticoid receptors. Exposure to an unpredictable, but not to a predictable, highly stressful reminder shock after a first traumatic experience resulted in PTSD-like phenotypes, including increased memory of the trauma, high anxiety, threat generalization, and resistance to extinction. Systemic corticosterone injection immediately after the traumatic experience, but not 3 d later, was sufficient to produce PTSD-like phenotypes. We suggest that, although after a first traumatic experience a suppression of the corticosterone-dependent response protects against the development of an anxiety disorder, experiencing more than one trauma (multiple hits) is a critical contributor to the etiology of PTSD. Copyright © 2015 the authors 0270-6474/15/3515903-13$15.00/0.

  16. Critical challenges in establishing emergency physician driven emergency departments – A Durban experience

    Directory of Open Access Journals (Sweden)

    R. Maharaj*

    2013-12-01

    The Western Cape experience has demonstrated the utility of an Emergency Physician led Emergency Department in improving the outcome of acute illness and trauma, which are strongly dependent on the early recognition of severity and the need for early intervention. We believe that a similar mind-set needs to be developed to service the increasing needs of the urban and peri-urban population served by eThekwini hospitals.

  17. Therapists’ experiences and perceptions of teamwork in neurological rehabilitation: Critical happenings in effective and ineffective teamwork

    OpenAIRE

    Suddick, K; De Souza, LH

    2007-01-01

    This article reports the second part of an exploratory study into occupational therapists` and physiotherapists` perceptions and experiences of team-work in neurological rehabilitation: the factors that were thought to influence effective and ineffective team-work, and the meaning behind effective and ineffective team work in neurological rehabilitation. The study was undertaken through semi-structured interviews of 10 therapists from three different neurological rehabilitation teams based in...

  18. Momentum and Energy Transfer in an Ionospheric Critical Ionization Velocity Experiment

    OpenAIRE

    Bolin, O.; Brenning, N.; Swenson, C. M.; Primdahl, Fritz

    1995-01-01

    We present new data from the subpayload of the GRIT II ionospheric active injection experiment. The analysis made possible by these data provides a good understanding of the momentum transfer between the injected ions and the ambient ionosphere. It resolves the conflict between the two competing models for the energy transfer from the newly created ions to hot electrons, while also giving a natural coupling between the energy and momentum transfer processes.

  19. Boosting critical thinking in a Project Management course: An active learning experience

    OpenAIRE

    Berbegal-Mirabent, Jasmina; Gil-Domènech, Dolors; Gieure, Clara

    2016-01-01

    [EN] The present study reports the experience of a project-based activity in which students are asked to plan an event. It is part of a Project Management course taught at Universitat Internacional de Catalunya, in a Masters’ Degree in Business Administration and Production Systems. The activity has been designed in such a way that it is expected to help students develop the acquired technical skills while it requires the use of different quantitative methods and tools to in...

  20. Experiences of fathering a baby admitted to neonatal intensive care: A critical gender analysis

    OpenAIRE

    Deeney, Kathleen; Lohan, Maria; Spence, Dale; Parkes, Jackie

    2012-01-01

    More fathers than ever before attend at the birth of their child and, internationally, there is a palpable pressure on maternity and neonatal services to include and engage with fathers. It is, thus, more important than ever to understand how fathers experience reproductive and neonatal health services and to understand how fathers can be successfully accommodated in these environments alongside their partners. In this paper we advance a theoretical framework for re-thinking fatherhood and he...

  1. Dogs’ recognition of human selfish and generous attitudes requires little but critical experience with people

    Science.gov (United States)

    Freidin, Esteban; Casanave, Emma B.

    2017-01-01

    There is some dispute regarding the role of experience in the development of dogs´ socio-cognitive abilities in their interaction with people. We sought to provide new evidence to this debate by comparing dogs with contrasting levels of experience with humans, in a task involving the discrimination of human generous and selfish attitudes. To this end, we compared the performance of adult family dogs against that of adult shelter dogs and puppies living in people´s homes. In training trials, the generous experimenter (G) signaled the bowl with food and allowed the dog to eat, whereas the selfish experimenter (S) also signaled the baited bowl, but she/he ate the food before the dog could have access to it. Then, subjects were allowed to freely choose between G and S in the choice test. The main finding was that adult subjects (both family and shelter dogs) developed a preference for G over S, but puppies did not. We conclude that the quality and/or quantity of everyday-contact with people did not affect the discrimination of human attitudes in the present protocol, but the amount of experience with people (in years) did matter. Finally, we discuss the relative role of domestication and ontogeny in the development of dogs´ socio-cognitive abilities. PMID:29045426

  2. Dogs' recognition of human selfish and generous attitudes requires little but critical experience with people.

    Science.gov (United States)

    Carballo, Fabricio; Freidin, Esteban; Casanave, Emma B; Bentosela, Mariana

    2017-01-01

    There is some dispute regarding the role of experience in the development of dogs´ socio-cognitive abilities in their interaction with people. We sought to provide new evidence to this debate by comparing dogs with contrasting levels of experience with humans, in a task involving the discrimination of human generous and selfish attitudes. To this end, we compared the performance of adult family dogs against that of adult shelter dogs and puppies living in people´s homes. In training trials, the generous experimenter (G) signaled the bowl with food and allowed the dog to eat, whereas the selfish experimenter (S) also signaled the baited bowl, but she/he ate the food before the dog could have access to it. Then, subjects were allowed to freely choose between G and S in the choice test. The main finding was that adult subjects (both family and shelter dogs) developed a preference for G over S, but puppies did not. We conclude that the quality and/or quantity of everyday-contact with people did not affect the discrimination of human attitudes in the present protocol, but the amount of experience with people (in years) did matter. Finally, we discuss the relative role of domestication and ontogeny in the development of dogs´ socio-cognitive abilities.

  3. Falsification of matching theory and confirmation of an evolutionary theory of behavior dynamics in a critical experiment.

    Science.gov (United States)

    McDowell, J J; Calvin, Olivia L; Hackett, Ryan; Klapes, Bryan

    2017-07-01

    Two competing predictions of matching theory and an evolutionary theory of behavior dynamics, and one additional prediction of the evolutionary theory, were tested in a critical experiment in which human participants worked on concurrent schedules for money (Dallery et al., 2005). The three predictions concerned the descriptive adequacy of matching theory equations, and of equations describing emergent equilibria of the evolutionary theory. Tests of the predictions falsified matching theory and supported the evolutionary theory. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Handling Worldwide LHC Computing Grid Critical Service Incidents : The infrastructure and experience behind nearly 5 years of GGUS ALARMs

    CERN Multimedia

    Dimou, M; Dulov, O; Grein, G

    2013-01-01

    In the Wordwide LHC Computing Grid (WLCG) project the Tier centres are of paramount importance for storing and accessing experiment data and for running the batch jobs necessary for experiment production activities. Although Tier2 sites provide a significant fraction of the resources a non-availability of resources at the Tier0 or the Tier1s can seriously harm not only WLCG Operations but also the experiments' workflow and the storage of LHC data which are very expensive to reproduce. This is why availability requirements for these sites are high and committed in the WLCG Memorandum of Understanding (MoU). In this talk we describe the workflow of GGUS ALARMs, the only 24/7 mechanism available to LHC experiment experts for reporting to the Tier0 or the Tier1s problems with their Critical Services. Conclusions and experience gained from the detailed drills performed in each such ALARM for the last 4 years are explained and the shift with time of Type of Problems met. The physical infrastructure put in place to ...

  5. Formation of hexagonal-wurtzite germanium by pulsed laser ablation

    Science.gov (United States)

    Zhang, Y.; Iqbal, Z.; Vijayalakshmi, S.; Qadri, S.; Grebel, H.

    2000-08-01

    A stable phase of relatively large hexagonal-wurtzite germanium (lonsdaleite) crystals (up to 10 μm) was formed when germanium was directly deposited at low pressure using pulsed ultraviolet laser ablation. Films were grown on various substrates at room temperature from a single crystal, cubic germanium target. Crystallites of the hexagonal-wurtzite phase of germanium were clearly identified using selected area electron diffraction. Further characterizations of the films were made using X-ray diffraction and confocal scanning micro-Raman spectroscopy.

  6. Communication: Water on hexagonal boron nitride from diffusion Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamdani, Yasmine S.; Ma, Ming; Michaelides, Angelos, E-mail: angelos.michaelides@ucl.ac.uk [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Alfè, Dario [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT (United Kingdom); Lilienfeld, O. Anatole von [Institute of Physical Chemistry and National Center for Computational Design and Discovery of Novel Materials, Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Argonne Leadership Computing Facility, Argonne National Laboratories, 9700 S. Cass Avenue Argonne, Lemont, Illinois 60439 (United States)

    2015-05-14

    Despite a recent flurry of experimental and simulation studies, an accurate estimate of the interaction strength of water molecules with hexagonal boron nitride is lacking. Here, we report quantum Monte Carlo results for the adsorption of a water monomer on a periodic hexagonal boron nitride sheet, which yield a water monomer interaction energy of −84 ± 5 meV. We use the results to evaluate the performance of several widely used density functional theory (DFT) exchange correlation functionals and find that they all deviate substantially. Differences in interaction energies between different adsorption sites are however better reproduced by DFT.

  7. Scaling Behavior and Beyond Equilibrium in the Hexagonal Manganites

    Directory of Open Access Journals (Sweden)

    S. M. Griffin

    2012-12-01

    Full Text Available We show that the improper ferroelectric phase transition in the multiferroic hexagonal manganites displays appropriate symmetry-breaking characteristics for testing the Kibble-Zurek mechanism originally proposed to describe early-universe phase transitions. We present an analysis of the Kibble-Zurek theory of topological defect formation applied to the hexagonal manganites, discuss the conditions determining the range of cooling rates in which Kibble-Zurek behavior is expected, and show that recent literature data are consistent with our predictions. Finally, we explore experimentally the crossover out of the Kibble-Zurek regime and find a surprising reversal of the scaling behavior.

  8. Multilayer DNA Origami Packed on Hexagonal and Hybrid Lattices

    DEFF Research Database (Denmark)

    Ke, Yonggang; Voigt, Niels Vinther; Shih, William M.

    2012-01-01

    “Scaffolded DNA origami” has been proven to be a powerful and efficient approach to construct two-dimensional or three-dimensional objects with great complexity. Multilayer DNA origami has been demonstrated with helices packing along either honeycomb-lattice geometry or square-lattice geometry. H...... DNA origami with honeycomb-lattice, square-lattice, and hexagonal-lattice packing of helices all in one design. The availability of hexagonal close-packing of helices extends our ability to build complex structures using DNA nanotechnology....

  9. Do out-of-body and near-death experiences point towards the reality of nonlocal consciousness? A critical evaluation

    Directory of Open Access Journals (Sweden)

    Pieter Craffert

    2015-07-01

    Full Text Available In recent years there was a steady flow of academic studies claiming that the mind or consciousness can function independently from a working brain. Such research is presented with great confidence as a scientific breakthrough and one that will alter received views on both humanity and the meaning of life as well as medical science in general and neuroscience in particular. In this article the three major streams of evidence for the existence of nonlocal consciousness are critically evaluated. Neither the testimonies of thousands of experients nor research on cardiac arrest patients or experimental research on veridical perception during out-of-body experiences at this stage provide sufficient evidence for such claims about nonlocal consciousness. Extraordinary claims about paradigm chances in the scientific world should be supported by uncontroversial and high quality evidence, which is currently not available.

  10. Three-Dimensional Electromagnetic Monte Carlo Particle-in-Cell Simulations of Critical Ionization Velocity Experiments in Space

    Science.gov (United States)

    Wang, J.; Biasca, R.; Liewer, P. C.

    1996-01-01

    Although the existence of the critical ionization velocity (CIV) is known from laboratory experiments, no agreement has been reached as to whether CIV exists in the natural space environment. In this paper we move towards more realistic models of CIV and present the first fully three-dimensional, electromagnetic particle-in-cell Monte-Carlo collision (PIC-MCC) simulations of typical space-based CIV experiments. In our model, the released neutral gas is taken to be a spherical cloud traveling across a magnetized ambient plasma. Simulations are performed for neutral clouds with various sizes and densities. The effects of the cloud parameters on ionization yield, wave energy growth, electron heating, momentum coupling, and the three-dimensional structure of the newly ionized plasma are discussed. The simulations suggest that the quantitative characteristics of momentum transfers among the ion beam, neutral cloud, and plasma waves is the key indicator of whether CIV can occur in space. The missing factors in space-based CIV experiments may be the conditions necessary for a continuous enhancement of the beam ion momentum. For a typical shaped charge release experiment, favorable CIV conditions may exist only in a very narrow, intermediate spatial region some distance from the release point due to the effects of the cloud density and size. When CIV does occur, the newly ionized plasma from the cloud forms a very complex structure due to the combined forces from the geomagnetic field, the motion induced emf, and the polarization. Hence the detection of CIV also critically depends on the sensor location.

  11. Spectrum of critical illness in undocumented border crossers. The Arizona-Mexico border experience.

    Science.gov (United States)

    Wong, Candy; Hsu, Wendy; Carr, Gordon E

    2015-03-01

    Approximately 150-250 migrants die each year while attempting to cross the border from Mexico to the Southwest United States. Many border crossers survive the journey, but some develop life-threatening medical complications. Such complications have been subject to little formal analysis. We sought to determine the causes of critical illness in this population and to analyze the hospital course and outcomes of these patients. We retrospectively identified border crossers admitted to the intensive care units (ICUs) of two major teaching hospitals in southern Arizona. We recorded admitting diagnoses, severity of illness, length of stay, resource use, discharge diagnoses, and mortality. Our investigation identified 55 admissions to adult ICUs between January 1, 2010 and December 31, 2012. The median age of patients was 27 years. The median hospital length of stay was 7 days, with a median ICU length of stay of 3 days. The median temperature on arrival to the emergency department was 36.8°C. The most common admission diagnoses included trauma (40), rhabdomyolysis (27), acute liver injury (25), dehydration (24), acute kidney injury (19), and encephalopathy (17). Thirteen patients presented with respiratory failure, six patients with severe sepsis, and two with septic shock. A total of 19 patients required ventilator support during their hospital stay, and 30 required at least one surgical intervention. One patient required renal replacement therapy. The median Acute Physiology and Chronic Health Evaluation II score was 6. All but one patient survived to discharge from the hospital. Border crossers are a unique population of young individuals exposed to high temperatures and extreme conditions. Our review of border crosser admissions showed that most patients demonstrated signs of dehydration and leukocytosis, despite a normal median temperature. The median ICU stay was short, despite a high number of patients requiring ventilator support and surgical intervention. Only

  12. The idealized quantum two-slit gedanken experiment revisited-Criticism and reinterpretation

    Energy Technology Data Exchange (ETDEWEB)

    El Naschie, Mohamed Saladin [Department of Physics, Alexandria University, Alexandria (Egypt); Department of Astrophysics, Cairo University, Cairo (Egypt); Department of Physics, Mansura University (Egypt)

    2006-02-01

    An idealized two-slit experiment is envisaged in which the hypothetical experimental set-up is constructed in such a way as to resemble a toy model giving information about the structure of quantum space-time itself. Thus starting from a very simple equation which may be interpreted as a physical realization of Goedel's undecidability theorem, we proceed to show that space-time is very likely to be akin to a fuzzy Kaehler-like manifold on the quantum level. This remarkable manifold transforms gradually into a classical space-time as we decrease the resolution in a way reversibly analogous to the processes of recovering classical space-time from the Riemannian space of general relativity. The paper's main philosophy is to emphasize that the quintessence of the two-slit experiment as well as Feynman's path integral could be given a different interpretation by altering our classical concept of space-time geometry and topology. In turn this would be in keeping with the development in theoretical physics since special and subsequently general relativity. In the final analysis it would seem that we have two different yet, from a positivistic philosophy viewpoint, completely equivalent alternatives to view quantum physics. Either we insist on what we see in our daily experiences, namely, a smooth four-dimensional space-time, and then accept, whether we like it or not, things such as probability waves and complex probabilities. Alternatively, we could see behind the facade of classical space-time a far more elaborate and highly complex fuzzy space-time with infinite hierarchical dimensions such as the so-called Fuzzy K3 or E-Infinity space-time and as a reward for this imaginative picture we can return to real probabilities without a phase and an almost classical picture with the concept of a particle's path restored. We say almost classical because non-linear dynamics and deterministic chaos have long shown the central role of randomness in classical

  13. An eye opening experience: A critical turning point in the life of a young woman with a severe visual impairment

    Directory of Open Access Journals (Sweden)

    Nikki Wedgwood

    2013-08-01

    Full Text Available Research on social inclusion often focuses on social exclusion. However, in order to gain greater insights into ways to facilitate social change, it is equally important to research the social inclusion of those normally excluded. Indeed, while one important purpose of studying disabilism is to catalogue and critique all its forms, another critical purpose is to better understand how disabilism can be resisted and/or ameliorated at individual and/or societal levels. Thus, it is equally important to understand when, why and how disabilism does not negatively impact the lives of people with impairments as well as when it does. This paper presents a single case study of Lynette, a young woman with a severe visual impairment who has a life-changing experience in an inclusive environment. In particular, it explores the impact of exclusive and inclusive contexts on Lynette's identity development as she transitions to adulthood. By juxtaposing Lynette's experiences of exclusion with those of inclusion, it highlights contexts in which there is a critical mass of people with impairments living alongside able-bodied people as a possible antecedent/impetus for greater social inclusion of people with impairments in society more generally.

  14. Diagnosis as the First Critical Point in the Treatment Trajectory: An Exploration of Operable Lung Cancer Patients' Lived Experiences.

    Science.gov (United States)

    Missel, Malene; Pedersen, Jesper H; Hendriksen, Carsten; Tewes, Marianne; Adamsen, Lis

    2015-01-01

    Significant advances have been made in the surgical treatment of lung cancer while patient experiences with diagnosis, treatment, and rehabilitation remain only sparsely researched. The objective of this study was to investigate how the diagnosis affects the daily lives of patients with operable lung cancer in order to identify their needs for care interventions from the point of diagnosis to hospitalization. We investigated patients' lived experiences from a longitudinal perspective at 4 critical time points during the treatment trajectory; we present here the findings from the first time point, diagnosis. Data were collected through interviews conducted 7 to 10 days following diagnosis of lung cancer. Data from 19 patients are included, and the analysis is based on Ricoeur's interpretation theory. The study framework is inspired by Schutz's phenomenological sociology. The findings are presented as themes that summarize and express the ways in which a diagnosis affects patients' daily lives: the cancer diagnosis comes as a shock, it changes everyday awareness; it presents the patient with an unfamiliar body, disturbs social relationships, forces the patient to face a new life situation, and demands one-on-one supportive care. Diagnosis is the first critical point for patients with operable lung cancer and disrupts their daily life. Patients need psychosocial support during the period from diagnosis to surgical intervention and patient-tailored one-on-one information. This article contributes to the knowledge base of support needs of lung cancer patients. Interventions aimed at supportive care during the period between diagnosis and surgical intervention should be researched.

  15. Fronts between hexagons and squares in a generalized Swift-Hohenberg equation

    DEFF Research Database (Denmark)

    Kubstrup, Christian; Herrero, H.; Pérez-García, C.

    1996-01-01

    Pinning effects in domain walls separating different orientations in patterns in nonequilibrium systems, are studied. Usually; theoretical studies consider perfect structures, but in experiments, point defects, grain boundaries, etc., always appear. The aim of this paper is to perform an analysis...... of the stability of fronts between hexagons and squares in a generalized Swift-Hohenberg model equation. We focus the analysis on pinned fronts between domains with different symmetries by using amplitude equations and by considering the small-scale structure in the pattern. The conditions for pinning effects...

  16. Broadening horizons: An exploration on the experiences of critical patients relatives

    Directory of Open Access Journals (Sweden)

    Agustina Díaz Sánchez

    2004-11-01

    Full Text Available The Purposes of this research were:1. To describe experiences from relatives of patients admitted in ICU and reanimation wards2. To analyze relationship between relatives and nurses working at ICU and reanimation wards3. To identify the demands of the relatives regarding nursing emotional support.Methodology: A qualitative study with an anthropological perspective was carried out. The fieldwork was carried out using two different techniques, participating observation and depth interviews. We paid special attention to the relationship between nurses and relatives, an essential skill for family support.Conclusions: An effective relationship between nurses and relatives is mandatory in order to implement an effective care giving. The support perceived by relatives is related to the relationship between them and the health professionals.

  17. Students’ Lived Experience on The Toughest Place to be a Binman in Critical Listening and Speaking 1 Class

    Directory of Open Access Journals (Sweden)

    Martha Pritzanda Pudhika

    2017-01-01

    Full Text Available The use of authentic videos has been implemented in Critical Listening and Speaking 1 (CLS 1 class. For instance, the use of The Toughest Place to be a Binman video. This video gives the students meaningful experiences. The students do not only get the material but they can also get social and environment issues that appear in the video. After watching the video, the students are expected to have their own experience towards the use of The Toughest Place to be a Binman video in CLS 1. Therefore, the aim of this research was to have a better understanding on the students’ lived experience on The Toughest Place to be a Binman in CLS 1. This research employed phenomenology study because this research focused on the students’ lived experience. As a research result, the research showed the participants’ stories and the interpretation. There were four emerging themes that appeared from the data processed. Those were meaningfulness, compassion, motivation, and action. Those four themes connected between each other.   DOI: https://doi.org/10.24071/llt.2016.190206

  18. Critical role of peripheral drug actions in experience-dependent changes in nucleus accumbens glutamate release induced by intravenous cocaine

    Science.gov (United States)

    Wakabayashi, Ken T.; Kiyatkin, Eugene A.

    2015-01-01

    Recent studies reveal that cocaine experience results in persistent neuroadaptive changes within glutamate (Glu) synapses in brain areas associated with drug reward. However, it remains unclear whether cocaine affects Glu release in drug-naive animals and how it is altered by drug experience. By using high-speed amperometry with enzyme-based and enzyme-free biosensors in freely moving rats, we show that an initial intravenous cocaine injection at a low self-administering dose (1 mg/kg) induces rapid, small and transient Glu release in the nucleus accumbens shell (NAc), which with subsequent injections rapidly becomes a much stronger, two-component increase. Using cocaine-methiodide, cocaine’s analogue that does not cross the blood-brain barrier, we confirm that the initial cocaine-induced Glu release in the NAc has a peripheral neural origin. Unlike cocaine, Glu responses induced by cocaine-methiodide rapidly habituate following repeated exposure. However, after cocaine experience this drug induces cocaine-like Glu responses. Hence, the interoceptive actions of cocaine, which essentially precede its direct actions in the brain, play a critical role in experience-dependent alterations in Glu release, cocaine-induced neural sensitization and may contribute to cocaine addiction. PMID:24111505

  19. Dislocation Dynamics Simulations of Junctions in Hexagonal Close-Packed Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Wu, C; Aubry, S; Chung, P; Arsenlis, A

    2011-12-05

    The formation and strength of dislocations in the hexagonal closed packed material beryllium are studied through dislocation junctions and the critical stress required to break them. Dislocation dynamics calculations (using the code ParaDiS) of junction maps are compared to an analytical line tension approximation in order to validate our model. Results show that the two models agree very well. Also the critical shear stress necessary to break 30{sup o} - 30{sup o} and 30{sup o} - 90{sup o} dislocation junctions is computed numerically. Yield surfaces are mapped out for these junctions to describe their stability regions as function of resolved shear stresses on the glide planes. The example of two non-coplanar binary dislocation junctions with slip planes [2-1-10] (01-10) and [-12-10] (0001) corresponding to a prismatic and basal slip respectively is chosen to verify and validate our implementation.

  20. Students' perceptions of effective learning experiences in dental school: a qualitative study using a critical incident technique.

    Science.gov (United States)

    Victoroff, Kristin Zakariasen; Hogan, Sarah

    2006-02-01

    Students' views of their educational experience can be an important source of information for curriculum assessment. Although quantitative methods, particularly surveys, are frequently used to gather such data, fewer studies have employed qualitative methods to examine students' dental education experiences. The purpose of this study is to explore characteristics of effective learning experiences in dental school using a qualitative method. All third-year (seventy) and fourth-year (seventy) dental students enrolled in one midwestern dental school were invited to participate. Fifty-three dental students (thirty-five male and eighteen female; thirty-two third-year and twenty-one fourth-year) were interviewed using a critical incident interview technique. Each student was asked to describe a specific, particularly effective learning incident that he or she had experienced in dental school and a specific, particularly ineffective learning incident, for comparison. Each interview was audiotaped. Students were assured that only the interviewer and one additional researcher would have access to the tapes. Data analysis resulted in identification of key themes in the data describing characteristics of effective learning experiences. The following characteristics of effective learning experiences were identified: 1) instructor characteristics (personal qualities, "checking-in" with students, and an interactive style); 2) characteristics of the learning process (focus on the "big picture," modeling and demonstrations, opportunities to apply new knowledge, high-quality feedback, focus, specificity and relevance, and peer interactions); and 3) learning environment (culture of the learning environment, technology). Common themes emerged across a wide variety of learning incidents. Although additional research is needed, the characteristics of effective learning experiences identified in this study may have implications for individual course design and for the dental school

  1. Forecast of criticality experiments and experimental programs needed to support nuclear operations in the United States of America: 1994--1999

    Energy Technology Data Exchange (ETDEWEB)

    Rutherford, D.

    1994-03-01

    This Forecast is generated by the Chair of the Experiment Needs Identification Workgroup (ENIWG), with input from Department of Energy and the nuclear community. One of the current concerns addressed by ENIWG was the Defense Nuclear Facilities Safety Board`s Recommendation 93-2. This Recommendation delineated the need for a critical experimental capability, which includes (1) a program of general-purpose experiments, (2) improving the information base, and (3) ongoing departmental programs. The nuclear community also recognizes the importance of criticality theory, which, as a stepping stone to computational analysis and safety code development, needs to be benchmarked against well-characterized critical experiments. A summary project of the Department`s needs with respect to criticality information includes (1) hands-on training, (2) criticality and nuclear data, (3) detector systems, (4) uranium- and plutonium-based reactors, and (5) accident analysis. The Workgroup has evaluated, prioritized, and categorized each proposed experiment and program. Transportation/Applications is a new category intended to cover the areas of storage, training, emergency response, and standards. This category has the highest number of priority-1 experiments (nine). Facilities capable of performing experiments include the Los Alamos Critical Experiment Facility (LACEF) along with Area V at Sandia National Laboratory. The LACEF continues to house the most significant collection of critical assemblies in the Western Hemisphere. The staff of this facility and Area V are trained and certified, and documentation is current. ENIWG will continue to work with the nuclear community to identify and prioritize experiments because there is an overwhelming need for critical experiments to be performed for basic research and code validation.

  2. A low cost route to hexagonal mesostructured carbon molecular sieves.

    Science.gov (United States)

    Kim, S S; Pinnavaia, T J

    2001-12-07

    A mesoporous carbon molecular sieve with a hexagonal framework structure (denoted C-MSU-H) has been prepared using a MSU-H silica template that can be assembled from a low cost soluble silicate precursor at near-neutral pH conditions.

  3. Electrochemical and SEM properties of Co 2 ion in hexagonal ...

    Indian Academy of Sciences (India)

    The electrode parameters of Co(II) ion in hexagonal meso phase of the lyotropic liquid crystal ternary system (pluronic P84/cobalt/-xylene) is determined using cyclic voltammetry, deduced convolutive voltammetry and chronoamperometry techniques. The morphology of nanostructured deposited films of Co2+ ion in ...

  4. Epitaxial hexagonal materials on IBAD-textured substrates

    Science.gov (United States)

    Matias, Vladimir; Yung, Christopher

    2017-08-15

    A multilayer structure including a hexagonal epitaxial layer, such as GaN or other group III-nitride (III-N) semiconductors, a oriented textured layer, and a non-single crystal substrate, and methods for making the same. The textured layer has a crystalline alignment preferably formed by the ion-beam assisted deposition (IBAD) texturing process and can be biaxially aligned. The in-plane crystalline texture of the textured layer is sufficiently low to allow growth of high quality hexagonal material, but can still be significantly greater than the required in-plane crystalline texture of the hexagonal material. The IBAD process enables low-cost, large-area, flexible metal foil substrates to be used as potential alternatives to single-crystal sapphire and silicon for manufacture of electronic devices, enabling scaled-up roll-to-roll, sheet-to-sheet, or similar fabrication processes to be used. The user is able to choose a substrate for its mechanical and thermal properties, such as how well its coefficient of thermal expansion matches that of the hexagonal epitaxial layer, while choosing a textured layer that more closely lattice matches that layer.

  5. Lattice-polarity-driven epitaxy of hexagonal semiconductor nanowires

    KAUST Repository

    Wang, Ping

    2015-12-22

    Lattice-polarity-driven epitaxy of hexagonal semiconductor nanowires (NWs) is demonstrated on InN NWs. In-polarity InN NWs form typical hexagonal structure with pyramidal growth front, whereas N-polarity InN NWs slowly turn to the shape of hexagonal pyramid and then convert to an inverted pyramid growth, forming diagonal pyramids with flat surfaces and finally coalescence with each other. This contrary growth behavior driven by lattice-polarity is most likely due to the relatively lower growth rate of the (0001 ̅) plane, which results from the fact that the diffusion barriers of In and N adatoms on the (0001) plane (0.18 and 1.0 eV, respectively) are about two-fold larger in magnitude than those on the (0001 ̅) plane (0.07 and 0.52 eV), as calculated by first-principles density functional theory (DFT). The formation of diagonal pyramids for the N-polarity hexagonal NWs affords a novel way to locate quantum dot in the kink position, suggesting a new recipe for the fabrication of dot-based devices.

  6. Influence of strontium on the cubic to ordered hexagonal phase ...

    Indian Academy of Sciences (India)

    ... Lecture Workshops · Refresher Courses · Symposia. Home; Journals; Bulletin of Materials Science; Volume 23; Issue 6. Influence of strontium on the cubic to ordered hexagonal phase transformation in barium magnesium niobate. M Thirumal A K Ganguli. Phase Transitions Volume 23 Issue 6 December 2000 pp 495-498 ...

  7. Hexagonal Boron Nitride Self-Launches Hyperbolic Phonon Polaritons

    NARCIS (Netherlands)

    Gilburd, Leonid; Kim, Kris S.; Ho, Kevin; Trajanoski, Daniel; Maiti, Aniket; Halverson, Duncan; de Beer, Sissi; Walker, Gilbert C.

    2017-01-01

    Hexagonal boron nitride (hBN) is a 2D material that supports traveling waves composed of material vibrations and light, and is attractive for nanoscale optical devices that function in the infrared. However, the only current method of launching these traveling waves requires the use of a metal

  8. Crystallization of M-type hexagonal ferrites from mechanically ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 29; Issue 5. Crystallization of -type hexagonal ferrites from mechanically activated mixtures of barium carbonate and goethite. J Temuujin M Aoyama M Senna T Masuko C Ando H Kishi A Minjigmaa. Ceramics and Glasses Volume 29 Issue 5 October 2006 pp 457-460 ...

  9. Free vibration of hexagonal panels supported at discrete points

    Science.gov (United States)

    Wu, K. Chauncey

    1991-01-01

    An analytical study to determine the structural dynamic behavior of a hexagonal panel with discrete simple supports is presented. These panels are representative of the facets of a precision reflector surface. The effects of both support point location and panel curvature on the lowest natural frequency of the panel are quantified and discussed.

  10. Spin transport in fully hexagonal boron nitride encapsulated graphene

    NARCIS (Netherlands)

    Gurram, M.; Omar, S.; Zihlmann, S.; Makk, P.; Schoenenberger, C.; van Wees, B. J.

    2016-01-01

    We study fully hexagonal boron nitride (hBN) encapsulated graphene spin valve devices at room temperature. The device consists of a graphene channel encapsulated between two crystalline hBN flakes: thick-hBN flake as a bottom gate dielectric substrate which masks the charge impurities from SiO2/Si

  11. Epitaxial hexagonal materials on IBAD-textured substrates

    Energy Technology Data Exchange (ETDEWEB)

    Matias, Vladimir; Yung, Christopher

    2017-08-15

    A multilayer structure including a hexagonal epitaxial layer, such as GaN or other group III-nitride (III-N) semiconductors, a <111> oriented textured layer, and a non-single crystal substrate, and methods for making the same. The textured layer has a crystalline alignment preferably formed by the ion-beam assisted deposition (IBAD) texturing process and can be biaxially aligned. The in-plane crystalline texture of the textured layer is sufficiently low to allow growth of high quality hexagonal material, but can still be significantly greater than the required in-plane crystalline texture of the hexagonal material. The IBAD process enables low-cost, large-area, flexible metal foil substrates to be used as potential alternatives to single-crystal sapphire and silicon for manufacture of electronic devices, enabling scaled-up roll-to-roll, sheet-to-sheet, or similar fabrication processes to be used. The user is able to choose a substrate for its mechanical and thermal properties, such as how well its coefficient of thermal expansion matches that of the hexagonal epitaxial layer, while choosing a textured layer that more closely lattice matches that layer.

  12. [Transphenoidal endoscopic approaches for pituitary adenomas: a critical review of our experience].

