WorldWideScience

Sample records for couche limite turbulente

  1. Developpement et implementation d'une methode pour resoudre les equations de la couche limite laminaire et turbulente

    Science.gov (United States)

    Leuca, Maxim

    CFD (Computational Fluid Dynamics) is a computational tool for studying flow in science and technology. The Aerospace Industry uses increasingly the CFD modeling and design phase of the aircraft, so the precision with which phenomena are simulated boundary layer is very important. The research efforts are focused on optimizing the aerodynamic performance of airfoils to predict the drag and delay the laminar-turbulent transition. CFD codes must be fast and efficient to model complex geometries for aerodynamic flows. The resolution of the boundary layer equations requires a large amount of computing resources for viscous flows. CFD codes are commonly used to simulate aerodynamic flows, require normal meshes to the wall, extremely fine, and, by consequence, the calculations are very expensive. . This thesis proposes a new approach to solve the equations of boundary layer for laminar and turbulent flows using an approach based on the finite difference method. Integrated into a code of panels, this concept allows to solve airfoils avoiding the use of iterative algorithms, usually computing time and often involving convergence problems. The main advantages of panels methods are their simplicity and ability to obtain, with minimal computational effort, solutions in complex flow conditions for relatively complicated configurations. To verify and validate the developed program, experimental data are used as references when available. Xfoil code is used to obtain data as a pseudo references. Pseudo-reference, as in the absence of experimental data, we cannot really compare two software together. Xfoil is a program that has proven to be accurate and inexpensive computing resources. Developed by Drela (1985), this program uses the method with two integral to design and analyze profiles of wings at low speed (Drela et Youngren, 2014), (Drela, 2003). NACA 0012, NACA 4412, and ATR-42 airfoils have been used for this study. For the airfoils NACA 0012 and NACA 4412 the calculations are made using the Mach number M =0.17 and Reynolds number Re = 6x10 6 conditions for which we have experimental results. For the airfoil ATR-42 the calculations are made using the Mach number M =0.1 and Reynolds number Re=536450 as it was analysed in LARCASE's Price-Paidoussis wind tunnel. Keywords: boundary layer, direct method, displacement thickness, finite differences, Xfoil code.

  2. Simulation de la couche limite hypersonique autour d'un corps ...

    African Journals Online (AJOL)

    Une des contraintes majeures intervenant dans la conception de la protection thermique d'engin spatial hypersonique est liée à l'échauffement de la paroi. Elle est du principalement à la présence de chocs forts au sein de l'écoulement, à la dissipation visqueuse dans les couches limites et aux effets de thermochimie.

  3. Turbulent diffusion downstream of a linear heat source installed in a turbulent boundary layer; Diffusion turbulente en aval d`une source lineaire de chaleur placee dans une couche limite turbulente

    Energy Technology Data Exchange (ETDEWEB)

    El Kabiri, M.; Paranthoen, P.; Rosset, L.; Lecordier, J.C. [Rouen Univ., 76 - Mont-Saint-Aignan (France)

    1997-12-31

    An experimental study of heat transport downstream of a linear source installed in a turbulent boundary layer is performed. Second and third order momenta of velocity and temperature fields are presented and compared to gradient-type modeling. (J.S.) 7 refs.

  4. Microprocessor controlled limitation system for a stand-alone freely movable treatment couch

    NARCIS (Netherlands)

    van de Vondel, I.; Coppens, L.; Verellen, D.; Bel, A.; Linthout, N.; de Beukeleer, M.; van den Berge, D.; Storme, G.

    1998-01-01

    Because of the capability of free movement in the treatment room, we recently introduced a Hercules treatment couch on one of our linear accelerators. One of the advantages of this couch is that it allows for a more flexible way of patient setup and that it can be moved entirely out of the way to

  5. Statistical analysis of high order moments is a turbulent boundary layer with strong density differences; Analyse statistique des moments d'ordre eleve dans une couche limite turbulente en presence de differences de densite importantes

    Energy Technology Data Exchange (ETDEWEB)

    Soudani, A. [Batna Univ., Dept. de Physique, Faculte des Sciences (Algeria); Bessaih, R. [Mentouri-Constantine Univ., Dept. de Genie Mecanique, Faculte des Sciences de l' Ingenieur (Algeria)

    2004-12-01

    The study of turbulent boundary layer with strong differences of density is important for the understanding of practical situations occurring for example in the cooling of turbine blades through the tangential injection of a different gas or in combustion. In order to study the fine structure of wall turbulence in the presence of significant variations of density, a statistical analysis of the experimental data, obtained in a wind tunnel, is carried out. The results show that the relaxation of the skewness factor of u'(S{sub u'}) is carried out more quickly in the external layer than close to the wall, as well for the air injection as for the helium injection. S{sub u'} grows close to the injection slot in an appreciable way and this increase is accentuated for the air injection than for the helium injection. This growth of the skewness factor close to the injection slot can be explained by the increase in the longitudinal convective flux of turbulent energy in this zone. The results show for the distribution of the flatness factor F{sub u'} that there is no significant effect of the density gradient on the intermittent structure of the instantaneous longitudinal velocity in the developed zone, x/{delta} {>=} 5. The statistical analysis carried out in this study shows that the helium injection in the boundary layer generates more violent ejections than in the case of air injection. This result is confirmed by the significant contribution of the ejections to turbulent mass flux.

  6. CouchDB the definitive guide

    CERN Document Server

    Anderson, J; Slater, Noah

    2010-01-01

    Three of CouchDB's creators show you how to use this document-oriented database as a standalone application framework or with high-volume, distributed applications. With its simple model for storing, processing, and accessing data, CouchDB is ideal for web applications that handle huge amounts of loosely structured data. That alone would stretch the limits of a relational database, yet CouchDB offers an open source solution that's reliable, scales easily, and responds quickly. CouchDB works with self-contained data that has loose or ad-hoc connections. It's a model that fits many real-world

  7. Scaling CouchDB

    CERN Document Server

    Holt, Bradley

    2011-01-01

    This practical guide offers a short course on scaling CouchDB to meet the capacity needs of your distributed application. Through a series of scenario-based examples, this book lets you explore several methods for creating a system that can accommodate growth and meet expected demand. In the process, you learn about several tools that can help you with replication, load balancing, clustering, and load testing and monitoring. Apply performance tips for tuning your databaseReplicate data, using Futon and CouchDB's RESTful interfaceDistribute CouchDB's workload through load balancingLearn option

  8. Study of the influence of the turbulent boundary conditions of a flow with parietal injection; Etude de l'influence des conditions aux limites turbulentes d'un ecoulement avec injection parietale

    Energy Technology Data Exchange (ETDEWEB)

    Chaouat, B.

    1998-07-01

    Numerical simulations of flows inside a solid propellant rocket engine with parietal injection are performed using the numerical resolution of Navier-Stokes equations in a k-{epsilon} turbulence model. Boundary conditions are defined considering laminar and turbulent fluid injections on the wall. In parallel, a Couette-type model is used to determine the velocity profile near the wall and the wall constraint for a laminar fluid injection. An analysis of simulations shows the influence of boundary conditions on the transition of the flow from the laminar to the turbulent regime, on the velocity profile near the wall, and on the evolution of Reynolds pressures. The average velocity profile is well reproduced but the first-order k-{epsilon} turbulence model shows limitations for the reproduction of turbulent pressure levels. A second-order Reynolds pressure model should be more appropriate. (J.S.)

  9. Superheroes on the Couch

    OpenAIRE

    White, Walter; Fernandez, Hilda; Green, Larry; Kingsbury, Paul; Adleman, Dan

    2014-01-01

    Drawing on psychoanalysis and critical theory, we explore some aspects of the human fascination with superheroes. From the traditional to the unconventional, as well as from the stars to the sidekicks, this panel will place some superheroes on the couch to freely speak about how society uses and produces super heroism.

  10. Advances in Laminar Turbulent Transition Modelling (Les avancees dans la modelisation de la transition laminaire turbulente)

    Science.gov (United States)

    2008-06-01

    la transition, la croissance des instabilités 3D et leurs mécanismes d’éclatement, les progrès effectués dans les méthodes Navier Stoke parabolisées...EN-AVT-151 Advances in Laminar Turbulent Transition Modelling (Les avancées dans la modélisation de la transition laminaire turbulente) Papers...

  11. Physique et modélisation d’interactions instationnaires onde de choc/couche limite autour de profils d’aile transsoniques par simulation numérique

    OpenAIRE

    Grossi, Fernando

    2014-01-01

    L’interaction onde de choc/couche limite en écoulement transsonique autour de profils aérodynamiques est étudiée numériquement utilisant différentes classes de modélisation de la turbulence. Les approches utilisées sont celles de modèles URANS et de méthodes hybrides RANS-LES. L’emploi d’une correction de compressibilité pour les fermetures à une équation est aussi évalué. Premièrement, la séparation intermittente induite par le choc sur un profil supercritique en conditions d’incidence proc...

  12. Reducing patient posture variability using the predicted couch position

    Energy Technology Data Exchange (ETDEWEB)

    Kruijf, Wilhelmus J.M. de, E-mail: kruijf.de.w@bvi.nl; Martens, Rob J.W.

    2015-10-01

    A method is presented in which the couch position is predicted before the treatment instead of obtaining a reference position at the first treatment fraction. This prevents systematic differences in patient posture between preparation and treatment. In literature, only limited data are available on couch positioning. We position our patients at the planned couch position, allowing a small difference between skin marks and lasers, followed by online imaging. For a 3-month period, our standard deviations (mm) in couch position in the vertical, longitudinal, and lateral directions were head and neck—1.6, 2.8, and 2.5; thorax—2.9, 5.5, and 4.5; breast—3.0, 4.1, and 4.0; and pelvis—3.5, 4.0, and 4.7, respectively. We have improved the reproducibility of patient posture in our institute by using the predicted couch position. Our data may serve as a reference for other institutes because the couch position variation is less than that published in literature.

  13. Intellectual Couch Potato?

    Science.gov (United States)

    Mason, Diana S.

    2002-08-01

    What does this say for where we've been and where we're going? The Information Age has brought us closer together. I know more about more people and events than I have ever known. I see this as a good thing. It is easy to keep in touch with friends. It is easy to buy and sell over the Internet, to seek answers on various questions, to gather facts, to improve your mind, etc. However, Joshua Benton of The Dallas Morning News1 cites a U.S. Department of Education report as stating, "Too many teachers make it into American classrooms without knowing the material they're teaching...". This concerns me greatly. With all the advantages afforded to us in an affluent society, then how/why can this be true? Other things in the report mentioned by Benton include (1) criticism of the states for setting low standards for new teachers; (2) colleges of education spending too much time on classroom management and teaching techniques and not enough on subject area content in mathematics, literature, and science; and (3) a call to the states to make it easier for professionals to switch careers into teaching through alternative programs. On the other side of the debate, how can 3 4 months of training in an alternative program bring successful teaching practices into the classroom? Yes, we need more teachers, especially in mathematics and science. Getting the content to these prospective teachers is not a problem. There is the Web, there are many online courses available (more on the way) both in subject areas and pedagogy, and the number of conferences and workshops offered abound. The following pages go into great depth regarding all the wonderful talks, workshops, and entertaining events that you can attend at the Fall 2002, ACS National Meeting, August 18 20. However, you've got to get off the couch and attend! The High School Program is Monday, August 19, from 8:30 until 3:00 at the Park Plaza Hotel. Preregistration is $30. Mahatma Gandhi said, "Live as if you were to die

  14. Chimpanzee 'Ham' In Biopack Couch

    Science.gov (United States)

    1961-01-01

    A three-year-old chimpanzee, named Ham, in the biopack couch for the MR-2 suborbital test flight. On January 31, 1961, a Mercury-Redstone launch from Cape Canaveral carried the chimpanzee 'Ham' over 640 kilometers down range in an arching trajectory that reached a peak of 254 kilometers above the Earth. The mission was successful and Ham performed his lever-pulling task well in response to the flashing light. NASA used chimpanzees and other primates to test the Mercury Capsule before launching the first American astronaut Alan Shepard in May 1961. The successful flight and recovery confirmed the soundness of the Mercury-Redstone systems.

  15. Electromagnetic guided couch and multileaf collimator tracking on a TrueBeam accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Rune; Ravkilde, Thomas; Worm, Esben Schjødt [Department of Medical Physics, Aarhus University Hospital, Aarhus 8000 (Denmark); Toftegaard, Jakob; Grau, Cai; Poulsen, Per Rugaard, E-mail: per.poulsen@rm.dk [Department of Oncology, Aarhus University Hospital, Aarhus 8000 (Denmark); Macek, Kristijan [Varian Medical Systems Imaging Laboratory GmbH, CH-5400 Baden (Switzerland)

    2016-05-15

    Purpose: Couch and MLC tracking are two promising methods for real-time motion compensation during radiation therapy. So far, couch and MLC tracking experiments have mainly been performed by different research groups, and no direct comparison of couch and MLC tracking of volumetric modulated arc therapy (VMAT) plans has been published. The Varian TrueBeam 2.0 accelerator includes a prototype tracking system with selectable couch or MLC compensation. This study provides a direct comparison of the two tracking types with an otherwise identical setup. Methods: Several experiments were performed to characterize the geometric and dosimetric performance of electromagnetic guided couch and MLC tracking on a TrueBeam accelerator equipped with a Millennium MLC. The tracking system latency was determined without motion prediction as the time lag between sinusoidal target motion and the compensating motion of the couch or MLC as recorded by continuous MV portal imaging. The geometric and dosimetric tracking accuracies were measured in tracking experiments with motion phantoms that reproduced four prostate and four lung tumor trajectories. The geometric tracking error in beam’s eye view was determined as the distance between an embedded gold marker and a circular MLC aperture in continuous MV images. The dosimetric tracking error was quantified as the measured 2%/2 mm gamma failure rate of a low and a high modulation VMAT plan delivered with the eight motion trajectories using a static dose distribution as reference. Results: The MLC tracking latency was approximately 146 ms for all sinusoidal period lengths while the couch tracking latency increased from 187 to 246 ms with decreasing period length due to limitations in the couch acceleration. The mean root-mean-square geometric error was 0.80 mm (couch tracking), 0.52 mm (MLC tracking), and 2.75 mm (no tracking) parallel to the MLC leaves and 0.66 mm (couch), 1.14 mm (MLC), and 2.41 mm (no tracking) perpendicular to the

  16. SU-E-T-98: Dependence of Radiotherapy Couch Transmission Factors On Field Size and Couch-Isocenter Distance

    International Nuclear Information System (INIS)

    Benhabib, S; Duan, J; Wu, X; Cardan, R; Shen, S; Huang, M; Popple, R; Brezovich, I

    2014-01-01

    Purpose: The dosimetric effect of the treatment couch is non-negligible in today's radiotherapy treatment. To accurately include couch in dose calculation, we investigated the dependence of couch transmission factors on field size and couch-isocenter distance. Methods: Couch transmission factors for Varian Exact Couch were determined by taking the ratios of ionization of a posterior-anterior beam with and without the couch in the beam path. Measurements were performed at the isocenter using a PTW cylindrical ionization chamber (Model 31030) with an Aluminum buildup cap of 1.1 cm thick for the 6 MV photon beam. Ionization readings for beam sizes ranging from 2 × 2 cm2 to 40 × 40 cm2 were taken. Transmission factors for couch-isocenter distances ranging from 3 cm to 20 cm were also investigated. Results: The couch transmission factors increased with the field size approximately in an exponential manner. For the field sizes that we tested, the transmission factor ranged from 0.976 to 0.992 for couch-isocenter distance of 3 cm. The transmission factor was also monotonically dependent on couch-isocenter separation distance, but in a lighter magnitude. For the tested couch heights, the transmission factor ranged from 0.974 – 0.972 for 2 × 2 cm2 field size and 0.992 – 0.986 for 40 × 40 cm2 field size. The dependence on couch-isocenter distance is stronger for larger field size. Conclusions: The transmission factor of a radiotherapy treatment couch increases with field size of the radiation beam and its distance from the isocenter. Such characterization of the couch transmission factor helps improve the accuracy of couch modeling for radiotherapy treatment planning

  17. Dosimetric evaluation of prostate rotations and their correction by couch rotations

    NARCIS (Netherlands)

    van Herten, Yvonne R. J.; van de Kamer, Jeroen B.; van Wieringen, Niek; Pieters, Bradley R.; Bel, Arjan

    2008-01-01

    PURPOSE: To investigate the dosimetric effect of prostate rotations and limited on-line corrections by couch rotations (

  18. Numerical simulation of turbulent shear flow using a cascade model; Numerische Simulation turbulenter Scherstroemungen mit einem Kaskadenmodell

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, V.

    1998-01-01

    Homogeneous stratified turbulent shear flow was simulated numerically using the cascade model of Eggers and Grossmann (1991). The model is made applicable to homogeneous shear flow by transformation into a coordinate system that moves along with a basic flow with a constant vertical velocity gradient. The author simulated cases of stable thermal stratification with Richardson numbers in the range of 0{<=}Ri{<=}1. The simulation data were evaluated with particular regard to the anisotropic characteristics of the turbulence field. Further, the results are compared with some common equation systems up to second order. (orig.) [Deutsch] Thema der vorliegenden Dissertation ist die numerische Simulation homogener geschichteter turbulenter Scherstroemungen. Grundlage der Simulation ist das von Eggers and Grossmann (1991) entwickelte Kaskadenmodell. Dieses Modell wird durch Transformation in ein Koordinatensystem, das mit einem Grundstrom mit konstantem vertikalen Geschwindigkeitsgradienten mitbewegt wird, auf homogene Scherstroemungen angewendet. Simuliert werden Faelle mit stabiler thermischer Schichtung mit Richardsonzahlen im Bereich von 0{<=}Ri{<=}1. Der Schwerpunkt bei der Auswertung der Simulationsdaten liegt auf der Untersuchung der Anisotropie-Eigenschaften des Turbulenzfeldes. Darueber hinaus wird ein Vergleich mit einigen gaengigen Schliessungsansaetzen bis zur zweiten Ordnung gezogen. (orig.)

  19. La destruction de la couche d'ozone

    OpenAIRE

    Mahieu, Emmanuel; Theate, Pascal; Brahy, Vincent

    2007-01-01

    L’ozone (O3) est présent dans l’atmosphère terrestre en quantité limitée, avec un maximum de concentration entre 15 et 50 km d’altitude. Cette molécule y joue un rôle essentiel en filtrant les rayons solaires ultraviolets dont les effets sur les êtres vivants peuvent être nocifs. L’influence des activités humaines sur la couche d’ozone stratosphérique s’est manifestée dès le début des années 1980, principalement au dessus de l’Antarctique, où une baisse significative de la quantité totale d’o...

  20. Cataract treatment: must we remain blind to couching? | Okoye ...

    African Journals Online (AJOL)

    Aim: To highlight the persistence of couching as a treatment for cataract in our community and its attendant complications. Materials and Methods: Retrospective study, using hospital records of 9 patients who had undergone couching and presented at the eye clinic, University of Nigeria Teaching Hospital, Enugu between ...

  1. Camera-based independent couch height verification in radiation oncology

    NARCIS (Netherlands)

    Kusters, M.; Louwe, R.J.W.; Biemans-van Kastel, L.; Nieuwenkamp, H.; Zahradnik, R.; Claessen, R.; Seters, R.V.; Huizenga, H.

    2015-01-01

    For specific radiation therapy (RT) treatments, it is advantageous to use the isocenter-to-couch distance (ICD) for initial patient setup.(1) Since sagging of the treatment couch is not properly taken into account by the electronic readout of the treatment machine, this readout cannot be used for

  2. Traditional couching for cataract treatment: A cause of visual ...

    African Journals Online (AJOL)

    The age range was from 43 years to 80years. The period between couching and presentation was between 3 months and 10 years. All the patients presented as a result of poor vision in the couched eyes. The complications recorded include glaucoma, optic atrophy and panuveitis. None had previous spectacle correction.

  3. Complications of traditional couching in a Nigerian local population

    African Journals Online (AJOL)

    Tabic 1 Complications in couched eyes. Complications. Frequency. Percentage. Secondary glaucoma. 8. 61.54 llyphaema. 2. 15.38. Optic atrophy. 2. 15.38. Phthisical globe and total. 1. 7.69. Hyphaema. Total. 13. 100%. Table 2 Visual acuity in couched eyes at presentation. Visual acuity. No. of eyes. Percentage. NLP. 6.

  4. Youth Homelessness and Vulnerability: How Does Couch Surfing Fit?

    Science.gov (United States)

    Curry, Susanna R; Morton, Matthew; Matjasko, Jennifer L; Dworsky, Amy; Samuels, Gina M; Schlueter, David

    2017-09-01

    Youth homelessness is a problem characterized by high levels of vulnerability. The extent to which couch surfing - moving from one temporary housing arrangement to another - is part of youth homelessness is not well understood. Chapin Hall's Voices of Youth Count, a national research initiative, involves a multicomponent approach to studying youth homelessness. This study reports emerging findings regarding couch surfing and homelessness primarily from a national survey of 13,113 adults with youth ages 13-25 in their households or who are themselves ages 18-25. Findings suggest that couch surfing is relatively common, particularly among the older age group. Among households with 13- to 17-year-olds and 18- to 25-year-olds, 4.0% and 20.5%, respectively, reported that any of them had couch surfed in the last 12 months. There are notable social, economic, and educational differences, on average, between youth reporting homelessness and those reporting only couch surfing. However, most youth who report experiencing homelessness also report couch surfing, and these youth who experience both circumstances present high levels of socioeconomic vulnerability. Couch surfing encompasses a range of experiences, some of which likely include need for services. Interviews currently in the field, and expanded analysis of data, will contribute more nuanced policy insights. © Society for Community Research and Action 2017.

  5. Turbulent conductivity in parallel with iso-velocities in a planar established flow; Conductibilite turbulente parallelement aux isovitesses dans un ecoulement plan en regime etabli

    Energy Technology Data Exchange (ETDEWEB)

    Jullien, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires, Direction des piles atomiques

    1968-02-01

    In this thesis are presented the experimental results obtained during the study of the turbulent diffusion of heat using a wire source in a flat air flow. The Taylor statistical theory laws are well respected in the domain studied. The experiments have made it possible to evaluate the influence of the Reynolds number and of the distance from the wall on the quadratic values of velocity fluctuations and on the Lagrange turbulence scales. In particular, the author has found a correlation between the Lagrange scales and the friction coefficient when the Reynolds number varies. A diffusion law is derived from the Taylor theory; it makes it possible to explain more clearly the idea of turbulent conductivity. (author) [French] Cette these presente les resultats experimentaux de l'etude de la diffusion turbulente de la chaleur a partir d'un fil source dans un ecoulement d'air plan. Les lois de la theorie statistique de Taylor sont bien verifiees dans le domaine d'etude. Les experiences ont permis d'evaluer l'influence du nombre de Reynolds et de la distance a la paroi sur les valeurs quadratiques des fluctuations de vitesse et les echelles lagrangiennes de turbulence. En particulier, l'auteur a trouve une correlation entre les echelles lagrangiennes et le coefficient de frottement lorsque le nombre de Reynolds varie. Comme consequences de la theorie de Taylor, une loi de diffusion est etablie et permet de preciser la notion de conductibilite turbulente. (auteur)

  6. The analytic setting today: using the couch or the chair?

    Science.gov (United States)

    Wiener, Jan

    2015-09-01

    This paper re-visits Murray Jackson's 1961 paper in the Journal of Analytical Psychology, 'Chair, couch and countertransference', with the aim of exploring the role of the couch for Jungian analysts in clinical practice today. Within the Society of Analytical Psychology (SAP) and some other London-based societies, there has been an evolution of practice from face-to-face sessions with the patient in the chair, as was Jung's preference, to a mode of practice where patients use the couch with the analyst sitting to the side rather than behind, as has been the tradition in psychoanalysis. Fordham was the founding member of the SAP and it was because of his liaison with psychoanalysis and psychoanalysts that this cultural shift came about. Using clinical examples, the author explores the couch/chair question in terms of her own practice and the internal setting as a structure in her mind. With reference to Bleger's (2013) paper 'Psychoanalysis of the psychoanalytic setting', the author discusses how the analytic setting, including use of the couch or the chair, can act as a silent container for the most primitive aspects of the patient's psyche which will only emerge in analysis when the setting changes or is breached. © 2015, The Society of Analytical Psychology.

  7. The return of the Freudian Couch®

    DEFF Research Database (Denmark)

    Juelskjær, Malou; Staunæs, Dorthe; Ratner, Helene Gad

    2013-01-01

    This article explores how the affective “set-up” of Freud’s legendary couch has been exported into modern education relations. The so-called psy-sciences from pedagogy, psychology, and psychiatry have informed self-management in school. Managing self-management has a material-affective dimension...... of comfort technology, we explore how the couch participates in transforming intensities and shaping desires by affecting bodies, voices, atmospheres, and relations. We look into the Danish school, which over the past decade has intensified its focus on preparing students to take part in a workforce....... Through our material-affective perspective we zoom in on everyday practices in the offices of principals to see how the couch, a mundane comfort technology, affects management relations between principal, students, parents, and teachers....

  8. On Murray Jackson's 1961 'Chair, couch and countertransference'.

    Science.gov (United States)

    Connolly, Angela

    2015-09-01

    One of the problems facing psychoanalysts of all schools is that theory has evolved at a much faster pace than practice. Whereas there has been an explosion of theory, practice has remained, at least officially, static and unchanging. It is in this sense that Murray Jackson's 1961 paper is still relevant today. Despite the rise of the new relational and intersubjective paradigms, most psychoanalysts, and not a few Jungian analysts, still seem to feel that the couch is an essential component of the analytical setting and process. If the use of the couch is usually justified by the argument that it favours regression, facilitates analytical reverie and protects the patient from the influence of the analyst, over time many important psychoanalysts have come to challenge this position. Increasingly these analysts suggest that the use of the couch may actually be incompatible with the newer theoretical models. This contention is strengthened by some of the findings coming from the neurosciences and infant research. This underlines the necessity of empirical research to verify the clinical effectiveness of these different positions, couch or face-to-face, but it is exactly this type of research that is lacking. © 2015, The Society of Analytical Psychology.

  9. Global concept, local practice: Taiwanese experience of CouchSurfing

    NARCIS (Netherlands)

    Chen, D.-J.

    2012-01-01

    Hospitality exchange tourism is a new type of niche tourism, which is highly dependent on the Internet. Through participating in global hospitality exchange networks, such as CouchSurfing, tourists can meet local people who are willing to offer free accommodation, and hosts can also meet people

  10. Validation of dynamic treatment-couch tracking for prostate SBRT.

    Science.gov (United States)

    Ehrbar, Stefanie; Schmid, Simon; Jöhl, Alexander; Klöck, Stephan; Guckenberger, Matthias; Riesterer, Oliver; Tanadini-Lang, Stephanie

    2017-06-01

    In stereotactic body radiation therapy (SBRT) of prostatic cancer, a high dose per fraction is applied to the target with steep dose gradients. Intrafractional prostate motion can occur unpredictably during the treatment and lead to target miss. This work investigated the dosimetric benefit of motion compensation with dynamic treatment-couch tracking for prostate SBRT treatments in the presence of prostatic motion. Ten SBRT treatment plans for prostate cancer patients with integrated boosts to their index lesion were prepared. The treatment plans were applied with a TrueBeam linear accelerator to a phantom in (a) static reference position, (b) moved with five prostate motion trajectories without any motion compensation, and (c) with real-time compensation using transponder-guided couch tracking. The geometrical position of the electromagnetic transponder was evaluated in the tracked and untracked situation. The dosimetric performance of couch tracking was evaluated, using Gamma agreement indices (GAI) and other dose parameters. These were evaluated within the phantoms biplanar diode array, as well as target- and organ-specific. The root-mean-square error of the motion traces (range: 0.8-4.4 mm) was drastically reduced with couch tracking (0.2-0.4 mm). Residual motion was mainly observed at abrupt direction changes with steep motion gradients. The phantom measurements showed significantly better GAI 1%/1mm with tracked (range: 83.4%-100.0%) than with untracked motion (28.9%-99.7%). Also GAI 2%/2mm was significantly superior for the tracked (98.4%-100.0%) than the untracked motion (52.3%-100.0%). The organ-specific evaluation showed significantly better target coverage with tracking. The dose to the rectum and bladder showed a dependency on the anterior-posterior motion direction. Couch tracking clearly improved the dosimetric accuracy of prostate SBRT treatments. The treatment couch was able to compensate the prostatic motion with only some minor residual motion

  11. Getting Started with GEO, CouchDB, and Nodejs

    CERN Document Server

    Thompson, Mick

    2011-01-01

    Today's mobile devices have GPS and standard APIs to give you access to coordinates-but what can you do with that data? With this concise book, application developers learn how to work with location data quickly and easily, using Node.js, CouchDB, and other open source tools and libraries. Node.js makes it simple to run event code on the Web, and the CouchDB document-oriented database lets you store location data and perform complex queries on it quickly. You'll learn how to get started with these tools, and then use them together to build an example project called MapChat, using HTML and Ja

  12. "Couch-potatoeism" and childhood obesity: The inverse causality hypothesis.

    Science.gov (United States)

    Fröberg, Andreas

    2015-04-01

    The bulk of cross-sectional studies suggests that lower levels of physical activity are associated with childhood obesity. Although this has led to the general understanding that "couch-potatoes" are fat on account of their inactive lifestyles, cross-sectional studies do not imply causality. On the contrary, the contribution of physical activity to obesity during childhood is currently unclear, and lately, studies have suggested that "couch-potatoeism" could be the result of obesity rather than its cause. Coupled with evidence suggesting that interventions have had little effect on children's physical activity levels as well as on obesity, this inverse causality challenges the role of physical activity in childhood obesity prevention strategies. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Caracterisation geotechnique du sable silteux utilise en couche de ...

    African Journals Online (AJOL)

    Le présent travail a pour objectif de déterminer les performances mécaniques en termes de portance CBR, de résistance en compression et en traction des sables silteux du Togo et du Benin afin d'envisager la possibilité d'utilisation de ce matériaux dans les couches d'assise des routes. 24 échantillons prélevés au sud du ...

  14. CouchSurfing : experiences, reputation, references and decision-making in an online hospitality network

    OpenAIRE

    Franz, Melanie

    2014-01-01

    The aim of this thesis was to analyse behavioural patterns that occur after a negative experience during a hospitality exchange. The focus of this study is the largest online hospitality network to date, the CouchSurfing Project. CouchSurfing enables travellers to connect and to offer each other help in form of a free hospitality exchange. Furthermore, CouchSurfing presents a platform for cultural exchange and the possibility for members to connect in this online-offline community. As part...

  15. Scalable Web Application using Node.JS and CouchDB

    OpenAIRE

    Paudyal, Umesh

    2011-01-01

    This report presents design and implementation of a protoype application using server side javascript programming language, node.JS and couchDB as backend database. It scales and evaluates the developed prototype application and the couchDB for their scalability and performance. The report concludes that node.JS is a suitable framework for development of scalable web servers and couchDB as a backend database, though natively not distributed and scalable, can be scaled and distributed across m...

  16. Machine-specific quality assurance procedure for stereotactic treatments with dynamic couch rotations.

    Science.gov (United States)

    Wilson, Byron; Gete, Ermias

    2017-12-01

    We present a method in which the treatment couch's accuracy is measured using the electronic portal imaging device (EPID) and a phantom of our own construction. Using this phantom, we were able to quantify the treatment couch walkout, and the rotation angle accuracy for both static and dynamic couch treatments. These measurements were used to provide an accurate measure of the treatment couch isocenter as well as to verify the couch rotation angle recorded in the trajectory log. The phantom was constructed using a polystyrene slab in which five ball bearings of 4 mm diameter are placed on the same plane at varying radii (0, 2.8, 4.4, 5.6, and 6.7 cm). The couch was rotated through its full extent (-90, 90 degrees) while MV images were acquired continuously. The couch rotational accuracy was calculated using a least squares minimization which fit the locations of the BBs to their expected locations relative to reference setup conditions. Using this approach, rotation angle and isocenter walkout was calculated in three dimensions. These measurements were used to quantify the accuracy of the couch as well as to validate the Varian TrueBeam trajectory logs. Additionally, a method for an EPID-based couch star-shot measurement was developed and compared with the traditional film-based method. The measured couch center of rotation consisted of a cloud of points clustered around the room isocenter within 0.7 mm distance. The trajectory log couch angle values agreed with those recorded in the DICOM header of the EPID images to the third significant digit and the couch rotation angles recorded in the trajectory log and DICOM header agreed with the calculated values to 0.08 degrees. Comparison of couch star-shot measurement developed in this study with film-based star-shot measurements gave an agreement to within 0.2 mm. We have developed a quality assurance method for the treatment couch which is simple, accurate, and enables the user to access a multitude of consistent data

  17. Secondary glaucoma in a 76 year old male following couching by a ...

    African Journals Online (AJOL)

    Any opacity or loss of transparency of the lens that caused diminution or impairment of vision is called cataract. Treatment of cataract is by surgical extraction. Couching is the earliest form of cataract surgery, traced to Assyria in 1700 BC. Couching procedures result on lens luxation, or subluxation or dislodgement, not an ...

  18. The clinical impact of the couch top and rails on IMRT and arc therapy

    International Nuclear Information System (INIS)

    Pulliam, Kiley B; Howell, Rebecca M; Followill, David; Luo, Dershan; Kry, Stephen F; White, R Allen

    2011-01-01

    The clinical impact of the Varian Exact Couch on dose, volume coverage to targets and critical structures, and tumor control probability (TCP) has not been described. Thus, we examined their effects on IMRT and arc therapy. Five clinical prostate patients were planned with both 6 MV eight-field IMRT and 6 MV two-arc RapidArc techniques using the Eclipse treatment planning system. These plans neglected treatment couch attenuation, as is a common clinical practice. Dose distributions were then recalculated in Eclipse with the inclusion of the Varian Exact Couch (imaging couch top) and the rails in varying configurations. The changes in dose and coverage were evaluated using the dose-volume histograms from each plan iteration. We used a TCP model to calculate losses in tumor control resulting from not accounting for the couch top and rails. We also verified dose measurements in a phantom. Failure to account for the treatment couch and rails resulted in clinically unacceptable dose and volume coverage losses to the targets for both IMRT and RapidArc. The couch caused average prescription dose losses (relative to plans that ignored the couch) to the prostate of 4.2% and 2.0% for IMRT with the rails out and in, respectively, and 3.2% and 2.9% for RapidArc with the rails out and in, respectively. On average, the percentage of the target covered by the prescribed dose dropped to 35% and 84% for IMRT (rails out and in, respectively) and to 18% and 17% for RapidArc (rails out and in, respectively). The TCP was also reduced by as much as 10.5% (6.3% on average). Dose and volume coverage losses for IMRT plans were primarily due to the rails, while the imaging couch top contributed most to losses for RapidArc. Both the couch top and rails contribute to dose and coverage losses that can render plans clinically unacceptable. A follow-up study we performed found that the less attenuating unipanel mesh couch top available with the Varian Exact couch does not cause a clinically

  19. Electromagnetic guided couch and multileaf collimator tracking on a TrueBeam accelerator

    DEFF Research Database (Denmark)

    Hansen, Rune; Ravkilde, Thomas; Worm, Esben Schjødt

    2016-01-01

    Purpose: Couch and MLC tracking are two promising methods for real-time motion compensation during radiation therapy. So far, couch and MLC tracking experiments have mainly been performed by different research groups, and no direct comparison of couch and MLC tracking of volumetric modulated arc...... therapy (VMAT) plans has been published. The Varian TrueBeam 2.0 accelerator includes a prototype tracking system with selectable couch or MLC compensation. This study provides a direct comparison of the two tracking types with an otherwise identical setup. Methods: Several experiments were performed...... to characterize the geometric and dosimetric performance of electromagnetic guided couch and MLC tracking on a TrueBeam accelerator equipped with a Millennium MLC. The tracking system latency was determined without motion prediction as the time lag between sinusoidal target motion and the compensating motion...

  20. SU-F-T-457: A Filmless Method for Measurement of Couch Translation Per Gantry Rotation and Couch Speed for Tomotherapy Using ArcCheck

    Energy Technology Data Exchange (ETDEWEB)

    Yang, B; Wong, R; Geng, H; Lam, W; Cheung, K; Yu, S [Hong Kong Sanatorium & Hospital, Hong Kong, N/A, Hong Kong (China)

    2016-06-15

    Purpose: To develop a filmless methodology based on an ArcCheck for QA measurement of the couch translation per gantry rotation and couch speed of a Tomotherapy unit. Methods: Two test plans recommended by TG148 were chosen for this study. A helical plan with 1 cm field size opened the leaves for 180 degrees at the 2nd, 7th and 12th of total 13 rotations and was used to verify if the couch travelled the expected distance per gantry rotation. The other test plan was a static plan with the gantry at 0°, 1cm field width and constant couch movement speed of 0.5mm/s. It was used for couch speed measurement. The ArcCheck was isocentrically set up and recorded movie files which took a snapshot exposure every 50ms. Due to the spiral pattern of diodes distribution, when one of the diodes of the ArcCheck located at the beam center, the dose profile as measured by the row of diodes which surrounded the center diode should have a symmetrical pattern. We divided the profile into left half A and right half B. Then a shape parameter was defined as S=Σ|(A−B)|/Σ(A+B). By searching the local minimum of S parameter, the beam center at different time could be located. The machine trajectory log data were also collected and analyzed for comparison. Results: The mean value of measured couch translation and couch speed by ArcCheck had less than 0.05% deviation from the planned values. For couch speed measurement, our result showed a mean value of 0.5002 with an uncertainty ±0.0031, which agreed very well with both the plan setting of 0.5 mm/s and the machine log data of 0.5005 mm/s. Conclusion: Couch translation measured using ArcCheck is accurate and comparable to the film-based measurement. This filmless method also provides a convenient and independent way for measuring couch speed.

  1. Couches Minces de Titanate de Baryum Par Depot Organometallique

    Science.gov (United States)

    Ousi Benomar, Wahib

    1993-01-01

    Nous avons demontre la possibilite de realiser des couches minces de titanate de baryum par depot organometallique. Les films sont obtenus apres dissolution d'organometalliques choisis dans un solvant et une cuisson a une temperature determinee par thermogravimetrie. Apres un second traitement thermique a des temperatures plus elevees, les echantillons presentent une structure polycristalline tetragonale; les cristallites sont observes par microscopie electronique a balayage. La mesure de la constante dielectrique a permis de mettre en evidence une transition de phase de la structure tetragonale a la structure cubique a une temperature d'environ 125^circC. Les mesures d'indice ont ete effectuees. On note une augmentation de l'indice de refraction des films avec la temperature indiquant une meilleure densification des films. Nous avons aussi montre qu'il etait possible d'utiliser ce materiau en tant que guide d'onde optique pour pouvoir exploiter ses proprietes electrooptiques dans l'avenir.

  2. Limiter

    Science.gov (United States)

    Cohen, S.A.; Hosea, J.C.; Timberlake, J.R.

    1984-10-19

    A limiter with a specially contoured front face is provided. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution. This limiter shape accommodates the various power scrape-off distances lambda p, which depend on the parallel velocity, V/sub parallel/, of the impacting particles.

  3. SU-F-T-470: Implementation of a Daily Quality Assurance Phantom for Six Degrees-Of-Freedom Couch Testing

    International Nuclear Information System (INIS)

    Gaballa, H; O’Brien, M; Riegel, A; Jamshidi, A; Klein, E

    2016-01-01

    Purpose: To develop a daily quality assurance (QA) device that can test the 6DoF (degrees of freedom) couch repositioning accuracy, prior to SBRT treatment deliveries, with an accuracy of ±0.3 degrees and ±0.3 mm. Methods: A daily QA phantom is designed with a focus on the derived center of projections of its markers, rather than tracking its individual markers one at a time. This approach can be the most favorable to address the intended machining accuracy of the QA phantom and the CBCT spatial resolution limitations, primarily 1 mm min slice thickness, simultaneously. With the current design, ±0.1 mm congruence of the resultant center of gravity of the markers with reference CT (0.6 mm minimum slice thickness) vs CBCT (1.0 mm minimum slice thickness) can be achieved. If successful, the QA device should be qualified to test 6DoF couch performance with a gauged accuracy of ±0.3 degrees/±0.3 mm. Testing is performed for the Varian True Beam 2.0 6DoF system. Results: Once the QA phantom is constructed and tested, agreement of the center of gravity of the reference CT scan and the CBCT scan of ±0.1 mm is achieved. This has translated into a consistent 3D-3D match on the treatment machine, CT vs CBCT, with a repetitive ±0.1 mm variation, thus exceeding our expectations. We have deployed the phantom for daily QA on one of our accelerators, and found that the QA time has increased by only 10 minutes. Conclusion: A 6DoF phantom has been designed (patent pending) and built with a realistic work flow in mind where the daily couch accuracy QA checks taking less than 10 minutes. Current developments include integration with the Varian’s Machine Performance Check consistency module.

  4. SU-F-T-470: Implementation of a Daily Quality Assurance Phantom for Six Degrees-Of-Freedom Couch Testing

    Energy Technology Data Exchange (ETDEWEB)

    Gaballa, H; O’Brien, M; Riegel, A; Jamshidi, A; Klein, E [Northwell Health, Lake Success, NY (United States)

    2016-06-15

    Purpose: To develop a daily quality assurance (QA) device that can test the 6DoF (degrees of freedom) couch repositioning accuracy, prior to SBRT treatment deliveries, with an accuracy of ±0.3 degrees and ±0.3 mm. Methods: A daily QA phantom is designed with a focus on the derived center of projections of its markers, rather than tracking its individual markers one at a time. This approach can be the most favorable to address the intended machining accuracy of the QA phantom and the CBCT spatial resolution limitations, primarily 1 mm min slice thickness, simultaneously. With the current design, ±0.1 mm congruence of the resultant center of gravity of the markers with reference CT (0.6 mm minimum slice thickness) vs CBCT (1.0 mm minimum slice thickness) can be achieved. If successful, the QA device should be qualified to test 6DoF couch performance with a gauged accuracy of ±0.3 degrees/±0.3 mm. Testing is performed for the Varian True Beam 2.0 6DoF system. Results: Once the QA phantom is constructed and tested, agreement of the center of gravity of the reference CT scan and the CBCT scan of ±0.1 mm is achieved. This has translated into a consistent 3D-3D match on the treatment machine, CT vs CBCT, with a repetitive ±0.1 mm variation, thus exceeding our expectations. We have deployed the phantom for daily QA on one of our accelerators, and found that the QA time has increased by only 10 minutes. Conclusion: A 6DoF phantom has been designed (patent pending) and built with a realistic work flow in mind where the daily couch accuracy QA checks taking less than 10 minutes. Current developments include integration with the Varian’s Machine Performance Check consistency module.

  5. SU-E-T-655: Quantifying the Dosimetric Characteristics of a Calypso Compatible Radiotherapy Treatment Couch with Angular Transmission Functions

    International Nuclear Information System (INIS)

    Duan, J; Shen, S; Wu, X; Popple, R; Cardan, R; Huang, M; Tannazi, F; Brezovich, I

    2015-01-01

    Purpose: To quantified the dosimetric characteristics of a Calypso compatible radiotherapy couch using continuously scanned transmission factor as a function of gantry angle. Methods: Radiation dose as a function of gantry angle was measured with an ionization chamber at the center of a 30 cm diameter cylindrical phantom placed on Qfix kVue Calypso compatible couch. A 3-D scanner was employed to continuously scan the dose during an arc rotation delivery. Nearly continuous transmission curves of 0.03° step size were obtained from IEC gantry angle 90° to180° for 6 MV and 15 MV photon beams at three couch longitudinal positions (due to longitudinally non-uniform shape of the couch rails) with rails both at the center and on sides. The transmission curves were evaluated to assess the attenuation by the couch. They were also compared to those of a carbon fiber couch top. Results: The scanned transmission curves of the Calypso comptible couch showed fine details of the couch transmission as a function of gantry angle. The attenuation by the couch varied from 2.4% to 12.9% for the 6 MV photo beam and from 1.8% to 8.9% for the 15 MV photon beam depending on the gantry angle. The attenuation by the flat couch top is only approximately 2 to 3%, but by the rail is much more significant. Because the rails are not uniformly shaped in the longitudinal direction, attenuation by the rail for the same gantry angle varied with the rail longitudinal position. The transmission curves of the carbon fiber couch top are nearly identical to those of the Calypso compatible couch top. Conclusion: The Calypso compatible couch attenuates radiation by 2.4%–12.9% and 1.8%–8.9% for 6 MV and 15 MV photon beams, respectively. The attenuation by the rails is much more significant than the flat couch top

  6. Assessment of dose error due to nylon mesh of treatment couch.

    Science.gov (United States)

    Gul, Attia; Liaquat, Mehnaz; Kanwal, Aneela; Abbasi, Nadeem Zia; Kakakhel, Muhammad Basim; Ali, Akbar

    2015-12-01

    This study aims at the assessment of dose error in patients undergoing radiotherapy due to treatment couch of Co-60 teletherapy unit. In this study beam attenuation due to treatment couch of Co-60 unit was measured in air for different gantry angles and field sizes. Polymethylmethacrylate (PMMA) phantom was used to estimate the effect of depth on attenuation. Impact of couch on surface dose was also evaluated. Beam attenuation due to couch was in the range of 0.5-28% for different gantry angles with standard field size of 10 × 10 cm(2) with optimum position of metallic cranks. Maximum attenuation (29%) was observed with smallest field size i.e. 5 × 5 cm(2). Beam attenuation has been found higher in phantom as compared to that in air However, no particular trend of attenuation has been noted with varying depth of phantom. A 6% increase in surface dose has also been observed due to couch insertion for normal beam incidence. Maximum error of 80% is also note-worthy for most unfavorable situation of irradiation at 180 degree through the metallic cranks. It has been determined that ignoring the treatment couch and its accessories can result in dose error of 0.5-80%, depending on gantry angle, field size and position of couch accessories. Therefore, consideration of dose error due to couch during treatment planning is recommended. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  7. Dose attenuation by a carbon fiber linac couch and modeling with a treatment planning system

    International Nuclear Information System (INIS)

    Sanchez Galiano, P.; Garcia Sancho, J.M.; Crelgo, D.; Pamos, M.; Fernandez, J.; Vivanco, J.

    2010-01-01

    The purpose of this work is to investigate the attenuation caused by a carbon fiber linac treatment couch and the ability of a commercial radiotherapy treatment planning system to simulate it. The attenuation caused by an Exact treatment couch in a Varian Clinac 2100 C/D was characterized in detail. Both 6 MV and 18 MV photon beams were studied. The treatment couch was modeled and incorporated to Elekta XiO treatment planning system. Measured and computed attenuation values were compared. As a result we found that the attenuation caused by this complex treatment couch is strongly dependent on the incidence angle of the beam. The measured attenuation values reach 16% for 6 MV and 10% for 18 MV. The model incorporated to the treatment planning software allows reducing the differences between measured and calculated data below 2.5% and 2.0% for 6 MV and 18 MV respectively. In conclusion, it is strongly recommended accounting for the perturbation caused by this carbon fiber treatment couch when the beam intersects it. The treatment planning system studied can simulate this treatment couch accurately. Clinical implementation of the described method requires a reliable procedure to reproduce the same patient geometry in the treatment delivery and planning. (Author).

  8. The thin layer technique and its application to electron microscopy; La technique des couches minces et son application a la microscopie electronique

    Energy Technology Data Exchange (ETDEWEB)

    Ranc, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1957-10-15

    This work deals with the technique of thin layers obtained by evaporation under vacuum, in the thickness range extending from a few monoatomic layers to several hundred angstroms. The great theoretical and practical interest of these layers has, it is well known, given rise to many investigations from Faraday onwards. Within the necessarily restricted limits of this study, we shall approach the problem more particularly from the point of view of: - their production; - their use in electron microscopy. A critical appraisal is made, in the light of present-day knowledge, based on our personal experience and on an extensive bibliography which we have collected on the subject. (author) [French] Le present travail concerne la technique des couches minces obtenues par evaporation sous vide, dans le domaine d'epaisseur qui s'etend de quelques couches monoatomiques a plusieurs centaines d'angstroms. L'interet theorique et pratique considerable de ces couches a suscite, comme on sait, de nombreux travaux depuis Faraday. Dans le cadre necessairement restreint de cette these, nous aborderons plus particulierement le point de vue de: - leur obtention; - leur utilisation en microscopie electronique. Il s'agit d'une mise au point critique, a la lumiere des connaissances actuelles, appuyee sur notre experience personnelle et sur une importante bibliographie, qu'il nous a ete donne de reunir a ce sujet. (auteur)

  9. SU-E-T-240: Accuracy of Dose Attenuation Correction for a 6D Carbon Fiber Treatment Couch Using a Virtual Couch Technique Integrated into a Treatment Planning System.

    Science.gov (United States)

    Shioiri, K; Kurooka, M; Yoshino, S; Maehana, W; Itou, M; Kusano, Y; Ide, S; Onodera, M; Nonaka, T; Nakayama, Y

    2012-06-01

    A commercial 6D carbon fiber radiotherapy treatment couch (Imaging Couch Top, BrainLAB) has recently been reported to attenuate photon beams and increase skin dose. To prevent skin toxicity and ensure the target dose, it is important to correct the attenuation properties of the treatment couch with the treatment planning system (TPS). In this study, we evaluated the accuracy of dose attenuation correction by a virtual couch technique integrated into the TPS. A virtual couch was modeled in the TPS (Eclipse v10.0, Varian). The CT value of the virtual couch was assigned with the CT value of the kilovoltage-CT images of the treatment couch. A phantom consisting of several plastic water slabs was created. We selected an evaluation point within the phantom on the couch structure at a 9 cm depth from the couch surface, which was placed at the isocenter. The doses at this point were calculated and measured at several gantry angles, from 120 degree to 240 degree at 10 degree steps, and each field size was 10 cm × 10 cm. The prescribed dose was 100 monitor units for 6/10 MV photon beams and 6 MV-SRS mode (Trilogy Tx, Varian). Dose measurements were performed with an ion chamber. The largest difference between measured and calculated doses was 3.3% for a gantry angle of 120 degree and 6 MV-SRS mode. The average dose difference was within 1.6% for all gantry angles and photon beams. In the case without attenuation correction, the largest difference was 8.2% and the average difference was 5.2%. Use of the virtual couch technique in TPS accomplished sufficient accuracy for dose attenuation correction of the 6D carbon fiber treatment couch, and it is an effective method for clinical use. © 2012 American Association of Physicists in Medicine.

  10. Utilization of optical tracking to validate a software-driven isocentric approach to robotic couch movements for proton radiotherapy

    International Nuclear Information System (INIS)

    Hsi, Wen C.; Zeidan, Omar A.; Law, Aaron; Schreuder, Andreas N.

    2014-01-01

    Purpose: An optical tracking and positioning system (OTPS) was developed to validate the software-driven isocentric (SDI) approach to control the six-degrees-of-freedom movement of a robotic couch. Methods: The SDI approach to movements rotating around a predefined isocenter, referred to as a GeoIso, instead of a mechanical pivot point was developed by the robot automation industry. With robotic couch-sag corrections for weight load in a traditional SDI approach, movements could be accurately executed for a GeoIso located within a 500 mm cubic volume on the couch for treatments. The accuracy of SDI movement was investigated using the OTPS. The GeoIso was assumed to align with the proton beam isocenter (RadIso) for gantry at the reference angle. However, the misalignment between GeoIso and RadIso was quantitatively investigated by measuring the displacements at various couch angles for a target placed at the RadIso at an initial couch angle. When circular target displacements occur on a plane, a relative isocenter shift (RIS) correction could be applied in the SDI movement to minimize target displacements. Target displacements at a fixed gantry angle without and with RIS correction were measured for 12 robotic couches. Target displacements for various gantry angles were performed on three couches in gantry rooms to study the gantry-induced RadIso shift. The RIS correction can also be applied for the RadIso shift. A new SDI approach incorporating the RIS correction with the couch sag is described in this study. In parallel, the accuracy of SDI translation movements for various weight loads of patients on the couch was investigated during positioning of patients for proton prostate treatments. Results: For a fixed gantry angle, measured target displacements without RIS correction for couch rotations in the horizontal plane varied from 4 to 20 mm. However, measured displacements perpendicular to couch rotation plane were about 2 mm for all couches. Extracted

  11. Utilization of optical tracking to validate a software-driven isocentric approach to robotic couch movements for proton radiotherapy.

    Science.gov (United States)

    Hsi, Wen C; Law, Aaron; Schreuder, Andreas N; Zeidan, Omar A

    2014-08-01

    An optical tracking and positioning system (OTPS) was developed to validate the software-driven isocentric (SDI) approach to control the six-degrees-of-freedom movement of a robotic couch. The SDI approach to movements rotating around a predefined isocenter, referred to as a GeoIso, instead of a mechanical pivot point was developed by the robot automation industry. With robotic couch-sag corrections for weight load in a traditional SDI approach, movements could be accurately executed for a GeoIso located within a 500 mm cubic volume on the couch for treatments. The accuracy of SDI movement was investigated using the OTPS. The GeoIso was assumed to align with the proton beam isocenter (RadIso) for gantry at the reference angle. However, the misalignment between GeoIso and RadIso was quantitatively investigated by measuring the displacements at various couch angles for a target placed at the RadIso at an initial couch angle. When circular target displacements occur on a plane, a relative isocenter shift (RIS) correction could be applied in the SDI movement to minimize target displacements. Target displacements at a fixed gantry angle without and with RIS correction were measured for 12 robotic couches. Target displacements for various gantry angles were performed on three couches in gantry rooms to study the gantry-induced RadIso shift. The RIS correction can also be applied for the RadIso shift. A new SDI approach incorporating the RIS correction with the couch sag is described in this study. In parallel, the accuracy of SDI translation movements for various weight loads of patients on the couch was investigated during positioning of patients for proton prostate treatments. For a fixed gantry angle, measured target displacements without RIS correction for couch rotations in the horizontal plane varied from 4 to 20 mm. However, measured displacements perpendicular to couch rotation plane were about 2 mm for all couches. Extracted misalignments of GeoIso and RadIso in

  12. Utilization of optical tracking to validate a software-driven isocentric approach to robotic couch movements for proton radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Hsi, Wen C., E-mail: Wen.Hsi@Mclaren.org, E-mail: Wenchien.hsi@sphic.org.cn; Zeidan, Omar A., E-mail: omar.zeidan@orlandohealth.com [ProCure Proton Therapy Center, Oklahoma City, Oklahoma 73142 (United States); Law, Aaron; Schreuder, Andreas N., E-mail: niek.schreuder@provisionhp.com [ProCure Training and Development Center, Bloomington, Indiana 47404 (United States)

    2014-08-15

    Purpose: An optical tracking and positioning system (OTPS) was developed to validate the software-driven isocentric (SDI) approach to control the six-degrees-of-freedom movement of a robotic couch. Methods: The SDI approach to movements rotating around a predefined isocenter, referred to as a GeoIso, instead of a mechanical pivot point was developed by the robot automation industry. With robotic couch-sag corrections for weight load in a traditional SDI approach, movements could be accurately executed for a GeoIso located within a 500 mm cubic volume on the couch for treatments. The accuracy of SDI movement was investigated using the OTPS. The GeoIso was assumed to align with the proton beam isocenter (RadIso) for gantry at the reference angle. However, the misalignment between GeoIso and RadIso was quantitatively investigated by measuring the displacements at various couch angles for a target placed at the RadIso at an initial couch angle. When circular target displacements occur on a plane, a relative isocenter shift (RIS) correction could be applied in the SDI movement to minimize target displacements. Target displacements at a fixed gantry angle without and with RIS correction were measured for 12 robotic couches. Target displacements for various gantry angles were performed on three couches in gantry rooms to study the gantry-induced RadIso shift. The RIS correction can also be applied for the RadIso shift. A new SDI approach incorporating the RIS correction with the couch sag is described in this study. In parallel, the accuracy of SDI translation movements for various weight loads of patients on the couch was investigated during positioning of patients for proton prostate treatments. Results: For a fixed gantry angle, measured target displacements without RIS correction for couch rotations in the horizontal plane varied from 4 to 20 mm. However, measured displacements perpendicular to couch rotation plane were about 2 mm for all couches. Extracted

  13. Development of a QA Phantom for online image registration and resultant couch shifts

    International Nuclear Information System (INIS)

    Arumugam, S.; Jameson, M.G.; Holloway, L.C.

