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Sample records for cihr stirs controversy

  1. Television's "Soap" Controversy.

    ERIC Educational Resources Information Center

    Stutzman, Brent

    The situation comedy, "Soap," television's first prime-time sex farce, stirred controversy months before its premiere, and subsequent pressure on advertisers forced the network to change the show's concept from an adult comedy to a "whodunit." This report summarizes the controversy, recounts reactions to the series, and lists the implications of…

  2. Teaching Controversy without Controversy

    ERIC Educational Resources Information Center

    Stiehm, Judith

    1976-01-01

    Discussion of "Sex, Power, and Politics" course at the University of Southern California in which the videotaping of class sessions is used to reduce classroom controversy while studying controversy. (ND)

  3. CIHR canadian HIV trials network HIV workshop: ethical research through community participation and strengthening scientific validity

    PubMed Central

    Mbuagbaw, Lawrence; Slogrove, Amy; Sas, Jacqueline; Kunda, John; Morfaw, Frederick; Mukonzo, Jackson; Thabane, Lehana

    2014-01-01

    The CIHR canadian HIV trials network mandate includes strengthening capacity to conduct and apply clinical research through training and mentoring initiatives of HIV researchers by building strong networks and partnerships on the African continent. At the17th International Conference on AIDS and Sexually Transmitted Infections in Africa (ICASA), the CTN facilitated a two-day workshop to address ethical issues in the conduct of HIV research, and career enhancing strategies for young African HIV researchers. Conference attendees were allowed to attend whichever session was of interest to them. We report on the topics covered, readings shared and participants’ evaluation of the workshop. The scientific aspects of ethical research in HIV and career enhancement strategies are relevant issues to conference attendees. PMID:25667706

  4. GAO Report on Voc Ed Stirs Controversy

    ERIC Educational Resources Information Center

    Rabben, Kenneth J.

    1975-01-01

    The article is intended to inform readers of the contents of the General Accounting Office report on the failure of vocational education in seven States and to present responses from Washington-based vocational education personnel. Included are the congressional committee review findings and recommendations based on the audit. (BP)

  5. Circumcision controversies.

    PubMed

    Pinto, Kirk

    2012-08-01

    Despite its long history and common practice, circumcision remains a controversial procedure. This article reviews the history of this operation, examines the controversy that surrounds it, and emphasizes the performing practitioner's responsibility to the patient and his family in guiding them through the complicated decision making surrounding newborn circumcision. PMID:22857844

  6. Plutonium controversy

    SciTech Connect

    Richmond, C.R.

    1980-01-01

    The toxicity of plutonium is discussed, particularly in relation to controversies surrounding the setting of radiation protection standards. The sources, amounts of, and exposure pathways of plutonium are given and the public risk estimated. (ACR)

  7. Controversy Corner.

    ERIC Educational Resources Information Center

    Morris, John O.

    1986-01-01

    Argues that business communication should encourage the use of plain language while breaking down the ideas that it is unprofessional to write in clear prose and that it is safer to keep prose muddy so as to avoid controversy in an organization. (SRT)

  8. Exxon Valdez controversy revived

    SciTech Connect

    Not Available

    1993-04-26

    Four years after its occurrence rocked the petroleum industry and revitalized the US environmental movement, the Exxon Valdez tanker oil spill off Alaska continues to stir controversy. Conflicting reports abound over whether there is long term damage to the Prince William Sound ecosystem resulting from the March 24, 1989, spill. Government scientists at recent conferences disclosed studies they contend show long term, significant damage to the sound. Exxon this month launched a counteroffensive, disclosing results of studies it funded that it claims show no credible scientific evidence of long term damage. At the same time, the company blasted as flawed the government's data on assessing environmental damage to the sound and charged that test samples from the sound were mishandled. Meantime, Prince William Sound still shows lingering effects from the Exxon Valdez oil spill. But recovery has been so rapid that there is more controversy over how to use $900 million in natural resource recovery funds that Exxon paid than over how badly species are suffering. The paper describes Exxon's studies; faulty data; lingering damage; and an update on tanker safety.

  9. Facelift Controversies.

    PubMed

    Barrett, Dane M; Gerecci, Deniz; Wang, Tom D

    2016-08-01

    The primary purpose of the facelift is to restore the shape, volume, and contours of the youthful face. Facelift surgery has evolved over the years into multiple techniques to accomplish the same results. This article discusses the common controversies in facelift surgery and evaluates the best available evidence to guide surgical decision-making. In regard to the salient question of whether there is a "best" technique, the literature suggests that the options are generally equal in efficacy. This highlights the need for high-quality research with standardized preoperative assessment and evaluation of postoperative results to better assess outcomes. PMID:27400849

  10. Tennessee to Texas: Tracing the Evolution Controversy in Public Education

    ERIC Educational Resources Information Center

    Armenta, Tony; Lane, Kenneth E.

    2010-01-01

    Darwin's Theory of Evolution has stirred controversy since its inception. Public schools in the United States, pressed by special interest groups on both sides of the controversy, have struggled with how best to teach the theory, if at all. Court cases have dealt with whether states can ban the teaching of evolutionary theory, whether Creationism…

  11. Controversial therapies.

    PubMed

    Silver, L B

    1995-01-01

    Parents of children or adolescents with disabilities want the best treatment. They are vulnerable to any person who reports having a quick solution and possibly a cure. It is important that professionals be informed of these controversial therapies so that they can educate parents on what is known about these treatments. There is a relationship between brain function and nutrition, as well as between brain function and allergic reactions. These relations appear to be true for children with learning disabilities, attention deficit hyperactivity disorder, and other neurologic disorders. At this time, however, we do not understand these relationships and there are no known treatments based on these relationships that have been shown to be clinically successful. Professionals must educate parents on proposed new treatments. Parents need to ask themselves why this amazing approach is not used by everyone. If the person proposing the treatment tells them that "most professionals are biased and do not believe the findings because they are different from the traditional treatments," they should feel free to ask to see the data supporting the concept and the treatment. They should not accept without question popular books published by the person proposing the treatment or information provided in a flyer or on a television show by the person proposing the treatment. They should not put their son or daughter through something unproved and unlikely to help. PMID:7751563

  12. Ultrasonic Stir Welding

    NASA Technical Reports Server (NTRS)

    Nabors, Sammy

    2015-01-01

    NASA Marshall Space Flight Center (MSFC) developed Ultrasonic Stir Welding (USW) to join large pieces of very high-strength metals such as titanium and Inconel. USW, a solid-state weld process, improves current thermal stir welding processes by adding high-power ultrasonic (HPU) energy at 20 kHz frequency. The addition of ultrasonic energy significantly reduces axial, frictional, and shear forces; increases travel rates; and reduces wear on the stir rod, which results in extended stir rod life. The USW process decouples the heating, stirring, and forging elements found in the friction stir welding process allowing for independent control of each process element and, ultimately, greater process control and repeatability. Because of the independent control of USW process elements, closed-loop temperature control can be integrated into the system so that a constant weld nugget temperature can be maintained during welding.

  13. Science in Europe/Attack on Marxists Stirs Controversy

    ERIC Educational Resources Information Center

    Hawkes, Nigel

    1977-01-01

    Reports the use of Methylphenidate (Ritalin) as a treatment for hyperkinetic children shows a peak enhancement of learning at a dose of 0.3 milligrams per hilogram of body weight and a peak enhancement of behavior at a dose of 1.0 milligrams per kilogram. (SL)

  14. Friction stir welding tool

    DOEpatents

    Tolle; Charles R. , Clark; Denis E. , Barnes; Timothy A.

    2008-04-15

    A friction stir welding tool is described and which includes a shank portion; a shoulder portion which is releasably engageable with the shank portion; and a pin which is releasably engageable with the shoulder portion.

  15. Multiple test tubes stirred mechanically

    NASA Technical Reports Server (NTRS)

    Leon, H. J.; Strong, I. J.

    1965-01-01

    Mechanical device simultaneously stirs multiple test tubes under controlled laboratory conditions. The invention provides a variable stirring rate, minimal amount of contamination of tube contents, unattended and simple operation, and easy maintenance and cleaning.

  16. Friction stir weld tools

    NASA Technical Reports Server (NTRS)

    Carter, Robert W. (Inventor); Payton, Lewis N. (Inventor)

    2007-01-01

    A friction stir weld tool sleeve is supported by an underlying support pin. The pin material is preferably selected for toughness and fracture characteristics. The pin sleeve preferably has a geometry which employs the use of an interrupted thread, a plurality of flutes and/or eccentric path to provide greater flow through. Paddles have been found to assist in imparting friction and directing plastic metal during the welding process.

  17. Friction Stir Weld Tools

    NASA Technical Reports Server (NTRS)

    Carter, Robert W. (Inventor); Payton, Lewis N. (Inventor)

    2007-01-01

    A friction stir weld tool sleeve is supported by an underlying support pin. The pin material is preferably selected for toughness and fracture characteristics. The pin sleeve preferably has a geometry which employs the use of an interrupted thread, a plurality of flutes and/or eccentric path to provide greater flow through. Paddles have been found to assist in imparting friction and directing plastic metal during the welding process.

  18. Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C., Jr.

    2008-01-01

    Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and promises to be an important welding process for any industries where welds of optimal quality are demanded. This article provides an introduction to the FSW process. The chief concern is the physical effect of the tool on the weld metal: how weld seam bonding takes place, what kind of weld structure is generated, potential problems, possible defects for example, and implications for process parameters and tool design. Weld properties are determined by structure, and the structure of friction stir welds is determined by the weld metal flow field in the vicinity of the weld tool. Metal flow in the vicinity of the weld tool is explained through a simple kinematic flow model that decomposes the flow field into three basic component flows: a uniform translation, a rotating solid cylinder, and a ring vortex encircling the tool. The flow components, superposed to construct the flow model, can be related to particular aspects of weld process parameters and tool design; they provide a bridge to an understanding of a complex-at-first-glance weld structure. Torques and forces are also discussed. Some simple mathematical models of structural aspects, torques, and forces are included.

  19. Managing Controversial Meetings.

    ERIC Educational Resources Information Center

    Marchiony, Eve

    The "management of crisis," as opposed to crisis management," requires prior planning. Boards of education that habitually practice courtesy and have some knowledge of group dynamics do not create controversy by their own actions and will have fewer controversial meetings to manage. Policymakers should know ahead of time what issues are likely to…

  20. Orbital friction stir weld system

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor); Carter, Robert W. (Inventor)

    2001-01-01

    This invention is an apparatus for joining the ends of two cylindrical (i.e., pipe-shaped) sections together with a friction stir weld. The apparatus holds the two cylindrical sections together and provides back-side weld support as it makes a friction stir weld around the circumference of the joined ends.

  1. Stirring turbulence with turbulence

    NASA Astrophysics Data System (ADS)

    Cekli, Hakki Ergun; Joosten, René; van de Water, Willem

    2015-12-01

    We stir wind-tunnel turbulence with an active grid that consists of rods with attached vanes. The time-varying angle of these rods is controlled by random numbers. We study the response of turbulence on the statistical properties of these random numbers. The random numbers are generated by the Gledzer-Ohkitani-Yamada shell model, which is a simple dynamical model of turbulence that produces a velocity field displaying inertial-range scaling behavior. The range of scales can be adjusted by selection of shells. We find that the largest energy input and the smallest anisotropy are reached when the time scale of the random numbers matches that of the largest eddies of the wind-tunnel turbulence. A large mismatch of these times creates a highly intermittent random flow with interesting but quite anomalous statistics.

  2. The vibrating string controversy

    NASA Astrophysics Data System (ADS)

    Wheeler, Gerald F.; Crummett, William P.

    1987-01-01

    In the mid-1700s a debate raged between Jean d'Alembert, Leonhard Euler, and Daniel Bernoulli concerning the proper solution to the classical wave equation. This controversy was partially solved by Lagrange and, more conclusively, by Fourier (50 years later) and it provides an interesting case study for the role of mathematics in the modeling of physical phenomena. Of particular note in this debate, was the meaning of boundary conditions. The controversy is summarized from the point of view of this mathematical physics perspective.

  3. Thermal Stir Welds in Titanium

    NASA Astrophysics Data System (ADS)

    Fonda, Richard W.; Knipling, Keith E.; Pilchak, Adam L.

    2016-01-01

    Although conventional friction stir welding (FSW) has proven unsuccessful in joining thick sections of alpha and near-alpha titanium alloys, thermal stir welding, a variant of the FSW process in which an external heat source is used to preheat the workpiece, is demonstrated to be able to reliably join 12.3-mm-thick plates of CP titanium. This paper describes the microstructures and textures that develop in these thermal stir welds. The observed microstructure was used to reconstruct the high-temperature microstructure and texture present during the welding process and therefore reveal the genesis of the welding structures.

  4. The Choice Controversy.

    ERIC Educational Resources Information Center

    Cookson, Peter W., Jr., Ed.

    Issues in school choice--constitutionality, feasibility, equity, and educational productivity--are examined in this book. The controversy requires an ongoing analysis of the origins of the school-choice movement, the kinds of plans proposed and implemented, their educational and social consequences, and the philosophical assumptions underlying the…

  5. Controversy Over Student "Rights"

    ERIC Educational Resources Information Center

    Fields, Cheryl

    2005-01-01

    This article reports on the controversy over the "academic bill of rights" that is being pushed by conservative activist David Horowitz of the Center for the Study of Popular Culture. A committee in the Pennsylvania House of Representatives passed a resolution in July that reflects the concerns of this "bill," which has been batted around in state…

  6. The Accountability Controversy

    ERIC Educational Resources Information Center

    Glisson, Charles

    1975-01-01

    Author discusses accountability controversy concerning effectiveness of social services. Turem's mechanistic and Gruber's organic models of accountability are compared and an alternate open system model of organization is offered which combines positive aspects of Turem's and Gruber's models as well as adds other constructive elements to them. (SE)

  7. Controversies in dengue pathogenesis.

    PubMed

    Halstead, Scott B

    2012-05-01

    Research into the pathogenesis of dengue fever has exploded over the last half-century, with issues that were considered simple becoming more complex as additional data are found. This has led to the development of a number of controversies that are being studied across the globe and debated in the literature. In this paper, the following six controversies are analysed and, where possible, resolved: the 1997 World Health Organization (WHO) case definition of dengue haemorrhagic fever (DHF) is not useful; DHF is not significantly associated with secondary dengue infection; DHF results from infection with a 'virulent' dengue virus; DHF is owing to abnormal T-cell responses; DHF results from auto-immune responses; and DHF results from direct infection of endothelial cells. PMID:22668442

  8. Quasars, Redshifts and Controversies

    NASA Astrophysics Data System (ADS)

    Arp, Halton C.

    1988-09-01

    Introduction; 1. Distance of quasars; 2. The battle over statistics; 3. Galaxies visibly connected to quasars; 4. Certain galaxies with many quasars; 5. Distribution of quasars in space; 6. Galaxies with excess redshift; 7. Small excess redshifts, the local group of galaxies, and quantization of redshifts; 8. Correcting intrinsic redshifts and identifying hydrogen clouds within nearby groups of galaxies; 9. Ejection from galaxies; 10. The sociology of the controversy; 11. Interpretations; Glossary; Index.

  9. Controversies in vaccine mandates.

    PubMed

    Lantos, John D; Jackson, Mary Anne; Opel, Douglas J; Marcuse, Edgar K; Myers, Angela L; Connelly, Beverly L

    2010-03-01

    Policies that mandate immunization have always been controversial. The controversies take different forms in different contexts. For routine childhood immunizations, many parents have fears about both short- and long-term side effects. Parental worries change as the rate of vaccination in the community changes. When most children are vaccinated, parents worry more about side effects than they do about disease. Because of these worries, immunization rates go down. As immunization rates go down, disease rates go up, and parents worry less about side effects of vaccination and more about the complications of the diseases. Immunization rates then go up. For teenagers, controversies arise about the criteria that should guide policies that mandate, rather than merely recommend and encourage, certain immunizations. In particular, policy makers have questioned whether immunizations for human papillomavirus, or other diseases that are not contagious, should be required. For healthcare workers, debates have focused on the strength of institutional mandates. For years, experts have recommended that all healthcare workers be immunized against influenza. Immunizations for other infections including pertussis, measles, mumps, and hepatitis are encouraged but few hospitals have mandated such immunizations-instead, they rely on incentives and education. Pandemics present a different set of problems as people demand vaccines that are in short supply. These issues erupt into controversy on a regular basis. Physicians and policy makers must respond both in their individual practices and as advisory experts to national and state agencies. The articles in this volume will discuss the evolution of national immunization programs in these various settings. We will critically examine the role of vaccine mandates. We will discuss ways that practitioners and public health officials should deal with vaccine refusal. We will contrast responses of the population as a whole, within the

  10. Controversies in Screening Mammography.

    PubMed

    Swain, Monique; Jeudy, Myrlene; Pearlman, Mark D

    2016-06-01

    The utility and effectiveness of screening mammography in diagnosing breast cancer at earlier stages and reducing disease-specific mortality remain controversial especially as to when to start and stop routine mammographic screening, and whether mammograms should be performed annually or biennially in average-risk women. This manuscript will analyze the available moderate and high-quality data to analyze both the benefits (lives saved and life-years saved) and inconveniences/harms (additional views, extra biopsies/overdiagnosis, and overtreatment of ductal carcinoma in situ) of different mammography screening guidelines to assist the practitioner in counseling their patients in clinical practice. PMID:27101240

  11. Controversy at Love Canal.

    PubMed

    Paigen, B

    1982-06-01

    A cancer researcher reviews the events surrounding the toxic waste contamination at Love Canal with emphasis on the political nature of the controversy about its health impact. Antagonism between the community and the New York State Department of Health was fueled by several factors: the state's awareness that it gained from delay in investigation, disagreement on health problems to be studied, control over the information gathering process, silencing of opposition opinion, and the violation of norms of scientific behavior. The author calls for the establishment of standards of ethical behavior for scientists in such situations, standards for conflict resolution, and means of appeal for those injured. PMID:7107238

  12. Electrodynamic force law controversy.

    PubMed

    Graneau, P; Graneau, N

    2001-05-01

    Cavalleri et al. [Phys. Rev. E 52, 2505 (1998); Eur. J. Phys. 17, 205 (1996)] have attempted to resolve the electrodynamic force law controversy. This attempt to prove the validity of either the Ampère or Lorentz force law by theory and experiment has revealed only that the two are equivalent when predicting the force on part of a circuit due to the current in the complete circuit. However, in our analysis of internal stresses, only Ampère's force law agrees with experiment. PMID:11415053

  13. The controversy of Warthin's tumor

    SciTech Connect

    Chapnik, J.S.

    1983-06-01

    Warthin's tumor is controversial. This controversy is multifaceted and relates to all aspects of the tumor from its historical beginnings to its pathogenesis, investigations, and treatments. In this paper, an in depth study of Warthin's tumor has been made to help clarify these controversies.

  14. Stirring vortices with vorticity holes

    NASA Astrophysics Data System (ADS)

    Velasco Fuentes, Oscar

    2012-11-01

    A vorticity hole is a region with, in absolute value, significantly lower vorticity than its surroundings. Here we discuss the dynamics of a Rankine vortex with two equal circular holes. If a symmetric initial condition is assumed, the evolution depends on three parameters: the vorticity drop, the hole size and the distance between the holes. We computed the evolution with a contour-dynamics model and quantified the stirring of fluid particles using finite-time Lyapunov exponents and Melnikov's method. The vorticity holes evolve similarly to a pair of vortices in an otherwise quiescent fluid, although they are additionally affected by their interaction with the boundary of the Rankine vortex. The strongest stirring occurs when the holes interact elastically and then always in the center of the vortex. This result contradicts the generally accepted notion that vortices are regions of null to weak stirring.

  15. Melt Stirring by Horizontal Crucible Vibration

    NASA Technical Reports Server (NTRS)

    Wolf, M. F.; Elwell, D.; Feigelson, R. S.

    1985-01-01

    Horizontal vibration suggested as technique for more effective stirring of melts in crystal-growth apparatus. Vibrational technique may replace accelerated crucible rotation. Potential superiority of vibrational technique shown by preliminary experiments in which ink stirred into water.

  16. Phase characteristics of electromagnetic stirring

    SciTech Connect

    Fujisaki, Keisuke; Ueyama, Takatsugu; Takahashi, Keiichi; Satoh, Shouji

    1997-09-01

    Electromagnetic stirring is used at billet molds as well as at slab mold, to get high quality steel at continuous casting in steel making plant. In order to get the same electromagnetic force in each billet mold and thus the same quality, phase characteristics of electromagnetic stirring is investigated. From the calculation result, it is found that the relative phase at which the difference of the electromagnetic torque in each mold becomes the smallest is 0 or 240 deg. To apply the phase characteristics of the EMS to the quality control, the authors propose the dynamic phase control system by two inverters to get the high quality in the surface crack.

  17. Deformation During Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    White, Henry J.

    2002-01-01

    Friction Stir Welding (FSW) is a solid state welding process that exhibits characteristics similar to traditional metal cutting processes. The plastic deformation that occurs during friction stir welding is due to the superposition of three flow fields: a primary rotation of a radially symmetric solid plug of metal surrounding the pin tool, a secondary uniform translation, and a tertiary ring vortex flow (smoke rings) surrounding the tool. If the metal sticks to the tool, the plug surface extends down into the metal from the outer edge of the tool shoulder, decreases in diameter like a funnel, and closes up beneath the pin. Since its invention, ten years have gone by and still very little is known about the physics of the friction stir welding process. In this experiment, an H13 steel weld tool (shoulder diameter, 0.797 in; pin diameter, 0.312 in; and pin length, 0.2506 in) was used to weld three 0.255 in thick plates. The deformation behavior during friction stir welding was investigated by metallographically preparing a plan view sections of the weldment and taking Vickers hardness test in the key-hole region.

  18. The controversy over change.

    PubMed

    Brandon, A N

    1978-01-01

    The full impact of twentieth century technology upon medical libraries was first felt in the late 1950s and early 1960s with the introduction of electronic automation into library methodology. During those years, often the aura of technology for the sake of technology prevailed, and medical librarians did little to inform themselves of capabilities, potentialities, and limitations in relation to cost-effective library usage of automation. Likewise, currently microforms and audiovisuals are frequently acquired for their own sake instead of for their capacity to transmit messages in the most effective and comprehensive way possible. Controversy has raged and still rages over the pros and cons of applying modern technology to library procedures and over the coexistence of the printed page with electronic media. New systems and methodologies, machine or manual, must realistically be evaluated in terms of increased service output by the library to its clientele. Regardless of technological sophistication, any machine that does not significantly contribute to that specific aim has no place in a library. The tradition of the medical librarian has always been to collect, organize, store, and disseminate information in the most efficient manner that the media of the times have had to offer. PMID:75031

  19. Photoprotection: facts and controversies.

    PubMed

    Skotarczak, K; Osmola-Mańkowska, A; Lodyga, M; Polańska, A; Mazur, M; Adamski, Z

    2015-01-01

    Excessive exposure of the skin to sunlight can lead to many negative effects, such as sunburn, photoaging and skin cancer development. Pollution and stratospheric ozone layer depletion are factors that increase exposure to ultraviolet radiation. This work is an accurate summary of the current state of knowledge on broad-spectrum photoprotection. Avoiding the sun, skin protection through the use of protective clothing and protective filters are currently the most effective methods of sunscreen provided that they are suitably used. In addition, discussed are controversial issues such as the toxicity of zinc used in sunscreen preparations and the potential for deficiency of vitamin D3 in relation with the application of strict photoprotection. The study has also addressed issues concerning the most recent lines of research in the exploration of modern methods of photoprotection both local and systemic, such as with the use of photolyase or examination of various enzymes repairing damage after sun exposure, as well as the promising future in photoprotection technology. PMID:25635982

  20. Radon Treatment Controversy

    PubMed Central

    Zdrojewicz, Zygmunt; Strzelczyk, Jadwiga (Jodi)

    2006-01-01

    In spite of long traditions, treatments utilizing radon-rich air or water have not been unequivocally embraced by modern medicine. The objective of this work is to examine factors that contribute to this continuing controversy. While the exact mechanism of radon's effect on human body is not completely understood, recent advances in radiobiology offer new insights into biochemical processes occurring at low-level exposures to ionizing radiation. Medical evidence and patients' testimonials regarding effectiveness of radon spa treatments of various ailments, most notably rheumatoid arthritis are accumulating worldwide. They challenge the premise of the Linear-No-Threshold (LNT) theory that the dose-effect response is the same per unit dose regardless of the total dose. Historically, such inference overshadowed scientific inquiries into the low-dose region and lead to a popular belief that no amount of radiation can be good. Fortunately, the LNT theory, which lacks any scientific basis, did not remain unchallenged. As the reviewed literature suggests, a paradigm shift, reflected in the consideration of hormetic effects at low-doses, is gaining momentum in the scientific community worldwide. The impetus comes from significant evidence of adaptive and stimulatory effects of low-levels of radiation on human immune system. PMID:18648641

  1. The Continuing Valencian Language Controversy.

    ERIC Educational Resources Information Center

    Neugaard, Edward J.

    1995-01-01

    Controversy lingers regarding the name of the language spoken in the Spanish autonomous province of Valencia. Although the variety of Catalan spoken there has long been called both "Catalan" and "Valencian," recent controversy has become bitter and often surrounded by violence. Despite the debate, the language is in danger of dying out. (nine…

  2. Teen Addiction. Current Controversies Series.

    ERIC Educational Resources Information Center

    Winters, Paul A., Ed.

    The Current Controversies series explores social, political, and economic controversies that dominate the national and international scenes today from a variety of perspectives. Recent surveys have shown that, after years of decline, drug use among teenagers has increased during the 1990s, and that alcohol and tobacco use have remained…

  3. Examining Controversies in Adult Education.

    ERIC Educational Resources Information Center

    Kreitlow, Burton W.; And Others

    Controversies over adult education purposes, methods, audiences, and procedures are examined. After outlining a procedure for reviewing competing positions on controversial topics, the book pairs the contrasting views of two authors on each of 10 key issues facing adult education. Chapters cover: philosophies at issue (David L. Boggs); identifying…

  4. The Great School Bus Controversy.

    ERIC Educational Resources Information Center

    Mills, Nicolaus, Ed.

    This anthology attempts to put the great school bus controversy of the 1970's in perspective by providing a forum in which a series of widely differing views, backed by hard data, can be compared. The first section, "Background and Legal History," places the controversy in a perspective that predates the 1970's. One article focuses on the history…

  5. Friction Stir Process Mapping Methodology

    NASA Technical Reports Server (NTRS)

    Kooney, Alex; Bjorkman, Gerry; Russell, Carolyn; Smelser, Jerry (Technical Monitor)

    2002-01-01

    In FSW (friction stir welding), the weld process performance for a given weld joint configuration and tool setup is summarized on a 2-D plot of RPM vs. IPM. A process envelope is drawn within the map to identify the range of acceptable welds. The sweet spot is selected as the nominal weld schedule. The nominal weld schedule is characterized in the expected manufacturing environment. The nominal weld schedule in conjunction with process control ensures a consistent and predictable weld performance.

  6. Pulsed ultrasonic stir welding system

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    An ultrasonic stir welding system includes a welding head assembly having a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. During a welding operation, ultrasonic pulses are applied to the rod as it rotates about its longitudinal axis. The ultrasonic pulses are applied in such a way that they propagate parallel to the longitudinal axis of the rod.

  7. Flexible Friction Stir Joining Technology

    SciTech Connect

    Feng, Zhili; Lim, Yong Chae; Mahoney, Murray; Sanderson, Samuel; Larsen, Steve; Steel, Russel; Fleck, Dale; Fairchild, Doug P; Wasson, Andrew J; Babb, Jon; Higgins, Paul

    2015-07-23

    Reported herein is the final report on a U.S. Department of Energy (DOE) Advanced Manufacturing Office (AMO) project with industry cost-share that was jointly carried out by Oak Ridge National Laboratory (ORNL), ExxonMobil Upstream Research Company (ExxonMobil), and MegaStir Technologies (MegaStir). The project was aimed to advance the state of the art of friction stir welding (FSW) technology, a highly energy-efficient solid-state joining process, for field deployable, on-site fabrications of large, complex and thick-sectioned structures of high-performance and high-temperature materials. The technology innovations developed herein attempted to address two fundamental shortcomings of FSW: 1) the inability for on-site welding and 2) the inability to weld thick section steels, both of which have impeded widespread use of FSW in manufacturing. Through this work, major advance has been made toward transforming FSW technology from a “specialty” process to a mainstream materials joining technology to realize its pervasive energy, environmental, and economic benefits across industry.

  8. Stirring effect on kaolinite dissolution rate

    NASA Astrophysics Data System (ADS)

    Metz, Volker; Ganor, Jiwchar

    2001-10-01

    Experiments were carried out measuring kaolinite dissolution rates using stirred and nonstirred flow-through reactors at pHs 2 to 4 and temperatures of 25°C, 50°C, and 70°C. The results show an increase of kaolinite dissolution rate with increasing stirring speed. The stirring effect is reversible, i.e., as the stirring slows down the dissolution rate decreases. The effect of stirring speed on kaolinite dissolution rate is higher at 25°C than at 50°C and 70°C and at pH 4 than at pHs 2 and 3. It is suggested that fine kaolinite particles are formed as a result of stirring-induced spalling or abrasion of kaolinite. These very fine particles have an increased ratio of reactive surface area to specific surface area, which results in enhancement of kaolinite dissolution rate. A balance between production and dissolution of the fine particles explains both the reversibility and the temperature and pH dependence of the stirring effect. Since the stirring effect on kaolinite dissolution rate varies with temperature and pH, measurement of kinetic parameters such as activation energy may be influenced by stirring. Therefore, standard use of nonagitated reaction vessels for kinetic experiments of mineral dissolution and precipitation is recommended, at least for slow reactions that are surface controlled.

  9. The Science-Textbook Controversies

    ERIC Educational Resources Information Center

    Nelkin, Dorothy

    1976-01-01

    The discrepancies between science and creationism are reflected in curriculum controversies. Students should be free to choose which theory they like, according to the creationists who view Darwinian science as incompatible with absolute moral values. (DS)

  10. Necrotizing enterocolitis: controversies and challenges

    PubMed Central

    Zani, Augusto; Pierro, Agostino

    2015-01-01

    Necrotizing enterocolitis is a devastating intestinal disease that affects ~5% of preterm neonates. Despite advancements in neonatal care, mortality remains high (30–50%) and controversy still persists with regards to the most appropriate management of neonates with necrotizing enterocolitis. Herein, we review some controversial aspects regarding the epidemiology, imaging, medical and surgical management of necrotizing enterocolitis and we describe new emerging strategies for prevention and treatment. PMID:26918125

  11. Controversies in Parotid Defect Reconstruction.

    PubMed

    Tamplen, Matthew; Knott, P Daniel; Fritz, Michael A; Seth, Rahul

    2016-08-01

    Reconstruction of the parotid defect is a complex topic that encompasses restoration of both facial form and function. The reconstructive surgeon must consider facial contour, avoidance of Frey syndrome, skin coverage, tumor surveillance, potential adjuvant therapy, and facial reanimation when addressing parotid defects. With each defect there are several options within the reconstructive ladder, creating controversies regarding optimal management. This article describes surgical approaches to reconstruction of parotid defects, highlighting areas of controversy. PMID:27400838

  12. Pulsed ultrasonic stir welding method

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    A method of performing ultrasonic stir welding uses a welding head assembly to include a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. In the method, the rod is rotated about its longitudinal axis during a welding operation. During the welding operation, a series of on-off ultrasonic pulses are applied to the rod such that they propagate parallel to the rod's longitudinal axis. At least a pulse rate associated with the on-off ultrasonic pulses is controlled.

  13. Gimbaled-shoulder friction stir welding tool

    NASA Technical Reports Server (NTRS)

    Carter, Robert W. (Inventor); Lawless, Kirby G. (Inventor)

    2010-01-01

    A gimbaled-shoulder friction stir welding tool includes a pin and first and second annular shoulders coupled to the pin. At least one of the annular shoulders is coupled to the pin for gimbaled motion with respect thereto as the tool is rotated by a friction stir welding apparatus.

  14. Wiping Metal Transfer in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C., Jr.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Much evidence suggests that as the friction stir pin-tool moves along a weld seam the displacement of metal takes place by a wiping action at the surface of a plug of metal that rotates with the tool. The wiping model is explained and some consequences for the friction stir welding process are drawn.

  15. Sexual Orientation, Controversy, and Science.

    PubMed

    Bailey, J Michael; Vasey, Paul L; Diamond, Lisa M; Breedlove, S Marc; Vilain, Eric; Epprecht, Marc

    2016-09-01

    SummaryOngoing political controversies around the world exemplify a long-standing and widespread preoccupation with the acceptability of homosexuality. Nonheterosexual people have seen dramatic surges both in their rights and in positive public opinion in many Western countries. In contrast, in much of Africa, the Middle East, the Caribbean, Oceania, and parts of Asia, homosexual behavior remains illegal and severely punishable, with some countries retaining the death penalty for it. Political controversies about sexual orientation have often overlapped with scientific controversies. That is, participants on both sides of the sociopolitical debates have tended to believe that scientific findings-and scientific truths-about sexual orientation matter a great deal in making political decisions. The most contentious scientific issues have concerned the causes of sexual orientation-that is, why are some people heterosexual, others bisexual, and others homosexual? The actual relevance of these issues to social, political, and ethical decisions is often poorly justified, however. PMID:27113562

  16. Macrostructure of Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Aloor, S.; Nowak, B.; Vargas, R.; McClure, J. C.; Murr, L. E.; Nunes, A. C.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    This paper will discuss two of the well know large scale features of friction stir welds: the "onion rings" seen in transverse sections, and the striations on the surface of the work piece. It will be shown that the surface features (sometimes called "tool marks") are the result of irregularities on the rotating shoulder of the pin tool and disappear when the shoulder is polished. The "onion ring" structure seen in transverse cross sections is formed by parts of the "carousel", the zone of material adjacent to and rotating with the pin tool, that are shed off in each rotation. The relation between the carousel and the "ring vortex", a rotational flow extending both in and out of the carousel and resembling a smoke-ring with the hole centered on the pin tool, will be discussed.

  17. Friction Stir Welding and Processing

    SciTech Connect

    Hovanski, Yuri; Carsley, John; Clarke, Kester D.; Krajewski, Paul E.

    2015-05-01

    With nearly twenty years of international research and collaboration in friction stir welding (FSW) and processing industrial applications have spread into nearly every feasible market. Currently applications exist in aerospace, railway, automotive, personal computers, technology, marine, cutlery, construction, as well as several other markets. Implementation of FSW has demonstrated diverse opportunities ranging from enabling new materials to reducing the production costs of current welding technologies by enabling condensed packaging solutions for traditional fabrication and assembly. TMS has sponsored focused instruction and communication in this technology area for more than fifteen years, with leadership from the Shaping and Forming Committee, which organizes a biannual symposium each odd year at the annual meeting. A focused publication produced from each of these symposia now comprises eight volumes detailing the primary research and development activities in this area over the last two decades. The articles assembled herein focus on both recent developments and technology reviews of several key markets from international experts in this area.

  18. The Academic Controversy Technique: Towards Cooperative Debates

    ERIC Educational Resources Information Center

    Jacobs, George M.

    2010-01-01

    The purpose of this paper is to introduce and explain a cooperative learning technique, Academic Controversy (Johnson, Johnson, & Smith, 1996), also known as Cooperative Controversy, Structured Controversy and Structured Academic Controversy, that has potential for use in education and other areas, and has support in both research and theory.…

  19. The Controversy around Black History.

    ERIC Educational Resources Information Center

    Pitre, Abul; Ray, Ruth

    2002-01-01

    Controversy over black history began in 1926, when Carter G. Woodson introduced Negro history week, and has continued into the 21st century. Proponents of black history believe it promotes diversity, develops self-esteem, and corrects myths and stereotypes. Opponents argue it is dishonest, divisive, and lacks academic credibility and rigor.…

  20. Teacher Quality, Controversy, and NCLB

    ERIC Educational Resources Information Center

    Porter-Magee, Kathleen

    2004-01-01

    No Child Left Behind (NCLB)--the sweeping federal law that requires all schools that receive federal Title I dollars to be held strictly accountable for student outcomes--is the most discussed education reform effort in the past half century. One of the many controversial and vexing elements of the law, especially among teachers, teacher unions,…

  1. Women's Athletics: Coping with Controversy.

    ERIC Educational Resources Information Center

    Hoepner, Barbara J., Ed.

    This book is a collection of papers discussing controversial topics in women's athletics. Section one, "Overview--Women's Rights," includes articles on women's rights and equal opportunities in sports, the emergence of women in sports, and significant events in a century of American women's sports. Section two, "Women's Intercollegiate…

  2. Elementary 72 - The Great Controversy

    ERIC Educational Resources Information Center

    Allsop, R. T.

    1973-01-01

    Discusses the controversy about the discovery of element 72, involving Urbain's isolation of celtium, Dauvillier's reexamination of celtium samples, and Coster and Hevesy's announcement of the existence of hafnium. Indicates that the Copenhagen workers are finally accredited for the element discovery in their x-ray spectral studies. (CC)

  3. Embracing Controversy in the Classroom

    ERIC Educational Resources Information Center

    Cannard, Kelly

    2005-01-01

    Discussing controversial topics such as stem cell research is a great way for students to build scientific understanding, enhance communication skills, and develop an appreciation for civic decision making. Tackling a topic such as stem cells at the middle level, however, can be a challenge because most young adolescents see the world in black and…

  4. Engaging Students in Controversial Issues

    ERIC Educational Resources Information Center

    Malikow, Max

    2006-01-01

    A year ago, an upstate New York college withdrew a speaking invitation to Wade Churchill, a University of Colorado professor who had characterized 9/11 victims as "little Eichmanns." Churchill's portrayal of 9/11 victims as a mixture of conscious and unwitting participants in a systemic evil of Holocaust proportions indeed was controversial. The…

  5. Teaching Controversial Issues of Bioethics.

    ERIC Educational Resources Information Center

    Stronck, David R.

    Many teachers avoid controversial topics because they do not want to upset students or parents, do not know appropriate instructional strategies, and fail to recognize the importance of motivating students through placing science in its relevant context. An example is provided for use in a methods course for helping future high school teachers to…

  6. Eliminating Racism: Profiles in Controversy.

    ERIC Educational Resources Information Center

    Katz, Phyllis A., Ed.; Taylor, Dalmas A., Ed.

    Dialogue and research on racism since the mid-1970s have yielded increased controversy over the theories, foundation, and continued existence of racism. The chapters presented in this book provide various divergent views of what constitutes racism and frameworks for reducing it. The following chapters (and their authors) are included: (1)…

  7. Surveying Students about Controversial Subjects

    ERIC Educational Resources Information Center

    Soronen, Lisa E.

    2007-01-01

    Background: Because of school districts' interest in best serving the health needs of students, many choose to administer surveys addressing controversial topics. Administering such surveys in a voluntary and anonymous manner may help reduce conflict. Methods: This is a review of 2 recent federal court of appeals decisions regarding surveying…

  8. Darwinian Controversies: An Historiographical Recounting

    ERIC Educational Resources Information Center

    Depew, David J.

    2010-01-01

    This essay reviews key controversies in the history of the Darwinian research tradition: the Wilberforce-Huxley debate in 1860, early twentieth-century debates about the heritability of acquired characteristics and the consistency of Mendelian genetics with natural selection; the 1925 Scopes trial about teaching evolution; tensions about race,…

  9. The Satanic Ritual Abuse Controversy.

    ERIC Educational Resources Information Center

    Putnam, Frank W.

    1991-01-01

    The issues raised by Jonker and Jonker-Bakker and Young et al (EC 601 187-188) illustrate a major controversy dividing the child abuse community, the alleged existence of a conspiracy of satanic, ritual, sexual abuse of children. No evidence is found to support claims that large numbers of babies and children are being sacrificed or abused in…

  10. Controversial Curriculum? Ask the Community!

    ERIC Educational Resources Information Center

    Davis, William Jeffrey

    2009-01-01

    Involving communities in the process of curriculum development may not be novel, but it seems lacking with regard to controversial issues such as lessons on diverse family structures, homosexuality, and other special situations. Disparity in values and convictions can lead one person to support a decision, while another person might hold an…

  11. Controversial Science and the Media

    NASA Astrophysics Data System (ADS)

    Riordon, James

    2012-03-01

    The possibility that the OPERA collaboration has detected superluminal neutrinos was among the most controversial topics in physics news in decades, and one of the most widely covered stories in all of science in 2011. Word of the research initially reached journalists and the public prior to publication in peer-reviewed journals. Understandably, many physicists are concerned that the significance of controversial science may be exaggerated or distorted when news organizations report on science at such an early stage. I will offer an overview of the ways the story was promoted by the media relations personnel, and outline the rationales that motivate media relations efforts along with the associated benefits and drawbacks that can result. Finally, I will examine the accuracy and completeness of the superluminal neutrino news stories that ultimately were made available to the general public.

  12. Controversial Science and the Media

    NASA Astrophysics Data System (ADS)

    Riordon, James

    2012-02-01

    The possibility that the OPERA collaboration has detected superluminal neutrinos was among the most controversial topics in physics news in decades, and one of the most widely covered stories in all of science in 2011. Word of the research initially reached journalists and the public prior to publication in peer-reviewed journals. Understandably, many physicists are concerned that the significance of controversial science may be exaggerated or distorted when news organizations report on science at such an early stage. I will offer an overview of the ways the story was promoted by the media relations personnel, and outline the rationales that motivate media relations efforts along with the associated benefits and drawbacks that can result. Finally, I will examine the accuracy and completeness of the superluminal neutrino news stories that ultimately were made available to the general public.

  13. Controversies in Pediatric Perioperative Airways

    PubMed Central

    Klučka, Jozef; Štourač, Petr; Štoudek, Roman; Ťoukálková, Michaela; Harazim, Hana; Kosinová, Martina

    2015-01-01

    Pediatric airway management is a challenge in routine anesthesia practice. Any airway-related complication due to improper procedure can have catastrophic consequences in pediatric patients. The authors reviewed the current relevant literature using the following data bases: Google Scholar, PubMed, Medline (OVID SP), and Dynamed, and the following keywords: Airway/s, Children, Pediatric, Difficult Airways, and Controversies. From a summary of the data, we identified several controversies: difficult airway prediction, difficult airway management, cuffed versus uncuffed endotracheal tubes for securing pediatric airways, rapid sequence induction (RSI), laryngeal mask versus endotracheal tube, and extubation timing. The data show that pediatric anesthesia practice in perioperative airway management is currently lacking the strong evidence-based medicine (EBM) data that is available for adult subpopulations. A number of procedural steps in airway management are derived only from adult populations. However, the objective is the same irrespective of patient age: proper securing of the airway and oxygenation of the patient. PMID:26759809

  14. Gimballed Shoulders for Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Carter, Robert; Lawless, Kirby

    2008-01-01

    In a proposed improvement of tooling for friction stir welding, gimballed shoulders would supplant shoulders that, heretofore, have been fixedly aligned with pins. The proposal is especially relevant to self-reacting friction stir welding. Some definitions of terms, recapitulated from related prior NASA Tech Briefs articles, are prerequisite to a meaningful description of the proposed improvement. In friction stir welding, one uses a tool that includes (1) a rotating shoulder on top (or front) of the workpiece and (2) a pin that rotates with the shoulder and protrudes from the shoulder into the depth of the workpiece. In conventional friction stir welding, the main axial force exerted by the tool on the workpiece is reacted through a ridged backing anvil under (behind) the workpiece. When conventional friction stir welding is augmented with an auto-adjustable pin-tool (APT) capability, the depth of penetration of the pin into the workpiece is varied in real time by a position- or forcecontrol system that extends or retracts the pin as needed to obtain the desired effect. In self-reacting (also known as self-reacted) friction stir welding as practiced heretofore, there are two shoulders: one on top (or front) and one on the bottom (or back) of the workpiece. In this case, a threaded shaft protrudes from the tip of the pin to beyond the back surface of the workpiece. The back shoulder is held axially in place against tension by a nut on the threaded shaft. Both shoulders rotate with the pin and remain aligned coaxially with the pin. The main axial force exerted on the workpiece by the tool and front shoulder is reacted through the back shoulder and the threaded shaft into the friction-stir-welding machine head, so that a backing anvil is no longer needed. A key transmits torque between the bottom shoulder and the threaded shaft, so that the bottom shoulder rotates with the shaft. This concludes the prerequisite definitions of terms.

  15. Structured Controversy: A Case Study Strategy.

    ERIC Educational Resources Information Center

    Herreid, Clyde Freeman

    1996-01-01

    Introduces a dynamic form of the case instruction method that involves debate and compromise. Discusses two versions of structured controversy and presents an example of structured controversy that involves the use of DNA fingerprinting in forensic medicine. (JRH)

  16. Current controversies in infective endocarditis

    PubMed Central

    Cahill, Thomas J.; Prendergast, Bernard D.

    2015-01-01

    Infective endocarditis is a life-threatening disease caused by a focus of infection within the heart. For clinicians and scientists, it has been a moving target that has an evolving microbiology and a changing patient demographic. In the absence of an extensive evidence base to guide clinical practice, controversies abound. Here, we review three main areas of uncertainty: first, in prevention of infective endocarditis, including the role of antibiotic prophylaxis and strategies to reduce health care-associated bacteraemia; second, in diagnosis, specifically the use of multimodality imaging; third, we discuss the optimal timing of surgical intervention and the challenges posed by increasing rates of cardiac device infection. PMID:26918142

  17. Main controversies in breast cancer

    PubMed Central

    Zervoudis, Stephane; Iatrakis, George; Tomara, Eirini; Bothou, Anastasia; Papadopoulos, George; Tsakiris, George

    2014-01-01

    In this article, we have reviewed available evidence for diagnosis, treatment, and follow-up in female breast cancer (BC). Into daily clinical practice some controversies are occurred. Especially, in the diagnosis field, despite the fact that the optimal age in which screening mammography should start is a subject of intense controversy, there is a shift toward the beginning at the age of 40 although it is suggested that the net benefit is small for women aged 40 to 49 years. In addition, a promising tool in BC screening seems to be breast tomosynthesis. Other tools such as 3D ultrasound and shear wave elastography (SWE) are full of optimism in BC screening although ultrasonography is not yet a first-line screening method and there is insufficient evidence to recommend the systemic use of the SWE for BC screening. As for breast magnetic resonance imaging (MRI), even if it is useful in BC detection in women who have a strong family history of BC, it is not generally recommended as a screening tool. Moreover, based on the lack of randomized clinical trials showing a benefit of presurgical breast MRI in overall survival, it’s integration into breast surgical operations remains debatable. Interestingly, in contrast to fine needle aspiration, core biopsy has gained popularity in presurgical diagnosis. Furthermore, after conservative surgery in patients with positive sentinel lymph nodes, the recent tendency is the shift from axillary dissection to axillary conserving strategies. While the accuracy of sentinel lymph node after neoadjuvant chemotherapy and second BC surgery remains controversial, more time is needed for evaluation and for determining the optimal interval between the two surgeries. Additionally, in the decision between immediate or delayed breast reconstruction, there is a tendency in the immediate use. In the prevention of BC, the controversial issue between tamoxifen and raloxifene becomes clear with raloxifene be more profitable through the toxicities

  18. Controversies in Contemporary Facial Reanimation.

    PubMed

    Kim, Leslie; Byrne, Patrick J

    2016-08-01

    Facial palsy is a devastating condition with profound functional, aesthetic, and psychosocial implications. Although the complexity of facial expression and intricate synergy of facial mimetic muscles are difficult to restore, the goal of management is to reestablish facial symmetry and movement. Facial reanimation surgery requires an individualized treatment approach based on the cause, pattern, and duration of facial palsy while considering patient age, comorbidities, motivation, and goals. Contemporary reconstructive options include a spectrum of static and dynamic procedures. Controversies in the evaluation of patients with facial palsy, timing of intervention, and management decisions for dynamic smile reanimation are discussed. PMID:27400842

  19. Current controversies in childhood vaccination.

    PubMed

    Carrillo-Marquez, Maria; White, Lisa

    2013-01-01

    As pediatric practitioners, one of the contemporary challenges in providing medical care for children is the increasing proportion of vaccination refusal. This occurs in spite of the demonstrated individual and collective benefit and cost effectiveness of vaccination. Controversies regarding vaccine components and side effects have misled parents to believe that vaccines might be harmful based on inaccurate data from the Internet, celebrities, as well as misinterpreted and frankly bad science. This belief of vaccines being harmful has led to fear and decreased immunization rates in spite of sound scientific evidence supporting the safety of vaccines and their lack of association with autism, developmental disabilities or other medical disorders. Some parents also believe in alternative ways to avoid disease, often adhering to practices that have little foundation in the best of empiric science. It is not a coincidence that recent outbreaks of vaccine-preventable diseases, including measles and pertussis (whooping cough), have occurred in areas where vaccination has declined largely due to exemptors. This article intends to review some of the common vaccine myths and controversies and to serve as a resource to provide accurate information and references for busy practitioners and the families that we serve. PMID:23444591

  20. Infrared properties of an anisotropically stirred fluid

    NASA Technical Reports Server (NTRS)

    Rubinstein, Robert; Barton, J. Michael

    1987-01-01

    A renormalization group is developed for the Navier-Stokes equations driven by an anisotropically correlated random stirring force. The stirring force generates homogeneous turbulence with a preferred direction. The force correlation is the sum of a small anisotropic perturbation and an isotropic correlation chosen, so that the fixed point of renormalization group has a k exp -5/3 energy spectrum. Fixed points for the anisotropic correlation are found near this isotropic fixed point. Two types of anisotropy are analyzed. when the additional stirring is in the plane perpendicular to the preferred direction, the renormalized viscosity is increased. When it is aligned with the preferred direction, the viscosity is decreased. A possible connection with the inverse energy cascade of two-dimensional turbulence is discussed.