    Science.gov (United States)

    Armengot, Miguel; Gallego, José María; Gómez, María José; Barcia, Juan Antonio; Basterra, Jorge; Barcia, Carlos

    2011-01-01

    The surgical approach to the pituitary fossae has evolved from transcranial to sublabial and transseptal microscopic ones, up to the current transsphenoidal endoscopic approach. To present our experience in the transnasal transsphenoidal approach for pituitary adenomas and the modifications introduced to improve tumoral resection and to lower iatrogenia. Over nine years, we operated on 37 patients with pituitary adenomas using the transsphenoidal endoscopic approach. We utilised optical lens of 0° (approach) and 30° (adenoma resection), optic navigator, surgical instruments for nasal endoscopic and pituitary surgery. During the neurosurgical step, the endoscope was fixed by an articulated arm. We acceded to the pituitary fossae by a bilateral sphenoidotomy. Sphenoid pneumatisation was sufficient in all the patients. The more common postoperative complications were diabetes insipidus and endocrinology deficiencies. Postoperative rhinoliquorrhea affected only one patient. No alterations of nasal fossae were observed. Mean patient hospitalisation was five days. Transsphenoidal endoscopic approach guided by navigator gives significant advantages: Shorter operating time and fewer complications, greater safety and preservation of the nasal passages. Resecting the sphenoidal rostrum and a fragment of adjacent nasal septum improves surgical instrument management into the pituitary fossae and therefore adenoma resection. Endoscope fixation stabilises the vision and allows the second surgeon to help more effectively. Copyright © 2010 Elsevier España, S.L. All rights reserved.

  13. Thermal hydraulic test for reactor safety system - Critical heat flux experiment and development of prediction models

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Soon Heung; Baek, Won Pil; Yang, Soo Hyung; No, Chang Hyun [Korea Advanced Institute of Science and Technology, Taejon (Korea)

    2000-04-01

    To acquire CHF data through the experiments and develop prediction models, research was conducted. Final objectives of research are as follows: 1) Production of tube CHF data for low and middle pressure and mass flux and Flow Boiling Visualization. 2) Modification and suggestion of tube CHF prediction models. 3) Development of fuel bundle CHF prediction methodology base on tube CHF prediction models. The major results of research are as follows: 1) Production of the CHF data for low and middle pressure and mass flux. - Acquisition of CHF data (764) for low and middle pressure and flow conditions - Analysis of CHF trends based on the CHF data - Assessment of existing CHF prediction methods with the CHF data 2) Modification and suggestion of tube CHF prediction models. - Development of a unified CHF model applicable for a wide parametric range - Development of a threshold length correlation - Improvement of CHF look-up table using the threshold length correlation 3) Development of fuel bundle CHF prediction methodology base on tube CHF prediction models. - Development of bundle CHF prediction methodology using correction factor. 11 refs., 134 figs., 25 tabs. (Author)

  14. HTR-PROTEUS Pebble Bed Experimental Program Cores 1, 1A, 2, and 3: Hexagonal Close Packing with a 1:2 Moderator-to-Fuel Pebble Ratio

    Energy Technology Data Exchange (ETDEWEB)

    John D. Bess; Barbara H. Dolphin; James W. Sterbentz; Luka Snoj; Igor Lengar; Oliver Köberl

    2012-03-01

    In its deployment as a pebble bed reactor (PBR) critical facility from 1992 to 1996, the PROTEUS facility was designated as HTR-PROTEUS. This experimental program was performed as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on the Validation of Safety Related Physics Calculations for Low Enriched HTGRs. Within this project, critical experiments were conducted for graphite moderated LEU systems to determine core reactivity, flux and power profiles, reaction-rate ratios, the worth of control rods, both in-core and reflector based, the worth of burnable poisons, kinetic parameters, and the effects of moisture ingress on these parameters. Four benchmark experiments were evaluated in this report: Cores 1, 1A, 2, and 3. These core configurations represent the hexagonal close packing (HCP) configurations of the HTR-PROTEUS experiment with a moderator-to-fuel pebble ratio of 1:2. Core 1 represents the only configuration utilizing ZEBRA control rods. Cores 1A, 2, and 3 use withdrawable, hollow, stainless steel control rods. Cores 1 and 1A are similar except for the use of different control rods; Core 1A also has one less layer of pebbles (21 layers instead of 22). Core 2 retains the first 16 layers of pebbles from Cores 1 and 1A and has 16 layers of moderator pebbles stacked above the fueled layers. Core 3 retains the first 17 layers of pebbles but has polyethylene rods inserted between pebbles to simulate water ingress. The additional partial pebble layer (layer 18) for Core 3 was not included as it was used for core operations and not the reported critical configuration. Cores 1, 1A, 2, and 3 were determined to be acceptable benchmark experiments.

  15. HTR-PROTEUS Pebble Bed Experimental Program Cores 1, 1A, 2, and 3: Hexagonal Close Packing with a 1:2 Moderator-to-Fuel Pebble Ratio

    Energy Technology Data Exchange (ETDEWEB)

    John D. Bess; Barbara H. Dolphin; James W. Sterbentz; Luka Snoj; Igor Lengar; Oliver Köberl

    2013-03-01

    In its deployment as a pebble bed reactor (PBR) critical facility from 1992 to 1996, the PROTEUS facility was designated as HTR-PROTEUS. This experimental program was performed as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on the Validation of Safety Related Physics Calculations for Low Enriched HTGRs. Within this project, critical experiments were conducted for graphite moderated LEU systems to determine core reactivity, flux and power profiles, reaction-rate ratios, the worth of control rods, both in-core and reflector based, the worth of burnable poisons, kinetic parameters, and the effects of moisture ingress on these parameters. Four benchmark experiments were evaluated in this report: Cores 1, 1A, 2, and 3. These core configurations represent the hexagonal close packing (HCP) configurations of the HTR-PROTEUS experiment with a moderator-to-fuel pebble ratio of 1:2. Core 1 represents the only configuration utilizing ZEBRA control rods. Cores 1A, 2, and 3 use withdrawable, hollow, stainless steel control rods. Cores 1 and 1A are similar except for the use of different control rods; Core 1A also has one less layer of pebbles (21 layers instead of 22). Core 2 retains the first 16 layers of pebbles from Cores 1 and 1A and has 16 layers of moderator pebbles stacked above the fueled layers. Core 3 retains the first 17 layers of pebbles but has polyethylene rods inserted between pebbles to simulate water ingress. The additional partial pebble layer (layer 18) for Core 3 was not included as it was used for core operations and not the reported critical configuration. Cores 1, 1A, 2, and 3 were determined to be acceptable benchmark experiments.

  16. Twenty years' single-center experience with mechanical heart valves: a critical review of anticoagulation policy.

    Science.gov (United States)

    Van Nooten, Guido J; Caes, Frank; François, Katrien; Van Bellleghem, Yves; Bové, Thierry; Vandenplas, Guy; Taeymans, Yves

    2012-01-01

    Since January 1990, a variety of mechanical valves (St. Jude Medical, CarboMedics, ATS Medical) have been implanted routinely at the authors' institution. The study aim was to analyze, retrospectively, the 20-year clinical results of those mechanical valves, and to challenge the anticoagulation policy employed over the years. Between January 1990 and December 2008, a total of 2,108 mechanical valves was inserted into 1,887 consecutive patients (1,346 aortic, 725 mitral, 27 tricuspid, 10 pulmonary). The mean age of the patients was 63 +/- 13.2 years, and the majority (61%) were males. Preoperatively, 71% the patients were in NYHA class > or = III (average 3.01). The most frequent comorbidities included: atrial fibrillation (n = 594), coronary disease (n = 567) and diabetes (n = 398). The follow up (99% complete) totaled 13,721 patient-years (pt-yr), and ranged from 12 to 241 months (average 84 months). In-hospital mortality was 5.2% (n = 98, 14 valve-related). Of the 629 late deaths, the majority were cardiac (n = 276). Survival (Kaplan-Meier estimation) was significantly better for aortic valve patients compared to mitral or multiple valve replacement (Mantel-Cox, p valve thrombosis 0.31, thromboembolism 1.08, and bleeding 0.91. However, as repeated events occurred in several patients, the hazard function was not constant. Multivariate analysis (Cox regression model) showed age > 70 years (p or = III (p II as significant risk factors for thromboembolism, while long-acting coumadin and NYHA class > II were significant risk factors for bleeding. This 20-year experience demonstrated excellent clinical outcomes for patients with mechanical prostheses, with no valve structural failure and an acceptable incidence of adverse events. INR values between 2-2.5 for aortic valve patients, and 3-3.5 for mitral valve patients, yielded the fewest major adverse events.

  17. Experience-dependent emergence of beta and gamma band oscillations in the primary visual cortex during the critical period.

    Science.gov (United States)

    Chen, Guang; Rasch, Malte J; Wang, Ran; Zhang, Xiao-hui

    2015-12-09

    Neural oscillatory activities have been shown to play important roles in neural information processing and the shaping of circuit connections during development. However, it remains unknown whether and how specific neural oscillations emerge during a postnatal critical period (CP), in which neuronal connections are most substantially modified by neural activity and experience. By recording local field potentials (LFPs) and single unit activity in developing primary visual cortex (V1) of head-fixed awake mice, we here demonstrate an emergence of characteristic oscillatory activities during the CP. From the pre-CP to CP, the peak frequency of spontaneous fast oscillatory activities shifts from the beta band (15-35 Hz) to the gamma band (40-70 Hz), accompanied by a decrease of cross-frequency coupling (CFC) and broadband spike-field coherence (SFC). Moreover, visual stimulation induced a large increase of beta-band activity but a reduction of gamma-band activity specifically from the CP onwards. Dark rearing of animals from the birth delayed this emergence of oscillatory activities during the CP, suggesting its dependence on early visual experience. These findings suggest that the characteristic neuronal oscillatory activities emerged specifically during the CP may represent as neural activity trait markers for the experience-dependent maturation of developing visual cortical circuits.

  18. Resolution comparison between integral-imaging-based hologram synthesis methods using rectangular and hexagonal lens arrays.

    Science.gov (United States)

    Chen, Ni; Yeom, Jiwoon; Jung, Jae-Hyun; Park, Jae-Hyeung; Lee, Byoungho

    2011-12-19

    We compare the resolution of the hologram reconstruction synthesis methods based on integral imaging using rectangular and hexagonal lens arrays. By using a hexagonal lens array instead of conventional rectangular lens array, the three-dimensional objects are sampled with hexagonal grids. Due to more efficient sampling of the hexagonal grid, the resolution of the reconstructed object is higher compared with the case of using rectangular lens array. We analyze the resolution enhancement of the hologram reconstruction quantitatively and verify it experimentally.

  19. An Examination of Muscle Activation and Power Characteristics While Performing the Deadlift Exercise With Straight and Hexagonal Barbells.

    Science.gov (United States)

    Camara, Kevin D; Coburn, Jared W; Dunnick, Dustin D; Brown, Lee E; Galpin, Andrew J; Costa, Pablo B

    2016-05-01

    The deadlift exercise is commonly performed to develop strength and power, and to train the lower-body and erector spinae muscle groups. However, little is known about the acute training effects of a hexagonal barbell vs. a straight barbell when performing deadlifts. Therefore, the purpose of this study was to examine the hexagonal barbell in comparison with the straight barbell by analyzing electromyography (EMG) from the vastus lateralis, biceps femoris, and erector spinae, as well as peak force, peak power, and peak velocity using a force plate. Twenty men with deadlifting experience volunteered to participate in the study. All participants completed a 1 repetition maximum (1RM) test with each barbell on 2 separate occasions. Three repetitions at 65 and 85% 1RM were performed with each barbell on a third visit. The results revealed that there was no significant difference for 1RM values between the straight and hexagonal barbells (mean ± SD in kg = 181.4 ± 27.3 vs. 181.1 ± 27.6, respectively) (p > 0.05). Significantly greater normalized EMG values were found from the vastus lateralis for both the concentric (1.199 ± 0.22) and eccentric (0.879 ± 0.31) phases of the hexagonal-barbell deadlift than those of the straight-barbell deadlift (0.968 ± 0.22 and 0.559 ± 1.26), whereas the straight-barbell deadlift led to significantly greater EMG values from the bicep femoris during the concentric phase (0.835 ± 0.19) and the erector spinae (0.753 ± 0.28) during the eccentric phase than the corresponding values for the hexagonal-barbell deadlift (0.723 ± 0.20 and 0.614 ± 0.21) (p ≤ 0.05). In addition, the hexagonal-barbell deadlift demonstrated significantly greater peak force (2,553.20 ± 371.52 N), peak power (1,871.15 ± 451.61 W), and peak velocity (0.805 ± 0.165) values than those of the straight-barbell deadlift (2,509.90 ± 364.95 N, 1,639.70 ± 361.94 W, and 0.725 ± 0.138 m·s, respectively) (p ≤ 0.05). These results suggest that the barbells led

  20. IEA Wind Task 23 Offshore Wind Technology and Deployment. Subtask 1 Experience with Critical Deployment Issues. Final Technical Report

    DEFF Research Database (Denmark)

    Lemming, Jørgen Kjærgaard

    The final report for IEA Wind Task 23, Offshore Wind Energy Technology and Deployment, is made up of two separate reports: Subtask 1: Experience with Critical Deployment Issues and Subtask 2: Offshore Code Comparison Collaborative (OC3). The Subtask 1 report included here provides background...... information and objectives of Task 23. It specifically discusses ecological issues and regulation, electrical system integration and offshore wind, external conditions, and key conclusions for Subtask 1. The Subtask 2 report covers OC3 background information and objectives of the task, OC3 benchmark exercises...... of aero-elastic offshore wind turbine codes, monopile foundation modeling, tripod support structure modeling, and Phase IV results regarding floating wind turbine modeling....

  1. Nurses' experiences of caring for critically ill, non-sedated, mechanically ventilated patients in the Intensive Care Unit

    DEFF Research Database (Denmark)

    Laerkner, Eva; Egerod, Ingrid; Hansen, Helle Ploug

    2015-01-01

    a protocol of no sedation is implemented. Data were generated during participant observation in practice and by interviews with 16 nurses. Data were analysed using thematic interpretive description. FINDINGS: An overall theme emerged: "Demanding, yet rewarding". The demanding aspects of caring for more awake...... was valued. Caring for more awake non-sedated patients required the nurses to act at the interface between ambiguous possibilities and needs, which was perceived as both demanding and rewarding.......OBJECTIVE: The objective was to explore nurses' experiences of caring for non-sedated, critically ill patients requiring mechanical ventilation. DESIGN AND SETTING: The study had a qualitative explorative design and was based on 13 months of fieldwork in two intensive care units in Denmark where...

  2. Francesco Bonatelli: A Critical (Experience-grounded Approach to Consciousness and Human Subject between Spiritualism and Positivism

    Directory of Open Access Journals (Sweden)

    Davide Poggi

    2016-08-01

    Full Text Available In the context of nineteenth-century philosophical reflection, Francesco Bonatelli (1830-1911 set himself the following goal: to defend the pillars of Spiritualism (the existence of a human subject with intellectual or supra-sensitive cognitive functions and ontology (the notions of esse and substantia through an careful examination of psychic contents and consciousness, while closely contesting both the psychology and the psychophysiology of Positivism (without rejecting its results in toto and Spiritualism itself (with all its uncritical assumptions and unnecessary metaphysical speculations. In works such as Pensiero e conoscenza (1864, La coscienza e il meccanesimo interiore (1872 and Percezione e pensiero (1892-1895 Bonatelli puts forward his “critical experience-grounded philosophy” and proposes an original solution to the problem of the nature of the subject, (self-consciousness and its unity, using an analysis of “sentiments” to reveal the inseparable tangle of the cognitive and ontological dimensions of the self.

  3. Time-critical database condition data handling in the CMS experiment during the first data taking period

    CERN Document Server

    Di Guida, Salvatore

    2011-01-01

    Automatic, synchronous and of course reliable population of the condition databases is critical for the correct operation of the online selection as well as of the offline reconstruction and analysis of data. In this complex infrastructure, monitoring and fast detection of errors is a very challenging task. To recover the system and to put it in a safe state requires spotting a faulty situation within strict time constraints. We will describe here the system put in place in the CMS experiment to automate the processes that populate centrally the Condition Databases and make condition data promptly available both online for the high-level trigger and offline for reconstruction. The data are automatically collected using centralized jobs or are ``dropped'' by the users in dedicate services (offline and online drop-box), which synchronize them and take care of writing them into the online database. Then they are automatically streamed to the offline database, and thus are immediately acce...

  4. INTEGRAL BENCHMARKS AVAILABLE THROUGH THE INTERNATIONAL REACTOR PHYSICS EXPERIMENT EVALUATION PROJECT AND THE INTERNATIONAL CRITICALITY SAFETY BENCHMARK EVALUATION PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    J. Blair Briggs; Lori Scott; Enrico Sartori; Yolanda Rugama

    2008-09-01

    Interest in high-quality integral benchmark data is increasing as efforts to quantify and reduce calculational uncertainties accelerate to meet the demands of next generation reactor and advanced fuel cycle concepts. The International Reactor Physics Experiment Evaluation Project (IRPhEP) and the International Criticality Safety Benchmark Evaluation Project (ICSBEP) continue to expand their efforts and broaden their scope to identify, evaluate, and provide integral benchmark data for method and data validation. Benchmark model specifications provided by these two projects are used heavily by the international reactor physics, nuclear data, and criticality safety communities. Thus far, 14 countries have contributed to the IRPhEP, and 20 have contributed to the ICSBEP. The status of the IRPhEP and ICSBEP is discussed in this paper, and the future of the two projects is outlined and discussed. Selected benchmarks that have been added to the IRPhEP and ICSBEP handbooks since PHYSOR’06 are highlighted, and the future of the two projects is discussed.

  5. Hybridization and Field Driven Phase Transitions in Hexagonally Warped Topological Insulators

    Science.gov (United States)

    Menon, Anirudha; Chowdhury, Debashree; Basu, Banasri

    2016-09-01

    In this paper, we discuss the role of material parameters and external field effects on a thin film topological insulator(TI) in the context of quantum phase transition (QPT). First, we consider an in-plane tilted magnetic field and determine the band structure of the surface states as a function of the tilt angle. We show that the presence of either a hybridization term or hexagonal warping or a combination of both leads to a semi-metal to insulator phase transition which is facilitated by their 𝒫𝒯 symmetry breaking character. We then note that while the introduction of an electric field does not allow for this QPT since it does not break 𝒫𝒯 symmetry, it can be used in conjunction with a tunneling element to reach a phase transition efficiently. The corresponding critical point is then nontrivially dependent on the electric field, which is pointed out here. Then, we demonstrate that including a hexagonal warping term leads to an immediate 𝒫𝒯 symmetry violating QPT.

  6. Electric field driven evolution of topological domain structure in hexagonal manganites

    Science.gov (United States)

    Yang, K. L.; Zhang, Y.; Zheng, S. H.; Lin, L.; Yan, Z. B.; Liu, J.-M.; Cheong, S.-W.

    2017-10-01

    Controlling and manipulating the topological state represents an important topic in condensed matters for both fundamental researches and applications. In this work, we focus on the evolution of a real-space topological domain structure in hexagonal manganites driven by electric field, using the analytical and numerical calculations based on the Ginzburg-Landau theory. It is revealed that the electric field drives a transition of the topological domain structure from the type-I pattern to the type-II one. In particular, it is identified that a high electric field can enforce the two antiphase-plus-ferroelectric (AP +FE ) domain walls with Δ Φ =π /3 to approach each other and to merge into one domain wall with Δ Φ = 2 π /3 eventually if the electric field is sufficiently high, where Δ Φ is the difference in the trimerization phase between two neighboring domains. Our simulations also reveal that the vortex cores of the topological structure can be disabled at a sufficiently high critical electric field by suppressing the structural trimerization therein, beyond which the vortex core region is replaced by a single ferroelectric domain without structural trimerization (Q = 0 ). Our results provide a stimulating reference for understanding the manipulation of real-space topological domain structure in hexagonal manganites.

  7. High Numerical Aperture Hexagonal Stacked Ring-Based Bidirectional Flexible Polymer Microlens Array.

    Science.gov (United States)

    Ahmed, Rajib; Yetisen, Ali K; Butt, Haider

    2017-03-28

    Flexible imprinted photonic nanostructures that are able to diffract/focus narrow-band light have potential applications in optical lenses, filters, tunable lasers, displays, and biosensing. Nanophotonic structures through holography and roll-to-roll printing may reduce fabrication complexities and expenses and enable mass production. Here, 3D photonic nanostructures of a stacked ring array were imprinted on acrylate polymer (AP) over poly(ethylene terephthalate) (PET) substrate through holography and lift-off processes to create a microlens array (MLA). The surface structure of the array consisted of circular nonostepped pyramids, and repeated patterns were in hexagonal arrangements. Stacked-ring-based MLA (SMLA) on a flexible AP-PET substrate showed efficient bidirectional light focusing and maximum numerical aperture (NA = 0.60) with a reasonable filling factor. The nanostructures produced a well-ordered hexagonally focused diffraction pattern in the far field, and power intensities were measured through angle-resolved experiments. The variation of nanostep dimensions (width and height) and the number of steps resulted in different photonic bandgaps, and the arrays produced distance-dependent narrow-band light focusing. The validation of the SMLA was demonstrated through the text, image, and hologram projection experiments. It is anticipated that imprinted bidirectional SMLA over flexible substrates may find applications in optical systems, displays, and portable sensors.

  8. Nurses' experiences of managing patient deterioration following a post-registration education programme: A critical incident analysis study.

    Science.gov (United States)

    Butler, Clare

    2017-10-13

    The aim of this study was to explore nurses' experiences assessing and managing deteriorating patients in practice following completion of a relevant post-registration education programme. Recognising the increasing acuity of ward patients, nurses are faced with patients who are at an increased risk of deterioration. Patients who are acutely ill or deteriorating often exhibit periods of physiological deterioration; however there is evidence illustrating that these clinical changes are frequently missed, misinterpreted or mismanaged in practice. In order to prepare nurses to competently assess and manage the deteriorating patient, education as a care initiative is offered to develop the knowledge and skills required. A qualitative study using critical incident analysis was conducted to acquire narrative data from nurses, describing their clinical practice experiences of patient deterioration. Thematic analysis was used to analyse the data. Findings revealed improvements in nurses' abilities to recognise patient deterioration, greater application of the evidence base and an increase in confidence and assertiveness. There was some evidence of applying the knowledge and skills learned, however equally some nurses indicated that they remained ill-prepared to apply the skills in practice. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  9. Chemical and Bandgap Engineering in Monolayer Hexagonal Boron Nitride.

    Science.gov (United States)

    Ba, Kun; Jiang, Wei; Cheng, Jingxin; Bao, Jingxian; Xuan, Ningning; Sun, Yangye; Liu, Bing; Xie, Aozhen; Wu, Shiwei; Sun, Zhengzong

    2017-04-03

    Monolayer hexagonal boron nitride (h-BN) possesses a wide bandgap of ~6 eV. Trimming down the bandgap is technically attractive, yet poses remarkable challenges in chemistry. One strategy is to topological reform the h-BN's hexagonal structure, which involves defects or grain boundaries (GBs) engineering in the basal plane. The other way is to invite foreign atoms, such as carbon, to forge bizarre hybrid structures like hetero-junctions or semiconducting h-BNC materials. Here we successfully developed a general chemical method to synthesize these different h-BN derivatives, showcasing how the chemical structure can be manipulated with or without a graphene precursor, and the bandgap be tuned to ~2 eV, only one third of the pristine one's.

  10. Calculation of Accurate Hexagonal Discontinuity Factors for PARCS

    Energy Technology Data Exchange (ETDEWEB)

    Pounders. J., Bandini, B. R. , Xu, Y, and Downar, T. J.

    2007-11-01

    In this study we derive a methodology for calculating discontinuity factors consistent with the Triangle-based Polynomial Expansion Nodal (TPEN) method implemented in PARCS for hexagonal reactor geometries. The accuracy of coarse-mesh nodal methods is greatly enhanced by permitting flux discontinuities at node boundaries, but the practice of calculating discontinuity factors from infinite-medium (zero-current) single bundle calculations may not be sufficiently accurate for more challenging problems in which there is a large amount of internodal neutron streaming. The authors therefore derive a TPEN-based method for calculating discontinuity factors that are exact with respect to generalized equivalence theory. The method is validated by reproducing the reference solution for a small hexagonal core.

  11. Dislocations in hexagonal and cubic GaN

    Science.gov (United States)

    Blumenau, A. T.; Elsner, J.; Jones, R.; Heggie, M. I.; Öberg, S.; Frauenheim, T.; Briddon, P. R.

    2000-12-01

    The structure and electronic activity of several types of dislocations in both hexagonal and cubic GaN are calculated using first-principles methods. Most of the stoichiometric dislocations investigated in hexagonal GaN do not induce deep acceptor states and thus cannot be responsible for the yellow luminescence. However, it is shown that electrically active point defects, in particular gallium vacancies and oxygen-related defect complexes, can be trapped at the stress field of the dislocations and may be responsible for this luminescence. For cubic GaN, we find the ideal stoichiometric 60° dislocation to be electrically active and the glide set to be more stable than the shuffle. The dissociation of the latter is considered.

  12. Exciton spectrum in multi-shell hexagonal semiconductor nanotube

    Directory of Open Access Journals (Sweden)

    O.M. Makhanets

    2012-10-01

    Full Text Available The theory of exciton spectrum in multi-shell hexagonal semiconductor nanotube is developed within the effective masses and rectangular potentials approximations using the method of effective potential. It is shown that the exciton binding energy for all states non-monotonously depends on the inner wire diameter, approaching several minimal and maximal magnitudes. The obtained theoretical results explain well the experimental positions of luminescence peaks for GaAs/Al0.4Ga0.6As nanotubes.

  13. Existence of non-abelian representations of the near hexagon

    Indian Academy of Sciences (India)

    In [5], a new combinatorial model with four types of points and nine types of lines of the slim dense near hexagon (5, 2) ⊗ (5, 2) was provided and it was then used to construct a non-abelain representation of (5, 2) ⊗ (5, 2) in the extraspecial 2-group 2 − 1 + 18 . In this paper, we give a direct proof for the existence of a ...

  14. Superconductivity from weak repulsion in hexagonal lattice systems

    OpenAIRE

    Nandkishore, Rahul; Thomale, Ronny; Chubukov, Andrey V.

    2014-01-01

    We analyze the pairing instabilities for fermions on hexagonal lattices (both honeycomb and triangular ones) in a wide range of fermionic densities. We argue that for a generic doping in this range, superconductivity at weak coupling is of Kohn-Luttinger type, and, due to the presence of electronic interactions beyond on-site repulsion, is a threshold phenomenon, with superconductivity emerging only if the attraction generated by the Kohn-Luttinger mechanism exceeds the bare repulsion in some...

  15. Thermodynamic and magnetic properties of the hexagonal type Ising nanowire

    OpenAIRE

    Kocakaplan, Yusuf; Kantar, Ersin

    2014-01-01

    The thermodynamic and magnetic properties of the mixed spin (1/2-1) hexagonal Ising nanowire (HIN) system with core-shell structure have been presented by means of the effective-field theory (EFT) with correlations. The effects of the physical parameters of the system on thermodynmaic and magnetic properties (magnetizations, susceptibilities, internal energies, and free energies and hysteresis curves) are investigated for both ferromagnetic and antiferromagnetic case, in detail. One can find ...

  16. Influence of strontium on the cubic to ordered hexagonal phase ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Oxides of the type Ba3–xSrxMgNb2O9 were synthesized by the solid state route. The x = 0 compo- sition (Ba3MgNb2O9) was found to crystallize in a disordered (cubic) perovskite structure when sintered at. 1000C. For higher Sr doping (x ≥ 0⋅5), there was clearly the presence of an ordered hexagonal phase ...

  17. Fractional Hofstadter States in Graphene on Hexagonal Boron Nitride

    Science.gov (United States)

    DaSilva, Ashley M.; Jung, Jeil; MacDonald, Allan H.

    2016-07-01

    In fractionally filled Landau levels there is only a small energy difference between broken translational symmetry electron-crystal states and exotic correlated quantum fluid states. We show that the spatially periodic substrate interaction associated with the long period moiré patterns present in graphene on nearly aligned hexagonal boron nitride tilts this close competition in favor of the former, explaining surprising recent experimental findings.

  18. Extension of the comet method to 2-D hexagonal geometry

    Energy Technology Data Exchange (ETDEWEB)

    Connolly, Kevin John; Rahnema, Farzad; Zhang, Dingkang, E-mail: farzad@gatech.edu [Nuclear and Radiological Engineering Program, George W. Woodruff School, Georgia Institute of Technology, Atlanta, GA (United States)

    2011-07-01

    The capability of the heterogeneous coarse mesh radiation transport (COMET) method developed at Georgia Tech has been expanded. COMET is now able to treat hexagonal geometry in two dimensions, allowing reactor problems to be solved for those next-generation reactors which utilize prismatic block structure and hexagonal lattice geometry in their designs. The COMET method is used to solve whole core reactor analysis problems without resorting to homogenization or low-order transport approximations. The eigenvalue and fission density distribution of the reactor are determined iteratively using response functions. The method has previously proven accurate in solving PWR, BWR, and CANDU eigenvalue problems. In this paper, three simple test cases inspired by high temperature test reactor material cross sections and fuel block geometry are presented. These cases are given not in an attempt to model realistic nuclear power systems, but in order to test the ability of the improved method. Solutions determined by the new hexagonal version of COMET, COMET-Hex, are compared with solutions determined by MCNP5, and the results show the accuracy and efficiency of the improved COMET-Hex method in calculating the eigenvalue and fuel pin fission density in sample full-core problems. COMETHex determines the eigenvalues of these simple problems to an order of within 50 pcm of the reference solutions and all pin fission densities to an average error of 0.2%, and it requires fewer than three minutes to produce these results. (author)

  19. On the dynamical nature of Saturn's North Polar hexagon

    Science.gov (United States)

    Rostami, Masoud; Zeitlin, Vladimir; Spiga, Aymeric

    2017-11-01

    An explanation of long-lived Saturn's North Polar hexagonal circumpolar jet in terms of instability of the coupled system polar vortex - circumpolar jet is proposed in the framework of the rotating shallow water model, where scarcely known vertical structure of the Saturn's atmosphere is averaged out. The absence of a hexagonal structure at Saturn's South Pole is explained similarly. By using the latest state-of-the-art observed winds in Saturn's polar regions a detailed linear stability analysis of the circumpolar jet is performed (i) excluding (;jet-only; configuration), and (2) including (;jet + vortex; configuration) the north polar vortex in the system. A domain of parameters: latitude of the circumpolar jet and curvature of its azimuthal velocity profile, where the most unstable mode of the system has azimuthal wavenumber 6, is identified. Fully nonlinear simulations are then performed, initialized either with the most unstable mode of small amplitude, or with the random combination of unstable modes. It is shown that developing barotropic instability of the ;jet+vortex; system produces a long-living structure akin to the observed hexagon, which is not the case of the ;jet-only; system, which was studied in this context in a number of papers in literature. The north polar vortex, thus, plays a decisive dynamical role. The influence of moist convection, which was recently suggested to be at the origin of Saturn's North Polar vortex system in the literature, is investigated in the framework of the model and does not alter the conclusions.

