WorldWideScience

Sample records for pierce instability

  1. Face piercing (body art: choosing pleasure vs. possible pain and posture instability

    Directory of Open Access Journals (Sweden)

    Eric eMatheron

    2011-09-01

    Full Text Available Piercings (body art, i.e. with jewelry are more and more widespread. They can induce various complications such as infections, allergies, headaches, and various skin, cartilage, or dental problems which will lead to economic effects on health-care systems. We draw attention to other possible side effects resulting from face piercing complications such as eye misalignment, decreased postural control efficiency, and nonspecific chronic back pain. We found that the origin was pierced jewelry on the face. Removing the jewelry restored eye alignment, improved postural control, and alleviated back pain in a lasting way. This observation is important for health; further investigations would be of interest.

  2. Body Piercing

    Science.gov (United States)

    ... most common body piercing. Other common places to pierce include the eyebrow, nose, tongue, lip, belly button, nipples, and genitals. Some people also pierce their ear cartilage (the hard part of the ...

  3. Piercing and Tattoos

    Science.gov (United States)

    Piercings and tattoos are body decorations that go back to ancient times. Body piercing involves making a hole in the skin ... can be in other parts of the body. Tattoos are designs on the skin made with needles ...

  4. Pierce Lumber, Inc.

    Science.gov (United States)

    The EPA is providing notice of a proposed Administrative Penalty Assessment against Pierce Lumber, Inc. (“Respondent”), located at 1629 13th Street, Belle Plaine, IA for alleged violations of its National Pollutant Discharge Elimination System permit (perm

  5. Tatuajes y "piercing" Tattoos and piercing

    Directory of Open Access Journals (Sweden)

    L E Valle

    2006-03-01

    Full Text Available A pesar de estar en el siglo XXI se ha retomado el lenguaje con códigos de comunicación arcaicos. Los jóvenes forman su identidad mediante la interacción con sus pares y los tatuajes y "piercing" tienen sus propios códigos, que son interpretados por el grupo que los lleva. Actualmente los tatuajes y los "piercing" encuentran su lugar predominante en la población adolescente, donde se han reinstalado por ser "moda" y generalmente se aceptan por estar generalizados. Asimismo los observamos en poblaciones marginales: de drogadictos y carcelarias. Realizarse un tatuaje y/o "piercing" implica ciertos riesgos, entre los que podemos mencionar la transmisión de infecciones que pueden ser localizadas en las zonas del tatuaje y/o "piercing"; y/o generalizadas como las virósicas algunas de las cuales conllevan riesgos de salud como el virus del HIV, de las hepatitis A,B,C. Pueden observarse también reacciones alérgicas, de hipersensibilidad, liquenoides, granulomatosas y varias como cicatrices hipertróficas y queloides; asimismo desencadenar un primer episodio de psoriasis, lupus, etc. Dentro de las recomendaciones para informar a la población deberíamos incluir: que las regiones del cuerpo más riesgosas para la realización de los mismos (que debieran evitarse son aquellas que asientan en cabeza (incluyendo boca, nariz, cuello y órganos genitales. También es importante tener la vacunación antitetánica actualizada, considerar las condiciones de higiene del local donde se va a asistir y el tipo de material a utilizar, debiendo ser en lo posible material descartable. Los cuidados durante los primeros días post práctica son: mantener la zona limpia y seca, baños cortos, secarse sin frotado y no exponerse al sol por tres o cuatro meses. Asimismo es aconsejable ante cualquier reacción concurrir a la consulta profesional.In spite of being in the XXI century, several archaic codes of communication language have been restablished. Young

  6. Pierce Patriarch "Prince of Quacks"

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This article provides brief biographies for Dr. Valentine Mott Pierce and his father, Dr. Ray Vaughn Pierce. Dr. R.V. Pierce has been described as the “uberquack,”...

  7. Post-piercing perichondritis.

    Science.gov (United States)

    Fernandez, André de Paula; Castro Neto, Ivan de; Anias, Christiane Ribeiro; Pinto, Patrícia Ciminelli Linhares; Castro, Jair de Carvalho E; Carpes, Arturo Frick

    2008-01-01

    Piercing has become more and more popular among adolescents. The procedure is generally performed by unqualified professionals and carries its risk. Non-sterilized material or inappropiate hygiene increases the possibility of perichondritis and celulitis. The disease is characterized by erythema of the auricula pinna, unbearable pain and fever. Left untreated, the condition progresses with edema along the auricula and abscess formation that may result in ischemic necrosis and a cauliflower anesthetic deformation. The most common bacteria is Pseudomonas aeruginosa. In cases with abscesses, drainage is necessary along with antibiotic therapy guided by cultures and antibiogram. The aim of this case report was to review the past 10 years of published papers dealing with anatomical aspects of the auricular pinna, the history of piercing and its most common complications. A case report of perichondritis after 'high' ear piercing that required surgical treatment and that progressed with no esthetic loss. Theoretical and practical experience based on a review and a report of a case that progressed satisfactorily. The increased incidence of perichondritis in adolescents should require more elaborated primary prevention measures.

  8. Diagrammer hos Pierce og Deleuze

    DEFF Research Database (Denmark)

    Busk, Malene

    2006-01-01

    Artiklen omhandler to forskellige begreber om diagrammet, nemlig Pierces og Deleuzes. De definerer udfra to meget forskellige udgangspukter begge diagrammet som kreativt redskab......Artiklen omhandler to forskellige begreber om diagrammet, nemlig Pierces og Deleuzes. De definerer udfra to meget forskellige udgangspukter begge diagrammet som kreativt redskab...

  9. Contact hypersensitivity after tongue piercing

    Directory of Open Access Journals (Sweden)

    Ananta Herachakri P

    2010-09-01

    Full Text Available Background: Recently tongue piercing has become increasingly popular in the society. Several case reports have presented various complications of tongue piercing. However, there is no scientific evidence about contact hypersensitivity to tongue piercing. Purpose: The aim of this study was to investigate the contact hypersensitivity after using tongue piercing. Methods: Nineteen male Rattus norvegicus were divided into three groups: group A treated with vaseline on the back and dorsum tongue (control group, group B (I treated with HgCl2 10% cream on the tongue dorsum, group B (II treated with tongue piercing for 10 days and group C with HgCl 2 10% cream on the back, ear lobe, and tongue, then re-exposure with same materials on ear, back and tongue for 24 and 48 hours. Before and after 24 and 48 hours applications, ear width was measured with sliding caliper. At the end of treatments, the rats were sacrificed. All tissue specimens were made for Hematoylin Eosine (H&E staining examination. The number of mononuclear cells was counted under light microscope Data was analyzed with One-Way ANOVA followed by LSD (p<0.05. Results: The result of this study showed that there were a significant difference of the thickness of ear lobe and the number of mononuclear cells (lymphocyte and monocyte among all groups. Conclusion: It is concluded that tongue piercing induce contact hypersensitivity.Latar belakang: Saat ini pemakaian tongue piercing sangat popular di masyarakat. Beberapa laporan kasus menunjukkan bahwa tongue piercing menimbulkan beberapa komplikasi. Namun, belum ada bukti ilmiah mengenai reaksi hipesensitivitas tongue piercing. Tujuan: Untuk mengetahui reaksi hipersensitivitas setelah menggunakan tongue piercing. Metode: Sembilan belas tikus jantan Rattus novergicus yang dibagi dalam tiga kemlompok yaitu: grup A diberi perlakuan dengan vaselin pada punggung dan dorsum lidah, grup B (I diberi perlakuan dengan krim HgCl2 10% pada dorsum lidah dan B

  10. How Dr. Pierce Promoted Himself

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This article is about Dr. Raymond V Pierce who owned St. Vincent Island before it became a refuge. The doctor painted advertisements for his famous “Woman’s Tonic”...

  11. [Piercing: health education or medicalization?].

    Science.gov (United States)

    Meningaud, J P; Moutel, G; Hervé, C

    2000-06-10

    In Europe, the piercing mode has naturally been associated with specific complications raising an important public health problem. The debate on the role physicians should play requires a careful analysis of the ethical issues involved. Specifically, should the piercing be done in a medical setting? This question is raised because, when performed under ideal conditions, the act of piercing requires a certain degree of medical competency: history taking, asepsia, technical procedure (hemostasis), anesthesia.... However, mandatory medicalization would not, in our opinion, appear to be desirable since we are dealing with a social rite which lies outside the domain of specific medical care. Nevertheless, although we do not advocate systematic medicalization, we do believe that medicine should play a role, in terms of public health, in this emerging practice. We discuss the modalities of a health education dialogue which could be established with professional practicing piercing.

  12. Pericondrite pós-piercing Post-piercing perichondritis

    Directory of Open Access Journals (Sweden)

    André de Paula Fernandez

    2008-12-01

    Full Text Available O uso de piercing tem se tornado uma prática muito freqüente entre os jovens. O procedimento na maioria vezes realizado por profissionais não-qualificados não é isento de riscos. O manuseio de material contaminado ou a higiene imprópria predispõem à pericondrite e à celulite. A pericondrite caracteriza-se pelo eritema do pavilhão auricular, dor intensa e febre. Sem tratamento, desenvolve-se um edema generalizado do pavilhão com formação de abscesso subpericondrial, podendo evoluir para necrose isquêmica da cartilagem e a temível deformidade estética conhecida como "orelha em couve flor". O agente responsável mais encontrado é o Pseudomonas aeruginosa. No estágio inicial da doença o tratamento pode ser feito com antibióticos de amplo espectro. Nos casos em que o abscesso está presente, a incisão e drenagem cirúrgica são obrigatórios acompanhado de antibioticoterapia guiado pela cultura e antibiograma. OBJETIVO: O objetivo deste relato de caso é realizar uma revisão bibliográfica dos últimos 10 anos abordando os aspectos anatômicos do pavilhão auricular, a história do uso de piercing e suas mais conhecidas complicações. MÉTODO: Relato de um caso de pericondrite pós-piercing transcartilaginoso onde houve a necessidade de tratamento cirúrgico com praticamente nenhuma deformidade estética. RESULTADO: Aquisição de experiência teórico-prática através de revisão bibliográfica e relato de um caso de evolução favorável para a paciente. CONCLUSÃO: Incidência crescente das complicações de pericondrites na população jovem deve levar à prevenção primária mais elaborada.Piercing has become more and more popular among adolescents. The procedure is generally performed by unqualified professionals and carries its risk. Non-sterilized material or inappropiate hygiene increases the possibility of perichondritis and celulitis. The disease is characterized by erythema of the auricula pinna, unbearable pain

  13. Piercings en cabeza y cuello

    OpenAIRE

    2014-01-01

    Los piercings corporales son una práctica habitual en la sociedad actual, y consisten en la perforación de un tejido para insertar un aro u otro elemento ornamental. Este procedimiento implica la creación de una puerta de entrada cutánea o mucosa que puede permitir el ingreso de microorganismos, además de la posible formación de cicatrices anómalas. Asimismo, el aro puede predisponer a otras complicaciones como reacciones de hipersensibilidad, desplazamientos o aspiración. Debido a esta ampli...

  14. Piercing and Tattoos - Multiple Languages: MedlinePlus

    Science.gov (United States)

    ... Home → Multiple Languages → All Health Topics → Piercing and Tattoos URL of this page: https://medlineplus.gov/languages/ ... XYZ List of All Topics All Piercing and Tattoos - Multiple Languages To use the sharing features on ...

  15. Rules of Appointment at Franklin Pierce College.

    Science.gov (United States)

    Franklyn Pierce Coll., Rindge, NH.

    This memorandum sets forth the regulations and procedures affecting appointments to the instructional faculty of Franklin Pierce College. Part A: General Provisions, includes information on faculty ranks, the procedure of appointment, the regular review, and normal retirement. Part B deals with the terms and conditions of appointment, including…

  16. Modeling and Optimization for Piercing Energy Consumption

    Institute of Scientific and Technical Information of China (English)

    XIAO Dong; PAN Xiao-li; YUAN Yong; MAO Zhi-zhong; WANG Fu-li

    2009-01-01

    Energy consumption is an important quality index in the production of seamless tubes. The complex factors affecting energy consumption make it difficult to build its mechanism model, and optimization is also very difficult, if not impossible. The piercing process was divided into three parts based on the production process, and an energy consumption prediction model was proposed based on the step mean value staged multiway partial least square meth-od. On the basis of the batch process prediction model, a genetic algorithm was adopted to calculate the optimum mean value of each process parameter and the minimum piercing energy consumption. Simulation proves that the op-timization method based on the energy consumption prediction model can obtain the optimum process parameters ef-fectively and also provide reliable evidences for practical production.

  17. Tongue piercing by a Yogi: QEEG observations.

    Science.gov (United States)

    Peper, Erik; Wilson, Vietta E; Gunkelman, Jay; Kawakami, Mitsumasa; Sata, Misa; Barton, William; Johnston, James

    2006-12-01

    : This study reports on the QEEG observations recorded from a yogi during tongue piercing in which he demonstrated voluntary pain control. The QEEG was recorded with a Lexicor 1620 from 19 sites with appropriate controls for impedence and artifacts. A neurologist read the data for abnormalities and the QEEG was analyzed by mapping, single and multiple hertz bins, coherence, and statistical comparisons with a normative database. The session included a meditation baseline and tongue piercing. During the meditative baseline period the yogi's QEEG maps suggesting that he was able to lower his brain activity to a resting state. This state showed a predominance of slow wave potentials (delta) during piercing and suggested that the yogi induced a state that may be similar to those found when individuals are under analgesia. Further research should be conducted with a group of individuals who demonstrate exceptional self-regulation to determine the underlying mechanisms, and whether the skills can be used to teach others how to manage pain.

  18. Self-piercing riveting properties, processes and applications

    CERN Document Server

    Chrysanthou, A

    2014-01-01

    Due to its speed, low energy requirements, and the fact that it does not require a pre-drilled hole, the technique of self-piercing riveting (SPR) has been increasingly adopted by many industries as a high-speed mechanical fastening technique for the joining of sheet material components. Self-piercing riveting comprehensively reviews the process, equipment, and corrosion behaviour of self-piercing riveting, and also describes the process of evaluation and modelling of strength of self-piercing riveted joints, quality control methods and non-destructive testing.Part one provides an exte

  19. Obituary: A. Keith Pierce, 1918 - 2005

    Science.gov (United States)

    Livingston, William Charles

    2006-12-01

    A. Keith Pierce was a solar astronomer who will be remembered for bringing the physics lab to the telescope and for his design of the world's largest solar telescope, the 1.5-meter McMath Telescope on Kitt Peak in Arizona. Born in Lincoln, Nebraska, he died of cancer in Tucson on 11 March 2005. He was eighty-six. His father, Tracy Pierce, had gone to graduate school in Berkeley, California, with a major in mathematics and a minor in astronomy. Fellow students of his class included Seth Nicholson and Donald Shane, people who were later to influence young Keith's life. Tracy Pierce received an appointment as an instructor, later Professor, of mathematics at the University of Nebraska in Lincoln. In his spare time dad Tracy became something of a telescope nut, following "the bible" —Albert Ingall's A.T.M (Amateur Telescope Making). His enthusiasm rubbed off on his son. Seth Nicholson, who became a famous Mt. Wilson Observatory astronomer, and Donald Shane from Berkeley, both stayed at the Pierce home while on their Sigma Xi lecture tours. After two years at Lincoln, followed by two more at Berkeley, Keith had earned his bachelor's degree in astronomy. During World War II, Dr. Shane became personnel director at the E.O. Lawrence Radiation Lab and arranged for Keith to work there at the cyclotron. A crash program to produce U235 from U238 was under way. At a crucial point in 1942 the cyclotron turned out the sought-after material. Much celebration ensued among the Rad Lab leaders. During this gala, Keith was on the night-shift and pretty much on his own. It was then that he turned a valve to the right, when left was called for, and the entire system went down. Shortly thereafter he was sent to Oak Ridge for the duration of the war. He cannot have been thought of badly, however, because he was invited to the Trinity test in New Mexico. (He didn't go because of the pending birth of his first son, John.) The year 1945 found Keith back in Berkeley working on his Ph

  20. Ion sound instability driven by ion beam

    CERN Document Server

    Koshkarov, O; Kaganovich, I D; Ilgisonis, V I

    2014-01-01

    In many natural and laboratory conditions, plasmas are often in the non-equilibrium state due to presence of stationary flows, when one particle species (or a special group, such as group of high energy particles, i.e. beam) is mowing with respect to the other plasma components. Such situations are common for a number of different plasma application such as diagnostics with emissive plasma probes, plasma electronics devices and electric propulsion devices. The presence of plasma flows often lead to the instabilities in such systems and subsequent development of large amplitude perturbations. The goal of this work is to develop physical insights and numerical tools for studies of stability of the excitation of the ion sound waves by the ion beam in the configuration similar to the plasma Pierce diode. This systems, in some limiting cases, reduce to mathematically similar equations originally proposed for Pierce instability. The finite length effect are crucial for this instability which generally belong to the...

  1. Julianne Pierce VNS Matrix / Julianne Pierce ; interv. Tilman Baumgärtel

    Index Scriptorium Estoniae

    Pierce, Julianne

    2006-01-01

    Intervjuu austraalia kunstniku Julianne Pierce'iga, kes koos Josephine Starrsi, Francesca da Rimini ja Virginia Barretiga lõi 1991. a. Sydney's naiskunstirühmituse VNS Matrix ning kirjutas "21. sajandi küberfeministliku manifesti". Rühmituse töödest

  2. Julianne Pierce VNS Matrix / Julianne Pierce ; interv. Tilman Baumgärtel

    Index Scriptorium Estoniae

    Pierce, Julianne

    2006-01-01

    Intervjuu austraalia kunstniku Julianne Pierce'iga, kes koos Josephine Starrsi, Francesca da Rimini ja Virginia Barretiga lõi 1991. a. Sydney's naiskunstirühmituse VNS Matrix ning kirjutas "21. sajandi küberfeministliku manifesti". Rühmituse töödest

  3. Remoção do piercing no perioperatório Remoción del piercing en el perioperatorio Perioperative removal of body piercing

    Directory of Open Access Journals (Sweden)

    Solange Diccini

    2008-02-01

    Full Text Available A permanência do piercing no intra-operatório pode ocasionar intercorrências. Este estudo teve como objetivo determinar as intervenções de enfermagem no pré-operatório e avaliar as complicações do piercing no intra-operatório. Durante a revisão da literatura, foram incluídos 16 artigos publicados de 1994 a 2006. Nove artigos (56,2% de intervenções de enfermagem no pré-operatório, quatro (25,0% de complicações do piercing no intra-operatório e três (18,8% sobre o uso do piercing no intra-operatório, não apresentando complicações. Concluímos que a presença de piercing oral durante o intra-operatório aumenta o risco de lesões e aspiração. No corpo, a presença do piercing pode causar lesões na pele, decorrentes da mobilização do paciente e queimaduras eletrocirúrgicas. Portanto, é necessária a retirada do piercing no pré-operatório.La permanencia del piercing en el intraoperatorio puede causar algún perjuicio. Pretendemos, determinar las intervenciones de enfermería en el preoperatorio y evaluar las complicaciones del piercing en el intraoperatorio. La revisión de la literatura mostró 16 artículos publicados de 1994 a 2006. Nueve (56,2% fueron de intervenciones de enfermería en el preoperatorio, cuatro (25,0% de complicaciones del piercing en intraoperatorio, tres (18,8% no mostraron complicaciones. Concluimos, la presencia del piercing oral, durante el intraoperatório aumenta el riesgo de aspiración y daño. En el cuerpo, puede causar heridas en la piel, provocadas por la movilización del enfermo y las quemaduras, debido al uso de bisturí eléctrico durante el acto intraoperatorio. Por consiguiente, es necesario retirar el piercing en el preoperatorio.The remaining of piercing in intraoperative can cause damages. This paper had as purpose defining the nursing interventions in the intraoperative and evaluates the complications caused by piercing in the intraoperative. This literature review had 16

  4. Oral Piercing and Oral Diseases: A Short Time Retrospective Study

    Directory of Open Access Journals (Sweden)

    Francesco Inchingolo, Marco Tatullo, Fabio M. Abenavoli, Massimo Marrelli, Alessio D. Inchingolo, Antonio Palladino, Angelo M. Inchingolo, Gianna Dipalma

    2011-01-01

    Full Text Available Body piercing indicates the puncturing of a part of the body in which jewelry may be worn. In recent years, oral piercing is increasingly popular especially among young people. Body piercing has to be considered as a surgical procedure to all intents and purposes and, as such, has to be performed only by qualified personnel able to assure high standards of professionalism in facilities subject to sanitary inspections.The aim of the present work is to verify what risks patients may be exposed to and what complications may occur after a healthcare professional performs oral piercing.Our retrospective study includes 108 patients (74 males and 34 females aged between 14 and 39 years, who had oral piercing done 12±4 months earlier. All the patients underwent clinical examination to reveal the possible presence of late complications. After piercing, none of the 108 patients developed widespread complications.Although all patients said they had followed the piercers' instructions, 96% of them reported postoperative local complications such as bleeding within 12 hours of piercing (90%, perilesional edema for 3±2 days after piercing surgery (80%, and persistent mucosal atrophy (70%.

  5. Management of Retained Genital Piercings: A Case Report and Review

    Directory of Open Access Journals (Sweden)

    Laura J. Moulton

    2017-01-01

    Full Text Available The prevalence of genital piercing among women is increasing. As the popularity increases, the number of complications from infection, injury, and retained jewelry is likely to rise. Techniques to remove embedded jewelry are not well described in the literature. The purpose of this report was to describe a case of a patient with a retained clitoral glans piercing, discuss a simple technique for outpatient removal, and review current evidence regarding associated risks of clitoral piercings. A 24-year-old female presented to the emergency department with an embedded clitoral glans piercing. Local anesthetic was injected into the periclitoral skin and a small superficial vertical incision was made to remove the ball of the retained barbell safely. In conclusion, among patients with retained genital piercing, outpatient removal of embedded jewelry is feasible. While the practice of female genital piercing is not regulated, piercing of the glans of the clitoris is associated with increased injury to the nerves and blood supply of the clitoris structures leading to future fibrosis and diminished function compared to piercing of the clitoral hood.

  6. Management of Retained Genital Piercings: A Case Report and Review

    Science.gov (United States)

    2017-01-01

    The prevalence of genital piercing among women is increasing. As the popularity increases, the number of complications from infection, injury, and retained jewelry is likely to rise. Techniques to remove embedded jewelry are not well described in the literature. The purpose of this report was to describe a case of a patient with a retained clitoral glans piercing, discuss a simple technique for outpatient removal, and review current evidence regarding associated risks of clitoral piercings. A 24-year-old female presented to the emergency department with an embedded clitoral glans piercing. Local anesthetic was injected into the periclitoral skin and a small superficial vertical incision was made to remove the ball of the retained barbell safely. In conclusion, among patients with retained genital piercing, outpatient removal of embedded jewelry is feasible. While the practice of female genital piercing is not regulated, piercing of the glans of the clitoris is associated with increased injury to the nerves and blood supply of the clitoris structures leading to future fibrosis and diminished function compared to piercing of the clitoral hood. PMID:28299217

  7. Tattoos and Piercings: Attitudes, Behaviors, and Interpretations of College Students

    Science.gov (United States)

    Horne, Jenn; Knox, David; Zusman, Jane; Zusman, Marty E.

    2007-01-01

    Previously, in those segments of America where "proper" behavior was valued, tattoos and body piercings were examples of what Goffman identified as "stigma"--they spoiled one's identity. Today, tattoos and piercings have become more mainstream. This study reports the survey of 400 undergraduates at a large southeastern university. Regarding…

  8. Application of hard coatings for blanking and piercing tools

    DEFF Research Database (Denmark)

    Podgornik, B.; Zajec, B.; Bay, Niels

    2011-01-01

    The aim of the present investigation was to examine the possibility of reducing lubrication and replacing expensive tungsten carbide material in blanking/piercing through introduction of hard tool coatings. Results show that hard PVD coatings can be successfully used in blanking/piercing...... critical value under dry friction conditions and leads to tool failure. Therefore, at present oxidation and temperature resistant hard coatings can give improved wear resistance of stamping tools, but elimination of lubricants in blanking and piercing processes is still not feasible....

  9. Perceptions of a photograph of a woman with visible piercings.

    Science.gov (United States)

    Martino, Sara

    2008-08-01

    To examine perceptions of people with visible piercings 105 undergraduate students from four different courses on campus (85 women, 20 men; M age=20.0 yr., SD=3.4) were randomly assigned to rate a photograph of a women with or without piercings on her eyebrow, ear, lip, and nose on 13 characteristics. Analysis indicated the model with visible piercings was rated less religious and more creative, artistic, and mysterious. These findings differ from previous findings on perception of tattoos. Implications and directions for research with different age groups are discussed.

  10. Pierce Lumber, Inc. - Clean Water Act Public Notice

    Science.gov (United States)

    The EPA is providing notice of a proposed Administrative Penalty Assessment against Pierce Lumber, Inc. (“Respondent”), located at 1629 13th Street, Belle Plaine, IA for alleged violations of its National Pollutant Discharge Elimination System permit (perm

  11. Pierce National Wildlife Refuge: Narrative Report: 1992: Calendar Year

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Pierce National Wildlife Refuge outlines Refuge accomplishments for the 1992 calendar year. The report begins by giving Refuge highlights...

  12. Drawing Euler Diagrams with Circles: The Theory of Piercings.

    Science.gov (United States)

    Stapleton, Gem; Leishi Zhang; Howse, John; Rodgers, Peter

    2011-07-01

    Euler diagrams are effective tools for visualizing set intersections. They have a large number of application areas ranging from statistical data analysis to software engineering. However, the automated generation of Euler diagrams has never been easy: given an abstract description of a required Euler diagram, it is computationally expensive to generate the diagram. Moreover, the generated diagrams represent sets by polygons, sometimes with quite irregular shapes that make the diagrams less comprehensible. In this paper, we address these two issues by developing the theory of piercings, where we define single piercing curves and double piercing curves. We prove that if a diagram can be built inductively by successively adding piercing curves under certain constraints, then it can be drawn with circles, which are more esthetically pleasing than arbitrary polygons. The theory of piercings is developed at the abstract level. In addition, we present a Java implementation that, given an inductively pierced abstract description, generates an Euler diagram consisting only of circles within polynomial time.

  13. Behaviour and Modelling of Self-piercing Screw and Self-piercing Rivet Connections: An Experimental and Numerical Investigation

    OpenAIRE

    Sønstabø, Johan Kolstø; Holmstrøm, Petter Henrik

    2013-01-01

    Accurate and reliable models of connections are essential for the design of aluminium parts in cars. Today, there exist a few models customized for self-piercing rivets (SPR), but none for self-piercing screws (SPS). This thesis presents an experimental and numerical study on the behaviour of SPR and SPS connections for different loading situations. For the rolled base material, AA6016 in the T4 condition, uniaxial tension, plane strain tension and in-plane single shear tests were performe...

  14. Preliminary design for a pierce wiggler beamstick and addendum

    Energy Technology Data Exchange (ETDEWEB)

    Pirkle, D.

    1988-05-01

    Lawrence Livermore National Laboratory is developing a fast tunable microwave source for operation at 250 GHz and 10kW peak output power. This report presents the preliminary design of a Pierce gun and solenoid magnet that will be compatible with a Pierce-wiggler electron beam formation system (beamstick). The beamstick will be an appropriate power source for a tunable gyro-BWO at 250 GHz. Figure 1 presents the major components of the Pierce-wiggler beamstick: the electron gun, solenoid, beam tunnel, wiggler, and vacuum valve. Figure 2 shows an artistic conception of how the beamstick will interface with the interaction magnet, modulator and gyro-BWO circuit at MIT. 15 figs.

  15. Tattoos, piercing, and sexual behaviors in young adults.

    Science.gov (United States)

    Nowosielski, Krzysztof; Sipiński, Adam; Kuczerawy, Ilona; Kozłowska-Rup, Danuta; Skrzypulec-Plinta, Violetta

    2012-09-01

    Body piercing and tattooing are accepted by a growing number of teenagers and young adults as a way of self-expressing. Some authors suggest association between body piercings/tattoos and early sexual initiation, higher number of sexual partners, or risky sexual behaviors. The aim of the study was to evaluate sexual behaviors among young adults with body modifications (BMs)--tattoos and piercings. One hundred twenty young healthy adults, ages between 20 and 35, were included in the population study. The study group was divided into three subgroups: controls (N = 60), adults with tattoos (N = 28), and adults with piercings (N = 32). The research instrument was a self-prepared questionnaire containing 59 questions assessing socioepidemiological parameters, sexual behaviors, incidents of sexual harassment in the past, and self-attractiveness evaluation, as well as questions concerning tattoos and piercings. Socioepidemiological variables and sexual behaviors were compared between subgroups. To assess and describe the correlation between having BM--tattoos and piercing--and sexual behaviors in the population of young adults by using the logistic regression model. Adults with BMs have had their first intercourse statistically earlier and were more sexually active compared with controls. There were no statically significant differences in sexual orientation, sexual preferences, engaging in risky sexual behaviors, frequency of masturbation, and history of sexual abuse between the groups. In contrast, the frequency of sexual intercourses was statistically higher and oral sex was more likely to be a dominant sexual activity in adults with BM compared with controls. The multivariate logistic model revealed that adults with BM were four times less likely to participate in religious practices and twice more likely to have early sexual initiation. Having BM is associated with early sexual initiation and more liberal attitudes toward sexual behaviors but not with engaging in

  16. The strength analysis of the wave piercing buoy

    Science.gov (United States)

    Jiang, Dong; Li, Wenhua; Chen, Xinyang; Chen, Haiquan

    2017-04-01

    The wave piercing buoy in this paper is different with the traditional cylindrical buoy, it is made by ultra-high molecular weight polyethylene (UHMWPE) and has six middle pontoons. In order to guarantee the stability of the buoy structure, it is necessary to carry out the strength analysis. This paper use the ANSYS software to carry on the simulation analysis to the buoy, and the result of it is compare with the actual operation, therefore ensure the strength of the wave piercing buoy meet the related requirements.

  17. 78 FR 78808 - Proposed Flood Elevation Determinations for Pierce County, Washington, and Incorporated Areas

    Science.gov (United States)

    2013-12-27

    ... Pierce County, Washington, and Incorporated Areas AGENCY: Federal Emergency Management Agency, DHS... its proposed rule concerning proposed flood elevation determinations for Pierce County, Washington... sources in Pierce County, Washington. On April 16, 2012, FEMA published a proposed rulemaking at 77 FR...

  18. 27 CFR 478.37 - Manufacture, importation and sale of armor piercing ammunition.

    Science.gov (United States)

    2010-04-01

    ... and sale of armor piercing ammunition. 478.37 Section 478.37 Alcohol, Tobacco Products, and Firearms..., importation and sale of armor piercing ammunition. No person shall manufacture or import, and no manufacturer or importer shall sell or deliver, armor piercing ammunition, except: (a) The manufacture or...

  19. 78 FR 4804 - Revision to the Washington State Implementation Plan; Tacoma-Pierce County Nonattainment Area

    Science.gov (United States)

    2013-01-23

    ... AGENCY 40 CFR Part 52 Revision to the Washington State Implementation Plan; Tacoma- Pierce County... (CAA) requirements related to the Tacoma-Pierce County nonattainment area for the 2006 fine particulate... Tacoma-Pierce County Clean Air Task Force, an advisory committee of community leaders, citizen...

  20. 27 CFR 478.92 - How must licensed manufacturers and licensed importers identify firearms, armor piercing...

    Science.gov (United States)

    2010-04-01

    ... manufacturers and licensed importers identify firearms, armor piercing ammunition, and large capacity ammunition..., armor piercing ammunition, and large capacity ammunition feeding devices? (a)(1) Firearms. You, as a... (bases). (b) Armor piercing ammunition—(1) Marking of ammunition. Each licensed manufacturer or licensed...

  1. 75 FR 14467 - Notice of Inventory Completion: Pierce College District, Lakewood, WA, and Thomas Burke Memorial...

    Science.gov (United States)

    2010-03-25

    ... National Park Service Notice of Inventory Completion: Pierce College District, Lakewood, WA, and Thomas... in the control of the Pierce College District, Lakewood, WA, and in the physical custody of the... human remains were most likely removed from Gig Harbor, Pierce County, WA. This notice is published as...

  2. The Separation of School and State: Pierce Reconsidered

    Science.gov (United States)

    Arons, Stephen

    1976-01-01

    Does the Constitution protect parents' right to pass their values along to their children? Author argues that it does, basing his contention on the language and the history of Pierce v. Society of Sisters, the landmark decision that guaranteed private schools' right to do business. (Editor/RK)

  3. George Pierce Baker's "Principles of Argumentation": "Completely Logical"?

    Science.gov (United States)

    Bordelon, Suzanne

    2006-01-01

    The article contends that previous scholars have misread George Pierce Baker's efforts by focusing primarily on "The Principles of Argumentation" and the role of logic. Baker's view of logic was more complex than scholars have claimed. He challenged traditional concepts of formal logic, highlighting only those aspects that would help students…

  4. Pierce County High School: Excellence Is the Standard

    Science.gov (United States)

    Principal Leadership, 2012

    2012-01-01

    This article features Pierce County High School in rural southeast Georgia whose 965 students, almost half of whom are from economically disadvantaged families, have demonstrated what a focus on student learning can accomplish. In 2004, the school ranked at the bottom of the state in students passing the high school graduation tests, and only 55%…

  5. Scaling properties of Wilson loops pierced by P-vortices

    DEFF Research Database (Denmark)

    Dunn, Patrick; Greensite, Jeffrey Paul

    2012-01-01

    these ratios are plotted versus loop area in physical units, for a range of lattice couplings, it is found that the points fall approximately on a single curve, consistent with scaling. We also find that the ratios are rather insensitive to the point where the minimal area of the loop is pierced by the P-vortex....

  6. Psychosocial Adjustment of College Students with Tattoos and Piercings

    Science.gov (United States)

    Roberti, Jonathan W.; Storch, Eric A.

    2005-01-01

    The purpose of this study was to examine the association between body modification practices and psychosocial adjustment. Participants were 198 undergraduate college students, 129 of whom had I or more piercings (other than in earlobe) or tattoos. Findings showed that individuals with body modifications reported more symptoms of depression and…

  7. A New Keyboard for the Bohlen-Pierce Scale

    CERN Document Server

    Nassar, Antonio

    2011-01-01

    The study of harmonic scales of musical instruments is discussed in all introductory physics texts devoted to the science of sound. In this paper, we present a new piano keyboard to make the so-called Bohlen-Pierce scale more functional and pleasing for composition and performance.

  8. Just a personal thing? A qualitative account of health behaviours and values associated with body piercing.

    Science.gov (United States)

    Randall, Jason A; Sheffield, David

    2013-03-01

    This study investigates the perceptions of individuals with body piercings in relation to health behaviours and values specifically taking into account piercing location. A qualitative study that employed a series of in-depth, semi-structured individual interviews using thematic analysis to analyse data. Nine individuals with a range of piercings were recruited and semi-structured interviews were carried out in a West Midlands piercing studio. The analysis identified themes relating to the presence of body piercings that included a range of health-related outcomes such as physical appearance, health behaviours, addiction and impressions. A possible relationship between oral piercings and 'crash dieting' was also identified. The results suggest that from the comments made the presence of body piercings is not related to any particular health concern, which is instead comparable to the general population. These results contradict previous studies citing a relationship with high-risk health behaviours. Further large-scale studies examining these findings are warranted.

  9. Patients' perceptions of patient care providers with tattoos and/or body piercings.

    Science.gov (United States)

    Westerfield, Heather V; Stafford, Amy B; Speroni, Karen Gabel; Daniel, Marlon G

    2012-03-01

    This study evaluated patients' perceptions of patient care providers with visible tattoos and/or body piercings. As tattooing and body piercing are increasingly popular, research that informs nursing administrators regarding policies on patient care providers having visible tattoos and body piercings is warranted. A total of 150 hospitalized adult patients compared pictures of male and female patient care providers in uniform with and without tattoos and/or nonearlobe body piercings. Patient care providers with visible tattoos and/or body piercings were not perceived by patients in this study as more caring, confident, reliable, attentive, cooperative, professional, efficient, or approachable than nontattooed or nonpierced providers. Tattooed female providers were perceived as less professional than male providers with similar tattoos. Female providers with piercings were perceived as less confident, professional, efficient, and approachable than nonpierced female providers. Nursing administrators should develop and/or evaluate policies regarding patient care providers with visible tattoos and/or body piercings.

  10. A power ramped pulsed mode laser piercing technique for improved CO 2 laser profile cutting

    Science.gov (United States)

    Tirumala Rao, B.; Ittoop, M. O.; Kukreja, L. M.

    2009-11-01

    Laser piercing is one of the inevitable requirements of laser profile cutting process and it has a direct bearing on the quality of the laser cut profiles. We have developed a novel power ramped pulsed mode (PRPM) laser piercing technique to produce much finer pierced holes and to achieve a better control on the process parameters compared to the existing methodology based on normal pulsed mode (NPM). Experiments were carried out with both PRPM and NPM laser piercing on 1.5-mm-thick mild steel using an in-house developed high-power transverse flow continuous wave (CW)-CO 2 laser. Significant improvements in the spatter, circularity of the pierced hole and reproducibility were achieved through the PRPM technique. We studied, in detail, the dynamics of processes involved in PRPM laser piercing and compared that with those of the NPM piercing.

  11. Triple inverter pierce oscillator circuit suitable for CMOS

    Science.gov (United States)

    Wessendorf; Kurt O.

    2007-02-27

    An oscillator circuit is disclosed which can be formed using discrete field-effect transistors (FETs), or as a complementary metal-oxide-semiconductor (CMOS) integrated circuit. The oscillator circuit utilizes a Pierce oscillator design with three inverter stages connected in series. A feedback resistor provided in a feedback loop about a second inverter stage provides an almost ideal inverting transconductance thereby allowing high-Q operation at the resonator-controlled frequency while suppressing a parasitic oscillation frequency that is inherent in a Pierce configuration using a "standard" triple inverter for the sustaining amplifier. The oscillator circuit, which operates in a range of 10 50 MHz, has applications for use as a clock in a microprocessor and can also be used for sensor applications.

  12. The impairment of Presidents Pierce and Coolidge after traumatic bereavement.

    Science.gov (United States)

    Davidson, Jonathan R T; Connor, Kathryn M

    2008-01-01

    The impact of bereavement in heads of government has been little studied. Two US presidents lost their teenaged sons in a traumatic manner, leaving them profoundly affected as they struggled to serve in office. We describe the bereavements of Presidents Franklin Pierce and Calvin Coolidge, using biographical and source material. Pierce and Coolidge were adversely affected by their bereavements, which almost certainly rendered them less effective in the discharge of their duties. The loss of their sons had a devastating effect on both men and deprived their presidential service of significant personal meaning. Lincoln's resilience in similar circumstances offers a contrasting perspective, however. We conclude that the psychiatric consequences of losing a child can adversely affect heads of government, may cause clinically significant distress, altered behavior, and reduced ability to provide effective leadership.

  13. The Development of Piezo-Driven Tools for Cellular Piercing

    Directory of Open Access Journals (Sweden)

    Changhai Ru

    2016-10-01

    Full Text Available Conventionally, intracytoplasmic sperm injection (ICSI in the mouse is conducted with piezo-drills that use a droplet of mercury for damping. The use of mercury causes concerns of toxicity and contamination. Although Fluorinert can be used as a substitute for mercury to reduce piezo-drill’s lateral vibration, the damping effect is not as satisfactory as mercury. In this work, a modified piezo-drill without using mercury was developed for the cellular piercing of mouse oocytes. Experimentally, appropriate parameters of driving voltage and frequency were obtained for the penetration of the zona pellucida of mouse oocytes. Furthermore, the lateral vibration of the injection pipette is lower than 1 μm in deionized water, which is not observable at 400 magnificence. With the piezo-drill without using mercury, the system performs the cellular piercing of mouse oocytes with a maximum cleavage rate of 94.7% (n = 117.

  14. Pierce - University of Georgia | Division of Cancer Prevention

    Science.gov (United States)

    Principal Investigator: J. Michael Pierce, PhDInstitution: University of Georgia, Athens, GA Our project, Discovery and Development of Cancer Glycomarkers, is a joint collaboration between our laboratories at the CCRC, which include Karen Abbott, Lance Wells, Kevin Dobbin, and Mike Tiemeyer, those at TGen, in Phoenix, AZ, Daniel Von Hoff, Haiyong Han, and Mike Demeure, and Caerus Discovery in Manassas, VA, which includes Cohava Gelber and S?ren Mogelsvang. |

  15. Fisher Pierce products for improving distribution system reliability

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    The challenges facing the electric power utility today in the 1990s has changed significantly from those of even 10 years ago. The proliferation of automation and the personnel computer have heightened the requirements and demands put on the electric distribution system. Today`s customers, fighting to compete in a world market, demand quality, uninterrupted power service. Privatization and the concept of unregulated competition require utilities to streamline to minimize system support costs and optimize power delivery efficiency. Fisher Pierce, serving the electric utility industry for over 50 years, offers a line of products to assist utilities in meeting these challenges. The Fisher Pierce Family of products provide tools for the electric utility to exceed customer service demands. A full line of fault indicating devices are offered to expedite system power restoration both locally and in conjunction with SCADA systems. Fisher Pierce is the largest supplier of roadway lighting controls, manufacturing on a 6 million dollar automated line assuring the highest quality in the world. The distribution system capacitor control line offers intelligent local or radio linked switching control to maintain system voltage and Var levels for quality and cost efficient power delivery under varying customer loads. Additional products, designed to authenticate revenue metering calibration and verify on sight metering service wiring, help optimize the profitability of the utility assuring continuous system service improvements for their customers.

  16. In Vitro Study on the Adhesion and Colonization of Candida Albicans on Metal and Acrylic Piercings

    Directory of Open Access Journals (Sweden)

    Stamenov N.

    2016-03-01

    Full Text Available Oral/perioral piercing may provide an ideal environment for adhesion and colonization of microorganisms. The aim of this study is to perform an “in vitro” research on the capabilities of adhesion of Candida albicans on oral piercings made of plastic and metal. Acrylic and metal piercings were incubated with Candida albicans and then were observed using scanning electron microscopy under different magnifications. A lot of irregularities and roughness were observed on the surface of the plastic piercing unlike the surface of the metal one, which is not so rough. Nevertheless, the number of Candida albicans colonies was considerably larger on the scanned metal surface in comparison to the plastic surface. In vitro the metal surface of the piercing creates better environment for the adhesion and colonization of microorganisms than the acrylic. This could be attributed to the electrostatic forces that most likely attract Candida albicans to the metal piercing in the early stages of biofilm formation.

  17. Design of a High Speed Planing Hull with a Cambered Step and Surface Piercing Hydrofoils

    Science.gov (United States)

    2014-06-01

    Design of a High Speed Planing Hull with a Cambered Step and Surface Piercing Hydrofoils by Leon Alexander Faison Bachelor of Science in...Speed Planing Hull with a Cambered Step and Surface Piercing Hydrofoils 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...cambered step and stern, surface piercing hydrofoils , commonly known as a Dynaplane hull. This configuration combines the drag reduction benefits of a

  18. BILATERAL PERICHONDRITIS OF PINNA FOLLOWING PIERCING OF HELIX – A CASE REPORT

    Directory of Open Access Journals (Sweden)

    Rajamani

    2014-01-01

    Full Text Available Piercing of Helix of pinna is a social custom of certain communities in Northern Tamil Nadu. Such a “high helical” piercing is well known to cause Perichondritis of Pinna. Most of the times such a Perichondritis is unilateral. Here we present a case of Bilateral Perichondritis of pinna, following ear piercing, first time from India subcontinent. We also highlight some practical points on management of such cases.

  19. Fibre laser piercing of mild steel: the effects of power intensity, gas type and pressure

    OpenAIRE

    Hashemzadeh, M.; Powell, J.; Voisey, K.T.

    2014-01-01

    Laser piercing is used to generate a starting point for laser cutting. The pierced hole is normally larger than the kerf width, which means that it cannot lie on the cut line. An experimental program investigating the piercing process as a function of laser and assist gas parameters is presented. An Nd:YAG fibre laser with a maximum power of 2 kW was used in continuous wave mode to pierce holes in 2 mm thick mild steel. Oxygen and nitrogen were used as assist gases, with pressures ranging fro...

  20. Fibre laser piercing of mild steel - The effects of power intensity, gas type and pressure

    Science.gov (United States)

    Hashemzadeh, M.; Powell, J.; Voisey, K. T.

    2014-04-01

    Laser piercing is used to generate a starting point for laser cutting. The pierced hole is normally larger than the kerf width, which means that it cannot lie on the cut line. An experimental programme investigating the piercing process as a function of laser and assist gas parameters is presented. An Nd:YAG fibre laser with a maximum power of 2 kW was used in continuous wave mode to pierce holes in 2 mm thick mild steel. Oxygen and nitrogen were used as assist gases, with pressures ranging from 0.3 to 12 bar. The sizes, geometries and piercing time of the holes produced have been analysed. The pierced hole size decreases with increasing gas pressure and increasing laser power. Oxygen assist gas produced larger diameter holes than nitrogen. A new technique is presented which produces pierced holes no larger than the kerf with and would allow the pierced hole to lie on the cut line of the finished product - allowing better material usage. This uses an inclined jet of nitrogen when piercing prior to oxygen assisted cutting.

  1. Mechanical instability

    CERN Document Server

    Krysinski, Tomasz

    2013-01-01

    This book presents a study of the stability of mechanical systems, i.e. their free response when they are removed from their position of equilibrium after a temporary disturbance. After reviewing the main analytical methods of the dynamical stability of systems, it highlights the fundamental difference in nature between the phenomena of forced resonance vibration of mechanical systems subjected to an imposed excitation and instabilities that characterize their free response. It specifically develops instabilities arising from the rotor-structure coupling, instability of control systems, the se

  2. Collective instabilities

    Energy Technology Data Exchange (ETDEWEB)

    K.Y. Ng

    2003-08-25

    The lecture covers mainly Sections 2.VIII and 3.VII of the book ''Accelerator Physics'' by S.Y. Lee, plus mode-coupling instabilities and chromaticity-driven head-tail instability. Besides giving more detailed derivation of many equations, simple interpretations of many collective instabilities are included with the intention that the phenomena can be understood more easily without going into too much mathematics. The notations of Lee's book as well as the e{sup jwt} convention are followed.

  3. Experimental Characterization of Supercavitating Finds Piercing a Ventilated Supercavity

    Science.gov (United States)

    2013-08-05

    1.1 Cavitation 1 1.2 Supercavitation 3 1.3 Supercavitating Hydrofoils 8 1.4 Surface Piercing Hydrofoils 13 1.5 Hydrodynamic Forces 14 1.6 Project...Cavitation on Traditional and Supercavitating Hydrofoil Sections, Adapted from (Auslaender, 1962) 9 1.5 Leading Edge Vibration on a Supercavitating Fin with a...for a Flat Plate Hydrofoil vs. Angle of Attack and Cavitation Number using Wu’s Free Streamline Theory (Wu, 1955). 21 2.3 Estimated Lift and Drag for

  4. Edge state and crisis in the Pierce diode

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, Pablo R.; Rempel, Erico L. [Institute of Aeronautical Technology (ITA) and World Institute for Space Environment Research (WISER), CTA/ITA/IEFM, Sao Jose dos Campos-SP 12228-900 (Brazil); Barroso, Joaquim J. [National Institute for Space Research (INPE) and World Institute for Space Environment Research (WISER), P. O. Box 515, Sao Jose dos Campos-SP 12227-010 (Brazil); Chian, Abraham C.-L. [National Institute for Space Research (INPE) and World Institute for Space Environment Research (WISER), P. O. Box 515, Sao Jose dos Campos-SP 12227-010 (Brazil); Observatoire de Paris, LESIA, CNRS, 92195 Meudon (France)

    2012-09-15

    We study the chaotic dynamics of the Pierce diode, a simple spatially extended system for collisionless bounded plasmas, focusing on the concept of edge of chaos, the boundary that separates transient from asymptotic dynamics. We fully characterize an interior crisis at the end of a periodic window, thereby showing direct evidence of the collision between a chaotic attractor, a chaotic saddle, and the edge of chaos, formed by a period-3 unstable periodic orbit and its stable manifold. The edge of chaos persists after the interior crisis, when the global attractor of the system increases its size in the phase space.

  5. Primary Cutaneous Chrysosporium Infection following Ear Piercing: A Case Report

    Directory of Open Access Journals (Sweden)

    Poonkiat Suchonwanit

    2015-07-01

    Full Text Available Chrysosporium is a large genus of saprophytic fungi that is commonly found in the soil. Infection caused by this organism is rare in humans and typically occurs in immunocompromised patients. Primary cutaneous Chrysosporium infection is relatively rare and has been reported in a heart transplant patient. The prognosis is usually favorable, but very poor in the setting of persistent profound immunosuppression. We herein report a case of primary cutaneous Chrysosporium infection following ear piercing in an immunocompetent patient. It is important for clinicians to consider this condition in patients with slow-onset skin and soft tissue infection following cutaneous injury, even in an immunocompetent setting.

  6. Adolescent and Young Adult Tattooing, Piercing, and Scarification.

    Science.gov (United States)

    Breuner, Cora C; Levine, David A

    2017-09-18

    Tattoos, piercing, and scarification are now commonplace among adolescents and young adults. This first clinical report from the American Academy of Pediatrics on voluntary body modification will review the methods used to perform the modifications. Complications resulting from body modification methods, although not common, are discussed to provide the pediatrician with management information. Body modification will be contrasted with nonsuicidal self-injury. When available, information also is presented on societal perceptions of body modification. Copyright © 2017 by the American Academy of Pediatrics.

  7. Tattoos and Piercing: A Review for the Emergency Department Physician

    Directory of Open Access Journals (Sweden)

    William K. Mallon

    2011-05-01

    Full Text Available Tattoos and piercings are increasingly part of everyday life for large sections of the population, and more emergency physicians are seeing these body modifications (BM adorn their patients. In this review we elucidate the most common forms of these BMs, we describe how they may affect both the physical and psychological health of the patient undergoing treatment, and also try to educate around any potential pitfalls in treating associated complications. [West J Emerg Med. 2011;12(4:393–398.

  8. Occupational accidents with piercing and cutting instruments in hospital nurses

    Directory of Open Access Journals (Sweden)

    Maria Helena Palucci Marziale

    2004-02-01

    Full Text Available Goals: To identify factors associated with occupational accidents caused by piercing and cutting instruments and to identify the consequences of these accidents.Methods: Descriptive field research. Data were obtained through semi-structured interviews with nurses who suffered accidents during one year in four hospitals at São Paulo State - Brazil. Results: factors associated with accidents were: work overload, poor quality material, inadequate disposal materials, professional negligence, clients’ aggressiveness, lack of attention and use of unsheathed needles. The accidents caused financial damages to the institutions as well as emotional and physical impairments to workers. Conclusions: There are several factors associated with accidents with piercing and cutting instruments. Therefore, preventive measures must be implemented according to the peculiarities of each work environment. Better care should be taken with the preparation of the professionals as well as with the information on risks from exposure to body/blood fluids they are given. A specific legislation is needed in our country in order to minimize this problem.

  9. Reflections on Dean Truman Pierce as Educator, Boss, Mentor and Friend

    Science.gov (United States)

    Watkins, J. Foster

    2012-01-01

    The author was invited to submit a reflective piece relative to his relationships with Dean Truman Pierce over the years to be presented on "The 30th Anniversary Celebration of the Truman Pierce Institute" at Auburn University. It was included in the program for the event.

  10. Tattooing and body piercing--what motivates you to do it?

    Science.gov (United States)

    Antoszewski, Bogusław; Sitek, Aneta; Fijałkowska, Marta; Kasielska, Anna; Kruk-Jeromin, Julia

    2010-09-01

    Body ornamentation is becoming more and more popular, especially among young people. To establish the sociodemographic characteristics of people with tattoos or body piercing and to analyze the motivations for body ornamentation. The questionnaire studies were undertaken in Lodz--one of the largest cities in Poland. The data was collected from a group of 968 people, 476 of whom had a piercing and 492 a permanent tattoo. Statistical analysis revealed that in the group of people with a tattoo, 36.8% were female and 63.2% were male. Contrary proportions were noted among people with a piercing: 78.8% female and 21.2% male. Body piercing is significantly more popular among women while tattooing is more popular in men. Among adolescents, body piercing is performed considerably earlier than tattooing. The main reasons for body ornamenting in the Polish population are the desire to enhance one's individuality and the need to increase sexual attractiveness.

  11. Knowledge, Attitudes and Behaviour about Tattoo and Piercing among University Students

    Directory of Open Access Journals (Sweden)

    Yeşim Şenol

    2014-09-01

    Full Text Available Objective: Special Study Modules were firstly introduced five years ago at Akdeniz University Faculty of Medicine. The learning of basic concepts related with the skin and skin decorative arts, scientific presentations, informational society brochure were aimed in skin decorative arts such as tattoos and piercing, special study module. Methods: Four students admitted special study module opened in 2008-2009 academic year and 7 students in 2009-2010. Students organized a questionnaire to reveal the need for information on the subject. A questionnaire for tattoo and piercing were applied to students of Faculty of Medicine, Faculty of Fine Arts and the Faculty of Education. Presentation was performed in accordance with the requirements revealed by the questionnaire form and prepared leaflets were distributed to the students. Results: The prevalence of tattooing and body piercing was 12.3% in all students (n=154. 47.6% (n=10 for only tattoo, 42.9% (n=9 for only piercing, 9.6% (n=2 for both tattoo and piercing. Of the Medical Faculty students, 6.3% reported having both piercing and tattoo; 10.5% of the Faculty of Education students reported having both tattoo and piercing and 25.5% of the Faculty of Fine Arts students reported having both piercing and tattoo. Students of Medical Faculty gave more correct answers about the information of tattoo and piercing. Fine Arts students enjoyed getting tattoo and piercing more than other students and they applied these procedures at the maximum rate. Information levels about complications after the procedures were not adequate among the subjects practiced these applications. Conclusion: Our study emphasized the necessity of the studies for informing individuals about the art of skin decoration.

  12. 27 CFR 478.149 - Armor piercing ammunition manufactured or imported for the purpose of testing or experimentation.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 3 2010-04-01 2010-04-01 false Armor piercing ammunition... Armor piercing ammunition manufactured or imported for the purpose of testing or experimentation. The provisions of §§ 478.37 and 478.99(d) with respect to the manufacture or importation of armor piercing...

  13. Recombination instability

    DEFF Research Database (Denmark)

    D'Angelo, N.

    1967-01-01

    A recombination instability is considered which may arise in a plasma if the temperature dependence of the volume recombination coefficient, alpha, is sufficiently strong. Two cases are analyzed: (a) a steady-state plasma produced in a neutral gas by X-rays or high energy electrons; and (b) an af...

  14. Rotating black holes pierced by a cosmic string

    CERN Document Server

    Kubiznak, David

    2015-01-01

    A rotating black hole threaded by an infinitely long cosmic string is studied in the framework of the Abelian Higgs model. We show that contrary to a common belief in the presence of rotation the backreaction of the string does not induce a simple conical deficit. This leads to new distinct features of the Kerr--string system such as modified ISCO or shifted ergosphere, though these effects are most likely outside the range of observational precision. For an extremal rotating black hole, the system exhibits a first-order phase transition for the gravitational Meissner effect: small black holes exhibit a flux-expelled solution, with the gauge and scalar field remaining identically in their false vacuum state on the event horizon, whereas the horizon of large black holes is pierced by the vortex. A brief review prepared for the MG14 Proceedings.

  15. Ulcer piercing: cleansing of complicated diabetic neuropathic foot ulcers by positive pressure irrigation.

    Science.gov (United States)

    Cavallini, M

    2014-02-01

    To demonstrate the efficacy of the ulcer piercing procedure, which allows constant cleansing of the ulcer and facilitates a positive pressure irrigation of any pierced hidden tracts, in order to reduce the negative impact of stasis on wound healing. We designed a surgical procedure of ulcer piercing and drainage with a silastic tube, which allows positive pressure irrigation of any pierced tracts. This procedure was performed in a continuous series of 25 selected diabetic patients affected by a Wagner stage 3 ulcer of the toe (n=16), metatarsal midfoot (n=5) and plantar Charcot foot (n=4), and with adequate foot arterial blood supply. Within 6 months of the ulcer piercing procedure, 23/25 of ulcers had completely healed. In two further cases, the ulcer piercing ring was still in place after 3 and 5 months, progressively healing with no active signs of infection. Taking into consideration the advantages and the lack of side effects afforded by this procedure, ulcer piercing represents a small but effective step towards an easier and safer approach to treating complicated diabetic neuropathic foot ulcers with adequate arterial blood supply. There were no external sources of funding for this study. The author has no conflicts of interest to declare with regard to the manuscript or its content.