  1. Friction Stir Welding of Steel Alloys

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    The friction stir welding process has been developed primarily for the welding of aluminum alloys. Other higher melting allows such, as steels are much more difficult to join. Special attention must be given to pin tool material selection and welding techniques. This paper addresses the joining of steels and other high melting point materials using the friction stir welding process. Pin tool material and welding parameters will be presented. Mechanical properties of weldments will also be presented. Significance: There are many applications for the friction stir welding process other than low melting aluminum alloys. The FSW process can be expanded for use with high melting alloys in the pressure vessel, railroad and ship building industries.

  2. Tough on Crime? Pfizer and the CIHR

    PubMed Central

    Evans, Robert G.

    2010-01-01

    The appointment of Dr. Bernard Prigent, vice-president and medical director of Pfizer Canada, to the Governing Council of the Canadian Institutes of Health Research, outraged many Canadian health researchers. Pfizer has been a “habitual offender,” persistently engaging in illegal and corrupt marketing practices, bribing physicians and suppressing adverse trial results. Since 2002 the company and its subsidiaries have been assessed $3 billion in criminal convictions, civil penalties and jury awards. The $2.3-billion settlement in September 2009 – a month before Dr. Prigent's appointment – set a new record for both criminal fines and total penalties. A link with Pfizer might well advance the commercialization of Canadian research – unhindered by law or morality. Is that now the only mandate, Dr. Beaudet? PMID:21532766

  3. Study of stirred layers on 316L steel created by friction stir processing

    NASA Astrophysics Data System (ADS)

    Langlade, C.; Roman, A.; Schlegel, D.; Gete, E.; Folea, M.

    2014-08-01

    Nanostructured materials are known to exhibit attractive properties, especially in the mechanical field where high hardness is of great interest. The friction stir process (FSP) is a recent surface engineering technique derived from the friction stir welding method (FSW). In this study, the FSP of an 316L austenitic stainless steel has been evaluated. The treated layers have been characterized in terms of hardness and microstructure and these results have been related to the FSP operational parameters. The process has been analysed using a Response Surface Method (RSM) to enable the stirred layer thickness prediction.

  4. Contact dermatitis: facts and controversies.

    PubMed

    Wolf, Ronni; Orion, Edith; Ruocco, Eleonora; Baroni, Adone; Ruocco, Vincenzo

    2013-01-01

    The history of contact dermatitis (CD) is inseparable from the history of the patch test, and the patch test is inseparable from the pioneer in the field, Josef Jadassohn (1860-1936). Despite the fact that we have been diagnosing, treating, and investigating the condition for more than 100 years, there are still many unsolved questions and controversies, which show no signs of coming to an end in the foreseeable future. This contribution reviews and highlights some of the disagreements and discrepancies associated with CD. For example: • What is the real sensitizer in balsam of Peru, one of the most common allergens, and what, if any, is the value of a low-balsam diet? • Is benzalkonium chloride, which has well-known and undisputed irritant properties, a contact allergen as well? • Is cocamidopropyl betaine (CABP) a common contact allergen and what is the actual sensitizer in CABP allergy the molecule itself, or impurities, or intermediaries in its synthesis? • How can the significant differences in the prevalence of sensitization of formaldehyde (FA, a common cause of contact allergy) between the United States (8%-9%) and Europe (2%-3%) be explained? • What is the relationship between formaldehyde releasers (FRs) allergy and an FA allergy? Should we recommend that FA-allergic patients also avoid FRs, and, if so, to what extent? • What is the true frequency of lanolin allergy? This issue remains enigmatic despite the expenditure of thousands of dollars and the innumerable hours spent investigating this subject. • What is the basis behind the so-called "lanolin paradox"? This label was coined in 1996 and is still a matter of controversy. • Is there such a thing as systemic CD from nickel, and, if so, to what extent? Is there a cross-reactivity or concomitant sensitization between nickel and cobalt?These are some of the controversial problems discussed. We have selected the ones that we consider to be of special interest and importance to the

  5. Cholesterol confusion and statin controversy.

    PubMed

    DuBroff, Robert; de Lorgeril, Michel

    2015-07-26

    The role of blood cholesterol levels in coronary heart disease (CHD) and the true effect of cholesterol-lowering statin drugs are debatable. In particular, whether statins actually decrease cardiac mortality and increase life expectancy is controversial. Concurrently, the Mediterranean diet model has been shown to prolong life and reduce the risk of diabetes, cancer, and CHD. We herein review current data related to both statins and the Mediterranean diet. We conclude that the expectation that CHD could be prevented or eliminated by simply reducing cholesterol appears unfounded. On the contrary, we should acknowledge the inconsistencies of the cholesterol theory and recognize the proven benefits of a healthy lifestyle incorporating a Mediterranean diet to prevent CHD. PMID:26225201

  6. Cholesterol confusion and statin controversy

    PubMed Central

    DuBroff, Robert; de Lorgeril, Michel

    2015-01-01

    The role of blood cholesterol levels in coronary heart disease (CHD) and the true effect of cholesterol-lowering statin drugs are debatable. In particular, whether statins actually decrease cardiac mortality and increase life expectancy is controversial. Concurrently, the Mediterranean diet model has been shown to prolong life and reduce the risk of diabetes, cancer, and CHD. We herein review current data related to both statins and the Mediterranean diet. We conclude that the expectation that CHD could be prevented or eliminated by simply reducing cholesterol appears unfounded. On the contrary, we should acknowledge the inconsistencies of the cholesterol theory and recognize the proven benefits of a healthy lifestyle incorporating a Mediterranean diet to prevent CHD. PMID:26225201

  7. Subclinical hypothyroidism: Controversies to consensus

    PubMed Central

    Raza, Syed Abbas; Mahmood, Nasir

    2013-01-01

    Diagnoses of subclinicaal hypothyroidism (SCH) is biochemically made, when serum thyroid stimulating hormone (TSH) levels is elevated while free thyroid hormone levels are within normal reference range. SCH is diagnosed after excluding all other causes of elevated TSH levels. Symptoms of SCH may vary from being asymptomatic to having mild nonspecific symptoms. The risk of progression to overt hypothyroidism is related to number of factors including initial serum TSH concentration, presence of auto antibodies, family history and presence goiter. Various screening recommendations for thyroid function assessment are in practice. There are still controversies surrounding SCH and associated risk of various cardiovascular diseases (CVDs), pregnancy outcomes, neuropsychiatric issues, metabolic syndrome, and dyslipidemia. Consensus will require more large randomized clinical studies involving various age groups and medical condition, especially in developing countries. All these efforts will definitely improve our understanding of disease and ultimately patient outcomes. PMID:24910826

  8. Controversies Among the Hypertension Guidelines.

    PubMed

    Ripley, Toni L; Baumert, Mary

    2016-02-01

    Hypertension affects 80 million people in the United States. It remains poorly controlled, with only 54% of diagnosed patients treated to blood pressure targets. Hypertension management is complex in part due to the volume of antihypertensive agents, variable patient needs and responses, and inconsistent design and outcomes from clinical trials. Therefore, trustworthy clinical practice guidelines have a key role in hypertension management. The United States experienced a 10-year gap in publication of hypertension guidelines, followed by multiple guideline publications in 2013. These guidelines led to more controversy than clarity, as there was discordance among them. This review summarizes the guidelines and clinical statements influencing the current debate in order to facilitate appropriate application. PMID:26668216

  9. Darwinian Controversies: An Historiographical Recounting

    NASA Astrophysics Data System (ADS)

    Depew, David J.

    2010-05-01

    This essay reviews key controversies in the history of the Darwinian research tradition: the Wilberforce-Huxley debate in 1860, early twentieth-century debates about the heritability of acquired characteristics and the consistency of Mendelian genetics with natural selection; the 1925 Scopes trial about teaching evolution; tensions about race, culture, and eugenics at the 1959 centenary celebration Darwin’s Origin of Species; adaptationism and its critics in the Sociobiology debate of 1970s and, more recently, Evolutionary Psychology; and current disputes about Intelligent Design. These controversies, I argue, are etched into public memory because they occur at the emotionally charged boundaries between public-political, technical-scientific, and personal-religious spheres of discourse. Over most of them falls the shadow of eugenics. The main lesson is that the history of Darwinism cannot be told except by showing the mutual influence of the different norms of discourse that obtain in the personal, technical, and public spheres. Nor can evolutionary biology successfully be taught to citizens and citizens-to-be until the fractious intersections between spheres of discourse have been made explicit. In the course of showing why, I take rival evolutionary approaches to be dynamical historical research traditions rather than static theories. Accordingly, I distinguish Darwin’s version of Darwinism from its later transformations. I pay special attention to the role Darwin assigned to development in evolution, which was marginalized by twentieth-century population genetical Darwinism, but has recently resurfaced in new forms. I also show how the disputed phrases “survival of the fittest” and “social Darwinism” have shaped personal anxieties about “Darwinism,” have provoked public opposition to teaching evolution in public schools, and have cast a shadow over efforts to effectively communicate to the public largely successful technical efforts to make

  10. School-Meals Makeover Stirs the Pot

    ERIC Educational Resources Information Center

    Shah, Nirvi

    2011-01-01

    Proposed new federal rules governing the meals served to school children across the country each weekday are causing a stir among food industry groups, cafeteria managers, parents, and students. The skirmish is over the U.S. Department of Agriculture's efforts, prompted by the recent passage of the Healthy, Hunger-Free Kids Act, to rewrite the…

  11. Ferrous friction stir weld physical simulation

    NASA Astrophysics Data System (ADS)

    Norton, Seth Jason

    2006-04-01

    Traditional fusion welding processes have several drawbacks associated with the melting and solidification of metal. Weld defects associated with the solidification of molten metal may act as initiation sites for cracks. Segregation of alloying elements during solidification may cause local changes in resistance to corrosion. The high amount of heat required to produce the molten metal in the weld can produce distortion from the intended position on cooling. The heat from the electric arc commonly used to melt metal in fusion welds may also produce metal fumes which are a potential health hazard. Friction stir welding is one application which has the potential to make full thickness welds in a single pass, while eliminating fume, reducing distortion, and eliminating solidification defects. Currently the friction stir welding process is used in the aerospace industry on aluminum alloys. Interest in the process by industries which rely on iron and its alloys for structural material is increasing. While friction stir welding has been shown to be feasible with iron alloys, the understanding of friction stir welding process effects on these materials is in its infancy. This project was aimed to better that understanding by developing a procedure for physical simulation of friction stir welding. Friction stir weld material tracer experiments utilizing stainless steel markers were conducted with plates of ingot iron and HSLA-65. Markers of 0.0625" diameter 308 stainless steel worked well for tracing the end position of material moved by the friction stir welding tool. The markers did not produce measurable increases in the loading of the tool in the direction of travel. Markers composed of 0.25" diameter 304 stainless steel did not perform as well as the smaller markers and produced increased loads on the friction stir welding tool. The smaller markers showed that material is moved in a curved path around the tool and deposited behind the tool. Material near the surface

  12. Thermal Stir Welding: A New Solid State Welding Process

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey

    2003-01-01

    Thermal stir welding is a new welding process developed at NASA's Marshall Space Flight Center in Huntsville, AL. Thermal stir welding is similar to friction stir welding in that it joins similar or dissimilar materials without melting the parent material. However, unlike friction stir welding, the heating, stirring and forging elements of the process are all independent of each other and are separately controlled. Furthermore, the heating element of the process can be either a solid-state process (such as a thermal blanket, induction type process, etc), or, a fusion process (YG laser, plasma torch, etc.) The separation of the heating, stirring, forging elements of the process allows more degrees of freedom for greater process control. This paper introduces the mechanics of the thermal stir welding process. In addition, weld mechanical property data is presented for selected alloys as well as metallurgical analysis.

  13. Thermal Stir Welding: A New Solid State Welding Process

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    Thermal stir welding is a new welding process developed at NASA's Marshall Space Flight Center in Huntsville, AL. Thermal stir welding is similar to friction stir welding in that it joins similar or dissimilar materials without melting the parent material. However, unlike friction stir welding, the heating, stirring and forging elements of the process are all independent of each other and are separately controlled. Furthermore, the heating element of the process can be either a solid-state process (such as a thermal blanket, induction type process, etc), or, a fusion process (YG laser, plasma torch, etc.) The separation of the heating, stirring, forging elements of the process allows more degrees of freedom for greater process control. This paper introduces the mechanics of the thermal stir welding process. In addition, weld mechanical property data is presented for selected alloys as well as metallurgical analysis.

  14. Controversies in kidney paired donation.

    PubMed

    Gentry, Sommer E; Montgomery, Robert A; Segev, Dorry L

    2012-07-01

    Kidney paired donation represented 10% of living kidney donation in the United States in 2011. National registries around the world and several separate registries in the United States arrange paired donations, although with significant variations in their practices. Concerns about ethical considerations, clinical advisability, and the quantitative effectiveness of these approaches in paired donation result in these variations. For instance, although donor travel can be burdensome and might discourage paired donation, it was nearly universal until convincing analysis showed that living donor kidneys can sustain many hours of cold ischemia time without adverse consequences. Opinions also differ about whether the last donor in a chain of paired donation transplants initiated by a nondirected donor should donate immediately to someone on the deceased donor wait-list (a domino or closed chain) or should be asked to wait some length of time and donate to start another sequence of paired donations later (an open chain); some argue that asking the donor to donate later may be coercive, and others focus on balancing the probability that the waiting donor withdraws versus the number of additional transplants if the chain can be continued. Other controversies in paired donation include simultaneous versus nonsimultaneous donor operations, whether to enroll compatible pairs, and interactions with desensitization protocols. Efforts to expand public awareness of and participation in paired donation are needed to generate more transplant opportunities. PMID:22732046

  15. [Sex "addiction": compulsion and controversy].

    PubMed

    Souza y Machorro, Mario

    2002-10-01

    Modern occidental society often distorts and, in some cases, ignores healthy concepts regarding sexuality. Besides, It not always considers this, to be mental health or to represent an expression of whole health. Such ambivalence towards sex and the sexual is located between the limits of the sacred and erotic, both associated to taboos and their transgression. Since the last century, the current "neosexual" revolution intents to dismantle old patterns in favor of the dissociation of human sexual sphere, the dispersion of sexual fragments towards individualism and intimate relationships diversification. Within such context, "addiction" to sex and the sexual, as a compulsive conduct, represents on one side a clinical reality each time better observed and diagnosed, where the importance of family history is recognized, as well as individual psychopathology, and marital life, in its etiology and also for its treatment and prevention. On the other hand, it has not been classified in the mental health catalogues as it is not considered, meanwhile, as the problem is been maintained, the co-morbidity and its consequences multiply, and the controversy continues. PMID:12557802

  16. HPV vaccines: a controversial issue?

    PubMed Central

    Nicol, A.F.; Andrade, C.V.; Russomano, F.B.; Rodrigues, L.L.S.; Oliveira, N.S.; Provance, D.W.

    2016-01-01

    Controversy still exists over whether the benefits of the available HPV vaccines outweigh the risks and this has suppressed uptake of the HPV vaccines in comparison to other vaccines. Concerns about HPV vaccine safety have led some physicians, healthcare officials and parents to withhold the recommended vaccination from the target population. The most common reason for not administering the prophylactic HPV vaccines are concerns over adverse effects. The aim of this review is the assessment of peer-reviewed scientific data related to measurable outcomes from the use of HPV vaccines throughout the world with focused attention on the potential adverse effects. We found that the majority of studies continue to suggest a positive risk-benefit from vaccination against HPV, with minimal documented adverse effects, which is consistent with other vaccines. However, much of the published scientific data regarding the safety of HPV vaccines appears to originate from within the financially competitive HPV vaccine market. We advocate a more independent monitoring system for vaccine immunogenicity and adverse effects to address potential conflicts of interest with regular systematic literature reviews by qualified individuals to vigilantly assess and communicate adverse effects associated with HPV vaccination. Finally, our evaluation suggests that an expanded use of HPV vaccine into more diverse populations, particularly those living in low-resource settings, would provide numerous health and social benefits. PMID:27074168

  17. Bisphenol A: Understanding the Controversy.

    PubMed

    Metz, Cynthia Marie

    2016-01-01

    Healthy People 2020 lists Bisphenol A (BPA) as a potential endocrine disruptor for which exposure should be reduced. The Healthy People 2020 Environmental Health Objectives focus on addressing environmental factors that negatively affect individuals' health even though the health effects of some toxic substances are not yet fully understood. An American Association of Occupational Health Nurses (AAOHN) position statement outlined the role occupational health nurses play in creating healthy and productive workplaces by promoting worker health. BPA is implicated in a variety of health outcomes such as breast and prostate cancer, menstrual irregularities, genital abnormalities in male babies, infertility in men and women, early puberty in girls, and metabolic disorders such as diabetes and obesity. The overall health issues attributed to BPA exposure are complex and controversial. Concerns regarding environmental health are growing as individuals become more dependent on plastics. Numerous health concerns have been directly connected to daily exposures to products manufactured with BPA. Government agencies support the use of BPA as a safe consumer product with the exception of BPA use in baby bottles and sippy cups, which has been banned in the United States and several other countries. Many agencies (e.g., Federal Drug Administration [FDA], World Health Organization [WHO], U.S. Department of Health & Human Services [U.S. DHHS], and the Centers for Disease Control and Prevention [CDC]) have expressed "some concern" about BPA based on research, and stated further research is warranted. PMID:26800896

  18. Big U. S. gas producing states fan prorationing controversy

    SciTech Connect

    Not Available

    1992-05-04

    This paper reports that the biggest gas producing states in the U.S. are embracing wholesale changes in prorationing rules. And their actions have stirred controversy and warnings among key energy lawmakers in Washington. The Texas Railroad Commission last week unanimously approved new rules for setting production volumes for gas wells. Texas is the country's No. 1 gas producer. TRC commissioners eliminated a system that prorated production based on monthly nominations by gas purchasers. The Office of Conservation in Louisiana, No. 2 ranked producer, recently conducted a hearing on a prorationing proposal supported by Gov. Edwin Edwards. Conservation Commissioner Herbert W. Thompson is expected to disclose the state's plans by the end of this month. No. 3 Oklahoma enacted a law last March restricting production from unallocated wells in the 4 winter months to the greater of 1 MMcfd or 40% of the calculated absolute open flow and the rest of the year to the greater of 750 Mcfd or 25% of the calculated absolute open flow.

  19. Get Controversial! Edgy Novels for Older Teens

    ERIC Educational Resources Information Center

    Cox Clark, Ruth

    2007-01-01

    This article is a discussion of authors and controversial novels that should be on the top of library media specialists' reading list if they work with high-school-age teens. "Controversial" is not a dirty word, it is an enticement! The goal of library media specialists is to get teens who may be burned out with reading due to incentive programs…

  20. Teachers, Classroom Controversy, and the Media

    ERIC Educational Resources Information Center

    Faulconer, Tracy; Freeman, Ayesha Coning

    2005-01-01

    This article discusses the relationship between teachers, classroom controversy and the media. It also features the story of Ayesha, who coincidentally is one of the authors of this article. Ayesha's story is a social studies teacher's bad dream featuring one of her worst fears: (1) public criticism; and (2) controversy over something that has…

  1. History Forum Addresses Creation/Evolution Controversy.

    ERIC Educational Resources Information Center

    Schweinsberg, John

    1997-01-01

    A series of programs entitled Creationism and Evolution: The History of a Controversy was presented at the University of Alabama in Huntsville. The controversy was addressed from an historical and sociological, rather than a scientific perspective. Speakers addressed the evolution of scientific creationism, ancient texts versus sedimentary rocks…

  2. "Mysticism" in Quantum Mechanics: The Forgotten Controversy

    ERIC Educational Resources Information Center

    Marin, Juan Miguel

    2009-01-01

    This paper argues that a European controversy over a "mystical" hypothesis, one assigning the mind a role to play at the material level of reality, shaped much of the debate over the interpretation of the quantum equations. It traces back the controversy to the past two decades, beginning in the late 1920s--birth of quantum theory--and concluding…

  3. Nuclear Weapons: Concepts, Issues, and Controversies.

    ERIC Educational Resources Information Center

    Reardon, Betty; And Others

    1983-01-01

    The schools must confront and deal with the issues of the nuclear weapons controversy on pain of ceasing to be relevant to the critical needs of the rising generation. Every aspect of the nuclear arms controversy needs to be discussed in secondary and university classrooms. (RM)

  4. Evolutionary Psychology: Controversies, Questions, Prospects, and Limitations

    ERIC Educational Resources Information Center

    Confer, Jaime C.; Easton, Judith A.; Fleischman, Diana S.; Goetz, Cari D.; Lewis, David M. G.; Perilloux, Carin; Buss, David M.

    2010-01-01

    Evolutionary psychology has emerged over the past 15 years as a major theoretical perspective, generating an increasing volume of empirical studies and assuming a larger presence within psychological science. At the same time, it has generated critiques and remains controversial among some psychologists. Some of the controversy stems from…

  5. Teaching about NAFTA Using Academic Controversy.

    ERIC Educational Resources Information Center

    Starr, Eileen M.

    1997-01-01

    Examines a teaching strategy called "constructive controversy" where students are required to argue both the pro and con positions concerning a controversial current topic. Describes students' response to a class using this method to examine the North American Free Trade Agreement (NAFTA). Student response was generally favorable. (MJP)

  6. Friction stir processing on carbon steel

    SciTech Connect

    Tarasov, Sergei Yu.; Melnikov, Alexander G.; Rubtsov, Valery E.

    2014-11-14

    Friction stir processing of medium carbon steel samples has been carried out using a milling machine and tools made of cemented tungsten carbide. Samples have been machined from 40 and 40X steels. The tools have been made in the shape of 5×5×1.5 mm and 3×3×1.5 mm tetrahedrons. The microstructure of stirred zone has been obtained using the smaller tool and consists of fine recrystallized 2-3 μm grains, whereas the larger tool has produced the 'onion-like' structures comprising hard quenched 'white' 500-600 MPa layers with 300-350 MPa interlayers of bainite needles. The mean values of wear intensity obtained after measuring the wear scar width were 0.02 mm/m and 0.001 mm/m for non-processed and processed samples, respectively.

  7. Microstructure characterization of the stir zone of submerged friction stir processed aluminum alloy 2219

    SciTech Connect

    Feng, Xiuli; Liu, Huijie; Lippold, John C.

    2013-08-15

    Aluminum alloy 2219-T6 was friction stir processed using a novel submerged processing technique to facilitate cooling. Processing was conducted at a constant tool traverse speed of 200 mm/min and spindle rotation speeds in the range from 600 to 800 rpm. The microstructural characteristics of the base metal and processed zone, including grain structure and precipitation behavior, were studied using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness maps were constructed on polished cross sections of as-processed samples. The effect of tool rotation speed on the microstructure and hardness of the stir zone was investigated. The average grain size of the stir zone was much smaller than that of the base metal, but the hardness was also lower due to the formation of equilibrium θ precipitates from the base metal θ′ precipitates. Stir zone hardness was found to decrease with increasing rotation speed (heat input). The effect of processing conditions on strength (hardness) was rationalized based on the competition between grain refinement strengthening and softening due to precipitate overaging. - Highlights: • SZ grain size (∼ 1 μm) is reduced by over one order of magnitude relative to the BM. • Hardness in the SZ is lower than that of the precipitation strengthened BM. • Metastable θ′ in the base metal transforms to equilibrium θ in the stir zone. • Softening in the SZ results from a decrease of precipitation strengthening.

  8. Flexible Hybrid Friction Stir Joining Technology

    SciTech Connect

    2008-12-01

    This factsheet describes a research project whose goal is to advance the friction stir welding (FSW) process as a manufacturing technology that can be deployed for on-site construction of large, complex and typically thick-sectioned structures made of high performance and high-temperature materials. This would transform FSW from a specialty joining process into one with pervasive application potential across a number of industrial sectors where the payoff of energy reduction, environmental and economic benefits would be significant.

  9. Fuel property effects in stirred combustors

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Soot formation in strongly backmixed combustion was investigated using the jet-stirred combustor (JSC). This device provided a combustion volume in which temperature and combustion were uniform. It simulated the recirculating characteristics of the gas turbine primary zone; it was in this zone where mixture conditions were sufficiently rich to produce soot. Results indicate that the JSC allows study of soot formation in an aerodynamic situation revelant to gas turbines.

  10. Ultrasonic stir welding process and apparatus

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2009-01-01

    An ultrasonic stir welding device provides a method and apparatus for elevating the temperature of a work piece utilizing at least one ultrasonic heater. Instead of relying on a rotating shoulder to provide heat to a workpiece an ultrasonic heater is utilized to provide ultrasonic energy to the workpiece. A rotating pin driven by a motor assembly performs the weld on the workpiece. A handheld version can be constructed as well as a fixedly mounted embodiment.

  11. Eddy stirring in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Naveira Garabato, A. C.; Ferrari, R.; Polzin, K. L.

    2011-09-01

    There is an ongoing debate concerning the distribution of eddy stirring across the Antarctic Circumpolar Current (ACC) and the nature of its controlling processes. The problem is addressed here by estimating the isentropic eddy diffusivity κ from a collection of hydrographic and altimetric observations, analyzed in a mixing length theoretical framework. It is shown that, typically, κ is suppressed by an order of magnitude in the upper kilometer of the ACC frontal jets relative to their surroundings, primarily as a result of a local reduction of the mixing length. This observation is reproduced by a quasi-geostrophic theory of eddy stirring across a broad barotropic jet based on the scaling law derived by Ferrari and Nikurashin (2010). The theory interprets the observed widespread suppression of the mixing length and κ in the upper layers of frontal jets as the kinematic consequence of eddy propagation relative to the mean flow within jet cores. Deviations from the prevalent regime of mixing suppression in the core of upper-ocean jets are encountered in a few special sites. Such `leaky jet' segments appear to be associated with sharp stationary meanders of the mean flow that are generated by the interaction of the ACC with major topographic features. It is contended that the characteristic thermohaline structure of the Southern Ocean, consisting of multiple upper-ocean thermohaline fronts separated and underlaid by regions of homogenized properties, is largely a result of the widespread suppression of eddy stirring by parallel jets.

  12. Global controversies and advances in skin cancer.

    PubMed

    Baldwin, Louise; Dunn, Jeff

    2013-01-01

    Advances and controversies of skin cancer prevention in the Asian-Pacific region are to be examined the world's first Global Controversies and Advances in Skin Cancer Conference to be held in Brisbane, Australia this November. APOCP Members are cordially invited to register early for the opportunity to contribute to the debate on a cancer which continues to be a prominent issue in the Asia Pacific and indeed worldwide. We need answers to the questions of why a cancer that is so preventable and easily detectable is still shrouded in controversy. Primary focuses will be on issues like viral involvement, vaccines and novel clinical approaches. PMID:23725105

  13. Tool For Friction Stir Tack Welding of Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Bjorkman, Gerald W.; Dingler, Johnny W.; Loftus, Zachary

    2003-01-01

    A small friction-stir-welding tool has been developed for use in tack welding of aluminum-alloy workpieces. It is necessary to tack-weld the workpieces in order to hold them together during friction stir welding because (1) in operation, a full-size friction-stir-welding tool exerts a large force that tends to separate the workpieces and (2) clamping the workpieces is not sufficient to resist this force. It is possible to tack the pieces together by gas tungsten arc welding, but the process can be awkward and time-consuming and can cause sufficient damage to necessitate rework. Friction stir tack welding does not entail these disadvantages. In addition, friction stir tack welding can be accomplished by use of the same automated equipment (except for the welding tool) used in subsequent full friction stir welding. The tool for friction stir tack welding resembles the tool for full friction stir welding, but has a narrower shoulder and a shorter pin. The shorter pin generates a smaller workpiece-separating force so that clamping suffices to keep the workpieces together. This tool produces a continuous or intermittent partial-penetration tack weld. The tack weld is subsequently consumed by action of the larger tool used in full friction stir welding tool.

  14. Sorting Out the Video Game Controversy.

    ERIC Educational Resources Information Center

    Crespi, Pam

    1983-01-01

    This article looks at the controversy over video games; arguments for and against them are offered, along with a list of regulations in force around the country and nine important factors agencies should consider before leasing the machines. (JM)

  15. Controversial Issues within Biology: Enriching Biology Teaching.

    ERIC Educational Resources Information Center

    Van Rooy, Wilhelmina

    2000-01-01

    Describes the development and implementation of a senior high school biology lesson concerned with organ transplantation. Discusses the teacher's rationale and techniques for using controversial issues in science teaching. (Contains 18 references.) (Author/WRM)

  16. Stir zone microstructure and strain rate during Al 7075-T6 friction stir spot welding

    NASA Astrophysics Data System (ADS)

    Gerlich, A.; Avramovic-Cingara, G.; North, T. H.

    2006-09-01

    The factors determining the temperature, heating rate, microstructure, and strain rate in Al 7075-T6 friction stir spot welds are investigated. Stir zone microstructure was examined using a combination of transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD) microscopy, while the strain rate during spot welding was calculated by incorporating measured temperatures and the average subgrain dimensions in the Zener-Hollomon relation. The highest temperature during friction stir spot welding (527 °C) was observed in spot welds made using a tool rotational speed of 3000 rpm. The stir zone regions comprised fine-grained, equiaxed, fully recrystallized microstructures. The calculated strain rate in Al 7075-T6 spot welds decreased from 650 to about 20 s-1 when the tool rotational speed increased from 1000 to 3000 rpm. It is suggested that the decrease in strain rate results when tool slippage occurs when the welding parameter settings facilitate transient local melting during the spot welding operation. Transient local melting and tool slippage are produced when the welding parameters produce sufficiently high heating rates and temperatures during spot welding. However, transient local melting and tool slippage is not produced in Al 7075-T6 spot welds made using a rotational speed of 1000 rpm since the peak temperature is always less than 475 °C.

  17. Automated multisyringe stir bar sorptive extraction using robust montmorillonite/epoxy-coated stir bars.

    PubMed

    Ghani, Milad; Saraji, Mohammad; Maya, Fernando; Cerdà, Víctor

    2016-05-01

    Herein we present a simple, rapid and low cost strategy for the preparation of robust stir bar coatings based on the combination of montmorillonite with epoxy resin. The composite stir bar was implemented in a novel automated multisyringe stir bar sorptive extraction system (MS-SBSE), and applied to the extraction of four chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol) as model compounds, followed by high performance liquid chromatography-diode array detection. The different experimental parameters of the MS-SBSE, such as sample volume, selection of the desorption solvent, desorption volume, desorption time, sample solution pH, salt effect and extraction time were studied. Under the optimum conditions, the detection limits were between 0.02 and 0.34μgL(-1). Relative standard deviations (RSD) of the method for the analytes at 10μgL(-1) concentration level ranged from 3.5% to 4.1% (as intra-day RSD) and from 3.9% to 4.3% (as inter-day RSD at 50μgL(-1) concentration level). Batch-to-batch reproducibility for three different stir bars was 4.6-5.1%. The enrichment factors were between 30 and 49. In order to investigate the capability of the developed technique for real sample analysis, well water, wastewater and leachates from a solid waste treatment plant were satisfactorily analyzed. PMID:27062720

  18. Friction Stir Weld Modeling at MSFC: Kinematics

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C., Jr.

    2000-01-01

    A "merry-go-round" computation model makes it easier to visualize how tracer experiments of varied sorts (chemical, shot, wire) are consistent with a "moving plug model" of flow around the friction stir welding pin-tool. The moving plug model comprises a twofold flow: 1. a primary rotation of a plug of metal with the tool, which moves metal around the tool by wiping it on and off the plug, and 2. a secondary, relatively slow circulation induced by the threads on the tool resembling a circular vortex ring around the tool.

  19. Gas fluidized-bed stirred media mill

    SciTech Connect

    Sadler, III, Leon Y.

    1997-01-01

    A gas fluidized-bed stirred media mill is provided for comminuting solid ticles. The mill includes a housing enclosing a porous fluidizing gas diffuser plate, a baffled rotor and stator, a hollow drive shaft with lateral vents, and baffled gas exhaust exit ports. In operation, fluidizing gas is forced through the mill, fluidizing the raw material and milling media. The rotating rotor, stator and milling media comminute the raw material to be ground. Small entrained particles may be carried from the mill by the gas through the exit ports when the particles reach a very fine size.

  20. Another Look at Controversial Issues and the Curriculum.

    ERIC Educational Resources Information Center

    Gardner, Peter

    1984-01-01

    Controversial issues should be taught in school. Charles Bailey's and R.F. Dearden's opinions of what makes an issue controversial are critiqued. Bailey accounts for controversial issues in behavioral terms; Dearden advances an epistemic account. (RM)

  1. Contrasting Controversies: Fracking and Climate Change

    NASA Astrophysics Data System (ADS)

    Duggan-Haas, D.; Zabel, I. H. H.; Ross, R. M.

    2014-12-01

    Slickwater high-volume hydraulic fracturing (commonly known as "fracking") is highly controversial. So is global warming, and the two issues are closely related, but the natures of these two controversies have substantial and important differences. Building upon years of experience in teaching and developing resources and strategies for teaching about evolution and climate change, staff at the Paleontological Research Institution have engaged in public outreach and educator professional development to help nurture understanding of fracking and the broader energy system. How are these controversies similar to and different from one another, and how should understanding these similarities and differences inform educational programming (and about how you talk about these issues with your Uncle Fred at the family holiday dinner?). It is nearly universally agreed amongst scientists who study climate that changes now underway are real and human caused, and are posing or likely to pose very serious problems for humanity. Scientists who study slickwater high-volume hydraulic fracturing agree that it causes environmental damage, but there is no consensus as to whether fracking causes more or less harm (e.g., among different kinds of environment harm, across different temporal and spatial scales, and among different social contexts) than other ways of producing energy on a large scale. In other words, the basic tenets of climate change are not a matter of scientific controversy, though the implications for policy making obviously remain politically controversial, while fracking is an issue of both scientific and political controversy. Without advocating for or against fracking, we help audiences disentangle scientific and political issues, better understand the energy resources used in their own communities, and consider issues of scale, systems, and complexity. We will compare and contrast the overlapping controversies surrounding climate change and fracking and highlight

  2. Crystallographic Texture in Bobbin Tool Friction-Stir-Welded Aluminum

    NASA Astrophysics Data System (ADS)

    Shen, Junjun; Wang, Feifan; Suhuddin, Uceu F. H.; Hu, Siyi; Li, Wenya; dos Santos, Jorge F.

    2015-07-01

    Bobbin tool friction-stir welding was used to join 3.2-mm-thick AA2198. The textural results show that four sub zones are formed vertically in the stirred zone. The materials in upper and lower two zones underwent negative and positive shears, respectively; they are uniformly recognized as dominate C and minor A simple shear components.

  3. Friction Stir Welding of Lightweight Vehicle Structures: Final Report

    SciTech Connect

    Sanella, M L

    2008-08-31

    The purpose of this Cooperative Research and Development Agreement (CRADA) between UTBattelle, LLC and Ford Motor Company was to establish friction stir welding (FSW) and friction stir processing as viable options for use in construction of lightweight substructures for trucks and cars, including engine cradles, suspension sub frames, instrument panel supports, and intake manifolds.

  4. Certification of a weld produced by friction stir welding

    DOEpatents

    Obaditch, Chris; Grant, Glenn J

    2013-10-01

    Methods, devices, and systems for providing certification of friction stir welds are disclosed. A sensor is used to collect information related to a friction stir weld. Data from the sensor is compared to threshold values provided by an extrinsic standard setting organizations using a certification engine. The certification engine subsequently produces a report on the certification status of the weld.

  5. Friction stir method for forming structures and materials

    DOEpatents

    Feng, Zhili; David, Stan A.; Frederick, David Alan

    2011-11-22

    Processes for forming an enhanced material or structure are disclosed. The structure typically includes a preform that has a first common surface and a recess below the first common surface. A filler is added to the recess and seams are friction stir welded, and materials may be stir mixed.

  6. A Rotating Plug Model of Friction Stir Welding Heat Transfer

    NASA Technical Reports Server (NTRS)

    Raghulapadu J. K.; Peddieson, J.; Buchanan, G. R.; Nunes, A. C.

    2006-01-01

    A simplified rotating plug model is employed to study the heat transfer phenomena associated with the fiction stir welding process. An approximate analytical solution is obtained based on this idealized model and used both to demonstrate the qualitative influence of process parameters on predictions and to estimate temperatures produced in typical fiction stir welding situations.

  7. Damage Tolerance Behavior of Friction Stir Welds in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process used in the fabrication of various aerospace structures. Self-reacting and conventional friction stir welding are variations of the friction stir weld process employed in the fabrication of cryogenic propellant tanks which are classified as pressurized structure in many spaceflight vehicle architectures. In order to address damage tolerance behavior associated with friction stir welds in these safety critical structures, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data describing fracture behavior, residual strength capability, and cyclic mission life capability of friction stir welds at ambient and cryogenic temperatures have been generated and will be presented in this paper. Fracture behavior will include fracture toughness and tearing (R-curve) response of the friction stir welds. Residual strength behavior will include an evaluation of the effects of lack of penetration on conventional friction stir welds, the effects of internal defects (wormholes) on self-reacting friction stir welds, and an evaluation of the effects of fatigue cycled surface cracks on both conventional and selfreacting welds. Cyclic mission life capability will demonstrate the effects of surface crack defects on service load cycle capability. The fracture data will be used to evaluate nondestructive inspection and proof test requirements for the welds.

  8. Meshless Simulation of Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Alfaro, I.; Fratini, L.; Cueto, E.; Chinesta, F.; Micari, F.

    2007-05-01

    This paper encompasses our first efforts towards the numerical simulation of friction stir welding by employing a Lagrangian approach. To this end, we have employed a meshless method, namely the Natural Element Method (NEM). Friction Stir welding is a welding process where the union between the work pieces is achieved through the extremely high deformation imposed by a rotating pin, which moves between the two pieces. This extremely high strain is the main responsible of the difficulties associated with the numerical simulation of this forming process. Eulerian and Arbitrary Lagrangian-Eulerian (ALE) frameworks encounter difficulties in some aspects of the simulation. For instance, these approaches need additional techniques for the description of the boundary between materials, such as level sets, boundary markers or similar. In this paper we address the issue of employing a Lagrangian framework, which adequately describes the evolution in time of the interphase. The meshless character of the technique also ensures that no degeneracy on the accuracy is obtained due to mesh distortion. Some examples are presented that show the potential of the technique in simulating such a process.

  9. The Plunge Phase of Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur; McClure, John; Avila, Ricardo

    2005-01-01

    Torque and plunge force during the initial plunge phase in Friction Stir Welding were measured for a 0.5 inch diameter pin entering a 2219 aluminum alloy plate. Weld structures were preserved for metallographic observation by making emergency stops at various plunge depths. The plunging pin tool is seen to be surrounded by a very fine grained layer of recrystallized metal extending substantially below the bottom of the pin, implying a shear interface in the metal below and not at the tool-metal interface. Torque and plunge force during the initial plunge phase in Friction Stir Welding are calculated from a straight forward model based on a concept to plastic flow in the vicinity of the plunging tool compatible with structural observations. The concept: a disk of weld metal seized to and rotating with the bottom of the pin is squeezed out laterally by the plunge force and extruded upwards in a hollow cylinder around the tool. As the shear surface separating rotating disk from stationary weld metal engulfs fresh metal, the fresh metal is subjected to severe shear deformation, which results in its recrystallization. Encouraging agreement between computations and measured torque and plunge force is obtained.

  10. Friction Stir Welding at MSFC: Kinematics

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.

    2001-01-01

    In 1991 The Welding Institute of the United Kingdom patented the Friction Stir Welding (FSW) process. In FSW a rotating pin-tool is inserted into a weld seam and literally stirs the faying surfaces together as it moves up the seam. By April 2000 the American Welding Society International Welding and Fabricating Exposition featured several exhibits of commercial FSW processes and the 81st Annual Convention devoted a technical session to the process. The FSW process is of interest to Marshall Space Flight Center (MSFC) as a means of avoiding hot-cracking problems presented by the 2195 aluminum-lithium alloy, which is the primary constituent of the Lightweight Space Shuttle External Tank. The process has been under development at MSFC for External Tank applications since the early 1990's. Early development of the FSW process proceeded by cut-and-try empirical methods. A substantial and complex body of data resulted. A theoretical model was wanted to deal with the complexity and reduce the data to concepts serviceable for process diagnostics, optimization, parameter selection, etc. A first step in understanding the FSW process is to determine the kinematics, i.e., the flow field in the metal in the vicinity of the pin-tool. Given the kinematics, the dynamics, i.e., the forces, can be targeted. Given a completed model of the FSW process, attempts at rational design of tools and selection of process parameters can be made.

  11. Flow Patterns During Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Guerra, M.; Schmidt, C.; McClure, J. C.; Murr, L. E.; Nunes, A. C.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    Friction Stir Welding is a relatively new technique for welding that uses a cylindrical pin or nib inserted along the weld seam. The nib (usually threaded) and the shoulder in which it is mounted are rapidly rotated and advanced along the seam. Extreme deformation takes place leaving a fine equiaxed structure in the weld region., The flow of metal during Friction Stir Welding is investigated using a faying surface tracer and a nib frozen in place during welding. It is shown that material is transported by two processes. The first is a wiping of material from the advancing front side of the nib onto a zone of material that rotates and advances with the nib. The material undergoes a helical motion within the rotational zone that both rotates and advances and descends in the wash of the threads on the nib and rises on the outer part of the rotational zone. After one or more rotations, this material is sloughed off in its wake of the nib, primarily on the advancing side. The second process is an entrainment of material from the front retreating side of the nib that fills in between the sloughed off pieces from the advancing side.

  12. New Tool Creates a Big Stir

    NASA Technical Reports Server (NTRS)

    2001-01-01

    A new self-adjusting, retractable pin tool for friction stir welding is now used in the manufacturing of components for NASA Space Shuttles. Friction stir welding is a process that makes straight-line welds without bringing the parent material to a liquid state. This is accomplished through high-speed rotation, which generates frictional heat between the welding tool and the piece being welded. This heat causes the material to soften to the point of plasticity without allowing it to melt. The plasticized material is then transferred from the front edge of the welding tool to the trail edge, where it joins the pieces being welded. However, a major flaw of this method is its reliance on a single-piece pin tool. The weld is left unfinished and a hole remains where the pin was inserted. The hole must be covered with a rivet in order to preserve the integrity of the weld. The NASA-developed pin tool, however, eliminates the need for this finishing step, as its retraction allows continuous rewelding at lesser depths, until the hole is completely closed. With this NASA technology, welding of higher strength alloys, as well as non-planer and variable thickness structures can be achieved.

  13. High-Powered, Ultrasonically Assisted Thermal Stir Welding

    NASA Technical Reports Server (NTRS)

    Ding, Robert

    2013-01-01

    This method is a solid-state weld process capable of joining metallic alloys without melting. The weld workpieces to be joined by thermal stir welding (TSW) are drawn, by heavy forces, between containment plates past the TSW stir tool that then causes joining of the weld workpiece. TSW is similar to friction stir welding (FSW) in that material is heated into a plastic state (not melted) and stirred using a stir rod. The FSW pin tool is an integrated geometrical structure consisting of a large-diameter shoulder, and a smaller-diameter stir pin protruding from the shoulder. When the pin is plunged into a weld workpiece, the shoulder spins on the surface of the weld workpiece, thus inducing frictional heat into the part. The pin stirs the fraying surfaces of the weld joint, thus joining the weld workpiece into one structure. The shoulder and stir pin of the FSW pin tool must rotate together at a desired rotational speed. The induced frictional energy control and stir pin control of the pin tool cannot be de-coupled. The two work as one integrated unit. TSW, on the other hand, de-couples the heating and stirring of FSW, and allows for independent control of each process element. A uniquely designed induction coil heats the weld workpiece to a desired temperature, and once heated, the part moves into a stir rod whose RPM is also independently controlled. As the weld workpiece moves into the stir rod, the piece is positioned, or sandwiched, between upper and lower containment plates. The plate squeezes together, thus compressing the upper and lower surfaces of the weld workpiece. This compressive force, also called consolidation force, consolidates the plastic material within the weld nugget material as it is being stirred by the stir rod. The stir rod is positioned through the center of the top containment plate and protrudes midway through the opposite lower containment plate where it is mechanically captured. The upper and lower containment plates are separated by a

  14. The controversy of cranial bone motion.

    PubMed

    Rogers, J S; Witt, P L

    1997-08-01

    Cranial bone motion continues to stimulate controversy. This controversy affects the general acceptance of some intervention methods used by physical therapists, namely, cranial osteopathic and craniosacral therapy techniques. Core to these intervention techniques is the belief that cranial bone mobility provides a compliant system where somatic dysfunction can occur and therapeutic techniques can be applied. Diversity of opinion over the truth of this concept characterizes differing viewpoints on the anatomy and physiology of the cranial complex. Literature on cranial bone motion was reviewed for the purpose of better understanding this topic. Published research overall was scant and inconclusive. Animal and human studies demonstrate a potential for small magnitude motion. Physical therapists should carefully scrutinize the literature presented as evidence for cranial bone motion. Further research is needed to resolve this controversy. Outcomes research, however, is needed to validate cranial bone mobilization as an effective treatment. PMID:9243408

  15. 'Mysticism' in quantum mechanics: the forgotten controversy

    NASA Astrophysics Data System (ADS)

    Marin, Juan Miguel

    2009-07-01

    This paper argues that a European controversy over a 'mystical' hypothesis, one assigning the mind a role to play at the material level of reality, shaped much of the debate over the interpretation of the quantum equations. It traces back the controversy to the past two decades, beginning in the late 1920s—birth of quantum theory—and concluding with Erwin Schrödinger's lectures published as 'Mind and Matter'. Becoming aware of the issues at stake can help us understand the historical, philosophical and cultural background from which today's physics emerged.

  16. Endoscope Reprocessing: Update on Controversial Issues

    PubMed Central

    Choi, Hyun Ho

    2015-01-01

    Several issues concerning endoscope reprocessing remain unresolved based on currently available data. Thus, further studies are required to confirm standard practices including safe endoscope shelf life, proper frequency of replacement of some accessories including water bottles and connecting tubes, and microbiological surveillance testing of endoscopes after reprocessing. The efficacy and cost-effectiveness of newer technology that allows automated cleaning and disinfection is one such controversial issue. In addition, there are no guidelines on whether delayed reprocessing and extended soaking may harm endoscope integrity or increase the bioburden on the external or internal device surfaces. In this review, we discuss the unresolved and controversial issues regarding endoscope reprocessing. PMID:26473115

  17. Metal Flow in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C., Jr.

    2006-01-01

    The plastic deformation field in Friction Stir Welding (FSW) is compared to that in metal cutting. A shear surface around the FSW tool analogous to the metal cutting shear plane is identified and comprises the basis of the "rotating plug" flow field model and the "wiping" model of tool interaction with weld metal. Within the context of these models: The FSW shear rate is estimated to be comparable to metal cutting shear rates. The effect of tool geometry on the FSW shear surface is discussed and related to published torque measurements. Various FS W structural features are explained, including a difference in structure of bimetallic welds when alloys on the advancing and retreating sides of the weld seam are exchanged. The joining mechanism and critical parameters of the FSW process are made clear.

  18. Ultrasonically-assisted Thermal Stir Welding System

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2014-01-01

    A welding head assembly has a work piece disposed between its containment plates' opposing surfaces with the work piece being maintained in a plastic state thereof at least in a vicinity of the welding head assembly's stir rod as the rod is rotated about its longitudinal axis. The welding head assembly and the work piece experience relative movement there between in a direction perpendicular to the rod's longitudinal axis as the work piece is subjected to a compressive force applied by the containment plates. A first source coupled to the first containment plate applies a first ultrasonic wave thereto such that the first ultrasonic wave propagates parallel to the direction of relative movement. A second source coupled to the second containment plate applies a second ultrasonic wave thereto such that the second ultrasonic wave propagates parallel to the direction of relative movement.propagates parallel to the direction of relative movement.

  19. Laser Peening Effects on Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Hatamleh, Omar

    2011-01-01

    Friction Stir Welding (FSW) is a welding technique that uses frictional heating combined with forging pressure to produce high strength bonds. It is attractive for aerospace applications. Although residual stresses in FSW are generally lower when compared to conventional fusion welds, recent work has shown that significant tensile residual stresses can be present in the weld after fabrication. Therefore, laser shock peening was investigated as a means of moderating the tensile residual stresses produced during welding. This slide presentation reviews the effect of Laser Peening on the weld, in tensile strength, strain, surface roughness, microhardness, surface wear/friction, and fatigue crack growth rates. The study concluded that the laser peening process can result in considerable improvement to crack initiaion, propagation and mechanical properties in FSW.

  20. Tool Forces Developed During Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Melendez, M.; Tang, W.; Schmidt, C.; McClure, J. C.; Nunes, A. C.; Murr, L. E.

    2003-01-01

    This paper will describe a technique for measuring the various forces and the torque that exist on the Friction Stir Welding pin tool. Results for various plunge depths, weld speeds, rotational speed, and tool configurations will be presented. Welds made on 6061 aluminum with typical welding conditions require a downward force of 2800 lbs. (12.5 kN) a longitudinal force in the direction of motion of 300 lbs (1.33 kN), a transverse force in the omega x v direction of 30 lbs (135 N). Aluminum 2195 under typical weld conditions requires a downward force of 3100 lbs. (1.38 kN), a longitudinal force of 920 lbs. (4.1 kN), and a transverse force of 45 lbs. (200 N) in the omega x v direction.