  20. Inter-band dynamics in a tunable hexagonal lattice

    Science.gov (United States)

    Windpassinger, Patrick; Weinberg, Malte; Simonet, Juliette; Struck, Julian; Oelschlaeger, Christoph; Luehmann, Dirk; Sengstock, Klaus

    2012-06-01

    Hexagonal lattices have recently attracted a lot of attention in the condensed matter community and beyond. Upon other intriguing features, their unique band structure exhibits Dirac cones at the corners of the Brillouin zone of the two lowest energy bands. Here, we report on the experimental observation of momentum-resolved inter-band dynamics of ultracold bosons between the two lowest Bloch bands (s- and p-band) of a hexagonal optical lattice with tunable band structure. Due to the spin-dependency of the lattice potential [1,2], a rotation of the magnetic quantization axis and the choice of the atomic spin state allow for an in-situ manipulation of the lattice structure from hexagonal to triangular geometry. It is thus possible to modify the band structure and open a gap at the Dirac cones. The loading of atoms into the excited band is achieved by a microwave transition between different spin states which in certain cases is only allowed as a result of interaction effects. We observe the time-dependent population of quasi momenta, revealing a striking influence of the existence of Dirac cones on the dynamics of atoms in the first two energy bands.[4pt] [1] P. Soltan-Panahi et al., Nature Physics 7, 43 (2011)[0pt] [2] P. Soltan-Panahi et al., Nature Physics 8, 71 (2012)

  1. Evaluation of the concrete shield compositions from the 2010 criticality accident alarm system benchmark experiments at the CEA Valduc SILENE facility

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Thomas Martin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Celik, Cihangir [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dunn, Michael E [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wagner, John C [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McMahan, Kimberly L [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Authier, Nicolas [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille (France); Jacquet, Xavier [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille (France); Rousseau, Guillaume [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille (France); Wolff, Herve [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille (France); Savanier, Laurence [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille (France); Baclet, Nathalie [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille (France); Lee, Yi-kang [French Atomic Energy Commission (CEA), Centre de Saclay, Gif sur Yvette (France); Trama, Jean-Christophe [French Atomic Energy Commission (CEA), Centre de Saclay, Gif sur Yvette (France); Masse, Veronique [French Atomic Energy Commission (CEA), Centre de Saclay, Gif sur Yvette (France); Gagnier, Emmanuel [French Atomic Energy Commission (CEA), Centre de Saclay, Gif sur Yvette (France); Naury, Sylvie [French Atomic Energy Commission (CEA), Centre de Saclay, Gif sur Yvette (France); Blanc-Tranchant, Patrick [French Atomic Energy Commission (CEA), Centre de Saclay, Gif sur Yvette (France); Hunter, Richard [Babcock International Group (United Kingdom); Kim, Soon [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dulik, George Michael [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Reynolds, Kevin H. [Y-12 National Security Complex, Oak Ridge, TN (United States)

    2015-01-01

    In October 2010, a series of benchmark experiments were conducted at the French Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA) Valduc SILENE facility. These experiments were a joint effort between the United States Department of Energy Nuclear Criticality Safety Program and the CEA. The purpose of these experiments was to create three benchmarks for the verification and validation of radiation transport codes and evaluated nuclear data used in the analysis of criticality accident alarm systems. This series of experiments consisted of three single-pulsed experiments with the SILENE reactor. For the first experiment, the reactor was bare (unshielded), whereas in the second and third experiments, it was shielded by lead and polyethylene, respectively. The polyethylene shield of the third experiment had a cadmium liner on its internal and external surfaces, which vertically was located near the fuel region of SILENE. During each experiment, several neutron activation foils and thermoluminescent dosimeters (TLDs) were placed around the reactor. Nearly half of the foils and TLDs had additional high-density magnetite concrete, high-density barite concrete, standard concrete, and/or BoroBond shields. CEA Saclay provided all the concrete, and the US Y-12 National Security Complex provided the BoroBond. Measurement data from the experiments were published at the 2011 International Conference on Nuclear Criticality (ICNC 2011) and the 2013 Nuclear Criticality Safety Division (NCSD 2013) topical meeting. Preliminary computational results for the first experiment were presented in the ICNC 2011 paper, which showed poor agreement between the computational results and the measured values of the foils shielded by concrete. Recently the hydrogen content, boron content, and density of these concrete shields were further investigated within the constraints of the previously available data. New computational results for the first experiment are now available

  2. Catalog and history of the experiments of criticality Saclay (1958-1964) Valduc / Building 10 (1964-2003); Catalogue et historique des experiences de criticite Saclay (1958 - 1964) Valduc / Batiment 10 (1964-2003)

    Energy Technology Data Exchange (ETDEWEB)

    Poullot, G.; Dumont, V.; Anno, J.; Cousinou, P. [Institut de Radioprotection et de Surete Nucleaire (IRSN), 92 - Fontenay aux Roses (France); Grivot, P.; Girault, E.; Fouillaud, P.; Barbry, F. [CEA Valduc, 21 - Is-sur-Tille (France)

    2003-07-01

    The group ' International Criticality Safety Evaluation Benchmark evaluation project ' (I.C.S.B.E.P.) has for aim to supply to the international community experiments of benchmarks criticality, of certified quality, used to guarantee the qualification of criticality calculation codes. Have been defined: a structure of experiments classification, a format of standard presentation, a structure of work with evaluation, internal and external checks, presentation in plenary session. After favourable opinion of the work group, the synthesis document called evaluation is integrated to the general report I.C.S.B.E.P. (N.C.)

  3. Neutron diffraction studies of the low-temperature magnetic structure of hexagonal FeGe

    DEFF Research Database (Denmark)

    Bernhard, J.; Lebech, Bente; Beckman, O.

    1984-01-01

    The magnetic structure of the hexagonal polymorph of FeGe has been investigated by means of neutron diffraction on single crystals at low temperature and for magnetic fields applied perpendicular to the c axis. Between 410 and approximately 55K the magnetic structure is collinear c......-axis antiferromagnetic. Below approximately 55K the structure changes to c-axis double-cone antiferromagnetic with an inter-layer turn angle for the basal-plane moment component of 194.4 degrees , independent of temperature and applied field. The cone half-angle increases with decreasing temperature to approximately 14...... degrees at 4.2K, but its temperature dependence shows a pronounced kink at 30K, indicating a phase change at this temperature. At 4.2K the authors observe an anomalous decrease of the basal-plane moment component at a critical field (B perpendicular to c) of 1.4 T. As the temperature is increased...

  4. Manipulation of BDNF signaling modifies the experience-dependent plasticity induced by pure tone exposure during the critical period in the primary auditory cortex.

    Science.gov (United States)

    Anomal, Renata; de Villers-Sidani, Etienne; Merzenich, Michael M; Panizzutti, Rogerio

    2013-01-01

    Sensory experience powerfully shapes cortical sensory representations during an early developmental "critical period" of plasticity. In the rat primary auditory cortex (A1), the experience-dependent plasticity is exemplified by significant, long-lasting distortions in frequency representation after mere exposure to repetitive frequencies during the second week of life. In the visual system, the normal unfolding of critical period plasticity is strongly dependent on the elaboration of brain-derived neurotrophic factor (BDNF), which promotes the establishment of inhibition. Here, we tested the hypothesis that BDNF signaling plays a role in the experience-dependent plasticity induced by pure tone exposure during the critical period in the primary auditory cortex. Elvax resin implants filled with either a blocking antibody against BDNF or the BDNF protein were placed on the A1 of rat pups throughout the critical period window. These pups were then exposed to 7 kHz pure tone for 7 consecutive days and their frequency representations were mapped. BDNF blockade completely prevented the shaping of cortical tuning by experience and resulted in poor overall frequency tuning in A1. By contrast, BDNF infusion on the developing A1 amplified the effect of 7 kHz tone exposure compared to control. These results indicate that BDNF signaling participates in the experience-dependent plasticity induced by pure tone exposure during the critical period in A1.

  5. Manipulation of BDNF signaling modifies the experience-dependent plasticity induced by pure tone exposure during the critical period in the primary auditory cortex.

    Directory of Open Access Journals (Sweden)

    Renata Anomal

    Full Text Available Sensory experience powerfully shapes cortical sensory representations during an early developmental "critical period" of plasticity. In the rat primary auditory cortex (A1, the experience-dependent plasticity is exemplified by significant, long-lasting distortions in frequency representation after mere exposure to repetitive frequencies during the second week of life. In the visual system, the normal unfolding of critical period plasticity is strongly dependent on the elaboration of brain-derived neurotrophic factor (BDNF, which promotes the establishment of inhibition. Here, we tested the hypothesis that BDNF signaling plays a role in the experience-dependent plasticity induced by pure tone exposure during the critical period in the primary auditory cortex. Elvax resin implants filled with either a blocking antibody against BDNF or the BDNF protein were placed on the A1 of rat pups throughout the critical period window. These pups were then exposed to 7 kHz pure tone for 7 consecutive days and their frequency representations were mapped. BDNF blockade completely prevented the shaping of cortical tuning by experience and resulted in poor overall frequency tuning in A1. By contrast, BDNF infusion on the developing A1 amplified the effect of 7 kHz tone exposure compared to control. These results indicate that BDNF signaling participates in the experience-dependent plasticity induced by pure tone exposure during the critical period in A1.

  6. Initial posting-a critical stage in the employment cycle: lessons from the experience of government doctors in Gujarat, India.

    Science.gov (United States)

    Purohit, Bhaskar; Martineau, Tim

    2016-07-11

    With the critical shortage of government doctors serving in rural health centers in India, understanding the initial posting policies, processes, and practices become important from a retention point of view. The initial posting is a very critical stage of an employment cycle and could play an important role in influencing the key human resource for health outcomes such as turnover and performance. The current study aimed at exploring a rather unknown phenomenon of the initial posting-related processes, practices, and perceptions of Medical Officers working with the Public Health Department in Gujarat, India. This was an exploratory study carried out in the state of Gujarat, India, that used qualitative methods first to document the extant initial posting policy with the help of document review and five Key Informant interviews; next, 19 in-depth interviews were carried out with Medical Officers to assess implementation of policies as well as processes and systems related to the initial posting of Medical Officers. A thematic framework approach was used to analyze qualitative data using NVIVO. The results indicate that there is no formal published or written initial posting policy in the state, and in the absence of a written and formal policy, the overall posting systems were perceived to be arbitrary by the study respondents. In the absence of any policy, the state has some unwritten informal practices such as posting the Medical Officers at their native places. Although this practice reflects a concern towards the Medical Officer's needs, such practices are not consistently applied indicating some inequity and possible implications over Medical Officers' retention and motivation. Initial posting is a critical aspect of an employment cycle, and the perceptions and experiences of MOs regarding the processes and practices involved in their initial posting can be crucial in influencing their performance and turnover rates. If long-term solutions are to be sought in

  7. Nuclear criticality safety guide

    Energy Technology Data Exchange (ETDEWEB)

    Pruvost, N.L.; Paxton, H.C. [eds.

    1996-09-01

    This technical reference document cites information related to nuclear criticality safety principles, experience, and practice. The document also provides general guidance for criticality safety personnel and regulators.

  8. Sensing operations based on hexagonal GaN microdisks acting as whispering-gallery mode optical microcavities.

    Science.gov (United States)

    Kouno, Tetsuya; Sakai, Masaru; Kishino, Katsumi; Hara, Kazuhiko

    2015-06-15

    Using room temperature photoluminescence measurements, we have demonstrated a sensing operation based on hexagonal GaN microdisks with a side length of approximately 1.5 μm that acted as optical microcavities. In the experiment, the optical microresonant systems based on the whispering-gallery mode (WGM) in the microdisks were affected by their ambient conditions, resulting in shifts of the lasing wavelength by varying the mixing ratios of isopropanol and o-xylene. We also obtained such shifts for aqueous solutions with varying sucrose concentrations. In addition, we demonstrated that tiny waterborne particles can be detected using a microdisk. These results indicate that the WGM in the hexagonal GaN microdisks potentially can be used to develop optical microbiosensors that can evaluate a limited area with a radius of 1-2 μm.

  9. Increasing the effective aperture of a detector and enlarging the receiving field of view in a 3D imaging lidar system through hexagonal prism beam splitting.

    Science.gov (United States)

    Lee, Xiaobao; Wang, Xiaoyi; Cui, Tianxiang; Wang, Chunhui; Li, Yunxi; Li, Hailong; Wang, Qi

    2016-07-11

    The detector in a highly accurate and high-definition scanning 3D imaging lidar system requires high frequency bandwidth and sufficient photosensitive area. To solve the problem of small photosensitive area of an existing indium gallium arsenide detector with a certain frequency bandwidth, this study proposes a method for increasing the receiving field of view (FOV) and enlarging the effective photosensitive aperture of such detector through hexagonal prism beam splitting. The principle and construction of hexagonal prism beam splitting is also discussed in this research. Accordingly, a receiving optical system with two hexagonal prisms is provided and the splitting beam effect of the simulation experiment is analyzed. Using this novel method, the receiving optical system's FOV can be improved effectively up to ±5°, and the effective photosensitive aperture of the detector is increased from 0.5 mm to 1.5 mm.

  10. Isotope engineering of van der Waals interactions in hexagonal boron nitride

    Science.gov (United States)

    Vuong, T. Q. P.; Liu, S.; van der Lee, A.; Cuscó, R.; Artús, L.; Michel, T.; Valvin, P.; Edgar, J. H.; Cassabois, G.; Gil, B.

    2018-02-01

    Hexagonal boron nitride is a model lamellar compound where weak, non-local van der Waals interactions ensure the vertical stacking of two-dimensional honeycomb lattices made of strongly bound boron and nitrogen atoms. We study the isotope engineering of lamellar compounds by synthesizing hexagonal boron nitride crystals with nearly pure boron isotopes (10B and 11B) compared to those with the natural distribution of boron (20 at% 10B and 80 at% 11B). On the one hand, as with standard semiconductors, both the phonon energy and electronic bandgap varied with the boron isotope mass, the latter due to the quantum effect of zero-point renormalization. On the other hand, temperature-dependent experiments focusing on the shear and breathing motions of adjacent layers revealed the specificity of isotope engineering in a layered material, with a modification of the van der Waals interactions upon isotope purification. The electron density distribution is more diffuse between adjacent layers in 10BN than in 11BN crystals. Our results open perspectives in understanding and controlling van der Waals bonding in layered materials.

  11. Growth of InAs Wurtzite Nanocrosses from Hexagonal and Cubic Basis

    DEFF Research Database (Denmark)

    Krizek, Filip; Kanne, Thomas; Razmadze, Davydas

    2017-01-01

    Epitaxially connected nanowires allow for the design of electron transport experiments and applications beyond the standard two terminal device geometries. In this Letter, we present growth methods of three distinct types of wurtzite structured InAs nanocrosses via the vapor-liquid-solid mechanis...... fabricated junctions in radial nanowire heterostructures.......Epitaxially connected nanowires allow for the design of electron transport experiments and applications beyond the standard two terminal device geometries. In this Letter, we present growth methods of three distinct types of wurtzite structured InAs nanocrosses via the vapor-liquid-solid mechanism....... Two methods use conventional wurtzite nanowire arrays as a 6-fold hexagonal basis for growing single crystal wurtzite nanocrosses. A third method uses the 2-fold cubic symmetry of (100) substrates to form well-defined coherent inclusions of zinc blende in the center of the nanocrosses. We show...

  12. Critical Jostling

    Directory of Open Access Journals (Sweden)

    Pippin Barr

    2016-11-01

    Full Text Available Games can serve a critical function in many different ways, from serious games about real world subjects to self-reflexive commentaries on the nature of games themselves. In this essay we discuss critical possibilities stemming from the area of critical design, and more specifically Carl DiSalvo’s adversarial design and its concept of reconfiguring the remainder. To illustrate such an approach, we present the design and outcomes of two games, Jostle Bastard and Jostle Parent. We show how the games specifically engage with two previous games, Hotline Miami and Octodad: Dadliest Catch, reconfiguring elements of those games to create interactive critical experiences and extensions of the source material. Through the presentation of specific design concerns and decisions, we provide a grounded illustration of a particular critical function of videogames and hope to highlight this form as another valuable approach in the larger area of videogame criticism.

  13. Critical Drivers for Safety Culture: Examining Department of Energy and U.S. Army Operational Experiences - 12382

    Energy Technology Data Exchange (ETDEWEB)

    Lowes, Elizabeth A. [The S.M. Stoller Corporation, Broomfield, Colorado (United States)

    2012-07-01

    Evaluating operational incidents can provide a window into the drivers most critical to establishing and maintaining a strong safety culture, thereby minimizing the potential project risk associated with safety incidents. By examining U.S. Department of Energy (DOE) versus U.S. Army drivers in terms of regulatory and contract requirements, programs implemented to address the requirements, and example case studies of operational events, a view of the elements most critical to making a positive influence on safety culture is presented. Four case studies are used in this evaluation; two from DOE and two from U.S. Army experiences. Although the standards guiding operations at these facilities are different, there are many similarities in the level of hazards, as well as the causes and the potential consequences of the events presented. Two of the incidents examined, one from a DOE operation and the other from a U.S. Army facility, resulted in workers receiving chemical burns. The remaining two incidents are similar in that significant conduct of operations failures occurred resulting in high-level radioactive waste (in the case of the DOE facility) or chemical agent (in the case of the Army facility) being transferred outside of engineering controls. A review of the investigation reports for all four events indicates the primary causes to be failures in work planning leading to ineffective hazard evaluation and control, lack of procedure adherence, and most importantly, lack of management oversight to effectively reinforce expectations for safe work planning and execution. DOE and Army safety programs are similar, and although there are some differences in contractual requirements, the expectations for safe performance are essentially the same. This analysis concludes that instilling a positive safety culture comes down to management leadership and engagement to (1) cultivate an environment that values a questioning attitude and (2) continually reinforce expectations

  14. [REPORTING CRITICAL LAB RESULTS, A CHALLENGE FOR THE LAB AND THE PHYSICIAN - A SUMMARY OF FOUR YEARS OF EXPERIENCE IN MEIR MEDICAL CENTER LABORATORIES].

    Science.gov (United States)

    Rashid, Gloria; Goldman, Jacob; Weinstein, Doron; Tohami, Tali; Neumark, Eran; Weiss, Eli

    2015-08-01

    Critical laboratory results require prompt reporting to the attending physician, as they may indicate that a patient is in a life-threatening condition. Although this important subject has been covered in many publications, it needs more attention from our healthcare organizations, which have no official policy on the subject. Matching expectations between the doctor and the laboratory needs to be better defined. The aim of this work was to inform the community of doctors and laboratories about the multiple problems concerning the reporting of critical laboratory results, to create a platform for exchanging views and ideas, and to build an extensive infrastructure for developing a unified plan to address this important issue. We present the results of four years of experience of reporting critical laboratory values at the Meir Medical Center Laboratories. The idea leading this work was to present the relatively low rate of critical results reported by the laboratories in 2010, sharing the problems discovered while investigating the situation in depth, and presenting the solutions that enabled us to obtain the desired results within four years. Gradual implementation of these improvements resulted in critical value reporting increasing from 55% in 2010 to 95% currently. We suggest a model for improving critical laboratory values reporting based on our 4-year experience, which emphasizes: (1) The importance of selecting proper tests and values for critical results; (2) The significance of using technology and computerized measures to support the process; and (3) Developing quick procedures for monitoring and controlling the process.

  15. Steps toward understanding the impact of early emotional experiences on disordered eating: The role of self-criticism, shame, and body image shame.

    Science.gov (United States)

    Gois, Ana Carolina; Ferreira, Cláudia; Mendes, Ana Laura

    2018-01-29

    In research, it has been suggested that early threatening emotional experiences, characterized by abuse, rejection, neglect or absence of affiliative signals may activate maladaptive defensive responses. Further, several studies have emphasised the association between the recall of early emotional experiences and eating psychopathology. However, this relationship does not seem to be direct. Thus, the current study explored the mediator roles of self-criticism and shame (general and body image-focused shame) in the link between early emotional experiences and the engagement in disordered eating, while controlling for the effect of body mass index. The sample of this study included 552 female participants, aged between 18 and 40 years old. The path analysis indicated that the absence of early positive emotional experiences was associated with disordered eating behaviours, through an increased perception of being negatively perceived as inferior or unattractive by others, self-critical attitudes, and body image-focused shame. The tested model accounted for 63% of body image shame and for 67% of disordered eating's variance, and showed an excellent model fit. These findings suggest that shame and self-criticism are defensive mechanisms associated with early threatening emotional experiences, which may trigger disordered eating behaviours. These data appear to offer important research and clinical implications supporting the development of intervention community programs for body and eating difficulties, that specifically target shame (general and body image-focused shame) and self-criticism, through the development of more adaptive emotional regulation strategies. Copyright © 2018. Published by Elsevier Ltd.

  16. Preliminary analyses of critical experiments using 10% enriched uranium nitrate solution with the 800mm-diameter cylindrical tank of STACY

    Energy Technology Data Exchange (ETDEWEB)

    Sono, Hiroki; Miyoshi, Yoshinori; Ohno, Akio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-05-01

    STACY, the static experiment critical facility in NUCEF, has the plan of a series of critical experiments using 10% enriched uranium nitrate solution with the 800mm-diameter cylindrical tank. The main purpose of these experiments is to measure the critical solution height and the temperature coefficient of reactivity by varying concentration of uranium and temperature of the fuel solution. Prior to these experiments, it is needed to make a diluting program of the solution, which is utilized to adjust the concentration of uranium, and to estimate the reactivity effect caused by temperature change. Therefore, such neutronic characteristics as critical solution height, height differential reactivity and kinetics parameters, were calculated with computational codes. In these preliminary analyses, simplified formulas to evaluate the above neutronic characteristics were also obtained by the least squares method applied to the results of computations. These formula well agree with computations within 0.1% up to 3.5%, so that they are useful to make detailed plans for the experiments and the reactor operation. Then, the temperature coefficient of reactivity is estimated at 3.85cent/degC, approximately. (author)

  17. Hexagon functions and the three-loop remainder function

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, Lance J.; Drummond, James M.; von Hippel, Matt; Pennington, Jeffrey

    2013-12-01

    We present the three-loop remainder function, which describes the scattering of six gluons in the maximally-helicity-violating configuration in planar NN = 4 super-Yang-Mills theory, as a function of the three dual conformal cross ratios. The result can be expressed in terms of multiple Goncharov polylogarithms. We also employ a more restricted class of hexagon functions which have the correct branch cuts and certain other restrictions on their symbols. We classify all the hexagon functions through transcendental weight five, using the coproduct for their Hopf algebra iteratively, which amounts to a set of first-order differential equations. The three-loop remainder function is a particular weight-six hexagon function, whose symbol was determined previously. The differential equations can be integrated numerically for generic values of the cross ratios, or analytically in certain kinematic limits, including the near-collinear and multi-Regge limits. These limits allow us to impose constraints from the operator product expansion and multi-Regge factorization directly at the function level, and thereby to fix uniquely a set of Riemann ζ valued constants that could not be fixed at the level of the symbol. The near-collinear limits agree precisely with recent predictions by Basso, Sever and Vieira based on integrability. The multi-Regge limits agree with the factorization formula of Fadin and Lipatov, and determine three constants entering the impact factor at this order. We plot the three-loop remainder function for various slices of the Euclidean region of positive cross ratios, and compare it to the two-loop one. For large ranges of the cross ratios, the ratio of the three-loop to the two-loop remainder function is relatively constant, and close to -7.

  18. Chromatic Dispersion Compensation Using Photonic Crystal Fibers with Hexagonal Distribution

    Directory of Open Access Journals (Sweden)

    Erick E. Reyes-Vera

    2013-11-01

    Full Text Available In this paper we show various configurations of photonic crystal fiber with hexagonal holes distribution for compensation of chromatic dispersion in optical communications links. The vectorial finite element method with scattering boundary condition was used for the analysis of the fibers. From these results it was estimated variation of the dispersion and the dispersion slope with respect to change in the diameter of the holes in the microstructure. With the above was possible to obtain values of dispersion in the C and L bands of telecommunications close to -850 ps / nm * km, with confinement losses 10-3 dB / km

  19. A wave dynamical interpretation of Saturn's polar hexagon

    Science.gov (United States)

    Allison, M.; Godfrey, D. A.; Beebe, R. F.

    1990-01-01

    The hexagonal, pole-centered cloud feature in Saturn's northern atmosphere, as revealed in Voyager close-encounter imaging mosaics, may be interpreted as a stationary Rossby wave. The wave is embedded within a sharply peaked eastward jet (of 100 meters per second) and appears to be perturbed by at least one anticyclonic oval vortex immediately to the south. The effectively exact observational determination of the horizontal wave number and phase speed, applied to a simple model dispersion relation, suggests that the wave is vertically trapped and provides a diagnostic template for further modeling of the deep atmospheric stratification.

  20. Inter-layer potential for hexagonal boron nitride

    Science.gov (United States)

    Leven, Itai; Azuri, Ido; Kronik, Leeor; Hod, Oded

    2014-03-01

    A new interlayer force-field for layered hexagonal boron nitride (h-BN) based structures is presented. The force-field contains three terms representing the interlayer attraction due to dispersive interactions, repulsion due to anisotropic overlaps of electron clouds, and monopolar electrostatic interactions. With appropriate parameterization, the potential is able to simultaneously capture well the binding and lateral sliding energies of planar h-BN based dimer systems as well as the interlayer telescoping and rotation of double walled boron-nitride nanotubes of different crystallographic orientations. The new potential thus allows for the accurate and efficient modeling and simulation of large-scale h-BN based layered structures.

  1. Approximation of the Neutron Diffusion Equation on Hexagonal Geometries

    OpenAIRE

    González Pintor, Sebastián

    2012-01-01

    La ecuación de la difusión neutrónica describe la población de neutrones de un reactor nuclear. Este trabajo trata con este modelo para reactores nucleares con geometría hexagonal. En primer lugar se estudia la ecuación de la difusión neutrónica. Este es un problema diferencial de valores propios, llamado problema de los modos Lambda. Para resolver el problema de los modos Lambda se han comparado diferentes métodos en geometrías unidimensionales, resultando como el mejor el método de elemento...

  2. Hippocampal Spike-Timing Correlations Lead to Hexagonal Grid Fields

    Science.gov (United States)

    Monsalve-Mercado, Mauro M.; Leibold, Christian

    2017-07-01

    Space is represented in the mammalian brain by the activity of hippocampal place cells, as well as in their spike-timing correlations. Here, we propose a theory for how this temporal code is transformed to spatial firing rate patterns via spike-timing-dependent synaptic plasticity. The resulting dynamics of synaptic weights resembles well-known pattern formation models in which a lateral inhibition mechanism gives rise to a Turing instability. We identify parameter regimes in which hexagonal firing patterns develop as they have been found in medial entorhinal cortex.

  3. Electronic structure of superlattices of graphene and hexagonal boron nitride

    KAUST Repository

    Kaloni, Thaneshwor P.

    2011-11-14

    We study the electronic structure of superlattices consisting of graphene and hexagonal boron nitride slabs, using ab initio density functional theory. We find that the system favors a short C–B bond length at the interface between the two component materials. A sizeable band gap at the Dirac point is opened for superlattices with single graphene layers but not for superlattices with graphene bilayers. The system is promising for applications in electronic devices such as field effect transistors and metal-oxide semiconductors.

  4. Hexagon POPE: effective particles and tree level resummation

    Energy Technology Data Exchange (ETDEWEB)

    Córdova, Lucía [Perimeter Institute for Theoretical Physics,Waterloo, Ontario N2L 2Y5 (Canada); Department of Physics and Astronomy & Guelph-Waterloo Physics Institute,University of Waterloo,Waterloo, Ontario N2L 3G1 (Canada)

    2017-01-12

    We present the resummation of the full Pentagon Operator Product Expansion series of the hexagon Wilson loop in planar N=4 SYM at tree level. We do so by considering the one effective particle states formed by a fundamental flux tube excitation and an arbitrary number of the so called small fermions which are then integrated out. We derive the one effective particle measures at finite coupling. By evaluating these measures at tree level and summing over all one effective particle states we reproduce the full 6 point tree level amplitude.

  5. Tunable Band Gaps of Mono-layer Hexagonal BNC Heterostructures

    OpenAIRE

    Peng, Qing; Zamiri, Amir; De, Suvranu

    2011-01-01

    Bandgap engineering by substituting C with B and N atoms in graphene has been shown to be a promising way to improve semiconducting properties of graphene. Such hybridized monolayers consisting of hexagonal BN phases in graphene (h-BNC) have been recently synthesized and char- acterized. In this paper, we present an ab initio density functional theory (DFT)-based study of h-BN domain size effect on band gap of mono-layer h-BNC heterostructures. The atomic structures, electronic band structure...

  6. The Effectiveness of Standardized Patient Experience (SPE Model in Teaching Critical Thinking Capability of Bachelor Nursing Students Compared to Case Study

    Directory of Open Access Journals (Sweden)

    Ryan Hara Permana

    2016-09-01

    Full Text Available Critical thinking is a main ability for nurses. However, the learning methods that are usually used by nursing education institutions cannot facilitate the development of critical thinking of nursing students optimally. This research investigated the effectiveness of Standardized Patient Experience (SPE model in practicing the critical thinking capability of nursing students compared to case study. This quasi-experiment study used 77 nursing students as the samples that were divided into control and experiment group. Although there are no significant different between the total critical thinking scores of the students who participated in SPE compared to case study (p= 0.146, but there are differences in analysis and problem solving aspect (p==0.019 and 0.00. the satisfaction and confidence level of the students toward the SPE are also significantly increased compared to case study (p=0.01 dan p=0.00. To conclude, both the SPE and case study method are effective in developing the critical thinking of the nursing students.

  7. Child and adolescent experience of and satisfaction with psychiatric care: a critical review of the research literature.

    Science.gov (United States)

    Biering, P

    2010-02-01

    This review paper contributes to better understanding of child and adolescent perception of quality of psychiatric care and should therefore be of interests for those who are concerned with the development and improvement of psychiatric care. * The review shows that the concept of patient satisfaction in child and adolescent psychiatric care is still underdeveloped and that few valid instruments have been developed to measure the concept. * The review helps to clarify the concept of adolescent satisfaction with psychiatric care by indentifying the universal components of the concept. * The paper concludes that children's perception of quality of care differs from their parents' and that quality assessment of children and adolescents needs to be heeded. Abstract Users' perspectives ought to be a determining factor for assessing the quality of psychiatric care and hence their perspectives need to be thoroughly understood. There is a lack of comprehensive knowledge of how children and adolescents perceive the quality of their psychiatric care. Therefore, the purpose of this paper is to critically review and synthesize findings from research on youth experience and satisfaction with psychiatric care. The review finds that knowledge about youth perception of quality of care is scattered and that few researchers consider previous findings. There are few valid instruments to measure child and adolescent patient satisfaction and few studies have considered these users' perceptions. These few studies indicate that adolescents' satisfaction has three universal components: satisfaction with environment and the organization of services; with user-caregiver relationship; and with treatment outcome. However, instruments that only use these factors lack sensitivity, while instruments that measure specific components of services capture differences in satisfaction between user groups. The review shows that parents and children have different mental care needs, and that the

  8. Plant Uptake of Organic Pollutants from Soil: A Critical Review ofBioconcentration Estimates Based on Modelsand Experiments

    Energy Technology Data Exchange (ETDEWEB)

    McKone, Thomas E.; Maddalena, Randy L.

    2007-01-01

    The role of terrestrial vegetation in transferring chemicals from soil and air into specific plant tissues (stems, leaves, roots, etc.) is still not well characterized. We provide here a critical review of plant-to-soil bioconcentration ratio (BCR) estimates based on models and experimental data. This review includes the conceptual and theoretical formulations of the bioconcentration ratio, constructing and calibrating empirical and mathematical algorithms to describe this ratio and the experimental data used to quantify BCRs and calibrate the model performance. We first evaluate the theoretical basis for the BCR concept and BCR models and consider how lack of knowledge and data limits reliability and consistency of BCR estimates. We next consider alternate modeling strategies for BCR. A key focus of this evaluation is the relative contributions to overall uncertainty from model uncertainty versus variability in the experimental data used to develop and test the models. As a case study, we consider a single chemical, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and focus on variability of bioconcentration measurements obtained from 81 experiments with different plant species, different plant tissues, different experimental conditions, and different methods for reporting concentrations in the soil and plant tissues. We use these observations to evaluate both the magnitude of experimental variability in plant bioconcentration and compare this to model uncertainty. Among these 81 measurements, the variation of the plant/soil BCR has a geometric standard deviation (GSD) of 3.5 and a coefficient of variability (CV-ratio of arithmetic standard deviation to mean) of 1.7. These variations are significant but low relative to model uncertainties--which have an estimated GSD of 10 with a corresponding CV of 14.

  9. IEA Wind Task 23, offshore wind technology and deployment. Subtask 1: Experience with critical deployment issues. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Lemming, J.

    2010-10-15

    The final report for IEA Wind Task 23, Offshore Wind Energy Technology and Deployment, is made up of two separate reports: Subtask 1: Experience with Critical Deployment Issues and Subtask 2: Offshore Code Comparison Collaborative (OC3). The Subtask 1 report included here provides background information and objectives of Task 23. It specifically discusses ecological issues and regulation, electrical system integration and offshore wind, external conditions, and key conclusions for Subtask 1. A comprehensive approach to planning is needed that integrates impacts on ecology, the effects of electrical infrastructure, and the layout of wind farms. Governments, which usually finance ecological research, should disclose results for wide dissemination as they become available. As example the workshop held suggested that documents covering the issues like offshore wind energy legislation, Guidelines for EIAs and SEAs and best practices need to be produced and distributed on a regular basis, as ecological research progresses and experience from the planning and operation of existing wind farms emerges. Research should help strike the balance between optimum regulation and the need to get projects up and running. Such research is needed to increase understanding of offshore wind metrology and its impact on electrical power fluctuations. More work is needed to develop special grid code and standards for offshore. The transient behavior of large cable installations (switching / harmonic/ Behavior and modeling of large HV cable systems) must be better understood. Connection and control systems must be developed for large offshore wind farms. Work is needed to develop the technical architecture of offshore wind grid systems. Public access to measurements (e.g., turbine power output, meteorological masts, buoys) is important, especially for model validation. Determining wake effects is currently the most important challenge in wind engineering. Emphasis should be put into

  10. Inclusive Financial Literacy Education for Inspiring a Critical Financial Consciousness: An Experiment in Partnership with Marginalised Youth

    Science.gov (United States)

    Visano, Brenda Spotton; Ek-Udofia, Imo

    2017-01-01

    In the absence of critical inquiry, traditional financial literacy education risks socialising economically marginalised groups into an acceptance of the very power structures that created their marginalisation in the first place. The instructor-facilitator seeking to confront the challenge of promoting critical thinking about a subject widely…

  11. Nuclear criticality safety experiments, calculations, and analyses - 1958 to 1982. Volume 2. Summaries. Complilation of papers from the Transactions of the American Nuclear Society

    Energy Technology Data Exchange (ETDEWEB)

    Koponen, B.L.; Hampel, V.E.