  16. High ear-piercing: an increasingly popular procedure with serious complications. Is good clinical practice exercised?

    Science.gov (United States)

    Lyons, Marie; Stephens, Joanna; Wasson, Joseph; DeZoysa, Nilantha; Vlastarakos, Petros V

    2012-03-01

    This study aimed to explore the current practice of performing high ear-piercing regarding consent protocols, and methods of practice using questionnaire-based survey in Hertfordshire and North London. Recommendations for good clinical practice are also made. 100 establishments performing ear piercing were identified. A 16-item questionnaire on techniques used, methods of high-ear piercing, methods of sterilization, consent issues and aftercare was completed. Seventy-six establishments agreed to participate. All practitioners prepared the skin before piercing. 58 (76%) used a needle for piercing, 11 (15%) used a spring-loaded gun and seven (9%) used both. 97% of the practitioners obtained written consent before proceeding. 9 (12%) had a lower age limit of 16 years and three (4%) of 18 years. 27 piercers (36%) provided an aftercare leaflet, 41 (54%) warned the patients about risks of infection, 16 (21%) warned about cosmetic deformity and 1 (1%) specifically mentioned cauliflower ear. Results indicated that high ear piercing is an invasive procedure with a significant risk of complications leading to cosmetic deformity. Establishments should be required to counsel patients properly about the risks and potential complications of the procedure. A code of practice should be drawn up with a minimum age for piercing, requirement for proper consent, excellent hygiene and good information for postoperative care.

  17. Reaksi Radang pada Lidah dengan Tongue Piercing (Kajian in vivo pada Lidah Tikus Jantan Sprague dawley

    Directory of Open Access Journals (Sweden)

    Feby Aryani

    2015-10-01

    Full Text Available Today tongue piercing has become increasingly popular in the society. Several case reports associated with tongue piercing have presented various complications, such as tooth fracture, viral infection (HIV, Hepatitis B and C, herpes simplex, Epstein Barr, fungal infection (Candida spp, pain altered taste, edema, paresthesis, gingival recession, prolonged bleeding, contact dermatitis. However, there is no scientific evidence to reveal hispathological change in tongue piercing. The aim of this study is to investigate the inflammation response to tongue piercing in Spraque Dawley rats. Eighteen Sprague Dawley rats were divided into one control group of 3 untreated rats and three experimental groups of 5 rats each, according to the duration of tongue piercing until the end of 1st week (A, 6th week (B and 12th week (C. At the end of treatments, the rats were anesthetized and sacrifices. Paraffin embedded tongue specimens were prepared for histological examination with H&E stainig. The number of inflammatory cells (PMN leukocytes, lymphocytes, macrophages was counted under light microscope. All experimental procedures were carried out under approval of study protocol by the Health and Medical Research Ethics Committee, Faculty of Medicine, Gadjah Mada University, Yogyakarta. The results of this study indicated that the number of PMN leukocytes, lymphocytes, and macrophages was increasing to the 1st week after tongue piercing. The number of lymphocytes and macrohpages was still increasing after 6th and 12th weeks of piercing, but the bumber of PMN leukocytes, lymphocytes, and macrophages between the groups of 1st, 6th, and 12th weeks after piercing. It was concluded that tongue piercing induce inflammatory response for 12 weeks in Sprague Dawley rats.

  18. Application of Hard Coatings for Improved Tribological Performance of Blanking and Piercing Tools

    DEFF Research Database (Denmark)

    Podgornik, B.; Zajec, B.; Bay, Niels

    2010-01-01

    The aim of the present investigation was to examine the possibility of reducing lubrication and replacing expensive tungsten carbide material in blanking/piercing through introduction of hard tool coatings. Results show that hard PVD coatings can be successfully used in blanking/piercing...... critical value under dry friction conditions and leads to tool failure. Therefore, at present oxidation and temperature resistant hard coatings can give improved wear resistance of stamping tools, but elimination of lubricants in blanking and piercing processes is still not feasible....

  19. [Carpal instability].

    Science.gov (United States)

    Redeker, J; Vogt, P M

    2011-01-01

    Carpal instability can be understood as a disturbed anatomical alignment between bones articulating in the carpus. This disturbed balance occurs either only dynamically (with movement) under the effect of physiological force or even statically at rest. The most common cause of carpal instability is wrist trauma with rupture of the stabilizing ligaments and adaptive misalignment following fractures of the radius or carpus. Carpal collapse plays a special role in this mechanism due to non-healed fracture of the scaphoid bone. In addition degenerative inflammatory alterations, such as chondrocalcinosis or gout, more rarely aseptic bone necrosis of the lunate or scaphoid bones or misalignment due to deposition (Madelung deformity) can lead to wrist instability. Under increased pressure the misaligned joint surfaces lead to bone arrosion with secondary arthritis of the wrist. In order to arrest or slow down this irreversible process, diagnosis must occur as early as possible. Many surgical methods have been thought out to regain stability ranging from direct reconstruction of the damaged ligaments, through ligament replacement to partial stiffening of the wrist joint.

  20. 75 FR 32855 - Safety Zone; Pierce County, WA, Department of Emergency Management, Regional Water Exercise

    Science.gov (United States)

    2010-06-10

    ... Management, Regional Water Exercise AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Pierce County, Washington, Department of Emergency Management is sponsoring a Regional Water Rescue... County, Washington, Department of Emergency Management is sponsoring a Regional Water Rescue Exercise...

  1. Pierce's Memorandum Account Book Designed for Farmers, Mechanics, and All People

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a memorandum account book containing advertisements for medications developed by Dr. R.V. Pierce, former owner of St. Vincent Island.

  2. Pierce and Franz Lake National Wildlife Refuges: Narrative Report: 1991: Calendar Year

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report for Pierce National Wildlife Refuge outlines Refuge accomplishments for the 1991 calendar year. The report begins by giving Refuge highlights...

  3. FINANCIAL INSTABILITY AND POLITICAL INSTABILITY

    Directory of Open Access Journals (Sweden)

    Ionescu Cristian

    2012-12-01

    Full Text Available There is an important link between the following two variables: financial instability and political instability. Often, the link is bidirectional, so both may influence each other. This is way the lately crisis are becoming larger and increasingly complex. Therefore, the academic environment is simultaneously talking about economic crises, financial crises, political crises, social crises, highlighting the correlation and causality between variables belonging to the economic, financial, political and social areas, with repercussions and spillover effects that extend from one area to another. Given the importance, relevance and the actuality of the ones described above, I consider that at least a theoretical analysis between economic, financial and political factors is needed in order to understand the reality. Thus, this paper aims to find links and connections to complete the picture of the economic reality.

  4. Instantaneous mechanical fastening of quasi-isotropic CFRP laminates by a self-piercing rivet

    OpenAIRE

    上田, 政人; 三宅, 崇太郎; 長谷川, 寛幸; 平野, 義鎭; Ueda, Masahito; Miyake, Sotaro; Hasegawa, Hiroyuki; Hirano, Yoshiyasu

    2012-01-01

    A modified self-piercing rivet (SPR) has been proposed to mechanically fasten CFRP laminates. The modified SPR consists of a rivet body and two flat washers. The two flat washers were used to suppress delamination in the CFRP laminates at the point of piercing. The advantages of the modified SPR for fastening CFRP laminates are instantaneous process time and low cost. Any pretreatments such as surface treatments or hole drilling are not required. In this study, the viability of the modified S...

  5. A Simulation for the Punchless Piercing Process using Lemaitre Damage Model

    Science.gov (United States)

    Lee, Sang Wook; Pourboghrat, Farhang

    2005-08-01

    The punchless piercing is a process that uses highly pressurized fluid instead of the conventional punch to make holes into the sheet metal. This process has many advantages over the conventional method for piercing various shaped holes into very thin strips of metal, composite, etc. An important cost advantage comes from not having to use a punch. Another important advantage comes from the top quality of pierced holes produced by punchless piercing, as no secondary finishing process will be needed for removing burrs typically found in conventional cutting processes. The ABAQUS/Explicit FEM code coupled with Lemaitre damage model has been used to more precisely characterize the punchless piercing process. The formulation adopted for this purpose focuses on the development of an efficient stress integration algorithm and development of a user material subroutine (VUMAT). For verification, the computed results have been compared with those of the experimental results in the literature and shown to be in good agreement with each other. The results obtained from this work are expected to be of significant interest to automotive and aerospace industries interested in using the punchless piercing process.

  6. Profile of oral piercing users and implications resulting from its use

    Directory of Open Access Journals (Sweden)

    Jeferson da Costa Marchiori

    2009-01-01

    Full Text Available Objective: To identify the profile of oral piercing users and the possible implications resulting from its use, as well as explaining to dentists about the possible consequences to their patients as a result of wearing this type of jewelry in the oral region.Methods: Fifty-one oral piercing users were interviewed. They were aged between 18 and 42 year, from different social classes, and resident in the city of Santa Maria, Rio Grande do Sul, Brazil.Results: Based on the questionnaires analyzed, the majority of users had tongue or lip piercing as a way to express identity, and 45% reported the occurrence of some type of oral and/or general alteration associated with the use of piercings. Conclusion: The majority of alterations are harmful to the piercing user’s health, therefore, professionals in the Dentistry area must be warnedto explain to their patients, who use oral piercings, about the consequences that may occur and the need for special care to ameliorate these problems.

  7. Modified Contact Line Dynamics about a Surface-Piercing Hydrofoil

    Science.gov (United States)

    Grivel, Morgane; Jeon, David; Gharib, Morteza

    2016-11-01

    The contact line around a surface-piercing hydrofoil is modified by introducing alternating hydrophobic and hydrophilic bands along one side of the body. These bands are either aligned perpendicular or parallel to the flow direction. The other side of the hydrofoil is un-patterned and retains its original, uniformly hydrophilic properties. The hydrofoil is mounted onto air bearings, such that it can freely move side-to-side in the water tunnel. A force sensor is attached to the setup via a universal joint in order to measure the forces acting on the body for several Reynolds numbers (ranging from 104 to 105) and angles of attack (ranging from -10o to 10o) . Cameras are also used to record the resulting flow structures and free surface elevation. The generation of wave trains and an altered free-surface elevation (also associated with the generation of surface waves) are observed over a wide range flow conditions. Force measurements elucidate how introducing these flow features impacts the forces acting on the hydrofoil, specifically with regards to the generation of lateral forces due to the asymmetric wetting conditions on either side of the hydrofoil. Work is funded by ONR Grant N00014-11-1-0031 and NSF GRFP Grant DGE-1144469.

  8. Nonlinear diffraction effects around a surface-piercing structure

    Energy Technology Data Exchange (ETDEWEB)

    Lalli, F.; Mascio, A. Di; Landrini, M. [Istituto Nazionale per Studi ed Esperienze di Architettura Navale, Rome (Italy)

    1995-12-31

    In the present paper the interaction of a wave system with a submerged or surface piercing body is studied. The wave diffraction caused by a cylinder in finite depth water and by a shoal is been computed and the results are compared with analytical solutions and experimental data. The problem is analyzed numerically in the frame of irrotational incompressible flow hypothesis. Both the linearized and the fully nonlinear mathematical models are studied. The numerical solution is gained by means of a mixed panel-desingularized formulation. An explicit time-marching algorithm updates the wave elevation and the potential at the free surface. In all cases, the numerical simulation mirrors the experimental data. In the case of the diffraction around a cylinder, the simulation confirms and extends the theoretical results of the second order analysis (Kriebel 1990, 1992): the linear model yields a very good estimation of the force amplitude acting on the body, while the wave profiles are poorly predicted when compared with the fully nonlinear simulation and the experimental data.

  9. Prevalence of tattooing and body piercing in Germany and perception of health, mental disorders, and sensation seeking among tattooed and body-pierced individuals.

    Science.gov (United States)

    Stirn, Aglaja; Hinz, Andreas; Brähler, Elmar

    2006-05-01

    The objective of this study was to obtain data on the incidence and relationship of psychological factors to tattooing and body piercing from a large and representative sample of German citizens (N=2043). Representative data (sample age range=14-93 years) were evaluated with respect to health-related quality of life (SF-36), mental health (General Health Questionnaire), mental disorders (Patient Health Questionnaire), and sensation seeking (Arnett Inventory of Sensation Seeking). The prevalence of tattooing and that of body piercing in the general German population are 8.5% and 6.5%, respectively. Individuals aged between 14 and 24 years display the highest rate of body piercings or tattoos (females, 41%; males, 27%). Within the group of individuals aged between 14 and 44 years, unemployment and nonaffiliation to a church are positively correlated, tattooing is significantly correlated with the perception of reduced mental health, and both tattooing and body piercing are correlated with significantly increased sensation-seeking behavior. Next to being motivated by fashion and the urge to fit in with one's peers, the major reasons for body modification practices in the German population appear to be negatively perceived conditions of life, reduced social integration, and increased sensation-seeking behavior.

  10. Pericondrite por piercing: relato de casos e revisão da literatura Ear piercing perichondritis: case reports and literature review

    Directory of Open Access Journals (Sweden)

    Ernesto N. Takahashi

    2004-10-01

    Full Text Available A pericondrite é uma infecção que envolve o pericôndrio do pavilhão auricular. Desencadeada pelo piercing, é secundária a uma reação alérgica ao níquel. O diagnóstico é essencialmente clínico, porém a realização de cultura e antibiograma é fundamental. Os patógenos freqüentemente envolvidos são germes Gram negativos (Pseudomonas aeruginosa. Os autores apresentam 3 casos de pericondrite por piercing atendidos no ambulatório de otorrinolaringologia e realizam uma revisão da literatura.Auricular perichondritis is a complication related to ear piercing, caused by the hypersensitivity to nickel. The diagnosis is essentially based on clinical findings. The most pathogen frequently involved is Pseudomonas aeruginosa. Culture is important to determine the antibiotic susceptibility. We report 3 cases of ear piercing associated perichondritis and present a literature review.

  11. Piercing of Consciousness as a Threshold-Crossing Operation.

    Science.gov (United States)

    Kang, Yul H R; Petzschner, Frederike H; Wolpert, Daniel M; Shadlen, Michael N

    2017-08-07

    Many decisions arise through an accumulation of evidence to a terminating threshold. The process, termed bounded evidence accumulation (or drift diffusion), provides a unified account of decision speed and accuracy, and it is supported by neurophysiology in human and animal models. In many situations, a decision maker may not communicate a decision immediately and yet feel that at some point she had made up her mind. We hypothesized that this occurs when an accumulation of evidence reaches a termination threshold, registered, subjectively, as an "aha" moment. We asked human participants to make perceptual decisions about the net direction of dynamic random dot motion. The difficulty and viewing duration were controlled by the experimenter. After indicating their choice, participants adjusted the setting of a clock to the moment they felt they had reached a decision. The subjective decision times (tSDs) were faster on trials with stronger (easier) motion, and they were well fit by a bounded drift-diffusion model. The fits to the tSDs alone furnished parameters that fully predicted the choices (accuracy) of four of the five participants. The quality of the prediction provides compelling evidence that these subjective reports correspond to the terminating process of a decision rather than a post hoc inference or arbitrary report. Thus, conscious awareness of having reached a decision appears to arise when the brain's representation of accumulated evidence reaches a threshold or bound. We propose that such a mechanism might play a more widespread role in the "piercing of consciousness" by non-conscious thought processes. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  12. Self-Pierce Riveting Through 3 Sheet Metal Combinations

    Science.gov (United States)

    Andersson, Roger; Jonason, Paul; Pettersson, Tommy

    2011-05-01

    One way to reduce the CO2 emissions in automotives is to reduce the weight of the Body-In-White. One easy to achieve the weight reduction is to replace steel sheet materials with Al alloys, which is 3 times lighter. One issue is the joining process, especially with combinations between steel grades and AL alloys. Example of combination of mixed material combinations (Al-steel) might be found in the door structure. The reason is because of the AL alloys worthier crash performance so the automotive manufacturer might want to use crash impact beams made by high strength steels in a AL intensive door structure. The joining process between aluminum and steel are problematic due it's not possible to use traditional spot-welding technologies due to the materials total difference in microstructure characteristics as well thermal properties. To overcome this issue then mechanical as well adhesion joining are frequently used. This paper describes a development process and subsequently analysis of a self-pierce rivet (SPR) process between 3 sheet metal combinations. The multi-material combinations in this study were a combination of ultra high strength steels sheets (DP1000) and a Al-alloy (AA 6014). The analysis of the SPR process, in sense of mechanical strengths, has been done by peel- and shear tests. To reduce the amount of future physical tests a virtual FE-model has been developed for the process. This FE model of the process has been subsequently used to analyze the mechanical strength during plastic deformation. By using inverse analysis a correct contact algorithm has been evaluated that would predict the binding force between the rivet and sheet under a deformation process. With this new virtual model it will not only possible to analyze and develop the SPR process but also to achieve the final strength of the joint.

  13. On the evaluation of Pierce parameters C and Q in a traveling wave tube

    Science.gov (United States)

    Simon, D. H.; Wong, P.; Chernin, D.; Lau, Y. Y.; Hoff, B.; Zhang, P.; Dong, C. F.; Gilgenbach, R. M.

    2017-03-01

    A study of an exactly solvable model of a traveling wave tube (TWT) shows that Pierce gain parameter C and space charge parameter Q generally depend on wavenumber k in addition to frequency ω. The choice of k at which C and Q are evaluated may strongly affect their values and, consequently, the values of the small signal gain obtained from 3- and 4-wave Pierce theory. In order to illustrate this effect, we calculate the spatial amplification rate, ki, from the exact dispersion relation for a dielectric TWT model which is exactly solvable. We compare this exact value of ki with approximate values obtained from Pierce's classical 3-wave and 4-wave dispersion relations, obtained by making various assumptions on k in the evaluation of C and Q. We find that the various ways to approximate C and Q will have a significant influence on the numerical values of ki. For our dielectric TWT example, Pierce's 4-wave TWT dispersion relation generally yields the most accurate values of ki if Q is evaluated for k = ω/v0, where v0 is the beam velocity, and if the complete frequency and wavelength dependence of C is retained. Pierce's 3-wave theory also yields accurate values of ki using a different form of Q from the 4-wave theory. The implications of this result for TWT design are explored.

  14. Fatigue Behaviors of Self-Piercing Rivets Joining Similar and Dissimilar Sheet Metals

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2007-01-01

    This paper summarizes the fatigue test results of self-piercing rivet (SPR) joints between similar and dissimilar sheet metals. The influences of material grades, material thickness, piercing direction and the use of structural adhesive on the rivet samples’ fatigue behaviors were investigated. Fatigue test results indicate that SPR joints have superior fatigue strength than resistance spot weld (RSW) joints for the same material combinations. The application of structure adhesive also significantly enhances the fatigue strength of the joint samples; this is particularly true for the lap shear loading configuration. In addition, different piercing directions for SPR joints have a noticeable effect on the static and fatigue strength of the joints. The joint fatigue results presented in this paper can offer design engineers with the durability data for SPR joints with these material combinations. Moreover, it will provide manufacturing engineers with some insights on the effects of different manufacturing parameters on the strength and durability of these joints.

  15. Performance of nursing auxiliaries and technicians in managing piercing cutting material: a necessary study.

    Science.gov (United States)

    Moura, Elaine Cristina Carvalho; Moreira, Maria de Fátima Santana; da Fonseca, Soraia Martins

    2009-01-01

    This study aimed to analyze the knowledge of nursing auxiliaries and technicians in handling and disposing of piercing-cutting material and describe their performance. This qualitative-descriptive research was carried out with three nursing auxiliaries and 12 technicians at a medium-size hospital, totaling 15 participants interviewed through a semi-structured script. Discourse was analyzed through the content analysis technique. Results appoint that, even though the participants have theoretical knowledge on the management of piercing-cutting material, they do not totally follow their knowledge, which exposes them to several biological risks, revealing reproductive knowledge and performance. Thus, we propose the implementation of continuing education programs based on constructivist methodological approach aiming at effective practices in the management and disposal of piercing-cutting material. In this perspective, research clarifying how adults apprehend knowledge can deepen the results described in the study.

  16. Online visual inspection of self-piercing riveting to determine the quality of the mechanical interlock

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, P; Cullen, J D; Al-Shamma' a, A I; Shaw, A [Liverpool John Moores University General Engineering Research Institute, RF and Microwave Group, Byrom Street, Liverpool, L3 3AF (United Kingdom)

    2007-07-15

    Self-piercing riveting (SPR) has become a significant joining technique for the automotive applications of aluminium sheets. Quality control in this locale has progressed at an altogether more leisurely rate than other areas of mechanical joining (e.g. spotweld) and is underdeveloped. Testing the quality mechanical interlock is often achieved by destructive testing, which results in material and time wastage. The solution is online monitoring of the self-piercing riveting process to provide non-destructive testing of the mechanical interlock. Introducing sensors into the process facilitates real time data acquisition, which can be used to determine the quality of the joint.

  17. 3D finite elements method (FEM Analysis of basic process parameters in rotary piercing mill

    Directory of Open Access Journals (Sweden)

    Z. Pater

    2012-10-01

    Full Text Available In this paper 3D FEM analysis of process parameters and its infl uence in rotary piercing mill is presented. The FEM analyze of the rotary piercing process was made under the conditions of 3D state of strain with taking into consideration the thermal phenomena. The calculations were made with application of different rolls’ skew angles and different plug designs. In the result, progression of shapes, temperature and distributions of stress and strain were characterized. The numerical results of calculations were compared with results of stand test with use of 100Cr6 steel. The comparisons of numerical and experimental tests confirm good agreement between obtained results.

  18. A Commentary on "Piercing the Bubble": Should Management Education "Confront" Poverty?

    Science.gov (United States)

    Dart, Raymond

    2008-01-01

    This commentary contrasts "Piercing the Bubble" by proposing "pull" (rather than "push") strategies as a way for business schools to more meaningfully engage poverty and social exclusion. By reframing poverty issues in such a manner that they connect with core business student interests of career opportunities, current management practices, and…

  19. 27 CFR 478.148 - Armor piercing ammunition intended for sporting or industrial purposes.

    Science.gov (United States)

    2010-04-01

    ... intended for sporting or industrial purposes. 478.148 Section 478.148 Alcohol, Tobacco Products, and... ammunition intended for sporting or industrial purposes. The Director may exempt certain armor piercing... for any such ammunition which is primarily intended for sporting purposes or intended for...

  20. An efficient domain decomposition strategy for wave loads on surface piercing circular cylinders

    DEFF Research Database (Denmark)

    Paulsen, Bo Terp; Bredmose, Henrik; Bingham, Harry B.

    2014-01-01

    A fully nonlinear domain decomposed solver is proposed for efficient computations of wave loads on surface piercing structures in the time domain. A fully nonlinear potential flow solver was combined with a fully nonlinear Navier–Stokes/VOF solver via generalized coupling zones of arbitrary shape...

  1. Improving Immunization Coverage in a Rural School District in Pierce County, Washington

    Science.gov (United States)

    Peterson, Robin M.; Cook, Carolyn; Yerxa, Mary E.; Marshall, James H.; Pulos, Elizabeth; Rollosson, Matthew P.

    2012-01-01

    Washington State has some of the highest percentages of school immunization exemptions in the country. We compared school immunization records in a rural school district in Pierce County, Washington, to immunization records in the state immunization information system (IIS) and parent-held records. Correcting school immunization records resulted…

  2. Pierce Butler's "An Introduction to Library Science: A Tract for Our Times? A Review Article

    Science.gov (United States)

    Cronin, Blaise

    2004-01-01

    Considers the historic and contemporary import of Pierce Butler's "An Introduction to Library Science". Characterizes the content of each chapter and critically analyses the central theses. Relates Butler's positivistic premises, assumptions and conclusions to the congeries of competing epistemological and ideological standpoints that defines…

  3. Application of Hard Coatings for Improved Tribological Performance of Blanking and Piercing Tools

    DEFF Research Database (Denmark)

    Podgornik, B.; Zajec, B.; Bay, Niels

    2010-01-01

    /piercing applications, even on softer tool steels, thus leading to reduced friction and wear as well as to lower costs of the tool. However, preparation of the substrate material and good coating to substrate adhesion are crucial. On the other hand, even with the use of low friction coating (DLC) stamping force exceeds...

  4. Improving Immunization Coverage in a Rural School District in Pierce County, Washington

    Science.gov (United States)

    Peterson, Robin M.; Cook, Carolyn; Yerxa, Mary E.; Marshall, James H.; Pulos, Elizabeth; Rollosson, Matthew P.

    2012-01-01

    Washington State has some of the highest percentages of school immunization exemptions in the country. We compared school immunization records in a rural school district in Pierce County, Washington, to immunization records in the state immunization information system (IIS) and parent-held records. Correcting school immunization records resulted…

  5. A Commentary on "Piercing the Bubble": Should Management Education "Confront" Poverty?

    Science.gov (United States)

    Dart, Raymond

    2008-01-01

    This commentary contrasts "Piercing the Bubble" by proposing "pull" (rather than "push") strategies as a way for business schools to more meaningfully engage poverty and social exclusion. By reframing poverty issues in such a manner that they connect with core business student interests of career opportunities, current management practices, and…

  6. Lifestyle and nickel allergy in a Swedish adolescent population: effects of piercing, tattooing and orthodontic appliances.

    Science.gov (United States)

    Fors, Ronny; Persson, Maurits; Bergström, Erik; Stenlund, Hans; Stymne, Birgitta; Stenberg, Berndt

    2012-11-01

    The aim of this study was to estimate the prevalence of life-style practices in adolescents and their association with nickel allergy. Upper secondary school pupils (n = 4,376; 15-23 years) were patch-tested for nickel aller-gy, follow-ing completion of a questionnaire (answered by 6,095). Almost 86% girls and 21% of boys reported piercing. More girls (6%) than boys (3%) had a tattoo. Twenty-six percent of the girls and 18% of the boys were regular smokers. Vegetarian/vegan diets were reported by 20% of girls and by 6% of boys. Piercing, female gender, and vocational programme increased the risk of nickel allergy, whereas orthodontic appliance treat-ment prior to piercing reduced the risk of nickel allergy. Pupils in vocational programmes had the highest prevalence of nickel allergy. Lifestyle behaviours are interconnected and cluster in subgroups of adolescents. Female sex, piercing and choice of educational programme are prominent lifestyle markers. A trend shift is observed, where more girls than boys report tattooing.

  7. Process Monitoring and Fault Diagnosis for Piercing Production of Seamless Tube

    Directory of Open Access Journals (Sweden)

    Dong Xiao

    2016-01-01

    Full Text Available With the development of modernization, the application of seamless tube becomes widespread. As the first process of seamless tube, piercing is vital for the quality of the tube. The solid round billet will be transformed into a hollow shell after the piercing process. The defects of hollow shell cannot be cleared in the following process, so a monitoring model for the quality of the hollow shell is important. But the piercing process is very complicated, and a mechanism model is difficult to build between the qualities of the hollow shell and measurement variables. Furthermore, an intelligent model is needed. We established two piercing process monitoring and fault diagnosis models based on the multiway principal component analysis (MPCA model and the multistage MPCA model, respectively, and furthermore we made a comparison between these two concepts. We took three ways to divide the period based on process, K-means, and GA, respectively. Simulation experiments have shown that the multistate MPCA method has advantage over the MPCA method and the model based on the genetic algorithm (GA can monitor the process effectively and detect the faults.

  8. Franklin Pierce College's Fire Department: 17 Student Volunteers and a Vintage Engine.

    Science.gov (United States)

    Meyer, Thomas J.

    1985-01-01

    Seventeen student volunteers form the Franklin Pierce College Fire Department. When the firefighters are on duty, they must carry electronic pagers at all times. They also participate in dormitory inspections and attend weekend sessions at a local firefighters' training school. (MLW)

  9. Pierce Butler's "An Introduction to Library Science: A Tract for Our Times? A Review Article

    Science.gov (United States)

    Cronin, Blaise

    2004-01-01

    Considers the historic and contemporary import of Pierce Butler's "An Introduction to Library Science". Characterizes the content of each chapter and critically analyses the central theses. Relates Butler's positivistic premises, assumptions and conclusions to the congeries of competing epistemological and ideological standpoints that defines…

  10. Are Tattooing and Body Piercing Indicators of Risk-Taking Behaviours among High School Students?

    Science.gov (United States)

    Deschesnes, Marthe; Fines, Phillipe; Demers, Stephanie

    2006-01-01

    Purpose: To date, studies pertaining to possible links between body modification and risk-taking behaviours have been conducted mainly among targeted groups. The objective of this study is to examine the influence of a number of risk-taking behaviours on the probability of being pierced or tattooed among a general adolescent population. Methods:…

  11. Intrinsic Motivation and Extrinsic Rewards: A Commentary on Cameron and Pierce's Meta-Analysis.

    Science.gov (United States)

    Lepper, Mark R.; And Others

    1996-01-01

    Provides a critical analysis of the meta-analysis of J. Cameron and W. D. Pierce (1994) of the experimental literature on the effects of extrinsic rewards on intrinsic motivation. Their overly simplistic conclusion has little theoretical or practical value and results from misuse of meta-analytic procedures. (SLD)

  12. The incidence of complications associated with lip and/or tongue piercings: a systematic review

    NARCIS (Netherlands)

    Hennequin-Hoenderdos, N.L.; Slot, D.E.; Van der Weijden, G.A.

    2016-01-01

    Objective: This review determines the incidence of complications associated with lip and/or tongue piercings based on a systematic evaluation of the available literature. Material and Methods: MEDLINE–PubMed, Cochrane-CENTRAL and EMBASE databases were comprehensively searched through June 2014 to id

  13. People with multiple tattoos and/or piercings are not at increased risk for HBV or HCV in The Netherlands.

    Directory of Open Access Journals (Sweden)

    Anouk T Urbanus

    Full Text Available BACKGROUND: Although published results are inconsistent, it has been suggested that tattooing and piercing are risk factors for HBV and HCV infections. To examine whether tattooing and piercing do indeed increase the risk of infection, we conducted a study among people with multiple tattoos and/or piercings in The Netherlands who acquired their tattoos and piercings in The Netherlands and/or abroad. METHODS: Tattoo artists, piercers, and people with multiple tattoos and/or piercings were recruited at tattoo conventions, shops (N = 182, and a biannual survey at our STI-outpatient clinic (N = 252 in Amsterdam. Participants were interviewed and tested for anti-HBc and anti-HCV. Determinants of HBV and HCV infections were analysed using logistic regression analysis. RESULTS: The median number of tattoos and piercings was 5 (IQR 2-10 and 2 (IQR 2-4, respectively. Almost 40% acquired their tattoo of piercing abroad. In total, 18/434 (4.2%, 95%CI: 2.64%-6.46% participants were anti-HBc positive and 1 was anti-HCV positive (0.2%, 95%CI: 0.01%-1.29%. Being anti-HBc positive was independently associated with older age (OR 1.68, 95%CI: 1.03-2.75 per 10 years older and being born in an HBV-endemic country (OR 7.39, 95%CI: 2.77-19.7. Tattoo- and/or piercing-related variables, like having a tattoo or piercing in an HBV endemic country, surface percentage tattooed, number of tattoos and piercings etc., were not associated with either HBV or HCV. CONCLUSIONS: We found no evidence for an increased HBV/HCV seroprevalence among persons with multiple tattoos and/or piercings, which might be due to the introduction of hygiene guidelines for tattoo and piercing shops in combination with the low observed prevalence of HBV/HCV in the general population. Tattoos and/or piercings, therefore, should not be considered risk factors for HBV/HCV in the Dutch population. These findings imply the importance of implementation of hygiene guidelines in other countries.

  14. Electron heat flux instability

    Science.gov (United States)

    Saeed, Sundas; Sarfraz, M.; Yoon, P. H.; Lazar, M.; Qureshi, M. N. S.

    2017-02-01

    The heat flux instability is an electromagnetic mode excited by a relative drift between the protons and two-component core-halo electrons. The most prominent application may be in association with the solar wind where drifting electron velocity distributions are observed. The heat flux instability is somewhat analogous to the electrostatic Buneman or ion-acoustic instability driven by the net drift between the protons and bulk electrons, except that the heat flux instability operates in magnetized plasmas and possesses transverse electromagnetic polarization. The heat flux instability is also distinct from the electrostatic counterpart in that it requires two electron species with relative drifts with each other. In the literature, the heat flux instability is often called the 'whistler' heat flux instability, but it is actually polarized in the opposite sense to the whistler wave. This paper elucidates all of these fundamental plasma physical properties associated with the heat flux instability starting from a simple model, and gradually building up more complexity towards a solar wind-like distribution functions. It is found that the essential properties of the instability are already present in the cold counter-streaming electron model, and that the instability is absent if the protons are ignored. These instability characteristics are highly reminiscent of the electron firehose instability driven by excessive parallel temperature anisotropy, propagating in parallel direction with respect to the ambient magnetic field, except that the free energy source for the heat flux instability resides in the effective parallel pressure provided by the counter-streaming electrons.

  15. Evaluating shoulder instability treatment

    NARCIS (Netherlands)

    van der Linde, J.A.

    2016-01-01

    Shoulder instability common occurs. When treated nonoperatively, the resulting societal costs based on health care utilization and productivity losses are significant. Shoulder function can be evaluated using patient reported outcome measurements (PROMs). For shoulder instability, these include the

  16. Jeans instability in superfluids

    Energy Technology Data Exchange (ETDEWEB)

    Hason, Itamar; Oz, Yaron [Tel-Aviv University, Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv (Israel)

    2014-11-15

    We analyze the effect of a gravitational field on the sound modes of superfluids. We derive an instability condition that generalizes the well-known Jeans instability of the sound mode in normal fluids. We discuss potential experimental implications. (orig.)

  17. Relativistic Gravothermal Instabilities

    CERN Document Server

    Roupas, Zacharias

    2014-01-01

    The thermodynamic instabilities of the self-gravitating, classical ideal gas are studied in the case of static, spherically symmetric configurations in General Relativity taking into account the Tolman-Ehrenfest effect. One type of instabilities is found at low energies, where thermal energy becomes too weak to halt gravity and another at high energies, where gravitational attraction of thermal pressure overcomes its stabilizing effect. These turning points of stability are found to depend on the total rest mass $\\mathcal{M}$ over the radius $R$. The low energy instability is the relativistic generalization of Antonov instability, which is recovered in the limit $G\\mathcal{M} \\ll R c^2$ and low temperatures, while in the same limit and high temperatures, the high energy instability recovers the instability of the radiation equation of state. In the temperature versus energy diagram of series of equilibria, the two types of gravothermal instabilities make themselves evident as a double spiral! The two energy l...

  18. Design of Helical Self-Piercing Rivet for Joining Aluminum Alloy and High-Strength Steel Sheets

    Energy Technology Data Exchange (ETDEWEB)

    Kim, W. Y.; Kim, D. B.; Park, J. G; Kim, D. H.; Kim, K. H.; Lee, I. H.; Cho, H. Y. [Chungbuk National University, Cheongju (Korea, Republic of)

    2014-07-15

    A self-piercing rivet (SPR) is a mechanical component for joining dissimilar material sheets such as those of aluminum alloy and steel. Unlike conventional rivets, the SPR directly pierces sheets without the need for drilling them beforehand. However, the regular SPR can undergo buckling when it pierces a high-strength steel sheet, warranting the design of a helical SPR. In this study, the joining and forging processes using the helical SPR were simulated using the commercial FEM code, DEFORM-3D. High-tensile-strength steel sheets of different strengths were joined with aluminum alloy sheets using the designed helical SPR. The simulation results were found to agree with the experimental results, validating the optimal design of a helical SPR that can pierce high-strength steel sheets.

  19. Defectos mucogingivales severos y problemas del habla como secuelas de la colocacion de un Piercing intraoral: reporte de caso

    National Research Council Canada - National Science Library

    Villarreal, Minerva; Garza, Gabriela; Trevino, Guadalupe; Rivera, Gerardo; Martinez, Hector

    2011-01-01

    Despues que un piercing es colocado dentro de la cavidad oral, varios problemas han sido descritos incluyendo dolor, sangrado, obstruccion de las vias aereas y dano de la mucosa o de la superficie dental...

  20. Steigerwald Lake National Wildlife Refuge, Franz Lake National Wildlife Refuge, and Pierce National Wildlife Refuge: Comprehensive Conservation Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Comprehensive Conservation Plan (CCP) was written to guide management on Steigerwald Lake NWR, Franz Lake NWR, and Pierce NWR for the next 15 years. This plan...

  1. ["My body belongs to me"--cultural history and psychology of piercings and tattoos].

    Science.gov (United States)

    Stirn, A

    2007-02-01

    At present tattoos and piercings can no longer be regarded as destructive acts of self mutilation practized by fringe groups. Body modifications (BMs) are found in virtually all preindustrial cultures and have their roots in ancient myths and magical rituals. The prevalence of tattoos and piercings in the German population is 8.5% and 6.8%, respectively. Unemployed young men and young women who do not live in a firm partnership show particularly high prevalences. The incidence of BMs correlates positively with the personality trait "sensation seeking", particularly in young women. BMs often serve to express individuality and identity, and they also reflect changed attitude towards the human body and body art as well as following fashion trends. However, BMs can also provide valuable diagnostic indications for identity search and risk taking behaviour.

  2. Adverse Effects of Tattoos and Piercing on Parent/Patient Confidence in Health Care Providers.

    Science.gov (United States)

    Johnson, Scarlett C; Doi, Maegan L M; Yamamoto, Loren G

    2016-09-01

    First impressions based on practitioner appearance often form the basis for preliminary assumptions regarding trust, confidence, and competence, especially in situations where patients or family members do not have an established relationship with the physician. Given their growing prevalence, we strove to further investigate whether visible tattoos or piercings on a medical provider affects a patient's perception of the provider's capabilities and their trust in the care that would be provided. A survey using photographs of simulated practitioners was administered to 314 participants split between rural and urban locations. Study volunteers rated tattooed practitioners with lower confidence ratings when compared with nontattooed practitioners and reported greater degrees of discomfort with greater degrees of facial piercing. We concluded that these factors adversely affect the clinical confidence ratings of practitioners, regardless of the gender, age group, or location of participants.

  3. Characterization of Coatings on Steel Self-Piercing Rivets for Use with Magnesium Alloys

    Science.gov (United States)

    McCune, Robert C.; Forsmark, Joy H.; Upadhyay, Vinod; Battocchi, Dante

    Incorporation of magnesium alloys in self-pierce rivet (SPR) joints poses several unique challenges among which are the creation of spurious galvanic cells and aggravated corrosion of adjacent magnesium when coated steel rivets are employed. This work firstly reviews efforts on development of coatings to steel fasteners for the diminution of galvanic corrosion when used with magnesium alloys. Secondly, approaches, based on several electrochemical methods, for the measurement of the galvanic-limiting effect of a number of commercially-available coatings to hardened 10B37 steel self-piercing rivets inserted into alloy couples incorporating several grades of magnesium are reported. Electrochemical impedance spectroscopy (EIS), zero-resistance ammeter (ZRA), corrosion potential and potential-mapping visualization methods (e.g. scanning vibrating electrode technique — SVET) are illustrated for the several rivet coatings considered.

  4. Directors’ Liability under thr Doctrine of Piercing the Corporate Veil : The Directors' Liability for Corporate Debt

    Directory of Open Access Journals (Sweden)

    Laya Joneydi

    2015-05-01

    Full Text Available The doctrine of piercing the corporate veil fascilitated holding directors liable for corporate debt. Nevertheless, the doctrine is not a seperate cause of action. Directors are bound by fiduciary duty, duty of loyalty and duty of care and skill to the corporation and its shareholders. However, there is not such a contractual relationship between directors and creditors. Thus, requiring directors to compensate creditors should be justified on tort law. In the Iranian, French and American legal systems, fault-based liability is the cause of action for directors' liability. The author found that in piercing cases, directors' liability follows the traditional rules of fault-based liability unless specified otherwise by statute as strict liability.

  5. Can Superconducting Cosmic Strings Piercing Seed Black Holes Generate Supermassive Black Holes in the Early Universe?

    CERN Document Server

    Lake, Matthew J

    2015-01-01

    The discovery of a large number of supermassive black holes at redshifts $z> 6$, when the Universe was only nine hundred million years old, has raised the fundamental question of how such massive compact objects could form in a (cosmologically) short time interval. Each of the proposed standard scenarios for black hole formation, involving rapid accretion of seed black holes, or black hole mergers, faces severe theoretical difficulties in explaining the short time formation of supermassive objects. In the present Letter, we propose an alternative scenario for the formation of supermassive black holes in the early Universe in which energy transfer from superconducting cosmic strings, piercing small seed black holes, is the main physical process leading to rapid mass increase. The increase in mass of a primordial seed black hole pierced by two antipodal strings is estimated and it is shown that this increases linearly in time. Due to the high energy transfer rate from the cosmic strings, we find that supermassi...

  6. Influence of rivet to sheet edge distance on fatigue strength of self-piercing riveted aluminium joints

    OpenAIRE

    Li, Dezhi; Han, Li; Thornton, M.; Shergold, M.

    2012-01-01

    Self-piercing riveting (SPR) is one of the main joining methods for lightweight aluminium automotive body structures due to its advantages. In order to further optimise the structure design and reduce the weight but without compromising strength, reduction of redundant materials in the joint flange area can be considered. For this reason, the influence of rivet to sheet edge distance on the fatigue strengths of self-piercing riveted joints was studied. Five edge distances, 5 mm, 6 mm, 8 mm, 1...

  7. Bilateral piercing of anterior scalene muscle by anterior branches of C5 & C6

    Directory of Open Access Journals (Sweden)

    Cankara N

    2009-07-01

    Full Text Available During routine dissection of a 25-year-old male cadaver, we observed C5 and C6 nerve roots pierced anterior scalene muscle bilaterally and then formed the superior trunk of brachial plexus after merging on the anterolateral aspect of the muscle. Suprascapular nerve originated from the superior trunk bilaterally. Knowledge of such variations may be important in the diagnosis of upper limb paresthesias.

  8. Shoulder instability; Schulterinstabilitaeten

    Energy Technology Data Exchange (ETDEWEB)

    Kreitner, Karl-Friedrich [Mainiz Univ. (Germany). Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie

    2014-06-15

    In the shoulder, the advantages of range of motion are traded for the disadvantages of vulnerability to injury and the development of instability. Shoulder instability and the lesion it produces represent one of the main causes of shoulder discomfort and pain. Shoulder instability is defined as a symptomatic abnormal motion of the humeral head relative to the glenoid during active shoulder motion. Glenohumeral instabilities are classified according to their causative factors as the pathogenesis of instability plays an important role with respect to treatment options: instabilities are classified in traumatic and atraumatic instabilities as part of a multidirectional instability syndrome, and in microtraumatic instabilities. Plain radiographs ('trauma series') are performed to document shoulder dislocation and its successful reposition. Direct MR arthrography is the most important imaging modality for delineation the different injury patterns on the labral-ligamentous complex and bony structures. Monocontrast CT-arthrography with use of multidetector CT scanners may be an alternative imaging modality, however, regarding the younger patient age, MR imaging should be preferred in the diagnostic work-up of shoulder instabilities. (orig.)

  9. Near-Surface Boundary Layer Turbulence Along a Horizontally-Moving, Surface-Piercing Vertical Wall

    CERN Document Server

    Washuta, Nathan; Duncan, James H

    2016-01-01

    The complex interaction between turbulence and the free surface in boundary layer shear flow created by a vertical surface-piercing wall is considered. A laboratory-scale device was built that utilizes a surface-piercing stainless steel belt that travels in a loop around two vertical rollers, with one length of the belt between the rollers acting as a horizontally-moving flat wall. The belt is accelerated suddenly from rest until reaching constant speed in order to create a temporally-evolving boundary layer analogous to the spatially-evolving boundary layer that would exist along a surface-piercing towed flat plate. Surface profiles are measured with a cinematic laser-induced fluorescence system and sub-surface velocity fields are recorded using a high-speed planar particle image velocimetry system. It is found that the belt initially travels through the water without creating any significant waves, before the free surface bursts with activity close to the belt surface. These free surface ripples travel away...

  10. Accurate model of electron beam profiles with emittance effects for pierce guns

    Science.gov (United States)

    Zeng, Peng; Wang, Guangqiang; Wang, Jianguo; Wang, Dongyang; Li, Shuang

    2016-09-01

    Accurate prediction of electron beam profile is one of the key objectives of electron optics, and the basis for design of the practical electron gun. In this paper, an improved model describing electron beam in Pierce gun with both space charge effects and emittance effects is proposed. The theory developed by Cutler and Hines is still applied for the accelerating region of the Pierce gun, while the motion equations of the electron beams in the anode aperture and drift tunnel are improved by modifying electron optics theory with emittance. As a result, a more universal and accurate formula of the focal length of the lens for the electron beam with both effects is derived for the anode aperture with finite dimension, and a modified universal spread curve considering beam emittance is introduced in drift tunnel region. Based on these improved motion equations of the electron beam, beam profiles with space charge effects and emittance effects can be theoretically predicted, which are subsequently approved to agree well with the experimentally measured ones. The developed model here is helpful to design more applicable Pierce guns at high frequencies.

  11. Radicinin from Cochliobolus sp. inhibits Xylella fastidiosa, the causal agent of Pierce's Disease of grapevine.

    Science.gov (United States)

    Aldrich, Thomas J; Rolshausen, Philippe E; Roper, M Caroline; Reader, Jordan M; Steinhaus, Matthew J; Rapicavoli, Jeannette; Vosburg, David A; Maloney, Katherine N

    2015-08-01

    The fastidious phytopathogenic bacterium, Xylella fastidiosa, poses a substantial threat to many economically important crops, causing devastating diseases including Pierce's Disease of grapevine. Grapevines (Vitis vinifera L.) planted in an area under Pierce's Disease pressure often display differences in disease severity and symptom expression, with apparently healthy vines growing alongside the dying ones, despite the fact that all the vines are genetic clones of one another. Under the hypothesis that endophytic microbes might be responsible for this non-genetic resistance to X. fastidiosa, endophytic fungi were isolated from vineyard cvs. 'Chardonnay' and 'Cabernet Sauvignon' grown under high Pierce's Disease pressure. A Cochliobolus sp. isolated from a Cabernet Sauvignon grapevine inhibited the growth of X. fastidiosa in vitro. Bioassay-guided isolation of an organic extract of Cochliobolus sp. yielded the natural product radicinin as the major active compound. Radicinin also inhibited proteases isolated from the culture supernatant of X. fastidiosa. In order to assess structure-activity relationships, three semi-synthetic derivatives of radicinin were prepared and tested for activity against X. fastidiosa in vitro. Assay results of these derivatives are consistent with enzyme inactivation by conjugate addition to carbon-10 of radicinin, as proposed previously. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Caracterización de estudiantes de bachillerato que usan piercings en Cali, Colombia

    Directory of Open Access Journals (Sweden)

    Ana Fernanda Jaimes

    2011-11-01

    Full Text Available Objetivo: Conocer en una muestra poblacional de bachilleres entre 6° y 12° de cuatro colegios de Cali, Colombia, dediferentes estratos socioeconómicos, las variables sociodemográficas que los caracterizan y los factores que les motivarona utilizar piercings.Materiales y métodos: Se aplicó una encuesta con 15 preguntas a 219 estudiantes bachilleres que manifestaron tenerpiercings y se realizó una entrevista en profundidad de forma aleatoria a 10% de la muestra.Resultados: De los 2120 estudiantes matriculados en bachillerato en los cuatro colegios de diferentes estratos socialesque cumplieron los criterios de inclusión del estudio, 219 estudiantes (10.3% utilizaban piercings, coincidiendo en losestratos alto, medio y bajo el predominio de su uso en jóvenes varones, a la edad de 16 años, con preferencia para colocárselosen los lóbulos de las orejas y lengua, en los sitios donde los adquirieron.Conclusión: Los factores que influyeron en la decisión de usar los piercings fueron el gusto por estos, mejorar su imagen,la moda y el deseo de explorar nuevas experiencias.

  13. College students with tattoos and piercings: motives, family experiences, personality factors, and perception by others.

    Science.gov (United States)

    Forbes, G B

    2001-12-01

    The motives, family experiences, and personality characteristics of 341 college students with and without tattoos or piercings were studied. Participants completed Lippa's 1991 measures of the Big Five personality factors, a shortened version of the Body Cathexis Scale, a series of questions about their childhood experiences, and questions about risk-taking behaviors. In addition, reasons to have or not have body modifications and the perceptions of people with body modifications were investigated. Of the 116 men and 186 women, 25% and 33%, respectively, had at least one tattoo or body piercing. There were very few differences in the childhood experiences or personality characteristics of people with or without body modifications. Although people with body modifications did not differ from people without modifications on the Big Five personality measures, people without modifications perceived people with modifications as much different from themselves on these measures. These results indicate that tattoos and piercings in college students are associated with significantly more risk-taking behavior, greater use of alcohol and marijuana, and less social conformity. However, the traditional stereotype that body modifications are indicators of social or personal pathology does not describe contemporary college students.

  14. Prevalence and acceptance of tattoos and piercings: a survey of young adults from the southern German-speaking area of Central Europe.

    Science.gov (United States)

    Stieger, Stefan; Pietschnig, Jakob; Kastner, Cornelia K; Voracek, Martin; Swami, Viren

    2010-06-01

    The present study examined the prevalence and acceptance of body piercings and tattoos among a community sample from the southern German-speaking area of Central Europe. A total of 440 respondents completed information about their own body piercings and tattoos and reported whether they would be likely never to have piercings and tattoos in the future. Analyses indicated that 19.8 and 15.2% of respondents had piercings (excluding the earlobe) and tattoos, respectively. Women were more likely to have body piercings than men, but there were no sex differences in tattooing. There were also few sociodemographic differences in piercings and tattoos, and most participants reported being likely to consider body art in the future. These results are considered in relation to prevalence estimates of body art in other Western countries and the associated health risks.

  15. Cavitation Instabilities in Inducers

    Science.gov (United States)

    2006-11-01

    gas handling turbomachines . The fluctuation of the cavity length is plotted in Fig.8 under the surge mode oscillation vi . The major differences...Cavitation Instabilities of Turbomachines .” AIAA Journal of Propulsion and Power, Vol.17, No.3, 636-643. [5] Tsujimoto, Y., (2006), “Flow Instabilities in

  16. Instability in evolutionary games.

    Directory of Open Access Journals (Sweden)

    Zimo Yang

    Full Text Available BACKGROUND: Phenomena of instability are widely observed in many dissimilar systems, with punctuated equilibrium in biological evolution and economic crises being noticeable examples. Recent studies suggested that such instabilities, quantified by the abrupt changes of the composition of individuals, could result within the framework of a collection of individuals interacting through the prisoner's dilemma and incorporating three mechanisms: (i imitation and mutation, (ii preferred selection on successful individuals, and (iii networking effects. METHODOLOGY/PRINCIPAL FINDINGS: We study the importance of each mechanism using simplified models. The models are studied numerically and analytically via rate equations and mean-field approximation. It is shown that imitation and mutation alone can lead to the instability on the number of cooperators, and preferred selection modifies the instability in an asymmetric way. The co-evolution of network topology and game dynamics is not necessary to the occurrence of instability and the network topology is found to have almost no impact on instability if new links are added in a global manner. The results are valid in both the contexts of the snowdrift game and prisoner's dilemma. CONCLUSIONS/SIGNIFICANCE: The imitation and mutation mechanism, which gives a heterogeneous rate of change in the system's composition, is the dominating reason of the instability on the number of cooperators. The effects of payoffs and network topology are relatively insignificant. Our work refines the understanding on the driving forces of system instability.

  17. Treatment of hip instability.

    Science.gov (United States)

    Robbins, G M; Masri, B A; Garbuz, D S; Greidanus, N; Duncan, C P

    2001-10-01

    Instability after total hip arthroplasty is a major source of patient morbidity, second only to aseptic loosening. Certain patient groups have been identified as having a greater risk of instability, including patients undergoing revision arthroplasty as early or late treatment for proximal femoral fractures.

  18. Satisfaction with life, self-esteem and evaluation of mental health in people with tattoos or piercings.

    Science.gov (United States)

    Pajor, Anna J; Broniarczyk-Dyła, Grażyna; Świtalska, Julita

    2015-01-01

    The aim of the study was to determine the level of life satisfaction and the various dimensions of self-esteem of pierced or tattooed people, and evaluate their mental health, compared to those without similar body modifications. The study was conducted on a sample of 449 people aged 16-58 years (mean age 26.7 ± 6.35), of whom 308 had body modifications: tattoo (n = 90), body piercings in places other than the ear lobe (n = 53), or both tattoos and piercings (n = 165). The control group consisted of 141 people without such modifications. The participants completed a questionnaire concerning their socio-demographic status, as well as the following psychological tests: The Satisfaction with Life Scale (SWLS), Multidimensional Self-Esteem Inventory (MSEI) and General Health Questionnaire (GHQ-28). Our findings show no significant differences in terms of life satisfaction between the group with tattoos or piercings and the control group. People with body modifications were characterized by higher self-esteem, with regard to their competence and leadership abilities. They also display fewer symptoms of social impairment and sleep disorders than the control group. Tattoos and piercings should not be considered as indicators of psychopathology.

  19. Pierced Lasso Bundles are a new class of knot-like motifs.

    Directory of Open Access Journals (Sweden)

    Ellinor Haglund

    2014-06-01

    Full Text Available A four-helix bundle is a well-characterized motif often used as a target for designed pharmaceutical therapeutics and nutritional supplements. Recently, we discovered a new structural complexity within this motif created by a disulphide bridge in the long-chain helical bundle cytokine leptin. When oxidized, leptin contains a disulphide bridge creating a covalent-loop through which part of the polypeptide chain is threaded (as seen in knotted proteins. We explored whether other proteins contain a similar intriguing knot-like structure as in leptin and discovered 11 structurally homologous proteins in the PDB. We call this new helical family class the Pierced Lasso Bundle (PLB and the knot-like threaded structural motif a Pierced Lasso (PL. In the current study, we use structure-based simulation to investigate the threading/folding mechanisms for all the PLBs along with three unthreaded homologs as the covalent loop (or lasso in leptin is important in folding dynamics and activity. We find that the presence of a small covalent loop leads to a mechanism where structural elements slipknot to thread through the covalent loop. Larger loops use a piercing mechanism where the free terminal plugs through the covalent loop. Remarkably, the position of the loop as well as its size influences the native state dynamics, which can impact receptor binding and biological activity. This previously unrecognized complexity of knot-like proteins within the helical bundle family comprises a completely new class within the knot family, and the hidden complexity we unraveled in the PLBs is expected to be found in other protein structures outside the four-helix bundles. The insights gained here provide critical new elements for future investigation of this emerging class of proteins, where function and the energetic landscape can be controlled by hidden topology, and should be take into account in ab initio predictions of newly identified protein targets.

  20. Nonlinear helical MHD instability

    Energy Technology Data Exchange (ETDEWEB)

    Zueva, N.M.; Solov' ev, L.S.

    1977-07-01

    An examination is made of the boundary problem on the development of MHD instability in a toroidal plasma. Two types of local helical instability are noted - Alfven and thermal, and the corresponding criteria of instability are cited. An evaluation is made of the maximum attainable kinetic energy, limited by the degree to which the law of conservation is fulfilled. An examination is made of a precise solution to a kinematic problem on the helical evolution of a cylindrical magnetic configuration at a given velocity distribution in a plasma. A numerical computation of the development of MHD instability in a plasma cylinder by a computerized solution of MHD equations is made where the process's helical symmetry is conserved. The development of instability is of a resonance nature. The instability involves the entire cross section of the plasma and leads to an inside-out reversal of the magnetic surfaces when there is a maximum unstable equilibrium configuration in the nonlinear stage. The examined instability in the tore is apparently stabilized by a magnetic hole when certain limitations are placed on the distribution of flows in the plasma. 29 references, 8 figures.