  1. Fundamentals of friction stir spot welding

    NASA Astrophysics Data System (ADS)

    Badarinarayan, Harsha

    The recent spike in energy costs has been a major contributor to propel the use of light weight alloys in the transportation industry. In particular, the automotive industry sees benefit in using light weight alloys to increase fuel efficiency and enhance performance. In this context, light weight design by replacing steel with Al and/or Mg alloys have been considered as promising initiatives. The joining of structures made of light weight alloys is therefore very important and calls for more attention. Friction Stir Spot Welding (FSSW) is an evolving technique that offers several advantages over conventional joining processes. The fundamentals aspects of FSSW are systematically studied in this dissertation. The effects and influence of process inputs (weld parameters and tool geometry) on the process output (weld geometry and static strength) is studied. A Design of Experiments (DoE) is carried out to identify the effect of each process parameter on weld strength. It is found that the tool geometry, and in particular the pin profile has a significant role in determining the weld geometry (hook, stir zone size etc.) which in turn influences the failure mode and weld strength. A novel triangular pin tool geometry is proposed that suppresses the hook formation and produces welds with twice the static strength as those produced with conventional cylindrical pin tools. An experimental and numerical approach is undertaken to understand the effect of pin geometry on the material flow and failure mechanism of spot welds. In addition, key practical issues have been addressed such as quantification of tool life and a methodology to control tool plunge depth during welding. Finally, by implementing the findings of this dissertation, FSSW is successfully performed on a closure panel assembly for an automotive application.

  2. Textures in Single-Crystal Aluminum Friction Stir Spot Welds

    NASA Astrophysics Data System (ADS)

    Shibayanagi, Toshiya; Gerlich, Adrian P.; Kashihara, Keizo; North, Thomas H.

    2009-04-01

    The present article examines the textural features produced during friction stir spot welding of single-crystal aluminum sheet. The crystal has the {111} plane perpendicular to the normal direction (ND) of the sheet, and the left< { 1 10} rightrangle direction parallel to the growth direction (GD). Friction stir spot welding was carried out using a rotation speed of 1500 rpm and a dwell time of 2 seconds, and completed spot welds were characterized using a combination of optical microscopy and electron backscatter diffraction (EBSD). The EBSD measurements indicate there are no significant changes in orientation in locations more than 840 μm from the stir-zone extremity. The orientation distribution in the thermomechanically-affected zone (TMAZ) region conformed with the {110}⊥ND orientation within 580 μm of the stir-zone extremity. In the location immediately adjacent to the stir-zone extremity, there was a deviation from the {110}//ND orientation due to a combination of compressive loading perpendicular to the stir-zone boundary and shear loading in the direction of tool rotation. It is suggested a {111}⊥ND texture in the stir zone is associated with material flow imposed by the thread on the rotating pin.

  3. Evolution as a Controversial Issue: A Review of Instructional Approaches

    ERIC Educational Resources Information Center

    Hermann, Ronald S.

    2008-01-01

    Although evolution has long been considered a controversial issue, little effort has been made to ensure that instructional approaches address the controversial nature of the issue. A framework for understanding the nature of controversy and some defining characteristics of controversial issues are provided. In light of this framework evolution is…

  4. Debating Diversity: Ethics and Controversial Public Issues

    ERIC Educational Resources Information Center

    Darr, Christopher R.

    2016-01-01

    Courses: Ethics, Organizational Communication, Political Communication. Objectives: After completing this unit activity, students should be able to (1) apply multiple ethical perspectives to real-world diversity issues in a debate format, and (2) explain the role of informational and social category diversity in current controversies.

  5. A Constructive Controversy Approach to "Case Studies"

    ERIC Educational Resources Information Center

    Bird, Sharon R.; Erickson, Karla A.

    2010-01-01

    On the basis of analysis of student responses to a case study titled "Drinks and Dinner," the authors evaluate the pedagogical potential of using constructive controversy case studies to teach about inequality. "Drinks and Dinner" is designed to capture the complexity of social interactions that defy simple solutions to engage students in…

  6. Controversy, Trials, and Crime--Oh My!

    ERIC Educational Resources Information Center

    Rott, Kim

    2006-01-01

    Teenagers' innate interest with the justice system is one of the reasons that so many high school literary classics teem with criminals, controversial issues, and trials. Novels such as "To Kill a Mockingbird," "A Separate Peace," "The Crucible," and "Twelve Angry Men" feature high-impact trials. In the author's desire to tap into this interest,…

  7. Controversial Therapies: A Review and Critique.

    ERIC Educational Resources Information Center

    Rooney, Karen J.

    1991-01-01

    The article offers guidelines to educators evaluating controversial therapies and applies them to four such therapies: tinted lenses as a cure for dyslexia; orthomolecular treatments for learning disabilities; pharmaceutical intervention for dyslexia; and visual training for children with learning disabilities. (DB)

  8. Controversial Novels and Censorship in the Schools.

    ERIC Educational Resources Information Center

    Katz, John Stuart

    The legal history of censorship in general in the United States as well as the legal context in particular of the censorship of novels from schools is discussed. This thesis deals with four novels which have aroused substantial controversy when taught in the schools. The novels are: "The Catcher in the Rye," by J. D. Salinger, "The Adventures of…

  9. Science, Politics, and the IQ Controversy.

    ERIC Educational Resources Information Center

    Snyderman, Mark; Rothman, Stanley

    1986-01-01

    The controversy over intelligence testing is more often influenced by political considerations than empirical research. A survey of 1,020 experts found that a majority agree that (1) intelligence can be defined; (2) heredity plays a role in individual and group IQ differences; and (3) intelligence testing in schools should continue at its present…

  10. Apraxia of Speech: Concepts and Controversies

    ERIC Educational Resources Information Center

    Ziegler, Wolfram; Aichert, Ingrid; Staiger, Anja

    2012-01-01

    Purpose: This article was written as an editorial to a collection of original articles on apraxia of speech (AOS) in which some of the more recent advancements in the understanding of this syndrome are discussed. It covers controversial issues concerning the theoretical foundations of AOS. Our approach was motivated by a change of perspective on…

  11. LCA – Unique and Controversial Case Studies

    EPA Science Inventory

    This session will focus on case studies and applications that have a unique or controversial aspect. Some of the most recent topics that seem to have significant interest include: LCA-based product declarations, LCA-based standards, LCA-based labels, alternative energy, agricul...

  12. Controversial Issues in Our Schools. Fastback 146.

    ERIC Educational Resources Information Center

    Goldstein, William

    There is virtually nothing taught in the American public school that is not potentially explosive at some time or place. America's cultural makeup provides for the development of controversy whenever such issues as sex, religion, politics, and economics are raised, and particularly when they are raised in the school environment. School…

  13. Anticipation and Controversy Surround "Superman" Release

    ERIC Educational Resources Information Center

    Aarons, Dakarai I.

    2010-01-01

    Well in advance of its official release, the education film "Waiting For Superman" has attracted a level of attention that could make it one of the year's most-watched documentaries--and one of the most controversial among educators, some of whom question its depictions of the American school system and how to improve it. Made by director Davis…

  14. Parental Voices and Controversies in Autism

    ERIC Educational Resources Information Center

    Langan, Mary

    2011-01-01

    Parents of children with autism have played a prominent role in controversies surrounding this condition. Parental voices were critical in challenging the "refrigerator mother" theory and more recently have attracted public attention for claims that autism may be caused by childhood vaccinations and that "unorthodox biomedical" treatments may…

  15. Controversial Issues: A Case for Neutrality?

    ERIC Educational Resources Information Center

    Cain, Paul

    1999-01-01

    Arguments against teachers asserting their own views about controversial issues say that neutrality enables students to develop autonomous reflection. Others claim that a nonneutral stance is morally preferable. There are some teaching situations in which a neutral stance may not be an option. (SK)

  16. Controversies in Pediatric Sports Medicine (Commentary).

    ERIC Educational Resources Information Center

    Dyment, Paul G.

    1989-01-01

    Discusses controversial issues that have arisen in children's sports, including infant exercise programs, trampolines, amenorrhea in the adolescent athlete, coed contact sports, and sport participation by children with Down Syndrome. Policy statements are included from the American Academy of Pediatrics. (JD)

  17. Evolution versus Creationism: The Public Education Controversy.

    ERIC Educational Resources Information Center

    Zetterberg, J. Peter, Ed.

    The University of Minnesota organized a conference ("Evolution and Public Education," December 5, 1981) to help clarify issues in the creation/evolution controversy and to examine arguments of the proponents of scientific creationism. This six-part book, a revised version of a resource manual compiled for the conference: (1) discusses the theory…

  18. Behind the Evolution/Creation Controversy.

    ERIC Educational Resources Information Center

    Parker, Franklin

    This paper discusses the historical background of the creationist movement, presents Federal Judge Overton's analysis of why and how the Creationists got the equal time evolution/creation teaching law passed in Arkansas, and examines how scientists and educators are reacting to the controversy. Creationists were set back when Overton declared…

  19. Courting Controversy: How to Build Interdisciplinary Units.

    ERIC Educational Resources Information Center

    Williams, Jackie; Reynolds, Terry Deal

    1993-01-01

    By focusing on a polluted river and a visit to a rural Tennessee town, sixth-grade students from suburban Asheville, North Carolina, learned more about this controversy than many of their well-informed parents and teachers. Steps for creating similar interdisciplinary thematic units are described, along with the benefits of team teaching and…

  20. Federal Judge Orders Showing of Controversial Film.

    ERIC Educational Resources Information Center

    Flygare, Thomas J.

    1987-01-01

    Reviews a recent court decision in Nebraska regarding the cancellation of a controversial film on the University of Nebraska campus. The film was cancelled after a state senator threatened to close the theater if the movie was shown. The lawsuit alleged the university violated the First Amendment in cancelling the film; the judge ruled for the…

  1. Teaching Controversial Issues in Social Studies.

    ERIC Educational Resources Information Center

    Guyton, Edith M.; Hoffman, Alan J.

    The design of a methods course offered at Georgia State University to prepare social studies teachers for dealing with controversial issues in the middle school or secondary social studies classroom is presented. The course focuses on identification, selection, an analysis of an issue as well as the requirement that the student develop some method…

  2. 30 CFR 281.9 - Jurisdictional controversies.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Jurisdictional controversies. 281.9 Section 281.9 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR OFFSHORE LEASING OF MINERALS OTHER THAN OIL, GAS, AND SULPHUR IN THE OUTER CONTINENTAL SHELF General § 281.9...

  3. 30 CFR 282.7 - Jurisdictional controversies.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Jurisdictional controversies. 282.7 Section 282.7 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR OFFSHORE OPERATIONS IN THE OUTER CONTINENTAL SHELF FOR MINERALS OTHER THAN OIL, GAS, AND SULPHUR General §...

  4. Friction Stir Spot Welding of Advanced High Strength Steels

    SciTech Connect

    Hovanski, Yuri; Grant, Glenn J.; Santella, M. L.

    2009-11-13

    Friction stir spot welding techniques were developed to successfully join several advanced high strength steels. Two distinct tool materials were evaluated to determine the effect of tool materials on the process parameters and joint properties. Welds were characterized primarily via lap shear, microhardness, and optical microscopy. Friction stir spot welds were compared to the resistance spot welds in similar strength alloys by using the AWS standard for resistance spot welding high strength steels. As further comparison, a primitive cost comparison between the two joining processes was developed, which included an evaluation of the future cost prospects of friction stir spot welding in advanced high strength steels.

  5. Microstructural evolution of pure copper during friction-stir welding

    NASA Astrophysics Data System (ADS)

    Mironov, S.; Inagaki, K.; Sato, Y. S.; Kokawa, H.

    2015-02-01

    The microstructural evolution of pure copper during friction-stir welding was found to be principally influenced by welding temperature. At temperatures below ~0.5 Tm (where Tm is melting point), the microstructure was shown to be essentially determined by continuous recrystallization, leading to significant grain refinement and related material strengthening in the stir zone. In contrast, grain structure development at temperatures above ~0.5 Tm was dominated by discontinuous recrystallization producing a relatively coarse grain structure in the stir zone and giving rise to material softening.

  6. Friction stir processing on high carbon steel U12

    SciTech Connect

    Tarasov, S. Yu. Rubtsov, V. E.; Melnikov, A. G.

    2015-10-27

    Friction stir processing (FSP) of high carbon steel (U12) samples has been carried out using a milling machine and tools made of cemented tungsten carbide. The FSP tool has been made in the shape of 5×5×1.5 mm. The microstructural characterization of obtained stir zone and heat affected zone has been carried out. Microhardness at the level of 700 MPa has been obtained in the stir zone with microstructure consisting of large grains and cementitte network. This high-level of microhardness is explained by bainitic reaction developing from decarburization of austenitic grains during cementite network formation.

  7. Magnetohydrodynamic calculation of in-mold electromagnetic stirring

    SciTech Connect

    Fujisaki, Keisuke; Ueyama, Takatsugu; Okazawa, Kensuke

    1997-03-01

    The in-mold electromagnetic stirring is used to control the initial solidification of molten steel of the continuous casting. To get the optimal operation of in-mold electromagnetic stirring through the fundamental characteristics, the authors did the magnetohydrodynamic calculation. The electromagnetic force has the eddy distribution through the electromagnetic analysis in case of the rotating stirring mode which is thought to give the uniform velocity at surface. However, it does not much influence on the fluid dynamics, because the inertial effect and the continuity are large enough.

  8. Evidence of induced chirality in stirred solutions of supramolecular nanofibers.

    PubMed

    Arteaga, Oriol; Canillas, Adolf; Purrello, Roberto; Ribó, Josep M

    2009-07-15

    Two-modulator generalized ellipsometry is used to determine the spectroscopic Mueller matrix of a solution of porphyrin supramolecular aggregates that have fibrous form. During the measurements the solutions were stirred in clockwise and anticlockwise directions. The pseudopolar decompostion is applied to the experimental Mueller matrices to unveil the birefringent and dichroics properties of the sample. The vortex flow in the stirred solution is found to modify the optical response of the aggregates to polarized light, and, in particular, its chiral signature is determined by the stirring direction in a totally reversible process. The data found show that chirality can be induced by stirring in solutions of supramolecular fibers and that a effective transfer of chirality from a macroscopic phenomenon to the supramolecular structures takes place. PMID:19823540

  9. Friction Stir Spot Welding of DP780 Carbon Steel

    SciTech Connect

    Santella, M. L.; Hovanski, Yuri; Frederick, Alan; Grant, Glenn J.; Dahl, Michael E.

    2009-09-15

    Friction stir spot welds were made in uncoated and galvannneled DP780 sheets using polycrystalline boron nitride stir tools. The tools were plunged at either a single continuous rate or in two segments consisting of a relatively high rate followed by a slower rate of shorter depth. Welding times ranged from 1-10 s. Increasing tool rotation speed from 800 to 1600 rpm increased strength values. The 2-segment welding procedures also produced higher strength joints. Average lap-shear strengths exceeding 10.3 kN were consistently obtained in 4 s on both the uncoated and the galvannealed DP780. The likelihood of diffusion and mechanical interlocking contributing to bond formation was supported by metallographic examinations. A cost analysis based on spot welding in automobile assembly showed that for friction stir spot welding to be economically competitive with resistance spot welding the cost of stir tools must approach that of resistance spot welding electrode tips.

  10. 17. DETAIL VIEW OF WHAT APPEARS TO BE STIRRING FORK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. DETAIL VIEW OF WHAT APPEARS TO BE STIRRING FORK THAT MIXED COFFEE BEANS AS THEY WERE HUSKED - Hacienda Cafetalera Santa Clara, Coffee Mill, KM 19, PR Route 372, Hacienda La Juanita, Yauco Municipio, PR

  11. Effects of friction stir welding on microstructure of 7075 aluminum

    SciTech Connect

    Rhodes, C.G.; Mahoney, M.W.; Bingel, W.H.; Spurling, R.A.; Bampton, C.C.

    1997-01-01

    Friction stir welding is a relatively new technique developed by The Welding Institute (TWI) for the joining of aluminum alloys. The technique, based on friction heating at the faying surfaces of two pieces to be joined, results in a joint created by interface deformation, heat, and solid-state diffusion. In evaluating friction stir welding, critical issues (beyond a sound joint) include microstructure control and localized mechanical property variations. A serious problem with fusion welding, even when a sound weld can be made, is the complete alteration of microstructure and the attendant loss of mechanical properties. Being a solid-state process, friction stir welding has the potential to avoid significant changes in microstructure and mechanical properties. The objective of this study was to evaluate the microstructural changes effected by friction stir welding of 7075 Al.

  12. Thermo-Mechanical Processing in Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Schneider, J. A.; Nunes, A. C., Jr.

    2002-01-01

    In Friction Stir Welding (FSW) a rotating pin-tool inserted into a weld seam literally stirs the edges of the seam together. In this study, two flow paths are proposed that define the FWS zone. Studies using a longitudinal tungsten wire (0.0025 dia.) were used to visualize and document the material flow. The material flow path is described using a mathematical model.

  13. Friction Stir Processing for Efficient Manufacturing

    SciTech Connect

    Mr. Christopher B. Smith; Dr. Oyelayo Ajayi

    2012-01-31

    Friction at contacting surfaces in relative motion is a major source of parasitic energy loss in machine systems and manufacturing processes. Consequently, friction reduction usually translates to efficiency gain and reduction in energy consumption. Furthermore, friction at surfaces eventually leads to wear and failure of the components thereby compromising reliability and durability. In order to reduce friction and wear in tribological components, material surfaces are often hardened by a variety of methods, including conventional heat treatment, laser surface hardening, and thin-film coatings. While these surface treatments are effective when used in conjunction with lubrication to prevent failure, they are all energy intensive and could potentially add significant cost. A new concept for surface hardening of metallic materials and components is Friction Stir Processing (FSP). Compared to the current surface hardening technologies, FSP is more energy efficient has no emission or waste by products and may result in better tribological performance. FSP involves plunging a rotating tool to a predetermined depth (case layer thickness) and translating the FSP tool along the area to be processed. This action of the tool produces heating and severe plastic deformation of the processed area. For steel the temperature is high enough to cause phase transformation, ultimately forming hard martensitic phase. Indeed, FSP has been used for surface modification of several metals and alloys so as to homogenize the microstructure and refine the grain size, both of which led to improved fatigue and corrosion resistance. Based on the effect of FSP on near-surface layer material, it was expected to have beneficial effects on friction and wear performance of metallic materials. However, little or no knowledge existed on the impact of FSP concerning friction and wear performance the subject of the this project and final report. Specifically for steel, which is the most dominant

  14. Flow Trajectories in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Bernstein, Edward L.

    1999-01-01

    In the Friction Stir Welding (FSW) process, a rotating, shouldered tool with a threaded pin is inserted under pressure along the seam of two pieces of metal which are tightly clamped together, and secured against a rigid anvil underneath. The rotating pin travels along the seam and through a combination of pressure and friction heating produces a zone of plastic deformation around the pin within the workpiece on either side of the seam. As the pin is moved in the direction of welding, the plasticised material moves around the tool and bonds together behind it. The elements of the material flow behavior are a combination of three elements. There is a rotational transport of material being carried around the tool, extrusion of material being forced around the pin on both sides into the cavity created behind it, and a lifting and dropping of material as it is stirred and mixed by the rotating action of the pin. It was assumed that rotational motion of the plastic zone is the primary mechanism for transport of material around the welding tool. A kinematic mathematical model was used to compute trajectories of material movement for various distributions of rotational slip within the plastic zone. These trajectories were then compared with the results of an experiment that produced radiographs of markers embedded in a workpiece that was welded with the FSW process. It was assumed that the copper wire markers retained their original length as the aluminum material flowed around them. The kinematic model included a constraint so that the displacements were such that the total length of the wire markers did not increase after deformation. There was good agreement between the calculated trajectories for the case of localized slip at the outer surface of the plastic deformation zone and the radiographs of the copper wire markers. The trajectories differed markedly from the radiograph traces when a distributed slip zone was assumed. It was concluded that the flow field could

  15. Controversial Physics: Perfect Public Outreach Opportunity

    NASA Astrophysics Data System (ADS)

    Thompson, Rebecca

    2012-03-01

    The goal of public outreach is to excite and engage the public in physics. What can be more exciting than controversy? When OPERA announced their discover of superluminal neutrinos, controversy within the physics community quickly followed. This result could overturn a century of established physics. From a public outreach perspective there was no better way to bring people usually unaware of current research into the discussion of this result. If handled well this could be used as a gateway to interest in other physics research. The public drive to learn more about this particular result can be harnessed to create interest in other cutting edge physics research and drive the public to continue their informal physics learning. If the results of OPERA and eventually proven incorrect as many physicists believe they will, that will not erase the public's new-found interest in physics but hopefully continue to fuel it.

  16. Mechanism for Self-Reacted Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Venable, Richard; Bucher, Joseph

    2004-01-01

    A mechanism has been designed to apply the loads (the stirring and the resection forces and torques) in self-reacted friction stir welding. This mechanism differs somewhat from mechanisms used in conventional friction stir welding, as described below. The tooling needed to apply the large reaction loads in conventional friction stir welding can be complex. Self-reacted friction stir welding has become popular in the solid-state welding community as a means of reducing the complexity of tooling and to reduce costs. The main problems inherent in self-reacted friction stir welding originate in the high stresses encountered by the pin-and-shoulder assembly that produces the weld. The design of the present mechanism solves the problems. The mechanism includes a redesigned pin-and-shoulder assembly. The welding torque is transmitted into the welding pin by a square pin that fits into a square bushing with set-screws. The opposite or back shoulder is held in place by a Woodruff key and high-strength nut on a threaded shaft. The Woodruff key reacts the torque, while the nut reacts the tensile load on the shaft.

  17. Comment: An Apparent Controversy in Auroral Physics

    NASA Astrophysics Data System (ADS)

    Haerendel, Gerhard

    2007-03-01

    In his article ``A turning point in auroral physics,'' Bryant argued against what he called the `standard' theory of auroral acceleration, according to which the electrons ``gain their energy from static electric fields,'' and offered wave acceleration as an alternative. Because of the importance of the process, not only for the aurora borealis but also for other cosmic plasmas, a clarification of this apparent controversy seems to be in place.

  18. Controversies in faith and health care.

    PubMed

    Tomkins, Andrew; Duff, Jean; Fitzgibbon, Atallah; Karam, Azza; Mills, Edward J; Munnings, Keith; Smith, Sally; Seshadri, Shreelata Rao; Steinberg, Avraham; Vitillo, Robert; Yugi, Philemon

    2015-10-31

    Differences in religious faith-based viewpoints (controversies) on the sanctity of human life, acceptable behaviour, health-care technologies and health-care services contribute to the widespread variations in health care worldwide. Faith-linked controversies include family planning, child protection (especially child marriage, female genital mutilation, and immunisation), stigma and harm reduction, violence against women, sexual and reproductive health and HIV, gender, end-of-life issues, and faith activities including prayer. Buddhism, Christianity, Hinduism, Islam, Judaism, and traditional beliefs have similarities and differences in their viewpoints. Improved understanding by health-care providers of the heterogeneity of viewpoints, both within and between faiths, and their effect on health care is important for clinical medicine, public-health programmes, and health-care policy. Increased appreciation in faith leaders of the effect of their teachings on health care is also crucial. This Series paper outlines some faith-related controversies, describes how they influence health-care provision and uptake, and identifies opportunities for research and increased interaction between faith leaders and health-care providers to improve health care. PMID:26159392

  19. Nondestructive Ultrasonic Inspection of Friction Stir Welds

    NASA Astrophysics Data System (ADS)

    Tabatabaeipour, M.; Hettler, J.; Delrue, S.; Van Den Abeele, K.

    Friction Stir Welding (FSW) is a relatively new solid-state welding procedure developed at The Welding Institute (TWI-UK) and the technique is widely employed for welding aluminum alloys in various applications. In order to examine the quality of the welds and to detect a variety of welding flaws such as wormholes and root-flaws, it is required to develop a methodical inspection technique that can be used for the identification and localization of such defects. The most prevalent and risky defect in this type of welding is the barely visible root flaw with a length varying from 100-700 μm. Due to the extreme characteristics of the flaw, off-the-shelf ultrasonic weld inspection methods are not always able to readily detect this type of minute defect feature. Here, we propose a novel approach to characterize root flaws using an oblique incident ultrasonic C-scan backscattering analysis. The implementation consists of an immersion ultrasonic testing method in pulse echo (i.e. backscatter) mode with a 3.5 MHz transducer, and makes use of an empirical procedure to engender of a shear wave dominated excitation at the root surface, and to properly gate the received signal for root flaw examination. By scanning the surface above the welded component, a C-scan image displaying the backscatter response from the root surface of the nugget zone can be obtained which allows a simple interpretation of the root flaw status of the weld.

  20. The Plunge Phase of Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    McClure, John C.

    2005-01-01

    The many advantages of Friction Stir Welding have led to a relatively rapid acceptance in the often conservative welding community. Because the process is so different from traditional fusion welding, with which most investigators are most familiar, there remain many aspects of FSW for which there is no clear consensus. For example, the well known onion rings seen in transverse sections have been variously interpreted as grain size variations, variation in density of second phase particles and parts of the carousel of material rotating with the pin that have been shed from the carousel. Using Orientation Imaging Microscopy, Schneider has recently noted that the onion rings have a different orientation (and hence etch differently) than the surrounding material, and this orientation is consistent with slip plane orientations at the edge of the carousel. Likewise, the forces and torque exerted by the FSW tool on the work piece largely remain unaccounted for. Although these forces are routinely measured by investigators with commercial instrumented welders, they are rarely reported or even qualitatively analyzed. This paper will introduce a model based on a carousel or disk of material that rotates with the tool to estimate the torque and plunge force required to plunge a tool into the work piece. A stationary tool is modeled rather than the moving tool because effects such as thermal transients and metallurgical changes in the sample (primarily aging in aluminum) can be more easily accounted for. It is believed, however, that with some modifications the model should be applicable to a moving tool also.

  1. Metal Flow During Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Guerra, M.; Schmidt, C.; McClure, J. C.; Murr, L. E.; Nunes, A. C.; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    The flow of metal during Friction Stir Welding is clarified using a faying surface tracer and a nib frozen in place during welding. It is shown that material is transported by two processes. The first is a wiping of material from the advancing front side of the nib onto a plug of material that rotates and advances with the nib. The material undergoes a helical motion within the plug that both rotates and advances with the plug and descends in the wash of the threads on the nib and rises on the outer part of the plug. After one or more rotations, this material is sloughed off the plug in its wake, primarily on the advancing side. The second process is an entrainment of material from the front retreating side of the nib that fills in between the sloughed off pieces from the advancing side. These two processes produce material with different mechanical properties and the strength of a weld should depend on the relative importance of the processes.

  2. Material Flow During Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Guerra, M.; McClure, J. C.; Murr, L. E.; Nunes, A. C.; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    The flow of metal during Friction Stir Welding is clarified using a faying surface tracer and a nib frozen in place during welding. It is shown that material is transported in two distinct streams or currents. One stream is a wiping of material from the advancing front side of the nib onto a plug of material that rotates and advances with the nib. The material undergoes a helical motion within the plug that both rotates and advances with the plug and descends in the wash of the threads on the nib and rises on the outer part of the plug. After one or more rotations, this material is sloughed off the plug in the wake of the tool primarily on the advancing side. The second stream of material is an entrainment of material from the retreating side of the nib that fills in between the sloughed off pieces from the advancing side. These two processes produce material with different mechanical properties and the strength of a weld should depend on the relative importance of the processes.

  3. Magnetic Properties of Friction Stir Processed Composite

    NASA Astrophysics Data System (ADS)

    Das, Shamiparna; Martinez, Nelson Y.; Das, Santanu; Mishra, Rajiv S.; Grant, Glenn J.; Jana, Saumyadeep; Polikarpov, Evgueni

    2016-07-01

    Of the many existing inspection or monitoring systems, each has its own advantages and drawbacks. These systems are usually comprised of semi-remote sensors that frequently cause difficulty in reaching complex areas of a component. This study proposes to overcome that difficulty by developing embedded functional composites, so that embedding can be achieved in virtually any component part and periodically can be interrogated by a reading device. The "reinforcement rich" processed areas can then be used to record properties such as strain, temperature, and stress state, to name a few, depending on the reinforcement material. Friction stir processing was used to fabricate a magnetostrictive composite by embedding galfenol particles into a nonmagnetic aluminum matrix. The aim was to develop a composite that produces strain in response to a varying magnetic field. Reinforcements were distributed uniformly in the matrix. Magnetization curves were studied using a vibrating sample magnetometer. A simple and cost-effective setup was developed to measure the magnetostrictive strain of the composites. Important factors affecting the magnetic properties were identified and the processing route was modified to improve the magnetic response.

  4. Inspecting Friction Stir Welding using Electromagnetic Probes

    NASA Technical Reports Server (NTRS)

    Kinchen, David G.

    2004-01-01

    A report describes the use of advanced electromagnetic probes to measure the dimensions, the spatial distribution of electrical conductivity, and related other properties of friction stir welds (FSWs) between parts made of the same or different aluminum alloy(s). The probes are of the type described in in another Tech Brief. To recapitulate: A probe of this type is essentially an eddy-current probe that includes a primary (driver) winding that meanders and multiple secondary (sensing) windings that meander along the primary winding. Electrical conductivity is commonly used as a measure of heat treatment and tempering of aluminum alloys, but prior to the development of these probes, the inadequate sensitivity and limited accuracy of electrical-conductivity probes precluded such use on FSWs between different aluminum alloys, and the resolution of those probes was inadequate for measurement of FSW dimensions with positions and metallurgical properties. In contrast, the present probes afford adequate accuracy and spatial resolution for the purposes of measuring the dimensions of FSW welds and correlating spatially varying electrical conductivities with metallurgical properties, including surface defects.

  5. Langangian Particle Model of Friction Stir Welding

    SciTech Connect

    Tartakovsky, Alexandre M.

    2006-12-13

    Since its invention fifteen years ago, Friction Stir Welding (FSW) has found commercial application in the marine, aerospace, rail, and now automotive industries. Development of the FSW process for each new application, however, has remained largely empirical. Few detailed numerical modeling techniques have been developed that can explain and predict important features of the process physics. This is particularly true in the areas of material flow, mixing mechanisms, and void prediction. In this paper we present a novel modeling approach to simulate FSW processes that may have significant advantages over current traditional finite element or finite difference based methods. The proposed model is based on the Smoothed Particle Hydrodynamics (SPH) method. Unlike traditional grid-based methods, Lagrangian particle methods such as SPH can simulate the dynamics of interfaces, large material deformations, void formations and the material's strain and temperature history without employing complex tracking schemes. Two- and three-dimensional FSW simulations for different tool designs are presented. Preliminary numerical results are in qualitative agreement with experimental observations. Detailed comparisons between experimental measurements and larger scale FSW simulations are required to further validate and calibrate the SPH based FSW model.

  6. Magnetic Properties of Friction Stir Processed Composite

    NASA Astrophysics Data System (ADS)

    Das, Shamiparna; Martinez, Nelson Y.; Das, Santanu; Mishra, Rajiv S.; Grant, Glenn J.; Jana, Saumyadeep; Polikarpov, Evgueni

    2016-03-01

    Of the many existing inspection or monitoring systems, each has its own advantages and drawbacks. These systems are usually comprised of semi-remote sensors that frequently cause difficulty in reaching complex areas of a component. This study proposes to overcome that difficulty by developing embedded functional composites, so that embedding can be achieved in virtually any component part and periodically can be interrogated by a reading device. The "reinforcement rich" processed areas can then be used to record properties such as strain, temperature, and stress state, to name a few, depending on the reinforcement material. Friction stir processing was used to fabricate a magnetostrictive composite by embedding galfenol particles into a nonmagnetic aluminum matrix. The aim was to develop a composite that produces strain in response to a varying magnetic field. Reinforcements were distributed uniformly in the matrix. Magnetization curves were studied using a vibrating sample magnetometer. A simple and cost-effective setup was developed to measure the magnetostrictive strain of the composites. Important factors affecting the magnetic properties were identified and the processing route was modified to improve the magnetic response.

  7. System for Controlling the Stirring Pin of a Friction Stir Welding Apparatus

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor); Romine, Peter L. (Inventor); Oelgoetz, Peter A. (Inventor)

    2002-01-01

    A control is provided for a friction stir welding apparatus comprising a pin tool which includes a shoulder and a rotating pin extending outwardly from the shoulder of the pin tool and which, in use, is plunged into a workpiece formed contacting workpiece members to stir weld the members together. The control system controls the penetration of the pin tool into the workpiece members which are mounted on a support anvil. The control system includes a pin length controller for controlling pin length relative to the shoulder and for producing a corresponding pin length signal. A pin force sensor senses the force being exerted on the pin during welding and produces a corresponding actual pin force signal. A probe controller controls a probe extending outwardly from the pin, senses a parameter related to the distance between the probe and the supporting anvil and produces a corresponding probe signal. A workpiece standoff sensor senses the standoff distance between the workpiece and the standoff sensor and produces a corresponding standoff signal. A control unit receives the various signals, together with a weld schedule, and, based on these signals and the weld schedule, controls the pin length controller so as to control pin penetration into the workpiece.

  8. Thermal Stir Welding Development at Marshall Space Flight Center

    NASA Technical Reports Server (NTRS)

    Ding, Robert J.

    2008-01-01

    Solid state welding processes have become the focus of welding process development at NASA's Marshall Space Flight Center. Unlike fusion weld processes such as tungsten inert gas (TIG), variable polarity plasma arc (VPPA), electron beam (EB), etc., solid state welding processes do not melt the material during welding. The resultant microstructure can be characterized as a dynamically recrystallized morphology much different than the casted, dentritic structure typical of fusion weld processes. The primary benefits of solid state processes over fusion weld processes include superior mechanic properties and the elimination of thermal distortion and residual stresses. These solid state processes attributes have profoundly influenced the direction of advanced welding research and development within the NASA agency. Thermal Stir Welding (TSW) is a new solid state welding process being developed at the Marshall Space Flight Center. Unlike friction stir welding, the heating, stirring and forging elements of the weld process can be decoupled for independent control. An induction coil induces energy into a workpiece to attain a desired plastic temperature. An independently controlled stir rod, captured within non-rotating containment plates, then stirs the plasticized material followed by forging plates/rollers that work the stirred weld joint. The independent control (decoupling) of heating, stirring and forging allows, theoretically, for the precision control of microstructure morphology. The TSW process is being used to evaluate the solid state joining of Haynes 230 for ARES J-2X applications. It is also being developed for 500-in (12.5 mm) thick commercially pure grade 2 titanium for navy applications. Other interests include Inconel 718 and stainless steel. This presentation will provide metallurgical and mechanical property data for these high melting temperature alloys.

  9. Early Controversies Over Athetosis: II. Treatment

    PubMed Central

    Lanska, Douglas J.

    2013-01-01

    Background Athetosis has been controversial since it was first described by William Hammond in 1871; many aspects of Hammond’s career were equally controversial. Methods Primary sources have been used to review treatment controversies in the 50-year period following the initial description of athetosis. Results The treatments used most commonly employed available pharmaceutical agents and modalities (e.g., galvanism). Initial anecdotal reports of success were seldom confirmed with subsequent experience. Several novel invasive therapies were also developed and promoted, all of which damaged or destroyed either upper or lower motor neuron pathways, and were also often associated with high mortality rates. In general, these therapies substituted paresis for abnormal spontaneous movements. These included peripheral nerve stretching, excision of a portion of the precentral gyrus, rhizotomy, nerve “transplantation” (i.e., neurotomy and nerve-to-nerve anastomoses), and “muscle group isolation” (i.e., alcohol neurolysis). There was no agreement on the appropriateness of such high-risk procedures, particularly given the intentional generation of further neurological morbidity. Discussion Pharmaceutical agents and modalities initially employed for athetosis had little a priori evidence-based justification and no biologically plausible theoretical framework to guide empiric treatment selection. Subsequently, all the invasive procedures employed were directed at lessening or removing the manifestations, rather than the underlying cause, of the abnormal central nervous system “irritation,” usually by imposing paresis or paralysis. Factors contributing to the disparity in outcomes between favorable initial reports and the often-disappointing results of later studies included reliance on anecdotal reports or small uncontrolled case series, placebo effects, biased observation, misdiagnosis, and biased reporting. PMID:23450199

  10. Treatment of genital warts: facts and controversies.

    PubMed

    Wolf, Ronni; Davidovici, Batya

    2010-01-01

    There are two opposing approaches in the treatment of genital warts: (1) the traditional approach advocates complete elimination of all lesions, and (2) a second approach regards condyloma as merely a cosmetic nuisance. After a long journey through many arguments and scientific papers, we have concluded that many unknowns, uncertainties, and controversies concerning the value of treatment of genital warts in terms of clearing and curing the disease (ie, eradicating the viruses, preventing cancer, and reducing infectivity). There is no consensus at present of whether treatment of men with evidence of genital human papillomavirus infection influences the natural history of their female sex partner's cervical disease. PMID:20797516

  11. Breast Cancer Screening Benefits: Research and Controversies.

    PubMed

    Odle, Teresa G

    2016-05-01

    The debate regarding the efficacy of breast cancer screening with mammography has intensified since about 2009, as the literature has reported on benefits, harms, and effectiveness of the technology in breast cancer diagnosis. As a result, women and their referring clinicians have been confused by conflicting reports in medical journals and the media. This article provides an overview of research and methodology used to generate these reports and the effects of contradictory research, screening recommendation changes, and the controversy over mammography efficacy on patients and the public. PMID:27146193

  12. Controversies in ureteroscopy: Wire, basket, and sheath

    PubMed Central

    Rizkala, Emad R; Monga, Manoj

    2013-01-01

    In the last one to two decades, flexible ureteroscopy has rapidly expanded its role in the treatment of urologic stone disease. With the frequent and expanded use of flexible ureteroscopy, other ancillary instruments were developed in order to ease and facilitate this technique, such as ureteral access sheaths (UAS) and a variety of wires and baskets. These developments, along with improved surgeon ureteroscopic competence, have often brought into question the need to implement the “traditional technique” of flexible ureteroscopy. In this review, we discuss a brief history of flexible ureteroscopy, its expanded indications, and the controversy surrounding the use of UAS, wires, and baskets. PMID:24082447

  13. Intellectual property and information controversy (II)

    NASA Astrophysics Data System (ADS)

    Aoyama, Hirokazu

    As advanced information has been proceeded rapidly, intellectual property has become more important than ever as business resources of enterprises. Based on the former report by the author "present status of and trend in intellectual property" this paper describes "information" related intellectual property controversy which have been occurred, that is, 1) affairs related to computer hardwares and softwares (the case of compatible machines and OS, the case of application softwares, computer crimes) and 2) affairs on trade secret (the case of revealing enterprises'secret, the case of industrial espionage). It also discusses how intellectual property should be protected and utilized from now on.

  14. Distal radius fracture: diagnosis, treatment, and controversies.

    PubMed

    Tang, Jin Bo

    2014-07-01

    This article presents the diagnosis and treatment of distal radius fractures with emphasis on (1) current common principles, (2) the author's current practices, and (3) controversies. The author emphasizes that displaced distal radius fractures should be approached first with a trial of closed reduction, with or without percutaneous pinning. If this reduction is unstable or unsuccessful, open reduction is indicated. Early treatments include percutaneous pinning through the distal radioulnar joint, early or delayed reattachment/repair of the avulsed dorsal periphery of the triangular fibrocartilage complex (TFCC), reattachment of the TFCC to the ulna fovea, and late reconstruction. PMID:24996466

  15. Injectables in the Nose: Facts and Controversies.

    PubMed

    Thomas, William Walsh; Bucky, Lou; Friedman, Oren

    2016-08-01

    Nasal injectables and surface treatments alter the appearance of the nose both primarily and following nasal surgery. Fillers such as hyaluronic acids, calcium hydroxyapatite, and fat have a variety of advantages and disadvantages in eliminating small asymmetries postrhinoplasty. All nasal injectables have rare but severe ocular and cerebral ischemic complications. The injection of steroids following nasal reconstruction has a role in preventing supratip swelling and can improve the appearance of grafts to the nose. Resurfacing techniques reduce the appearance of autotransplanted grafts to the nose; there is little controversy about their benefit but surgeon preference for timing is varied. PMID:27400851

  16. Bioavailability of the polyphenols: status and controversies.

    PubMed

    D'Archivio, Massimo; Filesi, Carmelina; Varì, Rosaria; Scazzocchio, Beatrice; Masella, Roberta

    2010-01-01

    The current interest in polyphenols has been driven primarily by epidemiological studies. However, to establish conclusive evidence for the effectiveness of dietary polyphenols in disease prevention, it is useful to better define the bioavailability of the polyphenols, so that their biological activity can be evaluated. The bioavailability appears to differ greatly among the various phenolic compounds, and the most abundant ones in our diet are not necessarily those that have the best bioavailability profile. In the present review, we focus on the factors influencing the bioavailability of the polyphenols. Moreover, a critical overview on the difficulties and the controversies of the studies on the bioavailability is discussed. PMID:20480022

  17. Extracorporeal life support: updates and controversies.

    PubMed

    Gadepalli, Samir K; Hirschl, Ronald B

    2015-02-01

    The use of Extracorporeal Life Support (ECLS) in children and adults has markedly increased during the past few years with over 4000 patients placed on ECLS every year in over 200 centers. This article focuses on updates to the physiology and mechanics of ECLS with use of magnetically levitated centrifugal pumps, hollow-fiber gas-exchange devices, and bi-caval dual-lumen catheters. We also explore controversies in management including indications, cannulation approaches, renal replacement, monitoring of anticoagulation, early ambulation, and termination of ECLS. Finally, we present changes in the systems that provide ECLS including the single-provider model and regionalization of care. PMID:25639803

  18. Retroperitoneal Sarcoma: Fact, Opinion, and Controversy.

    PubMed

    Gladdy, Rebecca A; Gupta, Abha; Catton, Charles N

    2016-10-01

    After diagnosis of retroperitoneal sarcoma (RPS), detailed imaging and multidisciplinary discussion should guide treatment including surgical resection and in select cases, neoadjuvant therapy. Local recurrence is common in RPS and is associated with grade, histologic subtype, completeness of resection, and size. As guidelines to standardize RPS patient management emerge, expert pathologic assessment and management in centers of excellence are benchmarks of quality of care. The efficacy of current chemotherapy is limited and there is a critical need to understand the molecular basis of sarcoma so that new drug therapies are developed. Multicenter clinical trials are needed to limit opinion and controversy in this complex and challenging disease. PMID:27591493

  19. Bioavailability of the Polyphenols: Status and Controversies

    PubMed Central

    D’Archivio, Massimo; Filesi, Carmelina; Varì, Rosaria; Scazzocchio, Beatrice; Masella, Roberta

    2010-01-01

    The current interest in polyphenols has been driven primarily by epidemiological studies. However, to establish conclusive evidence for the effectiveness of dietary polyphenols in disease prevention, it is useful to better define the bioavailability of the polyphenols, so that their biological activity can be evaluated. The bioavailability appears to differ greatly among the various phenolic compounds, and the most abundant ones in our diet are not necessarily those that have the best bioavailability profile. In the present review, we focus on the factors influencing the bioavailability of the polyphenols. Moreover, a critical overview on the difficulties and the controversies of the studies on the bioavailability is discussed. PMID:20480022

  20. Media Coverage and Public Opinion on Scientific Controversies.

    ERIC Educational Resources Information Center

    Mazur, Allan

    1981-01-01

    Examines the relationship of media coverage and public opinion in scientific controversy. A survey of coverage of controversies arising regarding sociobiology, water fluoridation, nuclear power and the Three Mile Island disaster indicates that the media play an active role in shaping and constructing controversy rather than just reporting it. (JMF)

  1. Creationism and Evolution: A Systems Perspective on a Textbook Controversy.

    ERIC Educational Resources Information Center

    Thompson, Patricia J.

    This paper addresses the effects of the controversies involved in one state's decision to exclude the study of evolution from its science curriculum and to require equal time for creationism as an alternative theory. Curricula and textbooks are examined for the impacts of evolutionary and creationist controversies. The controversy is discussed…

  2. Glaciers in Patagonia: Controversy and prospects

    NASA Astrophysics Data System (ADS)

    Kargel, J. S.; Alho, P.; Buytaert, W.; Célleri, R.; Cogley, J. G.; Dussaillant, A.; Guido, Z.; Haeberli, W.; Harrison, S.; Leonard, G.; Maxwell, A.; Meier, C.; Poveda, G.; Reid, B.; Reynolds, J.; Rodríguez, C. A. Portocarrero; Romero, H.; Schneider, J.

    2012-05-01

    Lately, glaciers have been subjects of unceasing controversy. Current debate about planned hydroelectric facilities—a US7- to 10-billion megaproject—in a pristine glacierized area of Patagonia, Chile [Romero Toledo et al., 2009; Vince, 2010], has raised anew the matter of how glaciologists and global change experts can contribute their knowledge to civic debates on important issues. There has been greater respect for science in this controversy than in some previous debates over projects that pertain to glaciers, although valid economic motivations again could trump science and drive a solution to the energy supply problem before the associated safety and environmental problems are understood. The connection between glaciers and climate change—both anthropogenic and natural—is fundamental to glaciology and to glaciers' practical importance for water and hydropower resources, agriculture, tourism, mining, natural hazards, ecosystem conservation, and sea level [Buytaert et al., 2010; Glasser et al., 2011]. The conflict between conservation and development can be sharper in glacierized regions than almost anywhere else. Glaciers occur in spectacular natural landscapes, but they also supply prodigious exploitable meltwater.

  3. Sugar substitutes: Health controversy over perceived benefits

    PubMed Central

    Tandel, Kirtida R.

    2011-01-01

    Sugar is an inseparable part of the food we consume. But too much sugar is not ideal for our teeth and waistline. There have been some controversial suggestions that excessive sugar may play an important role in certain degenerative diseases. So artificial sweeteners or artificially sweetened products continue to attract consumers. A sugar substitute (artificial sweetener) is a food additive that duplicates the effect of sugar in taste, but usually has less food energy. Besides its benefits, animal studies have convincingly proven that artificial sweeteners cause weight gain, brain tumors, bladder cancer and many other health hazards. Some kind of health related side effects including carcinogenicity are also noted in humans. A large number of studies have been carried out on these substances with conclusions ranging from “safe under all conditions” to “unsafe at any dose”. Scientists are divided in their views on the issue of artificial sweetener safety. In scientific as well as in lay publications, supporting studies are often widely referenced while the opposing results are de-emphasized or dismissed. So this review aims to explore the health controversy over perceived benefits of sugar substitutes. PMID:22025850

  4. Bleeding Avoidance Strategies: Consensus and Controversy

    PubMed Central

    Dauerman, Harold L.; Rao, Sunil V.; Resnic, Frederic S.; Applegate, Robert J.

    2011-01-01

    Bleeding complications after coronary intervention are associated with prolonged hospitalization, increased hospital costs, patient dissatisfaction, morbidity and one year mortality. Bleeding Avoidance Strategies represent a term incorporating multiple modalities that aim to reduce bleeding and vascular complications after cardiovascular catheterization. Recent improvements in the rates of bleeding complications after invasive cardiovascular procedures suggests that the clinical community has successfully embraced specific strategies and improved patient care in this area. There remains controversy regarding the efficacy, safety and/or practicality of 3 key bleeding avoidance strategies for cardiac catheterization and coronary intervention: procedural (radial artery approach, safezone arteriotomy), pharmacologic (multiple agents) and technological (vascular closure devices) approaches to improved access. In this article, we address areas of consensus with respect to selected modalities in order to define the role of each strategy in current practice. Furthermore, we focus on areas of controversy for selected modalities in order to define key areas warranting cautious clinical approaches and the need for future randomized clinical trials in this area. PMID:21700085

  5. Breast cancer screening: controversy of impact.

    PubMed

    Berry, Donald A

    2013-08-01

    Few medical issues have been as controversial--or as political, at least in the United States-as the role of mammographic screening for breast cancer. The advantages of finding a cancer early seem obvious. Indeed, randomized trials evaluating screening mammography demonstrate a reduction in breast cancer mortality, but the benefits are less than one would hope. Moreover, the randomized trials are themselves subject to criticism, including that they are irrelevant in the modern era because most were conducted before chemotherapy and hormonal therapy became widely used. In this article I chronicle the evidence and controversies regarding mammographic screening, including attempts to assess the relative contributions of screening and therapy in the substantial decreases in breast cancer mortality that have been observed in many countries over the last 20-25 years. I emphasize the trade-off between harms and benefits depending on the woman's age and other risk factors. I also discuss ways for communicating the associated risks to women who have to decide whether screening (and what screening strategy) is right for them. PMID:24074796

  6. Current Controversies With Recent Cholesterol Treatment Guidelines.

    PubMed

    Phillips, Elizabeth; Saseen, Joseph J

    2016-02-01

    Several guidelines and expert recommendations have been published recently regarding the prevention and treatment of atherosclerotic cardiovascular disease (ASCVD) risk. The American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend a drastic paradigm change in the treatment of cholesterol where treatment, based on level of cardiovascular risk, is based around using a fixed statin intensity therapy. This approach is endorsed by the American Diabetes Association. However, recommendations by the National Lipid Association (NLA) consist of the traditional approach of titrating therapy to achieve patient-specific lipoprotein targets. Despite the differences in overall approaches, the use of statin therapy as the cornerstone of treatment to reduce risk of cardiovascular events in at risk patients is a strong common theme. Clinicians should be aware of these differences, as they represent controversies with the overall treatment of ASCVD risk. Additional controversies related to the treatment of patients with ASCVD risk pertain to the role of nonstatin drugs and approaches to managing side effects. These topics are reviewed within this article and discuss implications for patient care. PMID:26611871

  7. Controversies in cancer pain. Medical perspectives.

    PubMed

    Foley, K M

    1989-06-01

    The treatment of pain in the patient with cancer has focused attention on a series of controversial issues involving medical, social, and moral factors. The medical factors include a lack of knowledge on the part of health care professionals regarding the rational use of opioid drugs. This is coupled with real limitations in the general understanding of the mechanisms of pain and its treatment using pharmacologic, anesthetic, and neurosurgical approaches. Several pharmacologic controversies, including the choice of drug, route and method of administration, and tolerance development and risk of substance abuse, have emerged with the use of opioids on a chronic basis in the cancer population. The social and moral implications involve the issue of who will pay for high technology pain management approaches for patients either at home or in hospice care and the ethical considerations in managing pain with opioid drugs. Carefully designed studies to assess these factors, coupled with broad educational programs, will improve the care of cancer patients in pain and expand our understanding of these important issues. PMID:2566369

  8. Gardnerella vaginalis: characteristics, clinical considerations, and controversies.

    PubMed Central

    Catlin, B W

    1992-01-01

    The clinical significance, Gram stain reaction, and genus affiliation of Gardnerella vaginalis have been controversial since Gardner and Dukes described the organism as the cause of "nonspecific vaginitis," a common disease of women which is now called bacterial vaginosis. The organism was named G. vaginalis when taxonomic studies showed that it was unrelated to bacteria in various genera including Haemophilus and Corynebacterium. Electron microscopy and chemical analyses have elucidated the organism's gram-variable reaction. Controversy over the etiology of bacterial vaginosis was largely resolved by (i) studies using improved media and methods for the isolation and identification of bacteria in vaginal fluids and (ii) standardization of criteria for clinical and laboratory diagnosis. Besides G. vaginalis, Mobiluncus spp., Mycoplasma hominis, and certain obligate anaerobes are now acknowledged as participants in bacterial vaginosis. The finding that G. vaginalis, Mobiluncus spp., and M. hominis inhabit the rectum indicates a potential source of autoinfection in addition to sexual transmission. Extravaginal infections with G. vaginalis are increasingly recognized, especially when the toxic anticoagulant polyanetholesulfonate is omitted from blood cultures and when urine cultures are incubated anaerobically for 48 h. The finding that mares harbor G. vaginalis suggests that an equine model can be developed for studies of Gardnerella pathogenesis. Images PMID:1498765

  9. A Brief Introduction to the Theory of Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C., Jr.

    2008-01-01

    Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and is already an important welding process for the aerospace industry, where welds of optimal quality are demanded. The structure of welds determines weld properties. The structure of friction stir welds is determined by the flow field in the weld metal in the vicinity of the weld tool. A simple kinematic model of the FSW flow field developed at Marshall Space Flight Center, which enables the basic features of FSW microstructure to be understood and related to weld process parameters and tool design, is explained.