    2010-01-01

    Full text: Purpose Recently our centre purchased an Elekta-Synergy accelerator with kV-CBCT and a hexapod couch attachment. This system allows six degrees of freedom for couch lOp shifts, based on registration of on line imaging. We designed and built a phantom in our centre to test the accuracy and precision of this system. The goal of this project was to investigate the accuracy and practical utilisation of this phantom. Method The phantom was constructed from perspex sheets and high density dental putty (Fig. I). Five high density regions (three small regions to simulate prostate seeds and two larger regions to simulate boney anatomy) were incorporated to test the manual and automatic registrations within the software. The phantom was utilised to test the accuracy and precision of repositioning with the hexapod couch and imaging system. To achieve this, the phantom was placed on the couch at known orientations and the shifts were quantified using the registration of verification and reference image data sets. True shifts and those predicted by the software were compared. Results The geometrical accuracy of the phantom was verified with measurements of the CT scan to be with I mm of the intended geometry. The image registration and resultant couch shifts were found to be accurate within I mm and 0.5 degrees. The phantom was found to be practical and easy to use. Conclusion The presented phantom provides a less expensive and effective alternative to commercially available systems for verifying imaging registration and corresponding six degrees of freedom couch shifts. (author)

  14. Head support to be attached to a Mk1 treatment couch

    International Nuclear Information System (INIS)

    Hannappel, L.

    1984-01-01

    The author presents a head support which can be attached to the bottom-end of the treatment couch Mkl (AECL teletherapy units). This head support facilitates the reproducible position of patients in case of irradiations of the skull and irradiations of head and neck and makes only possible to apply all techniques of irradiation of the skull and of head and neck. By means of suitable connection elements, the head support can also be used with the treatment couch of other manufacturers. (orig.) [de

  15. SU-F-T-298: The Impact of Modeling the Treatment Couch On Patient Specific VMAT QA

    Energy Technology Data Exchange (ETDEWEB)

    Gelover, E; Dalhart, A; Hyer, D [University of Iowa Hospitals & Clinics, Iowa City, IA (United States)

    2016-06-15

    Purpose: The aim of this work is to quantify the impact of modeling the treatment couch on the passing rate of ion chamber measurements during VMAT quality assurance. Methods: For the initial characterization, attenuation and surface dose measurements were performed following the guidelines of TG-176 for the Civco Universal couch top using an Elekta VersaHD accelerator at an energy of 6 MV. A simulation CT was performed to aid in the creation of contours for representing the shape and size of the couch top in the treatment planning system (TPS). A uniform value of density for the couch wall was determined by comparing the ratios of ion chamber measurements made in a 30×30×11 cm3 water phantom with the TPS dose values of a plan with the same geometry. At our institution, patient specific quality assurance is performed using a Sun Nuclear ArcCheck with a multi-plug for chamber measurements, a 0.125cc PTW TN31010 chamber, and a Sun Nuclear 1010 electrometer. Ten VMAT plans were transferred into the phantom geometry created in the TPS with two settings: with and without the couch. The chamber measurements were compared to both treatment plans. Results: A maximum attenuation of 3.6% was observed when the gantry angle was set to 120 and 240 degrees, passing obliquely through the couch. A uniform density of 0.6 g/cm3 for the couch wall was determined in the TPS by comparison with measured data. The VMAT ion chamber measurement/plan ratios systematically improved by 1.79% ±0.53% for all patients when the couch was included in the calculation. Conclusion: The attenuation and surface dose changes produced by the Civco couch can generate observable dose difference in VMAT plans. Including a couch model in the phantom plan used for patient specific VMAT QA can improve the ionization chamber agreement by up to ∼2%.

  16. SU-E-T-315: Dosimetric Effects of Couch Top Shift On VMAT Delivery in Absence of Indexing

    Energy Technology Data Exchange (ETDEWEB)

    Islam, M; Jin, H; Ferguson, S; Ahmad, S [Oklahoma Univ. Health Science Ctr., Oklahoma City, OK (United States)

    2015-06-15

    Purpose: To investigate dosimetric effects of couch top shift for volumetric-modulated arc therapy (VMAT) in absence of indexing of immobilization devices. Methods: A total of twelve VMAT treatment plans were selected from three regions (lung, abdomen, and pelvis) to account for the variation of the patient position relative to the couch top. The treatment plans were generated using the Varian Eclipse system. A pinpoint ionization chamber (PTW TN31014) was placed at the center of 16-cm solid water phantom and the dose was delivered using the Varian TrueBeam STx with BrainLAB ExacTrac couch top. To simulate the day-to-day variation of the patient position relative to couch top, the couch top was laterally shifted up to 50 mm, with an increment of 5 mm from 0 to 20 mm; and of 10 mm afterwards, and the phantom was moved back to 0 cm shift for measurement. The dose was also delivered using a Varian tennis racket grid insert at 0 cm shift to simulate the absence of couch top. The treatment plans were delivered with 6, 10, and 15 MV photons using the same leaf sequencing to investigate the energy dependence of couch top shift. The dose difference was normalized to 0 cm shift for the regular couch top for comparison. Results: The percent difference of dose was found to increase with lateral shift for all energies; however, the average differences were close to 0% and the maximum difference was within 1% along the lateral shifts. The differences with the absence of couch top were 2.2±0.5% (6MV), 1.7±0.3% (10MV), and 1.6±0.2% (15MV), respectively. Conclusion: The inclusion of couch top is recommended in treatment planning to minimize the dosimetric uncertainty between calculated and delivered dose even in absence of indexing of immobilization devices in VMAT delivery.

  17. The Return of the Freudian Couch®: Managing Affectivity through Technologies of Comfort

    Science.gov (United States)

    Juelskjaer, Malou; Staunaes, Dorthe; Ratner, Helene

    2013-01-01

    This article explores how the affective "set-up" of Freud's legendary couch has been exported into modern education relations. The so-called psy-sciences from pedagogy, psychology, and psychiatry have informed self-management in school. Managing self-management has a material-affective dimension. Through affective encounters with the…

  18. TU-D-9A-01: TG176: Dosimetric Effects of Couch Tops and Immobilization Devices

    International Nuclear Information System (INIS)

    Olch, A

    2014-01-01

    The dosimetric impact from devices external to the patient is a complex combination of increased skin dose, reduced tumor dose, and altered dose distribution. Although small monitor unit or dose corrections are routinely made for blocking trays, ion chamber correction factors, or tissue inhomogeneities, the dose perturbation of the treatment couch top or immobilization devices are often overlooked. These devices also increase surface dose, an effect which is also often ignored or underestimated. These concerns have grown recently due to the increased use of monolithic carbon fiber couch tops which are optimal for imaging for patient position verification but cause attenuation and increased surface dose compared to the ‘tennis racket’ style couch top they often replace. Also, arc delivery techniques have replaced stationary gantry techniques which cause a greater fraction of the dose to be delivered from posterior angles. A host of immobilization devices are available and used to increase patient positioning reproducibility, and these also have attenuation and skin dose implications which are often ignored. This report of Task Group 176 serves to present a survey of published data that illustrates the magnitude of the dosimetric effects of a wide range of devices external to the patient. The report also provides methods for modeling couch tops in treatment planning systems so the physicist can accurately compute the dosimetric effects for indexed patient treatments. Both photon and proton beams are considered. A discussion on avoidance of high density structures during beam planning is also provided. An important aspect of this report are the recommendations we make to clinical physicists, treatment planning system vendors, and device vendors on how to make measurements of skin dose and attenuation, how to report these values, and for the vendors, an appeal is made to work together to provide accurate couch top models in planning systems. Learning Objectives

  19. WE-G-213CD-06: Implementation of Real-Time Tumor Tracking Using Robotic Couch.

    Science.gov (United States)

    Buzurovic, I; Yu, Y; Podder, T

    2012-06-01

    The purpose of this study was to present a novel method for real- time tumor tracking using a commercially available robotic treatment couch, and to evaluate tumor tracking accuracy. Commercially available robotic couches are capable of positioning patients with high level of accuracy; however, currently there is no provision for compensating tumor motion using these systems. Elekta's existing commercial couch (PreciseTM Table) was used without changing its design. To establish the real-time couch motion for tracking, a novel control system was developed and implemented. The tabletop could be moved in horizontal plane (laterally and longitudinally) using two Maxon-24V motors with gearbox combination. Vertical motion was obtained using robust 70V-Rockwell Automation motor. For vertical motor position sensing, we used Model 755A-Accu- Coder encoder. Two Baumer-ITD_01_4mm shaft encoders were used for the lateral and longitudinal motions of the couch. Motors were connected to the Advance Motion Controls (AMC) amplifiers: for the vertical motion, motor AMC-20A20-INV amplifier was used, and two AMC-Z6A8 amplifiers were applied for the lateral and longitudinal couch motions. The Galil DMC-4133 controller was connected to standard PC computer using USB port. The system had two independent power supplies: Galil PSR-12- 24-12A, 24vdc power supply with diodes for controller and 24vdc motors and amplifiers, and Galil-PS300W72 72vdc power supply for vertical motion. Control algorithms were developed for position and velocity adjustment. The system was tested for real-time tracking in the range of 50mm in all 3 directions (superior-inferior, lateral, anterior- posterior). Accuracies were 0.15, 0.20, and 0.18mm, respectively. Repeatability of the desired motion was within ± 0.2mm. Experimental results of couch tracking show feasibility of real-time tumor tracking with high level of accuracy (within sub-millimeter range). This tracking technique potentially offers a simple and

  20. Comparison of multi-leaf collimator tracking and treatment-couch tracking during stereotactic body radiation therapy of prostate cancer.

    Science.gov (United States)

    Ehrbar, Stefanie; Schmid, Simon; Jöhl, Alexander; Klöck, Stephan; Guckenberger, Matthias; Riesterer, Oliver; Tanadini-Lang, Stephanie

    2017-12-01

    Motion mitigation during prostate stereotactic body radiation therapy (SBRT) ensures optimal target coverage while reducing the risk of overdosage of nearby organs. The geometrical and dosimetrical performance of motion mitigation with the multileaf-collimator (MLC tracking) or the treatment couch (couch tracking) were compared. For ten prostate patients, SBRT treatment plans with integrated boosts were prepared using volumetric modulated arc technique. For the geometrical evaluation, a lead sphere at the beam isocenter was moved according to five prostate motion curves (i) without mitigation, (ii) with MLC tracking or (iii) with couch tracking. During irradiation, MV images were taken and the over-/underexposed areas were evaluated. For the dosimetrical evaluation, the plans were applied to a dosimetric phantom. Dose distributions with and without mitigation were evaluated inside the target structure and organs at risk. The median over-/underexposed area was reduced significantly from 2.02cm 2 without mitigation to 1.00cm 2 and 0.45cm 2 with MLC and couch tracking. Closest dosimetrical agreement to the static references was achieved with couch tracking. MLC and couch tracking at a conventional linear accelerator significantly improved the accuracy of prostate SBRT in the presence of motion, whereby couch tracking showed slightly better performance than MLC tracking. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Analyse du developpement de la couche limite dynamique a l'entree ...

    African Journals Online (AJOL)

    In this study the problem of boundary-layer at the entrance of a horizontal cylindrical channel bounded by a porous medium is solved analytically. The porous medium saturated by an incompressible fluid is anisotropic in permeability whose principal axes are oriented with respect to terrestrial gravity field. The thickness of ...

  2. Simulation de la couche limite hypersonique autour d'un corps ...

    African Journals Online (AJOL)

    [7]. C.D. Scott, Wall Boundary. Equations with slip and Catalysis for. Multicomponent Gas Flows, Technical. Report TM-X-58111, NASA , 1973. [8]. C.R. Wilke , A Viscosity Equation for Gas Mixtures, The third Joint of. Chemical Physics, 1950, Vol.18, issu.4. [9]. J.L. Shin, J.N Moss, A.L.. Simmonds, Viscous shock layer heating.

  3. [Method for evaluating the positional accuracy of a six-degrees-of-freedom radiotherapy couch using high definition digital cameras].

    Science.gov (United States)

    Takemura, Akihiro; Ueda, Shinichi; Noto, Kimiya; Kurata, Yuichi; Shoji, Saori

    2011-01-01

    In this study, we proposed and evaluated a positional accuracy assessment method with two high-resolution digital cameras for add-on six-degrees-of-freedom radiotherapy (6D) couches. Two high resolution digital cameras (D5000, Nikon Co.) were used in this accuracy assessment method. These cameras were placed on two orthogonal axes of a linear accelerator (LINAC) coordinate system and focused on the isocenter of the LINAC. Pictures of a needle that was fixed on the 6D couch were taken by the cameras during couch motions of translation and rotation of each axis. The coordinates of the needle in the pictures were obtained using manual measurement, and the coordinate error of the needle was calculated. The accuracy of a HexaPOD evo (Elekta AB, Sweden) was evaluated using this method. All of the mean values of the X, Y, and Z coordinate errors in the translation tests were within ±0.1 mm. However, the standard deviation of the Z coordinate errors in the Z translation test was 0.24 mm, which is higher than the others. In the X rotation test, we found that the X coordinate of the rotational origin of the 6D couch was shifted. We proposed an accuracy assessment method for a 6D couch. The method was able to evaluate the accuracy of the motion of only the 6D couch and revealed the deviation of the origin of the couch rotation. This accuracy assessment method is effective for evaluating add-on 6D couch positioning.

  4. Writing and querying MapReduce views in CouchDB

    CERN Document Server

    Holt, Bradley

    2011-01-01

    If you want to use CouchDB to support real-world applications, you'll need to create MapReduce views that let you query this document-oriented database for meaningful data. With this short and concise ebook, you'll learn how to create a variety of MapReduce views to help you query and aggregate data in CouchDB's large, distributed datasets. You'll get step-by-step instructions and lots of sample code to create and explore several MapReduce views through the course of the book, using an example database you construct. To work with these different views, you'll learn how to use the Futon web a

  5. From ISIS to CouchDB: Databases and Data Models for Bibliographic Records

    Directory of Open Access Journals (Sweden)

    Luciano Ramalho

    2011-04-01

    Full Text Available For decades bibliographic data has been stored in non-relational databases, and thousands of libraries in developing countries still use ISIS databases to run their OPACs. Fast forward to 2010 and the NoSQL movement has shown that non-relational databases are good enough for Google, Amazon.com and Facebook. Meanwhile, several Open Source NoSQL systems have appeared. This paper discusses the data model of one class of NoSQL products, semistructured, document-oriented databases exemplified by Apache CouchDB and MongoDB, and why they are well-suited to collective cataloging applications. Also shown are the methods, tools, and scripts used to convert, from ISIS to CouchDB, bibliographic records of LILACS, a key Latin American and Caribbean health sciences index operated by the Pan-American Health Organization.

  6. Étude des couches MAC dédiées à l'UWB

    OpenAIRE

    Fofana, Nezo Ibrahim; Van den Bossche, Adrien; Val, Thierry

    2014-01-01

    National audience; La norme IEEE 802.15.4a UWB offre un moyen de communication adapté aux environnements où la localisation de noeuds mobiles par mesure de temps de vol est nécessaire, en particulier pour ses capacités à obtenir une grande précision de mesure de distance entre deux noeuds communicants. La couche physique basée sur l'hyper étalement de spectre présente des caractéristiques originales qu'il est nécessaire de prendre en compte pour proposer une couche d'accès au médium la plus a...

  7. Poster — Thur Eve — 33: The Influence of a Modeled Treatment Couch on Dose Distributions During IMRT and RapidArc Treatment Delivery

    International Nuclear Information System (INIS)

    Aldosary, Ghada; Nobah, Ahmad; Al-Zorkani, Faisal; Moftah, Belal; Devic, Slobodan

    2014-01-01

    Treatment couches have been known to perturb dose delivery in patients. This effect is most pronounced in techniques such as IMRT and RapidArc. Although modern treatment planning systems (TPS) include data for a “default” treatment couch, actual couches are not manufactured identically. Thus, variations in their Hounsfield Unit (HU) values may exist. This study demonstrates a practical and simple method of acquiring reliable HU data for any treatment couch. We also investigate the effects of both the default and modeled treatment couches on absorbed dose. Experimental verifications show that by neglecting to incorporate the treatment couch in the TPS, dose differences of up to 9.5% and 7.3% were present for 4 MV and 10 MV photon beams, respectively. Furthermore, a clinical study based on a cohort of 20 RapidArc and IMRT (brain, pelvis and abdominal) cases is performed. 2D dose distributions show that without the couch in the planning phase, differences ≤ 4.6% and 5.9% for RapidArc and IMRT cases are present for the same cases that the default couch was added to. Additionally, in comparison to the default couch, employing the modeled couch in the calculation process influences dose distributions by ≤ 2.7% and 8% for RapidArc and IMRT cases, respectively. This result was found to be site specific; where an accurate couch proves to be preferable for IMRT brain plans. As such, adding the couch during dose calculation decreases dose calculation errors, and a precisely modeled treatment couch offers higher dose delivery accuracy for brain treatment using IMRT

  8. Effet magnéto-optique et optique des couches minces à base de ...

    African Journals Online (AJOL)

    Cette étude a pour but la mesure des effets magnéto-optiques (rotation Faraday) en fonction du champ magnétique appliqué et en fonction de la longueur d'onde, ainsi que la mesure de la transmittance (effet optique) des couches minces à base de ferrite de cobalt. Les résultats montrent une forte rotation Faraday ...

  9. SU-F-J-37: Commissioning a Six Degree of Freedom Couch

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, D; Lam, K; Bredfeldt, J; Covington, E [University of Michigan Hospital and Health Systems, Ann Arbor, MI (United States)

    2016-06-15

    Purpose: The proper operation of a six degree of freedom couch (6DOFC) to position a patient for treatment requires that a number systems on the treatment unit work together correctly. Commissioning a 6DOFC requires not only the commissioning of each separate system but also commissioning the interactions between the systems. Methods: To commission a 6DOFC, we tested the resolvers that readout the linear and angular positions; the orthogonality of the axes of the laser positioning system, the imaging system, the gantry and the couch as well as their relationship to each other. An automated Winston-Lutz test was used verify the coincidence of the origins of the laser system, imaging system and treatment unit. The IsoCal phantom was used to verify the consistency of axes orientations between systems. The operation of the couch and imaging system was verified under simulated load conditions and an end to end test was performed to verify correct operation of the system. Results: The tests on the couch resolvers, orthogonality and coincidence of the axes of each system were successfully completed and showed excellent agreement. The automated Winston-Lutz test showed that the maximum displacement of the center of the radiation field with respect to the isocenter was <0.6 mm (radius) at isocenter. The analysis of the IsoCal phantom showed that the maximum variation of the radiation field with respect to known locations in the phantom was ∼0.9 mm for all the BBs in the phantom. Load tests showed maximum errors of 1 mm. Conclusion: We tested all system associated with the 6DOFC and found the uncertainty due to imaging was <.9mm and the uncertainty due to loading ∼1 mm, resulting in a total error of ∼1.4 mm.

  10. CONTRIBUTION A L’ETUDE DES PROPRIETES OPTIQUES DES COUCHES MINCES DE SILICIUM AMORPHE HYDROGENE

    Directory of Open Access Journals (Sweden)

    K MELLASSI

    2001-06-01

    Full Text Available Le présent travail est essentiellement consacré à l'étude de quelques propriétés optiques de couches minces de silicium amorphe hydrogéné (a-Si:H préparées par la technique de pulvérisation cathodique radiofréquence. Il s'agit précisément d'examiner séparément l'influence de la pression partielle d'hydrogène lors du dépôt et l'effet d'un recuit thermique classique post-dépôt sur les principales grandeurs optiques des couches telles que l'indice de réfraction, le gap optique et l'énergie d'Urbach. On montre que les faibles pressions d'hydrogène permettent une saturation des liaisons pendantes dans le matériau, alors que les fortes doses conduisent à la création de nouveaux défauts. On montre aussi qu'un recuit thermique à température moyenne permet une nette amélioration de la qualité structurale des couches déposées.

  11. Virtual couch shift (VCS): accounting for patient translation and rotation by online IMRT re-optimization

    International Nuclear Information System (INIS)

    Bol, G H; Lagendijk, J J W; Raaymakers, B W

    2013-01-01

    When delivering conventional intensity modulated radiotherapy (IMRT), discrepancies between the pre-treatment CT/MRI/PET based patient geometry and the daily patient geometry are minimized by performing couch translations and/or small rotations. However, full compensation of, in particular, rotations is usually not possible. In this paper, we introduce an online ‘virtual couch shift (VCS)’: we translate and/or rotate the pre-treatment dose distribution to compensate for the changes in patient anatomy and generate a new plan which delivers the transformed dose distribution automatically. We show for a phantom and a cervical cancer patient case that VCS accounts for both translations and large rotations equally well in terms of DVH results and 2%/2 mm γ analyses and when the various aspects of the clinical workflow can be implemented successfully, VCS can potentially outperform physical couch translations and/or rotations. This work is performed in the context of our hybrid 1.5 T MRI linear accelerator, which can provide translations and rotations but also deformations of the anatomy. The VCS is the first step toward compensating all of these anatomical changes by online re-optimization of the IMRT dose distribution. (paper)

  12. The effect of high-resolution fluences by couch shift between arcs on the VMAT plan quality

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung In; Park, So Yeon; Choi, Chang Heon; Park, Jong Min [Dept. of Radiation Oncology, Seoul National University Hospital, Seoul (Korea, Republic of); Wu, Hong Gyun [Dept. of Radiation Oncology, Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2016-12-15

    Various studies have demonstrated the dosimetric advantages of multi-leaf collimators (MLCs) with fine leaf widths for both intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), which can generate high resolution fluences. However, a practical disadvantage of MLCs with fine leaf widths is a limited field length in the longitudinal direction. This is because the numbers of leaves and motors are limited due to spatial constraints within the treatment head. We propose an alternative way to generate high resolution fluences of a VMAT plan without MLCs with fine leaf widths for the treatment of large H and N target volumes. With the Millennium 120 MLC with inner leaf widths of 5 mm, we simulate 2.5 mm inner leaf widths by a 2.5 mm shift of the patient couch in the longitudinal direction between arcs. In this way, we acquire not only the improved dosimetric effects of the MLCs with fine leaf widths, but also the full coverage of the H and N target volumes. The HAS plan was better than the others in terms of normal tissue sparing and plan efficiency.

  13. SU-F-J-125: Effects of Couch Position Variability On Dosimetric Accuracy with An MRI-Guided Co-60 Radiation Therapy Machine

    Energy Technology Data Exchange (ETDEWEB)

    Chow, P; Thomas, D; Agazaryan, N; Cao, M; Low, D; Yang, Y; Lamb, J [UCLA, Los Angeles, CA (United States)

    2016-06-15

    Purpose: Magnetic resonance imaging (MRI) guidance in radiation therapy brings real-time imaging and adaptive planning into the treatment vault where it can account for interfraction and intrafraction movement of soft tissue. The only commercially-available MRI-guided radiation therapy device is a three-head 60Co and MRI system with an integrated treatment planning system (TPS). An up to 20% attenuation of the beam by the couch is well modeled in the TPS. However, variations in the patient’s day-to-day position introduce discrepancies in the actual couch position relative its location as modeled in the treatment plan. For this reason, our institution avoids plans with beams that pass through or near the couch edges. This study looks at plans without restriction on beam angles and investigates the effects of couch shift by simulating shifts of the couch relative to the patient, in order to determine whether couch edge avoidance restrictions can be lifted. Methods: A total of 27 plans from 23 patients were investigated. Couch shifts of 1 and 2 cm were introduced in combinations of lateral and vertical direction to simulate variations in patient positioning on the couch giving 16 shifted plans per reference plan. The shift values of 1 and 2 cm were based on shifts recorded in 320 treatment fractions. Results: Measured couch attenuation versus TPS modeled agreed within 2.1%. Planning Target Volume (PTV) D95 changed less than 1% for 1 and 2 cm couch shifts in only the x-direction and less than 3% for all directions. Conclusion: The dosimetry of all plans with shifts up to ±2 cm was within reasonable clinical tolerances. Robustness of a plan to couch shifts can be tested in the TPS. Inclusion of beams traversing the couch edges should be considered if an improvement in plan quality or delivery time can be achieved.

  14. Evaluation of accuracy about 2D vs 3D real-time position management system based on couch rotation when non-coplanar respiratory gated radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Kyung Tae; Kim, Jung Soo [Dongnam Health University, Suwon (Korea, Republic of); Sim, Hyun Sun [College of Health Sciences, Korea University, Seoul (Korea, Republic of); Min, Jung Whan [Shingu University College, Sungnam (Korea, Republic of); Son, Soon Yong [Wonkwang Health Science University, Iksan (Korea, Republic of); Han, Dong Kyoon [College of Health Sciences, EulJi University, Daejeon (Korea, Republic of)

    2016-12-15

    Because of non-coplanar therapy with couch rotation in respiratory gated radiation therapy, the recognition of marker movement due to the change in the distance between the infrared camera and the marker due to the rotation of the couch is called RPM (Real-time The purpose of this paper is to evaluate the accuracy of motion reflections (baseline changes) of 2D gating configuration (two dot marker block) and 3D gating configuration (six dot marker block). The motion was measured by varying the couch angle in the clockwise and counterclockwise directions by 10° in the 2D gating configuration. In the 3D gating configuration, the couch angle was changed by 10° in the clockwise direction and compared with the baseline at the reference 0°. The reference amplitude was 1.173 to 1.165, the couch angle at 20° was 1.132, and the couch angle at 1.0° was 1.083. At 350° counterclockwise, the reference amplitude was 1.168 to 1.157, the couch angle at 340° was 1.124, and the couch angle at 330° was 1.079. In this study, the phantom is used to quantitatively evaluate the value of the amplitude according to couch change.

  15. Precision evaluation of the treatment that used coordinates confirmation of couch in case of two forgets adjoined

    International Nuclear Information System (INIS)

    Seo, Jeong Min; Jeong, Cheon Young; Park, Young Hwan; Song, Ki Won

    2003-01-01

    Confirming an error to be able to break out in a method to move couch manually while operator sees the skin marks on patient in case of curing head who got 2 targets adjoined, so we analyze coordinates price of couch, evaluate reproducibility and precision of change movements between targets. In radiotherapy, for confirming errors in manual movements by operators by exchanging between two targets to treat patient head, we read coordinates price(vertical, longitudinal, lateral three directions of couch) shown on a monitor of LINAC( CL 2100, Varian, USA) in order to evaluate accuracy about the length that moved in time for moving couch manually. After reading movement length of coordinates recorded in three directions of all treatment, we compared distance between targets recorded in RTP(Pinnacle, ADAC, USA) with reading coordinates price of couch, setting actually done the same patient for ten times, coordinates were recorded, treated for evaluating averages and degrees of errors and standard deviations. In method to confirm skin marks of patient by operators' view and to move couch manually, average standard deviations of movements between two targets are vertical 1.4 mm, longitudinal 0.9 mm, lateral 2.2 mm in each direction. As for the error in straight dimension, it is about 3.6 mm averages and 5.1 mm maximum. The average of errors in each directions was vertical 1mm, longitudinal 0.7 mm, lateral 2.7 mm. The greatest error broke out in lateral direction with 25% of all cases ; to exceed an error average. If operators moved manually couch for changing target points, errors about 3.6 mm average degrees occur. It is important that operators confirm the errors prices of actual couch coordinates for asking a correct movement between the targets adjoined each other ; in case of treatment demanding high precision like 3D conformal therapy or IMRT. Therefore, if we apply couch coordinates confirmation to reproducibility and to precision evaluation of treatment, it

  16. Étude de la microstructure de couches minces par diffraction des rayons X : description analytique des profils de raie

    Science.gov (United States)

    Boulle, A.; Guinebretière, R.; Dauger, A.

    2004-11-01

    Nous proposons un modèle cinématique permettant de décrire de façon analytique les profils de raie de diffraction des rayons X de couches minces épitaxiées. Comparé aux modèles analytiques existant, celui-ci permet de prendre en compte plusieurs types de défauts simultanément, notamment la rugosité du substrat, celle de la surface de la couche, et les fluctuations aléatoires (cumulatives ou non) de distance interréticulaire. Cette description peut s'appliquer aux cas de couches minces nanométriques (de quelques dizaines de nanomètres à quelques centaines de nanomètres) ainsi qu'aux couches ultra-minces (quelques Ångstroms). Les profils de raie sont affectés différemment selon la nature des défauts présents, ce qui permet d'envisager l'application de ce modèle pour la détermination quantitative des propriétés microstructurales des couches de façon simple et routinière.

  17. Megavoltage photon beam attenuation by carbon fiber couch tops and its prediction using correction factors

    International Nuclear Information System (INIS)

    Hayashi, Naoki; Shibamoto, Yuta; Obata, Yasunori; Kimura, Takashi; Nakazawa, Hisato; Hagiwara, Masahiro; Hashizume, Chisa I.; Mori, Yoshimasa; Kobayashi, Tatsuya

    2010-01-01

    The purpose of this study was to evaluate the effect of megavoltage photon beam attenuation (PBA) by couch tops and to propose a method for correction of PBA. Four series of phantom measurements were carried out. First, PBA by the exact couch top (ECT, Varian) and Imaging Couch Top (ICT, BrainLAB) was evaluated using a water-equivalent phantom. Second, PBA by Type-S system (Med-Tec), ECT and ICT was compared with a spherical phantom. Third, percentage depth dose (PDD) after passing through ICT was measured to compare with control data of PDD. Forth, the gantry angle dependency of PBA by ICT was evaluated. Then, an equation for PBA correction was elaborated and correction factors for PBA at isocenter were obtained. Finally, this method was applied to a patient with hepatoma. PBA of perpendicular beams by ICT was 4.7% on average. With the increase in field size, the measured values became higher. PBA by ICT was greater than that by Type-S system and ECT. PBA increased significantly as the angle of incidence increased, ranging from 4.3% at 180 deg to 11.2% at 120 deg. Calculated doses obtained by the equation and correction factors agreed quite well with the measured doses between 120 deg and 180 deg of angles of incidence. Also in the patient, PBA by ICT was corrected quite well by the equation and correction factors. In conclusion, PBA and its gantry angle dependency by ICT were observed. This simple method using the equation and correction factors appeared useful to correct the isocenter dose when the PBA effect cannot be corrected by a treatment planning system. (author)

  18. Comportement à la corrosion de couches minces nano structurées ...

    African Journals Online (AJOL)

    Nous avons élaboré par pulvérisation cathodique magnétron DC des couches minces nano structurées en alliages de fer–Silicium Fe1-xSix. Le comportement à la corrosion en milieu chloruré (H2O - 3,2 g/l NaCl) a été analysé. Nous avons constaté que les meilleures performances électrochimiques sont obtenues pour les ...

  19. A Chimpanzee, 'Ham,' in the Biopack Couch for the MR-2 Flight

    Science.gov (United States)

    1961-01-01

    A three-year-old chimpanzee, named Ham, in the biopack couch for the MR-2 suborbital test flight. On January 31, 1961, a Mercury-Redstone launch from Cape Canaveral carried the chimpanzee 'Ham' over 640 kilometers down range in an arching trajectory that reached a peak of 254 kilometers above the Earth. The mission was successful and Ham performed his lever-pulling task well in response to the flashing light. NASA used chimpanzees and other primates to test the Mercury Capsule before launching the first American astronaut Alan Shepard in May 1961. The successful flight and recovery confirmed the soundness of the Mercury-Redstone systems.

  20. A feasibility study of using couch-based real time dosimetric device in external beam radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakar, Ramachandran; Cramb, Jim; Kron, Tomas [Physical Sciences, Peter MacCallum Cancer Centre, Locked Bag 1, A' Beckett Street, Victoria 8006 (Australia)

    2011-12-15

    Purpose: Measurement of actual dose delivered during radiotherapy treatment aids in checking the accuracy of dose delivered to the patient. In this study, a couch-based real time dosimetric device has been proposed to measure the exit or entrance dose to a patient during external beam radiotherapy. The utility and feasibility of such a device using a 2D array of diodes has been demonstrated. Methods: Two MAPCHECK devices: MAPCHECK (1175) and MAPCHECK 2 (both SunNuclear) were embedded in a foam block in the treatment couch of a Varian 21iX linear accelerator. The angular dependence of the detector response for both devices was studied before implementing the MAPCHECKs for experimental purposes. An Alderson Rando head phantom was scanned with the MAPCHECK and MAPCHECK 2 devices separately and four different treatment plans were generated with target volumes at three different positions simulating typical clinical situations. The analytical anisotropic algorithm (AAA) was used to compute the doses in an Eclipse treatment planning system (Varian Medical Systems). The Rando phantom with the MAPCHECK device was exposed in Clinac 21iX linear accelerator. The measured dose distribution was compared with the calculated dose distribution to check for the accuracy in dose delivery. Results: Measured and computed dose distribution were found to agree with more than 93% of pixels passing at 3% and 3 mm gamma criteria for all the treatment plans. The couch-based real time dosimetry system may also be applied for noncoplanar beams where electronic portal imaging device (EPID) is not practical to measure the dose. Other advantages include checking the beam stability during the patient treatment, performing routine morning quality assurance (QA) tests in the linear accelerator, and to perform pretreatment verification of intensity modulated radiation therapy (IMRT). One of the drawbacks of this system is that it cannot be used for measuring the dose at 90 deg. or 270 deg. gantry

  1. SU-F-T-424: Mitigation of Increased Surface Dose When Treating Through A Carbon Fiber Couch Top

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, E; Misgina, F [University of Kentucky, Lexington, KY (United States)

    2016-06-15

    Purpose: To study the effect of the Varian carbon fiber couch top on surface dose for patients being treated using single PA beams in the supine position and to identify simple methods for surface dose reduction. Methods: Measurements of surface dose were obtained in Solid Water phantoms using both a parallel plate ionization chamber (PTW Advanced Markus) and EBT2 Radiochromic films for both 6 and 10MV photons. All measurements were referenced to a depth considered a typical for PA Spine fields. Techniques used to reduce the surface dose included introducing an air standoff using Styrofoam sheets to suspend the phantom surface above the couch top and by adding a thin high Z scattering foil on the table surface. Surface doses were evaluated for typical field sizes, standoff heights, and various scattering materials. Comparisons were made to the surface dose obtainable when treating through a Varian Mylar covered tennis racket style couch top. Results: Dependence on typical spine field sizes was relatively minor. Dependence on air gap was much more significant. Surface doses decreased exponentially with increases in air standoff distance. Surface doses were reduced by approximately 50% for an air gap of 10cm and 40% for a 15cm air gap. Surface doses were reduced by an additional 15% by the addition of a 1mm Tin scattering foil. Conclusion: Using simple techniques, it is possible to reduce the surface dose when treating single PA fields through the Varian carbon fiber couch top. Surface doses can be reduced to levels observed when treating though transparent Mylar tops by adding about 15 cm of air gap. Further reductions are possible by adding thin scattering foils, such as Tin or Lead, on the couch surface. This is a low cost approach to reduce surface dose when using the Varian carbon fiber couch top.

  2. SU-F-T-424: Mitigation of Increased Surface Dose When Treating Through A Carbon Fiber Couch Top

    International Nuclear Information System (INIS)

    Johnson, E; Misgina, F

    2016-01-01

    Purpose: To study the effect of the Varian carbon fiber couch top on surface dose for patients being treated using single PA beams in the supine position and to identify simple methods for surface dose reduction. Methods: Measurements of surface dose were obtained in Solid Water phantoms using both a parallel plate ionization chamber (PTW Advanced Markus) and EBT2 Radiochromic films for both 6 and 10MV photons. All measurements were referenced to a depth considered a typical for PA Spine fields. Techniques used to reduce the surface dose included introducing an air standoff using Styrofoam sheets to suspend the phantom surface above the couch top and by adding a thin high Z scattering foil on the table surface. Surface doses were evaluated for typical field sizes, standoff heights, and various scattering materials. Comparisons were made to the surface dose obtainable when treating through a Varian Mylar covered tennis racket style couch top. Results: Dependence on typical spine field sizes was relatively minor. Dependence on air gap was much more significant. Surface doses decreased exponentially with increases in air standoff distance. Surface doses were reduced by approximately 50% for an air gap of 10cm and 40% for a 15cm air gap. Surface doses were reduced by an additional 15% by the addition of a 1mm Tin scattering foil. Conclusion: Using simple techniques, it is possible to reduce the surface dose when treating single PA fields through the Varian carbon fiber couch top. Surface doses can be reduced to levels observed when treating though transparent Mylar tops by adding about 15 cm of air gap. Further reductions are possible by adding thin scattering foils, such as Tin or Lead, on the couch surface. This is a low cost approach to reduce surface dose when using the Varian carbon fiber couch top.

  3. The Oculist's Eye: Connections between Cataract Couching, Anatomy, and Visual Theory in the Renaissance.

    Science.gov (United States)

    Baker, Tawrin

    2017-01-01

    We now know that cataract couching involves depressing an occluded crystalline lens to the bottom of the vitreous chamber, but from the time of Galen until the seventeenth-century cataracts were thought to be separate concretions arising between the crystalline lens and the pupil. From Antiquity through the Renaissance, the combination of visual theory in which the crystalline humor is the author of vision, and surgical experience—that couching cataracts restored some degree of sight—resulted in anatomists depicting a large space between the crystalline lens and the pupil. In the Renaissance, oculists—surgical specialists with little higher education or connections to learned surgery or medicine—overwhelmingly performed eye surgeries. This article examines how the experience and knowledge of oculists, of barber-surgeons, and of learned surgeons influenced one another on questions of anatomy, visual theory, and surgical experience. By analyzing the writings of the oculist George Bartisch (c. 1535–1607), the barber-surgeon Ambroise Paré (1510–1590), and the learned surgeon Hieronymus Fabricius ab Aquapendente (1533–1619), we see that the oculists’ understanding of the eye—an eye constructed out of the probing, tactile experience of eye surgery—slowly lost currency among the learned toward the beginning of the seventeenth century.

  4. Relax with CouchDB - Into the non-relational DBMS era of Bioinformatics

    Science.gov (United States)

    Manyam, Ganiraju; Payton, Michelle A.; Roth, Jack A.; Abruzzo, Lynne V.; Coombes, Kevin R.

    2012-01-01

    With the proliferation of high-throughput technologies, genome-level data analysis has become common in molecular biology. Bioinformaticians are developing extensive resources to annotate and mine biological features from high-throughput data. The underlying database management systems for most bioinformatics software are based on a relational model. Modern non-relational databases offer an alternative that has flexibility, scalability, and a non-rigid design schema. Moreover, with an accelerated development pace, non-relational databases like CouchDB can be ideal tools to construct bioinformatics utilities. We describe CouchDB by presenting three new bioinformatics resources: (a) geneSmash, which collates data from bioinformatics resources and provides automated gene-centric annotations, (b) drugBase, a database of drug-target interactions with a web interface powered by geneSmash, and (c) HapMap-CN, which provides a web interface to query copy number variations from three SNP-chip HapMap datasets. In addition to the web sites, all three systems can be accessed programmatically via web services. PMID:22609849

  5. Photosensibilite et ecriture de guides d'ondes dans les couches minces de verre de chalcogenures

    Science.gov (United States)

    Ho, Nicolas

    Les travaux presentes portent sur le developpement de dispositifs plans a base de verre de chalcogenures. Les verres de la famille As-S-Se sont utilises, et en particulier l'As2S 3. Les verres de chalcogenures sont des semiconducteurs amorphes qui sont tres interessants du point de vue de l'optique dans le proche infrarouge. La formation de guides auto-inscrits dans des couches minces d'As2S3 est etudiee experimentalement et numeriquement. La grande photosensibilite de ce verre mene a de nouveaux comportements de formation qui sont demontres. L'auto-inscription est aussi utilisee pour caracteriser la photosensibilite des couches minces de verre de chalcogenures dans le proche infrarouge, ce qui est un probleme majeur pour le developpement de dispositifs d'optique non lineaire a base de ces materiaux. Differentes caracteristiques de cette photosensibilite sont mises en evidences, comme la presence d'un seuil en intensite, entre autres. Finalement, une application des verres de chalcogenures est presentee: la fabrication de matrices de guides d'ondes (waveguide arrays) a l'aide d'une technique holographique novatrice.

  6. A practical method of modeling a treatment couch using cone-beam computed tomography for intensity-modulated radiation therapy and RapidArc treatment delivery

    International Nuclear Information System (INIS)

    Aldosary, Ghada; Nobah, Ahmad; Al-Zorkani, Faisal; Devic, Slobodan; Moftah, Belal

    2015-01-01

    The effect of a treatment couch on dose perturbation is not always fully considered in intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). In the course of inverse planning radiotherapy techniques, beam parameter optimization may change in the absence of the couch, causing errors in the calculated dose distributions. Although modern treatment planning systems (TPS) include data for the treatment couch components, they are not manufactured identically. Thus, variations in their Hounsfield unit (HU) values may exist. Moreover, a radiotherapy facility may wish to have a third-party custom tabletop installed that is not included by the TPS vendor. This study demonstrates a practical and simple method of acquiring reliable computed tomography (CT) data for the treatment couch and shows how the absorbed dose calculated with the modeled treatment couch can differ from that with the default treatment couch found in the TPS. We also experimentally verified that neglecting to incorporate the treatment couch completely in the treatment planning process might result in dose differences of up to 9.5% and 7.3% for 4-MV and 10-MV photon beams, respectively. Furthermore, 20 RapidArc and IMRT cases were used to quantify the change in calculated dose distributions caused by using either the default or modeled couch. From 2-dimensional (2D) ionization chamber array measurements, we observed large dose distribution differences between the measurements and calculations when the couch was omitted that varied according to the planning technique and anatomic site. Thus, incorporating the treatment couch in the dose calculation phase of treatment planning significantly decreases dose calculation errors.

  7. Attenuation measures of the BrainLAB imaging couch and validation on the treatment planning system Eclipse; Medidas de atenuacao da mesa BrainLAB imaging couch e validacao no sistema de planejamento Eclipse

    Energy Technology Data Exchange (ETDEWEB)

    Serante, Alexandre R., E-mail: alexandre.serante@gmail.com [Clinica de Radioterapia Inga, Nitero, RJ (Brazil); Goncalves, Joao G. [Instituto Oncologico, Juiz de Fora, MG (Brazil); Neves-Junior, Wellington F.P.; Leite, Joao Paulo S.; Haddad, Cecilia M.K. [Hospital Sirio-Libanes, Sao Paulo, SP (Brazil). Servico de Radioterapia. Sociedade Beneficente de Senhoras

    2015-12-15

    In this work, attenuation measurements were performed for the beams of energy 6 and 15MV for the couch table BrainLAB Imaging Couch, consisting of carbon fiber. The measurements were performed in the Linac Novalis-Tx (Varian) for 5 x 5 and 10 x 10 cm² field sizes, varying gantry positions. The measured data were compared with the values calculated with the treatment planning system Eclipse, calculated with the algorithm AAA, in order to validate the model of the couch included in your library. The highest attenuation for the field size of 10 x 10 cm² was 7,5% and 4,8% for the beams 6 and 15 MV, respectively. With the field size of 5 x 5 cm² the highest attenuation value was 8,1% and 5,3%, for the beams 6 and 15 MV, respectively. Both measured at gantry position 120 deg C. From the attenuation data measured with an ionization chamber, it was possible to modify the model of the couch in Eclipse to obtain the smallest difference between measured and predicted values by the TPS. (author)

  8. Propriétés structurales et électrochimiques de couches minces de V2O5 élaborées par dépôt chimique de couches atomiques en phase vapeur (ALCVD)

    Science.gov (United States)

    Mantoux, A.; Badot, J.-C.; Baffier, N.; Farcy, J.; Pereira-Ramos, J.-P.; Lincot, D.; Groult, H.

    2002-04-01

    Les couches minces de V2O5 ont été élaborées par dépôt chimique de couches atomiques en phase vapeur (ALCVD). La diffraction des rayons X a mis en évidence le phénomène d'orientation préférentielle selon l'axe cristallographique c de V2O5 déposé sur le substrat titane. La microscopie électronique à transmission a permis de visualiser un grain de V2O5 ainsi que l'interface avec le substrat. La spectroscopie de photoélectrons induits par rayons X a permis de montrer que les couches directement issues de la synthèse par ALCVD (sans recuit ultérieur) sont partiellement réduites, de l'ordre de 10 % de V^{4+} en surface. Les mesures électrochimiques ont montré que les couches minces de V2O5, obtenues sur le support titane, étaient de très bonne qualité en terme de réversibilité, de cyclabilité et de bilan faradique (0,92 F/mol pour un potentiel d'arrêt de 3 volts et 1,6 F/mol pour un potentiel d'arrêt de 2,2 volts vs Li/Li^+).

  9. Host status of barley to Puccinia coronata from couch grass and P. striiformis from wheat and brome

    Science.gov (United States)

    The pathogenicity and identity of a field sample (PcE) of crown rust fungus Puccinia coronata collected in Hungary on wild couch grass (Elytrigia repens) and of a field sample (Psb) of stripe rust (P. striiformis) collected in the Netherlands on California brome (Bromus carinatus) was studied. We fo...

  10. Host status of barley to Puccinia coronata from couch grass and P. striiformis from wheat and brome

    NARCIS (Netherlands)

    Niks, R.E.; Heyzen, van S.; Szabo, L.J.; Alemu, S.K.

    2013-01-01

    The pathogenicity and identity was studied of a field sample (PcE) of crown rust fungus Puccinia coronata collected in Hungary on wild couch grass (Elymus repens) and of a field sample (Psb) of stripe rust (P. striiformis) collected in the Netherlands on California brome (Bromus carinatus). We

  11. Clinical Evaluation of a Robotic 6-Degree of Freedom Treatment Couch for Frameless Radiosurgery

    International Nuclear Information System (INIS)

    Gevaert, Thierry; Verellen, Dirk; Engels, Benedikt; Depuydt, Tom; Heuninckx, Karina; Tournel, Koen; Duchateau, Michael; Reynders, Truus; De Ridder, Mark

    2012-01-01

    Purpose: To evaluate the added value of 6–degree of freedom (DOF) patient positioning with a robotic couch compared with 4DOF positioning for intracranial lesions and to estimate the immobilization characteristics of the BrainLAB frameless mask (BrainLAB AG, Feldkirchen, Germany), more specifically, the setup errors and intrafraction motion. Methods and Materials: We enrolled 40 patients with 66 brain metastases treated with frameless stereotactic radiosurgery and a 6DOF robotic couch. Patient positioning was performed with the BrainLAB ExacTrac stereoscopic X-ray system. Positioning results were collected before and after treatment to assess patient setup error and intrafraction motion. Existing treatment planning data were loaded and simulated for 4DOF positioning and compared with the 6DOF positioning. The clinical relevance was analyzed by means of the Paddick conformity index and the ratio of prescribed isodose volume covered with 4DOF to that obtained with the 6DOF positioning. Results: The mean three-dimensional setup error before 6DOF correction was 1.91 mm (SD, 1.25 mm). The rotational errors were larger in the longitudinal (mean, 0.23°; SD, 0.82°) direction compared with the lateral (mean, –0.09°; SD, 0.72°) and vertical (mean, –0.10°; SD, 1.03°) directions (p < 0.05). The mean three-dimensional intrafraction shift was 0.58 mm (SD, 0.42 mm). The mean intrafractional rotational errors were comparable for the vertical, longitudinal, and lateral directions: 0.01° (SD, 0.35°), 0.03° (SD, 0.31°), and –0.03° (SD, 0.33°), respectively. The mean conformity index decreased from 0.68 (SD, 0.08) (6DOF) to 0.59 (SD, 0.12) (4DOF) (p < 0.05). A loss of prescribed isodose coverage of 5% (SD, 0.08) was found with the 4DOF positioning (p < 0.05). Half a degree for longitudinal and lateral rotations can be identified as a threshold for coverage loss. Conclusions: With a mask immobilization, patient setup error and intrafraction motions need to be

  12. Clinical Evaluation of a Robotic 6-Degree of Freedom Treatment Couch for Frameless Radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Gevaert, Thierry, E-mail: thierry.gevaert@uzbrussel.be [Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels (Belgium); Verellen, Dirk; Engels, Benedikt; Depuydt, Tom; Heuninckx, Karina; Tournel, Koen; Duchateau, Michael; Reynders, Truus; De Ridder, Mark [Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels (Belgium)

    2012-05-01

    Purpose: To evaluate the added value of 6-degree of freedom (DOF) patient positioning with a robotic couch compared with 4DOF positioning for intracranial lesions and to estimate the immobilization characteristics of the BrainLAB frameless mask (BrainLAB AG, Feldkirchen, Germany), more specifically, the setup errors and intrafraction motion. Methods and Materials: We enrolled 40 patients with 66 brain metastases treated with frameless stereotactic radiosurgery and a 6DOF robotic couch. Patient positioning was performed with the BrainLAB ExacTrac stereoscopic X-ray system. Positioning results were collected before and after treatment to assess patient setup error and intrafraction motion. Existing treatment planning data were loaded and simulated for 4DOF positioning and compared with the 6DOF positioning. The clinical relevance was analyzed by means of the Paddick conformity index and the ratio of prescribed isodose volume covered with 4DOF to that obtained with the 6DOF positioning. Results: The mean three-dimensional setup error before 6DOF correction was 1.91 mm (SD, 1.25 mm). The rotational errors were larger in the longitudinal (mean, 0.23 Degree-Sign ; SD, 0.82 Degree-Sign ) direction compared with the lateral (mean, -0.09 Degree-Sign ; SD, 0.72 Degree-Sign ) and vertical (mean, -0.10 Degree-Sign ; SD, 1.03 Degree-Sign ) directions (p < 0.05). The mean three-dimensional intrafraction shift was 0.58 mm (SD, 0.42 mm). The mean intrafractional rotational errors were comparable for the vertical, longitudinal, and lateral directions: 0.01 Degree-Sign (SD, 0.35 Degree-Sign ), 0.03 Degree-Sign (SD, 0.31 Degree-Sign ), and -0.03 Degree-Sign (SD, 0.33 Degree-Sign ), respectively. The mean conformity index decreased from 0.68 (SD, 0.08) (6DOF) to 0.59 (SD, 0.12) (4DOF) (p < 0.05). A loss of prescribed isodose coverage of 5% (SD, 0.08) was found with the 4DOF positioning (p < 0.05). Half a degree for longitudinal and lateral rotations can be identified as a threshold

  13. [Phytopathogenic bacteria of couch-grass in the crops of wheat].

    Science.gov (United States)

    Iakovleva, L M; Patyka, V F; Gvozdiak, R I; Shcherbina, T N

    2009-01-01

    Bacterialdiseases of weeds in the crops of wheat on the fields of Kyiv and Vinnytsya regions of Ukraine Elytrigia repens (L.) Nevski Agropyrum repens L. were revealed. The following symptoms of bacterial affections: the leaves wither, oval or hatched necrotic spots on green leaves, necroses on the stalks, empty-ears, partial blackening of the ear axes, awns, caryopsises, scales, water-soaked or dark brown with violet shade spots on the rhizomes were found. During the vegetation period bacteria were isolated from the affected plants which caused pathological process in the couch-grass and wheat. The pathogenic bacteria were identified as Pseudomonas syringae, P. viridiflava, Pseudomonas sp., Erwinia carotovora pv. carotovora, Pantoea agglomerans, the part of yellow-pigmentary isolates were not identified. Some Psyringae were isolated from the rhizomes during winterthawing. The paper is presented in Ukrainian.

  14. Les solvants organiques neutres épaissis pour le nettoyage d’une couche picturale.

    Directory of Open Access Journals (Sweden)

    Claire Dupuy

    2012-06-01

    Full Text Available L’évolution des techniques de restauration conduit à l’introduction de nouvelles méthodes et de nouvelles réflexions au service du nettoyage des couches picturales. Nous choisissons ici d’étudier l’une deces réflexions : l’épaississement des solvants organiques neutres liquides à l’aide d’éthers de cellulose et d’acides polyacryliques neutralisés.The evolution of restoration techniques led to the introduction of new methods and new research in the service of cleaning the pictorial layers. Here, we chose to consider one of these approaches: thickening of neutral organic liquid solvents using cellulose ethers and neutralized polyacrylic acid.

  15. SU-C-207-04: Reconstruction Artifact Reduction in X-Ray Cone Beam CT Using a Treatment Couch Model

    Energy Technology Data Exchange (ETDEWEB)

    Lasio, G; Hu, E; Zhou, J; Lee, M; Yi, B [University of Maryland School of Medicine, Baltimore, MD (United States)

    2015-06-15

    Purpose: to mitigate artifacts induced by the presence of the RT treatment couch in on-board CBCT and improve image quality Methods: a model of a Varian IGRT couch is constructed using a CBCT scan of the couch in air. The model is used to generate a set of forward projections (FP) of the treatment couch at specified gantry angles. The model couch forward projections are then used to process CBCT scan projections which contain the couch in addition to the scan object (Catphan phantom), in order to remove the attenuation component of the couch at any given gantry angle. Prior to pre-processing with the model FP, the Catphan projection data is normalized to an air scan with bowtie filter. The filtered Catphan projections are used to reconstruct the CBCT with an in-house FDK algorithm. The artifact reduction in the processed CBCT scan is assessed visually, and the image quality improvement is measured with the CNR over a few selected ROIs of the Catphan modules. Results: Sufficient match between the forward projected data and the x-ray projections is achieved to allow filtering in attenuation space. Visual improvement of the couch induced artifacts is achieved, with a moderate expense of CNR. Conclusion: Couch model-based correction of CBCT projection data has a potential for qualitative improvement of clinical CBCT scans, without requiring position specific correction data. The technique could be used to produce models of other artifact inducing devices, such as immobilization boards, and reduce their impact on patient CBCT images.

  16. Improvement of VMAT plan quality for head and neck cancer with high resolution fluences generated by couch shift between arcs.