    1982-10-21

    This compilation contains 688 complete summaries of papers on nuclear criticality safety as presented at meetings of the American Nuclear Society (ANS). The selected papers contain criticality parameters for fissile materials derived from experiments and calculations, as well as criticality safety analyses for fissile material processing, transport, and storage. The compilation was developed as a component of the Nuclear Criticality Information System (NCIS) now under development at the Lawrence Livermore National Laboratory. The compilation is presented in two volumes: Volume 1 contains a directory to the ANS Transaction volume and page number where each summary was originally published, the author concordance, and the subject concordance derived from the keyphrases in titles. Volume 2 contains-in chronological order-the full-text summaries, reproduced here by permission of the American Nuclear Society from their Transactions, volumes 1-41.

  12. Hexagonal vs. Rectilinear Grids for Explicit Finite Difference Schemes for the Two-dimensional Wave Equation

    OpenAIRE

    Hamilton, Brian; Bilbao, Stefan

    2013-01-01

    Finite difference schemes for the 2-D wave equation operating on hexagonal grids and the accompanyingnumerical dispersion properties have received little attention in comparison to schemes operating on rectilinear grids. This paper considers the hexagonal tiling of the wavenumber plane in order to show that thehexagonal grid is a more natural choice to emulate the isotropy of the Laplacian operator and the wave equation. Performance of the 7-point scheme on a hexagonal grid is better than pre...

  13. Growth of InAs Wurtzite Nanocrosses from Hexagonal and Cubic Basis.

    Science.gov (United States)

    Krizek, Filip; Kanne, Thomas; Razmadze, Davydas; Johnson, Erik; Nygård, Jesper; Marcus, Charles M; Krogstrup, Peter

    2017-10-11

    Epitaxially connected nanowires allow for the design of electron transport experiments and applications beyond the standard two terminal device geometries. In this Letter, we present growth methods of three distinct types of wurtzite structured InAs nanocrosses via the vapor-liquid-solid mechanism. Two methods use conventional wurtzite nanowire arrays as a 6-fold hexagonal basis for growing single crystal wurtzite nanocrosses. A third method uses the 2-fold cubic symmetry of (100) substrates to form well-defined coherent inclusions of zinc blende in the center of the nanocrosses. We show that all three types of nanocrosses can be transferred undamaged to arbitrary substrates, which allows for structural, compositional, and electrical characterization. We further demonstrate the potential for synthesis of as-grown nanowire networks and for using nanowires as shadow masks for in situ fabricated junctions in radial nanowire heterostructures.

  14. Engineering and localization of quantum emitters in large hexagonal boron nitride layers

    CERN Document Server

    Choi, Sumin; ElBadawi, Christopher; Lobo, Charlene; Wang, Xuewen; Juodkazis, Saulius; Seniutinas, Gediminas; Toth, Milos; Aharonovich, Igor

    2016-01-01

    Hexagonal boron nitride (hBN) is a wide bandgap van der Waals material that has recently emerged as promising platform for quantum photonics experiments. In this work we study the formation and localization of narrowband quantum emitters in large flakes (up to tens of microns wide) of hBN. The emitters can be activated in as-grown hBN by electron irradiation or high temperature annealing, and the emitter formation probability can be increased by ion implantation or focused laser irradiation of the as-grown material. Interestingly, we show that the emitters are always localized at edges of the flakes, unlike most luminescent point defects in 3D materials. Our results constitute an important step on the road map of deploying hBN in nanophotonics applications.

  15. Fabricating a regular hexagonal lattice structure by interference pattern of six femtosecond laser beams

    Science.gov (United States)

    Nakata, Yoshiki; Yoshida, Masataka; Osawa, Kazuhito; Miyanaga, Noriaki

    2017-09-01

    Interference of six countering femtosecond (fs) laser beams at a wavelength of 785 nm has been utilized to fabricate nanostructures in a regular hexagonal lattice. A diffractive-optical element for six-beam splitting was introduced to a beam correlation system. The lattice structure was in accordance with the simulated structure based on the principle of superposition of electric fields. The unit structures fabricated on gold thin films were nanobit, nanodrop, and metallic hole array. The height and diameter of a representative nanodrop were 450 and 210 nm, respectively. Molten structures such as nanodrops are believed to have been fabricated via a solid-liquid-solid (SLS) mechanism, as in the case of previous experiments using four beams. In addition, multi-shot processing is examined to fabricate through-holes at lower fluences.

  16. A transmitting antenna with hexagon illumination shape for four-color VLC

    Science.gov (United States)

    Liu, Kexin; Zhang, Lijun; Hu, Shanshan; Xing, Jichuan; Li, Ping'an

    2018-01-01

    This paper demonstrated a compact white light transmitting antenna based on four-color VLC system, which included an integrating rod and a Fresnel lens system. This paper mainly analyzed the homogenizer: the hexagon integrating rod. After simulation and optimizing, the size of this rod is designed as 60mm (length) x 4.35mm (D). As a result of experiments, this antenna which mixes RGBY-LEDs' beam into white light with high uniformity (67.18%), and illuminate the area of 0.75m x 0.75m at 1.77m transmission distance. The color temperature of the detection surface is 5583K, the chromatic aberration is 0.0021, compared with light source E of standard illumination, less than eye solution (0.005). Also, we verified that this antenna could ensure a stable SNR in mobile communication.

  17. Spin Seebeck effect in Y-type hexagonal ferrite thin films

    Science.gov (United States)

    Hirschner, J.; Maryško, M.; Hejtmánek, J.; Uhrecký, R.; Soroka, M.; Buršík, J.; Anadón, A.; Aguirre, M. H.; Knížek, K.

    2017-08-01

    The longitudinal spin Seebeck effect (SSE) has been investigated using Pt/ferrite bilayers employing two Y-hexagonal ferrites Ba2Zn2Fe12O22 (Zn2Y) and Ba2Co2Fe12O22 (Co2Y) deposited by a spin-coating method on SrTiO3(111 ) substrates. The prepared hexagonal ferrites are highly oriented with c axes perpendicular to the substrate plane. The room-temperature magnetic moments of both ferrimagnetic ferrites amount to similar values and, most importantly, both have easy magnetization normal to the c axis. Despite their similar magnetic response the notable SSE signal is only observed for Zn2Y whereas the SSE signal of Co2Y is below the experimental noise level. A plausible explanation for this surprising discrepancy is magnetic disorder induced by cobalt cations, the random distribution of which in the Co2Y ferrite structure might critically limit the spin-wave propagation. This results in suppression of the SSE signal in Co2Y, while the Zn2Y with nonmagnetic substituent exhibits significant SSE signal. The temperature dependence of SSE for Zn2Y was measured over the 30 -300 -K range and quantitatively analyzed considering the heat flow through the Pt/Zn2Y bilayer and thermal gradient across the Zn2Y thin layer as the most relevant parameters. Using this approach the normalized SSE smoothly increases with lowering temperature, which correlates to increasing magnon propagation length and magnetization with decreasing temperature.

  18. Towards a conceptual model of motorcyclists' Risk Awareness: a comparative study of riding experience effect on hazard detection and situational criticality assessment.

    Science.gov (United States)

    Bellet, Thierry; Banet, Aurélie

    2012-11-01

    This research investigates risk awareness abilities among different populations of motorcyclists. Risk awareness is defined here as an extension of the Situational Awareness theory applied to critical driving situations. This study is more particularly focused on two main cognitive abilities supporting risk awareness: hazard detection, corresponding to riders' skill to perceive critical event occurring in the road environment and to identify it as a threat, and situational criticality assessment, corresponding to a subjective assessment of the accident risk. From this theoretical framework, the aim is to compare motorcyclists' performances in risk awareness according to their experience in motorcycling. Four populations of motorcyclists are investigated: Professional (Policemen), Experienced riders, Novices, and Beginners. Method implemented is based of a set of 25 video sequences of driving situations presenting a risk of collision. Participants' task was firstly to stop the video film if they detect a hazard. Then, at the end of each sequence, they have also to assess the criticality of the driving situation as a whole, with a Likert scale (from 0 to 100% of criticality). Results obtained show that cognitive abilities in both (i) hazard detection and (ii) situational criticality assessment depend of the riding experience, and are learnt from two different timing. On one side, Professional and Experienced riders obtained better results than Novices and Beginners for hazard perception (i.e. shortest reaction time). In terms of situational criticality assessment, Beginners underestimate the situational risk and seem overconfident in their abilities to manage the situational risk, against Novices, Professional and Experienced riders, who have better competences in criticality assessment. From these empirical results, a conceptual model of motorcyclists' Risk Awareness is proposed. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. FAINT LUMINESCENT RING OVER SATURN’S POLAR HEXAGON

    Energy Technology Data Exchange (ETDEWEB)

    Adriani, Alberto; D’Aversa, Emiliano; Oliva, Fabrizio; Filacchione, Gianrico [Institute of Space Astrophysics and Planetology of INAF, Via Fosso del Cavaliere 100, I-00133 Rome (Italy); Moriconi, Maria Luisa, E-mail: alberto.adriani@iaps.inaf.it [Institute of Atmospheric Sciences and Climate of CNR, Via Fosso del Cavaliere 100, I-00133 Rome (Italy)

    2015-07-20

    Springtime insolation is presently advancing across Saturn's north polar region. Early solar radiation scattered through the gaseous giant's atmosphere gives a unique opportunity to sound the atmospheric structure at its upper troposphere/lower stratosphere at high latitudes. Here, we report the detection of a tenuous bright structure in Saturn's northern polar cap corresponding to the hexagon equatorward boundary, observed by Cassini Visual and Infrared Mapping Spectrometer on 2013 June. The structure is spectrally characterized by an anomalously enhanced intensity in the 3610–3730 nm wavelength range and near 2500 nm, pertaining to relatively low opacity windows between strong methane absorption bands. Our first results suggest that a strong forward scattering by tropospheric clouds, higher in respect to the surrounding cloud deck, can be responsible for the enhanced intensity of the feature. This can be consistent with the atmospheric dynamics associated with the jet stream embedded in the polar hexagon. Further investigations at higher spectral resolution are needed to better assess the vertical distribution and microphysics of the clouds in this interesting region.

  20. Band gap effects of hexagonal boron nitride using oxygen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sevak Singh, Ram; Leong Chow, Wai [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Yingjie Tay, Roland [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Temasek Laboratories-NTU, 50 Nanyang Avenue, Singapore 639798 (Singapore); Hon Tsang, Siu [Temasek Laboratories-NTU, 50 Nanyang Avenue, Singapore 639798 (Singapore); Mallick, Govind [Temasek Laboratories-NTU, 50 Nanyang Avenue, Singapore 639798 (Singapore); Weapons and Materials Research Directorate, U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005 (United States); Tong Teo, Edwin Hang, E-mail: htteo@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2014-04-21

    Tuning of band gap of hexagonal boron nitride (h-BN) has been a challenging problem due to its inherent chemical stability and inertness. In this work, we report the changes in band gaps in a few layers of chemical vapor deposition processed as-grown h-BN using a simple oxygen plasma treatment. Optical absorption spectra show a trend of band gap narrowing monotonically from 6 eV of pristine h-BN to 4.31 eV when exposed to oxygen plasma for 12 s. The narrowing of band gap causes the reduction in electrical resistance by ∼100 fold. The x-ray photoelectron spectroscopy results of plasma treated hexagonal boron nitride surface show the predominant doping of oxygen for the nitrogen vacancy. Energy sub-band formations inside the band gap of h-BN, due to the incorporation of oxygen dopants, cause a red shift in absorption edge corresponding to the band gap narrowing.

  1. A spin dependent hexagonal optical lattice with complex valued tunneling

    Science.gov (United States)

    Weinberg, Malte; Struck, Julian; Oelschlaeger, Christoph; Simonet, Juliette; Windpassinger, Patrick; Sengstock, Klaus

    2013-05-01

    The realization of ultracold quantum gases in hexagonal optical lattices allows for the investigation of unique topological properties especially in connection to Dirac cones. Here we report on prospects of engineering artificial gauge potentials for bosons in a tunable hexagonal optical lattice. An intrinsic spin-dependency offers a versatile method to lift the degeneracy of this bipartite lattice via the orientation of the quantization axis. It is thus possible to tailor gaps at the Dirac points in the dispersion relation. Moreover, complex tunneling parameters can be experimentally realized by applying an external periodic force which breaks time reversal symmetry. As the resulting Peierls phases range from 0 to 2 π it is possible to emulate artificial gauge potentials in such a system. With these tools at hand, we discuss the feasibility of the emulation of strong field physics with ultracold quantum gases in the honeycomb lattice as a step towards the realization of complex quantum systems, i.e. quantum Hall states and topological insulators.

  2. Landau theory of topological defects in multiferroic hexagonal manganites.

    Science.gov (United States)

    Artyukhin, Sergey; Delaney, Kris T; Spaldin, Nicola A; Mostovoy, Maxim

    2014-01-01

    Topological defects in ordered states with spontaneously broken symmetry often have unusual physical properties, such as fractional electric charge or a quantized magnetic field flux, originating from their non-trivial topology. Coupled topological defects in systems with several coexisting orders give rise to unconventional functionalities, such as the electric-field control of magnetization in multiferroics resulting from the coupling between the ferroelectric and ferromagnetic domain walls. Hexagonal manganites provide an extra degree of freedom: in these materials, both ferroelectricity and magnetism are coupled to an additional, non-ferroelectric structural order parameter. Here we present a theoretical study of topological defects in hexagonal manganites based on Landau theory with parameters determined from first-principles calculations. We explain the observed flip of electric polarization at the boundaries of structural domains, the origin of the observed discrete vortices, and the clamping between ferroelectric and antiferromagnetic domain walls. We show that structural vortices induce magnetic ones and that, consistent with a recent experimental report, ferroelectric domain walls can carry a magnetic moment.

  3. Defect sensitive etching of hexagonal boron nitride single crystals

    Science.gov (United States)

    Edgar, J. H.; Liu, S.; Hoffman, T.; Zhang, Yichao; Twigg, M. E.; Bassim, Nabil D.; Liang, Shenglong; Khan, Neelam

    2017-12-01

    Defect sensitive etching (DSE) was developed to estimate the density of non-basal plane dislocations in hexagonal boron nitride (hBN) single crystals. The crystals employed in this study were precipitated by slowly cooling (2-4 °C/h) a nickel-chromium flux saturated with hBN from 1500 °C under 1 bar of flowing nitrogen. On the (0001) planes, hexagonal-shaped etch pits were formed by etching the crystals in a eutectic mixture of NaOH and KOH between 450 °C and 525 °C for 1-2 min. There were three types of pits: pointed bottom, flat bottom, and mixed shape pits. Cross-sectional transmission electron microscopy revealed that the pointed bottom etch pits examined were associated with threading dislocations. All of these dislocations had an a-type burgers vector (i.e., they were edge dislocations, since the line direction is perpendicular to the [ 2 11 ¯ 0 ]-type direction). The pit widths were much wider than the pit depths as measured by atomic force microscopy, indicating the lateral etch rate was much faster than the vertical etch rate. From an Arrhenius plot of the log of the etch rate versus the inverse temperature, the activation energy was approximately 60 kJ/mol. This work demonstrates that DSE is an effective method for locating threading dislocations in hBN and estimating their densities.

  4. Roll and hexagonal patterns in a phase-contrast oscillator

    Science.gov (United States)

    Grynberg, Gilbert

    1993-07-01

    This paper presents a new approach to the problem of the optical instabilities for a thin slice of Kerr medium with a feedback mirror. We show how to interpret this instability in terms of the transverse modes of a cavity consisting of a normal mirror and a medium having the properties of both a phase-conjugate mirror and a normal mirror that we called phase-contrast mirror. The threshold condition for this instability and the properties of a few patterns (rolls and hexagons) above the oscillation threshold are discussed. Cet article présente une nouvelle approche au problème des instabilités optiques dans un milieu Kerr face à un miroir de réaction. Il montre comment les instabilités apparaissant peuvent être comprises en termes de modes transverses d'une cavité consistant en un miroir normal et un milieu possédant à la fois les propriétés d'un miroir à conjugaison de phase et celles d'un miroir normal appelé miroir à contraste de phase. La condition de seuil pour l'instabilité est établie ainsi que le comportement de diverses formes (rouleaux, hexagones) au-dessus du seuil d'oscillation.

  5. Anisotropic Hexagonal Boron Nitride Nanomaterials - Synthesis and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Han,W.Q.

    2008-08-01

    Boron nitride (BN) is a synthetic binary compound located between III and V group elements in the Periodic Table. However, its properties, in terms of polymorphism and mechanical characteristics, are rather close to those of carbon compared with other III-V compounds, such as gallium nitride. BN crystallizes into a layered or a tetrahedrally linked structure, like those of graphite and diamond, respectively, depending on the conditions of its preparation, especially the pressure applied. Such correspondence between BN and carbon readily can be understood from their isoelectronic structures [1, 2]. On the other hand, in contrast to graphite, layered BN is transparent and is an insulator. This material has attracted great interest because, similar to carbon, it exists in various polymorphic forms exhibiting very different properties; however, these forms do not correspond strictly to those of carbon. Crystallographically, BN is classified into four polymorphic forms: Hexagonal BN (h-BN) (Figure 1(b)); rhombohedral BN (r-BN); cubic BN (c-BN); and wurtzite BN (w-BN). BN does not occur in nature. In 1842, Balmain [3] obtained BN as a reaction product between molten boric oxide and potassium cyanide under atmospheric pressure. Thereafter, many methods for its synthesis were reported. h-BN and r-BN are formed under ambient pressure. c-BN is synthesized from h-BN under high pressure at high temperature while w-BN is prepared from h-BN under high pressure at room temperature [1]. Each BN layer consists of stacks of hexagonal plate-like units of boron and nitrogen atoms linked by SP{sup 2} hybridized orbits and held together mainly by Van der Waals force (Fig 1(b)). The hexagonal polymorph has two-layered repeating units: AA'AA'... that differ from those in graphite: ABAB... (Figure 1(a)). Within the layers of h-BN there is coincidence between the same phases of the hexagons, although the boron atoms and nitrogen atoms are alternatively located along the c

  6. Thermal stability of hexagonal OsB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Zhilin [Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States); Blair, Richard G. [Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States); Department of Physics, University of Central Florida, Orlando, FL 32816 (United States); Orlovskaya, Nina, E-mail: Nina.Orlovskaya@ucf.edu [Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States); Cullen, David A. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Andrew Payzant, E. [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2014-11-15

    The synthesis of novel hexagonal ReB{sub 2}-type OsB{sub 2} ceramic powder was performed by high energy ball milling of elemental Os and B powders. Two different sources of B powder have been used for this mechanochemical synthesis. One B powder consisted of a mixture of amorphous and crystalline phases and a mixture of {sup 10}B and {sup 11}B isotopes with a fine particle size, while another B powder was a purely crystalline (rhombohedral) material consisting of enriched {sup 11}B isotope with coarse particle size. The same Os powder was used for the synthesis in both cases. It was established that, in the first case, the hexagonal OsB{sub 2} phase was the main product of synthesis with a small quantity of Os{sub 2}B{sub 3} phase present after synthesis as an intermediate product. In the second case, where coarse crystalline {sup 11}B powder was used as a raw material, only Os{sub 2}B{sub 3} boride was synthesized mechanochemically. The thermal stability of hexagonal OsB{sub 2} powder was studied by heating under argon up to 876 °C and cooling in vacuo down to −225 °C. During the heating, the sacrificial reaction 2OsB{sub 2}+3O{sub 2}→2Os+2B{sub 2}O{sub 3} took place due to presence of O{sub 2}/water vapor molecules in the heating chamber, resulting in the oxidation of B atoms and formation of B{sub 2}O{sub 3} and precipitation of Os metal out of the OsB{sub 2} lattice. As a result of such phase changes during heating, the lattice parameters of hexagonal OsB{sub 2} changed significantly. The shrinkage of the a lattice parameter was recorded in 276–426 °C temperature range upon heating, which was attributed to the removal of B atoms from the OsB{sub 2} lattice due to oxidation followed by the precipitation of Os atoms and formation of Os metal. While significant structural changes occurred upon heating due to presence of O{sub 2}, the hexagonal OsB{sub 2} ceramic demonstrated good phase stability upon cooling in vacuo with linear shrinkage of the lattice

  7. The large area crop inventory experiment: An experiment to demonstrate how space-age technology can contribute to solving critical problems here on earth

    Science.gov (United States)

    1977-01-01

    The large area crop inventory experiment is being developed to predict crop production through satellite photographs. This experiment demonstrates how space age technology can contribute to solving practical problems of agriculture management.

  8. Polarized and depolarized light-scattering studies on Brownian diffusional and critical fluid systems: theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Sorensen, C.M.

    1976-01-01

    An effort to expand light-scattering autocorrelation techniques to Brownian diffusional and critical fluid systems in which multiple scattering effects are important, and to understand the observed similarity of the Rayleigh linewidth of light scattered from these two seemingly different systems is discussed. A formalism was developed to find the light field multiply scattered from a suspension of Brownian diffusing particles. For the field doubly scattered from a system of noninteracting Brownian particles, the intensity and correlation time were much less dependent on the scattering angle than for the singly scattered component. The polarized and depolarized correlation times of light scattered from Brownian particle systems were measured. The double-scattering formalism was extended to light scattered from critical fluid systems. In the region k xi greater than 5 the doubly and singly scattered correlation times were nearly equal. The dynamic droplet model of critical phenomena was developed which gives the proper, experimentally verified, forms for the intensity and linewidth of light scattered from a critical fluid. To test the dynamic droplet model and the mode theories Rayleigh linewidth predictions, light-scattering measurements were performed on the critical fluid system methanol and cyclohexane. The data agreed with both the dynamic droplet and decoupled mode theory predictions. The depolarized scattered spectra from a critical fluid were measured, and qualitative agreement with the double-scattering theory was found. 57 figures, 5 tables.

  9. Competing order in the fermionic Hubbard model on the hexagonal graphene lattice

    CERN Document Server

    Buividovich, Pavel; Ulybyshev, Maksim; von Smekal, Lorenz

    2016-01-01

    We study the phase diagram of the fermionic Hubbard model on the hexagonal lattice in the space of on-site and nearest neighbor couplings with Hybrid-Monte-Carlo simulations. With pure on-site repulsion this allows to determine the critical coupling strength for spin-density wave formation with the standard approach of introducing a small mass term, explicitly breaking the sublattice symmetry. The analogous mass term for charge-density wave formation above a critical nearest-neighbor repulsion, on the other hand, would introduce a fermion sign problem. The competition between the two and the phase diagram in the space of the two coouplings can however be studied in simulations without explicit sublattice symmetry breaking. Our results compare qualitatively well with the Hartree-Fock phase diagram. We furthermore demonstrate how spin-symmetry breaking by the Euclidean time discretization can be avoided also, when using an improved fermion action based on an exponetial transfer matrix with exact sublattice symm...

  10. Strong 3D and 1D magnetism in hexagonal Fe-chalcogenides FeS and FeSe vs. weak magnetism in hexagonal FeTe.

    Science.gov (United States)

    Parker, David S

    2017-06-13

    We present a comparative theoretical study of the hexagonal forms of the Fe-chalcogenides FeS, FeSe and FeTe with their better known tetragonal forms. While the tetragonal forms exhibit only an incipient antiferromagnetism and experimentally show superconductivity when doped, the hexagonal forms of FeS and FeSe display a robust magnetism. We show that this strong magnetism arises from a van Hove singularity associated with the direct Fe-Fe c-axis chains in the generally more three-dimensional NiAs structure. We also find that hexagonal FeTe is much less magnetic than the other two hexagonal materials, so that unconventional magnetically-mediated superconductivity is possible, although a large T c value is unlikely.

  11. Experiences of four parents with physical therapy and early mobility of their children in a pediatric critical care unit: A case series.

    Science.gov (United States)

    Parisien, Rachel B; Gillanders, Kirstie; Hennessy, Erin K; Herterich, Lisa; Saunders, Kendra; Lati, Jamil; Dos Santos, Stephanie; Hassall, Alison; O'Brien, Kelly K

    2016-05-31

    The aim of this study was to conduct a preliminary investigation into parents' experiences of physical therapy and early mobility (EM) for their children in a pediatric critical care unit (PCCU). We conducted a series of four qualitative case studies using in-depth semi-structured face-to-face interviews. We recruited parents of children who had undergone surgery and received at least one EM physical therapy intervention while intubated. We conducted a thematic analysis of transcribed interviews to illuminate the factors that influenced EM experiences. Four parents participated in the study. We developed an overview of Parental Experiences with Physical Therapy and Early Mobility in a PCCU, which includes four themes that parents believed influenced their experiences: (1) environmental factors; (2) awareness of physical therapist and health care professional (HCP) roles; (3) communication among parents and HCPs; and (4) parental participation in their child's EM, within the overarching parental experiences in the PCCU. This study affords a preliminary understanding of parents' experiences with physical therapy and EM in a PCCU setting. Results provide an important foundation for future research on mobility in the context of pediatric critical care research and practice.

  12. Determination of susceptibility and specific heat critical exponents for weak itinerant-electron ferromagnets from vibrating reed experiments

    Science.gov (United States)

    Balakrishnan, K.; Kaul, S. N.

    2002-04-01

    We report the observation of a linear relationship between the magnetic contribution to Young's modulus, ΔE/E0, and inverse magnetic susceptibility χ-1 for amorphous weak itinerant-electron ferromagnets Fe90Zr10 and Fe91Zr9 in the asymptotic critical region near the ferromagnetic-paramagnetic phase transition. The proportionality ΔE(T)/E0~χ-1(T) is shown to provide as accurate a means of determining the asymptotic critical exponent γ and the leading ``correction-to-scaling'' amplitudes for susceptibilty from the ΔE/E0 data as a direct measurement of magnetic susceptibilty does. Similarly, the well-known relation between the magnetic contributions to sound velocity and specific heat is fully exploited to extract accurate estimates for the universal critical amplitude ratio A+/A- and the asymptotic critical exponents α+/- for the specific heat from the sound velocity data. The presently determined values of α+/- and γ, together with the reported value for spontaneous magnetization critical exponent β, not only obey the scaling equalities α+=α- and α+2β+γ=2 but also assert that the atomic magnetic moments in the alloys in question interact with one another through an attractive interaction which decays faster than 1/r5 with the interatomic spacing, r.

  13. Thermal conductance of graphene/hexagonal boron nitride heterostructures

    Science.gov (United States)

    Lu, Simon; McGaughey, Alan J. H.

    2017-03-01

    The lattice-based scattering boundary method is applied to compute the phonon mode-resolved transmission coefficients and thermal conductances of in-plane heterostructures built from graphene and hexagonal boron nitride (hBN). The thermal conductance of all structures is dominated by acoustic phonon modes near the Brillouin zone center that have high group velocity, population, and transmission coefficient. Out-of-plane modes make their most significant contributions at low frequencies, whereas in-plane modes contribute across the frequency spectrum. Finite-length superlattice junctions between graphene and hBN leads have a lower thermal conductance than comparable junctions between two graphene leads due to lack of transmission in the hBN phonon bandgap. The thermal conductances of bilayer systems differ by less than 10% from their single-layer counterparts on a per area basis, in contrast to the strong thermal conductivity reduction when moving from single- to multi-layer graphene.

  14. Solitary plane waves in an isotropic hexagonal lattice

    DEFF Research Database (Denmark)

    Zolotaryuk, Yaroslav; Savin, A.V.; Christiansen, Peter Leth

    1998-01-01

    Solitary plane-wave solutions in a two-dimensional hexagonal lattice which can propagate in different directions on the plane are found by using the pseudospectral method. The main point of our studies is that the lattice model is isotropic and we show that the sound velocity is the same...... for different directions of wave propagation. The pseudospectral method allows us to obtain solitary wave solutions with very narrow profile, the thickness of which may contain a few atoms or even less than one lattice spacing (i.e., essentially discrete solutions). Since these nonlinear waves are quite narrow......, details of lattice microstructure appear to be important for their motion. Particularly, the regime of their propagation qualitatively depends on whether or not the direction of their motion occurs along the lattice bonds. Two types of solitary plane waves are found and studied. The stability...

  15. Magnetic tunnel junctions with monolayer hexagonal boron nitride tunnel barriers

    Energy Technology Data Exchange (ETDEWEB)

    Piquemal-Banci, M.; Galceran, R.; Bouzehouane, K.; Anane, A.; Petroff, F.; Fert, A.; Dlubak, B.; Seneor, P. [Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, Palaiseau 91767 (France); Caneva, S.; Martin, M.-B.; Weatherup, R. S.; Kidambi, P. R.; Robertson, J.; Hofmann, S. [Department of Engineering, University of Cambridge, Cambridge CB21PZ (United Kingdom); Xavier, S. [Thales Research and Technology, 1 avenue Augustin Fresnel, Palaiseau 91767 (France)

    2016-03-07

    We report on the integration of atomically thin 2D insulating hexagonal boron nitride (h-BN) tunnel barriers into Co/h-BN/Fe magnetic tunnel junctions (MTJs). The h-BN monolayer is directly grown by chemical vapor deposition on Fe. The Conductive Tip Atomic Force Microscopy (CT-AFM) measurements reveal the homogeneity of the tunnel behavior of our h-BN layers. As expected for tunneling, the resistance depends exponentially on the number of h-BN layers. The h-BN monolayer properties are also characterized through integration into complete MTJ devices. A Tunnel Magnetoresistance of up to 6% is observed for a MTJ based on a single atomically thin h-BN layer.

  16. Hexagonal photonic crystal waveguide based on barium titanate thin films

    Science.gov (United States)

    Li, Jianheng; Liu, Zhifu; Wessels, Bruce W.; Tu, Yongming; Ho, Seng-Tiong; Joshi-Imre, Alexandra; Ocola, Leonidas E.

    2011-03-01

    The simulation, fabrication and measurement of nonlinear photonic crystals (PhCs) with hexagonal symmetry in epitaxial BaTiO3 were investigated. The optical transmission properties of a PhC were simulated by a 2-D finite-difference time domain (FDTD) method. A complete bandgap exists for both the TE and TM optical modes. The fabricated PhC has a well-defined stop band over the spectral region of 1525 to 1575 nm. A microcavity structure was also fabricated by incorporation of a line defect in the PhC. Transmission of the microcavity structure over the spectral region from 1456 to 1584nm shows a well-defined 5 nm wide window at 1495nm. Simulations indicate that the phase velocity matched PhC microcavity device of 0.5 mm long can potentially serve as modulator with a 3 dB bandwidth of 4 THz.

  17. Functionalised hexagonal-domain graphene for position-sensitive photodetectors

    Science.gov (United States)

    De Sanctis, Adolfo; Barnes, Matthew D.; Amit, Iddo; Craciun, Monica F.; Russo, Saverio

    2017-03-01

    Graphene’s unique photoresponse has been largely used in a multitude of optoelectronics applications ranging from broadband photodetectors to wave-guide modulators. In this work we extend the range of applications to position-sensitive photodetectors (PSDs) using FeCl3-intercalated hexagonal domains of graphene grown by atmospheric pressure chemical vapour deposition (APCVD). The FeCl3-based chemical functionalisation of APCVD graphene crystals is affected by the presence of wrinkles and results in a non-uniform doping of the graphene layers. This doping profile creates multiple p-p+ photoactive junctions which show a linear and bipolar photoresponse with respect to the position of a focused light spot, which is ideal for the realization of a PSD. Our study paves the way towards the fabrication of flexible and transparent PSDs that could be embedded in smart textile and wearable electronics.

  18. Design considerations for quasi-phase-matching in doubly resonant lithium niobate hexagonal microresonators

    CSIR Research Space (South Africa)

    Sono, Tleyane J

    2017-08-01

    Full Text Available . Such nonlinear optical hexagonal micro-resonators are proposed as a platform for second harmonic generation (SHG) by the combined mechanisms of total internal reflection (TIR) and quasi-phase-matching (QPM). The proposed scheme for SHG via TIR-QPM in a hexagonal...

  19. Analytical solutions for some defect problems in 1D hexagonal and ...

    Indian Academy of Sciences (India)

    We study some typical defect problems in one-dimensional (1D) hexagonal and two-dimensional (2D) octagonal quasicrystals. The first part of this investigation addresses in detail a uniformly moving screw dislocation in a 1D hexagonal piezoelectric quasicrystal with point group 6. A general solution is derived in terms ...

  20. Macroscopically ordered hexagonal arrays by directed self-assembly of block copolymers with minimal topographic patterns.

    Science.gov (United States)

    Choi, Jaewon; Gunkel, Ilja; Li, Yinyong; Sun, Zhiwei; Liu, Feng; Kim, Hyeyoung; Carter, Kenneth R; Russell, Thomas P

    2017-10-12

    A simple and robust method has been developed for the generation of macroscopically ordered hexagonal arrays from the directed self-assembly (DSA) of cylinder-forming block copolymers (BCPs) based on minimal trench patterns with solvent vapor annealing. The use of minimal trench patterns allows us to probe the guided hexagonal arrays of cylindrical microdomains using grazing incidence small angle X-ray scattering (GISAXS), where the sample stage is rotated on the basis of the six-fold symmetry of a hexagonal system. It is found that the (10) planes of hexagonal arrays of cylindrical microdomains are oriented parallel to the underlying trench direction over macroscopic length scales (∼1 × 1 cm2). However, there are misorientations of the hexagonal arrays with short-range ordering. GISAXS patterns show that the hexagonal arrays on the minimal trench pattern are distorted, deviating from a perfect hexagonal lattice. This distortion has been attributed to the absence of topographic constraints in the unconfined direction on the 1-D minimal trench pattern. Also, the frustration of BCP microdomains, arising from the incommensurability between the trench pitch and natural period of the BCP at the base of the trench, influences the distortion of the hexagonal arrays.