  10. Weld Nugget Temperature Control in Thermal Stir Welding

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2014-01-01

    A control system for a thermal stir welding system is provided. The control system includes a sensor and a controller. The sensor is coupled to the welding system's containment plate assembly and generates signals indicative of temperature of a region adjacent and parallel to the welding system's stir rod. The controller is coupled to the sensor and generates at least one control signal using the sensor signals indicative of temperature. The controller is also coupled to the welding system such that at least one of rotational speed of the stir rod, heat supplied by the welding system's induction heater, and feed speed of the welding system's weld material feeder are controlled based on the control signal(s).

  11. Vortex excitation in a stirred toroidal Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Yakimenko, A. I.; Isaieva, K. O.; Vilchinskii, S. I.; Ostrovskaya, E. A.

    2015-02-01

    Motivated by a recent experiment [K. C. Wright et al., Phys. Rev. A 88, 063633 (2013), 10.1103/PhysRevA.88.063633], we investigate the microscopic mechanism for excitation of vortices and formation of a persistent current in an annular BEC stirred by a narrow blue-detuned optical beam. In the framework of a two-dimensional mean-field model, we study the dissipative dynamics of the condensate with parameters that reflect realistic experimental conditions. Vortex-antivortex pairs appear near the center of the stirrer in the bulk of the condensate for slow motion of the stirring beam. When the barrier angular velocity is above some critical value, an outer edge surface mode develops and breaks into the vortices entering the condensate annulus. We determine the conditions for creation of vortex excitations in the stirred toroidal condensate and compare our results with experimental observations.

  12. Program plan: DWPF/HLWDP stirred Melter Program Plan

    SciTech Connect

    Smith, M.E.

    1994-02-28

    Slurry Fed Melters (SFM) have been developed in the United States, Europe, and Japan for the conversion of high-level radioactive waste (HLW) to borosilicate glass for permanent disposal. The newest design, the stirred melter, combines the high production rates and high glass quality features of the Joule-heated melters with the low-cost, compact, simple maintenance features of the pot melters. However, further engineering design and demonstrations are needed to operate the stirred melter on a large scale. This document outlines the program which develops a full scale stirred melter for the DWPF (240 pph), and provides a basis which will allow further scale-up of the technology for use in the Hanford High Level Waste Disposal Program (HLWDP) for up to four times the reference capacity.

  13. Wet gringing of zeolite in stirred media mill

    NASA Astrophysics Data System (ADS)

    Mucsi, G.; Bohács, K.

    2016-04-01

    In the present study the results of systematic experimental series are presented with the specific goal of optimizing the zeolite nanoparticles' production using a wet stirred media mill. The diameter of the grinding media as well as the rotor velocity were varied in the experiments. Particle size distribution and "outer" specific surface area of the ground samples were measured by a laser particle size analyser. Additionally, BET, XRD and FT-IR analyses were performed for the characterization of the "total" specific surface area as well as the crystalline and material structure, respectively. Based on the results of the laboratory experiments it was found that wet stirred media milling provided significant reductions in the particle size of zeolite. Furthermore, the crystallinity of the samples also decreased, so not only the physical but the mineralogical characteristics of zeolite can be controlled by stirred media milling.

  14. Friction stir welding process to repair voids in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Rosen, Charles D. (Inventor); Litwinski, Edward (Inventor); Valdez, Juan M. (Inventor)

    1999-01-01

    The present invention provides an in-process method to repair voids in an aluminum alloy, particularly a friction stir weld in an aluminum alloy. For repairing a circular void or an in-process exit hole in a weld, the method includes the steps of fabricating filler material of the same composition or compatible with the parent material into a plug form to be fitted into the void, positioning the plug in the void, and friction stir welding over and through the plug. For repairing a longitudinal void (30), the method includes machining the void area to provide a trough (34) that subsumes the void, fabricating filler metal into a strip form (36) to be fitted into the trough, positioning the strip in the trough, and rewelding the void area by traversing a friction stir welding tool longitudinally through the strip. The method is also applicable for repairing welds made by a fusing welding process or voids in aluminum alloy workpieces themselves.

  15. Process Model for Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Adams, Glynn

    1996-01-01

    Friction stir welding (FSW) is a relatively new process being applied for joining of metal alloys. The process was initially developed by The Welding Institute (TWI) in Cambridge, UK. The FSW process is being investigated at NASA/MSEC as a repair/initial weld procedure for fabrication of the super-light-weight aluminum-lithium shuttle external tank. The FSW investigations at MSFC were conducted on a horizontal mill to produce butt welds of flat plate material. The weldment plates are butted together and fixed to a backing plate on the mill bed. A pin tool is placed into the tool holder of the mill spindle and rotated at approximately 400 rpm. The pin tool is then plunged into the plates such that the center of the probe lies at, one end of the line of contact, between the plates and the shoulder of the pin tool penetrates the top surface of the weldment. The weld is produced by traversing the tool along the line of contact between the plates. A lead angle allows the leading edge of the shoulder to remain above the top surface of the plate. The work presented here is the first attempt at modeling a complex phenomenon. The mechanical aspects of conducting the weld process are easily defined and the process itself is controlled by relatively few input parameters. However, in the region of the weld, plasticizing and forging of the parent material occurs. These are difficult processes to model. The model presented here addresses only variations in the radial dimension outward from the pin tool axis. Examinations of the grain structure of the weld reveal that a considerable amount of material deformation also occurs in the direction parallel to the pin tool axis of rotation, through the material thickness. In addition, measurements of the axial load on the pin tool demonstrate that the forging affect of the pin tool shoulder is an important process phenomenon. Therefore, the model needs to be expanded to account for the deformations through the material thickness and the

  16. Mechanistic Models of Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Stewart, Michael B.

    1998-01-01

    Friction stir welding is a welding process developed at The Welding Institute (TWI) in England. The method uses very large strain plastic deformation of the material to join two pieces of metal together. The material is deformed using a tool which is forced between the two pieces which rotates causing a bond. Beyond this, very little is actually known although many people working in the field are willing to speculate on the detailed mechanisms involved. Some measurements made using sacrificial thermocouples at the weld joint indicate that the maximum temperature during the weld process is on the order of 370C - well below the melting temperature of the material. However, at this temperature, the material properties are highly temperature dependent, and the yield stress is approximately an order of magnitude less at this temperature than it is at room temperature. As expected, there are many interpretations of the physical mechanisms occurring during the weld process. Although there is very little published concerned with FSW, some of the anecdotal theories will be described. One describes the primary mechanism as frictional heating at the front of the tool caused by slip between the tool and the material. At elevated temperatures, the weld material becomes soft and deforms around the tool but not essentially altered by the tool rotation, similar to an extrusion. As the material meets again at the rear of the tool, the temperatures and pressures are sufficient to cause the material to bond. All other structures seen are secondary and unimportant. Another theory examined last summer at NASA's Marshall Space Flight Center (MSFC) was that there was no slip between the tool and the material resulting in a rotating mass of plastic weld material traveling at a variety of angular velocities - the greatest at the tool surface diminishing to zero at the outer edge of the plastic mass surrounding the tool. This conceptual model was followed by simplified calculations which

  17. Microstructural issues in a friction-stir-welded aluminum alloy

    SciTech Connect

    Flores, O.V.; Kennedy, C.; Murr, L.E.; Brown, D.; Pappu, S.; Nowak, B.M.; McClure, J.C.

    1998-02-03

    Recent observations of microstructures associated with friction-stir welding (FSW) in a number of aluminum alloys have consistently demonstrated the actual weld zone to consist of a (dynamically) recrystallized grain structure resulting from the extreme, solid-state, plastic deformation characterizing the process. Because of solubilities associated with the various precipitates in 7075 and 6061 aluminum alloys, and the fact that the precipitates were either homogeneously distributed throughout both the original (unwelded) work-piece plates and the well zones (or formed varying densities of Widmanstaetten patterns within the original and recrystallized grains), it has been difficult to follow the stirring of stable, second-phase particles from the base metal (work-piece) into the weld zone. In the present investigation, a compositionally modified 1100 aluminum alloy (nominally 99.2% Al, 0.5% Fe, 0.15% Cu, 0.12% Si, 0.05 Mn, 0.04 Ti, balance in weight percent of Be and Mg), forming a stable microdendritic (second-phase), equiaxed, cell structure was friction-stir welded. These thermally stable, geometrically specific, precipitates in the base metal were compared with their disposition within the friction-stir-weld zone. In addition, as-cast plates of this alloy were cold-rolled 50% and friction-stir-welded in order to compare these two schedules (as-cast and 50% cold-rolled) in terms of residual hardness variations and related microstructural issues as well as the effect of prior deformation on the friction-stir welding process.

  18. Heat Control via Torque Control in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Venable, Richard; Colligan, Kevin; Knapp, Alan

    2004-01-01

    In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or friction stir welding). In fusion welding, measurement and control of heat input is a difficult problem. However, in friction stir welding, the basic principle of operation affords the potential of a straightforward solution: Neglecting thermal losses through the pin and the spindle that supports it, the rate of heat input to the workpiece is the product of the torque and the speed of rotation of the friction stir weld pin and, hence, of the spindle. Therefore, if one acquires and suitably processes data on torque and rotation and controls the torque, the rotation, or both, one should be able to control the heat input into the workpiece. In conventional practice in friction stir welding, one uses feedback control of the spindle motor to maintain a constant speed of rotation. According to the proposal, one would not maintain a constant speed of rotation: Instead, one would use feedback control to maintain a constant torque and would measure the speed of rotation while allowing it to vary. The torque exerted on the workpiece would be estimated as the product of (1) the torque-multiplication ratio of the spindle belt and/or gear drive, (2) the force measured by a load cell mechanically coupled to the spindle motor, and (3) the moment arm of the load cell. Hence, the output of the load cell would be used as a feedback signal for controlling the torque (see figure).

  19. FRICTION STIR SPOT WELDING OF 6016 ALUMINUM ALLOY

    SciTech Connect

    Mishra, Rajiv S.; Webb, S.; Freeney, T. A.; Chen, Y. L.; Gayden, X.; Grant, Glenn J.; Herling, Darrell R.

    2007-01-08

    Friction stir spot welding (FSSW) of 6016 aluminum alloy was evaluated with conventional pin tool and new off-center feature tools. The off-center feature tool provides significant control over the joint area. The tool rotation rate was varied between 1000 and 2500 rpm. Maximum failure strength was observed in the tool rotation range of 1200-1500 rpm. The results are interpreted in the context of material flow in the joint and influence of thermal input on microstructural changes. The off-center feature tool concept opens up new possibilities for plunge-type friction stir spot welding.

  20. Friction stir weld tools having fine grain structure

    DOEpatents

    Grant, Glenn J.; Frye, John G.; Kim, Jin Yong; Lavender, Curt A.; Weil, Kenneth Scott

    2016-03-15

    Tools for friction stir welding can be made with fewer process steps, lower cost techniques, and/or lower cost ingredients than other state-of-the-art processes by utilizing improved compositions and processes of fabrication. Furthermore, the tools resulting from the improved compositions and processes of fabrication can exhibit better distribution and homogeneity of chemical constituents, greater strength, and/or increased durability. In one example, a friction stir weld tool includes tungsten and rhenium and is characterized by carbide and oxide dispersoids, by carbide particulates, and by grains that comprise a solid solution of the tungsten and rhenium. The grains do not exceed 10 micrometers in diameter.

  1. Unraveling the Processing Parameters in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Schneider, Judy; Nunes, Arthur C., Jr.

    2005-01-01

    In friction stir welding (FSW), a rotating threaded pin tool is translated along a weld seam, literally stirring the edges of the seam together. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path or paths is required. In this study, various markers are used to trace the flow paths of the metal. X-ray radiographs record the segmentation and position of the wire. Several variations in the trajectories can be differentiated within the weld zone.

  2. Near Net Manufacturing Using Thin Gage Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Takeshita, Jennifer; Potter, David; Holquin, Michael

    2006-01-01

    Friction Stir Welding (FSW) and near net spin forming of FSW aluminumn blanks were investigated for large-scale pressure vessel applications. With a specific focus on very thin gage 2xxx and 7xxx aluminum alloys, the program concentrated on the following: the criteria used for material selection, a potential manufacturing flow, and the effectiveness and associated risks of near net spin forming. Discussion will include the mechanical properties of the friction stir welds and the parent material from before and after the spin forming process. This effort was performed under a NASA Space Exploration initiative focused on increasing the affordability, reliability and performance of pressure vessels larger than 10 ft. diameter.

  3. Characterization of the Micro Textures in a Friction Stir Weld

    NASA Technical Reports Server (NTRS)

    Schneider, Judy; Nunes, Arthur C.

    2004-01-01

    In friction stir welding (FSW), a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. The Dynamically-Recrystallized-Zone (DXZ) of a polished and etched FSW cross-section exhibits contrasting bands (the "onion-ring" structure), the origins of which are unclear. An orientation image mapping (OIM) study suggests that the corresponding bands may correspond respectively to a "straight-through" current of metal bypassing the pin tool in a single rotation or less and a "maelstrom" current rotating a number of times around the pin tool.

  4. Nonisothermal water transport through hydrophobic membranes in a stirred cell

    SciTech Connect

    Vazquez-Gonzalez, M.I.; Martinez, L.

    1994-10-01

    This paper studies the transport of pure water through microporous hydrophobic membranes in a stirred cell when bathed by two phases at different temperatures. The dependence of the phenomena on the stirring rate and on the average temperature has been investigated. The influence of these operating conditions on the mass transfer rate is discussed while keeping in mind the theories of mass and heat transfer within the membrane and adjoining liquids. The concept of temperature polarization is introduced in the transport equations, and it is shown to be important in the interpretation of our experimental results.

  5. Seam-Tracking for Friction Stir Welded Lap Joints

    NASA Astrophysics Data System (ADS)

    Fleming, Paul A.; Hendricks, Christopher E.; Cook, George E.; Wilkes, D. M.; Strauss, Alvin M.; Lammlein, David H.

    2010-11-01

    This article presents a method for automatic seam-tracking in friction stir welding (FSW) of lap joints. In this method, tracking is accomplished by weaving the FSW tool back-and-forth perpendicular to the direction of travel during welding and monitoring force and torque signals. Research demonstrates the ability of this method to automatically track weld seam positions. Additionally, tensile and S-bend test result comparisons demonstrate that weaving most likely does not reduce weld quality. Finally, benefits of this weave-based method to FSW of lap joints are discussed and methods for incorporating it into existing friction stir welding control algorithms (such as axial load control) are examined.

  6. Heat Treatment of Friction Stir Welded 7X50 Aluminum

    NASA Technical Reports Server (NTRS)

    Petter, George E. (Inventor); Figert, John D. (Inventor); Rybicki, Daniel J. (Inventor); Burnes, Timothy H. (Inventor)

    2004-01-01

    A method for treating alloy before and after friction stir welding, the method comprising the following steps. First solution heat treating a multiplicity of aluminum-zinc alloy engineered components for a first time period at a first temperature. First air cooling the components in ambient air at room temperatwe until the components are cooled to room temperature. Friction stir welding the components to form an assembly. Second solution heat treating the assembly for a second time period at a second temperature. Additional steps and embodiments are considered.

  7. Current questions and possible controversies in autophagy

    PubMed Central

    Lindqvist, L M; Simon, A K; Baehrecke, E H

    2015-01-01

    Interest in autophagy has exploded over the last decade, with publications highlighting crosstalk with several other cellular processes including secretion, endocytosis, and cell suicide pathways including apoptosis. Autophagy proteins have also been implicated in other cellular processes independently of their roles in autophagy, creating complexities in the interpretation of autophagy (Atg) mutant gene data. Interestingly, this self-eating process is a survival mechanism that can also promote cell death, but when and how autophagy may ‘switch’ its function is still under debate. Indeed, there are currently many models of how autophagy actually influences cell death. In this review, we highlight some outstanding questions and possible controversies in the autophagy field. PMID:26682061

  8. Lung Cancer—Current Concepts and Controversies

    PubMed Central

    Pett, Stuart B.; Wernly, Jorge A.; Akl, Bechara F.

    1986-01-01

    The recent literature contains a variety of controversial management alternatives for patients with pulmonary malignancy that affect all aspects of the lung cancer problem. Revisions in the classification system have been advanced in which the prognostic implications of specific ultrastructural and histochemical information are acknowledged. Computed tomography and, to a lesser extent, nuclide scanning have revolutionized the staging process, but limitations in these procedures are emerging. Improved survival following aggressive surgical treatment has challenged the adequacy of the standard staging system. The palliative role of radiotherapy is becoming more widely appreciated. Results of immunotherapy are equivocal and gains from chemotherapy are modest. Combinations of treatment modalities will require further documentation before they can be recommended with confidence. PMID:3529632

  9. The dental amalgam controversy: a review

    PubMed Central

    Feuer, George; Injeyan, H Stephen

    1996-01-01

    In spite of the long history of mercury amalgam as a dental restorative material, its use continues to be controversial. Mercury vapour is continuously released from dental amalgam and is ultimately absorbed into a variety of tissues. Experimental data have demonstrated that the uptake, tissue retention and excretion of mercury from dental amalgam is significant. Evidence has accumulated indicating a relationship between tissue mercury levels and a multitude of clinical manifestations. However, the clinical significance of mercury toxicity from dental amalgams is a matter for debate. The literature is devoid of randomized clinical trials that are rigorously designed to address this issue. Thus, although research data renders the notion of amalgam safety questionable, the dental community appears determined to continue its use as long as unequivocal evidence correlating amalgam mercury toxicity to specific clinical conditions is lacking.

  10. Controversies Surrounding Classification of Personality Disorder

    PubMed Central

    Tyrer, Peter

    2010-01-01

    Nowadays, it is apparent that personality disorder is a common condition. Some of the concepts of personality disorder that are currently in use are flawed and need to be revised. The aim of this article is to discuss the controversy created by the uncertainties in the current classification system and to suggest ways forward. In particular, the clinician needs to be aware of the importance of assessing personality abnormality in terms of a severity dimension, and of the ways in which such an abnormality can impact on treatments for other conditions. These changes in the notion of personality disorder are needed as, for the first time, a good evidence base is being established for potential treatments and these will be maximized if we have a classification fit for therapeutic purpose. PMID:20396426

  11. Element 74, the Wolfram Versus Tungsten Controversy

    SciTech Connect

    Holden,N.E.

    2008-08-11

    Two and a quarter centuries ago, a heavy mineral ore was found which was thought to contain a new chemical element called heavy stone (or tungsten in Swedish). A few years later, the metal was separated from its oxide and the new element (Z=74) was called wolfram. Over the years since that time, both the names wolfram and tungsten were attached to this element in various countries. Sixty years ago, IUPAC chose wolfram as the official name for the element. A few years later, under pressure from the press in the USA, the alternative name tungsten was also allowed by IUPAC. Now the original, official name 'wolfram' has been deleted by IUPAC as one of the two alternate names for the element. The history of this controversy is described here.

  12. Epistemological depth in a GM crops controversy.

    PubMed

    Hicks, Daniel J

    2015-04-01

    This paper examines the scientific controversy over the yields of genetically modified [GM] crops as a case study in epistemologically deep disagreements. Appeals to "the evidence" are inadequate to resolve such disagreements; not because the interlocutors have radically different metaphysical views (as in cases of incommensurability), but instead because they assume rival epistemological frameworks and so have incompatible views about what kinds of research methods and claims count as evidence. Specifically, I show that, in the yield debate, proponents and opponents of GM crops cite two different sets of claims as evidence, which correspond to two rival epistemological frameworks, classical experimental epistemology and Nancy Cartwright's evidence for use. I go on to argue that, even if both sides of the debate accepted Cartwright's view, they might still disagree over what counts as evidence, because evidence for use ties standards of evidence to what is sometimes called the "context of application." PMID:25768981

  13. [Oswaldo Cruz and the serology controversy].

    PubMed

    Carreta, Jorge Augusto

    2011-01-01

    This analysis of the discussion surrounding the efficacy of the plague serum produced by Manguinhos Institute in the early twentieth century begins with an overview of Oswaldo Cruz's service as head of the Public Health Directorship (Diretoria de Saúde Pública). The controversy itself is then addressed, through an exploration of correspondence exchanged by physicians Oswaldo Cruz, Miguel Pereira, Vital Brazil, Chapot Prévost, and Francisco Fajardo. Their letters reveal how bacteriology in Brazil was then marked by uncertainty and experimentation, even while this field of knowledge publicly touted itself as safe and incontestable. The article shows how arguments of an extra-scientific nature interfere with both research development and the acceptance of medical products. PMID:22012092

  14. A Jet-Stirred Apparatus for Turbulent Combustion Experiments

    NASA Astrophysics Data System (ADS)

    Davani, Abbasali; Ronney, Paul

    2015-11-01

    A novel jet-stirred combustion chamber is designed to study turbulent premixed flames. In the new approach, multiple impinging turbulent jets are used to stir the mixture. It is well known that pair of counterflowing turbulent jets produces nearly a constant intensity (u') along the jet axes. In this study, different numbers of impinging jets in various configurations are used to produce isotropic turbulence intensity. FLUENT simulations have been conducted to assess the viability of the proposed chamber. In order to be able to compare different configurations, three different non dimensional indices are introduces. Mean flow index; Homogeneity index, and Isotropicity index. Using these indices one can compare various chambers including conventional Fan-stirred Reactors. Results show that a concentric inlet/outlet chamber (CAIO) with 8 inlets and 8 outlets with inlet velocity of 20 m/s and initial intensity of 15% produces near zero mean flow and 2.5 m/s turbulence intensity which is much more higher than reported values for Fan-stirred chamber. This research was sponsored by National Science Foundation.

  15. Friction-Stir Welding of Aluminum For the Space Program

    NASA Technical Reports Server (NTRS)

    Jones, Clyde S.; Smelser, Jerry W. (Technical Monitor)

    2002-01-01

    The Marshall Space Flight Center is developing and characterizing the friction stir welding process for the Space Shuttle and other space programs. This revolutionary process, invented and patented by The Weld Institute in England, offers tremendous advantages for joining aluminum for high performance applications. It is particularly suited for advanced aluminum-lithium alloys, such as 2195, the primary structural alloy used in the External Tank. The friction stir welding process joins metals with minimal heat input, resulting in high-strength joints with high ductility. It is a simple process to demonstrate using a common milling machine for sample parts, but relatively expensive to implement on large-scale hardware, due to the high cost of tooling needed to handle the high forging pressures characteristic of the process. Recent developments at the Marshall Space Flight Center have demonstrated friction stir welding on linear joints up to 5 meters (15 ft.), with material thickness ranging between 2.5 mm and 16.5 mm (0.100" to 0.650"). High efficiency weld joints have been produced in aluminum from the 2000, 5000, and 6000 series alloy systems. A "retractable pin tool" system was patented by MSFC that allows use of friction stir welding for joints with changing material thickness, and with less rigid tooling than previously considered. This presentation will describe the details of alloys welded to-date and technical advances under development at MSFC. These developments could have substantial benefit to industrial applications for welding aluminum.

  16. Friction stir spot welding of hot-stamped boron steel

    SciTech Connect

    Hovanski, Yuri; Santella, M. L.; Grant, Glenn J.

    2007-11-01

    Hot-stamped, boron steel was successfully joined via friction stir spot welding using polycrystalline cubic boron nitride tooling. The resulting microstructure, microhardness and mechanical properties are reported, including a brief look into failure mechanisms. Relationships between the unique mechanical mixing, phase transformations and failure initiation sites associated with joining martensitic steels are characterized.

  17. Microstructural evolution of 6063 aluminum during friction-stir welding

    SciTech Connect

    Sato, Y.S.; Kokawa, Hiroyuki; Enomoto, Masatoshi; Jogan, Shigetoshi

    1999-09-01

    The microstructural distribution associated with a hardness profile in a friction-stir-welded, age-hardenable 6063 aluminum alloy has been characterized by transmission electron microscopy (TEM) and orientation imaging microscopy (OIM). The friction-stir process produces a softened region in the 6063 Al weld. Frictional heating and plastic flow during friction-stir welding create fine recrystallized grains in the weld zone and recovered grains in the thermomechanically affected zone. The hardness profile depends greatly on the precipitate distribution and only slightly on the grain size. The softened region is characterized by dissolution and growth of the precipitates during the welding. Simulated weld thermal cycles with different peak temperatures have shown that the precipitates are dissolved at temperatures higher than 675 K and that the density of the strengthening precipitate was reduced by thermal cycles lower than 675 K. A comparison between the thermal cycles and isothermal aging has suggested precipitation sequences in the softened region during friction-stir welding.

  18. Friction Stir Spot Welding of DP780 Carbon Steel

    SciTech Connect

    Santella, Michael L; Hovanski, Yuri; Frederick, David Alan; Grant, Glenn J; Dahl, Michael E

    2010-01-01

    Friction stir spot welds were made in uncoated and galvannealed DP780 sheets using polycrystalline boron nitride stir tools. The tools were plunged at either a single continuous rate or in two segments consisting of a relatively high rate followed by a slower rate of shorter depth. Welding times ranged from 1 to 10 s. Increasing tool rotation speed from 800 to 1600 rev min{sup -1} increased strength values. The 2-segment welding procedures also produced higher strength joints. Average lap shear strengths exceeding 10 {center_dot} 3 kN were consistently obtained in 4 s on both the uncoated and the galvannealed DP780. The likelihood of diffusion and mechanical interlocking contributing to bond formation was supported by metallographic examinations. A cost analysis based on spot welding in automobile assembly showed that for friction stir spot welding to be economically competitive with resistance spot welding the cost of stir tools must approach that of resistance spot welding electrode tips.

  19. Recent developments in Micro Friction Stir Welding: A review

    NASA Astrophysics Data System (ADS)

    Sithole, Keydon; Vasudeva Rao, Veeredhi

    2016-02-01

    The advent of friction stir welding (FSW) in 1991 has been evolutionary in the joining of metals and related materials. Friction stir welding has enabled the joining of metals that could not be joined by other welding processes. Research has shown that dissimilar materials with very different properties, plastics, composites and even wood can be joined by FSW. Recent activities in the application of FSW has seen the development of micro friction stir welding (μFSW), which is the FSW of very thin sections of thickness 1000 μm (1 mm) or less. Micro friction stir welding further extends the applications of FSW to areas such as copper electrical contacts, tailor-welded blanks, wood. Though μFSW is relatively new development significant work has been done to date with interesting research findings being reported. This paper aims to review developments in μFSW to date. The focus of the paper will be on problems peculiar to μFSW due to downscaling to the micro scale and other practical considerations.

  20. Neutron Radiography Visualization of Solid Particles in Stirring Liquid Metal

    NASA Astrophysics Data System (ADS)

    Sarma, M.; Ščepanskis, M.; Jakovičs, A.; Thomsen, K.; Nikoluškins, R.; Vontobel, P.; Beinerts, T.; Bojarevičs, A.; Platacis, E.

    This paper presents the analysis of the first dynamic neutron radiography experiment that visualized motion of solid particles in liquid metal, which was stirred by a system of four counter-rotating magnets. The paper also contains the quantitative results derived from neutron images: the distribution of particle concentration, number of admixed particles and velocities as functions of the magnet rotation speed.

  1. Defect Detectability Improvement for Conventional Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Hill, Chris

    2013-01-01

    This research was conducted to evaluate the effects of defect detectability via phased array ultrasound technology in conventional friction stir welds by comparing conventionally prepped post weld surfaces to a machined surface finish. A machined surface is hypothesized to improve defect detectability and increase material strength.

  2. Stop Tobacco in Restaurants: Fifth Grade Students STIR City Hall

    ERIC Educational Resources Information Center

    Morris, Ronald Vaughan

    2008-01-01

    This article discusses a campaign called STIR: Stop Tobacco in Restaurants, that was started by fourth and fifth grade students. The goal was to end smoking in public places, including restaurants, bowling alleys, sports bars, and pool halls. For two years they motivated their peers, coordinated an information campaign to urge kids and adults to…

  3. Temporarily alloying titanium to facilitate friction stir welding

    SciTech Connect

    Hovanski, Yuri

    2009-05-01

    While historically hydrogen has been considered an impurity in titanium, when used as a temporary alloying agent it promotes beneficial changes to material properties that increase the hot-workability of the metal. This technique known as thermohydrogen processing was used to temporarily alloy hydrogen with commercially pure titanium sheet as a means of facilitating the friction stir welding process. Specific alloying parameters were developed to increase the overall hydrogen content of the titanium sheet ranging from commercially pure to 30 atomic percent. Each sheet was evaluated to determine the effect of the hydrogen content on process loads and tool deformation during the plunge phase of the friction stir welding process. Two materials, H-13 tool steel and pure tungsten, were used to fabricate friction stir welding tools that were plunged into each of the thermohydrogen processed titanium sheets. Tool wear was characterized and variations in machine loads were quantified for each tool material and weld metal combination. Thermohydrogen processing was shown to beneficially lower plunge forces and stabilize machine torques at specific hydrogen concentrations. The resulting effects of hydrogen addition to titanium metal undergoing the friction stir welding process are compared with modifications in titanium properties documented in modern literature. Such comparative analysis is used to explain the variance in resulting process loads as a function of the initial hydrogen concentration of the titanium.

  4. Lateral position detection and control for friction stir systems

    DOEpatents

    Fleming, Paul; Lammlein, David; Cook, George E.; Wilkes, Don Mitchell; Strauss, Alvin M.; Delapp, David; Hartman, Daniel A.

    2010-12-14

    A friction stir system for processing at least a first workpiece includes a spindle actuator coupled to a rotary tool comprising a rotating member for contacting and processing the first workpiece. A detection system is provided for obtaining information related to a lateral alignment of the rotating member. The detection system comprises at least one sensor for measuring a force experienced by the rotary tool or a parameter related to the force experienced by the rotary tool during processing, wherein the sensor provides sensor signals. A signal processing system is coupled to receive and analyze the sensor signals and determine a lateral alignment of the rotating member relative to a selected lateral position, a selected path, or a direction to decrease a lateral distance relative to the selected lateral position or selected path. In one embodiment, the friction stir system can be embodied as a closed loop tracking system, such as a robot-based tracked friction stir welding (FSW) or friction stir processing (FSP) system.

  5. The Effect of Friction on Penetration in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Rapp, Steve

    2002-01-01

    "Friction stir butt welding," as it was originally termed by Wayne Thomas and Christopher Dawes, in the early 1990s, but now commonly called "friction stir welding," has made great progress as a new welding technique. Marshall Space Flight Center has been investigating the use of FSW for assembly of the Shuttle's external fuel tank since the late 1990s and hopes to have the process in use by the summer of 2002. In FSW, a cylindrical pin tool of hardened steel, is rotated and plunged into the abutting edges of the parts to be joined. The tool is plunged into the weldment to within about .050 in of the bottom to assure full penetration. As the tool moves along the joint, the tool shoulder helps produce frictional heating, causing the material to plasticize. The metal of the two abutting plates flows from the front of the tool to the back where it cools and coalesces to form a weld in the solid phase. One quarter inch thick plates of aluminum alloy 2219 were used in this study. Two samples, each consisting of two 4 in x 12 in plates, were friction stir welded. The anvil for one sample was coated with molybdenum sulfide, while for the other sample a sheet of roughened stainless steel was placed between the anvil and the sample. The retractable pin tool was used so that the depth of the pin tool penetration could be varied. As welding proceeded, the length of the pin tool was gradually increased from the starting point. The purpose of this investigation is to find out at what point, in the down ramp, penetration occurs. Differences in root structure of the friction stir weld due to differences in anvil friction will be observed. These observations will be analyzed using friction stir weld theory.

  6. The Spokane flood controversy and the Martian outflow channels

    NASA Technical Reports Server (NTRS)

    Baker, V. R.

    1978-01-01

    The controversy over Bretz's hypothesis concerning the cataclysmic Spokane flood is discussed. Attention is directed to similarities between the Channeled Scabland of Washington and some Martian land features considered to be catastrophic flood channels. Characteristics of the enormous plexus of proglacial stream channels eroded into the loess and basalt of the Columbia Plateau in eastern Washington are described. The controversiality of the suggestion that a catastrophic flood is responsible for the Martian features is considered with respect to the Spokane flood controversy.

  7. Protein crystallization in a 100 nl solution with new stirring equipment.

    PubMed

    Maki, S; Murai, R; Yoshikawa, H Y; Kitatani, T; Nakata, S; Kawahara, H; Hasenaka, H; Kobayashi, A; Okada, S; Sugiyama, S; Adachi, H; Matsumura, H; Takano, K; Murakami, S; Inoue, T; Sasaki, T; Mori, Y

    2008-05-01

    To investigate quantitatively the effects of stirring on protein crystallization, a new stirring system which can agitate a protein solution, approximately 100 nl, by providing Hagen-Poiseuille flow has been successfully developed. In addition, this new stirring system provides flow with a well defined pattern and velocity. Using this system, hen egg-white lysozyme was crystallized in 100-200 nl solutions while being stirred. The optimum stirring conditions for lysozyme crystals have been explored by evaluating the Reynolds (Re) number and the crystals obtained. Intermittent flow, as well as a low Re number, was found to contribute significantly to the growth of a smaller number of larger crystals. PMID:18421156

  8. Auto-Adjustable Tool for Self-Reacting and Conventional Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Carter, Robert W. (Inventor)

    2002-01-01

    A friction stir welding dcvice that is configured to perform convention friction stir welding as well as self-reacting friction stir welding is described. A pin passes hrough an upper shoulder and can selectively attach 10 and detach from a lower shoulder in a preferred embodiment. A controller maintains thc discrete position of, and/or force applied by, the upper and lower shoulders during self-reacting friction stir welding, or maintains the pin at a desired depth and/or applied force during conventional friction stir welding.

  9. Maxillary reconstruction: Current concepts and controversies

    PubMed Central

    Iyer, Subramania; Thankappan, Krishnakumar

    2014-01-01

    Maxillary reconstruction is still an evolving art when compared to the reconstruction of the mandible. The defects of maxilla apart from affecting the functions of the speech, swallowing and mastication also cause cosmetic disfigurement. Rehabilitation of the form and function in patients with maxillary defects is either by using an obturator prosthesis or by a surgical reconstruction. Literature is abundant with a variety of reconstructive methods. The classification systems are also varied, with no universal acceptance of any one of them. The oncologic safety of these procedures is still debated, and conclusive evidence in this regard has not emerged yet. Management of the orbit is also not yet addressed properly. Tissue engineering, that has been hyped to be one of the possible solutions for this vexing reconstructive problem, has not come out with reliable and reproducible results so far. This review article discusses the rationale and oncological safety of the reconstructing the maxillary defects, critically analyzes the classification systems, offers the different reconstructive methods and touches upon the controversies in this subject. The management of the retained and exenterated orbit associated with maxillectomy is reviewed. The surgical morbidity, complications and the recent advances in this field are also looked into. An algorithm, based on our experience, is presented. PMID:24987199

  10. Cytomegalovirus and glioblastoma; controversies and opportunities.

    PubMed

    Lawler, Sean E

    2015-07-01

    One of the more polarized ongoing debates in the brain tumor field over recent years has centered on the association of cytomegalovirus (CMV) with glioblastoma. Several laboratories have reported the presence of CMV antigens in glioblastoma patient specimens, whereas others have failed to detect them. CMV genomic DNA and mRNAs have been detected by PCR, but not in next-generation sequencing studies. CMV promotes high grade glioma progression in a mouse genetic model, and many CMV proteins promote cancer hallmarks in vitro, but actively replicating virus has not been isolated from tumor samples. A consensus is gradually emerging in which the presence of CMV antigens in glioblastoma is increasingly accepted. However, it remains challenging to understand this mechanistically due to the low levels of CMV nucleic acids and the absence of viral replication observed in tumors thus far. Nonetheless, these observations have inspired the development of novel therapeutic approaches based on anti-viral drugs and immunotherapy. The potential benefit of valganciclovir in glioblastoma has generated great interest, but efficacy remains to be established in a randomized trial. Also, early stage immunotherapy trials targeting CMV have shown promise. In the near future we will know more answers to these questions, and although areas of controversy may remain, and the mechanisms and roles of CMV in tumor growth are yet to be clearly defined, this widespread virus may have created important new therapeutic concepts and opportunities for the treatment of glioblastoma. PMID:25682092

  11. Controversies in proton therapy for prostate cancer.

    PubMed

    Bryant, Curtis; Henderson, Randal H; Hoppe, Bradford S; Mendenhall, William M; Nichols, R Charles; Su, Zhong; Li, Zuofeng; Mendenhall, Nancy P

    2016-08-01

    Proton therapy (PT) for prostate cancer has been a subject of controversy over the past two decades. Because of its dosimetric advantages when compared to conventional radiation, PT has the potential to improve the therapeutic ratio in the management of prostate cancer by decreasing toxicity and improving disease control. Nevertheless, its higher costs and the current lack of level I evidence documenting improved clinical outcomes have led some to question its cost-effectiveness. A number of new PT centers have been built over the past decade, leading many stakeholders, including patients, physicians, and insurers, to demand comparative effectiveness data to support its current use. In this review, we summarize the results of recently published studies that support the safety and efficacy of PT in the treatment of prostate cancer. We also review the available cost-effectiveness data for PT and discuss the future of PT, including the current randomized trial comparing PT to intensity-modulated radiation therapy and the need for additional research that may help to establish the relative benefit of PT when compared to photon-based radiation therapy. PMID:27558255

  12. More on SUPPORT: the controversy continues.

    PubMed

    Macklin, Ruth

    2015-01-01

    The article by Sunita VS Bandewar in the January-March issue does an excellent job of describing the controversy over informed consent in the SUPPORT clinical trial. As one of the authors of the duelling articles Bandewar cites, I commend the author's conclusions calling for disclosure not only of randomisation in so-called "standard of care" clinical trials, but also the comprehensive disclosure of risks in this type of research (also known as "comparative effectiveness research [CER]"). Bandewar surmises that the disclosure of randomisation could result in a "much higher chance of patients declining to participate in a randomised trial"; and that this may be one of the motives of those who argue for non-disclosure of randomisation. In fact, at least some supporters of limited disclosure of the risks in CER trials have expressly acknowledged their concerns about the recruitment of participants if all the risks of "standard of care" treatments are mentioned in the consent forms. PMID:25910283

  13. World bank in AIDS prevention controversy.

    PubMed

    James, J S

    1995-06-16

    A controversial editorial review article on AIDS prevention by researchers at the Center for AIDS Prevention Studies (CAPS) of the University of California was recently published in the British journal, AIDS. The article's thesis is that in addition to individual behavior, social and economic forces have played a role in promoting the spread of HIV in developing countries, where, by the year 2000, 90 percent of HIV infection will have occurred. The researchers argue that an economic approach, called structural adjustment programs [begun and spearheaded by the International Monetary Fund (IMF) and the World Bank], may have created conditions favoring the spread of HIV infection. The article is concerned about four alleged consequences of these programs: the decline of rural subsistence economy; the development of a transportation infrastructure; migration and urbanization; and reduced spending on health and social services. The CAPS authors recommend changes in development programs which focus on the satisfaction of basic human needs and movement from paternalistic to cooperative development policy. They suggest changing the charter of the World Bank and IMF to allow rescheduling or canceling of debt. World Bank officials, in letters to AIDS, tried to persuade the journal not to publish the article, citing that it falls below the journal's current standards and that some of the information is wrong. PMID:11362526

  14. Advances and controversies in yellow fever vaccination.

    PubMed

    Jonker, Emile F F; Visser, Leonardus G; Roukens, Anna H

    2013-11-01

    Ever since its development in 1937, the live-attenuated 17D yellow fever (YF) vaccine has been one of the most effective vaccines available to man. In this review we highlight the major steps in the development of 17D YF vaccine. We discuss the use of neutralizing antibodies as a surrogate marker for protection, and explore the strengths and weaknesses of the current plaque reduction neutralization test (PRNT), a technique developed in the 1960s that continues to be superior to every modern test in both sensitivity and specificity. The neutralizing antibodies demonstrated by the PRNT can be detected for several decades after vaccination, possibly even for the remainder of the recipient's natural life. We review the available evidence on the duration of protection after primary vaccination, a topic that has been the subject of controversy over the last few months. For persons who are immunocompromised due to disease, medication or advancing age, the duration of protection may be shorter: they should always have their vaccine response checked by PRNT. Due to the higher risk of severe adverse events after vaccination with 17D YF in this group, the development of a new, inactivated vaccine will have substantial benefits in this population. PMID:24757521

  15. Publication of Controversial Papers in Life.

    PubMed

    Lin, Shu-Kun

    2012-01-01

    Life (ISSN 2075-1729, http://www.mdpi.com/journal/life/) is a new journal that deals with new and sometime difficult interdisciplinary matters. Consequently, the journal will occasionally be presented with submitted articles that are controversial and/or outside conventional scientific views. Some papers recently accepted for publication in Life have attracted significant attention. Moreover, members of the Editorial Board have objected to these papers; some have resigned, and others have questioned the scientific validity of the contributions. In response I want to first state some basic facts regarding all publications in this journal. All papers are peer-reviewed, although it is often difficult to obtain expert reviewers for some of the interdisciplinary topics covered by this journal. I feel obliged to stress that although we will strive to guarantee the scientific standard of the papers published in this journal, all the responsibility for the ideas contained in the published articles rests entirely on their authors. Discussions on previously published articles are welcome and I hope that, by fostering discussion and by keeping an open-minded attitude towards new ideas, the journal will spur progress in this little explored, difficult and very exciting area of knowledge. [...]. PMID:26791663

  16. Current Controversies in Lung Cancer Staging.

    PubMed

    Carter, Brett W; Godoy, Myrna C B; Wu, Carol C; Erasmus, Jeremy J; Truong, Mylene T

    2016-07-01

    Lung cancer remains the leading cause of cancer-related mortality in the United States, and accurate staging of disease plays an important role in the formulation of treatment strategies and optimization of patient outcomes. The International Association for the Study of Lung Cancer has recently proposed changes to the upcoming eighth edition of the tumor, node, and metastasis (TNM-8) staging system used for lung cancer. This revised classification is based on significant differences in patient survival identified on analysis of a new large international database of lung cancer cases. Key changes include: further modifications to the T descriptors based on 1 cm increments in tumor size; grouping of tumors resulting in partial or complete lung atelectasis/pneumonitis; grouping of tumors involving a main bronchus with respect to distance from the carina; reassignment of diaphragmatic invasion; elimination of mediastinal pleural invasion as a descriptor; and further subdivision of metastatic disease into distinct descriptors based on the number of extrathoracic metastases and involved organs. Because of these changes, several new stage groups have been developed, and others have shifted. Although TNM-8 represents continued improvement upon modifications previously made to the staging system, reflecting an evolving understanding of tumor behavior and patient management, several limitations and unaddressed issues persist. Understanding the proposed revisions to TNM-8 and awareness of key limitations and potential controversial issues still unaddressed will allow radiologists to accurately stage patients with lung cancer and optimize treatment decisions. PMID:27306388

  17. Maxillary reconstruction: Current concepts and controversies.

    PubMed

    Iyer, Subramania; Thankappan, Krishnakumar

    2014-01-01

    Maxillary reconstruction is still an evolving art when compared to the reconstruction of the mandible. The defects of maxilla apart from affecting the functions of the speech, swallowing and mastication also cause cosmetic disfigurement. Rehabilitation of the form and function in patients with maxillary defects is either by using an obturator prosthesis or by a surgical reconstruction. Literature is abundant with a variety of reconstructive methods. The classification systems are also varied, with no universal acceptance of any one of them. The oncologic safety of these procedures is still debated, and conclusive evidence in this regard has not emerged yet. Management of the orbit is also not yet addressed properly. Tissue engineering, that has been hyped to be one of the possible solutions for this vexing reconstructive problem, has not come out with reliable and reproducible results so far. This review article discusses the rationale and oncological safety of the reconstructing the maxillary defects, critically analyzes the classification systems, offers the different reconstructive methods and touches upon the controversies in this subject. The management of the retained and exenterated orbit associated with maxillectomy is reviewed. The surgical morbidity, complications and the recent advances in this field are also looked into. An algorithm, based on our experience, is presented. PMID:24987199

  18. Microsurgical free flaps: Controversies in maxillofacial reconstruction

    PubMed Central

    George, Rinku K.; Krishnamurthy, Arvind

    2013-01-01

    Reconstructive microsurgery for oral and maxillofacial (OMF) defects is considered as a niche specialty and is performed regularly only in a handful of centers. Till recently the pectoralis major myocutaneous flap (PMMC) was considered to be the benchmark for OMF reconstruction. This philosophy is changing fast with rapid advancement in reconstructive microsurgery. Due to improvement in instrumentation and the development of finer techniques of flap harvesting we can positively state that microsurgery has come of age. Better techniques, microscopes and micro instruments enable us to do things previously unimaginable. Supramicrosurgery and ultrathin flaps are a testimony to this. Years of innovation in reconstructive microsurgery have given us a reasonably good number of very excellent flaps. Tremendous work has been put into producing some exceptionally brilliant research articles, sometimes contradicting each other. This has led to the need for clarity in some areas in this field. This article will review some controversies in reconstructive microsurgery and analyze some of the most common microvascular free flaps (MFF) used in OMF reconstruction. It aims to buttress the fact that three flaps-the radial forearm free flap (RFFF), anterolateral thigh flap (ALT) and fibula are the ones most expedient in the surgeon's arsenal, since they can cater to almost all sizeable defects we come across after ablative surgery in the OMF region. They can thus aptly be titled as the workhorses of OMF reconstruction with regard to free flaps. PMID:23662264

  19. South Africa's AIDS play provokes controversy.

    PubMed

    Lee, N

    1996-03-01

    The European Union (EU) has earmarked a total of 40 million rand (US$12 million) to foster AIDS awareness in South Africa. 14.27 million rand, approximately US$3.45 million, has been allocated by the Department of Health to fund "Sarafina 2," a controversial musical show about AIDS awareness written by Mbongeni Ngema. The allocation of such a large portion of EU funding to this one play has been strongly criticized. The funds could have instead been used to provide essential services. In response, the Department of Health claims that the money had not been subjected to the usual checking processes because the amount had been specifically dedicated to the production of the play. The EU ambassador, however, has reportedly stated that the play was never discussed and was not part of their program. The director of the AIDS directorate was out of the country when Ngema's tender for the play was accepted last August, and it was not until November that she learned about her department's sponsoring of the play. The health department has now forbade its employees from discussing the matter with the media. Minister of Health Nkosazana Zuma should expect a tough time when she goes before Manto Tshabalala's parliamentary portfolio committee on health which has been charged with investigating the matter. The committee will also review some of the accounting related to this issue. PMID:8596329

  20. Phytosynthesis of nanoparticles: concept, controversy and application

    PubMed Central

    2014-01-01

    Nanotechnology is an exciting and powerful discipline of science; the altered properties of which have offered many new and profitable products and applications. Agriculture, food and medicine sector industries have been investing more in nanotechnology research. Plants or their extracts provide a biological synthesis route of several metallic nanoparticles which is more eco-friendly and allows a controlled synthesis with well-defined size and shape. The rapid drug delivery in the presence of a carrier is a recent development to treat patients with nanoparticles of certain metals. The engineered nanoparticles are more useful in increasing the crop production, although this issue is still in infancy. This is simply due to the unprecedented and unforeseen health hazard and environmental concern. The well-known metal ions such as zinc, iron and copper are essential constituents of several enzymes found in the human system even though the indiscriminate use of similar other metal nanoparticle in food and medicine without clinical trial is not advisable. This review is intended to describe the novel phytosynthesis of metal and metal oxide nanoparticles with regard to their shape, size, structure and diverse application in almost all fields of medicine, agriculture and technology. We have also emphasized the concept and controversial mechanism of green synthesis of nanoparticles. PMID:24910577

  1. Phytosynthesis of nanoparticles: concept, controversy and application

    NASA Astrophysics Data System (ADS)

    Husen, Azamal; Siddiqi, Khwaja Salahuddin

    2014-05-01

    Nanotechnology is an exciting and powerful discipline of science; the altered properties of which have offered many new and profitable products and applications. Agriculture, food and medicine sector industries have been investing more in nanotechnology research. Plants or their extracts provide a biological synthesis route of several metallic nanoparticles which is more eco-friendly and allows a controlled synthesis with well-defined size and shape. The rapid drug delivery in the presence of a carrier is a recent development to treat patients with nanoparticles of certain metals. The engineered nanoparticles are more useful in increasing the crop production, although this issue is still in infancy. This is simply due to the unprecedented and unforeseen health hazard and environmental concern. The well-known metal ions such as zinc, iron and copper are essential constituents of several enzymes found in the human system even though the indiscriminate use of similar other metal nanoparticle in food and medicine without clinical trial is not advisable. This review is intended to describe the novel phytosynthesis of metal and metal oxide nanoparticles with regard to their shape, size, structure and diverse application in almost all fields of medicine, agriculture and technology. We have also emphasized the concept and controversial mechanism of green synthesis of nanoparticles.