    Science.gov (United States)

    Park, Jong Min; Park, So-Yeon; Wu, Hong-Gyun; Kim, Jung-In

    2018-02-01

    To investigate the changes in quality of the volumetric modulated arc therapy (VMAT) plans with couch-shift between arcs by half of a multi-leaf collimator (MLC) leaf width. A total of 22 patients with head-and-neck cancer were retrospectively selected. Since the smallest MLC leaf width was 5 mm in this study, the couch was shifted by 2.5 mm in the longitudinal-direction between arcs to increase the resolution of fluence map. A total of three types of VMAT plans were generated for each patient; the three types of plans were a two-full-arc plan without couch-shift (NS plan), a two-half-arc-pair plan with couch-shift (HAS plan), and a two-full-arc pair plan with couch-shift (FAS plan). Changes in the dose-volumetric parameters were investigated. The FAS plan showed the best plan quality for the target volumes and organs at risk compared to the NS and HAS plans. However, the magnitudes of differences among the three types of plans were minimal, and every plan was clinically acceptable. The average integral doses of the NS, HAS, and FAS plans were 160,549 ± 37,600 Gy-cc, 147,828 ± 33,343 Gy-cc, and 156,030 ± 36,263 Gy-cc, respectively. The average monitor unit of the NS, HAS, and FAS plans were 717 ± 120 MU, 648 ± 100 MU, and 763 ± 158 MU, respectively. The HAS plan was better than the others in terms of normal tissue sparing and plan efficiency. By shifting the couch by half of the MLC leaf width in the longitudinal direction between arcs, the VMAT plan quality could be improved. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  17. Photoreflectance et Photoconductivite des Couches Minces de Antimoinure de Indium Deposees Sur Arsenure de Gallium Par Pulverisation Cathodique avec Magnetron

    Science.gov (United States)

    Beaulieu, Yves

    L'attrait d'un systeme d'imagerie infrarouge integre, ou les detecteurs et l'electronique peuvent etre construits sur la meme gaufre, a motive l'etude de couches minces d'antimoniure d'indium (InSb) deposees sur des substrats d'arseniure de gallium (GaAs). La croissance epitaxiale de ces couches minces a ete realisee par pulverisation cathodique avec magnetron, en utilisant une approche multi -cibles (MSE) ou sous atmosphere d'un organometallique (MOMS). Malgre la grande difference des mailles cristallines des deux semiconducteurs, la qualite des couches minces est bonne et s'ameliore avec l'epaisseur, comme le demontrent les mesures de diffraction des rayons-X, d'effets Raman et Hall, et de microscopie electronique a transmission et a balayage. Les spectres de photoconductivite resolus en energie et en temps des couches deposees par MOMS ont demontre la coexistence de deux phenomenes de photoconduction en presence d'absorption interbande. Pour les energies de photon inferieures a environ 0.35 eV, la photoconductivite usuelle, due au piegeage rapide du porteur minoritaire excedentaire, est observee. Cependant, pour les energies superieures, une composante negative plus lente coexiste avec la composante positive. Elle est due au piegeage d'electrons chauds generes optiquement, dans les echantillons de type n, par des centres situes a haute energie, principalement dans la region de l'interface. Les mesures de photoreflectance dans la region des transitions E_1 et E _1 + Delta_1 ont ete realisees sur des couches deposees par MSE et des echantillons massifs de InSb. Les variations des elargissements de lignes spectrales ont confirme l'amelioration des couches avec l'epaisseur. De plus, l'analyse des lignes spectrales indique la presence d'effets excitoniques. La photoreflectance dans les echantillons massifs de haute purete de InSb a mis en evidence la presence d'une resonance sous les transitions etudiees. L'allure de la ligne spectrale, la position en energie et l

  18. SU-E-T-64: CG-Based Radiation Therapy Simulator with Physical Modeling for Avoidance of Collisions Between Gantry and Couch Or Patient

    International Nuclear Information System (INIS)

    Yamanouchi, M; Arimura, H; Yuda, I

    2014-01-01

    Purpose: It is time-consuming and might cause re-planning to check couch-gantry and patient-gantry collisions on a radiotherapy machine when using couch rotations for non-coplanar beam angles. The aim of this study was to develop a computer-graphics (CG)-based radiation therapy simulator with physical modeling for avoidance of collisions between gantry and couch or patient on a radiotherapy machine. Methods: The radiation therapy simulator was three-dimensionally constructed including a radiotherapy machine (Clinac iX, Varian Medical Systems), couch, and radiation treatment room according to their designs by using a physical-modeling-based computer graphics software (Blender, free and open-source). Each patient was modeled by applying a surface rendering technique to their planning computed tomography (CT) images acquired from 16-slice CT scanner (BrightSpeed, GE Healthcare). Immobilization devices for patients were scanned by the CT equipment, and were rendered as the patient planning CT images. The errors in the collision angle of the gantry with the couch or patient between gold standards and the estimated values were obtained by fixing the gantry angle for the evaluation of the proposed simulator. Results: The average error of estimated collision angles to the couch head side was -8.5% for gantry angles of 60 to 135 degree, and -5.5% for gantry angles of 225 to 300 degree. Moreover, the average error of estimated collision angles to the couch foot side was -1.1% for gantry angles of 60 to 135 degree, and 1.4% for gantry angles of 225 to 300 degree. Conclusion: The CG-based radiation therapy simulator could make it possible to estimate the collision angle between gantry and couch or patient on the radiotherapy machine without verifying the collision angles in the radiation treatment room

  19. The evaluation for the usability of the Varian Standard Couch modelingusing Treatment Planning System

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yong Mo; Song, Yong Min; Kim, Jin Man; Choi, Ji Min; Choi, Byeung Gi [Dept. of Radiation Oncology, Samsung Medical Center, Seoul (Korea, Republic of)

    2016-06-15

    When a radiation treatment, there is an attenuation by Carbon Fiber Couch. In this study, we tried to evaluate the usability of the Varian Standard Couch(VSC) by modeling with Treatment Planning System (TPS) VSC was scanned by CBCT(Cone Beam Computed Tomography) of the Linac(Clinac IX, VARIAN, USA), following the three conditions of VSC, Side Rail OutGrid(SROG), Side Rail InGrid(SRIG), Side Rail In OutSpine Down Bar(SRIOS). After scan, the data was transferred to TPS and modeled by contouring Side Rail, Side Bar Upper, Side Bar Lower, Spine Down Bar automatically. We scanned the Cheese Phantom(Middelton, USA) using Computed Tomography(Light Speed RT 16, GE, USA) and transfer the data to TPS, and apply VSC modeled previously with TPS to it. Dose was measured at the isocenter of Ion Chamber(A1SL, Standard imaging, USA) in Cheese Phantom using 4 and 10 MV radiation for every 5° gantry angle in a different filed size(3 X 3 cm{sup 2},10 X 10cm{sup 2}) without any change of MU(=100), and then we compared the calculated dose and measured dose. Also we included dose at the 127° in SRIG to compare the attenuation by Side Bar Upper. Results : The density of VSC by CBCT in TPS was 0.9g/cm{sup 3}, and in the case of Spine Down Bar, it was 0.7g/cm{sup 3}. The radiation was attenuated by 17.49%, 16.49%, 8.54%, and 7.59% at the Side Rail, Side Bar Upper, Side Bar Lower, and Spine Down Bar. For the accuracy of modeling, calculated dose and measured dose were compared. The average error was 1.13% and the maximum error was 1.98% at the 170° beam crossing the Spine Down Bar. To evaluate the usability for the VSC modeled by TPS, the maximum error was 1.98% as a result of compassion between calculated dose and measured dose. We found out that VSC modeling helped expect the dose, so we think that it will be helpful for the more accurate treatment.

  20. Dose impact of a carbon fiber couch for stereotactic body radiation therapy of lung tumors

    International Nuclear Information System (INIS)

    Tominaga, Hirofumi; Kanetake, Nagisa; Kawasaki, Keiichi; Iwashita, Yuki; Sakata, Junichi; Okuda, Tomoko; Araki, Fujio; Shimohigashi, Yoshinobu; Tomiyama, Yuki

    2013-01-01

    The aim of this study was to measure the dose attenuation caused by a carbon fiber radiation therapy table (Imaging Couch Top; ICT, BrainLab) and to evaluate the dosimetric impact of ICT during stereotactic body radiation therapy (SBRT) in lung tumors. The dose attenuation of ICT was measured using an ionization chamber and modeled by means of a treatment planning system (TPS). SBRT was planned with and without ICT in a lung tumor phantom and ten cases of clinical lung tumors. The results were analyzed from isocenter doses and a dose-volume histogram (DVH): D 95 , D mean , V 20 , V 5 , homogeneity index (HI), and conformity index (CI). The dose attenuation of the ICT modeled with TPS agreed to within ±1% of the actually measured values. The isocenter doses, D 95 and D mean with and without ICT showed differences of 4.1-5% for posterior single field and three fields in the phantom study, and differences of 0.6-2.4% for five fields and rotation in the phantom study and six fields in ten clinical cases. The dose impact of ICT was not significant for five or more fields in SBRT. It is thus possible to reduce the dose effect of ICT by modifying the beam angle and beam weight in the treatment plan. (author)

  1. DYNAMIQUE DE LA COUCHE LIMITE ATMOSPHERIQUE:
    DE LA TURBULENCE AUX SYSTEMES DE MESO-ECHELLE

    OpenAIRE

    Drobinski , Philippe

    2005-01-01

    The planetary boundary layer (PBL), at the interface between the surface and the free troposphere, is the region of transfer of energy (momentum, sensible and latent heat), wator vapor and pollutants between the surface and the free troposphere, upon which depends the horizontal and vertical distribution of clouds, aerosols and chemical species. The global understanding of physical processes in the PBL and their impact on the largest scales is an open field of high priority research activity....

  2. Continuous Arc Rotation of the Couch Therapy for the Delivery of Accelerated Partial Breast Irradiation: A Treatment Planning Analysis

    International Nuclear Information System (INIS)

    Shaitelman, Simona F.; Kim, Leonard H.; Yan Di; Martinez, Alvaro A.; Vicini, Frank A.; Grills, Inga S.

    2011-01-01

    Purpose: We present a novel form of arc therapy: continuous arc rotation of the couch (C-ARC) and compare its dosimetry with three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric-modulated arc therapy (VMAT) for accelerated partial breast irradiation (APBI). C-ARC, like VMAT, uses a modulated beam aperture and dose rate, but with the couch, not the gantry, rotating. Methods and Materials: Twelve patients previously treated with APBI using 3D-CRT were replanned with (1) C-ARC, (2) IMRT, and (3) VMAT. C-ARC plans were designed with one medial and one lateral arc through which the couch rotated while the gantry was held stationary at a tangent angle. Target dose coverage was normalized to the 3D-CRT plan. Comparative endpoints were dose to normal breast tissue, lungs, and heart and monitor units prescribed. Results: Compared with 3D-CRT, C-ARC, IMRT, and VMAT all significantly reduced the ipsilateral breast V50% by the same amount (mean, 7.8%). Only C-ARC and IMRT plans significantly reduced the contralateral breast maximum dose, the ipsilateral lung V5Gy, and the heart V5%. C-ARC used on average 40%, 30%, and 10% fewer monitor units compared with 3D-CRT, IMRT, and VMAT, respectively. Conclusions: C-ARC provides improved dosimetry and treatment efficiency, which should reduce the risks of toxicity and secondary malignancy. Its tangent geometry avoids irradiation of critical structures that is unavoidable using the en face geometry of VMAT.

  3. Etude des propriétés magnéto-optiques des couches minces à base ...

    African Journals Online (AJOL)

    Etude des propriétés magnéto-optiques des couches minces à base de ferrite de cobalt obtenues par voie sol-gel. ... Les courbes obtenues à la longueur d'onde de 820 nm présentent des cycles d'hystérésis avec des rotations rémanentes de 40, 60 et 81°/cm. Ces résultats présentent une excellente rotation Faraday de ...

  4. Novel and high volume use flame retardants in US couches reflective of the 2005 PentaBDE phase out.

    Science.gov (United States)

    Stapleton, Heather M; Sharma, Smriti; Getzinger, Gordon; Ferguson, P Lee; Gabriel, Michelle; Webster, Thomas F; Blum, Arlene

    2012-12-18

    California's furniture flammability standard Technical Bulletin 117 (TB 117) is believed to be a major driver of chemical flame retardant (FR) use in residential furniture in the United States. With the phase-out of the polybrominated diphenyl ether (PBDE) FR mixture PentaBDE in 2005, alternative FRs are increasingly being used to meet TB 117; however, it was unclear which chemicals were being used and how frequently. To address this data gap, we collected and analyzed 102 samples of polyurethane foam from residential couches purchased in the United States from 1985 to 2010. Overall, we detected chemical flame retardants in 85% of the couches. In samples purchased prior to 2005 (n = 41) PBDEs associated with the PentaBDE mixture including BDEs 47, 99, and 100 (PentaBDE) were the most common FR detected (39%), followed by tris(1,3-dichloroisopropyl) phosphate (TDCPP; 24%), which is a suspected human carcinogen. In samples purchased in 2005 or later (n = 61) the most common FRs detected were TDCPP (52%) and components associated with the Firemaster550 (FM 550) mixture (18%). Since the 2005 phase-out of PentaBDE, the use of TDCPP increased significantly. In addition, a mixture of nonhalogenated organophosphate FRs that included triphenyl phosphate (TPP), tris(4-butylphenyl) phosphate (TBPP), and a mix of butylphenyl phosphate isomers were observed in 13% of the couch samples purchased in 2005 or later. Overall the prevalence of flame retardants (and PentaBDE) was higher in couches bought in California compared to elsewhere, although the difference was not quite significant (p = 0.054 for PentaBDE). The difference was greater before 2005 than after, suggesting that TB 117 is becoming a de facto standard across the U.S. We determined that the presence of a TB 117 label did predict the presence of a FR; however, lack of a label did not predict the absence of a flame retardant. Following the PentaBDE phase out, we also found an increased number of flame retardants on the

  5. Algorithme distribué pour l'assignation de rôles dans Molecular MAC, une couche MAC multicanal

    OpenAIRE

    Darties, Benoit; Theoleyre, Fabrice; Duda, Andrzej

    2009-01-01

    International audience; Une couche MAC multicanal semble une approche intéressante afin d'optimiser le débit d'un réseau maillé radio en multiplexant les transmissions sur des canaux orthogonaux. En particulier, Molecular MAC pro- posé récemment étends I E E E 802.11 DCF afin d'offrir une telle fonctionnalité. Cependant, ce protocol requiert une assignation de rôles et canaux : certains noeuds utilisent un canal statique tandis que les autres sautent continuellement de canal. Nous étendons ici ...

  6. SU-F-T-515: Increased Skin Dose in Supine Craniospinal Irradiation Due to Carbon Fiber Couch and Vacuum Bag Immobilization Device

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, D; Zhao, Z; Wang, X; Yang, J [UT MD Anderson Cancer Center, Houston, TX (United States)

    2016-06-15

    Purpose: To measure the surface dose for supine craniospinal irradiation employing posterior beams, treating through an imaging couch and BlueBag immobilization device. Methods: The percentage depth dose (PDD) in the buildup region of a clinical 6 MV photon beam was measured using an Advanced Markus parallel plate ionization chamber in a solid water phantom. The PDD from a 10×10 cm{sup 2} anterior beam was measured at 100 cm SSD, simulating a traditional prone craniospinal technique. The measurements were compared to commissioning and treatment planning system data. The PDD was also measured in a posterior setup with the phantom surface laying directly on the Brainlab carbon fiber imaging couch, with the phantom surface 100 cm from the source, simulating a supine craniospinal setup. The posterior measurements were repeated with a BlueBag vacuum immobilization device between the couch and phantom, with thicknesses of 1.7 cm and 5 cm. The PDD from a 10×10 cm{sup 2} field and a typical 6×30 cm{sup 2} craniospinal field were also compared. The PDDs were normalized at 5 cm to reflect typical craniospinal prescription dose normalization. Results: The measured PDD curve from the anterior setup agreed well with commissioning and treatment planning data, with surface doses of 19.9%, 28.8% and 27.7%, respectively. The surface doses of the 10×10 cm{sup 2} and 6×30 cm{sup 2} fields delivered through the imaging couch were both 122.4%. The supine setup yielded surface doses of 122.4%, 121.6%, and 119.6% for the couch only, 1.7 cm bag, and 5 cm bag setups, respectively. Conclusion: Delivering craniospinal irradiation through a carbon fiber couch removes the majority of skin sparing. The addition of a vacuum bag immobilization device restores some skin sparing, but the magnitude of this effect is negligible.

  7. SU-E-J-126: An Online Replanning Method for FFF Beams Without Couch Shift

    Energy Technology Data Exchange (ETDEWEB)

    Ahunbay, E; Ates, O; Li, X [Medical College of Wisconsin, Milwaukee, WI (United States)

    2015-06-15

    Purpose: In a situation that couch shift for patient positioning is not preferred or prohibited (e.g., MR-Linac), segment aperture morphing (SAM) can address target dislocation and deformation. For IMRT/VMAT with flattening filter free (FFF) beams, however, SAM method would lead to an adverse translational dose effect due to the beam unflattening. Here we propose a new 2-step process to address both the translational effect of FFF beams and the target deformation. Methods: The replanning method consists of an offline and an online steps. The offline step is to create a series of pre-shifted plans (PSP) obtained by a so called “warm start” optimization (starting optimization from the original plan, rather from scratch) at a series of isocenter shifts with fixed distance (e.g. 2 cm, at x,y,z = 2,0,0 ; 2,2,0 ; 0,2,0; …;− 2,0,0). The PSPs all have the same number of segments with very similar shapes, since the warm-start optimization only adjusts the MLC positions instead of regenerating them. In the online step, a new plan is obtained by linearly interpolating the MLC positions and the monitor units of the closest PSPs for the shift determined from the image of the day. This two-step process is completely automated, and instantaneously fast (no optimization or dose calculation needed). The previously-developed SAM algorithm is then applied for daily deformation. We tested the method on sample prostate and pancreas cases. Results: The two-step interpolation method can account for the adverse dose effects from FFF beams, while SAM corrects for the target deformation. The whole process takes the same time as the previously reported SAM process (5–10 min). Conclusion: The new two-step method plus SAM can address both the translation effects of FFF beams and target deformation, and can be executed in full automation requiring no additional time from the SAM process. This research was supported by Elekta inc. (Crawley, UK)

  8. SU-E-J-258: Inter- and Intra-Fraction Setup Stability and Couch Change Tolerance for Image Guided Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Teboh, Forbang R; Agee, M; Rowe, L; Creasy, T; Schultz, J; Bell, R; Wong, J; Armour, E [Johns Hopkins University, Baltimore, MD (United States)

    2014-06-01

    Purpose: Immobilization devices combine rigid patient fixation as well as comfort and play a key role providing the stability required for accurate radiation delivery. In the setup step, couch re-positioning needed to align the patient is derived via registration of acquired versus reference image. For subsequent fractions, replicating the initial setup should yield identical alignment errors when compared to the reference. This is not always the case and further couch re-positioning can be needed. An important quality assurance measure is to set couch tolerances beyond which additional investigations are needed. The purpose of this work was to study the inter-fraction couch changes needed to re-align the patient and the intra-fraction stability of the alignment as a guide to establish the couch tolerances. Methods: Data from twelve patients treated on the Accuray CyberKnife (CK) system for fractionated intracranial radiotherapy and immobilized with Aquaplast RT, U-frame, F-Head-Support (Qfix, PA, USA) was used. Each fraction involved image acquisitions and registration with the reference to re-align the patient. The absolute couch position corresponding to the approved setup alignment was recorded per fraction. Intra-fraction set-up corrections were recorded throughout the treatment. Results: The average approved setup alignment was 0.03±0.28mm, 0.15±0.22mm, 0.06±0.31mm in the L/R, A/P, S/I directions respectively and 0.00±0.35degrees, 0.03±0.32degrees, 0.08±0.45degrees for roll, pitch and yaw respectively. The inter-fraction reproducibility of the couch position was 6.65mm, 10.55mm, and 4.77mm in the L/R, A/P and S/I directions respectively and 0.82degrees, 0.71degrees for roll and pitch respectively. Intra-fraction monitoring showed small average errors of 0.21±0.21mm, 0.00±0.08mm, 0.23±0.22mm in the L/R, A/P, S/I directions respectively and 0.03±0.12degrees, 0.04±0.25degrees, and 0.13±0.15degrees in the roll, pitch and yaw respectively. Conclusion

  9. A validation of carbon fiber imaging couch top modeling in two radiation therapy treatment planning systems: Philips Pinnacle3 and BrainLAB iPlan RT Dose

    Directory of Open Access Journals (Sweden)

    Njeh Christopher F

    2012-11-01

    Full Text Available Abstract Background Carbon fiber (CF is now the material of choice for radiation therapy couch tops. Initial designs included side metal bars for rigidity; however, with the advent of IGRT, involving on board imaging, new thicker CF couch tops without metal bars have been developed. The new design allows for excellent imaging at the expense of potentially unacceptable dose attenuation and perturbation. Objectives We set out to model the BrainLAB imaging couch top (ICT in Philips Pinnacle3 treatment planning system (TPS, to validate the already modeled ICT in BrainLAB iPlan RT Dose treatment planning system and to compute the magnitude of the loss in skin sparing. Results Using CF density of 0.55 g/cm3 and foam density of 0.03 g/cm3, we demonstrated an excellent agreement between measured dose and Pinnacle3 TPS computed dose using 6 MV beam. The agreement was within 1% for all gantry angle measured except for 120o, which was 1.8%. The measured and iPlan RT Dose TPS computed dose agreed to within 1% for all gantry angles and field sizes measured except for 100o where the agreement was 1.4% for 10 cm × 10 cm field size. Predicted attenuation through the couch by iPlan RT Dose TPS (3.4% - 9.5% and Pinnacle3 TPS (2% - 6.6% were within the same magnitude and similar to previously reported in the literature. Pinnacle3 TPS estimated an 8% to 20% increase in skin dose with increase in field size. With the introduction of the CF couch top, it estimated an increase in skin dose by approximately 46 - 90%. The clinical impact of omitting the couch in treatment planning will be dependent on the beam arrangement, the percentage of the beams intersecting the couch and their angles of incidence. Conclusion We have successfully modeled the ICT in Pinnacle3 TPS and validated the modeled ICT in iPlan RT Dose. It is recommended that the ICT be included in treatment planning for all treatments that involve posteriors beams. There is a significant

  10. A validation of carbon fiber imaging couch top modeling in two radiation therapy treatment planning systems: Philips Pinnacle3 and BrainLAB iPlan RT Dose

    International Nuclear Information System (INIS)

    Njeh, Christopher F; Parker, Jason; Spurgin, Joseph; Rhoe, Elizabeth

    2012-01-01

    Carbon fiber (CF) is now the material of choice for radiation therapy couch tops. Initial designs included side metal bars for rigidity; however, with the advent of IGRT, involving on board imaging, new thicker CF couch tops without metal bars have been developed. The new design allows for excellent imaging at the expense of potentially unacceptable dose attenuation and perturbation. We set out to model the BrainLAB imaging couch top (ICT) in Philips Pinnacle 3 treatment planning system (TPS), to validate the already modeled ICT in BrainLAB iPlan RT Dose treatment planning system and to compute the magnitude of the loss in skin sparing. Using CF density of 0.55 g/cm 3 and foam density of 0.03 g/cm 3 , we demonstrated an excellent agreement between measured dose and Pinnacle 3 TPS computed dose using 6 MV beam. The agreement was within 1% for all gantry angle measured except for 120 o , which was 1.8%. The measured and iPlan RT Dose TPS computed dose agreed to within 1% for all gantry angles and field sizes measured except for 100 o where the agreement was 1.4% for 10 cm × 10 cm field size. Predicted attenuation through the couch by iPlan RT Dose TPS (3.4% - 9.5%) and Pinnacle 3 TPS (2% - 6.6%) were within the same magnitude and similar to previously reported in the literature. Pinnacle 3 TPS estimated an 8% to 20% increase in skin dose with increase in field size. With the introduction of the CF couch top, it estimated an increase in skin dose by approximately 46 - 90%. The clinical impact of omitting the couch in treatment planning will be dependent on the beam arrangement, the percentage of the beams intersecting the couch and their angles of incidence. We have successfully modeled the ICT in Pinnacle 3 TPS and validated the modeled ICT in iPlan RT Dose. It is recommended that the ICT be included in treatment planning for all treatments that involve posteriors beams. There is a significant increase in skin dose that is dependent on the percentage of the beam

  11. SU-E-J-258: Inter- and Intra-Fraction Setup Stability and Couch Change Tolerance for Image Guided Radiation Therapy

    International Nuclear Information System (INIS)

    Teboh, Forbang R; Agee, M; Rowe, L; Creasy, T; Schultz, J; Bell, R; Wong, J; Armour, E

    2014-01-01

    Purpose: Immobilization devices combine rigid patient fixation as well as comfort and play a key role providing the stability required for accurate radiation delivery. In the setup step, couch re-positioning needed to align the patient is derived via registration of acquired versus reference image. For subsequent fractions, replicating the initial setup should yield identical alignment errors when compared to the reference. This is not always the case and further couch re-positioning can be needed. An important quality assurance measure is to set couch tolerances beyond which additional investigations are needed. The purpose of this work was to study the inter-fraction couch changes needed to re-align the patient and the intra-fraction stability of the alignment as a guide to establish the couch tolerances. Methods: Data from twelve patients treated on the Accuray CyberKnife (CK) system for fractionated intracranial radiotherapy and immobilized with Aquaplast RT, U-frame, F-Head-Support (Qfix, PA, USA) was used. Each fraction involved image acquisitions and registration with the reference to re-align the patient. The absolute couch position corresponding to the approved setup alignment was recorded per fraction. Intra-fraction set-up corrections were recorded throughout the treatment. Results: The average approved setup alignment was 0.03±0.28mm, 0.15±0.22mm, 0.06±0.31mm in the L/R, A/P, S/I directions respectively and 0.00±0.35degrees, 0.03±0.32degrees, 0.08±0.45degrees for roll, pitch and yaw respectively. The inter-fraction reproducibility of the couch position was 6.65mm, 10.55mm, and 4.77mm in the L/R, A/P and S/I directions respectively and 0.82degrees, 0.71degrees for roll and pitch respectively. Intra-fraction monitoring showed small average errors of 0.21±0.21mm, 0.00±0.08mm, 0.23±0.22mm in the L/R, A/P, S/I directions respectively and 0.03±0.12degrees, 0.04±0.25degrees, and 0.13±0.15degrees in the roll, pitch and yaw respectively. Conclusion

  12. L’emploi associatif et la reproduction des couches moyennes salariées

    Directory of Open Access Journals (Sweden)

    Gérard Chevalier

    2011-07-01

    Full Text Available L’analyse secondaire des enquêtes Emploi de l’Insee entre 1993 et 2002 révèle un accroissement des diplômés universitaires travaillant dans le secteur associatif. Les travaux statistiques sur les associations conduisent à poser que leurs fonctions correspondaient aux domaines privilégiés par les politiques publiques des années 1990, tels que l’éducation, le développement local, la culture ou l’action sociale. Considérant la continuité des fonctions de gestion des rapports sociaux d’une génération à l’autre et la proximité entre les profils culturels requis par les nouvelles missions associatives et ceux des animateurs des ces politiques, cet article interprète l’augmentation relevée comme le signe de la reproduction des couches moyennes salariées à travers les politiques publiques.Employment in non-profit sector and reproduction of service middle classesAnnual surveys carried out by a French statistical institute between 1993 and 2002 show an increasing proportion of at least 25 years old university graduates in non-profit sector. Statistical inquiries about this sector lead to assess that the jobs performed by theses graduates were congruent with issues treated by state public policies of the 90’s, such as education, local development, culture and social services. Considering the similarity between functions of these graduates in social control and the one of their parents and considering too the cultural congruence of these functions with the profile of the state policies officials, this paper concludes that graduates increase in non-profit sector is one of the ways used by public service middle class to reproduce itself through policies.El empleo asociativo y la reproducción de las capas medias asalariadasEl análisis segundario de las encuestas sobre el empleo realizadas por el INSEE (Institut national de la statistique et des études économiques entre 1993 y 2002 ponen en relieve un aumento de la

  13. Effectiveness of couch height-based patient set-up and an off-line correction protocol in prostate cancer radiotherapy.

    NARCIS (Netherlands)

    Lin, N.G.C.B. van; Nijenhuis, E.; Huizenga, H.; Vight, L.P. van der; Visser, A.

    2001-01-01

    PURPOSE: To investigate set-up improvement caused by applying a couch height-based patient set-up method in combination with a technologist-driven off-line correction protocol in nonimmobilized radiotherapy of prostate patients. METHODS AND MATERIALS: A three-dimensional shrinking action level

  14. A dosimetric comparison of real-time adaptive and non-adaptive radiotherapy: A multi-institutional study encompassing robotic, gimbaled, multileaf collimator and couch tracking

    DEFF Research Database (Denmark)

    Colvill, Emma; Booth, Jeremy; Nill, Simeon

    2016-01-01

    AND MATERIALS: Ten institutions with robotic(2), gimbaled(2), MLC(4) or couch tracking(2) used common materials including CT and structure sets, motion traces and planning protocols to create a lung and a prostate plan. For each motion trace, the plan was delivered twice to a moving dosimeter; with and without...

  15. eNAL++: a new and effective off-line correction protocol for rotational setup errors when using a robotic couch

    NARCIS (Netherlands)

    Martens, D.; Luesink, M.; Huizenga, H.; Pasma, K.L.

    2015-01-01

    Cone-beam CTs (CBCTs) installed on a linear accelerator can be used to provide fast and accurate automatic six degrees of freedom (6DoF) vector displacement information of the patient position just prior to radiotherapy. These displacement corrections can be made with 6DoF couches, which are

  16. SU-E-T-234: Daily Quality Assurance for a Six Degrees of Freedom Couch Using a Novel Phantom

    Energy Technology Data Exchange (ETDEWEB)

    Woods, K; Woollard, J; Ayan, A; Sandu, A; Sommerfeld, J; Gupta, N [Ohio State Univ, Columbus, OH (United States); Laurel, A [Memorial Medical Center, Modesto, CA (United States)

    2015-06-15

    Purpose: To test the accuracy and reproducibility of both translational and rotational movements for a couch with six degrees of freedom (6DoF) using a novel phantom design Methods: An end-to-end test was carried out using two different phantoms. A 6 cm3 cube with a central fiducial BB (WL-QA Sun Nuclear) and a custom fabricated rectangular prism (31 cm x 8 cm x 8 cm), placed on a baseplate with known angular offsets for pitch, roll and yaw with a central fiducial BB and unique surface structures for registration purposes, were used. The end-to-end test included an initial CT simulation for a reference study, setup to an offset mark on each phantom, registration of the reference CT to the acquired cone-beam CT, and final Winston-Lutz delivery at four cardinal gantry angles. Results for both translational and rotational movements were recorded and compared for both phantoms. Results: Translational and rotational measurements were performed with a PerfectPitch (Varian) couch for 10 trials for both phantoms. Distinct translational shifts were [−5.372±0.384mm, −10.183±0.137mm, 14.028±0.155mm] for the cube and [7.520±0.159mm, −9.117±0.101mm, 16.273±0.115mm] for the prototype phantom for lateral, longitudinal, and vertical shifts, respectively. Distinct rotational adjustments were [1.121±0.102o, −1.067±0.235o, −2.662±0.380o] for the cube and [2.534±0.059o, 1.994±0.025o, 2.094±0.076o] for the prototype for pitch, roll, and yaw, respectively. Winston-Lutz test results performed after 6DoF couch correction from each cardinal gantry angle ranged from 0.26–0.72mm for the cube and 0.55–0.86mm for the prototype. Conclusion: The prototype phantom is more precise for both translational and rotational adjustments compared to a commercial phantom. The design of the prototype phantom allows for a more discernible visual confirmation of correct translational and rotational adjustments with the prototype phantom. Winston-Lutz results are more accurate for the

  17. SU-E-T-234: Daily Quality Assurance for a Six Degrees of Freedom Couch Using a Novel Phantom

    International Nuclear Information System (INIS)

    Woods, K; Woollard, J; Ayan, A; Sandu, A; Sommerfeld, J; Gupta, N; Laurel, A

    2015-01-01

    Purpose: To test the accuracy and reproducibility of both translational and rotational movements for a couch with six degrees of freedom (6DoF) using a novel phantom design Methods: An end-to-end test was carried out using two different phantoms. A 6 cm3 cube with a central fiducial BB (WL-QA Sun Nuclear) and a custom fabricated rectangular prism (31 cm x 8 cm x 8 cm), placed on a baseplate with known angular offsets for pitch, roll and yaw with a central fiducial BB and unique surface structures for registration purposes, were used. The end-to-end test included an initial CT simulation for a reference study, setup to an offset mark on each phantom, registration of the reference CT to the acquired cone-beam CT, and final Winston-Lutz delivery at four cardinal gantry angles. Results for both translational and rotational movements were recorded and compared for both phantoms. Results: Translational and rotational measurements were performed with a PerfectPitch (Varian) couch for 10 trials for both phantoms. Distinct translational shifts were [−5.372±0.384mm, −10.183±0.137mm, 14.028±0.155mm] for the cube and [7.520±0.159mm, −9.117±0.101mm, 16.273±0.115mm] for the prototype phantom for lateral, longitudinal, and vertical shifts, respectively. Distinct rotational adjustments were [1.121±0.102o, −1.067±0.235o, −2.662±0.380o] for the cube and [2.534±0.059o, 1.994±0.025o, 2.094±0.076o] for the prototype for pitch, roll, and yaw, respectively. Winston-Lutz test results performed after 6DoF couch correction from each cardinal gantry angle ranged from 0.26–0.72mm for the cube and 0.55–0.86mm for the prototype. Conclusion: The prototype phantom is more precise for both translational and rotational adjustments compared to a commercial phantom. The design of the prototype phantom allows for a more discernible visual confirmation of correct translational and rotational adjustments with the prototype phantom. Winston-Lutz results are more accurate for the

  18. Effectiveness of couch height-based patient set-up and an off-line correction protocol in prostate cancer radiotherapy

    International Nuclear Information System (INIS)

    Lin, Emile N.J.Th. van; Nijenhuis, Edwin; Huizenga, Henk; Vight, Lisette van der; Visser, Andries

    2001-01-01

    Purpose: To investigate set-up improvement caused by applying a couch height-based patient set-up method in combination with a technologist-driven off-line correction protocol in nonimmobilized radiotherapy of prostate patients. Methods and Materials: A three-dimensional shrinking action level correction protocol is applied in two consecutive patient cohorts with different set-up methods: the traditional 'laser set-up' group (n=43) and the 'couch height set-up' group (n=112). For all directions, left-right, ventro-dorsal, and cranio-caudal, random and systematic set-up deviations were measured. Results: The couch height set-up method improves the patient positioning compared to the laser set-up method. Without application of the correction protocol, both systematic and random errors reduced to 2.2-2.4 mm (1 SD) and 1.7-2.2 mm (1 SD), respectively. By using the correction protocol, systematic errors reduced further to 1.3-1.6 mm (1 SD). One-dimensional deviations were within 5 mm for >90% of the measured fractions. The required number of corrections per patient in the off-line correction protocol was reduced significantly during the course of treatment from 1.1 to 0.6 by the couch height set-up method. The treatment time was not prolonged by application of the correction protocol. Conclusions: The couch height set-up method improves the set-up significantly, especially in the ventro-dorsal direction. Combination of this set-up method with an off-line correction strategy, executed by technologists, reduces the number of set-up corrections required

  19. Etude et caractérisation de la couche physique du standard IEEE802.16/WIMAX

    OpenAIRE

    ABOURA, Wissam; BENHABIB, Imane

    2014-01-01

    Dans ce travail nous avons étudié l’évolution et la caractérisation du système WiMAX/IEEE 802.16 ainsi que son architecture. En plus nous avons présenté les différents blocs de sa couche physique qui utilise la technique OFDM et le mécanisme de correction d’erreur (FEC) qui comporte les codes correcteurs d’erreurs (code convolutif et Reed Solomon) ainsi que les modulations numériques. Sur le côté du récepteur, nous avons implémenté l'estimation du canal de transmission. Ensu...

  20. EFFET DES TRAITEMENTS THERMIQUES SUR LA REACTION ENTRE DES COUCHES MINCES DE TITANE ET DES SUBSTRATS EN ACIER

    Directory of Open Access Journals (Sweden)

    D Slimani

    2015-06-01

    Full Text Available Des couches minces du titane pur ont été déposées avec la méthode de pulvérisation cathodique sur des substrats en acier, type FF80 K-1 contenants ~1% mass. en carbone. La réaction entre les deux parties du système substrat-couche mince est activée avec des traitements thermiques sous vide dans l’intervalle de températures de 400 à900°Cpendant 30 minutes. Les Spectres de diffraction de rayons x confirment l’inter- diffusion des éléments  chimiques du système résultants la formation et la croissance des nouvelles phases en particulier le carbure binaire TiC ayant des caractéristiques thermomécaniques importantes. L’analyse morphologique des échantillons traités  avec le microscope électronique à balayage (MEB montre l’augmentation du flux de diffusion atomique avec la température de recuit, notamment la diffusion du manganèse et du fer vers la surface libre des échantillons aux températures élevées provoquant la dégradation des propriétés mécaniques des revêtements contrairement au premiers stades d’interaction où on a obtenu des bonnes valeurs de la microdureté.

  1. Comparison of daily couch shifts using MVCT (TomoTherapy) and B-mode ultrasound (BAT System) during prostate radiotherapy.

    Science.gov (United States)

    Lin, Steven H; Sugar, Elizabeth; Teslow, Terrance; McNutt, Todd; Saleh, Habeeb; Song, Danny Y

    2008-08-01

    The purpose of this study was to compare daily couch shifts after prostate localization between megavoltage CT (MVCT, Hi-ART TomoTherapy) and b-mode ultrasound (BAT system). Nine hundred and thirteen couch shifts from 22 consecutive patients treated using MVCT localization were compared to 853 shifts from 23 randomly selected patients treated using b-mode ultrasound prostate localization. Shifts were made in three principal axes based on prostate position after comparing daily images to the initial planning CT. Mean shift for each axis and the shift variability both between and within individual subjects were calculated. Variability was higher for BAT compared to MVCT for vertical and cranial-caudal (CC) shifts (p=0.0084 and 0.01037, respectively), while lateral shifts were significantly greater for MVCT. For each individual, the pairwise correlations between shifts in different axes were calculated. Among all the groups and pairings, only the pairing of vertical and cranial/caudal adjustments in BAT-localized patients showed significant evidence of correlation after adjustment for multiple pairwise comparisons (p=0.0006). When compared to MVCT, the use of BAT for prostate localization results in greater variability of positional adjustments in vertical and CC directions. This likely reflects differences in the ability to precisely align b-mode ultrasound contours to KVCT images, as well as prostate excursion in vertical and CC direction caused by the ultrasound probe. These considerations need to be made when defining treatment volumes, and argue for the use of less disruptive techniques for daily prostate localization.

  2. An accuracy assessment of different rigid body image registration methods and robotic couch positional corrections using a novel phantom

    Energy Technology Data Exchange (ETDEWEB)

    Arumugam, Sankar; Xing Aitang [Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute, New South Wales 2170 (Australia); Jameson, Michael G. [Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute, New South Wales 2170, Australia and Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales 2522 (Australia); Holloway, Lois [Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute, New South Wales 2170 (Australia); Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales 2522 (Australia); University of New South Wales, Sydney, New South Wales 2052 (Australia); Institute of Medical Physics, School of Physics, University of Sydney, Sydney, New South Wales 2006 (Australia)

    2013-03-15

    Purpose: Image guided radiotherapy (IGRT) using cone beam computed tomography (CBCT) images greatly reduces interfractional patient positional uncertainties. An understanding of uncertainties in the IGRT process itself is essential to ensure appropriate use of this technology. The purpose of this study was to develop a phantom capable of assessing the accuracy of IGRT hardware and software including a 6 degrees of freedom patient positioning system and to investigate the accuracy of the Elekta XVI system in combination with the HexaPOD robotic treatment couch top. Methods: The constructed phantom enabled verification of the three automatic rigid body registrations (gray value, bone, seed) available in the Elekta XVI software and includes an adjustable mount that introduces known rotational offsets to the phantom from its reference position. Repeated positioning of the phantom was undertaken to assess phantom rotational accuracy. Using this phantom the accuracy of the XVI registration algorithms was assessed considering CBCT hardware factors and image resolution together with the residual error in the overall image guidance process when positional corrections were performed through the HexaPOD couch system. Results: The phantom positioning was found to be within 0.04 ({sigma}= 0.12) Degree-Sign , 0.02 ({sigma}= 0.13) Degree-Sign , and -0.03 ({sigma}= 0.06) Degree-Sign in X, Y, and Z directions, respectively, enabling assessment of IGRT with a 6 degrees of freedom patient positioning system. The gray value registration algorithm showed the least error in calculated offsets with maximum mean difference of -0.2({sigma}= 0.4) mm in translational and -0.1({sigma}= 0.1) Degree-Sign in rotational directions for all image resolutions. Bone and seed registration were found to be sensitive to CBCT image resolution. Seed registration was found to be most sensitive demonstrating a maximum mean error of -0.3({sigma}= 0.9) mm and -1.4({sigma}= 1.7) Degree-Sign in translational

  3. An accuracy assessment of different rigid body image registration methods and robotic couch positional corrections using a novel phantom

    International Nuclear Information System (INIS)

    Arumugam, Sankar; Xing Aitang; Jameson, Michael G.; Holloway, Lois

    2013-01-01

    Purpose: Image guided radiotherapy (IGRT) using cone beam computed tomography (CBCT) images greatly reduces interfractional patient positional uncertainties. An understanding of uncertainties in the IGRT process itself is essential to ensure appropriate use of this technology. The purpose of this study was to develop a phantom capable of assessing the accuracy of IGRT hardware and software including a 6 degrees of freedom patient positioning system and to investigate the accuracy of the Elekta XVI system in combination with the HexaPOD robotic treatment couch top. Methods: The constructed phantom enabled verification of the three automatic rigid body registrations (gray value, bone, seed) available in the Elekta XVI software and includes an adjustable mount that introduces known rotational offsets to the phantom from its reference position. Repeated positioning of the phantom was undertaken to assess phantom rotational accuracy. Using this phantom the accuracy of the XVI registration algorithms was assessed considering CBCT hardware factors and image resolution together with the residual error in the overall image guidance process when positional corrections were performed through the HexaPOD couch system. Results: The phantom positioning was found to be within 0.04 (σ= 0.12)°, 0.02 (σ= 0.13)°, and −0.03 (σ= 0.06)° in X, Y, and Z directions, respectively, enabling assessment of IGRT with a 6 degrees of freedom patient positioning system. The gray value registration algorithm showed the least error in calculated offsets with maximum mean difference of −0.2(σ= 0.4) mm in translational and −0.1(σ= 0.1)° in rotational directions for all image resolutions. Bone and seed registration were found to be sensitive to CBCT image resolution. Seed registration was found to be most sensitive demonstrating a maximum mean error of −0.3(σ= 0.9) mm and −1.4(σ= 1.7)° in translational and rotational directions over low resolution images, and this is reduced to

  4. Etude Des Caractéristiques Structurelles Des Couches Minces De ZnO. Application à une Cellule Photovoltaïque.

    OpenAIRE

    MERABET, Yassamina

    2014-01-01

    De nos jours les cellules solaires à couches minces sont de plus en plus utilisées essentiellement à raison de leur faible coût. Durant ces dernières décennies les performances de ces cellules ont été nettement améliorées. Dans le présent travail, nous avons fait une étude analytique sur les paramètres (caractéristiques) structurels des couches minces d’Oxyde de Zinc (ZnO) réalisées par la pulvérisation cathodique. Nous avons simulé une cellule solaire à l’aide d’un logiciel (SCAPS1-D) afin d...

  5. Dose attenuation by a carbon fiber linac couch and modeling with a treatment planning system; Medida de la atenuacion producida por la mesa de tratamiento de un acelerador lineal y su modelado en un sistema de planificacion

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Galiano, P.; Garcia Sancho, J.M.; Crelgo, D.; Pamos, M.; Fernandez, J.; Vivanco, J.

    2010-07-01

    The purpose of this work is to investigate the attenuation caused by a carbon fiber linac treatment couch and the ability of a commercial radiotherapy treatment planning system to simulate it. The attenuation caused by an Exact{copyright} treatment couch in a Varian{copyright} Clinac{copyright} 2100 C/D was characterized in detail. Both 6 MV and 18 MV photon beams were studied. The treatment couch was modeled and incorporated to Elekta{copyright} XiO{copyright} treatment planning system. Measured and computed attenuation values were compared. As a result we found that the attenuation caused by this complex treatment couch is strongly dependent on the incidence angle of the beam. The measured attenuation values reach 16% for 6 MV and 10% for 18 MV. The model incorporated to the treatment planning software allows reducing the differences between measured and calculated data below 2.5% and 2.0% for 6 MV and 18 MV respectively. In conclusion, it is strongly recommended accounting for the perturbation caused by this carbon fiber treatment couch when the beam intersects it. The treatment planning system studied can simulate this treatment couch accurately. Clinical implementation of the described method requires a reliable procedure to reproduce the same patient geometry in the treatment delivery and planning. (Author).

  6. Obtention de couches minces texturées de MoSe2 à partir de feuillets de Mo et de Te

    Science.gov (United States)

    Ouadah, A.; Pouzet, J.; Bemede, J. C.

    1993-01-01

    A process to obtain textured MoSe2 thin films is described. The films are obtained by annealing Mo and Te constituents, in thin films form, under Te and/or Se pressure. The films have been investigated by XPS analysis, X-ray analysis, scanning electron microscopy, transmission electron microscopy and optical and electrical measurements. Stoichiometric and textured MoSe2 thin films can be obtained. Measurements show that the thin films have better cristalline, optical and electrical properties than these of MoSe2 thin films obtained previously. Une méthode d'obtention de couches minces texturées de MoSe2 a été mise au point. Ces couches sont obtenues à partir de feuillets de Mo et de Te successivement superposés, puis traitées thermiquement en présence de vapeur de Te et/ou Se. Les couches obtenues sont étudiées par spectroscopie de photoélectrons (XPS), diffraction de rayons X, microscopie à balayage (MEB), microscopie électronique à transmission (MET) et par mesures optiques et électriques. Les. résultats montrent que des couches minces stcechiométriques et texturées de MoSe2 peuvent être obtenues. Leurs propriétés cristallines sont supérieures à celles obtenues antérieurement comme en témoignent les diagrammes de diffraction des rayons X ainsi que les caractéristiques optiques et électriques.

  7. Eating at the table, on the couch and in bed: An exploration of different locus of commensality in the discourses of Brazilian working mothers.

    Science.gov (United States)

    Scagliusi, Fernanda Baeza; da Rocha Pereira, Patrícia; Unsain, Ramiro Fernandez; de Morais Sato, Priscila

    2016-08-01

    Commensality is a remarkable human act, and tends to be more present among families. Nevertheless, it is possible that eating at the table is being taking for granted when one refers to family meals. Thus, this paper aims to analyze working mothers' discourses about family meals eaten at the table, on the couch and in the bed/bedroom. The participants were thirty mothers working in public universities of the Brazilian region called Baixada Santista. A qualitative study was conducted, using semi-structured interviews. In the transcripts the words "table", "couch", "bed", "bedroom" were located and the excerpts containing them were extracted and analyzed according to a classical and exploratory content analysis. The table is a significant component of meals that unite the family. While for some the meal at the table is an enjoyable moment, it is a stiff moment for others. Indeed, manners and the notion of hierarchy appeared only for the table. Regarding the couch, it seems that the family chose to eat there, because it is a more casual and relaxed setting. Eating in the bed was related to precarity, intimacy and casualness. In the three settings, watching television was a common practice, replacing or being added to talking. Commensality is such an important practice that appears in different settings and even in precarity contexts. The table emerged as the maximal cornerstone of commensality. However, when it was not present, new arrangements were made. Especially the couch seems to be a new commensal space, less formal and rigid, but able to allow some collective conviviality. Eating in the bed was a less common practice. Finally, the significant role that television assumed in meals is highlighted. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. ITV, mid-ventilation, gating or couch tracking - A comparison of respiratory motion-management techniques based on 4D dose calculations.

    Science.gov (United States)

    Ehrbar, Stefanie; Jöhl, Alexander; Tartas, Adrianna; Stark, Luisa Sabrina; Riesterer, Oliver; Klöck, Stephan; Guckenberger, Matthias; Tanadini-Lang, Stephanie

    2017-07-01

    Respiratory motion-management techniques (MMT) aim to ensure tumor dose coverage while sparing lung tissue. Dynamic treatment-couch tracking of the moving tumor is a promising new MMT and was compared to the internal-target-volume (ITV) concept, the mid-ventilation (MidV) principle and the gating approach in a planning study based on 4D dose calculations. For twenty patients with lung lesions, planning target volumes (PTV) were adapted to the MMT and stereotactic body radiotherapy treatments were prepared with the 65%-isodose enclosing the PTV. For tracking, three concepts for target volume definition were considered: Including the gross tumor volume of one phase (single-phase tracking), including deformations between phases (multi-phase tracking) and additionally including tracking latencies of a couch tracking system (reliable couch tracking). The accumulated tumor and lung doses were estimated with 4D dose calculations based on 4D-CT datasets and deformable image registration. Single-phase tracking showed the lowest ipsilateral lung Dmean (median: 3.3Gy), followed by multi-phase tracking, gating, reliable couch tracking, MidV and ITV concepts (3.6, 3.8, 4.1, 4.3 and 4.8Gy). The 4D dose calculations showed the MidV and single-phase tracking overestimated the target mean dose (-2.3% and -1.3%), while it was slightly underestimated by the other MMT (tracking concepts were shown to reduce the lung dose. Neglecting non-translational changes of the tumor in the target volume definition for tracking results in a slightly reduced target coverage. The slightly inferior dose coverage for MidV should be considered when applying this technique clinically. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. SU-F-T-430: Validation of IBEAM Evo Couch Top for Different Relative Electron Density (RED) Combination During Photon Beam Dose Calculation in Monaco− Treatment Planning System

    Energy Technology Data Exchange (ETDEWEB)

    Manigandan, D; Kumar, M; Mohandas, P; Puri, A; Bhalla, N [Fortis Cancer Institute, Mohali, Punjab (India)

    2016-06-15

    Purpose: Validation of iBEAM™ evo couch-top for different relative electron density (RED) combination during photon beam dose calculation in Monaco− TPS. Methods: The iBEAM™ evo couch-top has two layers:outer carbon fiber (CF) and inner foam core (FC). To study the beam intensity attenuation of couch-top, measured doses were compared with doses calculated for different REDs. Measurements were performed in solid water phantom with PTW-0.125cc ion-chamber positioned at center of the phantom with 5.3cm thickness slabs placed above and below the chamber. Similarly, in TPS, iBEAM™ evo couch-top was simulated and doses were calculated for different RED combinations (0.2CF-0.2FC, 0.4CF-0.2FC, 0.6CF-0.2FC, 0.8CF-0.2FC, and 1.0CF-0.2FC) by using Monte Carlo dose calculation algorithm in Monaco TPS (V5.1). Doses were measured for every 10 degree gantry angle separation, 10×10cm{sup 2} field size and 6MV photons. Then, attenuation is defined as the ratio of output at posterior gantry angle to output of its opposed anterior gantry angle (e.g.225°/45°). output fluctuation with different gantry angle was within ±0.21%. To confirm above results, dose-planes were measured for five pelvic VMAT plans (360°arc) in PTW two-dimensional array and compared with different calculated dose-planes of above-mentioned couch REDs. Gamma pass rates<1.00) were analyzed for 3%/2mm criteria. Results: Measured and calculated attenuation was in good agreement for the RED combination of 0.2CF-0.2FC and difference was within ±0.515%. However, other density combination showed difference of ±0.9841%, ±1.667%, ±2.9241% and ±2.8832% for 0.4CF-0.2FC, 0.6CF-0.2FC, 0.8CF-0.2FC, and 1.0CF-0.2FC, respectively. Maximum couch-top attenuation was observed at 110°–120° and 240°–250° and decreases linearly as the gantry angle approaches 180°. Moreover, gamma pass rate confirmed the above results and showed maximum pass rate of 96.23% for 0.2CF-0.2FC, whereas others were 95.72%, 95.12%, 94

  10. La destruction de la couche d'ozone et ses implications en Région wallonne

    OpenAIRE

    Mahieu, Emmanuel

    2007-01-01

    Stratospheric ozone is an important constituent of the Earth's atmosphere since it protects the biosphere from the most harmful ultraviolet radiations emitted by the sun. Some human activiites such as the use of man-mande chlorofluorocarbons have resulted in major destruction of ozone, in particular in the polar regions of the stratosphere. The Montreal Protocol has been successful in limiting the emissions of ozone depleting substances such as the complete ozone recovery is expected to take ...

  11. Evaluation of turbulent transport and flame surface dissipation using direct numerical simulation of turbulent combustion; Evaluation des termes de transport et de dissipation de surface de flamme par simulation numerique directe de la combustion turbulente

    Energy Technology Data Exchange (ETDEWEB)

    Boughanem, H.

    1998-03-24

    The assumption of gradient transport for the mean reaction progress variable has a limited domain of validity in premixed turbulent combustion. The existence of two turbulent transport regimes, gradient and counter-gradient, is demonstrated in the present work using Direct Numerical Simulations (DNS) of plane flame configurations. The DNS data base describes the influence of the heat release factor, of the turbulence-to-flame velocity ratio, and of an external pressure gradient. The simulations reveal a strong correlation between the regime of turbulent transport and the turbulent flame speed and turbulent flame thickness. These effects re not well described by current turbulent combustion models. A conditional approach `fresh gases / burnt gases` is proposed to overcome these difficulties. Furthermore, he development of flame instabilities in turbulent configurations is also observed in the simulations. A criterion is derived that determines the domain of occurrence of these instabilities (Darrieus- Landau instabilities, Rayleigh- Taylor instabilities, thermo-diffusive instabilities). This criterion suggests that the domain of occurrence of flame instabilities is not limited to small Reynolds numbers. (author) 98 refs.

  12. STRUCTURE DE LA TURBULENCE PARIETALE EN PRESENCE DE DIFFERENCE DE DENSITE

    Directory of Open Access Journals (Sweden)

    A SOUDANI

    2002-12-01

    Full Text Available Les effets de différences de densité importantes sur les transferts turbulents en couche limite sont étudiés expérimentalement. Les écarts de densité au sein de la couche limite sont produits par injection tangentielle d’air ou d’hélium dans un mélange de ces deux constituants. Les résultats montrent que la couche limite turbulente obtenue est associé à un gradient de densité normal à la paroi. Pour une vitesse d’injection donnée, les mesures mettent en évidence la conservation du frottement pariétal, et donc l’influence des différences de densité sur la vitesse de frottement. De plus, une forte corrélation entre les variations de densité et de vitesse montre l’influence marquée des structures cohérentes sur les phénomènes de transfert. Les résultats des données expérimentales des fluctuations de vitesse et de densité montrent que le développement spatio-temporel du flux massique turbulent longitudinal est fortement lié aux gradients de densité. La structure du flux massique turbulent ne dépend pas implicitement de la différence de densité mais plutôt de ses gradients. L’analyse dans les quadrants montre que l’injection d’hélium, dans la couche limite, engendre des éjections plus violentes que dans le cas d’une injection d’air. Ce résultat est confirmé par la contribution importante des éjections au flux massique turbulent.

  13. SU-F-T-642: Sub Millimeter Accurate Setup of More Than Three Vertebrae in Spinal SBRT with 6D Couch

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X; Zhao, Z; Yang, J; Yang, J; McAleer, M; Brown, P; Li, J; Ghia, A [MD Anderson Cancer Center, Houston, TX (United States)

    2016-06-15

    Purpose: To assess the initial setup accuracy in treating more than 3 vertebral body levels in spinal SBRT using a 6D couch. Methods: We retrospectively analyzed last 20 spinal SBRT patients (4 cervical, 9 thoracic, 7 lumbar/sacrum) treated in our clinic. These patients in customized immobilization device were treated in 1 or 3 fractions. Initial setup used ExacTrac and Brainlab 6D couch to align target within 1 mm and 1 degree, following by a cone beam CT (CBCT) for verification. Our current standard practice allows treating a maximum of three continuous vertebrae. Here we assess the possibility to achieve sub millimeter setup accuracy for more than three vertebrae by examining the residual error in every slice of CBCT. The CBCT had a range of 17.5 cm, which covered 5 to 9 continuous vertebrae depending on the patient and target location. In the study, CBCT from the 1st fraction treatment was rigidly registered with the planning CT in Pinnacle. The residual setup error of a vertebra was determined by expanding the vertebra contour on the planning CT to be large enough to enclose the corresponding vertebra on CBCT. The margin of the expansion was considered as setup error. Results: Out of the 20 patients analyzed, initial setup accuracy can be achieved within 1 mm for a span of 5 or more vertebrae starting from T2 vertebra to inferior vertebra levels. 2 cervical and 2 upper thoracic patients showed the cervical spine was difficult to achieve sub millimeter accuracy for multi levels without a customized immobilization headrest. Conclusion: If the curvature of spinal columns can be reproduced in customized immobilization device during treatment as simulation, multiple continuous vertebrae can be setup within 1 mm with the use of a 6D couch.

  14. SU-F-T-642: Sub Millimeter Accurate Setup of More Than Three Vertebrae in Spinal SBRT with 6D Couch

    International Nuclear Information System (INIS)

    Wang, X; Zhao, Z; Yang, J; Yang, J; McAleer, M; Brown, P; Li, J; Ghia, A

    2016-01-01

    Purpose: To assess the initial setup accuracy in treating more than 3 vertebral body levels in spinal SBRT using a 6D couch. Methods: We retrospectively analyzed last 20 spinal SBRT patients (4 cervical, 9 thoracic, 7 lumbar/sacrum) treated in our clinic. These patients in customized immobilization device were treated in 1 or 3 fractions. Initial setup used ExacTrac and Brainlab 6D couch to align target within 1 mm and 1 degree, following by a cone beam CT (CBCT) for verification. Our current standard practice allows treating a maximum of three continuous vertebrae. Here we assess the possibility to achieve sub millimeter setup accuracy for more than three vertebrae by examining the residual error in every slice of CBCT. The CBCT had a range of 17.5 cm, which covered 5 to 9 continuous vertebrae depending on the patient and target location. In the study, CBCT from the 1st fraction treatment was rigidly registered with the planning CT in Pinnacle. The residual setup error of a vertebra was determined by expanding the vertebra contour on the planning CT to be large enough to enclose the corresponding vertebra on CBCT. The margin of the expansion was considered as setup error. Results: Out of the 20 patients analyzed, initial setup accuracy can be achieved within 1 mm for a span of 5 or more vertebrae starting from T2 vertebra to inferior vertebra levels. 2 cervical and 2 upper thoracic patients showed the cervical spine was difficult to achieve sub millimeter accuracy for multi levels without a customized immobilization headrest. Conclusion: If the curvature of spinal columns can be reproduced in customized immobilization device during treatment as simulation, multiple continuous vertebrae can be setup within 1 mm with the use of a 6D couch.

  15. Conception et dimensionnement de Systèmes Photovoltaïques : introduction des Modules PV en couches minces dans le logiciel PVsyst

    OpenAIRE

    Mermoud, André

    2005-01-01

    Les nouvelles générations de capteurs photovoltaïques en couches minces (capteurs au silicium amorphe, et autres technologies CIS, CdTe, etc), apparaissent progressivement sur le marché. Certes, ces capteurs présentent des performances (en termes d'efficacité) inférieures aux capteurs classiques, constitués de tranches de silicium mono- ou poly-cristallin. Ils nécessitent donc de plus grandes surfaces de captage pour la même puissance installée. Cependant, leurs techniques de fabrication prés...