  1. High-pressure Al-rich hexagonal phases-What are their kin?

    DEFF Research Database (Denmark)

    Makovicky, Emil; Olsen, Lars Arnskov

    2008-01-01

    The hexagonal Al-rich high-pressure phases are members of a structural family with the same type of framework composed of double-ribbons of edge-sharing octahedra, but variably occupied trigonal and hexagonal channels. This family includes jaffeite, fluoborite, yeremeyevite, painite, and syntheti...... Ba indates. This kinship broadens the spectrum of elements potentially accommodated by these phases in the mantle....

  2. Radiological dose assessment for bounding accident scenarios at the Critical Experiment Facility, TA-18, Los Alamos National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-09-01

    A computer modeling code, CRIT8, was written to allow prediction of the radiological doses to workers and members of the public resulting from these postulated maximum-effect accidents. The code accounts for the relationships of the initial parent radionuclide inventory at the time of the accident to the growth of radioactive daughter products, and considers the atmospheric conditions at time of release. The code then calculates a dose at chosen receptor locations for the sum of radionuclides produced as a result of the accident. Both criticality and non-criticality accidents are examined.

  3. Carbon-coated hexagonal magnetite nanoflakes production by spray CVD of alcohols in mixture with water

    Science.gov (United States)

    Reyes-Reyes, Marisol; Hernández-Arriaga, Daniel; López-Sandoval, Román

    2014-12-01

    In this study, we report a successful technique for synthesizing magnetite hexagonal nanoflakes coated with carbon layers using spray thermal decomposition, which is a reproducible method that is easy to scale up. We investigated the effects of mixing different volumes of deionized (DI) water with alcohol on the population and quality of single-crystalline Fe3O4 hexagonal nanoflakes. Methanol and ethanol were used as the carbon and oxygen source, while ferrocene was mainly used as the Fe source. To obtain a large quantity of hexagonal structures, a strongly oxidative atmosphere was required. The DI water was used to enhance the oxidative environment during the reaction and was an important component for obtaining well-shaped hexagonal magnetite crystalline nanoflakes. The use of alcohols, water and the spray chemical vapor deposition (CVD) method make this procedure easy to use. In addition, this method provides a one-step process for synthesizing carbon-coated hexagonal Fe3O4 nanocrystals.

  4. Theoretical Perspectives on Critical Thinking Teaching: Reflections from Field Experiences from a Norwegian Lower Secondary School in Comparison to Tanzanian Secondary School Teaching Practices

    Directory of Open Access Journals (Sweden)

    Leatitia Gabriel Mashaza

    2017-08-01

    Full Text Available This paper presents the theoretical perspectives relevant to critical thinking as my topic of research during my teaching practice period which was conducted from 12th -28th October 2015 at Eidsvag secondary school in Bergen, Norway. As a requirement for Masters’ degree in social science education, all master students were required to engage in teaching practice in different Norwegian primary and secondary schools. Importantly, every student teacher was given a topic of concentration as a mini-research for the whole teaching practice period. My topic of research focused at exploring and gaining the theoretical and practical perspectives on critical thinking teaching by drawing some experiences from a Norwegian lower secondary school (Eidsvag skole in reflection to secondary school teaching practice experiences in Tanzania. Therefore, in this paper, my reflections with regard to the conditions favoring the possibility for critical thinking teaching and how it was enhanced by teachers at my practice school will be discussed. Further to that, I will also present the observed challenges of which, in my view, in way or another intervened the possibility for effective critical thinking teaching to take place.

  5. Self-organized criticality induced by quenched disorder: Experiments on flux avalanches in NbHx films

    NARCIS (Netherlands)

    Welling, M.S.; Aegerter, C.M.; Wijngaarden, R.J.

    2005-01-01

    We present an experimental study of the influence of quenched disorder on the distribution of flux avalanches in type-II superconductors. In the presence of much quenched disorder, the avalanche sizes are powerlaw distributed and show finite-size scaling, as expected from self-organized criticality

  6. Embedding Culture in a Field Experience Seminar: Lessons Learned about Promoting Preservice Teacher Critical Consciousness in an Urban School Partnership

    Science.gov (United States)

    Jacobs, Jennifer; Casciola, Vanessa; Arndt, Katie; Mallory, Mashainah

    2015-01-01

    This article reports the research findings of teacher educator inquiry using qualitative methods examining how incorporating the topic of culture into the field seminar component of a newly developed urban school-university partnership influenced preservice teachers' abilities to become critically conscious. After analyzing preservice teacher…

  7. Students' Critical Mathematical Thinking Skills and Character: Experiments for Junior High School Students through Realistic Mathematics Education Culture-Based

    Science.gov (United States)

    Palinussa, Anderson L.

    2013-01-01

    This paper presents the findings of a quasi-experimental with pre-test-post-test design and control group that aims to assess students' critical mathematical thinking skills and character through realistic mathematics education (RME) culture-based. Subjects of this study were 106 junior high school students from two low and medium schools level in…

  8. Preparation and optical properties of fullerene/ferrocene hybrid hexagonal nanosheets and large-scale production of fullerene hexagonal nanosheets.

    Science.gov (United States)

    Wakahara, Takatsugu; Sathish, Marappan; Miyazawa, Kun'ichi; Hu, Chunping; Tateyama, Yoshitaka; Nemoto, Yoshihiro; Sasaki, Toshio; Ito, Osamu

    2009-07-29

    The supramolecular nanoarchitectures, C(60)/ferrocene nanosheets, were prepared by a simple liquid-liquid interfacial precipitation method and fully characterized by means of SEM, STEM, HRTEM, XRD, Raman and UV-vis-NIR spectra. The highly crystallized C(60)/ferrocene hexagonal nanosheets had a size of ca. 9 microm and the formulation C(60)(ferrocene)(2). A strong charge-transfer (CT) band between ferrocene and C(60) was observed at 782 nm, indicating the presence of donor-acceptor interaction in the nanosheets. Upon heating the nanosheets to 150 degrees C, the CT band disappeared due to the sublimation of ferrocene from the C(60)/ferrocene hybrid, and C(60) nanosheets with an fcc crystal structure and the same shape and size as the C(60)/ferrocene nanosheets were obtained.

  9. What Is Critical in Critical Language Awareness?

    Science.gov (United States)

    Males, Terry

    2000-01-01

    Discusses the question of what is critical in critical language awareness by drawing on Hans Georg Gadamer's development of the dialectic of experience, historically effected consciousness, and the dialectic of question and answer. The openness found to characterize these three events initiates the space of distance by which the critical instance…

  10. Knowledge and critical thinking skills increase clinical reasoning ability in urogenital disorders: a Universitas Sriwijaya Medical Faculty experience

    Directory of Open Access Journals (Sweden)

    Irfannuddin Irfannuddin

    2009-03-01

    Full Text Available Aim Clinical reasoning is one of the essential competencies for medical practitioners, so that it must be exercised by medical students. Studies on quantitative evidence of factors influencing clinical reasoning abilicy of students are limited. The aim of this study was to determine the influence of knowledge and other factors on the clinical reasoning abiliry ofthe students, which can serve as reference to establish methods for learning ctinical reasoning.Methods This is a cross-sectional study on fourth semester students enrolled in the Competency-based Curriculum of the Medical Faculty, University of Sriwijaya. Data on clinical reasoning abilily and risk factors during urogenital blockwere collected inApril 2008, when the students have just completed the btock. Clinical reasoning abiliry was tested using the Script Concordance test and the risk factors were evaluated based on formative tests, block summative assessments, and student characteristics. Data were analyzed by Cox regression.Results The prevalence of low clinical reasoning ability of the 132 students was 38.6%. The group with low basic knowledge was found to have 63% risk ol low clinical reasoning abiliry when compared to those with high basic knowledge (adjusted RR = 1.63; 95% conidence intewal (Ct: 1.10 -2.42. When compared to students with high critical thinking skitls, those with lory critical thinking skills had 2.3 time to be low clinical reasoning abitity (adjusted RR : 2.30; 95% CI: 1.55 - 3.41.Conclusion Students with low critical thinking skills or with inadequate knowledge had a higher risk of low clinical reasoning ability. (Med J Indones 2009; 18: 53-9Keywords: clinical reasoning, basic knowledge, critical thinking, competency-based curriculum

  11. Cryogenic electrical insulation of superconducting power transmission lines: transfer of experience learned from metal superconductors to high critical temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Gerhold, J. [Technical University of Graz (Austria). Inst. fuer Electrische Maschinen und Antrisbechnik; Tanaka, T. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

    1998-11-01

    Superconducting power transmission lines have found renewed interest after the discovery of a superconductor with high critical temperature. Cooling by liquid nitrogen instead of helium has in fact a great impact on economics. The existing wide spread knowhow about dielectric performance in helium cooled transmission lines which were already developed up to a prototype stage can be used with benefit for the design of liquid nitrogen cooled lines. (author)

  12. Students’ Critical Mathematical Thinking Skills and Character: Experiments for Junior High School Students through Realistic Mathematics Education Culture-Based

    Directory of Open Access Journals (Sweden)

    Anderson L. Palinussa

    2013-01-01

    Full Text Available This paper presents the findings of a quasi-experimental with pre-testpost-test design and control group that aims to assess students’ critical mathematical thinking skills and character through realisticmathematics education (RME culture-based. Subjects of this studywere 106 junior high school students from two low and medium schools level in Ambon. The instruments of the study are: students’ early math skills test, critical thinking skills mathematical test and perception scale of students’character. Data was analyzed by using t test and Anova. The study found that: 1 Achievements and enhancement of students’ critical mathematical thinking skills who were treated with by realistic mathematics education is better then students’ skills were treated by conventional mathematics education. The differences are considered to: a overall students, b the level of early math skills, and c schools’ level; 2 Quality of students’ characterwho were treated by realistic mathematics education is better thenstudents’ character who were treated by conventional mathematicseducation The differences are considered to: a overall students, b the level of early math skills, and c schools’ level

  13. Documentation of nonroutine communications of critical or significant radiology results: a multiyear experience at a tertiary hospital.

    Science.gov (United States)

    Lakhani, Paras; Langlotz, Curtis P

    2010-10-01

    The aim of this study was to determine the frequency of radiology reports that contain nonroutine communications of results and categorize the urgency of such communications. A rule-based text-query algorithm was applied to a database of 2.3 million radiology reports, which has an accuracy of 98% for classifying reports containing documentation of communications. The frequency of such communications by year, modality, and study type was then determined. Finally, 200 random reports selected by the algorithm were analyzed, and reports containing critical results were categorized according to ascending levels of urgency. Critical or noncritical results to health care providers were present in 5.09% of radiology reports (116,184 of 2,282,923). For common modalities, documentation of communications were most frequent in CT (14.34% [57,537 of 402,060]), followed by ultrasound (9.55% [17,814 of 186,626]), MRI (5.50% [13,697 of 248,833]), and chest radiography (1.57% [19,840 of 1,262,925]). From 1997 to 2005, there was an increase in reports containing such communications (3.04% in 1997, 6.82% in 2005). More reports contained nonroutine communications in single-view chest radiography (1.29% [5,533 of 428,377]) than frontal/lateral chest radiography (0.80% [1,815 of 226,837]), diagnostic mammography (9.42% [3,662 of 38,877]) than screening mammography (0.47% [289 of 61,114]), and head CT (26.21% [20,963 of 79,985]) than abdominal CT (15.05% [19,871 of 132,034]) or chest CT (5.33% [3,017 of 56,613]). All of these results were statistically significant (P radiology reports indicating nonroutine communications, 155 (78%) had critical and 45 (22%) had noncritical results. Regarding level of urgency, 94 of 155 reports (60.6%) with critical results were categorized as high urgency, 31 (20.0%) as low urgency, 26 (16.8%) as medium urgency, and 4 (2.6%) as discrepant. From 1997 to 2005, there was a significant increase in documentation of nonroutine communications, which may be due

  14. Thought Experiments in Teaching Free-Fall Weightlessness: A Critical Review and an Exploration of Mercury's Behavior in "Falling Elevator"

    Science.gov (United States)

    Balukovic, Jasmina; Slisko, Josip; Cruz, Adrián Corona

    2017-01-01

    Different "thought experiments" dominate teaching approaches to weightlessness, reducing students' opportunities for active physics learning, which should include observations, descriptions, explanations and predictions of real phenomena. Besides the controversy related to conceptual definitions of weight and weightlessness, we report…

  15. Intensive care survivors' experiences of ward-based care: Meleis' theory of nursing transitions and role development among critical care outreach services.

    Science.gov (United States)

    Ramsay, Pam; Huby, Guro; Thompson, Andrew; Walsh, Tim

    2014-03-01

    To explore the psychosocial needs of patients discharged from intensive care, the extent to which they are captured using existing theory on transitions in care and the potential role development of critical care outreach, follow-up and liaison services. Intensive care patients are at an increased risk of adverse events, deterioration or death following ward transfer. Nurse-led critical care outreach, follow-up or liaison services have been adopted internationally to prevent these potentially avoidable sequelae. The need to provide patients with psychosocial support during the transition to ward-based care has also been identified, but the evidence base for role development is currently limited. Twenty participants were invited to discuss their experiences of ward-based care as part of a broader study on recovery following prolonged critical illness. Psychosocial distress was a prominent feature of their accounts, prompting secondary data analysis using Meleis et al.'s mid-range theory on experiencing transitions. Participants described a sense of disconnection in relation to profound debilitation and dependency and were often distressed by a perceived lack of understanding, indifference or insensitivity among ward staff to their basic care needs. Negotiating the transition between dependence and independence was identified as a significant source of distress following ward transfer. Participants varied in the extent to which they were able to express their needs and negotiate recovery within professionally mediated boundaries. These data provide new insights into the putative origins of the psychosocial distress that patients experience following ward transfer. Meleis et al.'s work has resonance in terms of explicating intensive care patients' experiences of psychosocial distress throughout the transition to general ward-based care, such that the future role development of critical care outreach, follow-up and liaison services may be more theoretically informed

  16. Surface complexation of Pb(II) by hexagonal birnessite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, K.; Refson, K.; Sposito, G.

    2010-10-15

    Natural hexagonal birnessite is a poorly-crystalline layer type Mn(IV) oxide precipitated by bacteria and fungi which has a particularly high adsorption affinity for Pb(II). X-ray spectroscopic studies have shown that Pb(II) forms strong inner-sphere surface complexes mainly at two sites on hexagonal birnessite nanoparticles: triple corner-sharing (TCS) complexes on Mn(IV) vacancies in the interlayers and double edge-sharing (DES) complexes on lateral edge surfaces. Although the TCS surface complex has been well characterized by spectroscopy, some important questions remain about the structure and stability of the complexes occurring on the edge surfaces. First-principles simulation techniques such as density functional theory (DFT) offer a useful way to address these questions by providing complementary information that is difficult to obtain by spectroscopy. Following this computational approach, we used spin-polarized DFT to perform total-energy-minimization geometry optimizations of several possible Pb(II) surface complexes on model birnessite nanoparticles similar to those that have been studied experimentally. We first validated our DFT calculations by geometry optimizations of (1) the Pb-Mn oxyhydroxide mineral, quenselite (PbMnO{sub 2}OH), and (2) the TCS surface complex, finding good agreement with experimental structural data while uncovering new information about bonding and stability. Our geometry optimizations of several protonated variants of the DES surface complex led us to conclude that the observed edge-surface species is very likely to be this complex if the singly-coordinated terminal O that binds to Pb(II) is protonated. Our geometry optimizations also revealed that an unhydrated double corner-sharing (DCS) species that has been proposed as an alternative to the DES complex is intrinsically unstable on nanoparticle edge surfaces, but could become stabilized if the local coordination environment is well-hydrated. A significant similarity exists

  17. Layer-structured hexagonal boron nitride carbon semiconductor alloys for deep UV photonics

    Science.gov (United States)

    Uddin, Md Rakib; Li, Jing; Lin, Jingyu; Jiang, Hongxing

    2015-03-01

    Hexagonal boron nitride carbon alloys, h - (BN)1-x(C2)x, are layer-structured semiconductor materials with a tunable bandgap energy from 0 eV (graphite) to 6.5 eV (h-BN). We report on synthesizing (BN)-rich h - (BN)1-x(C2)x semiconductor alloys using standard MOCVD growth technique on sapphire substrate. Bandgap energy variation with carbon concentration in the deep UV spectral range has been demonstrated through optical absorption measurements. Experimental results suggest that the critical carbon concentration (xc) to form the homogenous h - (BN)1-x(C2)x alloys is about 3.2% at a growth temperature of 1300 °C. It is expected that homogenous h - (BN)1-x(C2)x alloys with higher x can be achieved by increasing the growth temperature. This is a huge advantage over the InGaN alloy system in which higher growth temperatures cannot be utilized to close the miscibility gap. Together with our ability for producing high quality h-BN epilayers, h-(BN)C alloys and quantum wells open up new possibilities for realizing novel 2D optoelectronic devices with tunable physical properties. National Science Foundation.

  18. Mapping the layer count of few-layer hexagonal boron nitride at high lateral spatial resolutions

    Science.gov (United States)

    Mohsin, Ali; Cross, Nicholas G.; Liu, Lei; Watanabe, Kenji; Taniguchi, Takashi; Duscher, Gerd; Gu, Gong

    2018-01-01

    Layer count control and uniformity of two dimensional (2D) layered materials are critical to the investigation of their properties and to their electronic device applications, but methods to map 2D material layer count at nanometer-level lateral spatial resolutions have been lacking. Here, we demonstrate a method based on two complementary techniques widely available in transmission electron microscopes (TEMs) to map the layer count of multilayer hexagonal boron nitride (h-BN) films. The mass-thickness contrast in high-angle annular dark-field (HAADF) imaging in the scanning transmission electron microscope (STEM) mode allows for thickness determination in atomically clean regions with high spatial resolution (sub-nanometer), but is limited by surface contamination. To complement, another technique based on the boron K ionization edge in the electron energy loss spectroscopy spectrum (EELS) of h-BN is developed to quantify the layer count so that surface contamination does not cause an overestimate, albeit at a lower spatial resolution (nanometers). The two techniques agree remarkably well in atomically clean regions with discrepancies within  ±1 layer. For the first time, the layer count uniformity on the scale of nanometers is quantified for a 2D material. The methodology is applicable to layer count mapping of other 2D layered materials, paving the way toward the synthesis of multilayer 2D materials with homogeneous layer count.

  19. Integrated care through disease-oriented critical paths:experience from Japan’s regional health planning initiatives

    Directory of Open Access Journals (Sweden)

    Etsuji Okamoto

    2011-09-01

    Full Text Available Introduction: In April 2008, Japan launched a radical reform in regional health planning that emphasized the development of disease-oriented clinical care pathways. These 'inter-provider critical paths' have sought to ensure effective integration of various providers ranging among primary care practitioners, acute care hospitals, rehabilitation hospitals, long-term care facilities and home care.  Description of policy practice: All 47 prefectures in Japan developed their Regional Health Plans pursuant to the guideline requiring that these should include at least four diseases: diabetes, acute myocardial infarction, cerebrovascular accident and cancer.  To illustrate the care pathways developed, this paper describes the guideline referring to strokes and provides examples of the new Regional Health Plans as well as examples of disease-oriented inter-provider clinical paths. In particular, the paper examines the development of information sharing through electronic health records (EHR to enhance effective integration among providers is discussed.Discussion and conclusion: Japan's reform in 2008 is unique in that the concept of "disease-oriented regional inter-provider critical paths" was adopted as a national policy and all 47 prefectures developed their Regional Health Plans simultaneously. How much the new regional health planning policy has improved the quality and outcome of care remains to be seen and will be evaluated in 2013 after the five year planned period of implementation has concluded. Whilst electronic health records appear to be a useful tool in supporting care integration they do not guarantee success in the application of an inter-provider critical path.

  20. Integrated care through disease-oriented critical paths:experience from Japan’s regional health planning initiatives

    Directory of Open Access Journals (Sweden)

    Etsuji Okamoto

    2011-09-01

    Full Text Available Introduction: In April 2008, Japan launched a radical reform in regional health planning that emphasized the development of disease-oriented clinical care pathways. These 'inter-provider critical paths' have sought to ensure effective integration of various providers ranging among primary care practitioners, acute care hospitals, rehabilitation hospitals, long-term care facilities and home care.   Description of policy practice: All 47 prefectures in Japan developed their Regional Health Plans pursuant to the guideline requiring that these should include at least four diseases: diabetes, acute myocardial infarction, cerebrovascular accident and cancer.  To illustrate the care pathways developed, this paper describes the guideline referring to strokes and provides examples of the new Regional Health Plans as well as examples of disease-oriented inter-provider clinical paths. In particular, the paper examines the development of information sharing through electronic health records (EHR to enhance effective integration among providers is discussed. Discussion and conclusion: Japan's reform in 2008 is unique in that the concept of "disease-oriented regional inter-provider critical paths" was adopted as a national policy and all 47 prefectures developed their Regional Health Plans simultaneously. How much the new regional health planning policy has improved the quality and outcome of care remains to be seen and will be evaluated in 2013 after the five year planned period of implementation has concluded. Whilst electronic health records appear to be a useful tool in supporting care integration they do not guarantee success in the application of an inter-provider critical path.

  1. Controllable synthesis of hexagonal ZnO–carbon core–shell microrods and the removal of ZnO to form hexagonal carbon microtubes

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Yong, E-mail: xy91007@163.com [Department of Applied Chemistry, South China Agricultural University, Guangzhou 510642 (China); He, Wenqi; Gao, Chuang [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); Zheng, Mingtao; Lie, Bingfu; Liu, Xiaotang [Department of Applied Chemistry, South China Agricultural University, Guangzhou 510642 (China); Liu, Yingliang, E-mail: tliuyl@163.com [Department of Applied Chemistry, South China Agricultural University, Guangzhou 510642 (China)

    2013-06-15

    A simple and efficient approach was developed to produce regular and uniform shaped hexagonal ZnO–C core–shell micro-rods and carbon micro-tubes. A single-source raw material, zinc acetate dihydrate, has been used for the in situ generation of the hexagonal ZnO–C micro-rods in a sealed autoclave system at 500 °C for 12 h without a catalyst. The resulting products were characterized by X-ray powder diffraction, scanning and transmission electron microscopy, energy-dispersive X-ray analysis and room-temperature photoluminescence spectroscopy (PL). The partial or complete carbon coating on the ZnO surfaces plays an important role in modifying the PL properties. Impacting factors including thermolysis temperature, time and dose of the reactant on the evolution of the hexagonal shape were investigated. A possible formation diagram for the materials has been proposed and discussed based on the features of the reaction system. - Highlights: • Hexagonal ZnO–C core–shell microrods were synthesized by the lower temperature decomposition of zinc acetate. • The novel hexagonal carbon microtubes can gain by simply handling with dilute acid. • The partial or complete carbon coating on the ZnO surfaces plays an important role in modifying the PL properties. • A possible formation diagram for the materials has been proposed.

  2. The Prompt Fission Neutron Spectrum: From Experiment to the Evaluated Data and its Impact on Critical Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Rising, Michael Evan [Los Alamos National Laboratory

    2015-06-10

    After a brief introduction concerning nuclear data, prompt fission neutron spectrum (PFNS) evaluations and the limited PFNS covariance data in the ENDF/B-VII library, and the important fact that cross section uncertainties ~ PFNS uncertainties, the author presents background information on the PFNS (experimental data, theoretical models, data evaluation, uncertainty quantification) and discusses the impact on certain well-known critical assemblies with regard to integral quantities, sensitivity analysis, and uncertainty propagation. He sketches recent and ongoing research and concludes with some final thoughts.

  3. Self-criticism, dependency, and stress reactivity: an experience sampling approach to testing Blatt and Zuroff's (1992) theory of personality predispositions to depression in high-risk youth.

    Science.gov (United States)

    Adams, Philippe; Abela, John R Z; Auerbach, Randy; Skitch, Steven

    2009-11-01

    S. J. Blatt and D. C. Zuroff's 1992 theory of personality predispositions to depression posits that individuals who possess high levels of self-criticism and/or dependency are vulnerable to developing depression following negative events. The current study used experience sampling methodology to test this theory in a sample of 49 children ages 7 to 14. Children completed measures of dependency, self-criticism, and depressive symptoms. Subsequently, children were given a handheld computer that signaled them to complete measures of depressive symptoms and negative events at randomly selected times over 2 months. Results of hierarchical linear modeling analyses indicated that higher levels of both self-criticism and dependency were associated with greater elevations in depressive symptoms following negative events. Furthermore, each personality predisposition remained a significant predictor of such elevations after controlling for the interaction between the other personality predisposition and negative events. The results suggest that dependency and self-criticism represent distinct vulnerability factors to depression in youth.

  4. Twist-induced birefringence in hexagonal photonic fibers

    Science.gov (United States)

    Tentori, D.; Garcia-Weidner, A.; Torres-Gómez, I.

    2011-09-01

    Photonic crystal optical fibers have much more degrees of freedom concerning the geometries and index contrasts than step-index fibers; therefore, the theoretical analysis of their performance is usually based on the finite element method. In this work, taking advantage of the similarities observed for twisted single-mode fibers: standard (SMF-28 and SMF- 28e) and hexagonal photonic fibers, we propose that in regard with polarization performance, photonic fibers can be described using a simpler model based on classical polarization optics. The main advantages of the matrix model we propose lie in its accuracy and generality: for each one of the selected wavelengths and input states of polarization, it allows a precise prediction of the output polarization state. The comparison of the experimental results measured for standard and photonic fibers with the theoretical model predictions indicates that in both cases, twist induced birefringence is produced not only by the medium's photoelasticity, but also by the waveguide (cladding/core structure and asymmetry) modification. In addition, for the photonic fiber, the non-symmetrical response to right and left twist allowed the identification of an initial twist as part of the residual elliptical birefringence.

  5. Understanding Multiferroic Hexagonal Manganites by Static and Ultrafast Optical Spectroscopy

    Directory of Open Access Journals (Sweden)

    Yu Ting Wang

    2013-01-01

    Full Text Available Multiferroic hexagonal manganites ReMnO3 studied by optics are reviewed. Their electronic structures were revealed by static linear and nonlinear spectra. Two transitions located at ~1.7 eV and ~2.3 eV have been observed and attributed to the interband transitions from the lower-lying Mn3+dxy/dx2-y2 and dxz/dyz states to the Mn3+d3z2-r2 state, respectively. These so-called d-d transitions exhibit a blueshift as decreasing temperatures and an extra blueshift near TN. This dramatic change indicates that the magnetic ordering seriously influences the electronic structure. On the other hand, the ultrafast optical pump-probe spectroscopy has provided the important information on spin-charge coupling and spin-lattice coupling. Because of the strongly correlation between electronic structure and magnetic ordering, the amplitude of the initial rising component in ΔR/R shows striking changes at the vicinity of TN. Moreover, the coherent optical and acoustic phonons were observed on optical pump-probe spectroscopy. Both the amplitude and dephasing time of coherent phonons also exhibit significant changes at TN, which provide the evidence for spin-lattice interaction in these intriguing materials.

  6. Facile synthesis and structure characterization of hexagonal tungsten bronzes crystals

    Science.gov (United States)

    Lee, Jiann-Shing; Liu, Hao-Chuan; Peng, Gao-De; Tseng, Yawteng

    2017-05-01

    A facile molten-salt route was used to synthesize hexagonal Cs0.33WO3, Rb0.33WO3 and K0.30WO3 crystals. The three isostructural compounds were successfully prepared from the reaction of MxWO3 powders (M = Cs, Rb, K) in the CsCl/NaCl, RbCl/NaCl and KCl/NaCl fluxes, respectively. The structure determination and refinement, based on single-crystal X-ray diffraction data, are in agreement with previous works, possessing space group P63/mcm. The a and c parameters vary non-linearly with increasing radii of the M+ cations (rM) that is coordinated to twelve oxygen atoms. Both the volumes of unit-cell and WO6 octahedra vary linearly with rM, which become smaller from Cs0.33WO3 to K0.30WO3. The distortion of WO6 octahedra as well as isotropic displacement parameters increases from Cs0.33WO3 to K0.30WO3. The geometry of the WO6 octahedron becomes more regular with increasing rM. These structural trends arise from the effective size of the M+ cation.

  7. Thermal stability of simple tetragonal and hexagonal diamond germanium

    Science.gov (United States)

    Huston, L. Q.; Johnson, B. C.; Haberl, B.; Wong, S.; Williams, J. S.; Bradby, J. E.

    2017-11-01

    Exotic phases of germanium, that form under high pressure but persist under ambient conditions, are of technological interest due to their unique optical and electrical properties. The thermal evolution and stability of two of these exotic Ge phases, the simple tetragonal (st12) and hexagonal diamond (hd) phases, are investigated in detail. These metastable phases, formed by high pressure decompression in either a diamond anvil cell or by nanoindentation, are annealed at temperatures ranging from 280 to 320 °C for st12-Ge and 200 to 550 °C for hd-Ge. In both cases, the exotic phases originated from entirely pure Ge precursor materials. Raman microspectroscopy is used to monitor the phase changes ex situ following annealing. Our results show that hd-Ge synthesized via a pure form of a-Ge first undergoes a subtle change in structure and then an irreversible phase transformation to dc-Ge with an activation energy of (4.3 ± 0.2) eV at higher temperatures. St12-Ge was found to transform to dc-Ge with an activation energy of (1.44 ± 0.08) eV. Taken together with results from previous studies, this study allows for intriguing comparisons with silicon and suggests promising technological applications.

  8. Exfoliation of Hexagonal Boron Nitride via Ferric Chloride Intercalation

    Science.gov (United States)

    Hung, Ching-cheh; Hurst, Janet; Santiago, Diana; Rogers, Richard B.

    2014-01-01

    Sodium fluoride (NaF) was used as an activation agent to successfully intercalate ferric chloride (FeCl3) into hexagonal boron nitride (hBN). This reaction caused the hBN mass to increase by approx.100 percent, the lattice parameter c to decrease from 6.6585 to between 6.6565 and 6.6569 ?, the x-ray diffraction (XRD) (002) peak to widen from 0.01deg to 0.05deg of the full width half maximum value, the Fourier transform infrared (FTIR) spectrum's broad band (1277/cm peak) to change shape, and new FTIR bands to emerge at 3700 to 2700 and 1600/cm. This indicates hBN's structural and chemical properties are significantly changed. The intercalated product was hygroscopic and interacted with moisture in the air to cause further structural and chemical changes (from XRD and FTIR). During a 24-h hold at room temperature in air with 100 percent relative humidity, the mass increased another 141 percent. The intercalated product, hydrated or not, can be heated to 750 C in air to cause exfoliation. Exfoliation becomes significant after two intercalation-air heating cycles, when 20-nm nanosheets are commonly found. Structural and chemical changes indicated by XRD and FTIR data were nearly reversed after the product was placed in hydrochloric acid (HCl), resulting in purified, exfoliated, thin hBN products.

  9. Quantum Light in Curved Low Dimensional Hexagonal Boron Nitride Systems.

    Science.gov (United States)

    Chejanovsky, Nathan; Kim, Youngwook; Zappe, Andrea; Stuhlhofer, Benjamin; Taniguchi, Takashi; Watanabe, Kenji; Dasari, Durga; Finkler, Amit; Smet, Jurgen H; Wrachtrup, Jörg

    2017-11-07

    Low-dimensional wide bandgap semiconductors open a new playing field in quantum optics using sub-bandgap excitation. In this field, hexagonal boron nitride (h-BN) has been reported to host single quantum emitters (QEs), linking QE density to perimeters. Furthermore, curvature/perimeters in transition metal dichalcogenides (TMDCs) have demonstrated a key role in QE formation. We investigate a curvature-abundant BN system - quasi one-dimensional BN nanotubes (BNNTs) fabricated via a catalyst-free method. We find that non-treated BNNT is an abundant source of stable QEs and analyze their emission features down to single nanotubes, comparing dispersed/suspended material. Combining high spatial resolution of a scanning electron microscope, we categorize and pin-point emission origin to a scale of less than 20 nm, giving us a one-to-one validation of emission source with dimensions smaller than the laser excitation wavelength, elucidating nano-antenna effects. Two emission origins emerge: hybrid/entwined BNNT. By artificially curving h-BN flakes, similar QE spectral features are observed. The impact on emission of solvents used in commercial products and curved regions is also demonstrated. The 'out of the box' availability of QEs in BNNT, lacking processing contamination, is a milestone for unraveling their atomic features. These findings open possibilities for precision engineering of QEs, puts h-BN under a similar 'umbrella' of TMDC's QEs and provides a model explaining QEs spatial localization/formation using electron/ion irradiation and chemical etching.

  10. The ARIANNA Hexagonal Radio Array – performance and prospects

    Directory of Open Access Journals (Sweden)

    Hallgren Allan

    2016-01-01

    Full Text Available The origin of the highest energy cosmic rays at ∼1020 eV is still unknown. Ultra-high energy neutrinos from the GZK process should provide information on the sources and their properties. A promising and cost effective method for observing GZK-neutrinos is based on detection of Askaryan radio pulses with antennas installed in ice. The ARIANNA project aims at instrumenting a 36*36 km2 large area on the Ross Ice Shelf with an array of radio detection stations. The deployment of a test system for ARIANNA, the Hexagonal Radio Array (HRA, was completed in December 2014. The three first stations were installed in 2012. Solar panels are used to drive the < 10 W stations. The system hibernated at sunset in April and all stations returned to operation in September. The site is essentially free of anthropogenic noise. Simple cuts eliminate background and provides for efficient selection of neutrino events. Prospects for the sensitivity of the full ARIANNA array to the flux of GZK neutrinos are shown.