  2. LDL cholesterol: controversies and future therapeutic directions.

    PubMed

    Ridker, Paul M

    2014-08-16

    Lifelong exposure to raised concentrations of LDL cholesterol increases cardiovascular event rates, and the use of statin therapy as an adjunct to diet, exercise, and smoking cessation has proven highly effective in reducing the population burden associated with hyperlipidaemia. Yet, despite consistent biological, genetic, and epidemiological data, and evidence from randomised trials, there is controversy among national guidelines and clinical practice with regard to LDL cholesterol, its measurement, the usefulness of population-based screening, the net benefit-to-risk ratio for different LDL-lowering drugs, the benefit of treatment targets, and whether aggressive lowering of LDL is safe. Several novel therapies have been introduced for the treatment of people with genetic defects that result in loss of function within the LDL receptor, a major determinant of inherited hyperlipidaemias. Moreover, the usefulness of monoclonal antibodies that extend the LDL-receptor lifecycle (and thus result in substantial lowering of LDL cholesterol below the levels achieved with statins alone) is being assessed in phase 3 trials that will enrol more than 60,000 at-risk patients worldwide. These trials represent an exceptionally rapid translation of genetic observations into clinical practice and will address core questions of how low LDL cholesterol can be safely reduced, whether the mechanism of LDL-cholesterol lowering matters, and whether ever more aggressive lipid-lowering provides a safe, long-term mechanism to prevent atherothrombotic complications. PMID:25131980

  3. Obestatin: an interesting but controversial gut hormone.

    PubMed

    Lacquaniti, Antonio; Donato, Valentina; Chirico, Valeria; Buemi, Antoine; Buemi, Michele

    2011-01-01

    Obestatin is a 23-amino acid peptide hormone released from the stomach and is present not only in the gastrointestinal tract, but also in the spleen, mammary gland, breast milk and plasma. Obestatin appears to function as part of a complex gut-brain network whereby hormones and substances from the stomach and intestines signal the brain about satiety or hunger. In contrast to ghrelin, which causes hyperphagia and obesity, obestatin appears to act as an anorectic hormone, decreasing food intake and reducing body weight gain. Further studies have shown that obestatin is also involved in improving memory, regulating sleep, affecting cell proliferation, increasing the secretion of pancreatic juice enzymes and inhibiting glucose-induced insulin secretion. This hormone has not only been studied in the field of physiology but also in the fields of obesity and diabetes mellitus, and in patients with psychogenic eating disorders. Obestatin has a role in regulating the cell cycle by exerting proliferative effects that may be seen in cell physiology and oncology. Given the current controversy regarding the effects of obestatin and its cognate ligand, this article provides the latest review of the physiological and pathological characteristics of this hormone. PMID:22156552

  4. Endoscopic vein harvesting: technique, outcomes, concerns & controversies

    PubMed Central

    Sarang, Zubair

    2013-01-01

    The choice of the graft conduit for coronary artery bypass grafting (CABG) has significant implications both in the short- and long-term. The patency of a coronary conduit is closely associated with an uneventful postoperative course, better long-term patient survival and superior freedom from re-intervention. The internal mammary artery is regarded as the primary conduit for CABG patients, given its association with long-term patency and survival. However, long saphenous vein (LSV) continues to be utilized universally as patients presenting for CABG often have multiple coronary territories requiring revascularization. Traditionally, the LSV has been harvested by creating incisions from the ankle up to the groin termed open vein harvesting (OVH). However, such harvesting methods are associated with incisional pain and leg wound infections. In addition, patients find such large incisions to be cosmetically unappealing. These concerns regarding wound morbidity and patient satisfaction led to the emergence of endoscopic vein harvesting (EVH). Published experience comparing OVH with EVH suggests decreased wound related complications, improved patient satisfaction, shorter hospital stay, and reduced postoperative pain at the harvest site following EVH. Despite these reported advantages concerns regarding risk of injury at the time of harvest with its potential detrimental effect on vein graft patency and clinical outcomes have prevented universal adoption of EVH. This review article provides a detailed insight into the technical aspects, outcomes, concerns, and controversies associated with EVH. PMID:24251019

  5. Stirred media mills: Dynamics, performance, and physio-chemical aspects

    NASA Astrophysics Data System (ADS)

    Zheng, Jie

    While applications of stirred media mills for fine particle production have continued to grow, there is a lack of understanding of power requirements, optimum operating conditions and powder (product) characteristics underlying stirred media milling processes. To develop a physical understanding of stirred mill dynamics and scale-up principles, and to identify conditions and mechanisms for effective use of energy in fine grinding, the results of analysis of the literature and of tests in laboratory stirred media mills with media, limestone, and the effect of chemical additives as grinding aids are presented, and mill dynamics, performance and physico-chemical aspects are discussed. Four operational regions marked by sharp transitions are described: transition from static to dynamic friction; channeling; dispersion; and centrifugation. Equations, including power and modified Reynolds number, have been established for relating relevant operating and geometrical variables. Scale-up guidelines with respect to power consumption are also proposed. The best operating conditions for grinding limestone have been identified. The effect of additives on the grinding efficiency and the properties of ground product is discussed using the example of ultra fine grinding of limestone, in which more than a 100% increase in specific surface area and energy efficiency can be obtained. As solid concentration increases, media/pulp flow patterns pass through four regimes: vortex flow, rotating flow, layer formation above the impeller pins, and layer formation adjacent to the tank wall. Use of polyacrylic acid as an additive caused the media/pulp flow to move toward lower solid concentration situation, thus improving grinding conditions and resulting in better grinding. Fragmentation of the polymer molecules was found to occur during long term grinding and this was beneficial for ultrafine grinding. In summary, the research has led to the development of a physical understanding of mill

  6. Blastocystis: Consensus of treatment and controversies

    PubMed Central

    Sekar, Uma; Shanthi, M

    2013-01-01

    Blastocystis is a highly controversial protozoan parasite. It has been variably regarded as a commensal and pathogen. Scientists have for decades wondered whether it is truly an enteropathogen and if it is observed in symptomatic patients whether treatment is required because patient recovery and improvement has been noted even without any treatment. Though associated with self-limiting infection, treatment is warranted in many patients due to persistence of symptoms. This particularly holds true for children and adults who are immuno compromised. Several drugs have been used to treat Blastocystis but each one of them has produced widely variable rates of clinical cure and eradication of the parasite from the feces. Based on the studies carried out in vitro and clinical responses obtained in patients, metronidazole appears to be the most effective drug for Blastocystis infection. However, the therapy is complicated due to different dosages and regimens adopted and the unresponsiveness to treatment observed in several sections of the population studied. Recently, the finding of different subsets of Blastocystis exhibiting resistance to metronidazole and associated with variable degrees of symptoms has underscored the importance of typing the subsets of the parasite in order to foretell the clinical response and the need to treat. Till date, the mode of action of the drugs used and the mechanism of resistance is not entirely known and is a topic of speculation. Other drugs with anti Blastocystis activity and used in therapy includes trimethoprim sulfamethoxazole and nitazoxanide. Several other compounds have also been evaluated for the treatment either alone or in combination with the first or second line drugs. A lot of interest has also been generated on the role of probiotics particularly Saccharomyces boularrdii and other natural food compounds on eradication of the parasite. This review provides a comprehensive overview of antimicrobials used to target

  7. The Gaia Controversy: AGU'S Chapman Conference

    NASA Astrophysics Data System (ADS)

    Kauffman, Eric G.

    The controversial Gaia Hypothesis of James Lovelock of Coombe Mill, Launceston, Cornwall, U.K., and his colleagues variously contends that throughout Earth history the global biosphere has influenced, even controlled, the physicochemical evolution of Earth's environments (especially oceans and climate) for its own benefit. Since the origin of life, the biosphere has influenced selective pressures on evolution, maintained the Earth in a kind of homeostasis, and thus created an environmental optimum through time, regulated by and for the biosphere. Rarely has a hypothesis immediately sparked such passionate response. There is something in it for everybody, from hard core scientists to philosophers, ultraconservationists, students of world religions, mystics, politicians, and space enthusiasts; they were all there in San Diego, March 7-11, 1988, for the AGU Chapman Conference on Gaia Hypotheses. For 4 days an impressive list of specialists presented and debated the pros and cons of Gaia Hypotheses from diverse perspectives: modern and ancient biology, ecology, biochemistry, the physicochemical systems of the Earth, oceans, and atmosphere, and the evolution of the solar system. Focus was on modern to Pleistocene atmosphere-ocean-Earth systems, case histories of their interaction with the biosphere, and relatively simple models drawn from these observations and projected back through time. Equivalent studies on the geological and paleobiological history of the Earth-life system over the past 3.5 b.y. were underrepresented. Extended debates that followed generally strong presentations were lively, argumentative, and remarkably civil despite widely held views. The grace with which Jim Lovelock moved between his strongest critics and supporters set high standards for the debates. Everybody acknowledged a high learning curve.

  8. Cold dark matter: Controversies on small scales

    PubMed Central

    Weinberg, David H.; Bullock, James S.; Governato, Fabio; Kuzio de Naray, Rachel; Peter, Annika H. G.

    2015-01-01

    The cold dark matter (CDM) cosmological model has been remarkably successful in explaining cosmic structure over an enormous span of redshift, but it has faced persistent challenges from observations that probe the innermost regions of dark matter halos and the properties of the Milky Way’s dwarf galaxy satellites. We review the current observational and theoretical status of these “small-scale controversies.” Cosmological simulations that incorporate only gravity and collisionless CDM predict halos with abundant substructure and central densities that are too high to match constraints from galaxy dynamics. The solution could lie in baryonic physics: Recent numerical simulations and analytical models suggest that gravitational potential fluctuations tied to efficient supernova feedback can flatten the central cusps of halos in massive galaxies, and a combination of feedback and low star formation efficiency could explain why most of the dark matter subhalos orbiting the Milky Way do not host visible galaxies. However, it is not clear that this solution can work in the lowest mass galaxies, where discrepancies are observed. Alternatively, the small-scale conflicts could be evidence of more complex physics in the dark sector itself. For example, elastic scattering from strong dark matter self-interactions can alter predicted halo mass profiles, leading to good agreement with observations across a wide range of galaxy mass. Gravitational lensing and dynamical perturbations of tidal streams in the stellar halo provide evidence for an abundant population of low-mass subhalos in accord with CDM predictions. These observational approaches will get more powerful over the next few years. PMID:25646464

  9. Cold dark matter: Controversies on small scales.

    PubMed

    Weinberg, David H; Bullock, James S; Governato, Fabio; Kuzio de Naray, Rachel; Peter, Annika H G

    2015-10-01

    The cold dark matter (CDM) cosmological model has been remarkably successful in explaining cosmic structure over an enormous span of redshift, but it has faced persistent challenges from observations that probe the innermost regions of dark matter halos and the properties of the Milky Way's dwarf galaxy satellites. We review the current observational and theoretical status of these "small-scale controversies." Cosmological simulations that incorporate only gravity and collisionless CDM predict halos with abundant substructure and central densities that are too high to match constraints from galaxy dynamics. The solution could lie in baryonic physics: Recent numerical simulations and analytical models suggest that gravitational potential fluctuations tied to efficient supernova feedback can flatten the central cusps of halos in massive galaxies, and a combination of feedback and low star formation efficiency could explain why most of the dark matter subhalos orbiting the Milky Way do not host visible galaxies. However, it is not clear that this solution can work in the lowest mass galaxies, where discrepancies are observed. Alternatively, the small-scale conflicts could be evidence of more complex physics in the dark sector itself. For example, elastic scattering from strong dark matter self-interactions can alter predicted halo mass profiles, leading to good agreement with observations across a wide range of galaxy mass. Gravitational lensing and dynamical perturbations of tidal streams in the stellar halo provide evidence for an abundant population of low-mass subhalos in accord with CDM predictions. These observational approaches will get more powerful over the next few years. PMID:25646464

  10. Risky, early, controversial. Puberty in medical discourses.

    PubMed

    Cozzi, Donatella; Vinel, Virginie

    2015-10-01

    This article comes within the compass of a research program (entitled CorAge. Bodily Experiences and AgePassages among 9-13 year-olds (ANR-09-ENFT-017) conducted between 2009 and 2013 about the emergence of a "new" age in life--"preadolescence"--as instanced in France (Alsace, Lorraine) and Italy (Venetia). The impressive amount of references to "early puberty" and "precocious puberty", in a context of feeling of a premature end of childhood, led us to make an in-depth study of this issue: first, through an analysis of international and French and Italian medical journals; second, through interviews with health professionals. Following the thesis of Foucault, we assume that the discourses on puberty timing participate of classifications of the child body drenched with moral representations of childhood, especially on gender and age issue. Our results: the question of whether a secular trend in puberty timing even exists continues to be debated between American and European scientists. Second, the terms "puberty", "precocious puberty", "early puberty" have been used to indicate a variety of puberty markers, increasing confusion. A controversy has focused on early breast development in girls, because this attribute is questioning the order of ages and gender. Moreover, psychosocial factors presented as accelerating early puberty, do not demonstrate the relation between earliness and risk behavior. The literature, as it is moved by the female precocity, creates a medical category to objectify the complex and flexible process of puberty and invent female child precocity. These differences between American and European scholars and the interviews with French and Italian health professional show a gap between the international literature and practitioners, clinicians and nurses who regularly work with children: they neither find pubertal advancement, nor increase of "true precocious puberty", although they share concerns about premature feminization of girls (France) or

  11. Research controversies in management of oral mucositis.

    PubMed

    Biron, P; Sebban, C; Gourmet, R; Chvetzoff, G; Philip, I; Blay, J Y

    2000-01-01

    The management of mucositis is the subject of many controversies, and the optimal treatment is still not known. Several evaluation scoring systems have been described, but no one of these is appropriate to all clinical situations: a simple scale such as that devised by the WHO can be used routinely, and more sophisticated ones can be implemented by trained experimenters working in research. We have considered the impact of each of the treatments currently available on each stage of mucositis. In attempts at prevention, self-care, in the sense of oral hygiene, must remain atraumatic. It is probably advisable to differentiate patients with good previous oral care, in whom tooth brushing is beneficial, from others, in whom the risk of hemorrhage and infection excludes any brushing. Before the dosage of chemotherapy is reduced, the curative or palliative intent of the strategy must be carefully evaluated. In the vascular phase protection of the proliferating cells is attempted by means of vasoconstriction (cryotherapy), cytoprotection (prostaglandin E2 and other antioxidants) or epithelial cell-inhibiting factors such as TGF-B3. Treatments applied in the epithelial phase are directed at increasing the cell proliferation to accelerate epithelial restoration by sucralfate and several growth factors: hematopoietic GF, which has demonstrated a direct effect on the mucosa (GM-CSF), or epithelial growth factors such as keratinocyte GF. In the ulcerative and bacteriological phase attempts are made to attenuate sepsis by means of antiseptics (chlorhexidine), amphotericin B and antiviral agents or antibiotic lozenges. In the healing phase application of the low-energy helium-neon laser has demonstrably been followed by a later time of onset, less pronounced peak severity and shorter duration of oral mucositis. After cancer treatment, oral hygiene, inhibition of oral flora, and pain relief are the main goals. Physiopathogen-specific treatment is the next step, with the emphasis

  12. Screening for cancer: concepts and controversies.

    PubMed

    Gates, Thomas J

    2014-11-01

    Early detection of cancer is a core task in family medicine, and patients have come to expect screening tests, sometimes out of proportion to what evidence can justify. To understand the controversies surrounding screening and to provide sound advice to patients, family physicians should be familiar with the fundamental concepts of screening. Failure to account for the effects of lead-time, length-time, and overdiagnosis biases can lead to overestimation of screening benefits. For this reason, the best method for evaluating the benefit of screening tests is a randomized controlled trial showing decreased disease-specific or all-cause mortality. The number needed to screen can be used to measure the magnitude of benefit of screening tests. Accepted screening tests often require screening several hundred to more than 1,000 asymptomatic patients to prevent one death from the disease. The U.S. Preventive Services Task Force and American Academy of Family Physicians recommend screening for colorectal cancer in adults 50 to 75 years of age, and recommend against prostate-specific antigen testing to screen for prostate cancer. Annual low-dose computed tomography screening for lung cancer reduces mortality in persons 55 to 80 years of age with at least a 30-pack-year history who are otherwise healthy smokers or who have quit smoking within the past 15 years; however, it is associated with a high false-positive rate, uncertain harms from radiation exposure, and overdiagnosis. Therefore, it should be performed only in conjunction with smoking cessation interventions. PMID:25368922

  13. The Procedurally Directive Approach to Teaching Controversial Issues

    ERIC Educational Resources Information Center

    Gregory, Maughn Rollins

    2014-01-01

    Recent articles on teaching controversial topics in schools have employed Michael Hand's distinction between "directive teaching," in which teachers attempt to persuade students of correct positions on topics that are not rationally controversial, and "nondirective teaching," in which teachers avoid persuading students on…

  14. Visualizing Social Justice: Using Controversial Images in Social Studies Classrooms

    ERIC Educational Resources Information Center

    Hawley, Todd S.; Crowe, Alicia R.; Mooney, Evan

    2016-01-01

    In this article, we promote the use of controversial images to enhance the discussion of social justice issues in schools. Controversial images provide rich opportunities for students to question what is occurring currently in society as well as what has occurred in the past. We provide an example set of activities to be used in teacher education…

  15. Culture Shock: Using Art and Art Controversy To Teach History.

    ERIC Educational Resources Information Center

    McBride, Robert, Jr.

    1999-01-01

    Endorses the television series entitled "Culture Shock" that views controversial art as an artifact suggesting that the arts, and controversies surrounding them, can help viewers think critically about the issues of past and present societies. Focuses on "The Adventures of Huckleberry Finn," the painting "Olympia," jazz, and films in the…

  16. Urquhart's and Garfield's Laws: The British Controversy over Their Validity.

    ERIC Educational Resources Information Center

    Bensman, Stephen J.

    2001-01-01

    The British controversy over the validity of Urquhart's and Garfield's bibliometric laws during the 1970s constitutes an important episode in the formulation of the probability structure of human knowledge. Concludes with a resolution of the controversy by means of a statistical technique that incorporates Brookes' criticism of the Spearman…

  17. 16 CFR 2.3 - Policy as to private controversies.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... other action when the alleged violation of law is merely a matter of private controversy and does not... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Policy as to private controversies. 2.3... NONADJUDICATIVE PROCEDURES Inquiries; Investigations; Compulsory Processes § 2.3 Policy as to...

  18. Implants and Ethnocide: Learning from the Cochlear Implant Controversy

    ERIC Educational Resources Information Center

    Sparrow, Robert

    2010-01-01

    This paper uses the fictional case of the "Babel fish" to explore and illustrate the issues involved in the controversy about the use of cochlear implants in prelinguistically deaf children. Analysis of this controversy suggests that the development of genetic tests for deafness poses a serious threat to the continued flourishing of Deaf culture.…

  19. Resisting the Pendulum Swing: Informed Perspectives on Education Controversies.

    ERIC Educational Resources Information Center

    Jalongo, Mary Renck, Ed.

    Designed to offer more than slogans and buzzwords to practitioners who are grappling with an array of education controversies, this book provides classroom teachers with a spectrum of information about current controversies so that they will be better equipped to blend action with reflection. The book deliberately resists extremes and argues for…

  20. Teaching and Learning about Controversial Issues: Lessons from Northern Ireland

    ERIC Educational Resources Information Center

    King, John T.

    2009-01-01

    Teaching about controversial issues is a powerful tool in the repertoire of civic educators. Despite widespread agreement concerning the social, academic, and civic benefits to be gained from discussing controversial public issues within the classroom, empirical research reveals that doing so is a rare occurrence. While the literature explains…

  1. Preparing Students for Science in the Face of Social Controversy

    ERIC Educational Resources Information Center

    Bramschreiber, Terry; Westmoreland, David

    2015-01-01

    Science educators often teach topics that are largely resolved in the scientific community yet remain controversial in broader society. In such cases, students may perceive the teacher as biased. We present two exercises that foster more objective learning about the scientific underpinnings of socially controversial topics. The first exercise…

  2. Approaching Civic Responsibility Using Guided Controversies about Environmental Issues

    ERIC Educational Resources Information Center

    Dresner, Marion; Blatner, Jen Seamans

    2006-01-01

    We implemented a series of three guided controversies to provide experience in environmental problem solving to students in a science course designed for nonmajors. Students wrote essays in response to their experiences in each controversy; we analyzed these essays for five problem-solving criteria. A questionnaire administered at the end of the…

  3. Improving Learning by Discussing Controversies in 20th Century Physics.

    ERIC Educational Resources Information Center

    Niaz, Mansoor; Rodriguez, Maria A.

    2002-01-01

    Textbooks rarely emphasize how controversial some physics theories were at the time of their proposal. Makes the case that useful classroom debate can be generated by considering the controversy that arose over models of the atom such as Rutherford's and Bohr's, and ideas about fractional charges put forward by Millikan and arising from quark…

  4. Teachers' Perspectives on Incorporating Current Controversial Issues into the Curriculum.

    ERIC Educational Resources Information Center

    Wilson, Elizabeth; Sunal, Cynthia; Haas, Mary; Laughlin, Margaret

    Does a current controversial issue become part of the social studies curriculum in a context where the media focus largely on the issue? A study explored this question through surveys and in-depth interviews that investigated K-12 social studies teachers' perspectives on the incorporation of current controversial issues into the curriculum. A…

  5. Literature for Children: Avoiding Controversy and Intellectual Challenge.

    ERIC Educational Resources Information Center

    Adams, Dennis M.

    1986-01-01

    Discusses lack of literature on controversial subjects that can help prepare children and young adults to deal perceptively with complexities of modern world. Highlights include meeting the issues head-on, glorifying armed conflict in video media, avoiding issues of nuclear war, and intellectual depth and dealing with controversial issues. (12…

  6. Structured Academic Controversies in the Professional Physical Education Classroom.

    ERIC Educational Resources Information Center

    Overby, Lynnette Young; And Others

    1996-01-01

    Structured academic controversy is a cooperative learning strategy that can promote learning in theoretical physical education classes at the college level. This article explains how to conduct structured academic controversy, providing examples of topics (e.g., adapted physical education, biomechanics, motor development, and sport psychology).…

  7. Covering Conflict and Controversy: Measuring Balance, Fairness, Defamation.

    ERIC Educational Resources Information Center

    Simon, Todd F.; And Others

    1989-01-01

    Measures balance, fairness, and defamation in local stories containing controversy and covering law enforcement, education, local government, and business. Finds that most stories lack balance and that the opposing side of the controversy was not contacted in 28 percent of the instances. (RS)

  8. What's Wrong with the "Teach the Controversy" Slogan?

    ERIC Educational Resources Information Center

    Scott, Eugenie C.

    2007-01-01

    Teachers are often exhorted by creationists to "teach the controversy." Although such encouragement sounds on the surface like a proposal for critical thinking instruction, the history of the creationist movement in North America belies this claim. Rather than teach students to analyze and evaluate actual scientific controversies, the intent of…

  9. Main Field Test Report. Discussing Controversial Issues. Revised.

    ERIC Educational Resources Information Center

    Lai, Morris K.; And Others

    Discussing Controversial Issues (DCI) is a skill training program designed for high school students and teachers with an overall objective of developing student and teacher skill in discussing controversial issues effectively. The course materials identify 13 moderator techniques which teachers practice, and 13 participant techniques which…

  10. The NSF Science Education Controversy: Issues, Events, Decisions.

    ERIC Educational Resources Information Center

    Wiley, Karen B.

    Discussion of National Science Foundation (NSF) funding of precollege science education revolves around the controversy of whether NSF should fund "Man: A Course of Study" (MACOS). NSF had funded MACOS' curriculum development, implementation, and postevaluation during 1963-1975. The controversy began in March 1975 when U.S. Congressman John Conlan…

  11. The Recovered Memory Controversy: A Representative Case Study

    ERIC Educational Resources Information Center

    Colangelo, James J.

    2009-01-01

    The recovered memory controversy has been an ongoing debate within the mental health profession for the past two decades. Disagreement remains in the field over the veracity of "forgotten" memories of childhood sexual abuse that are recalled or recovered during therapy. At the heart of the controversy are the concepts of repression and…

  12. 12 CFR 1080.3 - Policy as to private controversies.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 9 2014-01-01 2014-01-01 false Policy as to private controversies. 1080.3 Section 1080.3 Banks and Banking BUREAU OF CONSUMER FINANCIAL PROTECTION RULES RELATING TO INVESTIGATIONS § 1080.3 Policy as to private controversies. The Bureau shall act only in the public interest and...

  13. 12 CFR 1080.3 - Policy as to private controversies.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 8 2012-01-01 2012-01-01 false Policy as to private controversies. 1080.3 Section 1080.3 Banks and Banking BUREAU OF CONSUMER FINANCIAL PROTECTION RULES RELATING TO INVESTIGATIONS § 1080.3 Policy as to private controversies. The Bureau shall act only in the public interest and...

  14. From Classroom to Controversy: Conflict in the Teaching of Religion

    ERIC Educational Resources Information Center

    Neal, Lynn S.

    2013-01-01

    What happens when a class assignment becomes a source of controversy? How do we respond? What do we learn? By describing the controversy surrounding an assignment on religion and representation, this article examines conflict's productive role in teaching about New Religious Movements (NRMs) and religion. It suggests that we consider how our…

  15. The Rasch Rating Model and the Disordered Threshold Controversy

    ERIC Educational Resources Information Center

    Adams, Raymond J.; Wu, Margaret L.; Wilson, Mark

    2012-01-01

    The Rasch rating (or partial credit) model is a widely applied item response model that is used to model ordinal observed variables that are assumed to collectively reflect a common latent variable. In the application of the model there is considerable controversy surrounding the assessment of fit. This controversy is most notable when the set of…

  16. Controversial Higher-Education Reforms Spark Riots in Athens

    ERIC Educational Resources Information Center

    Labi, Aisha

    2007-01-01

    This article discusses the Greek Parliament's controversial education bill passed recently that sparked riots and unrest in Athens. The government's controversial education package includes measures that would limit the number of years students can take to complete a university degree and would curtail university asylum laws. A separate proposal…

  17. Why Map Issues? On Controversy Analysis as a Digital Method

    PubMed Central

    2015-01-01

    This article takes stock of recent efforts to implement controversy analysis as a digital method in the study of science, technology, and society (STS) and beyond and outlines a distinctive approach to address the problem of digital bias. Digital media technologies exert significant influence on the enactment of controversy in online settings, and this risks undermining the substantive focus of controversy analysis conducted by digital means. To address this problem, I propose a shift in thematic focus from controversy analysis to issue mapping. The article begins by distinguishing between three broad frameworks that currently guide the development of controversy analysis as a digital method, namely, demarcationist, discursive, and empiricist. Each has been adopted in STS, but only the last one offers a digital “move beyond impartiality.” I demonstrate this approach by analyzing issues of Internet governance with the aid of the social media platform Twitter. PMID:26336325

  18. Controversy and the state: lord ARPA and intelligent computing.

    PubMed

    Guice, J

    1998-02-01

    This is a study of a well-known controversy in computer science, between artificial intelligence and neural networks researchers. It examines claims made by participants in the field that the controversy was triggered, shaped and finally resolved in connection to activities of state research agencies, particularly the US Department of Defense Advanced Research Projects Agency (ARPA). In contrast to these claims, this account concludes that, although ARPA's relations to the controversy among researchers were important, they were indirect. This study thus beings the analytical resources of studies of scientific controversy to bear on a domain which has so far gone largely unexamined in studies of 20th-century controversies - namely, state research policy and management. The account is based on contemporary documents, historical literatuare, and interviews with researchers and ARPA officials. PMID:11619937

  19. KNOW NUKES: a model for teaching controversial issues

    SciTech Connect

    Thomashow, M.S.

    1986-01-01

    This dissertation articulates elements of an educational strategy derived from the experience of the KNOW NUKES program, a teacher training project designed to introduce the nuclear power controversy in the high school classroom. This strategy can be used as means of furthering the effectiveness of controversial issues education, not only in the area of nuclear power, but in teaching about any environmental issue. This is specifically achieved by (2) placing the KNOW NUKES institute in the broader context of controversial issues education; (2) describing in detail KNOW NUKES project planning; (3) reviewing the structure and content of the various teaching techniques and materials that have been developed for the KNOW NUKES institute; (4) utilizing a particular technique developed by the institute that reveals varying perspectives on controversial issues, in this case, an instrumental for decoding the controversial issues that are explicit and implicit in corporate image advertisements; and (5) qualitatively evaluating the practical implementation of the KNOW NUKES model.

  20. Low-temperature friction-stir welding of 2024 aluminum

    SciTech Connect

    Benavides, S.; Li, Y.; Murr, L.E.; Brown, D.; McClure, J.C.

    1999-09-10

    Solid-state, friction-stir welding (FSW) has been demonstrated to involve dynamic recrystallization producing ultra-fine, equiaxed grain structures to facilitate superplastic deformation as the welding or joining mechanism. Since the recrystallization temperature also decreases with increasing strain rate, the FSW process is somewhat complicated because the ambient temperature, the frictional heating fraction, and the adiabatic heating fraction (proportional to the product of strain and strain-rate) will all influence both the recrystallization and grain growth within the FSW zone. Significantly reducing the ambient temperature of the base metal or work pieces to be welded would be expected to reduce the residual weld-zone grain size. The practical consequences of this temperature reduction would be the achievement of low-temperature welding. This study compares the residual grain sizes and microstructures in 2024 Al friction-stir welded at room temperature ({approximately} 30 C) and low temperature ({minus} 30 C).

  1. Effect of friction stir welding parameters on defect formation

    NASA Astrophysics Data System (ADS)

    Tarasov, S. Yu.; Rubtsov, V. E.; Eliseev, A. A.; Kolubaev, E. A.; Filippov, A. V.; Ivanov, A. N.

    2015-10-01

    Friction stir welding is a perspective method for manufacturing automotive parts, aviation and space technology. One of the major problems is the formation of welding defects and weld around the welding zone. The formation of defect is the main reason failure of the joint. A possible way to obtain defect-free welded joints is the selection of the correct welding parameters. Experimental results describing the effect of friction stir welding process parameters on the defects of welded joints on aluminum alloy AMg5M have been shown. The weld joint defects have been characterized using the non-destructive radioscopic and ultrasound phase array methods. It was shown how the type and size of defects determine the welded joint strength.

  2. Tracing Material Flow Paths in Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Sanders, Johnny; Schneider, Judy; Numes, Arthur, Jr.

    2005-01-01

    Heat and mechanical work are coupled in the friction stir welding process. The process variables are RPM, translational weld speed, and downward plunge force. The strain-temperature history of a metal element at each point on the cross-section of the weld is determined by the process variables plus the individual flow path taken by the particular filament of metal flowing around the tool and ending on flat point. The strain-temperature history determines the properties of a metal element on the weld cross-section. The strain-temperature history is carefully controlled in metal processes where direct control is feasible. Indirect estimates of the flow paths and the strain-temperature histories of filaments comprising friction stir welds can be made from a model, if the model is good enough. This paper describes marker studies of flow path geometries for various process parameters. Observed geometries are compared with geometries estimated from models.

  3. FRICTION STIR LAP WELDING OF ALUMINUM - POLYMER USING SCRIBE TECHNOLOGY

    SciTech Connect

    Upadhyay, Piyush; Hovanski, Yuri; Fifield, Leonard S.; Simmons, Kevin L.

    2015-02-16

    Friction Stir Scribe (FSS) technology is a relatively new variant of Friction Stir Welding (FSW) which enables lap joining of dissimilar material with very different melting points and different high temperature flow behaviors. The cutter scribe attached at the tip of FSW tool pin effectively cuts the high melting point material such that a mechanically interlocking feature is created between the dissimilar materials. The geometric shape of this interlocking feature determines the shear strength attained by the lap joint. This work presents first use of scribe technology in joining polymers to aluminum alloy. Details of the several runs of scribe welding performed in lap joining of ~3.175mm thick polymers including HDPE, filled and unfilled Nylon 66 to 2mm thick AA5182 are presented. The effect of scribe geometry and length on weld interlocking features is presented along with lap shear strength evaluations.

  4. Electromagnetic stirring with alternating current during electroslag remelting

    NASA Astrophysics Data System (ADS)

    Mitchell, Alec; Hernandez-Morales, Bernardo

    1990-08-01

    An alternating current (AC)-operated electromagnetic stirring (EMS) device, using line frequency, was designed and built to operate on a laboratory electroslag remelting (ESR) furnace for 150-mm-diameter ingots. Laboratory-scale experiments were conducted employing both 4340 alloy steel and INCONEL 718 alloy as electrode material. The initiation of stirring is accompanied by a thin strip of segregated material and favors the formation of spot segregation. Changes produced in the fluid flow conditions in the liquid pool ahead of the solidification front result in a transition from a highly directional columnar to an unoriented, branched structure. Except for small pockets of segregated liquid, the flow of molten metal does not penetrate into the mushy zone. Both electrode material and molten metal pool shape play an important role on the extent of promoting an equiaxed structure.

  5. Heat Treatment of Friction-Stir-Welded 7050 Aluminum Plates

    NASA Technical Reports Server (NTRS)

    Petter, George E.; Figert, John D.; Rybicki, Daniel J.; Burns, Timothy

    2006-01-01

    A method of heat treatment has been developed to reverse some of the deleterious effects of friction stir welding of plates of aluminum alloy 7050. This alloy is considered unweldable by arc and high-energy-density beam fusion welding processes. The alloy can be friction stir welded, but as-welded workpieces exhibit low ductility, low tensile and yield strengths, and low resistance to stress corrosion cracking. Heat treatment according to the present method increases tensile and yield strengths, and minimizes or eliminates stress corrosion cracking. It also increases ductility. This method of heat treatment is a superior alternative to a specification-required heat treatment that caused the formation of large columnar grains, which are undesired. Workpieces subjected to the prior heat treatment exhibited elongations <2 percent, and standard three-point bend specimens shattered. The development of the present heat treatment method was guided partly by the principles that (1) by minimizing grain sizes and relieving deformation stresses, one can minimize or eliminate stress corrosion cracking and (2) the key to maximizing strength and eliminating residual stresses is to perform post-weld solution heating for as long a time as possible while incurring little or no development of large columnar grains in friction stir weld nuggets. It is necessary to perform some of the solution heat treatment (to soften the alloy and improve machine welding parameters) before welding. The following is an example of thickness- dependent pre- and post-weld heat treatments according to the present method: For plates 0.270 in. (approx.6.86 mm) thick milled from plates 4.5 in. (114.3 mm) thick, perform pre-weld solution heating at 890 F (477 C) for 1 hour, then cool in air. After friction stir welding, perform solution heating for 10 minutes, quench, hold at room temperature for 96 hours, then age at 250 F (121 C) for 5 hours followed by 325 F (163 C) for 27 hours.

  6. New Materials Design Through Friction Stir Processing Techniques

    SciTech Connect

    Buffa, G.; Fratini, L.; Shivpuri, R.

    2007-04-07

    Friction Stir Welding (FSW) has reached a large interest in the scientific community and in the last years also in the industrial environment, due to the advantages of such solid state welding process with respect to the classic ones. The complex material flow occurring during the process plays a fundamental role in such solid state welding process, since it determines dramatic changes in the material microstructure of the so called weld nugget, which affects the effectiveness of the joints. What is more, Friction Stir Processing (FSP) is mainly being considered for producing high-strain-rate-superplastic (HSRS) microstructure in commercial aluminum alloys. The aim of the present research is the development of a locally composite material through the Friction Stir Processing (FSP) of two AA7075-T6 blanks and a different material insert. The results of a preliminary experimental campaign, carried out at the varying of the additional material placed at the sheets interface under different conditions, are presented. Micro and macro observation of the such obtained joints permitted to investigate the effects of such process on the overall joint performance.

  7. The Formability of Friction Stir Welds in Automotive Stamping Environments

    SciTech Connect

    Grant, Glenn J.; Davies, Richard W.; Stephens, Elizabeth V.; Wazny, Scott; Kaunitz, Leon; Waldron, Douglas J.

    2006-02-01

    Automobile body and truck cab structures are composed primarily of stampings formed from monolithic and constant gage blanks. Cost and weight penalties can arise when strength or other requirements in one small area of the part leads to the use of a material or gage that is overmatched to the needs of the rest of the stamping. Tailor Welded Blanks (TWBs) are hybrid sheet products composed of either different materials or different thickness sheets that are joined together, then subjected to a stamping operation to create a formed assembly. The strategy is employed generally to save weight and material costs in the formed assembly by placing higher strength or thicker sections only where needed. The forming or stamping process requires the joint to be severely deformed along with the parent sheets. Aluminum TWBs for automotive applications are particularly problematic because of the low formability of aluminum weld metal. Friction Stir Welding (FSW) is a process recently applied to Aluminum TWBs that has the potential to produce a higher quality weld. The current study presents data on the mechanical properties, formability, and FSW weld process parameter development for friction stir welded aluminum, Tailor Welded Blanks. Friction stir welded TWBs can be shown to have higher formability, higher ductility, and lower defect content than many competing joining processes, and they can be fabricated at speeds appropriate for automotive manufacturing.

  8. The Formability of Friction Stir Welds in Automotive Stamping Environments

    SciTech Connect

    Grant, Glenn J.; Davies, Richard W.; Stephens, Elizabeth V.; wazny, scott; Kaunitz, Leon; Waldron, D.

    2005-04-01

    Automobile body and truck cab structures are composed primarily of stampings formed from monolithic and constant gage blanks. Cost and weight penalties can arrise when strength or other requirements in one small area of the part leads to the use of a material or gage that is overmatched to the needs of the rest of the stamping. Tailor Welded Blanks (TWBs) are hybrid sheet products composed of either different materials or different thickness sheets that are joined together, then subjected to a stamping operation to create a formed assembly. The strategy is employed generally to save weight and material costs in the formed assembly by placing higher strength or thicker sections only where needed. The forming or stamping process requires the joint to be severely deformed along with the parent sheets. Aluminum TWBs for automotive applications are particularly problematic because of the low formability of aluminum weld metal. Friction Stir Welding (FSW) is a process recently applied to Aluminum TWBs that has the potential to produce a higher quality weld. The current study presents data on the mechanical properties, formability, and FSW weld process parameter development for friction stir woined, aluminum, Tailor Welded Blanks. Friction stir welded TWBs can be shown to have higher formability, higher ductility, and lower defect content than many competing joining processes, and they can be fabricated at speeds appropriate for automotive manufacturing.

  9. Macro-instability: a chaotic flow component in stirred tanks.

    PubMed

    Hasal, Pavel; Jahoda, Milan; Fort, Ivan

    2008-02-13

    Chaotic features of the macro-instability (MI) of flow patterns in stirred tanks are studied in this paper. Datasets obtained by measuring the axial component of the fluid velocity and the tangential force affecting the baffles are used. Two geometrically identical, flat-bottomed cylindrical mixing tanks (diameter of 0.3m) stirred with either pitched blade turbine impellers or Rushton turbine impeller are used in the experiments, and water and aqueous glycerol solutions are used as the working liquids. First, the presence of the MI component in the data is examined by spectral analysis. Then, the MI components are identified in the data using the proper orthogonal decomposition (POD) technique. The attractors of the macro-instability are reconstructed using either the POD eigenmodes or a method of delays and finally the attractor invariants are evaluated. The dependence of the correlation dimension and maximum Lyapunov exponent on the vessel operational conditions is determined together with their distribution within the tank. No significant spatial variability of the correlation dimension value is observed. Its value is strongly influenced by impeller speed and by the vessel-impeller geometry. More profound spatial distribution is displayed by the maximum Lyapunov exponent taking distinctly positive values. These two invariants, therefore, can be used to locate distinctive regions with qualitatively different MI dynamics within the stirred tank. PMID:17673415

  10. Recent Developments in Friction Stir Welding of Al-alloys

    NASA Astrophysics Data System (ADS)

    Çam, Gürel; Mistikoglu, Selcuk

    2014-06-01

    The diversity and never-ending desire for a better life standard result in a continuous development of the existing manufacturing technologies. In line with these developments in the existing production technologies the demand for more complex products increases, which also stimulates new approaches in production routes of such products, e.g., novel welding procedures. For instance, the friction stir welding (FSW) technology, developed for joining difficult-to-weld Al-alloys, has been implemented by industry in manufacturing of several products. There are also numerous attempts to apply this method to other materials beyond Al-alloys. However, the process has not yet been implemented by industry for joining these materials with the exception of some limited applications. The microstructures and mechanical properties of friction stir welded Al-alloys existing in the open literature will be discussed in detail in this review. The correlations between weld parameters used during FSW and the microstructures evolved in the weld region and thus mechanical properties of the joints produced will be highlighted. However, the modeling studies, material flow, texture formation and developments in tool design are out of the scope of this work as well as the other variants of this technology, such as friction stir spot welding (FSSW).

  11. A to Stirred-Liquid-Bath-Based Blackbody Source

    NASA Astrophysics Data System (ADS)

    Wang, J.; Yuan, Z.; Hao, X.; Wang, T.; Duan, Y.

    2015-08-01

    At the national facility for blackbody source radiance temperature calibration of the National Institute of Metrology, China, a stirred liquid bath blackbody was developed for use as a radiance temperature reference source, which has a temperature range from to . This blackbody source consists of a stirred liquid bath, a blackbody cavity, a standard capsule platinum resistance thermometer, and a dry-air purging system. The cavity is cylindrical with grooves on the inner wall. The cavity is 80 mm in diameter, with a depth of 520 mm, and is immersed in a bath filled with a water-ethylene glycol mixture. The average normal emissivity of the cavity is calculated to be better than 0.9999 with V grooves and when painted with Nextel 811-21 coating. The temperature stability of the blackbody source is over a period of 20 min, and the temperature uniformity of the cavity bottom is . The standard uncertainty of the radiance temperature of the stirred liquid bath blackbody source is estimated to be.

  12. New Materials Design Through Friction Stir Processing Techniques

    NASA Astrophysics Data System (ADS)

    Buffa, G.; Fratini, L.; Shivpuri, R.

    2007-04-01

    Friction Stir Welding (FSW) has reached a large interest in the scientific community and in the last years also in the industrial environment, due to the advantages of such solid state welding process with respect to the classic ones. The complex material flow occurring during the process plays a fundamental role in such solid state welding process, since it determines dramatic changes in the material microstructure of the so called weld nugget, which affects the effectiveness of the joints. What is more, Friction Stir Processing (FSP) is mainly being considered for producing high-strain-rate-superplastic (HSRS) microstructure in commercial aluminum alloys. The aim of the present research is the development of a locally composite material through the Friction Stir Processing (FSP) of two AA7075-T6 blanks and a different material insert. The results of a preliminary experimental campaign, carried out at the varying of the additional material placed at the sheets interface under different conditions, are presented. Micro and macro observation of the such obtained joints permitted to investigate the effects of such process on the overall joint performance.

  13. Thermo-Mechanical Processing in Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Schneider, Judy

    2003-01-01

    Friction stir welding is a solid-phase joining, or welding process that was invented in 1991 at The Welding Institute (TWI). The process is potentially capable of joining a wide variety of aluminum alloys that are traditionally difficult to fusion weld. The friction stir welding (FSW) process produces welds by moving a non-consumable rotating pin tool along a seam between work pieces that are firmly clamped to an anvil. At the start of the process, the rotating pin is plunged into the material to a pre-determined load. The required heat is produced by a combination of frictional and deformation heating. The shape of the tool shoulder and supporting anvil promotes a high hydrostatic pressure along the joint line as the tool shears and literally stirs the metal together. To produce a defect free weld, process variables (RPM, transverse speed, and downward force) and tool pin design must be chosen carefully. An accurate model of the material flow during the process is necessary to guide process variable selection. At MSFC a plastic slip line model of the process has been synthesized based on macroscopic images of the resulting weld material. Although this model appears to have captured the main features of the process, material specific interactions are not understood. The objective of the present research was to develop a basic understanding of the evolution of the microstructure to be able to relate it to the deformation process variables of strain, strain rate, and temperature.

  14. Microstructural Characterization of Friction Stir Welded Aluminum-Steel Joints

    NASA Astrophysics Data System (ADS)

    Patterson, Erin E.; Hovanski, Yuri; Field, David P.

    2016-06-01

    This work focuses on the microstructural characterization of aluminum to steel friction stir welded joints. Lap weld configuration coupled with scribe technology used for the weld tool have produced joints of adequate quality, despite the significant differences in hardness and melting temperatures of the alloys. Common to friction stir processes, especially those of dissimilar alloys, are microstructural gradients including grain size, crystallographic texture, and precipitation of intermetallic compounds. Because of the significant influence that intermetallic compound formation has on mechanical and ballistic behavior, the characterization of the specific intermetallic phases and the degree to which they are formed in the weld microstructure is critical to predicting weld performance. This study used electron backscatter diffraction, energy dispersive spectroscopy, scanning electron microscopy, and Vickers micro-hardness indentation to explore and characterize the microstructures of lap friction stir welds between an applique 6061-T6 aluminum armor plate alloy and a RHA homogeneous armor plate steel alloy. Macroscopic defects such as micro-cracks were observed in the cross-sectional samples, and binary intermetallic compound layers were found to exist at the aluminum-steel interfaces of the steel particles stirred into the aluminum weld matrix and across the interfaces of the weld joints. Energy dispersive spectroscopy chemical analysis identified the intermetallic layer as monoclinic Al3Fe. Dramatic decreases in grain size in the thermo-mechanically affected zones and weld zones that evidenced grain refinement through plastic deformation and recrystallization. Crystallographic grain orientation and texture were examined using electron backscatter diffraction. Striated regions in the orientations of the aluminum alloy were determined to be the result of the severe deformation induced by the complex weld tool geometry. Many of the textures observed in the weld

  15. Microstructural Characterization of Friction Stir Welded Aluminum-Steel Joints

    NASA Astrophysics Data System (ADS)

    Patterson, Erin E.; Hovanski, Yuri; Field, David P.