  16. SU-F-T-503: Trajectory Modulated Arc Therapy of Intracranial Lesions: Development of a Standardized Path-Based Technique for Fully Dynamic Couch-Gantry Modulated Treatments

    Energy Technology Data Exchange (ETDEWEB)

    Khan, S; Chin, E; Xing, L; Hristov, D; Fahimian, B [Stanford University, Stanford, CA (United States); Otto, K [University of British Columbia, Victoria (Canada)

    2016-06-15

    Purpose: The integration of couch motion during arc delivery is necessitated to enable irradiation trajectories such as coronal arcs, and to enhance the geometrical sampling for dynamic deliveries to the highest extent. To enable such capability, a platform of Trajectory Modulated Arc Therapy (TMAT) is developed in conjunction with standardized noncollisional dynamic path-set for irradiation of intracranial lesions. Methods: A generalized path-set was constructed through the combination of sagittal arcs (45 degrees from the CAX), axial arcs, and coronal arcs produced through modulation of the dynamic rotation of couch. The standardized path was implemented in a contiguous manner enabling the formation of fully automated sub-trajectories to provide maximal geometrical convergence with minimal number of arcs. Progressive sampling technique is used for direct aperture optimization of the MLCs and the selection of couch positions across the control points. Dosimetry of the resulting plans was assessed relative to clinically delivered plans. Using the TrueBeam Developer Mode, plan deliverability was tested. Results: Treatment planning of TMAT sub-trajectories for central, anterior and posterior tumor sites with volumes ranging from 4.75cc to 107cc demonstrated radically reduced doses to the critical OARs when compared to the clinically treated VMAT. Specifically, percentage reduction in mean dose for critical organs such as brainstem, cochlea, and optic nerve are found to be as low as 74±15%, 50±26% and 74±30% respectively as compared to VMAT. Conformity Index, defined as the ratio of tumor volume (VPTV) and 100% dose volume (V(D100%)), was reduced up to 12% while the Gradient Index, defined as V(D100%)/V(D50%), was concurrently improved by up to 14%. Conclusion: An automated standardized trajectory with dynamically modulated couch-gantry arcs has been developed for intracranial radiotherapy. Through the incorporation of coronal arcs, it is demonstrated that

  17. Influences on my clinical practice and identity. Jungian analysis on the couch-what and where is the truth of it?

    Science.gov (United States)

    Schmidt, Martin

    2014-11-01

    The author considers the various influences that have shaped his clinical practice and particular identity as a Jungian analyst. It is hoped that the sharing of these observations will, like a shard of a hologram, reflect aspects of the Jungian community as a whole. The author also attempts to put Jungian analysis 'on the couch' by looking at the current debate in the Journal between traditional and relational psychoanalysis. This is compared to the discourse that philosophy has been struggling with for centuries concerning the nature of truth. © 2014, The Society of Analytical Psychology.

  18. A Contribution to Turbulent Combustion: Premixed Flames and Material Surfaces Une contribution à la combustion turbulente : flammes prémélangées et surfaces des matériaux

    Directory of Open Access Journals (Sweden)

    Nicolleau F.

    2006-11-01

    Full Text Available The behavior of premixed flames has been examined by many authors. In fact the problem of combustion which develops in a turbulent medium depends on two scalings. One makes reference to the scales of the flame the other one is related to the turbulent field. Comparisons between these two scalings allow us to identified what sort of regime is expected. In this paper we first study the development of a material surface which may be identify with a flame front under rather severe conditions. An analytical approach is first used. Hereafter a numerical simulation will be introduced. The role of a fine grained turbulence is more active on the extension of the surface than large structures. To a large extent big eddies convey the surface without distorting it. The risks of extinction are generally predicted by making comparisons between the scales of the flame and the scales of the turbulent field starting from a direct simulation. Poinçot et al show that the smallest structures are not responsible for the extinction : intermediate structures are more efficient than the smallest ones. In a previous paper the role of these structures was examined : the distorting mechanism are acting in a cumulative way. The life time of the smallest structures is too short to have them playing a decive role in the extinction process. Intermediate sized structures are less active but they strain the flame during a longer period. This idea requires a detailed description of the turbulent field. That is made possible by using the ß model which accounts for the location of turbulent structures whose ranks in the whole sequence is termed n . The cumulative role of the velocity gradients is given as a function of n . The influence of the intermediate structure on the extinction process is thereby emphasized. Finally the ß model is also used to describe the domain of distributed combustion zones. Flames propagate in limited regions of space. These regions are disconnected

  19. Experimental and theoretical study of the atmospheric boundary layer over the paris area; Etude experimentale et theorique de la couche limite atmospherique en agglomeration parisienne

    Energy Technology Data Exchange (ETDEWEB)

    Menut, L

    1997-12-15

    This thesis studied the urban boundary layer dynamic behaviour over the Paris area by comparing urban (Paris) and suburban (Palaiseau) dynamic data such as lidars, sodars, sonic anemometers. All the data were obtained during the ECLAP experiment, specifically performed to characterize the differences between a city and its near environment. (author)

  20. Special Course on Shock-Wave/Boundary-Layer Interactions in Supersonic and Hypersonic Flows (Interactions entre Ondes de Choc et Couches Limites dans les Ecoulements Supersoniques et Hpersoniques).

    Science.gov (United States)

    1993-08-01

    Laser Corp.) was used as the flow was well-mixed in the wind tunnel stilling a light source. More recently, a 5-Watt Argon -Ion chamber by capturing...component capability, the ve- scattering mode. For all the tests presented here, the locimeter is equipped with two identical Argon lasers that forward...Directour dui Service des=oe o~us LUXEMBOURG Mmisirede l Ddw NVoireldgique Ottawa, Ontario KIA 0K2 I4ORVEGE DANEMAIU( Norwegia Defence Research

  1. SU-F-BRE-10: Methods to Simulate and Measure the Attenuation for Modeling a Couch Top with Rails for FFF Treatment Delivery On the Varian Edge Linac

    International Nuclear Information System (INIS)

    Gulam, M; Gardner, S; Zhao, B; Snyder, K; Song, K; Li, H; Gordon, J; Wen, N; Chetty, I; Kearns, W

    2014-01-01

    Purpose: To measure attenuation for modelling of the KVue Couchtop for 6X and 10X FFF SRS/SBRT treatment Methods: Treatment planning simulation studies were done using 6X FFF beams to estimate the dosimetric impact of KVue couchtops (including the Q-Fix IGRT [carbon fiber] and Calypso [nonconductive Kevlar material]) with a structure model obtained from a research workstation (Eclipse, advanced planning interface (API) v13). Prior to installation on the Varian Edge linac, the couchtop along with (Kevlar) rails were CT scanned with the rails at various positions. An additional scan with the couchtop 15cm above the CT table top was obtained with 20cm solid water to facilitate precised/indexed data acquisition. Measurements for attenuation were obtained for field sizes of 2, 4 and 10 cm 2 at 42 gantry angles including 6 pairs of opposing fields and other angles for oblique delivery where the beams traversed the couchtop and or rails. The delivery was fully automated with xml scripts running in developer mode. The results were then used to determine an accurate structure model for AAA (Eclipse v11) planning of IMRT and RapidArc delivery. Results: The planning simulation relative dose attenuation for oblique entry was not significantly different than the Exact IGRT or BrainLab iBeam couch except that the rails added 6% additional attenuation. The relative attenuation measurements for PA, PA (rails: inner position), oblique, oblique (rails: outer position), oblique (rails: inner position) were: −2.0%, −2.5%, −15.6%, −2.5%, −5.0% for 6X FFF and −1.4%, −1.5%, −12.2%, − 2.5%, −5.0% for 10X FFF with slight decrease in attenuation versus field size. A Couch structure model (with HU values) was developed. Calculation compared to measurement showed good agreement except for oblique (rails: outer position) where differences approached a magnitude of 6%. Conclusion: A model of the couch structures has been developed accounting for attenuation for FFF beams

  2. SU-F-BRE-10: Methods to Simulate and Measure the Attenuation for Modeling a Couch Top with Rails for FFF Treatment Delivery On the Varian Edge Linac

    Energy Technology Data Exchange (ETDEWEB)

    Gulam, M; Gardner, S; Zhao, B; Snyder, K; Song, K; Li, H; Gordon, J; Wen, N; Chetty, I [Henry Ford Health System, Detroit, MI (United States); Kearns, W [Varian Medical Systems, Clemmons, NC (United States)

    2014-06-15

    Purpose: To measure attenuation for modelling of the KVue Couchtop for 6X and 10X FFF SRS/SBRT treatment Methods: Treatment planning simulation studies were done using 6X FFF beams to estimate the dosimetric impact of KVue couchtops (including the Q-Fix IGRT [carbon fiber] and Calypso [nonconductive Kevlar material]) with a structure model obtained from a research workstation (Eclipse, advanced planning interface (API) v13). Prior to installation on the Varian Edge linac, the couchtop along with (Kevlar) rails were CT scanned with the rails at various positions. An additional scan with the couchtop 15cm above the CT table top was obtained with 20cm solid water to facilitate precised/indexed data acquisition. Measurements for attenuation were obtained for field sizes of 2, 4 and 10 cm{sup 2} at 42 gantry angles including 6 pairs of opposing fields and other angles for oblique delivery where the beams traversed the couchtop and or rails. The delivery was fully automated with xml scripts running in developer mode. The results were then used to determine an accurate structure model for AAA (Eclipse v11) planning of IMRT and RapidArc delivery. Results: The planning simulation relative dose attenuation for oblique entry was not significantly different than the Exact IGRT or BrainLab iBeam couch except that the rails added 6% additional attenuation. The relative attenuation measurements for PA, PA (rails: inner position), oblique, oblique (rails: outer position), oblique (rails: inner position) were: −2.0%, −2.5%, −15.6%, −2.5%, −5.0% for 6X FFF and −1.4%, −1.5%, −12.2%, − 2.5%, −5.0% for 10X FFF with slight decrease in attenuation versus field size. A Couch structure model (with HU values) was developed. Calculation compared to measurement showed good agreement except for oblique (rails: outer position) where differences approached a magnitude of 6%. Conclusion: A model of the couch structures has been developed accounting for attenuation for FFF

  3. Maintien de la couverture de surface dans les réseaux de capteurs avec une couche physique non idéale

    OpenAIRE

    Gallais , Antoine; Ingelrest , Francois; Carle , Jean; Simplot-Ryl , David

    2006-01-01

    Nous considérons le problème de la couverture de surface dans les réseaux de capteurs lorsqu'une couche physique non idéale est utilisée, la plupart des travaux récents dans ce domaine ayant été effectués dans un environnement idéal. Dans cette étude, nous montrons qu'un protocole prévu pour un tel environnement ne peut que difficilement fonctionner en l'état dans un milieu plus réaliste. Dans ce but, nous analysons avec le modèle du masquage lognormal un protocole localisé répandu dans la li...

  4. Méthodes d'accès basées sur le codage réseau couche physique

    OpenAIRE

    BUI, Huyen Chi

    2012-01-01

    Dans le domaine des réseaux satellitaires, l'apparition de terminaux interactifs à bas-prix nécessite le développement et la mise en œuvre de protocoles d'accès multiple capables de supporter différents profils d'utilisateurs. En particulier, l'Agence Spatiale Européenne (ESA) et le centre d'étude spatial allemand (DLR) ont récemment proposé des protocoles d'accès aléatoires basés sur le codage réseau couche physique et l'élimination itérative des interférences pour résoudre en partie le prob...

  5. Transport dans la couche d'inversion d'un transistor MOS. Utilité du formalisme de Kubo-Greenwood

    OpenAIRE

    Ghibaudo , G.

    1986-01-01

    Une étude du transport électronique dans la couche d'inversion d'un transistor MOS est présentée. L'utilisation du formalisme de Kubo-Greenwood rend possible l'explication du comportement global des coefficients de transport (conductivité, mobilité, ...) du régime d'inversion faible au régime d'inversion forte sur une gamme étendue de température. En particulier, il est montré que des phénomènes physiques découlant de la miniaturisation et/ou d'un fonctionnement à basse température, tels que ...

  6. Les mécanismes d'action des détergents et les doubles couche électriques aux interfaces Action Mechanisms of Detergents and Double Electric Layer At Interfaces

    Directory of Open Access Journals (Sweden)

    Briant J.

    2006-11-01

    Full Text Available Les doubles couches électriques aux interfaces jouent un rôle important dans l'action des additifs détergents ioniques, surtout dans la stabilisation des suspensions. Les phénomènes électrocinétiques aux interfaces : électroosmose, potentiel d'écoulement, électrophorèse, potentiel de sédimentation permettent de mettre en évidence la double couche électrique et d'en déterminer certaines caractéristiques signe de la charge de la couche mobile, potentiel électrocinétique, etc. Les relations entre la stabilité des suspensions et l'interaction des doubles couches électriques ont fait l'objet d'études approfondies de Deriaguin, Verwey et Overbeek. Ces auteurs ont analysé le mécanisme d'action des doubles couches électriques et la façon dont elles pouvaient créer des forces de répulsion capables de surmonter les forces d'attraction de Van der Waals entre particules. Leur analyse permet d'expliquer les observations faites sur les effets de la charge des particules, la nature des ions fixés, la concentration de la phase dispersante en produits actifs. Le mécanisme d'action des doubles couches électriques permet peut-être d'appréhender mieux le mécanisme d'action des additifs non ioniques. Double electric loyers at interfaces play an important part in the action of ionic detergent additives, especially in the stability of suspensions. Electrokinetic phenomena at interfaces (electroosmosis,flow potential, electrophoresis, sedimentation potential can be used to reveal the double electric layer and to determine various properties such as the sign of the charge of the mobile loyer, the electrokinetic potential, etc. The relations between the stabillity of suspensions and the interaction of double electric loyers have been the subject of in-depth research by Deriaguin, Verwey and Overbeek. The authors have analyzed the action mechanism of double electric loyers and the way they can create repulsion forces capable of overcoming

  7. Étude de la cinétique de croissance des couches minces de sulfure d'argent préparées par dépôt chimique en solution

    Science.gov (United States)

    Meherzi Maghraoui, H.; Cowache, P.; Lincot, D.; Dachraoui, M.

    1999-02-01

    The growth kinetics of silver sulfide films chemically deposited from aqueous silver nitrate-thiourea solutions at pH around 9 is studied as a function of the concentrations in solution, temperature (40 to 80 °C) and hydrodynamic regime. It is found that the growth takes place in a narrow pH window (8.8 to 9.4). It is activated by temperature with an apparent activation energy of 20.4 kJ.mol-1, which is coherent with a diffusion control evidenced by experiments at different hydrodynamic regimes. The overall rate equation has been determined. The ultimate thickness of the films (around 1-2 microns) is actually limited by a parasitic process attributed to unsticking. Cette étude concerne la croissance de couches minces de sulfure d'argent par dépôt chimique en solution (C.B.D) en présence de nitrate d'argent et de thiourée dans des conditions de pH légèrement basique (pH = 9) et à une température comprise entre (40 et 80 °C). L'équation de vitesse globale a été établie dans la fenêtre expérimentale de croissance. Le mécanisme réactionnel est sous contrôle diffusionnel avec une énergie d'activation apparente de 20,4 kJ.mol-1 et met probablement en jeu des étapes élémentaires. La croissance s'effectue en parallèle avec la réaction de précipitation en phase homogène. L'épaisseur des films peut atteindre 1,6 micron. Elle est actuellement limitée par un phénomène attribué à un décollement du substrat.

  8. Current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Loescher, D.H. [Sandia National Labs., Albuquerque, NM (United States). Systems Surety Assessment Dept.; Noren, K. [Univ. of Idaho, Moscow, ID (United States). Dept. of Electrical Engineering

    1996-09-01

    The current that flows between the electrical test equipment and the nuclear explosive must be limited to safe levels during electrical tests conducted on nuclear explosives at the DOE Pantex facility. The safest way to limit the current is to use batteries that can provide only acceptably low current into a short circuit; unfortunately this is not always possible. When it is not possible, current limiters, along with other design features, are used to limit the current. Three types of current limiters, the fuse blower, the resistor limiter, and the MOSFET-pass-transistor limiters, are used extensively in Pantex test equipment. Detailed failure mode and effects analyses were conducted on these limiters. Two other types of limiters were also analyzed. It was found that there is no best type of limiter that should be used in all applications. The fuse blower has advantages when many circuits must be monitored, a low insertion voltage drop is important, and size and weight must be kept low. However, this limiter has many failure modes that can lead to the loss of over current protection. The resistor limiter is simple and inexpensive, but is normally usable only on circuits for which the nominal current is less than a few tens of milliamperes. The MOSFET limiter can be used on high current circuits, but it has a number of single point failure modes that can lead to a loss of protective action. Because bad component placement or poor wire routing can defeat any limiter, placement and routing must be designed carefully and documented thoroughly.

  9. Quench limits

    International Nuclear Information System (INIS)

    Sapinski, M.

    2012-01-01

    With thirteen beam induced quenches and numerous Machine Development tests, the current knowledge of LHC magnets quench limits still contains a lot of unknowns. Various approaches to determine the quench limits are reviewed and results of the tests are presented. Attempt to reconstruct a coherent picture emerging from these results is taken. The available methods of computation of the quench levels are presented together with dedicated particle shower simulations which are necessary to understand the tests. The future experiments, needed to reach better understanding of quench limits as well as limits for the machine operation are investigated. The possible strategies to set BLM (Beam Loss Monitor) thresholds are discussed. (author)

  10. Dose limits

    International Nuclear Information System (INIS)

    Fitoussi, L.

    1987-12-01

    The dose limit is defined to be the level of harmfulness which must not be exceeded, so that an activity can be exercised in a regular manner without running a risk unacceptable to man and the society. The paper examines the effects of radiation categorised into stochastic and non-stochastic. Dose limits for workers and the public are discussed

  11. Inverse Limits

    CERN Document Server

    Ingram, WT

    2012-01-01

    Inverse limits provide a powerful tool for constructing complicated spaces from simple ones. They also turn the study of a dynamical system consisting of a space and a self-map into a study of a (likely more complicated) space and a self-homeomorphism. In four chapters along with an appendix containing background material the authors develop the theory of inverse limits. The book begins with an introduction through inverse limits on [0,1] before moving to a general treatment of the subject. Special topics in continuum theory complete the book. Although it is not a book on dynamics, the influen

  12. Cone beam CT imaging with limited angle of projections and prior knowledge for volumetric verification of non-coplanar beam radiation therapy: a proof of concept study

    International Nuclear Information System (INIS)

    Meng, Bowen; Xing, Lei; Han, Bin; Koong, Albert; Chang, Daniel; Li, Ruijiang; Cheng, Jason

    2013-01-01

    Non-coplanar beams are important for treatment of both cranial and noncranial tumors. Treatment verification of such beams with couch rotation/kicks, however, is challenging, particularly for the application of cone beam CT (CBCT). In this situation, only limited and unconventional imaging angles are feasible to avoid collision between the gantry, couch, patient, and on-board imaging system. The purpose of this work is to develop a CBCT verification strategy for patients undergoing non-coplanar radiation therapy. We propose an image reconstruction scheme that integrates a prior image constrained compressed sensing (PICCS) technique with image registration. Planning CT or CBCT acquired at the neutral position is rotated and translated according to the nominal couch rotation/translation to serve as the initial prior image. Here, the nominal couch movement is chosen to have a rotational error of 5° and translational error of 8 mm from the ground truth in one or more axes or directions. The proposed reconstruction scheme alternates between two major steps. First, an image is reconstructed using the PICCS technique implemented with total-variation minimization and simultaneous algebraic reconstruction. Second, the rotational/translational setup errors are corrected and the prior image is updated by applying rigid image registration between the reconstructed image and the previous prior image. The PICCS algorithm and rigid image registration are alternated iteratively until the registration results fall below a predetermined threshold. The proposed reconstruction algorithm is evaluated with an anthropomorphic digital phantom and physical head phantom. The proposed algorithm provides useful volumetric images for patient setup using projections with an angular range as small as 60°. It reduced the translational setup errors from 8 mm to generally <1 mm and the rotational setup errors from 5° to <1°. Compared with the PICCS algorithm alone, the integration of rigid

  13. Etude des transistors MOSFET à barrière Schottky, à canal Silicium et Germanium sur couches minces

    OpenAIRE

    Hutin , Louis

    2010-01-01

    Until the early 2000’s Dennard’s scaling rules at the transistor level have enabled to achieve a performance gain while still preserving the basic structure of the MOSFET building block from one generation to the next. However, this conservative approach has already reached its limits as shown by the introduction of channel stressors for the sub-130 nm technological nodes, and later high-k/metal gate stacks for the sub-65 nm nodes. Despite the introduction of high-k gate dielectrics, constrai...

  14. An Intronic Polymorphism in couch potato Is Not Distributed Clinally in European Drosophila melanogaster Populations nor Does It Affect Diapause Inducibility.

    Science.gov (United States)

    Zonato, Valeria; Fedele, Giorgio; Kyriacou, Charalambos P

    2016-01-01

    couch potato (cpo) encodes an RNA binding protein that has been reported to be expressed in the peripheral and central nervous system of embryos, larvae and adults, including the major endocrine organ, the ring gland. A polymorphism in the D. melanogaster cpo gene coding region displays a latitudinal cline in frequency in North American populations, but as cpo lies within the inversion In(3R)Payne, which is at high frequencies and itself shows a strong cline on this continent, interpretation of the cpo cline is not straightforward. A second downstream SNP in strong linkage disequilibrium with the first has been claimed to be primarily responsible for the latitudinal cline in diapause incidence in USA populations.Here, we investigate the frequencies of these two cpo SNPs in populations of Drosophila throughout continental Europe. The advantage of studying cpo variation in Europe is the very low frequency of In(3R)Payne, which we reveal here, does not appear to be clinally distributed. We observe a very different geographical scenario for cpo variation from the one in North America, suggesting that the downstream SNP does not play a role in diapause. In an attempt to verify whether the SNPs influence diapause we subsequently generated lines with different combinations of the two cpo SNPs on known timeless (tim) genetic backgrounds, because polymorphism in the clock gene tim plays a significant role in diapause inducibility. Our results reveal that the downstream cpo SNP does not seem to play any role in diapause induction in European populations in contrast to the upstream coding cpo SNP. Consequently, all future diapause studies on strains of D. melanogaster should initially determine their tim and cpo status.

  15. "Not Homeless Yet. I'm Kind of Couch Surfing": Finding Identities for People at a Homeless Shelter.

    Science.gov (United States)

    Terui, Sachiko; Hsieh, Elaine

    2016-01-01

    The meanings of homelessness are fluid and socially constructed, providing resources and limitations for individuals to negotiate their identities and relationships in everyday life. In this study, we examine the strategies and corresponding resources utilized by people who are homeless to cope with the labeling of a homeless identity and to redefine their identities. We used constant comparative analysis to examine in-depth interviews with 16 participants (male = 11, female = 5) who access a local homeless shelter in the southwest United States for resources. We identified three strategies that homeless people adopt to cope with the labeling of homeless identity: (a) differentiating oneself from others who are homeless, (b) prioritizing certain aspects of life, and (c) embracing the status of homelessness. Although these strategies have been identified in previous literature, the authors extend this line of research by identifying the common resources people who are homeless utilize when adopting these strategies, which entail important implications for theory development and practical implications.

  16. It's Not About "Freudian Couches and Personality Changing Drugs": An Investigation Into Men's Mental Health Help-Seeking Enablers.

    Science.gov (United States)

    Harding, Christine; Fox, Christopher

    2015-11-01

    Enabling factors that influenced men to seek assistance for mental health concerns--a previous underresearched area--was the primary focus of this research. Past research spanning four decades has focused on men's barriers to mental health help-seeking with limited research positing social norms within men's peer groups and reciprocity as potential mental health help-seeking enablers. Using a qualitative design, nine men were interviewed to identify the positive factors they believed assisted their help-seeking decisions. Social norms, reciprocity, a significant other, and helpfulness of their general practitioner were domains identified in the analysis of participant narratives. The study revealed the participants' mental health and treatment illiteracy. Ignorance and misplaced stereotypes, initially acted as barriers to help-seeking, leading to denial of illness, impeding treatment, and perpetuating stigma. Sportsmen disclosing their mental health issues were identified as a positive influence for other men's help-seeking and assisted in the development of help-seeking as a social norm. The results of this study contribute to understanding the factors that enable men to seek mental health help. © The Author(s) 2014.

  17. Age Limits

    OpenAIRE

    Jan Antfolk

    2017-01-01

    Whereas women of all ages prefer slightly older sexual partners, men—regardless of their age—have a preference for women in their 20s. Earlier research has suggested that this difference between the sexes’ age preferences is resolved according to women’s preferences. This research has not, however, sufficiently considered that the age range of considered partners might change over the life span. Here we investigated the age limits (youngest and oldest) of considered and actual sex partners in...

  18. Positioning accuracy during VMAT of gynecologic malignancies and the resulting dosimetric impact by a 6-degree-of-freedom couch in combination with daily kilovoltage cone beam computed tomography

    International Nuclear Information System (INIS)

    Yao, Lihong; Zhu, Lihong; Wang, Junjie; Liu, Lu; Zhou, Shun; Jiang, ShuKun; Cao, Qianqian; Qu, Ang; Tian, Suqing

    2015-01-01

    To improve the delivery of radiotherapy in gynecologic malignancies and to minimize the irradiation of unaffected tissues by using daily kilovoltage cone beam computed tomography (kV-CBCT) to reduce setup errors. Thirteen patients with gynecologic cancers were treated with postoperative volumetric-modulated arc therapy (VMAT). All patients had a planning CT scan and daily CBCT during treatment. Automatic bone anatomy matching was used to determine initial inter-fraction positioning error. Positional correction on a six-degrees-of-freedom (6DoF) couch was followed by a second scan to calculate the residual inter-fraction error, and a post-treatment scan assessed intra-fraction motion. The margins of the planning target volume (M PTV ) were calculated from these setup variations and the effect of margin size on normal tissue sparing was evaluated. In total, 573 CBCT scans were acquired. Mean absolute pre-/post-correction errors were obtained in all six planes. With 6DoF couch correction, the M PTV accounting for intra-fraction errors was reduced by 3.8–5.6 mm. This permitted a reduction in the maximum dose to the small intestine, bladder and femoral head (P = 0.001, 0.035 and 0.032, respectively), the average dose to the rectum, small intestine, bladder and pelvic marrow (P = 0.003, 0.000, 0.001 and 0.000, respectively) and markedly reduced irradiated normal tissue volumes. A 6DoF couch in combination with daily kV-CBCT can considerably improve positioning accuracy during VMAT treatment in gynecologic malignancies, reducing the M PTV . The reduced margin size permits improved normal tissue sparing and a smaller total irradiated volume

  19. SU-E-J-138: An IGRT QA Device for Measuring with Tenths-Millimeter Accuracy KV and MV Isocenter Congruence, Couch Travel and Laser Alignment of Accelerators Used for SRS and SBRT

    Energy Technology Data Exchange (ETDEWEB)

    Brezovich, I; Popple, R; Duan, J; Huang, M; Benhabib, S; Shen, S; Cardan, R; Wu, X [University of Alabama Birmingham, Birmingham, AL (United States)

    2014-06-01

    Purpose: To develop a practical device having sufficient accuracy for daily QA tests of accelerators used for SRS and SBRT. Methods: The UAB (Universal Alignment Ball) consists of a 6.35 mm (1/4 inch) diameter tungsten sphere located concentrically within a 25.4 mm (1 inch) diameter acrylic plastic (PMMA) sphere. The spheres are embedded in polystyrene foam, which, in turn, is surrounded by a cylindrical PMMA shell. The UAB is placed on the couch and aligned with wall lasers according to marks that have known positions in relation to the center of the spheres. Using planar and cone beam images the couch is shifted till the surface of the PMMA sphere matches Eclipse-generated circular contours. Anterior and lateral MV images taken with small MLC openings allow measurement of distance between kV and MV isocenter, laser and MLC alignment. Measurements were taken over a one-month period. Results: Artifacts from the tungsten sphere were confined within the PMMA sphere and did not affect cone beam localization of the sphere boundary, allowing 0.1 mm precise alignment with a computer-generated circle centered at kV isocenter. In tests extending over a one-month period, the distance between kV and MV isocenters along the vertical, longitudinal and lateral directions was 0.125 +/−0.06, 0.19 +/−0.08, and 0.02 +/−0.08 mm, respectively. Laser misalignment along these directions was 0.34 +/- 0.15, 0.74 +/−0.29, and 0.49 +/−0.22 mm. Automated couch shifts moved the spheres to within 0.1 mm of the selected position. The center of a 1cmx1cm MLC-defined field remained within +/−0.2 mm of the tungsten sphere center as the gantry was rotated. Conclusion: The UAB is practical for daily end-to-end QA tests of accelerator alignment. It provides tenths-mm accuracy for measuring agreement of kV and MV isocenters, couch motions, gantry flex and laser alignment.

  20. Formalisme rationnel le la méthode de détermination des contraintes résiduelles par diffraction des rayons X: application aux couches minces et multicouches

    OpenAIRE

    Badawi , K.; Kahloun , C.; Grilhé , J.

    1993-01-01

    L'utilisation du formalisme rationnel dans la méthode de détermination des contraintes résiduelles par diffraction des rayons X améliore la rigueur, la précision et l'élégance mathématique de la méthode. Elle permet d'éviter les approximations faites dans le formalisme conventionnel, et apporte des corrections qui dépassent 15 % dans certains cas de couches minces et de multicouches.

  1. Le dépôt de diamant en couche mince et ses applications Thin-Layer Diamond Depositing and Its Applications

    Directory of Open Access Journals (Sweden)

    Bertrand A.

    2006-11-01

    Full Text Available Nous avons cherché à faire le point sur la fabrication de couches minces de diamant qui, après avoir été très étudiée aux États-Unis vers la fin des années 1950, a fait l'objet d'une percée technologique soviétique en 1977. Celle-ci utilise l'effet solvant de l'hydrogène mélangé à un peu de méthane. Transformé en hydrogène atomique par décharge électrique, il interdit le dépôt de graphite et par conséquent permet seulement celui du diamant. Ce résultat est riche d'applications prometteuses en mécanique, en optique, en électronique. . . et constitue un élément clé pour la recherche spatiale. Les Japonais ont mis cinq ans pour réagir et les Américains cinq autres années. Mais ces derniers espèrent refaire leur retard grâce au programme Diamond Technology Initiative établi dans le cadre de l'initiative de Défense Stratégique (Guerre des Étoiles. Les retombées de ces travaux devraient concerner l'industrie pétrolière (paliers, trépans, capteurs en milieu extrême. This article reviews the depositing of diamond thin layers. After much research had been done on this technique in the United States in the late 1950s, a technological breakthrough was made by the Soviets in 1977. This breakthrough uses the solventeffect of hydrogen mixed with a bit of methane. This is transformed into atomic hydrogen by an electric discharge, thus preventing graphite from being deposited and hence enabling only diamond to be deposited. This achievement has a wealth of promising applications in mechanics, optics, electronics, etc. It is also a key element for space research. The Japanese took five years to react and the Americans another five years. But these latter hope to make up for lost time with the Diamond Technology Initiativepromoted within the framework of the Strategic Defense Initiative ( star wars . The fallouts from this research should involve the petroleum industry (bearings, drill bits, sensors in extreme

  2. Effet de la température de fabrication sur les propriétés structurales et morphologiques des couches épaisses de In2S3 ``spray"

    Science.gov (United States)

    Bouguila, N.; Bouzouita, H.; Lacaze, E.; Belhadj Amara, A.; Bouchriha, H.; Dhouib, A.

    1997-08-01

    We have investigated the substrate temperature effect on structural and morphological properties of thick layers deposited on glass substrate by spray method. X-ray diffraction has shown that the In2S3 is the main phase present in these films and that the structure and the allotropic form of this phase are affected by the substrate temperature. Analysis of these layers by Scanning Electronic Microscopy (SEM) and by Atomic Force Microscopy (AFM) revealed that a best crystallinity and homogeneity are approximately obtained for T_s = 613 K. Nous avons étudié l'effet de la température du substrat sur les propriétés structurales et morphologiques de couches de In2S3 déposées sur des lames de verre par la méthode de spray. La diffraction des rayons X a montré que L'In2S3 est la phase principale présente dans ces films et que la structure et la forme allotropique de cette phase sont affectées par la température du substrat. L'analyse de ces couches par Microscopie Électronique à Balayage (MEB) et par Microscopie à Force Atomique (MFA) a montré qu'une meilleure cristallinité et une meilleure homogénéité sont obtenues pour des températures du substrat voisines de 613 K.

  3. Age Limits.

    Science.gov (United States)

    Antfolk, Jan

    2017-03-01

    Whereas women of all ages prefer slightly older sexual partners, men-regardless of their age-have a preference for women in their 20s. Earlier research has suggested that this difference between the sexes' age preferences is resolved according to women's preferences. This research has not, however, sufficiently considered that the age range of considered partners might change over the life span. Here we investigated the age limits (youngest and oldest) of considered and actual sex partners in a population-based sample of 2,655 adults (aged 18-50 years). Over the investigated age span, women reported a narrower age range than men and women tended to prefer slightly older men. We also show that men's age range widens as they get older: While they continue to consider sex with young women, men also consider sex with women their own age or older. Contrary to earlier suggestions, men's sexual activity thus reflects also their own age range, although their potential interest in younger women is not likely converted into sexual activity. Compared to homosexual men, bisexual and heterosexual men were more unlikely to convert young preferences into actual behavior, supporting female-choice theory.

  4. Age Limits

    Directory of Open Access Journals (Sweden)

    Jan Antfolk

    2017-01-01

    Full Text Available Whereas women of all ages prefer slightly older sexual partners, men—regardless of their age—have a preference for women in their 20s. Earlier research has suggested that this difference between the sexes’ age preferences is resolved according to women’s preferences. This research has not, however, sufficiently considered that the age range of considered partners might change over the life span. Here we investigated the age limits (youngest and oldest of considered and actual sex partners in a population-based sample of 2,655 adults (aged 18-50 years. Over the investigated age span, women reported a narrower age range than men and women tended to prefer slightly older men. We also show that men’s age range widens as they get older: While they continue to consider sex with young women, men also consider sex with women their own age or older. Contrary to earlier suggestions, men’s sexual activity thus reflects also their own age range, although their potential interest in younger women is not likely converted into sexual activity. Compared to homosexual men, bisexual and heterosexual men were more unlikely to convert young preferences into actual behavior, supporting female-choice theory.

  5. On the Boltzmann-Grad Limit for Smooth Hard-Sphere Systems

    Science.gov (United States)

    Tessarotto, Massimo; Cremaschini, Claudio; Mond, Michael; Asci, Claudio; Soranzo, Alessandro; Tironi, Gino

    2018-03-01

    The problem is posed of the prescription of the so-called Boltzmann-Grad limit operator (L_{BG}) for the N-body system of smooth hard-spheres which undergo unary, binary as well as multiple elastic instantaneous collisions. It is proved, that, despite the non-commutative property of the operator L_{BG}, the Boltzmann equation can nevertheless be uniquely determined. In particular, consistent with the claim of Uffink and Valente (Found Phys 45:404, 2015) that there is "no time-asymmetric ingredient" in its derivation, the Boltzmann equation is shown to be time-reversal symmetric. The proof is couched on the "ab initio" axiomatic approach to the classical statistical mechanics recently developed (Tessarotto et al. in Eur Phys J Plus 128:32, 2013). Implications relevant for the physical interpretation of the Boltzmann H-theorem and the phenomenon of decay to kinetic equilibrium are pointed out.

  6. Effets de l'interaction avec l'oxygène sur le comportement de couches semi-conductrices de ZnO, SnO{2} et CdSe

    Science.gov (United States)

    Ain-Souya, A.; Ghers, M.; Haddad, A.; Tebib, W.; Rehamnia, R.; Messsalhi, A.; Bounouala, M.; Djouama, M. C.

    2005-05-01

    Les propriétés superficielles des matériaux solides diffèrent de celles du volume. A la surface, des défauts de différentes natures peuvent être présents. Ils permettent à la surface d'être interactive avec le milieu ambiant. Les multiples interactions entre les états de surface et des éléments du milieu extérieur peuvent modifier les propriétés superficielles. Ce travail étudie la régénération de couches semi-conductrices après adsorption isotherme d'oxygène à différentes températures effectuées entre 20 ° C et 300 ° C. Les matériaux qui ont servi à l'étude sont des couches de ZnO, SnO{2} et CdSe. Celles de CdSe ont été obtenues par co-évaporation, sous vide, de cadmium et de sélénium. Les échantillons de ZnO et SnO{2} ont été élaborés par oxydation, à des températures respectives de 450 ° C et 200 ° , de Zn et Sn déposés par électrolyse et par évaporation sous vide. Les matériaux évaporés ont été déposés sur des plaquettes en verre, les autres ont été électrodéposés sur des substrats métalliques. Les variations des propriétés électriques des couches ont été suivies par mesure de leur résistance électrique superficielle R. Les courbes LogR = f (103 /T (K)), relevées sous vide à différentes températures, sont caractéristiques d'un comportement de semi-conducteur. Des essais d'adsorption d'O{2} à différentes températures montrent des variations considérables de R. En effet, la chimisorption forte d'un gaz par une surface semi-conductrice est telle que l'échange électronique entre adsorbant et adsorbat provoque la formation d'une zone de charge d'espace modifiant la conduction superficielle. Les résultats mettent en évidence des domaines de température de plus haute sensibilité à l'oxygène. Pour le CdSe, certaines désorptions isothermes ont été suffisantes pour une régénération totale des échantillons. Les couches de ZnO ont souvent nécessité des désorptions programm

  7. Alliages magnétiques FePd et FePt en couches minces sous contrainte épitaxiale : mise en ordre en température et propriétés magnétiques

    Science.gov (United States)

    Arenal de La Concha, R.; Schuster, I.; Halley, D.; Marty, A.; Bayle-Guillemaud, P.

    2002-07-01

    In order to increase the storage capacities of the media of magnetic recording one seeks to decrease the size of the magnetic fields which carry information. The growth of thin layers of magnetic alloys in ordered phases makes it possible to plan structures with very strong perpendicular magnetic anisotropy, necessary to obtain stable fields in spite of their reduced size. We studied, thanks to an original device of in temperature X-rays diffraction, the ordering of FePd layers or FePt deposited by MBE in different states of initial order and constraint, then submitted to heat treatment. The ordering occured along the growth axis. The structure of the layers is very inhomogeneous: not ordered and ordered domains coexist, with or without defect in the stacking of the L10 phase, even domains of other phases. The small zones, which have been ordered during the growth, do not seem to take part in the development of the long range order during the treatment. The evolution of the ordered fraction is identical whatever the imposed state of epitaxial stress. Modifications of the experimental conditions make it possible from now to plan more systematic measurements with a temperature history more rigorous in order to confirm these observations. Afin d'augmenter les capacités de stockage des media d'enregistre ment magnétique, on cherche à diminuer la taille des domaines magnétiques qui portent l'information. L'élaboration de couches minces d'alliages magnétiques dans des phases ordonnées permet d'envisager des structures à très forte anisotropie magnétique perpendiculaire, nécessaire pour obtenir des domaines stables malgré leur taille réduite. Nous avons étudié, grâce à un dispositif original de diffraction X en température, la mise en ordre de couches FePd ou FePt déposées par MBE dans des états différents d'ordre initial et de contrainte. La mise en ordre se fait selon l'axe de croissance. La structure des couches est très inhomogène : coexistent

  8. Thermal and hydrodynamic study of a whirling liquid hydrogen layer under high heat flux; Etude thermique et hydrodynamique d'une couche tourbillonnaire d'hydrogenen liquide sous flux de chaleur eleve

    Energy Technology Data Exchange (ETDEWEB)

    Ewald, R. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1968-03-01

    In order to achieve a cold neutrons source ({lambda} {>=} 4.10{sup -10} m) in a high flux reactor ({approx} 10{sup 15} neutrons/cm{sup 2}.s), a whirling liquid hydrogen layer (145 mm OD, effective thickness 15 mm, height about 180 mm) was formed, out-of-pile, in a cylindrical transparent glass vessel. The whirling motion was obtained by tangential injection of the liquid, near the wall. Thermal and hydrodynamical conditions of formation and laws of similarity of such a layer were studied. The characteristics of this whirling flow were observed as a function of mass flow rate (5 to 27 g/s; 4.3 to 23 l/mn), and of spillway width (18 and 25 mm). Six different nozzles were used : 1.0; 1.5; 1.9; 2.25; 2.65 and 3.0 mm ID. The total heat influx was found between 8.6 and 10.4 kW. The heat flux density was about 9.4 W/cm{sup 2} and the mean layer density around 80 per cent of that of the liquid hydrogen at 20.4 Kelvin. High speed movies were used to analyze the boiling regime. (author) [French] En vue de realiser une source de neutrons froids ({lambda} {>=} 4.10{sup -10} m) dans un reacteur a haut flux ({approx} 10{sup 15} neutrons thermiques/cm{sup 2}.s), on a forme dans un vase cylindrique transparent en verre, hors-pile, une couche tourbillonnaire ('vortex') d'hydrogene liquide (diametre exterieur 145 mm, epaisseur effective 15 mm, hauteur 180 mm environ). Le mouvement giratoire est obtenu par injection tangentielle du liquide pres de la paroi. L'etude porte sur la determination des conditions thermiques et hydrodynamiques de la formation d'une telle couche et sur les regles de similitude de ce phenomene. On a observe les caracteristiques de l'ecoulement giratoire en fonction du debit (de 5 a 27 g/s, soit de 4.3 a 23 1/mn), de la vitesse d'injection (entre 10 et 110 m/s) et de la largeur du deversoir (18 et 25 mm), ceci pour six diametres differents d'injecteur (1.0 ; 1.5; 1.9; 2.25; 2.65 et 3.0 mm). Le flux de chaleur total mesure

  9. Mesure de la capacité différencielle de la double couche électrique en milieu hydrocarbure. Etude de l'interface métal-additifs pour lubrifiants. Première partie Measuring the Differential Capacity of the Electric Double Layer in a Hydrocarbon Medium. Analysis of the Metal Additive Interface for Lubricants. Part One

    OpenAIRE

    Hipeaux J. C.

    2006-01-01

    Le phénomène d'adsorption d'additifs détergents-dispersants contenus dans les huiles lubrifiantes est à la base de l'action de ces produits. L'existence d'une double couche électrique est un des paramètres envisagés lors de l'étude de l'interface métal-milieu hydrocarbure. La structure de cette double couche en liaison avec le phénomène d'adsorption à l'interface (courbe électrocapillaire, énergie libre de surface, charge, capacité différentielle) sont abordés. L'importance de la connaissance...

  10. Étude de l’influence des couches de non-tissés intermédiaires dans la réversibilité du doublage thermoplastique au Plextol B500®

    Directory of Open Access Journals (Sweden)

    Virginie Le Poizat

    2012-06-01

    Full Text Available Les choix concernant les matériaux et la mise en œuvre d’un doublage du support original d’une peinture par un textile et des adhésifs synthétiques sont souvent pris de manière empirique par les restaurateurs, sans être précédés de tests précis. La réversibilité, qui est un principe de déontologie primordial est encore imprécise pour ce type de doublage. Nous avons étudié par des expérimentations comment celle-ci peut être déterminée par le choix des couches intermédiaires.Choices about materials and the elaboration of synthetic linings are often made by the conservator, without any precise experimentation. Reversibility is an important deontological principal, not well-known concerning synthetic lining. We studied thanks to experimentations, how it can be influenced by the choice of the intermediate layers.

  11. Turbulent developments on the worldwide market for corn; Turbulente ontwikkelingen op wereldwijde graanmarkten

    Energy Technology Data Exchange (ETDEWEB)

    Gengler, L.

    2008-07-01

    The price of corn, seeds and other types of food crop has experienced a turbulent increase in the last two years. No less turbulent was the reporting on the consequences of market developments, especially in the last months. Various experts tumbled over each other with analyses of the causes, the consequences and the expectations. The food crisis was discussed worldwide and early June the FAO held a conference on this topic. Here, too, there was much disagreement on the question of guilt and the solutions. A recurring phenomenon is the pointing to biofuels as the cause of more expensive raw materials. This article addresses the main developments on the global corn markets. [mk]. [Dutch] De prijzen van granen, zaden en andere voedselgewassen hebben de afgelopen twee jaar een stormachtige stijging doorgemaakt. Minstens zo turbulent was, vooral de laatste maanden, de berichtgeving over de gevolgen van de marktontwikkelingen. Deskundigen van allerlei pluimage buitelden over elkaar heen met analyses van de oorzaken, de gevolgen, en de verwachtingen. Wereldwijd werd er gesproken over de voedselcrisis, en de FAO hield begin juni een conferentie over de problematiek. Ook daar heerste onenigheid over schuldvraag en oplossingen. Steeds terugkerend fenomeen is het wijzen naar biobrandstoffen als oorzaak van duurdere grondstoffen. In dit artikel komen de belangrijkste ontwikkelingen op de wereldwijde graanmarkten aan de orde.

  12. Thermal turbulent convection: thermal plumes and fluctuations; Convection thermique turbulente: panaches et fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Gibert, M

    2007-10-15

    In this study we investigate the phenomenon of thermal turbulent convection in new and unprecedented ways. The first system we studied experimentally is an infinite vertical channel, where a constant vertical mean gradient of temperature exists. Inside this channel the average mass flux is null. The results obtained from our measurements reveal that the flow is mainly inertial; indeed the dissipative coefficients (here the viscosity) play a role only to define a coherence length L. This length is the distance over which the thermal plumes can be considered as 'free falling' objects. The horizontal transport, of heat and momentum, is entirely due to fluctuations. The associated 'mixing length' is small compared to the channel width. In the other hand, the vertical heat transport is due to coherent structures: the heat plumes. Those objects were also investigated in a Lagrangian study of the flow in the bulk of a Rayleigh-Benard cell. The probe, which has the same density as the fluid used in this experiment, is a sphere of 2 cm in diameter with embarked thermometers and radio-emitter. The heat plumes transport it, which allows a statistical study of such objects. (author)

  13. HOME Income Limits

    Data.gov (United States)

    Department of Housing and Urban Development — HOME Income Limits are calculated using the same methodology that HUD uses for calculating the income limits for the Section 8 program. These limits are based on HUD...

  14. Adaptive limit margin detection and limit avoidance

    Science.gov (United States)

    Yavrucuk, Ilkay

    This thesis concerns the development of methods, algorithms, and control laws for the development of an adaptive flight envelope protection system to be used for both manned and unmanned aircraft. The proposed method lifts the requirement for detailed a priori information of aircraft dynamics by enabling adaptation to system uncertainty. The system can be used for limits that can be either measured or related to selected measurable quantities. Specifically, an adaptive technique for predicting limit margins and calculating the corresponding allowable control or controller command margins of an aircraft is described in an effort to enable true carefree maneuvering. This new approach utilizes adaptive neural network based loops for the approximation of required aircraft dynamics. For limits that reach their maximum value in steady state, a constructed estimator model is used to predict the maneuvering quasi-steady response behavior---the so called dynamic trim---of the limit parameters and the corresponding control or command margins. Linearly Parameterized Neural Networks as well as Single Hidden Layer Neural Networks are used for on-line adaptation. The approach does not require any off-line training of the neural networks, instead all learning is achieved during flight. Lyapunov based weight update laws are derived. The method is extended for multi-channelled control limiting for aircraft subject to multiple limits, and for automatic control and command limiting for UAV's. Simulation evaluations of the method using a linear helicopter model and a nonlinear Generalized Tiltrotor Simulation (GTRSIM) model are presented. Limit avoidance methods are integrated and tested through the implementation of an artificial pilot model and an active-stick controller model for tactile cueing in the tiltrotor simulation, GTRSIM. Load factor, angle-of-attack, and torque limits are considered as examples. Similarly, the method is applied to the Georgia Tech's Yamaha R-Max (GTMax

  15. Synthèse de Cuprates de Strontium (SrCu2O2) par MOCVD comme couche mince d'oxyde transparent conducteur de type P

    OpenAIRE

    Khan , Afzal

    2011-01-01

    Transparent conducting oxides (TCOs) as transparent electrodes in the form of thin film are used in a large number of applications such as solar cells, liquid crystal displays, touch screen etc. However, these technological applications of TCOs are still limited because of the availability of only n-type TCOs. For diverse technological applications synthesis of efficient p-type TCOs is of utmost importance. In p-type TCO category, copper oxides of delafossite structure (ACuO2) or SrCu202 stru...

  16. Synthèse de Cuprates de Strontium (SrCu2O) par MOCVD comme couche mince d'oxyde transparent conducteur de type P

    OpenAIRE

    Khan, Afzal

    2011-01-01

    Transparent conducting oxides (TCOs) as transparent electrodes in the form of thin film are used in a large number of applications such as solar cells, liquid crystal displays, touch screen etc. However, these technological applications of TCOs are still limited because of the availability of only n-type TCOs. For diverse technological applications synthesis of efficient p-type TCOs is of utmost importance. In p-type TCO category, copper oxides of delafossite structure (ACuO2) or SrCu202 stru...

  17. Applications Rheology of Foam Iin Porous Media At the Limiting Capillary Pressure Rhéologie des mousses en milieux poreux à la pression capillaire finale

    Directory of Open Access Journals (Sweden)

    Rossen W. R.

    2006-11-01

    *, de saturation en eau et de perméabilité relative de l'eau virtuellement sans variations, et de gradient de pression proportionnel au débit d'eau et indépendant du débit de gaz. Ce rapport étudie certaines implications de ces constatations pour des flux de mousse en régime permanent. Dans le cas d'un régime permanent radial 1D sans changement de phase, cette hypothèse implique que la mousse se comporte comme un fluide newtonien, même si la rhéologie de la mousse à texture constante est fortement non-newtonienne. En cas de déplacement à la vapeur d'eau, cependant, l'évaporation de l'eau quand la pression décroît dans le flux provenant d'un puits d'injection pourrait donner l'impression que la mousse subit un rhéoépaississement. Le colmatage complet ne peut survenir à régime permanent avec une mousse sous pc*. Mais une obturation temporaire est possible, la durée de cette obturation dépendant du débit de déplacement de l'eau et de l'élévation de la pression capillaire. L'effet capillaire final peut influer fortement sur les résultats de l'injection des carottes à faible gradient de pression. La déviation entre des couches de perméabilité différente dépend du contact entre les couches. Si deux couches sont séparées par une barrière imperméable, les données limitées dont on dispose sur les effets de la perméabilité sur la pc* suggèrent une déviation du flux vers la couche à faible perméabilité. Toutefois, si les couches sont en équilibre capillaire, la différence de pc* entre deux couches peut virtuellement entraîner une déviation totale du flux vers la couche à haute perméabilité.

  18. VT Limited Access Highways

    Data.gov (United States)

    Vermont Center for Geographic Information — A limited-access road, known by various terms worldwide, including limited-access highway, dual carriageway, expressway, and partial controlled access highway, is a...

  19. LANSCE beam current limiter

    International Nuclear Information System (INIS)

    Gallegos, F.R.

    1996-01-01

    The Radiation Security System (RSS) at the Los Alamos Neutron Science Center (LANSCE) provides personnel protection from prompt radiation due to accelerated beam. Active instrumentation, such as the Beam Current Limiter, is a component of the RSS. The current limiter is designed to limit the average current in a beam line below a specific level, thus minimizing the maximum current available for a beam spill accident. The beam current limiter is a self-contained, electrically isolated toroidal beam transformer which continuously monitors beam current. It is designed as fail-safe instrumentation. The design philosophy, hardware design, operation, and limitations of the device are described

  20. Elaboration et caracterisation de couches minces de CuInS2 deposees par la pyrolyse par pulverisation ultrasonique a base de transducteur

    Science.gov (United States)

    Petuenju, Eric Nguwuo

    by heat to obtain the formation of a new compound. The main objective of this thesis focuses on the use of ultrasonic spray pyrolysis technique to grow CuInS2 thin films and characterize them by different techniques. This choice is linked to the fact that the CuInS2 is a direct gap semiconductor material, which can act as absorber in solar photovoltaic technology. However, the growth of thin films of this material is subject to a problem of creation of interpenetrating networks of different types of semiconductors (n and p-type), which implies a suitable choice of deposition technique. It should be noted that the interest in existing methods, the ALCVD (Atomic Layer Vapor Deposition) and ILGAR (Ion Layer Gas Reaction) developed in paragraphs 2.4.1 and 2.4.2, is confronted with time limits of these methods. Indeed these two methods, owing to the principle of sequential production process, take place very slowly; and we showed that the thickness of the obtained thin film is proportional to the deposition time. In this work, spray pyrolysis is carried out in two different ways, namely ultrasonic and pneumatic spraying. Of these two methods, we showed that the transducer based ultrasonic spray pyrolysis is the method that can be used to grow thin films of CuInS2 a good homogeneity of the crystallites size (of the order of 110 A) and the morphology of the layers. Ultrasonic spraying was done with a piezoelectric system using a transducer. This system consists of a cylindrical container made of Teflon 5 cm diameter and 15 cm long in which is introduced the solution containing the precursor. The container is mounted on an ultrasonic transducer, component of the piezoelectric system TDK nebulizer unit NB-80E-01, which transforms the solution in aerosol. The aerosol is transported through a teflon tube by a carrier gas, the nitrogen, into a floating motion to the substrate. The substrate is placed on a heating plate whose temperature is controlled by a control monitor. The

  1. JET pump limiter

    International Nuclear Information System (INIS)

    Sonnenberg, K.; Deksnis, E.; Shaw, R.; Reiter, D.

    1988-01-01

    JET plans to install two pump limiter modules which can be used for belt-limiter, inner-wall and X-point discharges and, also, for 1-2s as the main limiter. A design is presented which is compatible with two diagnostic systems, and which allows partial removal of the pump limiter to provide access for remote-handling operations. The high heat-flux components are initially cooled during a pulse. Heat is removed between discharges by radiation and pressure contacts to a water-cooled support structure. The pumping edge will be made of annealed pyrolytic graphite. Exhaust efficiency has been estimated, for a 1-d edge model, using a Monte-Carlo calculation of neutral gas transport. When the pump limiter is operated together with other wall components we expect an efficiency of ≅ 5% (2.5 x 10 21 part/s). As a main limiter the efficiency increases to about 10%. (author)

  2. Limit analysis via creep

    International Nuclear Information System (INIS)

    Taroco, E.; Feijoo, R.A.

    1981-07-01

    In this paper it is presented a variational method for the limit analysis of an ideal plastic solid. This method has been denominated as Modified Secundary Creep and enables to find the collapse loads through a minimization of a functional and a limit process. Given an ideal plastic material it is shown how to determinate the associated secundary creep constitutive equation. Finally, as an application, it is found the limit load in an pressurized von Mises rigid plastic sphere. (Author) [pt

  3. Detector limitations, STAR

    Energy Technology Data Exchange (ETDEWEB)

    Underwood, D. G.

    1998-07-13

    Every detector has limitations in terms of solid angle, particular technologies chosen, cracks due to mechanical structure, etc. If all of the presently planned parts of STAR [Solenoidal Tracker At RHIC] were in place, these factors would not seriously limit our ability to exploit the spin physics possible in RHIC. What is of greater concern at the moment is the construction schedule for components such as the Electromagnetic Calorimeters, and the limited funding for various levels of triggers.

  4. Limit loads in nozzles

    International Nuclear Information System (INIS)

    Zouain, N.

    1983-01-01

    The static method for the evaluation of the limit loads of a perfectly elasto-plastic structure is presented. Using the static theorem of Limit Analysis and the Finite Element Method, a lower bound for the colapso load can be obtained through a linear programming problem. This formulation if then applied to symmetrically loaded shells of revolution and some numerical results of limit loads in nozzles are also presented. (Author) [pt

  5. Limits to Inclusion

    Science.gov (United States)

    Hansen, Janne Hedegaard

    2012-01-01

    In this article, I will argue that a theoretical identification of the limit to inclusion is needed in the conceptual identification of inclusion. On the one hand, inclusion is formulated as a vision that is, in principle, limitless. On the other hand, there seems to be an agreement that inclusion has a limit in the pedagogical practice. However,…

  6. Numerical Limit Analysis:

    DEFF Research Database (Denmark)

    Damkilde, Lars

    2007-01-01

    Limit State analysis has a long history and many prominent researchers have contributed. The theoretical foundation is based on the upper- and lower-bound theorems which give a very comprehensive and elegant formulation on complicated physical problems. In the pre-computer age Limit State analysis...... also enabled engineers to solve practical problems within reinforced concrete, steel structures and geotechnics....

  7. Limited data speaker identification

    Indian Academy of Sciences (India)

    The evidences from all these integrated systems can be combined to obtain a speaker identification system that provides improved performance under limited data. Hence the motivation for this work. A few attempts have been made earlier to study and provide solution to the problem of limited data in the speaker recognition ...

  8. Advanced limiters for ISX

    International Nuclear Information System (INIS)

    Mioduszewski, P.K.; Edmonds, P.H.; Sheffield, J.