  1. The genus Triozocera Pierce, 1909 (Insecta: Strepsiptera: Corioxenidae) in South America.

    Science.gov (United States)

    Kogan, Marcos; Cook, Jerry L

    2014-03-13

    A new species of Triozocera from the Brazilian Amazon basin was found in a sample of male Strepsiptera from the collection of the Instituto Nacional de Pesquisas da Amazonia (INPA-Manaus, Amazonas, Brazil). Triozocera buehrheimi sp.n. is described and the status of T. paulistana Kogan, 1958, the first strepsipteran described from Brazil, is reviewed, with additional diagnostic characters used to reinstate the species based on comparative analyses to the other three species occurring in southern US, Mexico, and Central America: T. mexicana Pierce, 1909, T. tecpanensis Brailowsky and Márquez, 1974, and T. vernalis Kifune and Brailowsky, 1987. A key to those species is included.

  2. Compositions and Methods for the Treatment of Pierce's Disease

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Goutam (Santa Fe, NM)

    2008-10-07

    Chimeric anti-microbial proteins, compositions, and methods for the therapeutic and prophylactic treatment of plant diseases caused by the bacterial pathogen Xylella fastidiosa are provided. The anti-microbial proteins of the invention generally comprise a surface recognition domain polypeptide, capable of binding to a bacterial membrane component, fused to a bacterial lysis domain polypeptide, capable of affecting lysis or rupture of the bacterial membrane, typically via a fused polypeptide linker. In particular, methods and compositions for the treatment or prevention of Pierce's disease of grapevines are provided. Methods for the generation of transgenic Vitus vinefera plants expressing xylem-secreted anti-microbial chimeras are also provided.

  3. Self-piercing rivets for light-weight body construction; Stanznieten im Karosserieleichtbau

    Energy Technology Data Exchange (ETDEWEB)

    Pilgrim, R. [Boellhoff GmbH, Bielefeld (Germany)

    2000-03-01

    The increasing tendency in the automotive industry to use aluminium, magnesium, sandwich materials, high tensile steel and combinations of these, as well as the need to join metallic materials with plastics calls for the application of new joining techniques. This article describes the technology of self-piercing rivets. (orig.) [German] Der zunehmende Trend in der Automobilindustrie, Leichtmetalle, Sandwich-Materialien, hoeherfesten Stahl und dessen Kombinationen einzusetzen sowie metallische Werkstoffe mit Kunststoffen zu verbinden, erfordert auch neue Fuegetechniken. Der Beitrag beschreibt die Stanzniet-Technik. (orig.)

  4. Piercing mandrel strengthening by surfacing with nickel aluminide-based alloy

    Science.gov (United States)

    Zorin, I. V.; Dubtsov, Yu N.; Sokolov, G. N.; Artem'ev, A. A.; Lysak, V. I.; Elsukov, S. N.

    2017-02-01

    Electrode composite wire (CW) was used for argon-arc surfacing of a thermal-resisting nickel aluminide-based alloy (Ni-Al-Cr-W-Mo-Ta system) on the butt-end surface of the non-water-cooled piercing mandrel. It was shown that multipassing surfacing forms a defect-free deposited metal based on the γ’-Ni3Al phase of various structural origins. Using high-temperature sclerometry and thermal fatigue testing methods, the metal deposited with CW containing ultrafine particle of 0.3-0.4 % wt. WC carbide features increased resistance to thermal and force effects at temperatures up to 1200 °C.

  5. Piercing of nectarless Hemerocallis (Xanthorrhoeaceae) flowers by Xylocopa varipuncta and X. virginica virginica (Apidae)

    OpenAIRE

    Barrows, Edward

    2016-01-01

    The native carpenter bee Xylocopa varipuncta frequently made and re-used piercings in tubular corolla bases of nonnative, nectarless Hemerocallis ‘Stella de Oro’ (Stella de Oro Daylily, HSDO) in the César E. Chávez Memorial Plaza in downtown Sacramento, California. The bees frequently visited HSDO flowers from mid-morning through late afternoon in August 2014 during the 3-yr, severe California drought. Their foraging bouts were up to 10 floral visits, and they were evidently obtaining cell fl...

  6. Labial piercing and localized periodontal destruction - partial periodontal regeneration following periodontal debridement and free gingival graft.

    Science.gov (United States)

    Kapferer, Ines; Hienz, Stefan; Ulm, Christian

    2008-02-01

    Localized periodontal destruction has been reported as a rare complication of intraoral piercings. The purpose of this case report was to illustrate the destructive nature of a lip stud and to describe the successful treatment of this case. The lip stud was removed and supra- and subgingival debridement was performed. Because of a shallow vestibule, the absence of keratinized gingiva, and the strong frenulum insertion at the gingival margins, a free gingival graft was placed. Subsequently the patient demonstrated a significant amount of osseous regeneration and partial coverage of the recession, which has been clinically and radiographically (computed tomography) documented.

  7. Spondylolisthesis and Posterior Instability

    Energy Technology Data Exchange (ETDEWEB)

    Niggemann, P.; Beyer, H.K.; Frey, H.; Grosskurth, D. (Privatpraxis fuer Upright MRT, Koeln (Germany)); Simons, P.; Kuchta, J. (Media Park Klinik, Koeln (Germany))

    2009-04-15

    We present the case of a patient with a spondylolisthesis of L5 on S1 due to spondylolysis at the level L5/S1. The vertebral slip was fixed and no anterior instability was found. Using functional magnetic resonance imaging (MRI) in an upright MRI scanner, posterior instability at the level of the spondylolytic defect of L5 was demonstrated. A structure, probably the hypertrophic ligament flava, arising from the spondylolytic defect was displaced toward the L5 nerve root, and a bilateral contact of the displaced structure with the L5 nerve root was shown in extension of the spine. To our knowledge, this is the first case described of posterior instability in patients with spondylolisthesis. The clinical implications of posterior instability are unknown; however, it is thought that this disorder is common and that it can only be diagnosed using upright MRI.

  8. Instabilities in nuclei

    CERN Document Server

    Csernai, László P; Papp, G

    1995-01-01

    The evolution of dynamical perturbations is examined in nuclear multifragmentation in the frame of Vlasov equation. Both plane wave and bubble type of perturbations are investigated in the presence of surface (Yukawa) forces. An energy condition is given for the allowed type of instabilities and the time scale of the exponential growth of the instabilities is calculated. The results are compared to the mechanical spinodal region predictions. PACS: 25.70 Mn

  9. Prediction of Algebraic Instabilities

    Science.gov (United States)

    Zaretzky, Paula; King, Kristina; Hill, Nicole; Keithley, Kimberlee; Barlow, Nathaniel; Weinstein, Steven; Cromer, Michael

    2016-11-01

    A widely unexplored type of hydrodynamic instability is examined - large-time algebraic growth. Such growth occurs on the threshold of (exponentially) neutral stability. A new methodology is provided for predicting the algebraic growth rate of an initial disturbance, when applied to the governing differential equation (or dispersion relation) describing wave propagation in dispersive media. Several types of algebraic instabilities are explored in the context of both linear and nonlinear waves.

  10. Tatuagem, body piercing e a experiência da dor: emoção, ritualização e medicalização Tattoo, body piercing and the experience of pain: emotion, ritualization and medicalization

    Directory of Open Access Journals (Sweden)

    Vitor Sérgio Ferreira

    2010-06-01

    Full Text Available Configurando uma experiência física que desafia tabus físicos e sociais, a marcação do corpo através da tatuagem e body piercing tem sido bastante explorada no espaço público mediatizado em função das questões da dor voluntária e dos riscos de saúde individual e pública implicados. Ao pânico moral que já envolvia estas práticas, associadas a comportamentos tidos como socialmente desviantes, psico-patológicos ou criminosos, junta-se-lhes outra espécie de pânico social, o «pânico higienista», associado ao receio de contrair doenças infecto-contagiosas, ou de reagir aos materiais ou tintas encarnados. No sentido de ir além destes discursos, este artigo pretende analisar: por um lado, como os consumidores actuais de tatuagem e body piercing lidam com a dor que lhe está associada, que emoções enquadram essa sensação e que estratégias convocam no seu controlo; por outro lado, como é que os produtores de tatuagem e body piercing, perante novas e mais alargadas clientelas, lidam com exigência de disciplinas sanitárias na sua prática profissional. Em termos metodológicos, a informação empírica apresentada no artigo foi obtida em situação de entrevista em profundidade, de natureza biográfica, semi-estruturada na sua preparação e semi-diretiva na sua aplicação, a portadores de corpos multitatuados e multiperfurados, profissionais ou apenas consumidores de tatuagem e body piercing. Quinze entrevistados com diferentes perfis sociais foram recrutados em estúdios de tatuagem e body piercing de Lisboa e arredores, depois de intenso trabalho etnográfico nesses mesmos espaços.Being a physical experience that challenges sensitive and social taboos, body marking with tattoos and body piercing has been fairly explored in the public sphere regarding the issues of voluntary pain and the risks of individual and public health that are involved. Associated with the moral panic that is already linked to these practices

  11. Body Piercing

    Science.gov (United States)

    ... caught on towels but won’t on disposable paper products. Avoid over cleaning. This will likely break down your skin and delay healing. Do NOT use antibacterial ointments because they don’t allow air to ...

  12. The Turbulent Boundary Layer on a Horizontally Moving, Partially Submerged, Surface-Piercing Vertical Wall

    CERN Document Server

    Washuta, Nathan; Duncan, James H

    2016-01-01

    The complex interactions between turbulence and the free surface, including air entrainment processes, in boundary layer shear flows created by vertical surface-piercing plates are considered. A laboratory-scale device was built that utilizes a surface-piercing stainless steel belt that travels in a loop around two vertical rollers, with one length of the belt between the rollers acting as a horizontally-moving flat wall. The belt is operated both as a suddenly-started plate to reproduce boundary layer flow or at steady state in the presence of a stationary flat plate positioned parallel to the belt to create a Couette flow with a free surface. Surface profiles are measured with a cinematic laser-induced fluorescence system in both experiments and air entrainment events and bubble motions are observed with stereo underwater white-light movies in the suddenly started belt experiment. It is found that the RMS surface height fluctuations, $\\eta$, peak near the boundaries of the flows and increase approximately l...

  13. The corrosion resistance of materials used for the manufacture of ear piercing studs

    Energy Technology Data Exchange (ETDEWEB)

    Correa, O. V.; Saiki, M.; Rogero, S. O.; Costa, I.

    2003-07-01

    Nickel containing alloy shave been widely used as substrates for the manufacture of studs used for ear piercing. Unfortunately, nickel has also been related to the development of allergic contact dermatitis caused by skin sensitization due to Ni''2+ ions. Nickel ions can be leached out into the body fluids due to corrosion reactions. Defect free coatings are very difficult to produce, and therefore nickel free materials should be used as substrates of ear piercing studs, although the commercial alloys used usually contain this element. In this study, the corrosion resistance of two kinds of commercial studs prepared with nickel containing substrates and a titanium laboratory made stud was determined in a culture medium. The corrosion resistance of the studs was investigated by means of potentiodynamic polarization tests and electrochemical impedance spectroscopy as a function of immersion time in the culture medium. The elements that leached out into the medium due to corrosion reactions were analyzed by instrumental neutron activation analysis. The surfaces of the commercial gold-coated studs were examined by scanning electron microscopy and analyzed by energy dispersive spectroscopy, both before and after exposure to the culture medium. The cytotoxicity of the tested studs was also determined in the culture medium. (Author) 10 refs.

  14. Ventilation Inception and Washout, Scaling, and Effects on Hydrodynamic Performance of a Surface Piercing Strut

    Science.gov (United States)

    Harwood, Casey; Young, Yin Lu; Ceccio, Steven

    2014-11-01

    High-lift devices that operate at or near a fluid free surface (such as surface-piercing or shallowly-submerged propellers and hydrofoils) are prone to a multiphase flow phenomenon called ventilation, wherein non-condensable gas is entrained in the low-pressure flow, forming a cavity around the body and dramatically altering the global hydrodynamic forces. Experiments are being conducted at the University of Michigan's towing tank using a canonical surface-piercing strut to investigate atmospheric ventilation. The goals of the work are (i) to gain an understanding of the dominant physics in fully wetted, partially ventilated, and fully ventilated flow regimes, (ii) to quantify the effects of governing dimensionless parameters on the transition between flow regimes, and (iii) to develop scaling relations for the transition between flow regimes. Using theoretical arguments and flow visualization techniques, new criteria are developed for classifying flow regimes and transition mechanisms. Unsteady transition mechanisms are described and mapped as functions of the governing non-dimensional parameters. A theoretical scaling relationship is developed for ventilation washout, which is shown to adequately capture the experimentally-observed washout boundary. This material is based upon work supported by the National Science Foundation Graduate Student Research Fellowship under Grant No. DGE 1256260. Support also comes from the Naval Engineering Education Center (Award No. N65540-10-C-003).

  15. Appearance and culture: oral pathology associated with certain "fashions" (tattoos, piercings, etc.).

    Science.gov (United States)

    Chimenos-Küstner, Eduardo; Batlle-Travé, Inés; Velásquez-Rengijo, Sandra; García-Carabaño, Tauca; Viñals-Iglesias, Helena; Roselló-Llabrés, Xavier

    2003-01-01

    Humans are characterized by a compulsive tendency to distinguish themselves from the rest: differences in clothes, hairstyle or "decorative" details are used to this effect, based on highly diverse criteria. Such differentiating practices may be aimed at identification with a certain ideological group, for example, or with a concrete "fashion", and involve the use of jewelry, clothes, unusual attire, hairstyles, mutilations, etc. In this context, the present review addresses certain aspects of mutilation practices from both the general and specifically dental perspectives. Mutations imply permanent or lasting sectioning or lesions of a part of the body, and comprise skeletal deforming, dental mutilations, circumcision, ablation of the clitoris, scarification, tattoos, and perforations (particularly of the soft tissues). In this sense, tattoos and perforations or piercings are popular -- particularly among adolescents. This trend may be interpreted as a form of communication, identity expression, or as a type of body cult (i.e., so-called "body art"). Such mutilating practices reflect different motivations including fashion, rebelliousness, differentiation, sexual motives, the remembering of events, physical sensations, and ethnic or tribal influences. However, these practices can cause complications such as infections, laceration and soft and hard tissue damage, hypersensitivity reactions and other alterations of variable severity. Under these premises, questions are raised concerning the competence of those who perform these mutilations, the preventive measures adopted, and the legal conditions under which tattoos and piercings are made in our society.

  16. Water deficit modulates the response of Vitis vinifera to the Pierce's disease pathogen Xylella fastidiosa.

    Science.gov (United States)

    Choi, Hong-Kyu; Iandolino, Alberto; da Silva, Francisco Goes; Cook, Douglas R

    2013-06-01

    Pierce's disease, caused by the bacterium Xylella fastidiosa, is one of the most devastating diseases of cultivated grape, currently restricted to the Americas. To test the long-standing hypothesis that Pierce's disease results from pathogen-induced drought stress, we used the Affymetrix Vitis GeneChip to compare the transcriptional response of Vitis vinifera to Xylella infection, water deficit, or a combination of the two stresses. The results reveal a redirection of gene transcription involving 822 genes with a minimum twofold change (P related proteins, abscisic acid- and jasmonic acid-responsive biosynthesis, and downregulation of transcripts related to photosynthesis, growth, and nutrition. Although the transcriptional response of plants to Xylella infection was largely distinct from the response of healthy plants to water stress, we find that 138 of the pathogen-induced genes exhibited a significantly stronger transcriptional response when plants were simultaneously exposed to infection and drought stress, suggesting a strong interaction between disease and water deficit. This interaction between drought stress and disease was mirrored in planta at the physiological level for aspects of water relations and photosynthesis and in terms of the severity of disease symptoms and the extent of pathogen colonization, providing a molecular correlate of the classical concept of the disease triangle in which environment impacts disease severity.

  17. Propagating Instabilities in Solids

    Science.gov (United States)

    Kyriakides, Stelios

    1998-03-01

    Instability is one of the factors which limit the extent to which solids can be loaded or deformed and plays a pivotal role in the design of many structures. Such instabilities often result in localized deformation which precipitates catastrophic failure. Some materials have the capacity to recover their stiffness following a certain amount of localized deformation. This local recovery in stiffness arrests further local deformation and spreading of the instability to neighboring material becomes preferred. Under displacement controlled loading the propagation of the transition fronts can be achieved in a steady-state manner at a constant stress level known as the propagation stress. The stresses in the transition fronts joining the highly deformed zone to the intact material overcome the instability nucleation stresses and, as a result, the propagation stress is usually much lower than the stress required to nucleate the instability. The classical example of this class of material instabilities is L/"uders bands which tend to affect mild steels and other metals. Recent work has demonstrated that propagating instabilities occur in several other materials. Experimental and analytical results from four examples will be used to illustrate this point: First the evolution of L=FCders bands in mild steel strips will be revisited. The second example involves the evolution of stress induced phase transformations (austenite to martensite phases and the reverse) in a shape memory alloy under displacement controlled stretching. The third example is the crushing behavior of cellular materials such as honeycombs and foams made from metals and polymers. The fourth example involves the axial broadening/propagation of kink bands in aligned fiber/matrix composites under compression. The microstructure and, as a result, the micromechanisms governing the onset, localization, local arrest and propagation of instabilities in each of the four materials are vastly different. Despite this

  18. Test of Slope and Intercept Bias in College Admissions: A Response to Aguinis, Culpepper, and Pierce (2010)

    Science.gov (United States)

    Mattern, Krista D.; Patterson, Brian F.

    2013-01-01

    Research on the predictive bias of cognitive tests has generally shown (a) no slope effects and (b) small intercept effects, typically favoring the minority group. Aguinis, Culpepper, and Pierce (2010) simulated data and demonstrated that statistical artifacts may have led to a lack of power to detect slope differences and an overestimate of the…

  19. Experimental study on upward bubble velocity and pierce length distributions in a water model of copper converter

    Institute of Scientific and Technical Information of China (English)

    Bin Du; Jiayun Zhang; Tuping Zhou; Qifeng Shu

    2003-01-01

    The upward bubble velocity and the pierce length distributions in a sectional water model of the copper convener in Guixi Smelter in Jiangxi, China, were measured using a two-contact electro-resistivity probe. In the case of using a single tuyere, the bubble velocity distribution along longitudinal direction was similar to that derived from Guassian function. Beyond the center of the longitudinal range, the bubble pierce length exhibited a sudden increase. The upward bubble velocity at a specified location could go up to meters per second. Its probability at a fixed location obeys a lognormal function; the bubble pierce length there varies bellow a few centimeters. In the case of using multi-tuyeres, the upward bubble velocity was roughly uniform right above the tuyeres and showed a slow decrease beyond this region. The bubble pierce length within both of these two regions was roughly uniform. Its average value in the former region, however, was found to be somewhat lower than that in the later.

  20. [Are nail polish, artificial nails and piercings allowed outside the surgical area?Recommendations for the perioperative policy

    NARCIS (Netherlands)

    Bucx, M.J.L.; Krijtenburg, P.; Scheffer, G.J.

    2017-01-01

    - An increasing number of patients wear nail polish, artificial nails or have piercings.- There is uncertainty about the perioperative management of these items, especially when located outside the surgical area.- In the majority of hospitals, patients are urged to remove these items preoperatively,

  1. Burn Bans lifted for Tribal Reservations in Snohomish and Pierce Counties on Jan. 11, Ban Continues for Yakama Reservation

    Science.gov (United States)

    Today the U.S. Environmental Protection Agency is lifting its burn ban on open burning for the Tulalip, Stillaguamish, Sauk-Suiattle and Puyallup Indian Reservations in Snohomish and Pierce Counties due to improved air quality, effective at 8:00 a.m., Janu

  2. MEN ARE INNOCENT UNTIL PROVEN GUILTY - A COMMENT ON THE EXAMINATION OF SEX-DIFFERENCES BY PIERCE AND KIRKPATRICK

    NARCIS (Netherlands)

    PICKERSGILL, MJ; ARRINDELL, WA

    1992-01-01

    Pierce and Kirkpatrick (1992, Behaviour Research and Therapy, 30, 415-418) addressed the finding that men reported lower levels of fear than women in response to specific fear items and concluded on the basis of their experiment that this was because the men were lying. Their conclusion is

  3. On-surface fibre-free zones and irregularity of piercing pattern in structurally stitched NCF preforms

    NARCIS (Netherlands)

    Koissin, Vitaly; Ruopp, Andreas; Lomov, Stepan V.; Verpoest, Ignaas; Witzel, Volker; Drechsler, Klaus

    2006-01-01

    The paper addresses the surface imperfections (openings in fibrous plies) and irregularity of the piercing pattern in structurally stitched multilayer carbon-fibre preforms. Each layer is a multiaxial multiply non-crimp fabric (NCF) with a non-structural stitching. The term “structural” presumes her

  4. Test of Slope and Intercept Bias in College Admissions: A Response to Aguinis, Culpepper, and Pierce (2010)

    Science.gov (United States)

    Mattern, Krista D.; Patterson, Brian F.

    2013-01-01

    Research on the predictive bias of cognitive tests has generally shown (a) no slope effects and (b) small intercept effects, typically favoring the minority group. Aguinis, Culpepper, and Pierce (2010) simulated data and demonstrated that statistical artifacts may have led to a lack of power to detect slope differences and an overestimate of the…

  5. Neutrino beam plasma instability

    Indian Academy of Sciences (India)

    Vishnu M Bannur

    2001-10-01

    We derive relativistic fluid set of equations for neutrinos and electrons from relativistic Vlasov equations with Fermi weak interaction force. Using these fluid equations, we obtain a dispersion relation describing neutrino beam plasma instability, which is little different from normal dispersion relation of streaming instability. It contains new, nonelectromagnetic, neutrino-plasma (or electroweak) stable and unstable modes also. The growth of the instability is weak for the highly relativistic neutrino flux, but becomes stronger for weakly relativistic neutrino flux in the case of parameters appropriate to the early universe and supernova explosions. However, this mode is dominant only for the beam velocity greater than 0.25 and in the other limit electroweak unstable mode takes over.

  6. Causes of genome instability

    DEFF Research Database (Denmark)

    Langie, Sabine A S; Koppen, Gudrun; Desaulniers, Daniel

    2015-01-01

    , genome instability can be defined as an enhanced tendency for the genome to acquire mutations; ranging from changes to the nucleotide sequence to chromosomal gain, rearrangements or loss. This review raises the hypothesis that in addition to known human carcinogens, exposure to low dose of other...... scientists aware of the increasing need to unravel the underlying mechanisms via which chemicals at low doses can induce genome instability and thus promote carcinogenesis.......Genome instability is a prerequisite for the development of cancer. It occurs when genome maintenance systems fail to safeguard the genome's integrity, whether as a consequence of inherited defects or induced via exposure to environmental agents (chemicals, biological agents and radiation). Thus...

  7. Comparative analysis of the tardigrade feeding apparatus: adaptive convergence and evolutionary pattern of the piercing stylet system

    Directory of Open Access Journals (Sweden)

    Roberto Guidetti

    2013-03-01

    Full Text Available A thorough analysis of the cuticular parts of tardigrade feeding apparatuses was performed in order to provide a more complete understanding of their evolution and their potential homologies with other animal phyla (e.g. Cycloneuralia and Arthropoda. The buccal- pharyngeal apparatuses of eight species belonging to both Eutardigrada and Heterotardigrada were studied using light and scanning electron microscopy. This study supports and completes a previous study on the relationships between form and function in the buccalpharyngeal apparatus of eutardigrades. The common sclerified structures of the tardigrade buccal-pharyngeal apparatus are: a buccal ring connected to a straight buccal tube, a buccal crown, longitudinal thickenings within the pharynx, and a stylet system composed of piercing stylets within stylet coats, and stylet supports. Specifically, heterotardigrades (Echiniscoidea have a narrow buccal tube; long piercing stylets, each with a longitudinal groove, that cross one another before exiting the mouth; pharyngeal bars and secondary longitudinal thickenings within the pharynx. In contrast, eutardigrades have stylets which are shorter than the buccal tube; Parachela have pharyngeal apophyses and placoids within the pharynx, while Apochela lack a buccal crown and cuticular thickenings within the pharynx, the buccal tube is very wide, and the short stylets are associated with triangular-shaped stylet supports. In both classes, when the piercing stylet tips emerge from the mouth to pierce food, the buccal tube opening is almost completely obstructed, which may hinder food uptake. In heterotardigrades, the crossing of the piercing stylets may further decrease food uptake, however this disadvantage may have been reduced in echiniscids by the evolution of a long buccal tube and long stylets able to run more parallel to the buccal tube. In contrast, eutardigrades evolved different strategies. In the order Apochela and in several

  8. Mixing through shear instabilities

    CERN Document Server

    Brüggen, M

    2000-01-01

    In this paper we present the results of numerical simulations of the Kelvin-Helmholtz instability in a stratified shear layer. This shear instability is believed to be responsible for extra mixing in differentially rotating stellar interiors and is the prime candidate to explain the abundance anomalies observed in many rotating stars. All mixing prescriptions currently in use are based on phenomenological and heuristic estimates whose validity is often unclear. Using three-dimensional numerical simulations, we study the mixing efficiency as a function of the Richardson number and compare our results with some semi-analytical formalisms of mixing.

  9. Performance Optimization of Self-Piercing Rivets through Analytical Rivet Strength Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Khaleel, Mohammad A.

    2005-08-01

    This paper presents the authors' work on strength optimization and failure mode prediction of self-piercing rivets (SPR) for automotive applications. The limit load-based strength estimator is used to estimate the static strength of an SPR under cross tension loading configuration. Failure modes associated with the estimated failure strength are also predicted. Experimental strength and failure mode observations are used to validate the model. It is shown that the strength of an SPR joint depends on the material and gage combinations, rivet design, die design and riveting direction. The rivet strength estimator is then used to optimize the rivet strength by comparing the measured rivet strength and failure mode with the predicted ones. Two illustrative examples are used in which rivet strength is optimized by changing rivet design and riveting direction from the original manufacturing parameters.

  10. Strength Estimation of Self-Piercing Rivets using Lower Bound Limit Load Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Khaleel, Mohammad A.

    2005-08-01

    This paper summarizes the authors' work on strength and failure mode estimation of self-piercing rivets (SPR) for automotive applications. First, the static cross tension strength of an SPR joint is estimated using a lower bound limit load based strength estimator. Failure mode associated with the predicted failure strength can also be identified. It is shown that the cross tension strength of an SPR joint depends on the material and gage combinations, rivet design, die design and riveting direction. The analytical rivet strength estimator is then validated by experimental rivet strength measurements and failure mode observations from nine SPR joint populations with various material and gage combinations. Next, the estimator is used to optimize rivet strength. Two illustrative examples are presented in which rivet strength is improved by changing rivet length and riveting direction from the original manufacturing parameters.

  11. Extension of Pierce model to multiple transmission lines interacting with an electron beam

    CERN Document Server

    Tamma, Venkata Ananth

    2013-01-01

    A possible route towards achieving high power microwave devices is through the use of novel slow-wave structures employing multiple coupled transmission lines (MTLs) whose behavior when coupled to electron beams have not been sufficiently explored. We present the extension of the one-dimensional linearized Pierce theory to MTLs coupled to a single electron beam. We develop multiple formalisms to calculate the k-{\\omega} dispersion relation of the system and find that the existence of a growing wave solution is always guaranteed if the electron propagation constant is larger than or equal to the largest propagation constant of the MTL system. We verify our findings with illustrative examples which bring to light unique properties of the system in which growing waves were found to exist within finite bands of the electron propagation constant and discuss possible approach to improve the gain. By treating the beam-MTL interaction as distributed dependent current generators in the MTL, we derive relations charact...

  12. [Tattoos and piercings: motives for body modification in women suffering from borderline symptomatology].

    Science.gov (United States)

    Höhner, Gesche; Teismann, Tobias; Willutzki, Ulrike

    2014-02-01

    Do women suffering from borderline symptomatology differ from women without these symptoms regarding their motives for body modifications?A sample of 289 women with body modifications were questioned about their tattoos, piercings and motives for body modifications as well as about symptoms of borderline personality disorder. Women with borderline symptomatology were compared to women without borderline symptomatology concerning the extent of and motives for body modification.The 2 groups showed no differences in regard to amount and extent of body modifications. The "borderline"-group considered individuality, coping and management of negative life-events to be more crucial reasons for body modification than the non-borderline females.The degree of a person's body modification is not a feasible indicator for psychopathological strain. Though, for people with borderline tendency body modification may serve as a coping strategy similar to self-injury.

  13. Self pierce riveting in the car body construction; Stanznieten im Karosserieleichtbau

    Energy Technology Data Exchange (ETDEWEB)

    Ahlers-Hestermann, G. [Boellhoff GmbH, Bielefeld (Germany)

    1999-09-01

    As an alterantive to spotwelding, self pierce riveting becomes more and more important in light weight automotive body constructions. The difficulties or impossibility of spotwelding Aluminium and High Tensile Strength Steel or material mixtures accelerated this development. Even plastic material can be joined to metal. Important mechanical properties such as fatigue and crash behaviour are improved. Costs are at the same level. Two examples of body parts in aluminium (Audi A6 bonnet and BMW 3 series front end) are described. (orig.) [German] Als Alternative zum Punktschweissen setzt sich das Stanznieten mit Halbhohlniet im Karosserieleichtbau mehr und mehr durch. Mit diesem Verfahren koennen verschiedene Materialen mit bis zu vier Lagen sicher verbunden werden. Dieser Beitrag der Boellhoff GmbH stellt das Verfahren vor und berichtet ueber zwei Beispiele aus der Praxis. (orig.)

  14. Labrets: Piercing and Stretching on the Northwest Coast and in Amazonia

    Directory of Open Access Journals (Sweden)

    Jenny Reddish

    2014-05-01

    Full Text Available This article examines the practice of piercing and stretching the lip in order to accommodate a labret in two regions: the North American Northwest Coast (with historical examples from Tlingit and Haida groups and lowland South America (utilizing ethnographic writings on Suya and Kayapo communities. Drawing on the recent ‘sensorial turn’ within anthropology, I suggest an approach which goes beyond considerations of the symbolism of body ornaments and analyses how the infliction of pain they involve can be manipulated to serve social ends at a local level. Also discussed is the use of labrets within global ‘mediascapes’ (Appadurai 1996 by Kayapo and Northwest Coast groups in the context of self-representation and the politicization of ‘culture’ (Wright 1998.

  15. Nickel sensitization in adolescents and association with ear piercing, use of dental braces and hand eczema. The Odense Adolescence Cohort Study on Atopic Diseases and Dermatitis (TOACS)

    DEFF Research Database (Denmark)

    Mørtz, Charlotte G; Lauritsen, Jens Martin; Bindslev-Jensen, Carsten

    2002-01-01

    The prevalence of nickel allergy (sensitization) and the associations with ear piercing, use of dental braces and hand eczema were assessed in a cohort of 1,501 8th grade schoolchildren (aged 12-16 years) in Odense, Denmark. Nickel allergy was found in 8.6% and was clinically relevant in 69......% of cases. Nickel allergy was found most frequently in girls and the association with ear piercing was confirmed. Application of dental braces (oral nickel exposure) prior to ear piercing (cutaneous nickel exposure) was associated with a significantly reduced prevalence of nickel allergy. In adolescents...

  16. Shock instability in dissipative gases

    OpenAIRE

    Radulescu, Matei I.; Sirmas, Nick

    2011-01-01

    Previous experiments have revealed that shock waves in thermally relaxing gases, such as ionizing, dissociating and vibrationally excited gases, can become unstable. To date, the mechanism controlling this instability has not been resolved. Previous accounts of the D'yakov-Kontorovich instability, and Bethe-Zel'dovich-Thompson behaviour could not predict the experimentally observed instability. To address the mechanism controlling the instability, we study the propagation of shock waves in a ...

  17. Body piercing and tattoos: a survey on young adults' knowledge of the risks and practices in body art

    Directory of Open Access Journals (Sweden)

    Caggiano Giuseppina

    2011-10-01

    Full Text Available Abstract Background The practice of tattooing and piercing has expanded in western society. In order to verify young adults' knowledge of the risk and practices related to body art, an investigation was conducted among freshmen of the University of Bari in the region of Apulia, Italy. Methods The study was carried out in the Academic Year 2009-2010 through an anonymous self-administered written questionnaire distributed to 1.656 freshmen enrolled in 17 Degree Courses. Results Of the 1.598 students included in the analysis, 78.3% believe it is risky to undergo piercing/tattoo practices. AIDS was indicated as a possible infection by 60.3% of freshmen, hepatitis C by 38.2%, tetanus by 34.3% and hepatitis B by 33.7% of the sample. 28.1% of freshmen were not aware that there are also non-infectious complications. 29% of the sample had at least one piercing or tattoo (this percentage does not include earlobe piercing in women. Of those with body art, the decision to undergo body art was made autonomously in 57.9% of the participants. 56.3% of freshmen undergoing body art had taken less than a month to decide. With regard to the reasons that led the sample to undergo body art, 28.4% were unable to explain it, 23.8% answered to improve their aesthetic aspect, 18.4% to distinguish themselves from others, 12.3% for fashion; 17.1% for other reasons. 25.4% of the sample declared that they had a piercing (79.8% female vs 20.2% male; ratio M/F 1:4.0. The average age for a first piercing was 15.3 years (range 10-27; SD ± 2.9. 9.6% of the sample declared that they have a tattoo (69.9% female vs 30.1% male; ratio M/F 1:2.3. The average age for a first tattoo was 17.5 years (range 10-26, SD ± 2.4. Conclusions Most of the freshmen knew about AIDS-related risks but not other potential risks. Body art is fairly common among young adults (especially women. The decision is often not shared with the family and is undertaken mostly without a specific reason or for the

  18. Body piercing and tattoos: a survey on young adults' knowledge of the risks and practices in body art

    Science.gov (United States)

    2011-01-01

    Background The practice of tattooing and piercing has expanded in western society. In order to verify young adults' knowledge of the risk and practices related to body art, an investigation was conducted among freshmen of the University of Bari in the region of Apulia, Italy. Methods The study was carried out in the Academic Year 2009-2010 through an anonymous self-administered written questionnaire distributed to 1.656 freshmen enrolled in 17 Degree Courses. Results Of the 1.598 students included in the analysis, 78.3% believe it is risky to undergo piercing/tattoo practices. AIDS was indicated as a possible infection by 60.3% of freshmen, hepatitis C by 38.2%, tetanus by 34.3% and hepatitis B by 33.7% of the sample. 28.1% of freshmen were not aware that there are also non-infectious complications. 29% of the sample had at least one piercing or tattoo (this percentage does not include earlobe piercing in women). Of those with body art, the decision to undergo body art was made autonomously in 57.9% of the participants. 56.3% of freshmen undergoing body art had taken less than a month to decide. With regard to the reasons that led the sample to undergo body art, 28.4% were unable to explain it, 23.8% answered to improve their aesthetic aspect, 18.4% to distinguish themselves from others, 12.3% for fashion; 17.1% for other reasons. 25.4% of the sample declared that they had a piercing (79.8% female vs 20.2% male; ratio M/F 1:4.0). The average age for a first piercing was 15.3 years (range 10-27; SD ± 2.9). 9.6% of the sample declared that they have a tattoo (69.9% female vs 30.1% male; ratio M/F 1:2.3). The average age for a first tattoo was 17.5 years (range 10-26, SD ± 2.4). Conclusions Most of the freshmen knew about AIDS-related risks but not other potential risks. Body art is fairly common among young adults (especially women). The decision is often not shared with the family and is undertaken mostly without a specific reason or for the improvement of

  19. Genetic instability in Gynecological Cancer

    Institute of Scientific and Technical Information of China (English)

    ZHAO Qing-hua; ZHOU Hong-lin

    2003-01-01

    Defects of mismatch repair (MMR) genes also have beenidentified in many kinds of tumors. Loss of MMR functionhas been linked to genetic instability especially microsatelliteinstability that results in high mutation rate. In this review, wediscussed the microsatellite instability observed in thegynecological tumors. We also discussed defects in the DNAmismatch repair in these tumors and their correlation to themicrosatellite instability, as well as the gene mutations due tothe microsatellite instability in these tumors. From thesediscussion, we tried to understand the mechanism ofcarcinogenesis in gynecological tumors from the aspect ofgenetic instability due to mismatch repair defects.

  20. Instabilities in sensory processes

    Science.gov (United States)

    Balakrishnan, J.

    2014-07-01

    In any organism there are different kinds of sensory receptors for detecting the various, distinct stimuli through which its external environment may impinge upon it. These receptors convey these stimuli in different ways to an organism's information processing region enabling it to distinctly perceive the varied sensations and to respond to them. The behavior of cells and their response to stimuli may be captured through simple mathematical models employing regulatory feedback mechanisms. We argue that the sensory processes such as olfaction function optimally by operating in the close proximity of dynamical instabilities. In the case of coupled neurons, we point out that random disturbances and fluctuations can move their operating point close to certain dynamical instabilities triggering synchronous activity.

  1. Modulation instability: The beginning

    Science.gov (United States)

    Noskov, Roman; Belov, Pavel; Kivshar, Yuri

    2012-11-01

    The study of metal nanoparticles plays a central role in the emerging novel technologies employing optics beyond the diffraction limit. Combining strong surface plasmon resonances, high intrinsic nonlinearities and deeply subwavelength scales, arrays of metal nanoparticles offer a unique playground to develop novel concepts for light manipulation at the nanoscale. Here we suggest a novel principle to control localized optical energy in chains of nonlinear subwavelength metal nanoparticles based on the fundamental nonlinear phenomenon of modulation instability. In particular, we demonstrate that modulation instability can lead to the formation of long-lived standing and moving nonlinear localized modes of several distinct types such as bright and dark solitons, oscillons, and domain walls. We analyze the properties of these nonlinear localized modes and reveal different scenarios of their dynamics including transformation of one type of mode to another. We believe this work paves a way towards the development of nonlinear nanophotonics circuitry.

  2. Instability and internet design

    Directory of Open Access Journals (Sweden)

    Sandra Braman

    2016-09-01

    Full Text Available Instability - unpredictable but constant change in one’s environment and the means with which one deals with it - has replaced convergence as the focal problem for telecommunications policy in general and internet policy in particular. Those who designed what we now call the internet during the first decade of the effort (1969-1979, who in essence served simultaneously as its policy-makers, developed techniques for coping with instability of value for network designers today and for those involved with any kind of large-scale sociotechnical infrastructure. Analysis of the technical document series that was medium for and record of that design process reveals coping techniques that began with defining the problem and went on to include conceptual labour, social practices, and technical approaches.

  3. Gravitational instabilities of superspinars

    CERN Document Server

    Pani, Paolo; Berti, Emanuele; Cardoso, Vitor

    2010-01-01

    Superspinars are ultracompact objects whose mass M and angular momentum J violate the Kerr bound (cJ/GM^2>1). Recent studies analyzed the observable consequences of gravitational lensing and accretion around superspinars in astrophysical scenarios. In this paper we investigate the dynamical stability of superspinars to gravitational perturbations, considering either purely reflecting or perfectly absorbing boundary conditions at the "surface" of the superspinar. We find that these objects are unstable independently of the boundary conditions, and that the instability is strongest for relatively small values of the spin. Also, we give a physical interpretation of the various instabilities that we find. Our results (together with the well-known fact that accretion tends to spin superspinars down) imply that superspinars are very unlikely astrophysical alternatives to black holes.

  4. Road and Street Centerlines, Roads in Pierce County, GA, Published in 2010, 1:7200 (1in=600ft) scale, Southern Georgia Regional Commission.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — , published at 1:7200 (1in=600ft) scale, was produced all or in part from Hardcopy Maps information as of 2010. It is described as 'Roads in Pierce County, GA'. Data...

  5. The instability of markets

    CERN Document Server

    Huberman, B A; Huberman, Bernardo A; Youssefmir, Michael

    1995-01-01

    Recent developments in the global liberalization of equity and currency markets, coupled to advances in trading technologies, are making markets increasingly interdependent. This increased fluidity raises questions about the stability of the international financial system. In this paper, we show that as couplings between stable markets grow, the likelihood of instabilities is increased, leading to a loss of general equilibrium as the system becomes increasingly large and diverse.

  6. Modulation instability: The beginning

    Science.gov (United States)

    Zakharov, V. E.; Ostrovsky, L. A.

    2009-03-01

    We discuss the early history of an important field of “sturm and drang” in modern theory of nonlinear waves. It is demonstrated how scientific demand resulted in independent and almost simultaneous publications by many different authors on modulation instability, a phenomenon resulting in a variety of nonlinear processes such as envelope solitons, envelope shocks, freak waves, etc. Examples from water wave hydrodynamics, electrodynamics, nonlinear optics, and convection theory are given.

  7. Simulation of the Groundwater-Flow System in Pierce, Polk, and St. Croix Counties, Wisconsin

    Science.gov (United States)

    Juckem, Paul F.

    2009-01-01

    Groundwater is the sole source of residential water supply in Pierce, Polk, and St. Croix Counties, Wisconsin. A regional three-dimensional groundwater-flow model and three associated demonstration inset models were developed to simulate the groundwater-flow systems in the three-county area. The models were developed by the U.S. Geological Survey in cooperation with the three county governments. The objectives of the regional model of Pierce, Polk, and St. Croix Counties were to improve understanding of the groundwaterflow system and to develop a tool suitable for evaluating the effects of potential water-management programs. The regional groundwater-flow model described in this report simulates the major hydrogeologic features of the modeled area, including bedrock and surficial aquifers, groundwater/surface-water interactions, and groundwater withdrawals from high-capacity wells. Results from the regional model indicate that about 82 percent of groundwater in the three counties is from recharge within the counties; 15 percent is from surface-water sources, consisting primarily of recirculated groundwater seepage in areas with abrupt surface-water-level changes, such as near waterfalls, dams, and the downgradient side of reservoirs and lakes; and 4 percent is from inflow across the county boundaries. Groundwater flow out of the counties is to streams (85 percent), outflow across county boundaries (14 percent), and pumping wells (1 percent). These results demonstrate that the primary source of groundwater withdrawn by pumping wells is water that recharges within the counties and would otherwise discharge to local streams and lakes. Under current conditions, the St. Croix and Mississippi Rivers are groundwater discharge locations (gaining reaches) and appear to function as 'fully penetrating' hydraulic boundaries such that groundwater does not cross between Wisconsin and Minnesota beneath them. Being hydraulic boundaries, however, they can change in response to

  8. Carpal instability nondissociative.

    Science.gov (United States)

    Wolfe, Scott W; Garcia-Elias, Marc; Kitay, Alison

    2012-09-01

    Carpal instability nondissociative (CIND) represents a spectrum of conditions characterized by kinematic dysfunction of the proximal carpal row, often associated with a clinical "clunk." CIND is manifested at the midcarpal and/or radiocarpal joints, and it is distinguished from carpal instability dissociative (CID) by the lack of disruption between bones within the same carpal row. There are four major subcategories of CIND: palmar, dorsal, combined, and adaptive. In palmar CIND, instability occurs across the entire proximal carpal row. When nonsurgical management fails, surgical options include arthroscopic thermal capsulorrhaphy, soft-tissue reconstruction, or limited radiocarpal or intercarpal fusions. In dorsal CIND, the capitate subluxates dorsally from its reduced resting position. Dorsal CIND usually responds to nonsurgical management; refractory cases respond to palmar ligament reefing and/or dorsal intercarpal capsulodesis. Combined CIND demonstrates signs of both palmar and dorsal CIND and can be treated with soft-tissue or bony procedures. In adaptive CIND, the volar carpal ligaments are slackened and are less capable of inducing the physiologic shift of the proximal carpal row from flexion into extension as the wrist ulnarly deviates. Treatment of choice is a corrective osteotomy to restore the normal volar tilt of the distal radius.

  9. Chromosomal instability in meningiomas.

    Science.gov (United States)

    van Tilborg, Angela A G; Al Allak, Bushra; Velthuizen, Sandra C J M; de Vries, Annie; Kros, Johan M; Avezaat, Cees J J; de Klein, Annelies; Beverloo, H Berna; Zwarthoff, Ellen C

    2005-04-01

    Approximately 60% of sporadic meningiomas are caused by inactivation of the NF2 tumor suppressor gene on chromosome 22. No causative gene is known for the remaining 40%. Cytogenetic analysis shows that meningiomas caused by inactivation of the NF2 gene can be divided into tumors that show monosomy 22 as the sole abnormality and tumors with a more complex karyotype. Meningiomas not caused by the NF2 gene usually have a diploid karyotype. Here we report that, besides the clonal chromosomal aberrations, the chromosome numbers in many meningiomas varied from one metaphase spread to the other, a feature that is indicative of chromosomal instability. Unexpectedly and regardless of genotype, a subgroup of tumors was observed with an average number of 44.9 chromosomes and little variation in the number of chromosomes per metaphase spread. In addition, a second subgroup was recognized with a hyperdiploid number of chromosomes (average 48.5) and considerable variation in numbers per metaphase. However, this numerical instability resulted in a clonal karyotype with chromosomal gains and losses in addition to loss of chromosome 22 only in meningiomas caused by inactivation of the NF2 gene. In cultured cells of all tumor groups, bi- and multinucleated cells were seen, as well as anaphase bridges, residual chromatid strings, multiple spindle poles, and unseparated chromatids, suggesting defects in the mitotic apparatus or kinetochore. Thus, we conclude that even a benign and slow-growing tumor like a meningioma displays chromosomal instability.

  10. Differences in scour around a single surface-piercing cylinder and a submerged cylinder

    Science.gov (United States)

    Beninati, M. L.; Volpe, M. A.; Riley, D. R.; Krane, M.

    2011-12-01

    The equilibrium state of scour for a single surface piercing cylinder and a submerged cylinder of specific aspect ratio are presented. The equilibrium state is defined by a scour depth and associated time interval for a given set of flow conditions. Control variables such as sediment coarseness (or grain size) and cylinder size are held constant, while the flow intensity is varied. Sediment bed form topology is characterized with a series of two-dimensional slices across the bed for both the surface-piercing and submerged cylinder cases. Test results will help identify the geometry and pattern of the scour around the cylinders to aid in the optimal design of marine hydrokinetic (MHK) support structures in an effort to help minimize the deleterious impact of these devices on the local substrate. This study is performed in the small-scale testing platform in the hydraulic flume facility (32 ft long, 4 ft wide and 1.25 ft deep) in the Environmental Fluid Mechanics and Hydraulics Laboratory (EFM&H) at Bucknell University. The cylinders, of the same material and diameter, are placed centrally in the sediment filled test section (2.5 ft long, 2 ft wide and 0.75 ft deep) of the platform. Flow field measurements are taken with a 16-MHz Micro Acoustic Doppler Velocimeter while water depth is acquired using an ultrasonic distance sensor. These devices are attached to a gantry system that can be accurately positioned anywhere in the test section. Clear-water conditions (in the absence of live-bed scour) are maintained to study the effect of the horseshoe and wake vortices on the displacement of sediment around the cylinder as well as downstream of the device. Bed form topology is measured using an HR Wallingford 2D Sediment Bed Profiler with a low-powered laser distance sensor to accurately characterize changes in bed form around the cylinders. Additionally, specifications for testing such as operational procedures for start-up and shut-down of the facility are given.

  11. Accidental aspiration of head scarf pin in left bronchus piercing the lung parenchyma: A rare case in a child

    Science.gov (United States)

    Parvez, Yusuf; Kandath, Mohammed Ashraf

    2016-01-01

    Foreign body (FB) aspiration is commonly seen in children but less commonly in adolescents. Headscarf pin aspiration is common in Muslim girls, who inappropriately place the pins between their lips while securing the scarf on the head. Bronchoscopy is the treatment modality of choice, and surgery is rarely required. An 11-year-old girl was admitted as a case of accidental aspiration of headscarf pin. X-ray chest showed a radiopaque object in the left bronchus piercing the lung parenchyma. Computed tomography (CT) chest confirmed the diagnosis. The headscarf pin was removed by flexible bronchoscopy as the ear, nose, and throat (ENT) surgeon failed to remove it by rigid bronchoscopy. The FB was removed successfully and the patient was discharged home. Removal of a sharp pin by bronchoscopy is difficult, especially if it pierces the lung parenchyma. In our case, the pin was bent by forceps and then removed by a flexible bronchoscope, which requires a highly skilled professional. PMID:27578937

  12. Shoulder instability; Schultergelenkinstabilitaet

    Energy Technology Data Exchange (ETDEWEB)

    Sailer, J.; Imhof, H. [Abteilung Osteoradiologie, Univ.-Klinik fuer Radiodiagnostik Wien (Austria)

    2004-06-01

    Shoulder instability is a common clinical feature leading to recurrent pain and limitated range of motion within the glenohumeral joint. Instability can be due a single traumatic event, general joint laxity or repeated episodes of microtrauma. Differentiation between traumatic and atraumatic forms of shoulder instability requires careful history and a systemic clinical examination. Shoulder laxity has to be differentiated from true instability followed by the clinical assessment of direction and degree of glenohumeral translation. Conventional radiography and CT are used for the diagnosis of bony lesions. MR imaging and MR arthrography help in the detection of soft tissue affection, especially of the glenoid labrum and the capsuloligamentous complex. The most common lesion involving the labrum is the anterior labral tear, associated with capsuloperiostal stripping (Bankart lesion). A number of variants of the Bankart lesion have been described, such as ALPSA, SLAP or HAGL lesions. The purpose of this review is to highlight different forms of shoulder instability and its associated radiological findings with a focus on MR imaging. (orig.) [German] Die Schultergelenkinstabilitaet ist haeufig fuer wiederholt auftretende Schmerzen sowie eine eingeschraenkte Beweglichkeit im Glenohumeralgelenk verantwortlich. Sie kann als Folge eines vorangegangenen Traumas, einer generellen Hyperlaxitaet oder infolge wiederholter Mikrotraumen entstehen. Die Differenzierung zwischen traumatischer und atraumatischer Form der Gelenkinstabilitaet erfordert eine sorgfaeltige Anamnese und eine genaue klinische Untersuchung. Die Gelelenklaxitaet als Differenzialdiagnose muss von der echten Instabilitaet unterschieden werden, die Instabilitaet wird dann im Rahmen des klinischen Status nach Grad und Richtung der glenohumeralen Translation unterteilt. Zur Diagnose knoecherner Laesionen werden das konventionelle Roentgen sowie die CT herangezogen. MRT sowie MR-Arthrographie dienen zur Detektion

  13. 自攻铆接技术--轻金属连接方法%Self-Pierce Riveting

    Institute of Scientific and Technical Information of China (English)

    苏鸿英

    2004-01-01

    @@ 1概况 在铝强化汽车车体,重型卡车驾驶室和运动娱乐汽车车体的安装中采用自攻铆接(Self-Pierce riveting)已经证明是成功的连接技术,并且已经有十年应用的历史.

  14. Lidar-revised geologic map of the Poverty Bay 7.5' quadrangle, King and Pierce Counties, Washington

    Science.gov (United States)

    Tabor, Rowland W.; Booth, Derek B.; Troost, Kathy Goetz

    2014-01-01

    For this map, we interpreted a 6-ft-resolution lidar digital elevation model combined with the geology depicted on the Geologic Map of the Poverty Bay 7.5' Quadrangle, King and Pierce Counties, Washington (Booth and others, 2004b). The authors of the 2004 map described, interpreted, and located the geology on the 1:24,000-scale topographic map of the Poverty Bay 7.5' quadrangle.

  15. Undersøgelse af pulsformers indflydelse på piercing og skæring i rummet

    DEFF Research Database (Denmark)

    Horstmann, Birgitte D.; Juhl, Thomas Winther

    1999-01-01

    Der er gennem en række laboratorieforsøg gennemført piercing og hjørneskæring i rummet (3D) i AISI 316 stål. Det er blevet konstateret at der kan opnås piercingtider på ned til ca. 1 sekund i det anvendte 5 mm pladestål. Tre forskellige pulsformer, Gated puls, Hyper puls og Super puls er blevet...

  16. Hydrographs showing groundwater levels for selected wells in the Puyallup River watershed and vicinity, Pierce and King Counties, Washington

    Science.gov (United States)

    Lane, R.C.; Julich, R.J.; Justin, G.B.

    2013-01-01

    Hydrographs of groundwater levels for selected wells in and adjacent to the Puyallup River watershed in Pierce and King Counties, Washington, are presented using an interactive Web-based map of the study area to illustrate changes in groundwater levels on a monthly and seasonal basis. The interactive map displays well locations that link to the hydrographs, which in turn link to the U.S. Geological Survey National Water Information System, Groundwater Site Inventory System.

  17. Motivations for body piercings and tattoos - the role of sexual abuse and the frequency of body modifications.

    Science.gov (United States)

    Stirn, Aglaja; Oddo, Silvia; Peregrinova, Ludmila; Philipp, Swetlana; Hinz, Andreas

    2011-12-30

    Though the popularity of body modification increases, psychosocial data about practitioners of body piercing and tattooing are few and controversial. Most studies used semi-structured interviews and relatively small sample sizes. The aim of this study was to explore psychosocial background information (motivation, sexual abuse) for body modification practises based on a sufficiently large sample. A core group of 432 subjects with body piercings and/or tattoos (readers of a specialised magazine on body modification; mean age: 28 years) was investigated in this study using a 55-item questionnaire. The mean number of body modifications (piercings and tattoos) was nine. Participants with a history of sexual abuse and high users with more than 10 body modifications differed from those without these features with respect to several motivations and consequences of body modification. Participants with sexual abuse often stated that they wanted to overcome certain experiences, and high users were characterised by the feeling of an addiction to continue body modification. Clinicians should include questions on body modifications and their motives in anamnestic schedules.

  18. Tattoos, piercings and re-configuration of the body. A path between bioethical and educational profiles

    Directory of Open Access Journals (Sweden)

    Carmela Bianco

    2014-03-01

    Full Text Available Tattoos and piercings can become a mask to hide behind? Everything can become a mask if we use it for masquerading. The tattoo is the anthropological roots of ancient and modern makeup that refers to the mask understood as that which creates the face, which gives it its social being. The tattoo is also an artistic decoration that should be born by the deep desire to communicate yourself to others. Tattoos must be able to "tell" the people who wear them, but if the latter decorate their body with a message or image that does not belong, it can cause the destruction of individuality. The tattoo is immortal. It can be a permanent dress, a way to resist the unwanted transformations using a piece of subjective identity, non-imitable, from which one cannot be excluded. Along with careful identification of psycho-sociological motivations that drive a young man to want a tattoo, you need to traverse an education that not only form a personality, teaches the knowledge of his own body. Getting a tattoo means not only change the morphology of the body but the risk of jeopardizing their health. Responsibility for their own health also means being aware that a tattoo can procure mild side effects or more severe depending on the initial state of health of the subject. Then a tattoo only after a careful history following the favorable opinion of the doctor and after a personal assessment aware. These initial objectives of a path bioethical-pedagogical significant.

  19. Control of a flexible, surface-piercing hydrofoil for high-speed, small-scale applications

    Science.gov (United States)

    Bousquet, Gabriel; Triantafyllou, Michael; Slotine, Jean-Jacques

    2016-11-01

    In recent years, hydrofoils have become ubiquitous in the design of high performance surface vehicles such as sailboats. They have proven particularly useful at small scales: while the speed of displacement-hull sailboats of length L is limited by their hull speed √{ gL } , due to wave making resistance, such limitations do not apply to hydrofoil crafts and sailboats. Such crafts of length O(1 - 10 m) are capable of reaching speeds in excess of 45 kts, often far faster than the wind. Besides, in the quest for super-maneuverability, actuated hydrofoils enable the efficient generation and control of large forces. With the intent to ultimately enable the design of small-scale, high-speed, and super-maneuverable surface vehicles, we investigate the problem of controlling the lift force generated by a flexible, surface-piercing hydrofoil traveling at high speed through a random wave field. We design a test platform composed of a rudder-like vertical foil, which is actuated in pitch, and instrumented with velocity, force, and immersion sensors. We present a feedback linearization controller, designed to operate over a wide range of velocities and sea states. Validation experiments are carried out on-the-field at speeds ranging from 3 to 10+m/s.