  11. Step flow versus mosaic film growth in hexagonal boron nitride.

    Science.gov (United States)

    Lu, Jiong; Yeo, Pei Shan Emmeline; Zheng, Yi; Xu, Hai; Gan, Chee Kwan; Sullivan, Michael B; Castro Neto, A H; Loh, Kian Ping

    2013-02-13

    Many emerging applications of hexagonal boron nitride (h-BN) in graphene-based nanoelectronics require high-quality monolayers as the ultrathin dielectric. Here, the nucleation and growth of h-BN monolayer on Ru(0001) surface are investigated using scanning tunneling microscopy with a view toward understanding the process of defect formation on a strongly interacted interface. In contrast to homoelemental bonding in graphene, the heteroelemental nature of h-BN gives rise to growth fronts with elemental polarity. This can have consequences in the different stages of film growth, from the nucleation of h-BN magic clusters and their sintering to form compact triangular islands to the growth of patchwork mosaic monolayer with a high density of misfit boundaries. The parallel alignment of triangular islands on the same terrace produces translational fault lines when growth fronts merge, while antiparallel alignment of islands on adjacent terraces produces non-bonded fault lines between domains terminated by like atoms. With these insights into the generation of void defects and fault lines at grain boundaries, we demonstrate a strategy to obtain high-quality h-BN monolayer film based on step flow growth.

  12. Graphene on hexagonal boron nitride as a tunable hyperbolic metamaterial.

    Science.gov (United States)

    Dai, S; Ma, Q; Liu, M K; Andersen, T; Fei, Z; Goldflam, M D; Wagner, M; Watanabe, K; Taniguchi, T; Thiemens, M; Keilmann, F; Janssen, G C A M; Zhu, S-E; Jarillo-Herrero, P; Fogler, M M; Basov, D N

    2015-08-01

    Hexagonal boron nitride (h-BN) is a natural hyperbolic material, in which the dielectric constants are the same in the basal plane (ε(t) ≡ ε(x) = ε(y)) but have opposite signs (ε(t)ε(z) graphene on h-BN. Tunability originates from the hybridization of surface plasmon polaritons in graphene with hyperbolic phonon polaritons in h-BN, so that the eigenmodes of the graphene/h-BN heterostructure are hyperbolic plasmon-phonon polaritons. The hyperbolic plasmon-phonon polaritons in graphene/h-BN suffer little from ohmic losses, making their propagation length 1.5-2.0 times greater than that of hyperbolic phonon polaritons in h-BN. The hyperbolic plasmon-phonon polaritons possess the combined virtues of surface plasmon polaritons in graphene and hyperbolic phonon polaritons in h-BN. Therefore, graphene/h-BN can be classified as an electromagnetic metamaterial as the resulting properties of these devices are not present in its constituent elements alone.

  13. Hexagonal boron nitride nanowalls: physical vapour deposition, 2D/3D morphology and spectroscopic analysis

    Science.gov (United States)

    BenMoussa, B.; D'Haen, J.; Borschel, C.; Barjon, J.; Soltani, A.; Mortet, V.; Ronning, C.; D'Olieslaeger, M.; Boyen, H.-G.; Haenen, K.

    2012-04-01

    Hexagonal boron nitride nanowalls were synthesized using reactive radio-frequency magnetron sputtering in combination with a hexagonal BN target. The nanowall formation is purely governed by addition of hydrogen to the nitrogen/argon gas mixture, and leads to a decreased incorporation of carbon and oxygen impurities. The surface morphology is assessed with scanning electron microscopy, while stoichiometry and reduced impurity content of the material was evidenced using Rutherford backscattering spectroscopy. Transmission electron microscopy confirms the hexagonal nature of the nanowalls, whose luminescent properties are studied with cathodoluminescence spectroscopy, shedding more light on the location and nature of the excitonic emission and crystalline quality of the h-BN nanowalls.

  14. Comparison between SVPWM two level in internal and external circle of hexagon

    Science.gov (United States)

    Giyantara, Andhika; Rameli, Mochammad

    2017-01-01

    This study presents a space vector pulse width modulation (SVPWM) method. Switching time for SVPWM two level is used to generate a sinusoidal waveform from the inverter. This waveform using as input for the induction motor. Usually, we use the internal circle to generate sinusoidal method. However, from the calculation, we can get two different equations, for the internal circle in hexagon and external circle for the hexagon. Comparison between voltage vector in the internal and external circle of hexagon using THD (Total Harmonic Distortion) value for each circle.

  15. Critical Heat Flux Phenomena at HighPressure & Low Mass Fluxes: NEUP Final Report Part I: Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Corradini, Michael [Univ. of Wisconsin, Madison, WI (United States); Wu, Qiao [Oregon State Univ., Corvallis, OR (United States)

    2015-04-30

    This report is a preliminary document presenting an overview of the Critical Heat Flux (CHF) phenomenon, the High Pressure Critical Heat Flux facility (HPCHF), preliminary CHF data acquired, and the future direction of the research. The HPCHF facility has been designed and built to study CHF at high pressure and low mass flux ranges in a rod bundle prototypical of conceptual Small Modular Reactor (SMR) designs. The rod bundle is comprised of four electrically heated rods in a 2x2 square rod bundle with a prototypic chopped-cosine axial power profile and equipped with thermocouples at various axial and circumferential positions embedded in each rod for CHF detection. Experimental test parameters for CHF detection range from pressures of ~80 – 160 bar, mass fluxes of ~400 – 1500 kg/m2s, and inlet water subcooling from ~30 – 70°C. The preliminary data base established will be further extended in the future along with comparisons to existing CHF correlations, models, etc. whose application ranges may be applicable to the conditions of SMRs.

  16. Rotational symmetry breaking in the topological superconductor SrxBi2Se3 probed by upper-critical field experiments.

    Science.gov (United States)

    Pan, Y; Nikitin, A M; Araizi, G K; Huang, Y K; Matsushita, Y; Naka, T; de Visser, A

    2016-06-28

    Recently it was demonstrated that Sr intercalation provides a new route to induce superconductivity in the topological insulator Bi2Se3. Topological superconductors are predicted to be unconventional with an odd-parity pairing symmetry. An adequate probe to test for unconventional superconductivity is the upper critical field, Bc2. For a standard BCS layered superconductor Bc2 shows an anisotropy when the magnetic field is applied parallel and perpendicular to the layers, but is isotropic when the field is rotated in the plane of the layers. Here we report measurements of the upper critical field of superconducting SrxBi2Se3 crystals (Tc = 3.0 K). Surprisingly, field-angle dependent magnetotransport measurements reveal a large anisotropy of Bc2 when the magnet field is rotated in the basal plane. The large two-fold anisotropy, while six-fold is anticipated, cannot be explained with the Ginzburg-Landau anisotropic effective mass model or flux flow induced by the Lorentz force. The rotational symmetry breaking of Bc2 indicates unconventional superconductivity with odd-parity spin-triplet Cooper pairs (Δ4-pairing) recently proposed for rhombohedral topological superconductors, or might have a structural nature, such as self-organized stripe ordering of Sr atoms.

  17. Optimization of Fast Critical Experiments to Reduce Nuclear Data Uncertainties in Support of a Fast Burner Reactor Design Concept

    Science.gov (United States)

    Stover, Tracy E., Jr.

    An optimization technique has been developed to select optimized experimental design specifications to produce data specifically designed to be assimilated to optimize a given reactor concept. Data from the optimized experiment is assimilated to generate posteriori uncertainties on the reactor concept's core attributes from which the design responses are computed. The reactor concept is then optimized with the new data to realize cost savings by reducing margin. The optimization problem iterates until an optimal experiment is found to maximize the savings. A new generation of innovative nuclear reactor designs, in particular fast neutron spectrum recycle reactors, are being considered for the application of closing the nuclear fuel cycle in the future. Safe and economical design of these reactors will require uncertainty reduction in basic nuclear data which are input to the reactor design. These data uncertainty propagate to design responses which in turn require the reactor designer to incorporate additional safety margin into the design, which often increases the cost of the reactor. Therefore basic nuclear data needs to be improved and this is accomplished through experimentation. Considering the high cost of nuclear experiments, it is desired to have an optimized experiment which will provide the data needed for uncertainty reduction such that a reactor design concept can meet its target accuracies or to allow savings to be realized by reducing the margin required due to uncertainty propagated from basic nuclear data. However, this optimization is coupled to the reactor design itself because with improved data the reactor concept can be re-optimized itself. It is thus desired to find the experiment that gives the best optimized reactor design. Methods are first established to model both the reactor concept and the experiment and to efficiently propagate the basic nuclear data uncertainty through these models to outputs. The representativity of the experiment

  18. A complexity basis for phenomenology: How information states at criticality offer a new approach to understanding experience of self, being and time.

    Science.gov (United States)

    Hankey, Alex

    2015-12-01

    In the late 19th century Husserl studied our internal sense of time passing, maintaining that its deep connections into experience represent prima facie evidence for it as the basis for all investigations in the sciences: Phenomenology was born. Merleau-Ponty focused on perception pointing out that any theory of experience must accord with established aspects of biology i.e. be embodied. Recent analyses suggest that theories of experience require non-reductive, integrative information, together with a specific property connecting them to experience. Here we elucidate a new class of information states with just such properties found at the loci of control of complex biological systems, including nervous systems. Complexity biology concerns states satisfying self-organized criticality. Such states are located at critical instabilities, commonly observed in biological systems, and thought to maximize information diversity and processing, and hence to optimize regulation. Major results for biology follow: why organisms have unusually low entropies; and why they are not merely mechanical. Criticality states form singular self-observing systems, which reduce wave packets by processes of perfect self-observation associated with feedback gain g = 1. Analysis of their information properties leads to identification of a new kind of information state with high levels of internal coherence, and feedback loops integrated into their structure. The major idea presented here is that the integrated feedback loops are responsible for our 'sense of self', and also the feeling of continuity in our sense of time passing. Long-range internal correlations guarantee a unique kind of non-reductive, integrative information structure enabling such states to naturally support phenomenal experience. Being founded in complexity biology, they are 'embodied'; they also fulfill the statement that 'The self is a process', a singular process. High internal correlations and René Thom

  19. [Experience with knowledge development in food handlers with te implementation of Hazard Analysis Critical control points (HACCP) in a hospital food service].

    Science.gov (United States)

    de Sousa, A A; de Salles, R K; Felipe, M R; Tosin, I

    1999-03-01

    The present article has as objective to describe the methodology of an experience of implantation of Hazard Analyses Critical Control Points (HACCP) with food handlers in a hospital food service establishment, inside of a conception of relationship and construction of knowledge. Meetings with the food handlers and nutritionists, with the objective of raising the difficulties poined for the sector and the work to be developed. The HACCP consisted of the evaluation of the operations, following the sequential steps recommended, looking itself to instruct the food handlers on the methods of the operations and its interpretations. The detected critical points, the measures of control, the criteria of correction and the monitoring have widely been argued, serving as didactic elements for the reconstruction of quality of the preparations. The discussions generated actions that were developed in short term, revealing the need of a more effective and continuous partnership for the new proposals.

  20. JENDL-3.2 performance in analyses of MISTRAL critical experiments for high-moderation MOX cores

    Energy Technology Data Exchange (ETDEWEB)

    Takada, Naoyuki [Nuclear Fuel Industries, Ltd., Fuel Engineering and Development Department, Tokai, Ibaraki (Japan); Hibi, Koki [Mitsubishi Heavy Industries Ltd., Tokyo (Japan); Ishii, Kazuya [Hitachi Ltd., Tokyo (Japan); Ando, Yoshihira [Toshiba Corp., Tokyo (Japan); Yamamoto, Toru; Ueji, Masao; Iwata, Yutaka [Nuclear Power Engineering Corp., Tokyo (Japan)

    2001-03-01

    NUPEC and CEA have launched an extensive experimental program called MISTRAL to study highly moderated MOX cores for the advanced LWRs. The analyses using SRAC system and MVP code with JENDL-3.2 library are in progress on the experiments of the MISTRAL and the former EPICURE programs. Various comparisons have been made between calculation results and measurement values. (author)

  1. Measuring the Coefficient of Restitution and More: A Simple Experiment to Promote Students' Critical Thinking and Autonomous Work

    Science.gov (United States)

    González, Manuel Á.; González, Miguel Á.; Vegas, Jesús; Llamas, César

    2017-01-01

    A simple experiment on the determination of the coefficient of restitution of different materials is taken as the basis of an extendable work that can be done by students in an autonomous way. On the whole, the work described in this paper would involve concepts of kinematics, materials science, air drag and buoyancy, and would help students to…

  2. Improving Critical Thinking "via" Authenticity: The CASPiE Research Experience in a Military Academy Chemistry Course

    Science.gov (United States)

    Chase, A. M.; Clancy, H. A.; Lachance, R. P.; Mathison, B. M.; Chiu, M. M.; Weaver, G. C.

    2017-01-01

    Course-based undergraduate research experiences (CUREs) can introduce many students to authentic research activities in a cost-effective manner. Past studies have shown that students who participated in CUREs report greater interest in chemistry, better data collection and analysis skills, and enhanced scientific reasoning compared to traditional…

  3. Growth and Expansion of the International Criticality Safety Benchmark Evaluation Project and the Newly Organized International Reactor Physics Experiment Evaluation Project

    Energy Technology Data Exchange (ETDEWEB)

    J. Blair Briggs; Lori Scott; Yolanda Rugama; Enrico Satori

    2007-05-01

    Since ICNC 2003, the International Criticality Safety Benchmark Evaluation Project (ICSBEP) has continued to expand its efforts and broaden its scope. Criticality-alarm / shielding type benchmarks and fundamental physics measurements that are relevant to criticality safety applications are not only included in the scope of the project, but benchmark data are also included in the latest version of the handbook. A considerable number of improvements have been made to the searchable database, DICE and the criticality-alarm / shielding benchmarks and fundamental physics measurements have been included in the database. There were 12 countries participating on the ICSBEP in 2003. That number has increased to 18 with recent contributions of data and/or resources from Brazil, Czech Republic, Poland, India, Canada, and China. South Africa, Germany, Argentina, and Australia have been invited to participate. Since ICNC 2003, the contents of the “International Handbook of Evaluated Criticality Safety Benchmark Experiments” have increased from 350 evaluations (28,000 pages) containing benchmark specifications for 3070 critical or subcritical configurations to 442 evaluations (over 38,000 pages) containing benchmark specifications for 3957 critical or subcritical configurations, 23 criticality-alarm-placement / shielding configurations with multiple dose points for each, and 20 configurations that have been categorized as fundamental physics measurements that are relevant to criticality safety applications in the 2006 Edition of the ICSBEP Handbook. Approximately 30 new evaluations and 250 additional configurations are expected to be added to the 2007 Edition of the Handbook. Since ICNC 2003, a reactor physics counterpart to the ICSBEP, The International Reactor Physics Experiment Evaluation Project (IRPhEP) was initiated. Beginning in 1999, the IRPhEP was conducted as a pilot activity by the by the Organization of Economic Cooperation and Development (OECD) Nuclear Energy

  4. The CIV processes in the CRIT experiments. [reconciliation of Critical Ionization Velocity hypothesis with sounding rocket observations

    Science.gov (United States)

    Papadopoulos, K.

    1992-01-01

    A qualitative analysis is conducted to reconcile the experimental data from critical ionization velocity (CIV) studies with CIV theories. The experimental data are reviewed demonstrating that: (1) the wave frequency is variable and low; (2) the wave polarization is almost isotropic; (3) electron energization is not easily reconciled with the observed wave spectrum; and (4) ambient electron density plays a role in determining CIV triggering conditions. Analytical treatment is given to the dispersion relation of the lower hybrid wave (LWH) instability driven by the streaming of an ion beam generated by the interaction of the neutral cloud with the ambient atmosphere. By incorporating the LWH instabilities of strong turbulence and finite-size effects into theoretical CIV relationships, the observations can be interpreted. The issues raised by the experimental data are understood within the context of a hypothesis of backward propagating nonlinearly collapsing wavepackets.

  5. Five-year experience of critical incidents associated with patient-controlled analgesia in an Irish University Hospital.

    LENUS (Irish Health Repository)

    Ahmad, I

    2012-02-01

    BACKGROUND: Patient-controlled analgesia (PCA) is a common and effective means of managing post-operative pain. We sought to identify factors that may lead to critical incidents (CIs) in patient safety when using PCA in our institution. METHODS: An observational study of prospectively collected data of patients who received PCA from 2002 to 2006 was performed. All CIs were documented and analysed by staff members of the acute pain service (APS). Cause analysis of CIs was undertaken to determine if measures can be instituted to prevent recurrence of similar events. RESULTS: Over eight thousand patients (8,240) received PCA. Twenty-seven CIs were identified. Eighteen were due to programming errors. Other CIs included co-administration of opioids and oversedation. CONCLUSION: In our institution, the largest contributory factor to CIs with PCAs was programming error. Strategies to minimize this problem include better education and surveillance.

  6. Nonoperative active management of critical limb ischemia: initial experience using a sequential compression biomechanical device for limb salvage.

    LENUS (Irish Health Repository)

    Sultan, Sherif

    2008-01-01

    Critical limb ischemia (CLI) patients are at high risk of primary amputation. Using a sequential compression biomechanical device (SCBD) represents a nonoperative option in threatened limbs. We aimed to determine the outcome of using SCBD in amputation-bound nonreconstructable CLI patients regarding limb salvage and 90-day mortality. Thirty-five patients with 39 critically ischemic limbs (rest pain = 12, tissue loss = 27) presented over 24 months. Thirty patients had nonreconstructable arterial outflow vessels, and five were inoperable owing to severe comorbidity scores. All were Rutherford classification 4 or 5 with multilevel disease. All underwent a 12-week treatment protocol and received the best medical treatment. The mean follow-up was 10 months (SD +\\/- 6 months). There were four amputations, with an 18-month cumulative limb salvage rate of 88% (standard error [SE] +\\/- 7.62%). Ninety-day mortality was zero. Mean toe pressures increased from 38.2 to 67 mm Hg (SD +\\/- 33.7, 95% confidence interval [CI] 55-79). Popliteal artery flow velocity increased from 45 to 47.9 cm\\/s (95% CI 35.9-59.7). Cumulative survival at 12 months was 81.2% (SE +\\/- 11.1) for SCBD, compared with 69.2% in the control group (SE +\\/- 12.8%) (p = .4, hazards ratio = 0.58, 95% CI 0.15-2.32). The mean total cost of primary amputation per patient is euro29,815 ($44,000) in comparison with euro13,900 ($20,515) for SCBD patients. SCBD enhances limb salvage and reduces length of hospital stay, nonoperatively, in patients with nonreconstructable vessels.

  7. Melioidosis Causing Critical Illness: A Review of 24 Years of Experience From the Royal Darwin Hospital ICU.

    Science.gov (United States)

    Stephens, Dianne P; Thomas, Jane H; Ward, Linda M; Currie, Bart J

    2016-08-01

    Melioidosis is increasing in incidence with newly recognized foci of melioidosis in the Americas, Africa, and elsewhere. This review describes the demographics, management, and outcomes of a large cohort of critically ill patients with melioidosis. Data were extracted from two prospective databases-the Menzies School of Health Research Melioidosis Database (1989-2013) and the Royal Darwin Hospital ICU Melioidosis Database (2001-2013). The Royal Darwin Hospital ICU is the only ICU in the tropical Top End of Northern Territory of Australia, an endemic area for melioidosis. The study included all patients with melioidosis admitted to Royal Darwin Hospital ICU from 1989 to 2013. From 1989 to 2013, 207 patients with melioidosis required admission to ICU. Mortality reduced from 92% (1989-1997) to 26% (1998-2013) (p < 0.001). The reduced mortality coincided with the introduction of an intensivist-led service, meropenem, and adjuvant granulocyte colony-stimulating factor for confirmed melioidosis sepsis in 1998. Pneumonia was the presenting illness in 155 of 207 (75%). ICU melioidosis patients (2001-2013) had an Acute Physiology and Chronic Health Evaluation II score of 23, median length of stay in the ICU of 7 days, and median ventilation hours of 130 and one third required renal replacement therapy. The mortality for critically ill patients with melioidosis in the Top End of the Northern Territory of Australia has substantially reduced over the past 24 years. The reduction in mortality coincided with the introduction of an intensivist-led model of care, the empiric use of meropenem, and adjunctive treatment with granulocyte colony-stimulating factor in 1998.

  8. Encouraging PV Adoption in New Market-Rate ResidentialConstruction: A Critical Review of Program Experiences to Date

    Energy Technology Data Exchange (ETDEWEB)

    Barbose, Galen; Wiser, Ryan; Bolinger, Mark

    2006-04-24

    In this paper, we review experiences with programs to support the deployment of photovoltaics (PV) in new, market-rate homes, drawing upon interviews with program managers around the country, project data, and publicly-available documentation on program design, impacts, and experiences. We focus on state clean energy funds, which have been established in 14 U.S. states to build markets for clean energy resources, as well as a select number of other state or local organizations whose activities are particularly noteworthy. We describe the types of programs implemented and their impacts to date, and discuss key issues and lessons learned for initiatives aimed at growing the new home market for PV.

  9. Critical appraisal of the impact of individual surgeon experience on the outcomes of laparoscopic liver resection in the modern era: collective experience of multiple surgeons at a single institution with 324 consecutive cases.

    Science.gov (United States)

    Goh, Brian K P; Teo, Jin-Yao; Lee, Ser-Yee; Kam, Juinn-Huar; Cheow, Peng-Chung; Jeyaraj, Premaraj; Chow, Pierce K H; Ooi, London L P J; Chung, Alexander Y F; Chan, Chung-Yip

    2017-09-15

    Most studies analyzing the learning experience of laparoscopic liver resection (LLR) focused on the experience of one or two expert pioneering surgeons. This study aims to critically analyze the impact of individual surgeon experience on the outcomes of LLR based on the contemporary collective experiences of multiple surgeons at single institution. Retrospective review of 324 consecutive LLR from 2006 to 2016. The cases were performed by 10 surgeons over various time periods. Four surgeons had individual experience with 90 cases. The cohort was divided into two groups: comparing a surgeon's experience between the first 20, 30, 40, and 50 cases with patients treated thereafter. Similarly, we performed subset analyses for anterolateral lesions, posterosuperior lesions, and major hepatectomies. As individual surgeons gained increasing experience, this was significantly associated with older patients being operated, decreased hand-assistance, larger tumor size, increased liver resections, increased major resections, and increased resections of tumors located at the posterosuperior segments. This resulted in significantly longer operation time and increased use of Pringle maneuver but no difference in other outcomes. Analysis of LLR for tumors in the posterosuperior segments demonstrated that there was a significant decrease in conversion rates after a surgeon had experience with 20 LLR. For major hepatectomies, there was a significant decrease in morbidity, mortality, and length of stay after acquiring experience with 20 LLR. LLR can be safely adopted today especially for lesions in the anterolateral segments. LLR for lesions in the difficult posterosuperior segments and major hepatectomies especially in cirrhosis should only be attempted by surgeons who have acquired a minimum experience with 20 LLR.

  10. Shock-synthesized hexagonal diamonds in Younger Dryas boundary sediments.

    Science.gov (United States)

    Kennett, Douglas J; Kennett, James P; West, Allen; West, G James; Bunch, Ted E; Culleton, Brendan J; Erlandson, Jon M; Que Hee, Shane S; Johnson, John R; Mercer, Chris; Shen, Feng; Sellers, Marilee; Stafford, Thomas W; Stich, Adrienne; Weaver, James C; Wittke, James H; Wolbach, Wendy S

    2009-08-04

    The long-standing controversy regarding the late Pleistocene megafaunal extinctions in North America has been invigorated by a hypothesis implicating a cosmic impact at the Allerød-Younger Dryas boundary or YDB (approximately 12,900 +/- 100 cal BP or 10,900 +/- 100 (14)C years). Abrupt ecosystem disruption caused by this event may have triggered the megafaunal extinctions, along with reductions in other animal populations, including humans. The hypothesis remains controversial due to absence of shocked minerals, tektites, and impact craters. Here, we report the presence of shock-synthesized hexagonal nanodiamonds (lonsdaleite) in YDB sediments dating to approximately 12,950 +/- 50 cal BP at Arlington Canyon, Santa Rosa Island, California. Lonsdaleite is known on Earth only in meteorites and impact craters, and its presence strongly supports a cosmic impact event, further strengthened by its co-occurrence with other nanometer-sized diamond polymorphs (n-diamonds and cubics). These shock-synthesized diamonds are also associated with proxies indicating major biomass burning (charcoal, carbon spherules, and soot). This biomass burning at the Younger Dryas (YD) onset is regional in extent, based on evidence from adjacent Santa Barbara Basin and coeval with broader continent-wide biomass burning. Biomass burning also coincides with abrupt sediment mass wasting and ecological disruption and the last known occurrence of pygmy mammoths (Mammuthus exilis) on the Channel Islands, correlating with broader animal extinctions throughout North America. The only previously known co-occurrence of nanodiamonds, soot, and extinction is the Cretaceous-Tertiary (K/T) impact layer. These data are consistent with abrupt ecosystem change and megafaunal extinction possibly triggered by a cosmic impact over North America at approximately 12,900 +/- 100 cal BP.

  11. Charge carrier transport properties in layer structured hexagonal boron nitride

    Directory of Open Access Journals (Sweden)

    T. C. Doan

    2014-10-01

    Full Text Available Due to its large in-plane thermal conductivity, high temperature and chemical stability, large energy band gap (˜ 6.4 eV, hexagonal boron nitride (hBN has emerged as an important material for applications in deep ultraviolet photonic devices. Among the members of the III-nitride material system, hBN is the least studied and understood. The study of the electrical transport properties of hBN is of utmost importance with a view to realizing practical device applications. Wafer-scale hBN epilayers have been successfully synthesized by metal organic chemical deposition and their electrical transport properties have been probed by variable temperature Hall effect measurements. The results demonstrate that undoped hBN is a semiconductor exhibiting weak p-type at high temperatures (> 700 °K. The measured acceptor energy level is about 0.68 eV above the valence band. In contrast to the electrical transport properties of traditional III-nitride wide bandgap semiconductors, the temperature dependence of the hole mobility in hBN can be described by the form of μ ∝ (T/T0−α with α = 3.02, satisfying the two-dimensional (2D carrier transport limit dominated by the polar optical phonon scattering. This behavior is a direct consequence of the fact that hBN is a layer structured material. The optical phonon energy deduced from the temperature dependence of the hole mobility is ħω = 192 meV (or 1546 cm-1, which is consistent with values previously obtained using other techniques. The present results extend our understanding of the charge carrier transport properties beyond the traditional III-nitride semiconductors.

  12. Hexagonal boron nitride neutron detectors with high detection efficiencies

    Science.gov (United States)

    Maity, A.; Grenadier, S. J.; Li, J.; Lin, J. Y.; Jiang, H. X.

    2018-01-01

    Neutron detectors fabricated from 10B enriched hexagonal boron nitride (h-10BN or h-BN) epilayers have demonstrated the highest thermal neutron detection efficiency among solid-state neutron detectors to date at about 53%. In this work, photoconductive-like vertical detectors with a detection area of 1 × 1 mm2 were fabricated from 50 μm thick free-standing h-BN epilayers using Ni/Au and Ti/Al bilayers as ohmic contacts. Leakage currents, mobility-lifetime (μτ) products under UV photoexcitation, and neutron detection efficiencies have been measured for a total of 16 different device configurations. The results have unambiguously identified that detectors incorporating the Ni/Au bilayer on both surfaces as ohmic contacts and using the negatively biased top surface for neutron irradiation are the most desired device configurations. It was noted that high growth temperatures of h-10BN epilayers on sapphire substrates tend to yield a higher concentration of oxygen impurities near the bottom surface, leading to a better device performance by the chosen top surface for irradiation than by the bottom. Preferential scattering of oxygen donors tends to reduce the mobility of holes more than that of electrons, making the biasing scheme with the ability of rapidly extracting holes at the irradiated surface while leaving the electrons to travel a large average distance inside the detector at a preferred choice. When measured against a calibrated 6LiF filled micro-structured semiconductor neutron detector, it was shown that the optimized configuration has pushed the detection efficiency of h-BN neutron detectors to 58%. These detailed studies also provided a better understanding of growth-mediated impurities in h-BN epilayers and their effects on the charge collection and neutron detection efficiencies.

  13. Triggering the atomic layers control of hexagonal boron nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yangxi [State Key Laboratory of Advanced Ceramic Fibers and Composites, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Zhang, Changrui, E-mail: crzhang12@gmail.com [State Key Laboratory of Advanced Ceramic Fibers and Composites, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Li, Bin [State Key Laboratory of Advanced Ceramic Fibers and Composites, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Jiang, Da; Ding, Guqiao; Wang, Haomin [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China); Xie, Xiaoming, E-mail: xmxie@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China)

    2014-09-15

    Highlights: • Thickness of h-BN films can be controlled from double atomic layers to over ten atomic layers by adjusting the CVD parameters, quite different from the reported thickness control of up to tens of nanometers. (The interlayer distance of h-BN is 0.333 nm.) • Growth mechanisms of h-BN are discussed, especially for bilayer h-BN films. • Both epitaxial growth and diffusion-segregation process are involved in the synthesis of bilayer h-BN films. - Abstract: In this work, we report the successful synthesis of large scale hexagonal boron nitride films with controllable atomic layers. The films are grown on thin nickel foils via ambient pressure chemical vapor deposition with borazine as the precursor. The atomic layers of h-BN films can be controlled in a narrow range by adjusting growth time and the cooling rates. Transmission electron microscope results shows the h-BN films exhibit high uniformity and good crystalline. X-ray photoelectron spectroscopy shows the B/N elemental ratio is about 1.01. The h-BN films exhibit a pronounced deep ultraviolet absorption at 203.0 nm with a large optical band gap of 6.02 ± 0.03 eV. The results suggest potential applications of h-BN films in deep ultraviolet and dielectric materials. Growth mechanisms of h-BN films with thickness control are discussed, especially when the synthesized h-BN films after a higher cooling rate show an in-plane rotation angle between bilayers. Both epitaxial growth and diffusion-segregation process are involved in the synthesis of bilayer h-BN films.

  14. Magnetic vortex dynamics on a picosecond timescale in a hexagonal permalloy pattern

    Energy Technology Data Exchange (ETDEWEB)

    Shim, J.-H.; Kim, D.-H.; Mesler, B.; Moon, J.-H.; Lee, K.-J.; Anderson, E. H.; Fischer, P.

    2009-12-02

    We have observed a motion of magnetic vortex core in a hexagonal Permalloy pattern by means of Soft X-ray microscopy. Pump-probe stroboscopic observation on a picosecond timescale has been carried out after exciting a ground state vortex structure by an external field pulse of 1 ns duration. Vortex core is excited off from the center position of the hexagonal pattern but the analysis of the core trajectory reveals that the motion is nongyrotropic.

  15. Electronic properties of Mn-decorated silicene on hexagonal boron nitride

    KAUST Repository

    Kaloni, Thaneshwor P.

    2013-12-17

    We study silicene on hexagonal boron nitride, using first-principles calculations. Since hexagonal boron nitride is semiconducting, the interaction with silicene is weaker than for metallic substrates. It therefore is possible to open a 50 meV band gap in the silicene. We further address the effect of Mn decoration by determining the onsite Hubbard interaction parameter, which turns out to differ significantly for decoration at the top and hollow sites. The induced magnetism in the system is analyzed in detail.

  16. Magnetic properties of the Ising system on alternate layers of a hexagonal lattice

    Science.gov (United States)

    Masrour, R.; Jabar, A.; Benyoussef, A.; Hamedoun, M.

    2018-02-01

    The magnetic properties of the mixed spin-1 and spin-5/2 Ising ferrimagnetic model on a hexagonal lattice have been studied using the Monte Carlo simulations. The hexagonal lattice study is formed by alternate layers of spins σ = 1 and S = 5 / 2. The thermal variations of the magnetizations are given. The magnetic hysteresis cycles are established for different values of exchange interactions, crystal-field and temperatures. The magnetic coercive field is deduced.

  17. The hexagonal lattice marks in the muroids rodent explain molar-cusp enamel line

    OpenAIRE

    Ruiz Bustos, A.

    2011-01-01

    The crown enamel line of muroids rodent has geometric traces that coincide exactly with an equilateral triangular lattice. This finding helps to explain the muroids dental pattern from a novel perspective in molar morphology that it is based on hexagonal structures. The adult traces imply that the morphology of the teeth mammals is consequence of a morphogenetic process. This is the study of the hexagonal lattice marks observed in the enamel line, and therefore called odontohexasymmetry. ...

  18. Group Dynamics as a Critical Component of Successful Space Exploration: Conceptual Theory and Insights from the Biosphere 2 Closure Experiment

    Science.gov (United States)

    Nelson, Mark; Allen, John P.