    2016-03-01

    This work focuses on the microstructural characterization of aluminum to steel friction stir welded joints. Lap weld configuration coupled with scribe technology used for the weld tool have produced joints of adequate quality, despite the significant differences in hardness and melting temperatures of the alloys. Common to friction stir processes, especially those of dissimilar alloys, are microstructural gradients including grain size, crystallographic texture, and precipitation of intermetallic compounds. Because of the significant influence that intermetallic compound formation has on mechanical and ballistic behavior, the characterization of the specific intermetallic phases and the degree to which they are formed in the weld microstructure is critical to predicting weld performance. This study used electron backscatter diffraction, energy dispersive spectroscopy, scanning electron microscopy, and Vickers micro-hardness indentation to explore and characterize the microstructures of lap friction stir welds between an applique 6061-T6 aluminum armor plate alloy and a RHA homogeneous armor plate steel alloy. Macroscopic defects such as micro-cracks were observed in the cross-sectional samples, and binary intermetallic compound layers were found to exist at the aluminum-steel interfaces of the steel particles stirred into the aluminum weld matrix and across the interfaces of the weld joints. Energy dispersive spectroscopy chemical analysis identified the intermetallic layer as monoclinic Al3Fe. Dramatic decreases in grain size in the thermo-mechanically affected zones and weld zones that evidenced grain refinement through plastic deformation and recrystallization. Crystallographic grain orientation and texture were examined using electron backscatter diffraction. Striated regions in the orientations of the aluminum alloy were determined to be the result of the severe deformation induced by the complex weld tool geometry. Many of the textures observed in the weld

  16. The controversial age of Kilimanjaro's plateau glaciers

    NASA Astrophysics Data System (ADS)

    Uglietti, Chiara; Zapf, Alexander; Szidat, Sönke; Salazar, Gary; Hardy, Doug; Schwikowski, Margit

    2015-04-01

    Interpreting climate signals contained in natural archives requires a precise chronology. Radiocarbon analysis can be a powerful tool for dating high-altitude ice cores, especially for the lowermost segments for which ice flow-induced thinning limits the counting of annual layers. Radiocarbon dating has been applied to ice cores containing sufficient organic material, which is a limiting factor to the wider application of this technique. We present a novel radiocarbon dating approach using carbonaceous aerosols enclosed in the ice to help resolve the debate about the age of the Kilimanjaro's plateau glaciers. Paleoclimate reconstructions based on six ice cores drilled in 2000 assigned a basal age of 11'700 years. A recent study claims recurring cycles of waxing and waning controlled primarily by atmospheric moisture and an absence of the ice bodies was suggested for 1200 AD. The Kilimanjaro ice fields are subject to rapid areal shrinkage and thinning and are expected to disappear within several decades. Resolving the controversy of the time frame for the extinction of the Kilimanjaro ice might have wide implications for the understanding of the natural climate variability in the tropics. A stratigraphic sequence of samples from the exposed vertical ice cliffs at the margins of the Northern Ice Field (NIF) was collected in 2011. A total of 45 horizontal short cores (50 cm length) were extracted from 22 horizons characterized by varying micro-particle concentrations. Additionally, 3 samples were taken from the glacier surface to investigate a potential age offset. All samples were shipped frozen to Paul Scherrer Institute, decontaminated in a cold room by removing the outer layer (0.3 mm) and by rinsing the samples with ultra-pure water. The insoluble carbonaceous particles were filtrated by using freshly preheated quartz fibre filters. Procedural blanks were estimated using artificial ice blocks of frozen ultra-pure water treated as real ice samples and were

  17. Borderline viability: controversies in caring for the extremely premature infant.

    PubMed

    Leuthner, Steven R

    2014-12-01

    Controversy surrounding the decision to resuscitate at the limits or borderline of viability has been at the center of neonatal ethical debate for decades. This debate has led to numerous reports from individual institutions, councils, and advisory committees that all have remarkable consistency in the development of gestational age-based guidelines. This article reviews legal or regulatory concerns that may contradict ethical discussion and guidelines, discriminatory and scientific basis concerns with consensus guidelines, and personal controversy about how to determine best interest. Guidelines are a reasonable place to start in helping determine parental authority and autonomy. The article also addresses controversies raised in counseling and costs. PMID:25459775

  18. Controversies in the Management of Papillary Thyroid Cancer Revisited

    PubMed Central

    Guerrero, Marlon A.; Clark, Orlo H.

    2011-01-01

    The debate on the appropriate treatment of patients with papillary thyroid cancer (PTC) has persisted for several decades. The main controversies focus on the extent of surgery, the timing of central neck dissection, and the indications for radioactive iodine ablation. These controversies continue, for the most part, due to the good prognosis of PTC patients and the questionable effect these treatment modalities have on patient survival. This paper addresses these three controversies and the role of molecular tumor markers in the appropriate treatment selection. PMID:22091417

  19. Stirring-assisted assembly of nanowires at liquid-solid interfaces

    NASA Astrophysics Data System (ADS)

    Li, Wen-Ze; Wei, Wei; Chen, Jun-Yi; He, Ji-Xiang; Xue, Sheng-Nan; Zhang, Jing; Liu, Xia; Li, Xiang; Fu, Yu; Jiao, Yong-Hua; Zhang, Kai; Liu, Fuchun; Han, En-Hou

    2013-03-01

    The assembly of Ag nanowires on quartz substrates from suspensions of water and ethylene glycol under stirring has been investigated. The introduction of stirring makes a remarkable difference to the assembly morphology. Firstly, the surface coverage of Ag nanowires is increased by a factor of 4 (in water) and 8 (in ethylene glycol) with stirring. Secondly, the Ag nanowires assembled in the stirred ethylene glycol dispersion were highly aligned. The influence of the surface of substrates, solvents and profile of the nanowires on the alignment has been explored, which indicates that stirring is an efficient way to generate nanowire arrays. This study has revealed the great potential of the stirring-assisted assembly technique in producing structurally controlled nanoarchitectures, opening up new opportunities for manufacturing ordered nanomaterials.

  20. Investigation of the Microstructure of Joints of Aluminum Alloys Produced by Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Kolubaev, E. A.

    2015-02-01

    Special features of the microstructure of joints of aluminum-magnesium and aluminum-copper alloys produced by friction stir welding are analyzed. It is demonstrated that a layered structure with ultradisperse grains is produced by friction stir welding at the center of the weld joint. An analogy is drawn between the microstructures of joints produced by friction stir welding and surface layer produced by sliding friction.

  1. Superplastic Forming of Aluminum Multisheet Structures Fabricated Using Friction Stir Welding and Refill Friction Stir Spot Welding

    SciTech Connect

    Grant, Glenn J.; Herling, Darrell R.; Arbegast, William J.; Allen, Casey D.; Degen, Cassandra M.

    2006-12-20

    Superplastically-formed structural panels are growing in their applications in aerospace, aircraft, automotive, and other industries. Generally, monolithic sheets are employed, limiting the size and complexity of the final part. However, more complex and larger final geometries are possible if individual sheet materials can be joined together through an appropriate joining technology, then SPF formed to final shape. The primary challenge in this type of SPF fabrication has been making a joint between the sheets that will survive the SPF forming event and display the correct amount of elongation in the joint relative to the base materials being formed. Friction Stir Welding is an ideal joining technology for SPF applications because the forming response of the weld metal at SPF conditions is adjustable by selecting different weld process parameters during initial joining. This allows the SPF deformation in the weld metal to be “tuned” to the deformation of the parent sheet to prevent early failure from occurring in either the weld metal or the parent sheet due to mismatched SPF flow stresses. Industrial application of the concept of matching flow stresses is currently being pursued on a program at the Pacific Northwest National Laboratory on room temperature formed friction stir welded tailor welded blanks for heavy truck applications. Flow stress matching and process parameter “tuning” is also important in the fabrication of SPF multisheet structural panels. These panels are fabricated by joining three sheets together with alternating welds top and bottom, so that each weld penetrates only two of the three sheets. This sheet pack is then sealed with a weld seam around the outside and hot gas is introduced between the sheets through a welded tube. Under SPF conditions the sheet pack inflates to produce an internally supported structure. In this paper we presents results on an investigation into using FSW and Refill Friction Stir Spot Welding to fabricated

  2. Commentary: The Anatomy of Controversy: Freedom and Responsibility for Teaching.

    ERIC Educational Resources Information Center

    Carter, Jack L.

    1979-01-01

    The role of the biology teacher in American schools and colleges is discussed with regard to the social, political, and economic implications of new discoveries in science. Controversial ethical issues related to teaching human genetics are presented. (SA)

  3. Understanding and Developing Controversial Issues in College Courses.

    ERIC Educational Resources Information Center

    Payne, Brian K.; Gainey, Randy R.

    2003-01-01

    Discusses common controversial issues in different college disciplines, such as the death penalty and drug legalization. Also suggests useful methods for encouraging enlightening discussions, such as verbal and physical cues, student-centered activities, and text selection. (SLD)

  4. Building on faults: How to represent controversies with digital methods.

    PubMed

    Venturini, Tommaso

    2012-10-01

    In a previous article in this journal, I introduced Bruno Latour's cartography of controversies and I discussed half of it, namely how to observe techno-scientific controversies. In this article I will concentrate on the remaining half: how to represent the complexity of social debates in a legible form. In my previous paper, we learnt how to explore the richness of collective existence through Actor-Network Theory. In this one, I will discuss how to render such complexity through an original visualization device: the controversy-website. Capitalizing on the potential of digital technologies, the controversy-website has been developed as a multilayered toolkit to trace and aggregate information on public debates. PMID:23832559

  5. A Critique of "Controversial Medical Treatments of Learning Disabilities"

    ERIC Educational Resources Information Center

    Feingold, Benjamin F.

    1977-01-01

    The author replies to the article titled "Controversial Medical Treatments of Learning Disabilities" (R. Sieben), and discusses research on the relationship between food additives and hyperactivity, and dietary treatments for learning disabled children. (IM)

  6. Superluminal Neutrinos: The Good Kind of Science Controversy

    NASA Astrophysics Data System (ADS)

    Lucibella, Michael

    2012-03-01

    After OPERA released results indicating neutrinos were traveling faster than the speed of light, a number of vocal of scientists said that they shouldn't have prematurely engaged in ``science by press release.'' However, controversial claims like this, if handled right, can actually be a boon to science. Getting the public interested in cutting edge physics is notoriously difficult, but the public is always interested in hearing about a controversy. The press conference and following debate becomes a great teaching moment that offers the public a unique opportunity to get an inside and have an in-depth look at how science works. Scientists willing to publicly engage in this kind of civil controversy are important because when other scientific controversies arise, ones with major public policy implications, the public starts out with a better understanding of how science works, and scientists have better practice managing questions from the public.

  7. Recent developments in health care law: culture and controversy.

    PubMed

    Berry, Roberta M; Bliss, Lisa; Caley, Sylvia; Lombardo, Paul A; Wolf, Leslie E

    2013-03-01

    This article reviews recent developments in health care law, focusing on controversy at the intersection of health care law and culture. The article addresses: emerging issues in federal regulatory oversight of the rapidly developing market in direct-to-consumer genetic testing, including questions about the role of government oversight and professional mediation of consumer choice; continuing controversies surrounding stem cell research and therapies and the implications of these controversies for healthcare institutions; a controversy in India arising at the intersection of abortion law and the rights of the disabled but implicating a broader set of cross-cultural issues; and the education of U.S. health care providers and lawyers in the theory and practice of cultural competency. PMID:23180091

  8. 37 CFR 351.3 - Controversy and further proceedings.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... participant who has filed a written direct statement. (2) Bad faith inflation of claim. If the Copyright Royalty Judges determine that a participant asserts in bad faith an amount in controversy in excess of...

  9. 37 CFR 351.3 - Controversy and further proceedings.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... participant who has filed a written direct statement. (2) Bad faith inflation of claim. If the Copyright Royalty Judges determine that a participant asserts in bad faith an amount in controversy in excess of...

  10. Summerhill Dismembered: Using Controversy to Motivate Adult Learners.

    ERIC Educational Resources Information Center

    Murray, Louis; Lawrence, Brenda

    1995-01-01

    Workshops for teachers engaged in practitioner-based inquiry centered on the controversial issues raised by a television documentary on the Summerhill School. Learners normally engaged in distance education were motivated by the processes of dissent, argument, and disputation. (SK)

  11. The Chilling Effect: How Do Researchers React to Controversy?

    PubMed Central

    Kempner, Joanna

    2008-01-01

    Background Can political controversy have a “chilling effect” on the production of new science? This is a timely concern, given how often American politicians are accused of undermining science for political purposes. Yet little is known about how scientists react to these kinds of controversies. Methods and Findings Drawing on interview (n = 30) and survey data (n = 82), this study examines the reactions of scientists whose National Institutes of Health (NIH)-funded grants were implicated in a highly publicized political controversy. Critics charged that these grants were “a waste of taxpayer money.” The NIH defended each grant and no funding was rescinded. Nevertheless, this study finds that many of the scientists whose grants were criticized now engage in self-censorship. About half of the sample said that they now remove potentially controversial words from their grant and a quarter reported eliminating entire topics from their research agendas. Four researchers reportedly chose to move into more secure positions entirely, either outside academia or in jobs that guaranteed salaries. About 10% of the group reported that this controversy strengthened their commitment to complete their research and disseminate it widely. Conclusions These findings provide evidence that political controversies can shape what scientists choose to study. Debates about the politics of science usually focus on the direct suppression, distortion, and manipulation of scientific results. This study suggests that scholars must also examine how scientists may self-censor in response to political events. PMID:19018657

  12. Friction Stir Welding Development at NASA, Marshall Space Flight Center

    NASA Technical Reports Server (NTRS)

    McGill, Preston; Gentz, Steve (Technical Monitor)

    2001-01-01

    Friction stir welding (FSW) is a solid state process that pan be used to join materials without melting. The process was invented by The Welding Institute (TWI), Cambridge, England. Friction stir welding exhibits several advantages over fusion welding in that it produces welds with fewer defects and higher joint efficiency and is capable of joining alloys that are generally considered non-weldable with a fusion weld process. In 1994, NASA-Marshall began collaborating with TWI to transform FSW from a laboratory curiosity to a viable metal joining process suitable for manufacturing hardware. While teamed with TWI, NASA-Marshall began its own FSW research and development effort to investigate possible aerospace applications for the FSW process. The work involved nearly all aspects of FSW development, including process modeling, scale-up issues, applications to advanced materials and development of tooling to use FSW on components of the Space Shuttle with particular emphasis on aluminum tanks. The friction stir welding process involves spinning a pin-tool at an appropriate speed, plunging it into the base metal pieces to be joined, and then translating it along the joint of the work pieces. In aluminum alloys the rotating speed typically ranges from 200 to 400 revolutions per minute and the translation speed is approximately two to five inches per minute. The pin-tool is inserted at a small lead angle from the axis normal to the work piece and requires significant loading along the axis of the tool. An anvil or reaction structure is required behind the welded material to react the load along the axis of the pin tool. The process requires no external heat input, filler material, protective shielding gas or inert atmosphere typical of fusion weld processes. The FSW solid-state weld process has resulted in aluminum welds with significantly higher strengths, higher joint efficiencies and fewer defects than fusion welds used to join similar alloys.

  13. Retractable Pin Tools for the Friction Stir Welding Process

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Two companies have successfully commercialized a specialized welding tool developed at the Marshall Space Flight Center (MSFC). Friction stir welding uses the high rotational speed of a tool and the resulting frictional heat created from contact to crush, 'stir' together, and forge a bond between two metal alloys. It has had a major drawback, reliance on a single-piece pin tool. The pin is slowly plunged into the joint between two materials to be welded and rotated as high speed. At the end of the weld, the single-piece pin tool is retracted and leaves a 'keyhole,' something which is unacceptable when welding cylindrical objects such as drums, pipes and storage tanks. Another drawback is the requirement for different-length pin tools when welding materials of varying thickness. An engineer at the MSFC helped design an automatic retractable pin tool that uses a computer-controlled motor to automatically retract the pin into the shoulder of the tool at the end of the weld, preventing keyholes. This design allows the pin angle and length to be adjusted for changes in material thickness and results in a smooth hole closure at the end of the weld. Benefits of friction stir welding, using the MSFC retractable pin tool technology, include the following: The ability to weld a wide range of alloys, including previously unweldable and composite materials; provision of twice the fatigue resistance of fusion welds and no keyholes; minimization of material distortion; no creation of hazards such as welding fumes, radiation, high voltage, liquid metals, or arcing; automatic retraction of the pin at the end of the weld; and maintaining full penetration of the pin.

  14. Controlling Force and Depth in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Adams, Glynn; Loftus, Zachary; McCormac, Nathan; Venable, Richard

    2005-01-01

    Feedback control of the penetration force applied to a pin tool in friction stir welding has been found to be a robust and reliable means for controlling the depth of penetration of the tool. This discovery has made it possible to simplify depth control and to weld with greater repeatability, even on workpieces with long weld joints. Prior to this discovery, depths of penetration in friction stir welding were controlled by hard-tooled roller assemblies or by depth actuators controlled by feedback from such external sensors as linear variable-differential transformers or laser-based devices. These means of control are limited: A hard-tooled roller assembly confines a pin tool to a preset depth that cannot be changed easily during the welding process. A measurement by an external sensor is only an indirect indicative of the depth of penetration, and computations to correlate such a measurement with a depth of penetration are vulnerable to error. The present force-feedback approach exploits the proportionality between the depth and the force of penetration Unlike a depth measurement taken by an external sensor, a force measurement can be direct because it can be taken by a sensor coupled directly to the pin tool. The reading can be processed through a modern electronic servo control system to control an actuator to keep the applied penetration force at the desired level. In comparison with the older depth-control methods described above, this method offers greater sensitivity to plasticizing of the workpiece metal and is less sensitive to process noise, resulting in a more consistent process. In an experiment, a tapered panel was friction stir welded while controlling the force of penetration according to this method. The figure is a plot of measurements taken during the experiment, showing that force was controlled with a variation of 200 lb (890 N), resulting in control of the depth of penetration with a variation of 0.004 in. (0.1 mm).

  15. Friction Stir Spot Welding of Advanced High Strength Steels

    SciTech Connect

    Santella, Michael L; Hovanski, Yuri; Grant, Glenn J; Frederick, D Alan; Dahl, Michael E

    2009-02-01

    Friction stir spot welding was used to join two advanced high-strength steels using polycrystalline cubic boron nitride tooling. Numerous tool designs were employed to study the influence of tool geometry on weld joints produced in both DP780 and a hot-stamp boron steel. Tool designs included conventional, concave shouldered pin tools with several pin configurations; a number of shoulderless designs; and a convex, scrolled shoulder tool. Weld quality was assessed based on lap shear strength, microstructure, microhardness, and bonded area. Mechanical properties were functionally related to bonded area and joint microstructure, demonstrating the necessity to characterize processing windows based on tool geometry.

  16. Friction Stir Spot Welding of Advanced High Strength Steels

    SciTech Connect

    Hovanski, Yuri; Santella, M. L.; Grant, Glenn J.

    2009-12-28

    Friction stir spot welding was used to join two advanced high-strength steels using polycrystalline cubic boron nitride tooling. Numerous tool designs were employed to study the influence of tool geometry on weld joints produced in both DP780 and a hot-stamp boron steel. Tool designs included conventional, concave shouldered pin tools with several pin configurations; a number of shoulderless designs; and a convex, scrolled shoulder tool. Weld quality was assessed based on lap shear strength, microstructure, microhardness, and bonded area. Mechanical properties were functionally related to bonded area and joint microstructure, demonstrating the necessity to characterize processing windows based on tool geometry.

  17. FRICTION STIR MICROSTRUCTURAL MODIFICATION OF INVESTMENT CAST F357

    SciTech Connect

    Jana, s.; Mishra, Rajiv S.; Chou, H. N.; Herling, Darrell R.

    2007-02-09

    A hypoeutectic Al-Si alloy has been friction stir processed in this study using various run parameter combinations. Tensile test results indicate at least three times improvement in ductility value over as-cast T6 condition because of refinement in Si particle size. Si particle size and shape has been quantified and correlated with mechanical properties. Tool rotation rate seems to have the most significant effect on properties. Higher tool rotation rate resulted in more uniform and homogeneous microstructure though some anomaly is observed at very high tool rotation rate.

  18. Developing Friction Stir Welding Process Model for ICME Application

    NASA Astrophysics Data System (ADS)

    Yang, Yu-Ping

    2015-01-01

    A framework for developing a product involving manufacturing processes was developed with integrated computational materials engineering approach. The key component in the framework is a process modeling tool which includes a thermal model, a microstructure model, a thermo-mechanical, and a property model. Using friction stir welding (FSW) process as an example, development of the process modeling tool was introduced in detail. The thermal model and the microstructure model of FSW of steels were validated with the experiment data. The model can predict reasonable temperature and hardness distributions as observed in the experiment. The model was applied to predict residual stress and joint strength of a pipe girth weld.

  19. Friction stir welding tool and process for welding dissimilar materials

    DOEpatents

    Hovanski, Yuri; Grant, Glenn J; Jana, Saumyadeep; Mattlin, Karl F

    2013-05-07

    A friction stir welding tool and process for lap welding dissimilar materials are detailed. The invention includes a cutter scribe that penetrates and extrudes a first material of a lap weld stack to a preselected depth and further cuts a second material to provide a beneficial geometry defined by a plurality of mechanically interlocking features. The tool backfills the interlocking features generating a lap weld across the length of the interface between the dissimilar materials that enhances the shear strength of the lap weld.

  20. Production of verruculogen by Penicillium estinogenum in stirred fermenters.

    PubMed

    Day, J B; Mantle, P G; Shaw, B I

    1980-04-01

    A spectrofluorometric assay for the estimation of the tremorgenic mycotoxin verruculogen in crude mycelial extract has been devised and used to determine concentrations as low as 0.2 microgram ml-1. Verruculogen production by Penicillium estinogenum has been extended from surface culture to submerged culture in 60 1 stirred fermenters, in which the maximum cell-associated mycotoxin yield [5 mg (100 ml culture)-1] was obtained within 7 d. It was found necessary to supplement the medium (Czapek Dox broth plus 0.5% yeast extract) with calcium chloride (2%) to induce profuse sporulation (2 X 10(7) conidia ml-1). PMID:7420051

  1. Fatigue Crack Growth in Peened Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Forth, Scott C.; Hatamleh, Omar

    2008-01-01

    Friction stir welding induces residual stresses that accelerates fatigue crack growth in the weld nugget. Shot peening over the weld had little effect on growth rate. Laser peening over the weld retarded the growth rate: Final crack growth rate was comparable to the base, un-welded material. Crack tunneling evident from residual compressive stresses. 2195-T8 fracture surfaces were highly textured. Texturing makes comparisons difficult as the material system is affecting the data as much as the processing. Material usage becoming more common in space applications requiring additional work to develop useful datasets for damage tolerance analyses.

  2. Design and Testing of a Friction Stir Processing Machine for Laboratory Research

    SciTech Connect

    Karen S. Miller; Rodney J. Bitsoi; Eric D. Larsen; Herschel B. Smartt

    2006-08-01

    This presentation describes the design, fabrication and testing of a friction stir processing machine. The machine is intended to be a flexible research tool for a broad range of friction stir processing studies. The machine design also addresses the need for an affordable, robust design for general laboratory use.

  3. Effects of Laser Peening, and Shot Peening, on Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Hatamleh, Omar; Hackel, Lloyd; Rankin, Jon; Truong, Chanh; Walter, Matt

    2006-01-01

    A viewgraph presentation describing the effects of laser peening and shot peening on friction stir welding is shown. The topics include: 1) Background; 2) Friction Stir Welding (FSW); 3) Microstructure; 4) Laser & Shot Peening; 5) Residual Stresses; 6) Tensile Behavior; 7) Fatigue Life & Surface Roughness; 8) Crack Growth; and 9) Benefits.

  4. The influence of stirring rate on biopharmaceutical properties of Eudragit RS microspheres.

    PubMed

    Mateovic, T; Kriznar, B; Bogataj, M; Mrhar, A

    2002-01-01

    Eudragit RS microspheres containing pipemidic acid, as a model drug, were prepared by the solvent evaporation method using an acetone/liquid paraffin solvent system. The aim of the work was to evaluate the influence of stirring rate on the average particle size, particle morphology, drug content and release kinetics, as well as the influence of particle size on microsphere morphology, drug content and release kinetics. Stirring rate has been found to significantly influence the average diameter of microspheres. The average diameter decreases as the stirring rate increases. This can be explained by production of a finer dispersion of droplets when higher stirring rates are applied and, consequently, by the formation of smaller microspheres. With increasing stirring rate and increasing fraction particle size the drug content also increases. It is assumed that this dependence is a consequence of an uneven diffusion of the drug from the inner to the outer emulsion phase, and an uneven encapsulation of drug particles during the preparation. Drug release follows the Higuchi model. As seen from SEM photographs, larger microspheres are more porous and the microspheres produced at higher stirring rates are more porous than those produced at lower stirring rates. This explains the unexpected finding that the release rate increases as the fraction particle size and the stirring rate increase. PMID:11811756

  5. Stirring and mixing effects on oscillations and inhomogeneities in the minimal bromate oscillator

    NASA Astrophysics Data System (ADS)

    Dutt, A. K.; Menzinger, M.

    1999-04-01

    Stirring and mixing effects on the oscillations and inhomogeneities in the bromate-bromide-cerous system (minimal bromate oscillator) have been investigated in a continuously fed stirred tank reactor (CSTR). A movable microelectrode is used to monitor the inhomogeneities inside the CSTR in an oscillating phase. The results are explained in terms of the theory of imperfect mixing.

  6. 7 CFR 58.711 - Cheddar, colby, washed or soaked curd, granular or stirred curd cheese.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... stirred curd cheese. 58.711 Section 58.711 Agriculture Regulations of the Department of Agriculture... soaked curd, granular or stirred curd cheese. Cheese, used in the manufacture of pasteurized process cheese products should possess a pleasing and desirable taste and odor consistent with the age of...

  7. 7 CFR 58.711 - Cheddar, colby, washed or soaked curd, granular or stirred curd cheese.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... stirred curd cheese. 58.711 Section 58.711 Agriculture Regulations of the Department of Agriculture... soaked curd, granular or stirred curd cheese. Cheese, used in the manufacture of pasteurized process cheese products should possess a pleasing and desirable taste and odor consistent with the age of...

  8. 7 CFR 58.711 - Cheddar, colby, washed or soaked curd, granular or stirred curd cheese.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... stirred curd cheese. 58.711 Section 58.711 Agriculture Regulations of the Department of Agriculture... soaked curd, granular or stirred curd cheese. Cheese, used in the manufacture of pasteurized process cheese products should possess a pleasing and desirable taste and odor consistent with the age of...

  9. THE USE OF STIR-BAR SORPTIVE EXTRACTION (SBSE) FOR ANALYTICAL FOOD ANALYSIS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stir bar sorptive extraction (SBSE) is a relatively new technique which employs an adsorptive coating on a magnetic stir bar. The technique is similar to solid phase microextraction (SPME) in theory, but in practice is considerably different due to the difference in physical design. Three experime...

  10. Sampling of Malodorous Compounds in Air Using Stir Bar Sorbtive Extraction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Twisters, (poly)-dimethylsiloxane-coated magnetic stir bars, were used to measure malodorous compounds in air. In initial experiments, a minimum deployment time was determined by preloading the stir bars with 10 compounds with a range of volatilities and polarities and then monitoring their loss. ...

  11. Metal Cutting Theory and Friction Stir Welding Tool Design

    NASA Technical Reports Server (NTRS)

    Payton, Lewis N.

    2003-01-01

    Friction Stir Welding (FSW) is a relatively new industrial process that was invented at The Weld Institute (TWI, United Kingdom) and patented in 1992 under research funded by in part by the National Aeronautics and Space Administration (NASA). Often quoted advantages of the process include good strength and ductility along with minimization of residual stress and distortion. Less well advertised are the beneficial effects of this solid state welding process in the field of occupational and environmental safety. It produces superior weld products in difficult to weld materials without producing any toxic fumes or solid waste that must be controlled as hazardous waste. In fact, it reduces noise pollution in the workspace as well. In the early days of FSW, most welding was performed on modified machine tools, in particular on milling machines with modified milling cutters. In spite of the obvious milling heritage of the process, the techniques and lessons learned from almost 250 years of successful metalworking with milling machines have not been applied in the field of modern Friction Stir Welding. The goal of the current research was to study currently successful FSW tools and parameterize the process in such a way that the design of new tools for new materials could be accelerated. Along the way, several successful new tooling designs were developed for current issues at the Marshall Space Flight Center with accompanying patent disclosures

  12. Friction Stir Weld Restart+Reweld Repair Allowables

    NASA Technical Reports Server (NTRS)

    Clifton, Andrew

    2008-01-01

    A friction stir weld (FSW) repair method has been developed and successfully implemented on Al 2195 plate material for the Space Shuttle External Fuel Tank (ET). The method includes restarting the friction stir weld in the termination hole of the original weld followed by two reweld passes. Room temperature and cryogenic temperature mechanical properties exceeded minimum FSW design strength and compared well with the development data. Simulated service test results also compared closely to historical data for initial FSW, confirming no change to the critical flaw size or inspection requirements for the repaired weld. Testing of VPPA fusion/FSW intersection weld specimens exhibited acceptable strength and exceeded the minimum design value. Porosity, when present at the intersection was on the root side toe of the fusion weld, the "worst case" being 0.7 inch long. While such porosity may be removed by sanding, this "worst case" porosity condition was tested "as is" and demonstrated that porosity did not negatively affect the strength of the intersection weld. Large, 15-inch "wide panels" FSW repair welds were tested to demonstrate strength and evaluate residual stresses using photo stress analysis. All results exceeded design minimums, and photo stress analysis showed no significant stress gradients due to the presence of the restart and multi-pass FSW repair weld.

  13. Microstructural Investigation of Friction-Stir-Welded 7005 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Xu, Xuesong; Lu, Yan; Zheng, Feiyan; Chen, Bin

    2015-11-01

    This paper is aimed to investigate the microstructure of 7005 aluminum sheets joined by friction-stir welding as well as their mechanical properties. Specimens with ten different sets of welding parameters were studied. Tensile test and fracture analysis determined that the joint of the best quality was obtained at the rotation speed of 1000 rpm matching with the travel speed of 200 mm/min, and the travel speed has more impact on the ultimate tensile strength. Optical microscope observation was applied to this high-quality specimen and gave evidence to explaining the formation of the onion ring structure. Electron back-scattered diffraction (EBSD) technique was employed to characterize the textures and revealed the evolution of microstructures during friction stir processing. The EBSD results showed that the grains maintain their original orientations at relatively low deformation while the orientations rotate under increasing strain. Accumulated rotation will turn the textures into mixed shear components, which finally results in grain refinement and contributes to the high quality of the joint.

  14. A model of material flow during friction stir welding

    SciTech Connect

    Hamilton, Carter Dymek, Stanislaw; Blicharski, Marek

    2008-09-15

    Tin plated 6061-T6 aluminum extrusions were friction stir welded in a 90 deg. butt-weld configuration. A banded microstructure of interleaved layers of particle-rich and particle-poor material comprised the weld nugget. Scanning and transmission electron microscopy revealed the strong presence of tin within the particle-rich bands, but TEM foils taken from the TMAZ, HAZ and base material showed no indication of Sn-containing phases. Since tin is limited to the surface of the pre-weld extrusions, surface material flowed into the nugget region, forming the particle-rich bands. Similarly, the particle-poor bands with no tin originated from within the thickness of the extrusions. A model of material flow during friction stir welding is proposed for which the weld nugget forms as surface material extrudes from the retreating side into a plasticized zone surrounding the FSW pin. The extruded column buckles between the extrusion force driving the material into the zone and the drag force of the in-situ material resisting its entry. A banded microstructure of interleaved surface material and in-situ material, therefore, develops. The model successfully describes several of the experimentally observed weld characteristics, but the model is limited to specific conditions of material flow and assumptions regarding steady-state.

  15. Rewriting of States' Standards on Social Studies Stirs Debate

    ERIC Educational Resources Information Center

    Robelen, Erik W.

    2010-01-01

    As debate continues around the development and adoption of common standards in English and mathematics, several states are independently wrestling with rewrites of standards in a content area largely absent from that national discussion--social studies--and encountering their own shares of controversy. Flash points in the social studies debates…

  16. Protein crystallization in a 100 nl solution with new stirring equipment

    PubMed Central

    Maki, S.; Murai, R.; Yoshikawa, H. Y.; Kitatani, T.; Nakata, S.; Kawahara, H.; Hasenaka, H.; Kobayashi, A.; Okada, S.; Sugiyama, S.; Adachi, H.; Matsumura, H.; Takano, K.; Murakami, S.; Inoue, T.; Sasaki, T.; Mori, Y.

    2008-01-01

    To investigate quantitatively the effects of stirring on protein crystallization, a new stirring system which can agitate a protein solution, ∼100 nl, by providing Hagen–Poiseuille flow has been successfully developed. In addition, this new stirring system provides flow with a well defined pattern and velocity. Using this system, hen egg-white lysozyme was crystallized in 100–200 nl solutions while being stirred. The optimum stirring conditions for lysozyme crystals have been explored by evaluating the Reynolds (Re) number and the crystals obtained. Intermittent flow, as well as a low Re number, was found to contribute significantly to the growth of a smaller number of larger crystals. PMID:18421156

  17. The Effect of Premixed Al-Cu Powder on the Stir Zone in Friction Stir Welding of AA3003-H18

    NASA Astrophysics Data System (ADS)

    Abnar, B.; Kazeminezhad, M.; Kokabi, A. H.

    2015-02-01

    In this research, 3-mm-thick AA3003-H18 non-heat-treatable aluminum alloy plates were joined by friction stir welding (FSW). It was performed by adding pure Cu and premixed Cu-Al powders at various rotational speeds of 800, 1000, and 1200 rpm and constant traveling speeds of 100 mm/min. At first, the powder was filled into the gap (0.2 or 0.4 mm) between two aluminum alloy plates, and then the FSW process was performed in two passes. The microstructure, mechanical properties, and formation of intermetallic compounds were investigated in both cases of using pure Cu and premixed Al-Cu powders. The results of using pure Cu and premixed Al-Cu powders were compared in the stir zone at various rotational speeds. The copper particle distribution and formation of Al-Cu intermetallic compounds (Al2Cu and AlCu) in the stir zone were desirable using premixed Al-Cu powder into the gap. The hardness values were significantly increased by formation of Al-Cu intermetallic compounds in the stir zone and it was uniform throughout the stir zone when premixed Al-Cu powder was used. Also, longitudinal tensile strength from the stir zone was higher when premixed Al-Cu powder was used instead of pure Cu powder.

  18. Stirring in massive, young debris discs from spatially resolved Herschel images

    NASA Astrophysics Data System (ADS)

    Moór, A.; Kóspál, Á.; Ábrahám, P.; Apai, D.; Balog, Z.; Grady, C.; Henning, Th.; Juhász, A.; Kiss, Cs.; Krivov, A. V.; Pawellek, N.; Szabó, Gy. M.

    2015-02-01

    A significant fraction of main-sequence stars are encircled by dusty debris discs, where the short-lived dust particles are replenished through collisions between planetesimals. Most destructive collisions occur when the orbits of smaller bodies are dynamically stirred up, either by the gravitational effect of locally formed Pluto-sized planetesimals (self-stirring scenario), or via secular perturbation caused by an inner giant planet (planetary stirring). The relative importance of these scenarios in debris systems is unknown. Here, we present new Herschel Space Observatory imagery of 11 discs selected from the most massive and extended known debris systems. All discs were found to be extended at far-infrared wavelengths, five of them being resolved for the first time. We evaluated the feasibility of the self-stirring scenario by comparing the measured disc sizes with the predictions of the model calculated for the ages of our targets. We concluded that the self-stirring explanation works for seven discs. However, in four cases, the predicted pace of outward propagation of the stirring front, assuming reasonable initial disc masses, was far too low to explain the radial extent of the cold dust. Therefore, for HD 9672, HD 16743, HD 21997, and HD 95086, another explanation is needed. We performed a similar analysis for β Pic and HR 8799, reaching the same conclusion. We argue that planetary stirring is a promising possibility to explain the disc properties in these systems. In HR 8799 and HD 95086, we may already know the potential perturber, since their known outer giant planets could be responsible for the stirring process. Interestingly, the discs around HD 9672, HD 21997, and β Pic are also unique in harbouring detectable amount of molecular CO gas. Our study demonstrates that among the largest and most massive debris discs self-stirring may not be the only active scenario, and potentially planetary stirring is responsible for destructive collisions and debris

  19. Medical ethics: principles, persons, and perspectives: from controversy to conversation.

    PubMed

    Boyd, K M

    2005-08-01

    Medical ethics, principles, persons, and perspectives is discussed under three headings: History, Theory, and Practice. Under Theory, the author will say something about some different approaches to the study and discussion of ethical issues in medicine--especially those based on principles, persons, or perspectives. Under Practice, the author will discuss how one perspectives based approach, hermeneutics, might help in relation first to everyday ethical issues and then to public controversies. In that context some possible advantages of moving from controversy to conversation will be explored; and that will then be illustrated with reference to a current controversy about the use of human embryos in stem cell therapy research. The paper begins with history, and it begins in the author's home city of Edinburgh. PMID:16076975

  20. Teaching controversial issues in the secondary school science classroom

    NASA Astrophysics Data System (ADS)

    van Rooy, Wilhelmina

    1993-12-01

    A sample of fourteen secondary school biology teachers chosen from twelve schools were interviewed. The purpose was to determine their views on how controversial issues in science might be handled in the secondary school science classroom and whether the issues of surrogacy and human embryo experimentation were suitable controversial issues for discussion in schools. In general, teachers indicated that controversial issues deserve a more prominent place in the science curriculum because they have the potential to foster thinking, learning, and interest in science. The issues of surrogacy and human embryo experimentation were seen as appropriate contexts for learning, provided that teachers were well informed and sensitive to both the students and to the school environment.

  1. Why Is Studying the Genetics of Intelligence So Controversial?

    PubMed

    Tabery, James

    2015-01-01

    From the very beginning, studies of the nature and nurture of intelligence have been closely associated with an interest in intervening, and those interventions have been surrounded by controversy. The nature of those controversies has not always been the same, however. Since the mid-nineteenth century, when Francis Galton imagined a science that would assess the extent to which a trait like "genius" was due to nature or due to nurture, science and technology have changed dramatically, and so have the interventions that have been envisioned in light of those developments. A scientist today can search for particular stretches of DNA and assess whether differences in those stretches are associated with differences in a human trait of interest; a genetic counselor today can genetically test an individual (be it an embryo, fetus, newborn, child, or adult) and provide information about what that genetic result means, allowing for interventions that can range from terminating a pregnancy to prescribing chemotherapy. So when one asks a question like, "Why is studying the genetics of intelligence controversial?," it is important to realize up front that the answer will be, "It can be controversial for a variety of different reasons, and those reasons have evolved over time." The purpose of this essay is to provide a survey of the controversies that surround genetic studies of intelligence. With the survey in place, I will then draw out several lessons both for scientists who study the genetics of intelligence as well as for science studies scholars (bioethicists, philosophers, historians, sociologists) who reflect and comment on the controversies surrounding that research. PMID:26413953

  2. Controversial ultrasound findings in mid trimester pregnancy. Evidence based approach.

    PubMed

    Ebrashy, Alaa; Kurjak, Asim; Adra, Abdallah; Aliyu, Labaran Dayyabu; Wataganara, Tuangsit; de Sá, Renato Augusto Moreira; Pooh, Ritsuko; Sen, Cihat; Stanojevic, Milan

    2016-03-01

    Mid trimester fetal anatomy scan is a fundamental part of routine antenatal care. Some U/S soft markers or controversial U/S signs are seen during the scan and create some confusion regarding their relation to fetal chromosomal abnormalities. Example of these signs: echogenic focus in the heart, echogenic bowel, renal pyelectasis, ventriculomegaly, polydactely, club foot, choroid plexus cyst, single umbilical artery. We are presenting an evidence based approach from the literature for management of these controversial U/S signs. PMID:26506099

  3. Controversies in the pathophysiology and management of hyphema.

    PubMed

    Bansal, Svati; Gunasekeran, Dinesh Visva; Ang, Bryan; Lee, Jiaying; Khandelwal, Rekha; Sullivan, Paul; Agrawal, Rupesh

    2016-01-01

    Traumatic hyphemas present dilemmas to physicians. There are numerous controversies pertaining to the optimal approach to traumatic hyphema and no standardized guidelines for its management. We address some of these controversies and present a pragmatic approach. We discuss various medical agents and surgical techniques available for treatment, along with the indications for their use. We address the complications associated with hyphema and how to diagnose and manage them and consider the management of hyphema in special situations such as in children and sickle-cell anemia and in rare clinical syndromes such as recurrent hyphema after placement of anterior chamber intraocular lenses. PMID:26632664

  4. SLI Complex Curvature Friction Stir Weld Risk Reduction Program

    NASA Technical Reports Server (NTRS)

    Hartley, Paula J.; Schneider, Jules; Jones, Chip; Lawless, Kirby; Russell, Carolyn

    2003-01-01

    The Space Launch Initiative Program (SLI) in conjunction with the National Center for Advanced Manufacturing (NCAM) will demonstrate the ability to produce large-scale complex curvature hardware using the self-reacting friction stir welding process. This multi-phased risk reduction program includes friction stir welding process development and manufacture of a 22-ft diameter quarter dome using a conventional tooling approach; it culminates in a 27.5-ft diameter quarter dome demonstration performed on a 5-axis Universal Weld System. The design, fabrication, and installation of the Universal Weld System is made possible through a collaboration between the State of Louisiana, NASA, and the University of New Orleans. The Universal Weld System, manufactured by MTS Systems Corporation, will be installed at the Michoud Assembly Facility in New Orleans, Louisiana, and will be capable of manufacturing domes up to 30 ft in diameter. All welding will be accomplished using the Adaptable Adjustable Pin Tool (AdAPT) weld head and controller manufactured by MTS. Weld parameters will be developed for an aluminum alloy in gauges ranging from 0.320 to 0.400 in. thick. Weld quality will be verified through radiography, mechanical property testing at ambient and LN2 temperatures, and metallurgical analysis. The AdAPT weld head will then be mounted on a 22-ft diameter dome tool, which will be modified to include a welding track and drive system for moving the AdAPT weld head along the weld joint. This tool will then be used to manufacture a 22-ft diameter dome of an aluminum alloy, with 0.320-in. constant thickness joints, consisting of three individual gore panels. Finally, the 27.5-ft diameter quarter dome will be welded on the Universal Weld System. The quarter dome will consist of three individual gore panels with weld lands tapering from 0.320 to 0.360 in. in thickness. With the demonstration of these welds, the ability to manufacture large diameter domes using the friction stir

  5. Friction Stir Spot Welding of 6061 Aluminum-to-Copper

    NASA Astrophysics Data System (ADS)

    Heideman, Robert J.

    Friction stir spot welding (FSSW) between 1.5mm thick 6061 Al on top and 1.5mm thick Cu at bottom was conducted. First, weld parameters and the weld macrostructure that were necessary to form good quality welds, as determined using lap shear weld strength, were identified. Tool rotation speed and tool pin length are key variables that control weld strength. To obtain high quality strong welds, a Cu ring extruded upward from the lower Cu sheet into the upper 6061 Al-sheet, which promoted bonding and interlocking between the sheets, and an Al-rich stir zone between Cu ring and weld keyhole were both necessary. Second, a technique where the tool remained in the sample after FSSW helped determine the material flow that takes place during high quality weld formation and the functions of the welding tool features. The tool threads cause 6061 Al from the upper sheet to move downward into the region near the threads. The tool shoulder causes a counter flow movement of 6061 Al that results in the formation of the Al-rich stir zone and also causes the upward extrusion of the lower Cu sheet. This technique also identified that a Cu-rich material forms on the tool tip, that this material sheds and rebuilds during subsequent welds, and that this material can form large Cu-rich particles that can completely fill the tool threads, impede proper material flow and lead to a low strength, poor quality weld. Third, to further understand welding parameters, weld temperatures, torque, and vertical forces were measured. Temperature data was collected using a tool holder that permitted wireless thermocouple data collection. Through these measurements, rotational plunge weld energy was recognized as important in determining if a quality weld formed, and weld plunge rate was identified as the welding parameter that significantly impacted rotational weld plunge energy. The final phase of research was to improve weld quality consistency. Through repetitive trials with a single tool

  6. Tool for Two Types of Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Carter, Robert

    2006-01-01

    A tool that would be useable in both conventional and self-reacting friction stir welding (FSW) has been proposed. The tool would embody both a prior tooling concept for self-reacting FSW and an auto-adjustable pin-tool (APT) capability developed previously as an augmentation for conventional FSW. Some definitions of terms are prerequisite to a meaningful description of the proposed tool. In conventional FSW, depicted in Figure 1, one uses a tool that includes (1) a rotating shoulder on top (or front) of the workpiece and (2) a rotating pin that protrudes from the shoulder into the depth of the workpiece. The main axial force exerted by the tool on the workpiece is reacted through a ridged backing anvil under (behind) the workpiece. When conventional FSW is augmented with an APT capability, the depth of penetration of the pin into the workpiece is varied in real time by a position- or force-control system that extends or retracts the pin as needed to obtain the desired effect. In self-reacting (also known as self-reacted) friction stir welding (SR-FSW), there are two rotating shoulders: one on top (or front) and one on the bottom (or back) of the workpiece. In this case, a threaded shaft protrudes from the tip of the pin to beyond the back surface of the workpiece. The back shoulder is held axially in place against tension by a nut on the threaded shaft. The main axial force exerted on the workpiece by the tool and front shoulder is reacted through the back shoulder and the threaded shaft, back into the FSW machine head, so that a backing anvil is no longer needed. A key transmits torque between the bottom shoulder and the threaded shaft, so that the bottom shoulder rotates with the shaft. A tool for SRFSW embodying this concept was reported in "Mechanism for Self-Reacted Friction Stir Welding" (MFS-31914), NASA Tech Briefs, Vol. 28, No. 10 (October 2004), page 53. In its outward appearance, the proposed tool (see Figure 2) would fit the above description of an SR

  7. Microstructural and superplastic characteristics of friction stir processed aluminum alloys

    NASA Astrophysics Data System (ADS)

    Charit, Indrajit

    Friction stir processing (FSP) is an adapted version of friction stir welding (FSW), which was invented at The Welding Institute (TWI), 1991. It is a promising solid state processing tool for microstructural modification at localized scale. Dynamic recrystallization occurs during FSP resulting in fine grained microstructure. The main goal of this research was to establish microstructure/superplasticity relationships in FSP aluminum alloys. Different aluminum alloys (5083 Al, 2024 Al, and Al-8.9Zn-2.6Mg-0.09Sc) were friction stir processed for investigating the effect of alloy chemistry on resulting superplasticity. Tool rotation rate and traverse speeds were controlled as the prime FSP parameters to produce different microstructures. In another study, lap joints of 7475 Al plates were also studied to explore the possibility of developing FSW/superplastic forming route. Microstructures were evaluated using optical, scanning and transmission electron microscopy, orientation imaging microscopy and differential scanning calorimetry. Mechanical properties were evaluated using tensile testing. FSP 2024 Al (3.9 mum grain size) exhibited an optimum ductility of 525% at a strain rate of 10-2 s-1 and 430°C. Grain boundary sliding mechanism was found to be the dominant mode of deformation in this alloy. In 5083 Al alloy, it was found that changing the process parameters, grain sizes in the range of 3.5--8.5 mum grain size could be obtained. Material processed with colder processing parameters showed a decrease in ductility due to microstructural instability, and followed solute drag dislocation glide mechanism. On the other hand, materials processed with hotter parameter combinations showed mode of deformation related to grain boundary sliding mechanism. FSP of as-cast Al-Zn-Mg-Sc alloy resulted in ultrafine grains (0.68 mum) with attractive combination of high strain rate and low temperature superplasticity. This also demonstrated that superplastic microstructures could be

  8. Multi-stir bar sorptive extraction for analysis of odor compounds in aqueous samples.

    PubMed

    Ochiai, Nobuo; Sasamoto, Kikuo; Ieda, Teruyo; David, Frank; Sandra, Pat

    2013-11-01

    As reproducible coating of stir bars with more polar phases was found to be very difficult, a supporting grid was used in the development of an ethyleneglycol-modified Silicone (EG Silicone) coated stir bar. This new polar coating showed good performance for the extraction of polar solutes, but long term use also showed degradation of the coating due to friction while stirring. In order to address the lower robustness of the EG Silicone stir bar which has a much softer coating compared to a conventional polydimethylsiloxane (PDMS) stir bar, a novel SBSE procedure termed multi-SBSE ((m)SBSE) was developed. (m)SBSE consists of the robust PDMS stir bar stirring at the bottom of the vial and the EG Silicone stir bar attached on the inner side wall of the vial (a magnetic clip is used for the set-up). After extraction, the two stir bars are placed in a single glass desorption liner and are simultaneously thermally desorbed. The desorbed compounds were analyzed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Compared to conventional SBSE, (m)SBSE provides more uniform enrichment of a wide range of odor compounds in aqueous sample since both stir bars can complement each other, while eliminating the damage of the EG Silicone phase during the extraction. The robustness of the EG Silicone stir bar was dramatically increased and more than 30 extraction and desorption cycles were possible without loss in performance. The recoveries for polar solutes such as 2-acetyl pyrrole (logKow: 0.55), benzyl alcohol (logKow: 1.08), guaiacol (logKow: 1.34), and indole (logKow: 2.05) were increased by a factor of about 2-7. The (m)SBSE-TD-GC-MS method showed good linearity (r(2)>0.9913) and high sensitivity (limit of detection: 0.011-0.071 ng mL(-1)) for the test compounds spiked in water. The feasibility and benefit of the method was demonstrated with analysis of odor compounds in roasted green tea. The normalized areas obtained from (m)SBSE showed the best

  9. Interfacial Reaction during Friction Stir Welding of Al and Cu

    NASA Astrophysics Data System (ADS)

    Genevois, C.; Girard, M.; Huneau, B.; Sauvage, X.; Racineux, G.

    2011-08-01

    Commercially pure copper was joined to a 1050 aluminum alloy by friction stir welding. A specific configuration where the tool pin was fully located in the aluminum plate was chosen. In such a situation, there is no mechanical mixing between the two materials, but frictional heating gives rise to a significant thermally activated interdiffusion at the copper/aluminum interface. This gives rise to the formation of defect-free joints where the bonding is achieved by a very thin intermetallic layer at the Cu/Al interface. Nanoscaled grains within this bonding layer were characterized using transmission electron microscopy (TEM). Two phases were identified, namely, Al2Cu and Al4Cu9 phases. The nucleation and growth of these two phases are discussed and compared to the standard reactive interdiffusion reactions between Cu and Al.

  10. Prolegomena to the Study of Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C., Jr.

    2010-01-01

    The literature contains many approaches toward modeling of the friction stir welding (FSW) process with varying treatments of the weld metal properties. It is worthwhile to consider certain fundamental features of the process before attempting to interpret FSW phenomena: Because of the unique character of metal deformation (as opposed to, say, viscous deformation) a velocity "discontinuity" or shear surface occurs in FSW and determines much of the character of the welding mechanism. A shear surface may not always produce a sound bond. Balancing mechanical power input against conduction and convection heat losses yields a relation, a "temperature index", between spindle speed and travel speed to maintain constant weld temperature. But many process features are only weakly dependent upon temperature. Thus, unlike modeling of metal forming processes, it may be that modeling the FSW process independently of the material conditions has some merit.