    1982-01-01

    Continuous removal of heat and particles becomes a vital necessity in future steady-state fusion devices. The pump limiter seems to be an attractive concept to combine these two tasks. On ISX, various schemes of pump limiters are being explored with the final goal to furnish the ISX--C device with a pump limiter to handle heat removal and particle control in steady state. The emphasis of the present paper is on pump limiters based on ballistic particle collection. If this concept turns out to be successful in supplying sufficient pumping efficiency, it may be possible to design pump limiters without a leading edge. Analytical calculations of the particle collection efficiency are given for various limiter configurations. Pumping efficiencies of approximately 4--10%, depending on the specific configuration, seem to be feasible and should be sufficient for steady-state operation. Initial experimental results on pump limiter studies in ISX--B confirm the calculated collection efficiencies. By measuring the ion saturation current to the limiter blade and the pressure buildup simultaneously, we found a correlation between the incident particle flux and the pressure rise that agrees well with a simple model

  9. Universal Limits on Computation

    CERN Document Server

    Krauss, L M

    2004-01-01

    The physical limits to computation have been under active scrutiny over the past decade or two, as theoretical investigations of the possible impact of quantum mechanical processes on computing have begun to make contact with realizable experimental configurations. We demonstrate here that the observed acceleration of the Universe can produce a universal limit on the total amount of information that can be stored and processed in the future, putting an ultimate limit on future technology for any civilization, including a time-limit on Moore's Law. The limits we derive are stringent, and include the possibilities that the computing performed is either distributed or local. A careful consideration of the effect of horizons on information processing is necessary for this analysis, which suggests that the total amount of information that can be processed by any observer is significantly less than the Hawking-Beckenstein entropy associated with the existence of an event horizon in an accelerating universe.

  10. Modeling Complex Time Limits

    Directory of Open Access Journals (Sweden)

    Oleg Svatos

    2013-01-01

    Full Text Available In this paper we analyze complexity of time limits we can find especially in regulated processes of public administration. First we review the most popular process modeling languages. There is defined an example scenario based on the current Czech legislature which is then captured in discussed process modeling languages. Analysis shows that the contemporary process modeling languages support capturing of the time limit only partially. This causes troubles to analysts and unnecessary complexity of the models. Upon unsatisfying results of the contemporary process modeling languages we analyze the complexity of the time limits in greater detail and outline lifecycles of a time limit using the multiple dynamic generalizations pattern. As an alternative to the popular process modeling languages there is presented PSD process modeling language, which supports the defined lifecycles of a time limit natively and therefore allows keeping the models simple and easy to understand.

  11. Mitigating greenhouse: Limited time, limited options

    International Nuclear Information System (INIS)

    Moriarty, Patrick; Honnery, Damon

    2008-01-01

    Most human-caused climate change comes from fossil fuel combustion emissions. To avoid the risk of serious climate change, very recent research suggests that emission reductions will need to be both large and rapidly implemented. We argue that technical solutions-improving energy efficiency, use of renewable and nuclear energy, and carbon capture and sequestration-can only be of minor importance, mainly given the limited time available to take effective climate action. Only curbing energy use, perhaps through 'social efficiency' gains, particularly in the high-energy consumption countries, can provide the rapid emissions reductions needed. The social efficiency approach requires a basic rethinking in how we can satisfy our human needs with low environmental impacts. Large cuts in emissions could then occur rapidly, but only if resistance to such changes can be overcome. Particularly in transport, there are also serious potential conflicts between the technical and the social efficiency approaches, requiring a choice to be made

  12. 7 CFR 1400.204 - Limited partnerships, limited liability partnerships, limited liability companies, corporations...

    Science.gov (United States)

    2010-01-01

    ..., limited liability companies, corporations, and other similar legal entities. 1400.204 Section 1400.204..., limited liability partnerships, limited liability companies, corporations, and other similar legal entities. (a) A limited partnership, limited liability partnership, limited liability company, corporation...

  13. Novel limiter pump topologies

    International Nuclear Information System (INIS)

    Schultz, J.H.

    1981-01-01

    The use of limiter pumps as the principle plasma exhaust system of a magnetic confinement fusion device promises significant simplification, when compared to previously investigating divertor based systems. Further simplifications, such as the integration of the exhaust system with a radio frequency heating system and with the main reactor shield and structure are investigated below. The integrity of limiters in a reactor environment is threatened by many mechanisms, the most severe of which may be erosion by sputtering. Two novel topolgies are suggested which allow high erosion without limiter failure

  14. Putting Harry Potter on the couch.

    Science.gov (United States)

    Noctor, Colman

    2006-10-01

    This article will explore J.K. Rowling's Harry Potter (2004) literary series from a psychoanalytical perspective. The author draws out the main themes of the Harry Potter stories to see if they can be employed clinically to assist in psychotherapeutic work with children and adolescents. The article begins by discussing Bettelheim's (1976) extensive work on children's fairytales and their therapeutic value, moving on to discuss Rustin and Rustin's (2005) more recent insights into narrative therapy and children's fiction. A clinical example is given of how the storylines were implemented to enhance a psychotherapeutic group process for adolescents. The author hopes to illustrate the power of symbolism and metaphor in the Harry Potter storylines and elucidate why these books may appeal to young people with mental health difficulties.

  15. HOME Rent Limits

    Data.gov (United States)

    Department of Housing and Urban Development — In accordance with 24 CFR Part 92.252, HUD provides maximum HOME rent limits. The maximum HOME rents are the lesser of: The fair market rent for existing housing for...

  16. ACA Federal Upper Limits

    Data.gov (United States)

    U.S. Department of Health & Human Services — Affordable Care Act Federal Upper Limits (FUL) based on the weighted average of the most recently reported monthly average manufacturer price (AMP) for...

  17. HUD Program Income Limits

    Data.gov (United States)

    Department of Housing and Urban Development — Income limits used to determine the income eligibility of applicants for assistance under three programs authorized by the National Housing Act. These programs are...

  18. Limited Denial of Participation

    Data.gov (United States)

    Department of Housing and Urban Development — A Limited Denial of Participation (LDP) is an action taken by a HUD Field Office or the Deputy Assistant Secretary for Single Family (DASSF) or Multifamily (DASMF)...

  19. Limited Income and Resources

    Data.gov (United States)

    U.S. Department of Health & Human Services — Information for those with limited income and resources (those who may qualify for or already have the Low Income Subsidy to lower their prescription drug coverage...

  20. Towards Improved Optical Limiters

    National Research Council Canada - National Science Library

    Huffman, Peter

    2002-01-01

    .... The first approach was to synthesize and study soluble thallium phthalocyanines. Thallium, due to its proximity to lead and indium on the periodic table, should exhibit favorable optical limiting properties...

  1. SIS - Annual Catch Limit

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Annual Catch Limit (ACL) dataset within the Species Information System (SIS) contains information and data related to management reference points and catch data.

  2. Limited Scleroderma (CREST Syndrome)

    Science.gov (United States)

    ... limited scleroderma is believed to be an autoimmune disorder, in which your immune system turns against your body. The immune system appears to stimulate the production of too much collagen, a key component of connective tissue. This overproduction ...

  3. Political campaign spending limits

    OpenAIRE

    Pastine, Ivan; Pastine, Tuvana

    2010-01-01

    Political campaign spending ceilings are purported to limit the incumbent’s ability to exploit his fundraising advantage. If the challenger does not have superior campaign effectiveness, in contrast to conventional wisdom, we show that the incumbent always benefits from a limit as long as he has an initial voter disposition advantage, however small and regardless of the candidates’ relative fundraising ability. If the challenger has higher campaign spending effectiveness, th...

  4. Safety and design limits

    International Nuclear Information System (INIS)

    Shishkov, L. K.; Gorbaev, V. A.; Tsyganov, S. V.

    2007-01-01

    The paper touches upon the issues of NPP safety ensuring at the stage of fuel load design and operation by applying special limitations for a series of parameters, that is, design limits. Two following approaches are compared: the one used by west specialists for the PWR reactor and the Russian approach employed for the WWER reactor. The closeness of approaches is established, differences that are mainly peculiarities of terms are noted (Authors)

  5. Xenotransplantation: Perspectives and limits

    OpenAIRE

    Hammer, Claus

    2001-01-01

    Xenotransplantation faces the dilemma of an unlimited supply of cells, tissues and organs on the one hand and severe obstacles and limits on the other. One reason for the limitations is that the source animal of choice, the pig, and the human recipient separated 90 million years ago during evolution, a time in which biological characteristics such as anatomy, physiology and immunology have had much time to drift far apart. The acceptance of such an evolutionary widely divergent organ, especia...

  6. Altruism and Reproductive Limitations

    Directory of Open Access Journals (Sweden)

    Carey J. Fitzgerald

    2009-04-01

    Full Text Available We examined how different types of reproductive limitations — functional (schizoid personality disorder and schizophrenia, physical (malnutrition, and sexual (bisexuality and homosexuality — influenced altruistic intentions toward hypothetical target individuals of differing degrees of relatedness (r = 0, .25, and .50. Participants were 312 undergraduate students who completed a questionnaire on altruism toward hypothetical friends, half-siblings, and siblings with these different types of reproductive limitations. Genetic relatedness and reproductive limitations did not influence altruistic decision-making when the cost of altruism was low but did as the cost of altruism increased, with participants being more likely to help a sibling over a half-sibling and a half-sibling over a friend. Participants also indicated they were more likely to help a healthy (control person over people with a reproductive limitation. Of the three types of reproductive limitations, functional limitations had the strongest effect on altruistic decision-making, indicating that people were less likely to help those who exhibit abnormal social behavior.

  7. Quantum-limit spectroscopy

    CERN Document Server

    Ficek, Zbigniew

    2017-01-01

    This book covers the main ideas, methods, and recent developments of quantum-limit optical spectroscopy and applications to quantum information, resolution spectroscopy, measurements beyond quantum limits, measurement of decoherence, and entanglement. Quantum-limit spectroscopy lies at the frontier of current experimental and theoretical techniques, and is one of the areas of atomic spectroscopy where the quantization of the field is essential to predict and interpret the existing experimental results. Currently, there is an increasing interest in quantum and precision spectroscopy both theoretically and experimentally, due to significant progress in trapping and cooling of single atoms and ions. This progress allows one to explore in the most intimate detail the ways in which light interacts with atoms and to measure spectral properties and quantum effects with high precision. Moreover, it allows one to perform subtle tests of quantum mechanics on the single atom and single photon scale which were hardly eve...

  8. Hadron collider luminosity limitations

    CERN Document Server

    Evans, Lyndon R

    1992-01-01

    The three colliders operated to date have taught us a great deal about the behaviour of both bunched and debunched beams in storage rings. The main luminosity limitations are now well enough understood that most of them can be stronglu attenuated or eliminated by approriate design precautions. Experience with the beam-beam interaction in both the SPS and the Tevatron allow us to predict the performance of the new generation of colliders with some degree of confidence. One of the main challenges that the accelerator physicist faces is the problem of the dynamic aperture limitations due to the lower field quality expected, imposed by economic and other constraints.

  9. SLC kicker magnet limitations

    International Nuclear Information System (INIS)

    Cassel, R.; Donaldson, A.; Mattison, T.; Bowden, G.; Weaver, J.; Bulos, F.; Fiander, D.

    1991-01-01

    The SLC Damping Ring kicker magnets requires a fast magnetic field rise time of 58 nsec, a peak field of 800 gauss, a pulse amplitude stability of 0.01%, and a reasonable operational lifetime. The original kicker magnets designed by SLAC and at Fermi were not able to fulfill the SLC kicker requirements. Extensive studies were conducted to determine the limitation in the magnets, response of the ferrite in kicker magnet, and the modifications needed to improve the kicker magnet performance. The paper details the SLAC and Fermi kicker magnets limitation of performance

  10. Activation analysis. Detection limits

    International Nuclear Information System (INIS)

    Revel, G.

    1999-01-01

    Numerical data and limits of detection related to the four irradiation modes, often used in activation analysis (reactor neutrons, 14 MeV neutrons, photon gamma and charged particles) are presented here. The technical presentation of the activation analysis is detailed in the paper P 2565 of Techniques de l'Ingenieur. (A.L.B.)

  11. Limited data speaker identification

    Indian Academy of Sciences (India)

    Speaker identification; limited training and testing data; MFSR; LPR; LPRP; LVQ; GMM–UBM and combining. ... Department of Information Science and Engineering, Siddaganga Institute of Technology, Tumkur 572 103; Department of Electronics and Communication Engineering, Indian Institute of Technology Guwahati, ...

  12. Occupational dose equivalent limits

    International Nuclear Information System (INIS)

    Goldfinch, E.P.

    1980-01-01

    This paper considers methods of limiting individual radiation risks by recognizing the variation of risk with age at exposure, taking into account both somatic and genetic risks and proposes a simple formula for controlling individual cumulative exposure and hence risk. (Author)

  13. Limited data speaker identification

    Indian Academy of Sciences (India)

    dependent or text-independent type. Speech for the same text is used for ... are practical situations like forensic investigations where the availability of speech data is limited and technology is ...... Murthy K S R, Yegnanarayana B 2006 Combining evidence from residual phase and MFCC features for speaker recognition.

  14. Limits of Software Reuse

    NARCIS (Netherlands)

    Holenderski, L.

    2006-01-01

    Software reuse is considered one of the main techniques to increasesoftware productivity. We present two simple mathematical argumentsthat show some theoretical limits of reuse. It turns out that the increase of productivity due to internal reuse is at most linear, farfrom the needed exponential

  15. Current limiter circuit system

    Energy Technology Data Exchange (ETDEWEB)

    Witcher, Joseph Brandon; Bredemann, Michael V.

    2017-09-05

    An apparatus comprising a steady state sensing circuit, a switching circuit, and a detection circuit. The steady state sensing circuit is connected to a first, a second and a third node. The first node is connected to a first device, the second node is connected to a second device, and the steady state sensing circuit causes a scaled current to flow at the third node. The scaled current is proportional to a voltage difference between the first and second node. The switching circuit limits an amount of current that flows between the first and second device. The detection circuit is connected to the third node and the switching circuit. The detection circuit monitors the scaled current at the third node and controls the switching circuit to limit the amount of the current that flows between the first and second device when the scaled current is greater than a desired level.

  16. FTU pump limiter

    International Nuclear Information System (INIS)

    Alessandrini, C.; Ciotti, M.; Mattei, A. De; Maddaluno, G.; Mazzitelli, G.

    1989-01-01

    The control of the refuelling and recycling of the plasma is crucial in providing enhanced performances in tokamaks and steady-state operation in future reactors. In this paper, we report details of the design and analysis for the pump limiter to be incorporated into the FTU tokamak. The FTU, presently under commissioning, is a compact high field (B=8T), medium high density, circular cross section machine with small accesses. The dimensions of the equatorial port (width 8 cm) would reduce the length of the entrance throat to a few centimeters, which is unacceptable for efficient particle trapping. We have, therefore, designed a rotating blade of the pump limiter head that, in the working position, extends in the toroidal direction inside the vacuum chamber. (author) 8 refs., 4 figs

  17. Age Limit of Pediatrics.

    Science.gov (United States)

    Hardin, Amy Peykoff; Hackell, Jesse M

    2017-09-01

    Pediatrics is a multifaceted specialty that encompasses children's physical, psychosocial, developmental, and mental health. Pediatric care may begin periconceptionally and continues through gestation, infancy, childhood, adolescence, and young adulthood. Although adolescence and young adulthood are recognizable phases of life, an upper age limit is not easily demarcated and varies depending on the individual patient. The establishment of arbitrary age limits on pediatric care by health care providers should be discouraged. The decision to continue care with a pediatrician or pediatric medical or surgical subspecialist should be made solely by the patient (and family, when appropriate) and the physician and must take into account the physical and psychosocial needs of the patient and the abilities of the pediatric provider to meet these needs. Copyright © 2017 by the American Academy of Pediatrics.

  18. Are Limit Orders Rational?

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Martin

    2007-01-01

    Roč. 14, č. 4 (2007), s. 32-38 ISSN 0572-3043 R&D Projects: GA ČR(CZ) GA402/06/1417; GA ČR GA402/04/1294; GA ČR GD402/03/H057 Institutional research plan: CEZ:AV0Z10750506 Keywords : market microstructure * limit order market * portfolio selection Subject RIV: AH - Economics

  19. Density limits in Tokamaks

    International Nuclear Information System (INIS)

    Tendler, M.

    1984-06-01

    The energy loss from a tokamak plasma due to neutral hydrogen radiation and recycling is of great importance for the energy balance at the periphery. It is shown that the requirement for thermal equilibrium implies a constraint on the maximum attainable edge density. The relation to other density limits is discussed. The average plasma density is shown to be a strong function of the refuelling deposition profile. (author)

  20. Photovoltaic energy cost limit

    International Nuclear Information System (INIS)

    Coiante, D.

    1992-01-01

    Referring to a photovoltaic system for grid connected applications, a parametric expression of kWh cost is derived. The limit of kWh cost is carried out extrapolating the values of cost components to their lowest figure. The reliability of the forecast is checked by disaggregating kWh cost in direct and indirect costs and by discussing the possible cost reduction of each component

  1. Limits of Nuclear Stability

    CERN Document Server

    Nerlo-Pomorska, B; Kleban, M

    2003-01-01

    The modern version of the liquid-drop model (LSD) is compared with the macroscopic part of the binding energy evaluated within the Hartree-Fock- Bogoliubov procedure with the Gogny force and the relativistic mean field theory. The parameters of a liquid-drop like mass formula which approximate on the average the self-consistent results are compared with other models. The limits of nuclear stability predicted by these models are discussed.

  2. Pressure limitation method

    International Nuclear Information System (INIS)

    Brady, M.

    1989-01-01

    The pressure in a glovebox is maintained, for safety, between predetermined negative and positive limits relative to atmospheric pressure by means of a lute comprising a closed vessel having a tube sealed through its upper region and extending downwards towards its lower region and having an open end thereat. The other end of the tube is connected to the glovebox and the upper region of the vessel is vented to atmosphere via an extract system. The vessel and tube are filled with liquid to such a level, sealing the open end of the tube, that (a) at the said negative limit the liquid level in the vessel falls to unseal the tube and allow atmospheric air to enter the glovebox, and (b) at the said positive limit the liquid level in the tube falls to unseal the tube and allow gas from the glovebox to vent to atmosphere. A catch-pot is provided between tube and the glovebox to prevent any entrained liquid entering the glovebox, and similar means may also be provided to prevent any entrained liquid entering the extract system. (author)

  3. Mesure de la capacité différencielle de la double couche électrique en milieu hydrocarbure. Etude de l'interface métal-additifs pour lubrifiants. Première partie Measuring the Differential Capacity of the Electric Double Layer in a Hydrocarbon Medium. Analysis of the Metal Additive Interface for Lubricants. Part One

    Directory of Open Access Journals (Sweden)

    Hipeaux J. C.

    2006-11-01

    Full Text Available Le phénomène d'adsorption d'additifs détergents-dispersants contenus dans les huiles lubrifiantes est à la base de l'action de ces produits. L'existence d'une double couche électrique est un des paramètres envisagés lors de l'étude de l'interface métal-milieu hydrocarbure. La structure de cette double couche en liaison avec le phénomène d'adsorption à l'interface (courbe électrocapillaire, énergie libre de surface, charge, capacité différentielle sont abordés. L'importance de la connaissance du potentiel de charge nulle est montrée. Une revue bibliographique des moyens d'accès à la mesure des capacités différentielles de la double couche est farte, l'objectif à atteindre étant le choix d'une technique de mesure possible en milieu hydrocarbure, sur électrode solide. Une méthode, basée sur l'étude du début de la charge de la double couche électrique et utilisant la superposition d'une tension carrée à une tension continue maintenue constante, est développée et l'étude théorique du circuit réalisée. Des courbes capacité différentielle = f (tension de polarisation sont tracées pour des solutions dans l'heptane de différents additifs utilisés en lubrification. Une réflexion sur les mécanismes d'adsorption est faite à partir de l'exploitation de ces courbes expérimentales. A titre de comparaison quelques tracés de courbes de capacité différentielle sont effectués avec un produit antistatique rendant fortement conducteur les hydrocarbures et un produit antiusure. Enfin un système de référence utilisant une électrode au calomel est proposé. The adsorption phenomena of detergent-dispersant additives contained in lubricating ails is behind for the action of such products. The existence of an electrical double layer is one of the parameters token into consideration when analyzing the métal/hydrocarbon medium interface. The structure of this double layer in connection with the adsorption phenomenon on

  4. Caractérisation de la perméabilité des couches constituant la barrière passive des installations de stockage de déchets non dangereux Permeability characterization of the geological barrier of non dangerous landfill sites

    Directory of Open Access Journals (Sweden)

    Mouthier B.

    2012-09-01

    Full Text Available Pour obtenir son autorisation d’exploiter, une Installation de Stockage de Déchets Non Dangereux (ISDND doit justifier réglementairement sa favorabilité géologique. Le « Guide de bonnes pratiques pour les reconnaissances géologiques » de l’AFNOR fournit les critères d’aptitude du site à recevoir une ISDND et les moyens à mettre en œuvre, dont ceux qui concernent la perméabilité des couches géologiques qui protègent le milieu naturel. La mesure de la perméabilité in situ, en forage, des matériaux peu à très peu perméables des deux couches de la barrière de sécurité passive, est une opération délicate qui nécessite une mise en œuvre soignée respectant les normes appropriées, choisies en fonction des gammes de perméabilité attendues. Plusieurs types d’essai en forage sont présentés. In order to get administrative authorization, a non dangerous waste landfill site (ISDND, must justify a favourable geological context, which follows the AFNOR “Guide de bonnes pratiques pour les reconnaissances géologiques ». Criteria and technical means are described among which the in situ and lab permeability determination processes. The low and very low permeability coefficient to be measured within the deep argillaceous formations of a landfill site, is a delicate operation which must be representative and accurate. Depending the permeability range, several norms are proposed.

  5. Strategic arms limitation

    Science.gov (United States)

    Allen Greb, G.; Johnson, Gerald W.

    1983-10-01

    Following World War II, American scientists and politicians proposed in the Baruch plan a radical solution to the problem of nuclear weapons: to eliminate them forever under the auspices of an international nuclear development authority. The Soviets, who as yet did not possess the bomb, rejected this plan. Another approach suggested by Secretary of War Henry Stimson to negotiate directly with the Soviet Union was not accepted by the American leadership. These initial arms limitation failures both reflected and exacerbated the hostile political relationship of the superpowers in the 1950s and 1960s. Since 1969, the more modest focus of the Soviet-American arms control process has been on limiting the numbers and sizes of both defensive and offensive strategic systems. The format for this effort has been the Strategic Arms Limitatins Talks (Salt) and more recently the Strategic Arms Reduction Talks (START). Both sides came to these negotiations convinced that nuclear arsenals had grown so large that some for of mutual restraint was needed. Although the SALT/START process has been slow and ponderous, it has produced several concrete the agreements and collateral benefits. The 1972 ABM Treaty restricts the deployment of ballistic missile defense systems, the 1972 Interim Agreement places a quantitative freeze on each side's land based and sea based strategic launchers, and the as yet unratified 1979 SALT II Treaty sets numerical limits on all offensive strategic systems and sublimits on MIRVed systems. Collateral benefits include improved verification procedures, working definitions and counting rules, and permanent bureaucratic apparatus which enhance stability and increase the chances for achieving additional agreements.

  6. Limits to Cloud Susceptibility

    Science.gov (United States)

    Coakley, James A., Jr.

    2002-01-01

    1-kilometer AVHRR observations of ship tracks in low-level clouds off the west coast of the U S. were used to determine limits for the degree to which clouds might be altered by increases in anthropogenic aerosols. Hundreds of tracks were analyzed to determine whether the changes in droplet radii, visible optical depths, and cloud top altitudes that result from the influx of particles from underlying ships were consistent with expectations based on simple models for the indirect effect of aerosols. The models predict substantial increases in sunlight reflected by polluted clouds due to the increases in droplet numbers and cloud liquid water that result from the elevated particle concentrations. Contrary to the model predictions, the analysis of ship tracks revealed a 15-20% reduction in liquid water for the polluted clouds. Studies performed with a large-eddy cloud simulation model suggested that the shortfall in cloud liquid water found in the satellite observations might be attributed to the restriction that the 1-kilometer pixels be completely covered by either polluted or unpolluted cloud. The simulation model revealed that a substantial fraction of the indirect effect is caused by a horizontal redistribution of cloud water in the polluted clouds. Cloud-free gaps in polluted clouds fill in with cloud water while the cloud-free gaps in the surrounding unpolluted clouds remain cloud-free. By limiting the analysis to only overcast pixels, the current study failed to account for the gap-filling predicted by the simulation model. This finding and an analysis of the spatial variability of marine stratus suggest new ways to analyze ship tracks to determine the limit to which particle pollution will alter the amount of sunlight reflected by clouds.

  7. Dose. Detriment. Limit assessment

    International Nuclear Information System (INIS)

    Breckow, J.

    2015-01-01

    One goal of radiation protection is the limitation of stochastic effects due to radiation exposure. The probability of occurrence of a radiation induced stochastic effect, however, is only one of several other parameters which determine the radiation detriment. Though the ICRP-concept of detriment is a quantitative definition, the kind of detriment weighting includes somewhat subjective elements. In this sense, the detriment-concept of ICRP represents already at the stage of effective dose a kind of assessment. Thus, by comparing radiation protection standards and concepts interconvertible or with those of environment or occupational protection one should be aware of the possibly different principles of detriment assessment.

  8. Marketing with limited budget

    OpenAIRE

    Smirnova, Daria

    2017-01-01

    The purpose of this research-based thesis was to get an idea how managers of two small resembling hotels of a specific region deal with marketing process with a limited budget. In addition, the aim of the thesis was to examine if hotel managers who were interviewed perceive marketing only in the way of ‘promotion’ rather than marketing research, marketing mix and marketing environment theories. It was also found out if hotel managers of those hotels consider marketing as a key to successful h...

  9. Limitation of Auditors' Liability

    DEFF Research Database (Denmark)

    Werlauff, Erik; Foged-Ladefoged, Lise Kolding

    2014-01-01

    The article examines the question of whether rules on the limitation of auditors’ liability within the perspective of EU law are needed, and if so, which rules can provide an appropriate balance between the potential injured party’s interests and those of the auditing sector, including with respect...... to the fact that the insurance premiums associated with an unlimited liability must of course make the auditor’s tasks more expensive. Relevant EU recommendations and a comparative glance at other EU countries’ proposed solutions to the problem are included....

  10. Search with Limited Resources.

    Science.gov (United States)

    1983-02-01

    D-R1-76 122 SERCH WITH ’LIMITED RESOURCES(U) DUKE UNIV DURHM NC i/i DEPTOF COMPUTER SCIENCE D C MUTCHLER FEB 83 CS11983-1 USI FE AFOSR-TR-83-i154...over all possible S" g ame trees. How to weight this average has not yet been specified. It is reasonable. glven the lack of additional information, to...complete binary 0-1 tree can be described by two parameters: P a number of goal nodes with value ŕ". and vt = number of goal nodes. This Justifies

  11. Limitations of Boltzmann's principle

    International Nuclear Information System (INIS)

    Lavenda, B.H.

    1995-01-01

    The usual form of Boltzmann's principle assures that maximum entropy, or entropy reduction, occurs with maximum probability, implying a unimodal distribution. Boltzmann's principle cannot be applied to nonunimodal distributions, like the arcsine law, because the entropy may be concave only over a limited portion of the interval. The method of subordination shows that the arcsine distribution corresponds to a process with a single degree of freedom, thereby confirming the invalidation of Boltzmann's principle. The fractalization of time leads to a new distribution in which arcsine and Cauchy distributions can coexist simultaneously for nonintegral degrees of freedom between √2 and 2

  12. Limitations of Expert Evidence

    OpenAIRE

    Serpil Salaçin

    1997-01-01

    Limitations of Expert Evidence Edited by Stephen Leadbeatter MB ChB MCRPath ISBN 1 86016 029 8 Printed in Great Britain by Cathedral Print Services Ltd, Salisbury, 1996 Kitap 25 Ekim 1994 te The Royal College of Physicians ve The Royal College of Pathologists tarafından düzenlenen konferanstan sonra hekimlere ve avukatlara konuyu tartışmaya açmak için basılmış. Bilirkişi görüşünün temel filozofisinin, bu görevi yapanlar ve bu hizmeti alanların yapabileceklerin...

  13. Fault current limiter

    Science.gov (United States)

    Darmann, Francis Anthony

    2013-10-08

    A fault current limiter (FCL) includes a series of high permeability posts for collectively define a core for the FCL. A DC coil, for the purposes of saturating a portion of the high permeability posts, surrounds the complete structure outside of an enclosure in the form of a vessel. The vessel contains a dielectric insulation medium. AC coils, for transporting AC current, are wound on insulating formers and electrically interconnected to each other in a manner such that the senses of the magnetic field produced by each AC coil in the corresponding high permeability core are opposing. There are insulation barriers between phases to improve dielectric withstand properties of the dielectric medium.

  14. Limitations of inclusive fitness.

    Science.gov (United States)

    Allen, Benjamin; Nowak, Martin A; Wilson, Edward O

    2013-12-10

    Until recently, inclusive fitness has been widely accepted as a general method to explain the evolution of social behavior. Affirming and expanding earlier criticism, we demonstrate that inclusive fitness is instead a limited concept, which exists only for a small subset of evolutionary processes. Inclusive fitness assumes that personal fitness is the sum of additive components caused by individual actions. This assumption does not hold for the majority of evolutionary processes or scenarios. To sidestep this limitation, inclusive fitness theorists have proposed a method using linear regression. On the basis of this method, it is claimed that inclusive fitness theory (i) predicts the direction of allele frequency changes, (ii) reveals the reasons for these changes, (iii) is as general as natural selection, and (iv) provides a universal design principle for evolution. In this paper we evaluate these claims, and show that all of them are unfounded. If the objective is to analyze whether mutations that modify social behavior are favored or opposed by natural selection, then no aspect of inclusive fitness theory is needed.

  15. (Limiting the greenhouse effect)

    Energy Technology Data Exchange (ETDEWEB)

    Rayner, S.

    1991-01-07

    Traveler attended the Dahlem Research Conference organized by the Freien Universitat, Berlin. The subject of the conference was Limiting the Greenhouse Effect: Options for Controlling Atmospheric CO{sub 2} Accumulation. Like all Dahlem workshops, this was a meeting of scientific experts, although the disciplines represented were broader than usual, ranging across anthropology, economics, international relations, forestry, engineering, and atmospheric chemistry. Participation by scientists from developing countries was limited. The conference was divided into four multidisciplinary working groups. Traveler acted as moderator for Group 3 which examined the question What knowledge is required to tackle the principal social and institutional barriers to reducing CO{sub 2} emissions'' The working rapporteur was Jesse Ausubel of Rockefeller University. Other working groups examined the economic costs, benefits, and technical feasibility of options to reduce emissions per unit of energy service; the options for reducing energy use per unit of GNP; and the significant of linkage between strategies to reduce CO{sub 2} emissions and other goals. Draft reports of the working groups are appended. Overall, the conference identified a number of important research needs in all four areas. It may prove particularly important in bringing the social and institutional research needs relevant to climate change closer to the forefront of the scientific and policy communities than hitherto.

  16. Limits to biofuels

    Directory of Open Access Journals (Sweden)

    Johansson S.

    2013-06-01

    Full Text Available Biofuel production is dependent upon agriculture and forestry systems, and the expectations of future biofuel potential are high. A study of the global food production and biofuel production from edible crops implies that biofuel produced from edible parts of crops lead to a global deficit of food. This is rather well known, which is why there is a strong urge to develop biofuel systems that make use of residues or products from forest to eliminate competition with food production. However, biofuel from agro-residues still depend upon the crop production system, and there are many parameters to deal with in order to investigate the sustainability of biofuel production. There is a theoretical limit to how much biofuel can be achieved globally from agro-residues and this amounts to approximately one third of todays’ use of fossil fuels in the transport sector. In reality this theoretical potential may be eliminated by the energy use in the biomass-conversion technologies and production systems, depending on what type of assessment method is used. By surveying existing studies on biofuel conversion the theoretical limit of biofuels from 2010 years’ agricultural production was found to be either non-existent due to energy consumption in the conversion process, or up to 2–6000TWh (biogas from residues and waste and ethanol from woody biomass in the more optimistic cases.

  17. The limitation and modification of flux-limited diffusion theory

    International Nuclear Information System (INIS)

    Liu Chengan; Huang Wenkai

    1986-01-01

    The limitation of various typical flux-limited diffusion theory and advantages of asymptotic diffusion theory with time absorption constant are analyzed and compared. The conclusions are as following: Though the flux-limited problem in neutron diffusion theory are theoretically solved by derived flux-limited diffusion equation, it's going too far to limit flux due to the inappropriate assumption in deriving flux-limited diffusion equation. The asymptotic diffusion theory with time absorption constant has eliminated the above-mentioned limitation, and it is more accurate than flux-limited diffusion theory in describing neutron transport problem

  18. [Does medicine limit enlightenment?].

    Science.gov (United States)

    Schipperges, H

    1977-01-01

    In the first, historical part the most important programs of "Medical Enlightenment", are pointed out, beginning with Leibniz, followed by the public health movement of the 18th century, up to the time of Immanuel Kant. Based on this historical background several concepts of a "Medical Culture" are analysed in detail, for instance the "Theorie einer Medizinal-Ordnung" by Johann Benjamin Ehrhard (1800), the "Medicinische Reform" by Rudolf Virchow (1848) and the programs of the "Gesellschaft Deutscher Naturforscher und Arzte" (about 1850-1890), the latter bearing both scientific and political character. Following the historical part, the question is raised whether "Enlightenment" is limited by medicine and whether medicine is able to provide a program for individual health education resulting in a more cultivated style of private life, and lastly how this might be realized.

  19. Personal Freedom beyond Limits

    Directory of Open Access Journals (Sweden)

    Juan Fernando Sellés

    2013-07-01

    Full Text Available In this work we distinguish between freedom in the human manifestations (intelligence, will,actions and personal freedom in the personal intimacy. This second is beyond the freedom reached bythe classic and modern thought, since it takes root in the personnel act of being. Because of it, it is not possible to characterize this freedom like the classic description as ‘domain over the own acts’, becauseit is a description of ‘categorial’ order; neither like present day ‘autonomy’ or ‘independence’, becausethe existence of one person alone is impossible, since ‘person’ means relation, personal free openingto other persons, description of the ‘transcendental’ order and, therefore, to the margin of limits.

  20. Drinking to the Limit

    DEFF Research Database (Denmark)

    Järvinen, Margaretha; Ellersgaard, Christoph Houman; Larsen, Anton Grau

    2014-01-01

    : economic, cultural, inherited and organisational. A range of variables measuring alcohol norms, drinking practices and alcohol-related problems are then inserted into the space. This article identifies status differences in the employees’ drinking patterns indicating that respondents with large amounts...... of economic, cultural and inherited capital are more responsive to alcohol-related health messages than respondents (and especially males) occupying positions low in the social space. This, however, does not mean that respondents from dominant groups have ‘safe’ drinking habits, as these are defined...... by the Danish National Health Board. Rather, this article identifies a relatively large group of high-positioned respondents balancing at the limits of risky drinking – or transgressing them, if measured by international standards....

  1. Limits to oil pricing

    International Nuclear Information System (INIS)

    Austvik, O.G.

    1992-01-01

    The bad record of oil price forecasting indicates that conventional oil market models should be critically reassessed. Scenario planning may be one alternative approach. This approach does not contradict other theories of the market. But it claims that no single discipline is able to tell the whole truth about the market. The SP approach stresses and clarifies the role of uncertainty. It argues that without a cross-disciplinary approach, with an adequate choice of parameters, at the right level of in depth discussion, the analysis may either lose essential input or drown in detail. As an example of the methodology, an analysis of the oil market in the 1990s is presented. This shows how upper and lower limits for the price can be constructed, and which actual price development can be expected, in a combination of economic and political reasoning. (author)

  2. Wave Propagation in the Effective Model of Alternating Porous and Impermeable Solid Layers Propagation des ondes dans un modèle effectif constitué de couches solides alternativement poreuses et imperméables

    Directory of Open Access Journals (Sweden)

    Molotkov L.

    2006-12-01

    ées. Ils ont été récemment remis à jour pour la description des roches fracturées (Hsu et Schoenberg, 1993. Dans ce cas, il s'agit de modèles stratifiés élastiques à fractures. Toutefois, les roches-réservoirs sont poreuses et perméables. La porosité et la perméabilité sont prises en compte dans le modèle bien connu de Biot. Les séquences poreuses finement stratifiées ont certaines propriétés distinctes qui font l'objet de recherches actuelles (Schoenberg, 1996. Il est donc devenu important de remettre à jour les concepts développés sur les milieux poreux. Bakulin et Molotkov (1998, 1997 ont effectué la première étape en généralisant aux milieux poroélastiques la technique d'homogénéisation de Backus. Nous nous concentrons ici sur un cas particulier où il n'y a qu'une direction préférentielle de l'écoulement du fluide dans les roches poreuses. Ceci peut être provoqué par la présence de barrières imperméables ou de formes lenticulaires, qui sont modélisées comme un ensemble de couches solides croisant des milieux poreux. Un tel modèle correspond à des roches fortement anisotropes vis-à-vis des propriétés hydrauliques, et présente une très forte anisotropie de structure de son espace poreux.

  3. Limit, breakthrough and prosperity

    International Nuclear Information System (INIS)

    Takahashi, Minoru

    1973-01-01

    It is pointed out that the flow toward serious crises is in progress with regard to energy and industrial problems. Technical and industrial preparation and countermeasure to the flow are proposed, and the existence of a certain new world attainable on the assumption that the countermeasure is successful is described. The relation between oil output and the increasing demand for energy is pointed out as a subject matter of the crisis. The contribution of oil energy to total energy, after the output turns to decreasing process, decreases by 177.87x10 6 tons (converted to coal at the rate 6848 kcal/kg) per year at maximum. Converted to the GNP of the world, this becomes (425 dollar/ton x 177.87 x 10 6 ton=75.6 x 10 9 dollar). This fluctuation width in a year must be compensated by the change of industrial structure and energy supplying means. The countermeasure and preparation are proposed from the viewpoints of the energy and the industrial structure in which nuclear power generation plays important role. The largest production on the earth limited by energy consumption and the temperature balance on the earth is investigated, and the perspective in the future is given. (Yamamoto, Y.)

  4. Negative Peer Cultures in Juvenile Institutional Settings: Staff as Couch Coaches or Couch Slouches

    Science.gov (United States)

    Ahonen, Lia; Degner, Jurgen

    2012-01-01

    Juveniles in institutional treatment lack the skills to cope with societal expectations, rules, and moral values. If not prevented by staff, bonds are established with other deviant youth and the placement serves as a perfect "school of crime." This article aims to explore staff strategies to prevent negative peer cultures, as well as…

  5. The limits of deterrence

    International Nuclear Information System (INIS)

    Tertrais, Bruno

    2009-01-01

    The objective of this contribution is to propose a better insight of the validity of the theory of deterrence, and of related doctrines in more complex and more various situations than in the past: emergence of powers like China and India, of new nuclear States like North Korea and Pakistan, of countries planning to acquire nuclear weapons like Iran, and possibility of a new wave of nuclear proliferation in Middle-East and north-eastern Asia. It also aims at providing arguments in the debates on the struggle against nuclear proliferation and on the future of deterrence. The author first presents and comments the principles of deterrence, and illustrates them by more or less recent historical situations (Iran during the war with Iraq, USA after Pearl Harbour, Arab-Israeli wars, Iraq, and so on). He notably outlines that the notion of deterrence is present in Islamic culture, and that Iran has well integrated it in its defence strategy. Examples of statements and behaviours of other Arab leaders are discussed. The author also briefly indicates how the deterrence strategy is present in the official doctrines of Russia, India, Pakistan, and North Korea. In a second part, based on various examples, the author analyses the practical limitations of deterrence by distinguishing the psychological dimension (bounded rationality, political leaders suffering from various psychological problems, importance of the ideological and spiritual dimension, values prevailing on interests, the case of Iran), and the strategic dimension (good understanding of the enemy, sensitivity of the threat of massive damages, existence of a single decision centre and of an efficient communication). The author finally proposes seven recommendations for better deterrence efficiency

  6. Over the limit.

    Science.gov (United States)

    Qu, G

    1989-01-01

    With over 1 billion population, China is adding some 15 million to that total each year. And in the 18 years from 1982 to 2000, the net increase of Chinese population is expected to exceed 200 million. Because of the gigantic pressure from population and some mistakes in policies, the levels of ecological destruction and environment pollution are both serious. This includes deforestation, grassland degradation, desert encroachment, water resources shortage, and waste of mineral resources. Natural disasters including floods and droughts caused by those problems happen more and more frequently. If development damages the resource base, it can only result in a false prosperity, the so-called hollow economy. A large number of environmental problems result directly or indirectly from the pressure of population growth. Studies show that the appropriate number of people that can be supported by China's 9.6 million sq. km is about 700 million. However, this limit is now exceeded by over 300 million people, and will be exceeded by 500 million by the end of this century. Therefore, the task is to implement a birth control policy. At present, in urban areas, the goal of family planning has been reached, but in rural areas hard work is needed. Population control in urban areas, especially in big and medium-sized cities, includes dealing with the inflow of migrants from the countryside. There are 13 cities with a population above 2 million, 37 cities above 1-2 million, and 75 cities above 0.5-1 million. A lot of cities are very crowded, exerting great pressure on the environment. The booming of rural enterprises could provide a good solution to control the flow of rural people into big and medium-sized cities. The relationship between population, resources, environment, and development should be managed properly.

  7. The turbulent viscosity models and their experimental validation; Les modeles de viscosite turbulente et leur validation experimentale

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This workshop on turbulent viscosity models and on their experimental validation was organized by the `convection` section of the French society of thermal engineers. From the 9 papers presented during this workshop, 8 deal with the modeling of turbulent flows inside combustion chambers, turbo-machineries or in other energy-related applications, and have been selected for ETDE. (J.S.)

  8. Limitations of Expert Evidence

    Directory of Open Access Journals (Sweden)

    Serpil Salaçin

    1997-10-01

    Full Text Available Limitations of Expert Evidence Edited by Stephen Leadbeatter MB ChB MCRPath ISBN 1 86016 029 8 Printed in Great Britain by Cathedral Print Services Ltd, Salisbury, 1996 Kitap 25 Ekim 1994 te The Royal College of Physicians ve The Royal College of Pathologists tarafından düzenlenen konferanstan sonra hekimlere ve avukatlara konuyu tartışmaya açmak için basılmış. Bilirkişi görüşünün temel filozofisinin, bu görevi yapanlar ve bu hizmeti alanların yapabileceklerinin sınırlarının tartışılması amaçlanmış.Seksen altı sayfadan oluşan kitabın fiatı on iki İngiliz Sterlini. Kitap üç bölüm ve bunların altında toplanan on ana başlıktan oluşmakta. Elinize aldığınızda küçük boyutu ve anlaşılır dili ile hemen okunup bitirelecek kitaplardan sanılıyor. En azından ben böyle düşünmüştüm. Ancak daha L A Tuınberg ve A J Bellinham’ın ön yazısında ben çarpıldım. Değerli yazarların kaleme aldığı başlıklar ve gündeme getirdiği tartışmaların tüm Adli Bilimlerle uğraşanların dikkatle okuması gereken cinsten olduğu kanısındayım. Birinci bölüm The Legal Perspective iki anabaşlıktan oluşuyor, The Criminal legal perspective Honour Judje Martin Stephens tarafından yazılmış,bilirkişi olarak görev yapabilmek için belgelenmiş bir eğitim olması gerektiği, mahkemelerde ya da yazılı raporlarda verilebilecek görüşlerin incelikleri tartışılmış. Bu bölümün ikinci anabaşlığı The civil legal perspective avukat Jennifer Cummin tarafından yazılmış. Toplum gözünde bilirkişinin anlamı ve mahkemenin bilirkişi görüşünü değişmez bilimsel doğru gibi algılayarak düştüğü bilimsel yanılgı ve raporlardaki kavram farkı dile getirilmiş. İkinci Bölüm The Medical And Scientific Perspective başlığı altında Roger C Evans MD Clinical evidence başlığında toplumun hasta tedavisi ve bilirkişilik hizmetinden beklentilerinin unrealistik olduğu ve

  9. FED pumped limiter configuration issues

    International Nuclear Information System (INIS)

    Haines, J.R.; Fuller, G.M.

    1983-01-01

    Impurity control in the Fusion Engineering Device (FED) is provided by a toroidal belt pumped limiter. Limiter design issues addressed in this paper are (1) poloidal location of the limiter belt, (2) shape of the limiter surface facing the plasma, and (3) whether the belt is pumped from one or both sides. The criteria used for evaluation of limiter configuration features were sensitivity to plasma edge conditions and ease of maintenance and fabrication. The evaluation resulted in the selection of a baseline FED limiter that is located at the bottom of the device and has a flat surface with a single leading edge

  10. Charter Halibut Limited Access Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This limited access system limits the number of charter vessels that may participate in the guided sport fishery for halibut in area 2C and 3A. NMFS issues a charter...

  11. Guidelines for setting speed limits

    CSIR Research Space (South Africa)

    Wium, DJW

    1986-02-01

    Full Text Available A method is described for setting the speed limit for a particular road section. Several speed limits based on different criteria are described for each of nine traffic and road factors. The most appropriate speed limit for each relevant factor...

  12. Material limitations on the detection limit in refractometry.

    Science.gov (United States)

    Skafte-Pedersen, Peder; Nunes, Pedro S; Xiao, Sanshui; Mortensen, Niels Asger

    2009-01-01

    We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η, with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and filling fractions into account, the detection limit declines. As an example we discuss the fundamental limits of silicon-based high-Q resonators, such as photonic crystal resonators, for sensing in a bio-liquid environment, such as a water buffer. In the transparency window (λ ≳ 1100 nm) of silicon the detection limit becomes almost independent on the filling fraction, while in the visible, the detection limit depends strongly on the filling fraction because the silicon absorbs strongly.

  13. Material Limitations on the Detection Limit in Refractometry

    Directory of Open Access Journals (Sweden)

    Niels Asger Mortensen

    2009-10-01

    Full Text Available We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and filling fractions into account, the detection limit declines. As an example we discuss the fundamental limits of silicon-based high-Q resonators, such as photonic crystal resonators, for sensing in a bio-liquid environment, such as a water buffer. In the transparency window (λ ≳ 1100 nm of silicon the detection limit becomes almost independent on the filling fraction, while in the visible, the detection limit depends strongly on the filling fraction because the silicon absorbs strongly.

  14. Material limitations on the detection limit in refractometry

    DEFF Research Database (Denmark)

    Skafte-Pedersen, Peder; Nunes, Pedro; Xiao, Sanshui

    2009-01-01

    We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and...

  15. Optimum shapes for pump limiters

    International Nuclear Information System (INIS)

    Ulrickson, M.

    1982-05-01

    The design of a pump limiter depends strongly on the details of the plasma scrapeoff zone. A model has been developed which allows the transport coefficients in the scrapeoff to be functions of n and t. This model has been used to predict scrapeoff profiles for FED/INTOR. The profiles are used to find and analyze limiter profiles. The results suggest the use of limiter shapes which curve toward the plasma

  16. ICRF power limitation relation to density limit in ASDEX

    International Nuclear Information System (INIS)

    Ryter, F.

    1992-01-01

    Launching high ICRF power into ASDEX plasmas required good antenna-plasma coupling. This could be achieved by sufficient electron density in front of the antennas i.e. small antenna-plasma distance (1-2 cm) and moderate to high line-averaged electron density compared to the density window in ASDEX. These are conditions eventually close to the density limit. ICRF heated discharges terminated by plasma disruptions caused by the RF pulse limited the maximum RF power which can be injected into the plasma. The disruptions occurring in these cases have clear phenomenological similarities with those observed in density limit discharges. We show in this paper that the ICRF-power limitation by plasma disruptions in ASDEX was due to reaching the density limit. (author) 3 refs., 3 figs

  17. Limit cycles in quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, Patrick

    2015-04-27

    In this thesis we investigate Limit Cycles in Quantum Systems. Limit cycles are a renormalization group (RG) topology. When degrees of freedom are integrated out, the coupling constants flow periodically in a closed curve. The presence of limit cycles is restricted by the necessary condition of discrete scale invariance. A signature of discrete scale invariance and limit cycles is log-periodic behavior. The first part of this thesis is concerned with the study of limit cycles with the similarity renormalization group (SRG). Limit cycles are mainly investigated within conventional renormalization group frameworks, where degrees of freedom, which are larger than a given cutoff, are integrated out. In contrast, in the SRG potentials are unitarily transformed and thereby obtain a band-diagonal structure. The width of the band structure can be regarded as an effective cutoff. We investigate the appearance of limit cycles in the SRG evolution. Our aim is to extract signatures as well as the scaling factor of the limit cycle. We consider the 1/R{sup 2}-potential in a two-body system and a three-body system with large scattering lengths. Both systems display a limit cycle. Besides the frequently used kinetic energy generator we apply the exponential and the inverse generator. In the second part of this thesis, Limit Cycles at Finite Density, we examine the pole structure of the scattering amplitude for distinguishable fermions at zero temperature in the medium. Unequal masses and a filled Fermi sphere for each fermion species are considered. We focus on negative scattering lengths and the unitary limit. The properties of the three-body spectrum in the medium and implications for the phase structure of ultracold Fermi gases are discussed.

  18. Magnetic shielding of a limiter

    International Nuclear Information System (INIS)

    Brevnov, N.N.; Stepanov, S.B.; Khimchenko, L.N.; Matthews, G.F.; Goodal, D.H.J.

    1991-01-01

    Localization of plasma interaction with material surfaces in a separate chamber, from where the escape of impurities is hardly realized, i.e. application of magnetic divertors or pump limiters, is the main technique for reduction of the impurity content in a plasma. In this case, the production of a divertor configuration requires a considerable power consumption and results in a less effective utilization of the magnetic field volume. Utilization of a pump limiter, for example the ICL-type, under tokamak-reactor conditions would result in the extremely high and forbidden local heat loadings onto the limiter surface. Moreover, the magnetically-shielded pump limiter (MSL) was proposed to combine positive properties of the divertor and the pump limiter. The idea of magnetic shielding is to locate the winding with current inside the limiter head so that the field lines of the resultant magnetic field do not intercept the limiter surface. In this case the plasma flows around the limiter leading edges and penetrates into the space under the limiter. The shielding magnetic field can be directed either counter the toroidal field or counter the poloidal one of a tokamak, dependent on the concrete diagram of the device. Such a limiter has a number of advantages: -opportunity to control over the particle and impurity recycling without practical influence upon the plasma column geometry, - perturbation of a plasma column magnetic configuration from the side of such a limiter is less than that from the side of the divertor coils. The main deficiency is the necessity to locate active windings inside the discharge chamber. (author) 5 refs., 3 figs

  19. Évolution des contraintes résiduelles dans la couche de diffusion d’un acier modèle Fe-Cr-C nitruré

    DEFF Research Database (Denmark)

    Jegou, Sébastien; Barrallier, Laurent; Somers, Marcel A. J.

    2011-01-01

    Limiter la fatigue et la corrosion des pièces est possible grâce à une nitruration. Des contraintes résiduelles en découlent. Le rôle de la diffusion du carbone sur le développement de ces contraintes a été étudié sur un acier modèle Fe-3%m.Cr-0.35%m.C.......Limiter la fatigue et la corrosion des pièces est possible grâce à une nitruration. Des contraintes résiduelles en découlent. Le rôle de la diffusion du carbone sur le développement de ces contraintes a été étudié sur un acier modèle Fe-3%m.Cr-0.35%m.C....

  20. Solubility limits on radionuclide dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Kerrisk, J.F.

    1984-12-31

    This paper examines the effects of solubility in limiting dissolution rates of a number of important radionuclides from spent fuel and high-level waste. Two simple dissolution models were used for calculations that would be characteristics of a Yucca Mountain repository. A saturation-limited dissolution model, in which the water flowing through the repository is assumed to be saturated with each waste element, is very conservative in that it overestimates dissolution rates. A diffusion-limited dissolution model, in which element-dissolution rates are limited by diffusion of waste elements into water flowing past the waste, is more realistic, but it is subject to some uncertainty at this time. Dissolution rates of some elements (Pu, Am, Sn, Th, Zr, Sm) are always limited by solubility. Dissolution rates of other elements (Cs, Tc, Np, Sr, C, I) are never solubility limited; their release would be limited by dissolution of the bulk waste form. Still other elements (U, Cm, Ni, Ra) show solubility-limited dissolution under some conditions. 9 references, 3 tables.

  1. FUEL CASK IMPACT LIMITER VULNERABILITIES

    International Nuclear Information System (INIS)

    Leduc, D.; England, J.; Rothermel, R.

    2009-01-01

    Cylindrical fuel casks often have impact limiters surrounding just the ends of the cask shaft in a typical 'dumbbell' arrangement. The primary purpose of these impact limiters is to absorb energy to reduce loads on the cask structure during impacts associated with a severe accident. Impact limiters are also credited in many packages with protecting closure seals and maintaining lower peak temperatures during fire events. For this credit to be taken in safety analyses, the impact limiter attachment system must be shown to retain the impact limiter following Normal Conditions of Transport (NCT) and Hypothetical Accident Conditions (HAC) impacts. Large casks are often certified by analysis only because of the costs associated with testing. Therefore, some cask impact limiter attachment systems have not been tested in real impacts. A recent structural analysis of the T-3 Spent Fuel Containment Cask found problems with the design of the impact limiter attachment system. Assumptions in the original Safety Analysis for Packaging (SARP) concerning the loading in the attachment bolts were found to be inaccurate in certain drop orientations. This paper documents the lessons learned and their applicability to impact limiter attachment system designs

  2. Test limits using correlated measurements

    NARCIS (Netherlands)

    Albers, Willem/Wim; Arts, G.R.J.; Kallenberg, W.C.M.

    1998-01-01

    In the standard model for inspection of manufactured parts measurements of the characteristic of interest are subject to, typically small, measurement errors. This leads to test limits which are slightly more strict than the corresponding specification limits. Quite often, however, such direct

  3. New power limits for extremes

    NARCIS (Netherlands)

    Balkema, G.

    2013-01-01

    For order statistics there is a deceptively simple link between affine and power norming, using exponential transforms. This link does not tell the whole story about limit distributions. The exponential transforms W=eV and W=−e−V yield limit variables which are either positive or negative. Under

  4. Dose limits for ionising radiation

    International Nuclear Information System (INIS)

    Gifford, D.

    1989-01-01

    Dose limits for exposure to ionising radiation are assessed to see if they give sufficient protection both for the occupationally exposed and for the general public. It is concluded that current limits give a level of safety that satisfies the necessary criteria in the light of present knowledge and further reductions would be unlikely to improve standards of safety. (author)

  5. Beam-limiting and radiation-limiting interlocks

    International Nuclear Information System (INIS)

    Macek, R.J.

    1996-01-01

    This paper reviews several aspects of beam-limiting and radiation- limiting interlocks used for personnel protection at high-intensity accelerators. It is based heavily on the experience at the Los Alamos Neutron Science Center (LANSCE) where instrumentation-based protection is used extensively. Topics include the need for ''active'' protection systems, system requirements, design criteria, and means of achieving and assessing acceptable reliability. The experience with several specific devices (ion chamber-based beam loss interlock, beam current limiter interlock, and neutron radiation interlock) designed and/or deployed to these requirements and criteria is evaluated

  6. Beam-limiting and radiation-limiting interlocks

    Energy Technology Data Exchange (ETDEWEB)

    Macek, R.J.

    1996-04-01

    This paper reviews several aspects of beam-limiting and radiation- limiting interlocks used for personnel protection at high-intensity accelerators. It is based heavily on the experience at the Los Alamos Neutron Science Center (LANSCE) where instrumentation-based protection is used extensively. Topics include the need for ``active`` protection systems, system requirements, design criteria, and means of achieving and assessing acceptable reliability. The experience with several specific devices (ion chamber-based beam loss interlock, beam current limiter interlock, and neutron radiation interlock) designed and/or deployed to these requirements and criteria is evaluated.

  7. Study of the coastal atmospheric boundary layer during ESCOMPTE 2001. Evaluation and improvement of the efficiency of a UHF radar; Etude de la couche limite atmospherique cotiere durant ESCOMPTE 2001. Evaluation et amelioration des performances d'un radar UHF

    Energy Technology Data Exchange (ETDEWEB)

    Puygrenier, V.

    2005-12-15

    Forecasting of pollution events was the main objective of the ESCOMPTE-2001 campaign, which took place in the Marseille/Fos/Berre heterogeneous area (southeastern France) in the early summer 2001. This goal requires good understanding and taking into account, by physico-chemical numerical models, of the physical processes in the Atmospheric Boundary Layer (ABL), in which pollutants are emitted, transported and diffused. In the ESCOMPTE-2001 campaign context, this work was devoted to study the low troposphere during sea breeze events, related to meteorological conditions responsible for poor air quality of coastal areas. It presents notably an oscillation of the sea breeze intensity and competitions of locals and regional sea breeze, which change the advective time of the marine air above the continental surface and thus influence the ABL development and its pollutants concentration. This study is based principally on the network of four UHF wind profilers radars set up on the coastal area of Marseille/Fos/Berre, allowing a continuous three-dimensional description of the sea breeze flow and the ABL. For the needs of this phenomenological work, methodological developments was realized to improve the measurement of ABL turbulent properties with UHF radars (terms of turbulent kinetic energy budget) and the use of wind profilers network for the study of pollutants plumes trajectory-graphy. (author)

  8. Mass and heat transfers in the parietal boundary layer and inside a flat porous wall submitted to effusion or transpiration; Transferts de masse et de chaleur dans la couche limite parietale et a l'interieur d'une paroi poreuse plane soumise a de l'effusion ou de la transpiration

    Energy Technology Data Exchange (ETDEWEB)

    Bellettre, J.