  20. The Hydroelastic Response of a Flexible Surface-Piercing Strut in Wetted, Ventilated, and Cavitating Flows

    Science.gov (United States)

    Harwood, Casey; Ward, Jacob; Young, Yin Lu; Felli, Mario; Falchi, Massimo; Ceccio, Steven

    2016-11-01

    High-speed and highly loaded lifting surfaces are prone to ventilation and cavitation. Increasing use of compliant materials (e.g. composites) in such systems necessitates a better understanding of the fluid-structure interactions of lifting surfaces in multiphase flow. Experiments on a flexible surface-piercing hydrofoil have been performed in a towing tank and a free-surface cavitation tunnel. The objectives are (i) to demonstrate the effects of material compliance upon hydrodynamic performance and stability of multiphase flow regimes, and (ii) to quantify the effects of multiphase flow upon the structural response and hydroelastic stability of flexible lifting bodies. A non-optical shape-sensing method is developed, which permits 3D bending and twisting deformations of the hydrofoil to be accurately inferred. The effects of the foil's compliance on hydrodynamic loads, structural motions and flow regimes are discussed. Partial immersion of the hydrofoil causes a mode-dependent change in added-mass that can encourage coalescence of higher modes. At the same time, increasing flow speed and ventilated flow decrease the damping associated with certain modes. Unsteady cavity shedding modulates the system parameters, causing a broadening of the frequency response. The authors would like to acknowledge the support of Dr. Ki-Han Kim under ONR Grant Number N00014-13-1-0383 and N00014-16-1-2433.

  1. Development and Comparison of Symptom Indices for Quantifying Grapevine Resistance to Pierce's Disease.

    Science.gov (United States)

    Krivanek, A F; Stevenson, J F; Walker, M A

    2005-01-01

    ABSTRACT Symptoms of Pierce's disease (PD) were assessed under greenhouse conditions on field-resistant and field-susceptible grapevines in order to characterize the PD resistance phenotype in the genus Vitis. A cane maturation index (CMI) was developed to quantify the green-islands symptom, which was measured at 12 weeks post-bacterial inoculation, along with leaf scorch and percentage of xylem vessels blocked by occlusions. Canes of resistant genotypes matured normally and had a significantly lower CMI score of 0.9 (on a 0-to-6 scale) compared with 5.1 for the susceptible genotypes. The CMI scoring method had a high correlation (R(2) = 0.91) with previously characterized field performance, whereas leaf scorch had only a moderate correlation (R(2) = 0.51) with field performance. Average scorched area on leaves of the susceptible and resistant genotypes was 80 and 48%, respectively, demonstrating that leaf scorch can be extensive in resistant genotypes under the presented screening conditions, and suggesting that systemic infection can occur in all evaluated genotypes. Occlusions within both stem and petiole vessels were composed principally of tyloses and were significantly higher in petioles than in stems of either resistant or susceptible backgrounds. Susceptible genotypes displayed a higher level of stem tylose occlusions relative to resistant genotypes, but correlation to field performance was low (R(2) = 0.13). Ease of use and high correlation to field performance makes CMI scoring a better choice for PD resistance evaluations relative to other phenotypic symptom assessments.

  2. Tensile and fatigue behaviour of self-piercing rivets of CFRP to aluminium for automotive application

    Science.gov (United States)

    Kang, J.; Rao, H.; Zhang, R.; Avery, K.; Su, X.

    2016-07-01

    In this study, the tensile and fatigue behaviour of self-piercing rivets (SPRs) in carbon fibre reinforced plastic (CFRP) to aluminium 6111 T82 alloys were evaluated. An average maximum lap-shear tensile load capacity of 3858 N was achieved, which is comparable to metal-to-metal SPR lap-shear joints. The CFRP-Al SPRs failed in lap-shear tension due to pull-out of the rivet head from the CFRP upper sheet. The CFRP-Al SPR lap- shear specimens exhibited superior fatigue life compared to previously studied aluminium-to- aluminium SPR lap-shear joints. The SPR lap-shear joints under fatigue loads failed predominantly due to kinked crack growth along the width of the bottom aluminium sheet. The fatigue cracks initiated in the plastically deformed region of the aluminium sheet close to the rivet shank in the rivet-sheet interlock region. Scatter in fatigue life and failure modes was observed in SPR lap-shear specimens tested close to maximum tensile load.

  3. Nutritional requirements of Xylella fastidiosa, which causes Pierce's disease in grapes.

    Science.gov (United States)

    Chang, C J; Donaldson, R C

    2000-03-01

    A defined medium (XF-26) containing 3 inorganic salts, 2 tricarboxylic acids, 17 amino acids, potato starch, phenol red, and agar was used as the starting point for the study. Deletions of one or more ingredients were performed to prepare various media. A medium was considered able to support growth of Xylella fastidiosa strains responsible for Pierce's disease in grapes, only after 10 serial passages had been completed. Of 3 inorganic salts, K2HPO4 and MgSO4 x 7H2O were essential, and (NH4)2HPO4 was nonessential for growth. Of the Krebs cycle intermediates, all (citrate, alpha-ketoglutarate, succinate, fumarate, malate, and oxaloacetate) but isocitrate supported growth of cultivated strains, whereas only citrate alone or citrate plus succinate supported the primary isolation of PD bacterium. Of 17 amino acids, 6 uncharged polar R groups (asparagine, cysteine, glutamine, glycine, serine, and threonine) supported growth, whereas 8 nonpolar R groups (alanine, isoleucine, leucine, methionine, phenylalanine, proline, tryptophan, and valine) or 3 positively charged polar groups (arginine, histidine, and lysine) did not. Starch proved to be nonessential.

  4. Free-surface turbulent wake of a surface-piercing slender body at various Froude numbers

    Science.gov (United States)

    Seo, Jeonghwa; Samad, Abdus; Rhee, Shin Hyung

    2016-11-01

    Free-surface effects on the near-wake around a surface-piercing slender body were investigated through flow field and wave elevation measurements. The near-wake flow field was measured by a towed underwater stereoscopic particle image velocimetry (SPIV) system. The measured flow field was analyzed to obtain coherent turbulence structures by using the Reynolds and proper orthogonal decomposition methods. Three different Froude numbers (Fr) - 0.126, 0.282, and 0.400 - were selected to represent mild, intermediate, and violent free-surface motions. At Fr = 0.126, the wave was hardly visible, although the turbulence strength and isotropy increased near the free-surface. At Fr = 0.282, though it was steady and smooth, wave-induced separation was clearly observed near the juncture of the free-surface and model trailing edge. At Fr = 0.400, wave breaking and the resulting bubbly free-surface were developed with an expanded wave-induced separation region. The wave-induced separation stimulated momentum transfer and turbulence dissipation, resulting in a significant change in the frequency of dominant free-surface motion in the downstream. This research was supported by the IT R&D program of MOTIE/KEIT (Grant No. 100660329) and the National Research Foundation of Korea, Grant funded by the Korean government (Grant No. 2013R1A1A2012597).

  5. Overexpression of antimicrobial lytic peptides protects grapevine from Pierce's disease under greenhouse but not field conditions.

    Science.gov (United States)

    Li, Zhijian T; Hopkins, Donald L; Gray, Dennis J

    2015-10-01

    Pierce's disease (PD) caused by Xylella fastidiosa prevents cultivation of grapevine (Vitis vinifera) and susceptible hybrids in the southeastern United States and poses a major threat to the grape industry of California and Texas. Genetic resistance is the only proven control of X. fastidiosa. Genetic engineering offers an alternative to heretofore ineffective conventional breeding in order to transfer only PD resistance traits into elite cultivars. A synthetic gene encoding lytic peptide LIMA-A was introduced into V. vinifera and a Vitis hybrid to assess in planta inhibition of X. fastidiosa. Over 1050 independent transgenic plant lines were evaluated in the greenhouse, among which nine lines were selected and tested under naturally-inoculated field conditions. These selected plant lines in the greenhouse remain disease-free for 10 years, to date, even with multiple manual pathogen inoculations. However, all these lines in the field, including a grafted transgenic rootstock, succumbed to PD within 7 years. We conclude that in planta production of antimicrobial lytic peptides does not provide durable PD resistance to grapevine under field conditions.

  6. Suppression of Astronomical Sources Using Starshades and the McMath-Pierce Solar Telescope

    Science.gov (United States)

    Novicki, Megan; Warwick, Steve; Smith, Daniel; Richards, Michael; Harness, Anthony

    2016-01-01

    The external starshade is a method for the direct detection and spectral characterization of terrestrial planets around other stars, a key goal identified in ASTRO2010. Tests of this approach have been and continue to be conducted in the lab and in the field (Samuele et al., 2010, Glassman et al., 2014) using non-collimated light sources with a spherical wavefront. We extend the current approach to performing night-time observations of astronomical objects using small-scale (approximately 1/300th) starshades and the McMath-Pierce Solar Telescope at Kitt Peak National Observatory. We placed a starshade directly in the path of the beam from an astronomical object in front of the main heliostat. Using only flat mirrors, we then directed the light through the observatory path and reflected it off the West heliostat to an external telescope located approximately 270m away, for an effective baseline of 420m.This configuration allowed us to make measurements of flat wavefront sources with a Fresnel number close to those expected in proposed full-scale space configurations. We present the results of our engineering runs conducted in 2015.

  7. Ballistic Performance of Alumina and Zirconia-toughened Alumina Against 7.62 Armour Piercing Projectile

    Directory of Open Access Journals (Sweden)

    S G. Savio

    2014-09-01

    Full Text Available A study was carried out to compare the ballistic performance of high purity alumina and zirconia-toughened alumina (ZTA using depth of penetration (DoP test configuration against 7.62 mm armour piercing (AP ammunition. The effect of tile thickness on the differential efficiency factor (DEF was studied for tile thickness in the range of 3 mm to 6 mm for alumina tiles and 3 mm to 5 mm for ZTA tiles. The DEF is found to increase as tile thickness increases. An analysis on the failed shots showed that the residual shot weight does not follow a single linear relationship with ceramic tile thickness unlike the residual DoP for all thicknesses of tiles. Post-ballistic analysis on ceramic powder for particle size distribution was carried out and the results are presented.Defence Science Journal, Vol. 64, No. 5, September 2014, pp.477-483, DOI:http://dx.doi.org/10.14429/dsj.64.6745

  8. Sound scattering by free surface piercing and fluid-loaded cylindrical shells.

    Science.gov (United States)

    Avital, Eldad J; Miloh, Touvia

    2011-07-28

    A vertical flexible, thin, cylindrical shell is considered to be clamped to a rigid base in shallow water and piercing its surface. The shell is composed of an isotropic and homogeneous material and may be empty inside or filled with compressible fluid. Linear acoustics and structural dynamics are used to model sound scattering caused by an external incident sound wave. A solution is derived using a Fourier transform in the tangential and vertical directions. A collocation technique coupled with an orthogonalization procedure is used to account for the edge conditions of the shell. It is shown that zero sound scattering, indicating acoustic invisibility, is theoretically attainable and can be achieved when a continuous distribution of an oscillating pressure load is applied on the shell's wall. Similarly, zero sound transmission into the shell's inner fluid can also be considered. The possibility of using a pre-determined discrete distribution of the applied pressure load is also discussed. The derived equations are numerically solved to examine sound scattering by a thin aluminium shell in shallow water.

  9. A new approach using the Pierce two-node model for different body parts.

    Science.gov (United States)

    Foda, Ehab; Sirén, Kai

    2011-07-01

    This paper presents a new approach, in applying the Pierce two-node model, to predict local skin temperatures of individual body parts with good accuracy. In this study, local skin temperature measurements at 24 sites on the bodies of 11 human subjects were carried out in a controlled environment under three different indoor conditions (i.e. neutral, warm and cold). The neutral condition measurements were used to adjust the local skin set-points in the model for each body part. Additional modifications to the calculation algorithm were introduced corresponding to different body parts. The local core set-points were then calculated, using a line search method, as the input values that allow the model to predict the skin temperatures with maximum deviation of ±0.1°C for the neutral condition. The model predictability was verified for the other two indoor conditions, and the results show that the modified model predicts local skin temperatures with average deviation of ±0.3°C.

  10. Radiation Induced Genomic Instability

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, William F.

    2011-03-01

    Radiation induced genomic instability can be observed in the progeny of irradiated cells multiple generations after irradiation of parental cells. The phenotype is well established both in vivo (Morgan 2003) and in vitro (Morgan 2003), and may be critical in radiation carcinogenesis (Little 2000, Huang et al. 2003). Instability can be induced by both the deposition of energy in irradiated cells as well as by signals transmitted by irradiated (targeted) cells to non-irradiated (non-targeted) cells (Kadhim et al. 1992, Lorimore et al. 1998). Thus both targeted and non-targeted cells can pass on the legacy of radiation to their progeny. However the radiation induced events and cellular processes that respond to both targeted and non-targeted radiation effects that lead to the unstable phenotype remain elusive. The cell system we have used to study radiation induced genomic instability utilizes human hamster GM10115 cells. These cells have a single copy of human chromosome 4 in a background of hamster chromosomes. Instability is evaluated in the clonal progeny of irradiated cells and a clone is considered unstable if it contains three or more metaphase sub-populations involving unique rearrangements of the human chromosome (Marder and Morgan 1993). Many of these unstable clones have been maintained in culture for many years and have been extensively characterized. As initially described by Clutton et al., (Clutton et al. 1996) many of our unstable clones exhibit persistently elevated levels of reactive oxygen species (Limoli et al. 2003), which appear to be due dysfunctional mitochondria (Kim et al. 2006, Kim et al. 2006). Interestingly, but perhaps not surprisingly, our unstable clones do not demonstrate a “mutator phenotype” (Limoli et al. 1997), but they do continue to rearrange their genomes for many years. The limiting factor with this system is the target – the human chromosome. While some clones demonstrate amplification of this chromosome and thus lend

  11. Modulational instability of nematic phase

    Indian Academy of Sciences (India)

    T Mithun; K Porsezian

    2014-02-01

    We numerically observe the effect of homogeneous magnetic field on the modulationally stable case of polar phase in = 2 spinor Bose–Einstein condensates (BECs). Also we investigate the modulational instability of uniaxial and biaxial (BN) states of polar phase. Our observations show that the magnetic field triggers the modulational instability and demonstrate that irrespective of the magnetic field effect the uniaxial and biaxial nematic phases show modulational instability.

  12. Political Instability and Economic Growth

    OpenAIRE

    Swagel, Phillip; Roubini, Nouriel; Ozler, Sule; Alesina, Alberto

    1992-01-01

    This paper investigates the relationship between political instability and per capita GDP growth in a sample of 113 countries for the period 1950-1982. We define ?political instability? as the propensity of a government collapse, and we estimate a model in which political instability and economic growth are jointly determined. The main result of this paper is that in countries and time periods with a high propensity of government collapse, growth is significantly lower than otherwise. This ef...

  13. Weibel instability with nonextensive distribution

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Hui-Bin; Liu, Shi-Bing [Strong-field and Ultrafast Photonics Lab, Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China)

    2013-10-15

    Weibel instability in plasma, where the ion distribution is isotropic and the electron component of the plasma possesses the anisotropic temperature distribution, is investigated based on the kinetic theory in context of nonextensive statistics mechanics. The instability growth rate is shown to be dependent on the nonextensive parameters of both electron and ion, and in the extensive limit, the result in Maxwellian distribution plasma is recovered. The instability growth rate is found to be enhanced as the nonextensive parameter of electron increases.

  14. Instabilities in mimetic matter perturbations

    Science.gov (United States)

    Firouzjahi, Hassan; Gorji, Mohammad Ali; Mansoori, Seyed Ali Hosseini

    2017-07-01

    We study cosmological perturbations in mimetic matter scenario with a general higher derivative function. We calculate the quadratic action and show that both the kinetic term and the gradient term have the wrong sings. We perform the analysis in both comoving and Newtonian gauges and confirm that the Hamiltonians and the associated instabilities are consistent with each other in both gauges. The existence of instabilities is independent of the specific form of higher derivative function which generates gradients for mimetic field perturbations. It is verified that the ghost instability in mimetic perturbations is not associated with the higher derivative instabilities such as the Ostrogradsky ghost.

  15. [Aspirin suppresses microsatellite instability].

    Science.gov (United States)

    Wallinger, S; Dietmaier, W; Beyser, K; Bocker, T; Hofstädter, F; Fishel, R; Rüschoff, J

    1999-01-01

    Nonsteroidal anti-inflammatory drugs (NSAIDs) exhibit cancer preventive effects and have been shown to induce regression of adenomas in FAP patients. In order to elucidate the probable underlying mechanism, the effect of NSAIDs on mismatch repair related microsatellite instability was investigated. Six colorectal cancer cell lines all but one deficient for human mismatch repair (MMR) genes were examined for microsatellite instability (MSI) prior and after treatment with Aspirin or Sulindac. For rapid in vitro analysis of MSI a microcloning assay was developed by combining Laser microdissection and random (PEP-) PCR prior to specific MSI-PCR. Effects of NSAIDs on cell cycle and apoptosis were systematically investigated by using flow cytometry and cell-sorting. MSI frequency in cells deficient of MMR genes (hMSH2, hMLH1, hMSH6) was markedly reduced after long-term (> 10 weeks) NSAID treatment. This effect was reversible, time- and concentration dependent. However, in the hPMS2 deficient endometrial cancer cell line (HEC-1-A) the MSI phenotype kept unchanged. According to cell sorting, non-apoptotic cells were stable and apoptotic cells were unstable. These results suggest that aspirin/sulindac induces a genetic selection for microsatellite stability in a subset of MMR-deficient cells and may thus provide an effective prophylactic therapy for HNPCC related colorectal carcinomas.

  16. Instability of enclosed horizons

    CERN Document Server

    Kay, Bernard S

    2013-01-01

    We study the classical massless scalar wave equation on the region of 1+1-dimensional Minkowski space between the two branches of the hyperbola $x^2-t^2=1$ with vanishing boundary conditions on it. We point out that there are initially finite-energy initially, say, right-going waves for which the stress-energy tensor becomes singular on the null-line $t+x=0$. We also construct the quantum theory of this system and show that, while there is a regular Hartle-Hawking-Israel-like state, there are coherent states built on this for which there is a similar singularity in the expectation value of the renormalized stress-energy tensor. We conjecture that in 1+3-dimensional situations with 'enclosed horizons' such as a (maximally extended) Schwarzschild black hole in equilibrium in a stationary box or the (maximally extended) Schwarzschild-AdS spacetime, there will be a similar singularity at the horizon and that would signal an instability when matter perturbations and/or gravity are switched on. Such an instability ...

  17. Libration driven multipolar instabilities

    CERN Document Server

    Cébron, David; Herreman, Wietze

    2014-01-01

    We consider rotating flows in non-axisymmetric enclosures that are driven by libration, i.e. by a small periodic modulation of the rotation rate. Thanks to its simplicity, this model is relevant to various contexts, from industrial containers (with small oscillations of the rotation rate) to fluid layers of terrestial planets (with length-of-day variations). Assuming a multipolar $n$-fold boundary deformation, we first obtain the two-dimensional basic flow. We then perform a short-wavelength local stability analysis of the basic flow, showing that an instability may occur in three dimensions. We christen it the Libration Driven Multipolar Instability (LDMI). The growth rates of the LDMI are computed by a Floquet analysis in a systematic way, and compared to analytical expressions obtained by perturbation methods. We then focus on the simplest geometry allowing the LDMI, a librating deformed cylinder. To take into account viscous and confinement effects, we perform a global stability analysis, which shows that...

  18. The corrosion resistance of materials used for the manufacture of ear piercing studs

    Directory of Open Access Journals (Sweden)

    Correa, O. V.

    2003-12-01

    Full Text Available Nickel containing alloys have been widely used as substrates for the manufacture of studs used for ear piercing. Unfortunately, nickel has also been related to the development of allergic contact dermatitis caused by skin sensitization due to Ni2+ ions. Nickel ions can be leached out into the body fluids due to corrosion reactions. Defect free coatings are very difficult to produce, and therefore nickel free materials should be used as substrates of ear piercing studs, although the commercial alloys used usually contain this element. In this study, the corrosion resistance of two kinds of commercial studs prepared with nickel containing substrates and a titanium laboratory made stud was determined in a culture medium. The corrosion resistance of the studs was investigated by means of potentiodynamic polarization tests and electrochemical impedance spectroscopy as a function of immersion time in the culture medium. The elements that leached out into the medium due to corrosion reactions were analyzed by instrumental neutron activation analysis. The surfaces of the commercial gold-coated studs were examined by scanning electron microscopy and analyzed by energy dispersive spectroscopy, both before and after exposure to the culture medium. The cytotoxicity of the tested studs was also determined in the culture medium.

    Aleaciones conteniendo níquel se han utilizado como substratos para la fabricación de aretes perforantes para orejas. Desafortunadamente, el níquel ha sido relacionado con el desarrollo de una reacción alérgica conocida como dermatitis de contacto, causada por la sensibilización debido a los iones de Ni2+. Estos iones pueden ser liberados hacia los fluidos corporales debido a las reacciones de corrosión. Los aretes, habitualmente, se revisten con películas de oro. Sin embargo, es muy difícil hacer los revestimientos libres de defectos superficiales. Por lo tanto, materiales sin níquel deber

  19. Surface-Piercing Activities of the Humpback Whale, Megaptera, Related to Parasites and Mechanics}

    Science.gov (United States)

    Galvin, C.

    2006-12-01

    Humpback whales leap out of the water (breach), strike the water surface with their long fins (flipper), strike the water surface with their tail (lobtail), and hold motionless in a vertical position with their heads above water (spyhop). These four surface-piercing activities were known to early whalers, but their explanations remain uncertain. A whale breaches by swimming from depth toward the water surface at an oblique angle, propelling himself into the air at an angle to the water's surface (0 to 70 degrees), rotating about his long axis, and landing on his back, belly up to the sky. Rotation requires applying angular momentum to the whale's trunk, which photographs suggest comes from flinging out the flipper on the side rotating upward, and keeping the downward-rotating flipper closer to the trunk. The humpback has unusually long flippers (long moment arms) up to 30 percent of trunk length. Its generic name, Megaptera, can translate as `long flipper'. Continued use of one flipper as the moment arm raises the possibility of right-handed or left-handed whales, but Whitehead's (1985) data do not support that result. Parasites as a cause of breaching is a hypothesis at least as old as Beale (1839), but in the last half of the 20th century, breaching, flippering, and lobtailing came to be understood as social activities of whales. Whitehead's work in the 1980s provides much data on humpback activities, as well as a prevailing social interpretation of the data. External parasites (loosely defined) include whale lice (fingernail-sized crablike animals) and barnacles (both fixed shell and flexible goosenecked species). Thousands of these animals may inhabit a single whale. Whale lice populate crevices of the jaws and eyes, the pleats in the throat pouch under the jaw, and shelter at fixed barnacles. Fixed barnacles thrive on exposed bumps on the whale's head and flippers. Gooseneck barnacles appear in photos attached to trailing edges of fins and tail. Some parasites

  20. Surface-water hydrology and runoff simulations for three basins in Pierce County, Washington

    Science.gov (United States)

    Mastin, M.C.

    1996-01-01

    The surface-water hydrology in Clear, Clarks, and Clover Creek Basins in central Pierce County, Washington, is described with a conceptual model of the runoff processes and then simulated with the Hydrological Simulation Program-FORTRAN (HSPF), a continuous, deterministic hydrologic model. The study area is currently undergoing a rapid conversion of rural, undeveloped land to urban and suburban land that often changes the flow characteristics of the streams that drain these lands. The complex interactions of land cover, climate, soils, topography, channel characteristics, and ground- water flow patterns determine the surface-water hydrology of the study area and require a complex numerical model to assess the impact of urbanization on streamflows. The U.S. Geological Survey completed this investigation in cooperation with the Storm Drainage and Surface Water Management Utility within the Pierce County Department of Public Works to describe the important rainfall-runoff processes within the study area and to develop a simulation model to be used as a tool to predict changes in runoff characteristics resulting from changes in land use. The conceptual model, a qualitative representation of the study basins, links the physical characteristics to the runoff process of the study basins. The model incorporates 11 generalizations identified by the investigation, eight of which describe runoff from hillslopes, and three that account for the effects of channel characteristics and ground-water flow patterns on runoff. Stream discharge was measured at 28 sites and precipitation was measured at six sites for 3 years in two overlapping phases during the period of October 1989 through September 1992 to calibrate and validate the simulation model. Comparison of rainfall data from October 1989 through September 1992 shows the data-collection period beginning with 2 wet water years followed by the relatively dry 1992 water year. Runoff was simulated with two basin models-the Clover

  1. Reynolds and froude number effect on the flow past an interface-piercing circular cylinder

    Directory of Open Access Journals (Sweden)

    Koo Bonguk

    2014-09-01

    Full Text Available The two-phase turbulent flow past an interface-piercing circular cylinder is studied using a high-fidelity orthogonal curvilinear grid solver with a Lagrangian dynamic subgrid-scale model for large-eddy simulation and a coupled level set and volume of fluid method for air-water interface tracking. The simulations cover the sub-critical and critical and post critical regimes of the Reynolds and sub and super-critical Froude numbers in order to investigate the effect of both dimensionless parameters on the flow. Significant changes in flow features near the air-water interface were observed as the Reynolds number was increased from the sub-critical to the critical regime. The interface makes the separation point near the interface much delayed for all Reynolds numbers. The separation region at intermediate depths is remarkably reduced for the critical Reynolds number regime. The deep flow resembles the single-phase turbulent flow past a circular cylinder, but includes the effect of the free-surface and the limited span length for sub-critical Reynolds numbers. At different Froude numbers, the air-water interface exhibits significantly changed structures, including breaking bow waves with splashes and bubbles at high Froude numbers. Instantaneous and mean flow features such as interface structures, vortex shedding, Reynolds stresses, and vorticity transport are also analyzed. The results are compared with reference experimental data available in the literature. The deep flow is also compared with the single-phase turbulent flow past a circular cylinder in the similar ranges of Reynolds numbers. Discussion is provided concerning the limitations of the current simulations and available experimental data along with future research

  2. Vascular occlusions in grapevines with Pierce's disease make disease symptom development worse.

    Science.gov (United States)

    Sun, Qiang; Sun, Yuliang; Walker, M Andrew; Labavitch, John M

    2013-03-01

    Vascular occlusions are common structural modifications made by many plant species in response to pathogen infection. However, the functional role(s) of occlusions in host plant disease resistance/susceptibility remains controversial. This study focuses on vascular occlusions that form in stem secondary xylem of grapevines (Vitis vinifera) infected with Pierce's disease (PD) and the impact of occlusions on the hosts' water transport and the systemic spread of the causal bacterium Xylella fastidiosa in infected vines. Tyloses are the predominant type of occlusion that forms in grapevine genotypes with differing PD resistances. Tyloses form throughout PD-susceptible grapevines with over 60% of the vessels in transverse sections of all examined internodes becoming fully blocked. By contrast, tylose development was mainly limited to a few internodes close to the point of inoculation in PD-resistant grapevines, impacting only 20% or less of the vessels. The extensive vessel blockage in PD-susceptible grapevines was correlated to a greater than 90% decrease in stem hydraulic conductivity, compared with an approximately 30% reduction in the stems of PD-resistant vines. Despite the systemic spread of X. fastidiosa in PD-susceptible grapevines, the pathogen colonized only 15% or less of the vessels in any internode and occurred in relatively small numbers, amounts much too small to directly block the vessels. Therefore, we concluded that the extensive formation of vascular occlusions in PD-susceptible grapevines does not prevent the pathogen's systemic spread in them, but may significantly suppress the vines' water conduction, contributing to PD symptom development and the vines' eventual death.

  3. Three New Pierce's Disease Pathogenicity Effectors Identified Using Xylella fastidiosa Biocontrol Strain EB92-1.

    Directory of Open Access Journals (Sweden)

    Shujian Zhang

    Full Text Available Xylella fastidiosa (X. fastidiosa infects a wide range of plant hosts and causes economically serious diseases, including Pierce's Disease (PD of grapevines. X. fastidiosa biocontrol strain EB92-1 was isolated from elderberry and is infectious and persistent in grapevines but causes only very slight symptoms under ideal conditions. The draft genome of EB92-1 revealed that it appeared to be missing genes encoding 10 potential PD pathogenicity effectors found in Temecula1. Subsequent PCR and sequencing analyses confirmed that EB92-1 was missing the following predicted effectors found in Temecula1: two type II secreted enzymes, including a lipase (LipA; PD1703 and a serine protease (PD0956; two identical genes encoding proteins similar to Zonula occludens toxins (Zot; PD0915 and PD0928, and at least one relatively short, hemagglutinin-like protein (PD0986. Leaves of tobacco and citrus inoculated with cell-free, crude protein extracts of E. coli BL21(DE3 overexpressing PD1703 exhibited a hypersensitive response (HR in less than 24 hours. When cloned into shuttle vector pBBR1MCS-5, PD1703 conferred strong secreted lipase activity to Xanthomonas citri, E. coli and X. fastidiosa EB92-1 in plate assays. EB92-1/PD1703 transformants also showed significantly increased disease symptoms on grapevines, characteristic of PD. Genes predicted to encode PD0928 (Zot and a PD0986 (hemagglutinin were also cloned into pBBR1MCS-5 and moved into EB92-1; both transformants also showed significantly increased symptoms on V. vinifera vines, characteristic of PD. Together, these results reveal that PD effectors include at least a lipase, two Zot-like toxins and a possibly redundant hemagglutinin, none of which are necessary for parasitic survival of X. fastidiosa populations in grapevines or elderberry.

  4. Morphology and biology of the fruit piercing moth, Ophiusa corona (Fabricious (Lepidoptera: Noctuidae

    Directory of Open Access Journals (Sweden)

    Permkam, S.

    2006-05-01

    Full Text Available Morphology and biology of the fruit-piercing moth Ophiusa coronata (Fabricious (Lepidoptera: Noctuidae were studied in laboratory. Eggs were spherical and colored grayish green with an average diameter of 1.03±0.01 mm (mean±SEM. The larvae were looper caterpillars, possessing 2 white bands on the black head. The body was brown to blackish, marked with black spots and red longitudinal streaks. The pupa was black-brown. The adult moth had rufous and fuscous forewings tinged with a black spot in the middle. The hind wings were bright yellow in ground color with a dark band at the anterior and the posterior borders. Time required for egg to adult development averaged 40.35±0.59 days (mean±SEM. The average duration for egg, larval and pupal developments were 4.0±0.0, 23.20±0.49 and 13.15±0.22 days, respectively. Sexual maturity for female took 10.67±1.05 days. The average duration of egg laying, number of eggs and longevity of adult moths were 7.33±1.28 days, 333.0±171.82 egg/female and 22.83±2.45 days, respectively. Feeding preference and phototaxis of adult studies showed that adults likely preferred to feed ranking from slices of pineapple, banana, papaya and citrus, whereas sapodilla and rose apple were rarely fed on. Blue light and mercury vapor light were highly attractive, whereas violet light and fluorescent light were less attractive to this adult moth species.

  5. Extraction of lanthanides by polysulfone microcapsules containing EHPNA. I. Piercing method

    Institute of Scientific and Technical Information of China (English)

    靖宇; 王月; 侯海龙; 徐建鸿; 王运东

    2015-01-01

    Since the conventional liquid-liquid extraction method suffered from a series of problems such as inefficiency of one stage extraction, vast device occupation and severe emulsification, we adopted microcapsule (MC) technique to change the former liq-uid-liquid extraction to liquid-solid extraction. Firstly, the piercing method was performed to prepare the empty polysulfone (PSF) microcapsules, which was easy to implement and control. Secondly, the ultrasonic approach was utilized to prepare the functional microcapsules containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA). We focused on a key factor of the molar ratio of PSF over 1-Methyl-2-pyrrolidinone (NMP), attaining a loading ratio as high as 7.21 g-EHPNA/g-PSF. Thirdly, we examined the kinetics and thermodynamics of extraction. Kinetic results demonstrated that equilibrium was reached within two hours, with an extraction rate of Sm3+≈Er3+>La3+; Thermodynamic results showed that the extraction of lanthanides complied with the Langmuir law, with an extraction capacity of 0.25–0.30 mmol/g-microcapsule. Fourthly, stripping experiment indicated that three hours were re-quired to accomplish equilibrium for La3+ and Sm3+ while longer hours for Er3+. Finally, seven extraction-stripping cyclic experiments were performed for three mixed elements, the results of which revealed that Sm3+ and Er3+ maintained constantly high extraction amount whilst La3+ leveled off at approximately 50%. This proposed polysulfone microcapsule containing EHPNA is suitable to be applied to extraction and concentration of rare earth metals.

  6. Bony instability of the shoulder.

    Science.gov (United States)

    Bushnell, Brandon D; Creighton, R Alexander; Herring, Marion M

    2008-09-01

    Instability of the shoulder is a common problem treated by many orthopaedists. Instability can result from baseline intrinsic ligamentous laxity or a traumatic event-often a dislocation that injures the stabilizing structures of the glenohumeral joint. Many cases involve soft-tissue injury only and can be treated successfully with repair of the labrum and ligamentous tissues. Both open and arthroscopic approaches have been well described, with recent studies of arthroscopic soft-tissue techniques reporting results equal to those of the more traditional open techniques. Over the last decade, attention has focused on the concept of instability of the shoulder mediated by bony pathology such as a large bony Bankart lesion or an engaging Hill-Sachs lesion. Recent literature has identified unrecognized large bony lesions as a primary cause of failure of arthroscopic reconstruction for instability, a major cause of recurrent instability, and a difficult diagnosis to make. Thus, although such bony lesions may be relatively rare compared with soft-tissue pathology, they constitute a critically important entity in the management of shoulder instability. Smaller bony lesions may be amenable to arthroscopic treatment, but larger lesions often require open surgery to prevent recurrent instability. This article reviews recent developments in the diagnosis and treatment of bony instability.

  7. Cinerama sickness and postural instability

    NARCIS (Netherlands)

    Bos, J.E.; Ledegang, W.D.; Lubeck, A.J.A.; Stins, J.F.

    2013-01-01

    Motion sickness symptoms and increased postural instability induced by motion pictures have been reported in a laboratory, but not in a real cinema. We, therefore, carried out an observational study recording sickness severity and postural instability in 19 subjects before, immediately and 45 min af

  8. Marital instability after midlife.

    Science.gov (United States)

    Wu, Z; Penning, M J

    1997-09-01

    "Divorce in later life has been shown to produce dramatic declines in the economic, psychological, and physical well-being of marital partners. This study examines the prevalence and determinants of marital disruption after midlife using Becker's theory of marital instability. Using recent Canadian national data, the marital outcomes of women and men who were married as of age 40 are tracked across the remaining years of the marriage. Cox proportional hazard regression models indicate stabilizing effects of the duration of the marriage, the age at first marriage, the presence of young children, as well as of remarriage for middle-aged and older persons. Other significant risk factors include education, heterogamous marital status, premarital cohabitation, number of siblings, and region."

  9. Instability and Information

    CERN Document Server

    Patzelt, Felix

    2015-01-01

    Many complex systems exhibit extreme events far more often than expected for a normal distribution. This work examines how self-similar bursts of activity across several orders of magnitude can emerge from first principles in systems that adapt to information. Surprising connections are found between two apparently unrelated research topics: hand-eye coordination in balancing tasks and speculative trading in financial markets. Seemingly paradoxically, locally minimising fluctuations can increase a dynamical system's sensitivity to unpredictable perturbations and thereby facilitate global catastrophes. This general principle is studied in several domain-specific models and in behavioural experiments. It explains many findings in both fields and resolves an apparent antinomy: the coexistence of stabilising control or market efficiency and perpetual instabilities resembling critical phenomena in physical systems.

  10. Structural and Material Instability

    DEFF Research Database (Denmark)

    Cifuentes, Gustavo Cifuentes

    This work is a small contribution to the general problem of structural and material instability. In this work, the main subject is the analysis of cracking and failure of structural elements made from quasi-brittle materials like concrete. The analysis is made using the finite element method. Three...... use of interface elements) is used successfully to model cases where the path of the discontinuity is known in advance, as is the case of the analysis of pull-out of fibers embedded in a concrete matrix. This method is applied to the case of non-straight fibers and fibers with forces that have....... Numerical problems associated with the use of elements with embedded cracks based on the extended finite element method are presented in the next part of this work. And an alternative procedure is used in order to successfully remove these numerical problems. In the final part of this work, a computer...

  11. The bar instability revisited

    CERN Document Server

    Chiodi, Filippo; Claudin, Philippe

    2012-01-01

    The river bar instability is revisited, using a hydrodynamical model based on Reynolds averaged Navier-Stokes equations. The results are contrasted with the standard analysis based on shallow water Saint-Venant equations. We first show that the stability of both transverse modes (ripples) and of small wavelength inclined modes (bars) predicted by the Saint-Venant approach are artefacts of this hydrodynamical approximation. When using a more reliable hydrodynamical model, the dispersion relation does not present any maximum of the growth rate when the sediment transport is assumed to be locally saturated. The analysis therefore reveals the fundamental importance of the relaxation of sediment transport towards equilibrium as it it is responsible for the stabilisation of small wavelength modes. This dynamical mechanism is characterised by the saturation number, defined as the ratio of the saturation length to the water depth Lsat/H. This dimensionless number controls the transition from ripples (transverse patte...

  12. Beam instability Workshop - plenary sessions

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    The purpose of this workshop was to provide a review of the mechanisms of limiting beam instabilities, their cures, including feedback, and beam measurement for synchrotron radiation light sources. 12 plenary sessions took place whose titles are: 1) challenging brilliance and lifetime issues with increasing currents; 2) limiting instabilities in multibunch; 3) experience from high currents in B factories; 4) longitudinal dynamics in high intensity/bunch; 5) Transverse instabilities for high intensity/bunch; 6) working group introduction from ESRF experience; 7) impedance modelling: simulations, minimization; 8) report on the broadband impedance measurements and modelling workshop; 9) feedback systems for synchrotron light sources; 10) beam instabilities diagnostics; 11) harmonic cavities: the pros and cons; and 12) experimental study of fast beam-ion instabilities at PLS. This document gathers the 12 articles that were presented during these sessions.

  13. Equilibrium Electro-osmotic Instability

    CERN Document Server

    Rubinstein, Isaak

    2014-01-01

    Since its prediction fifteen years ago, electro-osmotic instability has been attributed to non-equilibrium electro-osmosis related to the extended space charge which develops at the limiting current in the course of concentration polarization at a charge-selective interface. This attribution had a double basis. Firstly, it has been recognized that equilibrium electro-osmosis cannot yield instability for a perfectly charge-selective solid. Secondly, it has been shown that non-equilibrium electro-osmosis can. First theoretical studies in which electro-osmotic instability was predicted and analyzed employed the assumption of perfect charge-selectivity for the sake of simplicity and so did the subsequent numerical studies of various time-dependent and nonlinear features of electro-osmotic instability. In this letter, we show that relaxing the assumption of perfect charge-selectivity (tantamount to fixing the electrochemical potential in the solid) allows for equilibrium electro-osmotic instability. Moreover, we s...

  14. Instability in Shocked Granular Gases

    CERN Document Server

    Sirmas, Nick; Radulescu, Matei

    2013-01-01

    Shocks in granular media, such as vertically oscillated beds, have been shown to develop instabilities. Similar jet formation has been observed in explosively dispersed granular media. Our previous work addressed this instability by performing discrete-particle simulations of inelastic media undergoing shock compression. By allowing finite dissipation within the shock wave, instability manifests itself as distinctive high density non-uniformities and convective rolls within the shock structure. In the present study we have extended this work to investigate this instability at the continuum level. We modeled the Euler equations for granular gases with a modified cooling rate to include an impact velocity threshold necessary for inelastic collisions. Our results showed a fair agreement between the continuum and discrete-particle models. Discrepancies, such as higher frequency instabilities in our continuum results may be attributed to the absence of higher order effects.

  15. Instability in shocked granular gases

    Science.gov (United States)

    Sirmas, Nick; Falle, Sam; Radulescu, Matei

    2014-05-01

    Shocks in granular media, such as vertically oscillated beds, have been shown to develop instabilities. Similar jet formation has been observed in explosively dispersed granular media. Our previous work addressed this instability by performing discrete-particle simulations of inelastic media undergoing shock compression. By allowing finite dissipation within the shock wave, instability manifests itself as distinctive high density non-uniformities and convective rolls within the shock structure. In the present study we have extended this work to investigate this instability at the continuum level. We modeled the Euler equations for granular gases with a modified cooling rate to include an impact velocity threshold necessary for inelastic collisions. Our results showed a fair agreement between the continuum and discrete-particle models. Discrepancies, such as higher frequency instabilities in our continuum results may be attributed to the absence of higher order effects.

  16. Gravitational Instabilities in Circumstellar Disks

    CERN Document Server

    Kratter, Kaitlin M

    2016-01-01

    [Abridged] Star and planet formation are the complex outcomes of gravitational collapse and angular momentum transport mediated by protostellar and protoplanetary disks. In this review we focus on the role of gravitational instability in this process. We begin with a brief overview of the observational evidence for massive disks that might be subject to gravitational instability, and then highlight the diverse ways in which the instability manifests itself in protostellar and protoplanetary disks: the generation of spiral arms, small scale turbulence-like density fluctuations, and fragmentation of the disk itself. We present the analytic theory that describes the linear growth phase of the instability, supplemented with a survey of numerical simulations that aim to capture the non-linear evolution. We emphasize the role of thermodynamics and large scale infall in controlling the outcome of the instability. Despite apparent controversies in the literature, we show a remarkable level of agreement between analyt...

  17. Gravitational Instabilities in Circumstellar Disks

    Science.gov (United States)

    Kratter, Kaitlin; Lodato, Giuseppe

    2016-09-01

    Star and planet formation are the complex outcomes of gravitational collapse and angular momentum transport mediated by protostellar and protoplanetary disks. In this review, we focus on the role of gravitational instability in this process. We begin with a brief overview of the observational evidence for massive disks that might be subject to gravitational instability and then highlight the diverse ways in which the instability manifests itself in protostellar and protoplanetary disks: the generation of spiral arms, small-scale turbulence-like density fluctuations, and fragmentation of the disk itself. We present the analytic theory that describes the linear growth phase of the instability supplemented with a survey of numerical simulations that aim to capture the nonlinear evolution. We emphasize the role of thermodynamics and large-scale infall in controlling the outcome of the instability. Despite apparent controversies in the literature, we show a remarkable level of agreement between analytic predictions and numerical results. In the next part of our review, we focus on the astrophysical consequences of the instability. We show that the disks most likely to be gravitationally unstable are young and relatively massive compared with their host star, Md/M*≥0.1. They will develop quasi-stable spiral arms that process infall from the background cloud. Although instability is less likely at later times, once infall becomes less important, the manifestations of the instability are more varied. In this regime, the disk thermodynamics, often regulated by stellar irradiation, dictates the development and evolution of the instability. In some cases the instability may lead to fragmentation into bound companions. These companions are more likely to be brown dwarfs or stars than planetary mass objects. Finally, we highlight open questions related to the development of a turbulent cascade in thin disks and the role of mode-mode coupling in setting the maximum angular

  18. Evaluation of an URANS-LES Hybrid Approach for Turbulent Free Surface Flows Around Surface-Piercing Bodies

    Science.gov (United States)

    2007-10-01

    fraction is obtained from its transport of-fluid (VOF) method. The same surface-piercing equation hydrofoil is considered with a rectangular plan-form...time-scale to be Hydrofoil resolved was computed from r = / u’, where £ was The computational domain is bounded by an taken as 0.02 c, and u’as 0.5U0...chord-lengths forward and aft state, we took steady RANS solution as the initial from the leading-edge of the hydrofoil , respectively, condition. The

  19. [Tatoos, piercing: body art? Body damage? Debasement of the body or return to a primitive way of life?].

    Science.gov (United States)

    Grognard, C

    2006-01-01

    Tatoos and piercing, though they might appear as something like a trend, if not a craze, remain for a majority minority and even fringe practices. For the adolescent, questing for his identity (no more a child, not yet an adult), the tegmental sign is a way of engraving in the flesh dramatic events of his existence. The body mark is a search for independence, a symbolic attainment of self-reliance, a way of severing the umbilical cord and of asserting oneself. In face of a life no longer under control, the body is an object at hand, on which self-will is almost unbridled... These body modifications testify to change.

  20. Abelianization of QCD plasma instabilities

    Science.gov (United States)

    Arnold, Peter; Lenaghan, Jonathan

    2004-12-01

    QCD plasma instabilities appear to play an important role in the equilibration of quark-gluon plasmas in heavy-ion collisions in the theoretical limit of weak coupling (i.e. asymptotically high energy). It is important to understand what nonlinear physics eventually stops the exponential growth of unstable modes. It is already known that the initial growth of plasma instabilities in QCD closely parallels that in QED. However, once the unstable modes of the gauge fields grow large enough for non-Abelian interactions between them to become important, one might guess that the dynamics of QCD plasma instabilities and QED plasma instabilities become very different. In this paper, we give suggestive arguments that non-Abelian self-interactions between the unstable modes are ineffective at stopping instability growth, and that the growing non-Abelian gauge fields become approximately Abelian after a certain stage in their growth. This in turn suggests that understanding the development of QCD plasma instabilities in the nonlinear regime may have close parallels to similar processes in traditional plasma physics. We conjecture that the physics of collisionless plasma instabilities in SU(2) and SU(3) gauge theory becomes equivalent, respectively, to (i) traditional plasma physics, which is U(1) gauge theory, and (ii) plasma physics of U(1)×U(1) gauge theory.

  1. Tatuajes y piercing: consideraciones sobre el alcance de una ordenanza municipal en la ciudad de Córdoba Tattoos and piercing: considerations about the scope of a municipal statue in Cordoba city

    Directory of Open Access Journals (Sweden)

    J M Verduzco

    2008-09-01

    Full Text Available Las ordenanzas municipales son herramientas legales, a través de las cuales los municipios o comunas ejercen un control sobre diversas actividades, algunas de las cuales como el caso de la práctica de tatuajes y piercing, pueden ser nocivas para la salud. La Municipalidad de Córdoba a través de la Ordenanza Nº 10962, sancionada el 6 de Octubre de 2005, intenta controlar esta ancestral práctica realizada sobre la piel humana. El presente trabajo tiene como finalidad analizar el articulado de esta Ordenanza y hacer algunas consideraciones sobre su utilidad en la prevención de enfermedades.Municipal statues are legal tools ratified by the municipal legislative power, stablishing rules in the corresponding scope. This rules have the aim of regulating different activities, over which the Municipality police power is excercised. Many of this activities are related to public health, because they can cause diseases in the population exposed to them. The practice of tattoing and piercing is one of this activities able to cause diseases. Due to this fact, the Municipality of Córdoba has sanctioned statue 10962 in order to control this ancestral practice.

  2. [Body modifications and sexual health : Impact of tattoos, body piercing and esthetic genital plastic surgery on the sexual health of women and men].

    Science.gov (United States)

    Stirn, Aglaja Valentina; Zannoni, Ronja

    2017-07-25

    The present paper addresses the psychological impact of body modifications (e.g. tattoos, body piercing and esthetic genital plastic surgery) on the sexual health of individuals and refers to past and present research insights. Body modifications are understood as invasive interventions on the human body, especially interventions on the human skin which result in (semi-)permanent changes. Tattoos and body piercing (in particular genital piercing) positively affect the sexual satisfaction and the sexual appeal of men and women but there is a controversial association with high risk sexual behavior. Moreover, this article focuses on esthetic genital plastic surgery based on the increasing interest and insights of the impact on female genital self-perception and sexual behavior.

  3. Instability of ties in compression

    DEFF Research Database (Denmark)

    Buch-Hansen, Thomas Cornelius

    2013-01-01

    Masonry cavity walls are loaded by wind pressure and vertical load from upper floors. These loads results in bending moments and compression forces in the ties connecting the outer and the inner wall in a cavity wall. Large cavity walls are furthermore loaded by differential movements from...... exact instability solutions are complex to derive, not to mention the extra complexity introducing dimensional instability from the temperature gradients. Using an inverse variable substitution and comparing an exact theory with an analytical instability solution a method to design tie...

  4. Microsatellite instability in bladder cancer

    DEFF Research Database (Denmark)

    Gonzalez-Zulueta, M; Ruppert, J M; Tokino, K;

    1993-01-01

    Somatic instability at microsatellite repeats was detected in 6 of 200 transitional cell carcinomas of the bladder. Instabilities were apparent as changes in (GT)n repeat lengths on human chromosome 9 for four tumors and as alterations in a (CAG)n repeat in the androgen receptor gene on the X...... chromosome for three tumors. Single locus alterations were detected in three tumors, while three other tumors revealed changes in two or more loci. In one tumor we found microsatellite instability in all five loci analyzed on chromosome 9. The alterations detected were either minor 2-base pair changes...

  5. Subject to Instability

    Directory of Open Access Journals (Sweden)

    Karen Bouwer

    2000-06-01

    Full Text Available For Plantier, language constitutes reality and is male dominated. Readers of texts, she says, are at a disadvantage because the author imposes a logic that we must accept in order to understand the text. The discourses shaping our social reality have the same effect. Plantier has struggled against individual voices, discourses, and the very fabric of language informed by these discourses. "Subject to Instability" examines the impact on her generic evolution of a changing sense of self, of who her interlocutors are, and of those for whom she is speaking. I argue that her increasing attempt to juggle many different voices destabilizes her "monologic," poetical voice, resulting in a blurring of generic boundaries and eventually the abandonment of poetry. Recognizing that our entry into language is a form of alienation also unsettles Plantier because it undermines the very identity that allows her to speak for others. She concludes that each woman needs to become a Subject in her own right, but she continues to struggle against dominant discourses, modeling "resisting reader" strategies. If she can no longer practice "monologic steadfastness," this does not deter her from attempting to dismantle patriarchal language and striving to make her voice prevail over others.

  6. Solution of the Pierce problem near a corner of a rectilinear flow with a polygonal cross-section

    CERN Document Server

    Kotelnikov, Igor A

    2014-01-01

    An ill-posed problem of synthesis of the Pierce electrodes for a cylindrical beam with a polygonal cross-section is considered. It is assumed that a beam of charged particles is extracted from a space-charge-limited planar diode and the Pierce electrodes outside of the beam ensure its zero angular divergence. A mathematical statement of the problem presumes a computation of the electrostatic potential outside of the beam that should match the Child-Langmuir 1D potential inside of the beam. An exact solution is first obtained for the potential outside of the beam near its right angle. The solution involves double analytic continuation and a numerical integration of the hypergeometric function and can be used as a benchmark for testing numerical codes. It is shown that equipotential surfaces have fractures that can be pushed away from the corner of the beam by means of smoothing the beam corners. This solution is then generalized to an angle of arbitrary magnitude.

  7. Nickel sensitization in adolescents and association with ear piercing, use of dental braces and hand eczema. The Odense Adolescence Cohort Study on Atopic Diseases and Dermatitis (TOACS)

    DEFF Research Database (Denmark)

    Mørtz, Charlotte G; Lauritsen, Jens Martin; Bindslev-Jensen, Carsten;

    2002-01-01

    % of cases. Nickel allergy was found most frequently in girls and the association with ear piercing was confirmed. Application of dental braces (oral nickel exposure) prior to ear piercing (cutaneous nickel exposure) was associated with a significantly reduced prevalence of nickel allergy. In adolescents...... a significant association was found between hand eczema and nickel allergy. A follow-up study of this population is planned in order to assess the course and development of contact dermatitis, hand eczema and atopic diseases in adulthood and after choice of occupation....

  8. Surface-micromachined 1MHz oscillator with low-noise Pierce configuration

    Energy Technology Data Exchange (ETDEWEB)

    Roessig, T.A.; Howe, R.T.; Pisano, A.P. [Univ. of California, Berkeley, CA (United States); Smith, J.H. [Sandia National Labs., Albuquerque, NM (United States)

    1998-06-01

    A prototype high frequency tuning fork oscillator has been fabricated and tested in an integrated surface micromachining technology. The amplifier circuitry uses a capacitive current detection method, which offers superior noise performance over previous resistive methods. The prototype device has an output frequency of 1.022 MHz and exhibits a noise floor of {minus}88 dBc/Hz at a distance of 500 Hz from the carrier. The dominant source of frequency instability is the nonlinearity introduced by the use of parallel plate actuation.

  9. Atlantoaxial instability in Down's syndrome

    OpenAIRE

    J Gordon Millichap

    1987-01-01

    The radiographs and clinical evaluations of 90 children with Down’s syndrome were reassessed after an interval of 5 years in a study of atlantoaxial instability (AAI) at the Derbyshire Children’s Hospital and Infirmary, Derby, UK.

  10. Evaporative instabilities in climbing films

    Science.gov (United States)

    Hosoi, A. E.; Bush, John W. M.

    2001-09-01

    We consider flow in a thin film generated by partially submerging an inclined rigid plate in a reservoir of ethanol or methanol water solution and wetting its surface. Evaporation leads to concentration and surface tension gradients that drive flow up the plate. An experimental study indicates that the climbing film is subject to two distinct instabilities. The first is a convective instability characterized by flattened convection rolls aligned in the direction of flow and accompanied by free-surface deformations; in the meniscus region, this instability gives rise to pronounced ridge structures aligned with the mean flow. The second instability, evident when the plate is nearly vertical, takes the form of transverse surface waves propagating up the plate.

  11. Intrinsic Instability of Coronal Streamers

    CERN Document Server

    Chen, Y; Song, H Q; Shi, Q Q; Feng, S W; Xia, L D; 10.1088/0004-637X/691/2/1936

    2009-01-01

    Plasma blobs are observed to be weak density enhancements as radially stretched structures emerging from the cusps of quiescent coronal streamers. In this paper, it is suggested that the formation of blobs is a consequence of an intrinsic instability of coronal streamers occurring at a very localized region around the cusp. The evolutionary process of the instability, as revealed in our calculations, can be described as follows: (1) through the localized cusp region where the field is too weak to sustain the confinement, plasmas expand and stretch the closed field lines radially outward as a result of the freezing-in effect of plasma-magnetic field coupling; the expansion brings a strong velocity gradient into the slow wind regime providing the free energy necessary for the onset of a subsequent magnetohydrodynamic instability; (2) the instability manifests itself mainly as mixed streaming sausage-kink modes, the former results in pinches of elongated magnetic loops to provoke reconnections at one or many loc...

  12. Material Instabilities in Particulate Systems

    Science.gov (United States)

    Goddard, J. D.

    1999-01-01

    Following is a brief summary of a theoretical investigation of material (or constitutive) instability associated with shear induced particle migration in dense particulate suspensions or granular media. It is shown that one can obtain a fairly general linear-stability analysis, including the effects of shear-induced anisotropy in the base flow as well as Reynolds dilatancy. A criterion is presented here for simple shearing instability in the absence of inertia and dilatancy.

  13. Instability following total knee arthroplasty.

    Science.gov (United States)

    Rodriguez-Merchan, E Carlos

    2011-10-01

    Background Knee prosthesis instability (KPI) is a frequent cause of failure of total knee arthroplasty. Moreover, the degree of constraint required to achieve immediate and long-term stability in total knee arthroplasty (TKA) is frequently debated. Questions This review aims to define the problem, analyze risk factors, and review strategies for prevention and treatment of KPI. Methods A PubMed (MEDLINE) search of the years 2000 to 2010 was performed using two key words: TKA and instability. One hundred and sixty-five initial articles were identified. The most important (17) articles as judged by the author were selected for this review. The main criteria for selection were that the articles addressed and provided solutions to the diagnosis and treatment of KPI. Results Patient-related risk factors predisposing to post-operative instability include deformity requiring a large surgical correction and aggressive ligament release, general or regional neuromuscular pathology, and hip or foot deformities. KPI can be prevented in most cases with appropriate selection of implants and good surgical technique. When ligament instability is anticipated post-operatively, the need for implants with a greater degree of constraint should be anticipated. In patients without significant varus or valgus malalignment and without significant flexion contracture, the posterior cruciate ligament (PCL) can be retained. However, the PCL should be sacrificed when deformity exists particularly in patients with rheumatoid arthritis, previous patellectomy, previous high tibial osteotomy or distal femoral osteotomy, and posttraumatic osteoarthritis with disruption of the PCL. In most cases, KPI requires revision surgery. Successful outcomes can only be obtained if the cause of KPI is identified and addressed. Conclusions Instability following TKA is a common cause of the need for revision. Typically, knees with deformity, rheumatoid arthritis, previous patellectomy or high tibial osteotomy, and

  14. Midcarpal instability: a radiological perspective

    Energy Technology Data Exchange (ETDEWEB)

    Toms, Andoni Paul [Norfolk and Norwich University Hospital NHS Trust, Department of Radiology, Norwich, Norfolk (United Kingdom); Radiology Academy, Cotman Centre, Norwich, Norfolk (United Kingdom); Chojnowski, Adrian [Norfolk and Norwich University Hospital NHS Trust, Department of Orthopaedic Surgery, Norwich, Norfolk (United Kingdom); Cahir, John G. [Norfolk and Norwich University Hospital NHS Trust, Department of Radiology, Norwich, Norfolk (United Kingdom)

    2011-05-15

    Midcarpal instability (MCI) is the result of complex abnormal carpal motion at the midcarpal joint of the wrist. It is a form of non-dissociative carpal instability (CIND) and can be caused by various combinations of extrinsic ligament injuries that then result in one of several subtypes of MCI. The complex patterns of injury and the kinematics are further complicated by competing theories, terminology and classifications of MCI. Palmar, dorsal, ulna midcarpal instability, and capitolunate or chronic capitolunate instability are all descriptions of types of MCI with often overlapping features. Palmar midcarpal instability (PMCI) is the most commonly reported type of MCI. It has been described as resulting from deficiencies in the ulna limb of the palmar arcuate ligament (triquetrohamate-capitate) or the dorsal radiotriquetral ligaments, or both. Unstable carpal articulations can be treated with limited carpal arthrodesis or the ligamentous defects can be treated with capsulorrhaphy or ligament reconstruction. Conventional radiographic abnormalities are usually limited to volar intercalated segment instability (VISI) patterns of carpal alignment and are not specific. For many years stress view radiographs and videofluoroscopy have been the methods of choice for demonstrating carpal instability and abnormal carpal kinematics respectively. Dynamic US can be also used to demonstrate midcarpal dyskinesia including the characteristic triquetral ''catch-up'' clunk. Tears of the extrinsic ligaments can be demonstrated with MR arthrography, and probably with CT arthrography, but intact yet redundant ligaments are more difficult to identify. The exact role of these investigations in the diagnosis, categorisation and management of midcarpal instability has yet to be determined. (orig.)