    As space exploration and eventually habitation achieves longer durations, successfully managing group dynamics of small, physically isolated groups will become vital. The paper summarizes important underlying research and conceptual theory and how these manifested in a well-documented example: the closure experiments of Biosphere 2. Key research breakthroughs in discerning the operation of small human groups comes from the pioneering work of W.R. Bion. He discovered two competing modalities of behavior. The first is the “task-oriented” or work group governed by shared acceptance of goals, reality-thinking in relation to time, resources and rational, and intelligent management of challenges presented. The opposing, usually unconscious, modality is what Bion called the “basic-assumption” group and alternates between three “group animal” groups: dependency/kill the leader; fight/flight and pairing. If not dealt with, these dynamics work to undermine and defeat the conscious task group’s goal achievement. The paper discusses crew training and selection, various approaches to structuring the work and hierarchy of the group, the importance of contact with a larger population through electronic communication and dealing with the “us-them” syndrome frequently observed between crew and Mission Control. The experience of the first two year closure of Biosphere 2 is drawn on in new ways to illustrate vicissitudes and management of group dynamics especially as both the inside team of biospherians and key members of Mission Control had training in working with group dynamics. Insights from that experience may help mission planning so that future groups in space cope successfully with inherent group dynamics challenges that arise.

  19. Extending the benefits of early mobility to critically ill patients undergoing continuous renal replacement therapy: the Michigan experience.

    Science.gov (United States)

    Talley, Cheryl L; Wonnacott, Robert O; Schuette, Janice K; Jamieson, Jill; Heung, Michael

    2013-01-01

    Evidence to support improved outcomes with early ambulation is strong in medical literature. Yet, critically ill continuous renal replacement therapy (CRRT) patients remain tethered to their beds by devices delivering supportive therapy. The University of Michigan Adult CRRT Committee identified this deficiency and sought to change it. There was no guidance in the literature to support mobilizing this population; therefore, we reviewed literature from devices with similar technological profiles. Revision of our institutional mobility protocol for the CRRT population included a simple safety acronym, ASK. The acronym addresses appropriate candidacy; secured, appropriate access; and potential device and patient complications as a memorable aid to help nursing staff determine whether their CRRT patients are candidates for early mobility. After implementing our CRRT mobility standard, a preliminary study of 109 CRRT patients and a review of incident reports related to CRRT demonstrated no significant adverse patient events or falls and no access complications related to mobility. This deliberate intervention allows CRRT patients to safely engage in mobility activities to improve this population's outcomes. A simple mobility protocol and safety acronym partnered with strong clinical leadership has permitted the University of Michigan to add CRRT patients to the body of early mobility literature.

  20. Hexagonal ZnO nanorods assembled flowers for photocatalytic dye degradation: Growth, structural and optical properties

    Science.gov (United States)

    Rahman, Qazi Inamur; Ahmad, Musheer; Misra, Sunil Kumar; Lohani, Minaxi B.

    2013-12-01

    A facile hydrothermal method was used to synthesize highly crystalline hexagonal ZnO nanorods assembled flowers by the reaction of zinc acetate and hexamethylenetetraamine (HMTA) at 105 °C. The morphological characterizations revealed that well defined ZnO nanorods were assembled into flowers morphology. X-rays diffraction patterns showed the highly crystalline nature of ZnO with hexagonal wurtzite structure. The structural and optical properties of hexagonal ZnO nanorods assembled flowers were measured by Fourier transform infra-red (FT-IR) and ultraviolet-visible (UV-Vis) measurements. The as-synthesized hexagonal ZnO nanorods assembled flowers were applied as an efficient photocatalyst for the photodegradation of organic dyes under UV-light irradiation. The methylene blue (MB) and rhodamine B (RhB) over the surface of hexagonal ZnO nanorods assembled flowers considerably degraded by ∼91% and ∼80% within 140 min respectively. The degradation rate constants were found to be kapp (0.01313 mint-1) and kapp(0.0104 mint-1) for MB and RhB dye respectively. The enhanced dye degradation might be attributed to the efficient charge separation and the large number of oxyradicals generation on the surface of the hexagonal ZnO nanorods assembled flowers.

  1. Anomalous lattice compressibility of hexagonal Eu{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Irshad, K.A.; Chandra Shekar, N.V., E-mail: chandru@igcar.gov.in

    2017-07-01

    Monoclinic Eu{sub 2}O{sub 3} was investigated in a Mao-Bell type diamond anvil cell using angle dispersive x-ray diffraction up to a pressure of 26 GPa. Pressure induced structural phase transition from monoclinic to hexagonal phase was observed at 4.3 GPa with 2% volume collapse. Birch –Murnaghan equation of state fit to the pressure volume data yielded a bulk modulus of 159(9) GPa and 165(6) GPa for the monoclinic and hexagonal phases respectively. Equation of state fitting to the structural parameters yielded an axial compressibility of β{sub a} > β{sub c} > β{sub b} for the parent monoclinic phase, showing the least compressibility along b axis. Contrary to the available reports, an anomalous lattice compressibility behavior is observed for the high pressure hexagonal phase, characterized by pronounced hardening of a axis above 15 GPa. The observed incompressible nature of the hexagonal a axis in the pressure range 15–25 GPa is found to be compensated by doubling the compressibility along the c axis. - Highlights: • Structural phase transition in Eu{sub 2}O{sub 3} from monoclinic to hexagonal phase. • Anomalous lattice compressibility in the hexagonal phase has reported first time. • Quantitative analysis of lattice compressibility.

  2. Next generation of elevated [CO2] experiments with crops: a critical investment for feeding the future world.

    Science.gov (United States)

    Ainsworth, Elizabeth A; Beier, Claus; Calfapietra, Carlo; Ceulemans, Reinhart; Durand-Tardif, Mylene; Farquhar, Graham D; Godbold, Douglas L; Hendrey, George R; Hickler, Thomas; Kaduk, Jörg; Karnosky, David F; Kimball, Bruce A; Körner, Christian; Koornneef, Maarten; Lafarge, Tanguy; Leakey, Andrew D B; Lewin, Keith F; Long, Stephen P; Manderscheid, Remy; McNeil, David L; Mies, Timothy A; Miglietta, Franco; Morgan, Jack A; Nagy, John; Norby, Richard J; Norton, Robert M; Percy, Kevin E; Rogers, Alistair; Soussana, Jean-Francois; Stitt, Mark; Weigel, Hans-Joachim; White, Jeffrey W

    2008-09-01

    A rising global population and demand for protein-rich diets are increasing pressure to maximize agricultural productivity. Rising atmospheric [CO(2)] is altering global temperature and precipitation patterns, which challenges agricultural productivity. While rising [CO(2)] provides a unique opportunity to increase the productivity of C(3) crops, average yield stimulation observed to date is well below potential gains. Thus, there is room for improving productivity. However, only a fraction of available germplasm of crops has been tested for CO(2) responsiveness. Yield is a complex phenotypic trait determined by the interactions of a genotype with the environment. Selection of promising genotypes and characterization of response mechanisms will only be effective if crop improvement and systems biology approaches are closely linked to production environments, that is, on the farm within major growing regions. Free air CO(2) enrichment (FACE) experiments can provide the platform upon which to conduct genetic screening and elucidate the inheritance and mechanisms that underlie genotypic differences in productivity under elevated [CO(2)]. We propose a new generation of large-scale, low-cost per unit area FACE experiments to identify the most CO(2)-responsive genotypes and provide starting lines for future breeding programmes. This is necessary if we are to realize the potential for yield gains in the future.

  3. Setting ozone critical levels for annual Mediterranean pasture species: Combined analysis of open-top chamber experiments.

    Science.gov (United States)

    Sanz, J; González-Fernández, I; Elvira, S; Muntifering, R; Alonso, R; Bermejo-Bermejo, V

    2016-11-15

    Annual Dehesa-type pastures comprise semi-natural vegetation communities dominated by annual species characteristic of the Mediterranean basin areas of Southern Europe. This study analyses all the datasets available on the effects of ozone (O3) on annual pasture species in order to review and propose new exposure- and flux-based O3 critical levels (CLes) following the methodology of the Convention on Long-Range Transboundary Air Pollution (CLRTAP). Based on the potential effect on pastures main ecosystem services, the availability of data and the statistical significance of the regressions, three variables have been selected for establishing CLes: total above-ground biomass, consumable food value (CFV), as a nutritional quality index, and reproductive capacity based on flower and seed production. New CLes proposed for a 10% loss (with 95% confidence intervals between brackets) of above-ground biomass and reproductive capacity were, respectively, AOT40=3.1 (2.6, 3.8) and 2.0 (1.5, 2.8) ppmh and POD1=12.2 (8.9, 15.5) and 7.2 (1.1, 13.3) mmolm(-2). The provisional AOT40- and POD1-based CLes for CFV were 2.3 (1.6, 4.0) ppmh and 4.6 (2.7, 6.5) mmolm(-2) respectively. By using only O3-sensitive species for the exposure and dose-response functions, the proposed CLes should be used for risk assessments. Their use for quantifying O3 damage may lead to an overestimation of the effects. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Graphdiyne nanoribbons with open hexagonal rings: Existence of topological unprotected edge states

    Science.gov (United States)

    Chen, Cong; Li, Jin; Sheng, Xian-Lei

    2017-10-01

    Using first principles calculations, we studied a new class of graphdiyne nanoribbons (GDYNR) with open hexagonal rings on the edges. To avoid the effects from dangling bond, hydrogen or oxygen atoms were absorbed on the edges. There are two kinds of GDYNR depending on the edge structures, armchair and zigzag. The electronic structures show that all of them are semiconductors. The band gap can be tuned by the width of GDYNR. As the width of nanoribbons increases, the energy gap decreases firstly and then increases, and reaches a minimum gap for both kinds. To understand the intriguing phenomenon, we constructed a tight-binding model for GDYNR and found that the existence of the minimum of the energy gap is due to the competition between the interaction within the two edges and the coupling in between. Furthermore, topological unprotected edge states are found in the band structure of a semi-infinite system by calculating surface Green's function. If GDYNR could be synthesized in experiments, it would be useful for the nanodevices in the future.

  5. Influence of point defects on the near edge structure of hexagonal boron nitride

    Science.gov (United States)

    McDougall, Nicholas L.; Partridge, Jim G.; Nicholls, Rebecca J.; Russo, Salvy P.; McCulloch, Dougal G.

    2017-10-01

    Hexagonal boron nitride (hBN) is a wide-band-gap semiconductor with applications including gate insulation layers in graphene transistors, far-ultraviolet light emitting devices and as hydrogen storage media. Due to its complex microstructure, defects in hBN are challenging to identify. Here, we combine x-ray absorption near edge structure (XANES) spectroscopy with ab initio theoretical modeling to identify energetically favorable defects. Following annealing of hBN samples in vacuum and oxygen, the B and N K edges exhibited angular-dependent peak modifications consistent with in-plane defects. Theoretical calculations showed that the energetically favorable defects all produce signature features in XANES. Comparing these calculations with experiments, the principle defects were attributed to substitutional oxygen at the nitrogen site, substitutional carbon at the boron site, and hydrogen passivated boron vacancies. Hydrogen passivation of defects was found to significantly affect the formation energies, electronic states, and XANES. In the B K edge, multiple peaks above the major 1 s to π* peak occur as a result of these defects and the hydrogen passivated boron vacancy produces the frequently observed doublet in the 1 s to σ* transition. While the N K edge is less sensitive to defects, features attributable to substitutional C at the B site were observed. This defect was also calculated to have mid-gap states in its band structure that may be responsible for the 4.1-eV ultraviolet emission frequently observed from this material.

  6. Role of defects in the adsorption of small molecules on single-layer hexagonal boron nitride

    Science.gov (United States)

    Jiang, Tao; Rawal, Takat B.; Le, Duy; Rahman, Talat S.

    In this work, we have investigated the adsorption of small molecules (CO, CO2, H2) on single-layer hexagonal boron nitride (h-BN) with point defects employing ab initio density functional theory (DFT) with incorporation of non-local van der Waals functional. We find that N vacancy (VN) and N substituted by B (BN) facilitate the adsorption of CO and CO2 molecules on h-BN. CO molecularly chemisorbs on h-BN with these defects with adsorption energy of -1.01 eV and -2.56 eV, whereas CO2 molecularly chemisorbs with adsorption energy of -1.66 eV and -0.094 eV. In contrast H2 does not chemisorb on these defects. We will analyze the geometric and electronic structure of these systems to establish the rationale for the differences in behavior for these adsorbates. We will also present results of the phonon dispersion of the systems, and discuss the vibrational modes of those adsorbed molecules. These results provide atomistic understanding of the physical processes involved in, occurring at the reaction sites, the conversion of synthetic gases into higher alcohols as observed in recent experiments. Work supported in part by NSF Grant CHE-1465105.

  7. Experiences in Conducting Participatory Communication Research for HIV Prevention Globally: Translating Critical Dialog into Action through Action Media.

    Science.gov (United States)

    Parker, Warren Martin; Becker-Benton, Antje

    2016-01-01

    developed through expert-led didactic approaches that, at best, engage audiences at the end of the development cycle through pretesting of communication concepts. Action Media provides an alternative approach that can be utilized to inform communication by integrating community perspectives at the outset. Notwithstanding the focused engagement with small group representative of health-vulnerable subpopulations, Action Media findings have informed large-scale communication interventions. The approach is directly linked to enabling ownership, critical thinking, and mobilization of knowledge for change.

  8. Torn between dual roles: the experiences of nurse-family members when a loved one is hospitalised in a critical condition.

    Science.gov (United States)

    Giles, Tracey M; Williamson, Victoria

    2015-11-01

    To understand and interpret the experiences of nurse-family members when a family member or loved one is hospitalised in a critical condition. Having a family member hospitalised with a critical illness is a traumatic stressor, often with long-term sequelae. Providing holistic care for family members who are also nurses makes the provision of care more complex because of their professional expertise; yet few studies have explored this issue. In this descriptive study, qualitative data were collected using a questionnaire and analysed using van Manen's (Researching Lived Experience: Human Science for an Action Sensitive Pedagogy, 1990, State University of New York Press, London, ON) six-step approach. Twenty nurse-family members completed an online questionnaire in June 2013. Qualitative findings from 19 participants were included in the analysis. The phenomenological analysis approach described by van Manen (Researching Lived Experience: Human Science for an Action Sensitive Pedagogy, 1990, State University of New York Press, London, ON) was used to describe and interpret nurse-family member experiences. Nurse-family members experience significant dual role conflicts between their personal and professional personas due to their specialised knowledge, need for watchfulness and competing expectations. Our findings describe how dual role conflicts developed and were managed, and reveal the resultant emotional toll and psychological distress as nurse-family members struggled to resolve these conflicts. Nurse-family members require a different type of care than general public family members, yet their unique needs are often unmet, leading to increased anxiety and distress that could potentially be minimised. An increased awareness and emphasis on the nurse-family member experience can ensure health care professionals are better placed to provide appropriate and targeted care to minimise distressing dual role conflicts. There is a need for targeted and specialised

  9. CriticalEd

    DEFF Research Database (Denmark)

    Kjellberg, Caspar Mølholt; Meredith, David

    2014-01-01

    The best text method is commonly applied among music scholars engaged in producing critical editions. In this method, a comment list is compiled, consisting of variant readings and editorial emendations. This list is maintained by inserting the comments into a document as the changes are made...... such as Sibelius or Finale. It was hypothesized that it would be possible to develop a Sibelius plug-in, written in Manuscript 6, that would improve the critical editing work flow, but it was found that the capabilities of this scripting language were insufficient. Instead, a 3-part system was designed and built...

  10. User perception and experience of the introduction of a novel critical care patient viewer in the ICU setting.

    Science.gov (United States)

    Dziadzko, Mikhail A; Herasevich, Vitaly; Sen, Ayan; Pickering, Brian W; Knight, Ann-Marie A; Moreno Franco, Pablo

    2016-04-01

    Failure to rapidly identify high-value information due to inappropriate output may alter user acceptance and satisfaction. The information needs for different intensive care unit (ICU) providers are not the same. This can obstruct successful implementation of electronic medical record (EMR) systems. We evaluated the implementation experience and satisfaction of providers using a novel EMR interface-based on the information needs of ICU providers-in the context of an existing EMR system. This before-after study was performed in the ICU setting at two tertiary care hospitals from October 2013 through November 2014. Surveys were delivered to ICU providers before and after implementation of the novel EMR interface. Overall satisfaction and acceptance was reported for both interfaces. A total of 246 before (existing EMR) and 115 after (existing EMR+novel EMR interface) surveys were analyzed. 14% of respondents were prescribers and 86% were non-prescribers. Non-prescribers were more satisfied with the existing EMR, whereas prescribers were more satisfied with the novel EMR interface. Both groups reported easier data gathering, routine tasks & rounding, and fostering of team work with the novel EMR interface. This interface was the primary tool for 18% of respondents after implementation and 73% of respondents intended to use it further. Non-prescribers reported an intention to use this novel interface as their primary tool for information gathering. Compliance and acceptance of new system is not related to previous duration of work in ICU, but ameliorates with the length of EMR interface usage. Task-specific and role-specific considerations are necessary for design and successful implementation of a EMR interface. The difference in user workflows causes disparity of the way of EMR data usage. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  11. Both movement-end and task-end are critical for error feedback in visuomotor adaptation: a behavioral experiment.

    Directory of Open Access Journals (Sweden)

    Takumi Ishikawa

    Full Text Available An important issue in motor learning/adaptation research is how the brain accepts the error information necessary for maintaining and improving task performance in a changing environment. The present study focuses on the effect of timing of error feedback. Previous research has demonstrated that adaptation to displacement of the visual field by prisms in a manual reaching task is significantly slowed by delayed visual feedback of the endpoint, suggesting that error feedback is most effective when given at the end of a movement. To further elucidate the brain mechanism by which error information is accepted in visuomotor adaptation, we tested whether error acceptance is linked to the end of a given task or to the end of an executed movement. We conducted a behavioral experiment using a virtual shooting task in which subjects controlled their wrist movements to meet a target with a cursor as accurately as possible. We manipulated the timing of visual feedback of the impact position so that it occurred either ahead of or behind the true time of impact. In another condition, the impact timing was explicitly indicated by an additional cue. The magnitude of the aftereffect significantly varied depending on the timing of feedback (p < 0.05, Friedman's Test. Interestingly, two distinct peaks of aftereffect were observed around movement-end and around task-end, irrespective of the existence of the timing cue. However, the peak around task-end was sharper when the timing cue was given. Our results demonstrate that the brain efficiently accepts error information at both movement-end and task-end, suggesting that two different learning mechanisms may underlie visuomotor transformation.

  12. Rural posting experience, requests for transfer, and perspectives about critical factors for staff retention among primary health care workers in urban Kano, Nigeria.

    Science.gov (United States)

    Lawan, U M; Amole, G T; Khayi, J H

    2017-01-01

    Inadequate skilled manpower at rural posts is a serious impediment toward equitable and universal access to healthcare in Nigeria. To examine the experiences of primary health care (PHC) workers on rural assignments, requests for transfer, and perspectives about critical factors for retention of healthcare workers at rural posts. Using descriptive cross-sectional design, 262 PHC workers in Kano were studied. Data were collected using semi-structured questionnaires and analyzed on Statistical Package for Social Sciences version 22. Pearson's Chi-square and Fisher's exact tests were used to test for significant association between categorical variables. P ≤ 0.05 was considered significant. The mean age of the workers was 36.0 ± 9 years. Majority were females (55.4%) and married (64.2%) with mean working experience of 13.0 ± 8.0 years. Only 29 (11.2%) had rural posting experience. Mean duration of posting was 4.0 ± 2.0 years; 19 (65.5%) sought re-deployment for lack of social amenities and good schools for children 19 (100.0%) and poor work environment 17 (89.5%). Common positive rural experiences mentioned were less work pressure 26 (89.7%), cordial relationship with colleagues and community members 24 (82.8%), and willingness of the community to partake in health activities 24 (82.8%). Common negative experiences reported include lack of social amenities 27 (93.1), lack of equipment and supplies in facilities 26 (89.7%), and stagnation 22 (75.9%). The workers' perspectives about critical factors for retention at rural posts include good facility infrastructure and functional equipment 240 (92.3%), good housing 237 (91.2%), potable water and electricity supply 238 (91.5%), good schools for staff's children 38 (91.5%), and good access of road to town 239 (91.9%). While steering gear at upgrading basic infrastructures in rural areas, government should in the interim, ensure attractive working and living conditions at rural posts.

  13. Implementing the CASPiE course-based research experience at the United States Military Academy: Affective responses and effects on critical thinking

    Science.gov (United States)

    Chase, Anthony Michael

    The Center for Authentic Science Practices in Education (CASPiE) pioneered a course-based research experience approach to teaching chemistry laboratory courses. The method had previously been studied in a variety of institutional settings. Recently, the United States Military Academy at West Point decided to develop CASPiE-style modules for the introductory honors chemistry course. This research setting presents clean experimental-control comparisons and a group of faculty who were completely new to the method. Equipping students with authentic research experiences early in their education is important regardless of the institution. However, cadets at a military academy must make decisions relatively early (the outset of their second year) as to what their career trajectory will be as eventual officers. In the new CASPiE-based experience, cadets are given the opportunity to select from one of three different modules (analytical chemistry, toxicology, and chemical engineering) in which to participate during the course. These three modules represent subsections of an overall Army waste-to-energy research project. Cadets generate unique hypotheses, real data, and research posters towards the advancement of the project. Posters are then presented in a session. that includes an audience of project stakeholders, course instructors, and other academy faculty and staff. Here, I will present my research methods, evaluative procedures, and findings in the affective domain, critical thinking, and laboratory content comprehension.

  14. Regioselectivity of Sc2C2@C3v(8)-C82: Role of the Sumanene-Type Hexagon in Diels-Alder Reaction.

    Science.gov (United States)

    Zhao, Pei; Zhao, Xiang; Ehara, Masahiro

    2016-09-16

    Recently, several experiments have demonstrated high chemical reactivity of the sumanene-type hexagon in Sc2C2@C82. To further uncover its reactivity, the Diels-Alder reaction to all the nonequivalent C-C bonds of C82 and Sc2C2@C82 has been investigated by density functional theory calculations. For the free fullerene, the [5,6] bond 7 is the thermodynamically most favored, whereas the addition on the [6,6] bond 3 has the lowest activation energy. Diels-Alder reaction has no preference for addition sites in the sumanene-type hexagon. However, in the case of the endohedral fullerene, the [6,6] bond 19 in the special hexagon becomes the most reactive site according to both kinetic and thermodynamic considerations. Further analyses reveal that bond 19 in Sc2C2@C82 exhibits the shortest bond length and third largest π-orbital axis vector. In addition, the LUMOs of bond 19 are also symmetry-allowed to interact with butadiene.

  15. The role of biopsies and autopsies in the diagnosis of cognitive impairment, with emphasis on small vessel diseases: A critical appraisal enriched by personal experience

    Directory of Open Access Journals (Sweden)

    Leila Chimelli

    Full Text Available ABSTRACT. Acquired and hereditary microangiopathies cause cerebral small vessel diseases (CSVD that impair cognition. The most frequent is primary angiitis of the CNS (PACNS, whose diagnosis remains challenging, requiring a multidisciplinary approach. Secondary vasculitis, CADASIL, miscellaneous microangiopathies and lymphomas, also cause cognitive impairment. Despite the fact that the need for biopsy has decreased in the era of new neuroimaging methods, biopsies that include small leptomeningeal and parenchymal arterial vessels still remain the gold standard to diagnose PACNS and other CSVD, and to exclude mimics such as infections and malignancies. New approaches for pathological consequences relevant to vascular cognitive impairment such as silent brain lesions, microinfarcts, microbleeds and subtle loss of microstructural integrity, may be detected in autopsies. This article addresses the role of biopsies and autopsies for the diagnosis of cognitive impairment related to small vessel diseases or other inflammatory/ischemic processes, and presents a critical appraisal based on personal experience.

  16. Critical factors for the replication of mumps virus in primary chicken embryo fibroblasts defined by the use of design of experiments (DoE).

    Science.gov (United States)

    Markusic, Maja; Pavlović, Nediljko; Santak, Maja; Marić, Gorana; Kotarski, Ljerka; Forcic, Dubravko

    2013-02-01

    Live attenuated vaccines against mumps virus (MuV) have been traditionally produced by passaging the virus in the embryonated chicken eggs or primary chicken embryo fibroblasts (CEFs). Virus propagation on these cell substrates enables successful virus attenuation and retains it sufficiently antigenic to induce lasting protective immunity in humans. The aim of this study was to identify critical factors for MuV replication in primary CEFs grown on a small-scale level in order to explore possibilities for improvements in the virus replication and yield. The effect of differently prepared cells, culturing conditions, and infection conditions on virus yield was estimated by employing statistical design of experiments (DoE) methodology. Our results show that the preparation of primary CEFs and the way of their infection substantially impact virus yield and are critical for efficient MuV replication. These process parameters should be considered in further process optimization. We also demonstrate the applicability of DoE in optimization of virus replication as a crucial step in obtaining high virus yields.

  17. Zone-Center Raman Active Modes In Cubic And Hexagonal Diamond

    Science.gov (United States)

    Mehl, Michael J.; Pickard, Warren E.

    1989-07-01

    The recent interest in the growth of thin diamond films has led us to consider the differences between the hexagonal (lonsdaleite) and cubic structures. Both phases have very similar properties, and empirical and theoretical considerations indicate that their structural energies are nearly identical. When thin films are grown the hexagonal phase may compete with the cubic phase, making characterization of the film difficult. Cubic diamond has one Raman active mode, while hexagonal diamond has three. The opportunity thus exists for Raman spectroscopy to differentiate between the two tetrahedrally bonded phases (as well as "amorphous" or graphitic phases). Electronic structure calculations can be used to obtain theoretical Q=0 frequencies of the Raman active modes in both structures. We have used the first principles Linearized Augmented Plane Wave method within the local density approximation to calculate the zone center phonon frequencies. The calculated frequency of the cubic diamond Raman mode is 1336 cm-1, very close to the experimental value of 1333 cm-1. Our calculations indicate that the hexagonal structure A t has a zone-center frequency of 1269 cm-1, the Elg mode is at 1215 cm-1, and the E1g mode is at 430 cm-1. Anharmonic corrections are rather large (2-3%) in the cubic diamond Raman mode and in the hexagonal Al mode, but are not important in the E2g and Elg modes. We will compare our results with the available experimental information.

  18. Comparative Raman studies of cubic and hexagonal GaN epitaxial layers

    Science.gov (United States)

    Tabata, A.; Enderlein, R.; Leite, J. R.; da Silva, S. W.; Galzerani, J. C.; Schikora, D.; Kloidt, M.; Lischka, K.

    1996-04-01

    Hexagonal and cubic GaN layers are grown on (001) GaAs substrates by means of molecular beam epitaxy. First order Raman spectra are taken from these layers at various incident laser wavelengths and temperatures. The T2 transverse-optical (TO) and longitudinal-optical (LO) frequencies of cubic GaN are determined, as well as the A1 TO and LO, E1 TO, and E2 frequencies of hexagonal GaN. The T2 TO frequency of cubic GaN lies between the A1 and E1 TO frequencies of hexagonal GaN as one expects comparing the lattice dynamics of zincblende and wurtzite type crystals. The T2 TO frequency is close to the calculated value but disagrees with a recently reported experimental value. For the hexagonal layer, all frequencies are close to those previously measured. A broad Raman structure below the A1 LO peak is interpreted in terms of a disturbed long range order of the hexagonal layer.

  19. Test-retest reliability and minimal detectable change of the hexagon agility test.

    Science.gov (United States)

    Beekhuizen, Kristina S; Davis, Maurice D; Kolber, Morey J; Cheng, Ming-Shun S

    2009-10-01

    The purpose of this study was to examine the test-retest reliability and minimal detectable change (MDC95) of the hexagon test. The hexagon test is a routinely used measure of agility in the sports and rehabilitation professions, yet its reliability has not been investigated in prior research. A total of 26 college-aged men (n = 17) and women (n = 9) of various activity levels were recruited to participate in 3 testing sessions: baseline, 1 hour after baseline, and 48 hours after baseline. The results of this study indicated excellent test-retest reliability for both same-day intraclass correlation coefficient (ICC) model 3,1 = 0.938 and between-day ICC (3,1) = 0.924 analyses. The MDC95 for the hexagon test was 1.015 seconds. A significant difference in the mean times was identified during the same-day test-retest sessions (p learning effect. The hexagon test shows excellent reliability for measuring agility, which supports its use as a tool to assess athletic performance and lower-extremity agility. Evidence of reliability, in addition to its ease of administration, makes the hexagon test a practical and effective method to measure agility. When using this test as a measure of agility, a change of greater than 1.015 seconds is necessary to be 95% certain that the change in time reflects improvement and exceeds measurement error. A practice trial is recommended prior to recording scores to attenuate the possibility of a learning effect.

  20. Disabled women's experiences of accessing and utilising maternity services when they are affected by domestic abuse: a critical incident technique study.

    Science.gov (United States)

    Bradbury-Jones, Caroline; Breckenridge, Jenna P; Devaney, John; Kroll, Thilo; Lazenbatt, Anne; Taylor, Julie

    2015-08-20

    Women and their babies are entitled to equal access to high quality maternity care. However, when women fit into two or more categories of vulnerability they can face multiple, compound barriers to accessing and utilising services. Disabled women are up to three times more likely to experience domestic abuse than non-disabled women. Domestic abuse may compromise health service access and utilisation and disabled people in general have suboptimal access to healthcare services. Despite this, little is known about the compounding effects of disability and domestic abuse on women's access to maternity care. The aim of the study was to identify how women approach maternity care services, their expectations of services and whether they are able to get the type of care that they need and want. We conducted a qualitative, Critical Incident Technique study in Scotland. Theoretically we drew on Andersen's model of healthcare use. The model was congruent with our interest in women's intended/actual use of maternity services and the facilitators and barriers impacting their access to care. Data were generated during 2013 using one-to-one interviews. Five women took part and collectively reported 45 critical incidents relating to accessing and utilising maternity services. Mapped to the underpinning theoretical framework, our findings show how the four domains of attitudes; knowledge; social norms; and perceived control are important factors shaping maternity care experiences. Positive staff attitude and empowering women to have control over their own care is crucial in influencing women's access to and utilisation of maternity healthcare services. Moreover these are cyclical, with the consequences and outcomes of healthcare use becoming part of the enabling or disabling factors affecting future healthcare decisions.Further consideration needs to be given to the development of strategies to access and recruit women in these circumstances. This will provide an opportunity for

  1. Growth of Atomic Hexagonal Boron Nitride Layers and Graphene/Hexagonal Boron Nitride Heterostructures by Molecular Beam Epitaxy

    Science.gov (United States)

    Xu, Zhongguang

    Graphene, as a famous Van der Waals material, has attracted intensive attention from research group and industry all over the world after 2004, while hexagonal boron nitride (h-BN), as an excellent two-dimensional (2D) dielectric layer, has been studied intensively mainly for its compatibility with graphene and other 2D materials. To realize the technological potential of 2D system, it is essential to synthesize large-area, high-quality 2D thin films through a scalable and controllable method in order to investigate novel phenomenon in fundamental physics and promising device applications. In this thesis, the growth of graphene, h-BN and their vertical and lateral heterostructures by molecular beam epitaxy (MBE) is mainly discussed. In addition, the growth mechanism, fundamental physics and possible applications are also studied. In-situ epitaxial growth of graphene/h-BN heterostructures on cobalt (Co) film substrate was achieved by using plasma-assisted MBE in Chapter 2. We demonstrated a solution for direct fabricating graphene/h-BN vertical stacking structures. Various characterizations, such as Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM), were carried out to confirm and evaluate the heterostructures. Wafer-scale heterostructures consisting of single-layer/bilayer graphene and multilayer h-BN were achieved. The mismatch angle between graphene and h-BN is below 1°. Chapter 3 studied the growth of graphene/h-BN heterostructures on Co foil substrate by plasma-assisted MBE. It is found that the coverage of h-BN layers on the epitaxial thin graphite layer is growth-time dependent. Large-area, uniform-quality h-BN film was successfully deposited on thin graphite layer. Based on the as-grown h-BN (5-6 nm)/G (26-27 nm) heterostructure, without using any transferring process, we fabricated capacitor devices with Co(foil)/G/h-BN/Co(contact) configuration to evaluate the

  2. Leader as critical thinker.

    Science.gov (United States)

    Lemire, Judith A

    2002-01-01

    A leader possess the critical-thinking knowledge and skills that provide the framework from which complex problem solving evolves. This article explores the leader as critical thinker, including a progressive plan for integrating critical-thinking concepts and associated teaching strategies into the RN to BSN and graduate curricula. To improve the critical thinking of nurses, educators must emphasize the cognitive and disposition aspects of critical thinking; promote active and sequential learning; role model critical thinking; design practical that focus on leadership and critical thinking; and conduct valid and consistent evaluations. The acquisition and application of critical thinking and problem-solving skills are progressive and refined through life-long learning and experience. This expertise begins with a sound knowledge base of the critical thinking composite and problem-solving strategies.