    1998-12-01

    The flows and the heat transfer near and inside a porous wall subjected to an internal flow are numerically and experimentally studied. Numerical simulations of the main flow are performed using a classical model of turbulence (RNG k-{xi} model). A discrete modeling of blowing through a porous plate is developed in order to predict interactions between the main flow and the injected fluid. Numerical results are in good agreement with experimental data obtained with a subsonic wind tunnel. The coupling between the heat transfer near and inside porous plates is studied for different injection rates, main flow temperatures and internal exchange surfaces of porous media. Surfaces temperatures are calculated using a nodal model of internal heat transfer, linked to the model of boundary layer submitted to injection. By comparing numerical and experimental temperatures of walls, the heat transfer coefficients inside porous media are calculated. In order to improve the thermal protection of walls, the transpiration with a liquid is studied. Experimental results, obtained with ethanol injection whereas the main flow is gaseous, show an important enhancement of the protection process. The coolant evaporation rate is calculated using measurement of mass fraction in the boundary layer and is used for the numerical study of mass transfer in the boundary layer. (author)

  9. Experimental and modeling study of the impact of vertical transport processes from the boundary-layer on the variability and the budget of tropospheric ozone; Etude experimentale et numerique de l'influence des processus de transport depuis la couche-limite sur la variabilite et le bilan d'ozone tropospherique

    Energy Technology Data Exchange (ETDEWEB)

    Colette, A

    2005-12-15

    Closing the tropospheric ozone budget requires a better understanding of the role of transport processes from the major reservoirs: the planetary boundary layer and the stratosphere. Case studies lead to the identification of mechanisms involved as well as their efficiency. However, their global impact on the budget must be addressed on a climatological basis. This manuscript is thus divided in two parts. First, we present case studies based on ozone LIDAR measurements performed during the ESCOMPTE campaign. This work consists in a data analysis investigation by means of a hybrid - Lagrangian study involving: global meteorological analyses, Lagrangian particle dispersion computation, and mesoscale, chemistry - transport, and Lagrangian photochemistry modeling. Our aim is to document the amount of observed ozone variability related to transport processes and, when appropriate, to infer the role of tropospheric photochemical production. Second, we propose a climatological analysis of the respective impact of transport from the boundary-layer and from the tropopause region on the tropospheric ozone budget. A multivariate analysis is presented and compared to a trajectography approach. Once validated, this algorithm is applied to the whole database of ozone profiles collected above Europe during the past 30 years in order to discuss the seasonal, geographical and temporal variability of transport processes as well as their impact on the tropospheric ozone budget. The variability of turbulent mixing and its impact on the persistence of tropospheric layers will also be discussed. (author)

  10. Exchanges in boundary layer and low troposphere and consequences on pollution of Fos-Berre-Marseille area (ESCOMPTE experiment); Echanges dans la couche limite et la base troposphere et consequences sur la pollution dans la region de Fos-Berre-Marseille (Experience ESCOMPTE)

    Energy Technology Data Exchange (ETDEWEB)

    Moppert, C

    2006-02-15

    The aim of this study is to analyse the vertical structure of the low troposphere during the ESCOMPTE campaign in relation with transport and diffusion of pollutants. This analysis shows the difficulty to define a boundary layer. It allows us to highlight a complex superposition of several internal boundary layers, particularly near the coast. The study of the layer where pollution may be accumulated or diluted pointed out the fact that pollution is trapped near the surface, close to the coastline under sea-breeze conditions whereas it is advected over the mountains where the boundary layers are deeper. During sea-breeze conditions, the ozone concentration is paradoxically weak near the sources at the coastline (titration). Over the mountains, the strong developments of the boundary layers result in a mixing between the highly polluted low troposphere and the surface which enhances the ozone concentration. (author)

  11. The Limits of Exercise Physiology

    DEFF Research Database (Denmark)

    Gabriel, Brendan M; Zierath, Juleen R

    2017-01-01

    Many of the established positive health benefits of exercise have been documented by historical discoveries in the field of exercise physiology. These investigations often assess limits: the limits of performance, or the limits of exercise-induced health benefits. Indeed, several key findings have...... been informed by studying highly trained athletes, in addition to healthy or unhealthy people. Recent progress has been made in regard to skeletal muscle metabolism and personalized exercise regimes. In this perspective, we review some of the historical milestones of exercise physiology, discuss how...

  12. Nuclear Structure at the Limits

    International Nuclear Information System (INIS)

    Nazarewicz, W.

    1998-01-01

    One of the frontiers of todays nuclear science is the journey to the limits of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The tour to the limits is not only a quest for new, exciting phenomena, but the new data are expected, as well, to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this series of lectures, current developments in nuclear structure at the limits are discussed from a theoretical perspective, mainly concentrating on medium-mass and heavy nuclei

  13. Nuclear Structure at the Limits

    Energy Technology Data Exchange (ETDEWEB)

    Nazarewicz, Witold

    1997-12-31

    One of the frontiers of today`s nuclear science is the ``journey to the limits``: of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The tour to the limits is not only a quest for new, exciting phenomena but the new data are expected, as well, to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this talk, current developments in nuclear structure at the limits are discussed from a theoretical perspective.

  14. Limited Releases of Krsko NPP

    International Nuclear Information System (INIS)

    Breznik, B.; Kovac, A.

    2001-01-01

    Full text: Krsko Nuclear Power Plant is about 700 MW Pressurised Water Reactor plant located in Slovenia close to the border with Croatia. The authorised limit for the radioactive releases is basically set to 50 μSv effective dose per year to the members of the public. There is also additional limitation of total activities released in a year and concentration. The poster presents the effluents of the year 2000 and evaluated dose referring to the limits and to the natural and other sources of radiation around the plant. (author)

  15. Biased limiter experiments on text

    International Nuclear Information System (INIS)

    Phillips, P.E.; Wootton, A.J.; Rowan, W.L.; Ritz, C.P.; Rhodes, T.L.; Bengtson, R.D.; Hodge, W.L.; Durst, R.D.; McCool, S.C.; Richards, B.; Gentle, K.W.; Schoch, P.; Forster, J.C.; Hickok, R.L.; Evans, T.E.

    1987-01-01

    Experiments using an electrically biased limiter have been performed on the Texas Experimental Tokamak (TEXT). A small movable limiter is inserted past the main poloidal ring limiter (which is electrically connected to the vacuum vessel) and biased at V Lim with respect to it. The floating potential, plasma potential and shear layer position can be controlled. With vertical strokeV Lim vertical stroke ≥ 50 V the plasma density increases. For V Lim Lim > 0 the results obtained are inconclusive. Variation of V Lim changes the electrostatic turbulence which may explain the observed total flux changes. (orig.)

  16. (the so called limiting resource).

    Indian Academy of Sciences (India)

    An asymmetry in response to rainfall is not surprising in the light of Liebig's law of the minimum, which says that the yield of a crop is determined by the scarcest resource (the so called limiting resource).

  17. Limited-Access Heart Surgery

    Science.gov (United States)

    ... Surgery Menu Topics Topics FAQs Limited-Access Heart Surgery Article Info En español Thousands of heart surgeries ... with cardiovascular disease. What is minimally invasive heart surgery? In minimally invasive heart surgery, surgeons take steps ...

  18. OECD Maximum Residue Limit Calculator

    Science.gov (United States)

    With the goal of harmonizing the calculation of maximum residue limits (MRLs) across the Organisation for Economic Cooperation and Development, the OECD has developed an MRL Calculator. View the calculator.

  19. Heat kernels and critical limits

    OpenAIRE

    Pickrell, Doug

    2007-01-01

    This paper is an exposition of several questions linking heat kernel measures on infinite dimensional Lie groups, limits associated with critical Sobolev exponents, and Feynmann-Kac measures for sigma models.

  20. Multifamily Tax Subsidy Income Limits

    Data.gov (United States)

    Department of Housing and Urban Development — Multifamily Tax Subsidy Projects (MTSP) Income Limits were developed to meet the requirements established by the Housing and Economic Recovery Act of 2008 (Public...

  1. Shell model with several particles in the continuum: application to the two-proton decay; Modele en couches avec plusieurs particules dans le continuum: description de la radioactivite deux protons

    Energy Technology Data Exchange (ETDEWEB)

    Rotureau, J

    2005-02-15

    The recent experimental results concerning nuclei at the limit of stability close to the drip-lines and in particular the two-proton emitters require a development of new methodologies to reliably calculate and understand properties of those exotic physical systems. In this work we have extended the Shell Model Embedded in the Continuum (SMEC) in order to describe the coupling with two particles in the scattering continuum. We have obtained a microscopic description of the two-proton emission that takes into account the antisymmetrization of the total wavefunction, the configuration mixing and the three-body asymptotics. We have studied the decay of the 1{sub 2}{sup -} state in {sup 18}Ne in two limiting cases: (i) a sequential emission of two protons through the correlated continuum of {sup 17}F and (ii) emission of {sup 2}He cluster that disintegrates because of the final state interaction (diproton emission). Independently of the choice of the effective interaction we have observed that the two-proton emission of the 1{sub 2}{sup -} in {sup 18}Ne is mainly a sequential process; the ratio between the widths of the diproton emission and the sequential decay does not exceed 8% in any case. (author)

  2. US ITER limiter module design

    International Nuclear Information System (INIS)

    Mattas, R.F.; Billone, M.; Hassanein, A.

    1996-08-01

    The recent U.S. effort on the ITER (International Thermonuclear Experimental Reactor) shield has been focused on the limiter module design. This is a multi-disciplinary effort that covers design layout, fabrication, thermal hydraulics, materials evaluation, thermo- mechanical response, and predicted response during off-normal events. The results of design analyses are presented. Conclusions and recommendations are also presented concerning, the capability of the limiter modules to meet performance goals and to be fabricated within design specifications using existing technology

  3. Limits on the photon mass

    International Nuclear Information System (INIS)

    Vasseur, G.

    1996-03-01

    Is the photon mass strictly null as it is told in quantum electrodynamics. In fact, a coherent theory can be build with a massive photon. Experiences have been regularly led to try to make obvious an eventual non null photon mass. Superior limits more and more strict have been found. Here is given a general survey of the consequences of a non null photon mass, different methods to measure it and the achieved limits. (author). 30 refs., 1 fig

  4. Hydrodynamic Limit of Multiple SLE

    Science.gov (United States)

    Hotta, Ikkei; Katori, Makoto

    2018-04-01

    Recently del Monaco and Schleißinger addressed an interesting problem whether one can take the limit of multiple Schramm-Loewner evolution (SLE) as the number of slits N goes to infinity. When the N slits grow from points on the real line R in a simultaneous way and go to infinity within the upper half plane H, an ordinary differential equation describing time evolution of the conformal map g_t(z) was derived in the N → ∞ limit, which is coupled with a complex Burgers equation in the inviscid limit. It is well known that the complex Burgers equation governs the hydrodynamic limit of the Dyson model defined on R studied in random matrix theory, and when all particles start from the origin, the solution of this Burgers equation is given by the Stieltjes transformation of the measure which follows a time-dependent version of Wigner's semicircle law. In the present paper, first we study the hydrodynamic limit of the multiple SLE in the case that all slits start from the origin. We show that the time-dependent version of Wigner's semicircle law determines the time evolution of the SLE hull, K_t \\subset H\\cup R, in this hydrodynamic limit. Next we consider the situation such that a half number of the slits start from a>0 and another half of slits start from -a < 0, and determine the multiple SLE in the hydrodynamic limit. After reporting these exact solutions, we will discuss the universal long-term behavior of the multiple SLE and its hull K_t in the hydrodynamic limit.

  5. Passive fault current limiting device

    Science.gov (United States)

    Evans, Daniel J.; Cha, Yung S.

    1999-01-01

    A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment.

  6. The JET belt limiter tiles

    International Nuclear Information System (INIS)

    Deksnis, E.

    1988-09-01

    The belt limiter system, comprising two full toroidal rings of limiter tiles, was installed in JET in 1987. In consists of water-cooled fins with the limiter material in form of tile inbetween. The tiles are designed to absorb heat fluxes during irradiation without the surface temperature exceeding 2000 0 C and to radiate this heat between pulses to the water cooled sink whose temperature is lower than that of the vacuum vessel. An important feature of the design is to maximise the area of the radiating surface facing the water cooled fin. This leads to a tile depth much greater than the width of the tile facing the heat flux. Limiter tiles intercept particles flowing out of the plasma through the area between the two belt limiter rings and through remaining surface area of the plasma column. Power deposition to a limiter tile depends strongly on the shape of the plasma, the edge plasma properties as well as on the surface profile of the tiles. This paper will discuss the methodology that was followed in producing an optimized surface profile of the tiles. This shaped profile has the feature that the resulting power deposition profile is roughly similar for a wide range of plasma parameters. (author)

  7. Preliminary disposal limits, plume interaction factors, and final disposal limits

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2018-01-11

    In the 2008 E-Area Performance Assessment (PA), each final disposal limit was constructed as the product of a preliminary disposal limit and a plume interaction factor. The following mathematical development demonstrates that performance objectives are generally expected to be satisfied with high confidence under practical PA scenarios using this method. However, radionuclides that experience significant decay between a disposal unit and the 100-meter boundary, such as H-3 and Sr-90, can challenge performance objectives, depending on the disposed-of waste composition, facility geometry, and the significance of the plume interaction factor. Pros and cons of analyzing single disposal units or multiple disposal units as a group in the preliminary disposal limits analysis are also identified.

  8. Time-limited optimal dynamics beyond the Quantum Speed Limit

    DEFF Research Database (Denmark)

    Gajdacz, Miroslav; Das, Kunal K.; Arlt, Jan

    2015-01-01

    -off expressed in terms of the direct Hilbert velocity provides a robust prediction of the quantum speed limit and allows to adapt the control optimization such that it yields a predefined fidelity. The results are verified numerically in a multilevel system with a constrained Hamiltonian, and a classification......The quantum speed limit sets the minimum time required to transfer a quantum system completely into a given target state. At shorter times the higher operation speed has to be paid with a loss of fidelity. Here we quantify the trade-off between the fidelity and the duration in a system driven...

  9. Oxide growth during short term oxidation of stainless steels at high temperatures; Sur la croissance de la couche d'oxydes au cours de l'oxydation de courte duree des aciers inoxydables a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Galerie, A.; Combarmond, L.; Tran, M.; Wouters, Y. [Institut National Polytechnique, SIMaP, 38 - Grenoble (France); Gonzales, S. [ArcelorMittal Stainless Europe, Centre de Recherche, 62 - Isbergues (France)

    2008-07-01

    The stainless steels AISI 304, 316L, 430 and 441 were studied during high temperature exposures for short times ({<=} 2 min) corresponding to the final furnace annealing of the production lines. The temperature of the laboratory furnace was similar to that fixed in the industrial furnace for achieving complete recrystallization of the steels: 900 deg C for AISI 430, 1 060 deg C for AISI 441, 1120 deg C for both 304 and 316 austenitic grades. The flowing atmosphere exactly simulated that of the combustion of methane with air/fuel ratio of 12: 73% N{sub 2}, 16% H{sub 2}O, 8% CO{sub 2}, 3% O{sub 2}. Oxidation kinetics was followed by oxide scale thickness determination using Glow Discharge Optical Spectroscopy and also by mass change measurements. Scale growth was shown to be linear, with a rate depending on oxidation temperature, much less on the composition of the steels. Oxygen transfer at the gas-oxide interface was therefore rate-limiting. Influence of cold rolling reduction rate was of minor importance, indicating no kinetic limitation of the chromium supply from the alloy substrates. Comparative mass changes evidenced oxide vaporization at the early beginning of the process, slowing down for increasing oxidation time. Measured vaporization rates were compared with calculations using the Knudsen model and a good agreement was found with pure chromia vaporization. For long oxidation times, manganese spinel (Mn,Cr){sub 3}O{sub 4} was shown by GDOS to cover the initial chromia and vaporization rates were reduced, approaching those measured on stainless steels in the literature. (authors)

  10. Generalized Geometric Quantum Speed Limits

    Science.gov (United States)

    Pires, Diego Paiva; Cianciaruso, Marco; Céleri, Lucas C.; Adesso, Gerardo; Soares-Pinto, Diogo O.

    2016-04-01

    The attempt to gain a theoretical understanding of the concept of time in quantum mechanics has triggered significant progress towards the search for faster and more efficient quantum technologies. One of such advances consists in the interpretation of the time-energy uncertainty relations as lower bounds for the minimal evolution time between two distinguishable states of a quantum system, also known as quantum speed limits. We investigate how the nonuniqueness of a bona fide measure of distinguishability defined on the quantum-state space affects the quantum speed limits and can be exploited in order to derive improved bounds. Specifically, we establish an infinite family of quantum speed limits valid for unitary and nonunitary evolutions, based on an elegant information geometric formalism. Our work unifies and generalizes existing results on quantum speed limits and provides instances of novel bounds that are tighter than any established one based on the conventional quantum Fisher information. We illustrate our findings with relevant examples, demonstrating the importance of choosing different information metrics for open system dynamics, as well as clarifying the roles of classical populations versus quantum coherences, in the determination and saturation of the speed limits. Our results can find applications in the optimization and control of quantum technologies such as quantum computation and metrology, and might provide new insights in fundamental investigations of quantum thermodynamics.

  11. Generalized Geometric Quantum Speed Limits

    Directory of Open Access Journals (Sweden)

    Diego Paiva Pires

    2016-06-01

    Full Text Available The attempt to gain a theoretical understanding of the concept of time in quantum mechanics has triggered significant progress towards the search for faster and more efficient quantum technologies. One of such advances consists in the interpretation of the time-energy uncertainty relations as lower bounds for the minimal evolution time between two distinguishable states of a quantum system, also known as quantum speed limits. We investigate how the nonuniqueness of a bona fide measure of distinguishability defined on the quantum-state space affects the quantum speed limits and can be exploited in order to derive improved bounds. Specifically, we establish an infinite family of quantum speed limits valid for unitary and nonunitary evolutions, based on an elegant information geometric formalism. Our work unifies and generalizes existing results on quantum speed limits and provides instances of novel bounds that are tighter than any established one based on the conventional quantum Fisher information. We illustrate our findings with relevant examples, demonstrating the importance of choosing different information metrics for open system dynamics, as well as clarifying the roles of classical populations versus quantum coherences, in the determination and saturation of the speed limits. Our results can find applications in the optimization and control of quantum technologies such as quantum computation and metrology, and might provide new insights in fundamental investigations of quantum thermodynamics.

  12. The estimation of derived limits

    International Nuclear Information System (INIS)

    Harrison, N.T.; Bryant, P.M.; Clarke, R.H.; Morley, F.

    1979-08-01

    In practical radiation protection, it is often necessary to calculate limits of intake of radionuclides associated with various quantities; such limits are needed, for example, to assess the adequacy of the control of environmental contamination. In publication 26 of the International Commission on Radiological Protection (ICRP), these limits, when related to the basic limits of dose-equivalent by a defined model, are referred to as Derived Limits (DLs). In the present report the principles to be adopted by the Board in calculating DLs to be recommended for general application within the United Kingdom are outlined. DLs will be recommended for a wide range of radionuclides and for circumstances relevant to the workplace, and, more frequently, the general environment. The latter will include DLs in foodstuffs and associated environmental materials, such as soil and grass, and DLs for discharges from stacks. DLs will be related to dose equivalents for workers or members of the public for stochastic or non-stochastic effects as appropriate. Consideration will be given to relevant data on radiosensitivity, metabolism and dosimetry for children and to the physicochemical forms of radionuclides. (author)

  13. Why Property Tax Limitations Won't Limit Everyone's Taxes.

    Science.gov (United States)

    Picus, Larry

    Property tax limitation measures passed in 1978 by voters in California and Idaho contain provisions that apparently will reduce the equity of the property tax system in both states. Changes in assessment practices mandated by the new laws will shift the property tax burden away from business and commercial property and toward residential property…

  14. Derived limits for surface contamination

    CERN Document Server

    Wrixon, A D; Linsley, G S; White, D F

    1979-01-01

    Derived limits (DLs) for surface contamination were first established for use in the nuclear energy industry where a wide variety of radionuclides is encountered. They were later used in factories, hospitals, and universities, where the radionuclides used are normally fewer in number, either known or readily identifiable, and often of low toxicity. In these situations the current limits are frequently over-restrictive. This report describes a reassessment of the values in the light of more recent information on the possible pathways of exposure and the dose equivalent limits given in ICRP Publication 26. The reassessment is prompted also by the introduction of SI units. The results of the reassessment are used to produce a classification of DLs for all radionuclides for active and inactive area surfaces and for skin.

  15. Income trusts and limited partnerships

    International Nuclear Information System (INIS)

    Toews, E.L.

    1999-01-01

    This author provided a conceptual overview of income trusts and limited partnerships that are designed to pass operating cash flow directly to investors without the imposition of corporate taxes, discussed the evolution of the market, the mechanism used to price income funds, past and present performance of the sector, and made some predictions concerning the sector's future performance. 13 figs

  16. Environmental risk limits for zinc

    NARCIS (Netherlands)

    Bodar CWM; SEC

    2007-01-01

    Environmental Riks Limits (ERLs) were derived for zinc. ERLs serve as advisory values to set environmental quality standards in the Netherlands. The ERLs for zinc closely follow the outcomes of earlier discussions on zinc within the Water Framework Directive and EC Regulation 793/93. The ERLs refer

  17. Environmental risk limits for zinc

    NARCIS (Netherlands)

    Bodar CWM; SEC

    2007-01-01

    Environmental Riks Limits (ERLs) were derived for zinc. ERLs serve as advisory values to set environmental quality standards in the Netherlands. The ERLs for zinc closely follow the outcomes of earlier discussions on zinc within the Water Framework Directive and EC Regulation 793/93. The ERLs

  18. Historical Drawbacks of Limited Liability

    Directory of Open Access Journals (Sweden)

    Denis Boyle

    2016-07-01

    Full Text Available Limited liability is a human invention which has facilitated enormous economic growth around the world, particularly since the time of its general application in advanced countries during the nineteenth century. The individual legal identity of companies, coupled with the limited liability of their owners, has provided protection for investors from the risks associated with their investments. It has thus contributed to increase the sources of capital available to finance projects which might otherwise have been considered unviable. However, the legal protection offered to investors has negative consequences for other participants in economies. Speculation in stock markets often damages society. It is very important to study the drawbacks of limited liability and to suggest modifications to achieve a more stable, less volatile, economic growth in the world. Although this article goes to some lengths to recognise the work of authors who emphasise the positive historical economic contribution of limited lability, its main objective is to provoke a reflection around texts which point out the drawbacks and propose solutions.

  19. Landscape genetics and limiting factors

    Science.gov (United States)

    Samuel A. Cushman; Andrew J. Shirk; Erin L. Landguth

    2013-01-01

    Population connectivity is mediated by the movement of organisms or propagules through landscapes. However, little is known about how variation in the pattern of landscape mosaics affects the detectability of landscape genetic relationships. The goal of this paper is to explore the impacts of limiting factors on landscape genetic processes using simulation...

  20. LIMITS OF THE EARTH BIOSPHERE

    Directory of Open Access Journals (Sweden)

    Karel KUDRNA

    2011-01-01

    Full Text Available Evaluation of the state of CO2 accumulation in the atmosphere demands knowledge on possibilities of the biosphere – its photosynthetizing apparatus, conditions and limits of absorption. A decisive precondition is to determine relation of CO2 accumulation by photosynthesis in dependence on the water balance, especially on its control quantity – transpiration, which is stabilized by supporting of underground waters.

  1. Limits on light Higgs bosons

    International Nuclear Information System (INIS)

    Dawson, S.

    1988-01-01

    Experimental limits on light Higgs bosons (M/sub H/ < 5 GeV) are examined. Particular attention is paid to the process K → πH. It is shown that there may be an allowed window for light Higgs bosons between about 100 and 210 MeV. 13 refs., 2 figs

  2. 77 FR 76841 - Lending Limits

    Science.gov (United States)

    2012-12-31

    ... DEPARTMENT OF THE TREASURY Office of the Comptroller of the Currency 12 CFR Part 32 [Docket ID OCC-2012-0007] RIN 1557-AD59 Lending Limits AGENCY: Office of the Comptroller of the Currency, Treasury. ACTION: Final rule. SUMMARY: The Office of the Comptroller of the Currency (OCC) is amending its lending...

  3. 78 FR 37930 - Lending Limits

    Science.gov (United States)

    2013-06-25

    ... efforts, and the current lending limits rule recognizes the beneficial effects of netting or collateral in... transaction at issue. For a repurchase agreement or a securities loan where the collateral is cash, exposure... from the other party.\\23\\ For securities lending transactions where the collateral is other securities...

  4. 77 FR 37265 - Lending Limits

    Science.gov (United States)

    2012-06-21

    ..., less cash received from the other party. For securities lending transactions where the collateral is...;Prices of new books are listed in the first FEDERAL REGISTER issue of each #0;week. #0; #0; #0; #0;#0... OCC-2012-0007] RIN 1557-AD59 Lending Limits AGENCY: Office of the Comptroller of the Currency...

  5. Limitations of existing web services

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Limitations of existing web services. Uploading or downloading large data. Serving too many user from single source. Difficult to provide computer intensive job. Depend on internet and its bandwidth. Security of data in transition. Maintain confidentiality of data ...

  6. Graph limits and hereditary properties

    OpenAIRE

    Janson, Svante

    2011-01-01

    We collect some general results on graph limits associated to hereditary classes of graphs. As examples, we consider some classes defined by forbidden subgraphs and some classes of intersection graphs, including triangle-free graphs, chordal graphs, cographs, interval graphs, unit interval graphs, threshold graphs, and line graphs.

  7. The density limit in Tokamaks

    International Nuclear Information System (INIS)

    Alladio, F.

    1985-01-01

    A short summary of the present status of experimental observations, theoretical ideas and understanding of the density limit in tokamaks is presented. It is the result of the discussion that was held on this topic at the 4th European Tokamak Workshop in Copenhagen (December 4th to 6th, 1985). 610 refs

  8. Limit of crustal drilling depth

    Directory of Open Access Journals (Sweden)

    Y.S. Zhao

    2017-10-01

    Full Text Available Deep drilling is becoming the direct and the most efficient means in exploiting deep mineral resources, facilitating to understanding the earthquake mechanism and performing other scientific researches on the Earth's crust. In order to understand the limit of drilling depth in the Earth's crust, we first conducted tests on granite samples with respect to the borehole deformation and stability under high temperature and high pressure using the triaxial servo-controlled rock testing system. Then the critical temperature-pressure coupling conditions that result in borehole instability are derived. Finally, based on the testing results obtained and the requirements for the threshold values of borehole deformations during deep drilling, the limit of drilling depth in the Earth's crust is formulated with ground temperature.

  9. A Randomized Central Limit Theorem

    International Nuclear Information System (INIS)

    Eliazar, Iddo; Klafter, Joseph

    2010-01-01

    The Central Limit Theorem (CLT), one of the most elemental pillars of Probability Theory and Statistical Physics, asserts that: the universal probability law of large aggregates of independent and identically distributed random summands with zero mean and finite variance, scaled by the square root of the aggregate-size (√(n)), is Gaussian. The scaling scheme of the CLT is deterministic and uniform - scaling all aggregate-summands by the common and deterministic factor √(n). This Letter considers scaling schemes which are stochastic and non-uniform, and presents a 'Randomized Central Limit Theorem' (RCLT): we establish a class of random scaling schemes which yields universal probability laws of large aggregates of independent and identically distributed random summands. The RCLT universal probability laws, in turn, are the one-sided and the symmetric Levy laws.

  10. Adiabatic limit in perturbation theory

    CERN Document Server

    Epstein, H

    1976-01-01

    It is shown that, with correct mass and wave function renormalization, the time-ordered products for Wick polynomials T(L(y/sub 1/)...L(y/sub n/)) constructed by a method outlined in a previous paper (Epstein and Glaser, 1970) are such that the vectors of the form integral T(L(y/sub 1/)...L(y/sub n/)) g(y/sub 1/)...g(y/sub n/) psi dy/sub 1/...dy/sub n/ have limits when g tends to a constant, provided psi is chosen in a suitable dense domain. It follows that the S-matrix has unitary adiabatic limit as an operator-valued formal power series in Fock space. (4 refs).

  11. Surfactants at the Design Limit.

    Science.gov (United States)

    Czajka, Adam; Hazell, Gavin; Eastoe, Julian

    2015-08-04

    This article analyzes how the individual structural elements of surfactant molecules affect surface properties, in particular, the point of reference defined by the limiting surface tension at the aqueous cmc, γcmc. Particular emphasis is given to how the chemical nature and structure of the hydrophobic tails influence γcmc. By comparing the three different classes of surfactants, fluorocarbon, silicone, and hydrocarbon, a generalized surface packing index is introduced which is independent of the chemical nature of the surfactants. This parameter ϕcmc represents the volume fraction of surfactant chain fragments in a surface film at the aqueous cmc. It is shown that ϕcmc is a useful index for understanding the limiting surface tension of surfactants and can be useful for designing new superefficient surfactants.

  12. Nuclear Structure at the Limits

    Energy Technology Data Exchange (ETDEWEB)

    Nazarewicz, W.

    1998-01-12

    One of the frontiers of today�s nuclear science is the �journey to the limits� of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The tour to the limits is not only a quest for new, exciting phenomena, but the new data are expected, as well, to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this series of lectures, current developments in nuclear structure at the limits are discussed from a theoretical perspective, mainly concentrating on medium-mass and heavy nuclei.

  13. Limitation and life in space

    Science.gov (United States)

    Israel, Marvin; Smith, T. Scott

    1986-08-01

    ``The Earth is the very quintescence of the human condition...,'' says Hannah Arendt. Georg Simmel writes: ``The stranger is by nature no `owner of soil'—soil not only in the physical, but also in the figurative sense of a life-substance which is fixed, if not in a point in space, at least in an ideal point of social environment.'' How will no longer being Earthbound affect persons' experience of themselves and of others? Space colonization offers an opportunity for new self-definition by the alteration of existing limits. Thus ``limitation'' is a useful concept for exploring the physical, social and psychological significance of the colonization of space. Will people seek the security of routine, of convention, of hierarchy as in the military model governing our present-day astronauts? or will they seek to maximize the freedom inherent in extraordinary living conditions—as bohemians, deviants, travelers?

  14. Limited taste discrimination in Drosophila.

    Science.gov (United States)

    Masek, Pavel; Scott, Kristin

    2010-08-17

    In the gustatory systems of mammals and flies, different populations of sensory cells recognize different taste modalities, such that there are cells that respond selectively to sugars and others to bitter compounds. This organization readily allows animals to distinguish compounds of different modalities but may limit the ability to distinguish compounds within one taste modality. Here, we developed a behavioral paradigm in Drosophila melanogaster to evaluate directly the tastes that a fly distinguishes. These studies reveal that flies do not discriminate among different sugars, or among different bitter compounds, based on chemical identity. Instead, flies show a limited ability to distinguish compounds within a modality based on intensity or palatability. Taste associative learning, similar to olfactory learning, requires the mushroom bodies, suggesting fundamental similarities in brain mechanisms underlying behavioral plasticity. Overall, these studies provide insight into the discriminative capacity of the Drosophila gustatory system and the modulation of taste behavior.

  15. Limit laws for exponential families

    OpenAIRE

    Balkema, August A.; Klüppelberg, Claudia; Resnick, Sidney I.

    1999-01-01

    For a real random variable [math] with distribution function [math] , define ¶ [math] ¶ The distribution [math] generates a natural exponential family of distribution functions [math] , where ¶ [math] ¶ We study the asymptotic behaviour of the distribution functions [math] as [math] increases to [math] . If [math] then [math] pointwise on [math] . It may still be possible to obtain a non-degenerate weak limit law [math] by choosing suitable scaling and centring constants [math] an...

  16. FAIR VALUE: UTILITY AND LIMITS

    OpenAIRE

    Valentin Gabriel Cristea

    2015-01-01

    This paper presents the utility and the limits of the fair value. We believe that any new product must be tried and tested before being imposed on the market and must be accepted by all potential users and those who will be affected, directly or indirectly and its advantages, disadvantages, risks, its cost must be predetermined and analyzed in a comprehensive and objective.We ask: Do financial statements at fair value meet users' expectations? The requirement to use fair value pricing mode...

  17. On Uselessness of Limit Orders

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Martin

    2007-01-01

    Roč. 2007, č. 24 (2007), s. 45-57 ISSN 1212-074X R&D Projects: GA ČR GD402/03/H057; GA ČR GA402/07/1113; GA ČR(CZ) GA402/06/1417 Institutional research plan: CEZ:AV0Z10750506 Keywords : market microstructure * limit order market * portfolio selection Subject RIV: AH - Economics

  18. Limits to global groundwater consumption

    Science.gov (United States)

    de Graaf, I.; Van Beek, L. P.; Sutanudjaja, E.; Wada, Y.; Bierkens, M. F.

    2016-12-01

    Groundwater is the largest accessible freshwater resource worldwide and is of critical importance for irrigation, and so for global food security. For many regions of the world where groundwater abstraction exceeds groundwater recharge, persistent groundwater depletion occurs. A direct consequence of depletion is falling groundwater levels, reducing baseflows to rivers, harming ecosystems. Also, pumping costs increase, wells dry up and land subsidence can occur. Water demands are expected to increase further due to growing population, economic development and climate change, posing the urgent question how sustainable current water abstractions are worldwide and where and when these abstractions approach conceivable limits with all the associated problems. Here, we estimated past and future trends (1960-2050) in groundwater levels resulting from changes in abstractions and climate and predicted when limits of groundwater consumption are reached. We explored these limits by predicting where and when groundwater levels drop that low that groundwater becomes unattainable for abstractions and how river flows are affected. Water availabilities, abstractions, and lateral groundwater flows are simulated (5 arcmin. resolution) using a coupled version of the global hydrological model PCR-GLOBWB and a groundwater model based on MODFLOW. The groundwater model includes a parameterization of the worlds confined and unconfined aquifer systems, needed for a realistic simulation of groundwater head dynamics. Results show that, next to the existing regions experiencing groundwater depletion (like India, Pakistan, Central Valley) new regions will develop, e.g. Southern Europe, the Middle East, and Africa. Using a limit that reflects present-day feasibility of groundwater abstraction, we estimate that in 2050 groundwater becomes unattainable for 20% of the global population, mainly in the developing countries and pumping cost will increase significantly. Largest impacts are found

  19. Summary of Dissolved Concentration Limits

    International Nuclear Information System (INIS)

    Yueting Chen

    2001-01-01

    According to the Technical Work Plan titled Technical Work Plan for Waste Form Degradation Process Model Report for SR (CRWMS M and O 2000a), the purpose of this study is to perform abstractions on solubility limits of radioactive elements based on the process-level information and thermodynamic databases provided by Natural Environment Program Operations (NEPO) and Waste Package Operations (WPO). The scope of this analysis is to produce solubility limits as functions, distributions, or constants for all transported radioactive elements identified by the Performance Assessment Operations (PAO) radioisotope screening. Results from an expert elicitation for solubility limits of most radioactive elements were used in the previous Total System Performance Assessments (TSPAs). However, the elicitation conducted in 1993 does not meet the criteria set forth by the U.S. Nuclear Regulatory Commission (NRC) due to lack of documentation and traceability (Kotra et al. 1996, Section 3). Therefore, at the Waste Form Abstraction Workshop held on February 2-4, 1999, at Albuquerque, New Mexico, the Yucca Mountain Site Characterization Project (YMP) decided to develop geochemical models to study solubility for the proposed Monitored Geologic Repository. WPO/NEPO is to develop process-level solubility models, including review and compilation of relevant thermodynamic data. PAO's responsibility is to perform abstractions based on the process models and chemical conditions and to produce solubility distributions or response surfaces applicable to the proposed repository. The results of this analysis and conceptual model will feed the performance assessment for Total System Performance Assessment--Site Recommendation (TSPA-SR) and Total System Performance Assessment--License Application (TSPA-LA), and to the Waste Form Degradation Process Model Report section on concentration limits

  20. Summary of Dissolved Concentration Limits

    Energy Technology Data Exchange (ETDEWEB)

    Yueting Chen

    2001-06-11

    According to the Technical Work Plan titled Technical Work Plan for Waste Form Degradation Process Model Report for SR (CRWMS M&O 2000a), the purpose of this study is to perform abstractions on solubility limits of radioactive elements based on the process-level information and thermodynamic databases provided by Natural Environment Program Operations (NEPO) and Waste Package Operations (WPO). The scope of this analysis is to produce solubility limits as functions, distributions, or constants for all transported radioactive elements identified by the Performance Assessment Operations (PAO) radioisotope screening. Results from an expert elicitation for solubility limits of most radioactive elements were used in the previous Total System Performance Assessments (TSPAs). However, the elicitation conducted in 1993 does not meet the criteria set forth by the U.S. Nuclear Regulatory Commission (NRC) due to lack of documentation and traceability (Kotra et al. 1996, Section 3). Therefore, at the Waste Form Abstraction Workshop held on February 2-4, 1999, at Albuquerque, New Mexico, the Yucca Mountain Site Characterization Project (YMP) decided to develop geochemical models to study solubility for the proposed Monitored Geologic Repository. WPO/NEPO is to develop process-level solubility models, including review and compilation of relevant thermodynamic data. PAO's responsibility is to perform abstractions based on the process models and chemical conditions and to produce solubility distributions or response surfaces applicable to the proposed repository. The results of this analysis and conceptual model will feed the performance assessment for Total System Performance Assessment--Site Recommendation (TSPA-SR) and Total System Performance Assessment--License Application (TSPA-LA), and to the Waste Form Degradation Process Model Report section on concentration limits.

  1. Problems of anthropogenic tritium limitation

    Directory of Open Access Journals (Sweden)

    Kochetkov О.A.

    2013-12-01

    Full Text Available This article contains the current situation in respect to the environmental concentrations of anthropogenic and natural tritium. There are presented and analyzed domestic standards for НТО of all Radiation Safety Standards (NRB, as well as the regulations analyzed for tritium in drinking water taken in other countries today. This article deals with the experience of limitation of tritium and focuses on the main problem of rationing of tritium — rationing of organically bound tritium.

  2. IONIC LIQUIDS: PREPARATIONS AND LIMITATIONS

    Directory of Open Access Journals (Sweden)

    Dzulkefly Kuang Abdullah

    2010-11-01

    Full Text Available Ionic liquids are considered as an ideal alternative to volatile organic solvents and chemical industries in the future,because they are non-volatile. Ionic liquids are also considered as new novel chemical agents and widely regarded as agreener alternative to many commonly used solvents. Ionic liquids have been studied for a wide range of syntheticapplications and have attracted considerable interest for use as electrolytes in the areas of organic synthesis, catalysis,solar cell, fuel cells, electrodeposition and supercapacitors. However, some ionic liquids suffer from more or less somedrawbacks such as toxicity, preparation and high cost in the process for use. Most recently, three types of ionic liquidsare attracted much attentions specifically traditional ionic liquid, protic ionic liquid and deep eutectic solvent, wheretheir preparation, mechanism and limitation were differentiated. However, those liquids are having their ownadvantages and limitations based on applications. Traditional ionic liquid and protic ionic liquid are highly cost andtoxic for applied engineering research, but they consist of micro-biphasic systems composed of ionic compounds whichhave more varieties in the applications. The deep eutectic solvent is very economic for large-scale possessing but thereare only limited ionic mixtures to certain application such as electrochemistry.

  3. Photon and graviton mass limits

    Science.gov (United States)

    Goldhaber, Alfred Scharff; Nieto, Michael Martin

    2010-01-01

    Efforts to place limits on deviations from canonical formulations of electromagnetism and gravity have probed length scales increasing dramatically over time. Historically, these studies have passed through three stages: (1) testing the power in the inverse-square laws of Newton and Coulomb, (2) seeking a nonzero value for the rest mass of photon or graviton, and (3) considering more degrees of freedom, allowing mass while preserving explicit gauge or general-coordinate invariance. Since the previous review the lower limit on the photon Compton wavelength has improved by four orders of magnitude, to about one astronomical unit, and rapid current progress in astronomy makes further advance likely. For gravity there have been vigorous debates about even the concept of graviton rest mass. Meanwhile there are striking observations of astronomical motions that do not fit Einstein gravity with visible sources. “Cold dark matter” (slow, invisible classical particles) fits well at large scales. “Modified Newtonian dynamics” provides the best phenomenology at galactic scales. Satisfying this phenomenology is a requirement if dark matter, perhaps as invisible classical fields, could be correct here too. “Dark energy” might be explained by a graviton-mass-like effect, with associated Compton wavelength comparable to the radius of the visible universe. Significant mass limits are summarized in a table.

  4. Photon and graviton mass limits

    International Nuclear Information System (INIS)

    Goldhaber, Alfred Scharff; Nieto, Michael Martin

    2010-01-01

    Efforts to place limits on deviations from canonical formulations of electromagnetism and gravity have probed length scales increasing dramatically over time. Historically, these studies have passed through three stages: (1) testing the power in the inverse-square laws of Newton and Coulomb, (2) seeking a nonzero value for the rest mass of photon or graviton, and (3) considering more degrees of freedom, allowing mass while preserving explicit gauge or general-coordinate invariance. Since the previous review the lower limit on the photon Compton wavelength has improved by four orders of magnitude, to about one astronomical unit, and rapid current progress in astronomy makes further advance likely. For gravity there have been vigorous debates about even the concept of graviton rest mass. Meanwhile there are striking observations of astronomical motions that do not fit Einstein gravity with visible sources. ''Cold dark matter'' (slow, invisible classical particles) fits well at large scales. ''Modified Newtonian dynamics'' provides the best phenomenology at galactic scales. Satisfying this phenomenology is a requirement if dark matter, perhaps as invisible classical fields, could be correct here too. ''Dark energy''might be explained by a graviton-mass-like effect, with associated Compton wavelength comparable to the radius of the visible universe. Significant mass limits are summarized in a table.

  5. Workshop on confidence limits. Proceedings

    International Nuclear Information System (INIS)

    James, F.; Lyons, L.; Perrin, Y.

    2000-01-01

    The First Workshop on Confidence Limits was held at CERN on 17-18 January 2000. It was devoted to the problem of setting confidence limits in difficult cases: number of observed events is small or zero, background is larger than signal, background not well known, and measurements near a physical boundary. Among the many examples in high-energy physics are searches for the Higgs, searches for neutrino oscillations, B s mixing, SUSY, compositeness, neutrino masses, and dark matter. Several different methods are on the market: the CL s methods used by the LEP Higgs searches; Bayesian methods; Feldman-Cousins and modifications thereof; empirical and combined methods. The Workshop generated considerable interest, and attendance was finally limited by the seating capacity of the CERN Council Chamber where all the sessions took place. These proceedings contain all the papers presented, as well as the full text of the discussions after each paper and of course the last session which was a discussion session. The list of participants and the 'required reading', which was expected to be part of the prior knowledge of all participants, are also included. (orig.)

  6. Impact-limiting materials characterization

    International Nuclear Information System (INIS)

    Glass, R.E.; Duffey, T.A.; McConnell, P.

    1993-01-01

    Three types of impact-limiting materials have been characterized which have applications in packages for the transport of radioactive materials. These materials are aluminum honeycombs, polyurethane foams, and aluminum foams. The results of the materials characterization have indicated strengths and weaknesses for each type of material. The polyurethane foams provide good impact limiting ability and excellent thermal insulation. However, they burn when subjected to the regulatory thermal event in the presence of air. The aluminum honeycombs provide excellent impact resistance in specific impact orientations. However, they provide relatively poor resistance to thermal assault. Finally, the aluminum foams exhibit relatively poor impact energy absorption capacities, significant variability in energy absorption, and limited thermal insulation. The development of the figures of merit examined the response of the materials to the impact event with the intent of maximizing the energy absorption of the materials with respect to either the volume or mass of the materials. Three figures of merit will be presented for the structural response. The figure of merit for the thermal event is based on minimizing the heat flux to the containment boundary. The paper presents a discussion of the test methods, a summary of the data and the figures of merit for each material. (J.P.N.)

  7. Does general relativity theory have the classical Newtonian limit limit

    International Nuclear Information System (INIS)

    Denisov, V.I.; Logunov, A.A.

    1980-01-01

    Newton gravitation theory and Newtonian approximation of the general relativity theory are considered. By the method of successive approximations Einstein equations have been solved and Newtonian approximation of the Einstein theory is obtained. It is shown that in general relativity theory there is no Newtonian limit for the integrals of the motion of matter and gravitational field, as the integrals of the motion of the Newton gravitation theory and Newtonian approximation of Einstein theory do not coincide. The Einstein general relativity theory is constructed at the cost of refusal of the conservation laws for energy-momentum of matter and gravitational field taken together

  8. Limits of dose escalation in lung cancer: a dose-volume histogram analysis comparing coplanar and non-coplanar techniques

    Energy Technology Data Exchange (ETDEWEB)

    Derycke, S.; Van Duyse, B.; Schelfhout, J.; De Neve, W.

    1995-12-01

    To evaluate the feasibility of dose escalation in radiotherapy of inoperable lung cancer, a dose-volume histogram analysis was performed comparing standard coplanar (2D) with non-coplanar (3D) beam arrangements on a non-selected group of 20 patients planned by Sherouse`s GRATISTM 3D-planning system. Serial CT-scanning was performed and 2 Target Volumes (Tvs) were defined. Gross Tumor Volume (GTV) defined a high-dose Target Volume (TV-1). GTV plus location of node stations with > 10% probability of invasion (Minet et al.) defined an intermediate-dose Target Volume (TV-2). However, nodal regions which are incompatible with cure were excluded from TV-2. These are ATS-regions 1, 8, 9 and 14 all left and right as well as heterolateral regions. For 3D-planning, Beam`s Eye View selected (by an experienced planner) beam arrangements were optimised using Superdot, a method of target dose-gradient annihilation developed by Sherouse. A second 3D-planning was performed using 4 beam incidences with maximal angular separation. The linac`s isocenter for the optimal arrangement was located at the geometrical center of gravity of a tetraheder, the tetraheder`s comers being the consecutive positions of the virtual source. This ideal beam arrangement was approximated as close as possible, taking into account technical limitations (patient-couch-gantry collisions). Criteria for tolerance were met if no points inside the spinal cord exceeded 50 Gy and if at least 50% of the lung volume received less than 20Gy. If dose regions below 50 Gy were judged acceptable at TV-2, 2D- as well as 3D-plans allow safe escalation to 80 Gy at TV-1. When TV-2 needed to be encompassed by isodose surfaces exceeding 50Gy, 3D-plans were necessary to limit dose at the spinal cord below tolerance. For large TVs dose is limited by lung tolerance for 3D-plans. An analysis (including NTCP-TCP as cost functions) of rival 3D-plans is being performed.

  9. Limits to the growth debate

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, L.

    The first two major studies sponsored by the club of Rome were the report of the Meadows team at MIT, The Limits to Growth, published in 1972, and the Mesarovic and Pestel report, Mankind at the Turning Point, published in 1974. When the Club of Rome met in Philadelphia in April of 1976, its pronouncements reflected a frame of mind quite different from that of 1972. Recently, Herman Kahn and his colleagues at the Hudson Institute have published The Next 200 Years, a book evidently inspired as much by antagonism to the limits-to-growth school of thought as by affirmative faith in its own vision of technological optimism. The author discusses the content of the studies and summarizes his own position in four areas. (1) While no trend of growth of anything can continue indefinitely in the real world, there are not global physical limits to economic growth within a time frame susceptible to plausible foresight or relevant to policy making. (2) In some world regions, notably South Asia and tropical Africa, population growth rates do indeed threaten to create a kind of Malthusian trap, and the rapid reduction of fertility is critically important to their development prospects and urgent in time. (3) For other parts of the world, both rates and directions of growth will be more influenced by changes in preferences for consumption and in attitudes toward production than by physical constraints, although higher energy costs and environmental pressures will also be important influences in generating such changes in growth patterns. (4) Probable changes in directions of growth will generate new and important issues in international economic and political relations, with both dangers and opportunities for the evolving world order. (MCW)

  10. Combination trading with limit orders

    Directory of Open Access Journals (Sweden)

    Henry Schellhorn

    1997-01-01

    Full Text Available We model the exchange of commodities that are contingent upon each other, when traders place mostly limit orders. Examples include: 1 a market of financial futures where future spreads are also traded, 2 a market of mutual funds and stocks, 3 a market of options and stocks, under the viewpoint that they are both combinations of Arrow-Debreu securities. We prove that consistent prices are optimal. We develop a fixed-point algorithm to compute an optimal price and allocation. The algorithm combines ideas from contraction mapping theory and from homotopy theory. It is much faster than a traditional linear programming approach.

  11. Mammalian cloning: advances and limitations.

    Science.gov (United States)

    Solter, D

    2000-12-01

    For many years, researchers cloning mammals experienced little success, but recent advances have led to the successful cloning of several mammalian species. However, cloning by the transfer of nuclei from adult cells is still a hit-and-miss procedure, and it is not clear what technical and biological factors underlie this. Our understanding of the molecular basis of reprogramming remains extremely limited and affects experimental approaches towards increasing the success rate of cloning. Given the future practical benefits that cloning can offer, the time has come to address what should be done to resolve this problem.

  12. Large networks and graph limits

    CERN Document Server

    Lovász, László

    2012-01-01

    Recently, it became apparent that a large number of the most interesting structures and phenomena of the world can be described by networks. Developing a mathematical theory of very large networks is an important challenge. This book describes one recent approach to this theory, the limit theory of graphs, which has emerged over the last decade. The theory has rich connections with other approaches to the study of large networks, such as "property testing" in computer science and regularity partition in graph theory. It has several applications in extremal graph theory, including the exact for

  13. Food irradiation, profits and limitations

    International Nuclear Information System (INIS)

    Luna C, P.C.

    1992-05-01

    The utility of the irradiation to overcome diverse problems of lost nutritious, it has been demonstrated in multiple investigation works, that its have confirmed the value and the inoculation of the irradiated foods. The quantity of energy applied to each food, is in function of the wanted effect. In this document a guide with respect to the practical application and the utility of the irradiation process in different foods, as well as the suggested dose average is shown. Among the limitations of the use of this technology, its are the costs and not being able to apply it to some fresh foods. (Author)

  14. Nanofabrication principles, capabilities and limits

    CERN Document Server

    Cui, Zheng

    2017-01-01

    This second edition of Nanofabrication is one of the most comprehensive introductions on nanofabrication technologies and processes. A practical guide and reference, this book introduces readers to all of the developed technologies that are capable of making structures below 100nm. The principle of each technology is introduced and illustrated with minimum mathematics involved. Also analyzed are the capabilities of each technology in making sub-100nm structures, and the limits of preventing a technology from going further down the dimensional scale. This book provides readers with a toolkit that will help with any of their nanofabrication challenges.

  15. FAIR VALUE: UTILITY AND LIMITS

    Directory of Open Access Journals (Sweden)

    Valentin Gabriel Cristea

    2015-05-01

    Full Text Available This paper presents the utility and the limits of the fair value. We believe that any new product must be tried and tested before being imposed on the market and must be accepted by all potential users and those who will be affected, directly or indirectly and its advantages, disadvantages, risks, its cost must be predetermined and analyzed in a comprehensive and objective.We ask: Do financial statements at fair value meet users' expectations? The requirement to use fair value pricing model that was carrying was not accompanied by a parallel examination of its impact on the presentation of accounts.

  16. CSS3 pushing the limits

    CERN Document Server

    Greig, Stephen

    2013-01-01

    Push CSS3 and your design skills to the limit-and beyond! Representing an evolutionary leap forward for CSS, CSS3 is chock-full of new capabilities that dramatically expand the boundaries of what a styling language can do. But many of those new features remain undocumented, making it difficult to learn what they are and how to use them to create the sophisticated sites and web apps clients demand and users have grown to expect. Until now. This book introduces you to all of CSS3's new and advanced features, and, with the help of dozens of real-world examples and live

  17. LIMITED RESTAURANT SERVICE: EASTER WEEKEND

    CERN Document Server

    2003-01-01

    As Friday, April 18 and Monday, April 21, 2003 are CERN holidays, restaurants no. 1 (COOP : Bldg. 501- Meyrin) and no. 3 (AVENANCE : Bldg. 866 - Prévessin) will be closed and will remain so on Saturday and Sunday, April 19 - 20. They will reopen on Tuesday, April 22 at 7h00. During these four days, a limited service will be provided by restaurant no. 2 (DSR : Bldg. 504 - Meyrin) from 8h00 to 21h00 with hot meals served from 11h30 to 14h00 and from 18h00 to 19h30.

  18. Moral Limits of the Market

    DEFF Research Database (Denmark)

    Ooi, Can-Seng

    2017-01-01

    Scholars and the practice community unanimously advocate sustainable balanced and sensitive tourism development. Engaging with locals and setting up public-private partnerships are frequently championed. This working paper introduces a set of lenses in the moral philosophy tradition and argues...... that the current pragmatic solutions to sustainable tourism development could not resolve issues of authenticity, equity, rights and fairness. There are three in-built moral limits in the tourism market, and namely: the market assumes it can price everything including culture and nature; the market distributes...

  19. Interstellar scattering and resolution limitations

    Science.gov (United States)

    Dennison, Brian

    Density irregularities in both the interplanetary medium and the ionized component of the interstellar medium scatter radio waves, resulting in limitations on the achievable resolution. Interplanetary scattering (IPS) is weak for most observational situations, and in principle the resulting phase corruption can be corrected for when observing with sufficiently many array elements. Interstellar scattering (ISS), on the other hand, is usually strong at frequencies below about 8 GHz, in which case intrinsic structure information over a range of angular scales is irretrievably lost. With the earth-space baselines now planned, it will be possible to search directly for interstellar refraction, which is suspected of modulating the fluxes of background sources.

  20. Relations entre les types de dépôts évaporitiques et la présence de couches riches en matière organique (roches-mères potentielles Relationship Between Different Types of Evaporitic Deposits and the Occurrence of Organic-Rich Layers (Potential Source Rocks

    Directory of Open Access Journals (Sweden)

    Busson G.

    2006-11-01

    Full Text Available La fertilité exceptionnelle des eaux salées est confirmée par des études récentes sur l'Actuel (marais salants de Méditerranée occidentale. Le benthos est représenté par des mollusques, foraminifères, ostracodes et surtout des cyanophycées et des populations bactériennes ; le plancton par le microphytoplancton (Dunaliella, diatomées, etc, par le zooplancton (flagellés, Arternia salina et par de très nombreuses bactéries hétérotrophes. Si les espèces sont d'autant plus rares que la salinité est élevée, la prolifération des formes adaptées peut atteindre des valeurs supérieures à celles réalisées dans la plupart des autres milieux. On rappelle ensuite l'efficacité des systèmes d'eaux stratifiées pour la conservation de la matière organique originellement élaborée dans l'eau photique et oxygénée. Ces systèmes peuvent s'accompagner de proliférations bactériennes photosynthétiques exposées à des mortalités en masse pouvant être responsables de véritables lamines organiques. Dans les évaporites de plates-formes où la ségrégation des salinités et des dépôts a été synchrone et latérale, la tranche d'eau a dû être faible et, de ce fait, peu favorable à l'établissement de systèmes d'eaux stratifiées et surtout à leur pérennité géologique. Ces accumulations s'avèrent donc en général pauvres en matière organique, de même qu'elles ne s'accompagnent pas d'appareils récifaux abondants. Dans les évaporites de centre de cuvette, les dépôts sont imputables à une succession de phases de salinité croissante dans le temps : calcaires sur les zones hautes, contemporains de minces couches à matière organique dans les dépressions ; sulfate de calcium sur les aires d'épaisseur moyenne pouvant être encore contemporain de couche à matière organique dans les aires déprimées ; enfin, remplissage par la halite des zones centrales profondes et déprimées. A ces phases successives, se

  1. Limit Cycles and Conformal Invariance

    CERN Document Server

    Fortin, Jean-Francois; Stergiou, Andreas

    2013-01-01

    There is a widely held belief that conformal field theories (CFTs) require zero beta functions. Nevertheless, the work of Jack and Osborn implies that the beta functions are not actually the quantites that decide conformality, but until recently no such behavior had been exhibited. Our recent work has led to the discovery of CFTs with nonzero beta functions, more precisely CFTs that live on recurrent trajectories, e.g., limit cycles, of the beta-function vector field. To demonstrate this we study the S function of Jack and Osborn. We use Weyl consistency conditions to show that it vanishes at fixed points and agrees with the generator Q of limit cycles on them. Moreover, we compute S to third order in perturbation theory, and explicitly verify that it agrees with our previous determinations of Q. A byproduct of our analysis is that, in perturbation theory, unitarity and scale invariance imply conformal invariance in four-dimensional quantum field theories. Finally, we study some properties of these new, "cycl...