  15. Instability of enclosed horizons

    Science.gov (United States)

    Kay, Bernard S.

    2015-03-01

    We point out that there are solutions to the scalar wave equation on dimensional Minkowski space with finite energy tails which, if they reflect off a uniformly accelerated mirror due to (say) Dirichlet boundary conditions on it, develop an infinite stress-energy tensor on the mirror's Rindler horizon. We also show that, in the presence of an image mirror in the opposite Rindler wedge, suitable compactly supported arbitrarily small initial data on a suitable initial surface will develop an arbitrarily large stress-energy scalar near where the two horizons cross. Also, while there is a regular Hartle-Hawking-Israel-like state for the quantum theory between these two mirrors, there are coherent states built on it for which there are similar singularities in the expectation value of the renormalized stress-energy tensor. We conjecture that in other situations with analogous enclosed horizons such as a (maximally extended) Schwarzschild black hole in equilibrium in a (stationary spherical) box or the (maximally extended) Schwarzschild-AdS spacetime, there will be similar stress-energy singularities and almost-singularities—leading to instability of the horizons when gravity is switched on and matter and gravity perturbations are allowed for. All this suggests it is incorrect to picture a black hole in equilibrium in a box or a Schwarzschild-AdS black hole as extending beyond the past and future horizons of a single Schwarzschild (/Schwarzschild-AdS) wedge. It would thus provide new evidence for 't Hooft's brick wall model while seeming to invalidate the picture in Maldacena's ` Eternal black holes in AdS'. It would thereby also support the validity of the author's matter-gravity entanglement hypothesis and of the paper ` Brick walls and AdS/CFT' by the author and Ortíz.

  16. Vector-Resonance-Multimode Instability

    Science.gov (United States)

    Sergeyev, S. V.; Kbashi, H.; Tarasov, N.; Loiko, Yu.; Kolpakov, S. A.

    2017-01-01

    The modulation and multimode instabilities are the main mechanisms which drive spontaneous spatial and temporal pattern formation in a vast number of nonlinear systems ranging from biology to laser physics. Using an Er-doped fiber laser as a test bed, here for the first time we demonstrate both experimentally and theoretically a new type of a low-threshold vector-resonance-multimode instability which inherits features of multimode and modulation instabilities. The same as for the multimode instability, a large number of longitudinal modes can be excited without mode synchronization. To enable modulation instability, we modulate the state of polarization of the lasing signal with the period of the beat length by an adjustment of the in-cavity birefringence and the state of polarization of the pump wave. As a result, we show the regime's tunability from complex oscillatory to periodic with longitudinal mode synchronization in the case of resonance matching between the beat and cavity lengths. Apart from the interest in laser physics for unlocking the tunability and stability of dynamic regimes, the proposed mechanism of the vector-resonance-multimode instability can be of fundamental interest for the nonlinear dynamics of various distributed systems.

  17. Elliptic and magneto-elliptic instabilities

    Directory of Open Access Journals (Sweden)

    Lyra Wladimir

    2013-04-01

    Full Text Available Vortices are the fundamental units of turbulent flow. Understanding their stability properties therefore provides fundamental insights on the nature of turbulence itself. In this contribution I briely review the phenomenological aspects of the instability of elliptic streamlines, in the hydro (elliptic instability and hydromagnetic (magneto-elliptic instability regimes. Vortex survival in disks is a balance between vortex destruction by these mechanisms, and vortex production by others, namely, the Rossby wave instability and the baroclinic instability.

  18. A systematic review of animal predation creating pierced shells: implications for the archaeological record of the Old World

    Directory of Open Access Journals (Sweden)

    Anna Maria Kubicka

    2017-01-01

    Full Text Available Background The shells of molluscs survive well in many sedimentary contexts and yield information about the diet of prehistoric humans. They also yield evidence of symbolic behaviours through their use as beads for body adornments. Researchers often analyse the location of perforations in shells to make judgements about their use as symbolic objects (e.g., beads, the assumption being that holes attributable to deliberate human behaviour are more likely to exhibit low variability in their anatomical locations, while holes attributable to natural processes yield more random perforations. However, there are non-anthropogenic factors that can cause perforations in shells and these may not be random. The aim of the study is compare the variation in holes in shells from archaeological sites from the Old World with the variation of holes in shells pierced by mollusc predators. Methods Three hundred and sixteen scientific papers were retrieved from online databases by using keywords, (e.g., ‘shell beads’; ‘pierced shells’; ‘drilling predators’; 79 of these publications enabled us to conduct a systematic review to qualitatively assess the location of the holes in the shells described in the published articles. In turn, 54 publications were used to assess the location of the holes in the shells made by non-human predators. Results Almost all archaeological sites described shells with holes in a variety of anatomical locations. High variation of hole-placement was found within the same species from the same site, as well as among sites. These results contrast with research on predatory molluscs, which tend to be more specific in where they attacked their prey. Gastropod and bivalve predators choose similar hole locations to humans. Discussion Based on figures in the analysed articles, variation in hole-location on pierced shells from archaeological sites was similar to variation in the placement of holes created by non-human animals

  19. A systematic review of animal predation creating pierced shells: implications for the archaeological record of the Old World

    Science.gov (United States)

    Rosin, Zuzanna M.; Tryjanowski, Piotr

    2017-01-01

    Background The shells of molluscs survive well in many sedimentary contexts and yield information about the diet of prehistoric humans. They also yield evidence of symbolic behaviours through their use as beads for body adornments. Researchers often analyse the location of perforations in shells to make judgements about their use as symbolic objects (e.g., beads), the assumption being that holes attributable to deliberate human behaviour are more likely to exhibit low variability in their anatomical locations, while holes attributable to natural processes yield more random perforations. However, there are non-anthropogenic factors that can cause perforations in shells and these may not be random. The aim of the study is compare the variation in holes in shells from archaeological sites from the Old World with the variation of holes in shells pierced by mollusc predators. Methods Three hundred and sixteen scientific papers were retrieved from online databases by using keywords, (e.g., ‘shell beads’; ‘pierced shells’; ‘drilling predators’); 79 of these publications enabled us to conduct a systematic review to qualitatively assess the location of the holes in the shells described in the published articles. In turn, 54 publications were used to assess the location of the holes in the shells made by non-human predators. Results Almost all archaeological sites described shells with holes in a variety of anatomical locations. High variation of hole-placement was found within the same species from the same site, as well as among sites. These results contrast with research on predatory molluscs, which tend to be more specific in where they attacked their prey. Gastropod and bivalve predators choose similar hole locations to humans. Discussion Based on figures in the analysed articles, variation in hole-location on pierced shells from archaeological sites was similar to variation in the placement of holes created by non-human animals. Importantly, we found that

  20. A Reassessment of George Pierce Baker's "The Principles of Argumentation": Minimizing the Use of Formal Logic in Favor of Practical Approaches

    Science.gov (United States)

    Bordelon, Suzanne

    2006-01-01

    In this article, the author demonstrated how recent histories relied primarily on previous accounts and one textbook to characterize George Pierce Baker's work. This narrow assessment of "The Principles of Argumentation" limits one's understanding of his contribution to argumentation theory and pedagogy. Similarly, one has seen the need for care…

  1. SPR Characteristics Curve and Distribution of Residual Stress in Self-Piercing Riveted Joints of Steel Sheets

    Directory of Open Access Journals (Sweden)

    Rezwanul Haque

    2017-01-01

    Full Text Available Neutron diffraction was used to describe the residual stress distributions in self-piercing riveted (SPR joints. The sheet material displayed a compressive residual stress near the joint, and the stress gradually became tensile in the sheet material far away from the joint. The stress in the rivet leg was lower in the thick joint of the softer steel sheet than in the thin joint of the harder steel sheet. This lower magnitude was attributed to the lower force gradient during the rivet flaring stage of the SPR process curve. This study shows how the residual stress results may be related to the physical occurrences that happened during joining, using the characteristics curve. The study also shows that neutron diffraction technique enabled a crack in the rivet tip to be detected which was not apparent from a cross-section.

  2. NORMAL INCIDENCE SOUND ABSORPTION COEFFICIENT OF DIRECT PIERCING CARVED WOOD PANEL WITH DAUN SIREH MOTIF USING BOUNDARY ELEMENT METHOD

    Directory of Open Access Journals (Sweden)

    Mohd Zamri Jusoh

    2013-06-01

    Full Text Available The Direct Piercing Carved Wood Panel (DPCWP installed in Masjid Abidin, Kuala Terengganu, is one example that carries much aesthetic and artistic value. The use of DPCWP in earlier mosques was envisaged to improve the intelligibility of indoor speech because the perforated panels allow some of the sound energy to pass through. In this paper, the normal incidence sound absorption coefficient of DPCWP with Daun Sireh motif, which is a form of floral pattern, is discussed. The Daun Sireh motif was chosen and investigated for 30%, 35%, 40%, and 45% perforation ratios. The simulations were conducted using BEASY Acoustic Software based on the boundary element method. The simulation results were compared with measurements obtained by using the sound intensity technique. An accompanying discussion on both the numerical and the measurement tendencies of the sound absorption characteristics of the DPCWP is provided. The results show that the DPCWP with Daun Sireh motif can act as a good sound absorber.

  3. Capillarys 2 Flex Piercing 糖化血红蛋白检测系统性能验证

    Institute of Scientific and Technical Information of China (English)

    陈乔彬; 李维; 刘梦莹; 张伟; 邓玉奎; 张静

    2015-01-01

    目的:评价 Capillarys 2 Flex Piercing 全自动毛细管电泳仪检测糖化血红蛋白(HbA1c)的检测性能。方法参照美国临床实验室标准化协会(CLSI)及厂家声明对 Capillarys 2 Flex Piercing 全自动毛细管电泳仪测定 HbA1c 的精密度、正确度、可报告范围、抗干扰能力、不同检测系统结果一致性进行验证。结果Capillarys 2 Flex Piercing 全自动毛细管电泳仪检测正常HbA1c 水平的批内、批间变异系数(CV)分别为0.80%、0.92%,病理 HbA1c 水平的批内、批间 CV 分别为1.10%、1.32%;正确度验证的偏差均小于厂家声明的5%;可报告范围验证的回归方程为 Y =1.002X +0.023(r 2=0.023,P =0.000),在4.4%~18.3%范围内的检测结果能达到线性要求;在 HbA1c 浓度分别在低、中、高水平时,干扰物总胆红素、脂血、血红蛋白对测定HbA1c 的偏差绝对值均未超过5%;与 Bio-Rad Variant Ⅱ糖化血红蛋白分析仪检测结果的一致性分析的回归方程为 Y =0.9877X -0.1344(r 2=0.9942,P =0.000),呈良好的线性关系;基于生物学变异的最佳允许总误差为2.31%。结论Capillar-ys 2 Flex Piercing 全自动毛细管电泳仪检测 HbA1c 的性能达到 CLSI 指南和厂家说明书的要求,可以满足临床检测需求。

  4. Seasonal Abundance and Suppression of Fruit-Piercing Moth Eudocima phalonia (L. in a Citrus Orchard in Sarawak

    Directory of Open Access Journals (Sweden)

    Stephen Chan Teck Leong

    2011-01-01

    Full Text Available Seasonal population of the fruit-piercing moths Eudocima spp. was monitored throughout the citrus growing seasons in a citrus orchard and in site adjacent to secondary forest from July 2007 to June 2009. The moth was detected practically throughout the year with activity lowest during the wet months (September-February when fruits are still available and while highest during the dry months (May-June which also coincided with the main fruiting season. The effects of an nC24 horticultural mineral oil (HMO on the citrus fruit damage caused by fruit-piecing moths was also determined. The percent fruit damage was significantly lowest (P≤0.05 in HMO-treated plots (8.4, followed by Dimethoate-treated plots (11.6 and untreated plots (22.5. However, there was no significant difference between HMO and Dimethoate treated plots indicating HMO is effective in reducing percent fruit damage.

  5. Interfacial instabilities and Kapitsa pendula

    Science.gov (United States)

    Krieger, Madison

    2015-11-01

    Determining the critera for onset and amplitude growth of instabilities is one of the central problems of fluid mechanics. We develop a parallel between the Kapitsa effect, in which a pendulum subject to high-frequency low-amplitude vibrations becomes stable in the inverted position, and interfaces separating fluids of different density. It has long been known that such interfaces can be stabilized by vibrations, even when the denser fluid is on top. We demonstrate that the stability diagram for these fluid interfaces is identical to the stability diagram for an appopriate Kapitsa pendulum. We expand the robust, ``dictionary''-type relationship between Kapitsa pendula and interfacial instabilities by considering the classical Rayleigh-Taylor, Kelvin-Helmholtz and Plateau instabilities, as well as less-canonical examples ranging in scale from the micron to the width of a galaxy.

  6. Interfacial Instability during Granular Erosion.

    Science.gov (United States)

    Lefebvre, Gautier; Merceron, Aymeric; Jop, Pierre

    2016-02-12

    The complex interplay between the topography and the erosion and deposition phenomena is a key feature to model granular flows such as landslides. Here, we investigated the instability that develops during the erosion of a wet granular pile by a dry dense granular flow. The morphology and the propagation of the generated steps are analyzed in relation to the specific erosion mechanism. The selected flowing angle of the confined flow on a dry heap appears to play an important role both in the final state of the experiment, and for the shape of the structures. We show that the development of the instability is governed by the inertia of the flow through the Froude number. We model this instability and predict growth rates that are in agreement with the experiment results.

  7. Evaporative Instability in Binary Mixtures

    Science.gov (United States)

    Narayanan, Ranga; Uguz, Erdem

    2012-11-01

    In this talk we depict the physics of evaporative convection for binary systems in the presence of surface tension gradient effects. Two results are of importance. The first is that a binary system, in the absence of gravity, can generate an instability only when heated from the vapor side. This is to be contrasted with the case of a single component where instability can occur only when heated from the liquid side. The second result is that a binary system, in the presence of gravity, will generate an instability when heated from either the vapor or the liquid side provided the heating is strong enough. In addition to these results we show the conditions at which interfacial patterns can occur. Support from NSF OISE 0968313, Partner Univ. Fund and a Chateaubriand Fellowship is acknowledged.

  8. A new paradigm for numerical simulation of microneedle-based drug delivery aided by histology of microneedle-pierced skin.

    Science.gov (United States)

    Han, Tao; Das, Diganta Bhusan

    2015-06-01

    Microneedle (MN) is a relatively recent invention and an efficient technology for transdermal drug delivery (TDD). Conventionally, mathematical models of MNs drug delivery define the shape of the holes created by the MNs in the skin as the same as their actual geometry. Furthermore, the size of the MN holes in the skin is considered to be either the same or a certain fraction of the length of the MNs. However, the histological images of the MN-treated skin indicate that the real insertion depth is much shorter than the length of the MNs and the shapes may vary significantly from one case to another. In addressing these points, we propose a new approach for modeling MN-based drug delivery, which incorporates the histology of MN-pierced skin using a number of concepts borrowed from image processing tools. It is expected that the developed approach will provide better accuracy of the drug diffusion profile. A new computer program is developed to automatically obtain the outline of the MNs-treated holes and import these images into computer software for simulation of drug diffusion from MN systems. This method can provide a simple and fast way to test the quality of MNs design and modeling, as well as simulate experimental studies, for example, permeation experiments on MN-pierced skin using diffusion cell. The developed methodology is demonstrated using two-dimensional (2D) numerical modeling of flat MNs (2D). However, the methodology is general and can be implemented for three dimensional (3D) MNs if there is sufficient number of images for reconstructing a 3D image for numerical simulation. Numerical modeling for 3D geometry is demonstrated by using images of an ideal 3D MN. The methodology is not demonstrated for real 3D MNs, as there are not sufficient numbers of images for the purpose of this paper.

  9. Development of a model for the stiffness and life time prediction of self piercing riveted joints in automotive components

    Energy Technology Data Exchange (ETDEWEB)

    Dannbauer, H.; Gaier, C.; Dutzler, E.; Halaszi, C. [Engineering Center Steyr GmbH and Co. KG, St. Valentin (Austria). Structural Analysis Dept.

    2006-07-01

    Stiffness and strength behaviour of light weight components in the automotive industry are significantly affected by the properties of the joints. The applied joining process, the number and the location of the sopt joints have thus a large technological and economic influence. The strength of spot welds can only marginally be increased by the strength of the applied plate material. By application of high strength steels the utilization of mechanical joining techniques like self piercing riveting is recommended which exhibit higher strengths. Because of light weight design and safety aspects the application of high strength steels in the development of car bodies becomes increasingly important. For an efficient design and optimization of these complex structures reliable CAE techniques are required. For spot welding suitable models for the evaluation of strength and life time of complex structures like car bodies have already been developed, but sufficient models for calculation of self piercing riveted joints are not existent up to the present, because the strength properties of mechanical joints are more difficult to integrate. For this reason, a substitution model has been created which accounts for a correct local stiffness and enables life time assessments. The model has been calibrated based on test data and by parameters like material properties, plate thickness, rivet diameter and their combinations into account. The result is a substitution model similar to that applied to spot welding, but by consideration of additional parameters to achieve a good agreement with the experiments. Summarizing, the substitution model covers all parameters (plate thickness, rivet diameter) which are relevant in the automotive and light truck industry. (orig.)

  10. Removal of copper and iron by polyurethane foam column in FIA system for the determination of nickel in pierced ring.

    Science.gov (United States)

    Vongboot, Monnapat; Suesoonthon, Monrudee

    2015-01-01

    Polyurethane foam (PUF) mini-column was used to eliminate copper and iron for the determination of nickel in pierced rings. The PUF mini-column was connected to FIA system for on-line sorption of copper and iron in complexes form of CuSCN(+) and FeSCN(2+). For this season, the acid solution containing a mixture of Ni(II), Fe(III), Cu(II) and SCN(-) ions was firstly flew into the PUF column. Then, the percolated solution which Fe(III) and Cu(II) ions is separated from analysis was injected into FIA system to react with 4-(2-pyridylazo) resorcinol (PAR) reagent in basic condition which this method is called pH gradient technique. The Ni-PAR complexes obtained were measured theirs absorbance at 500 nm by UV visible spectrophotometer. In this study, it was found that Cu(II) and Fe(III) were completely to form complexes with 400 mmol/L KSCN and entirely to eliminate in acidic condition at pH 3.0. In the optimum condition of these experiments, the method provided the linear relationship between absorbance and the concentration of Ni(II) in the range from 5.00 to 30.00 mg/L. Linear equation is y=0.0134x+0.0033 (R(2)=0.9948). Precision, assessed in the term of the relative standard deviation, RSD, and accuracy for multiple determinations obtained in values of 0.77-1.73% and 97.4%, respectively. The level of an average amount of Ni(II) in six piercing rings was evaluated to be 14.78 mg/g.

  11. Laboratory blast wave driven instabilities

    Science.gov (United States)

    Kuranz, Carolyn

    2008-11-01

    This presentation discusses experiments involving the evolution of hydrodynamic instabilities in the laboratory under high-energy-density (HED) conditions. These instabilities are driven by blast waves, which occur following a sudden, finite release of energy, and consist of a shock front followed by a rarefaction wave. When a blast wave crosses an interface with a decrease in density, hydrodynamic instabilities will develop. Instabilities evolving under HED conditions are relevant to astrophysics. These experiments include target materials scaled in density to the He/H layer in SN1987A. About 5 kJ of laser energy from the Omega Laser facility irradiates a 150 μm plastic layer that is followed by a low-density foam layer. A blast wave structure similar to those in supernovae is created in the plastic layer. The blast wave crosses an interface having a 2D or 3D sinusoidal structure that serves as a seed perturbation for hydrodynamic instabilities. This produces unstable growth dominated by the Rayleigh-Taylor (RT) instability in the nonlinear regime. We have detected the interface structure under these conditions using x-ray backlighting. Recent advances in our diagnostic techniques have greatly improved the resolution of our x-ray radiographic images. Under certain conditions, the improved images show some mass extending beyond the RT spike and penetrating further than previously observed or predicted by current simulations. The observed effect is potentially of great importance as a source of mass transport to places not anticipated by current theory and simulation. I will discuss the amount of mass in these spike extensions, the associated uncertainties, and hypotheses regarding their origin We also plan to show comparisons of experiments using single mode and multimode as well as 2D and 3D initial conditions. This work is sponsored by DOE/NNSA Research Grants DE-FG52-07NA28058 (Stewardship Sciences Academic Alliances) and DE-FG52-04NA00064 (National Laser User

  12. Telomere dysfunction and chromosome instability

    Energy Technology Data Exchange (ETDEWEB)

    Murnane, John P., E-mail: jmurnane@radonc.ucsf.edu [Department of Radiation Oncology, University of California San Francisco, 2340 Sutter Street, San Francisco, CA 94143-1331 (United States)

    2012-02-01

    The ends of chromosomes are composed of a short repeat sequence and associated proteins that together form a cap, called a telomere, that keeps the ends from appearing as double-strand breaks (DSBs) and prevents chromosome fusion. The loss of telomeric repeat sequences or deficiencies in telomeric proteins can result in chromosome fusion and lead to chromosome instability. The similarity between chromosome rearrangements resulting from telomere loss and those found in cancer cells implicates telomere loss as an important mechanism for the chromosome instability contributing to human cancer. Telomere loss in cancer cells can occur through gradual shortening due to insufficient telomerase, the protein that maintains telomeres. However, cancer cells often have a high rate of spontaneous telomere loss despite the expression of telomerase, which has been proposed to result from a combination of oncogene-mediated replication stress and a deficiency in DSB repair in telomeric regions. Chromosome fusion in mammalian cells primarily involves nonhomologous end joining (NHEJ), which is the major form of DSB repair. Chromosome fusion initiates chromosome instability involving breakage-fusion-bridge (B/F/B) cycles, in which dicentric chromosomes form bridges and break as the cell attempts to divide, repeating the process in subsequent cell cycles. Fusion between sister chromatids results in large inverted repeats on the end of the chromosome, which amplify further following additional B/F/B cycles. B/F/B cycles continue until the chromosome acquires a new telomere, most often by translocation of the end of another chromosome. The instability is not confined to a chromosome that loses its telomere, because the instability is transferred to the chromosome donating a translocation. Moreover, the amplified regions are unstable and form extrachromosomal DNA that can reintegrate at new locations. Knowledge concerning the factors promoting telomere loss and its consequences is

  13. Stringy bounces and gradient instabilities

    CERN Document Server

    Giovannini, Massimo

    2017-01-01

    Bouncing solutions are obtained from a generally covariant action characterized by a potential which is a nonlocal functional of the dilaton field at two separated space-time points. Gradient instabilities are shown to arise in this context but they are argued to be nongeneric. After performing a gauge-invariant and frame-invariant derivation of the evolution equations of the fluctuations, a heuristic criterium for the avoidance of pathological instabilities is proposed and corroborated by a number of explicit examples that turn out to be compatible with a quasi-flat spectrum of curvature inhomogeneities for typical wavelengths larger than the Hubble radius.

  14. Research on aviation fuel instability

    Science.gov (United States)

    Baker, C. E.; Bittker, D. A.; Cohen, S. M.; Seng, G. T.

    1984-01-01

    The problems associated with aircraft fuel instability are discussed. What is currently known about the problem is reviewed and a research program to identify those areas where more research is needed is discussed. The term fuel instability generally refers to the gums, sediments, or deposits which can form as a result of a set of complex chemical reactions when a fuel is stored for a long period at ambient conditions or when the fuel is thermally stressed inside the fuel system of an aircraft.

  15. Mechanical Instabilities of Biological Tubes

    Science.gov (United States)

    Hannezo, Edouard; Prost, Jacques; Joanny, Jean-François

    2012-07-01

    We study theoretically the morphologies of biological tubes affected by various pathologies. When epithelial cells grow, the negative tension produced by their division provokes a buckling instability. Several shapes are investigated: varicose, dilated, sinuous, or sausagelike. They are all found in pathologies of tracheal, renal tubes, or arteries. The final shape depends crucially on the mechanical parameters of the tissues: Young’s modulus, wall-to-lumen ratio, homeostatic pressure. We argue that since tissues must be in quasistatic mechanical equilibrium, abnormal shapes convey information as to what causes the pathology. We calculate a phase diagram of tubular instabilities which could be a helpful guide for investigating the underlying genetic regulation.

  16. Hydromagnetic Instabilities in Neutron Stars

    CERN Document Server

    Lasky, Paul D; Kokkotas, Kostas D; Glampedakis, Kostas

    2011-01-01

    We model the non-linear ideal magnetohydrodynamics of poloidal magnetic fields in neutron stars in general relativity assuming a polytropic equation of state. We identify familiar hydromagnetic modes, in particular the 'sausage/varicose' mode and 'kink' instability inherent to poloidal magnetic fields. The evolution is dominated by the kink instability, which causes a cataclysmic reconfiguration of the magnetic field. The system subsequently evolves to new, non-axisymmetric, quasi-equilibrium end-states. The existence of this branch of stable quasi-equilibria may have consequences for magnetar physics, including flare generation mechanisms and interpretations of quasi-periodic oscillations.

  17. Political instability and illegal immigration.

    Science.gov (United States)

    Campos, J E; Lien, D

    1995-01-01

    "Economic theory suggests that transnational migration results from the push-pull effect of wage differentials between host and source countries. In this paper, we argue that political instability exacerbates the migration flow, with greater instability leading to relatively larger flows. We conclude then that an optimal solution to the illegal immigration problem requires proper coordination of immigration and foreign policies by the host country. A narrow preoccupation with tougher immigration laws is wasteful and may be marginally effective." Emphasis is on the United States as a host country.

  18. Undulation Instability of Epithelial Tissues

    CERN Document Server

    Basan, Markus; Prost, Jacques; Risler, Thomas; 10.1103/PhysRevLett.106.158101

    2011-01-01

    Treating the epithelium as an incompressible fluid adjacent to a viscoelastic stroma, we find a novel hydrodynamic instability that leads to the formation of protrusions of the epithelium into the stroma. This instability is a candidate for epithelial fingering observed in vivo. It occurs for sufficiently large viscosity, cell-division rate and thickness of the dividing region in the epithelium. Our work provides physical insight into a potential mechanism by which interfaces between epithelia and stromas undulate, and potentially by which tissue dysplasia leads to cancerous invasion.

  19. Secondary instabilities of linearly heated falling films

    Institute of Scientific and Technical Information of China (English)

    HU Jun; SUN Dejun; HU Guohui; YIN Xieyuan

    2005-01-01

    Secondary instabilities of linearly heated failing films are studied through three steps. Firstly, the analysis of the primary linear instability on Miladinova's long wave equation of the linearly heated film is performed. Secondly, the similar Landau equation is derived through weak nonlinear theory, and a two-dimensional nonlinear saturation solution of primary instability is obtained within the weak nonlinear domain. Thirdly, the secondary (three-dimensional) instability of the two-dimensional wave is studied by the Floquet theorem.Our secondary instability analysis shows that the Marangoni number has destabilization effect on the secondary instability.

  20. Edge instabilities of topological superconductors

    Science.gov (United States)

    Hofmann, Johannes S.; Assaad, Fakher F.; Schnyder, Andreas P.

    2016-05-01

    Nodal topological superconductors display zero-energy Majorana flat bands at generic edges. The flatness of these edge bands, which is protected by time-reversal and translation symmetry, gives rise to an extensive ground-state degeneracy. Therefore, even arbitrarily weak interactions lead to an instability of the flat-band edge states towards time-reversal and translation-symmetry-broken phases, which lift the ground-state degeneracy. We examine the instabilities of the flat-band edge states of dx y-wave superconductors by performing a mean-field analysis in the Majorana basis of the edge states. The leading instabilities are Majorana mass terms, which correspond to coherent superpositions of particle-particle and particle-hole channels in the fermionic language. We find that attractive interactions induce three different mass terms. One is a coherent superposition of imaginary s -wave pairing and current order, and another combines a charge-density-wave and finite-momentum singlet pairing. Repulsive interactions, on the other hand, lead to ferromagnetism together with spin-triplet pairing at the edge. Our quantum Monte Carlo simulations confirm these findings and demonstrate that these instabilities occur even in the presence of strong quantum fluctuations. We discuss the implications of our results for experiments on cuprate high-temperature superconductors.

  1. Lending sociodynamics and economic instability

    Science.gov (United States)

    Hawkins, Raymond J.

    2011-11-01

    We show how the dynamics of economic instability and financial crises articulated by Keynes in the General Theory and developed by Minsky as the Financial Instability Hypothesis can be formalized using Weidlich’s sociodynamics of opinion formation. The model addresses both the lending sentiment of a lender in isolation as well as the impact on that lending sentiment of the behavior of other lenders. The risk associated with lending is incorporated through a stochastic treatment of loan dynamics that treats prepayment and default as competing risks. With this model we are able to generate endogenously the rapid changes in lending opinion that attend slow changes in lending profitability and find these dynamics to be consistent with the rise and collapse of the non-Agency mortgage-backed securities market in 2007/2008. As the parameters of this model correspond to well-known phenomena in cognitive and social psychology, we can both explain why economic instability has proved robust to advances in risk measurement and suggest how policy for reducing economic instability might be formulated in an experimentally sound manner.

  2. The Chemistry of Beer Instability

    Science.gov (United States)

    Stewart, Graham G.

    2004-01-01

    Brewing of beer, one of the oldest biotechnology industries was one of the earliest processes to be undertaken on commercial basis. Biological instability involves contamination of bacteria, yeast, or mycelia fungi and there is always a risk in brewing that beer can become contaminated by micro-organisms.

  3. Size effects on cavitation instabilities

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Tvergaard, Viggo

    2006-01-01

    In metal-ceramic systems the constraint on plastic flow leads to so high stress triaxialities that cavitation instabilities may occur. If the void radius is on the order of magnitude of a characteristic length for the metal, the rate of void growth is reduced, and the possibility of unstable cavi...... as the void grows to a size well above the characteristic material length....

  4. Waves and instabilities in plasmas

    CERN Document Server

    Chen Liu

    1987-01-01

    The topics covered in these notes are selective and tend to emphasize more on kinetic-theory approaches to waves and instabilities in both uniform and non-uniform plasmas, students are assumed to have some basic knowledge of plasma dynamics in terms of single-particle and fluid descriptions.

  5. GENETIC INSTABILITY IN CERVICAL CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    赵旻; 伍欣星; 邱小萍; 李晖; 戴天力; 谭云

    2002-01-01

    Objective: The role of human papillomavirus (HPV) in the development of cervical carcinoma has been clearly established but other factors could be involved in cervical tumorigenesis such as loss of heterozygosity (LOH) and microsatellite instability (MI). The aim of the present study was to investigate the genetic instability in cervical carcinoma tissues and provide evidence for discoveringnew tumor suppressor genes and screening diagnostic molecular marker of cervical carcinoma. Methods: Fifty primary cervical carcinoma samples from high-incidence area were analyzed by PCR for HPV16 infection, LOH and microsatellite instability. Results: HPV16 was detected in 88% of the cases. Sixty-six percent of total cases showed LOH with no more than 3 different loci per case. The highest frequency of the allelic loss was found in D18S474 (18q21, 40.5%). MI was detected in 4 cases (8%) only. Conclusion: Different percentages of LOH on specific chromosomal regions were found and MI was very infrequent in cervical carcinoma. The putative suppressor gene(s) could be located on specific chromosome regions such as 18q, and genetic instability could be involved in cervical tumorigenesis.

  6. Singlet and triplet instability theorems

    Science.gov (United States)

    Yamada, Tomonori; Hirata, So

    2015-09-01

    A useful definition of orbital degeneracy—form-degeneracy—is introduced, which is distinct from the usual energy-degeneracy: Two canonical spatial orbitals are form-degenerate when the energy expectation value in the restricted Hartree-Fock (RHF) wave function is unaltered upon a two-electron excitation from one of these orbitals to the other. Form-degenerate orbitals tend to have isomorphic electron densities and occur in the highest-occupied and lowest-unoccupied molecular orbitals (HOMOs and LUMOs) of strongly correlated systems. Here, we present a mathematical proof of the existence of a triplet instability in a real or complex RHF wave function of a finite system in the space of real or complex unrestricted Hartree-Fock wave functions when HOMO and LUMO are energy- or form-degenerate. We also show that a singlet instability always exists in a real RHF wave function of a finite system in the space of complex RHF wave functions, when HOMO and LUMO are form-degenerate, but have nonidentical electron densities, or are energy-degenerate. These theorems provide Hartree-Fock-theory-based explanations of Hund's rule, a singlet instability in Jahn-Teller systems, biradicaloid electronic structures, and a triplet instability during some covalent bond breaking. They also suggest (but not guarantee) the spontaneous formation of a spin density wave (SDW) in a metallic solid. The stability theory underlying these theorems extended to a continuous orbital-energy spectrum proves the existence of an oscillating (nonspiral) SDW instability in one- and three-dimensional homogeneous electron gases, but only at low densities or for strong interactions.

  7. Observation of Parametric Instability in Advanced LIGO

    CERN Document Server

    Evans, Matthew; Fritschel, Peter; Miller, John; Barsotti, Lisa; Martynov, Denis; Brooks, Aidan; Coyne, Dennis; Abbott, Rich; Adhikari, Rana; Arai, Koji; Bork, Rolf; Kells, Bill; Rollins, Jameson; Smith-Lefebvre, Nicolas; Vajente, Gabriele; Yamamoto, Hiroaki; Derosa, Ryan; Effler, Anamaria; Kokeyama, Keiko; Betzweiser, Joseph; Frolov, Valera; Mullavey, Adam; O`Reilly, Brian; Dwyer, Sheila; Izumi, Kiwamu; Kawabe, Keita; Landry, Michael; Sigg, Daniel; Ballmer, Stefan; Massinger, Thomas J; Staley, Alexa; Mueller, Chris; Grote, Hartmut; Ward, Robert; King, Eleanor; Blair, David; Ju, Li; Zhao, Chunnong

    2015-01-01

    Parametric instabilities have long been studied as a potentially limiting effect in high-power interferometric gravitational wave detectors. Until now, however, these instabilities have never been observed in a kilometer-scale interferometer. In this work we describe the first observation of parametric instability in an Advanced LIGO detector, and the means by which it has been removed as a barrier to progress.

  8. Analogy between thermal convective and magnetohydrodynamic instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Valdmanis, Ya.Ya.; Kukainis, O.A.

    1977-01-01

    An examination is made of the analogy between thermo-convective instability and instability produced by various electromagnetic forces both in steady and alternating thermal and electromagnetic fields. An example is given for calculating an assumed bubble instability which could occur in an alternating magnetic field. 17 references.

  9. Amplitude Equation for Instabilities Driven at Deformable Surfaces - Rosensweig Instability

    Science.gov (United States)

    Pleiner, Harald; Bohlius, Stefan; Brand, Helmut R.

    2008-11-01

    The derivation of amplitude equations from basic hydro-, magneto-, or electrodynamic equations requires the knowledge of the set of adjoint linear eigenvectors. This poses a particular problem for the case of a free and deformable surface, where the adjoint boundary conditions are generally non-trivial. In addition, when the driving force acts on the system via the deformable surface, not only Fredholm's alternative in the bulk, but also the proper boundary conditions are required to get amplitude equations. This is explained and demonstrated for the normal field (or Rosensweig) instability in ferrofluids as well as in ferrogels. An important aspect of the problem is its intrinsic dynamic nature, although at the end the instability is stationary. The resulting amplitude equation contains cubic and quadratic nonlinearities as well as first and (in the gel case) second order time derivatives. Spatial variations of the amplitudes cannot be obtained by using simply Newell's method in the bulk.

  10. Current meter - direction and other data from the PIERCE in support of the Outer Continental Shelf - South Atlantic project from 23 October 1974 to 09 November 1974 (NODC Accession 7800778)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current meter - direction and other data were collected from the PIERCE from 23 October 1974 to 09 November 1974. Data were collected by Atlantic Oceanographic and...

  11. Water physical and chemical data from current meter and bottle casts from the G.W. PIERCE as part of the Ocean Continental Shelf - Mid Atlantic (OCS - Mid Atlantic) project, 22 October 1975 - 31 October 1975 (NODC Accession 8200067)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Water physical and chemical data were collected using current meter and bottle casts from the G.W. PIERCE from October 22, 1975 to October 31, 1975. Data were...

  12. Taxonomic code, temperature, and other data collected from net casts in North Atlantic Ocean from G.W. PIERCE; 23 October 1975 to 30 October 1975 (NODC Accession 7601641)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Taxonomic Code, temperature, and other data were collected using net casts and other instruments in the North Atlantic Ocean from G.W. PIERCE. Data were collected...

  13. Competing structural instabilities in cubic perovskites

    CERN Document Server

    Vanderbilt, D

    1994-01-01

    We study the antiferrodistortive instability and its interaction with ferroelectricity in cubic perovskite compounds. Our first-principles calculations show that coexistence of both instabilities is very common. We develop a first-principles scheme to study the thermodynamics of these compounds when both instabilities are present, and apply it to SrTiO$_3$. We find that increased pressure enhances the antiferrodistortive instability while suppressing the ferroelectric one. Moreover, the presence of one instability tends to suppress the other. A very rich $P$--$T$ phase diagram results.

  14. Body piercing and tattoo: awareness of health related risks among 4,277 Italian secondary school adolescents

    Directory of Open Access Journals (Sweden)

    Mazzoleni Francesco

    2010-02-01

    Full Text Available Abstract Background The awareness of health risks associated with body art among secondary school pupils has never previously been studied in depth. A large sample of secondary school adolescents from the Veneto Region (North East Italy were investigated in order to inform health education programs. Methods 6 public secondary schools from each of the 7 Provinces of the Veneto Region were selected. All students attending the 1st, 3rd, and 5th school years were surveyed by an anonymous self administered questionnaire on their perception of health risks related to body art and other explanatory variables. Logistic regression analysis was employed, reporting adjusted Odds Ratios (OR with 95% Confidence Interval (CI. Results Among 4,277 available students (aged 14-22 years, boys were consistently: less knowledgeable of infectious diseases related to body art (OR = 0.78; CI: 0.66, 0.94, less likely to be aware of the hygienic norms to be observed in a body art parlour (OR = 0.54; 0.44, 0.65, less likely to refer to a certified body art parlour (OR = 0.56; 0.48, 0.66, less likely to refer to a professional health care provider for complications related to body art (OR = 0.71; 0.59, 0.86. Students attending the first school year (baseline had a lesser knowledge of body art related infectious diseases, were less likely to refer to a certified body art parlour, and to know the mandatory hygienic rules to be observed when performing body modifications. Interviewees from the provinces of Rovigo and Vicenza were less likely to be conscious of the health risks associated with body modifications, and those with tattoos were less knowledgeable about the infection risk (OR = 0.60; 0.42, 0.86 and less likely to refer to a professional health care provider in case of medical complication (OR = 0.68;0.48, 0.95. Students with piercings were less likely to refer to a certified practitioner for receiving body art (OR = 0.62; 0.50, 0.77 or therapy for medical

  15. Body piercing and tattoo: awareness of health related risks among 4,277 Italian secondary school adolescents.

    Science.gov (United States)

    Cegolon, Luca; Miatto, Enrico; Bortolotto, Melania; Benetton, Mirca; Mazzoleni, Francesco; Mastrangelo, Giuseppe

    2010-02-17

    The awareness of health risks associated with body art among secondary school pupils has never previously been studied in depth. A large sample of secondary school adolescents from the Veneto Region (North East Italy) were investigated in order to inform health education programs. 6 public secondary schools from each of the 7 Provinces of the Veneto Region were selected. All students attending the 1st, 3rd, and 5th school years were surveyed by an anonymous self administered questionnaire on their perception of health risks related to body art and other explanatory variables. Logistic regression analysis was employed, reporting adjusted Odds Ratios (OR) with 95% Confidence Interval (CI). Among 4,277 available students (aged 14-22 years), boys were consistently: less knowledgeable of infectious diseases related to body art (OR = 0.78; CI: 0.66, 0.94), less likely to be aware of the hygienic norms to be observed in a body art parlour (OR = 0.54; 0.44, 0.65), less likely to refer to a certified body art parlour (OR = 0.56; 0.48, 0.66), less likely to refer to a professional health care provider for complications related to body art (OR = 0.71; 0.59, 0.86). Students attending the first school year (baseline) had a lesser knowledge of body art related infectious diseases, were less likely to refer to a certified body art parlour, and to know the mandatory hygienic rules to be observed when performing body modifications. Interviewees from the provinces of Rovigo and Vicenza were less likely to be conscious of the health risks associated with body modifications, and those with tattoos were less knowledgeable about the infection risk (OR = 0.60; 0.42, 0.86) and less likely to refer to a professional health care provider in case of medical complication (OR = 0.68;0.48, 0.95). Students with piercings were less likely to refer to a certified practitioner for receiving body art (OR = 0.62; 0.50, 0.77) or therapy for medical complications (OR = 0.37; 0.29, 0.46). Health

  16. Quad-Bike Operational Instability

    Directory of Open Access Journals (Sweden)

    Ross H. Macmillan

    2017-05-01

    Full Text Available The stake-holders in the quad-bike (QB industry in Australia have failed to reach a satisfactory resolution of the present impasse that exists with respect to the causes and mitigation of the trauma suffered by riders due to QB instability. In an effort to provide purchasers with data enabling them to discriminate between safer and less safe machines, static longitudinal and lateral tests have been conducted by various interested parties; quasi-static lateral tests have also been conducted under some operational conditions. It is argued that while these static tests are valid, under many operating conditions QBs will not reach such unstable slopes due to poor traction. Further, these tests do not include the quasi-static and dynamic factors which also influence the processes associated with operational instability. For these reasons, the static tests do not provide an adequate basis for discrimination between safer and less safe machines.

  17. Nonlinear evolution of drift instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W.W.; Krommes, J.A.; Oberman, C.R.; Smith, R.A.

    1984-01-01

    The nonlinear evolution of collisionless drift instabilities in a shear-free magnetic field has been studied by means of gyrokinetic particle simulation as well as numerical integration of model mode-coupling equations. The purpose of the investigation is to identify relevant nonlinear mechanisms responsible for the steady-state drift wave fluctuations. It is found that the saturation of the instability is mainly caused by the nonlinear E x B convection of the resonant electrons and their associated velocity space nonlinearity. The latter also induces energy exchange between the competing modes, which, in turn, gives rise to enhanced diffusion. The nonlinear E x B convection of the ions, which contributes to the nonlinear frequency shift, is also an important ingredient for the saturation.

  18. Streaming Instabilities in Protoplanetary Disks

    CERN Document Server

    Youdin, A N; Youdin, Andrew N.; Goodman, Jeremy

    2004-01-01

    Interpenetrating streams of solids and gas in a Keplerian disk produce a local, linear instability. The two components mutually interact via aerodynamic drag, which generates radial drift and triggers unstable modes. The secular instability does not require self-gravity, yet it generates growing particle density perturbations that could seed planetesimal formation. Growth rates are slower than dynamical, but faster than radial drift, timescales. Growth rates, like streaming velocities, are maximized for marginal coupling (stopping times comparable dynamical times). Fastest growth occurs when the solid to gas density ratio is order unity and feedback is strongest. Curiously, growth is strongly suppressed when the densities are too nearly equal. The relation between background drift and wave properties is explained by analogy with Howard's semicircle theorem. The three-dimensional, two-fluid equations describe a sixth order (in the complex frequency) dispersion relation. A terminal velocity approximation allows...

  19. Instability of supersymmetric microstate geometries

    CERN Document Server

    Eperon, Felicity C; Santos, Jorge E

    2016-01-01

    We investigate the classical stability of supersymmetric, asymptotically flat, microstate geometries with five non-compact dimensions. Such geometries admit an "evanescent ergosurface": a timelike hypersurface of infinite redshift. On such a surface, there are null geodesics with zero energy relative to infinity. These geodesics are stably trapped in the potential well near the ergosurface. We present a heuristic argument indicating that this feature is likely to lead to a nonlinear instability of these solutions. We argue that the precursor of such an instability can be seen in the behaviour of linear perturbations: nonlinear stability would require that all linear perturbations decay sufficiently rapidly but the stable trapping implies that some linear perturbation decay very slowly. We study this in detail for the most symmetric microstate geometries. By constructing quasinormal modes of these geometries we show that generic linear perturbations decay slower than any inverse power of time.

  20. Buckling instability of squeezed droplets

    CERN Document Server

    Elfring, Gwynn J

    2015-01-01

    Motivated by recent experiments, we consider theoretically the compression of droplets pinned at the bottom on a surface of finite area. We show that if the droplet is sufficiently compressed at the top by a surface, it will always develop a shape instability at a critical compression. When the top surface is flat, the shape instability occurs precisely when the apparent contact angle of the droplet at the pinned surface is pi, regardless of the contact angle of the upper surface, reminiscent of past work on liquid bridges and sessile droplets as first observed by Plateau. After the critical compression, the droplet transitions from a symmetric to an asymmetric shape. The force required to deform the droplet peaks at the critical point then progressively decreases indicative of catastrophic buckling. We characterize the transition in droplet shape using illustrative examples in two dimensions followed by perturbative analysis as well as numerical simulation in three dimensions. When the upper surface is not f...

  1. Stretching Folding Instability and Nanoemulsions

    CERN Document Server

    Chan, Chon U

    2009-01-01

    Here we show a folding-stretching instability in a microfluidic flow focusing device using silicon oil (100cSt) and water. The fluid dynamics video demonstrates an oscillating thread of oil focused by two co-flowing streams of water. We show several high-speed sequences of these oscillations with 30,000 frames/s. Once the thread is decelerated in a slower moving pool downstream an instability sets in and water-in-oil droplets are formed. We reveal the details of the pinch-off with 500,000 frames/s. The pinch-off is so repeatable that complex droplet patterns emerge. Some of droplets are below the resolution limit, thus smaller than 1 micrometer in diameter.

  2. Instability of ties in compression

    DEFF Research Database (Denmark)

    Buch-Hansen, Thomas Cornelius

    2013-01-01

    Masonry cavity walls are loaded by wind pressure and vertical load from upper floors. These loads results in bending moments and compression forces in the ties connecting the outer and the inner wall in a cavity wall. Large cavity walls are furthermore loaded by differential movements from...... the temperature gradient between the outer and the inner wall, which results in critical increase of the bending moments in the ties. Since the ties are loaded by combined compression and moment forces, the loadbearing capacity is derived from instability equilibrium equations. Most of them are iterative, since......-connectors in cavity walls was developed. The method takes into account constraint conditions limiting the free length of the wall tie, and the instability in case of pure compression which gives an optimal load bearing capacity. The model is illustrated with examples from praxis....

  3. Instability of supersymmetric microstate geometries

    Energy Technology Data Exchange (ETDEWEB)

    Eperon, Felicity C.; Reall, Harvey S.; Santos, Jorge E. [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

    2016-10-07

    We investigate the classical stability of supersymmetric, asymptotically flat, microstate geometries with five non-compact dimensions. Such geometries admit an “evanescent ergosurface”: a timelike hypersurface of infinite redshift. On such a surface, there are null geodesics with zero energy relative to infinity. These geodesics are stably trapped in the potential well near the ergosurface. We present a heuristic argument indicating that this feature is likely to lead to a nonlinear instability of these solutions. We argue that the precursor of such an instability can be seen in the behaviour of linear perturbations: nonlinear stability would require that all linear perturbations decay sufficiently rapidly but the stable trapping implies that some linear perturbation decay very slowly. We study this in detail for the most symmetric microstate geometries. By constructing quasinormal modes of these geometries we show that generic linear perturbations decay slower than any inverse power of time.

  4. Modern management of patellar instability.

    Science.gov (United States)

    Rhee, Shin-Jae; Pavlou, George; Oakley, Jeremy; Barlow, David; Haddad, Farres

    2012-12-01

    Recurrent patellofemoral instability is a disabling condition, attributed to a variety of anatomical aetiologies. Trochlear dysplasia, patella alta, an increased tibial tubercle trochlear groove distance of greater than 20 mm and soft tissue abnormalities such as a torn medial patellofemoral ligament and inadequate vastus medialis obliquus are all factors to be considered. Management of this condition remains difficult and controversial and knowledge of the functional anatomy and biomechanics of the patellofemoral joint, a detailed history and clinical examination, and an accurate patient assessment are all imperative to formulate an appropriate management plan. Surgical treatment is based on the underlying anatomical pathology with an aim to restore normal patellofemoral kinematics. We summarise aspects of assessment, treatment and outcome of patellofemoral instability and propose an algorithm of treatment.

  5. Mechanical Instabilities of Biological Tubes

    CERN Document Server

    Hannezo, Edouard; Prost, Jacques; 10.1103/PhysRevLett.109.018101

    2012-01-01

    We study theoretically the shapes of biological tubes affected by various pathologies. When epithelial cells grow at an uncontrolled rate, the negative tension produced by their division provokes a buckling instability. Several shapes are investigated : varicose, enlarged, sinusoidal or sausage-like, all of which are found in pathologies of tracheal, renal tubes or arteries. The final shape depends crucially on the mechanical parameters of the tissues : Young modulus, wall-to-lumen ratio, homeostatic pressure. We argue that since tissues must be in quasistatic mechanical equilibrium, abnormal shapes convey information as to what causes the pathology. We calculate a phase diagram of tubular instabilities which could be a helpful guide for investigating the underlying genetic regulation.

  6. Fluctuations and Instability in Sedimentation

    KAUST Repository

    Guazzelli, Élisabeth

    2011-01-21

    This review concentrates on the fluctuations of the velocities of sedimenting spheres, and on the structural instability of a suspension of settling fibers. For many years, theoretical estimates and numerical simulations predicted the fluctuations of the velocities of spheres to increase with the size of the container, whereas experiments found no such variation. Two ideas have increased our understanding. First, the correlation length of the velocity fluctuations was found experimentally to be 20 interparticle separations. Second, in dilute suspensions, a vertical variation in the concentration due to the spreading of the front with the clear fluid can inhibit the velocity fluctuations. In a very dilute regime, a homogeneous suspension of fibers suffers a spontaneous instability in which fast descending fiber-rich columns are separated by rising fiber-sparse columns. In a semidilute regime, the settling is hindered, more so than for spheres. © 2011 by Annual Reviews. All rights reserved.

  7. Placing Marangoni instabilities under arrest

    CERN Document Server

    Bhamla, M Saad

    2016-01-01

    Soap bubbles occupy the rare position of delighting and fascinating both young children and scientific minds alike. Sir Isaac Newton, Joseph Plateau, Carlo Marangoni, and Pierre-Gilles de Gennes, not to mention countless others, have discovered remarkable results in optics, molecular forces and fluid dynamics from investigating this seemingly simple system. We present here a compilation of curiosity-driven experiments that systematically investigate the surface flows on a rising soap bubble. From childhood experience, we are familiar with the vibrant colors and mesmerizing display of chaotic flows on the surface of a soap bubble. These flows arise due to surface tension gradients, also known as Marangoni flows or instabilities. In Figure 1, we show the surprising effect of layering multiple instabilities on top of each other, highlighting that unexpected new phenomena are still waiting to be discovered, even in the simple soap bubble.

  8. Circulation in blast driven instabilities

    Science.gov (United States)

    Henry de Frahan, Marc; Johnsen, Eric

    2016-11-01

    Mixing in many natural phenomena (e.g. supernova collapse) and engineering applications (e.g. inertial confinement fusion) is often initiated through hydrodynamic instabilities. Explosions in these systems give rise to blast waves which can interact with perturbations at interfaces between different fluids. Blast waves are formed by a shock followed by a rarefaction. This wave profile leads to complex time histories of interface acceleration. In addition to the instabilities induced by the acceleration field, the rarefaction from the blast wave decompresses the material at the interface, further increasing the perturbation growth. After the passage of the wave, circulation circulation generated by the blast wave through baroclinic vorticity continues to act upon the interface. In this talk, we provide scaling laws for the circulation and amplitude growth induced by the blast wave. Numerical simulations of the multifluid Euler equations solved using a high-order accurate Discontinuous Galerkin method are used to validate the theoretical results.

  9. MD 751: Train Instability Threshold

    CERN Document Server

    Carver, Lee Robert; Metral, Elias; Salvant, Benoit; Levens, Tom; Nisbet, David; Zobov, M; CERN. Geneva. ATS Department

    2016-01-01

    The purpose of this MD is to measure the octupole current thresholds for stability for a single bunch, and then make an immediate comparison (with the same operational settings) for a train of 72 bunches separated by 25ns. From theory, the expected thresholds should be similar. Any discrepancy between the two cases will be of great interest as it could indicate the presence of additional mechanisms that contribute to the instability threshold, for example electron cloud.

  10. Polygonal instabilities on interfacial vorticities

    CERN Document Server

    Labousse, Matthieu

    2015-01-01

    We report the results of a theoretical investigation of the stability of a toroidal vortex bound by an interface. Two distinct instability mechanisms are identified that rely on, respectively, surface tension and fluid inertia, either of which may prompt the transformation from a circular to a polygonal torus. Our results are discussed in the context of three experiments, a toroidal vortex ring, the hydraulic jump, and the hydraulic bump.

  11. Instability of colliding metastable strings

    Energy Technology Data Exchange (ETDEWEB)

    Hiramatsu, Takashi [Kyoto Univ. (Japan). Yukawa Inst. for Theoretical Physics; Eto, Minoru [Yamagata Univ. (Japan). Dept. of Physics; Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kobayashi, Tatsuo [Kyoto Univ. (Japan). Dept. of Physics; Ookouchi, Yutaka [Kyoto Univ. (Japan). Dept. of Physics; Kyoto Univ. (Japan). The Hakubi Center for Advanced Research

    2013-04-15

    We investigate the collision dynamics of two metastable strings which can be viewed as tube-like domain walls with winding numbers interpolating a false vacuum and a true vacuum. We find that depending on the relative angle and speed of two strings, instability of strings increases and the false vacuum is filled out by rapid expansion of the strings or of a remnant of the collision.

  12. Ballistic Limit of High-Strength Steel and Al7075-T6 Multi-Layered Plates Under 7.62-mm Armour Piercing Projectile Impact

    OpenAIRE

    Rahman, N.A.; S. Abdullah; Zamri,W. F. H.; M. F. Abdullah; M. Z. Omar; Sajuri, Z.

    2016-01-01

    Abstract This paper presents the computational-based ballistic limit of laminated metal panels comprised of high strength steel and aluminium alloy Al7075-T6 plate at different thickness combinations to necessitate the weight reduction of existing armour steel plate. The numerical models of monolithic configuration, double-layered configuration and triple-layered configuration were developed using a commercial explicit finite element code and were impacted by 7.62 mm armour piercing projectil...

  13. Gravitational instabilities in astrophysical fluids

    Science.gov (United States)

    Tohline, Joel E.