  11. Lateral position detection and control for friction stir systems

    DOEpatents

    Fleming, Paul; Lammlein, David H.; Cook, George E.; Wilkes, Don Mitchell; Strauss, Alvin M.; Delapp, David R.; Hartman, Daniel A.

    2011-11-08

    Friction stir methods are disclosed for processing at least one workpiece using a rotary tool with rotating member for contacting and processing the workpiece. The methods include oscillating the rotary tool laterally with respect to a selected propagation path for the rotating member with respect to the workpiece to define an oscillation path for the rotating member. The methods further include obtaining force signals or parameters related to the force experienced by the rotary tool at least while the rotating member is disposed at the extremes of the oscillation. The force signals or parameters associated with the extremes can then be analyzed to determine a lateral position of the selected path with respect to a target path and a lateral offset value can be determined based on the lateral position. The lateral distance between the selected path and the target path can be decreased based on the lateral offset value.

  12. Pin Tool Geometry Effects in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Querin, J. A.; Rubisoff, H. A.; Schneider, J. A.

    2009-01-01

    In friction stir welding (FSW) there is significant evidence that material can take one of two different flow paths when being displaced from its original position in front of the pin tool to its final position in the wake of the weld. The geometry of the pin tool, along with the process parameters, plays an important role in dictating the path that the material takes. Each flow path will impart a different thermomechanical history on the material, consequently altering the material microstructure and subsequent weld properties. The intention of this research is to isolate the effect that different pin tool attributes have on the flow paths imparted on the FSWed material. Based on published weld tool geometries, a variety of weld tools were fabricated and used to join AA2219. Results from the tensile properties and microstructural characterization will be presented.

  13. Metal cutting analogy for establishing Friction Stir Welding process parameters

    NASA Astrophysics Data System (ADS)

    Stafford, Sylvester Allen

    A friction stir weld (FSW) is a solid state joining operation whose processing parameters are currently determined by lengthy trial and error methods. To implement FSWing rapidly in various applications will require an approach for predicting process parameters based on the physics of the process. Based on hot working conditions for metals, a kinematic model has been proposed for calculating the shear strain and shear strain rates during the FSW process, validation of the proposed model with direct measuring is difficult however. Since the shear strain and shear strain rates predicted for the FSW process, are similar to those predicted in metal cutting, validation of the FSW algorithms with microstructural studies of metal chips may be possible leading to the ability to predict FSW processing parameters.

  14. Friction Stir Welding of ODS and RAFM Steels

    NASA Astrophysics Data System (ADS)

    Yu, Zhenzhen; Feng, Zhili; Hoelzer, David; Tan, Lizhen; Sokolov, Mikhail A.

    2015-09-01

    Advanced structural materials such as oxide dispersion strengthened steels and reduced-activation ferritic/martensitic steels are desired in fusion reactors as primary candidate materials for first wall and blanket structures, due to their excellent radiation and high-temperature creep resistance. However, their poor fusion weldability has been the major technical challenge limiting practical applications. For this reason, solid-state friction stir welding (FSW) has been considered for such applications. In this work, the effect of FSW parameters on joining similar and dissimilar advanced structural steels was investigated. Scanning electron microscopy and electron backscatter diffraction methods were used to reveal the effects of FSW on grain size, micro-texture distribution, and phase stability. Hardness mapping was performed to evaluate mechanical properties. Post weld heat treatment was also performed to tailor the microstructure in the welds in order to match the weld zone mechanical properties to the base material.

  15. Material Flow during Friction Stir Welding of HSLA 65 Steel

    NASA Astrophysics Data System (ADS)

    Young, John; Field, David; Nelson, Tracy

    2013-07-01

    Material flow during friction stir welding of HSLA-65 steel was investigated by crystallographic texture analysis. During the welding process, the steel deforms primarily by local shear deformation in the austenite phase and then transforms upon cooling. Texture data from three weld specimens were compared to theoretical textures calculated using ideal Euler angles for shear in face centered cubic (FCC) structures transformed by the Kurdjumov-Sacks (KS) relationship. These theoretical textures show similarities to the experimental textures. Texture data from the weld specimens revealed a rotation of the shear direction corresponding to the tangent of the weld tool on both the area directly under the weld tool shoulder and weld cross sections. In addition, texture data showed that while the shear plane of the area under the weld tool shoulder remained constant, the shear plane of the weld cross sections is influenced by the weld tool pin.

  16. A cubic autocatalytic reaction in a continuous stirred tank reactor

    SciTech Connect

    Yakubu, Aisha Aliyu; Yatim, Yazariah Mohd

    2015-10-22

    In the present study, the dynamics of the cubic autocatalytic reaction model in a continuous stirred tank reactor with linear autocatalyst decay is studied. This model describes the behavior of two chemicals (reactant and autocatalyst) flowing into the tank reactor. The behavior of the model is studied analytically and numerically. The steady state solutions are obtained for two cases, i.e. with the presence of an autocatalyst and its absence in the inflow. In the case with an autocatalyst, the model has a stable steady state. While in the case without an autocatalyst, the model exhibits three steady states, where one of the steady state is stable, the second is a saddle point while the last is spiral node. The last steady state losses stability through Hopf bifurcation and the location is determined. The physical interpretations of the results are also presented.

  17. Friction Stir Welding of ODS and RAFM Steels

    DOE PAGESBeta

    Yu, Zhenzhen; Feng, Zhili; Hoelzer, David; Tan, Lizhen; Sokolov, Mikhail A.

    2015-09-14

    Advanced structural materials such as oxide dispersion strengthened steels and reduced-activation ferritic/martensitic steels are desired in fusion reactors as primary candidate materials for first wall and blanket structures, due to their excellent radiation and high-temperature creep resistance. However, their poor fusion weldability has been the major technical challenge limiting practical applications. For this reason, solid-state friction stir welding (FSW) has been considered for such applications. In this paper, the effect of FSW parameters on joining similar and dissimilar advanced structural steels was investigated. Scanning electron microscopy and electron backscatter diffraction methods were used to reveal the effects of FSW onmore » grain size, micro-texture distribution, and phase stability. Hardness mapping was performed to evaluate mechanical properties. Finally, post weld heat treatment was also performed to tailor the microstructure in the welds in order to match the weld zone mechanical properties to the base material.« less

  18. FRICTION-STIR-LAP-WELDS OF AA6111 ALUMINUM ALLOY

    SciTech Connect

    Yadava, Manasij; Mishra, Rajiv S.; Chen, Y. L.; Gayden, X.; Grant, Glenn J.

    2007-01-09

    Lap joints of 1 mm thick AA6111 aluminum sheets were made by friction stir welding, using robotic and conventional machines. Welds were made for advancing as well as retreating side loading. Thinning in welds was quantified. Lap shear test of welds was conducted in as-welded and paint-baked conditions. Conventional machine welds showed less thinning and better strength than robotic machine welds. Process forces in conventional machine welding were higher. Paint bake treatment improved the weld strength; but the improvement varied with process parameters. Advancing side loaded welds achieved higher strength than the retreating side loaded welds. Fracture location was found to occur on the loaded side of the weld and along the thinning defect.

  19. Friction Stir Welding of ODS and RAFM Steels

    SciTech Connect

    Yu, Zhenzhen; Feng, Zhili; Hoelzer, David; Tan, Lizhen; Sokolov, Mikhail A.

    2015-09-14

    Advanced structural materials such as oxide dispersion strengthened steels and reduced-activation ferritic/martensitic steels are desired in fusion reactors as primary candidate materials for first wall and blanket structures, due to their excellent radiation and high-temperature creep resistance. However, their poor fusion weldability has been the major technical challenge limiting practical applications. For this reason, solid-state friction stir welding (FSW) has been considered for such applications. In this paper, the effect of FSW parameters on joining similar and dissimilar advanced structural steels was investigated. Scanning electron microscopy and electron backscatter diffraction methods were used to reveal the effects of FSW on grain size, micro-texture distribution, and phase stability. Hardness mapping was performed to evaluate mechanical properties. Finally, post weld heat treatment was also performed to tailor the microstructure in the welds in order to match the weld zone mechanical properties to the base material.

  20. Tidal stirring and phytoplankton bloom dynamics in an estuary

    USGS Publications Warehouse

    Cloern, J.E.

    1991-01-01

    In South San Francisco Bay, estuarine phytoplankton biomass fluctuates at the time scale of days to weeks; much of this variability is associated with fluctuations in tidal energy. During the spring seasons of every year from 1980-1990, episodic blooms occurred in which phytoplankton biomass rose from a baseline of 2-4mg chlorophyll a m-3, peaked at 20-40 chlorophyll a m-3, then returned to baseline values, all within several weeks. Each episode of biomass increase occurred during neap tides, and each bloom decline coincided with spring tides. This suggests that daily variations in the rate of vertical mixing by tidal stirring might control phytoplankton bloom dynamics in some estuaries. Simulation experiments with a numerical model of phytoplankton population dynamics support this hypothesis. -from Author

  1. Laser-Assisted Stir Welding of 25-mm-Thick HSLA-65 Plate

    NASA Astrophysics Data System (ADS)

    Williamson, Keith M.

    2002-12-01

    Laser-assisted stir welding is a hybrid process that combines energy from a laser with functional heating and mechanical energy to join materials in the solid state. The technology is an adaptation of friction stir welding which is particularly suited for joining thick plates. Aluminum plates up to 75 mm thick have been successfully joined using friction stir welding. Since joining occurs in the solid state, stir technology offers the capability for fabricating full penetration joints in thick plates with better mechanical properties and less weld distortion than is possible by fusion processes. Currently friction stir welding is being used in several industries to improve productivity, reduce weight, and increase the strength of welded structures. Examples include: (a) the aircraft/aerospace industry where stir technology is currently being used to fabricate the space shuttle's external tank as well as components of the Delta family of rockets; (b) the shipping industry where container manufacturers are using stir technology to produce lighter containers with more payload capacity; and (c) the oil industry where offshore platform manufactures are using automated stir welding plants to fabricate large panels and structures up to 16 meters long with widths as required. In all these cases, stir technology has been restricted to aluminum alloys; however, stainless and HSLA 65 steels have been recently stir welded with friction as the primary heat source. One of the difficulties in adapting stir welding to steel is tool wear aggravated by the high tool rubbing velocities needed to provide frictional heat input into the material. Early work showed that the tool shoulder reached temperatures above 1000 C and the weld seam behind the tool stayed within this temperature range for up to 25 mm behind the tool. Cross sections of stir welded samples showed that the heat-affected zone is relatively wide and follows the profile of the tool shoulder. Besides minimizing the tool

  2. Controlled polymerization of acrylonitrile proceeded along with the Belousov-Zhabotinsky oscillator by changing its stirring conditions

    NASA Astrophysics Data System (ADS)

    Furue, Yuuka; Okano, Kunihiko; Banno, Taisuke; Asakura, Kouichi

    2016-02-01

    Chemical oscillations of the manganese-ion catalyzed Belousov-Zhabotinsky (BZ) reaction system were found to be controlled by changing its stirring conditions. The oscillation stopped at a high stirring rate, while it reappeared immediately by reducing the stirring rate. It is known in the BZ reaction system, that the radical polymerization takes place along with the oscillation when acrylic monomers are added. By the addition of acrylonitrile to the system stirred at a high stirring rate, the oscillation as well as the polymerization of acrylonitrile stopped. The radical polymerization of acrylonitrile by the BZ oscillator is thus found to be made controllable by changing the mixing conditions.

  3. Reading "Daddy's Roommate": Preservice Teachers Respond to a Controversial Text.

    ERIC Educational Resources Information Center

    Williams, Shawyn

    2002-01-01

    Explores the responses of the author's 31 pre-service teachers to a controversial picture book. Begins by searching for a short text geared to elementary age children and suited for read-alouds. Notes that she believes that the majority of pre-service teachers at this stage in the program are still very impressionable and must be given multiple…

  4. Before We Were Us, We Were Them: Curating Controversy

    ERIC Educational Resources Information Center

    Watson, Keri

    2014-01-01

    Prompted by the passage of Alabama House Bill 56, I organized the museum studies course I taught for Auburn University at Montgomery in the 2013 spring semester around an exhibition on immigration. The course offered the opportunity to engage students, faculty, and the community in discussion of an important, timely, and controversial topic.…

  5. Education Dept. to End Controversial Study of Upward Bound

    ERIC Educational Resources Information Center

    Field, Kelly

    2008-01-01

    Yielding to pressure from Congress and grant recipients, the U.S. Education Department has agreed to abandon a controversial evaluation of the Upward Bound (UB) college-preparation program. The study, which began last year, was designed to measure whether Upward Bound would have a bigger impact on college-going rates if it were refocused on…

  6. Taking One's Principles Seriously: A Teacher Confronts Controversy

    ERIC Educational Resources Information Center

    Hare, William

    2010-01-01

    A teacher faces hostility from certain colleagues who view his decision to attend a controversial lecture as tantamount to the repudiation of the principle of inclusive education and the rights of students with disabilities. The teacher sees the proposed boycott of the lecture as a form of censorship threatening freedom of inquiry and critical…

  7. The Reverse Discrimination Controversy. A Moral and Legal Analysis.

    ERIC Educational Resources Information Center

    Fullinwider, Robert K.

    This book has two principal aims: to clarify the topical and controversial issue of reverse discrimination and to reach some conclusions about the rights and wrongs involved in this issue. Focusing mainly on preferential hiring, the book explicitly and extensively addresses the law and the institutional context of the issues. Examination of the…

  8. The Vocational-Liberal Arts Controversy: Looking Backwards.

    ERIC Educational Resources Information Center

    Miles, Sue L.

    The liberal arts-vocational education controversy is examined in this article through a series of fictitious letters based on historical facts that present the thoughts of key educational personalities regarding the community college's role in providing vocational education and liberal arts education. Part I, which takes the form of a letter and…

  9. Use of Dramatic Enquiry to Explore Controversies in Science

    ERIC Educational Resources Information Center

    Phillipson, Neil; Poad, Gordon

    2010-01-01

    With the increasing prominence of "How science works" in science courses in England and the imperative of equipping students to engage with the controversies thrown up by the advance of science, science departments need new teaching strategies. Here we describe the application of "Dramatic Enquiry" to GCSE science. The project, developed by…

  10. Teaching About the Creation/Evolution Controversy. Fastback 134.

    ERIC Educational Resources Information Center

    Bergman, Jerry

    The booklet discusses questions related to teaching engendered by the creation/evolution controversy, presents current positions of educators and textbooks, and recommends a two-model teaching approach. It is divided into six chapters. Chapter I defines and summarizes evolution and creationism as different belief structures, and outlines various…

  11. Socio-Scientific Controversies and Students' Conceptions about Scientists

    ERIC Educational Resources Information Center

    Reis, Pedro; Galvao, Cecilia

    2004-01-01

    This article discusses the results of a mainly qualitative study into possible impacts of recent controversial socio-scientific issues on a group of Portuguese secondary school students regarding their conceptions about scientists. The 86 participants: (1) answered a questionnaire with open-ended questions; and (2) wrote a science fiction story…

  12. Scientific Controversies in Teaching Science: The Case of Volta.

    ERIC Educational Resources Information Center

    Kipnis, Nahum

    2001-01-01

    Discusses a way of introducing a scientific controversy that emphasizes objective aspects of such issues as multiple theoretical interpretation of phenomena, choosing a theory, and insistence on the chosen theory. The goal is to give students a better insight into the workings of science and provide guidelines for building theories in their own…

  13. Controversial Therapies for Young Children with Developmental Disabilities.

    ERIC Educational Resources Information Center

    Nickel, Robert E.

    1996-01-01

    This article examines reasons parents may choose a controversial alternative treatment for a child with developmental disabilities and reviews a few specific treatments--vitamin B-6 and magnesium, auditory integration training, megavitamins and minerals, Piracetam, intravenous immunoglobulin, and melatonin. Recommendations on talking with families…

  14. The Ecology Controversy: Opposing Viewpoints. Critical Issues Series.

    ERIC Educational Resources Information Center

    McCuen, Gary E., Ed.; Bender, David L., Ed.

    Ecological problems are explored in this book of sixteen student readings and exercises aimed at developing and applying critical thinking skills. The readings, mostly extracts from books and periodicals, are introduced by the editor and accompanied by questions. Chapter I, The Population Controversy, includes selections from Paul Ehrlich's The…

  15. Improving the Quality of Science Classroom Discourse on Controversial Issues.

    ERIC Educational Resources Information Center

    Geddis, Arthur N.

    1991-01-01

    Illustrates how the sophistication of students' discussion on controversial issues can be increased by explicit attention to (1) the defensibility of more than one position, and (2) the relationship between protagonist's interests and the positions adopted. Presents a case study of a teacher using this scheme as he reflects on and modifies his…

  16. Disaster, Controversy--Are You Prepared for the Worst?

    ERIC Educational Resources Information Center

    Heller, Robert W.; And Others

    1991-01-01

    Provides demographic profiles from "Executive Educator's" fourth annual survey of U.S. school executives. Regarding disaster preparedness, only a small percentage of all districts in earthquake-prone areas have earthquake and fire action plans. Concerning controversial issues, teaching about substance abuse, child abuse, and teen suicide meets…

  17. Piaget, IQ, and the Nature-Nurture Controversy

    ERIC Educational Resources Information Center

    Furth, H. G.

    1973-01-01

    Four basic assumptions of IQ tests - age constancy, scholastic validity, standard environment and performance suggiciency are alien to Piaget's theory. Heredity cannot be statistically separated from environment; therefore, Piagetian theory would suggest the nature-nurture controversy is devoid of meaning. (ST)

  18. The Animal Experimentation Controversy: Ethical Views of Prospective Teachers

    ERIC Educational Resources Information Center

    de Villiers, Rian

    2012-01-01

    Vivisection (live animal experimentation) is a controversial issue for many people. The purpose of this case study is to examine the attitudes of prospective teachers toward vivisection in education and research, to determine if gender has an influence on these attitudes, and to discuss the implications of these attitudes with regard to teaching…

  19. Controversial Issues in Orientation and Mobility: Then and Now.

    ERIC Educational Resources Information Center

    Hill, Everett W.; Jacobson, William H.

    1985-01-01

    A review of issues in orientation and mobility (0M) considers controversies in: (1) OM systems (use of short cane vs. long cane, dog guide vs. cane, electronic travel aids); (2) OM personnel preparation (such as bachelor's vs. master's level training); and (3) direct services (such as one-to-one vs. group OM lessons). (CL)

  20. The Legitimizing Function of Judicial Rhetoric in the Eugenics Controversy.

    ERIC Educational Resources Information Center

    Hasian, Marouf, Jr.; Croasmun, Earl

    1992-01-01

    Investigates the possibility that judicial policymaking is responsive to the situational exigencies created in part through public discourse. Investigates the elite and public perspectives regarding the eugenics controversy in the 1920s to explore the emergent relationship between the public and technical spheres of argument. (SR)

  1. The Continuing Controversy over Grades. TM Report 51.

    ERIC Educational Resources Information Center

    Warren, Jonathan R.

    Although grades have been criticized for lack of reliability, end-of course grades and grade-point averages are reliable enough for most uses. The charge of unreliability applies only to grades on themes, tests, or other individual pieces of student work. On the other side of the controversy, grades have been said to be essential to the learning…

  2. The Seal Killing Controversy: What Are the Facts?

    ERIC Educational Resources Information Center

    Scheffer, Victor B.

    1973-01-01

    Discusses the seal controversy using the harp and Alaska fur seals to illustrate the two distinct issues, i.e., conservation (the effect of killing upon the animal population); and two, morality (the effect of killing upon the human spirit). Factual information combines with personal philosophy. (LK)

  3. Teaching Darwin: Contemporary Social Studies through Controversial Issues

    ERIC Educational Resources Information Center

    Swanson, Helge

    2010-01-01

    I explore Darwin and his Theory of Natural Selection from a Social Science perspective and a social studies approach of inquiry into contemporary issues. This approach augments the more common natural science focus on the mechanics of natural selection and evolution in favor of a focus on social issues, controversy, and dialog necessary to support…

  4. Cagney and Lacey: Negotiating the Controversial in Popular Television.

    ERIC Educational Resources Information Center

    Hillier, Jim

    This paper discusses some of the ways in which the commitment of the television series Cagney and Lacey to the examination of often controversial social issues from liberal or progressive standpoints--especially issues associated with the women's movement--is worked through in narrative practice. The origins and development of the series are…

  5. Creationism in the Classroom: A Controversy with Serious Consequences

    ERIC Educational Resources Information Center

    Baker, Sylvia

    2010-01-01

    The resignation of the Revd Professor Michael Reiss from his position as Director of Education at the Royal Society over the issue of the teaching of creationism in school science classes provides the background to this article. The immediate controversy is described and considered in relation to its wider context and to the serious questions that…

  6. Aptitude Testing Controversy: Beliefs, Not Values, Are on Trial.

    ERIC Educational Resources Information Center

    Gonzalez-Tamayo, Eulogio

    This paper analyzes research findings about the role of values and beliefs in aptitude testing. Indications are found that the ongoing controversy over the lack of ethnic, racial, and sex fairness in aptitude testing is rooted in the tests themselves. Test designers, it is argued, are influenced by their socioeconomic position (they are usually…

  7. Diversity in Information Technology Education: Issues and Controversies

    ERIC Educational Resources Information Center

    Trajkovski, Goran, Ed.

    2006-01-01

    "Diversity in Information Technology Education: Issues and Controversies" sheds light on the status of diversity in the field of IT education. It identifies a wide range of problems that educators face on a daily basis, and gives practical, applicable solutions, mainly by showcasing successful and replicable examples. The chapters in "Diversity in…

  8. Fair Use or Exploitation?: The Google Book Search Controversy

    ERIC Educational Resources Information Center

    Baksik, Corinna

    2006-01-01

    The Google Book Search Library Project, in which millions of books from libraries will be scanned and made searchable on the Web, has led to controversy and legal action. Publishers are suing Google for copyright infringement, while Google claims their use falls under the fair use privilege of the "Copyright Act". An overview of the library…

  9. "We Make It Controversial": Elementary Preservice Teachers' Beliefs about Race

    ERIC Educational Resources Information Center

    Buchanan, Lisa Brown

    2015-01-01

    The impetus for this study began during an elementary teacher education course meeting, where preservice teachers discussed whether or not it was appropriate to discuss controversial topics--including race--with young children. Preservice teachers disclosed their "uncomfortableness" with race at large, and emphasized that discussions…

  10. Teaching Controversial Materials: Teaching about the Nuclear Issue.

    ERIC Educational Resources Information Center

    Wall, Joseph

    1986-01-01

    Describes difficulties encountered in presenting a college course on nuclear weapons and disarmament. Maintains that such courses must strive for a fuller historical account of the arms race, in addition to stressing the humanistic and ethical questions involved. Warns that controversy will arise and concludes that even blind anger is preferable…

  11. Media Coverage in a Community Controversy: Initial and Subsequent Effects.

    ERIC Educational Resources Information Center

    Watt, James H., Jr.; van den Berg, Sjef

    The choice of time lag between variables can affect surveys of public opinion and audience behavior, according to this report on the effects of media coverage of the controversy surrounding the operation of the supersonic transport Concorde out of Dulles Airport, near Washington, D.C. Five theories of media effects are outlined, including direct…

  12. Race and Genetics: Controversies in Biomedical, Behavioral, and Forensic Sciences

    ERIC Educational Resources Information Center

    Ossorio, Pilar; Duster, Troy

    2005-01-01

    Among biomedical scientists, there is a great deal of controversy over the nature of race, the relevance of racial categories for research, and the proper methods of using racial variables. This article argues that researchers and scholars should avoid a binary-type argument, in which the question is whether to use race always or never.…

  13. Teaching Controversy by Seminar: An Example in Quaternary Geomorphology.

    ERIC Educational Resources Information Center

    Harwood, Doug

    1987-01-01

    Describes how seminar work can be structured to help students develop skills of critical thinking and expression when discussing controversial issues in their chosen subject. Particular emphasis is given to methods of organizing instructional materials and appropriate roles for seminar leaders. The debate surrounding the existence of a prehistoric…

  14. Design Piracy: Student Perceptions of a Constructive Controversy Activity

    ERIC Educational Resources Information Center

    Marcketti, Sara B.

    2007-01-01

    Optimal learning occurs when students are interested in the subject matter, are motivated with challenging and quality learning opportunities, and when immersed in atmospheres that make learning enjoyable. One technique to promote optimal learning is through the use of constructive controversies. The purpose of this study was to provide an example…

  15. Childhood Psychological Disorders: Current Controversies. Making Sense of Psychology

    ERIC Educational Resources Information Center

    Bursztyn, Alberto M., Ed.

    2011-01-01

    This accessible, informative book will help teachers, parents, and practitioners make sense of current issues and controversies surrounding childhood disabilities. Almost 12 percent of children in American schools have been identified as disabled in ways that interfere with their capacity to learn. Yet parents of children with disabilities often…

  16. Should We Teach Homosexuality as a Controversial Issue?

    ERIC Educational Resources Information Center

    Hand, Michael

    2007-01-01

    Philosophers of education disagree on how the question of the moral status of homosexual acts should be tackled in the classroom. Some argue that the question should be taught as a controversial issue, that we should present rival moral positions as even-handedly as possible; others maintain that we should actively promote the view that homosexual…

  17. Hate Speech: The History of an American Controversy.

    ERIC Educational Resources Information Center

    Walker, Samuel

    Noting that no other country in the world offers protection to offensive speech, this book provides a comprehensive account of the history of the hate speech controversy in the United States. The book examines the issue, from the conflicts over the Ku Klux Klan in the 1920s and American Nazi groups in the 1930s, to the famous Skokie, Illinois…

  18. Know Nukes: A Model for Teaching Controversial Issues.

    ERIC Educational Resources Information Center

    Thomashow, Mitchell

    1984-01-01

    Summarizes a nuclear power workshop that presented techniques useful in controversial issues education. An introductory exercise and an overview of propagandistic techniques (listed in "The Propaganda Game") related to self-deception, language, irrelevance, exploitation, form, and maneuver are included. Outline of workshop presentation is also…

  19. 16 CFR 2.3 - Policy as to private controversies.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Policy as to private controversies. 2.3 Section 2.3 Commercial Practices FEDERAL TRADE COMMISSION ORGANIZATION, PROCEDURES AND RULES OF PRACTICE NONADJUDICATIVE PROCEDURES Inquiries; Investigations; Compulsory Processes § 2.3 Policy as to...

  20. The Evolution/Creation Science Controversy: Educate Rather Than Debate.

    ERIC Educational Resources Information Center

    Jane, Beverley

    This paper is linked to the theme History and Philosophy of Science. The Evolution and creation science controversy is now in the general public's arena and poses a challenge for school science. The paper begins by briefly describing the current situation concerning this issue in Australia and the United States of America. In the subject Biology,…

  1. Ethical Perspectives on the Current Controversy Regarding Openness in Adoption.

    ERIC Educational Resources Information Center

    Tavis, Timothy M.

    This paper outlines current changes in American adoption practice and the controversies surrounding these changes. It includes a discussion of the role that neo-Kantian and utilitarian perspectives have played in American adoption policy and practice, and offers an alternative, the communitarian perspective, described by Sandel (1984). Adoption…

  2. 42 CFR 405.1839 - Amount in controversy.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Aggregation of claims. For purposes of satisfying the applicable amount in controversy requirement for a... the same cost reporting period. Aggregation of claims from more than one cost reporting period to meet... reporting periods under appeal would increase, in the aggregate, by at least $50,000. (2) Aggregation...

  3. Liebig-Wohler Controversy and the Concept of Isomerism

    ERIC Educational Resources Information Center

    Esteban, Soledad

    2008-01-01

    Very often controversies contribute to the development of science. An example is the conflict between Liebig and Wohler on the occasion of their analyses of fulminates and cyanates, which showed that compounds with different properties could have the same composition. Their results, together with other similar evidences, led Berzelius to recognize…

  4. Millennia of Discord: The Controversial Educational Program of Isocrates

    ERIC Educational Resources Information Center

    Marsh, Charles

    2010-01-01

    Five years ago in "Theory and Research in Education", James R. Muir fired a new salvo in the debate regarding the merits of Isocrates' educational program, a controversy that has endured for more than two millennia. Was the Isocratean program misguided and lowbrow, as in the estimations of Plato and Aristotle--or was it the most successful program…

  5. "Smoky Night" and "Crack": Controversial Subjects in Current Children's Stories.

    ERIC Educational Resources Information Center

    Koehnecke, Dianne

    2001-01-01

    Discusses two children's picture books: "Smoky Night" and "The House that Crack Built." Notes that the books deal with the Los Angeles riots and the use and distribution of crack cocaine. Concludes that each book treats important issues with sensitivity and honesty and is engaging, even when dealing with controversial topics in a didactic…

  6. The Continuum and Current Controversies in the USA.

    ERIC Educational Resources Information Center

    Taylor, Steven J.

    2001-01-01

    This article reviews policy developments in deinstitutionalization and community inclusion in North America, specifically the United States. It begins with a critique of the continuum concept and the associated principle of the least restrictive environment. Past and current controversies surrounding deinstitutionalization are then examined.…

  7. Relational Frame Theory: An Overview of the Controversy

    ERIC Educational Resources Information Center

    Gross, Amy C.; Fox, Eric J.

    2009-01-01

    Although Skinner's "Verbal Behavior" (1957) was published over 50 years ago, behavior-analytic research on human language and cognition has been slow to develop. In recent years, a new behavioral approach to language known as relational frame theory (RFT) has generated considerable attention, research, and debate. The controversy surrounding RFT…

  8. Is Race Really Controversial in the University Classroom?

    ERIC Educational Resources Information Center

    Philion, Stephen

    2009-01-01

    Today, even though "social justice" programs exist as a virtual growth industry on US campuses and many universities have incorporated classes on race and racism into their curricula, everyone continues to be faced with the perception that race is a "controversial" topic that has to be broached with care due to its "sensitive nature". This is even…

  9. Supreme Court Actions Push a Wrenching Controversy Straight at You.

    ERIC Educational Resources Information Center

    Harrington-Lueker, Donna

    1989-01-01

    The Supreme Court's past and expected future rulings on abortion cases will add controversy and costs to schools. Estimates the costs of teenage pregnancy; reviews the legal history of abortion; and offers guidelines on how schools can help reduce teenage pregnancy. (MLF)

  10. EVOLUTIONARY TRACKS OF TIDALLY STIRRED DISKY DWARF GALAXIES

    SciTech Connect

    Lokas, Ewa L.; Kazantzidis, Stelios; Mayer, Lucio E-mail: stelios@mps.ohio-state.edu

    2011-09-20

    Using collisionless N-body simulations, we investigate the tidal evolution of late-type, rotationally supported dwarfs inside Milky Way sized host galaxies. Our study focuses on a wide variety of dwarf orbital configurations and initial structures. During the evolution, the disky dwarfs undergo strong mass loss, the stellar disks are transformed into spheroids, and rotation is replaced by random motions of the stars. Thus, the late-type progenitors are transformed into early-type dwarfs as envisioned by the tidal stirring model for the formation of dwarf spheroidal (dSph) galaxies in the Local Group. We determine the photometric properties of the dwarfs, including the total visual magnitude, the half-light radius, and the central surface brightness as they would be measured by an observer near the galactic center. Special emphasis is also placed on studying their kinematics and shapes. We demonstrate that the measured values are biased by a number of observational effects including the increasing angle of the observation cone near the orbital pericenter, the fact that away from the pericenter the tidal tails are typically oriented along the line of sight, and the fact that for most of the evolution the stellar components of the dwarfs are triaxial ellipsoids whose major axis tumbles with respect to the line of sight. Finally, we compare the measured properties of the simulated dwarfs to those of dwarf galaxies in the Local Group. The evolutionary tracks of the dwarfs in different parameter planes and the correlations between their different properties, especially the total magnitude and the surface brightness, strongly suggest that present-day dSph galaxies may have indeed formed from late-type progenitors as proposed by the tidal stirring scenario.

  11. Ethylene oxidation in a well-stirred reactor

    SciTech Connect

    Marinov, N.M.; Malte, P.C.

    1994-10-01

    The detailed ethylene oxidation data set of Thornton, obtained for a well-stirred reactor operated fuel-lean at atmospheric pressure and for temperatures of 1003K to 1253K, is used as a basis for the comparison of chemical kinetic mechanisms reported in the literature and for the development of a new ethylene oxidation mechanism. The mechanisms examined are those of Westbrook and Pitz and Dagaut et al. These mechanisms indicated that unusually large rates for the vinyl decomposition reaction are required to obtain agreement with the Thornton data set. A new ethylene oxidation mechanism is developed in order to overcome some of the drawbacks of the previous mechanisms. The new mechanism closely simulates the overall rate of loss of ethylene, and the concentation of CO, CO{sub 2}, H{sub 2}, CH{sub 2}O, C{sub 2}H{sub 2}, CH{sub 3}OH, CH{sub 4}, and C{sub 2}H{sub 6} measured for the stirred reactor. Predictions by this mechanism are dependent on a new high temperature vinyl oxidation route, C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}CHO + O with a k{sub C2H3+O2=CH2CHO+O}/k{sub C2H3+O2=CH2O+HCO} branching ratio of 1.20 at 1053K to 2.05 at 1253K. The branching ratio values were dependent upon the extent of fall-off for the C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}O + HCO reaction.

  12. Versatile Friction Stir Welding/Friction Plug Welding System

    NASA Technical Reports Server (NTRS)

    Carter, Robert

    2006-01-01

    A proposed system of tooling, machinery, and control equipment would be capable of performing any of several friction stir welding (FSW) and friction plug welding (FPW) operations. These operations would include the following: Basic FSW; FSW with automated manipulation of the length of the pin tool in real time [the so-called auto-adjustable pin-tool (APT) capability]; Self-reacting FSW (SRFSW); SR-FSW with APT capability and/or real-time adjustment of the distance between the front and back shoulders; and Friction plug welding (FPW) [more specifically, friction push plug welding] or friction pull plug welding (FPPW) to close out the keyhole of, or to repair, an FSW or SR-FSW weld. Prior FSW and FPW systems have been capable of performing one or two of these operations, but none has thus far been capable of performing all of them. The proposed system would include a common tool that would have APT capability for both basic FSW and SR-FSW. Such a tool was described in Tool for Two Types of Friction Stir Welding (MFS- 31647-1), NASA Tech Briefs, Vol. 30, No. 10 (October 2006), page 70. Going beyond what was reported in the cited previous article, the common tool could be used in conjunction with a plug welding head to perform FPW or FPPW. Alternatively, the plug welding head could be integrated, along with the common tool, into a FSW head that would be capable of all of the aforementioned FSW and FPW operations. Any FSW or FPW operation could be performed under any combination of position and/or force control.

  13. Auto-adjustable pin tool for friction stir welding

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor); Oelgoetz, Peter A. (Inventor)

    1999-01-01

    An auto-adjusting pin tool for friction stir welding is presented wherein the pin tool automatically adjusts for welding materials of varying thicknesses, and the pin can be incrementally withdrawn from the workpieces thus eliminating any crater or keyhole in the weld. The inventive apparatus is comprised of a welding head housing a motor connected to a controller instrument package and an arbor supported by bearings. The arbor forms an interior cylinder and is encircled by a stationary slip ring though which are ported hydraulic passageways into the interior cylinder of the arbor such that a piston housed therein may be moved axially. Coupled to the piston is a pin tool which is treaded on its lower end and which is moveably seated in, and extending through, a shoulder housing having concave lower face. When welding, the rotating treaded end of the pin enters and stirs the workpieces while the lower face of the shoulder housing compacts the workpieces. As the welding head traverses the shoulder housing the controller senses any rising pressure on the lower face of the shoulder housing and withdraws the arbor to keep the pressure constant. At the same time, the piston moves towards the workpieces thus extending the pin further from the shoulder. This keeps the pin at a proper depth in the workpieces regardless of their thicknesses. As the weld terminates this same operation can be used to incrementally withdraw the pin during the final part of the traverse, thus eliminating any keyhole or crater that would otherwise be created.

  14. Modifying AM60B Magnesium Alloy Die Cast Surfaces by Friction Stir Processing

    SciTech Connect

    Santella, Michael L; Feng, Zhili; Degen, Cassandra; Pan, Dr. Tsung-Yu

    2006-01-01

    These experiments were done to evaluate the feasibility of locally modifying the surface properties of magnesium alloys with friction-stir processing. The magnesium alloy used for the study was high-pressure die-cast AM60B, nominally Mg-6Al-0.13 Mn (wt. %). Friction-stir passes were made with a translation speed of 1.7 mm/s using tool-rotation speeds of 1,250 rpm or 2,500 rpm. Stir passes with good appearance were obtained under both conditions. In some cases up to five passes were overlapped on a single bar to produce stir zones with cross-sectional dimensions of about 1.5 mm x 10 mm. Metallographic examinations indicated that the stir zones were largely comprised of a magnesium solid solution with equiaxed grains on the order of 5-10 {micro}m in size. Hardness mapping showed that the stir zones experienced increases of 16-25% compared to the as-cast metal. Room-temperature testing showed that, compared to the cast metal, the stir zones had flow stresses nearly 20% higher with about twice the tensile elongation.

  15. Design and evaluation of improved magnetic stir bars for single-mode microwave reactors.

    PubMed

    Obermayer, David; Damm, Markus; Kappe, C Oliver

    2013-08-14

    Magnetic stirring in sealed cylindrical vessels designed for use in single-mode microwave instruments is typically less than optimal, and is not comparable to the efficient agitation that can be generally obtained in a round-bottomed flask fitted with a suitable magnetic stir bar or using overhead mechanical stirring systems. A new "vertical blade" stir bar design that improves the stirring performance in the very narrow, flow-constricting microwave vessels has been developed and evaluated for several different transformations where stirring and efficient agitation are known to be of importance. The better performance of these novel stirrers compared to the traditional cylindrical stir bar design is not only due to the geometry of the stirrer but also to the utilization of a magnetic material with a stronger magnetic transmission force (Sm2Co17) compared to standard ferrite or AlNiCo alloys. For all three tested cases involving solid/liquid, liquid/liquid and highly viscous reaction systems, the new vertical blade stirrers showed a distinctively improved performance resulting in higher conversions and/or product yields. PMID:23797332

  16. Characterization of Multilayered Multipass Friction Stir Weld on ASTM A572 G50 Steel

    DOE PAGESBeta

    Lim, Yong Chae; Sanderson, Samuel; Mahoney, Murray; Yu, Xinghua; Qiao, Dongxiao; Wang, Yanli; Zhang, Wei; Feng, Zhili

    2014-01-01

    A multilayered multipass friction stir weld (MM-FSW) on ASTM A572 Grade 50 steel was characterized to understand its potential application for thick-section structures. The 15-mm-thick section was fabricated by stacking up three steel plates and then friction stir welding the plates together in a total of 5 passes. The unique butt/lap joint configuration encountered in the multilayer weld was examined to understand the effect of tool rotation direction on the joint quality especially the formation of hooking defect. Charpy V-notch impact toughness tests showed generally higher impact toughness energy for the stir zone than the base metal with a ductilemore » fracture mode. The microhardness value was measured from 195 to 220 HV in the stir zone, while the base metal showed an average value of 170 HV. The microstructure in the stir zone and the adjacent heat affected zone was quantified using Optical and Scanning Electron Microscopy (SEM) including Electron Backscatter Diffraction (EBSD). The increased toughness and hardness were correlated with the refined microstructure in stir zone, resulting from severe plastic deformation and subsequent dynamic recrystallization during friction stir welding.« less

  17. Characterization of Multilayered Multipass Friction Stir Weld on ASTM A572 G50 Steel

    SciTech Connect

    Lim, Yong Chae; Sanderson, Samuel; Mahoney, Murray; Yu, Xinghua; Qiao, Dongxiao; Wang, Yanli; Zhang, Wei; Feng, Zhili

    2014-01-01

    A multilayered multipass friction stir weld (MM-FSW) on ASTM A572 Grade 50 steel was characterized to understand its potential application for thick-section structures. The 15-mm-thick section was fabricated by stacking up three steel plates and then friction stir welding the plates together in a total of 5 passes. The unique butt/lap joint configuration encountered in the multilayer weld was examined to understand the effect of tool rotation direction on the joint quality especially the formation of hooking defect. Charpy V-notch impact toughness tests showed generally higher impact toughness energy for the stir zone than the base metal with a ductile fracture mode. The microhardness value was measured from 195 to 220 HV in the stir zone, while the base metal showed an average value of 170 HV. The microstructure in the stir zone and the adjacent heat affected zone was quantified using Optical and Scanning Electron Microscopy (SEM) including Electron Backscatter Diffraction (EBSD). The increased toughness and hardness were correlated with the refined microstructure in stir zone, resulting from severe plastic deformation and subsequent dynamic recrystallization during friction stir welding.

  18. Effects of cutting intensity and stirring speed on syneresis and curd losses during cheese manufacture.

    PubMed

    Everard, C D; O'Callaghan, D J; Mateo, M J; O'Donnell, C P; Castillo, M; Payne, F A

    2008-07-01

    Recombined whole milk was renneted under constant conditions of pH, temperature, and added calcium, and the gel was cut at a constant firmness. The effects of cutting and stirring on syneresis and curd losses to whey were investigated during cheese making using a factorial design with 3 cutting modes designed to provide 3 different cutting intensity levels (i.e., total cutting revolutions), 3 levels of stirring speed, and 3 replications. These cutting intensities and stirring speeds were selected to give a wide range of curd grain sizes and curd shattering, respectively. Both factors affected curd losses, and correct selection of these factors is important in the cheesemaking industry. Decreased cutting intensity and increased stirring speed significantly increased the losses of fines and fat from the curd to the whey. Cutting intensities and stirring speeds in this study did not show significant effects on curd moisture content over the course of syneresis. Levels of total solids, fines, and fat in whey were shown to change significantly during syneresis. It is believed that larger curd particles resulting from low cutting intensities coupled with faster stirring speeds resulted in a higher degree of curd shattering during stirring, which caused significant curd losses. PMID:18565915

  19. Effect of cooling rate on microstructure of friction-stir welded AA1100 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Yi, D.; Mironov, S.; Sato, Y. S.; Kokawa, H.

    2016-06-01

    In this work, the microstructural changes occurring during cooling of friction-stir welded aluminum alloy AA1100 were evaluated. To this end, friction-stir welding (FSW) was performed in a wide range of cooling rates of 20-62 K/s and the evolved microstructures were studied by using electron backscatter diffraction. Below 0.6 Tm (Tm being the melting point), the stir zone material was found to experience no significant changes during cooling. At higher FSW temperatures, however, notable changes occurred in the welded material, including grain growth, sharpening of texture, reduction of the fraction of high-angle boundaries and material softening.

  20. Grain Structure Development During Friction Stir Welding of Single-Crystal Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Jeon, Jong Jin; Mironov, Sergey; Sato, Yutaka S.; Kokawa, Hiroyuki; Park, Seung Hwan C.; Hirano, Satoshi

    2013-07-01

    The high-resolution electron backscatter diffraction (EBSD) technique was used to study the grain boundary development and texture evolution during friction stir welding (FSW) in a single-crystal austenitic stainless steel. Strain-induced crystal rotations were found to be induced by simple shear deformation. With the crystal rotations, the single-crystal structure was broken up into a fine-grained polycrystalline aggregate in the stir zone. This process was deduced to be governed by continuous and discontinuous recrystallizations operating during the FSW process. The final texture which evolved in the stir zone was dominated by A/bar{A}\\{ {111} \\} < 110 rangle ideal simple shear orientations.

  1. Effects of Fusion Tack Welds on Self-Reacting Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Pendleton, M. L.; Brooke, S. A.; Russell, C. K.

    2012-01-01

    In order to know whether fusion tack welds would affect the strength of self-reacting friction stir seam welds in 2195-T87 aluminum alloy, the fracture stresses of 144 tensile test coupons cut from 24 welded panels containing segments of friction stir welds were measured. Each of the panels was welded under unique processing conditions. A measure of the effect of the tack welds for each panel was devised. An analysis of the measures of the tack weld effect supported the hypothesis that fusion tack welds do not affect the strength of self-reacting friction stir welds to a 5% level of confidence.

  2. Some microstructural characterisations in a friction stir welded oxide dispersion strengthened ferritic steel alloy

    NASA Astrophysics Data System (ADS)

    Legendre, F.; Poissonnet, S.; Bonnaillie, P.; Boulanger, L.; Forest, L.

    2009-04-01

    The goal of this study is to characterize microstructure of a friction stir welded oxide dispersion strengthened alloy. The welded material is constituted by two sheets of an yttria-dispersion-strengthened PM 2000 ferritic steel. Different areas of the friction stir welded product were analyzed using field emission gun secondary electron microscopy (FEG-SEM) and electron microprobe whereas nanoindentation was used to evaluate mechanical properties. The observed microstructural evolution, including distribution of the yttria dispersoids, after friction stir welding process is discussed and a correlation between the microstructure and the results of nanoindentation tests is established.

  3. Stability of Y–Ti–O precipitates in friction stir welded nanostructured ferritic alloys

    DOE PAGESBeta

    Yu, Xinghua; Mazumder, B.; Miller, M. K.; David, S. A.; Feng, Z.

    2015-01-19

    Nanostructured ferritic alloys, which have complex microstructures which consist of ultrafine ferritic grains with a dispersion of stable oxide particles and nanoclusters, are promising materials for fuel cladding and structural applications in the next generation nuclear reactor. This paper evaluates microstructure of friction stir welded nanostructured ferritic alloys using electron microscopy and atom probe tomography techniques. Atom probe tomography results revealed that nanoclusters are coarsened and inhomogeneously distributed in the stir zone and thermomechanically affected zone. Three hypotheses on coarsening of nanoclusters are presented. Finally, the hardness difference in different regions of friction stir weld has been explained.

  4. Ultrasonic-assisted friction stir welding on V95AT1 (7075) aluminum alloy

    NASA Astrophysics Data System (ADS)

    Tarasov, S. Yu.; Rubtsov, V. Ye.; Kolubaev, E. A.; Ivanov, A. N.; Fortuna, S. V.; Eliseev, A. A.

    2015-10-01

    Ultrasonic-assisted friction stir butt welding on aluminum alloy V95AT1 (7075) has been carried out. Samples have been characterized using metallography, microhardness and XRD. As shown, ultrasonic treatment during welding provides extra plasticizing of metal and better stirring efficiency. The latter serves for elimination of defects, such as root flaw and grain refining in the stir zone. The stress state in the welded joint is characterized by tensile stress in the direction of the weld seam centerline and compression in the transversal direction. The ultrasonic treatment was shown to increase the compression stress and relieve the tensile one.

  5. Use of Friction Stir Welding and Friction Stir Processing for Advanced Nuclear Fuels and Materials Joining Applications

    SciTech Connect

    J. I. Cole; J. F. Jue

    2006-06-01

    Application of the latest developments in materials technology may greatly aid in the successful pursuit of next generation reactor and transmutation technologies. One such area where significant progress is needed is joining of advanced fuels and materials. Rotary friction welding, also referred to as friction stir welding (FSW), has shown great promise as a method for joining traditionally difficult to join materials such as aluminum alloys. This relatively new technology, first developed in 1991, has more recently been applied to higher melting temperature alloys such as steels, nickel-based and titanium alloys. An overview of the FSW technology is provided and two specific nuclear fuels and materials applications where the technique may be used to overcome limitations of conventional joining technologies are highlighted.

  6. Pregnancy is more dangerous than the pill: A critical analysis of professional responses to the Yaz/Yasmin controversy.

    PubMed

    Geampana, Alina

    2016-10-01

    The fourth and most recent generation of hormones used in oral contraceptives has stirred a significant amount of debate regarding the safety of these compounds. Drospirenone, a new type of synthetic hormone used in popular oral contraceptives Yaz and Yasmin, has been found by epidemiologists to increase the risk of blood clots when compared to the previous generations of pills. North American regulatory bodies have investigated the health risks of drospirenone and concluded that the increased risks do not require pulling the new contraceptive technology off the market. Instead, the FDA and Health Canada along with several medical associations have actively managed the Yaz/Yasmin controversy through official statements and press releases between 2010 and 2014. This study provides an analysis of these documents and how risk information about drospirenone-containing pills has been presented to the public. The analysis addresses a gap in our knowledge about cultural factors that impact contraceptive risk assessment. Prevalent risk models used by professionals are highlighted and examined through the use of critical discourse analysis methods. More specifically, this paper highlights the main strategies used to put drospirenone risks into perspective and classify it as safe. I argue that while risks related to pregnancy and the postpartum period are overly-emphasized, other risks are downplayed through a selection process underscored by normative beliefs about women's bodies and sexuality. Future research needs to address consumer perspectives and bridge the gap between lay and scientific risk/benefit assessment of oral contraceptives. PMID:27522113

  7. Thermal Performance Evaluation of Friction Stir Welded and Bolted Cold Plates with Al/Cu Interface

    NASA Astrophysics Data System (ADS)

    Lakshminarayanan, A. K.; Suresh, M.; Sibi Varshan, M.

    2015-05-01

    An attempt is made to design and fabricate a cold plate with aluminum-copper dissimilar interface joined by friction stir welding. Optimum welding conditions for obtaining sound-quality corner and T joints with an aluminum-copper interface were established. Welded cross sections of the friction stir welded cold plate were analyzed to understand the bonding characteristics. Computational fluid dynamics (CFD) was used to evaluate the fluid-flow characteristics and thermal resistance of friction stir welded cold plate and the resulted are compared with the conventional bolted cold plate configuration. For CFD modeling of a cold plate with a dissimilar interface, a new methodology is proposed. From the CFD analysis and experimental results, it is observed that friction stir welded cold plate offered better thermal performance compared to the bolted cold plate and it is due to the metallurgical bonding at the aluminum-copper interface with the dispersion of copper particles.