  2. Hamiltonian mechanics limits microscopic engines

    Science.gov (United States)

    Anglin, James; Gilz, Lukas; Thesing, Eike

    2015-05-01

    We propose a definition of fully microscopic engines (micro-engines) in terms of pure mechanics, without reference to thermodynamics, equilibrium, or cycles imposed by external control, and without invoking ergodic theory. This definition is pragmatically based on the observation that what makes engines useful is energy transport across a large ratio of dynamical time scales. We then prove that classical and quantum mechanics set non-trivial limits-of different kinds-on how much of the energy that a micro-engine extracts from its fuel can be converted into work. Our results are not merely formal; they imply manageable design constraints on micro-engines. They also suggest the novel possibility that thermodynamics does not emerge from mechanics in macroscopic regimes, but rather represents the macroscopic limit of a generalized theory, valid on all scales, which governs the important phenomenon of energy transport across large time scale ratios. We propose experimental realizations of the dynamical mechanisms we identify, with trapped ions and in Bose-Einstein condensates (``motorized bright solitons'').

  3. The Limited Test Ban Treaty

    International Nuclear Information System (INIS)

    Loeb, B.S.

    1991-01-01

    This paper discusses the Limited Test Ban Treaty which came at the end of nearly five years of frustrated efforts to obtain a comprehensive test ban. Negotiations toward that end had begun in October 1958. At the same time a voluntary, informal moratorium on tests was initiated. The negotiations soon stalled over the Soviet Union's resistance to internationally supervised inspections on its soil. In April 1959 a phased ban that was to be limited at first to atmospheric tests conducted below an altitude of 50 kilometers. Such tests were thought to be easily verifiable. The Soviets rejected this idea and continued to insist that a complete test ban need not require numerous inspections. The two sides nevertheless appeared to be nearing agreement on a treaty to ban all but relatively small underground tests when, in May 1960, an U.S. U-2 reconnaissance plane was shot down over Soviet territory. After a thorough review of the U.S. position, the Kennedy administration proposed in April 1961 a draft treaty that made several concessions toward the Soviet position. Nevertheless, the Soviets, still disagreeing with the provisions for verification and with the makeup of the control organization, rejected it

  4. Peptidomics for Studying Limited Proteolysis.

    Science.gov (United States)

    Tsuchiya, Takashi; Osaki, Tsukasa; Minamino, Naoto; Sasaki, Kazuki

    2015-11-06

    Limited proteolysis is a pivotal mechanism regulating protein functions. Identifying physiologically or pathophysiologically relevant cleavage sites helps to develop molecular tools that can be used for diagnostics or therapeutics. During proteolysis of secretory and membrane proteins, part of the cleaved protein is liberated and destined to undergo degradation but should retain original cleavage sites created by proteolytic enzymes. We profiled endogenous peptides accumulated for 4 h in media conditioned by primary cultured rat cardiac fibroblasts. A total of 3916 redundant peptide sequences from 94 secretory proteins and membrane proteins served to identify limited cleavage sites, both annotated and unannotated, for signal peptide or propeptide removal, peptide hormone processing, ectodomain shedding, and regulated intramembrane proteolysis. Incorrectly predicted signal cleavage sites are found in typical proteins such as extracellular matrix proteins and the peptide hormone precursor adrenomedullin ADM. The revealed signal peptide cleavage site for ADM was experimentally verified by identifying the major molecular form of flanking proadrenomedullin N-terminal peptide. We suggest that profiling of endogenous peptides, like transcriptome sequence reads, makes sense in regular cells such as fibroblasts and that peptidomics provides insight into proteolysis-regulated protein functions.

  5. 36 CFR 4.21 - Speed limits.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Speed limits. 4.21 Section 4... TRAFFIC SAFETY § 4.21 Speed limits. (a) Park area speed limits are as follows: (1) 15 miles per hour... superintendent may designate a different speed limit upon any park road when a speed limit set forth in paragraph...

  6. Be-limiter experiment on ISX

    International Nuclear Information System (INIS)

    Mioduszewski, P.K.

    1984-01-01

    The relevance of this experiment to the JET experiment is described. Data on the following issues are given: (1) thermo-mechanical properties of the Be-limiter; (2) particle flow to limiter; (3) heat flow to the limiter; (4) limiter-plasma-wall interaction; (5) plasma properties/operation; (6) active control of plasma-limiter operation; and (7) fault conditions

  7. Controlling percolation with limited resources

    Science.gov (United States)

    Schröder, Malte; Araújo, Nuno A. M.; Sornette, Didier; Nagler, Jan

    2017-12-01

    Connectivity, or the lack thereof, is crucial for the function of many man-made systems, from financial and economic networks over epidemic spreading in social networks to technical infrastructure. Often, connections are deliberately established or removed to induce, maintain, or destroy global connectivity. Thus, there has been a great interest in understanding how to control percolation, the transition to large-scale connectivity. Previous work, however, studied control strategies assuming unlimited resources. Here, we depart from this unrealistic assumption and consider the effect of limited resources on the effectiveness of control. We show that, even for scarce resources, percolation can be controlled with an efficient intervention strategy. We derive such an efficient strategy and study its implications, revealing a discontinuous transition as an unintended side effect of optimal control.

  8. Mathematical methods for hydrodynamic limits

    CERN Document Server

    Masi, Anna

    1991-01-01

    Entropy inequalities, correlation functions, couplings between stochastic processes are powerful techniques which have been extensively used to give arigorous foundation to the theory of complex, many component systems and to its many applications in a variety of fields as physics, biology, population dynamics, economics, ... The purpose of the book is to make theseand other mathematical methods accessible to readers with a limited background in probability and physics by examining in detail a few models where the techniques emerge clearly, while extra difficulties arekept to a minimum. Lanford's method and its extension to the hierarchy of equations for the truncated correlation functions, the v-functions, are presented and applied to prove the validity of macroscopic equations forstochastic particle systems which are perturbations of the independent and of the symmetric simple exclusion processes. Entropy inequalities are discussed in the frame of the Guo-Papanicolaou-Varadhan technique and of theKipnis-Oll...

  9. Limited vitrectomy in phacomorphic glaucoma

    Directory of Open Access Journals (Sweden)

    Ritika Sachdev

    2017-01-01

    Full Text Available One of the challenging situations for a cataract surgeon is phacoemulsification in the shallow anterior chamber like cases of phacomorphic glaucoma. Some of the main concerns of operating in a narrow space include endothelial decompensation, descemet's detachment, and posterior capsular rents. High vitreous pressure predisposes to posterior capsular rents owing to a reduced concavity of the posterior capsule and increasing the proximity of phaco-tip to the posterior capsule. We describe a technique of limited vitrectomy in such cases. A small gauge 23-G/25-G trocar cannula is passed transconjunctivally, and the liquefied vitreous is allowed to egress. Vitrectomy is done extraocularly till the vitreous pressure lowers down. This technique helps to debulk the vitreous and decompress the globe in a controlled manner. The resultant posterior displacement of iris-lens diaphragm causes a deepening of the anterior chamber to facilitate phacoemulsification.

  10. Pericytes limit tumor cell metastasis

    DEFF Research Database (Denmark)

    Xian, Xiaojie; Håkansson, Joakim; Ståhlberg, Anders

    2006-01-01

    Previously we observed that neural cell adhesion molecule (NCAM) deficiency in beta tumor cells facilitates metastasis into distant organs and local lymph nodes. Here, we show that NCAM-deficient beta cell tumors grew leaky blood vessels with perturbed pericyte-endothelial cell-cell interactions...... and deficient perivascular deposition of ECM components. Conversely, tumor cell expression of NCAM in a fibrosarcoma model (T241) improved pericyte recruitment and increased perivascular deposition of ECM molecules. Together, these findings suggest that NCAM may limit tumor cell metastasis by stabilizing...... the microvessel wall. To directly address whether pericyte dysfunction increases the metastatic potential of solid tumors, we studied beta cell tumorigenesis in primary pericyte-deficient Pdgfb(ret/ret) mice. This resulted in beta tumor cell metastases in distant organs and local lymph nodes, demonstrating a role...

  11. LIMITED RESTAURANT SERVICE : EASTER WEEKEND

    CERN Document Server

    2003-01-01

    As Friday, April 18 and Monday, April 21, 2003 are CERN holidays, restaurants no. 1 (COOP : Bldg. 501- Meyrin) and no. 3 (AVENANCE : Bldg. 866 - Prévessin) will be closed and will remain so on Saturday and Sunday, April 19 - 20. They will reopen on Tuesday, April 22 at 7h00. During these four days, a limited service will be provided by restaurant no. 2 (DSR : Bldg. 504 - Meyrin) from 8h00 to 21h00 with hot meals served from 11h30 to 14h00 and from 18h00 to 19h30. On Thursday, April 17, all three restaurants will operate according to the usual times except for restaurant no. 1 which will close at 21h00 instead of 1 o'clock in the morning.

  12. LIMITED RESTAURANT SERVICE 'JEUNE GENEVOIS'

    CERN Multimedia

    2000-01-01

    On Thursday, September 7, 2000, all restaurants, cafétérias and kiosques will be closed except for restaurant no. 1 and its cafétéria (COOP - building 501 - Meyrin) which will provide a limited service from 8h00 to 21h00. Hot meals will be served from 11h30 to 14h00 and from 18h00 to 19h30. For technical reasons, restaurant no. 2 and its cafétéria (DSR - building 504 - Meyrin) will remain closed on Friday, September 8. They will resume their normal activities on Monday, September 11, 2000. The other restaurants, cafétérias and kiosques will offer their normal service as from Friday, September 8.

  13. LIMITED RESTAURANT SERVICE : EASTER WEEKEND

    CERN Multimedia

    Restaurant Supervisory Committee

    2002-01-01

    As Friday 29 March and Monday 1st April 2002 are CERN holidays, restaurants no. 1 (COOP, bldg. 501- Meyrin) and no. 3 (Avenance, bldg. 866 - Prévessin) will be closed and will remain so on Saturday and Sunday 30-31 March. They will reopen on Tuesday 2 April at 7h00. During these four days, a limited service will be provided by restaurant no. 2 (DSR, bldg. 504 - Meyrin) from 8h00 to 21h00 with hot meals served from 11h30 to 14h00 and from 18h00 to 19h30. On Thursday 28 March, all three restaurants will operate according to the usual times except for restaurant no. 1 which will close at 21h00 instead of 1 o'clock in the morning. Restaurant Supervisory Committee Tel. 77551

  14. LIMITED RESTAURANT SERVICE : EASTER WEEKEND

    CERN Multimedia

    Restaurant Supervisory Committee

    2002-01-01

    As Friday, March 29 and Monday, April 1st, 2002 are CERN holidays, restaurants no. 1 (COOP : Bldg. 501- Meyrin) and no. 3 (Avenance : Bldg. 866 - Prévessin) will be closed and will remain so on Saturday and Sunday, March 30 - 31. They will reopen on Tuesday, April 2 at 7h00. During these four days, a limited service will be provided by restaurant no. 2 (DSR : Bldg. 504 - Meyrin) from 8h00 to 21h00 with hot meals served from 11h30 to 14h00 and from 18h00 to 19h30. On Thursday, March 28, all three restaurants will operate according to the usual times except for restaurant no. 1 which will close at 21h00 instead of 1 o'clock in the morning.   Restaurant Supervisory Committee, tel. 77551

  15. LIMITED RESTAURANT SERVICE: EASTER WEEKEND

    CERN Multimedia

    Restaurant Supervisory Committee

    2001-01-01

    As Friday 13 and Monday 16 April 2001 are CERN holidays, restaurants no. 1 (COOP, bldg. 501- Meyrin) and no. 3 (Générale de Restauration, bldg. 866 - Prévessin) will be closed and will remain so on Saturday 14 and Sunday 15 April. They will reopen on Tuesday 17 April at 7h00. During these four days, a limited service will be provided by restaurant no. 2 (DSR, bldg. 504 - Meyrin) from 8h00 to 21h00 with hot meals served from 11h30 to 14h00 and from 18h00 to 19h30. On Thursday 12 April, all three restaurants will operate according to the usual times except for restaurant no 1, which will close at 21h00 instead of 1 o'clock in the morning.

  16. Limits to power system growth

    International Nuclear Information System (INIS)

    Slater, S.M.; Klein, A.C.; Webb, B.J.; Pauley, K.A.

    1993-01-01

    In the design of space nuclear power systems a variety of conversion techniques may be used, each with its own advantages and disadvantages. A study was performed which analyzed over 120 proposed system designs. The designs were compared to identify the optimum conversion system as a function of power level and find limits to specific mass (kg/kWe) for each power cycle. Furthermore, the component masses were studied to determine which component of the overall design contributes the most to total system mass over a variety of power levels. The results can provide a focus for future research efforts by selecting the best conversion technology for the desired power range, and optimizing the system component which contributes most to the total mass

  17. THE LIMITS OF ESP TESTS

    Directory of Open Access Journals (Sweden)

    Norica-Felicia BUCUR

    2015-07-01

    Full Text Available Global market forces have determined not only higher education institutions all over the world to include ESP courses in their curriculum to enhance their students’ future employability, but also public and private organisations to offer their employees the opportunity to attend ESP courses in order to meet the continuously growing ESP needs. From this perspective, ESP compentence could become a subcomponent of one of the key competences for lifelong learning, communication in foreign languages. Therefore assessing ESP competence seems to acquire paramount importance since stakeholders need accurate information about the ESP learners’ abilities to cope with specific language tasks. This article offers a concise overview of the principles and practices of ESP assessment, a detailed description of the features of ESP tests, while focusing particularly on the limits of ESP tests in order to identify possible solutions to overcome them.

  18. Sodium nitrate combustion limit tests

    International Nuclear Information System (INIS)

    Beitel, G.A.

    1976-04-01

    Sodium nitrate is a powerful solid oxidant. Energetically, it is capable of exothermically oxidizing almost any organic material. Rate-controlling variables such as temperature, concentration of oxidant, concentration of fuel, thermal conductivity, moisture content, size, and pressure severely limit the possibility of a self-supported exothermic reaction (combustion). The tests reported in this document were conducted on one-gram samples at atmospheric pressure. Below 380 0 C, NaNO 3 was stable and did not support combustion. At moisture concentrations above 22 wt percent, exothermic reactions did not propagate in even the most energetic and reactive compositions. Fresh resin and paraffin were too volatile to enable a NaNO 2 -supported combustion process to propagate. Concentrations of NaNO 3 above 95 wt percent or below 35 wt percent did not react with enough energy release to support combustion. The influence of sample size and confining pressure, both important factors, was not investigated in this study

  19. Certifying Equality With Limited Interaction

    DEFF Research Database (Denmark)

    Brody, Joshua Eric; Chakrabarti, Amit; McGregor, Andrew

    2012-01-01

    by focusing on two subtle aspects. The first is to consider the {\\em expected} communication cost (at a worst-case input) for a protocol that uses limited interaction---i.e., a bounded number of rounds of communication---and whose error probability is zero or close to it. The second is to consider the {\\em...... information cost} of such protocols. We obtain asymptotically optimal rounds-versus-communication and rounds-versus-information tradeoffs for the problem. For the case of zero-error communication cost, we obtain essentially matching bounds, up to a tiny additive constant. As an application of our information...... cost bounds, we obtain new bounded-round randomized lower bounds for the \\textsc{or-equality} problem that have a direct-sum flavor. Such lower bounds were previously known only for deterministic protocols or one-round randomized protocols. The \\textsc{or-equality} problem is in turn closely related...

  20. Setting limits on marine pollution

    International Nuclear Information System (INIS)

    1973-01-01

    The need for internationally acceptable standards and regulations for preventing pollution of the sea by radioactive materials was recognized by the United Nations Conference on the Law of the Sea, when it adopted the Convention on the High Seas in April 1958. Article 25 of the Convention provides that 'every State shall take measures to prevent pollution of the seas from the dumping of radioactive wastes, taking into account any standards and regulations which may be formulated by the competent international organizations'. The Conference also adopted a resolution recommending that the IAEA pursue studies and take action to assist States in controlling the discharge of radioactive materials into the sea. In response to this resolution, an expert panel was set up in 1958, under the Chairmanship of Mr. Brynielsson of Sweden, and met again in 1959, to recommend the necessary measures for ensuring that the disposal of radioactive wastes into the sea would not involve an unacceptable degree of hazard to man. The Director General of the IAEA and an expert panel in 1960 considered the administrative, organizational and legal measures which might be taken on an international level on the basis of the Brynielsson Report. This panel held four meetings between January 1961 and January 1963. From the very beginning of its work, two different views arose on the fundamental questions of the permissibility of disposing radioactive waste into the sea under international law. One viewpoint was to prohibit the disposal of all radioactive wastes into the sea, while the other proposed to seek permission prior to disposal and to register it. In 1967 a technical panel was convened to discuss Standardization of Waste Categories and in 1970 the panel on Procedures for Establishing Limits for Radionuclides in the Sea was aimed at clarifying the principles for limiting the introduction of radioactive waste into the sea and for establishing a register of radioactive waste discharged into

  1. Permissible limit for mandibular expansion.

    Science.gov (United States)

    Motoyoshi, Mitsuru; Shirai, Sawa; Yano, Shinya; Nakanishi, Kotoe; Shimizu, Noriyoshi

    2005-04-01

    In recent years, mandibular expansion has been increasingly performed in conjunction with orthodontic treatment. Lateral tipping of the molars associated with mandibular expansion should, however, be considered, because excessive expansion may result in excessive buccal tooth inclination, which may disturb the occlusal relationship. This study was conducted to quantitatively clarify molar movement during mandibular expansion using the Schwarz appliance to determine the permissible limit of mandibular expansion as a clinical index for inclination movement. Inclinations in the masticatory surface of the first molar and intermolar width were measured before expansion (T1), after expansion (T2), and before edgewise treatment (T3). Lower plaster models from 29 subjects treated with expansion plates were used and compared with models from 11 control subjects with normal occlusion. The average treatment change (T1-T2) in intermolar width was 5.42 mm (standard deviation 1.98), and the average angle of buccal tooth inclination was 10.16 degrees (standard deviation 3.83). No significant correlation was found between age prior to treatment and the treatment period when they were compared with the intermolar width increments and inclination angles. There was a significant positive correlation between retention duration and the amount of expansion. The regression coefficient of the angle of buccal tooth inclination during expansion to the increment of the intermolar width was approximately 0.2. This means that 1 mm of expansion is accompanied by 5 degrees of molar lateral tipping. This coefficient is clinically useful for estimating the permissible limit for mandibular expansion.

  2. Prostatic carcinoma: limited field irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Rounsaville, M.C.; Green, J.P.; Vaeth, J.M.; Purdon, R.P.; Heltzel, M.M.

    1987-07-01

    This is a retrospective study of 251 patients with histologically proven adenocarcinoma treated primarily with limited field radiotherapy techniques, under the principle direction of authors JMV and JPG, between 1968 and 1981 in San Francisco, California. All patients are followed for a minimum of 3 years; mean follow-up is 7.3 years. Routine clinical staging procedures included: HandP, digital prostate exam, cystoscopy, biopsy, blood studies including serum acid phosphatase, and imaging studies including chest X ray, IVP, bone survey or radionucleotide bone scan, and in recent years, pelvic CT scans. Twelve patients are Stage A1, 37-Stage A2, 50-Stage B, 140-Stage C1 and 12-Stage C2. Ninety percent of all cases and 85% of Stage C patients were treated with limited fields to the prostate and periprostatic volume only. Total doses were prescribed at midplane or isocenter and were generally 6500-7000 cGy, daily doses of 180-200 cGy, 5 days per week. Actuarial 5- and 10-year survival rates are: entire population-69% and 47%; Stage A1-74% and 50%; Stage A2-81% and 67%; Stage B-84% and 53%; Stage C1-63% and 42%; Stage C2-32% and 11%. The 5- and 10-year disease-free actuarial survivals are: entire population-71% and 50%; Stage A1-89% and 74%; Stage A2-82% and 69%; Stage B-71% and 52%; Stage C1-67% and 44%; Stage C2-0%. Sites of recurrence, alone or as a component of the failure pattern are: 37 (15%) local, 11 (4%) symptomatic regional recurrence (lower extremity edema, pelvic pain/sciatica, hydroureteronephrosis), and 87 (35%) distant metastasis. Seven (3%) had unknown sites of failure. Local-regional failure occurred in 42% of Stage C2 patients.

  3. Pure Phase Solubility Limits: LANL

    Energy Technology Data Exchange (ETDEWEB)

    C. Stockman

    2001-01-26

    The natural and engineered system at Yucca Mountain (YM) defines the site-specific conditions under which one must determine to what extent the engineered and the natural geochemical barriers will prevent the release of radioactive material from the repository. Most important mechanisms for retention or enhancement of radionuclide transport include precipitation or co-precipitation of radionuclide-bearing solid phases (solubility limits), complexation in solution, sorption onto surfaces, colloid formation, and diffusion. There may be many scenarios that could affect the near-field environment, creating chemical conditions more aggressive than the conditions presented by the unperturbed system (such as pH changes beyond the range of 6 to 9 or significant changes in the ionic strength of infiltrated waters). For an extended period of time, the near-field water composition may be quite different and more extreme in pH, ionic strength, and CO{sub 2} partial pressure (or carbonate concentration) than waters at some distance from the repository. Reducing conditions, high pH (up to 11), and low carbonate concentration may be present in the near-field after reaction of infiltrating groundwater with engineered barrier systems, such as cementitious materials. In the far-field, conditions are controlled by the rock-mass buffer providing a near-neutral, oxidizing, low-ionic-strength environment that controls radionuclide solubility limits and sorption capacities. There is the need for characterization of variable chemical conditions that affect solubility, speciation, and sorption reactions. Modeling of the groundwater chemistry is required and leads to an understanding of solubility and speciation of the important radionuclides. Because experimental studies cannot be performed under the numerous potential chemical conditions, solubility limitations must rely on geochemical modeling of the radionuclide's chemistry. Fundamental thermodynamic properties, such as solubility

  4. Psychoanalysis on the couch: can neuroscience provide the answers?

    Science.gov (United States)

    Mechelli, Andrea

    2010-12-01

    Over a century after Freud's attempt to establish psychoanalysis as a natural science, there is renewed interest in the integration of psychoanalytic and neuroscientific findings within a single theoretical and experimental framework. However, it is important that any intellectual exchange is not motivated only by declining confidence in psychoanalytic theory and practice or awareness of the rising fortunes of the brain sciences. The present paper considers three possible ways in which psychoanalysis and neuroscience might be integrated. These include the investigation of the neurological organisation of psychoanalytically defined phenomena; the evaluation of psychoanalytic theories based on their neurobiological evidence; and the use of neuroimaging techniques to assess the progress and outcome of psychoanalytic treatment. The author argues that these exercises are unlikely to provide psychoanalysis with the "unlimited opportunities for overcoming its uncertainties and doubts" that some have anticipated. For instance, the argument that mapping psychoanalytically defined phenomena in the brain may provide biological validity to these phenomena should be considered an expression of logical confusion; the evaluation of psychoanalytic theories based on their biological evidence is critically dependent on speculative interpretation of what the theories predict at neuronal level; and the supposedly objective evaluation of the progress and outcome of psychoanalytic treatment on the basis of neurobiological data relies on the subjective reports of the patient and analyst. In light of this conclusion, there are a number of outstanding questions which remain to be addressed, including whether psychoanalysis should adhere to scientific canons and whether this would necessarily require an experimental methodology. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Complications of traditional couching in a Nigerian local population ...

    African Journals Online (AJOL)

    ,38 et atrophie optique 15,38%. Acuité visuelle d'aucune perception de lumière était vu dans 33,33% des yeux principalement à travers le glaucome secondaire mais 50% des yeux avaient eu acuité visuelle corrigée de 6/18 ou mieux.

  6. Authoring from the Couch: Research Directions and Possibilities

    NARCIS (Netherlands)

    R.L. Guimarães (Rodrigo); P.S. Cesar Garcia (Pablo Santiago); D.C.A. Bulterman (Dick)

    2008-01-01

    htmlabstractDespite most of the authoring systems for digital TV assume the author to be seated in front of a computer on the broadcaster side, current research is interested in the new role of the viewer in producing and distributing content. The goal of this paper is to identify a number of

  7. Risk Factors for Couching Practices in Plateau State, Nigeria ...

    African Journals Online (AJOL)

    Perpetua

    obtained from the state office of the National Population. Commission. The estimated target population was 627,206. To calculate the minimum sample size, the following parameters were used in the Rapid Assessment of Cataract. Surgical Services (RACSS) software: an estimated prevalence of blindness due to cataract of ...

  8. Films from the Couch: Film Theory and Psychoanalysis

    Directory of Open Access Journals (Sweden)

    Pedro Sangro Colón

    2008-10-01

    Full Text Available   Different disciplines have contributed to weaving a theory of psychoanalysis in the cinema: ranging from the loans from anthropology and experimental psychology, to proposals belonging to the specific sphere of film theory, such as Filmology, Text Analysis or Feminist Theory in films. In all cases, the aim is to establish a relationship between the significance structure that governs the cinema and psychology, so as to confirm that the cinema’s system of representation is modelled on our unconscious psychological apparatus, as was explained by the psychoanalyst Jacques Lacan, among others. The arrival of psychoanalysis in film thought forges the idea that considers the cinema as an auxiliary psychological device capable of making us subjects and submerging us in the emotions in play in the conflicts proposed by any audiovisual story.

  9. Trauma child on the couch: transference, introjection, identification.

    Science.gov (United States)

    Kelley-Lainé, Kathleen

    2014-03-01

    This paper attempts to explore some of the psychic processes at work with patients whom I identify as the "trauma child". The term is a metaphor rather than a diagnosis of "traumatisation", to indicate patients particularly resistant to maturational processes. They feel blocked and thereby find it difficult to evolve as creative adults. As opposed to the "traumatised" child no particular distressing event can be identified as a cause for emotional suffering. The malaise is often "low key" or silent but functions as a saboteur, undermining satisfactory existence. The trauma child is constantly seduced by regressive functioning and bound by numerous strategies of resistance of reality and often incapable of relinquishing the boundless pleasure of omnipotence. On the basis of my clinical work with the "trauma child", I will explore the different processes of introjection in transference and counter transference, paying particular attention to the dynamics of identification between analyst and patient and its implications for object relations. Instead of "healthy" identification with the other, taking account of difference and reality, the mode of object relations can be that of "pathological imitation" based on fantasies of oral incorporation. A kind of regressive defense against "mature" relationships; it is an attempt to acquire a substitute identity through magical imitation. Analytical listening, associative work and interpretation stimulate maturational processes within the patient and help him/her to let go of immature relational modes fixated in childhood.

  10. Changing ideas of global limits.

    Science.gov (United States)

    Goddy, D

    1984-03-02

    In this discussion of changing ideas of global limits, attention is directed to world trade, moral restraint, and the "green revolution." A fresh look at the work of those who first considered population problems, e.gg., Malthur, can help make some sense of the population problems the world faces today. Malthus, writing in the late 1700s, concluded that population multiplies with each generation. He saw that food production was limited by the amount of available cropland and that the more people there are, the less food they will have to eat -- assuming that all available cropland is planted. This grim view of the future led Malthus to oppose government aid to the poor maintaining that such assistance would only encourage poor people to have large families. His solution was "moral restratin," seeing it as the duty of each individual to refrain from marriage until he was able to support his children. At the time this advice seemed cruel and Malthus was bitterly attacked by writers everywhere in Europe. Karl Marx and other ctitics of Malthus believed that poverty was caused by unjust governments and the selfishness of the rich. Marx clamied that the problem was too few jobs rather than too many people. The dire predictions of Malthus were soon forgotten as manufacturing industries began to transform the economies of Western Europe in the 1800s. Along with soaring economic growth came a host of developments that improved people's lives, e.g., better transportation, better sanitiation and nutrition, and better medicine. New inventions helped farmers fo produce more food. Next came the "demographic transition." Population grew quickly in Europe and North America as people became healthier and lived longer. Gradually, people in the industrial nations began deciding to have smaller families to enable them to afford an even higher living standard. By the late 1920s birthrates in Europe and the US had dropped so low that mention of the "population problem" usually referred

  11. Laboratory Limits on Neutrino Masses

    Science.gov (United States)

    Weinheimer, Christian

    The recent neutrino oscillation experiments have obtained nonzero differences of squared neutrino masses and therefore proven that neutrinos are massive particles. The values of the neutrino masses have to be determined in a different way. There are two classes of laboratory experiments, both of which have yielded up to now only upper limits on neutrino masses. The direct mass experiments investigate the kinematics of weak decays, obtaining information about the neutrino mass without further requirements. Here, the tritium β decay experiments give the most stringent results. The search for neutrinoless double β decay is also very sensitive to the neutrino mass states. However, this search is complementary to direct neutrino mass experiments, since it requires neutrinos to be identical to their antiparticles and probes a linear combination of neutrino masses including complex phases. This chapter is structured as follows. After an introduction in Sect. 2.1, the two approaches are discussed together with the current experimental results in Sects. 2.2 and 2.3, followed by consideration of the outlook for future activities in Sect. 2.4.

  12. IDENTIDADES MASCULINAS: LIMITES E POSSIBILIDADES

    Directory of Open Access Journals (Sweden)

    May-Lin Wang

    2006-06-01

    Full Text Available O presente trabalho toma por base uma abordagem psicossocial para discorrer sobre os limites impostos pelos estereótipos de gênero à construção de uma identidade masculina, em contraposição às possibilidades de subjetivação, num cenário cultural de pluralidade identitária. Ênfase é dada à socialização estereotipada dos meninos, num processo no qual se verifica uma espécie de superposição do contexto socio-histórico em que cresceram os pais àquele no qual o menino é socializado, acentuando determinadas crenças sobre gênero. O modelo tradicional de virilidade, que imperava inquestionável até bem pouco tempo, ignorando as necessidades afetivas e valorizando características como a competitividade, a preocupação com o desempenho, o autoritarismo, a dominação e a opressão, vem sendo questionado como pilar maior da identidade masculina tradicional.

  13. Limits to Drift Chamber Resolution

    CERN Document Server

    Riegler, Werner

    1998-01-01

    ATLAS (A Large Toroidal LHC Apparatus) will be a general-purpose experiment at the Large Hadron Collider that will be operational at CERN in the year 2004. The ATLAS muon spectrometer aims for a momentum resolution of 10% for a transverse momentum of pT=1TeV. The precision tracking devices in the muon system will be high pressure drift tubes (MDTs) with a single wire resolution of 1100 chambers covering an area of ≈ 2500m2. The high counting rates in the spectrometer as well as the aim for excellent spatial resolution and high efficiency put severe constraints on the MDT operating parameters. This work describes a detailed study of all the resolution limiting factors in the ATLAS environment. A ’full chain’ simulation of the MDT response to photons and charged particles as well as quantitative comparisons with measurements was performed. The good agreement between simulation and measurements resulted in a profound understanding of the drift chamber processes and the individual contributions to the spat...

  14. Photon and graviton mass limits

    Energy Technology Data Exchange (ETDEWEB)

    Nieto, Michael [Los Alamos National Laboratory; Goldhaber Scharff, Alfred [SUNY

    2008-01-01

    We review past and current studies of possible long-distance, low-frequency deviations from Maxwell electrodynamics and Einstein gravity. Both have passed through three phases: (1) Testing the inverse-square laws of Newton and Coulomb, (2) Seeking a nonzero value for the rest mass of photon or graviton, and (3) Considering more degrees of freedom, allowing mass while preserving gauge or general-coordinate invariance. For electrodynamics there continues to be no sign of any deviation. Since our previous review the lower limit on the photon Compton wavelength (associated with weakening of electromagnetic fields in vacuum over large distance scale) has improved by four orders of magnitude, to about one astronomical unit. Rapid current progress in astronomical observations makes it likely that there will be further advances. These ultimately could yield a bound exceeding galactic dimensions, as has long been contemplated. Meanwhile, for gravity there have been strong arguments about even the concept of a graviton rest mass. At the same time there are striking observations, commonly labeled 'dark matter' and 'dark energy' that some argue imply modified gravity. This makes the questions for gravity much more interesting. For dark matter, which involves increased attraction at large distances, any explanation by modified gravity would be qualitatively different from graviton mass. Because dark energy is associated with reduced attraction at large distances, it might be explained by a graviton-mass-like effect.

  15. Voltage limitations of electrostatic accelerators

    International Nuclear Information System (INIS)

    Hyder, H. R. McK.

    1999-01-01

    The history of electrostatic accelerators has been punctuated by a series of projects in which innovative designs have failed to meet the expectations of their designers. From the early, air-insulated Van de Graaffs at Round Hill to certain of the large pressurized heavy ion accelerators of the 1970s and 1980s, increases in size or changes in design and materials have not always led to the maximum voltages expected or extrapolated. Since these failures have continued beyond childhood into a mature technology, it is reasonable to assume that the causes of voltage limitation are varied and complex. They have remained poorly understood for a number of reasons: resources for an extended program of research into breakdown and failure of electrostatic generators have always been meager, especially for large machines devoted to nuclear research; the inaccessibility of pressurized generators makes instrumentation difficult and testing slow; the calculation of transient and dynamic effects is laborious and the results difficult to verify; voltage test experiments on operating accelerators are inhibited by the significant risk of damage due to energy release on breakdown: and the total voltages (though not the local fields) achieved in many electrostatic accelerators exceed those produced in any other man-made environment. In this review, the behavior of several generators of different designs is examined in order to assess the importance of the various design features and operating conditions that control the maximum voltage achievable in a working machine

  16. Voltage limitations of electrostatic accelerators

    International Nuclear Information System (INIS)

    Hyder, H.R.

    1999-01-01

    The history of electrostatic accelerators has been punctuated by a series of projects in which innovative designs have failed to meet the expectations of their designers. From the early, air-insulated Van de Graaffs at Round Hill to certain of the large pressurized heavy ion accelerators of the 1970s and 1980s, increases in size or changes in design and materials have not always led to the maximum voltages expected or extrapolated. Since these failures have continued beyond childhood into a mature technology, it is reasonable to assume that the causes of voltage limitation are varied and complex. They have remained poorly understood for a number of reasons: resources for an extended program of research into breakdown and failure of electrostatic generators have always been meager, especially for large machines devoted to nuclear research; the inaccessibility of pressurized generators makes instrumentation difficult and testing slow; the calculation of transient and dynamic effects is laborious and the results difficult to verify; voltage test experiments on operating accelerators are inhibited by the significant risk of damage due to energy release on breakdown: and the total voltages (though not the local fields) achieved in many electrostatic accelerators exceed those produced in any other man-made environment. In this review, the behavior of several generators of different designs is examined in order to assess the importance of the various design features and operating conditions that control the maximum voltage achievable in a working machine. copyright 1999 American Institute of Physics

  17. Extremity replantations: Possibilities and limitations

    Directory of Open Access Journals (Sweden)

    Vučetić Čedomir

    2011-01-01

    Full Text Available Amputated parts of extremities can be replanted under some convenient conditions. Replantations have been done for over four decades. The long way of technological development has been passed and today the great results of recovering are reached. Replantations are challenge with many possibilities, but also with many limitations, because the operation is very complexive. Our research shows that traumatic amputations on extremities in Serbia are mostly caused by circular saw (41%, by ax (14,6%, by shelter (12,5%, by press and in traffic (10,4%, by cable, rope, chain and derrick (9% and by wedding ring (2,1%. General recovery of replanted fingers, according Tamai criteria, on our clinical material was excellent in 29,8% of cases, good (42,5%, satisfying (22,9% and bad (4,6%. Every patient was satisfied with operation, according the subjective patients' estimation. During the past decades the huge experience has been collected and various technological development in medicine suggest redefinition of indications and also suggest accepting particular, individual indications in some cases of amputated parts of extremity and replantations.

  18. Opacity Limit for Supermassive Protostars

    Science.gov (United States)

    Becerra, Fernando; Marinacci, Federico; Inayoshi, Kohei; Bromm, Volker; Hernquist, Lars E.

    2018-04-01

    We present a model for the evolution of supermassive protostars from their formation at {M}\\star ≃ 0.1 {M}ȯ until their growth to {M}\\star ≃ {10}5 {M}ȯ . To calculate the initial properties of the object in the optically thick regime, we follow two approaches: one based on idealized thermodynamic considerations, and another based on a more detailed one-zone model. Both methods derive a similar value of {n}{{F}}≃ 2× {10}17 {cm}}-3 for the density of the object when opacity becomes important, i.e., the opacity limit. The subsequent evolution of the growing protostar is determined by the accretion of gas onto the object and can be described by a mass–radius relation of the form {R}\\star \\propto {M}\\star 1/3 during the early stages, and of the form {R}\\star \\propto {M}\\star 1/2 when internal luminosity becomes important. For the case of a supermassive protostar, this implies that the radius of the star grows from {R}\\star ≃ 0.65 {au} to {R}\\star ≃ 250 {au} during its evolution. Finally, we use this model to construct a subgrid recipe for accreting sink particles in numerical simulations. A prime ingredient thereof is a physically motivated prescription for the accretion radius and the effective temperature of the growing protostar embedded inside it. From the latter, we can conclude that photoionization feedback can be neglected until very late in the assembly process of the supermassive object.

  19. The limits of racial prejudice.

    Science.gov (United States)

    Lewis, Kevin

    2013-11-19

    The racial segregation of romantic networks has been documented by social scientists for generations. However, because of limitations in available data, we still have a surprisingly basic idea of the extent to which this pattern is generated by actual interpersonal prejudice as opposed to structural constraints on meeting opportunities, how severe this prejudice is, and the circumstances under which it can be reduced. I analyzed a network of messages sent and received among 126,134 users of a popular online dating site over a 2.5-mo period. As in face-to-face interaction, online exchanges are structured heavily by race. Even when controlling for regional differences in meeting opportunities, site users-especially minority site users-disproportionately message other users from the same racial background. However, this high degree of self-segregation peaks at the first stage of contact. First, users from all racial backgrounds are equally likely or more likely to cross a racial boundary when reciprocating than when initiating romantic interest. Second, users who receive a cross-race message initiate more new interracial exchanges in the future than they would have otherwise. This effect varies by gender, racial background, and site experience; is specific to the racial background of the original sender; requires that the recipient replied to the original message; and diminishes after a week. In contrast to prior research on relationship outcomes, these findings shed light on the complex interactional dynamics that-under certain circumstances-may amplify the effects of racial boundary crossing and foster greater interracial mixing.

  20. Measuring stress: Uses and limitations

    Energy Technology Data Exchange (ETDEWEB)

    Suter, G.W. II [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.

    1994-12-31

    The topic of the uses and limitations of measuring stress in the oceans is addressed. The use of the term stress in this context is ambiguous. Rather than assuming that stress is an actual measurable property of oceans, one may assume that the term refers to the complex of harmful things that is going on in the oceans. that is, it is a cover term for a complex of processes and states, many of which are unknown or undefined. The appeal of the term stress used in that way is very tempting. Considerable complexity results from the fact that the ocean consists of numerous and diverse species and ecosystems each of which have various properties that have some claim to protection. Another source of complexity is the diversity of factors which constitute threats to the environment. In evaluating the concepts of ecological risk assessment, there are sources of hazardous agents, there are receptors that are affected, and there is a process by which these interact termed exposure. As a result of exposure there is some probability that the actions of the sources have caused or will cause some effect on the receptor, the risk. Assessments may be source driven; they may attempt to determine the risks associated with a waste outfall. Assessments may also be effects driven; they may attempt to determine the cause of a die-off of marine mammals or determine the likelihood of a particular rise in sea-level. Finally, they may be exposure driven. Each of these components of the causal chain might serve as measures of stress.

  1. 45 CFR 3.26 - Speed limit.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Speed limit. 3.26 Section 3.26 Public Welfare... INSTITUTES OF HEALTH FEDERAL ENCLAVE Traffic Regulations § 3.26 Speed limit. The speed limit is 25 miles per hour, unless otherwise posted. A driver of a vehicle may not exceed the speed limit. ...

  2. Food irradiation: advantages and limitations

    International Nuclear Information System (INIS)

    Hernandes, N.K.; Vital, H. de C.; Sabaa-Srur, A.U.O.

    2003-01-01

    Food irradiation is a physical method of processing food (e.g. freezing, canning). It has been thoroughly researched over the last four decades and is recognized as a safe and wholesome method. It has the potential both of disinfesting dried food to reduce storage losses and disinfesting fruits and vegetables to meet quarantine requirements for export trade. Low doses of irradiation inhibit spoilage losses due to sprouting of root and tuber crops. Food- borne diseases due to contamination by pathogenic microorganisms and parasites of meat, poultry, fish, fishery products and spices are on the increase. Irradiation of these solid foods can decontaminate them of pathogenic organisms and thus provide safe food to the consumer. Irradiation can successfully replace the fumigation treatment of cocoa beans and coffee beans and disinfest dried fish, dates, dried fruits, etc. One of the most important advantages of food irradiation processing is that it is a coldprocess which does not significantly alter physico-chemical characters of the treated product. It can be applied to food after its final packaging. Similar to other physical processes of food processing, (e.g. canning, freezing), irradiation is a capital intensive process. Thus, adequate product volume must be made available in order to maximize the use of the facility and minimize the unit cost of treatment. Lack of harmonization of regulations among the countries which have approved irradiated foods hampers the introduction of this technique for international trade. Action at the international level has to be taken in order to remedy this situation. One of the important limitations of food irradiation processing is its slow acceptance by consumers, due inter alia to a perceived association with radioactivity. The food industry tends to be reluctant to use the technology in view of uncertainties regarding consumer acceptance of treated foods. Several market testing and consumer acceptance studies have been carried

  3. Term limits and the tobacco industry.

    Science.gov (United States)

    Apollonio, Dorie E; Glantz, Stanton A; Bero, Lisa A

    2014-03-01

    In the 1990s several American states passed term limits on legislators with the stated intention of reducing the influence of wealthy industries on career legislators. Although term limits in the United States do not have a direct relationship to public health, the tobacco industry anticipated that term limits could have indirect effects by either limiting or expanding industry influence. We detail the strategy of the tobacco industry in the wake of term limits using internal tobacco company documents and a database of campaign contributions made to legislators in term limited states between 1988 and 2002. Despite some expectations that term limits would limit tobacco industry access to state legislators, term limits appear to have had the opposite effect. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Beta limits of a completely bootstrapped tokamak

    International Nuclear Information System (INIS)

    Weening, R.H.; Bondeson, A.

    1992-03-01

    A beta limit is given for a completely bootstrapped tokamak. The beta limit is sensitive to the achievable Troyon factor and depends directly upon the strength of the tokamak bootstrap effect. (author) 16 refs

  5. Setting limits on supersymmetry using simplified models

    CERN Document Server

    Gutschow, C.

    2012-01-01

    Experimental limits on supersymmetry and similar theories are difficult to set because of the enormous available parameter space and difficult to generalize because of the complexity of single points. Therefore, more phenomenological, simplified models are becoming popular for setting experimental limits, as they have clearer physical implications. The use of these simplified model limits to set a real limit on a concrete theory has not, however, been demonstrated. This paper recasts simplified model limits into limits on a specific and complete supersymmetry model, minimal supergravity. Limits obtained under various physical assumptions are comparable to those produced by directed searches. A prescription is provided for calculating conservative and aggressive limits on additional theories. Using acceptance and efficiency tables along with the expected and observed numbers of events in various signal regions, LHC experimental results can be re-cast in this manner into almost any theoretical framework, includ...

  6. On thermodynamic limits of entropy densities

    NARCIS (Netherlands)

    Moriya, H; Van Enter, A

    We give some sufficient conditions which guarantee that the entropy density in the thermodynamic limit is equal to the thermodynamic limit of the entropy densities of finite-volume (local) Gibbs states.

  7. Toward Modeling Limited Plasticity in Ceramic Materials

    National Research Council Canada - National Science Library

    Grinfeld, Michael; Schoenfeld, Scott E; Wright, Tim W

    2008-01-01

    The characteristic features of many armor-related ceramic materials are the anisotropy on the micro-scale level and the very limited, though non-vanishing, plasticity due to limited number of the planes for plastic slip...

  8. The limiting current in a one-dimensional situation: Transition from a space charge limited to magnetically limited flow

    International Nuclear Information System (INIS)

    Kumar, Raghwendra; Biswas, Debabrata

    2008-01-01

    For a nonrelativistic electron beam propagating in a cylindrical drift tube, it is shown that the limiting current density does not saturate to the electrostatic one-dimensional (1D) estimate with increasing beam radius. Fully electromagnetic particle-in-cell (PIC) simulation studies show that beyond a critical aspect ratio, the limiting current density is lower than the 1D electrostatic prediction. The lowering in the limiting current density is found to be due to the transition from the space charge limited to magnetically limited flow. An adaptation of Alfven's single particle trajectory method is used to estimate the magnetically limited current as well as the critical radius beyond which the flow is magnetically limited in a drift tube. The predictions are found to be in close agreement with PIC simulations

  9. ISX-A graphite limiter experiment

    International Nuclear Information System (INIS)

    Langley, R.A.; Colchin, R.J.; Isler, R.C.; Murakami, M.; Simpkins, J.E.; Cecchi, J.L.; Corso, V.L.; Dylla, H.F.; Ellis, R.A. Jr.; Nishi, M.

    1979-01-01

    Graphite limiters were installed and tested in the ISX-A tokamak as part of the ISX-A surface physics program and the TFTR materials research program. The puropse of the experiment was to compare plasma performance using graphite limiters as opposed to the standard ISX-A stainless steel limiters. Heaters were installed in the graphite limiters so that the effects of operation at elevated temperatures could be evaluated

  10. Codimension zero laminations are inverse limits

    OpenAIRE

    Lozano Rojo, Álvaro

    2013-01-01

    The aim of the paper is to investigate the relation between inverse limit of branched manifolds and codimension zero laminations. We give necessary and sufficient conditions for such an inverse limit to be a lamination. We also show that codimension zero laminations are inverse limits of branched manifolds. The inverse limit structure allows us to show that equicontinuous codimension zero laminations preserves a distance function on transversals.

  11. 7 CFR 52.3185 - Moisture limits.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Moisture limits. 52.3185 Section 52.3185 Agriculture... United States Standards for Grades of Dried Prunes Moisture, Uniformity of Size, Defects § 52.3185 Moisture limits. Dried prunes shall not exceed the moisture limits for the applicable grades and kind and...

  12. 50 CFR 38.13 - Speed limits.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 6 2010-10-01 2010-10-01 false Speed limits. 38.13 Section 38.13 Wildlife... NATIONAL WILDLIFE REFUGE SYSTEM MIDWAY ATOLL NATIONAL WILDLIFE REFUGE Prohibitions § 38.13 Speed limits. No person on Midway Atoll National Wildlife Refuge will exceed the speed limit for automobiles, trucks...

  13. 36 CFR 1004.21 - Speed limits.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Speed limits. 1004.21 Section 1004.21 Parks, Forests, and Public Property PRESIDIO TRUST VEHICLES AND TRAFFIC SAFETY § 1004.21 Speed limits. (a) Speed limits in the area administered by the Presidio Trust are as follows: (1) 15 miles per...

  14. Author: IM Rautenbach PROPORTIONALITY AND THE LIMITATION ...

    African Journals Online (AJOL)

    10332324

    understood are defined, and the way in which the concepts "limitation of rights" and. "limitation clauses" are ... conflict between rights and powers, between powers, between rights, involving in each case the same ...... limitation of rights from taking hard and difficult decisions on what is required in "an open and democratic ...

  15. 29 CFR 4050.11 - Limitations.

    Science.gov (United States)

    2010-07-01

    ... missing participants. (b) Limitation on benefit value. The total actuarial present value of all benefits... 29 Labor 9 2010-07-01 2010-07-01 false Limitations. 4050.11 Section 4050.11 Labor Regulations... § 4050.11 Limitations. (a) Exclusive benefit. The benefits provided for under this part will be the only...

  16. 12 CFR 24.4 - Investment limits.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Investment limits. 24.4 Section 24.4 Banks and... ENTITIES, COMMUNITY DEVELOPMENT PROJECTS, AND OTHER PUBLIC WELFARE INVESTMENTS § 24.4 Investment limits. (a) Limits on aggregate outstanding investments. A national bank's aggregate outstanding investments under...

  17. 12 CFR 616.6600 - Leasing limit.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Leasing limit. 616.6600 Section 616.6600 Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM LEASING § 616.6600 Leasing limit. All leases made by Farm Credit System institutions shall be subject to the lending and leasing limit in subpart J...

  18. High temperature superconducting fault current limiter

    Science.gov (United States)

    Hull, John R.

    1997-01-01

    A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).

  19. 47 CFR 73.1725 - Limited time.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Limited time. 73.1725 Section 73.1725... Rules Applicable to All Broadcast Stations § 73.1725 Limited time. (a) Operation is applicable only to... stations on the channel. (b) No authorization will be granted for: (1) A new limited time station; (2) A...

  20. The density limit in JET diverted plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, D.J.; Clement, S.; Gottardi, N.; Gowers, C.; Harbour, P.; Loarte, A.; Horton, L.; Lingertat, J.; Lowry, C.G.; Saibene, G.; Stamp, M.; Stork, D. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Monk, R. [Royal Holloway Coll., London (United Kingdom). Dept. of Physics

    1994-07-01

    In JET limiter plasmas the density limit is associated with radiated power fractions of 100% and, in plasmas with carbon limiters, it is invariably disruptive. However, in discharges with solid beryllium limiters the limit is identified with the formation of a MARFE and disruptions are less frequent. In addition, the improved conditioning of the vessel arising from the use of beryllium has significantly improved the density limit scaling, so that the maximum density rises with the square root of the input power. In diverted plasmas several confinement regimes exist, making the characterization of the density limit more complex. While the density limit in L-mode plasmas is generally disruptive, the limit in ELMy and ELM-free H-modes generally prompts a return to the L-mode and a disruption is not inevitable. The density limit does rise with the increasing power, but the L-to-H transition complicates the analysis. Nevertheless, at low plasma currents (<2 MA), densities significantly above the Greenwald limit can be achieved, while at higher currents power handling limitations have constrained the range of density which can be achieved. (authors). 7 refs., 4 figs.

  1. Effluent release limits, sources and control

    International Nuclear Information System (INIS)

    Swindell, G.E.

    1977-01-01

    Objectives of radiation protection in relation to releases. Environmental transfer models for radionuclides. Relationship between releases, environmental levels and doses to persons. Establishment of release limits: Limits based on critical population group concept critical pathway analysis and identification of critical group. Limits based on optimization of radiation protection individual dose limits, collective doses and dose commitments 1) differential cost benefit analysis 2) authorized and operational limits taking account of future exposures. Monitoring of releases to the environment: Objectives of effluent monitoring. Typical sources and composition of effluents; design and operation of monitoring programmes; recording and reporting of monitoring results; complementary environmental monitoring. (orig.) [de

  2. Predictions of nitrogen oxides production in diffusion turbulent flames; Predictions de la production des oxydes d`azote dans les flammes turbulentes de diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, H.; Gokalp, I. [Centre National de la Recherche Scientifique (CNRS), 45 - Orleans-la-Source (France). Laboratoire de Combustion Systemes Reactifs

    1996-12-31

    The suitability of the turbulent combustion flamelets model in order to predict the index of NO{sub x} production in turbulent flames of hydrogen diffusion is analyzed. In the flamelet approach, the turbulent flame is equivalent to a group of laminar flames submitted to a mechanical stretching which generates a chemical disequilibrium. This effect can be described by the stretching or by the scalar dissipation ratio. A numerical modeling is performed in order to evaluate the advantages of both approaches and to compare the behaviour of the NO{sub x} emission index with the experiments of Chen and Driscoll. This study shows that predictions of NO{sub x} emission indexes have a correct behaviour with respect to the Damkoehler number only when the scalar dissipation ratio is used as a parameter to describe the chemical state outside equilibrium. Predictions of the flamelet models are improving when the Damkoehler number increases. On the other hand, the absolute NO{sub x} concentrations are overestimated and can be due to the effects of differential diffusion. (J.S.) 14 refs.

  3. Mecanismos, processos e democracias : a sociologia histórica de Charles Tilly e a história breve mas turbulente de um lago

    Directory of Open Access Journals (Sweden)

    António Rosas

    2007-01-01

    Full Text Available Compared to its alternatives, the claims that democracies result from the material-economical modernisation, the incarnation of a certain type of political culture or the institutional objectivation seem to be less and less reasonable. The aim of this article is not only to familiarise the reader with one of the most promising theoretical perspectives of contemporary comparative historical sociology – that of Charles Tilly – but also to demonstrate how a processual analysis of political regimes is the more suitable to understand and improve today’s real democracies.

  4. Turbulent viscosity and scale laws in turbulent jets with variable density; Viscosite turbulente et lois d`echelles dans les jets turbulents a masse volumique variable

    Energy Technology Data Exchange (ETDEWEB)

    Pietri, L.; Amielh, M.; Anselmet, F.; Fulachier, L. [Institut de Recherche sur les Phinomenes Hors Equilibre Equipe Turbulence, 13 - Marseille (France)

    1997-12-31

    Turbulent flows with strong density variations, like helium jets in the ambient air, have specific properties linked with the difference of gas densities. This paper presents some experimental results of turbulence properties inside such flows: the Reynolds tensions and the associated turbulent viscosity, and some characteristics linked with the statistical properties of the different turbulence scales. These last results allows to show the complexity of such flows characterized by the influence of external parameters (Reynolds number, initial density ratio, initial momentum flux) that govern the evolution of these parameters inside the jet from the nozzle up to regions where similarity properties are reached. (J.S.) 12 refs.

  5. Soil pollution and soil limit values.

    Science.gov (United States)

    Horváth, A

    2000-02-01

    One of the tools for preventing soil pollution and thus protection of public health is the application of appropriate limit values. Policies on soil protection in relation to soil pollution include two basic strategies: a preventive approach and a remediation or cleanup approach. Preventive, multifunctional limit values are independent from present or future land use. Remediation limit values are connected with land use--these are functional limit values. Both types of limit values are applied in Hungary. Determination of soil limit values demands long-term field investigations, but to estimate allowable concentration for a given site reverse risk assessment methods are well applicable. A comparison and evaluation of the calculated data and the measurement results obtained at the use of the area is indispensable. Further investigations are needed for establishment of combined limit values when more polluting components are present simultaneously in the soil.

  6. Fluid Dynamics of Three-Dimensional Turbulent Shear Flows and Transition: Conference Proceedings of the Symposium of the Fluid Dynamics Panel Held in Cesme (Turkey) on 3-6 October 1988

    Science.gov (United States)

    1989-04-01

    one. Participation in AGARD activities is by invitation only and is normally limited to citizens of the NATO nations. The content of this publication ...discr~tis&s sur les maillages d~callis de la m~thode SMAC /9/, sont rdsolues par des m~thodes implicites directions altern~s (A.D.I.). C’est...turbulente. II ast A neter que las spots tur- bulents apparaissent de fagon al~ateire aussi bien en temps qu’en espace (figure 7) . Des exp~riances ont 6t6

  7. Frontiers of particle beams: Intensity limitations

    International Nuclear Information System (INIS)

    Dienes, M.; Month, M.; Turner, S.

    1992-01-01

    The present volume is the proceedings of the latest of these joint schools, held on Hilton Head Island, South Carolina, in 1990. This course dealt with intensity limitations and was centered on a series of lectures which could be divided into the following main categories: Self and environmental fields, Coherent instabilities and their simulation, Beam-beam interaction, Other multiparticle effects, Beam source limitations, Engineering limitations. (orig.)

  8. Limitation of brillouin scatter in plasmas

    International Nuclear Information System (INIS)

    Kruer, W.L.; Valeo, E.J.; Estabrook, K.G.

    1975-01-01

    A simple model is proposed for the limitation of Brillouin backscatter often observed experimentally. This limitation is a natural consequence of the limited mass and heat capacity of the underdense plasma. In this model a reflection front moves through the underdense plasma supersonically. For plasmas prepared by a prepulse, the reflectivity could then be time-dependent in agreement with some recent experimental measurements. (U.S.)

  9. Diffraction limit of refractive compound lens

    International Nuclear Information System (INIS)

    Kolchevsky, N.N.; Petrov, P.V.