    1990-01-01

    Over the past decade, the significant advancements that have been made in the development of computational tools and numerical techniques have allowed astrophysicists to begin to model accurately the nonlinear growth of gravitational instabilities in a variety of physical systems. The fragmentation or rotationally driven fission of dynamically evolving, self-gravitating ``drops and bubbles'' is now routinely modeled in full three-dimensional generality as we attempt to understand the behavior of protostellar clouds, rotating stars, galaxies, and even the primordial soup that defined the birth of the universe. A brief review is presented here of the general insights that have been gained from studies of this type, followed by a somewhat more detailed description of work, currently underway, that is designed to explain the process of binary star formation. A short video animation sequence, developed in conjunction with some of the research being reviewed, illustrates the basic-nature of the fission instability in rotating stars and of an instability that can arise in a massive disk that forms in a protostellar cloud.

  14. Microphysics of cosmic ray driven plasma instabilities

    CERN Document Server

    Bykov, A M; Malkov, M A; Osipov, S M

    2013-01-01

    Energetic nonthermal particles (cosmic rays, CRs) are accelerated in supernova remnants, relativistic jets and other astrophysical objects. The CR energy density is typically comparable with that of the thermal components and magnetic fields. In this review we discuss mechanisms of magnetic field amplification due to instabilities induced by CRs. We derive CR kinetic and magnetohydrodynamic equations that govern cosmic plasma systems comprising the thermal background plasma, comic rays and fluctuating magnetic fields to study CR-driven instabilities. Both resonant and non-resonant instabilities are reviewed, including the Bell short-wavelength instability, and the firehose instability. Special attention is paid to the longwavelength instabilities driven by the CR current and pressure gradient. The helicity production by the CR current-driven instabilities is discussed in connection with the dynamo mechanisms of cosmic magnetic field amplification.

  15. Hydrogeologic framework, groundwater movement, and water budget in the Puyallup River Watershed and vicinity, Pierce and King Counties, Washington

    Science.gov (United States)

    Welch, Wendy B.; Johnson, Kenneth H.; Savoca, Mark E.; Lane, Ron C.; Fasser, Elisabeth T.; Gendaszek, Andrew S.; Marshall, Cameron; Clothier, Burt G.; Knoedler, Eric N.

    2015-01-01

    This report presents information used to characterize the groundwater-flow system in the Puyallup River Watershed and vicinity, and includes descriptions of the geology and hydrogeologic framework; groundwater recharge and discharge; groundwater levels and flow directions; seasonal groundwater level fluctuations; interactions between aquifers and the surface-water system; and a water budget. The study area covers about 1,220 square miles in northern Pierce and southern King Counties, Washington; extends north to the Green River and Auburn Valley and southwest to the Puyallup River and adjacent uplands; and is bounded on the south and east by foothills of the Cascade Range and on the west by Puget Sound. The area is underlain by a northwest-thickening sequence of unconsolidated glacial and interglacial deposits, which overlie sedimentary and volcanic bedrock units that crop out in the foothills along the southern and eastern margin of the study area. Geologic units were grouped into 13 hydrogeologic units consisting of aquifers, confining units, and an underlying bedrock unit. A surficial hydrogeologic unit map was developed and used with well information from 1,012 drillers’ logs to construct 8 hydrogeologic sections, and unit extent and thickness maps.

  16. Dynamic Strength Evaluations for Self-Piercing Rivets and Resistance Spot Welds Joining Similar and Dissimilar Metals

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Khaleel, Mohammad A.

    2007-10-01

    This paper summarizes the dynamic joint strength evaluation procedures and the measured dynamic strength data for thirteen joint populations of self-piercing rivets (SPR) and resistance spot welds (RSW) joining similar and dissimilar metals. A state-of-the-art review of the current practice for conducting dynamic tensile/compressive strength tests in different strain rate regimes is first presented, and the generic issues associated with dynamic strength test are addressed. Then, the joint strength testing procedures and fixture designs used in the current study are described, and the typical load versus displacement curves under different loading configurations are presented. Uniqueness of the current data compared with data in the open literature is discussed. The experimental results for all the joint populations indicate that joint strength increases with increasing loading rate. However, the strength increase from 4.47m/s (10mph) to 8.94m/s (20mph) is not as significant as the strength increase from static to 4.47m/s. It is also found that with increasing loading velocity, displacement to failure decreases for all the joint samples. Therefore, “brittleness” of the joint sample increases with impact velocity. Detailed static and dynamic strength data and the associated energy absorption levels for all the samples in the thirteen joint populations are also included.

  17. An iterative Rankine BEM for wave-making analysis of submerged and surface- piercing bodies in finite water depth

    Institute of Scientific and Technical Information of China (English)

    HE Guanghua

    2013-01-01

    A 3-D iterative Rankine Boundary Element Method (BEM) for seakeeping problem in time domain is developed in the framework of linear potential theory. Waves generated by both submerged and surface-piercing bodies moving at a constant forward speed in otherwise calm water, and the resultant steady wave pattern, wave profile and resistance are computed to validate this newly-developed code. A rectangular computational domain moving with the same forward speed as the body is introduced, in which an artificial damping beach is installed at an outer portion of the free surface except the downstream side for satisfying the radiation condition. The velocity potential on the ship hull and the normal velocity on the free surface are obtained directly by solving the boundary integral equation, with the Rankine source used as the kernel function. An iterative time-marching scheme is employed for updating both kinematic and dynamic free surface boundary conditions to stabilize the calculation. Extensive results including the wave patterns, wave profiles and wave resistances for a submerged spheroid and a Wigley hull with forward speed are presented to validate the efficiency of the proposed 3-D time-domain higher-order approach. Finally, the sensitivity of ship-generated waves to the water depth is investigated. Computed results show satisfactory agreement with the corresponding experimental data and other numerical solutions.

  18. Use of diesel engine and surface-piercing propeller to achieve fuel savings for inshore fishing boats

    Science.gov (United States)

    Zainol, Ismail; Yaakob, Omar

    2016-06-01

    Fishing is a major local industry in Malaysia, particularly in rural areas. However, the rapidly increasing price of fuel is seriously affecting the industry's viability. At present, outboard petrol engines are the preferred choice for use in small-scale fishing boats because they deliver the advantages of high speed and low weight, they are easy to install, and they use minimal space. Petrol outboard engines are known to consume a greater amount of fuel than inboard diesel engines, but installing diesel engines with conventional submerged propellers in existing small-scale fishing boats is not economically viable because major hullform modifications and extra expenditure are required to achieve this. This study describes a proposal to enable reductions in fuel consumption by introducing the combined use of a diesel engine and surface-piercing propeller (SPP). An analysis of fuel consumption reduction is presented, together with an economic feasibility study. Resulting data reveal that the use of the proposed modifications would save 23.31 liters of fuel per trip (40.75 %) compared to outboard motors, equaling annual savings of RM 3962 per year.

  19. Ballistic Impact Response of Ceramic-Faced Aramid Laminated Composites Against 7.62 mm Armour Piercing Projectiles

    Directory of Open Access Journals (Sweden)

    Nityananda Nayak

    2013-07-01

    Full Text Available Ballistic impact response of ceramic- composite armor, consisting of zirconia toughened alumina (ZTA ceramic front and aramid laminated composite as backing, against 7.62 mm armor piercing (AP projectiles has been studied. Two types of backing composite laminates i.e. Twaron-epoxy and Twaron-polypropylene (PP of 10 mm and 15 mm thickness were used with a ceramic face of 4mm thick ZTA. The ceramic- faced and the stand alone composite laminates were subjected to ballistic impact of steel core 7.62 mm AP projectiles with varying impact velocities and their V50 ballistic limit (BL was determined. A sharp rise in BL was observed due to addition of ceramic front layer as compared to stand alone ones. The impact energy was absorbed during penetration primarily by fracture of ceramic, deformation and fracture of projectile and elastic-plastic deformation of flexible backing composite layer. The breaking of ceramic tiles were only limited to impact area and did not spread to whole surface and projectile shattering above BL and blunting on impact below BL was observed. The ceramic- faced composites showed higher BL with Twaron-PP as backing than Twaron-epoxy laminate of same thickness. This combination of ceramic-composite laminates exhibited better multi-hit resistance capability; ideal for light weight armor.Defence Science Journal, 2013, 63(4, pp.369-375, DOI:http://dx.doi.org/10.14429/dsj.63.2616

  20. New insights into an RNAi approach for plant defence against piercing-sucking and stem-borer insect pests.

    Science.gov (United States)

    Li, Haichao; Guan, Ruobing; Guo, Huimin; Miao, Xuexia

    2015-11-01

    Insect double-stranded (ds)RNA expression in transgenic crops can increase plant resistance to biotic stress; however, creating transgenic crops to defend against every insect pest is impractical. Arabidopsis Mob1A is required for organ growth and reproduction. When Arabidopsis roots were soaked in dsMob1A, the root lengths and numbers were significantly suppressed and plants could not bolt or flower. Twenty-four hours after rice roots were immersed in fluorescent-labelled dsEYFP (enhanced yellow fluorescent protein), fluorescence was observed in the rice sheath and stem and in planthoppers feeding on the rice. The expression levels of Ago and Dicer in rice and planthoppers were induced by dsEYFP. When rice roots were soaked in dsActin, their growth was also significantly suppressed. When planthoppers or Asian corn borers fed on rice or maize that had been irrigated with a solution containing the dsRNA of an insect target gene, the insect's mortality rate increased significantly. Our results demonstrate that dsRNAs can be absorbed by crop roots, trigger plant and insect RNAi and enhance piercing-sucking and stem-borer insect mortality rates. We also confirmed that dsRNA was stable under outdoor conditions. These results indicate that the root dsRNA soaking can be used as a bioinsecticide strategy during crop irrigation. © 2015 John Wiley & Sons Ltd.

  1. Modes of storage ring coherent instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.M.

    1986-12-01

    Longitudinal impedance in a beam and various modes of longitudinal coherent instabilities are discussed. The coasting beam coherent instability, microwave instability, and single-bunch longitudinal coherent instabilities are considered. The Vlasov equation is formulated, and a method of solving it is developed. The synchrotron modes are treated, which take the possible bunch shape distortion fully into consideration. A method of treating the synchrotron mode coupling in the case of a small bunch is discussed which takes advantage of the fact that only a few of the synchrotron modes can contribute in such a case. The effect of many bunches on the coherent motion of the beam and the longitudinal symmetric coupled bunch modes are discussed. The transverse impedance is then introduced, and the transverse coasting beam instability is discussed. Various bunched beam instabilities are discussed, including both single bunch instabilities and coupled bunch instabilities. The Vlasov equation for transverse as well as longitudinal motion of particles is introduced as well as a method of solving it within a linear approximation. Head-tail modes and short bunch instabilities and strong coupling instabilities in the long bunch case are covered. (LEW)

  2. Compressor instability with integral methods

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Y.K. Eddie [Nanyang Technological Univ., Singapore (Singapore). School of Mechanical and Aerospace Engineering; Liu, Ningyu [Singapore National Univ. (Singapore). Dept. of Mechanical Engineering

    2007-07-01

    ''Compressor Instability with Integral Methods'' is a book, to bring together the quick integral approaches and advances in the field for the prediction of stall and surge problem in compressor. This book is useful for people involved in the flow analysis, design and testing of rotating machinery. For students, it can be used as a specialized topic of senior undergraduate or graduate study. The book can also be served as a self-study material to those who keen to acquire this knowledge. In brief, this book focuses on the numerical/computational analysis for the effect of distorted inlet flow propagation on the rotating stall and surge in axial compressors. It gains insight into the basic phenomena controlling these flow instabilities, and reveals the influence of inlet parameters on rotating stall and surge. The book starts from the confirmation and application of Kim et al's integral method and then follows by a development to this method through the proposing and applying a critical distortion line. This line is applied successfully on the stall prediction of in-flight compressor due to flaming of refueling leakage near inlet, a typical real and interesting example of compressor stall and surge operation. Further, after a parametric study on the integral method and the distorted flow field of compressor using Taguchi method, a novel integral method is formulated using more appropriate and practical airfoil characteristics, with a less assumptions needed for derivation. Finally, as an extended work, the famous Greitzer's instability flow model, the well-known B-parameter model applied for analyzing the stall and surge characteristics, is studied parametrically using Taguchi method. (orig.)

  3. Bathtub vortex induced by instability

    Science.gov (United States)

    Mizushima, Jiro; Abe, Kazuki; Yokoyama, Naoto

    2014-10-01

    The driving mechanism and the swirl direction of the bathtub vortex are investigated by the linear stability analysis of the no-vortex flow as well as numerical simulations. We find that only systems having plane symmetries with respect to vertical planes deserve research for the swirl direction. The bathtub vortex appearing in a vessel with a rectangular cross section having a drain hole at the center of the bottom is proved to be induced by instability when the flow rate exceeds a threshold. The Coriolis force is capable of determining the swirl direction to be cyclonic.

  4. Spatiotemporal chaos involving wave instability

    Science.gov (United States)

    Berenstein, Igal; Carballido-Landeira, Jorge

    2017-01-01

    In this paper, we investigate pattern formation in a model of a reaction confined in a microemulsion, in a regime where both Turing and wave instability occur. In one-dimensional systems, the pattern corresponds to spatiotemporal intermittency where the behavior of the systems alternates in both time and space between stationary Turing patterns and traveling waves. In two-dimensional systems, the behavior initially may correspond to Turing patterns, which then turn into wave patterns. The resulting pattern also corresponds to a chaotic state, where the system alternates in both space and time between standing wave patterns and traveling waves, and the local dynamics may show vanishing amplitude of the variables.

  5. Nonlinear Instability of Liquid Layers.

    Science.gov (United States)

    Newhouse, Lori Ann

    The nonlinear instability of two superposed viscous liquid layers in planar and axisymmetric configurations is investigated. In the planar configuration, the light layer fluid is bounded below by a wall and above by a heavy semiinfinite fluid. Gravity drives the instability. In the first axisymmetric configuration, the layer is confined between a cylindrical wall and a core of another fluid. In the second, a thread is suspended in an infinite fluid. Surface tension forces drive the instability in the axisymmetric configurations. The nonlinear evolution of the fluid-fluid interface is computed for layers of arbitrary thickness when their dynamics are fully coupled to those of the second fluid. Under the assumption of creeping flow, the flow field is represented by an interfacial distribution of Green's functions. A Fredholm integral equation of the second kind for the strength of the distribution is derived and then solved using an iterative technique. The Green's functions produce flow fields which are periodic in the direction parallel to the wall and have zero velocity on the wall. For small and moderate surface tension, planar layers evolve into a periodic array of viscous plumes which penetrate into the overlying fluid. The morphology of the plumes depends on the surface tension and the ratio of the fluid viscosities. As the viscosity of the layer increases, the plumes change from a well defined drop on top of a narrow stem to a compact column of rising fluid. The capillary instability of cylindrical interfaces and interfaces in which the core thickness varies in the axial direction are investigated. In both the unbounded and wall bounded configurations, the core evolves into a periodic array of elongated fluid drops connected by thin, almost cylindrical fluid links. The characteristics of the drop-link structure depend on the core thickness, the ratio of the core radius to the wall radius, and the ratio of the fluid viscosities. The factors controlling the

  6. Mode-locking via dissipative Faraday instability

    Science.gov (United States)

    Tarasov, Nikita; Perego, Auro M.; Churkin, Dmitry V.; Staliunas, Kestutis; Turitsyn, Sergei K.

    2016-08-01

    Emergence of coherent structures and patterns at the nonlinear stage of modulation instability of a uniform state is an inherent feature of many biological, physical and engineering systems. There are several well-studied classical modulation instabilities, such as Benjamin-Feir, Turing and Faraday instability, which play a critical role in the self-organization of energy and matter in non-equilibrium physical, chemical and biological systems. Here we experimentally demonstrate the dissipative Faraday instability induced by spatially periodic zig-zag modulation of a dissipative parameter of the system--spectrally dependent losses--achieving generation of temporal patterns and high-harmonic mode-locking in a fibre laser. We demonstrate features of this instability that distinguish it from both the Benjamin-Feir and the purely dispersive Faraday instability. Our results open the possibilities for new designs of mode-locked lasers and can be extended to other fields of physics and engineering.

  7. Transverse Instabilities in the Fermilab Recycler

    Energy Technology Data Exchange (ETDEWEB)

    Prost, L.R.; Burov, A.; Shemyakin, A.; Bhat, C.M.; Crisp, J.; Eddy, N.; /Fermilab

    2011-07-01

    Transverse instabilities of the antiproton beam have been observed in the Recycler ring soon after its commissioning. After installation of transverse dampers, the threshold for the instability limit increased significantly but the instability is still found to limit the brightness of the antiprotons extracted from the Recycler for Tevatron shots. In this paper, we describe observations of the instabilities during the extraction process as well as during dedicated studies. The measured instability threshold phase density agrees with the prediction of the rigid beam model within a factor of 2. Also, we conclude that the instability threshold can be significantly lowered for a bunch contained in a narrow and shallow potential well due to effective exclusion of the longitudinal tails from Landau damping.

  8. Optimal excitation of two dimensional Holmboe instabilities

    CERN Document Server

    Constantinou, Navid C

    2010-01-01

    Highly stratified shear layers are rendered unstable even at high stratifications by Holmboe instabilities when the density stratification is concentrated in a small region of the shear layer. These instabilities may cause mixing in highly stratified environments. However these instabilities occur in tongues for a limited range of parameters. We perform Generalized Stability analysis of the two dimensional perturbation dynamics of an inviscid Boussinesq stratified shear layer and show that Holmboe instabilities at high Richardson numbers can be excited by their adjoints at amplitudes that are orders of magnitude larger than by introducing initially the unstable mode itself. We also determine the optimal growth that obtains for parameters for which there is no instability. We find that there is potential for large transient growth regardless of whether the background flow is exponentially stable or not and that the characteristic structure of the Holmboe instability asymptotically emerges for parameter values ...

  9. Mode-locking via dissipative Faraday instability.

    Science.gov (United States)

    Tarasov, Nikita; Perego, Auro M; Churkin, Dmitry V; Staliunas, Kestutis; Turitsyn, Sergei K

    2016-08-09

    Emergence of coherent structures and patterns at the nonlinear stage of modulation instability of a uniform state is an inherent feature of many biological, physical and engineering systems. There are several well-studied classical modulation instabilities, such as Benjamin-Feir, Turing and Faraday instability, which play a critical role in the self-organization of energy and matter in non-equilibrium physical, chemical and biological systems. Here we experimentally demonstrate the dissipative Faraday instability induced by spatially periodic zig-zag modulation of a dissipative parameter of the system-spectrally dependent losses-achieving generation of temporal patterns and high-harmonic mode-locking in a fibre laser. We demonstrate features of this instability that distinguish it from both the Benjamin-Feir and the purely dispersive Faraday instability. Our results open the possibilities for new designs of mode-locked lasers and can be extended to other fields of physics and engineering.

  10. Instabilities and transition in boundary layers

    Indian Academy of Sciences (India)

    N Vinod; Rama Govindarajan

    2005-03-01

    Some recent developments in boundary layer instabilities and transition are reviewed. Background disturbance levels determine the instability mechanism that ultimately leads to turbulence. At low noise levels, the traditional Tollmien–Schlichting route is followed, while at high levels, a `by-pass' route is more likely. Our recent work shows that spot birth is related to the pattern of secondary instability in either route.

  11. Beam Instabilities in the Scale Free Regime

    CERN Document Server

    Folli, Viola; Conti, Claudio; 10.1103/PhysRevLett.108.033901

    2012-01-01

    The instabilities arising in a one-dimensional beam sustained by the diffusive photorefractive nonlinearity in out-of-equilibrium ferroelectrics are theoretically and numerically investigated. In the "scale-free model", in striking contrast with the well-known spatial modulational instability, two different beam instabilities dominate: a defocusing and a fragmenting process. Both are independent of the beam power and are not associated to any specific periodic pattern.

  12. Electron proton instability in the CSNS ring

    Institute of Scientific and Technical Information of China (English)

    WANG Na; QIN Qing; LIU Yu-Dong

    2009-01-01

    The electron proton(e-p)instability has been observed in many proton accelerators.It will induce transverse beam size blow-up,cause beam loss and restrict the machine performance.Much research work has been done on the causes,dynamics and cures of this instability.A simulation code is developed to study the e-p instability in the ring of the China Spallation Neutron Source(CSNS).

  13. Fishbone Instability Excited by Barely Trapped Electrons

    Institute of Scientific and Technical Information of China (English)

    WANG Zhong-Tian; LONG Yong-Xing; DONG Jia-Qi; WANG Long; Fulvio Zonca

    2006-01-01

    Fishbone instability excited by barely trapped suprathermal electrons (BTSEs) in tokamaks is investigated theoretically. The frequency of the mode is found to close to procession frequency of BTSEs. The growth rate of the mode is much smaller than that of the ideal magnetohytrodynamic (MHD) internal kink mode that is in contrast to the case of trapped ion driven fishbone instability. The analyses also show that spatial density gradient reversal is necessary for the instability. The correlation of the results with experiments is discussed.

  14. [Cervical spine instability in the surgical patient].

    Science.gov (United States)

    Barbeito, A; Guerri-Guttenberg, R A

    2014-03-01

    Many congenital and acquired diseases, including trauma, may result in cervical spine instability. Given that airway management is closely related to the movement of the cervical spine, it is important that the anesthesiologist has detailed knowledge of the anatomy, the mechanisms of cervical spine instability, and of the effects that the different airway maneuvers have on the cervical spine. We first review the normal anatomy and biomechanics of the cervical spine in the context of airway management and the concept of cervical spine instability. In the second part, we review the protocols for the management of cervical spine instability in trauma victims and some of the airway management options for these patients.

  15. Two-Fluid Interface Instability Being Studied

    Science.gov (United States)

    Niederhaus, Charles E.

    2003-01-01

    The interface between two fluids of different density can experience instability when gravity acts normal to the surface. The relatively well known Rayleigh-Taylor (RT) instability results when the gravity is constant with a heavy fluid over a light fluid. An impulsive acceleration applied to the fluids results in the Richtmyer-Meshkov (RM) instability. The RM instability occurs regardless of the relative orientation of the heavy and light fluids. In many systems, the passing of a shock wave through the interface provides the impulsive acceleration. Both the RT and RM instabilities result in mixing at the interface. These instabilities arise in a diverse array of circumstances, including supernovas, oceans, supersonic combustion, and inertial confinement fusion (ICF). The area with the greatest current interest in RT and RM instabilities is ICF, which is an attempt to produce fusion energy for nuclear reactors from BB-sized pellets of deuterium and tritium. In the ICF experiments conducted so far, RM and RT instabilities have prevented the generation of net-positive energy. The $4 billion National Ignition Facility at Lawrence Livermore National Laboratory is being constructed to study these instabilities and to attempt to achieve net-positive yield in an ICF experiment.

  16. Aeroelastic instability problems for wind turbines

    DEFF Research Database (Denmark)

    Hansen, Morten Hartvig

    2007-01-01

    This paper deals with the aeroelostic instabilities that have occurred and may still occur for modem commercial wind turbines: stall-induced vibrations for stall-turbines, and classical flutter for pitch-regulated turbines. A review of previous works is combined with derivations of analytical...... stiffness and chordwise position of the center of gravity along the blades are the main parameters for flutter. These instability characteristics are exemplified by aeroelastic stability analyses of different wind turbines. The review of each aeroelastic instability ends with a list of current research...... issues that represent unsolved aeroelostic instability problems for wind turbines. Copyright (c) 2007 John Wiley & Sons, Ltd....

  17. Review of two-phase instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Han Ok; Seo, Han Ok; Kang, Hyung Suk; Cho, Bong Hyun; Lee, Doo Jeong

    1997-06-01

    KAERI is carrying out a development of the design for a new type of integral reactors. The once-through helical steam generator is important design features. The study on designs and operating conditions which prevent flow instability should precede the introduction of one-through steam generator. Experiments are currently scheduled to understand two-phase instability, evaluate the effect of each design parameter on the critical point, and determine proper inlet throttling for the prevention of instability. This report covers general two-phase instability with review of existing studies on this topics. The general classification of two phase flow instability and the characteristics of each type of instability are first described. Special attention is paid to BWR core flow instability and once-through steam generator instability. The reactivity feedback and the effect of system parameters are treated mainly for BWR. With relation to once-through steam generators, the characteristics of convective heating and dryout point oscillation are first investigated and then the existing experimental studies are summarized. Finally chapter summarized the proposed correlations for instability boundary conditions. (author). 231 refs., 5 tabs., 47 figs

  18. Systems and methods for controlling flame instability

    KAUST Repository

    Cha, Min Suk

    2016-07-21

    A system (62) for controlling flame instability comprising: a nozzle (66) coupled to a fuel supply line (70), an insulation housing (74) coupled to the nozzle, a combustor (78) coupled to the nozzle via the insulation housing, where the combustor is grounded (80), a pressure sensor (82) coupled to the combustor and configured to detect pressure in the combustor, and an instability controlling assembly coupled to the pressure sensor and to an alternating current power supply (86), where, the instability controlling assembly can control flame instability of a flame in the system based on pressure detected by the pressure sensor.

  19. Instabilities of flows and transition to turbulence

    CERN Document Server

    Sengupta, Tapan K

    2012-01-01

    Introduction to Instability and TransitionIntroductionWhat Is Instability?Temporal and Spatial InstabilitySome Instability MechanismsComputing Transitional and Turbulent FlowsFluid Dynamical EquationsSome Equilibrium Solutions of the Basic EquationBoundary Layer TheoryControl Volume Analysis of Boundary LayersNumerical Solution of the Thin Shear Layer (TSL) EquationLaminar Mixing LayerPlane Laminar JetIssues of Computing Space-Time Dependent FlowsWave Interaction: Group Velocity and Energy FluxIssues of Space-Time Scale Resolution of FlowsTemporal Scales in Turbulent FlowsComputing Time-Averag

  20. The Chemistry of Beer Instability

    Science.gov (United States)

    Stewart, Graham G.

    2004-07-01

    Compared to most other alcoholic beverages, beer is unique because it is unstable when in the final package. This instability can be divided into biological and nonbiological instability. Nonbiological stability of beer involves a wide range of chemical processes and can be considered in a number of categories: physical, flavor, light, foam, and gushing. It is the balance between flavanoid polyphenols (tannoids) and sensitive proteins that specifically combine with polyphenols to form haze that largely dictates physical stability. The flavor stability of beer primarily depends on the oxygen concentration of packaged beer but is influenced by all stages of the brewing process. Foam stability in a glass of beer reflects the quality of the beverage. The backbone of foam is hydrophobic polypeptides. Novel brewing processes such as high-gravity brewing result in a disproportionate loss of these polypeptides and have a negative effect on the foam stability of the resulting beer. Beer is light sensitive, especially in the 350 500 nm range. Beer exposed to this wavelength range in clear or green glass containers quickly develop nauseous skunky-like off-flavors resulting from the formation of 3-methyl-2-butene-1-thiol. Methods of enhancing all of these types of beer stability are discussed.

  1. Option price and market instability

    Science.gov (United States)

    Baaquie, Belal E.; Yu, Miao

    2017-04-01

    An option pricing formula, for which the price of an option depends on both the value of the underlying security as well as the velocity of the security, has been proposed in Baaquie and Yang (2014). The FX (foreign exchange) options price was empirically studied in Baaquie et al., (2014), and it was found that the model in general provides an excellent fit for all strike prices with a fixed model parameters-unlike the Black-Scholes option price Hull and White (1987) that requires the empirically determined implied volatility surface to fit the option data. The option price proposed in Baaquie and Cao Yang (2014) did not fit the data during the crisis of 2007-2008. We make a hypothesis that the failure of the option price to fit data is an indication of the market's large deviation from its near equilibrium behavior due to the market's instability. Furthermore, our indicator of market's instability is shown to be more accurate than the option's observed volatility. The market prices of the FX option for various currencies are studied in the light of our hypothesis.

  2. Cosmic Rays and Radiative Instabilities

    CERN Document Server

    Hartquist, T W; Falle, S A E G; Pittard, J M; Van Loo, S

    2011-01-01

    In the absence of magnetic fields and cosmic rays, radiative cooling laws with a range of dependences on temperature affect the stability of interstellar gas. For about four and a half decades, astrophysicists have recognised the importance of the thermal instablity for the formation of clouds in the interstellar medium. Even in the past several years, many papers have concerned the role of the thermal instability in the production of molecular clouds. About three and a half decades ago, astrophysicists investigating radiative shocks noticed that for many cooling laws such shocks are unstable. Attempts to address the effects of cosmic rays on the stablity of radiative media that are initially uniform or that have just passed through shocks have been made. The simplest approach to such studies involves the assumption that the cosmic rays behave as a fluid. Work based on such an approach is described. Cosmic rays have no effect on the stability of initially uniform, static media with respect to isobaric perturb...

  3. Visco-Resistive Plasmoid Instability

    CERN Document Server

    Comisso, Luca

    2016-01-01

    The plasmoid instability in visco-resistive current sheets is analyzed in both the linear and nonlinear regimes. The linear growth rate and the wavenumber are found to scale as $S^{1/4} {\\left( {1 + {P_m}} \\right)}^{-5/8}$ and $S^{3/8} {\\left( {1 + {P_m}} \\right)}^{-3/16}$ with respect to the Lundquist number $S$ and the magnetic Prandtl number $P_m$. Furthermore, the linear layer width is shown to scale as $S^{-1/8} {(1+P_m)}^{1/16}$. The growth of the plasmoids slows down from an exponential growth to an algebraic growth when they enter into the nonlinear regime. In particular, the time-scale of the nonlinear growth of the plasmoids is found to be $\\tau_{NL} \\sim S^{-3/16} {(1 + P_m)^{19/32}}{\\tau _{A,L}}$. The nonlinear growth of the plasmoids is radically different from the linear one and it is shown to be essential to understand the global current sheet disruption. It is also discussed how the plasmoid instability enables fast magnetic reconnection in visco-resistive plasmas. In particular, it is shown t...

  4. Combustion instability modeling and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Santoro, R.J.; Yang, V.; Santavicca, D.A. [Pennsylvania State Univ., University Park, PA (United States)] [and others

    1995-10-01

    It is well known that the two key elements for achieving low emissions and high performance in a gas turbine combustor are to simultaneously establish (1) a lean combustion zone for maintaining low NO{sub x} emissions and (2) rapid mixing for good ignition and flame stability. However, these requirements, when coupled with the short combustor lengths used to limit the residence time for NO formation typical of advanced gas turbine combustors, can lead to problems regarding unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions, as well as the occurrence of combustion instabilities. Clearly, the key to successful gas turbine development is based on understanding the effects of geometry and operating conditions on combustion instability, emissions (including UHC, CO and NO{sub x}) and performance. The concurrent development of suitable analytical and numerical models that are validated with experimental studies is important for achieving this objective. A major benefit of the present research will be to provide for the first time an experimentally verified model of emissions and performance of gas turbine combustors.

  5. Grapevine rootstock effects on scion sap phenolic levels, resistance to Xylella fastidiosa infection, and progression of Pierce's disease.

    Science.gov (United States)

    Wallis, Christopher M; Wallingford, Anna K; Chen, Jianchi

    2013-01-01

    The xylem-limited bacterium Xylella fastidiosa (Xf) causes Pierce's disease (PD), an important disease of grapevine, Vitis vinifera L. Grapevine rootstocks were developed to provide increased resistance to root disease, but rootstock effects on cane and vine diseases remain unclear. Grapevines that consisted of Cabernet Sauvignon or Chardonnay grafted to 13 different rootstocks were inoculated with Xf and evaluated for PD severity and Xf titer after 6 months. A subset of six rootstock/scion combinations had xylem sap phenolic levels assessed in non-infected and Xf-infected grapevines. Vigor also was analyzed by measuring root lengths and masses. Cabernet Sauvignon grafted to 101-14MG, 1103P, 420A, or Schwarzmann had reduced PD severity compared to Cabernet Sauvignon grafted to 110R, 5BB, or SO4. Chardonnay grafted to Salt Creek or Freedom had reduced PD severity compared to Chardonnay grafted to RS3 or Schwarzmann. Chardonnay grafted to RS3 had greater Xf titer than Chardonnay grafted to 101-14MG, Freedom, or Salt Creek. No other differences in Xf titer among rootstocks were observed. Of the six scion/rootstock combinations which had xylem sap phenolics analyzed, Chardonnay/RS3 had the highest levels of most phenolics whereas Cabernet Sauvignon/101-14MG had the lowest phenolic levels. However, Chardonnay/101-14MG, which had mild PD symptoms, had greater sap levels of caftaric acid than other scion/rootstock combinations. Sap levels of caftaric acid, methyl salicylate, a procyanidin trimer, and quinic acid were greater in Xf-infected vs. non-infected grapevines. Chardonnay on 101-14MG or Salt Creek had greater root mass than Chardonnay on RS3. Cabernet Sauvignon on 101-14MG had greater root mass than Cabernet Sauvignon on 110R. These results identified rootstocks with the capacity for reducing PD symptom progression. Rootstocks also were shown to affect Xf titer, xylem sap phenolic levels, and plant vigor.

  6. Capillarys 2 Flex Piercing: Analytical performance assessment according to CLSI protocols for HbA1c quantification.

    Science.gov (United States)

    Doggui, Radhouene; Abdelhafidh Sahli, Chaïma; Aissa, Wassef Lotfi; Hammami, Maroua; Ben Sedrine, Maha; Mahjoub, Rahma; Zouaoui, Khemais; Daboubi, Rim; Siala, Hajer; Messaoud, Taieb; Bibi, Amina

    2017-09-01

    HbA1c is used for monitoring diabetic balance. In this paper we report an assessment of the analytical performances of Capillarys 2 Flex Piercing (C2FP) for HbA1c measurement using CE (Capillary Electrophoresis). CLSI (Clinical and Laboratory Standard Institute) protocols are used for the evaluation of apparatus performances: precision, linearity, method comparison, trueness and common interferences. HbA1c CVs average in intra-assay was 1.6% between run imprecision CV ranged from 0.1 to 1.8%. The linearity was demonstrated between 4.7 and 15.0%. The comparison study revealed that Bland Altman plot mean difference was equal to -0.03 (CI 95% (-0.05 to -0.0003)) and Passing-Bablok regression intercept was -0.05, CI95%(-0.13 -  -0.05); slope: 1.00, CI95%[1.00-1.01]. A strong correlation (r > 0.99) was proved. No significant effects of hemoglobin variants were seen with CE on HbA1c measurement. No problem related to sample-to-sample carry over was noted. No interferences of LA1c and cHb were observed. CE allowed quantification of HbA1c even at low level of total hemoglobin (40 g/L) in contrast to HPLC. Furthermore, this analyzer offered the opportunity of quantifying the HbA2 simultaneously with HbA1c . This evaluation showed that C2FP is a convenient system for the control of diabetes and the detection of hemoglobinopathies. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Relationship Between Piercing-Sucking Insect Control and Internal Lint and Seed Rot in Southeastern Cotton (Gossypium hirsutum L.).

    Science.gov (United States)

    Medrano, Enrique G; Bell, Alois A; Greene, Jeremy K; Roberts, Phillip M; Bacheler, Jack S; Marois, James J; Wright, David L; Esquivel, Jesus F; Nichols, Robert L; Duke, Sara

    2015-08-01

    In 1999, crop consultants scouting for stink bugs (Hemiptera spp.) in South Carolina discovered a formerly unobserved seed rot of cotton that caused yield losses ranging from 10 to 15% in certain fields. The disease has subsequently been reported in fields throughout the southeastern Cotton Belt. Externally, diseased bolls appeared undamaged; internally, green fruit contain pink to dark brown, damp, deformed lint, and necrotic seeds. In greenhouse experiments, we demonstrated transmission of the opportunistic bacterium Pantoea agglomerans by the southern green stink bug, Nezara viridula (L.). Here, green bolls were sampled from stink bug management plots (insecticide protected or nontreated) from four South Atlantic coast states (North Carolina, South Carolina, Georgia, and Florida) to determine disease incidence in the field and its association with piercing-sucking insects feeding. A logistic regression analysis of the boll damage data revealed that disease was 24 times more likely to occur (P = 0.004) in bolls collected from plots in Florida, where evidence of pest pressure was highest, than in bolls harvested in NC with the lowest detected insect pressure. Fruit from plots treated with insecticide, a treatment which reduced transmission agent numbers, were 4 times less likely to be diseased than bolls from unprotected sites (P = 0.002). Overall, punctured bolls were 125 times more likely to also have disease symptoms than nonpunctured bolls, irrespective of whether or not plots were protected with insecticides (P = 0.0001). Much of the damage to cotton bolls that is commonly attributed to stink bug feeding is likely the resulting effect of vectored pathogens. Published by Oxford University Press on behalf of Entomological Society of America 2015. This work is written by US Government employees and is in the public domain in the US.

  8. Interfacial instabilities in vibrated fluids

    Science.gov (United States)

    Porter, Jeff; Laverón-Simavilla, Ana; Tinao Perez-Miravete, Ignacio; Fernandez Fraile, Jose Javier

    2016-07-01

    Vibrations induce a range of different interfacial phenomena in fluid systems depending on the frequency and orientation of the forcing. With gravity, (large) interfaces are approximately flat and there is a qualitative difference between vertical and horizontal forcing. Sufficient vertical forcing produces subharmonic standing waves (Faraday waves) that extend over the whole interface. Horizontal forcing can excite both localized and extended interfacial phenomena. The vibrating solid boundaries act as wavemakers to excite traveling waves (or sloshing modes at low frequencies) but they also drive evanescent bulk modes whose oscillatory pressure gradient can parametrically excite subharmonic surface waves like cross-waves. Depending on the magnitude of the damping and the aspect ratio of the container, these locally generated surfaces waves may interact in the interior resulting in temporal modulation and other complex dynamics. In the case where the interface separates two fluids of different density in, for example, a rectangular container, the mass transfer due to vertical motion near the endwalls requires a counterflow in the interior region that can lead to a Kelvin-Helmholtz type instability and a ``frozen wave" pattern. In microgravity, the dominance of surface forces favors non-flat equilibrium configurations and the distinction between vertical and horizontal applied forcing can be lost. Hysteresis and multiplicity of solutions are more common, especially in non-wetting systems where disconnected (partial) volumes of fluid can be established. Furthermore, the vibrational field contributes a dynamic pressure term that competes with surface tension to select the (time averaged) shape of the surface. These new (quasi-static) surface configurations, known as vibroequilibria, can differ substantially from the hydrostatic state. There is a tendency for the interface to orient perpendicular to the vibrational axis and, in some cases, a bulge or cavity is induced

  9. On the descriptions of beam instabilities

    CERN Document Server

    Maillard, Antoine

    2016-01-01

    We investigate two interesting features of beam instabilities in accelerators : First, we provide the equivalence between two models to describe transverse instabilities, the circulant matrix model (based on a longitudinal phase space discretization) and the Vlasov formalism. Secondly, we show how to derive dispersion integrals for transverse detuning effects in the Vlasov formalism, thus allowing for Landau damping mechanism.

  10. Parametric Instability: An Elementary Demonstration and Discussion.

    Science.gov (United States)

    Case, William

    1980-01-01

    Discusses parametric oscillators and parametric instability. A simple, easy-to-construct system which exhibits parametric instability is presented. The two lowest-order resonances are described and analyzed in detail. The analysis stresses the physical and intuitive aspects of the problem. (Author/HM)

  11. Energetic particle instabilities in fusion plasmas

    NARCIS (Netherlands)

    Sharapov, S. E.; Alper, B.; Berk, H. L.; Borba, D. N.; Breizman, B. N.; Challis, C. D.; Classen, I.G.J.; Edlund, E. M.; Eriksson, J.; Fasoli, A.; Fredrickson, E. D.; Fu, G. Y.; Garcia-Munoz, M.; Gassner, T.; Ghantous, K.; Goloborodko, V.; Gorelenkov, N. N.; Gryaznevich, M. P.; Hacquin, S.; Heidbrink, W. W.; Hellesen, C.; Kiptily, V. G.; Kramer, G. J.; Lauber, P.; Lilley, M. K.; Lisak, M.; Nabais, F.; Nazikian, R.; Nyqvist, R.; Osakabe, M.; C. Perez von Thun,; Pinches, S. D.; Podesta, M.; Porkolab, M.; Shinohara, K.; Schoepf, K.; Todo, Y.; Toi, K.; VanZeeland, M. A.; Voitsekhovich, I.; White, R. B.; Yavorskij, V.; ITPA EP TG Contributors,; JET-EFDA Contributors,

    2013-01-01

    Remarkable progress has been made in diagnosing energetic particle instabilities on present-day machines and in establishing a theoretical framework for describing them. This overview describes the much improved diagnostics of Alfvén instabilities and modelling tools developed world-wide, and discus

  12. Cultural diversity, economic development and societal instability

    Science.gov (United States)

    Nettle, D.; Grace, J.B.; Choisy, M.; Cornell, H.V.; Guegan, J.-F.; Hochberg, M.E.

    2007-01-01

    Background. Social scientists have suggested that cultural diversity in a nation leads to societal instability. However, societal instability may be affected not only by within-nation on ?? diversity, but also diversity between a nation and its neighbours or ?? diversity. It is also necessary to distinguish different domains of diversity, namely linguistic, ethnic and religious, and to distinguish between the direct effects of diversity on societal instability, and effects that are mediated by economic conditions. Methodology/Principal Findings. We assembled a large cross-national dataset with information on ?? and ?? cultural diversity, economic conditions, and indices of societal instability. Structural equation modeling was used to evaluate the direct and indirect effects of cultural diversity on economics and societal stability. Results show that different type and domains of diversity have interacting effects. As previously documented, linguistic ?? diversity has a negative effect on economic performance, and we show that it is largely through this economic mechanism that it affects societal instability. For ?? diversity, the higher the linguistic diversity among nations in a region, the less stable the nation. But, religious ?? diversity has the opposite effect, reducing instability, particularly in the presence of high linguistic diversity. Conclusions. Within-nation linguistic diversity is associated with reduced economic performance, which, in turn, increases societal instability. Nations which differ linguistically from their neighbors are also less stable. However, religious diversity between, neighboring nations has the opposite effect, decreasing societal instability.

  13. Magnetic resonance imaging in glenohumeral instability

    Science.gov (United States)

    Jana, Manisha; Gamanagatti, Shivanand

    2011-01-01

    The glenohumeral joint is the most commonly dislocated joint of the body and anterior instability is the most common type of shoulder instability. Magnetic resonance (MR) imaging, and more recently, MR arthrography, have become the essential investigation modalities of glenohumeral instability, especially for pre-procedure evaluation before arthroscopic surgery. Injuries associated with glenohumeral instability are variable, and can involve the bones, the labor-ligamentous components, or the rotator cuff. Anterior instability is associated with injuries of the anterior labrum and the anterior band of the inferior glenohumeral ligament, in the form of Bankart lesion and its variants; whereas posterior instability is associated with reverse Bankart and reverse Hill-Sachs lesion. Multidirectional instability often has no labral pathology on imaging but shows specific osseous changes such as increased chondrolabral retroversion. This article reviews the relevant anatomy in brief, the MR imaging technique and the arthrographic technique, and describes the MR findings in each type of instability as well as common imaging pitfalls. PMID:22007285

  14. Hydrodynamic Instabilities in Rotating Fluids

    Institute of Scientific and Technical Information of China (English)

    KarlBuehler

    2000-01-01

    Rotating flow systems are often used to study stability phenomena and structure developments.The closed spherical gap prblem is generalized into an open flow system by superimposing a mass flux in meridional direction.The basic solutions at low Reynolds numbers are described by analytical methods.The nonlinear supercritical solutions are simulated numerically and realized in experiments.Novel steady and time-dependent modes of flows are obtained.The extensive results concern the stability behaviour.non-uniqueness of supercritical solutions,symmetry behaviour and transitions between steady and time-dependent solutions.The experimental investigations concern the visualization of the various instabilities and the quatitative description of the flow structures including the laminar-turbulent transition.A Comparison between theoretical and experimental results shows good agreement within the limit of rotational symmetric solutions from the theory.

  15. Transient spirals as superposed instabilities

    CERN Document Server

    Sellwood, J A

    2014-01-01

    We present evidence that recurrent spiral activity, long manifested in simulations of disk galaxies, results from the super-position of a few transient spiral modes. Each mode lasts between five and ten rotations at its corotation radius where its amplitude is greatest. The scattering of stars as each wave decays takes place over narrow ranges of angular momentum, causing abrupt changes to the impedance of the disk to subsequent traveling waves. Partial reflections of waves at these newly created features, allows new standing-wave instabilities to appear that saturate and decay in their turn, scattering particles at new locations, creating a recurring cycle. The spiral activity causes the general level of random motion to rise, gradually decreasing the ability of the disk to support further activity unless the disk contains a dissipative gas component from which stars form on near-circular orbits. We also show that this interpretation is consistent with the behavior reported in other recent simulations with l...

  16. Gravitational Instability of a Kink

    CERN Document Server

    Barreto, W; Lehner, L; Winicour, J

    1996-01-01

    We study the equilibria of a self-gravitating scalar field in the region outside a reflecting barrier. By introducing a potential difference between the barrier and infinity, we create a kink which cannot decay to a zero energy state. In the realm of small amplitude, the kink decays to a known static solution of the Einstein-Klein-Gordon equation. However, for larger kinks the static equilibria are degenerate, forming a system with two energy levels. The upper level is unstable and, under small perturbations, decays to the lower energy stable equilibrium. Under large perturbations, the unstable upper level undergoes collapse to a black hole. The equilibrium of the system provides a remarkably simple and beautiful illustration of a turning point instability.

  17. Mapping Instabilities in Polymer Friction

    Science.gov (United States)

    Rand, Charles; Crosby, Alfred

    2005-03-01

    Schallamach waves are instabilities that occur as interfaces between a soft elastomer and rigid surface slide past each other.(1) The presence of Schallamach waves can lead to drastic changes in frictional properties. Although the occurrence of Schallamach waves has been studied for the past several decades, a general map relating fundamental material properties, geometry, and operating conditions (i.e. speed and temperature) has not been established. Using a combinatorial approach, we illustrate the role of modulus, testing velocity and surface energetics of crosslinked poly(dimethyl siloxane) on the generation Schallamach waves. This knowledge will be used with polymer patterning processes to fabricate responsive coatings for applications such as anti-fouling coatings. (1)Schallamach, A.;Wear 1971,17, 301-312.

  18. Secondary instability in boundary-layer flows

    Science.gov (United States)

    Nayfeh, A. H.; Bozatli, A. N.

    1979-01-01

    The stability of a secondary Tollmien-Schlichting wave, whose wavenumber and frequency are nearly one half those of a fundamental Tollmien-Schlichting instability wave is analyzed using the method of multiple scales. Under these conditions, the fundamental wave acts as a parametric exciter for the secondary wave. The results show that the amplitude of the fundamental wave must exceed a critical value to trigger this parametric instability. This value is proportional to a detuning parameter which is the real part of k - 2K, where k and K are the wavenumbers of the fundamental and its subharmonic, respectively. For Blasius flow, the critical amplitude is approximately 29% of the mean flow, and hence many other secondary instabilities take place before this parametric instability becomes significant. For other flows where the detuning parameter is small, such as free-shear layer flows, the critical amplitude can be small, thus the parametric instability might play a greater role.

  19. Taylor instability in rhyolite lava flows

    Science.gov (United States)

    Baum, B. A.; Krantz, W. B.; Fink, J. H.; Dickinson, R. E.

    1989-01-01

    A refined Taylor instability model is developed to describe the surface morphology of rhyolite lava flows. The effect of the downslope flow of the lava on the structures resulting from the Taylor instability mechanism is considered. Squire's (1933) transformation is developed for this flow in order to extend the results to three-dimensional modes. This permits assessing why ridges thought to arise from the Taylor instability mechanism are preferentially oriented transverse to the direction of lava flow. Measured diapir and ridge spacings for the Little and Big Glass Mountain rhyolite flows in northern California are used in conjunction with the model in order to explore the implications of the Taylor instability for flow emplacement. The model suggests additional lava flow features that can be measured in order to test whether the Taylor instability mechanism has influenced the flows surface morphology.

  20. Whipping Instabilities in Electrified Liquid Jets

    CERN Document Server

    Marin, Alvaro G; Loscertales, Ignacio G; Barrero, Antonio

    2008-01-01

    A liquid jet may develop different types of instabilities, like the so-called Rayleigh-Plateau instability, which breaks the jet into droplets. However, another type of instabilities may appear when we electrify a liquid jet and induce some charge at his surface. Among them, the most common is the so-called Whipping Instability, which is characterized by violent and fast lashes of the jet. In the submitted fluid dynamic video(see http://hdl.handle.net/1813/11422), we will show an unstable charged glycerine jet in a dielectric liquid bath, which permits an enhanced visualization of the instability. For this reason, it is probably the first time that these phenomena are visualized with enough clarity to analyze features as the effect of the feeding liquid flow rate through the jet or as the surprising spontaneous stabilization at some critical distance to the ground electrode.

  1. 3-D nonlinear evolution of MHD instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Bateman, G.; Hicks, H. R.; Wooten, J. W.

    1977-03-01

    The nonlinear evolution of ideal MHD internal instabilities is investigated in straight cylindrical geometry by means of a 3-D initial-value computer code. These instabilities are characterized by pairs of velocity vortex cells rolling off each other and helically twisted down the plasma column. The cells persist until the poloidal velocity saturates at a few tenths of the Alfven velocity. The nonlinear phase is characterized by convection around these essentially fixed vortex cells. For example, the initially centrally peaked temperature profile is convected out and around to form an annulus of high temperature surrounding a small region of lower temperature. Weak, centrally localized instabilities do not alter the edge of the plasma. Strong, large-scale instabilities, resulting from a stronger longitudinal equilibrium current, drive the plasma against the wall. After three examples of instability are analyzed in detail, the numerical methods and their verification are discussed.

  2. Tensile Instability in a Thick Elastic Body

    Science.gov (United States)

    Overvelde, Johannes T. B.; Dykstra, David M. J.; de Rooij, Rijk; Weaver, James; Bertoldi, Katia

    2016-08-01

    A range of instabilities can occur in soft bodies that undergo large deformation. While most of them arise under compressive forces, it has previously been shown analytically that a tensile instability can occur in an elastic block subjected to equitriaxial tension. Guided by this result, we conducted centimeter-scale experiments on thick elastomeric samples under generalized plane strain conditions and observed for the first time this elastic tensile instability. We found that equibiaxial stretching leads to the formation of a wavy pattern, as regions of the sample alternatively flatten and extend in the out-of-plane direction. Our work uncovers a new type of instability that can be triggered in elastic bodies, enlarging the design space for smart structures that harness instabilities to enhance their functionality.

  3. Lidar-revised geologic map of the Olalla 7.5' quadrangle, King, Kitsap, and Pierce Counties, Washington

    Science.gov (United States)

    Tabor, Rowland W.; Haugerud, Ralph A.; Booth, Derek B.; Troost, Kathy Goetz

    2013-01-01

    The Olalla 7.5' quadrangle, which lies almost in the center of the Puget Lowland, displays the broad range of geologic environments typical of the region. The upland plain is fluted by the passage of the great continental ice sheet that last covered the area about 17,000 (14,000 radiocarbon) years ago. The plain is cut by channel deposits, both late glacial and postglacial in age, and it is cleaved even more deeply by one of the major arms of Puget Sound, Colvos Passage, which here separates the west coast of Vashon Island from the Kitsap Peninsula. Beneath the deposits of the last ice sheet is a complex sequence of older Quaternary-age sediments that extends about 400 m below the modern ground surface. These older sediments are best exposed along the shorelines and beach cliffs of Puget Sound, where wave action and landslides maintain relatively fresh exposures. The older sediments typically are compact, having been loaded by ice during one or more episodes of glaciation subsequent to their deposition. Locally these sediments are also cemented by iron and manganese oxides and hydroxides, a consequence of many tens or hundreds of thousands of years of weathering and groundwater movement. Our map is an interpretation of a 6-ft resolution lidar-derived digital elevation model combined with the geology depicted on the "Geologic map of the Olalla 7.5' quadrangle, King, Kitsap, and Pierce Counties, Washington," by Booth and Troost (2005), which was described, interpreted, and located on the 1953 1:24,000-scale topographic map of the Olalla 7.5-minute quadrangle. The original topographic base map, derived from 1951 aerial photographs, has 20-ft contours, nominal horizontal resolution of circa 40 ft (12 m), and nominal mean vertical accuracy of circa 13 ft (4 m). This new DEM has a horizontal resolution of 6 ft (2 m) and mean vertical accuracy circa 1 ft (0.3 m). The greater resolution and accuracy of the lidar DEM facilitated a much-improved interpretation of many

  4. Lidar-revised geologic map of the Olalla 7.5' quadrangle, King, Kitsap, and Pierce Counties, Washington

    Science.gov (United States)

    Tabor, Rowland W.; Haugerud, Ralph A.; Booth, Derek B.; Troost, Kathy Goetz

    2013-01-01

    The Olalla 7.5' quadrangle, which lies almost in the center of the Puget Lowland, displays the broad range of geologic environments typical of the region. The upland plain is fluted by the passage of the great continental ice sheet that last covered the area about 17,000 (14,000 radiocarbon) years ago. The plain is cut by channel deposits, both late glacial and postglacial in age, and it is cleaved even more deeply by one of the major arms of Puget Sound, Colvos Passage, which here separates the west coast of Vashon Island from the Kitsap Peninsula. Beneath the deposits of the last ice sheet is a complex sequence of older Quaternary-age sediments that extends about 400 m below the modern ground surface. These older sediments are best exposed along the shorelines and beach cliffs of Puget Sound, where wave action and landslides maintain relatively fresh exposures. The older sediments typically are compact, having been loaded by ice during one or more episodes of glaciation subsequent to their deposition. Locally these sediments are also cemented by iron and manganese oxides and hydroxides, a consequence of many tens or hundreds of thousands of years of weathering and groundwater movement. Our map is an interpretation of a 6-ft resolution lidar-derived digital elevation model combined with the geology depicted on the "Geologic map of the Olalla 7.5' quadrangle, King, Kitsap, and Pierce Counties, Washington," by Booth and Troost (2005), which was described, interpreted, and located on the 1953 1:24,000-scale topographic map of the Olalla 7.5-minute quadrangle. The original topographic base map, derived from 1951 aerial photographs, has 20-ft contours, nominal horizontal resolution of circa 40 ft (12 m), and nominal mean vertical accuracy of circa 13 ft (4 m). This new DEM has a horizontal resolution of 6 ft (2 m) and mean vertical accuracy circa 1 ft (0.3 m). The greater resolution and accuracy of the lidar DEM facilitated a much-improved interpretation of many

  5. Capillary Instability in Nanoimprinted Polymer Films

    Energy Technology Data Exchange (ETDEWEB)

    Alvine, Kyle J.; Ding, Yifu; Douglas, Jack F.; Ro, Hyun W.; Okerberg, Brian C.; Karim, Alamgir; Soles, Christopher L.

    2009-07-01

    Capillary forces play an active role in defining the equilibrium structure of nanoscale structures. This effect can be especially pronounced in soft materials such as polymers near or above their glass transition temperature Tg where material flow is possible. In these situations, the effect of surface tension can produce varied and complex capillary instabilities, even in relatively simple geometries such as parallel line-space grating patterns. Here we investigate a novel capillary instability that arises in polystyrene line-space gratings with a residual layer connecting these structures (created by nanoimprint lithography) upon thermal annealing of these patterns. This novel instability is characterized by the development of lateral undulations of the lines that culminates in the local coalescence of adjacent imprinted lines. An exact analytic model of this undulatory instability is not possible, but we introduce a simple physical model for this lateral instability based on the driving force to reduce the surface energy, as in the well-known Rayleigh-Plateau instability which is likewise surface energy driven. Good agreement is obtained between this simplified model and our observations. Our insights into the nature of this instability have implications for controlling the thermal stability of nanoscale patterns made by nanoimprint lithography or other lithography techniques.

  6. The Growth Effects of Institutional Instability

    DEFF Research Database (Denmark)

    Berggren, Niclas; Bergh, Andreas; Bjørnskov, Christian

    . While institutional instability is negatively related to growth in the baseline case, there are indications that the effect can be positive in rich countries, suggesting that institutional reform is not necessarily costly even during a transition period. Sensitivity analysis, e.g., decomposing...... the growth effects of institutional quality and instability, using the political risk index from the ICRG in a cross-country study of 132 countries, measuring instability as the coefficient of variation. Using the aggregate index, we find evidence that institutional quality is positively linked to growth...

  7. The short circuit instability in protoplanetary disks

    DEFF Research Database (Denmark)

    Hubbard, A.; McNally, C.P.; Mac Low, M.M.