  8. Counterrotating-Shoulder Mechanism for Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C., Jr.

    2007-01-01

    A counterrotating-shoulder mechanism has been proposed as an alternative to the mechanism and fixtures used in conventional friction stir welding. The mechanism would internally react most or all of the forces and torques exerted on the workpiece, making it unnecessary to react the forces and torques through massive external fixtures. In conventional friction stir welding, a rotating pin tool is inserted into, and moved along, a weld seam. As the pin tool moves, it stirs together material from the opposite sides of the seam to form the weld. A large axial plunge force must be exerted upon the workpiece through and by the pin tool and a shoulder attached above the pin tool in order to maintain the pressure necessary for the process. The workpiece is secured on top of an anvil, which supports the workpiece against the axial plunge force and against the torque exerted by the pin tool and shoulder. The anvil and associated fixtures must be made heavy (and, therefore, are expensive) to keep the workpiece stationary. In addition, workpiece geometries must be limited to those that can be accommodated by the fixtures. The predecessor of the proposed counterrotating-shoulder mechanism is a second-generation, self-reacting tool, resembling a bobbin, that makes it possible to dispense with the heavy anvil. This tool consists essentially of a rotating pin tool with opposing shoulders. Although the opposing shoulders maintain the necessary pressure without need to externally apply or react a large plunge force, the torque exerted on the workpiece remains unreacted in the absence of a substantial external fixture. Depending on the RPM and the thickness of the workpiece, the torque can be large. The proposed mechanism (see figure) would include a spindle attached to a pin tool with a lower shoulder. The spindle would be coupled via splines to the upper one of three bevel gears in a differential drive. The middle bevel gear would be the power-input gear and would be coupled to the

  9. Ten years of HPV vaccines: State of art and controversies.

    PubMed

    Angioli, Roberto; Lopez, Salvatore; Aloisi, Alessia; Terranova, Corrado; De Cicco, Carlo; Scaletta, Giuseppe; Capriglione, Stella; Miranda, Andrea; Luvero, Daniela; Ricciardi, Roberto; Montera, Roberto; Plotti, Francesco

    2016-06-01

    The human papillomavirus (HPV) represents one of the most common sexually transmitted infections and it has been related to cervical cancer. The HPV vaccines prevent infection with certain species of HPV associated with the development of cervical cancer or genital warts. We carried out a PubMed search up to 2015 evaluating all randomized studies published in literature. This review discusses the current status of HPVs vaccines on the global market, efficacy, safety profiles, controversies and future vaccine developments. Three HPVs vaccines are currently on the global market: bivalent, quadrivalent and ninevalent. Bivalent and quadrivalent vaccines can protect against almost 70% of cervical HPV-related cancerous and precancerous conditions and the ninevalent vaccine, instead, provides a protection against almost 90%. The use of vaccinations raised several controversies in the last years and, currently, is not possible to establish which type of vaccine is most effective, however all of them are safe. PMID:27066937

  10. [Trend in person-situation controversy about personality research].

    PubMed

    Wakabayashi, A

    1993-10-01

    The purpose is to review the trend in "person-situation controversy", and to comment on recent literature and their implications. "Person-situation controversy" is related to whether people do or do not have consistent personality traits. Although the topic is not at all new, it aroused a great deal of interest since the publication of Mischel's (1968) "personality and assessment". Here, we began with Mischel's criticism against the trait approach, then, we discussed two opposite viewpoints of situationism and interactionism. Situationism is the idea that situational variables influence more on the behavior of people than personality traits, while interactionism is the idea that personality traits and situations interact with each other to influence behavior. Furthermore, this article focussed on three conceptual issues, such as consistency, prediction, and meaning of traits. Finally, the reconsideration and evaluation of the two viewpoints were presented from a viewpoint of personality psychology. PMID:8301895

  11. Social controversy belongs in the climate science classroom

    NASA Astrophysics Data System (ADS)

    Walsh, Elizabeth M.; Tsurusaki, Blakely K.

    2014-04-01

    Scientists, educators and stakeholders are grappling with how to best approach climate change education for diverse audiences, a task made difficult due to persistent social controversy. This Perspective examines how sociocultural learning theories can inform the design and implementation of climate change education experiences for learners with varied understandings of and attitudes towards climate change. The literature demonstrates that explicitly addressing learners' social and community experiences, values and knowledge supports understandings of and increased concern about climate change. Science learning environments that situate climate change in its social context can support conceptual understandings, shift attitudes and increase the participation of diverse communities in responding to climate change. Examples are provided of successful programmes that attend to social dimensions and learners' previous experiences, including experiences of social controversy.

  12. Questions raised by the controversy over recovered memories of incest.

    PubMed

    Lief, Harold I

    2003-01-01

    The controversy in the mental health community over recovered memory has been heated. The devastation to families falsely accused of incest has been profound. A fortunate consequence, however, has been the vigorous pursuit of answers to a variety of mind-behavior questions raised by the controversy. In this article I raise some of the important questions and in reply I review and summarize some of the data. Some questions deal with the nature of memory and of unconscious processes, especially the role of implicit memory; the techniques of recovered memory therapy and the evolution of pseudomemories and its relevance to clinical practice; the effects, real and alleged, of trauma; the place of dreams, flashbacks, and repetitive patterns of behavior in the understanding of memory and behavior; and finally, questions dealing with the definition of reality. All of these are important issues for the psychoanalyst. PMID:12866698

  13. Controversial issues in home health care: a roundtable discussion.

    PubMed

    McAllister, J C; Black, B L; Griffin, R E; Smith, J E

    1986-04-01

    Controversial issues in home health care (HHC) were discussed by a panel of four individuals involved in or knowledgeable about HHC. The panel addressed the following issues: reluctance of health professionals to participate in home care, challenges in providing HHC services, assigning responsibility for HHC services, reimbursement considerations in joint-venture arrangements, assuming fiscal responsibility for unreimbursed care, selecting HHC providers, defining patient rights, selecting drug products for home-care patients, competing with community pharmacists, circumvention of pharmacist input in preparation of solutions for home infusion, and the future of HHC. Hospital pharmacists who plan to become involved or are already involved in providing HHC services should become familiar with these controversial issues. PMID:3706341

  14. Understanding the agreements and controversies surrounding childhood psychopharmacology

    PubMed Central

    Parens, Erik; Johnston, Josephine

    2008-01-01

    The number of children in the US taking prescription drugs for emotional and behavioral disturbances is growing dramatically. This growth in the use of psychotropic drugs in pediatric populations has given rise to multiple controversies, ranging from concerns over off-label use and long-term safety to debates about the societal value and cultural meaning of pharmacological treatment of childhood behavioral and emotional disorders. This commentary summarizes the authors' eight main findings from the first of five workshops that seek to understand and produce descriptions of these controversies. The workshop series is convened by The Hastings Center, a bioethics research institute located in Garrison, New York, U.S.A. PMID:18261228

  15. Controversies in the management of primary sclerosing cholangitis.

    PubMed

    Nayagam, Jeremy S; Pereira, Stephen P; Devlin, John; Harrison, Phillip M; Joshi, Deepak

    2016-02-18

    Primary sclerosing cholangitis (PSC) remains a rare but significant disease, which affects mainly young males in association with inflammatory bowel disease. There have been few advances in the understanding of the pathogenesis of the condition and no therapeutics with proven mortality benefit aside from liver transplantation. There remain areas of controversy in the management of PSC which include the differentiation from other cholangiopathies, in particular immunoglobulin G4 related sclerosing cholangitis, the management of dominant biliary strictures, and the role of ursodeoxycholic acid. In addition, the timing of liver transplantation in PSC remains difficult to predict with standard liver severity scores. In this review, we address these controversies and highlight the latest evidence base in the management of PSC. PMID:26925200

  16. Alveolar Osteitis: A Comprehensive Review of Concepts and Controversies

    PubMed Central

    Kolokythas, Antonia; Olech, Eliza; Miloro, Michael

    2010-01-01

    Alveolar osteitis, “dry socket”, remains amongst the most commonly encountered complications following extraction of teeth by general dentists and specialists. A great body of literature is devoted to alveolar osteitis addressing the etiology and pathophysiology of this condition. In addition numerous studies are available discussing methods and techniques to prevent this condition. To this date though great controversy still exists regarding the appropriate terminology used for this condition as well as the actual etiology, pathophysiology, and best methods of prevention and treatment. This article is a comprehensive critical review of the available literature addressing the concepts and controversies surrounding alveolar osteitis. We aim to assist the dental health care professional with patient preparation and management of this commonly encountered postoperative condition should be encountered. PMID:20652078

  17. Self-Reacting Friction Stir Welding for Aluminum Alloy Circumferential Weld Applications

    NASA Technical Reports Server (NTRS)

    Bjorkman, Gerry; Cantrell, Mark; Carter, Robert

    2003-01-01

    Friction stir welding is an innovative weld process that continues to grow in use, in the commercial, defense, and space sectors. It produces high quality and high strength welds in aluminum alloys. The process consists of a rotating weld pin tool that plasticizes material through friction. The plasticized material is welded by applying a high weld forge force through the weld pin tool against the material during pin tool rotation. The high weld forge force is reacted against an anvil and a stout tool structure. A variation of friction stir welding currently being evaluated is self-reacting friction stir welding. Self-reacting friction stir welding incorporates two opposing shoulders on the crown and root sides of the weld joint. In self-reacting friction stir welding, the weld forge force is reacted against the crown shoulder portion of the weld pin tool by the root shoulder. This eliminates the need for a stout tooling structure to react the high weld forge force required in the typical friction stir weld process. Therefore, the self-reacting feature reduces tooling requirements and, therefore, process implementation costs. This makes the process attractive for aluminum alloy circumferential weld applications. To evaluate the application of self-reacting friction stir welding for aluminum alloy circumferential welding, a feasibility study was performed. The study consisted of performing a fourteen-foot diameter aluminum alloy circumferential demonstration weld using typical fusion weld tooling. To accomplish the demonstration weld, weld and tack weld development were performed and fourteen-foot diameter rings were fabricated. Weld development consisted of weld pin tool selection and the generation of a process map and envelope. Tack weld development evaluated gas tungsten arc welding and friction stir welding for tack welding rings together for circumferential welding. As a result of the study, a successful circumferential demonstration weld was produced leading

  18. Effect of processing parameters on the corrosion behaviour of friction stir processed AA 2219 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Surekha, K.; Murty, B. S.; Prasad Rao, K.

    2009-04-01

    The effect of processing parameters (rotation speed and traverse speed) on the corrosion behaviour of friction stir processed high strength precipitation hardenable AA 2219-T87 alloy was investigated. The results indicate that the rotation speed has a major influence in determining the rate of corrosion, which is attributed to the breaking down and dissolution of the intermetallic particles. Corrosion resistance of friction stir processed alloy was studied by potentiodynamic polarization, electrochemical impedance spectroscopy, salt spray and immersion tests.

  19. Stability of Y Ti O Precipitates in Friction Stir Welded Nanostructured Ferritic Alloys

    DOE PAGESBeta

    Yu, Xinghua; Mazumder, Baishakhi; Miller, Michael K; David, Stan A; Feng, Zhili

    2015-01-01

    Nanostructured ferritic alloys (NFAs), which have complex microstructures consisting of ultrafine ferritic grains with a dispersion of stable oxide particles and nanoclusters (NC), are promising materials for fuel cladding and structural applications in the next generation nuclear reactor. This study evaluates microstructure of friction stir welded NFA using electron microscopy and atom probe tomography (APT) techniques. APT results revealed NCs are coarsened and inhomogeneously distributed in the stir zone. Three hypotheses on coarsening of NC are presented.

  20. Chlorine: Undergraduate Research on an Element of Controversy

    NASA Astrophysics Data System (ADS)

    Chang, Hasok

    2009-04-01

    If chemical elements were people, chlorine would be a celebrity. Although intrinsically no more or less important than any other element, chlorine has had a knack of making headlines. The genre of "object biography" has been quite successful in popular science recently. We took this opportunity to write a "biographical" study of chlorine. Chlorine's wide range of interesting controversies is well suited for attracting and maintaining the enthusiasm of the diverse range of students we teach in our department.

  1. Controversies in the antiphospholipid syndrome: can we ever stop warfarin?

    PubMed Central

    Fonseca, Ana G; D'Cruz, David P

    2008-01-01

    Patients with antiphospholipid syndrome are at increased risk for recurrent arterial and venous thrombosis and therefore benefit from long term warfarin therapy. The optimal duration of warfarin therapy after a first venous thromboembolic event is however a matter of some controversy and many questions remain unanswered. After reviewing and analysing the available evidence, we discuss some common scenarios in everyday clinical practice where treatment decisions are difficult. PMID:19014462

  2. Controversies and challenges of vaccination: an interview with Elizabeth Miller.

    PubMed

    Miller, Elizabeth

    2015-01-01

    Although strong evidence exists that the benefits of vaccination by far outweigh potential adverse events, controversy still exists. This has led opponents of vaccination to question its safety, efficacy and necessity. In an interview with Professor Elizabeth Miller, we discuss the continuum of beliefs held by vaccine refusers and hesitators, the resulting health consequences, and ways in which health professionals and industry regulators can help promote transparency to better convey the substantial health benefits of vaccination. PMID:26472230

  3. Controversies in Knee Rehabilitation: Anterior Cruciate Ligament Injury

    PubMed Central

    Failla, Mathew J.; Arundale, Amelia J.H.; Logerstedt, David S.; Snyder-Mackler, Lynn

    2014-01-01

    Controversy in management of athletes exists after anterior cruciate ligament injury and reconstruction. Consensus criteria for evaluating successful outcomes following ACL injury include no re-injury or recurrent giving way, no joint effusion, quadriceps strength symmetry, restored activity level and function, and returning to pre-injury sports. Using these criterions, we will review the success rates of current management strategies after ACL injury and provide recommendations for the counseling of athletes after ACL injury. PMID:25818715

  4. The tidelands oil controversy: The prize and the responsibility

    SciTech Connect

    Hagar, A.V.

    1995-12-31

    This article reviews the legal history of the Tidelands oil controversy in the Santa Barbara Channel of Southern California. A blowout of a well in an offshore platform in 1969 marked the beginning of California`s anti-oil movement. Santa Barbara today is a combination of industrialization and recreation, and like the oil and water that are the lifeblood of these two pursuits, they do not mix.

  5. Monarch butterfly migration in North America: Controversy and conservation.

    PubMed

    Malcolm, S B

    1987-05-01

    The monarch butterfly is the most spectacular example of insect migration known. Monarchs are threatened by the destruction of their over-wintering sites in Mexico, California and elsewhere, and many efforts are being made to conserve these sites. However, a controversial recent suggestion, that some monarch populations may not migrate at all, has jeopardized some of these efforts. This article assesses the evidence for and against the new suggestion. PMID:21227836

  6. Numerical Simulations of Inclusion Behavior in Gas-Stirred Ladles

    NASA Astrophysics Data System (ADS)

    Lou, Wentao; Zhu, Miaoyong

    2013-06-01

    A computation fluid dynamics-population balance model (CFD-PBM) coupled model has been proposed to investigate the bubbly plume flow and inclusion behavior including growth, size distribution, and removal in gas-stirred ladles, and some new and important phenomena and mechanisms were presented. For the bubbly plume flow, a modified k- ɛ model with extra source terms to account for the bubble-induced turbulence was adopted to model the turbulence, and the bubble turbulent dispersion force was taken into account to predict gas volume fraction distribution in the turbulent gas-stirred system. For inclusion behavior, the phenomena of inclusions turbulent random motion, bubbles wake, and slag eye forming on the molten steel surface were considered. In addition, the multiple mechanisms both that promote inclusion growth due to inclusion-inclusion collision caused by turbulent random motion, shear rate in turbulent eddy, and difference inclusion Stokes velocities, and the mechanisms that promote inclusion removal due to bubble-inclusion turbulence random collision, bubble-inclusion turbulent shear collision, bubble-inclusion buoyancy collision, inclusion own floatation near slag-metal interface, bubble wake capture, and wall adhesion were investigated. The importance of different mechanisms and total inclusion removal ratio under different conditions, and the distribution of inclusion number densities in ladle, were discussed and clarified. The results show that at a low gas flow rate, the inclusion growth is mainly attributed to both turbulent shear collision and Stokes collision, which is notably affected by the Stokes collision efficiency, and the inclusion removal is mainly attributed to the bubble-inclusion buoyancy collision and inclusion own floatation near slag-metal interface. At a higher gas flow rate, the inclusions appear as turbulence random motion in bubbly plume zone, and both the inclusion-inclusion and inclusion-bubble turbulent random collisions become

  7. Low-Temperature Friction-Stir Welding of 2024 Aluminum

    NASA Technical Reports Server (NTRS)

    Benavides, S.; Li, Y.; Murr, L. E.; Brown, D.; McClure, J. C.

    1998-01-01

    Solid state friction-stir welding (FSW) has been demonstrated to involve dynamic recrystallization producing ultra-fine, equiaxed grain structures to facilitate superplastic deformation as the welding or joining mechanism. However, the average residual, equiaxed, grain size in the weld zone has ranged from roughly 0.5 micron to slightly more than 10 micron, and the larger weld zone grain sizes have been characterized as residual or static grain growth as a consequence of the temperatures in the weld zone (where center-line temperatures in the FSW of 6061 Al have been shown to be as high as 480C or -0.8 T(sub M) where T(sub M) is the absolute melting temperature)). In addition, the average residual weld zone grain size has been observed to increase near the top of the weld, and to decrease with distance on either side of the weld-zone centerline, an d this corresponds roughly to temperature variations within the weld zone. The residual grain size also generally decreases with decreasing FSW tool rotation speed. These observations are consistent with the general rules for recrystallization where the recrystallized grain size decreases with increasing strain (or deformation) at constant strain rate, or with increasing strain-rate, or with increasing strain rate at constant strain; especially at lower ambient temperatures, (or annealing temperatures). Since the recrystallization temperature also decreases with increasing strain rate, the FSW process is somewhat complicated because the ambient temperature, the frictional heating fraction, and the adiabatic heating fraction )proportional to the product of strain and strain-rate) will all influence both the recrystallization and growth within the FSW zone. Significantly reducing the ambient temperature of the base metal or work pieces to be welded would be expected to reduce the residual weld-zone grain size. The practical consequences of this temperature reduction would be the achievement of low temperature welding. This

  8. Common controversies in total knee replacement surgery: Current evidence

    PubMed Central

    Nikolaou, Vasileios S; Chytas, Dimitrios; Babis, George C

    2014-01-01

    Total knee replacement (TKR) is a widely used operation that has radically improved the quality of life of millions of people during the last few decades. However, some technical details, concerning the surgical procedure and the rehabilitation following total knee arthroplasty, are still a matter of a strong debate. In this review of the literature, we have included the best evidence available of the last decade, in an effort to shed light on some of the most controversial subjects related to TKR surgery. Posterior-stabilized or cruciate-retaining prosthesis? To use a tourniquet during operation or not? Do patients need continuous passive motion for their post-surgery rehabilitation? To resurface patella or not? These are some of the most controversial topics that until now have been persistent dilemmas for the orthopedic surgeon. Results of this systematic review of the literature are highly controversial. These conflicting results are an indication that larger and more well conducted high quality trials are needed in order to gain more secure answers. At the same time, it is becoming apparent that a meticulous operative technique, respecting the soft tissue envelope and knowing the principles of alignment and soft tissue balancing, are some of the parameters that might contribute more to achieving the optimal results for the patients. PMID:25232522

  9. Empowerment in healthcare policy making: three domains of substantive controversy.

    PubMed

    Chiapperino, Luca; Tengland, Per-Anders

    2015-12-01

    This paper distinguishes between the uses of empowerment across different contexts in healthcare policy and health promotion, providing a model for the ethical and political scrutiny of those uses. We argue that the controversies currently engendered by empowerment are better understood by means of a historical distinction between two concepts of empowerment, namely, what we call the radical empowerment approach and the new wave of empowerment. Building on this distinction, we present a research agenda for ethicists and policy makers, highlighting three domains of controversy raised by the new wave of empowerment, namely: (1) the relationship between empowerment and paternalistic interferences on the part of professionals; (2) the evaluative commitment of empowerment strategies to the achievement of health-related goals; and (3) the problems arising from the emphasis on responsibility for health in recent uses of empowerment. Finally, we encourage the explicit theorisation of these moral controversies as a necessary step for the development and implementation of ethically legitimate empowerment processes. PMID:26650538

  10. Embryo stem cell research: ten years of controversy.

    PubMed

    Robertson, John A

    2010-01-01

    This overview of 10 years of stem cell controversy reviews the moral conflict that has made ESCs so controversial and how this conflict plays itself out in the legal realm, focusing on the constitutional status of efforts to ban ESC research or ESC-derived therapies. It provides a history of the federal funding debate from the Carter to the Obama administrations, and the importance of the Raab memo in authorizing federal funding for research with privately derived ESCs despite the Dickey-Wicker ban on federal funding of embryo research. It also reviews the role that scientists themselves have played in developing regulations for ESC research, the emergence of ESCROs as special review bodies for ESC research, and the thorough consent requirements for donation of IVF embryos to ESC research. With research now transitioning from the lab to the clinic, the article reviews the challenges of ensuring safety and consent in translational research. It concludes with a call for respecting those persons who have to using or working with ESC products and an account of how obtaining stem cells from a person's own cells will alleviate some but not all of the controversy surrounding ESC research. PMID:20579242

  11. Strain Rates and Grain Growth in Al 5754 and Al 6061 Friction Stir Spot Welds

    NASA Astrophysics Data System (ADS)

    Gerlich, A.; Yamamoto, M.; North, T. H.

    2007-06-01

    The stir zone temperature and microstructures are compared in friction stir spot welds produced in Al 5754 and Al 6061 alloys. Electron backscattered diffraction was used to determine the relationship between tool rotation speed during welding and final stir zone grain size. Comparison of the grain sizes in rapidly quenched welds with those in air-cooled joints confirmed that grain growth occurred only in Al 6061 spot welds. There was no evidence of abnormal grain growth in the stir zones of Al 6061 welds; the final grain size could be represented using an Arrhenius equation. The strain rates during welding were determined by incorporating the stir zone temperature and average subgrain sizes in quenched spot welds in the Zener-Hollomon relation. When the tool rotation speed increased from 750 to 3000 RPM, the strain rate values ranged from 180 to 497 s-1 in Al 5754 spot welds and from 55 to 395 s-1 in Al 6061 spot welds. It is suggested that a no-slip boundary condition may be appropriate during numerical modeling of Al 5754 and 6061 friction stir spot welding. This is not the case during Al 7075, Al 2024, and Mg-alloy AZ91 spot welding because spontaneous melting facilitates slippage at the tool contact interface.

  12. Friction stir welding of F82H steel for fusion applications

    NASA Astrophysics Data System (ADS)

    Noh, Sanghoon; Ando, Masami; Tanigawa, Hiroyasu; Fujii, Hidetoshi; Kimura, Akihiko

    2016-09-01

    In the present study, friction stir welding was employed to join F82H steels and develop a potential joining technique for a reduced activation ferritic/martensitic steel. The microstructures and mechanical properties on the joint region were investigated to evaluate the applicability of friction stir welding. F82H steel sheets were successfully butt-joined with various welding parameters. In welding conditions, 100 rpm and 100 mm/min, the stirred zone represented a comparable hardness distribution with a base metal. Stirred zone induced by 100 rpm reserved uniformly distributed precipitates and very fine ferritic grains, whereas the base metal showed a typical tempered martensite with precipitates on the prior austenite grain boundary and lath boundary. Although the tensile strength was decreased at 550 °C, the stirred zone treated at 100 rpm showed comparable tensile behavior with base metal up to 500 °C. Therefore, friction stir welding is considered a potential welding method to preserve the precipitates of F82H steel.

  13. Effects of stir-fry cooking with different edible oils on the phytochemical composition of broccoli.

    PubMed

    Moreno, Diego A; López-Berenguer, Carmen; García-Viguera, Cristina

    2007-01-01

    Numerous epidemiological studies indicate that Brassica vegetables in general and broccoli in particular protect humans against cancer; they are rich sources of glucosinolates and possess a high content on flavonoids, vitamins, and mineral nutrients. The contents of total intact glucosinolates, total phenolics, vitamin C, and minerals (potassium, sodium, calcium, magnesium, iron, manganese, zinc, and copper) in the edible portions of freshly harvested broccoli (florets), which was subjected to stir-frying treatments, were evaluated. In the present work, the stir-fry cooking experiments were carried out using different edible oils from plant origin (refined olive oil, extra virgin olive oil, sunflower oil, peanut oil, soyabean oil, and safflower oil) known and used worldwide. Results showed that during stir-frying, phenolics and vitamin C were more affected than glucosinolates and minerals. Stir-fry cooking with extra virgin olive, soybean, peanut, or safflower oil did not reduce the total glucosinolate content of the cooked broccoli compared with that of the uncooked sample. The vitamin C content of broccoli stir-fried with extra virgin olive or sunflower oil was similar to that of the uncooked sample, but greater than those samples stir-fried with other oils. PMID:17995900

  14. Enriched boundary layers for heterogeneous reaction in stirred microfluidic flows

    NASA Astrophysics Data System (ADS)

    Kirtland, Joseph; Stroock, Abraham

    2008-11-01

    The rate of transport of a scalar from a fluid stream to a reactive surface depends on both the character of the flow and the scalar concentration profile incident on the surface. Uniaxial flows tend to form thick regions of low concentration near the reactive surface, leading to decreased rates of scalar transport. For irreversible reactions, this effect can be mitigated through efficient mixing of the bulk. This ensures that the average concentration is incident on the reactive surface, and that concentration boundary layers are kept thin. Coupled reversible reactions, such as those occurring at the electrodes of an electrochemical cell, can complicate the analysis of such a system. In a stirred microfluidic electrochemical cell, depletion of the reactant of the forward reaction implies enrichment of the reactant of the reverse reaction. This enriched fluid can bypass the well mixed bulk, leading to increased scaling of the overall transport process with the Péclet number Pe, even in cases of efficient bulk mixing. We present numerical and experimental results in several such flows and discuss situations where this enrichment can be beneficial (amplification in sensors) or detrimental (quantitative concentration measurement). J. Kirtland, G. McGraw, A. Stroock. Physics of Fluids 18, 073602 (2006).

  15. Chemical pretreatment of coal in a stirred ball mill

    SciTech Connect

    Birlingmair, D.; Burkhart, L.; Tampy, G.; Pollard, J.

    1988-06-01

    Techniques were studied to alter and control the surface chemistry of ultrafine coal and mineral particles during comminution in a stirred ball mill to enhance liberation and subsequent physical separation. Three-phase (kerosene-liquid-solid) contact angle measurements were taken with kerosene as the oil phase; with acidic, basic, neutral, and sodium dithionite solutions constituting the aqueous phase, and organic-rich and mineral-rich fractions of Upper Freeport coal constituting the solid phase. The hydrophobic/hydrophilic effect of the aqueous solutions on the organic-rich and mineral-rich fractions was compared to the results of microbubble froth flotation. Continuous microbubble column flotation experiments were also conducted and the effect of several variables investigated. In general, slow feed rates, high frother concentration and high frit pressure yielded better results. The use of oxone, a peroxygen triple salt, as a chemical reagent during grinding and pretreatment prior to beneficiation, was explored. The acidic surface functional oxygen groups were studied to more fully understand the changes on coal samples affected by chemical pretreatment. 6 refs., 3 figs., 7 tabs.

  16. Isolated thermocouple amplifier system for stirred fixed-bed gasifier

    DOEpatents

    Fasching, George E.

    1992-01-01

    A sensing system is provided for determining the bed temperature profile of the bed of a stirred, fixed-bed gasifier including a plurality of temperature sensors for sensing the bed temperature at different levels, a transmitter for transmitting data based on the outputs of the sensors to a remote operator's station, and a battery-based power supply. The system includes an isolation amplifier system comprising a plurality of isolation amplifier circuits for amplifying the outputs of the individual sensors. The isolation amplifier circuits each comprise an isolation operational amplifier connected to a sensor; a first "flying capacitor" circuit for, in operation, controlling the application of power from the power supply to the isolation amplifier; an output sample and hold circuit connected to the transmitter; a second "flying capacitor" circuit for, in operation, controlling the transfer of the output of the isolation amplifier to the sample and hold circuit; and a timing and control circuit for activating the first and second capacitor circuits in a predetermined timed sequence.

  17. Reexamination of the infrared properties of randomly stirred hydrodynamics

    SciTech Connect

    Berera, A.; Yoffe, S. R.

    2010-12-15

    Dynamic renormalization-group (RG) methods were originally used by Forster, Nelson, and Stephen (FNS) to study the large-scale behavior of randomly stirred incompressible fluids governed by the Navier-Stokes equations. Similar calculations using a variety of methods have been performed but have led to a discrepancy in results. In this paper, we carefully reexamine in d dimensions the approaches used to calculate the renormalized viscosity increment and, by including an additional constraint which is neglected in many procedures, conclude that the original result of FNS is correct. By explicitly using step functions to control the domain of integration, we calculate a nonzero correction caused by boundary terms which cannot be ignored. We then go on to analyze how the noise renormalization, which is absent in many approaches, contributes an O(k{sup 2}) correction to the force autocorrelation and show conditions for this to be taken as a renormalization of the noise coefficient. Following this, we discuss the applicability of this RG procedure to the calculation of the inertial range properties of fluid turbulence.

  18. Lateral stirring of large-scale tracer fields by altimetry

    NASA Astrophysics Data System (ADS)

    Dencausse, Guillaume; Morrow, Rosemary; Rogé, Marine; Fleury, Sara

    2014-01-01

    Ocean surface fronts and filaments have a strong impact on the global ocean circulation and biogeochemistry. Surface Lagrangian advection with time-evolving altimetric geostrophic velocities can be used to simulate the submesoscale front and filament structures in large-scale tracer fields. We study this technique in the Southern Ocean region south of Tasmania, a domain marked by strong meso- to submesoscale features such as the fronts of the Antarctic Circumpolar Current (ACC). Starting with large-scale surface tracer fields that we stir with altimetric velocities, we determine `advected' fields which compare well with high-resolution in situ or satellite tracer data. We find that fine scales are best represented in a statistical sense after an optimal advection time of ˜2 weeks, with enhanced signatures of the ACC fronts and better spectral energy. The technique works best in moderate to high EKE regions where lateral advection dominates. This technique may be used to infer the distribution of unresolved small scales in any physical or biogeochemical surface tracer that is dominated by lateral advection. Submesoscale dynamics also impact the subsurface of the ocean, and the Lagrangian advection at depth shows promising results. Finally, we show that climatological tracer fields computed from the advected large-scale fields display improved fine-scale mean features, such as the ACC fronts, which can be useful in the context of ocean modelling.

  19. Manual adjustable probe tool for friction stir welding

    NASA Technical Reports Server (NTRS)

    Oelgoetz, Peter A. (Inventor); Ding, Jeff (Inventor)

    2000-01-01

    A friction stir welding tool is provided generally comprising three parts: a rotatable welding tool body (22) that has an outer threaded surface (32) and a probe (24) extending from a distal end of the body, a shoulder (26), which has a threaded inner surface (40) and a bore (36) at a distal end of the shoulder, and a jam nut (28), which has a threaded inner surface (42). The shoulder is threaded onto the tool body such that the probe extends from the shoulder through the bore by a preferred length. The jam nut is then threaded onto the tool body to secure the shoulder. The tool is operatively connected to a drive motor for rotating the tool body. The shoulder may include a knife edge projecting from the distal end (38) thereof adjacent the bore. The knife edge inhibits the weld material from migrating along the probe to intrude inside the shoulder, where it may prevent separation of the tool body and the shoulder when readjustment of the tool is necessary.

  20. Friction Stir Welded Thin Wall Cryogenic Tank Skins

    NASA Astrophysics Data System (ADS)

    Potter, David M.; Takeshita, Jennifer A.; Holguin, Michael J.

    2007-01-01

    A cryogenic propellant tank is the common element of trans-planetary transportation systems, in-space storage depots, lunar landers, in-space habitats/laboratories, ascent/descent, and launch vehicles. Lockheed Martin's (LM) cryogenic tank approach integrates Friction Stir Welding (FSW) with thin-gage aluminum monocoque structural design, common spin formed FSW domes and variable tank lengths to tailor the cryogenic tank from smaller stages, such as landers or ascent/descent stages, to very large on-orbit or In Space Resource Utilization (ISRU) storage systems. Thin gage corrosion resistant steel (CRES) construction combined with normal fusion welding as used on LM's Centaur has already been demonstrated to provide the highest cryogenic tank mass fraction (~.90) for large scale, cryogenic propellant storage. However, current fusion welding technology is limited by the alloys that are considered weldable and typically achieves only 50% of the parent material ultimate strength at the weld joint. Preliminary LM technology development indicates that in certain aluminum alloys, the FSW joint retains up to 100% of the parent material ultimate strength at LH2 temperatures. Combining FSW and aluminum monocoque tank design would create a large scale cryogenic tank with a mass fraction in excess of the current industry standard and therefore is ideal for affordable, reliable, high capacity propellant storage required for all facets of space exploration.

  1. Friction Stir Additive Manufacturing: Route to High Structural Performance

    NASA Astrophysics Data System (ADS)

    Palanivel, S.; Sidhar, H.; Mishra, R. S.

    2015-03-01

    Aerospace and automotive industries provide the next big opportunities for additive manufacturing. Currently, the additive industry is confronted with four major challenges that have been identified in this article. These challenges need to be addressed for the additive technologies to march into new frontiers and create additional markets. Specific potential success in the transportation sectors is dependent on the ability to manufacture complicated structures with high performance. Most of the techniques used for metal-based additive manufacturing are fusion based because of their ability to fulfill the computer-aided design to component vision. Although these techniques aid in fabrication of complex shapes, achieving high structural performance is a key problem due to the liquid-solid phase transformation. In this article, friction stir additive manufacturing (FSAM) is shown as a potential solid-state process for attaining high-performance lightweight alloys for simpler geometrical applications. To illustrate FSAM as a high-performance route, manufactured builds of Mg-4Y-3Nd and AA5083 are shown as examples. In the Mg-based alloy, an average hardness of 120 HV was achieved in the built structure and was significantly higher than that of the base material (97 HV). Similarly for the Al-based alloy, compared with the base hardness of 88 HV, the average built hardness was 104 HV. A potential application of FSAM is illustrated by taking an example of a simple stiffener assembly.

  2. New insight into influence of mechanical stirring on membrane fouling of membrane bioreactor: Mixed liquor properties and hydrodynamic conditions.

    PubMed

    Qi, Chao; Wang, Jinnan; Lin, Yaohua

    2016-07-01

    Although membrane bioreactor is widely used in wastewater treatment, the problem of membrane fouling remains to be resolved. This paper focused on the influence of mechanical stirring on membrane fouling. Ammonium removal decreased with viscous bulking when stirring rates slowed down. Trans-membrane pressure increased more rapidly when the stirring rate decreased. The resistance of the gel layer increased significantly under low stirring rates, which indicated that the fouling rates of MBR in different stages were attributed to gel layer variation. The proportion of small particles increased when stirring rates slowed down. Furthermore, 16S rRNA gene amplicon sequencing showed that Proteobacteria and Actinobacteria were dominant in the mixed liquor. The relative abundance of Actinobacteria increased from 41% to 50% in the entire experiment. The computational fluid dynamics model was used to simulate the fluid flow characteristics. The model indicated velocities and directions of the fluid flow changes with different stirring rates. PMID:27058400

  3. CFD simulation of an unbaffled stirred tank reactor driven by a magnetic rod: assessment of turbulence models.

    PubMed

    Li, Jiajia; Deng, Baoqing; Zhang, Bing; Shen, Xiuzhong; Kim, Chang Nyung

    2015-01-01

    A simulation of an unbaffled stirred tank reactor driven by a magnetic stirring rod was carried out in a moving reference frame. The free surface of unbaffled stirred tank was captured by Euler-Euler model coupled with the volume of fluid (VOF) method. The re-normalization group (RNG) k-ɛ model, large eddy simulation (LES) model and detached eddy simulation (DES) model were evaluated for simulating the flow field in the stirred tank. All turbulence models can reproduce the tangential velocity in an unbaffled stirred tank with a rotational speed of 150 rpm, 250 rpm and 400 rpm, respectively. Radial velocity is underpredicted by the three models. LES model and RNG k-ɛ model predict the better tangential velocity and axial velocity, respectively. RNG k-ɛ model is recommended for the simulation of the flow in an unbaffled stirred tank with magnetic rod due to its computational effort. PMID:26465300

  4. Stirring-induced bifurcation driven by the chaotic regime in the Belousov—Zhabotinsky reaction in a CSTR

    NASA Astrophysics Data System (ADS)

    Strizhak, Peter E.

    1995-09-01

    The stirring-induced bifurcation at low stirring rate S 0 = 23 rpm of the reaction volume has been observed for the chaotic regime in the Belousov—Zhabotinsky oscillating chemical reaction (malonic acidbromatecerium(III)sulfuric acid) in a continuously stirred tank reactor in premixing mode. This bifurcation is characterized by a stepwise growth of the macroscopic spatial concentration gradients that is shown by the use of the time dependencies of the potential difference between two platinum electrodes.

  5. Teaching Controversial Topics to Skeptical High School Students

    NASA Astrophysics Data System (ADS)

    Ford, K. S.

    2012-12-01

    Tennessee passes the "Monkey Bill" (HB 0368, SB 0893), North Carolina's state government passes a law to criminalize reference in state documents to scientific models that predict sea level rise to reach at least one meter by the next century, and public concern still lags far behind the scientific community's concern on climate change. The American public and even science teachers across the country seem to have lost faith in the ability of the scientific community to unify a strong message about several important scientific lessons, including global warming in particular. This lack of a unified message has weakened the ability of science teachers to effectively teach the lesson of global warming. For science teachers in strongly conservative areas of the country, it is much easier to omit difficult topics and avoid angering parents and school board members. Teachers who do feel strongly about scientifically proven, yet publically controversial topics CAN teach these topics in conservative areas by confirming students' belief systems by being honest and open about motivations surrounding both sides of controversial topics, and by using vocabulary that avoids triggering negative perceptions about these controversial topics. For true learning and change of preconceived opinion to take place, it is important for students to come to the understanding in their own minds in an open and safe learning environment instead of having the message "preached" to them, which only serves to make them feel unintelligent and defensive if they disagree. This presentation will include lessons learned from a practicing science teacher who works in a community that overwhelmingly disputes the validity of human impacts on climate change.

  6. Agonist treatment in opioid use: advances and controversy.

    PubMed

    Viswanath, Biju; Chand, Prabhat; Benegal, Vivek; Murthy, Pratima

    2012-06-01

    Opioid dependence is a chronic relapsing condition which requires comprehensive care; pharmacological agents form the mainstay of its long term treatment. The two most popular approaches are the harm reduction method using agonists and the complete abstinence method using antagonists. Currently, particularly from the harm minimization perspective and the low feasibility of an abstinence based approach, there is an increasing trend toward agonist treatment. The use of buprenorphine has gained popularity in view of its safety profile and the availability of the buprenorphine-naloxone combination has made it popular as a take-home treatment. This review outlines the pharmacological advances and controversies in this area. PMID:22813654

  7. Cancer stem cell targeted therapy: progress amid controversies

    PubMed Central

    Wang, Tao; Shigdar, Sarah; Gantier, Michael P.; Hou, Yingchun; Wang, Li; Li, Yong; Shamaileh, Hadi Al; Yin, Wang; Zhou, Shu-Feng; Zhao, Xinhan; Duan, Wei

    2015-01-01

    Although cancer stem cells have been well characterized in numerous malignancies, the fundamental characteristics of this group of cells, however, have been challenged by some recent observations: cancer stem cells may not necessary to be rare within tumors; cancer stem cells and non-cancer stem cells may undergo reversible phenotypic changes; and the cancer stem cells phenotype can vary substantially between patients. Here the current status and progresses of cancer stem cells theory is illustrated and via providing a panoramic view of cancer therapy, we addressed the recent controversies regarding the feasibility of cancer stem cells targeted anti-cancer therapy. PMID:26496035

  8. Global challenges, efforts, and controversies in neonatal care.

    PubMed

    St Clair, Nicole E; Batra, Maneesh; Kuzminski, Jacquelyn; Lee, Anne C C; O'Callahan, Cliff

    2014-12-01

    Simple low-cost, evidence-based interventions such as clean delivery practices, immediate warming, umbilical cord care, and neonatal resuscitation could prevent 40% to 70% of newborn deaths globally, but many obstacles preclude the provision of those basic interventions for all newborns, particularly in low-resource regions. Global efforts have led to widespread development of neonatal clinical practice guidelines, training programs, and policies. Because of a shortage of health care resources, standards of care have been redefined to meet the needs of underserved populations. This article provides an overview of the challenges, efforts, and controversies surrounding neonatal health in low-resource settings. PMID:25459772

  9. Beyond Controversies: Sexuality Education for Adolescents in India

    PubMed Central

    Khubchandani, Jagdish; Clark, Jeffrey; Kumar, Raman

    2014-01-01

    Sexuality education for adolescents is one of the most controversial topics in the field of child health. In the past decade, policymakers in India have also struggled with the issue and there has been greater public discourse. However, policymaking and public discussions on adolescent sexuality education are frequently fueled by religious, social, and cultural values, while receiving scant scientific attention. To meet the needs of an expanding young population in India, scientific evidence for best practices must be kept at the core of policymaking in the context of sexuality education for adolescents. PMID:25374847

  10. Controversies in the Management of Traumatic Brain Injury.

    PubMed

    Jinadasa, Sayuri; Boone, M Dustin

    2016-09-01

    Traumatic brain injury (TBI) is a physical insult (a bump, jolt, or blow) to the brain that results in temporary or permanent impairment of normal brain function. TBI describes a heterogeneous group of disorders. The resulting secondary injury, namely brain swelling and its sequelae, is the reason why patients with these vastly different initial insults are homogenously treated. Much of the evidence for the management of TBI is poor or conflicting, and thus definitive guidelines are largely unavailable for clinicians at this time. A substantial portion of this article focuses on discussing the controversies in the management of TBI. PMID:27521198

  11. Controversies in the Management of the Trauma Patient.

    PubMed

    Rodman, Regina E; Kellman, Robert M

    2016-08-01

    Facial trauma is a significant cause of morbidity in the United States. Despite the large volume of trauma surgeries at most academic institutions, there is still controversy regarding management of many traumatic injuries. The literature lacks clear-cut best practices for most fractures. In orbital trauma, there is debate about the optimal timing of repair, preferred biomaterial to be used, and the utility of evaluation afterward with intraoperative computed tomographic scan. In repair of mandible fractures, there is debate regarding open versus closed reduction of subcondylar fractures, or alternatively, endoscopic repair. PMID:27400843

  12. Controversies and Trends in United Kingdom Bunion Surgery.

    PubMed

    Harrison, William D; Walker, Christopher R

    2016-06-01

    Current practice and controversies in UK bunion surgery are discussed. Patients tend to be offered a distally based metatarsal osteotomy, such as a chevron or scarf osteotomy, for mild to moderate symptomatic bunions. Greater deformities are managed with a more extreme scarf, supplemented with a proximal phalangeal osteotomy. A proximal fusion in the form of the Lapidus-type procedure is still reserved for the most severe, hypermobile, or arthritic cases. Minimally invasive techniques for bunions have failed to disseminate into common UK practice. The trends in the United Kingdom regarding litigation, venous thromboembolism, and osteodesis for bunion surgery are also discussed. PMID:27261802

  13. The XY female in sport: the controversy continues.

    PubMed Central

    Hipkin, L J

    1993-01-01

    The summer and winter Olympic Games have been accompanied by much press coverage of the controversy and confusion over sex tests for sportswomen. Much of this has centred on the eligibility of subjects with androgen insensitivity to compete in women's events. The purpose of this paper is to review the process of sex differentiation and its abnormalities, highlighting those conditions in which biologically active testosterone is secreted which might confer an advantage in women's sporting events. Images Figure 1 Figure 2 Figure 6 Figure 7 Figure 8 Figure 9 PMID:8242269

  14. Antidepressant Use During Pregnancy: Current Controversies and Treatment Strategies

    PubMed Central

    Payne, Jennifer L.; Meltzer-Brody, Samantha

    2009-01-01

    The treatment of depression during pregnancy is both a common and complex clinical challenge. The decision to expose the fetus to antidepressant medication during pregnancy must be weighed against the risks of untreated maternal depression to both mother and fetus. Maternal depression during pregnancy has been associated with increased rates of preterm birth and maternal substance use. The safety of antidepressant use during pregnancy appears to be largely reassuring but there remain two areas of controversy including neonatal withdrawal syndrome and primary pulmonary hypertension of the newborn (PPHN). Individualized treatment recommendations based on the patient's history are essential in order to optimize outcomes. PMID:19661762

  15. Breast cancer screening controversies: who, when, why, and how?

    PubMed

    Chetlen, Alison; Mack, Julie; Chan, Tiffany

    2016-01-01

    Mammographic screening is effective in reducing mortality from breast cancer. The issue is not whether mammography is effective, but whether the false positive rate and false negative rates can be reduced. This review will discuss controversies including the reduction in breast cancer mortality, overdiagnosis, the ideal screening candidate, and the optimal imaging modality for breast cancer screening. The article will compare and contrast screening mammography, tomosynthesis, whole-breast screening ultrasound, magnetic resonance imaging, and molecular breast imaging. Though supplemental imaging modalities are being utilized to improve breast cancer diagnosis, mammography still remains the gold standard for breast cancer screening. PMID:26093511

  16. Controversies in water management: Frames and mental models

    SciTech Connect

    Kolkman, M.J. Veen, A. van der Geurts, P.A.T.M.

    2007-10-15

    Controversies in decision and policy-making processes can be analysed using frame reflection and mental model mapping techniques. The purpose of the method presented in this paper is to improve the quality of the information and interpretations available to decision makers, by surfacing and juxtaposing the different frames of decision makers, experts, and special interests groups. The research provides a new method to analyse frames. It defines a frame to consist of perspectives and a mental model, which are in close interaction (through second order learning processes). The mental model acts like a 'filter' through which the problem situation is observed. Five major perspective types guide the construction of meaning out of the information delivered by the mental model, and determine what actors see as their interests. The perspective types are related to an actor's institutional and personal position in the decision making process. The method was applied to a case, in order to test its viability. The case concerns the decision making process and environmental impact assessment procedure for the improvement of dike ring 53 in the Netherlands, which was initiated by the Dutch 'Flood Defences Act 1996'. In this specific case the perspectives and mental models of stakeholders were elicited to explain controversies. The case was analysed with regard to the conflicts emerging between stakeholders, on an individual level. The influence of institutional embedding of individuals on the use of information and the construction of meaning, and the limits of a participatory approach were analysed within the details of controversies that emerged during the case analysis. Complicating factor appeared to be the interaction between national dike safety norms (short term) and local water management problems (long term). Revealed controversies mainly concerned disputes between an organisational and a technical perspective. But also disputes on distribution of responsibilities

  17. Case-Based Teacher Preparation for Teaching Controversial Topics in Middle School

    ERIC Educational Resources Information Center

    Muth, K. Denise; Polizzi, Nicholas C.; Glynn, Shawn M.

    2007-01-01

    Many middle school teachers are not prepared to develop units and lesson plans on controversial topics. In addition, many are not prepared to respond effectively when controversial topics arise unexpectedly during routine lessons. This is a significant problem because controversial topics are arising with increasing frequency in middle school…

  18. Several Controversial Issues on Early Childhood Education and Care in Contemporary Japan.

    ERIC Educational Resources Information Center

    Takeuchi, Michio

    This paper provides an overview of current controversial issues in early childhood education in Japan. One controversy discussed is the increasing emphasis on cognitive development in early childhood programs since World War II, especially the focus on reading and writing; and presents the controversy surrounding the task of learning Japanese and…

  19. Some Personal Perspectives on Controversial Practices in Early Childhood Special Education.

    ERIC Educational Resources Information Center

    Strain, Phillip S.; van den Pol, Richard

    1999-01-01

    This response to McWilliams (EC 623 401) concerning controversial early intervention practices with young children with disabilities recounts the authors' involvement with programs originally considered controversial but now generally accepted. It notes that controversial practices that merit review and study and those that are hopelessly flawed…

  20. Ethylene oxidation chemistry in a well-stirred reactor

    SciTech Connect

    Marinov, N.; Malte, P.

    1994-09-01

    Ethylene is an important intermediate in the combustion of methane, larger aliphatic hydrocarbons, and aromatics. Detailed fuel-lean C{sub 2}H{sub 4}H{sub 2}O/air well-stirred reactor data by Thornton were used to analyze reported combustion chemistry mechanisms and the development of this study`s ethylene oxidation mechanism. The data set had been obtained for the temperature range 1,003 to 1,253 K and ethylene-oxygen equivalence ratio range 0.086 to 0.103, at atmospheric pressure. Mechanisms were derived from reaction sets of Westbrook and Pitz, and Dagaut, Cathonnet and Boettner. Examination of each reported mechanism indicated unusually large kinetic rates for the vinyl decomposition reaction were used in order to obtain agreement with the Thornton data set. An ethylene oxidation model was developed in order to address the mechanistic problems of the previous models. This study`s mechanism well simulated the overall rate of ethylene oxidation and concentration profiles of CO, CO{sub 2}, H{sub 2}, CH{sub 2}O, C{sub 2}H{sub 2}, CH{sub 3}OH, CH{sub 4}, and C{sub 2}H{sub 6}. Successful predictions by the model were dependent on a new high temperature vinyl oxidation reaction route, C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}CHO + O with a branching ratio of 1.19--1.21 at 1,053 K to 1.63--2.47 at 1,253 K. The branching ratio values were dependent upon the extent of fall-off for the C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}O + HCO reaction. 132 refs.