  3. Thermodynamics of the hexagonal close-packed iron-nitrogen system from first-principles

    DEFF Research Database (Denmark)

    Bakkedal, Morten Bjørn

    is assumed fixed.The models are developed entirely from first-principles calculations based on fundamen-tal quantum mechanical calculation through the density functional theory approach with the atomic numbers and crystal structures as the only input parameters. A complete thermody-namic description should......First-principles thermodynamic models are developed for the hexagonal close-packed ε-Fe-N system. The system can be considered as a hexagonal close-packed host lattice of iron atoms and with the nitrogen atoms residing on a sublattice formed by the octahedral interstices. The iron host lattice...... to hexagonal systems and a numerically tractable extended equation of state is developed to describe thermody-namic equilibrium properties at finite temperature.The model is applied to ε-Fe3N specifically. Through the versatility of the model, equi-librium lattice parameters, the bulk modulus, and the thermal...

  4. A planar carbon allotrope with linear bipentagon-octagon and hexagon arrangement

    Science.gov (United States)

    Zheng, Guohui; Jia, Yalei; Gao, Song; Ke, San-Huang

    2017-03-01

    A two-dimensional (2D) metallic carbon allotrope is proposed, which consists of linearly aligned bipentagon-octagon and hexagon rings in a planar sheet. The relatively high percentage of hexagon and the regular arrangement of the polygons make it energetically more favorable than most of other predicted 2D carbon allotropes. Phonon dispersions without negative frequencies also indicate its stability. Electronic structure calculations show that its metallic nature is mainly due to the atoms shared by the pentagon, hexagon and octagon. Its lattice thermal conductivity is only about one fifth of that of graphene. Armchair- and zigzag-edged nanoribbons of this structure are also studied. The former is metallic while the latter has a small band gap due to the spin-polarized edge states. The appropriate band gap and the significantly reduced thermal conductivity suggest potential applications in thermoelectricity.

  5. Fourier-transform infrared spectroscopy (FTIR) analysis of triclinic and hexagonal birnessites

    Science.gov (United States)

    Ling, Florence T.; Post, Jeffrey E.; Heaney, Peter J.; Kubicki, James D.; Santelli, Cara M.

    2017-05-01

    The characterization of birnessite structures is particularly challenging for poorly crystalline materials of biogenic origin, and a determination of the relative concentrations of triclinic and hexagonal birnessite in a mixed assemblage has typically required synchrotron-based spectroscopy and diffraction approaches. In this study, Fourier-transform infrared spectroscopy (FTIR) is demonstrated to be capable of differentiating synthetic triclinic Na-birnessite and synthetic hexagonal H-birnessite. Furthermore, IR spectral deconvolution of peaks resulting from Mnsbnd O lattice vibrations between 400 and 750 cm- 1 yield results comparable to those obtained by linear combination fitting of synchrotron X-ray absorption fine structure (EXAFS) data when applied to known mixtures of triclinic and hexagonal birnessites. Density functional theory (DFT) calculations suggest that an infrared absorbance peak at 1628 cm- 1 may be related to OH vibrations near vacancy sites. The integrated intensity of this peak may show sensitivity to vacancy concentrations in the Mn octahedral sheet for different birnessites.

  6. Precursor salt assisted syntheses of high-index faceted concave hexagon and nanorod-like polyoxometalates

    Science.gov (United States)

    Pal, Jaya; Ganguly, Mainak; Mondal, Chanchal; Negishi, Yuichi; Pal, Tarasankar

    2014-12-01

    This paper describes an effective method for a precursor salt assisted fabrication and reshaping of two different polyoxometalates [(NH4)2Cu(MoO4)2 (ACM) and Cu3(MoO4)2(OH)2 (CMOH)] into five distinctive shapes through straightforward and indirect routes. Explicit regulation of the structural arrangements of ACM and CMOH has been studied in detail with altered precursor salt concentration employing our laboratory developed modified hydrothermal (MHT) method. Morphologically different ACM 3D architectures are evolved with higher molybdate concentration, whereas 1D growth of CMOH is observed with increased copper concentration. Interesting morphological transformation of the products has been accomplished employing one precursor salt at a time without using any other foreign reagent. It has been proven that large ACMs become labile in the presence of incoming Cu(ii) and NH4+ ions of the precursor salts. A new strategy for the conversion of faceted ACMs (hexagonal plate, circular plate and hollow flower) to exclusive CMOH nanorods through a Cu(ii) assisted reaction has been adopted. According to thermodynamic consideration, the synthesis of rare concave nanostructures with high index facet is still challenging due to their higher reactivity. In this study, concave hexagonal ACM with high index facet {hkl} has been successfully prepared for the first time from hexagonal ACM through simple etching with ammonium heptamolybdate (AHM), which is another precursor salt. Hexagonal ACM corrugates to a concave hexagon because of the higher reactivity of the {001} crystal plane than that of the {010} plane. It has been shown that high index facet exposed concave hexagonal ACM serves as a better catalyst for the photodegradation of dye than the other microstructures enclosed by low index facets.This paper describes an effective method for a precursor salt assisted fabrication and reshaping of two different polyoxometalates [(NH4)2Cu(MoO4)2 (ACM) and Cu3(MoO4)2(OH)2 (CMOH)] into

  7. Effective Hamiltonian for surface states of topological insulator thin films with hexagonal warping

    Energy Technology Data Exchange (ETDEWEB)

    Siu, Zhuo Bin; Jalil, Mansoor B. A. [Computational Nanoelectronics and Nanodevices Laboratory, Electrical and Computer Engineering Department, National University of Singapore (Singapore); Tan, Seng Ghee [Data Storage Institute, Agency for Science, Technology and Research - A*STAR (Singapore)

    2016-05-15

    The effective Hamiltonian of the surface states on semi-infinite slabs of the topological insulators (TI) Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} require the addition of a cubic momentum hexagonal warping term on top of the usual Dirac fermion Hamiltonian in order to reproduce the experimentally measured constant energy contours at intermediate values of Fermi energy. In this work, we derive the effective Hamiltonian for the surface states of a Bi{sub 2}Se{sub 3} thin film incorporating the corresponding hexagonal warping terms. We then calculate the dispersion relation of the effective Hamiltonian and show that the hexagonal warping leads distorts the equal energy contours from the circular cross sections of the Dirac cones.

  8. Formation of long-lived resonances in hexagonal cavities by strong coupling of superscar modes

    Science.gov (United States)

    Song, Qinghai; Ge, Li; Wiersig, Jan; Cao, Hui

    2013-08-01

    The recent progresses in single crystalline wide bandgap hexagonal disk have stimulated intense research attention on pursuing ultraviolet (UV) laser diodes with low thresholds. While whispering-gallery modes based UV lasers have been successfully obtained in GaN, ZnO nanorods, and nanopillars, the reported thresholds are still very high, due to the low-quality (Q) factors of the hexagonal resonances. Here we demonstrate resonances whose Q factors can be more than two orders of magnitude higher than the hexagonal modes, promising the reduction of the energy consumption. The key to our finding is the avoided resonance crossing between superscar states along two sets of nearly degenerated triangle orbits, which leads to the formation of hexagram modes. The mode couplings suppress the field distributions at the corners and the deviations from triangle orbits simultaneously and therefore enhance the Q factors significantly.

  9. Hexagonally ordered nanoparticles templated using a block copolymer film through Coulombic interactions

    Science.gov (United States)

    Lee, Wonjoo; Lee, Seung Yong; Zhang, Xin; Rabin, Oded; Briber, R. M.

    2013-02-01

    We present a novel and simple method for forming hexagonal gold nanoparticle arrays that uses Coulombic interactions between negatively charged gold nanoparticles on positively charged vertically oriented poly(4-vinylpyridine) cylinders formed in a spin cast polystyrene-b-poly(4-vinylpyridine) block copolymer film. Exposure of the block copolymer film to dibromobutane vapor quaternizes and crosslinks the poly(4-vinylpyridine) domains which allows for the templated deposition of gold nanoparticles into a self-assembled hexagonal array through electrostatic interactions. These systems can form the basis for sensors or next generation nanoparticle based electronics.

  10. Substrate integrated waveguide cross-coupling filter with multilayer hexagonal cavity.

    Science.gov (United States)

    Wu, B; Xu, Z Q; Liao, J X

    2013-01-01

    Hexagonal cavities and their applications to multilayer substrate integrated waveguide (SIW) filters are presented. The hexagonal SIW cavity which can combine flexibility of rectangular one and performance of circular one is convenient for bandpass filter's design. Three types of experimental configuration with the same central frequency of 10 GHz and bandwidth of 6%, including three-order and four-order cross-coupling topologies, are constructed and fabricated based on low temperature cofired ceramic (LTCC) technology. Both theoretical and experimental results are presented.

  11. Elaboration of nickel-impregnated over hexagonal mesoporous materials and their catalytic application

    Directory of Open Access Journals (Sweden)

    M. Laribi

    2016-11-01

    Full Text Available Hexagonal mesoporous silicas with different nickel contents have been synthesized and characterized by several techniques such as N2 physical adsorption, elemental analysis, XRD, TEM and temperature programmed reduction (TPR. In fact, the nickel-impregnated over hexagonal mesoporous silicas showed both high activity and high selectivity for Friedel–Crafts alkylations of benzene with benzyl chloride. The kinetics of the reaction over these catalysts have been investigated and the reaction has been extended to other substrates like toluene, p-xylene, anisole, naphthalene and methylnaphthalene.

  12. Quasi free-standing silicene in a superlattice with hexagonal boron nitride

    KAUST Repository

    Kaloni, T. P.

    2013-11-12

    We study a superlattice of silicene and hexagonal boron nitride by first principles calculations and demonstrate that the interaction between the layers of the superlattice is very small. As a consequence, quasi free-standing silicene is realized in this superlattice. In particular, the Dirac cone of silicene is preserved. Due to the wide band gap of hexagonal boron nitride, the superlattice realizes the characteristic physical phenomena of free-standing silicene. In particular, we address by model calculations the combined effect of the intrinsic spin-orbit coupling and an external electric field, which induces a transition from a semimetal to a topological insulator and further to a band insulator.

  13. Non-linear excitation of quantum emitters in hexagonal boron nitride multiplayers

    Directory of Open Access Journals (Sweden)

    Andreas W. Schell

    2016-12-01

    Full Text Available Two-photon absorption is an important non-linear process employed for high resolution bio-imaging and non-linear optics. In this work, we realize two-photon excitation of a quantum emitter embedded in a two-dimensional (2D material. We examine defects in hexagonal boron nitride (hBN and show that the emitters exhibit similar spectral and quantum properties under one-photon and two-photon excitation. Furthermore, our findings are important to deploy two-dimensional hexagonal boron nitride for quantum non-linear photonic applications.

  14. Fabrication of Tungsten-UO 2 Hexagonal-Celled Fuel-Element Configurations

    Energy Technology Data Exchange (ETDEWEB)

    Goetsch, R.R.; Cover, P.W.; Gripshover, P.J.; Wilson, W.J.

    1964-12-04

    The gas-pressure-bonding process is being evaluated as a means of fabricating tungsten-UO 2 hexagonal-celled fuel geometries. A two-part study was initiated to optimize the fuel materials and to develp the required fixturing and loading techniques. Production of fueled tungsten-coated UO 2 particles in in progress so that geometries embodying coated particles or coated particles plus fine tungsten powder can be evaluated. Tests to data have shown the rquirement for a pretreatment in which a gaseous oxide phase is removed. Initial loading and fixturing procedures were proven satisfactory by the fabrication of a 19-cylindrical-hole hexagonal-type composite.

  15. Acoustic phonons in the hexagonal perovskite CsNiCl3 around the Gamma-point

    DEFF Research Database (Denmark)

    Visser, D.; Monteith, A.R.; Rønnow, H.M.

    2000-01-01

    The acoustic phonon dispersion curves of the hexagonal perovskite CsNiCl3 were measured at room temperature in the vicinity of the Gamma-point along the [0 0 1] and [1 1 0] directions. The derived velocity of sound values for the longitudinal and transverse acoustic phonons are compared with the ......The acoustic phonon dispersion curves of the hexagonal perovskite CsNiCl3 were measured at room temperature in the vicinity of the Gamma-point along the [0 0 1] and [1 1 0] directions. The derived velocity of sound values for the longitudinal and transverse acoustic phonons are compared...

  16. UV-light driven photocatalytic performance of hydrothermally-synthesized hexagonal CePO4 nanorods

    Science.gov (United States)

    Zhu, Zhongqi; Zhang, Ke; Zhao, Heyun; Zhu, Jing

    2017-10-01

    Hexagonal CePO4 nanorods were synthesized via a simple hydrothermal method without the presence of surfactants and then characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption and photoluminescence (PL) spectroscopy. UV-light driven photocatalytic activities of hexagonal CePO4 nanorods were detailedly demonstrated via degrading different organic dyes such as congo red (CR), organic rhodamine B (RB), methyl orange (MO) and methylene blue (MB) since these nanorods exhibit strong UV absorption with the cutoff edge of about 420 nm.

  17. APCVD hexagonal boron nitride thin films for passive near-junction thermal management of electronics

    Science.gov (United States)

    KC, Pratik; Rai, Amit; Ashton, Taylor S.; Moore, Arden L.

    2017-12-01

    The ability of graphene to serve as an ultrathin heat spreader has been previously demonstrated with impressive results. However, graphene is electrically conductive, making its use in contact with electronic devices problematic from a reliability and integration perspective. As an alternative, hexagonal boron nitride (h-BN) is a similarly structured material with large in-plane thermal conductivity but which possesses a wide band gap, thereby giving it potential to be utilized for directing contact, near-junction thermal management of electronics without shorting or the need for an insulating intermediate layer. In this work, the viability of using large area, continuous h-BN thin films as direct contact, near-junction heat spreaders for electronic devices is experimentally evaluated. Thin films of h-BN several square millimeters in size were synthesized via an atmospheric pressure chemical vapor deposition (APCVD) method that is both simple and scalable. These were subsequently transferred onto a microfabricated test device that simulated a multigate transistor while also allowing for measurements of the device temperature at various locations via precision resistance thermometry. Results showed that these large-area h-BN films with thicknesses of 77–125 nm are indeed capable of significantly lowering microdevice temperatures, with the best sample showing the presence of the h-BN thin film reduced the effective thermal resistance by 15.9% ± 4.6% compared to a bare microdevice at the same power density. Finally, finite element simulations of these experiments were utilized to estimate the thermal conductivity of the h-BN thin films and identify means by which further heat spreading performance gains could be attained.

  18. Structural alteration of hexagonal birnessite by aqueous Mn(II): Impacts on Ni(II) sorption

    Energy Technology Data Exchange (ETDEWEB)

    Lefkowitz, Joshua P.; Elzinga, Evert J.

    2017-09-01

    We studied the impacts of aqueous Mn(II) (1 mM) on the sorption of Ni(II) (200 μM) by hexagonal birnessite (0.1 g L- 1) at pH 6.5 and 7.5 with batch experiments and XRD, ATR-FTIR and Ni K-edge EXAFS analyses. In the absence of Mn(II)aq, sorbed Ni(II) was coordinated predominantly as triple corner-sharing complexes at layer vacancies at both pH values. Introduction of Mn(II)aq into Ni(II)-birnessite suspensions at pH 6.5 caused Ni(II) desorption and led to the formation of edge-sharing Ni(II) complexes. This was attributed to competitive displacement of Ni(II) from layer vacancies by either Mn(II) or by Mn(III) formed through interfacial Mn(II)-Mn(IV) comproportionation, and/or incorporation of Ni(II) into the birnessite lattice promoted by Mn(II)-catalyzed recrystallization of the sorbent. Similar to Mn(II)aq, the presence of HEPES or MES caused the formation of edge-sharing Ni(II) sorption complexes in Ni(II)-birnessite suspensions, which was attributed to partial reduction of the sorbent by the buffers. At pH 7.5, interaction with aqueous Mn(II) caused reductive transformation of birnessite into secondary feitknechtite that incorporated Ni(II), enhancing removal of Ni(II) from solution. These results demonstrate that reductive alteration of phyllomanganates may significantly affect the speciation and solubility of Ni(II) in anoxic and suboxic environments.

  19. Status of criticality safety research at NUCEF

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Ken [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    Two critical facilities, named STACY (Static Experiment Critical Facility) and TRACY (Transient Experiment Critical Facility), at the Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF) started their hot operations in 1995. Since then, basic experimental data for criticality safety research have been accumulated using STACY, and supercritical experiments for the study of criticality accident in a reprocessing plant have been performed using TRACY. In this paper, the outline of those critical facilities and the main results of TRACY experiments are presented. (author)

  20. End-of-life decisions in the Intensive Care Unit (ICU) - Exploring the experiences of ICU nurses and doctors - A critical literature review.

    Science.gov (United States)

    Flannery, Liz; Ramjan, Lucie Michelle; Peters, Kath

    2016-05-01

    End-of-life decision making in the Intensive Care Unit (ICU), can be emotionally challenging and multifaceted. Doctors and nurses are sometimes placed in a precarious position where they are required to make decisions for patients who may be unable to participate in the decision-making process. There is an increasing frequency of the need for such decisions to be made in ICU, with studies reporting that most ICU deaths are heralded by a decision to withdraw or withhold life-sustaining treatment. The purpose of this paper is to critically review the literature related to end-of-life decision making among ICU doctors and nurses and focuses on three areas: (1) Who is involved in end-of-life decisions in the ICU?; (2) What challenges are encountered by ICU doctors and nurses when making decisions?; and (3) Are these decisions a source of moral distress for ICU doctors and nurses? This review considered both qualitative and quantitative research conducted from January 2006 to March 2014 that report on the experiences of ICU doctors and nurses in end-of-life decision making. Studies with a focus on paediatrics, family/relatives perspectives, advance care directives and euthanasia were excluded. A total of 12 papers were identified for review. There were differences reported in the decision making process and collaboration between doctors and nurses (which depended on physician preference or seniority of nurses), with overall accountability assigned to the physician. Role ambiguity, communication issues, indecision on futility of treatment, and the initiation of end-of-life discussions were some of the greatest challenges. The impact of these decisions included decreased job satisfaction, emotional and psychological 'burnout'. Further research is warranted to address the need for a more comprehensive, standardised approach to support clinicians (medical and nursing) in end-of-life decision making in the ICU. Copyright © 2015 Australian College of Critical Care Nurses Ltd

  1. Synthesis of hexagonal mesoporous MgAl LDH nanoplatelets adsorbent for the effective adsorption of Brilliant Yellow.

    Science.gov (United States)

    Pourfaraj, Reza; Fatemi, Seyed Jamilaldin; Kazemi, Sayed Yahya; Biparva, Pourya

    2017-12-15

    Hexagonal mesoporous MgAl layered double hydroxide (LDH) was synthesized through a simple hydrothermal method and was employed without calcination as adsorbent in the removal of the direct anionic azo dye, Brilliant Yellow (BY). The adsorbent was characterized by XRD, FT-IR, SEM and BET surface area. Hexagonal platelets of MgAl LDH were fabricated with nanometric building blocks. Batch experiments were carried out for study effects of contact time, amount of adsorbent, solution pH and solution temperature on the removal efficiency of BY. The adsorption of BY onto the MgAl LDH was pH dependent and the highest value of adsorption capacity was observed at pH=6. The equilibrium adsorption data were obtained using the Langmuir, Freundlich and Temkin isotherms. The results indicated that the experimental adsorption data were fitted to Langmuir and Freundlich models. The maximum adsorption capacity of BY onto the MgAl LDH was found to be 115mg/g. The kinetic data of adsorption were evaluated by pseudo-first order and pseudo-second order, which described well by pseudo-second order model. The negative values of ΔG° at all temperature indicated that the adsorption process was spontaneous. The values of ΔH° and ΔS° were calculated 19.3kJ/mol and 80.5J/mol·K, respectively. The positive value of ΔH° shows that the adsorption was endothermic, while positive ΔS° value reflects increased disorder at the solid-solution interface during the adsorption. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Contributions to the qualification of the ''CRISTAL'' criticality calculi scheme: interpretation of critical experiments. Elaboration of a characterization system of neutronic configurations; Contributions a la qualification du schema de calcul de criticite ''cristal'': interpretation d'experiences critiques. Elaboration d'un systeme de caracterisation des configurations neutroniques

    Energy Technology Data Exchange (ETDEWEB)

    Gagnier, E

    1999-06-01

    This thesis work is about the validation of the new criticality-safety package CRISTAL and contributes to the modernization and the improvement of the computational tools. The first part presents neutronic elements, the objectives of safety criticality studies and the package CRISTAL. Then, the validation work concerned two series of experiments involving uranyl solutions (UO{sub 2}F{sub 2}) and UO{sub 2} powders. For these experiments, the differences between the computation results and the experimental results were analysed. It was highlighted interesting physical phenomena such of the compensations of errors between the approximate representation by the 99 energy group structure on the first resonance of oxygen and the anisotropy of the diffusion simulation as well as the influence of uranium 234 in high enriched solutions in uranium 235. Once the work of the experimental qualification carried out, raises the question of the use the base of qualification and the ''calculation-experiment'' variations which are referred to it. It is often difficult to establish the link between the ''studied configuration'' and the experiments of the base of qualification. The presented characterisation system proposes to answer in a way automatic and quantified this difficulty: - in bringing an answer on the package qualification for the studied configuration, - in giving an estimate of the package bias. To answer these points, it was defined a set of 35 characteristic neutronic parameters representing the behaviour of the medium. To process the information brought by these parameters and to use it to answer the objectives of the system, we called upon statistical methods (Principal Components Analysis and Sliced Inverse Regression). The results obtained in the feasibility studies showed the relevance of these methods for the considered objectives. (author)

  3. Quasi-hexagonal vortex-pinning lattice using anodized aluminum oxide nanotemplates

    DEFF Research Database (Denmark)

    Hallet, X.; Mátéfi-Tempfli, M.; Michotte, S.

    2009-01-01

    The bottom barrier layer of well-ordered nanoporous alumina membranes reveals a previously unexploited nanostructured template surface consisting of a triangular lattice of hemispherical nanoscale bumps. Quasi-hexagonal vortex-pinning lattice arrays are created in superconducting Nb films deposit...

  4. A highly porous three-dimensional aluminum phosphonate with hexagonal channels: synthesis, structure and adsorption properties.

    Science.gov (United States)

    Tang, Si-Fu; Cai, Jin-Jun; Li, Liang-Jun; Lv, Xiao-Xia; Wang, Chao; Zhao, Xue-Bo

    2014-04-28

    A 3D porous aluminum(III) trisphosphonate, constructed from 1D inorganic aluminum phosphate chains and tripodal organic linkers, contains large hexagonal channels (1.24 nm in diameter) and a highly accessible void (50.3%) which allow it to have a fast and relatively high uptake of H2, N2 and CO2.

  5. A transfer technique for high mobility graphene devices on commercially available hexagonal boron nitride

    NARCIS (Netherlands)

    Zomer, P. J.; Dash, S. P.; Tombros, N.; van Wees, B. J.

    2011-01-01

    We present electronic transport measurements of single and bilayer graphene on commercially available hexagonal boron nitride. We extract mobilities as high as 125 000 cm(2) V-1 s(-1) at room temperature and 275 000 cm(2) V-1 s(-1) at 4.2 K. The excellent quality is supported by the early

  6. Hexagonal wheel formation through the hydrogen-bonded assembly of cobalt Pacman complexes.

    Science.gov (United States)

    Leeland, James W; White, Fraser J; Love, Jason B

    2011-04-14

    A cobalt aquo-hydroxo complex of a ditopic Schiff-base pyrrole-crown ether macrocycle has been prepared and forms a rigid Pacman-clefted structure that assembles through hydrogen-bonding into a hexagonal wheel motif in the solid state.

  7. Achieving a multi-band metamaterial perfect absorber via a hexagonal ring dielectric resonator

    Science.gov (United States)

    Li, Li-Yang; Wang, Jun; Du, Hong-Liang; Wang, Jia-Fu; Qu, Shao-Bo

    2015-06-01

    A multi-band absorber composed of high-permittivity hexagonal ring dielectric resonators and a metallic ground plate is designed in the microwave band. Near-unity absorptions around 9.785 GHz, 11.525 GHz, and 12.37 GHz are observed for this metamaterial absorber. The dielectric hexagonal ring resonator is made of microwave ceramics with high permittivity and low loss. The mechanism for the near-unity absorption is investigated via the dielectric resonator theory. It is found that the absorption results from electric and magnetic resonances where enhanced electromagnetic fields are excited inside the dielectric resonator. In addition, the resonance modes of the hexagonal resonator are similar to those of standard rectangle resonators and can be used for analyzing hexagonal absorbers. Our work provides a new research method as well as a solid foundation for designing and analyzing dielectric metamaterial absorbers with complex shapes. Project supported by the National Natural Science Foundation of China (Grant Nos. 61331005, 11204378, 11274389, 11304393, and 61302023), the Aviation Science Foundation of China (Grant Nos. 20132796018 and 20123196015), the Natural Science Foundation for Post-Doctoral Scientists of China (Grant Nos. 2013M532131 and 2013M532221), the Natural Science Foundation of Shaanxi Province, China (Grant No. 2013JM6005), and the Special Funds for Authors of Annual Excellent Doctoral Degree Dissertations of China (Grant No. 201242).

  8. Periodic mesoporous organosilicas consisting of 3d hexagonally ordered interconnected globular pores

    NARCIS (Netherlands)

    Vercaemst, C.; Friedrich, H.|info:eu-repo/dai/nl/304837350; de Jongh, P.E.|info:eu-repo/dai/nl/186125372; Neimark, A.V.; Goderis, B.; Verpoort, F.; van der Voort, P.

    2009-01-01

    A new family of periodic mesoporous organosilicas with 100% E-configured ethenylene-bridges and controllable pore systems is presented. 2D hexagonally ordered hybrid nanocomposites consisting of cylindrical pores are obtained, of which some are filled with solid material. The architectural

  9. Self-diffusion in the hexagonal structure of Zirconium and Hafnium: computer simulation studies

    Directory of Open Access Journals (Sweden)

    Diego Hernán Ruiz

    2005-12-01

    Full Text Available Self-diffusion by vacancy mechanism is studied in two metals of hexagonal close packed structure, namely Hafnium and Zirconium. Computer simulation techniques are used together with many-body potentials of the embedded atom type. Defect properties are calculated at 0 K by molecular static while molecular dynamic is used to explore a wide temperature range.

  10. Tensile Behaviour of Welded Wire Mesh and Hexagonal Metal Mesh for Ferrocement Application

    Science.gov (United States)

    Tanawade, A. G.; Modhera, C. D.

    2017-08-01

    Tension tests were conducted on welded mesh and hexagonal Metal mesh. Welded Mesh is available in the market in different sizes. The two types are analysed viz. Ø 2.3 mm and Ø 2.7 mm welded mesh, having opening size 31.75 mm × 31.75 mm and 25.4 mm × 25.4 mm respectively. Tensile strength test was performed on samples of welded mesh in three different orientations namely 0°, 30° and 45° degrees with the loading axis and hexagonal Metal mesh of Ø 0.7 mm, having opening 19.05 × 19.05 mm. Experimental tests were conducted on samples of these meshes. The objective of this study was to investigate the behaviour of the welded mesh and hexagonal Metal mesh. The result shows that the tension load carrying capacity of welded mesh of Ø 2.7 mm of 0° orientation is good as compared to Ø2.3 mm mesh and ductility of hexagonal Metal mesh is good in behaviour.

  11. Holland's Hexagonal Personality Model for a Sample of Greek University Students

    Science.gov (United States)

    Sidiropoulou-Dimakakou, Despina; Mylonas, Kostas; Argyropoulou, Katerina

    2008-01-01

    The aim of this study was to describe the hexagonal person-environment fit for the Holland personality types for a Greek sample of 156 university students. The statistical analysis followed both exploratory--such as multidimensional scaling--and confirmatory methods--such as covariance structure models. These methods were employed in an…

  12. 2D of hexagonal plasmonic necklaces for enhanced second harmonic generation

    DEFF Research Database (Denmark)

    Gómez-Tornero, Alejandro; Tserkezis, Christos; Mateos, Luis

    2017-01-01

    Hexagonal plasmonic necklaces of silver nanoparticles organized in 2D superlattices on functional ferroelectric templates are fabricated in large-scale spatial regions by using a surfactant-free photo-deposition process. The plasmonic necklaces support broad radiative plasmonic resonances allowin...

  13. Direct synthesis of inverse hexagonally ordered diblock copolymer/polyoxometalate nanocomposite films

    NARCIS (Netherlands)

    Lunkenbein, T.; Kamperman, M.M.G.; Li, Z.; Bojer, C.; Drechsler, M.; Forster, S.; Wiesner, U.; Muller, A.; Breu, J.

    2012-01-01

    Nanostructured inverse hexagonal polyoxometalate composite films were cast directly from solution using poly(butadiene-block-2-(dimethylamino)ethyl methacrylate) (PB-b-PDMAEMA) diblock copolymers as structure directing agents for phosphomolybdic acid (H(3)[PMo(12)O(40)], H(3)PMo). H(3)PMo units are

  14. Eigenstates of a particle in an array of hexagons with periodic boundary condition

    Directory of Open Access Journals (Sweden)

    A Nemati

    2013-10-01

    Full Text Available In this paper the problem of a particle in an array of hexagons with periodic boundary condition is solved. Using the projection operators, we categorize eigenfunctions corresponding to each of the irreducible representations of the symmetry group . Based on these results, the Dirichlet and Neumann boundary conditions are discussed.

  15. Discovery of new hexagonal supramolecular nanostructures formed by squalenoylation of an anticancer nucleoside analogue.

    Science.gov (United States)

    Couvreur, Patrick; Reddy, L Harivardhan; Mangenot, Stéphanie; Poupaert, Jacques H; Desmaële, Didier; Lepêtre-Mouelhi, Sinda; Pili, Barbara; Bourgaux, Claudie; Amenitsch, H; Ollivon, Michel

    2008-02-01

    In this study, the dynamically folded conformation of squalene (SQ) is taken advantage of to link this natural compound to the anticancer nucleoside analogue gemcitabine (gem) in order to achieve the spontaneous formation of nanoassemblies (SQgem) in water. Cryogenic transmission electron microscopy examination reveals particles (104 nm) with a hexagonal or multifaceted shape that display an internal structure made of reticular planes, each particle being surrounded by an external shell. X-ray diffraction evidences the hexagonal molecular packing of SQgem, resulting from the stacking of direct or inverse cylinders. The respective volumes of the gem and SQ molecules as well as molecular modeling of SQgem suggest the stacking of inverse hexagonal phases, in which the central aqueous core, consisting of water and gem molecules, is surrounded by SQ moieties. These SQgem nanoassemblies also exhibit impressively greater anticancer activity than gem against a solid subcutaneously grafted tumor, following intravenous administration. To our knowledge, this is the first demonstration of hexagonal phase organization with a SQ derivative.

  16. Laplace type problems for a lattice with cell composed by two triangles and one hexagon

    Directory of Open Access Journals (Sweden)

    Marius Stoka

    2016-09-01

    Full Text Available We solve a Laplace type problem for a lattice of the Euclidean plane with cell composed by two triangles and one hexagon. We compute the probability that a segment of random position and constant length intersects a side of the lattice.

  17. Comparative study of the interfaces of graphene and hexagonal boron nitride with silver

    DEFF Research Database (Denmark)

    Garnica, Manuela; Schwarz, Martin; Ducke, Jacob

    2016-01-01

    Silver opens up interesting perspectives in the fabrication of complex systems based on heteroepitaxial layers after the growth of a silicene layer on its (111) face has been proposed. In this work we explore different synthesis methods of hexagonal boron nitride (h-BN) and graphene sheets on sil...

  18. A study on the behaviour of M-type barium hexagonal ferrite based ...

    Indian Academy of Sciences (India)

    This paper deals with development of single- and double-layer microwave absorbing paints using Mn-substituted barium hexagonal ferrite. The comparative studies of both theoretical and experimental results at Ku band have been reported. It has been found that the single layer absorbing paint exhibits peak absorption of ...

  19. Analisa Faktor Penyebab Kegagalan Mesin Grinder pada Proses Produksi Plastic Film di PT. Mutiara Hexagon

    OpenAIRE

    Hidayat, Imam; Pratiwi, Swandya Eka

    2013-01-01

    Bila suatu mesin memiliki tingkat kegagalan yang tinggi, maka perlu dilakukan analisis mengenai penyebab – penyebab kegagalan tersebut hingga ke akar permasalahannya sehingga dapat menentukan tindakan yang sesuai untuk meningkatkan kinerja suatu mesin. PT. Mutiara Hexagon merupakan sebuah Perusahaan yang bergerak dibidang industri pembuatan plastik kemasan. Dalam line pembuatan lembaran film diperlukan mesin CPP (Cast Poly Propylene Machine) dan mesin grinder dalam prosesnya....

  20. Structural hierarchy in flow-aligned hexagonally self-organized microphases with parallel polyelectrolytic structures

    NARCIS (Netherlands)

    Ruotsalainen, T; Torkkeli, M; Serimaa, R; Makela, T; Maki-Ontto, R; Ruokolainen, J; ten Brinke, G; Ikkala, O; Mäkelä, Tapio; Mäki-Ontto, Riikka

    2003-01-01

    We report a novel structural hierarchy where a flow-aligned hexagonal self-organized structure is combined with a polyelectrolytic self-organization on a smaller length scale and where the two structures are mutually parallel. Polystyrene-block-poly(4-vinylpyridine) (PS-block-P4VP) is selected with