    2013-01-01

    We introduce a magneto-hydrodynamic instability which occurs, among other locations, in the inner, hot regions of protoplanetary disks, and which alters the way in which resistive dissipation of magnetic energy into heat proceeds. This instability can be likened to both an electrical short circuit...... and lightning, as it concentrates the dissipation of magnetic energy by means of the enhanced release of free electrons. This instability can generate very high temperatures, making it an excellent candidate for thermally processing protoplanetary disk solids, from annealing silicates to melting chondrules...

  8. Quantum effects in beam-plasma instabilities

    CERN Document Server

    Bret, A

    2015-01-01

    Among the numerous works on quantum effects that have been published in recent years, streaming instabilities in plasma have also been revisited. Both the fluid quantum and the kinetic Wigner-Maxwell models have been used to explore quantum effects on the Weibel, Filamentation and Two-Stream instabilities. While quantum effects usually tend to reduce the instabilities, they can also spur new unstable branches. A number of theoretical results will be reviewed together with the implications to one physical setting, namely the electron driven fast ignition scenario.

  9. More on core instabilities of magnetic monopoles

    CERN Document Server

    Striet, J

    2003-01-01

    In this paper we present new results on the core instability of the 't Hooft Polyakov monopoles we reported on before. This instability, where the spherical core decays in a toroidal one, typically occurs in models in which charge conjugation is gauged. In this paper we also discuss a third conceivable configuration denoted as ``split core'', which brings us to some details of the numerical methods we employed. We argue that a core instability of 't Hooft Polyakov type monopoles is quite a generic feature of models with charged Higgs particles.

  10. TERRAIN, Pierce County, WA

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — Terrain data, as defined in FEMA Guidelines and Specifications, Appendix N: Data Capture Standards, describes the digital topographic data that was used to create...

  11. BASEMAP, PIERCE COUNTY, WISCONSIN

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — FEMA Framework Basemap datasets comprise six of the seven FGDC themes of geospatial data that are used by most GIS applications (Note: the seventh framework theme,...

  12. TERRAIN, PIERCE, COUNTY, USA

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — Terrain data, as defined in FEMA Guidelines and Specifications, Appendix N: Data Capture Standards, describes the digital topographic data that was used to create...

  13. Conflict at Pierce College

    Science.gov (United States)

    Bergerson, Amy A.

    2004-01-01

    This case was written for use in courses in higher education leadership. It is particularly useful for examining the environment in which decisions are made in higher education institutions. In the case, a young administrator is confronted with an ethical dilemma. She initially receives the support of her superiors in handling the situation, but…

  14. Caring for Pierced Ears

    Science.gov (United States)

    ... Boards study tools Online Learning Center Meetings and events Make a difference Career planning Media Relations Toolkit AAD apps Academy meeting Chronic urticaria—for members Chronic urticaria—for public Dermatology World Dialogues in Dermatology JAAD Mohs AUC ...

  15. A new method for piercing the tentorium cerebelli for implanting fragile electrodes into the brain stem in the rhesus monkey (Macaca mulatta).

    Science.gov (United States)

    Wu, Jing; Wang, Wenchao; Rizak, Joshua Dominic; Wang, Zhengbo; Wang, Jianhong; Feng, Xiaoli; Dong, Jinrun; Li, Lin; Liu, Li; Xu, Liqi; Yang, Shangchuan; Hu, Xintian

    2014-03-01

    Recent developments in neuron recording techniques include the invention of some fragile electrodes. The fragility of these electrodes impedes their successful use in deep brain recordings because it is difficult to penetrate the electrodes through the dura mater, especially the tentorium cerebelli (TC) enclosing the cerebellum and brain stem. This paper reports a new method to pierce the TC for inserting fragile electrodes into the inferior colliculus of rhesus monkeys. Briefly, a unique tool kit, consisting of needles with sharp tips, a guide tube and an "impactor," was used in a multistep protocol to pierce the TC. The impactor provided a brief force that quickly thrusts the needles through the meninges without causing significant damage to the brain tissue under the TC. Using this novel approach, tetrodes were successfully implanted into the inferior colliculus of a rhesus monkey and neuronal discharge signals were recorded. This method, which is simple, convenient and economical, allows neurophysiologists to study the electrophysiological characteristics of deep brain structures under the TC with advanced, albeit fragile, electrodes.

  16. 冰箱门内壳楔形冲孔模设计%Design of the Wedge-Shaped Piercing Die for the Inner Shell of the Refrigerator Door

    Institute of Scientific and Technical Information of China (English)

    秦建保

    2001-01-01

    分析了冰箱门内壳的冲孔工艺性,介绍了楔形冲孔模的结构及工作过程,还介绍了设计与工作中的注意事项。%The hole-piercing processing property of an inner shell of the refrigerator door was analyzed. The structure and the working process of the wedge-shaped piercing die were introduced.And the attention points in the design and manufacture of the die were stated.

  17. Taylor Instability of Incompressible Liquids

    Science.gov (United States)

    Fermi, E.; von Neumann, J.

    1955-11-01

    A discussion is presented in simplified form of the problem of the growth of an initial ripple on the surface of an incompressible liquid in the presence of an acceleration, g, directed from the outside into the liquid. The model is that of a heavy liquid occupying at t = 0 the half space above the plane z = 0, and a rectangular wave profile is assumed. The theory is found to represent correctly one feature of experimental results, namely the fact that the half wave of the heavy liquid into the vacuum becomes rapidly narrower while the half wave pushing into the heavy liquid becomes more and more blunt. The theory fails to account for the experimental results according to which the front of the wave pushing into the heavy liquid moves with constant velocity. The case of instability at the boundary of 2 fluids of different densities is also explored. Similar results are obtained except that the acceleration of the heavy liquid into the light liquid is reduced.

  18. Pulsational-Pair Instability Supernovae

    CERN Document Server

    Woosley, S E

    2016-01-01

    The final evolution of stars in the mass range 60 - 150 solar masses is explored. Depending upon their mass loss and rotation rates, many of these stars will end their lives as pulsational pair-instability supernovae. Even a non-rotating 70 solar mass star is pulsationally unstable during oxygen shell burning and can power a sub-luminous supernova. Rotation decreases the limit further. For more massive stars, the pulsations are less frequent, span a longer time, and are more powerful. Violent pulsations eject not only any residual low density envelope, but also that fraction of the helium core mass outside about 35 - 50 solar masses. The remaining core of helium and heavy elements continues to evolve, ultimately forming an iron core of about 2.5 solar masses that probably collapses to a black hole. A variety of observational transients result with total durations ranging from days to 10,000 years, and luminosities from 10$^{41}$ to 10$^{44}$ erg s$^{-1}$. Many transients resemble ordinary Type IIp supernovae,...

  19. The azimuthal magnetorotational instability (AMRI)

    CERN Document Server

    Ruediger, G; Schultz, M; Hollerbach, R; Stefani, F

    2013-01-01

    We consider the interaction of differential rotation and toroidal fields that are current-free in the gap between two corotating axially unbounded cylinders. It is shown that nonaxisymmetric perturbations are unstable if the rotation rate and Alfven frequency of the field are of the same order almost independent of the magnetic Prandtl number Pm. For the very steep rotation law \\Omega\\propto R^{-2} (the Rayleigh limit) this Azimuthal MagnetoRotational Instability (AMRI) scales with the ordinary Reynolds number and the Hartmann number, which allows a laboratory experiment with liquid metals like sodium or gallium in a Taylor-Couette container. The growth rate of AMRI scales with \\Omega^2 in the low-conductivity limit and with \\Omega in the high-conductivity limit. For the weakly nonlinear system the numerical values of the kinetic energy and the magnetic energy are derived for magnetic Prandtl numbers between 0.05 and unity. We find that the magnetic energy scales with the magnetic Reynolds number Rm, while th...

  20. Transient spirals as superposed instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Sellwood, J. A. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Carlberg, R. G., E-mail: sellwood@physics.rutgers.edu, E-mail: carlberg@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada)

    2014-04-20

    We present evidence that recurrent spiral activity, long manifested in simulations of disk galaxies, results from the superposition of a few transient spiral modes. Each mode lasts between 5 and 10 rotations at its corotation radius where its amplitude is greatest. The scattering of stars as each wave decays takes place over narrow ranges of angular momentum, causing abrupt changes to the impedance of the disk to subsequent traveling waves. Partial reflections of waves at these newly created features allows new standing-wave instabilities to appear that saturate and decay in their turn, scattering particles at new locations, creating a recurring cycle. The spiral activity causes the general level of random motion to rise, gradually decreasing the ability of the disk to support further activity unless the disk contains a dissipative gas component from which stars form on near-circular orbits. We also show that this interpretation is consistent with the behavior reported in other recent simulations with low-mass disks.

  1. Boyle's law and gravitational instability

    CERN Document Server

    Lombardi, M; Lombardi, Marco; Bertin, Giuseppe

    2001-01-01

    We have re-examined the classical problem of the macroscopic equation of state for a hydrostatic isothermal self-gravitating gas cloud bounded by an external medium at constant pressure. We have obtained analytical conditions for its equilibrium and stability without imposing any specific shape and symmetry to the cloud density distribution. The equilibrium condition can be stated in the form of an upper limit to the cloud mass; this is found to be inversely proportional to the power 3/2 of a form factor \\mu characterizing the shape of the cloud. In this respect, the spherical solution, associated with the maximum value of the form factor, \\mu = 1, turns out to correspond to the shape that is most difficult to realize. Surprisingly, the condition that defines the onset of the Bonnor instability (or gravothermal catastrophe) can be cast in the form of an upper limit to the density contrast within the cloud that is independent of the cloud shape. We have then carried out a similar analysis in the two-dimensiona...

  2. Thermal instability of cell nuclei

    Science.gov (United States)

    Warmt, Enrico; Kießling, Tobias R.; Stange, Roland; Fritsch, Anatol W.; Zink, Mareike; Käs, Josef A.

    2014-07-01

    DNA is known to be a mechanically and thermally stable structure. In its double stranded form it is densely packed within the cell nucleus and is thermo-resistant up to 70\\:^\\circ {\\rm{C}}. In contrast, we found a sudden loss of cell nuclei integrity at relatively moderate temperatures ranging from 45 to 55\\:^\\circ {\\rm{C}}. In our study, suspended cells held in an optical double beam trap were heated under controlled conditions while monitoring the nuclear shape. At specific critical temperatures, an irreversible sudden shape transition of the nuclei was observed. These temperature induced transitions differ in abundance and intensity for various normal and cancerous epithelial breast cells, which clearly characterizes different cell types. Our results show that temperatures slightly higher than physiological conditions are able to induce instabilities of nuclear structures, eventually leading to cell death. This is a surprising finding since recent thermorheological cell studies have shown that cells have a lower viscosity and are thus more deformable upon temperature increase. Since the nucleus is tightly coupled to the outer cell shape via the cytoskeleton, the force propagation of nuclear reshaping to the cell membrane was investigated in combination with the application of cytoskeletal drugs.

  3. Careers in conditions of instability

    Directory of Open Access Journals (Sweden)

    Hohlova Valentina Vasil'evna

    2016-04-01

    Full Text Available The purpose of this work is the research of the social-economic phenomenon of a career as a result of conscious human position and behaviour in the field of employment, which is connected with job and professional growth, as a chain of events which are components of life, the sequence of professional activities and other biographical roles, which all together express the commitment of a person’s activity according to his generalized model of self-development. On the basis of the theoretical analysis the dependence of making a career in the condition of instability and indefiniteness on job market flexibility, erosion and even the destruction of the usual way of life and labor relations. The career concepts under the conditions of flexible capitalism and of career policy as the typology of empiric differences of job biographic models are considered. The peculiarity of the proposed career policy concept is that its individual alternatives of career making oppose to organization management and personal demands: the difference between a professional’s wishes and a specific strategy of the development phases are quite noticeable. According to the results of empiric research carried out through the methods of interview, polling, expert assessment, the analysis of the received results, the mathematical data processing the basic types of the career policy and its connection with the organization’s personal development are revealed.

  4. Magnetorotational instability in protoplanetary discs

    CERN Document Server

    Salmeron, Roberto Aureliano; Salmeron, Raquel; Wardle, Mark

    2004-01-01

    We investigate the linear growth and vertical structure of the magnetorotational instability (MRI) in weakly ionised, stratified accretion discs. The magnetic field is initially vertical and dust grains are assumed to have settled towards the midplane, so charges are carried by electrons and ions only. Solutions are obtained at representative radial locations from the central protostar for different choices of the initial magnetic field strength, sources of ionisation, and disc surface density. The MRI is active over a wide range of magnetic field strengths and fluid conditions in low conductivity discs. For the minimum-mass solar nebula model, incorporating cosmic ray ionisation, perturbations grow at 1 AU for B < 8 G. For a significant subset of these strengths (0.2 - 5 G), the growth rate is of order the ideal MHD rate (0.75 Omega). Similarly, when cosmic rays are assumed to be excluded from the disc by the winds emitted by the magnetically active protostar, unstable modes grow at this radius for B less...

  5. Chromosomal instability determines taxane response

    DEFF Research Database (Denmark)

    Swanton, C.; Nicke, B.; Schuett, M.

    2009-01-01

    Microtubule-stabilizing (MTS) agents, such as taxanes, are important chemotherapeutics with a poorly understood mechanism of action. We identified a set of genes repressed in multiple cell lines in response to MTS agents and observed that these genes are overexpressed in tumors exhibiting chromos...... resistance but carboplatin sensitivity, indicating that CIN may determine MTS response in vivo. Thus, pretherapeutic assessment of CIN may optimize treatment stratification and clinical trial design using these agents....... chromosomal instability (CIN). Silencing 22/50 of these genes, many of which are involved in DNA repair, caused cancer cell death, suggesting that these genes are involved in the survival of aneuploid cells. Overexpression of these "CIN-survival'' genes is associated with poor outcome in estrogen receptor......-positive breast cancer and occurs frequently in basal-like and Her2-positive cases. In diploid cells, but not in chromosomally unstable cells, paclitaxel causes repression of CIN-survival genes, followed by cell death. In the OV01 ovarian cancer clinical trial, a high level of CIN was associated with taxane...

  6. Magnetorotational Explosive Instability in Keplerian Disks

    CERN Document Server

    Shtemler, Yuri; Mond, Michael

    2015-01-01

    In this paper it is shown that deferentially rotating disks that are in the presence of weak axial magnetic field are prone to a new nonlinear explosive instability. The latter occurs due to the near-resonance three-wave interactions of a magnetorotational instability with stable Alfven-Coriolis and magnetosonic modes. The dynamical equations that govern the temporal evolution of the amplitudes of the three interacting modes are derived. Numerical solutions of the dynamical equations indicate that small frequency mismatch gives rise to two types of behavior: 1. explosive instability which leads to infinite values of the three amplitudes within a finite time, and 2. bounded irregular oscillations of all three amplitudes. Asymptotic solutions of the dynamical equations are obtained for the explosive instability regimes and are shown to match the numerical solutions near the explosion time.

  7. Shear instabilities in shallow-water magnetohydrodynamics

    CERN Document Server

    Mak, Julian; Hughes, D W

    2016-01-01

    Within the framework of shallow-water magnetohydrodynamics, we investigate the linear instability of horizontal shear flows, influenced by an aligned magnetic field and stratification. Various classical instability results, such as H{\\o}iland's growth rate bound and Howard's semi-circle theorem, are extended to this shallow-water system for quite general profiles. Two specific piecewise-constant velocity profiles, the vortex sheet and the rectangular jet, are studied analytically and asymptotically; it is found that the magnetic field and stratification (as measured by the Froude number) are generally both stabilising, but weak instabilities can be found at arbitrarily large Froude number. Numerical solutions are computed for corresponding smooth velocity profiles, the hyperbolic-tangent shear layer and the Bickley jet, for a uniform background field. A generalisation of the long-wave asymptotic analysis of Drazin & Howard (1962) is employed in order to understand the instability characteristics for both ...

  8. Elliptical instability in terrestrial planets and moons

    CERN Document Server

    Cébron, David; Moutou, Claire; Gal, Patrice Le; 10.1051/0004-6361/201117741

    2012-01-01

    The presence of celestial companions means that any planet may be subject to three kinds of harmonic mechanical forcing: tides, precession/nutation, and libration. These forcings can generate flows in internal fluid layers, such as fluid cores and subsurface oceans, whose dynamics then significantly differ from solid body rotation. In particular, tides in non-synchronized bodies and libration in synchronized ones are known to be capable of exciting the so-called elliptical instability, i.e. a generic instability corresponding to the destabilization of two-dimensional flows with elliptical streamlines, leading to three-dimensional turbulence. We aim here at confirming the relevance of such an elliptical instability in terrestrial bodies by determining its growth rate, as well as its consequences on energy dissipation, on magnetic field induction, and on heat flux fluctuations on planetary scales. Previous studies and theoretical results for the elliptical instability are re-evaluated and extended to cope with ...

  9. Interfacial fluid instabilities and Kapitsa pendula

    CERN Document Server

    Krieger, Madison Ski

    2015-01-01

    The onset and development of instabilities is one of the central problems in fluid mechanics. Here we develop a connection between instabilities of free fluid interfaces and inverted pendula. When acted upon solely by the gravitational force, the inverted pendulum is unstable. This position can be stabilised by the Kapitsa phenomenon, in which high-frequency low-amplitude vertical vibrations of the base creates a fictitious force which opposes the gravitational force. By transforming the dynamical equations governing a fluid interface into an appropriate pendulum, we demonstrate how stability can be induced in fluid systems by properly tuned vibrations. We construct a "dictionary"-type relationship between various pendula and the classical Rayleigh-Taylor, Kelvin-Helmholtz, Rayleigh-Plateau and the self-gravitational instabilities. This makes several results in control theory and dynamical systems directly applicable to the study of "tunable" fluid instabilities, where the critical wavelength depends on the e...

  10. Zonostrophic instability driven by discrete particle noise

    CERN Document Server

    St-Onge, D A

    2016-01-01

    The consequences of discrete particle noise for a system possessing a possibly unstable collective mode are discussed. It is argued that a zonostrophic instability (of homogeneous turbulence to the formation of zonal flows) occurs just below the threshold for linear instability. The scenario provides a new interpretation of the random forcing that is ubiquitously invoked in stochastic models such as the second-order cumulant expansion (CE2) or stochastic structural instability theory (SSST); neither intrinsic turbulence nor coupling to extrinsic turbulence is required. A representative calculation of the zonostrophic neutral curve is made for a simple two-field model of toroidal ion-temperature-gradient-driven modes. To the extent that the damping of zonal flows is controlled by the ion--ion collision rate, the point of zonostrophic instability is independent of that rate.

  11. Kelvin-Helmholtz instability in solar spicules

    Directory of Open Access Journals (Sweden)

    H Ebadi

    2016-12-01

    Full Text Available Magneto hydrodynamic waves, propagating along spicules, may become unstable and the expected instability is of Kelvin-Helmholtz type. Such instability can trigger the onset of wave turbulence leading to an effective plasma heating and particle acceleration. In present study, two-dimensional magneto hydrodynamic simulations performed on a Cartesian grid is presented in spicules with different densities, moving at various speeds depending on their environment. Simulations being applied in this study show the onset of Kelvin-Helmholtz type instability and transition to turbulent flow in spicules. Development of Kelvin-Helmholtz instability leads to momentum and energy transport, dissipation, and mixing of fluids. When magnetic fields are involved, field amplification is also possible to take place

  12. Fluid description for the resonant Weibel instability

    CERN Document Server

    Sarrat, M; Ghizzo, A

    2016-01-01

    We discuss a fluid model with inclusion of the complete pressure tensor dynamics for the description of Weibel type instabilities in a counterstreaming beams configuration. Differently from the case recently studied in Sarrat et al. 2016, where perturbations perpendicular to the beams were considered, here we focus only on modes propagating along the beams. Such a configuration is responsible for the growth of two kind of instabilities, the Two-Stream Instability and the Weibel instability, which in this geometry becomes "time-resonant", i.e. propagative. This fluid description agrees with the kinetic one and makes it possible e.g. to identify the transition between non-propagative and propagative Weibel modes, already evidenced by Lazar et al. 2009 as a "slope-breaking" of the growth rate, in terms of a merger of two non propagative Weibel modes.

  13. Can dust coagulation trigger streaming instability?

    CERN Document Server

    Drazkowska, Joanna

    2014-01-01

    Streaming instability can be a very efficient way of overcoming growth and drift barriers to planetesimal formation. However, it was shown that strong clumping, which leads to planetesimal formation, requires a considerable number of large grains. State-of-the-art streaming instability models do not take into account realistic size distributions resulting from the collisional evolution of dust. We investigate whether a sufficient quantity of large aggregates can be produced by sticking and what the interplay of dust coagulation and planetesimal formation is. We develop a semi-analytical prescription of planetesimal formation by streaming instability and implement it in our dust coagulation code based on the Monte Carlo algorithm with the representative particles approach. We find that planetesimal formation by streaming instability may preferentially work outside the snow line, where sticky icy aggregates are present. The efficiency of the process depends strongly on local dust abundance and radial pressure g...

  14. Electrocapillary instability of magnetic fluid peak

    CERN Document Server

    Mkrtchyan, Levon; Dikansky, Yuri

    2013-01-01

    The paper presents an experimental study of the capillary electrostatic instability occurring under effect of a constant electric field on a magnetic fluid individual peak. The peaks under study occur at disintegration of a magnetic fluid layer applied on a flat electrode surface under effect of a perpendicular magnetic field. The electrocapillary instability shows itself as an emission of charged drops jets from the peak point in direction of the opposing electrode. The charged drops emission repeats periodically and results in the peak shape pulsations. It is shown that a magnetic field affects the electrocapillary instability occurrence regularities and can stimulate its development. The critical electric and magnetic field strengths at which the instability occurs have been measured; their dependence on the peak size is shown. The hysteresis in the system has been studied; it consists in that the charged drops emission stops at a lesser electric (or magnetic) field strength than that of the initial occurr...

  15. Experimental Replication of an Aeroengine Combustion Instability

    Science.gov (United States)

    Cohen, J. M.; Hibshman, J. R.; Proscia, W.; Rosfjord, T. J.; Wake, B. E.; McVey, J. B.; Lovett, J.; Ondas, M.; DeLaat, J.; Breisacher, K.

    2000-01-01

    Combustion instabilities in gas turbine engines are most frequently encountered during the late phases of engine development, at which point they are difficult and expensive to fix. The ability to replicate an engine-traceable combustion instability in a laboratory-scale experiment offers the opportunity to economically diagnose the problem (to determine the root cause), and to investigate solutions to the problem, such as active control. The development and validation of active combustion instability control requires that the causal dynamic processes be reproduced in experimental test facilities which can be used as a test bed for control system evaluation. This paper discusses the process through which a laboratory-scale experiment was designed to replicate an instability observed in a developmental engine. The scaling process used physically-based analyses to preserve the relevant geometric, acoustic and thermo-fluid features. The process increases the probability that results achieved in the single-nozzle experiment will be scalable to the engine.

  16. Nonlinear electrostatic drift Kelvin-Helmholtz instability

    Science.gov (United States)

    Sharma, Avadhesh C.; Srivastava, Krishna M.

    1993-01-01

    Nonlinear analysis of electrostatic drift Kelvin-Helmholtz instability is performed. It is shown that the analysis leads to the propagation of the weakly nonlinear dispersive waves, and the nonlinear behavior is governed by the nonlinear Burger's equation.

  17. Overview of Rayleigh-Taylor instability

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, D.H.

    1983-01-01

    The aim of this talk is to survey Rayleigh-Taylor instability, describing the phenomenology that occurs at a Taylor unstable interface, and reviewing attempts to understand these phenomena quantitatively.

  18. Summary of impedance issues and beam instabilities

    CERN Document Server

    Zimmermann, Frank

    2016-01-01

    This paper summarizes the session on impedance issues and beam instabilities at the ICFA workshop on future circular electron-positron factories “eeFACT2016” [1] held at the Cockcroft Institute, Daresbury, from 24 to 27 October 2016. This session also covered active beam stabilization by feedback systems. Beam-beam effects and coherent beambeam instabilities were addressed separately and, therefore, are not included here.

  19. Jeans instability in the linearized Burnett regime

    CERN Document Server

    García-Colin, L S

    2005-01-01

    Jeans instability is derived for the case of a low density self-gravitating gas beyond the Navier-Stokes equations. The Jeans instability criterium is shown to depend on a Burnett coefficient if the formalism is taken up to fourth order in the wave number. It is also shown that previously known viscosity corrections to the Jeans wave-number are enhanced if the full fourth order formalism is applied to the stability analysis.

  20. Energetic particle instabilities in fusion plasmas

    CERN Document Server

    Sharapov, S E; Berk, H L; Borba, D N; Breizman, B N; Challis, C D; Classen, I G J; Edlund, E M; Eriksson, J; Fasoli, A; Fredrickson, E D; Fu, G Y; Garcia-Munoz, M; Gassner, T; Ghantous, K; Goloborodko, V; Gorelenkov, N N; Gryaznevich, M P; Hacquin, S; Heidbrink, W W; Hellesen, C; Kiptily, V G; Kramer, G J; Lauber, P; Lilley, M K; Lisak, M; Nabais, F; Nazikian, R; Nyqvist, R; Osakabe, M; von Thun, C Perez; Pinches, S D; Podesta, M; Porkolab, M; Shinohara, K; Schoepf, K; Todo, Y; Toi, K; Van Zeeland, M A; Voitsekhovich, I; White, R B; Yavorskij, V; TG, ITPA EP; Contributors, JET-EFDA

    2013-01-01

    Remarkable progress has been made in diagnosing energetic particle instabilities on present-day machines and in establishing a theoretical framework for describing them. This overview describes the much improved diagnostics of Alfven instabilities and modelling tools developed world-wide, and discusses progress in interpreting the observed phenomena. A multi-machine comparison is presented giving information on the performance of both diagnostics and modelling tools for different plasma conditions outlining expectations for ITER based on our present knowledge.

  1. Plasma wave instabilities in nonequilibrium graphene

    DEFF Research Database (Denmark)

    Aryal, Chinta M.; Hu, Ben Yu-Kuang; Jauho, Antti-Pekka

    2016-01-01

    We study two-stream instabilities in a nonequilibrium system in which a stream of electrons is injected into doped graphene. As with equivalent nonequilibrium parabolic band systems, we find that the graphene systems can support unstable charge-density waves whose amplitudes grow with time. We...... of the injected electrons that maximizes the growth rate increases with increasing | q |. We compare the range and strength of the instability in graphene to that of two- and three-dimensional parabolic band systems....

  2. Resonant Triad Instability in Stratified Fluids

    CERN Document Server

    Joubaud, Sylvain; Odier, Philippe; Dauxois, Thierry

    2012-01-01

    Internal gravity waves contribute to fluid mixing and energy transport, not only in oceans but also in the atmosphere and in astrophysical bodies. We provide here the first experimental measurement of the growth rate of a resonant triad instability (also called parametric subharmonic instability) transferring energy to smaller scales where it is dissipated. We make careful and quantitative comparisons with theoretical predictions for propagating vertical modes in laboratory experiments.

  3. On viscoelastic instability in polymeric filaments

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Hassager, Ole

    1999-01-01

    The 3D Lagrangian Integral Method is used to simulate the effects of surface tension on the viscoelastic end-plate instability, occuring in the rapid extension of some polymeric filaments between parallel plates. It is shovn that the surface tension delays the onset of the instability. Furthermore...... it is demonstrated that surface tension plays a key role in the selection of the most unstable mode...

  4. ON THE INSTABILITY OF THE RAILWAY VEHICLES

    Directory of Open Access Journals (Sweden)

    Traian MAZILU

    2011-11-01

    Full Text Available The railway vehicles have two sources of instability. The most common is the hunting induced by the reversed conic shape of the rolling surfaces of the wheels. The other one is related by the anomalous Doppler effect that can occurs when the train velocity exceeds the phase velocity of the waves induced in the track structure. Some aspects regarding the two sources of instability are presented.

  5. Studies of elastic-plastic instabilities

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    1999-01-01

    Analyses of plastic instabilities are reviewed, with focus on results in structural mechanics as well as continuum mechanics. First the basic theories for bifurcation and post-bifurcation behavior are briefly presented. Then, localization of plastic flow is discussed, including shear band formation...... in solids, localized necking in biaxially stretched metal sheets, and the analogous phenomenon of buckling localization in structures. Also some recent results for cavitation instabilities in elastic-plastic solids are reviewed....

  6. Systematics of shoulder instability; Systematik der Schulterinstabilitaet

    Energy Technology Data Exchange (ETDEWEB)

    Kreitner, K.F.; Maehringer-Kunz, A. [Johannes-Gutenberg-Universitaet Mainz, Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie, Mainz (Germany)

    2015-03-01

    Shoulder instability is defined as a symptomatic abnormal motion of the humeral head relative to the glenoid during active shoulder motion. Glenohumeral instabilities are classified according to the causative factors as the pathogenesis of instability plays an important role with respect to treatment options. Instabilities are classified into traumatic and atraumatic instabilities as part of a multidirectional instability syndrome and into microtraumatic instabilities. For diagnostics plain radiographs (''trauma series'') are performed to document shoulder dislocation and its successful repositioning. Direct magnetic resonance (MR) arthrography is the most important imaging modality for delineation of the different injury patterns of the labral-ligamentous complex and bony structures. Monocontrast computed tomography (CT) arthrography with the use of multidetector CT scanners represents an alternative imaging modality; however, MR imaging should be preferred in the work-up of shoulder instabilities due to the mostly younger age of patients. (orig.) [German] Unter einer Schulterinstabilitaet versteht man jede zu Beschwerden fuehrende Translation des Humeruskopfs in Relation zur Gelenkpfanne waehrend einer aktiven Bewegung der Schulter. Glenohumerale Instabilitaeten werden heute nach ihrer Aetiologie eingeteilt, da bei der Wahl der Therapie der Entstehungsmechanismus der Instabilitaet eine wichtige Rolle spielt. Danach unterscheidet man primaer traumatisch von atraumatisch entstandenen Instabilitaeten sowie Mikroinstabilitaeten. Bei der Diagnostik dienen konventionelle Roentgenuebersichtsaufnahmen nur noch zur Dokumentation einer Luxation und zur Beurteilung der Reposition. Die durch eine Instabilitaet hervorgerufenen Verletzungsfolgen am labroligamentaeren Komplex und den knoechernen Strukturen werden heute bevorzugt mit der direkten MR-Arthrographie dargestellt. Hierbei koennen unterschiedliche Verletzungsmuster dargestellt werden. Nach

  7. Weibel instability in relativistic quantum plasmas

    Science.gov (United States)

    Mendonça, J. T.; Brodin, G.

    2015-08-01

    Generation of quasi-static magnetic fields, due to the Weibel instability is studied in a relativistic quantum plasma. This instability is induced by a temperature anisotropy. The dispersion relation and growth rates for low frequency electromagnetic perturbations are derived using a wave-kinetic equation which describes the evolution of the electron Wigner quasi-distribution. The influence of parallel kinetic effects is discussed in detail.

  8. A hydrodynamic approach to QGP instabilities

    CERN Document Server

    Calzetta, E

    2013-01-01

    We show that the usual linear analysis of QGP Weibel instabilities based on the Maxwell-Boltzmann equation may be reproduced in a purely hydrodynamic model. The latter is derived by the Entropy Production Variational Method from a transport equation including collisions, and can describe highly nonequilibrium flow. We find that, as expected, collisions slow down the growth of Weibel instabilities. Finally, we discuss the strong momentum anisotropy limit.

  9. Correlation of OPLL with spinal instability

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ho Chul; Chung, Tae Sub; Kim, Young Soo [Yonsei Univ. College of Medicine, Seoul (Korea, Republic of)

    1998-08-01

    To evaluate the relationship between spinal instability and ossification of the posterior longitudinal ligament(OPLL). Materials and Methods: In 70 patients(M:F=45:25, mean age=53 years) diagnosed as OPLL on the basis of surgical operation field findings and radiological evaluation [plain film(n=70), CT(n=64),MRI(n=55)], involved levels were the cervical spine(n=32), lumbar spine(n=23), and both the cervical and lumbar spine(n=15). Spinal instability was radiologically diagnosed as horizontal displacement of one vertebra by another of more than 3.5 mm, or a difference in rotation from either adjacent vertebra by more than 11 degree in lateral cervical spine and a difference of more than 1.5 mm from the posterior body margins to the point of intersection of two lines drawn parallel to the opposing segmental endplate in extension lateral lumbar spine. We divided OPLL into group I(continuous, segmental, mixed) and group II(retrodiscal), and compared spinal instability in these two groups. Results: In cervical OPLL, group I comprised 33 cases and group II 14. In group I, spinal instability was noted in 8/33 cases(24%) or 10/123 segments(8.1%). Spinal instability in group II, on the other hand, was found in 13/14 cases(93%) or 17/26 segments(65%). Ossification occurred at the retrodiscal level in 37 cases, byt in case was continuous. In group II, spinal instability was found in 25 of 37 cases(69%), oe in 29 of 55 segments(53%). Conclusion: Compared to other types of OPLL, the frequency of retrodiscal OPLL in association with spinal instability was high. Spinal instability may thus be the most important cause of retrodiscal OPLL.

  10. Beam Instabilities in Circular Particle Accelerators

    CERN Document Server

    Metral, Elias

    2017-01-01

    The theory of impedance-induced bunched-beam coherent instabilities is reviewed following Laclare's formalism, adding the effect of an electronic damper in the transverse plane. Both single-bunch and coupled-bunch instabilities are discussed, both low-intensity and high-intensity regimes are analysed, both longitudinal and transverse planes are studied, and both short-bunch and long-bunch regimes are considered. Observables and mitigation measures are also examined.

  11. Spinal instability in ankylosing spondylitis

    Directory of Open Access Journals (Sweden)

    Badve Siddharth

    2010-01-01

    Full Text Available Background: Unstable spinal lesions in patients with ankylosing spondylitis are common and have a high incidence of associated neurological deficit. The evolution and presentation of these lesions is unclear and the management strategies can be confusing. We present retrospective analysis of the cases of ankylosing spondylitis developing spinal instability either due to spondylodiscitis or fractures for mechanisms of injury, presentations, management strategies and outcome. Materials and Methods: In a retrospective analysis of 16 cases of ankylosing spondylitis, treated surgically for unstable spinal lesions over a period of 12 years (1995-2007; 87.5% (n=14 patients had low energy (no obvious/trivial trauma while 12.5% (n=2 patients sustained high energy trauma. The most common presentation was pain associated with neurological deficit. The surgical indications included neurological deficit, chronic pain due to instability and progressive deformity. All patients were treated surgically with anterior surgery in 18.8% (n=3 patients, posterior in 56.2% (n=9 patients and combined approach in 25% (n=4 patients. Instrumented fusion was carried out in 87.5% (n=14 patients. Average surgical duration was 3.84 (Range 2-7.5 hours, blood loss 765.6 (± 472.5 ml and follow-up 54.5 (Range 18-54 months. The patients were evaluated for pain score, Frankel neurological grading, deformity progression and radiological fusion. One patient died of medical complications a week following surgery. Results: Intra-operative adverse events like dural tears and inadequate deformity correction occurred in 18.7% (n=3 patients (Cases 6, 7 and 8 which could be managed conservatively. There was a significant improvement in the Visual analogue score for pain from a pre-surgical median of 8 to post-surgical median of 2 (P=0.001, while the neurological status improved in 90% (n=9 patients among those with preoperative neurological deficit who could be followed-up (n =10. Frankel

  12. The Abelianization of QCD Plasma Instabilities

    CERN Document Server

    Arnold, P; Arnold, Peter; Lenaghan, Jonathan

    2004-01-01

    QCD plasma instabilities appear to play an important role in the equilibration of quark-gluon plasmas in heavy-ion collisions in the theoretical limit of weak coupling (i.e. asymptotically high energy). It is important to understand what non-linear physics eventually stops the exponential growth of unstable modes. It is already known that the initial growth of plasma instabilities in QCD closely parallels that in QED. However, once the unstable modes of the gauge-fields grow large enough for non-Abelian interactions between them to become important, one might guess that the dynamics of QCD plasma instabilities and QED plasma instabilities become very different. In this paper, we give suggestive arguments that non-Abelian self-interactions between the unstable modes are ineffective at stopping instability growth, and that the growing non-Abelian gauge fields become approximately Abelian after a certain stage in their growth. This in turn suggests that understanding the development of QCD plasma instabilities i...

  13. On the chiral imbalance and Weibel instabilities

    Science.gov (United States)

    Kumar, Avdhesh; Bhatt, Jitesh R.; Kaw, P. K.

    2016-06-01

    We study the chiral-imbalance and the Weibel instabilities in presence of the quantum anomaly using the Berry-curvature modified kinetic equation. We argue that in many realistic situations, e.g. relativistic heavy-ion collisions, both the instabilities can occur simultaneously. The Weibel instability depends on the momentum anisotropy parameter ξ and the angle (θn) between the propagation vector and the anisotropy direction. It has maximum growth rate at θn = 0 while θn = π / 2 corresponds to a damping. On the other hand the pure chiral-imbalance instability occurs in an isotropic plasma and depends on difference between the chiral chemical potentials of right and left-handed particles. It is shown that when θn = 0, only for a very small values of the anisotropic parameter ξ ∼ξc, growth rates of the both instabilities are comparable. For the cases ξc Weibel modes dominate over the chiral-imbalance instability if μ5 / T ≤ 1. However, when μ5 / T ≥ 1, it is possible to have dominance of the chiral-imbalance modes at certain values of θn for an arbitrary ξ.

  14. [Capsular retensioning in anterior unidirectional glenohumeral instability].

    Science.gov (United States)

    Benítez Pozos, Leonel; Martínez Molina, Oscar; Castañeda Landa, Ezequiel

    2007-01-01

    To present the experience of the Orthopedics Service PEMEX South Central Hospital in the management of anterior unidirectional shoulder instability with an arthroscopic technique consisting of capsular retensioning either combined with other anatomical repair procedures or alone. Thirty-one patients with anterior unidirectional shoulder instability operated-on between January 1999 and December 2005 were included. Fourteen patients underwent capsular retensioning and radiofrequency, and in 17 patients, capsular retensioning was combined with suture anchors. Patients with a history of relapsing glenohumeral dislocations and subluxations, with anterior instability with or without associated Bankart lesions were selected; all of them were young. The results were assessed considering basically the occurrence of instability during the postoperative follow-up. No cases of recurring instability occurred. Two cases had neuroma and one experienced irritation of the suture site. Six patients had residual limitation of combined lateral rotation and abduction movements, of a mean of 10 degrees compared with the healthy contralateral side. The most frequent incident was the leak of solutions to the soft tissues. Capsular retensioning, whether combined or not with other anatomical repair techniques, has proven to result in a highly satisfactory rate of glenohumeral stabilization in cases of anterior unidirectional instabilities. The arthroscopic approach offers the well-known advantages of causing less damage to the soft tissues, and a shorter time to starting rehabilitation therapy and exercises.

  15. Hydrogeologic Framework, Groundwater Movement, and Water Budget in the Chambers-Clover Creek Watershed and Vicinity, Pierce County, Washington

    Science.gov (United States)

    Savoca, Mark E.; Welch, Wendy B.; Johnson, Kenneth H.; Lane, R.C.; Fasser, Elisabeth T.

    2010-01-01

    This report presents information used to characterize the groundwater-flow system in the Chambers-Clover Creek Watershed and vicinity, and includes descriptions of the geology and hydrogeologic framework; groundwater recharge and discharge; groundwater levels and flow directions; seasonal groundwater level fluctuations; interactions between aquifers and the surface-water system; and a water budget. The study area covers about 706 square miles in western Pierce County, Washington, and extends north to the Puyallup River, southwest to the Nisqually River, and is bounded on the south and east by foothills of the Cascade Range and on the west by Puget Sound. The area is underlain by a northwest-thickening sequence of unconsolidated glacial and interglacial deposits which overlie sedimentary and volcanic bedrock units that crop out in the foothills along the southern and southeastern margin of the study area. Geologic units were grouped into 11 hydrogeologic units consisting of aquifers, confining units, and an underlying bedrock unit. A surficial hydrogeologic unit map was developed and used with well information from 450 drillers' logs to construct 6 hydrogeologic sections, and unit extent and thickness maps. Groundwater in unconsolidated glacial and interglacial aquifers generally flows to the northwest towards Puget Sound, and to the north and northeast towards the Puyallup River. These generalized flow patterns likely are complicated by the presence of low permeability confining units that separate discontinuous bodies of aquifer material and act as local groundwater-flow barriers. Water levels in wells completed in the unconsolidated hydrogeologic units show seasonal variations ranging from less than 1 to about 50 feet. The largest groundwater-level fluctuation (78 feet) observed during the monitoring period (March 2007-September 2008) was in a well completed in the bedrock unit. Synoptic streamflow measurements made in September 2007 and July 2008 indicated a

  16. Numerical simulation of the groundwater-flow system in the Chambers-Clover Creek Watershed and Vicinity, Pierce County, Washington

    Science.gov (United States)

    Johnson, Kenneth H.; Savoca, Mark E.; Clothier, Burt

    2011-01-01

    A groundwater-flow model was developed to contribute to an improved understanding of water resources in the Chambers-Clover Creek Watershed. The model covers an area of about 491 square miles in western Pierce County, Washington, and is bounded to the northeast by the Puyallup River valley, to the southwest by the Nisqually River valley, and extends northwest to Puget Sound, and southeast to Tanwax Creek. The Puyallup and Nisqually Rivers occupy large, relatively flat alluvial valleys that are separated by a broad, poorly drained, upland area that covers most of the model area. Chambers and Clover Creeks drain much of the central uplands and flow westward to Puget Sound. The model area is underlain by a northwest-thickening sequence of unconsolidated glacial (till and outwash) and interglacial (fluvial and lacustrine) deposits. Ten unconsolidated hydrogeologic units in the model area form the basis of the groundwater-flow model. Groundwater flow in the Chambers-Clover Creek Watershed and vicinity was simulated using the groundwater-flow model, MODFLOW-2000. The finite-difference model grid comprises 146 rows, 132 columns, and 11 layers. Each model cell has a horizontal dimension of 1,000 by 1,000 feet, and the model contains a total of 123,602 active cells. The thickness of model layers varies throughout the model area and ranges from 1.5 feet in the A3 aquifer unit to 1,567 feet in the G undifferentiated unit. Groundwater flow was simulated for both steady-state and transient conditions. Steady-state conditions were simulated using average recharge, discharge, and water levels for the 24-month period September 2006-August 2008. Transient conditions were simulated for the period September 2006-August 2008 using 24 monthly stress periods. Resource managers and local stakeholders intend to use the model to evaluate a range of water resource issues under both steady-state and transient conditions. Initial conditions for the transient model were developed from a 3-year

  17. Beam-Ion Instability in PEP-II

    Energy Technology Data Exchange (ETDEWEB)

    Heifets, S.; Kulikov, A.; Wang, Min-Huey; Wienands, U.; /SLAC

    2007-11-07

    The instability in the PEP-II electron ring has been observed while reducing the clearing gap in the bunch train. We study the ion effects in the ring summarizing existing theories of the beam-ion interaction, comparing them with observations, and estimating effect on luminosity in the saturation regime. Considering the gap instability we suggest that the instability is triggered by the beam-ion instability, and discuss other mechanisms pertinent to the instability.

  18. Laser pulse modulation instabilities in partially stripped plasma

    Institute of Scientific and Technical Information of China (English)

    Hu Qiang-Lin; Liu Shi-Bing; Jiang Yi-Jian

    2005-01-01

    The laser pulse modulation instabilities in partially stripped plasma were discussed based on the phase and group velocities of the laser pulse and the two processes that modulation instabilities excited. The excitation condition and growth rate of the modulation instability were obtained. It was found that the positive chirp and competition between normal and abnormal dispersions play important roles in the modulation instability. In the partially stripped plasma,the increased positive chirp enhances the modulation instability, and the dispersion competition reduces it.

  19. Instabilities in Interacting Binary Stars

    Science.gov (United States)

    Andronov, I. L.; Andrych, K. D.; Antoniuk, K. A.; Baklanov, A. V.; Beringer, P.; Breus, V. V.; Burwitz, V.; Chinarova, L. L.; Chochol, D.; Cook, L. M.; Cook, M.; Dubovský, P.; Godlowski, W.; Hegedüs, T.; Hoňková, K.; Hric, L.; Jeon, Y.-B.; Juryšek, J.; Kim, C.-H.; Kim, Y.; Kim, Y.-H.; Kolesnikov, S. V.; Kudashkina, L. S.; Kusakin, A. V.; Marsakova, V. I.; Mason, P. A.; Mašek, M.; Mishevskiy, N.; Nelson, R. H.; Oksanen, A.; Parimucha, S.; Park, J.-W.; Petrík, K.; Quiñones, C.; Reinsch, K.; Robertson, J. W.; Sergey, I. M.; Szpanko, M.; Tkachenko, M. G.; Tkachuk, L. G.; Traulsen, I.; Tremko, J.; Tsehmeystrenko, V. S.; Yoon, J.-N.; Zola, S.; Shakhovskoy, N. M.

    2017-07-01

    The types of instability in the interacting binary stars are briefly reviewed. The project “Inter-Longitude Astronomy” is a series of smaller projects on concrete stars or groups of stars. It has no special funds, and is supported from resources and grants of participating organizations, when informal working groups are created. This “ILA” project is in some kind similar and complementary to other projects like WET, CBA, UkrVO, VSOLJ, BRNO, MEDUZA, AstroStatistics, where many of us collaborate. Totally we studied 1900+ variable stars of different types, including newly discovered variables. The characteristic timescale is from seconds to decades and (extrapolating) even more. The monitoring of the first star of our sample AM Her was initiated by Prof. V.P. Tsesevich (1907-1983). Since more than 358 ADS papers were published. In this short review, we present some highlights of our photometric and photo-polarimetric monitoring and mathematical modeling of interacting binary stars of different types: classical (AM Her, QQ Vul, V808 Aur = CSS 081231:071126+440405, FL Cet), asynchronous (BY Cam, V1432 Aql), intermediate (V405 Aql, BG CMi, MU Cam, V1343 Her, FO Aqr, AO Psc, RXJ 2123, 2133, 0636, 0704) polars and magnetic dwarf novae (DO Dra) with 25 timescales corresponding to different physical mechanisms and their combinations (part “Polar”); negative and positive superhumpers in nova-like (TT Ari, MV Lyr, V603 Aql, V795 Her) and many dwarf novae stars (“Superhumper”); eclipsing “non-magnetic” cataclysmic variables(BH Lyn, DW UMa, EM Cyg; PX And); symbiotic systems (“Symbiosis”); super-soft sources (SSS, QR And); spotted (and not spotted) eclipsing variables with (and without) evidence for a current mass transfer (“Eclipser”) with a special emphasis on systems with a direct impact of the stream into the gainer star's atmosphere, which we propose to call “Impactor” (short from “Extreme Direct Impactor”), or V361 Lyr-type stars. Other

  20. Dynamic Instability of Rapidly Rotating Protostars

    Science.gov (United States)

    Pickett, B. K.; Durisen, R. H.; Johnson, M. S.; Davis, G. A.

    1994-12-01

    Modern studies of collapse and fragmentation of protostellar clouds suggest a wide variety of outcomes, depending on the assumed initial conditions. Individual equilibrium objects which result from collapse are likely to be in rapid rotation and can have a wide range of structures. We have undertaken a survey of parameter space in order to examine the role of dynamic instabilities in the subsequent evolution of these objects. For the purposes of conducting a systematic study, we so far have considered only the n = 3/2 polytropic equilibrium states that might form from the collapse of uniformly rotating spherical clouds. By varying the central concentration of the assumed initial cloud, we obtain equilibrium states distinguished primarily by their different specific angular momentum distributions. These equilibrium states span the range between starlike objects with angular momentum distributions analogous to the Maclaurin spheroids and objects more accurately described as massive Keplerian disks around stars. Using a new SCF code to generate the n = 3/2 axisymmetric equilibrium states and an improved 3D hydrodynamics code, we have investigated the the onset and nature of global dynamic instabilities in these objects. The starlike objects are unstable to barlike instabilities at T/|W| gtorder 0.27, where T/|W| is the ratio of total rotational kinetic energy to gravitational potential energy. These instabilities are vigorous and lead to violent ejection of mass and angular momentum. As the angular momentum distribution shifts to the other extreme, one- and two-armed spiral instabilities begin to dominate at considerably lower T/|W|. These instabilities appear to be driven by the SLING and swing mechanisms. In extremely flattened disks, one-armed spirals dominate all other disturbances but eventually saturate at nonlinear amplitude without producing fragmentation. We conclude that the nature of the global instabilities encountered during the process of star formation

  1. Intimate partner violence and housing instability.

    Science.gov (United States)

    Pavao, Joanne; Alvarez, Jennifer; Baumrind, Nikki; Induni, Marta; Kimerling, Rachel

    2007-02-01

    The mental and physical health consequences of intimate partner violence (IPV) have been well established, yet little is known about the impact of violence on a woman's ability to obtain and maintain housing. This cross-sectional study examines the relationship between recent IPV and housing instability among a representative sample of California women. It is expected that women who have experienced IPV will be at increased risk for housing instability as evidenced by: (1) late rent or mortgage, (2) frequent moves because of difficulty obtaining affordable housing, and/or (3) without their own housing. Data were taken from the 2003 California Women's Health Survey, a population-based, random-digit-dial, annual probability survey of adult California women (N=3619). Logistic regressions were used to predict housing instability in the past 12 months, adjusting for the following covariates; age, race/ethnicity, education, poverty status, marital status, children in the household, and past year IPV. In the multivariate model, age, race/ethnicity, marital status, poverty, and IPV were significant predictors of housing instability. After adjusting for all covariates, women who experienced IPV in the last year had almost four times the odds of reporting housing instability than women who did not experience IPV (adjusted odds ratio=3.98, 95% confidence interval: 2.94-5.39). This study found that IPV was associated with housing instability among California women. Future prospective studies are needed to learn more about the nature and direction of the relationship between IPV and housing instability and the possible associated negative health consequences.

  2. Dynamical instabilities in disc-planet interactions

    CERN Document Server

    Lin, Min-Kai

    2012-01-01

    Protoplanetary discs may become dynamically unstable due to structure induced by an embedded giant planet. In this thesis, I discuss the stability of such systems and explore the consequence of instability on planetary migration. I begin with non-self-gravitating, low viscosity discs and show that giant planets induce shocks inside its co-orbital region, leading to a profile unstable to vortex formation around a potential vorticity minimum. This instability is commonly known as the vortex or Rossby wave instability. Vortex-planet interaction lead to episodic phases of migration, which can be understood in the framework of type III migration. I then examine the effect of disc self-gravity on gap stability. The linear theory of the Rossby wave instability is extended to include disc gravity, which shows that self-gravity is effective at stabilising the vortex instability at small azimuthal wavenumber. This is consistent with the observation that more vortices develop with increasing disc mass in hydrodynamic si...

  3. Coherent Instabilities of ILC Damping Ring

    Energy Technology Data Exchange (ETDEWEB)

    Heifets, S.; Stupakov, G.; Bane, K.; /SLAC

    2006-09-27

    The paper presents the first attempt to estimates the ILC damping ring impedance and compare thresholds of the classical instabilities for several designs initially proposed for the DR. The work was carried out in the spring of 2006. Since then the choice of the DR is narrowed. Nevertheless, the analysis described may be useful for the next iterations of the beam stability. Overall, the conventional instabilities will have little impact on the ring performance provided the careful design of the ring minimizes the impedance below acceptable level indicated above. The only exception is the transverse CB instability. The longitudinal CB is less demanding. However, even the transverse CB instability would have threshold current above nominal provided the aperture in the wigglers is increased from 8 mm to 16 mm. The microwave instability needs more studies. Nevertheless, we should remember that the ILC DR is different from existing high-current machines at least in two respects: absence of the beam-beam tune spread stabilizing beams in colliders, and unusual strict requirements for low emittance. That may cause new problems such as bunch emittance dilution due to high-frequency wakes (BPMs, grooves), etc. Even if such a possibility exists, it probably universal for all machines and ought be addressed in the design of vacuum components rather than have effect on the choice of the machine design.

  4. Tidal instability in exoplanetary systems evolution

    Directory of Open Access Journals (Sweden)

    Le Gal P.

    2011-02-01

    Full Text Available A new element is proposed to play a role in the evolution of extrasolar planetary systems: the tidal (or elliptical instability. It comes from a parametric resonance and takes place in any rotating fluid whose streamlines are (even slightly elliptically deformed. Based on theoretical, experimental and numerical works, we estimate the growth rate of the instability for hot-jupiter systems, when the rotation period of the star is known. We present the physical process, its application to stars, and preliminary results obtained on a few dozen systems, summarized in the form of a stability diagram. Most of the systems are trapped in the so-called "forbidden zone", where the instability cannot grow. In some systems, the tidal instability is able to grow, at short timescales compared to the system evolution. Implications are discussed in the framework of misaligned transiting systems, as the rotational axis of the star would be unstable in systems where this elliptical instability grows.

  5. Diffusive Magnetohydrodynamic Instabilities beyond the Chandrasekhar Theorem

    Science.gov (United States)

    Rüdiger, Günther; Schultz, Manfred; Stefani, Frank; Mond, Michael

    2015-10-01

    We consider the stability of axially unbounded cylindrical flows that contain a toroidal magnetic background field with the same radial profile as their azimuthal velocity. For ideal fluids, Chandrasekhar had shown the stability of this configuration if the Alfvén velocity of the field equals the velocity of the background flow, i.e., if the magnetic Mach number {Mm}=1. We demonstrate that magnetized Taylor-Couette flows with such profiles become unstable against non-axisymmetric perturbations if at least one of the diffusivities is finite. We also find that for small magnetic Prandtl numbers {Pm} the lines of marginal instability scale with the Reynolds number and the Hartmann number. In the limit {Pm}\\to 0 the lines of marginal instability completely lie below the line for {Mm}=1 and for {Pm}\\to ∞ they completely lie above this line. For any finite value of {Pm}, however, the lines of marginal instability cross the line {Mm}=1, which separates slow from fast rotation. The minimum values of the field strength and the rotation rate that are needed for the instability (slightly) grow if the rotation law becomes flat. In this case, the electric current of the background field becomes so strong that the current-driven Tayler instability (which also exists without rotation) appears in the bifurcation map at low Hartmann numbers.

  6. Soliton modulation instability in fiber lasers

    Science.gov (United States)

    Tang, D. Y.; Zhao, L. M.; Wu, X.; Zhang, H.

    2009-08-01

    We report experimental evidence of soliton modulation instability in erbium-doped fiber lasers. An alternate type of spectral sideband generation was always experimentally observed on the soliton spectrum of the erbium-doped soliton fiber lasers when energy of the formed solitons reached beyond a certain threshold value. Following this spectral sideband generation, if the pump power of the lasers was further increased, either a new soliton would be formed or the existing solitons would experience dynamical instabilities, such as the period-doubling bifurcations or period-doubling route to chaos. We point out that the mechanism for this soliton spectral sideband generation is the modulation instability of the solitons in the lasers. We further show that, owing to the internal energy balance of a dissipative soliton, modulation instability itself does not destroy the stable soliton evolution in a laser cavity. It is the strong resonant wave coupling between the soliton and dispersive waves that leads to the dynamic instability of the solitons.

  7. Competition between Buneman and Langmuir Instabilities

    Institute of Scientific and Technical Information of China (English)

    GUO Jun; YU Bin

    2012-01-01

    The electron-ion beam instabilities are studied by one-dimensional electrostatic particle-in-cell simulation.The simulation results show that both the low-frequency Buneman mode and high-frequency Langmuir wave (LW) are excited in the nonlinear phase. The power of Buneman instability is stronger than that of the LW.The Buneman instability is firstly excited.Then the backward LW appears,which is probably excited by the particles trapped in the wave potential and moving opposite to the original beam direction.After some time,the forward LW can be found,which has a larger maximum frequency than that of the backward LW.With the decrease of the electron drift velocity,the instabilities become weaker; the LW appears to have almost equal intensities and becomes symmetric for forward and backward propagation directions. The LW can also heat the electron,so the relative drift speed cannot far exceed the electron thermal speed,which is not helpful to the development of Buneman instability.