    2015-01-01

    A compound X-ray and neutron lenses is an array of lenses with a common axis. The resolution limited by aberration and by diffraction. Diffraction limit comes from theory based on absorption aperture of the compound refractive lenses. Beam passing through transparent lenses form Airy pattern. Results of calculation of diffraction resolution limit for non-transparent X-ray and neutron lenses are discussed. (authors)

  10. The Limited Liability Company: An Analysis

    OpenAIRE

    Wayne Wells; Gary Yoshimoto

    1993-01-01

    In recent years, businesses in many states have been given the opportunity to select a new form in which to conduct business called the limited liability company. This form provides the advantage of the personal liability protection of a corporation, while being taxed as a partnership. If most states create the limited liability company and current issues of uncertainty are favorably resolved, the limited liability company should become the most advantageous business form for most small and m...

  11. Analysis of forming limit in tube hydroforming

    International Nuclear Information System (INIS)

    Kim, Chan Il; Yang, Seung Hang; Kim, Young Suk

    2013-01-01

    The automotive industry has shown increasing interest in tube hydroforming. Despite many automobile structural parts being produced from cylindrical tubes, failures frequently occur during tube hydroforming under improper forming conditions. These problems include wrinkling, buckling, folding back, and bursting. We perform analytical studies to determine forming limits in tube hydroforming and demonstrate how these forming limits are influenced by the loading path. Theoretical results for the forming limits of wrinkling and bursting are compared with experimental results for an aluminum tube.

  12. Practical determination of operating transfer limits

    Energy Technology Data Exchange (ETDEWEB)

    Chao, X.Y.; Austria, R.R.; Reppen, N.D.; Welsh, D.E. [Power Technologies, Inc., Schenectady, NY (United States); Uhrin, J.A.; Shultz, J.B. [Allegheny Power Service Corp., Greensburg, PA (United States)

    1995-12-31

    This paper presents a means for determining and reporting power transfer limits with respect to avoiding thermal, low voltage, and voltage collapse problems. The technique uses contingency analysis to select the most limiting contingencies, then generated PV curves for the selected cases. Adaptive transfer increments and limits on the transfer range to study are used to give the algorithm the speed necessary for on-line applications. The results of the computer implementation of the approach are also presented.

  13. Flight envelope limit detection and avoidance

    Science.gov (United States)

    Horn, Joseph Francis

    1999-12-01

    New advanced algorithms, control laws, and pilot cueing methods were developed to provide flight envelope limit protection on rotorcraft and fixed-wing aircraft. The envelope limiting systems were designed to detect an approaching limit boundary and then provide force-feel cues on the control stick so that the pilot can avoid violations of structural and controllability limits. The limit detection algorithms were designed to predict the future response of a limited parameter in order to give an adequate time margin for corrective action. The dynamic trim estimation method, which uses a neural network to estimate the quasi-steady response of the aircraft based on stick position and measured flight data, was applied to provide torque and V-n envelope protection on the XV-15 tilt-rotor aircraft and demonstrated in simulations with a pilot model. This system was also applied to provide angle-of-attack and load factor protection on the V-22 tilt-rotor aircraft and demonstrated using real-time piloted simulation. The adaptive dynamic trim estimation method extended this approach by using sensor data history to adapt to model uncertainties. The peak response limiting algorithm, which is used to detect and prevent limit violations that occur in the transient response, was applied to provide longitudinal flapping limiting on the XV-15 and demonstrated in batch simulations. Simulation results showed that the dynamic trim estimation scheme has the potential to effectively expand an aircraft's flight envelope by allowing the pilot to safely fly near limit boundaries. An adaptive algorithm was used to adjust to variations in the mass properties of the aircraft, but improvements to the adaptation method are warranted. The peak response limiting system was shown to be effective in determining rate and position constraints on the stick travel to ensure that flapping limits are not violated.

  14. Limited Approach in Endoscopic Dacryocystorhinostomy of Pediatrics

    OpenAIRE

    Hashemi, Seyyed Mostafa; Eshaghian, Afrooz

    2017-01-01

    Background: Limited spatial nasal cavity in children, make pediatric dacryocystorhinostomy (DCR) a difficult surgical procedure. We apply a limited approach to pediatric DCR and follow them for their consequences. Materials and Methods: An experimental study was done in pediatric DCR with limited approach (age < 14-year-old). After written consent, with general anesthesia, with nasal endoscopic surgery, lacrimal bone is exposed and extruded. In contrast with routine procedure, ascending proce...

  15. Asymptotic Limits in Macroscopic Plasma Models

    OpenAIRE

    Jüngel, Ansgar

    2000-01-01

    A model hierarchy of macroscopic equations for plasmas consisting of electrons and ions is presented. The model equations are derived from the transient Euler-Poisson system in the zero-relaxation-time, zero-electron-mass and quasineutral limits. These asymptotic limits are performed using entropy estimates and compactness arguments. The resulting limits equations are Euler systems with a nonlinear Poisson equation and nonlinear drift-diffusion equations.

  16. Classical limit for quantum mechanical energy eigenfunctions

    International Nuclear Information System (INIS)

    Sen, D.; Sengupta, S.

    2004-01-01

    The classical limit problem is discussed for the quantum mechanical energy eigenfunctions using the Wentzel-Kramers-Brillouin approximation, free from the problem at the classical turning points. A proper perspective of the whole issue is sought to appreciate the significance of the discussion. It is observed that for bound states in arbitrary potential, appropriate limiting condition is definable in terms of a dimensionless classical limit parameter leading smoothly to all observable classical results. Most important results are the emergence of classical phase space, keeping the observable distribution functions non-zero only within the so-called classical region at the limit point and resolution of some well-known paradoxes. (author)

  17. TFTR movable limiter instrumentation and controls

    International Nuclear Information System (INIS)

    Frankenberg, J.; Collins, D.; Kaufmann, D.; Mamoun, A.

    1983-01-01

    The TFTR movable limiter is a single poloidal limiter located within one 18 /SUP o/ segment of the vacuum vessel. It consists of three (3) interconnected inconel backing plates covered with titanium carbide coated graphite tiles. The backing plates are positioned by three independent screw drive actuators. Cooling water is fed through the horizontal port cover to tubes brazed onto the backs of the backing plates. Thermocouples monitor the limiter temperature. (1) and more fully described in refs. (1) and (2). The positioning actuators are driven by independently controlled DC servo motors, controlled either locally or from CICADA. Drive motor shaft position is monitored by chain driven encoders and potentiometers. Limiter blade position can be varied to suit any plasma within the operating range. CICADA is programmed to keep the limiter stroke within safe operating limits. A microprocessor duplicates the CICADA protective function allowing limiter operation without CICADA. The potentiometer signal is sent to an analog computer, which safeguards the limiter against failure of the encoders or the micro-processor. Cooling water flows through the limiter in 3 separate paths, one for each blade. The flow rate and temperature rise through each loop are measured accurately to allow CICADA to calculate the heat into each blade. The water system is also interlocked and alarmed to prevent dumping of water into the vacuum vessel

  18. 47 CFR 95.1019 - Marketing limitations.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Marketing limitations. 95.1019 Section 95.1019 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Low Power Radio Service (LPRS) General Provisions § 95.1019 Marketing limitations. Transmitters...

  19. 47 CFR 95.1219 - Marketing limitations.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Marketing limitations. 95.1219 Section 95.1219 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Medical Device Radiocommunication Service (MedRadio) § 95.1219 Marketing limitations. Transmitters...

  20. 50 CFR 640.21 - Harvest limitations.

    Science.gov (United States)

    2010-10-01

    ... § 640.21 Harvest limitations. (a) Berried lobsters. A berried (egg-bearing) spiny lobster or slipper...) Undersized attractants. A live spiny lobster under the minimum size limit specified in paragraph (b)(1) of... future use as an attractant in a trap provided it is held in a live well aboard the vessel. No more than...

  1. SOME LIMIT-THEOREMS IN LOG DENSITY

    NARCIS (Netherlands)

    BERKES, [No Value; DEHLING, H

    Motivated by recent results on pathwise central limit theorems, we study in a systematic way log-average versions of classical limit theorems. For partial sums S(k) of independent r.v.'s we prove under mild technical conditions that (1/log N)SIGMA(k less-than-or-equal-to N)(1/k)I{S(k)/a(k)

  2. 33 CFR 401.28 - Speed limits.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Speed limits. 401.28 Section 401... TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.28 Speed limits. (a) The maximum speed over the bottom for a vessel of more than 12 m in overall length shall be regulated so as not to...

  3. 32 CFR 935.132 - Speed limits.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Speed limits. 935.132 Section 935.132 National... WAKE ISLAND CODE Motor Vehicle Code § 935.132 Speed limits. Each person operating a motor vehicle on Wake Island shall operate it at a speed— (a) That is reasonable, safe, and proper, considering time of...

  4. h → 0 limit of quantum electrodynamics

    International Nuclear Information System (INIS)

    Dente, G.C.

    1978-01-01

    Using a two-step procedure, we construct the h → 0 limit of quantum electrodynamics: (1) We functionally integrate away the photon coordinates in the transition amplitude to a general particle state with radiation. (2) We then take the h → 0 limit, using care to vary only those particle variables which have not been specified in defining the final radiation state

  5. Tokamak advanced pump limiter experiments and analysis

    International Nuclear Information System (INIS)

    Conn, R.W.

    1983-06-01

    Experiments with pump limiter modules on several operating tokamaks establish such limiters as efficient collectors of particles and has demonstrated the importance of ballistic scattering as predicted theoretically. Plasma interaction with recycling neutral gas appears to become important as the plasma density increases and the effective ionization mean free path within the module decreases. In limiters with particle collection but without active internal pumping, the neutral gas pressure is found to vary nonlinearly with the edge plasma density at the highest densities studies. Both experiments and theory indicate that the energy spectrum of gas atoms in the pump ducting is non-thermal, consistent with the results of Monte Carlo neutral atom transport calculations. The distribution of plasma power over the front surface of such modules has been measured and appears to be consistent with the predictions of simple theory. Initial results from the latest experiment on the ISX-B tokamak with an actively pumped limiter module demonstrates that the core plasma density can be controlled with a pump limiter and that the scrape-off layer plasma can partially screen the core plasma from gas injection. The results from module pump limiter experiments and from the theory and design analysis of advanced pump limiters for reactors are used to suggest the major features of a definitive, axisymmetric, toroidal belt pump limiter experiment

  6. Modelling of particles collection by vented limiters

    International Nuclear Information System (INIS)

    Tsitrone, E.; Pegourie, B.; Granata, G.

    1995-01-01

    This document deals with the use of vented limiters for the collection of neutral particles in Tore Supra. The model developed for experiments is presented together with its experimental validation. Some possible improvements to the present limiter are also proposed. (TEC). 5 refs., 3 figs

  7. 50 CFR 648.145 - Possession limit.

    Science.gov (United States)

    2010-10-01

    ... containers. Compliance with the daily possession limit will be determined by dividing the number of black sea..., DEPARTMENT OF COMMERCE FISHERIES OF THE NORTHEASTERN UNITED STATES Management Measures for the Black Sea Bass Fishery § 648.145 Possession limit. (a) No person shall possess more than 25 black sea bass, in, or...

  8. 47 CFR 78.115 - Modulation limits.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Modulation limits. 78.115 Section 78.115... SERVICE Technical Regulations § 78.115 Modulation limits. (a) If amplitude modulation is employed, negative modulation peaks shall not exceed 100 percent modulation. [37 FR 3292, Feb. 12, 1972, as amended...

  9. 47 CFR 74.663 - Modulation limits.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Modulation limits. 74.663 Section 74.663 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... Stations § 74.663 Modulation limits. If amplitude modulation is employed, negative modulation peaks shall...

  10. 47 CFR 90.669 - Emission limits.

    Science.gov (United States)

    2010-10-01

    ... 896-901/935-940 Mhz Band § 90.669 Emission limits. (a) On any frequency in an MTA licensee's spectrum block that is adjacent to a non-MTA frequency, the power of any emission shall be attenuated below the... 47 Telecommunication 5 2010-10-01 2010-10-01 false Emission limits. 90.669 Section 90.669...

  11. The limited partnership review. Historical and comparative ...

    African Journals Online (AJOL)

    The United Kingdom limited partnership can be described as the statutory equivalent of the South African partnership en commandite, which was received from French law via Roman-Dutch law. Proposed in 1838 and eventually introduced in 1907, the limited partnership has not proved as popular as its proponents would ...

  12. 14 CFR 141.23 - Advertising limitations.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Advertising limitations. 141.23 Section 141...) SCHOOLS AND OTHER CERTIFICATED AGENCIES PILOT SCHOOLS General § 141.23 Advertising limitations. (a) The... certificate may not advertise that the school is certificated unless it clearly differentiates between courses...

  13. 14 CFR 142.31 - Advertising limitations.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Advertising limitations. 142.31 Section 142...) SCHOOLS AND OTHER CERTIFICATED AGENCIES TRAINING CENTERS General § 142.31 Advertising limitations. (a) A certificate holder may not conduct, and may not advertise to conduct, any training, testing, and checking that...

  14. Limits of detection and decision. Part 4

    International Nuclear Information System (INIS)

    Voigtman, E.

    2008-01-01

    Probability density functions (PDFs) have been derived for a number of commonly used limit of detection definitions, including several variants of the Relative Standard Deviation of the Background-Background Equivalent Concentration (RSDB-BEC) method, for a simple linear chemical measurement system (CMS) having homoscedastic, Gaussian measurement noise and using ordinary least squares (OLS) processing. All of these detection limit definitions serve as both decision and detection limits, thereby implicitly resulting in 50% rates of Type 2 errors. It has been demonstrated that these are closely related to Currie decision limits, if the coverage factor, k, is properly defined, and that all of the PDFs are scaled reciprocals of noncentral t variates. All of the detection limits have well-defined upper and lower limits, thereby resulting in finite moments and confidence limits, and the problem of estimating the noncentrality parameter has been addressed. As in Parts 1-3, extensive Monte Carlo simulations were performed and all the simulation results were found to be in excellent agreement with the derived theoretical expressions. Specific recommendations for harmonization of detection limit methodology have also been made

  15. 14 CFR 23.1583 - Operating limitations.

    Science.gov (United States)

    2010-01-01

    ... design landing weight selected by the applicant is less than the maximum weight. (3) For normal, utility... altitude and ambient temperature within the range selected by the applicant at which— (i) The airplane... furnished: (1) Limitations required by § 23.1521. (2) Explanation of the limitations, when appropriate. (3...

  16. 26 CFR 1.856-2 - Limitations.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 9 2010-04-01 2010-04-01 false Limitations. 1.856-2 Section 1.856-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES Real Estate Investment Trusts § 1.856-2 Limitations. (a) Effective date. The provisions of part II...

  17. 26 CFR 1.851-2 - Limitations.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 9 2010-04-01 2010-04-01 false Limitations. 1.851-2 Section 1.851-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES Regulated Investment Companies and Real Estate Investment Trusts § 1.851-2 Limitations. (a...

  18. 40 CFR 1502.7 - Page limits.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Page limits. 1502.7 Section 1502.7 Protection of Environment COUNCIL ON ENVIRONMENTAL QUALITY ENVIRONMENTAL IMPACT STATEMENT § 1502.7 Page limits. The text of final environmental impact statements (e.g., paragraphs (d) through (g) of § 1502.10...

  19. 42 CFR 3.414 - Limitations.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Limitations. 3.414 Section 3.414 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PROVISIONS PATIENT SAFETY ORGANIZATIONS AND PATIENT SAFETY WORK PRODUCT Enforcement Program § 3.414 Limitations. No action under this...

  20. Quantum quenches in the thermodynamic limit.

    Science.gov (United States)

    Rigol, M

    2014-05-02

    We introduce a linked-cluster based computational approach that allows one to study quantum quenches in lattice systems in the thermodynamic limit. This approach is used to study quenches in one-dimensional lattices. We provide evidence that, in the thermodynamic limit, thermalization occurs in the nonintegrable regime but fails at integrability. A phase transitionlike behavior separates the two regimes.

  1. Central Limit Theorem for Coloured Hard Dimers

    Directory of Open Access Journals (Sweden)

    Maria Simonetta Bernabei

    2010-01-01

    Full Text Available We study the central limit theorem for a class of coloured graphs. This means that we investigate the limit behavior of certain random variables whose values are combinatorial parameters associated to these graphs. The techniques used at arriving this result comprise combinatorics, generating functions, and conditional expectations.

  2. Variable Speed Limit (VSL) - Best Management Practice

    Science.gov (United States)

    2012-07-01

    The Variable Speed Limit (VSL) system on the I-4 corridor in Orlando was implemented by Florida Department of Transportation in 2008, and since its deployment, it was revealed that the majority of traffic exceeds the speed limit by more mph when the ...

  3. Challenging the limits for beam bending designs

    DEFF Research Database (Denmark)

    Goltermann, Per

    2017-01-01

    The traditional design limits of beams in bending have been challenged by testing from very under-reinforced design to over-reinforced and strengthened over-reinforced designs in order to investigate if the current limits could be abolished. The ductility of normally reinforced beam depends...

  4. Distinguishing Limitation on Constitutional Rights from Their ...

    African Journals Online (AJOL)

    Suspension of and limitation on fundamental rights and freedoms are justified violations of constitutional rights. Temporary suspension of some fundamental rights and freedoms can be made on the ground of a state of emergency. Since most constitutional rights are not absolute, they can be limited on basis of national ...

  5. 48 CFR 2901.302 - Limitations.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Limitations. 2901.302 Section 2901.302 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL DEPARTMENT OF LABOR ACQUISITION REGULATION SYSTEM Agency Acquisition Regulations 2901.302 Limitations. DOLAR System issuances are...

  6. 14 CFR 25.25 - Weight limits.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Weight limits. 25.25 Section 25.25... STANDARDS: TRANSPORT CATEGORY AIRPLANES Flight General § 25.25 Weight limits. (a) Maximum weights. Maximum... conditions (such as zero fuel weight, center of gravity position and weight distribution) must be established...

  7. The Acoustic Limit for the Boltzmann Equation

    Science.gov (United States)

    Bardos, Claude; Golse, François; Levermore, C. David

    The acoustic equations are the linearization of the compressible Euler equations about a spatially homogeneous fluid state. We first derive them directly from the Boltzmann equation as the formal limit of moment equations for an appropriately scaled family of Boltzmann solutions. We then establish this limit for the Boltzmann equation considered over a periodic spatial domain for bounded collision kernels. Appropriately scaled families of DiPerna-Lions renormalized solutions are shown to have fluctuations that converge entropically (and hence strongly in L1) to a unique limit governed by a solution of the acoustic equations for all time, provided that its initial fluctuations converge entropically to an appropriate limit associated to any given L2 initial data of the acoustic equations. The associated local conservation laws are recovered in the limit.

  8. ITER Experts' meeting on density limits

    International Nuclear Information System (INIS)

    Borrass, K.; Igitkhanov, Y.L.; Uckan, N.A.

    1989-12-01

    The necessity of achieving a prescribed wall load or fusion power essentially determines the plasma pressure in a device like ITER. The range of operation densities and temperatures compatible with this condition is constrained by the problems of power exhaust and the disruptive density limit. The maximum allowable heat loads on the divertor plates and the maximum allowable sheath edge temperature practically impose a lower limit on the operating densities, whereas the disruptive density limit imposes an upper limit. For most of the density limit scalings proposed in the past an overlap of the two constraints or at best a very narrow accessible density range is predicted for ITER. Improved understanding of the underlying mechanisms is therefore a crucial issue in order to provide a more reliable basis for extrapolation to ITER and to identify possible ways of alleviating the problem

  9. Determination of the Meteor Limiting Magnitude

    Science.gov (United States)

    Kingery, A.; Blaauw, R.; Cooke, W. J.

    2016-01-01

    The limiting meteor magnitude of a meteor camera system will depend on the camera hardware and software, sky conditions, and the location of the meteor radiant. Some of these factors are constants for a given meteor camera system, but many change between meteor shower or sporadic source and on both long and short timescales. Since the limiting meteor magnitude ultimately gets used to calculate the limiting meteor mass for a given data set, it is important to have an understanding of these factors and to monitor how they change throughout the night, as a 0.5 magnitude uncertainty in limiting magnitude translates to a uncertainty in limiting mass by a factor of two.

  10. Limiting law excess sum rule for polyelectrolytes.

    Science.gov (United States)

    Landy, Jonathan; Lee, YongJin; Jho, YongSeok

    2013-11-01

    We revisit the mean-field limiting law screening excess sum rule that holds for rodlike polyelectrolytes. We present an efficient derivation of this law that clarifies its region of applicability: The law holds in the limit of small polymer radius, measured relative to the Debye screening length. From the limiting law, we determine the individual ion excess values for single-salt electrolytes. We also consider the mean-field excess sum away from the limiting region, and we relate this quantity to the osmotic pressure of a dilute polyelectrolyte solution. Finally, we consider numerical simulations of many-body polymer-electrolyte solutions. We conclude that the limiting law often accurately describes the screening of physical charged polymers of interest, such as extended DNA.

  11. Estimating uncertainty of data limited stock assessments

    DEFF Research Database (Denmark)

    Kokkalis, Alexandros; Eikeset, Anne Maria; Thygesen, Uffe Høgsbro

    2017-01-01

    Many methods exist to assess the fishing status of data-limited stocks; however, little is known about the accuracy or the uncertainty of such assessments. Here we evaluate a new size-based data-limited stock assessment method by applying it to well-assessed, data-rich fish stocks treated as data......-limited. Particular emphasis is put on providing uncertainty estimates of the data-limited assessment. We assess four cod stocks in the North-East Atlantic and compare our estimates of stock status (F/Fmsy) with the official assessments. The estimated stock status of all four cod stocks followed the established stock...... assessments remarkably well and the official assessments fell well within the uncertainty bounds. The estimation of spawning stock biomass followed the same trends as the official assessment, but not the same levels. We conclude that the data-limited assessment method can be used for stock assessment...

  12. Anomalies and the Large N Limit

    International Nuclear Information System (INIS)

    Agarwal, A.; Akant, L.

    2003-01-01

    Operator algebra aspects of the Large N limit of Bosonic vector models are analyzed. It is shown that the Large N limit is a classical theory, and a general method, based on defromation quatization, for calculating the Poisson algebra of dynamical observables in the limiting classical theory is presented. The Poisson algebra of O(N) invariant observables of Bosonic vector models is constructed in this approach, and is shown to be a central extension of the Symplectic Lie algebra. The relation of the central term to anomalies is discussed. A comparision of the classical theories obtained in the Large N limit and that in the small (ℎ/2π) limit is also presented

  13. Self-triggering superconducting fault current limiter

    Science.gov (United States)

    Yuan, Xing [Albany, NY; Tekletsadik, Kasegn [Rexford, NY

    2008-10-21

    A modular and scaleable Matrix Fault Current Limiter (MFCL) that functions as a "variable impedance" device in an electric power network, using components made of superconducting and non-superconducting electrically conductive materials. The matrix fault current limiter comprises a fault current limiter module that includes a superconductor which is electrically coupled in parallel with a trigger coil, wherein the trigger coil is magnetically coupled to the superconductor. The current surge doing a fault within the electrical power network will cause the superconductor to transition to its resistive state and also generate a uniform magnetic field in the trigger coil and simultaneously limit the voltage developed across the superconductor. This results in fast and uniform quenching of the superconductors, significantly reduces the burnout risk associated with non-uniformity often existing within the volume of superconductor materials. The fault current limiter modules may be electrically coupled together to form various "n" (rows).times."m" (columns) matrix configurations.

  14. The limits on trypanosomatid morphological diversity.

    Directory of Open Access Journals (Sweden)

    Richard John Wheeler

    Full Text Available Cell shape is one, often overlooked, way in which protozoan parasites have adapted to a variety of host and vector environments and directional transmissions between these environments. Consequently, different parasite life cycle stages have characteristic morphologies. Trypanosomatid parasites are an excellent example of this in which large morphological variations between species and life cycle stage occur, despite sharing well-conserved cytoskeletal and membranous structures. Here, using previously published reports in the literature of the morphology of 248 isolates of trypanosomatid species from different hosts, we perform a meta-analysis of the occurrence and limits on morphological diversity of different classes of trypanosomatid morphology (trypomastigote, promastigote, etc. in the vertebrate bloodstream and invertebrate gut environments. We identified several limits on cell body length, cell body width and flagellum length diversity which can be interpreted as biomechanical limits on the capacity of the cell to attain particular dimensions. These limits differed for morphologies with and without a laterally attached flagellum which we suggest represent two morphological superclasses, the 'juxtaform' and 'liberform' superclasses. Further limits were identified consistent with a selective pressure from the mechanical properties of the vertebrate bloodstream environment; trypanosomatid size showed limits relative to host erythrocyte dimensions. This is the first comprehensive analysis of the limits of morphological diversity in any protozoan parasite, revealing the morphogenetic constraints and extrinsic selection pressures associated with the full diversity of trypanosomatid morphology.

  15. Concentration and limit behaviors of stationary measures

    Science.gov (United States)

    Huang, Wen; Ji, Min; Liu, Zhenxin; Yi, Yingfei

    2018-04-01

    In this paper, we study limit behaviors of stationary measures of the Fokker-Planck equations associated with a system of ordinary differential equations perturbed by a class of multiplicative noise including additive white noise case. As the noises are vanishing, various results on the invariance and concentration of the limit measures are obtained. In particular, we show that if the noise perturbed systems admit a uniform Lyapunov function, then the stationary measures form a relatively sequentially compact set whose weak∗-limits are invariant measures of the unperturbed system concentrated on its global attractor. In the case that the global attractor contains a strong local attractor, we further show that there exists a family of admissible multiplicative noises with respect to which all limit measures are actually concentrated on the local attractor; and on the contrary, in the presence of a strong local repeller in the global attractor, there exists a family of admissible multiplicative noises with respect to which no limit measure can be concentrated on the local repeller. Moreover, we show that if there is a strongly repelling equilibrium in the global attractor, then limit measures with respect to typical families of multiplicative noises are always concentrated away from the equilibrium. As applications of these results, an example of stochastic Hopf bifurcation and an example with non-decomposable ω-limit sets are provided. Our study is closely related to the problem of noise stability of compact invariant sets and invariant measures of the unperturbed system.

  16. Alignment of the TFTR bumper limiter

    International Nuclear Information System (INIS)

    Barnes, G.W.; Owens, D.K.; Loesser, G.D.; Ulrickson, M.

    1989-01-01

    The TFTR Bumper Limiter (BL) is an axisymmetric toroidal limiter mounted on the inner wall of the vacuum vessel. It subtends 120 degree poloidally and has a surface area of 22 m 2 . The plasma facing surface consists of 1,000 kg of graphite tiles mounted on watercooled Inconel backing plates. During the initial installation in the Spring of 1985, the limiter surface was aligned to the toroidal magnetic field by mechanical and magnetic measurements to an estimated accuracy of ±2 mm. During subsequent operation, especially in the 1988 run period in which 30 MW of Neutral Beam Injection routinely occurred, several tiles at points on the limiter which protruded slightly into the plasma were severely damaged. The damage, cracked and spalled tiles, is believed to be initiated by high energy disruptions and aggravated by normal high power operation. The damage pattern and temperature rise during normal operation are consistent with this interpretation. A vacuum vessel opening to replace the damaged tiles and realign the limiter was required. The bumper limiter was reshaped to be circular to ±0.5 mm at the midplane by means of mechanical measurements in order to better distribute the heat loads and eliminate hot spots. The ±0.5 mm accuracy is determined by the variation in individual tile thickness which is ±0.5 mm. This paper describes the methods used to mechanically align the limiter and presents evidence based on machine operation with plasma that the limiter is reasonably well aligned with the toroidal field. Future work dealing with the alignment of the total limiter to the toroidal field using mechanical and magnetic measurements and the replacement of a subset of the carbon tiles with carbon-carbon composite material is also discussed. 7 refs., 4 figs

  17. Extreme Physics and Informational/Computational Limits

    Energy Technology Data Exchange (ETDEWEB)

    Di Sia, Paolo, E-mail: paolo.disia@univr.it, E-mail: 10alla33@virgilio.it [Department of Computer Science, Faculty of Science, Verona University, Strada Le Grazie 15, I-37134 Verona (Italy) and Faculty of Computer Science, Free University of Bozen, Piazza Domenicani 3, I-39100 Bozen-Bolzano (Italy)

    2011-07-08

    A sector of the current theoretical physics, even called 'extreme physics', deals with topics concerning superstring theories, multiverse, quantum teleportation, negative energy, and more, that only few years ago were considered scientific imaginations or purely speculative physics. Present experimental lines of evidence and implications of cosmological observations seem on the contrary support such theories. These new physical developments lead to informational limits, as the quantity of information, that a physical system can record, and computational limits, resulting from considerations regarding black holes and space-time fluctuations. In this paper I consider important limits for information and computation resulting in particular from string theories and its foundations.

  18. Fractional Diffusion Limit for Collisional Kinetic Equations

    KAUST Repository

    Mellet, Antoine

    2010-08-20

    This paper is devoted to diffusion limits of linear Boltzmann equations. When the equilibrium distribution function is a Maxwellian distribution, it is well known that for an appropriate time scale, the small mean free path limit gives rise to a diffusion equation. In this paper, we consider situations in which the equilibrium distribution function is a heavy-tailed distribution with infinite variance. We then show that for an appropriate time scale, the small mean free path limit gives rise to a fractional diffusion equation. © 2010 Springer-Verlag.

  19. Limiting effects in double EEX beamline

    Science.gov (United States)

    Ha, G.; Power, J. G.; Conde, M.; Doran, D. S.; Gai, W.

    2017-07-01

    The double emittance exchange (EEX) beamline is suggested to overcome the large horizontal emittance and transverse jitter issues associated with the single EEX beamline while preserving its powerful phase-space manipulation capability. However, the double EEX beamline also has potential limitations due to coherent synchrotron radiation (CSR) and transverse jitter. The former limitation arises because double EEX uses twice as many bending magnets as single EEX which means stronger CSR effects degrading the beam quality. The latter limitation arises because a longitudinal jitter in front of the first EEX beamline is converted into a transverse jitter in the middle section (between the EEX beamlines) which can cause beam loss or beam degradation. In this paper, we numerically explore the effects of these two limitations on the emittance and beam transport.

  20. Recognizing limitations in eddy current testing

    International Nuclear Information System (INIS)

    Van Drunen, G.; Cecco, V.S.

    1981-11-01

    This paper addresses known limitations and constraints in eddy current nondestructive testing. Incomplete appreciation for eddy current limitations is believed to have contributed to both under-utilization and misapplication of the technique. Neither situation need arise if known limitations are recognized. Some, such as the skin depth effect, are inherent to electromagnetic test methods and define the role of eddy current testing. Others can be overcome with available technology such as surface probes to find circumferential cracks in tubes and magnetic saturation of ferromagnetic alloys to eliminate permeability effects. The variables responsible for limitations in eddy current testing are discussed and where alternative approaches exist, these are presented. Areas with potential for further research and development are also identified

  1. 17 CFR 150.2 - Position limits.

    Science.gov (United States)

    2010-04-01

    ... basis, options thereon, in excess of the following: Speculative Position Limits Contract Spot month...,000 6,500 New York Board of Trade Cotton No. 2 300 3,500 5,000 Kansas City Board of Trade Hard Winter...

  2. The limitation of radioactive wastes from hospitals

    International Nuclear Information System (INIS)

    Schuurman, B.; IJtsma, D.; Zwigt, A.

    1987-01-01

    Interviews were made with radiation experts working at hospitals about the treatment and limiting of radioactive wastes. The authors conclude that with the aid of hospital personnel a decrease of the volume of radioactive waste is possible. 25 refs

  3. Stable convergence and stable limit theorems

    CERN Document Server

    Häusler, Erich

    2015-01-01

    The authors present a concise but complete exposition of the mathematical theory of stable convergence and give various applications in different areas of probability theory and mathematical statistics to illustrate the usefulness of this concept. Stable convergence holds in many limit theorems of probability theory and statistics – such as the classical central limit theorem – which are usually formulated in terms of convergence in distribution. Originated by Alfred Rényi, the notion of stable convergence is stronger than the classical weak convergence of probability measures. A variety of methods is described which can be used to establish this stronger stable convergence in many limit theorems which were originally formulated only in terms of weak convergence. Naturally, these stronger limit theorems have new and stronger consequences which should not be missed by neglecting the notion of stable convergence. The presentation will be accessible to researchers and advanced students at the master's level...

  4. Space-charge limits in linear accelerators

    International Nuclear Information System (INIS)

    Wangler, T.P.

    1980-12-01

    This report presents equations that allow an approximate evaluation of the limiting beam current for a large class of radio-frequency linear accelerators, which use quadrupole strong focusing. Included are the Alvarez, the Wideroe, and the radio-frequency quadrupole linacs. The limiting-current formulas are presented for both the longitudinal and the transverse degrees of freedom by assuming that the average space-charge force in the beam bunch arises from a uniformly distributed charge within an azimuthally symmetric three-dimensional ellipsoid. The Mathieu equation is obtained as an approximate, but general, form for the transverse equation of motion. The smooth-approximation method is used to obtain a solution and an expression for the transverse current limit. The form of the current-limit formulas for different linac constraints is discussed

  5. Limited flip angle MR imaging: Hemorrhagic applications

    International Nuclear Information System (INIS)

    Drayer, B.P.; Rigamonti, D.; Johnson, P.C.; Spetzler, R.F.; Keller, P.J.; Flom, R.A.; Bird, C.R.; Hodak, J.A.

    1987-01-01

    The authors studied 64 patients with hemorrhagic brain lesions, including vascular malformations (n = 29), hemorrhagic infarctions (n = 9), chronic slit hemorrhagic residua of hypertensive hematoma (n = 10), trauma (n = 8), and gliobastoma multiforme (n = 8). With a 1.5-T MR imaging system, 5-mm sections were obtained at a repetition time of 300 msec (or 500), an echo time of 12.3 msec (or 10 and 40), and a flip angle of 60 0 (or 20 0 ). The limited flip angle study was always extremely sensitive for the detection of hemosiderin. With multiple cavernous angiomas, additional small lesions (in five of 18 patients) were detected only with the limited flip angle technique. The hemosiderin-laden macrophage residua of hemorrhagic infarction and hypertensive hematoma were better seen on limited flip angle images than on T2-weighted spin-echo images. The detection of blood on limited flip angle images permitted the grading of glioma as glioblastoma multiforme

  6. Limited english proficiency accessibility program : demonstration program.

    Science.gov (United States)

    2013-03-01

    In 2006, the Tri-County Metropolitan Transportation District of Oregon (TriMet) secured grant funding from the Federal Transit Administration : (FTA) that enabled the agency to launch a creative and ambitious Limited English Proficiency (LEP) demonst...

  7. Matrix model calculations beyond the spherical limit

    International Nuclear Information System (INIS)

    Ambjoern, J.; Chekhov, L.; Kristjansen, C.F.; Makeenko, Yu.

    1993-01-01

    We propose an improved iterative scheme for calculating higher genus contributions to the multi-loop (or multi-point) correlators and the partition function of the hermitian one matrix model. We present explicit results up to genus two. We develop a version which gives directly the result in the double scaling limit and present explicit results up to genus four. Using the latter version we prove that the hermitian and the complex matrix model are equivalent in the double scaling limit and that in this limit they are both equivalent to the Kontsevich model. We discuss how our results away from the double scaling limit are related to the structure of moduli space. (orig.)

  8. 48 CFR 46.705 - Limitations.

    Science.gov (United States)

    2010-10-01

    ... QUALITY ASSURANCE Warranties 46.705 Limitations. (a) Except for the warranties in the clauses at 52.246-3, Inspection of Supplies—Cost-Reimbursement, and 52.246-8, Inspection of Research and Development—Cost...

  9. Limit Interchange and L'Hopital's Rule

    Science.gov (United States)

    Ecker, Michael W.

    2011-01-01

    Conventional application of these two calculus staples is stretched here, somewhat recreationally, but also to raise solid questions about the role of limit interchange in analysis--without, however, delving any deeper than first-year Calculus.

  10. The classical limit of W-algebras

    International Nuclear Information System (INIS)

    Figueroa-O'Farrill, J.M.; Ramos, E.

    1992-01-01

    We define and compute explicitly the classical limit of the realizations of W n appearing as hamiltonian structures of generalized KdV hierarchies. The classical limit is obtained by taking the commutative limit of the ring of pseudodifferential operators. These algebras - denoted w n - have free field realizations in which the generators are given by the elementary symmetric polynomials in the free fields. We compute the algebras explicitly and we show that they are all reductions of a new algebra w KP , which is proposed as the universal classical W-algebra for the w n series. As a deformation of this algebra we also obtain w 1+∞ , the classical limit of W 1+∞ . (orig.)

  11. Beam limiter for thermonuclear fusion devices

    International Nuclear Information System (INIS)

    Kaminsky, M.S.

    1976-01-01

    A beam limiter circumscribes the interior surface of a vacuum vessel to inhibit collisions of contained plasma and the vessel walls. The cross section of the material making up the limiter has a flatsided or slightly concave portion of increased width towards the plasma and portions of decreased width towards the interior surface of the vessel. This configuration is designed to prevent a major fraction of the material sputtered, vaporized and blistered from the limiter from reaching the plasma. It also allows adequate heat transfer from the wider to the narrower portions. The preferred materials for the beam limiter are solids of sintered, particulate materials of low atomic number with low vapor pressure and low sputtering and blistering yields. 7 claims, 3 figures

  12. Limitations of science and adaptive management

    OpenAIRE

    Narasimhan, T.N.

    2001-01-01

    Adaptive management consists in patterning human sustenance within the constraints of Earth and biological systems whose behavior is inherently uncertain and difficult to control. For successful adaptive management, a mind-set recognizing the limitations of science is needed.

  13. Limitations of science and adaptive management

    Energy Technology Data Exchange (ETDEWEB)

    Narasimhan, T.N.

    2001-12-20

    Adaptive management consists in patterning human sustenancewithin the constraints of Earth and biological systems whose behavior isinherently uncertain and difficult to control. For successful adaptivemanagement, a mind-set recognizing the limitations of science isneeded.

  14. Health Outcomes Survey - Limited Data Set

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Medicare Health Outcomes Survey (HOS) limited data sets (LDS) are comprised of the entire national sample for a given 2-year cohort (including both respondents...

  15. Rural variable speed limits : phase II.

    Science.gov (United States)

    2012-05-01

    The Wyoming Department of Transportation (WYDOT) installed its first variable speed limit (VSL) corridor along : Interstate 80 in the Elk Mountain Corridor in the Spring of 2009 in an effort to improve safety and reduce road closures, : particularly ...

  16. Zero noise limits using local times

    OpenAIRE

    Trevisan, Dario

    2013-01-01

    We consider a well-known family of SDEs with irregular drifts and the correspondent zero noise limits. Using (mollified) local times, we show which trajectories are selected. The approach is completely probabilistic and relies on elementary stochastic calculus only.

  17. 7 CFR 3560.612 - Loan limits.

    Science.gov (United States)

    2010-01-01

    ... DIRECT MULTI-FAMILY HOUSING LOANS AND GRANTS On-Farm Labor Housing § 3560.612 Loan limits. The maximum loan amount will be 100 percent of the allowable total development costs of on-farm labor housing and...

  18. MHD stability, operational limits and disruptions

    International Nuclear Information System (INIS)

    1999-01-01

    The present physics understandings of magnetohydrodynamic (MHD) stability of tokamak plasmas, the threshold conditions for onset of MHD instability, and the resulting operational limits on attainable plasma pressure (beta limit) and density (density limit), and the consequences of plasma disruption and disruption related effects are reviewed and assessed in the context of their application to a future DT burning reactor prototype tokamak experiment such as ITER. The principal considerations covered within the MHD stability and beta limit assessments are (i) magnetostatic equilibrium, ideal MHD stability and the resulting ideal MHD beta limit; (ii) sawtooth oscillations and the coupling of sawtooth activity to other types of MHD instability; (iii) neoclassical island resistive tearing modes and the corresponding limits on beta and energy confinement; (iv) wall stabilization of ideal MHD instabilities and resistive wall instabilities; (v) mode locking effects of non-axisymmetric error fields; (vi) edge localized MHD instabilities (ELMs, etc.); and (vii) MHD instabilities and beta/pressure gradient limits in plasmas with actively modified current and magnetic shear profiles. The principal considerations covered within the density limit assessments are (i) empirical density limits; (ii) edge power balance/radiative density limits in ohmic and L-mode plasmas; and (iii) edge parameter related density limits in H-mode plasmas. The principal considerations covered in the disruption assessments are (i) disruption causes, frequency and MHD instability onset; (ii) disruption thermal and current quench characteristics; (iii) vertical instabilities (VDEs), both before and after disruption, and plasma and in-vessel halo currents; (iv) after disruption runaway electron formation, confinement and loss; (v) fast plasma shutdown (rapid externally initiated dissipation of plasma thermal and magnetic energies); (vi) means for disruption avoidance and disruption effect mitigation; and

  19. Inviscid incompressible limits on expanding domains

    Czech Academy of Sciences Publication Activity Database

    Feireisl, Eduard; Nečasová, Šárka; Sun, Y.

    2014-01-01

    Roč. 27, č. 10 (2014), s. 2465-2477 ISSN 0951-7715 R&D Projects: GA ČR GA13-00522S Institutional support: RVO:67985840 Keywords : compressible Navier-Stokes system * large domain * inviscid limit * incompressible limit Subject RIV: BA - General Mathematics Impact factor: 1.208, year: 2014 http://iopscience.iop.org/0951-7715/27/10/2465/

  20. 50 CFR 622.37 - Size limits.

    Science.gov (United States)

    2010-10-01

    ...), TL. (iv) Red snapper -16 inches (40.6 cm), TL, for a fish taken by a person subject to the bag limit... to the bag limit specified in § 622.39(b)(1)(ii)—22 inches (55.9 cm), TL. (iv) Red grouper—(A) For a... inches (30.5 cm), TL. (iii) Blackfin, cubera, dog, gray, mahogany, queen, silk, and yellowtail snappers...

  1. Gulf of Mexico mud toxicity limitations

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, H.E.; Beardmore, D.H. (Phillips Petroleum Co., Bartlesville, OK (USA)); Stewart, W.S. (Drilling Specialties Co. (US))

    1989-10-01

    Because of the Environmental Protection Agency's recent toxicity limits on drilling mud discharges for offshore Gulf of Mexico, Phillips Petroleum conducted a mud toxicity study based on both field and lab tests. The study, discussed in this article, found the polyanionic cellulose-sulfomethylated quebracho-chrome lignosulfonate mud Phillips had been using would comfortably pass the toxicity limitations. The study also found barite and thinners were of low toxicity, and hydrocarbons and surfactants were highly toxic.

  2. Light Obscuration Particle Counter Fuel Contamination Limits

    Science.gov (United States)

    2015-10-08

    limits were derived from 1.0 mg/L concentration levels for ISO 12103-1 A1Ultrafine and ISO 12103-1 A2 Fine test dusts , and down to a 5 ppm free water...AND USE OF LIQUID FUELS Charleston, South Carolina USA 4-8 October 2015 LIGHT OBSCURATION PARTICLE COUNTER FUEL CONTAMINATION LIMITS Joel... contamination . Based on this work the Department of Defense Tri-Service Petroleum, Oil and Lubricants Technical Steering Committee has recommended

  3. Limits and signatures of relativistic spaceflight

    Science.gov (United States)

    Yurtsever, Ulvi; Wilkinson, Steven

    2018-01-01

    While special relativity imposes an absolute speed limit at the speed of light, our Universe is not empty Minkowski spacetime. The constituents that fill the interstellar/intergalactic vacuum, including the cosmic microwave background photons, impose a lower speed limit on any object travelling at relativistic velocities. Scattering of cosmic microwave photons from an ultra-relativistic object may create radiation with a characteristic signature allowing the detection of such objects at large distances.

  4. Pressure limits of an axisymmetric torus

    International Nuclear Information System (INIS)

    Yoshikawa, S.

    1986-03-01

    In order to clarify the pressure limit of a toroidal plasma equilibrium in a three-dimensional geometry, an azimuthally symmetric toroidal plasma was considered. In a tokamak-like plasma, the net toroidal current is necessary for a finite β plasma equilibrium. If external conductors are used to provide the rotational transform, iota, the plasma pressure is limited to β = (iota/2π) 2 /2A, where A is the aspect ratio

  5. Compression limits in cascaded quadratic soliton compression

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw

    2008-01-01

    Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency.......Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency....

  6. Window in the dark matter exclusion limits

    International Nuclear Information System (INIS)

    Zaharijas, Gabrijela; Farrar, Glennys R.

    2005-01-01

    We consider the cross section limits for light dark matter cadnidates (m=0.4 to 10 GeV). We calculate the interaction of dark matter in the crust above underground dark matter detectors and find that in the intermediate cross section range, the energy loss of dark matter is sufficient to fall below the energy threshold of current underground experiments. This implies the existence of a window in the dark matter exclusion limits in the micro-barn range

  7. Mass limits for the muon neutrino

    International Nuclear Information System (INIS)

    Hoffman, C.M.; Sandberg, V.D.

    1982-01-01

    The possibility of improving the present limit on the mass of the muon neutrino is discussed. It is found that decays of muons and pions are not useful means to significantly improve this limit. On the other hand, the decays K 0 /sub L/ → π/sup +-/μ/sup -+/nu/sub μ/ and K + → π 0 μ + nu/sub μ/ appear to be quite promising. Possible experiments are discussed

  8. A lattice hierarchy and its continuous limits

    International Nuclear Information System (INIS)

    Fan Engui

    2008-01-01

    By introducing a discrete spectral problem, we derive a lattice hierarchy which is integrable in Liouville's sense and possesses a multi-Hamiltonian structure. It is show that the discrete spectral problem converges to the well-known AKNS spectral problem under a certain continuous limit. In particular, we construct a sequence of equations in the lattice hierarchy which approximates the AKNS hierarchy as a continuous limit

  9. Operating limits Hanford Production Reactors. Revision 2

    Energy Technology Data Exchange (ETDEWEB)

    Owsley, G.F. [comp.

    1963-05-20

    This report is applicable to the eight operating production reactors, B, C, D, DR, F, H, KE, and KW. It covers the following: operating parameter limitations; reactivity limitations; control and safety systems; reactor fuel loading; coolant requirements with irradiated fuel in reactor; reactor confinement; test facilities; code compliance; safety instrumentation and set points; and control criteria. Also discussed are administrative procedures for process control, training, audits and inspection, and reports and records.

  10. Loop quantization as a continuum limit

    International Nuclear Information System (INIS)

    Manrique, Elisa; Oeckl, Robert; Weber, Axel; Zapata, Jose A

    2006-01-01

    We present an implementation of Wilson's renormalization group and a continuum limit tailored for loop quantization. The dynamics of loop-quantized theories is constructed as a continuum limit of the dynamics of effective theories. After presenting the general formalism we show as a first explicit example the 2D Ising field theory, an interacting relativistic quantum field theory with local degrees of freedom quantized by loop quantization techniques

  11. Limiting values for radioactive materials in food

    International Nuclear Information System (INIS)

    Steiner, Martin

    2014-01-01

    The contribution describes the fundamentals of radiation protection: LNT (linear, no threshold) hypotheses, ALARA (a slow as reasonably achievable), limiting values. Using the example the nuclear accident in Chernobyl the differences in contamination development in different foodstuffs in Germany is demonstrated including recommended limiting values and the radiation exposures after 30 years due to consumption of contaminated food. The natural radioactivity is about 0.3 mSv/year.

  12. Survey of beam-beam limitations

    International Nuclear Information System (INIS)

    Courant, E.; Cornacchia, M.; Donald, M.M.R.; Evans, L.R.; Tazzari, S.; Wilson, E.J.N.

    1979-01-01

    The effect of beam-beam interaction is known to limit the luminosity of electron-positron storage rings and will, no doubt, limit the proton-antiproton collision scheme for the SPS. While theorists are struggling to explain this phenomenon it is more instructive to list their failures than their rather limited successes, in the hope that experiments may emerge which will direct their endeavors. The search for a description of a nonlinear system as it approaches the limit in which ordered motion breaks down, is the nub of the problem. It has engaged many fine mathematical intellects for decades and will no doubt continue to do so long after ISABELLE, the p antip and LEP are past achievements. Empirical scaling laws are emerging which relate electron machines to each other but their extrapolation to proton machines remain a very speculative exercise. Experimental data on proton limits is confined to one machine, the ISR, which does not normally suffer the beam-beam effect and where it must be artificially induced or simulated. This machine is also very different in important ways from the p antip collider. The gloomy picture which has emerged recently is that the fixed limits which were conventionally assumed for proton and electron machines can only be said to be valid for the machines which engendered them - the best guess that could be made at the time. They are very difficult to extrapolate to other sets of parameters

  13. Risk based limits for Operational Safety Requirements

    Energy Technology Data Exchange (ETDEWEB)

    Cappucci, A.J. Jr.

    1993-01-18

    OSR limits are designed to protect the assumptions made in the facility safety analysis in order to preserve the safety envelope during facility operation. Normally, limits are set based on ``worst case conditions`` without regard to the likelihood (frequency) of a credible event occurring. In special cases where the accident analyses are based on ``time at risk`` arguments, it may be desirable to control the time at which the facility is at risk. A methodology has been developed to use OSR limits to control the source terms and the times these source terms would be available, thus controlling the acceptable risk to a nuclear process facility. The methodology defines a new term ``gram-days``. This term represents the area under a source term (inventory) vs time curve which represents the risk to the facility. Using the concept of gram-days (normalized to one year) allows the use of an accounting scheme to control the risk under the inventory vs time curve. The methodology results in at least three OSR limits: (1) control of the maximum inventory or source term, (2) control of the maximum gram-days for the period based on a source term weighted average, and (3) control of the maximum gram-days at the individual source term levels. Basing OSR limits on risk based safety analysis is feasible, and a basis for development of risk based limits is defensible. However, monitoring inventories and the frequencies required to maintain facility operation within the safety envelope may be complex and time consuming.

  14. Risk based limits for Operational Safety Requirements

    International Nuclear Information System (INIS)

    Cappucci, A.J. Jr.

    1993-01-01

    OSR limits are designed to protect the assumptions made in the facility safety analysis in order to preserve the safety envelope during facility operation. Normally, limits are set based on ''worst case conditions'' without regard to the likelihood (frequency) of a credible event occurring. In special cases where the accident analyses are based on ''time at risk'' arguments, it may be desirable to control the time at which the facility is at risk. A methodology has been developed to use OSR limits to control the source terms and the times these source terms would be available, thus controlling the acceptable risk to a nuclear process facility. The methodology defines a new term ''gram-days''. This term represents the area under a source term (inventory) vs time curve which represents the risk to the facility. Using the concept of gram-days (normalized to one year) allows the use of an accounting scheme to control the risk under the inventory vs time curve. The methodology results in at least three OSR limits: (1) control of the maximum inventory or source term, (2) control of the maximum gram-days for the period based on a source term weighted average, and (3) control of the maximum gram-days at the individual source term levels. Basing OSR limits on risk based safety analysis is feasible, and a basis for development of risk based limits is defensible. However, monitoring inventories and the frequencies required to maintain facility operation within the safety envelope may be complex and time consuming

  15. Photonic limiters with enhanced dynamic range

    Science.gov (United States)

    Kononchuk, Rodion; Limberopoulos, Nicholaos; Anisimov, Igor; Vitebskiy, Ilya; Chabanov, Andrey

    2018-02-01

    Optical limiters transmit low intensity input light while blocking input light with the intensity exceeding certain limiting threshold. Conventional passive limiters utilize nonlinear optical materials, which are transparent at low light intensity and turn absorptive at high intensity. Strong nonlinear absorption, though, can result in over- heating and destruction of the limiter. Another problem is that the limiting threshold provided by the available optical material with nonlinear absorption is too high for many applications. To address the above problems, the nonlinear material can be incorporated in a photonic structure with engineered dispersion. At low intensity, the photonic structure can display resonant transmission via localized mode(s), while at high intensity the resonant transmission can disappear, and the entire stack can become highly re ective (not absorptive) within a broad frequency range. In the proposed design, the transition from the resonant transmission at low intensity to nearly total re ectivity at high intensity does not rely on nonlinear absorption; instead, it requires only a modest change in the refractive index of the nonlinear material. The latter implies a dramatic increase in the dynamic range of the limiter. The main idea is to eliminate the high-intensity resonant transmission by decoupling the localized (resonant) modes from the input light, rather than suppressing those modes using nonlinear absorption. Similar approach can be used for light modulation and switching.

  16. Environmental radiation standards and risk limitation

    International Nuclear Information System (INIS)

    Kocher, D.C.

    1987-01-01

    The Environmental Protection Agency and Nuclear Regulatory Commission have established environmental radiation standards for specific practices which correspond to limits on risk to the public that vary by several orders of magnitude and often are much less than radiation risks that are essentially unregulated, e.g., risks from radon in homes. This paper discusses a proposed framework for environmental radiation standards that would improve the correspondence with limitation of risk. This framework includes the use of limits on annual effective dose equivalent averaged over a lifetime, rather than limits on dose equivalent to whole body or any organ for each year of exposure, and consideration of exposures of younger age groups as well as adults; limits on annual effective dose equivalent averaged over a lifetime no lower than 0.25 mSv (25 mrem) per practice; maintenance of all exposures as low as reasonably achievable (ALARA); and establishment of a generally applicable de minimis dose for public exposures. Implications of the proposed regulatory framework for the current system of standards for limiting public exposures are discussed. 20 refs

  17. Determination and Interpretation of Characteristic Limits for Radioactivity Measurements: Decision Threshhold, Detection Limit and Limits of the Confidence Interval

    International Nuclear Information System (INIS)

    2017-01-01

    Since 2004, the environment programme of the IAEA has included activities aimed at developing a set of procedures for analytical measurements of radionuclides in food and the environment. Reliable, comparable and fit for purpose results are essential for any analytical measurement. Guidelines and national and international standards for laboratory practices to fulfil quality assurance requirements are extremely important when performing such measurements. The guidelines and standards should be comprehensive, clearly formulated and readily available to both the analyst and the customer. ISO 11929:2010 is the international standard on the determination of the characteristic limits (decision threshold, detection limit and limits of the confidence interval) for measuring ionizing radiation. For nuclear analytical laboratories involved in the measurement of radioactivity in food and the environment, robust determination of the characteristic limits of radioanalytical techniques is essential with regard to national and international regulations on permitted levels of radioactivity. However, characteristic limits defined in ISO 11929:2010 are complex, and the correct application of the standard in laboratories requires a full understanding of various concepts. This publication provides additional information to Member States in the understanding of the terminology, definitions and concepts in ISO 11929:2010, thus facilitating its implementation in Member State laboratories.

  18. 24 CFR 248.127 - Limitations on action pursuant to Federal cost limit.

    Science.gov (United States)

    2010-04-01

    ... cost limit. (b) Transfer of the project. With respect to owners who seek to transfer the project— (1) If the transfer preservation rent does not exceed the Federal cost limit, or if the transfer preservation rent exceeds the Federal cost limit and the owner is willing to transfer the project at a price...

  19. Communicative action as a way of annihilating the human limits. Human limits in transhumanism

    OpenAIRE

    TEREC-VLAD LOREDANA

    2015-01-01

    In this paper we aim to analyse the biological limits of the human individual and the limits of knowledge, as well as the way they can be overcome Transhumanism can be defined as: the idea that humans can use reason in order to transcend the limit of the human condition within transhumanism

  20. Threshold limit values, permissible exposure limits, and feasibility: The bases for exposure limits in the United States

    International Nuclear Information System (INIS)

    Rappaport, S.M.

    1993-01-01

    The development of exposure limits in the United States has always relied heavily upon the threshold limit values (TLVs) developed by the American Conference of Governmental Industrial Hygienists (ACGIH). In fact, the TLVs were adopted as official exposure limits by the Occupational Safety and Health Administration (OSHA) in 1972 and 1989. Given the continuing importance of the ACGIH limits, this paper compares the basis of the TLVs with that employed by OSHA de novo in its 12 new permissible exposure limits (PELs). Using benzene as an example, it is shown that OSHA's new PELs have been established following a rigorous assessment of the inherent risks and the feasibility of instituting the limit. The TLVs, on the other hand, have been developed by ad hoc procedures and appear to have traditionally reflected levels thought to be achievable at the time. However, this might be changing. Analysis of the historical reductions of TLVs, for 27 substances on the 1991-1992 list of intended changes, indicates smaller reductions in the past (median reduction of 2.0-2.5-fold between 1946 and 1988) compared to those currently being observed (median reduction of 7.5-fold between 1989 and 1991). Further analysis suggests a more aggressive policy of the ACGIH regarding TLVs for carcinogens but not for substances that produce effects other than cancer. Regardless of whether the basis of the TLVs has changed recently, it would take a relatively long time for the impact of any change to be felt, since the median age of the 1991-1992 TLVs is 16.5 years, and 75% of these limits are more than 10 years old. The implications of OSHA's continued reliance on the TLVs as a means of updating its PELs are discussed, and four alternatives are presented to the ACGIH regarding the future of its activities related to exposure limits. It is concluded that new mechanisms are needed for OSHA to update its PELs in a timely fashion so that the TLVs will not be adopted by default in the future