  8. On the Chiral imbalance and Weibel Instabilities

    CERN Document Server

    Kumar, Avdhesh; Kaw, Predhiman K

    2016-01-01

    We study the chiral-imbalance and the Weibel instabilities in presence of the quantum anomaly using the Berry-curvature modified kinetic equation. We argue that in many realistic situations, e.g. relativistic heavy-ion collisions, both the instabilities can occur simultaneously. The Weibel instability depends on the momentum anisotropy parameter $\\xi$ and the angle ($\\theta_n$) between the propagation vector and the anisotropy direction. It has maximum growth rate at $\\theta_n=0$ while $\\theta_n=\\pi/2$ corresponds to a damping. On the other hand the pure chiral-imbalance instability occurs in an isotropic plasma and depends on difference between the chiral chemical potentials of right and left-handed particles. It is shown that when $\\theta_n=0$, only for a very small values of the anisotropic parameter $\\xi\\sim \\xi_c$, growth rates of the both instabilities are comparable. For the cases $\\xi_c<\\xi\\ll1$, $\\xi\\approx 1$ or $\\xi \\geq 1$ at $\\theta_n=0$, the Weibel modes dominate over the chiral-imbalance ins...

  9. Pressure-driven instabilities in astrophysical jets

    CERN Document Server

    Longaretti, Pierre-Yves

    2008-01-01

    Astrophysical jets are widely believed to be self-collimated by the hoop-stress due to the azimuthal component of their magnetic field. However this implies that the magnetic field is largely dominated by its azimuthal component in the outer jet region. In the fusion context, it is well-known that such configurations are highly unstable in static columns, leading to plasma disruption. It has long been pointed out that a similar outcome may follow for MHD jets, and the reasons preventing disruption are still not elucidated, although some progress has been accomplished in the recent years. In these notes, I review the present status of this open problem for pressure-driven instabilities, one of the two major sources of ideal MHD instability in static columns (the other one being current-driven instabilities). I first discuss in a heuristic way the origin of these instabilities. Magnetic resonances and magnetic shear are introduced, and their role in pressure-driven instabilities discussed in relation to Suydam'...

  10. Multiphase Instabilities in Explosive Dispersal of Particles

    Science.gov (United States)

    Rollin, Bertrand; Ouellet, Frederick; Annamalai, Subramanian; Balachandar, S. ``Bala''

    2015-11-01

    Explosive dispersal of particles is a complex multiphase phenomenon that can be observed in volcanic eruptions or in engineering applications such as multiphase explosives. As the layer of particles moves outward at high speed, it undergoes complex interactions with the blast-wave structure following the reaction of the energetic material. Particularly in this work, we are interested in the multiphase flow instabilities related to Richmyer-Meshkov (RM) and Rayleigh-Taylor (RM) instabilities (in the gas phase and particulate phase), which take place as the particle layer disperses. These types of instabilities are known to depend on initial conditions for a relatively long time of their evolution. Using a Eulerian-Lagrangian approach, we study the growth of these instabilities and their dependence on initial conditions related to the particulate phase - namely, (i) particle size, (ii) initial distribution, and (iii) mass ratio (particles to explosive). Additional complexities associated with compaction of the layer of particles are avoided here by limiting the simulations to modest initial volume fraction of particles. A detailed analysis of the initial conditions and its effects on multiphase RM/RT-like instabilities in the context of an explosive dispersal of particles is presented. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, Contract No. DE-NA0002378.

  11. Effects of electron temperature anisotropy on proton mirror instability evolution

    Science.gov (United States)

    Ahmadi, Narges; Germaschewski, Kai; Raeder, Joachim

    2016-06-01

    Proton mirror modes are large amplitude nonpropagating structures frequently observed in the magnetosheath. It has been suggested that electron temperature anisotropy can enhance the proton mirror instability growth rate while leaving the proton cyclotron instability largely unaffected, therefore causing the proton mirror instability to dominate the proton cyclotron instability in Earth's magnetosheath. Here we use particle-in-cell simulations to investigate the electron temperature anisotropy effects on proton mirror instability evolution. Contrary to the hypothesis, electron temperature anisotropy leads to excitement of the electron whistler instability. Our results show that the electron whistler instability grows much faster than the proton mirror instability and quickly consumes the electron-free energy so that there is no electron temperature anisotropy left to significantly impact the evolution of the proton mirror instability.

  12. Effects of electron temperature anisotropy on proton mirror instability evolution

    CERN Document Server

    Ahmadi, Narges; Raeder, Joachim

    2016-01-01

    Proton mirror modes are large amplitude nonpropagating structures frequently observed in the magnetosheath. It has been suggested that electron temperature anisotropy can enhance the proton mirror instability growth rate while leaving the proton cyclotron instability largely unaffected, therefore causing the proton mirror instability to dominate the proton cyclotron instability in Earth's magnetosheath. Here, we use particle-in-cell simulations to investigate the electron temperature anisotropy effects on proton mirror instability evolution. Contrary to the hypothesis, electron temperature anisotropy leads to excitement of the electron whistler instability. Our results show that the electron whistler instability grows much faster than the proton mirror instability and quickly consumes the electron free energy, so that there is no electron temperature anisotropy left to significantly impact the evolution of the proton mirror instability.

  13. Bernstein instability driven by thermal ring distribution

    Science.gov (United States)

    Yoon, Peter H.; Hadi, Fazal; Qamar, Anisa

    2014-07-01

    The classic Bernstein waves may be intimately related to banded emissions detected in laboratory plasmas, terrestrial, and other planetary magnetospheres. However, the customary discussion of the Bernstein wave is based upon isotropic thermal velocity distribution function. In order to understand how such waves can be excited, one needs an emission mechanism, i.e., an instability. In non-relativistic collision-less plasmas, the only known Bernstein wave instability is that associated with a cold perpendicular velocity ring distribution function. However, cold ring distribution is highly idealized. The present Brief Communication generalizes the cold ring distribution model to include thermal spread, so that the Bernstein-ring instability is described by a more realistic electron distribution function, with which the stabilization by thermal spread associated with the ring distribution is demonstrated. The present findings imply that the excitation of Bernstein waves requires a sufficiently high perpendicular velocity gradient associated with the electron distribution function.

  14. Pathways towards instability in financial networks

    Science.gov (United States)

    Bardoscia, Marco; Battiston, Stefano; Caccioli, Fabio; Caldarelli, Guido

    2017-02-01

    Following the financial crisis of 2007-2008, a deep analogy between the origins of instability in financial systems and complex ecosystems has been pointed out: in both cases, topological features of network structures influence how easily distress can spread within the system. However, in financial network models, the details of how financial institutions interact typically play a decisive role, and a general understanding of precisely how network topology creates instability remains lacking. Here we show how processes that are widely believed to stabilize the financial system, that is, market integration and diversification, can actually drive it towards instability, as they contribute to create cyclical structures which tend to amplify financial distress, thereby undermining systemic stability and making large crises more likely. This result holds irrespective of the details of how institutions interact, showing that policy-relevant analysis of the factors affecting financial stability can be carried out while abstracting away from such details.

  15. Modulational instability arising from collective Rayleigh scattering.

    Science.gov (United States)

    Robb, G R M; McNeil, B W J

    2003-02-01

    It is shown that under certain conditions a collection of dielectric Rayleigh particles suspended in a viscous medium and enclosed in a bidirectional ring cavity pumped by a strong laser field can produce a new modulational instability transverse to the wave-propagation direction. The source of the instability is collective Rayleigh scattering i.e., the spontaneous formation of periodic longitudinal particle-density modulations and a backscattered optical field. Using a linear stability analysis a dispersion relation is derived which determines the region of parameter space in which modulational instability of the backscattered field and the particle distribution occurs. In the linear regime the pump is modulationally stable. A numerical analysis is carried out to observe the dynamics of the interaction in the nonlinear regime. In the nonlinear regime the pump field also becomes modulationally unstable and strong pump depletion occurs.

  16. The Parker Instability in Disk Galaxies

    CERN Document Server

    Rodrigues, Luiz Felippe S; Shukurov, Anvar; Bushby, Paul J; Fletcher, Andrew

    2016-01-01

    We examine the evolution of the Parker instability in galactic disks using 3D numerical simulations. We consider a local Cartesian box section of a galactic disk, where gas, magnetic fields and cosmic rays are all initially in a magnetohydrostatic equilibrium. This is done for different choices of initial cosmic ray density and magnetic field. The growth rates and characteristic scales obtained from the models, as well as their dependences on the density of cosmic rays and magnetic fields, are in broad agreement with previous (linearized, ideal) analytical work. However, this non-ideal instability develops a multi-modal 3D structure, which cannot be quantitatively predicted from the earlier linearized studies. This 3D signature of the instability will be of importance in interpreting observations. As a preliminary step towards such interpretations, we calculate synthetic polarized intensity and Faraday rotation measure maps, and the associated structure functions of the latter, from our simulations; these sug...

  17. Rational Instability in the Natural Coalition Forming

    CERN Document Server

    Vinogradova, Galina

    2012-01-01

    We are investigating a paradigm of instability in coalition forming among countries, which indeed is intrinsic to any collection of individual groups or other social aggregations. Coalitions among countries are formed by the respective attraction or repulsion caused by the historical bond propensities between the countries, which produced an intricate circuit of bilateral bonds. Contradictory associations into coalitions occur due to the independent evolution of the bonds. Those coalitions tend to be unstable and break down frequently. The model extends some features of the physical theory of Spin Glasses. Within the frame of this model, the instability is viewed as a consequence of decentralized maximization processes searching for the best coalition allocations. In contrast to the existing literature, a rational instability is found to result from forecast rationality of countries. Using a general theoretical framework allowing to analyze the countries' decision making in coalition forming, we feature a sys...

  18. INSTABILITY OF GAS/LIQUID COAXIAL JET

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this article the emphasis was given to the discussion of the effects of diameter ratio and swirling on instability character for the gas/liquid coaxial jet used by Liao, et al.[1]. The results indicate that the finite diameter ratio markedly increases the maximum growth rate, the most unstable wavenumber, as well as the cutoff wavenumber. It implies that the finite diameter ratio will lead to the liquid jet breakup length shorter and the liquid drop size smaller. The effect of the swirling jets is much more complex: for the axisymmetric perturbation mode, the swirling enhances the flow stability, for helical perturbation, the dominant instability mode occurs at n<0. And it is found that in long wave region there exists a new kind of instability modes at n=1 that was not mentioned in Liao et al.'s article. For this new mode, there appears a dominated swirling ratio at which the flow has the maximum growth rate.

  19. Metal pad instabilities in liquid metal batteries

    Science.gov (United States)

    Zikanov, Oleg

    2016-11-01

    Strong variations between the electrical conductivities of electrolyte and metal layers in a liquid metal battery indicate the possibility of 'metal pad' instabilities. Deformations of the electrolyte-metal interfaces cause strong perturbations of electric currents, which, hypothetically, can generate Lorentz forces enhancing the deformations. We investigate this possibility using two models: a mechanical analogy and a two-dimensional linearized approximation. It is found that the battery is prone to instabilities of two types. One is similar to the sloshing-wave instability observed in the Hall-Héroult aluminum reduction cells. Another is new and related to the interactions of current perturbations with the azimuthal magnetic field induced by the base current. Financial support was provided by the U.S. National Science Foundation (Grant CBET 1435269).

  20. Magnetic interchange instability of accretion disks

    Science.gov (United States)

    Kaisig, M.; Tajima, T.; Lovelace, R. V. E.

    1992-01-01

    The nonlinear evolution of the magnetic interchange or buoyancy instability of a differentially rotating disk threaded by an ordered vertical magnetic field is investigated. A 2D ideal fluid in the equatorial plane of a central mass in the corotating frame of reference is considered as a model for the disk. If the rotation rate of the disk is Keplerian, the disk is found to be stable. If the vertical magnetic field is sufficiently strong, and the field strength decreases with distance from the central object, and thus the rotation of the disk deviates from Keplerian, if is found that an instability develops. The magnetic flux and disk matter expand outward in certain ranges of azimuth, while disk matter with less magnetic flux moves inward over the remaining range of azimuth, showing a characteristic development of an interchange instability.

  1. Mirror Instability in the Turbulent Solar Wind

    Science.gov (United States)

    Hellinger, Petr; Landi, Simone; Matteini, Lorenzo; Verdini, Andrea; Franci, Luca

    2017-04-01

    The relationship between a decaying strong turbulence and the mirror instability in a slowly expanding plasma is investigated using two-dimensional hybrid expanding box simulations. We impose an initial ambient magnetic field perpendicular to the simulation box, and we start with a spectrum of large-scale, linearly polarized, random-phase Alfvénic fluctuations that have energy equipartition between kinetic and magnetic fluctuations and a vanishing correlation between the two fields. A turbulent cascade rapidly develops, magnetic field fluctuations exhibit a Kolmogorov-like power-law spectrum at large scales and a steeper spectrum at sub-ion scales. The imposed expansion (taking a strictly transverse ambient magnetic field) leads to the generation of an important perpendicular proton temperature anisotropy that eventually drives the mirror instability. This instability generates large-amplitude, nonpropagating, compressible, pressure-balanced magnetic structures in a form of magnetic enhancements/humps that reduce the perpendicular temperature anisotropy.

  2. On stability and instability criteria for magnetohydrodynamics.

    Science.gov (United States)

    Friedlander, Susan; Vishik, Misha M.

    1995-06-01

    It is shown that for most, but not all, three-dimensional magnetohydrodynamic (MHD) equilibria the second variation of the energy is indefinite. Thus the class of such equilibria whose stability might be determined by the so-called Arnold criterion is very restricted. The converse question, namely conditions under which MHD equilibria will be unstable is considered in this paper. The following sufficient condition for linear instability in the Eulerian representation is presented: The maximal real part of the spectrum of the MHD equations linearized about an equilibrium state is bounded from below by the growth rate of an operator defined by a system of local partial differential equations (PDE). This instability criterion is applied to the case of axisymmetric toroidal equilibria. Sufficient conditions for instability, stronger than those previously known, are obtained for rotating MHD. (c) 1995 American Institute of Physics.

  3. Photofluid Instabilities of Hot Stellar Envelopes

    CERN Document Server

    Spiegel, E A; Spiegel, Edward A.; Tao, Louis

    1999-01-01

    Beginning from a relatively simple set of dynamical equations for a fluid permeated by a radiative field strong enough to produce significant forces, we find the structure of plane-parallel equilibria and study their stability to small acoustic disturbances. In doing this, we neglect viscous effects and complications of nongreyness. We find that acoutic instabilities occur over a wide range of conditions below the Eddington limit. This result is in line with findings reported twenty years ago but it contradicts some more recent reports of the absence of instabilities. We briefly attempt to identify the causes of the discrepancies and then close with a discussion of the possible astrophysical interest of such instabilities.

  4. Control and simulation of thermoacoustic instabilities

    Science.gov (United States)

    Poinsot, Thierry

    2014-11-01

    Combustion instabilities (CI), due to thermoacoustic coupling between acoustic waves and chemical reaction, constitute a major danger for all combustion systems. They can drive the system to unstable states where the whole combustor can oscillate, vibrate, quench or in extreme cases explode or burn. Such phenomena are commonly observed in the final phases of development programs, leading to major difficulties and significant additional costs. One of the most famous examples of combustion instabilities is the F1 engine of the Apollo program which required more than 1000 engine tests to obtain a stable regime satisfying all other constraints (performance, ignition, etc). CIs constitute one of the most challenging problems in fluid mechanics: they combine turbulence, acoustics, chemistry, unsteady two-phase flow in complex geometries. Since combustion instabilities have been identified (more than hundred years ago), the combustion community has followed two paths: (1) improve our understanding of the phenomena controlling stability to build engines which would be ``stable by design'' and (2) give up on a detailed understanding of mechanisms and add control systems either in open or closed loop devices to inhibit unstable modes. Of course, understanding phenomena driving combustion instabilities to suppress them would be the most satisfying approach but there is no fully reliable theory or numerical method today which can predict whether a combustor will be stable or not before it is fired. This talk will present an overview of combustion instabilities phenomenology before focusing on: (1) active control methods for combustion instabilities and (2) recent methods to predict unstable modes in combustors. These methods are based on recent Large Eddy Simulation codes for compressible reacting flows on HPC systems but we will also describe recent fully analytical methods which provide new insights into unstable modes in annular combustion chambers. Support: European

  5. Arthroscopic Findings in Anterior Shoulder Instability

    Science.gov (United States)

    Hantes, Michael; Raoulis, Vasilios

    2017-01-01

    Background: In the last years, basic research and arthroscopic surgery, have improved our understanding of shoulder anatomy and pathology. It is a fact that arthroscopic treatment of shoulder instability has evolved considerably over the past decades. The aim of this paper is to present the variety of pathologies that should be identified and treated during shoulder arthroscopy when dealing with anterior shoulder instability cases. Methods: A review of the current literature regarding arthroscopic shoulder anatomy, anatomic variants, and arthroscopic findings in anterior shoulder instability, is presented. In addition, correlation of arthroscopic findings with physical examination and advanced imaging (CT and MRI) in order to improve our understanding in anterior shoulder instability pathology is discussed. Results: Shoulder instability represents a broad spectrum of disease and a thorough understanding of the pathoanatomy is the key for a successful treatment of the unstable shoulder. Patients can have a variety of pathologies concomitant with a traditional Bankart lesion, such as injuries of the glenoid (bony Bankart), injuries of the glenoid labrum, superiorly (SLAP) or anteroinferiorly (e.g. anterior labroligamentous periosteal sleeve avulsion, and Perthes), capsular lesions (humeral avulsion of the glenohumeral ligament), and accompanying osseous-cartilage lesions (Hill-Sachs, glenolabral articular disruption). Shoulder arthroscopy allows for a detailed visualization and a dynamic examination of all anatomic structures, identification of pathologic findings, and treatment of all concomitant lesions. Conclusion: Surgeons must be well prepared and understanding the normal anatomy of the glenohumeral joint, including its anatomic variants to seek for the possible pathologic lesions in anterior shoulder instability during shoulder arthroscopy. Patient selection criteria, improved surgical techniques, and implants available have contributed to the enhancement of

  6. INTRINSIC INSTABILITY OF THE LATTICE BGK MODEL

    Institute of Scientific and Technical Information of China (English)

    熊鳌魁

    2002-01-01

    Based on the stability analysis with no linearization and expansion,it is argued that instability in the lattice BGK model is originated from the linearrelaxation hypothesis of collision in the model. The hypothesis stands up only whenthe deviation from the local equilibrium is weak. In this case the computation is abso-lutely stable for real fluids. But for flows of high Reynolds number, this hypothesis isviolated and then instability takes place physically. By performing a transformationa quantified stability criteria is put forward without those approximation. From thecriteria a sufficient condition for stability can be obtained and serve as an estimationof the limited Reynolds number as high as possible.

  7. Nonlinear evolution of whistler wave modulational instability

    DEFF Research Database (Denmark)

    Karpman, V.I.; Lynov, Jens-Peter; Michelsen, Poul;

    1995-01-01

    The nonlinear evolution of the modulational instability of whistler waves coupled to fast magnetosonic waves (FMS) and to slow magnetosonic waves (SMS) is investigated. Results from direct numerical solutions in two spatial dimensions agree with simplified results from a set of ordinary different......The nonlinear evolution of the modulational instability of whistler waves coupled to fast magnetosonic waves (FMS) and to slow magnetosonic waves (SMS) is investigated. Results from direct numerical solutions in two spatial dimensions agree with simplified results from a set of ordinary...

  8. Transient convective instabilities in directional solidification

    CERN Document Server

    Meca, Esteban

    2010-01-01

    We study the convective instability of the melt during the initial transient in a directional solidification experiment in a vertical configuration. We obtain analytically the dispersion relation, and perform an additional asymptotic expansion for large Rayleigh number that permits a simpler analytical analysis and a better numerical behavior. We find a transient instability, i.e. a regime in which the system destabilizes during the transient whereas the final unperturbed steady state is stable. This could be relevant to growth mode predictions in solidification.

  9. Relativistic Cyclotron Instability in Anisotropic Plasmas

    Science.gov (United States)

    López, Rodrigo A.; Moya, Pablo S.; Navarro, Roberto E.; Araneda, Jaime A.; Muñoz, Víctor; Viñas, Adolfo F.; Alejandro Valdivia, J.

    2016-11-01

    A sufficiently large temperature anisotropy can sometimes drive various types of electromagnetic plasma micro-instabilities, which can play an important role in the dynamics of relativistic pair plasmas in space, astrophysics, and laboratory environments. Here, we provide a detailed description of the cyclotron instability of parallel propagating electromagnetic waves in relativistic pair plasmas on the basis of a relativistic anisotropic distribution function. Using plasma kinetic theory and particle-in-cell simulations, we study the influence of the relativistic temperature and the temperature anisotropy on the collective and noncollective modes of these plasmas. Growth rates and dispersion curves from the linear theory show a good agreement with simulations results.

  10. Composition driven structural instability in perovskite ferroelectrics

    Directory of Open Access Journals (Sweden)

    Chao Xu

    2017-04-01

    Full Text Available Ferroelectric solid solutions usually exhibit enhanced functional properties at the morphotropic phase boundary separating two ferroelectric phases with different orientations of polarization. The underlying mechanism is generally associated with polarization rotational instability and the flattened free energy profile. In this work we show that the polarization extensional instability can also be induced at the morphotropic phase boundary beyond the reported polar-nonpolar phase boundary. The piezoelectricity enhanced by this mechanism exhibits excellent thermal stability, which helps to develop high performance piezoelectric materials with good temperature stability.

  11. White-light parametric instabilities in plasmas.

    Science.gov (United States)

    Santos, J E; Silva, L O; Bingham, R

    2007-06-08

    Parametric instabilities driven by partially coherent radiation in plasmas are described by a generalized statistical Wigner-Moyal set of equations, formally equivalent to the full wave equation, coupled to the plasma fluid equations. A generalized dispersion relation for stimulated Raman scattering driven by a partially coherent pump field is derived, revealing a growth rate dependence, with the coherence width sigma of the radiation field, scaling with 1/sigma for backscattering (three-wave process), and with 1/sigma1/2 for direct forward scattering (four-wave process). Our results demonstrate the possibility to control the growth rates of these instabilities by properly using broadband pump radiation fields.

  12. The Farley Instability: A Laboratory Test

    DEFF Research Database (Denmark)

    D'Angelo, N.; Pécseli, Hans; Petersen, P. I.

    1974-01-01

    An experiment is described that was performed in an alkali plasma (Cs) device in order to test the theory of the Farley instability. With υ E×B > Cs (the speed of sound) and νι ≳ ω cι (ν e ≪ ω ce ) wave excitation occurs, the waves traveling normal to the magnetic field B at the υ E×B speed....... The perturbations are strongly elongated along the B field lines, with λ∥ ≫ λ⊥. A comparison with theoretical predictions is given for the observed excitation conditions of the instability....

  13. Streaming instability in negative ion plasma

    Science.gov (United States)

    Kumar, Ajith; Mathew, Vincent

    2017-09-01

    The streaming instability in an unmagnetized negative ion plasma has been studied by computational and theoretical methods. A one dimensional electrostatic Particle In Cell Simulation and fluid dynamical description of negative ion plasma showed that, if the positive ions are having a relative streaming velocity, four different wave modes corresponding to Langmuir wave, fast and slow ion waves and ion acoustic waves are produced. Below a critical wave number, instead of two distinct fast and slow ion waves, we observed a coupled wave mode. The value of the critical wave number is strongly determined by the ion streaming velocity. The thermal velocities of electrons and ions influence the growth rate of instability.

  14. Theory of electrohydrodynamic instabilities in electrolytic cells

    Science.gov (United States)

    Bruinsma, R.; Alexander, S.

    1990-01-01

    The paper develops the theory of the hydrodynamic stability of an electrolytic cell as a function of the imposed electric current. A new electrohydrodynamic instability is encountered when the current is forced to exceed the Nernst limit. The convection is driven by the volume force exerted by the electric field on space charges in the electrolyte. This intrinsic instability is found to be easily masked by extrinsic convection sources such as gravity or stirring. A linear stability analysis is performed and a dimensionless number Le is derived whose value determines the convection pattern.

  15. Instabilities in numerical loop quantum cosmology

    CERN Document Server

    Rosen, J; Khanna, G; Jung, Jae-Hun; Khanna, Gaurav; Rosen, Jessica

    2006-01-01

    In this article we perform von Neumann analysis of the difference equations that arise as a result of loop quantum gravity being applied to models of cosmology and black holes. In particular, we study the numerical stability of Bianchi I LRS (symmetric and non-symmetric constraint) and Schwarzschild interior (symmetric constraint) models, and find that there exist domains over which there are instabilities, generically. We also present explicit evolutions of wave-packets in these models and clearly demonstrate the presence of these instabilities.

  16. Combustion instability mitigation by magnetic fields

    Science.gov (United States)

    Jocher, Agnes; Pitsch, Heinz; Gomez, Thomas; Bonnety, Jérôme; Legros, Guillaume

    2017-06-01

    The present interdisciplinary study combines electromagnetics and combustion to unveil an original and basic experiment displaying a spontaneous flame instability that is mitigated as the non-premixed sooting flame experiences a magnetic perturbation. This magnetic instability mitigation is reproduced by direct numerical simulations to be further elucidated by a flow stability analysis. A key role in the stabilization process is attributed to the momentum and thermochemistry coupling that the magnetic force, acting mainly on paramagnetic oxygen, contributes to sustain. The spatial local stability analysis based on the numerical simulations shows that the magnetic field tends to reduce the growth rates of small flame perturbations.

  17. An instability in neutron stars at birth

    Science.gov (United States)

    Burrows, Adam; Fryxell, Bruce A.

    1992-01-01

    Calculations with a two-dimensional hydrodynamic simulation show that a generic Raleigh-Taylor-like instability occurs in the mantles of nascent neutron stars, that it is possibly violent, and that the standard spherically symmetric models of neutron star birth and supernova explosion may be inadequate. Whether this 'convective' instability is pivotal to the supernova mechanism, pulsar nagnetic fields, or a host of other important issues that attend stellar collapse remains to be seen, but its existence promises to modify all questions concerning this most energetic of astronomical phenomena.

  18. Plasma instabilities in high electric fields

    DEFF Research Database (Denmark)

    Morawetz, K.; Jauho, Antti-Pekka

    1994-01-01

    We analyze nonequilibrium screening with nonequilibrium Green function techniques. By employing the generalized Kadanoff-Baym ansatz to relate the correlation function to the nonequilibrium distribution function, the latter of which is assumed to be a shifted Maxwellian, an analytically tractable...... expression is derived for the nonequilibrium dielectric function epsilon(K, omega). For certain values of momenta K and frequency omega, Imepsilon(K, omega) becomes negative, implying a plasma instability. This new instability exists only for strong electric fields, underlining its nonequilibrium origin....

  19. A fast beam-ion instability

    Energy Technology Data Exchange (ETDEWEB)

    Stupakov, G.V. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1996-08-01

    The ionization of residual gas by an electron beam in an accelerator generates ions that can resonantly couple to the beam through a wave propagating in the beam-ion system. Results of the study of a beam-ion instability are presented for a multi-bunch train taking into account the decoherence of ion oscillations due to the ion frequency spread and spatial variation of the ion frequency. It is shown that the combination of both effects can substantially reduce the growth rate of the instability. (author)

  20. Metal pad instabilities in liquid metal batteries

    CERN Document Server

    Zikanov, Oleg

    2015-01-01

    A mechanical analogy is used to analyze the interaction between the magnetic field, electric current and deformation of interfaces in liquid metal batteries. It is found that, during charging or discharging, a sufficiently large battery is prone to instabilities of two types. One is similar to the metal pad instability known for aluminum reduction cells. Another type is new. It is related to the destabilizing effect of the Lorentz force formed by the azimuthal magnetic field induced by the base current and the current perturbations caused by the local variations of the thickness of the electrolyte layer.

  1. Early Prevention Method for Power Systems Instability

    DEFF Research Database (Denmark)

    Dmitrova, Evgenia

    In the scope of this work, a method capable of fast identification of the proper countermeasure, that prevents emerging instability, has been developed. The focus is placed on the prevention of aperiodic small signal angular instability by means of manipulations applied to load nodes (nodes conta......’s evolution to self-curing systems, for which the human factor involved in control, will keep diminishing....... and defines which amount of countermeasure would be sufficient to bring a critical generator to the stable operation. The early prevention method is addressing the possibility of near real time analysis, utilizing computationally efficient algorithms. The method is providing efficient countermeasure matching...

  2. Managing incontinence due to detrusor instability.

    Science.gov (United States)

    2001-08-01

    Urinary incontinence affects around 3.5 million people of all ages in the UK. For many, incontinence severely restricts their routine activities and damages their quality of life and self-esteem. In about one-third of women sufferers, and around a half of all men with incontinence, the cause is detrusor instability. This condition is characterised by involuntary bladder contractions or pressure rises during bladder filling, which result in a strong or uncontrollable urge to pass urine and, often, incontinence. Here, we consider a primary care-based approach to managing urinary incontinence in adults, concentrating on the medical management of detrusor instability.

  3. THREE-BEAM INSTABILITY IN THE LHC*

    CERN Document Server

    Burov, A

    2013-01-01

    In the LHC, a transverse instability is regularly observed at 4TeV right after the beta-squeeze, when the beams are separated by about their ten transverse rms sizes [1-3], and only one of the two beams is seen as oscillating. So far only a single hypothesis is consistent with all the observations and basic concepts, one about a third beam - an electron cloud, generated by the two proton beams in the high-beta areas of the interaction regions. The instability results from a combined action of the cloud nonlinear focusing and impedance.

  4. Low energy ghosts and the Jeans' instability

    Science.gov (United States)

    Gümrükçüoǧlu, A. Emir; Mukohyama, Shinji; Sotiriou, Thomas P.

    2016-09-01

    We show that a massless canonical scalar field minimally coupled to general relativity can become a tachyonic ghost at low energies around a background in which the scalar's gradient is spacelike. By performing a canonical transformation we demonstrate that this low energy ghost can be recast, at the level of the action, in a form of a fluid that undergoes a Jeans-like instability affecting only modes with large wavelength. This illustrates that low energy tachyonic ghosts do not lead to a catastrophic quantum vacuum instability, unlike the usual high-energy ghost degrees of freedom.

  5. Efficiency Versus Instability in Plasma Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, Valeri [Fermilab; Burov, Alexey [Fermilab; Nagaitsev, Sergei [Fermilab

    2017-01-05

    Plasma wake-field acceleration in a strongly nonlinear (a.k.a. the blowout) regime is one of the main candidates for future high-energy colliders. For this case, we derive a universal efficiency-instability relation, between the power efficiency and the key instability parameter of the witness bunch. We also show that in order to stabilize the witness bunch in a regime with high power efficiency, the bunch needs to have high energy spread, which is not presently compatible with collider-quality beam properties. It is unclear how such limitations could be overcome for high-luminosity linear colliders.

  6. Dissipation-induced instabilities and symmetry

    Institute of Scientific and Technical Information of China (English)

    Oleg N. Kirillov; Ferdinand Verhulst

    2011-01-01

    The paradox of destabilization of a conservative or non-conservative system by small dissipation, or Ziegler's paradox (1952), has stimulated a growing interest in the sensitivity of reversible and Hamiltonian systems with respect to dissipative perturbations. Since the last decade it has been widely accepted that dissipation-induced instabilities are closely related to singularities arising on the stability boundary, associated with Whitney's umbrella. The first explanation of Ziegler's paradox was given (much earlier) by Oene Bottema in 1956. The aspects of the mechanics and geometry of dissipation-induced instabilities with an application to rotor dynamics are discussed.

  7. Stream instabilities in relativistically hot plasma

    CERN Document Server

    Shaisultanov, Rashid; Eichler, David

    2011-01-01

    The instabilities of relativistic ion beams in a relativistically hot electron background are derived for general propagation angles. It is shown that the Weibel instability in the direction perpendicular to the streaming direction is the fastest growing mode, and probably the first to appear, consistent with the aligned filaments that are seen in PIC simulations. Oblique, quasiperpendicular modes grow almost as fast, as the growth rate varies only moderately with angle, and they may distort or corrugate the filaments after the perpendicular mode saturates.

  8. Polyhedral (in-)stability of protein crystals

    Science.gov (United States)

    Nanev, Christo N.; Penkova, Anita N.

    2002-04-01

    The polyhedral (in-)stability of monoclinic hen-egg white lysozyme (HEWL) crystals, grown by means of PEG-6000, and that of orthorhombic trypsin crystals has been investigated experimentally. On the basis of a quantitative theoretical analysis, it is compared with the polyhedral (in-)stability of tetragonal HEWL and cubic ferritin crystals. The unambiguous conclusion is that the phenomenon is due to the diffusive supply of matter. This conclusion is also supported by the fact that the phenomenon has common features for both proteins and small molecular crystals.

  9. Methods for Simulating the Heavy Core Instability

    Directory of Open Access Journals (Sweden)

    Chang Philip

    2013-04-01

    Full Text Available Vortices have been proposed as the sites of planet formation, where dust collects and grows into planetesimals, the building blocks of planets. However, for very small dust particles that can be treated as a pressure-less fluid, we have recently discovered the “heavy core” instability, driven by the density gradient in the vortex. In order to understand the eventual outcome of this instability, we need to study its non-linear development. Here, we describe our ongoing work to develop highly accurate numerical models of a vortex with a density gradient embedded within a protoplanetary disk.

  10. Influence of Helium in Gravitational Instabilities

    Science.gov (United States)

    Corona-Galindo, M. G.; Cardona, O.; Klapp, J.

    1990-11-01

    RESUMEN. Hemos analizado los modos hid rod inamicos de un modelo de fluido de dos componentes (hidr6geno y helio), y hemos obtenido la condici6n de inestabilidad para masas mayores que 1.39 veces la bien conocida masa dejeans. ABSTRACT, We have analysed the hydrodynamical modes of a two component fluid model (hydrogen and helium), and we have obtained the instability condition for masses greater than 1.39 times the well-known Jeans mass. K words: COSMOLOGY - GRAVITATION - INSTABILITIES

  11. Selective hemiepiphyseodesis for patellar instability with associated genu valgum.

    Science.gov (United States)

    Kearney, Sean P; Mosca, Vincent S

    2015-03-01

    Patellar instability limits activity and promotes arthritis. Correcting genu valgum with selective hemiepiphyseodesis can treat patellar instability. We retrospectively reviewed 26 knees with patellar instability and associated genu valgum that underwent hemiepiphyseodesis. Average anatomic lateral distal femoral angle (aLDFA) significantly corrected. Symptoms improved in all patients. All competitive athletes returned to sports. One complication occurred. In genu valgum, the patella seeks an abnormal mechanical axis, resulting in patellar instability. By correcting the mechanical axis with hemiepiphyseodesis, patellar instability symptoms improve and patients return to sports. Complications are rare. Selective hemiepiphyseodesis is recommended when treating patellar instability with associated genu valgum.

  12. Genomic instability and cancer: an introduction

    Institute of Scientific and Technical Information of China (English)

    Zhiyuan Shen

    2011-01-01

    @@ Genomic instability as a major driving force of tumorigenesis.The ultimate goal of cell division for most non-cancerous somatic cells is to accurately duplicate the genome and then evenly divide the duplicated genome into the two daughter cells.This ensures that the daughter cells will have exactly the same genetic material as their parent cell.

  13. Final State of Gregory-Laflamme Instability

    CERN Document Server

    Lehner, Luis

    2011-01-01

    We describe the behavior of a perturbed 5-dimensional black string subject to the Gregory-Laflamme instability. We show that the horizon evolves in a self-similar manner, where at any moment in the late-time development of the instability the horizon can be described as a sequence of 3-dimensional spherical black holes of varying size, joined by black string segments of similar radius. As with the initial black string, each local string segment is itself unstable, and this fuels the self-similar cascade to (classically) arbitrarily small scales; in the process the horizon develops a fractal structure. In finite asymptotic time, the remaining string segments shrink to zero-size, yielding a naked singularity. Since no fine-tuning is required to excite the instability, this constitutes a generic violation of cosmic censorship. We further discuss how this behavior is related to satellite formation in low-viscosity fluid streams subject to the Rayleigh-Plateau instability, and estimate the fractal dimension of the...

  14. Instabilities of soft films on compliant substrates

    Science.gov (United States)

    Holland, M. A.; Li, B.; Feng, X. Q.; Kuhl, E.

    2017-01-01

    Instabilities in bilayered systems can generate a wide variety of patterns ranging from simple folds, wrinkles, and creases to complex checkerboards, hexagons, and herringbones. Physics-based theories traditionally model these systems as a thin film on a thick substrate under confined compression and assume that the film is orders of magnitude stiffer than the substrate. However, instability phenomena in soft films on soft substrates remain insufficiently understood. Here we show that soft bilayered systems are highly sensitive to the stiffness ratio, boundary conditions, and mode of compression. In a systematic analysis over a wide range of stiffness ratios, from 0.1 domain compression, substrate prestretch, and film growth, we observe significantly different instability characteristics in the low-stiffness-contrast regime, for β domain compression are unstable for a wide range of wrinkling modes, under film-only compression, the same systems display distinct wrinkling modes.Strikingly, these discrepancies disappear when using measures of effective strain, effective stiffness, and effective wavelength. Our study suggests that future instability studies should use these effective measures to standardize their findings. Our results have important applications in soft matter and living matter physics, where stiffness contrasts are low and small environmental changes can have large effects on morphogenesis, pattern tabselection, and the evolution of shape.

  15. Electronegative Plasma Instabilities in Industrial Pulsed Plasmas

    Science.gov (United States)

    Pribyl, Patrick; Hansen, Anders; Gekelman, Walter

    2016-10-01

    Electronegative gases that are important for industrial etch processes have a series of instabilities that occur at process relevant conditions. These have been studied since the 1990s, but are becoming a much more important today as plasma reactors are being pushed to produce ever finer features, and tight control of the etch process is becoming crucial. The experiments are being done in a plasma etch tool that closely simulates a working industrial device. ICP coils in different configurations are driven by a pulsed RF generators operating at 2-5 MHz. A computer controlled automated probe drive can access a volume above the substrate. The probe can be a Langmuir probe, a ``Bdot'' probe, or an emissive probe the latter used for more accurate determination of plasma potential. A microwave interferometer is available to measure line-averaged electron density. The negative ion instability is triggered depending upon the gas mix (Ar,SF6) , pressure and RF power. The instability can be ``burned through'' by rapidly pulsing the RF power. In this study we present measurements of plasma current and density distribution over the wafer before, after and during the rapid onset of the instability. Work suported by NSF-GOALI Award and done at the BAPSF.

  16. Upstream and Downstream Influence in STBLI Instability

    Science.gov (United States)

    Martin, Pino; Priebe, Stephan; Helm, Clara

    2016-11-01

    Priebe and Martín (JFM, 2012) show that the low-frequency unsteadiness in shockwave and turbulent boundary layer interactions (STBLI) is governed by an inviscid instability. Priebe, Tu, Martín and Rowley (JFM, 2016) show that the instability is an inviscid centrifugal one, i.e Görtlerlike vortices. Previous works had given differing conclusions as to whether the low-frequency unsteadiness in STBLI is caused by an upstream or downstream mechanism. In this paper, we reconcile these opposite views and show that upstream and downstream correlations co-exist in the context of the nature of Görtler vortices. We find that the instability is similar to that in separated subsonic and laminar flows. Since the turbulence is modulated but passive to the global mode, the turbulent separated flows are amenable to linear global analysis. As such, the characteristic length and time scales, and the receptivity of the global mode might be determined, and low-order models that represent the low-frequency dynamics in STBLI might be developed. The centrifugal instability persists even under hypersonic conditions. This work is funded by the AFOSR Grant Number AF9550-15-1-0284 with Dr. Ivett Leyva.

  17. FLARE FLAME INSTABILITY AND BURNER COMBUSTION CONTROL

    OpenAIRE

    БОНДАРЕНКО А.В.; В. Э. Волков; Максимов, М. В.

    2014-01-01

    Research of the flare instability development and the laminar-to-turbulent transition for the flares was executed. It was proved that the effects of viscosity and compressibility have the stabilizing influence on the gas flame. The study of the individual flare stability makes the theoretical basis of the fuel burning technology in combustion chambers and for the burner combustion control.

  18. Genome organization, instabilities, stem cells, and cancer

    Directory of Open Access Journals (Sweden)

    Senthil Kumar Pazhanisamy

    2009-01-01

    Full Text Available It is now widely recognized that advances in exploring genome organization provide remarkable insights on the induction and progression of chromosome abnormalities. Much of what we know about how mutations evolve and consequently transform into genome instabilities has been characterized in the spatial organization context of chromatin. Nevertheless, many underlying concepts of impact of the chromatin organization on perpetuation of multiple mutations and on propagation of chromosomal aberrations remain to be investigated in detail. Genesis of genome instabilities from accumulation of multiple mutations that drive tumorigenesis is increasingly becoming a focal theme in cancer studies. This review focuses on structural alterations evolve to raise a variety of genome instabilities that are manifested at the nucleotide, gene or sub-chromosomal, and whole chromosome level of genome. Here we explore an underlying connection between genome instability and cancer in the light of genome architecture. This review is limited to studies directed towards spatial organizational aspects of origin and propagation of aberrations into genetically unstable tumors.

  19. Theory and Experiments on Chemical Instabilities.

    Science.gov (United States)

    1983-12-31

    following institutions and conferences: 1981 Jan. 8 X Reunion de Fisica Estadistica , Cocoyoc, Mexico, Resonances and Control Features Feb. 13 Michigan State...Aeronautics and Astronautics, Invited Remarks, Palo Alto, CA 1982 Feb. 25,26 Industrial Affiliates Program ": .’ Hydrodynamic and Chemical Instabilities

  20. Laboratory experiments on arc deflection and instability

    Energy Technology Data Exchange (ETDEWEB)

    Zweben, S.; Karasik, M.

    2000-03-21

    This article describes experiments on arc deflection instability carried out during the past few years at the Princeton University Plasma Physics Laboratory (PPPL). The approach has been that of plasma physicists interested in arcs, but they believe these results may be useful to engineers who are responsible for controlling arc behavior in large electric steel furnaces.

  1. Pattern formation - Instabilities in sand ripples

    DEFF Research Database (Denmark)

    Hansen, J. L.; v. Hecke, M.; Haaning, A.

    2001-01-01

    Sand ripples are seen below shallow wavy water and are formed whenever water oscillates over a bed of sand. Here we analyse the instabilities that can upset this perfect patterning when the ripples are subjected to large changes in driving amplitude or frequency, causing them to deform both...

  2. Nonlinear parametric instability of wind turbine wings

    DEFF Research Database (Denmark)

    Larsen, Jesper Winther; Nielsen, Søren R.K.

    2006-01-01

    Nonlinear rotor dynamic is characterized by parametric excitation of both linear and nonlinear terms caused by centrifugal and Coriolis forces when formulated in a moving frame of reference. Assuming harmonically varying support point motions from the tower, the nonlinear parametric instability...

  3. Rossby Wave Instability of Keplerian Accretion Disks

    CERN Document Server

    Lovelace, R V E; Colgate, S A; Nelson, A F

    1999-01-01

    We find a linear instability of non-axisymmetric Rossby waves in a thin non-magnetized Keplerian disk when there is a local maximum in the radial profile of a key function ${\\cal L}(r) \\equiv {\\cal F}(r) S^{2/\\Gamma}(r)$, where ${\\cal F}^{-1} = \\hat {\\bf z}\\cdot ({\\bf \

  4. Perception and self-organised instability

    Directory of Open Access Journals (Sweden)

    Karl eFriston

    2012-07-01

    Full Text Available This paper considers state-dependent dynamics that mediate perception in the brain. In particular, it considers the formal basis of self-organised instabilities that enable perceptual transitions during Bayes-optimal perception. The basic phenomena we consider are perceptual transitions that lead to conscious ignition (Dehaene & Changeux, 2011 and how they depend on dynamical instabilities that underlie chaotic itinerancy (Tsuda, 2001; Breakspear, 2001 and self-organised criticality (Shew, Yang, Yu, Roy, & Plenz, 2011; Plenz & Thiagarajan, 2007; Beggs & Plenz, 2003. Our approach is based on a dynamical formulation of perception as approximate Bayesian inference, in terms of variational free energy minimisation. This formulation suggests that perception has an inherent tendency to induce dynamical instabilities (critical slowing that enable the brain to respond sensitively to sensory perturbations. We briefly review the dynamics of perception, in terms of generalised Bayesian filtering and free energy minimisation, present a formal conjecture about self-organised instability and then test this conjecture, using neuronal (numerical simulations of perceptual categorisation.

  5. Surface instabilities during straining of anisotropic materials

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang; Richelsen, Ann Bettina

    2006-01-01

    The development of instabilities in traction-free surfaces is investigated numerically using a unit cell model. Full finite strain analyses are conducted using isotropic as well as anisotropic yield criteria and both plane strain tension and compression are considered. In the load range of tension...

  6. Kinetic Simulations of Rayleigh-Taylor Instabilities

    CERN Document Server

    Sagert, Irina; Colbry, Dirk; Howell, Jim; Staber, Alec; Strother, Terrance

    2014-01-01

    We report on an ongoing project to develop a large scale Direct Simulation Monte Carlo code. The code is primarily aimed towards applications in astrophysics such as simulations of core-collapse supernovae. It has been tested on shock wave phenomena in the continuum limit and for matter out of equilibrium. In the current work we focus on the study of fluid instabilities. Like shock waves these are routinely used as test-cases for hydrodynamic codes and are discussed to play an important role in the explosion mechanism of core-collapse supernovae. As a first test we study the evolution of a single-mode Rayleigh-Taylor instability at the interface of a light and a heavy fluid in the presence of a gravitational acceleration. To suppress small-wavelength instabilities caused by the irregularity in the separation layer we use a large particle mean free path. The latter leads to the development of a diffusion layer as particles propagate from one fluid into the other. For small amplitudes, when the instability is i...

  7. Mechanisms of cadmium induced genomic instability

    Energy Technology Data Exchange (ETDEWEB)

    Filipic, Metka, E-mail: metka.filipic@nib.si [National Institute of Biology, Department for Genetic Toxicology and Cancer Biology, Ljubljana (Slovenia)

    2012-05-01

    Cadmium is an ubiquitous environmental contaminant that represents hazard to humans and wildlife. It is found in the air, soil and water and, due to its extremely long half-life, accumulates in plants and animals. The main source of cadmium exposure for non-smoking human population is food. Cadmium is primarily toxic to the kidney, but has been also classified as carcinogenic to humans by several regulatory agencies. Current evidence suggests that exposure to cadmium induces genomic instability through complex and multifactorial mechanisms. Cadmium dose not induce direct DNA damage, however it induces increase in reactive oxygen species (ROS) formation, which in turn induce DNA damage and can also interfere with cell signalling. More important seems to be cadmium interaction with DNA repair mechanisms, cell cycle checkpoints and apoptosis as well as with epigenetic mechanisms of gene expression control. Cadmium mediated inhibition of DNA repair mechanisms and apoptosis leads to accumulation of cells with unrepaired DNA damage, which in turn increases the mutation rate and thus genomic instability. This increases the probability of developing not only cancer but also other diseases associated with genomic instability. In the in vitro experiments cadmium induced effects leading to genomic instability have been observed at low concentrations that were comparable to those observed in target organs and tissues of humans that were non-occupationally exposed to cadmium. Therefore, further studies aiming to clarify the relevance of these observations for human health risks due to cadmium exposure are needed.

  8. Mix and hydrodynamic instabilities on NIF

    Science.gov (United States)

    Smalyuk, V. A.; Robey, H. F.; Casey, D. T.; Clark, D. S.; Döppner, T.; Haan, S. W.; Hammel, B. A.; MacPhee, A. G.; Martinez, D.; Milovich, J. L.; Peterson, J. L.; Pickworth, L.; Pino, J. E.; Raman, K.; Tipton, R.; Weber, C. R.; Baker, K. L.; Bachmann, B.; Berzak Hopkins, L. F.; Bond, E.; Caggiano, J. A.; Callahan, D. A.; Celliers, P. M.; Cerjan, C.; Dixit, S. N.; Edwards, M. J.; Felker, S.; Field, J. E.; Fittinghoff, D. N.; Gharibyan, N.; Grim, G. P.; Hamza, A. V.; Hatarik, R.; Hohenberger, M.; Hsing, W. W.; Hurricane, O. A.; Jancaitis, K. S.; Jones, O. S.; Khan, S.; Kroll, J. J.; Lafortune, K. N.; Landen, O. L.; Ma, T.; MacGowan, B. J.; Masse, L.; Moore, A. S.; Nagel, S. R.; Nikroo, A.; Pak, A.; Patel, P. K.; Remington, B. A.; Sayre, D. B.; Spears, B. K.; Stadermann, M.; Tommasini, R.; Widmayer, C. C.; Yeamans, C. B.; Crippen, J.; Farrell, M.; Giraldez, E.; Rice, N.; Wilde, C. H.; Volegov, P. L.; Gatu Johnson, M.

    2017-06-01

    Several new platforms have been developed to experimentally measure hydrodynamic instabilities in all phases of indirect-drive, inertial confinement fusion implosions on National Ignition Facility. At the ablation front, instability growth of pre-imposed modulations was measured with a face-on, x-ray radiography platform in the linear regime using the Hydrodynamic Growth Radiography (HGR) platform. Modulation growth of "native roughness" modulations and engineering features (fill tubes and capsule support membranes) were measured in conditions relevant to layered DT implosions. A new experimental platform was developed to measure instability growth at the ablator-ice interface. In the deceleration phase of implosions, several experimental platforms were developed to measure both low-mode asymmetries and high-mode perturbations near peak compression with x-ray and nuclear techniques. In one innovative technique, the self-emission from the hot spot was enhanced with argon dopant to "self-backlight" the shell in-flight. To stabilize instability growth, new "adiabat-shaping" techniques were developed using the HGR platform and applied in layered DT implosions.

  9. On cavitation instabilities with interacting voids

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2012-01-01

    voids so far apart that the radius of the plastic zone around each void is less than 1% of the current spacing between the voids, can still affect each others at the occurrence of a cavitation instability such that one void stops growing while the other grows in an unstable manner. On the other hand...

  10. Instabilities in power law gradient hardening materials

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Tvergaard, Viggo

    2005-01-01

    Tension and compression instabilities are investigated for specimens with dimensions in the micron range. A finite strain generalization of a higher order strain gradient plasticity theory is implemented in a finite element scheme capable of modeling power law hardening materials. Effects...

  11. Study of Fast Instability in Fermilab Recycler

    Energy Technology Data Exchange (ETDEWEB)

    Antipov, Sergey [Chicago U.; Adamson, Philip [Fermilab; Nagaitsev, Sergei [Fermilab; Yang, Ming-Jen [Fermilab

    2016-06-01

    One of the factors which may limit the intensity in the Fermilab Recycler is a fast transverse instability. It develops within a hundred turns and, in certain conditions, may lead to a beam loss. Various peculiar features of the instability: its occurrence only above a certain intensity threshold, and only in horizontal plane, as well as the rate of the instability, suggest that its cause is electron cloud. We studied the phenomena by observing the dynamics of stable and unstable beam. We found that beam motion can be stabilized by a clearing bunch, which confirms the electron cloud nature of the instability. The findings suggest electron cloud trapping in Recycler combined function mag-nets. Bunch-by-bunch measurements of betatron tune show a tune shift towards the end of the bunch train and allow the estimation of the density of electron cloud and the rate of its build-up. The experimental results are in agreement with numerical simulations of electron cloud build-up and its interaction with the beam.

  12. Modelling Fluidelastic Instability Forces in Tube Arrays

    Science.gov (United States)

    Anderson, J. Burns

    Historically, heat exchangers have been among the most failure prone components in nuclear power plants. Most of these failures are due to tube failures as a result of corrosion, fatigue and fretting wear. Fatigue and fretting wear are a result of flow induced vibration through turbulent buffeting and fluidelastic instability mechanisms. Fluidelastic instability is by far the most important and complex mechanism. This research deals with modelling fluidelastic instability and the resulting tube response. The proposed time domain model uses the concept of a flow cell (Hassan & Hayder [16]) to represent the complex flow field inside a shell and tube heat exchanger and accounts for temporal variations in the flow separation points as a result of tube motion. The fluidelastic forces are determined by predicting the attachment lengths. The predicted forces are used to simulate the response of a single flexible tube inside a shell and tube heat exchanger. It was found that accounting for temporal variations in the separation points predicted lower critical flow velocities, than that of fixed attachment and separation points. Once unstable a phase lag is predicted between the fluidelastic forces and tube response. It was determined that the predicted critical flow velocities agreed well with available experimental data. The developed model represents an important step towards a realistic fluidelastic instability model which can be used to design the new generation nuclear steam generators.

  13. Modulational instability in periodic quadratic nonlinear materials

    DEFF Research Database (Denmark)

    Corney, Joel Frederick; Bang, Ole

    2001-01-01

    We investigate the modulational instability of plane waves in quadratic nonlinear materials with linear and nonlinear quasi-phase-matching gratings. Exact Floquet calculations, confirmed by numerical simulations, show that the periodicity can drastically alter the gain spectrum but never complete...

  14. Nonlinear parametric instability of wind turbine wings

    DEFF Research Database (Denmark)

    Larsen, Jesper Winther; Nielsen, Søren R.K.

    2006-01-01

    Nonlinear rotor dynamic is characterized by parametric excitation of both linear and nonlinear terms caused by centrifugal and Coriolis forces when formulated in a moving frame of reference. Assuming harmonically varying support point motions from the tower, the nonlinear parametric instability o...

  15. Longitudinal Single Bunch Instability Study on BEPCII

    CERN Document Server

    Dou, Wang; Zhe, Duan; Na, Wang; Li, Wang; Lin, Wang; Jie, Gao

    2013-01-01

    In order to study the single bunch longitudinal instability in BEPCII, experiments on the positron ring (BPR) for the bunch lengthening phenomenon were made. By analyzing the experimental data based on Gao's theory, the longitudinal loss factor for the bunch are obtained. Also, the total wake potential and the beam current threshold are estimated.

  16. Regional Educational Inequality and Political Instability.

    Science.gov (United States)

    Monchar, Philip Harris

    1981-01-01

    From a study of 46 nations over the period 1957 to 1973, it is argued that regional educational inequality indicates the presence of other regional social, political, and economic inequalities, and it is all of these factors together that generate feelings of relative deprivation and the pursuant political instability. (Author/SJL)

  17. Political instability and country risk : new evidence

    NARCIS (Netherlands)

    DeHaan, J; Siermann, CLJ; VanLubek, E

    1997-01-01

    This note presents new estimates of a probit model for the debt rescheduling, using a sample of 65 countries over the period 1984-93. Apart from economic variables, a whole range of indicators for political instability are included in the model as explanatory variables. It turns out, that none is si

  18. Fisher Information, Sustainability, Development and Political Instability

    Science.gov (United States)

    Fisher information is a measure of order inherent in the timer series data for any dynamic system. We have computed the Fisher Information for nation-states using the data from 1960 to 1997 from the State Instability Task Force. We find that nation-states fall into two categories...

  19. Collisionless shock waves mediated by Weibel Instability

    Science.gov (United States)

    Naseri, Neda; Ruan, Panpan; Zhang, Xi; Khudik, Vladimir; Shvets, Gennady

    2015-11-01

    Relativistic collisionless shocks are common events in astrophysical environments. They are thought to be responsible for generating ultra-high energy particles via the Fermi acceleration mechanism. It has been conjectured that the formation of collisionless shocks is mediated by the Weibel instability that takes place when two initially cold, unmagnetized plasma shells counter-propagate into each other with relativistic drift velocities. Using a PIC code, VLPL, which is modified to suppress numerical Cherenkov instabilities, we study the shock formation and evolution for asymmetric colliding shells with different densities in their own proper reference frame. Plasma instabilities in the region between the shock and the precursor are also investigated using a moving-window simulation that advances the computational domain at the shock's speed. This method helps both to save computation time and avoid severe numerical Cherenkov instabilities, and it allows us to study the shock evolution in a longer time period. Project is supported by US DOE grants DE-FG02-04ER41321 and DE-FG02-07ER54945.

  20. Nonlinear Kinetic Dynamics of Magnetized Weibel Instability

    CERN Document Server

    Palodhi, L; Pegoraro, F

    2010-01-01

    Kinetic numerical simulations of the evolution of the Weibel instability during the full nonlinear regime are presented. The formation of strong distortions in the electron distribution function resulting in formation of strong peaks in it and their influence on the resulting electrostatic waves are shown.